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IMPLANT SURFACE CHARACTERISTICS (MICRODESIGN)

Comprehensive Postgraduate Periodontology Examination Notes

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INTRODUCTION & DEFINITION

• Implant surface characteristics - also referred to as microdesign - encompass the chemical and physical properties of the implant surface that determine the nature of hard and soft tissue responses.
• Key concept (Newman & Carranza 14th ed., Ch.73): "Implant surface characteristics - microtopography - have been shown to influence the healing process positively. Accordingly, modification of implant surface characteristics has been a major area of research interest and development."
• A key element in the reaction of hard and soft tissues to an implant involves the implant's surface characteristics, that is, the chemical and physical properties. [Carranza's Clinical Periodontology, 10th Ed., Ch. 73]
• The synthetic biomaterials used for the construction of dental implants and associated abutments can be classified into metallic, ceramic, and surface-modified (coated, reacted, or ion-implanted) groups. [Misch Implantology 4th Ed.]

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FLOWCHART 1: Overview of Implant Surface Characteristics

IMPLANT SURFACE CHARACTERISTICS
          |
    ______|_______________________________
    |                                    |
SURFACE CHEMISTRY               SURFACE TOPOGRAPHY
(Chemical Composition)          (Physical Properties)
    |                                    |
 - Titanium oxide layer           - Macrogeometry
 - Alloy composition              - Microtopography
 - Surface free energy            - Nanotopography
 - Wettability                    - Roughness (Ra values)
 - Ion exchange at interface      - Peak-to-valley dimensions
          |                                    |
     MODIFICATIONS ACHIEVED BY:
          |
    ______|_______________________________
    |                                    |
ADDITIVE PROCESSES           SUBTRACTIVE PROCESSES
(Add material to surface)    (Remove/alter surface)
    |                                    |
 - Plasma spraying               - Machining (Turned)
 - HA coating                    - Acid etching
 - TiO2 anodizing                - Sandblasting
 - Fluoride incorporation        - Combination (SLA)
 - Growth factor biocoating      - Electropolishing
 - Bisphosphonate coating
 - Antibiotic coating
 - Biomimetic CaP deposition

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1. RATIONALE FOR SURFACE MODIFICATION

• Modifications in surface energy, chemical composition, and surface topography are known to influence cellular activity and tissue responses, leading to enhanced osteogenesis.
• At the molecular level, modified implant surfaces increase adsorption of serum proteins, mineral ions, and cytokines, which subsequently promote cellular migration and attachment.
• Implant surface characteristics can also aid in the retention of a fibrin clot, thus providing a migratory pathway for the differentiating osteogenic cells to reach the implant surface.
• Today, implants are treated with a variety of technologies to modify surface characteristics (microscale or nanoscale) to enhance bone formation. [Newman & Carranza 14th Ed., Ch. 73]
• "Some materials are biocompatible because they do not provoke an immune reaction and are 'passive' toward the tissue-healing process. On the other hand, some materials, as well as various surface characteristics, enhance bone apposition at the implant surface in an osteoconductive manner." [Carranza's 10th Ed., Ch. 73]
• Biomaterial surface chemistry (purity and critical surface tension for wetting), topography (roughness), and type of tissue integration (osseous, fibrous, or mixed) can be correlated with shorter- and longer-term in vivo host responses. [Misch Implantology 4th Ed.]

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2. IMPLANT SURFACE CHEMICAL COMPOSITION

2a. Titanium - The Standard Material

• There have been unsuccessful trials with oral implants made of carbon or hydroxyapatite - their lack of resistance to occlusal forces led to frequent fractures.
• Noble metals or alloys do not resist corrosion and have thus been abandoned.
• Today, most oral implants are made of CP (commercially pure) titanium or titanium alloys.

2b. Mechanism of Biomolecule Adsorption on TiO₂

• Biomolecules (normally appear as folded up structures to hide their insoluble parts) will adhere to the TiO₂ surface after displacing original water molecules.
• Initially attracted by weak van der Waals forces, the high dielectric constant of titanium oxides and the polarizability of the molecules after adsorption lead to high bond strengths considered irreversible when surpassing 30 kcal/mol. [Newman & Carranza 14th Ed., Ch. 73]

2c. Titanium Alloy Concerns

• Ti6Al4V (titanium-aluminum 6%, vanadium 4%) - known to provoke bone resorption as the result of leakage of some toxic components (aluminum and vanadium).
• "The different surface oxides are then argued to be responsible for a 'lesser' quality of osseointegration because of the potential of corrosion products that contain aluminum and vanadium." [Misch Implantology 4th Ed.]

2d. Oxide Layer Behavior In Vivo

• Oxide modification during in vivo exposure has been shown to result in increased titanium oxide layer thickness of up to 200 nm.
• The highest oxide growth area corresponded to a bone marrow site; the lowest growth was associated with titanium in contact with cortical regions of bone.
• Increased levels of calcium and phosphorus were found in the oxide surface layers - indicating an active exchange of ions at the interface. [Misch Implantology 4th Ed.]

2e. CaP-Coated Implants - Long-Term Perspective

Examiner Note: "To date, clinical results with CaP-coated implants have not been encouraging from a long-term perspective."

• For good-quality bone, after 15 years of follow-up, clinical success rates of 99% have been reported for implants with a turned surface.
• Enhanced implant surface characteristics are likely to be most beneficial for more challenging situations, such as poor-quality bone and early and immediate loading. [Newman & Carranza 14th Ed., Ch. 73]

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3. IMPLANT SURFACE FREE ENERGY AND MICROSCOPIC ROUGHNESS

3a. The Bioliquid Interface Concept

• When an implant is brought into bodily tissues, it faces a "bioliquid," an aqueous environment.
• Within milliseconds: water, ions, and small biomolecules are absorbed.
• This absorbed layer might seem to render all surfaces equal. However, the large molecules and cells that subsequently adhere are influenced by the surface characteristics of this pellicle layer.
• The composition and structure of the initial layer are largely determined by the underlying surface.
• Thus, the three-dimensional shape of the molecules will be modified during their adherence to this pellicle layer and will unveil different radicals depending on this metamorphosis. [Newman & Carranza 14th Ed., Ch. 73; Carranza's 10th Ed., Ch. 73]

3b. Surface Free Energy (Wettability)

• Surface free energy, often called "wettability," is an important parameter for these interactions.
• Assessed through the shape of a standardized drop of liquid put on the clean implant surface - the contact angle reveals cohesive vs. adhesive forces.
• A ball-shaped drop reveals low surface free energy.
• High surface energy implants showed a threefold increase in fibroblast adhesion.
• High-energy surfaces (metals, alloys, ceramics) are best suited to achieve cell adhesion.
• Surface tension values of 40 dyne/cm and higher are characteristic of very clean surfaces. [Carranza's 10th Ed.; Misch Implantology 4th Ed.]

3c. Surface Roughness Parameters

• Surface roughness can be measured with a profilometer, a stylus that follows the surface and measures:
  • Ra values: peak-to-valley dimensions (height parameter)
  • Scx values: spacing between irregularities
• "No implant surface is smooth" - even turned (machined) implant surfaces are not truly "smooth." [Carranza's 10th Ed., Ch. 73]

Classification of Implant Surface Roughness (Albrektsson & Wennerberg)

3d. Effects of Surface Roughness on Bone Response

• Roughened implant surfaces speed up the bone apposition.
• In vitro, more prostaglandin E₂ (PGE₂) and transforming growth factor beta (TGF-β₁) are produced on roughened than on smoother surfaces. [Carranza's 10th Ed.]
• Disadvantages of roughened surfaces:
  • Increased ion leakage
  • Increased adherence of macrophages and subsequent bone resorption
  • In vitro adsorption of fibronectin was higher on smooth than on roughened CP titanium surfaces (fibronectin is a glycoprotein that determines subsequent cell adhesion)
• Microtopography also influences the number and morphology of cell adhesion pseudopods and cell orientation.
• Grooves in an implant surface will guide cell migration along their direction.
• Bone growth can enter altered microtopographic features such as pits and porosities with internal dimensions of only a few microns. [Carranza's 10th Ed., Ch. 73]

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4. MODIFICATION PROCESSES

FLOWCHART 2: Classification of Surface Modification Processes

SURFACE MODIFICATION PROCESSES
              |
     _________|_________
     |                  |
ADDITIVE            SUBTRACTIVE
PROCESSES           PROCESSES
     |                  |
  Increases         Removes or
  surface           alters existing
  material          surface
     |                  |
  - HA/CaP coating   - Machining
  - TPS              - Acid etching
  - Anodizing        - Sandblasting
  - Fluoride         - Electropolishing
  - Growth factors   - Combination (SLA)
  - Bisphosphonates
  - Antibiotics
  - Biomimetic HA
     |                  |
  Generally           Changes most
  "ROUGHER"           notable at
  surfaces            MICROSCOPIC level

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4a. ADDITIVE PROCESSES

• Methods include: inorganic mineral coatings, plasma spraying, biocoating with growth factors, fluoride, and particulates or cements containing calcium phosphates, sulfates, or carbonates.
• Additive surface modifications tend to increase the surface texture more than subtractive modifications, resulting in topographically "rougher" implant surfaces.
• Surface roughness can also be increased by oxidation or adding an oxide layer. [Newman & Carranza 14th Ed., Ch. 73]

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i. TITANIUM PLASMA SPRAYED (TPS) SURFACE

• TPS surface demonstrated higher torque resistance than turned or acid-etched/blasted surfaces because the roughness creates greater mechanical interlocking.
• Disadvantage: High surface complexity makes decontamination very challenging in peri-implantitis.
• In peri-implantitis treatment (Roccuzzo et al., 2011): reduction of PPD and BoP was less pronounced at TPS surface than SLA. [Newman & Carranza 14th Ed.; Carranza's 10th Ed.; Clinical Periodontology and Implant Dentistry 6th Ed.]

