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Quick Navigation Guide

• Q1: Clinical diagnostic aids + vitality testing (thermal, EPT, LDF)
• Q2: Endodontic emergencies + Acute alveolar abscess (signs, symptoms, management)
• Q3: Intraoral radiography in endodontics (types and uses)
• Q4: Pulp vitality tests (comparison table)
• Q5: Electric pulp tester (principle, technique, interpretation)
• Q6: Rationale of endodontics
• Q7: Buccal object rule / SLOB rule
• Q8: RVG / Radio Visiography [2M]

• Q9: Classification of pulp and periapical diseases
• Q10: Irreversible pulpitis (features, diagnosis, DD, treatment)
• Q11: Resorption classification + External cervical root resorption
• Q12: Reversible pulpitis
• Q13: Differences between reversible and irreversible pulpitis (table)
• Q14: Chronic hyperplastic pulpitis (pulp polyp)
• Q16: Phoenix abscess [2M]
• Q17: Zones of a periapical lesion
• Q19: Incision and drainage
• Q20: Pink tooth (Mummery) - internal resorption
• Q21: Management of internal root resorption

• Q22: Obturation techniques + materials
• Q23: Thermoplasticized GP technique (Thermafil, Obtura II, Continuous wave)
• Q24: Standardization of instruments + Step-back preparation
• Q25: Root canal irrigants - NaOCl vs CHX (detailed)
• Q26: Intracanal medicaments (Ca(OH)2, Triple antibiotic paste, DAP)
• Q27: Working length definition + Apex locators
• Q28: Ingle's radiographic WL method
• Q30: Single visit RCT - advantages
• Q31: Balanced force technique
• Q32: Apexification (Ca(OH)2, MTA plug, Regenerative)
• Q33: Errors in access cavity preparation
• Q34: Root canal sealers (classification + properties)

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ENDODONTICS - Complete Answer Guide (Page 2)

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CONTINUING: VITAL PULP THERAPY & RCT

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1. Bioceramic Sealer

• Hydrophilic - sets in the presence of moisture (uses dentinal fluid)
• Dimensionally stable - does not shrink; slightly expands on setting
• Excellent biocompatibility - stimulates hard tissue formation
• Alkaline pH (~12.8) - antimicrobial
• Radiopaque
• Excellent sealing ability - bonds chemically to dentin via hydroxyapatite formation
• Antibacterial against E. faecalis

• Root canal sealer with GP (single cone technique preferred with BC sealer)
• Root-end filling
• Apexification / apexogenesis
• Perforation repair

• No eugenol (no cytotoxicity)
• Moisture-activated (no drying needed)
• Superior bond strength to dentin
• Bioactive (promotes bone healing)

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2. Warm Vertical Condensation (Schilder's Technique)

• Finger spreaders and pluggers (sizes 8-11)
• Heat carrier (Glick No. 1 or Touch'n Heat system, System B)
• GP cones (non-standardized/conventional)

1. Fit a master GP cone 1 mm short of WL; tug-back should be present
2. Coat with sealer, seat cone
3. Sear off excess coronal GP with heated instrument
4. Downpack (apical compaction):
   • Heat carrier placed into GP, withdraw in 1-2 seconds
   • Follow immediately with cold plugger applying firm apical pressure
   • Repeat until apical 5 mm is densely compacted
5. Backfill (coronal compaction):
   • Inject segments of softened GP (Obtura / cartridge system)
   • Condense each increment with cold plugger
   • Continue coronally until access filled

1. Develop continuously tapering funnel shape
2. Narrow apical foramen to smallest practical size
3. Maintain original canal curvature
4. Apical foramen in original position
5. Do not force debris beyond apex

• 3D obturation (fills lateral canals, isthmuses, fins)
• Excellent apical seal
• Adapts to irregular canal anatomy
• Best technique for teeth with lateral canals

• Technique-sensitive
• Risk of apical extrusion if canal not tapered properly
• Time-consuming
• Expensive equipment

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3. Non-Radiographic Methods of Working Length Determination

1. Electronic Apex Locator (EAL) - most commonly used non-radiographic method; measures electrical impedance/resistance to locate CDJ
2. Tactile method - sense of file binding/resistance at apical constriction; highly operator-dependent, unreliable
3. Paper point method - moist paper point = WL; unreliable alone
4. Average tooth length method - using published mean tooth lengths (Kuttler's/Black's tables); least accurate
5. Patient response - patient signals discomfort when file reaches apical area; unreliable, unethical

• See previous detailed answer (Root ZX, 4th generation)
• Accuracy: ~90-95% within 0.5 mm of CDJ
• Works best in multi-frequency (ratio) devices

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4. Ni-Ti (Nickel-Titanium) Files

• Super-elasticity (pseudoelasticity) - returns to original shape after deformation; 2-3x more flexible than SS
• Shape memory - returns to original straight shape when heated
• Low modulus of elasticity - follows canal curvature without straightening
• Cuts efficiently (rake angle design)