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ii. HYDROXYAPATITE (HA) COATING

• HA coating by plasma spraying was brought to the dental profession by deGroot.
• Block et al. and Thomas et al. showed accelerated bone formation and maturation around HA-coated implants in dogs.
• HA coating can also reduce the corrosion rate of substrate alloys.
• The bone adjacent to HA-coated implants has been reported to be better organized and with a higher degree of mineralization.
• HA-bone attachment is superior to the HA-implant interface - a significant concern.
• Implants of solid sintered HA have been shown to be susceptible to fatigue failure.

Controversies: "Some authors caution that HA coatings do not necessarily represent an advantage for the long-term prognosis of the system." Bacterial microleakage between the HA layer and titanium has been reported to cause accelerated bone loss.

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iii. ANODIZED SURFACE (TiO₂ Modification)

• Another line of research used increased or modified titanium oxide (TiO₂) layers to enhance or accelerate bone formation.
• Achieved by anodizing or chemical processing.
• The oxide content of the TiO₂ layer is essential for nucleation processes to form calcium phosphate precipitates, which lead to mineralized bone formation.
• TiUnite (Nobel Biocare): Electrochemical process that thickens and roughens the titanium oxide layer. Even minute pores allow bone deposition - pore sizes reach a few microns only. Apatite crystal deposition is evident in the oxide layer. [Carranza's 10th Ed., Ch. 73; Misch Implantology 4th Ed.]

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iv. FLUORIDE INCORPORATION

• Fluoride ions can be displaced by oxygen originating from phosphates, thus achieving a covalent binding between bone and implant surface.
• Fluoride release is also known to inhibit the adhesion of proteoglycans and glycoproteins on the hydroxyapatite surface - two macromolecules known to inhibit mineralization. [Carranza's 10th Ed., Ch. 73]

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v. BIOACTIVE / PHARMACOLOGIC COATINGS (Misch 4th Ed.)

• Nanometer-thin fibrinogen coating containing minimal amounts of bisphosphonates.
• Improved early implant fixation - effect maintained at 5 years after prosthetic loading.
• Reduced marginal bone resorption observed.
• Mechanism: Bisphosphonates inhibit resorption and renewal of bone mediated by osteoclasts, retaining existing bone.
• Concern: Old bone becomes brittle, creating a nonideal local environment for increased BIC.

• Simvastatin induces expression of BMP-2 mRNA that promotes bone formation.
• Topical application of statins increased bone formation and concurrently suppressed osteoclast activity.

• Gentamycin, along with HA layer, can be coated onto the implant surface as a local prophylactic agent.
• Tetracycline enhances blood clot attachment and retention on the implant surface during the initial phase of the healing process, promoting osseointegration.

• Collagen with chondroitin sulfate: slightly higher BIC values than reference implant at 2 weeks.

• Purpose: to diminish the initial inflammatory response after implant placement and encourage rapid bone growth.
• Growth factors and fragments of the organic matrix of bone are used.

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4b. SUBTRACTIVE PROCESSES

• Methods: machining, acid etching, blasting, or a combination of these processes.
• Enhance the amount or speed of osseointegration.
• Changes are most notable at the microscopic level. [Newman & Carranza 14th Ed., Ch. 73]

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i. MACHINED/TURNED SURFACE

• Proponents argue that machined surface is the most conducive to cell attachment.
• "Even turned, or machined, implant surfaces are not 'smooth.'" (SEM view confirms this) [Carranza's 10th Ed.; Misch Implantology 4th Ed.]

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ii. ACID ETCHING

• Etching with strong acids increases the surface roughness and the surface area of titanium implants.
• Implants treated with solution of nitric and hydrofluoric acids to chemically alter the surface and eliminate some types of contaminant products.
• The acids rapidly attack metals other than titanium - electrochemical in nature.
• Thought to promote favorable cellular responses and increased bone formation in close proximity to the surface.
• BIOMET 3i OSSEOTITE and NanoTite - commercially available acid-etched systems. [Newman & Carranza 14th Ed.; Misch Implantology 4th Ed.]

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iii. SANDBLASTING (PARTICLE BLASTING)

• Particles projected through a nozzle at high velocity onto the implant.
• Materials used: titanium dioxide, aluminum dioxide, HA.
• Provides irregular rough surfacing with <10 μm scales and a potential for impurity inclusions.
• DENTSPLY Implants ASTRA TECH TiOblast, Zimmer Dental MTX. [Misch Implantology 4th Ed.]

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iv. SANDBLASTED, LARGE GRIT, ACID ETCHED (SLA) SURFACE

Examiner Keyword: SLA = Sandblasted, Large grit, Acid-Etched

• "When the surface roughness is microscopic, such as that achieved with an acid-etched or blasted implant, the bone adaptation to the microtopography will increase the shear strength needed to fracture the bone from the surface to a level that is greater than a turned surface but less than a plasma-sprayed surface." [Carranza's 10th Ed., Ch. 73]
• In peri-implantitis treatment: reduction of PPD and BoP was more pronounced at the implants with the SLA surface than those with the TPS surface (Roccuzzo et al., 2011).

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v. SLActive SURFACE (CHEMICALLY MODIFIED SLA)

Recent Terminology: SLActive = Chemically modified SLA surface (hydrophilic modification)

• Modification of SLA surface to improve hydrophilicity/wettability.
• Clinical studies (Straumann) show that resonance frequency analysis (RFA) values for SLActive implants ranged 58–67 immediately after placement.
• At late healing, RFA values reached 76–80 for both SLA and SLActive implants. [Clinical Periodontology and Implant Dentistry 6th Ed.]

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vi. ELECTROPOLISHING

• Used to reduce surface roughness to only the 0.1 μm scale by controlled removal of the surface layer by dissolution.
• Employed for titanium alloy Ti-6Al-4V to improve mechanical properties. [Misch Implantology 4th Ed.]

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vii. LASER ABLATION

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5. CLASSIFICATION OF IMPLANT SURFACES BY SURFACE CHARACTERISTICS

"Based on surface characteristics, implants are classified into:

1. Titanium plasma sprayed coating
2. Sandblasting surface etching
3. Laser-induced surface roughening
4. Hydroxyapatite coating"

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6. COMPREHENSIVE TABLE: IMPLANT SURFACE TYPES

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7. SURFACE TOPOGRAPHY LEVELS: MACRO, MICRO, AND NANO

FLOWCHART 3: Levels of Surface Topography

IMPLANT SURFACE TOPOGRAPHY
         |
    _____|__________________________
    |            |                 |
MACRO-       MICRO-            NANO-
TOPOGRAPHY   TOPOGRAPHY        TOPOGRAPHY
(>100 μm)    (1–100 μm)        (<1 μm / nanometer)
    |            |                 |
Thread        Pits, grooves,    Crystal-level
design,       surface           features
implant       roughness (Ra),   Nanotube arrays
shape,        peaks-valleys     Ion substitution
diameter      Achieved by:      Governs initial
              SLA, TPS,         protein
              acid etch,        adsorption
              sandblast         (fibronectin,
                                vitronectin)

• "Advancing dental implant surface technology - from micron- to nanotopography" - Mendonca et al., 2008 [referenced in Newman & Carranza 14th Ed.]
• Nanoroughness influences initial protein adsorption that determines subsequent cell adhesion. [Newman & Carranza 14th Ed.]

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8. SURFACE CLEANLINESS, CONTAMINATION & STERILIZATION

8a. Definition of a Clean Surface

• "A clean surface is an atomically clean surface with no other elements than the biomaterial constituents."
• Contaminants can be: particulates, continuous films (e.g., oil, fingerprints), and atomic impurities or molecular layers caused by the thermodynamic instability of surfaces.
• High-energy surfaces (metals, oxides, ceramics) usually tend to bind more to contamination monolayers than polymers and carbon.

8b. Historical Context

• In the earlier times of dental implantology, no specific protocol for surface preparation, cleaning, sterilization, and handling of implants was established.
• Researchers demonstrated adverse host responses caused by:
  • Faulty preparation and sterilization
  • Omission to eliminate adsorbed gases
  • Organic and inorganic debris
• According to Albrektsson: "Implants that seem functional may fail even after years of function, and the cause may be attributed to improper ultrasonic cleaning, sterilization, or handling during the surgical placement."

8c. Carbon Contamination

• Lausmaa et al. showed that titanium implants had large variations in carbon contamination loads (20%–60%) in the 0.3- to 1-nm thickness range, attributed to air exposure and residues from cleaning solvents and lubricants used during fabrication.
• Trace amounts of Ca, P, N, Si, S, Cl, and Na were noted:
  • Fluorine: from passivation and etching treatments
  • Ca, Na, Cl: from autoclaving
  • Si: from sand and glass-beading processes

8d. Sterilization Methods and Effects

• RFGDT + UV-sterilized implants showed rapid bone ingrowth and maturation.
• Steam-sterilized implants seemed to favor thick collagen fibers at the surface.
• Gamma radiation: ceramics can be discolored and polymers degraded by gamma radiation exposures.