• Better flexibility - ideal for curved canals
• Reduces canal transportation and ledging
• Faster preparation
• Maintains original canal curvature

• Sudden fracture without warning (cyclic fatigue + torsional fatigue)
• Cannot be pre-curved manually
• Cannot be sterilized as many times as SS (fatigue accumulates)
• More expensive

• 1st Gen: M-Wire (ProFile, ProTaper Universal) - conventional NiTi
• 2nd Gen: M-Wire (ProTaper NEXT) - improved flexibility
• 3rd Gen: CM Wire (controlled memory) - HyFlex CM, typhoon
• 4th Gen: Gold wire (heat treatment) - ProTaper Gold, WaveOne Gold
• 5th Gen: Blue wire (heat treatment) - Reciproc Blue, Vortex Blue

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5. Apex Locators

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6. Lateral Compaction Technique (Cold Lateral Condensation)

1. Select master cone matching MAF (master apical file) - should bind 1 mm short of WL (tug-back)
2. Coat master cone with sealer, insert to WL
3. Insert finger spreader alongside master cone, apply apical and lateral pressure for 15-30 seconds; rotate and withdraw
4. Insert accessory/auxiliary cone (fine-fine or fine) into space created by spreader
5. Repeat steps 3-4 until spreader can only penetrate 3-4 mm from canal orifice
6. Sear off excess GP at orifice with hot instrument
7. Verify radiographically

• Most commonly taught technique
• Easy to learn
• Good apical seal
• Allows verification radiograph before completion
• Easily retrievable for retreatment

• Does not fill lateral canals or fins
• Multiple cones + sealer interfaces (potential microleakage)
• Finger fatigue with many accessory cones
• Cannot fill complex anatomy as well as warm techniques

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7. Cold Lateral Compaction

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8. Sodium Hypochlorite (NaOCl) - Note

• Accidental injection beyond apex
• Immediate severe pain, rapid swelling, ecchymosis, paraesthesia, hemorrhage
• Management: Stop irrigation immediately; large volume saline flush; analgesics (IV/IM); ice pack; antibiotics; reassure; monitor; refer if severe

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9. Ingle's Method of Working Length Determination

• Estimate tooth length from diagnostic radiograph
• Place file at estimated length, take working radiograph
• Adjust: WL = ETL ± correction factor
• Target: 0.5-1.0 mm short of radiographic apex

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10. Errors in Cleaning and Shaping the Root Canal System

1. Ledge formation - false step/shelf created on canal wall; due to uncurved files, inadequate coronal flaring
2. Apical transportation/zipping - teardrop shape at apex; loss of working length and apical constriction
3. Perforation (strip perforation) - thin inner curved wall perforated; common in curved canals
4. Elbow formation - narrowing above ZIP in curved canal
5. Straightening of curved canal - loss of original curvature
6. Over-instrumentation - beyond apex, foramen torn/destroyed
7. Under-instrumentation - debris not removed, apical seal poor

• Torsional failure (file binds and handle continues to rotate)
• Cyclic fatigue (repeated bending of NiTi file in curved canal)
• Management of separated file: attempt bypassing with small files; ultrasonic removal (Masserann kit); surgical retrieval; leave in place if cannot be removed

• NaOCl accident (overpressure injection)
• Insufficient irrigation (incomplete debridement)

• Thin layer of cut dentin, pulp remnants, bacteria pushed onto canal walls
• Should be removed with EDTA + NaOCl before obturation
• If left: microleakage, bacterial growth under it

• Pre-operative radiograph to assess canal curvature (Schneider's angle)
• Pre-curving files for curved canals
• Adequate coronal flaring before apical instrumentation
• Use flexible NiTi files in curved canals
• Recapitulation between instruments
• Copious irrigation

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11. Pulpotomy

• Primary teeth with carious exposure (if radicular pulp is vital)
• Young permanent teeth with incomplete apex (Cvek pulpotomy)
• Cervical pulpotomy

• Necrotic radicular pulp
• Pathological root resorption (primary teeth)
• Mobility due to bone loss
• No restorable crown

• Most commonly used in pediatric dentistry
• Remove coronal pulp
• Apply 1:5 diluted formocresol on cotton pellet for 5 minutes
• Fixation/mummification of radicular pulp
• Restore with ZOE base + SSC (stainless steel crown)

• Superior outcomes; biocompatible
• MTA placed directly on radicular pulp stumps
• Promotes dentin bridge formation
• Used in both primary and young permanent teeth

• Promotes hard tissue barrier
• Higher failure rate in primary teeth due to internal resorption induction

• Newer, excellent biocompatibility
• Similar to MTA but sets faster, easier to handle

• Only 2 mm of exposed/inflamed pulp removed
• MTA or Ca(OH)2 placed
• Maintains entire radicular pulp for continued root development

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12. Mineral Trioxide Aggregate (MTA) - Composition and Uses

• Main: Portland cement (75%) + Bismuth oxide (20%) + Gypsum (5%)
• Portland cement = Tricalcium silicate + Dicalcium silicate + Tricalcium aluminate + Tetracalcium aluminoferrite
• Bismuth oxide = radiopacifier
• Water:powder ratio = 0.33

• pH: 12.5 (alkaline) - antimicrobial
• Setting time: 2 hours 45 minutes (slow)
• Sets in presence of moisture (unique advantage)
• Radiopaque
• Excellent biocompatibility
• Induces hard tissue formation (cementum, bone, dentin bridge)
• Excellent sealing ability
• Low solubility

1. Apexification (open apex management in non-vital immature teeth) - MTA apical plug
2. Apexogenesis (vital pulp therapy in incompletely developed roots)
3. Pulp capping (direct and indirect)
4. Pulpotomy (primary and permanent teeth)
5. Perforation repair (furcation, strip, iatrogenic perforations)
6. Root-end filling (retrofilling in periapical surgery)
7. Cervical root resorption repair
8. Resorptive defect filling
9. Cracked tooth management

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13. Perforation and Its Management

1. Carious perforations
2. Iatrogenic (procedural) perforations
3. Resorptive perforations

1. Coronal/chamber floor (furcation perforation)
2. Cervical (strip perforation at CEJ level)
3. Midroot (strip perforation in curves)
4. Apical (over-instrumentation)

• Sudden bleeding during access
• Sudden loss of pain during pulpectomy
• Sudden length discrepancy
• EAL reading changes
• Radiograph showing file in wrong position
• CBCT (most accurate)

• Location (cervical = poor; apical = better)
• Size (small = better)
• Time elapsed (immediate repair = best)
• Contamination (infected = poor)
• Involvement of crestal bone

• MTA - material of choice for most perforations
• Clean perforation site with saline/NaOCl
• Place MTA into defect (small increments, moist cotton pellet)
• Allow to set; continue RCT
• Biodentine, GIC, Super-EBA can also be used

• Furcation perforations (large, infected): surgical access, MTA placement, bone graft
• Strip perforations that cannot be managed non-surgically

• Calcium sulfate or collagen placed externally as matrix
• MTA packed internally against matrix

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14. Irrigating Solutions - Enumeration + Note on NaOCl

• 17% EDTA for 1 minute (removes inorganic component)
• Followed by 5.25% NaOCl (removes organic component)
• Final flush: saline or EDTA

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15. Reamers and Files

• Cross-section: triangular or square
• Cutting action: primarily rotational (quarter-turn and pull motion)
• Fewer flutes per unit length compared to files
• More rigid
• Used for enlarging/reaming the canal

• Cross-section: square or rhomboidal
• Made by twisting a blank
• Cutting action: push-pull (filing motion) AND rotation
• Available in: hand (stainless steel), NiTi rotary
• Usage: most commonly used file type

• Cross-section: S-shaped (double helix spiral)
• Made by machining (cutting flutes into a round blank)
• Cutting action: pull stroke only (very aggressive)
• Excellent for removing GP (retreatment)
• Danger: fractures easily if rotated
• Usage: canal enlargement, GP removal

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16. Laws of Access Cavity Preparation

1. Law of Centrality: The floor of the pulp chamber is always located in the center of the tooth at the level of the cemento-enamel junction (CEJ).
2. Law of Concentricity: The walls of the pulp chamber are always concentric to the external surface of the tooth at the level of the CEJ.
3. Law of CEJ: The CEJ is the most consistent and reliable landmark to determine the position of the pulp chamber floor and canal orifices.
4. Law of Color Change: The color of the pulp chamber floor is always darker than the walls.
5. Law of Orifice Location: Canal orifices are located at the point angles (corners) of the floor and canal orifice positions are symmetrical except for the mesiobuccal root of upper molars.
6. Law of Symmetry (1): Except for maxillary molars, canal orifices are equidistant from a line drawn in the mesiodistal direction through the central groove.
7. Law of Symmetry (2): Except for maxillary molars, if a line is drawn across the orifice of one canal, the other canal orifice will be found on the opposite side.

• Round bur (#2 or #4) for initial access through enamel
• Safe-ended bur (Endo-Z, Endo-Access) for removing roof of pulp chamber without gouging floor
• Remove all caries and unsupported enamel
• Achieve straight-line access to canal orifices

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17. Injectable Gutta Percha Systems

• GP pellets heated in a gun; injected through 23- or 25-gauge needles
• Used for backfill after apical plug (continuous wave technique)
• Can fill the entire canal system
• Risk of overfill and shrinkage if technique not controlled

• Alpha-phase GP in pre-loaded metal cannulas
• Cannula heated in oven, placed in gun, injected
• Three types: Regular (body fill), Firm (incremental), Endoset (fast set)
• Softer fill than Obtura; less pressure

• GP-coated carrier, not strictly injectable but thermoplasticized
• Heated in Thermaprep oven; inserted into canal
• Core acts as carrier for GP