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9. CELLULAR PHENOMENA AT IMPLANT–BONE INTERFACE DURING HEALING

FLOWCHART 4: Cellular Events at Implant Surface Over Time

IMPLANT PLACEMENT
       |
       ↓ IMMEDIATE (0 hr)
SERUM ADSORPTION
• Protein adsorption (fibronectin, vitronectin, albumin)
• Lipids, sugars, mineral ions absorbed to surface
       |
       ↓ 0–3 DAYS
MESENCHYMAL CELL RECRUITMENT
• Cell attachment & Proliferation
• Surface modification of adsorbed layer by cells
       |
       ↓ 3–6 DAYS
OSTEOBLAST DIFFERENTIATION & OSTEOID PRODUCTION
• Matrix vesicle production
• Matrix production
       |
       ↓ 6–21 DAYS
MATRIX VESICLE MATURATION & CALCIFICATION
• Matrix calcification
• Mineral ion incorporation
       |
       ↓ >21 DAYS
BONE REMODELING
• Woven bone → Lamellar bone
• Remodeling by osteoclasts and osteoblasts

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10. SURFACE ROUGHNESS AND PERI-IMPLANTITIS RISK

Critical Examiner Point: Surface roughness is a double-edged sword - while it enhances osseointegration, rough surfaces carry a higher risk of peri-implantitis progression and are harder to decontaminate.

Evidence from Animal Studies:

• Compared implants with smooth, polished surface vs. roughened SLA surface.
• After 5 months following ligature removal: bone loss had progressed more and inflammatory lesion in connective tissue was larger at implants with the rough than with the smooth surface.
• "The progression of peri-implantitis, if left untreated, is more pronounced at implants with a moderately rough surface than at implants with a polished surface."

• Compared commercially available implants with SLA, TiOblast, TiUnite, and turned surfaces.
• Spontaneous progression of peri-implantitis occurred with all implant types during 6-month period.
• All specimens presented with large inflammatory lesions that extended apical of the pocket epithelium.
• Osteoclasts in large numbers were detected on the surface of crestal bone.

• Compared turned vs. TiUnite surfaces.
• Significantly larger amount of bone loss occurred around implants with the modified surface than around implants with the turned surface.

• Modified surface implants showed significantly larger bone loss following ligature removal than turned surface implants and teeth.

In Peri-Implantitis Treatment:

• "Macrogeometry threads and microtopography surface characteristics make implant surfaces very challenging to decontaminate." [Newman & Carranza 14th Ed., Ch. 73]

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11. SURFACE CHARACTERISTICS AND HARD TISSUE INTERFACE

• Material properties, surface free energy, and roughness profile are determining factors that influence bone apposition.
• Altered implant surface topographies (acid etching, blasting, combinations, or increasing titanium oxide layer) appear to result in greater bone apposition compared to a turned or machined surface.
• The percentage of implant surface that actually contacts mineralized trabeculae varies greatly depending on bone type at implantation site and type of implant surface.
• Some implant surfaces may have an exponential bone apposition to stabilize after some time; others demonstrate a linear increase over months. [Carranza's 10th Ed., Ch. 73]

Strength of Bone-Implant Interface - Comparative

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12. SOFT TISSUE INTERFACE AND SURFACE CHARACTERISTICS

• For two decades, research focused almost exclusively on the bone-to-implant interface, and the overlying soft tissues were largely unexplored.
• The original Brånemark system implants had turned (machined) surfaces - which are less likely to be associated with soft tissue inflammatory problems.
• Today there is greater interest in peri-implant soft tissues and the soft tissue-to-implant interface as a function of esthetics and maintenance of a seal or barrier against microbial invasion.
• Ultrastructural examination: epithelial cells attach to implant surface with basal lamina and hemidesmosomes. [Newman & Carranza 14th Ed., Ch. 73; Carranza's 10th Ed., Ch. 73]

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13. IMPORTANT RECENT TERMINOLOGY CHANGES

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14. COMPARISON TABLE: DIFFERENT REFERENCES ON KEY TOPICS

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15. SUMMARY OF KEY EXAMINER KEYWORDS

• Microdesign - term for implant surface characteristics
• Microtopography / Nanotopography - levels of surface texture
• Ra value - surface roughness parameter (peak-to-valley)
• Scx value - spacing between surface irregularities
• Additive vs. Subtractive processes - classification of surface modification
• SLA (Sandblasted, Large grit, Acid Etched) - most studied surface
• SLActive - chemically modified (hydrophilic) SLA
• TPS (Titanium Plasma Sprayed) - roughest conventional surface
• Osseointegration - direct structural and functional connection between bone and implant WITHOUT intervening soft tissue
• Bioliquid environment - immediate contact medium for implant surface
• Surface free energy / Wettability / Contact angle - measures of surface-liquid interaction
• Pellicle layer - initial adsorbed layer whose composition is determined by the underlying surface
• Van der Waals forces - initial weak attractive forces for biomolecule adsorption
• PGE₂ and TGF-β₁ - more produced on roughened surfaces
• Fibronectin - glycoprotein; higher adsorption on SMOOTH than roughened surfaces
• Hydroxyapatite-bone vs. HA-implant interface - HA-bone attachment is superior
• Re-osseointegration - de novo bone formation and de novo osseointegration to implant portion that suffered bone loss during peri-implantitis
• RFGDT (Radio Frequency Glow Discharge Treatment) - sterilization that improves surface wettability
• Gamma radiation >2.5 Mrad - standard sterilization for metallic implant systems
• Decontamination challenge - macrogeometry and microtopography make implant surfaces very challenging to decontaminate (relevant in peri-implantitis)
• BIC (Bone-Implant Contact) - quantitative measure of osseointegration success

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16. EXAMINER'S QUICK-REFERENCE: CLINICAL SIGNIFICANCE OF SURFACE CHARACTERISTICS

CLINICAL IMPLICATIONS OF SURFACE CHARACTERISTICS
               |
    ___________|______________________________________________
    |                    |                                   |
PRIMARY             PERI-IMPLANT             DECONTAMINATION
OSSEOINTEGRATION    MAINTENANCE              CHALLENGE
    |                    |                                   |
Roughened surface   Rough surfaces =        Macrogeometry +
speeds up bone      MORE peri-implantitis   Microtopography =
apposition          progression if untreated VERY challenging
(PGE₂, TGF-β₁)     vs. smooth/turned       to decontaminate
    |                    |                                   |
Most beneficial      Turned surface =        Relevant to
in poor quality     best post-surgical       peri-implantitis
bone (D3, D4)       bone gain response       management
and early/          and inflammation         (surgical approach
immediate           resolution              often needed)
loading

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1. Newman MG, Takei HH, Klokkevold PR, Carranza FA. Newman and Carranza's Clinical Periodontology and Implantology, 14th Edition. Chapter 73: Peri-Implant Anatomy, Biology, and Function.
2. Newman MG, Takei HH, Carranza FA. Carranza's Clinical Periodontology, 10th Edition. Chapter 73: Implant Surface Characteristics (Microdesign); Chapter 76: Standard Implant Surgical Procedures.
3. Lang NP, Lindhe J. Clinical Periodontology and Implant Dentistry, 6th Edition. Chapter 26: Peri-Implantitis; Chapter 51: Sinus Elevation Procedures.
4. Misch CE. Dental Implant Prosthetics / Misch Implantology, 4th Edition. Chapter 5: Biomaterials for Dental Implants; Chapter 9: Dental Implant Surfaces.
5. Reddy S. Essentials of Clinical Periodontology and Periodontics. Chapter 47: Dental Implants - Periodontal Considerations.

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IMPLANT SURFACE CHARACTERISTICS (MICRODESIGN)

Continuation of Comprehensive Postgraduate Examination Notes

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17. NANOTECHNOLOGY AND NANOTOPOGRAPHY IN IMPLANT SURFACES

• "Structural features in the extracellular matrix are on the nanometer scale, and it is thought that biomaterials that mimic this environment might more effectively promote the processes of bone regeneration."
• As nanotechnology advances, nanoscale surfaces have been introduced in dentistry.
• Nanotechnology involves materials with a surface roughness range between 1 and 100 nm, which are thought to influence:
  • The adsorption of proteins
  • The adhesion of osteoblastic cells
  • The rate of osseointegration [Misch Implantology 4th Ed.]

Biological Rationale for Nanotopography

• Submicron scale features (<1 μm with undercuts) allow the deposition of bone matrix.
• Micron scale surface features (<10 μm) mimic a single osteoclast resorption pit.
• Macroscale cavities (>10 μm) are similar to resorption activity of one or more osteoclasts.
• "As with natural bone, osteoblasts find these surface irregularities and begin depositing matrix in and around them to form bone."
• Bone cell migration and bone formation on titanium implant surfaces are also thought to be related to the similarity between the microroughness of the surface and the pit irregularities found in natural bone surfaces resulting from osteoclast activity. [Misch Implantology 4th Ed.]

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18. ROUGHNESS CLASSIFICATION TABLE (Wennerberg/Albrektsson - as cited in Misch 4th Ed., Table 9.1)

Examiner Note: Sa value is used as the roughness parameter in Misch's classification (3D equivalent of Ra).

• "Wennerberg's recommended range of roughness" for implant surfaces: Sa of approximately 1.49 μm (moderately rough category).
• Resorbable Blast Media (RBM) treated implants with HA as blast media produce a surface in the moderately rough category with an Sa of 1.49. [Misch Implantology 4th Ed.]

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19. EFFECT OF BLAST PARTICLE SIZE ON SURFACE ROUGHNESS

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20. ETCHING WITH ACID (SUBTRACTIVE) - DETAILED

• Acid treatment of a titanium implant removes the surface oxide and any contamination, resulting in a clean and homogenous surface.
• The acids used include: hydrochloric acid, sulfuric acid, and others.
• "These modifications can be divided into subtractive and additive processes, depending on whether material is removed or deposited on the implant surface."
• Pits, grooves, and protrusions characterize the microtopography and contribute to an increase in surface area.
• Studies have shown increased levels of bone-to-implant contact (BIC) for microrough surfaces.
• Treatment performed with machined surface requires a longer healing time (original Brånemark protocol: 3 to 6 months before loading). [Misch Implantology 4th Ed.]