• Combines heat source (System B) + injection gun (Obtura)
• Complete system for warm vertical + backfill

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18. Classify Endodontic Instruments

1. Broaches (barbed broach, smooth broach)
2. Reamers (K-reamer, T-reamer)
3. Files (K-file, H-file, R-file, S-file, U-file)
4. Root canal condensers (spreaders, pluggers)

1. Rotary NiTi systems (ProTaper, Reciproc, WaveOne, HyFlex)
2. Gates-Glidden drills
3. Peeso reamers (Largo drills)
4. Lentulo spirals (sealer placement)

1. Ultrasonic files (K-file + ultrasonic energy)
2. Sonic systems (Endoactivator)

1. Exploring: K-files (#8, #10)
2. Debridement: H-files, barbed broaches
3. Shaping: All rotary and hand files
4. Obturation: Spreaders, pluggers, heat carriers
5. Canal preparation: Gates-Glidden, Peeso reamers
6. Surgical: Ultrasonic retrotips, microfiles

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19. Spreaders and Pluggers

• Long, pointed, tapered instruments
• Used for lateral condensation of GP (push sideways + apically)
• Motion: apical pressure + rotation
• Available as: finger spreaders (preferred - better tactile sense) and D-type (handle) spreaders
• Sizes correspond to GP cone sizes (A, B, C or Fine, Fine-Medium, Medium)

• Flat-ended, blunt-tipped instruments
• Used for vertical condensation of GP (push GP apically/downward)
• Used in warm vertical condensation technique
• Available in graduated sizes (numbers 8-11 or letter sizes)

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20. Apexogenesis [2M]

• Apexogenesis: Pulp is VITAL → continued root development possible
• Apexification: Pulp is NON-VITAL → only barrier formation, no further development

1. Remove only coronal infected pulp (Cvek/partial pulpotomy or full pulpotomy)
2. Hemostasis with saline
3. Place biocompatible material (MTA, Biodentine, Ca(OH)2) on pulp stumps
4. Restore with GIC + composite
5. Monitor radiographically every 6 months
6. Root continues to develop to full length (increased length + thicker walls)
7. Once root is fully formed: complete RCT if needed

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21. Apical Foramen and Constriction

1. Apical Constriction (Minor Diameter/CDJ):
   • Narrowest part of root canal
   • Located 0.5-1.0 mm from radiographic apex
   • Represents the cemento-dentinal junction (CDJ)
   • Ideal termination point for preparation and obturation
   • Has least blood supply disturbance if respected
2. Apical Foramen (Major Diameter):
   • Actual opening of root canal at root apex
   • Larger than constriction
   • May not coincide with anatomical apex (may be lateral in 30% of cases)
   • Working length should terminate at constriction, NOT the foramen
3. Anatomical Apex:
   • Tip of the root (visible on radiograph)
   • May not coincide with apical foramen (offset by 0-3 mm)

• CDJ diameter: 0.23 mm (young) to 0.28 mm (old) - minor diameter
• Foramen diameter: 0.50 mm (young) to 0.68 mm (old) - major diameter
• CDJ to foramen: 0.5 mm (young) to 0.67 mm (old)

• Obturation should end at constriction (0.5-1.0 mm from radiographic apex)
• Over-instrumentation beyond foramen causes pain, delayed healing
• Apex locators measure the CDJ electronically

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22. Uses of MTA

1. Apexification (MTA apical plug)
2. Apexogenesis (vital pulp therapy)
3. Direct and indirect pulp capping
4. Pulpotomy
5. Perforation repair (furcation, cervical, midroot)
6. Root-end filling (retrograde)
7. Resorption defect repair
8. Internal/external resorption management

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23. Sterilization of Endodontic Instruments

• 121°C at 15 psi for 15-20 minutes (gravity cycle)
• 134°C at 30 psi for 3-4 minutes (pre-vacuum cycle)
• Kills all organisms including spores
• Most reliable; no residue
• Compatible with most stainless steel instruments (repeated cycles weaken NiTi)

• 160°C for 2 hours OR 170°C for 1 hour
• Good for instruments that might corrode with steam
• Slower; not suitable for plastic handles

• Formaldehyde + alcohol + water under pressure (131°C, 20 psi, 20 min)
• No rust/corrosion of instruments
• Requires special chemical solution

• Cold sterilization; 55°C, 12+ hours
• Used for heat-sensitive materials (rubber goods, NiTi single-use files)
• Toxic, requires long aeration time

• 10 hours for sterilization, 20-30 minutes for disinfection
• Cold sterilization of heat-sensitive items
• Cidex (activated glutaraldehyde)

• 217-232°C for 10 seconds
• Quick chairside method for individual files
• Not recommended by CDC (insufficient penetration for spores)

• WaveOne, Reciproc - designed for single patient use
• Eliminates cross-contamination concerns with NiTi

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24. Chlorhexidine

• Binds to hydroxyapatite in dentin and slowly releases over 48-168 hours
• Provides residual antimicrobial action

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ADDITIONAL INSTRUMENTS (Second Table)

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25. Gutta Percha

• Alpha phase: Crystalline, flexible, tacky when heated; used in thermoplasticized techniques
• Beta phase: Used in standardized GP cones (stiffer, less tacky)

• Gutta percha: 19-22%
• Zinc oxide: 59-75%
• Wax/resin: 1-4%
• Metal sulfates (radiopacifiers): 1-17%

• Radiopaque
• Biocompatible (non-toxic, non-carcinogenic)
• Dimensionally stable
• Easily removed with solvents (chloroform, xylene, halothane) for retreatment
• Softens at 65°C, flows at 100°C
• No antibacterial property (needs sealer)
• Non-adhesive to dentin (needs sealer)

1. Standardized cones: Match ISO file sizes (0.02 taper); used in lateral condensation
2. Non-standardized/conventional cones: Variable taper; used in vertical condensation (master cone, fine-fine, fine, medium, large)

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26. Gates-Glidden Drills

• #1 (yellow): 0.5 mm diameter
• #2 (red): 0.7 mm
• #3 (blue): 0.9 mm
• #4 (green): 1.1 mm
• #5 (black): 1.3 mm
• #6 (white): 1.5 mm

1. Coronal flaring (most common use)
2. Removing GP in retreatment (coronal 2/3)
3. Post-space preparation
4. Opening calcified canals

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27. H-Files (Hedstrom Files)

1. Canal enlargement by filing action
2. Removing GP in retreatment (most efficient)
3. Straightening curved canals (post-prep)
4. Used with step-back technique

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28. Recapitulation

1. Re-establish working length (counteract shortening)
2. Prevent canal blockage by removing dentin debris
3. Maintain apical patency (prevent packing of debris at apex)
4. Prevent ledge formation

• After each step-back instrument, return MAF to full working length
• Rotate gently, irrigate, withdraw
• Confirm WL is maintained before proceeding to next larger instrument

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29. Classification of Pulp Protective Agents

1. Pulp capping agents (direct contact with pulp): Ca(OH)2, MTA, Biodentine
2. Cavity liners (thin layer, seal tubules, release fluoride): Ca(OH)2, GIC, RMGIC
3. Cavity bases (thick layer, thermal insulation): ZOE, ZPC (zinc phosphate cement), GIC, RMGIC
4. Desensitizing agents: Fluoride varnishes, oxalate salts

1. Thermal insulators: Ca(OH)2 liner, ZOE, ZPC
2. Sedatives/Obtundents: Ca(OH)2, ZOE (eugenol has sedative effect)
3. Antibacterial: Ca(OH)2, ZOE, CHX-containing liners
4. Hard tissue inducers: Ca(OH)2, MTA, Biodentine

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30. Antibiotic Pastes as Intracanal Medicaments

• Metronidazole + Ciprofloxacin + Minocycline
• Proportions: 1:1:1
• Used in regenerative endodontics, LSTR therapy
• Problem: Minocycline causes crown discoloration

• Replace minocycline with clindamycin or amoxicillin

• Metronidazole + Ciprofloxacin
• Preferred in regenerative endodontics (avoids staining)

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31. AH Plus Sealer

• Paste A (resin): Bisphenol-A epoxy resin + zirconium oxide + calcium tungstate + aerosil
• Paste B (hardener): Adamantane amine + dibenzylamine + TCD-diamine + zirconium oxide + aerosil

• Long working time (~8 hours)
• Low solubility (virtually insoluble)
• Excellent dimensional stability (0.1% shrinkage only)
• High radiopacity
• Excellent adhesion to dentin (via covalent bonds with free amine groups in dentin)
• Low cytotoxicity once set
• Fills dentinal tubules (penetration)

• Sealer with GP (lateral or vertical condensation)
• Superior bond strength compared to ZOE sealers

• Slight discoloration (amine groups may cause staining)
• Technique-sensitive mixing
• May be difficult to remove for retreatment

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32. Pulp Capping

• Pinpoint mechanical/traumatic exposure (<1 mm) in healthy pulp
• Minimal hemorrhage, controlled by saline within 10 minutes
• No signs of irreversible pulpitis
• Young patient (better healing potential)
• Mature or immature tooth with vital pulp

• Carious exposure (contaminated pulp)
• Hemorrhage uncontrollable within 10 minutes
• Irreversible pulpitis (spontaneous pain)

1. Rubber dam isolation (mandatory)
2. Remove caries under magnification
3. Hemorrhage control with saline-soaked cotton
4. Place MTA/Biodentine on exposed pulp site (2-3 mm thickness)
5. Restore coronally with GIC + composite (good coronal seal essential)
6. Monitor: vitality test at 3, 6, 12 months; radiograph at 6, 12 months

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33. Masserann Kit

1. Trephine burs (tube-shaped hollow drills): Create a trough around the separated instrument to loosen it
2. Masserann tube extractor: Hollow tube with internal mechanism to grip the instrument
3. Key/driver: Rotates the tube to engage and unscrew/withdraw the fragment
4. Available in sizes to match common fragment diameters