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21. TREATMENT WITH LASERS (SUBTRACTIVE) - DETAILED

• Lasers can modify implant surfaces by using an ablation technique.
• During laser ablation, the substrate material vaporizes and forms a crater. Depending on material properties, a resolidified material forms a rim along the periphery of the crater.
• Results of laser ablation:
  • Titanium surface microstructures with increased hardness
  • Increased corrosion resistance
  • Increased purity
  • Standard roughness with a thicker oxide layer
• Biological studies showed the potential of the surface to orient osteoblast cell attachment and control the direction of ingrowth. [Misch Implantology 4th Ed.]

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22. RESORBABLE BLAST MEDIA (RBM) SURFACE

• RBM surface treatment uses hydroxyapatite (HA) as the blast media.
• Advantage over aluminum oxide blasting: Any particles remaining on the surface are resorbable and do not affect healing.
• HA is also a component of bone; thus blasting with HA is not only biocompatible and resorbable but also osteoinductive.
• Commercial example: Hahn Tapered Implants. [Misch Implantology 4th Ed., Table 9.3]

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23. COMPREHENSIVE TABLE: IMPLANT SURFACE SYSTEMS COMMERCIALLY AVAILABLE

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24. BIOLOGICAL RESPONSES AND INTERACTION WITH THE IMPLANT SURFACE

Stages of Osseointegration (Three Stages of Repair)

IMPLANT PLACEMENT INTO OSTEOTOMY
              |
              ↓ STAGE 1
INITIAL FORMATION OF BLOOD CLOT
• Blood components interact with dental implant surface
• Adsorption of plasma proteins (fibrin) onto surface
              |
              ↓ STAGE 2
CELLULAR ACTIVATION
• Migration of bone cells through fibrin clot
• Ability of surface to RETAIN fibrin during wound contraction
  is CRITICAL in determining whether migrating cells reach implant
              |
              ↓ STAGE 3
CELLULAR RESPONSE
• Bone cells reach implant surface via migration through fibrin
  and early structural matrix proteins
• Bone laid down directly on implant surface
• Moderately rough and rough surfaces promote this activity
  by: providing surface features with which fibrin can become
  entangled and increasing available surface area for fibrin attachment
              |
              ↓
IMPROVED BIC (Bone-Implant Contact) → OSSEOINTEGRATION

• "Microroughness on implant surfaces helps in retention of the fibrin clot. This in turn enables the migration of bone progenitor cells that deposit bone in close proximity to the implant, improving the BIC. Pits on the implant surface mimic naturally occurring osteoclastic activity and lead osteoblasts to deposit bone on the surface of the implant, leading to improved osseointegration." [Misch Implantology 4th Ed.]

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25. SURFACE ROUGHNESS AND BIOFILM FORMATION (PERI-IMPLANT DISEASE LINK)

• "Biofilm formation is directly proportional to surface roughness; the greater the roughness, the higher the rate of biofilm formation is around the implants."
• The wettability and surface free energy (SFE) of a specific surface also influence biofilm formation on implants.

Surface Properties that Reduce Bacterial Adhesion:

1. Negatively charged surfaces
2. Super-hydrophobic surfaces
3. Super-hydrophilic surfaces
4. Nanometer-scale surface roughness

Critical Point: "The presence of an acquired pellicle-containing host and bacterially derived proteins poses a great challenge to the control of bacterial adhesion and biofilm formation based on surface modifications."

---

26. SURFACE ENERGY: PASSIVATION, CHEMICAL CLEANING, AND CONTACT ANGLE

Passivation and Chemical Cleaning Standards

• ASTM International (ASTM B600, ASTM F-86) specifications for final surface treatment of surgical titanium implants require:
  • Pickling and descaling with molten alkaline base salts
  • Followed by treatment with nitric or hydrofluoric acid to decrease and eliminate contaminants such as iron.
• Iron or other elements may contaminate the implant surface as a result of the machining process and can have an effect of demineralizing the bone matrix.

Contact Angle and Contamination

• "A shift in contact angle (increase) is related to the contamination of the surface by hydrophobic contaminants and decreases the surface tension parameters."
• "The wetting of the surface by blood at the time of placement can be a good indication of the high surface energy of the implant."
• Contact angles are greatly modified by acid treatment or water rinsing.
• "A general rule has been that cleaner is better." [Misch Implantology 4th Ed.]

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27. STERILIZATION AND SURFACE INTEGRITY

• "Manipulation with bare fingers or powdered gloves, tap water, and residual vapors" are potential sources of surface contamination that should be strictly avoided.
• Carbon contamination (20%–60%) found in 0.3–1 nm range on titanium implant surfaces due to air exposure and cleaning solvent/lubricant residues (Lausmaa et al.).

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28. CALCIUM PHOSPHATE (CaP) CERAMICS - DETAILED PROPERTIES

CaP Biomaterial Advantages:

1. Chemical compositions of high purity and of substances similar to constituents of normal biological tissue (calcium, phosphorus, oxygen, hydrogen)
2. Excellent biocompatibility profiles
3. Osteoconductive - the mineralized structure resembles bone mineral phase Ca₅(PO₄)₃OH
4. CaP coatings are nonconductors of heat and electricity - a relative benefit for coated implants
5. Off-white color - considered advantageous

Effect of Crystallinity on HA Resorption Rate:

• "In general, the less crystalline the material, the faster its resorption rate."
• pH effect: As pH decreases (chronic inflammation or infection), CaPO₄ resorbs by a solution-mediated process (becomes chemically unstable). [Misch Implantology 4th Ed.]

---

29. ZIRCONIA IMPLANTS AND SURFACE CHARACTERISTICS

Surface Modification of Zirconia:

• Surface modifications of zirconia implants such as sandblasting and acid etching trigger tetragonal-to-monoclinic (t → m) phase transformation.
• This transformation is associated with 3% to 4% phase volume expansion and induces compressive stresses that shield the crack tip from the applied stress.
• This unique characteristic is known as transformation toughening.
• Concern: The surface flaws introduced by sandblasting and acid etching act as stress concentrators and may become potential sites for crack initiation and propagation, causing strength degradation and the possibility of implant fracture. [Misch Implantology 4th Ed.]

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30. GROWTH FACTORS AND BIOLOGICALLY ACTIVE PEPTIDES AS SURFACE COATINGS

Four Growth Factors with Potential Use in Implantology:

• PDGF-B: "Chang and colleagues have demonstrated that PDGF stimulates osseointegration of dental implants in vivo." However, isolated recombinant PDGF may also affect bone formation adversely.
• BMP-2: Often used in bone-implant interaction studies. High doses of BMP-2 have been associated with localized and temporary bone impairment or increased bone resorption caused by stimulation of osteoclast formation. However, once levels drop, normal bone formation is observed.
• BMPs can be delivered via absorbable collagen sponge to augment bone ridge before implant placement, or via implants with porous structures coated with rhBMP-2.
• rhBMPs are costly, have a high dose requirement (several micrograms to milligrams), and have a poor distribution profile.
• Clinically, platelet-rich plasma (PRP) or platelet-fibrin clot is the equivalent of pure PDGF usage.

Usage of Biologically Active Peptides:

• Fibronectin (protein of extracellular bone matrix): stimulated osteoblastic differentiation and tissue mineralization and contributed to strong osseointegration of implants in experimental models in vivo.
• Common problems: Increased cost of implants, complications with usage, and preservation of bioactive material before implantation; concerns about rate and area of release into surrounding tissues. [Misch Implantology 4th Ed.]

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31. HYDROPHILIC vs. HYDROPHOBIC IMPLANT SURFACE INTERFACE - EARLY OSSEOINTEGRATION

• Bosshardt et al. (2011): Studied the role of bone debris in early healing adjacent to hydrophilic and hydrophobic implant surfaces in man.
• Lang et al. (2011): Studied early osseointegration to hydrophilic and hydrophobic implant surfaces in humans.
• Donos et al. (2011): Investigated gene expression profile of osseointegration of a hydrophilic compared to a hydrophobic microrough implant surface.
• The SLActive (hydrophilic) surface represents the application of this principle commercially, demonstrating accelerated osseointegration compared to conventional SLA. [Clinical Periodontology and Implant Dentistry 6th Ed.]

---

32. CLINICAL SIGNIFICANCE OF ALTERED MICROTOPOGRAPHY

• "Over the past decade there has been great interest in implant surface modifications that alter the surface characteristics at the microscopic level (i.e., altered microtopography)."
• Subtractive implant surface modifications such as blasting (e.g., RBM, Lifecore), acid etching (e.g., Osseotite®, Implant Innovations, Inc.), and a combination of both (e.g., SLA, Straumann) have gained favor because they are thought to enhance bone-to-implant contact through initial clot stabilization and osteoblast migration to the implant surface.
• These implant surface modifications have been shown to enhance the bone-to-implant contact and strength of resistance compared with machined-surface implants.
• Significantly, the altered microtopography appears to improve implant success in poor-quality bone sites. [Carranza's 10th Ed.]

Machined vs. Rough Surface - Clinical Comparison:

• "In contrast to the macroscopically rough TPS and HA-coated implant surfaces, machined implant surfaces are much more resistant to bacterial contamination and progressive bone loss. However, when compared to implants with 'rough' surfaces, machined surfaces provide weaker secondary stability and consequently result in lower success rates in poor-quality or grafted bone." [Carranza's 10th Ed., Ch. 76]

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33. SURFACE TOPOGRAPHY OF IMPLANT (FIGURE CLASSIFICATION - Carranza's 10th Ed.)