1. Locate the fractured instrument (CBCT/radiograph)
2. Gain straight-line access with Gates-Glidden or ultrasonic
3. Select trephine bur slightly larger than fragment diameter
4. Trephine creates trough around fragment (1-2 mm depth)
5. Place extractor tube over fragment
6. Activate internal mechanism to grip fragment
7. Rotate counter-clockwise to unscrew and withdraw

• Ultrasonic technique (most commonly successful): Ultrasonic tip placed next to fragment; vibration loosens it
• IRS (Instrument Removal System) - Meitrac, Endo Extractor
• Bypass and leave in place (if in apical third of curved canal)
• Surgical retrieval (last resort)

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34. Peeso Reamers (Largo Drills)

1. Post-space preparation (most common use) - creates space for intraradicular post after RCT
2. Orifice opening and coronal flaring
3. Removing GP during retreatment (coronal portion)

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35. Root-End Filling Materials (Retrograde/Retrofilling Materials)

• Good marginal seal (no microleakage)
• Biocompatible
• Insoluble in tissue fluids
• Promotes hard tissue formation
• Radiopaque
• Bacteriostatic
• Easily manipulated
• Sets in presence of moisture

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36. Retrograde Filling Materials

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37. EDTA (Ethylenediaminetetraacetic Acid)

1. Smear layer removal (inorganic component) - used as final rinse before obturation
2. Canal lubricant (RC-Prep, File-Eze - EDTA + urea peroxide in glycol) - facilitates instrumentation
3. Negotiating calcified canals (EDTA gel placed before fine files)
4. Combined with NaOCl: complete smear layer removal

• 17% EDTA (1 minute) → saline flush → 5.25% NaOCl (1 minute) → saline flush
• Removes both organic (NaOCl) + inorganic (EDTA) components

• EDTA liquid: 17% for irrigation
• EDTA gel (RC-Prep, File-Eze): lubricant during instrumentation
• EDTAC: EDTA + Cetrimide (surfactant) - better penetration

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38. Twist Drills

• Creating space for cast post and core or prefabricated posts
• Similar function to Peeso reamers

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39. K-Files

1. Canal exploration (#8, #10)
2. Working length determination
3. Canal preparation (step-back, crown-down)
4. Patency filing

• Standard K-file: For canal shaping
• K-Flex file: More flexible (rhomboidal cross-section), better in curved canals
• Flex-R file: For balanced force technique (rounded tip)

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40. Zipping

• Loss of apical constriction (cannot create apical stop)
• Over-instrumentation beyond apex
• Sealer/GP extrusion
• Post-operative pain
• Reduced healing prognosis

• Pre-curve files before insertion in curved canals
• Use flexible NiTi files
• Crown-down technique (reduces stress on apical files)
• Balanced force technique
• Step-back technique with recapitulation
• Do not skip file sizes

• Re-establish WL carefully
• Use fine file to re-check true WL
• If severe, consider re-routing or accept compromised seal (augment with warm GP)

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41. Dens Invaginatus (Dens in Dente)

• Type I: Invagination is enamel-lined and confined within crown; does not extend beyond CEJ
• Type II: Invagination extends beyond CEJ into root but remains within root canal system
• Type III: Invagination extends beyond CEJ and communicates with periodontal ligament or perforates at apex; severe form

• Deep foramen caecum (palatal pit) - pathognomonic
• Barrel-shaped or conical crown
• Often asymptomatic until pulp becomes necrotic (due to thin enamel lining of invagination allowing bacterial entry)
• Early pulp necrosis (often in young patients)

• "Tooth within a tooth" appearance
• Radiopaque teardrop or loop within root canal
• Widely open apex (immature)

• Type I: Prophylactic sealing of foramen caecum with resin
• Type II: RCT of invagination + main canal (complex anatomy)
• Type III: Surgery (apicoectomy) + MTA retrograde fill; extraction in severe cases

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42. Minor and Major Diameter

• Narrowest part of root canal - located 0.5-1.0 mm from radiographic apex
• Represents CDJ (cemento-dentinal junction)
• Average: 0.23-0.28 mm
• Ideal termination point for canal preparation and obturation

• The wider opening at or near the anatomic apex
• Average: 0.50-0.68 mm
• Actual exit of root canal system
• May be on the side of apex (not always at tip)

• Files should be sized to the minor diameter (creates apical stop)
• Obturation should terminate at minor diameter
• Electronic apex locators detect the major diameter (CDJ-foramen junction)

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43. Microbial Flora of Root Canals

• Predominantly obligate anaerobes:
  • Fusobacterium nucleatum
  • Prevotella intermedia / melaninogenica
  • Porphyromonas gingivalis
  • Peptostreptococcus species
  • Bacteroides species
  • Treponema denticola
  • Actinomyces species