• A: Highly textured implant with titanium plasma-sprayed surface
• B: Highly textured implant with hydroxyapatite-coated surface
• C: Implant with smooth, machined surface
• D: Micro-textured implant with acid etched surface

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34. IMPLANT DESIGN OUTCOMES - SURFACE CHARACTERISTICS IN CONTEXT

• "Many clinicians adhere to the premise that longer implants, threaded implants, and rough-surfaced implants are better than shorter, unthreaded, and smooth designs."
• "Implants with altered surface microtopography (e.g., acid-etched or blasted) enhance the bone to implant interface and can improve outcomes, especially in compromised sites."
• "Lower success rates have been associated with smooth-surfaced (i.e., machined) implants."
• "In patients with inadequate sites, risk factors, or challenging circumstances, certain implant designs may perform better than others. An example is the effect of implant surface characteristics." [Newman & Carranza 14th Ed.]

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35. MACROGEOMETRY AND SURFACE CHARACTERISTICS INTERACTION

• "Macrogeometry threads and microtopography surface characteristics make implant surfaces very challenging to decontaminate."
• The combination of macrogeometry (thread design, pitch, diameter) and microtopography is critical to:
  • Primary stability
  • Bone-implant contact area
  • Resistance to removal forces
  • Decontamination challenge in peri-implantitis

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36. BONE HEALING AROUND IMPLANTS WITH ROUGH SURFACE - HISTOLOGIC EVIDENCE

AstraTech Implant - Histologic Sequence (Abrahamsson et al., 2004 / Berglundh et al., 2003):

• Device used: Custom-made implants (c.p. titanium) in the shape of a solid screw with rough surface topography.
• Thread pitch distance between consecutive profiles: 1.25 mm.
• 0.4-mm deep U-shaped circumferential trough within the thread region.

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37. BONE HEALING TIMELINE - WOVEN TO LAMELLAR TRANSITION

IMPLANT PLACEMENT
       |
       ↓ INITIAL PHASE
Slight tissue necrosis from surgical trauma
       |
       ↓
Multinucleated osteoclasts remove tissue / blood clot
       |
       ↓
OSTEOID (poorly mineralized) BONE replaces cleared tissue
       |
       ↓
WOVEN BONE formation:
• Fast growing (irregular pattern)
• Large osteocytic lacunae
• Intense staining of mineralized matrix (toluidine blue)
• Begins on bony wall and on implant surface (2 weeks)
       |
       ↓ 1–2 MONTHS (under effect of load)
WOVEN BONE slowly transforms to LAMELLAR BONE:
• Parallel layers of collagen fibrils
• Each with its own orientation
• Typical polarized light aspect
• Lamellar bone apposition occurs at slow pace of
  "a few microns per day"
       |
       ↓
SECONDARY REMODELING:
• Replacing primary bone by secondary osteons
• At 8 weeks: almost perfect coating of implant surface with bone

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38. THE PELLICLE LAYER CONCEPT - DETAILED

This is a highly testable examiner concept:

1. Within milliseconds - water, ions, and small biomolecules absorbed
2. Large molecules and cells subsequently adhere - influenced by surface characteristics of this pellicle layer
3. Composition and structure of initial layer largely determined by the underlying surface
4. The three-dimensional shape of the molecules will be modified during their adherence - will unveil different radicals depending on this metamorphosis
5. This is why even though the pellicle seems to "equalize" surfaces, the underlying surface properties still ultimately determine the biological response

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39. OVERALL SUMMARY TABLE: ALL SURFACE TYPES COMPARED

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40. COMPLETE FLOWCHART: DECISION FRAMEWORK FOR IMPLANT SURFACE SELECTION

CLINICAL SCENARIO
       |
   ____|___________________________________________
   |                                              |
GOOD QUALITY BONE                       POOR QUALITY / COMPROMISED
(D1, D2 bone)                           BONE (D3, D4 bone) OR
       |                                EARLY/IMMEDIATE LOADING
       |                                              |
MACHINED SURFACE                        ENHANCED SURFACE
acceptable;                             CHARACTERISTICS
99% success at 15 yr                    NECESSARY
       |                                              |
   ____|____                               ___________|_________
   |        |                             |                     |
Esthetic   Standard               MODERATELY ROUGH          ROUGH
zones      sites                  (SLA / SLActive /         (TPS / HA)
                                  acid-etch / blast)          - higher early
                                  - Best balance of             BIC
                                  osseointegration            - BUT higher
                                  and decontamination           peri-implantitis
                                  if peri-implantitis           risk
                                  occurs                      - Hardest to
                                                               decontaminate

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41. KEY FACTS FROM EACH REFERENCE - QUICK REVISION

From Newman & Carranza 14th Ed. (Chapter 73):

• Surface characteristics = "microdesign"
• Titanium oxidizes within nanoseconds → passive TiO₂ layer (10 nm)
• Biomolecule bond strength considered irreversible when surpassing 30 kcal/mol
• Ti6Al4V → toxic leakage of Al and V → bone resorption
• For good-quality bone: 99% success at 15 years with turned surface
• Enhanced surface characteristics most beneficial for poor-quality bone and early/immediate loading
• Macrogeometry + microtopography = very challenging to decontaminate
• CaP-coated implants: not encouraging from a long-term perspective

From Carranza's 10th Ed. (Chapter 73):

• Surface free energy = "wettability"
• Roughened surfaces speed up bone apposition; produce more PGE₂ and TGF-β₁
• Fibronectin higher adsorption on smooth than roughened surfaces
• Roughened surfaces → increased ion leakage and macrophage adherence
• TPS → highest torque resistance; SLA → intermediate; Machined → lowest
• "No implant surface is smooth" - even machined surfaces have grooves/ridges
• Ra values (profilometer): peak-to-valley; Scx values: spacing between irregularities
• Lamellar bone apposition: "a few microns per day"

From Lang & Lindhe (CPID) 6th Ed. (Chapters 5, 26):

• Rough surfaces show more peri-implantitis progression when untreated (Berglundh 2007, Albouy 2008/2012, Carcuac 2013)
• Turned surface: best post-surgical bone gain and inflammation resolution
• SLA vs. TPS in peri-implantitis treatment: SLA responds better (Roccuzzo 2011)
• Hydrophilic vs. hydrophobic surfaces: studied by Lang et al., Bosshardt et al., Donos et al. (2011)
• De novo bone formation on rough surface: continuous layer at 6 weeks; lamellar bone at 16 months

From Misch Implantology 4th Ed. (Chapters 5, 9):

• Sa roughness categories: smooth (0–0.4 μm), minimally rough (0.5–1 μm), moderately rough (1–2 μm), rough (>2 μm)
• Wennerberg's recommended range: Sa ~1.49 μm (moderately rough)
• Surface tension ≥40 dyne/cm = characteristic of very clean surface; excellent integration conditions
• Three stages of repair after implant placement: blood clot → cellular activation → cellular response
• Growth factors: BMP-2, BMP-7, FGF-2, PDGF-B
• Bisphosphonate coating: improved fixation at 5 years; reduced marginal bone resorption
• HA coating (plasma spray): originally introduced by deGroot; consistent thickness 50 μm at 32 weeks
• Zirconia (Y-TZP): 900–1200 MPa flexural strength; low plaque affinity; t→m phase transformation risk
• Laser ablation: increased hardness, corrosion resistance, purity, thicker oxide layer
• RFGDT: improved wettability, thinner oxide layer; caution: deposits silica oxide from glass envelope
• Carbon contamination (Lausmaa et al.): 20–60% in 0.3–1 nm range
• Gamma radiation >2.5 Mrad: standard sterilization
• ASTM B600 and ASTM F-86: standards for passivation with molten alkaline salts + nitric/HF acid

From Essentials of Clinical Periodontology (S. Reddy):

• Classification based on surface characteristics: TPS, sandblasting, laser-induced roughening, HA coating

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42. RECENT TERMINOLOGY CHANGES - COMPLETE TABLE

---

1. Newman MG et al. Newman and Carranza's Clinical Periodontology and Implantology, 14th Ed.
2. Newman MG et al. Carranza's Clinical Periodontology, 10th Ed.
3. Lang NP, Lindhe J. Clinical Periodontology and Implant Dentistry, 6th Ed.
4. Misch CE. Misch Implantology (Dental Implant Prosthetics), 4th Ed.
5. Reddy S. Essentials of Clinical Periodontology and Periodontics.

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IMPLANT SURFACE CHARACTERISTICS (MICRODESIGN)

Comprehensive Postgraduate Periodontology Theory Examination Notes

Synthesized from All Uploaded References

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INTRODUCTION AND DEFINITION

• Implant surface characteristics - also referred to as microdesign - encompass the chemical and physical properties of the implant surface that determine the nature of hard and soft tissue responses.
• "Implant surface characteristics - microtopography - have been shown to influence the healing process positively. Accordingly, modification of implant surface characteristics has been a major area of research interest and development." [Newman & Carranza 14th Ed., Ch. 73]
• "A key element in the reaction of hard and soft tissues to an implant involves the implant's surface characteristics, that is, the chemical and physical properties. Some materials are not suitable for implantation because they have toxic cellular side effects. Some materials are biocompatible because they do not provoke an immune reaction and are 'passive' toward the tissue-healing process. On the other hand, some materials, as well as various surface characteristics, enhance bone apposition at the implant surface in an osteoconductive manner." [Carranza's 10th Ed., Ch. 73]
• The synthetic biomaterials used for the construction of dental implants and associated abutments can be classified into metallic, ceramic, and surface-modified (coated, reacted, or ion-implanted) groups. [Misch Implantology 4th Ed.]
• Biomaterial surface chemistry (purity and critical surface tension for wetting), topography (roughness), and type of tissue integration (osseous, fibrous, or mixed) can be correlated with shorter- and longer-term in vivo host responses. [Misch Implantology 4th Ed.]

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FLOWCHART 1: Overview of Implant Surface Characteristics

IMPLANT SURFACE CHARACTERISTICS (MICRODESIGN)
                    |
         ___________|___________________________
         |                                      |
  SURFACE CHEMISTRY                    SURFACE TOPOGRAPHY
  (Chemical Composition)               (Physical Properties)
         |                                      |
  - Titanium oxide layer               - Macrogeometry
  - Alloy composition                  - Microtopography
  - Surface free energy                - Nanotopography
  - Wettability / contact angle        - Roughness (Ra / Sa values)
  - Ion exchange at interface          - Peak-to-valley dimensions
  - Dielectric constant                - Spacing (Scx values)
                    |
        MODIFICATIONS ACHIEVED BY:
                    |
         ___________|___________________________
         |                                      |
  ADDITIVE PROCESSES                SUBTRACTIVE PROCESSES
  (Add material to surface)         (Remove/alter surface)
         |                                      |
  - Plasma spraying (TPS, HA)       - Machining (Turned)
  - TiO2 anodizing                  - Acid etching
  - Fluoride incorporation          - Sandblasting
  - Growth factor biocoating        - Combination (SLA)
  - Bisphosphonate coating          - Electropolishing
  - Antibiotic coating              - Laser ablation
  - Biomimetic CaP deposition
  - Statin coating
  - Collagen coating

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1. RATIONALE FOR SURFACE MODIFICATION

• Modifications in surface energy, chemical composition, and surface topography are known to influence cellular activity and tissue responses, leading to enhanced osteogenesis.
• At the molecular level, modified implant surfaces increase adsorption of serum proteins, mineral ions, and cytokines, which subsequently promote cellular migration and attachment.
• Implant surface characteristics can also aid in the retention of a fibrin clot, thus providing a migratory pathway for the differentiating osteogenic cells to reach the implant surface.
• Today, implants are treated with a variety of technologies to modify surface characteristics (microscale or nanoscale) to enhance bone formation. [Newman & Carranza 14th Ed., Ch. 73]
• "Before Brånemark clarified the proper surgical steps to obtain an intimate bone-to-implant contact (osseointegration), researchers focused on surface characteristics to obtain bone apposition. The quest was for biocompatible if not bioactive surfaces, achieved through additive or subtractive processes." [Carranza's 10th Ed., Ch. 73]

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2. IMPLANT SURFACE CHEMICAL COMPOSITION

2a. Material Evolution

2b. Titanium - The Standard Material

2c. Mechanism of Biomolecule Adsorption on TiO₂

• Titanium has a high dielectric constant - higher than most other metal oxides.
• Biomolecules (normally folded to hide their insoluble parts) will adhere to the TiO₂ surface after displacing original water molecules.
• Initially attracted by weak van der Waals forces; the high dielectric constant and polarizability of the molecules after adsorption lead to high bond strengths considered irreversible when surpassing 30 kcal/mol.
• Because of its propensity to be covered by an uninterrupted oxide layer with ceramic-like properties, titanium makes the coating of implants theoretically superfluous. [Newman & Carranza 14th Ed., Ch. 73]

2d. Titanium Alloy (Ti6Al4V) - Concerns

• Ti6Al4V (titanium-aluminum 6%, vanadium 4%) is known to provoke bone resorption as the result of leakage of some toxic components (aluminum and vanadium).
• "The different surface oxides are then argued to be responsible for a 'lesser' quality of osseointegration because of the potential of corrosion products that contain aluminum and vanadium." [Misch Implantology 4th Ed.]

2e. In Vivo Surface Reactions

• Oxide modification during in vivo exposure: increased TiO₂ layer thickness up to 200 nm.
• Increased levels of calcium and phosphorus found in oxide surface layers - indicating active exchange of ions at the interface.
• Hydrogen peroxide conditions interact with Ti to form a complex gel ("titanium gel conditions") - credited with attractive in vitro properties including low toxicity, inflammation, bone modeling, and bactericidal characteristics.
• Free titanium ions have been shown to inhibit the growth of HA crystals (i.e., mineralization of calcified tissues at the interface). [Misch Implantology 4th Ed.]

2f. Long-Term Clinical Perspective

• "To date, clinical results with CaP-coated implants have not been encouraging from a long-term perspective."
• For good-quality bone, after 15 years of follow-up, clinical success rates of 99% have been reported for implants with a turned surface.
• Enhanced implant surface characteristics are likely to be most beneficial for more challenging situations - poor-quality bone and early and immediate loading. [Newman & Carranza 14th Ed., Ch. 73]

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3. SURFACE FREE ENERGY AND MICROSCOPIC ROUGHNESS

3a. The Bioliquid Interface Concept

IMPLANT PLACED IN BODILY TISSUES (BONE)
              |
              ↓ WITHIN MILLISECONDS
WATER, IONS, SMALL BIOMOLECULES ABSORBED
("bioliquid" = aqueous environment)
              |
              ↓
PELLICLE LAYER FORMS
• Composition and structure LARGELY DETERMINED
  by the underlying surface characteristics
              |
              ↓
LARGE MOLECULES AND CELLS adhere to pellicle layer
• 3D shape of molecules MODIFIED during adherence
• Different radicals UNVEILED depending on this metamorphosis
• Surface characteristics of pellicle layer determine
  which proteins/cells adhere and how
              |
              ↓
SURFACE ENERGY, CHEMISTRY, AND TOPOGRAPHY
→ determine protein adsorption
→ determine cell adhesion and migration
→ determine osseointegration outcome

3b. Surface Free Energy (Wettability)

• Surface free energy, often called "wettability," is an important parameter for these interactions.
• Assessed through the shape of a standardized drop of liquid put on the clean implant surface.
• The contact angle reveals cohesive vs. adhesive forces.
• A ball-shaped drop reveals low surface free energy.
• High surface energy implants showed a threefold increase in fibroblast adhesion.
• High-energy surfaces (metals, alloys, ceramics) are best suited to achieve cell adhesion.
• Surface tension values of ≥40 dyne/cm are characteristic of very clean surfaces and excellent biological integration conditions.
• "A shift in contact angle (increase) is related to the contamination of the surface by hydrophobic contaminants" and decreases the surface tension parameters.
• "The wetting of the surface by blood at the time of placement can be a good indication of the high surface energy of the implant." [Carranza's 10th Ed.; Misch Implantology 4th Ed.]

3c. Surface Roughness Parameters

• Surface roughness measured with a profilometer - a stylus that follows the surface and measures:
  • Ra values: peak-to-valley dimensions (height parameter) - 2D measurement
  • Sa values: 3D equivalent of Ra - more accurate for implant surfaces
  • Scx values: spacing between irregularities
• "No implant surface is smooth" - even turned (machined) implant surfaces are not truly smooth (SEM confirms grooves, ridges, and pits). [Carranza's 10th Ed., Ch. 73; Misch Implantology 4th Ed.]

3d. Classification of Surface Roughness (Wennerberg/Albrektsson - cited in Misch 4th Ed., Table 9.1)

• Wennerberg's recommended range: Sa approximately 1.49 μm (moderately rough category). [Misch Implantology 4th Ed.]

3e. Effects of Surface Roughness on Bone Response

• Speed up bone apposition.
• In vitro: more prostaglandin E₂ (PGE₂) and transforming growth factor beta (TGF-β₁) are produced.
• Surface features with which fibrin can become entangled - increases fibrin retention.
• Increases available surface area for fibrin attachment → greater BIC.
• Moderately rough and rough surfaces promote migration of bone cells to implant surface.
• Pits on implant surface mimic naturally occurring osteoclastic activity and lead osteoblasts to deposit bone.

• Increased ion leakage.
• Increased adherence of macrophages and subsequent bone resorption.
• In vitro adsorption of fibronectin was higher on smooth than on roughened CP titanium surfaces.
• Biofilm formation directly proportional to surface roughness - greater roughness = higher biofilm formation rate.
• More pronounced peri-implantitis progression if left untreated.
• Very challenging to decontaminate in peri-implantitis management. [Carranza's 10th Ed.; Misch Implantology 4th Ed.]

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4. CLASSIFICATION OF MODIFICATION PROCESSES

SURFACE MODIFICATION PROCESSES
               |
      _________|_________
      |                  |
ADDITIVE             SUBTRACTIVE
PROCESSES            PROCESSES
      |                  |
Increases           Removes or
surface             alters existing
material            surface
      |                  |
Generally           Changes most
"ROUGHER"           notable at
surfaces            MICROSCOPIC
                    level
      |                  |
  - HA/CaP coating   - Machining
  - TPS              - Acid etching
  - Anodizing        - Sandblasting
  - Fluoride         - Electropolishing
  - Growth factors   - Combination (SLA)
  - Bisphosphonates  - Laser ablation
  - Antibiotics
  - Biomimetic HA
  - Statins
  - Collagen

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5. ADDITIVE PROCESSES - DETAILED

• Methods include: inorganic mineral coatings, plasma spraying, biocoating with growth factors, fluoride, and particulates or cements containing calcium phosphates, sulfates, or carbonates.
• Additive surface modifications tend to increase the surface texture more than subtractive modifications, resulting in topographically "rougher" implant surfaces.
• Surface roughness can also be increased by oxidation or adding an oxide layer. [Newman & Carranza 14th Ed., Ch. 73]

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5a. TITANIUM PLASMA SPRAYED (TPS) SURFACE

• TPS demonstrated higher torque resistance because the roughness creates greater mechanical interlocking.
• In peri-implantitis treatment (Roccuzzo et al., 2011): reduction of PPD and BoP was less pronounced at TPS than at SLA surface.
• "Implant resective techniques" on TPS surface showed some benefit at 3-year follow-up (Romeo et al., 2007) - with caution regarding potential damage from overheating and spreading of metal particles. [Newman & Carranza 14th Ed.; Carranza's 10th Ed.; Lang & Lindhe 6th Ed.]