• Enterococcus faecalis - most important; gram-positive, facultative anaerobe
• Resists Ca(OH)2 (survives alkaline pH via proton pump)
• Resists starvation
• Forms biofilms (invades dentinal tubules up to 500 μm)
• This is why CHX (2%) and TAP are used in failing cases

• Streptococcus (microaerophilic)
• Fusobacterium
• Spirochetes

• Microorganisms exist as organized biofilm communities (not planktonic)
• Biofilms are resistant to antibiotics and irrigants
• NaOCl + EDTA + ultrasonic agitation most effective against biofilms

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SECTION 4: TRAUMA, ENDO-PERIO, SURGERY, DISCOLORED TEETH

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44. Fracture of Maxillary Central Incisor Involving Dentin - Trauma Management (18-year-old, 1 month ago)

• Class II (Ellis) = Crown fracture involving enamel AND dentin WITHOUT pulp exposure
• After 1 month: dentin may have secondary dentin response; evaluate pulp vitality carefully

1. Pulp vitality test (thermal + EPT) - check if pulp is still vital
2. Periapical radiograph - check root fracture, periapical status
3. Check for pulp exposure at fracture surface

1. Dentin desensitization - GIC liner over exposed dentin
2. Composite resin restoration (most esthetic, immediate)
3. Reattachment - if patient brings original fragment, can be reattached with composite
4. Long-term: crowns/veneers if extensive

1. Root canal treatment (pulpectomy + RCT)
2. Consider MTA apical plug if apex is immature (at 18, may still be developing)
3. Bleaching if tooth is discolored after RCT
4. Composite restoration or crown

• Consider direct pulp cap with MTA if just exposed
• Or interim Ca(OH)2 dressing + monitor

• Indication: Vital tooth discoloration
• Material: 10-22% carbamide peroxide (in custom tray)
• Technique:
  1. Alginate impressions + study models
  2. Fabricate custom soft vinyl bleaching tray (reservoir technique - slight space over tooth)
  3. Patient loads tray with small amount of bleaching gel
  4. Wears overnight (6-8 hours) or 2-4 hours during day
  5. Duration: 2-6 weeks
• Mechanism: Carbamide peroxide → H2O2 + urea → H2O2 oxidizes chromogenic molecules
• Side effects: Temporary sensitivity, gingival irritation (from ill-fitting tray)
• Contraindications: Pregnancy, severe sensitivity, caries/active disease

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45. Classify Tooth Discolorations and Causes

1. Pulpal causes:
   • Pulp necrosis/hemorrhage - grey/black (hemoglobin breakdown products)
   • Internal resorption - pink (vascular granulation tissue)
   • Calcification - yellow-brown
2. Developmental causes:
   • Amelogenesis imperfecta - yellow-brown opaque
   • Dentinogenesis imperfecta - grey-blue opalescent
   • Enamel hypoplasia - white/yellow-brown spots
   • Fluorosis - white spots (mild) to brown-black pitting (severe)
   • Tetracycline staining - yellow-grey-brown banding (dose and timing dependent; given before age 8)
   • Erythroblastosis fetalis - green/blue-green (bilirubin)
3. Metabolic disorders:
   • Porphyria - red-brown (porphyrins deposited)
   • Alkaptonuria - brown-black
   • Congenital hyperbilirubinemia - yellow-green

1. Yellow: Plaque, poor oral hygiene, tobacco
2. Brown: Tea, coffee, tobacco, tobacco products
3. Black/Green: Chromogenic bacteria, iron supplements
4. Orange: Chromogenic bacteria (Serratia marcescens)
5. Green: Chromogenic bacteria (Penicillium, Aspergillus) on cervical enamel

• Coronal leakage of blood from instrumentation
• Residual pulp tissue
• ZOE sealer (slight yellowing)
• AH26 sealer (grey/brown - silver mirror reaction)
• Grey MTA (crown discoloration)
• Ledermix (yellow stain)

• Extrinsic: Professional cleaning, polishing
• Intrinsic mild: External bleaching (night guard)
• Intrinsic severe (tetracycline): Veneers, crowns
• Non-vital tooth: Walking bleach (sodium perborate) or thermocatalytic bleaching

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Exam Tip: For short-answer topics (2M questions), focus on: definition, composition/classification, and clinical significance. For long-answer topics (10M+), always structure as: definition → classification → etiology → clinical features → diagnosis → management. This systematic approach maximizes marks.