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5b. HYDROXYAPATITE (HA) COATING

• Showed accelerated bone formation and maturation around HA-coated implants in dogs vs. non-coated implants.
• HA coating can also reduce the corrosion rate of substrate alloys.
• Bone adjacent to HA-coated implants: better organized with higher degree of mineralization.
• Most significant result: increase in bone penetrations, enhancing fixation in areas of limited initial bone contact.

Controversy: "Some authors caution that HA coatings do not necessarily represent an advantage for the long-term prognosis of the system." Bacterial microleakage between the HA layer and titanium has been reported to cause accelerated bone loss.

• "In general, the less crystalline the material, the faster its resorption rate."
• HA is nonconductor of heat and electricity - considered advantageous for coated dental implants. [Misch Implantology 4th Ed.]

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5c. METHODS FOR APPLYING CALCIUM PHOSPHATE (CaP) COATINGS

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5d. ANODIZED SURFACE (TiO₂ Modification - TiUnite)

• Another line of research used increased or modified TiO₂ layers to enhance or accelerate bone formation.
• Achieved by anodizing or chemical processing.
• The oxide content of the TiO₂ layer is essential for nucleation processes to form calcium phosphate precipitates → mineralized bone formation.
• TiUnite (Nobel Biocare): Electrochemical process that thickens and roughens the titanium oxide layer. Even minute pores allow bone deposition - pore sizes reach a few microns only. Apatite crystal deposition is evident in the oxide layer. [Carranza's 10th Ed., Ch. 73; Misch Implantology 4th Ed.]

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5e. FLUORIDE INCORPORATION

• Fluoride ions can be displaced by oxygen originating from phosphates, thus achieving a covalent binding between bone and implant surface.
• Fluoride release is also known to inhibit the adhesion of proteoglycans and glycoproteins on the hydroxyapatite surface - two macromolecules known to inhibit mineralization. [Carranza's 10th Ed., Ch. 73]

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5f. PHARMACOLOGIC / BIOACTIVE COATINGS

i. BISPHOSPHONATE COATING (Misch 4th Ed.)

• Nanometer-thin fibrinogen coating containing minimal amounts of bisphosphonates.
• Improved early implant fixation - effect maintained at 5 years after prosthetic loading.
• Reduced marginal bone resorption.
• Resonance frequency analysis (RFA): better fixation in coated implants.
• At 5 years: bisphosphonate-coated implants showed only a small amount of resorption (median 0.20 mm).
• Histologic analysis: mature lamellar bone trabeculae in intimate contact with implants at 6-month follow-up.
• Mechanism: bisphosphonates inhibit osteoclast-mediated bone resorption → retain existing bone.
• Concern: Old bone becomes brittle → nonideal local environment for increased BIC; "bony shield" concept may explain better early fixation.

ii. STATIN COATING (Misch 4th Ed.)

• Simvastatin induces expression of BMP-2 mRNA → promotes bone formation.
• Topical statins increased bone formation and suppressed osteoclast activity at bone-healing site.
• Clinical studies reported statin use associated with increased bone mineral density.

iii. ANTIBIOTIC COATING (Misch 4th Ed.)

• Gentamycin + HA layer coated onto implant surface → local prophylactic agent.
• Tetracycline enhances blood clot attachment and retention on implant surface during initial healing → promotes osseointegration.

iv. COLLAGEN COATING (Misch 4th Ed.)

• Collagen coating based on extracellular matrix containing chondroitin sulfate (prepared by fibrillogenesis).
• Slightly higher BIC values than reference implant at 2 weeks; continued nearly equally.

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5g. FUNCTIONALIZATION WITH BIOLOGICALLY ACTIVE SUBSTANCES

• Purpose: diminish initial inflammatory response after implant placement and encourage rapid bone growth.
• Four growth factors with potential use in implantology:

• BMP-2 delivery: via absorbable collagen sponge or porous implants coated with rhBMP-2.
• High doses of BMP-2 → localized/temporary bone impairment or increased bone resorption from osteoclast stimulation (levels drop → normal bone formation resumes).
• rhBMPs: costly; high dose requirement (several μg to mg); poor distribution profile.
• PDGF-B: Chang et al. demonstrated stimulation of osseointegration in vivo. Isolated recombinant PDGF may affect bone formation adversely.
• Clinical equivalent of PDGF: platelet-rich plasma (PRP) or platelet-fibrin clot.

• Fibronectin: Stimulates osteoblastic differentiation, tissue mineralization, strong osseointegration in vivo.
• Common problems: increased implant cost; complications with usage; preservation challenges; concerns about rate and area of release into surrounding tissues.

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5h. BIOMIMETIC FORMATION OF HYDROXYAPATITE ON IMPLANT SURFACE (Misch 4th Ed.)

• Uses coatings with similar composition to human bone → accelerated osseointegration during earliest healing stages.
• CaP apatite has the same chemical composition as mineral bone phase → no inflammatory reaction.
• HA plasma spraying in clinical studies produced quicker osseointegration at early stages, but accelerated bone loss due to bacterial microleakage between HA layer and titanium has been reported.

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6. SUBTRACTIVE PROCESSES - DETAILED

• Methods: machining, acid etching, blasting, or a combination of these processes.
• Enhance the amount or speed of osseointegration.
• Changes are most notable at the microscopic level. [Newman & Carranza 14th Ed., Ch. 73]

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6a. MACHINED/TURNED SURFACE

• "Even turned, or machined, implant surfaces are not 'smooth.'" - SEM view confirms grooves and marks from manufacturing tools.
• Proponents argue machined surface is most conducive to cell attachment.
• "In contrast to macroscopically rough TPS and HA-coated surfaces, machined implant surfaces are much more resistant to bacterial contamination and progressive bone loss."
• However: machined surfaces provide weaker secondary stability → lower success rates in poor-quality or grafted bone. [Carranza's 10th Ed.; Misch Implantology 4th Ed.]

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6b. ACID ETCHING

• Acid treatment removes the surface oxide and any contamination → clean and homogeneous surface.
• Acids used: hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid.
• ASTM specifications (ASTM B600, ASTM F-86): pickling and descaling with molten alkaline base salts + nitric/HF acid treatment.
• Rapidly attacks metals other than titanium - electrochemical in nature.
• Thought to promote favorable cellular responses and increased bone formation in close proximity to the surface.
• Commercial examples: BIOMET 3i OSSEOTITE and NanoTite. [Newman & Carranza 14th Ed.; Misch Implantology 4th Ed.]

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6c. SANDBLASTING (PARTICLE BLASTING)

• Particles projected through a nozzle at high velocity onto the implant.
• Materials used: titanium dioxide (TiO₂), aluminum dioxide (Al₂O₃), HA.
• Provides irregular rough surfacing with <10 μm scales and potential for impurity inclusions.
• Commercial examples: DENTSPLY/ASTRA TECH TiOblast, Zimmer Dental MTX. [Misch Implantology 4th Ed.]

Effect of Blast Particle Size on Roughness:

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6d. RESORBABLE BLAST MEDIA (RBM) SURFACE

• Uses HA as the blast media (instead of aluminum oxide, grit, or sand).
• Key advantage: Any particles remaining on surface are resorbable and biocompatible → do not affect healing.
• HA is also a component of bone → osteoinductive.
• Sa of 1.49 μm (within Wennerberg's recommended range).
• Commercial example: Hahn Tapered Implants. [Misch Implantology 4th Ed.]

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6e. SLA (SANDBLASTED, LARGE GRIT, ACID ETCHED)

Examiner Keyword: SLA = Sandblasted, Large grit, Acid-Etched

• "When the surface roughness is microscopic, such as that achieved with an acid-etched or blasted implant, the bone adaptation to the microtopography will increase the shear strength needed to fracture the bone from the surface to a level that is greater than a turned surface but less than a plasma-sprayed surface." [Carranza's 10th Ed., Ch. 73]
• Subtractive surface modifications (blasting, acid etching, SLA) enhance bone-to-implant contact through initial clot stabilization and osteoblast migration to the implant surface.
• Altered microtopography appears to improve implant success in poor-quality bone sites. [Carranza's 10th Ed., Ch. 76]

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6f. SLActive SURFACE - RECENT TERMINOLOGY

Recent Terminology/Update: SLActive = Chemically modified SLA surface (hydrophilic modification)

• Modification of SLA surface to improve hydrophilicity/wettability.
• Distinction from SLA: SLActive is a distinct surface - not just modified SLA but a separately studied hydrophilic entity.
• Studies on early osseointegration to hydrophilic and hydrophobic implant surfaces (Lang et al., 2011; Bosshardt et al., 2011; Donos et al., 2011 - cited in CPID 6th Ed.).
• RFA values for SLActive implants at placement: 58–67; at late healing: 76–80. [Lang & Lindhe 6th Ed.; Newman & Carranza 14th Ed.]

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6g. ELECTROPOLISHING

• Used to reduce surface roughness to only 0.1 μm scale by controlled removal of surface layer by dissolution.
• Employed for titanium alloy Ti-6Al-4V to improve mechanical properties. [Misch Implantology 4th Ed.]

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6h. LASER ABLATION

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7. CLASSIFICATION OF IMPLANTS BY SURFACE CHARACTERISTICS

"Based on surface characteristics, implants are classified into:

1. Titanium plasma sprayed coating
2. Sandblasting surface etching
3. Laser-induced surface roughening
4. Hydroxyapatite coating"

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8. NANOTECHNOLOGY AND NANOTOPOGRAPHY

• "Structural features in the extracellular matrix are on the nanometer scale, and it is thought that biomaterials that mimic this environment might more effectively promote the processes of bone regeneration."
• Nanotechnology involves materials with a surface roughness range between 1 and 100 nm.
• Nanoscale surfaces influence:
  • Adsorption of proteins
  • Adhesion of osteoblastic cells
  • Rate of osseointegration

Biological Rationale for Different Scale Surface Features:

• Bone cell migration and bone formation on titanium surfaces related to similarity between microroughness and pit irregularities found in natural bone surfaces from osteoclast activity.
• "As with natural bone, osteoblasts find these surface irregularities and begin depositing matrix in and around them to form bone."
• "Advancing dental implant surface technology - from micron- to nanotopography" (Mendonca et al., 2008 - referenced in Newman 14th Ed.). [Misch Implantology 4th Ed.; Newman & Carranza 14th Ed.]

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9. SURFACE TOPOGRAPHY - THREE LEVELS

IMPLANT SURFACE TOPOGRAPHY
              |
    _________|________________________________
    |                |                        |
MACRO-          MICRO-                  NANO-
TOPOGRAPHY      TOPOGRAPHY              TOPOGRAPHY
(>100 μm)       (1–100 μm)              (<1 μm)
    |                |                        |
Thread          Pits, grooves,          Crystal-level
design,         surface                 features
implant         roughness               (1–100 nm)
shape,          peaks-valleys
diameter        Ra / Sa values
                Achieved by:
                SLA, TPS,
                acid etch,
                sandblast,
                laser
    |                |                        |
Determines      Determines              Governs initial
Primary         Bone-Implant            protein adsorption
stability       Contact (BIC)           (fibronectin,
                                        vitronectin)
                                        Cell behavior

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10. CELLULAR PHENOMENA AT IMPLANT-BONE INTERFACE DURING HEALING

IMPLANT PLACEMENT
       |
       ↓ IMMEDIATE (0 hr)
SERUM ADSORPTION
• Protein adsorption (fibronectin, vitronectin, albumin)
• Lipids, sugars, mineral ions absorbed to surface
       |
       ↓ 0–3 DAYS
MESENCHYMAL CELL RECRUITMENT
• Cell attachment and Proliferation
• Surface modification of adsorbed layer
       |
       ↓ 3–6 DAYS
OSTEOBLAST DIFFERENTIATION AND OSTEOID PRODUCTION
• Matrix vesicle production
• Matrix production
       |
       ↓ 6–21 DAYS
MATRIX VESICLE MATURATION AND CALCIFICATION
• Matrix calcification
• Mineral ion incorporation
       |
       ↓ >21 DAYS
BONE REMODELING
• Woven bone → Lamellar bone
• Remodeling by osteoclasts and osteoblasts

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11. BONE HEALING TIMELINE - HISTOLOGIC SEQUENCE

IMPLANT PLACEMENT
       |
       ↓ INITIAL PHASE
Slight tissue necrosis from surgical trauma
       |
       ↓
Multinucleated OSTEOCLASTS remove tissue/blood clot
       |
       ↓
OSTEOID (poorly mineralized) bone replaces cleared tissue
       |
       ↓
WOVEN BONE formation:
• Fast growing (irregular pattern)
• Large osteocytic lacunae; intense staining
• Begins on bony wall AND on implant surface (2 weeks)
• Primary scaffold of tiny trabeculae
       |
       ↓ 1–2 MONTHS (under effect of load)
WOVEN BONE → LAMELLAR BONE:
• Parallel layers of collagen fibrils
• Each with its own orientation (polarized light)
• Lamellar bone apposition: "a few microns per day"
       |
       ↓
SECONDARY REMODELING (>8 weeks):
• Replacing primary bone by secondary osteons
• Almost perfect coating of implant surface with bone

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12. STAGES OF OSSEOINTEGRATION REPAIR

IMPLANT PLACEMENT INTO OSTEOTOMY
              |
              ↓ STAGE 1
INITIAL FORMATION OF BLOOD CLOT
• Blood components interact with implant surface
• Adsorption of plasma proteins (fibrin) onto surface
• Ability of surface to RETAIN fibrin during wound
  contraction is CRITICAL
              |
              ↓ STAGE 2
CELLULAR ACTIVATION
• Migration of bone cells through fibrin clot
• Moderately rough and rough surfaces provide features
  for fibrin entanglement → increased fibrin retention
              |
              ↓ STAGE 3
CELLULAR RESPONSE
• Bone cells reach implant surface via migration
• Bone laid down directly on implant surface
• Pits on surface mimic osteoclastic pits → guide
  osteoblasts to deposit bone
              |
              ↓
IMPROVED BIC → OSSEOINTEGRATION

• "Microroughness on implant surfaces helps in retention of the fibrin clot. This in turn enables the migration of bone progenitor cells that deposit bone in close proximity to the implant, improving the BIC." [Misch Implantology 4th Ed.]

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13. SURFACE ROUGHNESS AND PERI-IMPLANT DISEASE

Critical Examiner Point: Surface roughness is a double-edged sword.

• "Macrogeometry threads and microtopography surface characteristics make implant surfaces very challenging to decontaminate." [Newman & Carranza 14th Ed., Ch. 73]

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14. SURFACE PROPERTIES THAT REDUCE BACTERIAL ADHESION

1. Negatively charged surfaces
2. Super-hydrophobic surfaces
3. Super-hydrophilic surfaces
4. Nanometer-scale surface roughness

"Biofilm formation is directly proportional to surface roughness; the greater the roughness, the higher the rate of biofilm formation is around the implants. The wettability and surface free energy (SFE) of a specific surface also influence the biofilm formation on implants."

Caveat: "The presence of an acquired pellicle containing host and bacterially derived proteins poses a great challenge to the control of bacterial adhesion and biofilm formation based on surface modifications."

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15. SURFACE CLEANLINESS, CONTAMINATION, AND STERILIZATION

Definition of a Clean Surface

• "A clean surface is an atomically clean surface with no other elements than the biomaterial constituents."
• Contaminants: particulates, continuous films (oil, fingerprints), and atomic impurities/molecular layers caused by thermodynamic instability of surfaces.
• High-energy surfaces (metals, oxides, ceramics) bind more to contamination than polymers and carbon.

Historical Background

• In early implantology: no specific protocol for surface preparation, cleaning, sterilization, and handling.
• Adverse host responses caused by faulty preparation, sterilization, adsorbed gases, organic/inorganic debris.
• Albrektsson: "Implants that seem functional may fail even after years of function due to improper ultrasonic cleaning, sterilization, or handling."

Carbon Contamination (Lausmaa et al.)

• Carbon contamination loads: 20–60% in 0.3–1 nm range on titanium implants.
• Source: air exposure and residues from cleaning solvents and lubricants used during fabrication.

Passivation Standards

• ASTM B600, ASTM F-86: Pickling and descaling with molten alkaline base salts + treatment with nitric or hydrofluoric acid to eliminate iron and other contaminants.
• "A general rule has been that cleaner is better." [Misch Implantology 4th Ed.]

Sterilization Methods and Effects

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16. ZIRCONIA IMPLANTS AND SURFACE CHARACTERISTICS

Surface Modification of Zirconia:

• Sandblasting and acid etching trigger tetragonal-to-monoclinic (t→m) phase transformation.
• Associated with 3–4% phase volume expansion → induces compressive stresses at crack tip → transformation toughening.
• Concern: Surface flaws introduced by sandblasting/acid etching act as stress concentrators → potential sites for crack initiation and propagation → strength degradation → implant fracture risk.

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17. COMPREHENSIVE TABLE: ALL SURFACE TYPES - COMPLETE COMPARISON

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18. COMPARATIVE TABLE: DIFFERENT REFERENCES ON KEY TOPICS

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19. CLINICAL SIGNIFICANCE SUMMARY

CLINICAL SCENARIO
       |
   ____|____________________________________________
   |                                               |
GOOD QUALITY BONE                       POOR QUALITY / COMPROMISED
(D1, D2 bone)                           BONE (D3, D4) OR
       |                                EARLY / IMMEDIATE LOADING
       |                                               |
MACHINED SURFACE                        ENHANCED SURFACE
acceptable;                             CHARACTERISTICS
99% success at 15 yr                    NECESSARY
"Lower success rates with               (SLA / SLActive /
machined surface in poor bone"          acid-etch / blasted)
       |                                               |
   ____|____                               ____________|____________
   |        |                             |                         |
ESTHETIC  STANDARD               MODERATELY ROUGH              AVOID ROUGH
ZONES     SITES                  PREFERRED:                    (TPS/HA) due to:
                                  - Best balance of             - High peri-implantitis
                                    osseointegration              progression risk
                                    and decontaminability       - Hardest to decontaminate
                                  - Post-surgical               - Least favorable
                                    treatment response            treatment response
                                    if peri-implantitis occurs

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20. COMPLETE KEYWORD LIST FOR EXAMINATION

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21. RECENT TERMINOLOGY CHANGES - COMPLETE TABLE

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1. Newman MG, Takei HH, Klokkevold PR, Carranza FA. Newman and Carranza's Clinical Periodontology and Implantology, 14th Ed. - Ch. 73 (Peri-Implant Anatomy, Biology, and Function)
2. Newman MG, Takei HH, Carranza FA. Carranza's Clinical Periodontology, 10th Ed. - Ch. 73 (Implant Surface Characteristics), Ch. 76 (Standard Implant Surgical Procedures)
3. Lang NP, Lindhe J. Clinical Periodontology and Implant Dentistry, 6th Ed. - Ch. 5 (Process of Osseointegration), Ch. 26 (Peri-Implantitis)
4. Misch CE. Misch Implantology (Dental Implant Prosthetics), 4th Ed. - Ch. 5 (Biomaterials for Dental Implants), Ch. 9 (Dental Implant Surfaces)
5. Reddy S. Essentials of Clinical Periodontology and Periodontics - Ch. 47 (Dental Implants: Periodontal Considerations)