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ENDODONTICS - Complete Answer Guide (Page 3)

Trauma, Endo-Perio Lesions, Surgery, Discolored Teeth & Miscellaneous

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Previously covered (from Page 2 overlap):

• Dens invaginatus, Minor/Major diameter, Microbial flora of root canals - answered in previous session
• 18-year-old dentin fracture, Tooth discoloration classification + Night guard bleaching - answered in previous session

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NEW TOPICS:

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1. Enumerate Causes of Discoloration of Teeth + Treatment Options for Discolored Anterior Teeth

• Yellow: Plaque, poor oral hygiene
• Brown: Tea, coffee, tobacco, tobacco products, chlorhexidine long-term use, iron supplements
• Black: Chromogenic bacteria (anaerobes), iron/bismuth salts
• Green/Orange: Chromogenic bacteria (Penicillium, Aspergillus) on cervical enamel
• White patches: Demineralization (early caries)

• Fluorosis: White opaque spots (mild) → brown/black pitting (severe); due to excess fluoride during enamel formation
• Tetracycline staining: Yellow-grey-brown horizontal banding; dose and timing-dependent; exposure before age 8; cannot be bleached (severe cases need veneers/crowns)
• Amelogenesis imperfecta: Yellow-brown opaque enamel
• Dentinogenesis imperfecta: Blue-grey opalescent (amber), shell teeth
• Enamel hypoplasia: White/yellow-brown spots or pits

• Pulp necrosis + hemorrhage: Grey-black (hemosiderin, hemin, hematin from hemoglobin breakdown)
• Internal resorption: Pink tooth (vascular granulation tissue visible through crown)
• Calcific degeneration: Yellow-brown (secondary/tertiary dentin obliterates pulp)
• Residual pulp tissue after RCT: Brown staining
• Sealer/medicament penetration: AH26 (grey-brown), Ledermix (yellow), Grey MTA (dark grey)

• Erythroblastosis fetalis / neonatal jaundice: Green-blue (bilirubin)
• Porphyria: Red-brown (porphyrins)
• Alkaptonuria: Brown-black

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2. Ellis Class III Fracture

• Class I: Fracture limited to enamel only
• Class II: Fracture involving enamel + dentin (no pulp exposure)
• Class III: Fracture involving enamel + dentin + PULP EXPOSURE (vital pulp)
• Class IV: Non-vital tooth (pulp necrosis regardless of fracture extent)
• Class V: Tooth avulsion
• Class VI: Root fracture with or without crown fracture
• Class VII: Tooth displacement without fracture
• Class VIII: Fracture of entire crown
• Class IX: Fractures of primary (deciduous) teeth

• Visible pink/red dot at fracture surface (exposed pulp)
• Bleeding from pulp
• Exquisite sensitivity to air/temperature
• Usually in young patients due to trauma

• Direct pulp cap (MTA/Biodentine): If exposure ≤1 mm, controlled hemorrhage, young patient
• Cvek partial pulpotomy: Remove 2 mm of pulp tissue; MTA over remaining pulp; high success

• Full pulpotomy (cervical): Remove coronal pulp to cervical level; MTA over radicular pulp stumps
• Best for immature teeth (apexogenesis goal)

• Pulpectomy + RCT (complete root canal treatment)

• Apexogenesis (if pulp viable): partial pulpotomy + MTA → allows root development
• Apexification (if pulp necrotic): Ca(OH)2 or MTA apical plug

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3. Endo-Perio Lesions (Endodontic-Periodontal Lesions)

1. Apical foramen (main pathway)
2. Lateral/accessory canals (especially in furcation of molars)
3. Dentinal tubules (exposed at root surface after attachment loss)

• Infection starts in pulp → spreads via apex/lateral canals → appears as periodontal lesion
• Pulp: non-vital
• Probing: narrow, deep pocket along root; sinus tract on probing
• Treatment: RCT alone; heals completely after successful RCT
• Prognosis: Good

• Periodontitis destroys attachment → involves apex → may secondarily affect pulp (late)
• Pulp: usually vital initially
• Probing: wide, generalized pocketing; pattern consistent with periodontitis
• Treatment: Periodontal treatment alone (SRP, surgery)
• Prognosis: Depends on periodontal response

• Primary endo lesion + primary perio lesion exist simultaneously and merge
• Both pulp necrosis AND periodontal attachment loss
• The two lesions communicate
• Treatment: Both RCT AND periodontal treatment required
• Prognosis: Guarded to poor (worst prognosis)

• Endo lesion present long enough to cause secondary periodontal breakdown
• Treatment: RCT first → periodontal treatment if residual pocketing remains
• Prognosis: Moderate

• Periodontal disease progresses to apex → causes pulp necrosis
• Treatment: RCT + periodontal treatment
• Prognosis: Poor (extensive bone loss)

• Both endo and perio disease present independently without communication
• Each treated separately

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4. Replantation - Indications and Procedure

1. Intentional replantation: Planned removal, treatment (retrograde fill), and replantation of tooth that cannot be treated in situ
2. Emergency replantation: After accidental tooth avulsion

• Avulsed permanent tooth
• Patient presents promptly (within 60 minutes, ideally within 15-30 min)
• Good periodontal condition
• Mature/immature tooth
• No systemic contraindications

• Tooth inaccessible for conventional RCT (severely tipped, curved)
• Fractured instrument at apex not retrievable
• Root perforation non-manageable
• Failed apicoectomy
• Periodontal-endodontic lesions (combined approach)
• Insurance/economic reasons (instead of implant)

• Grossly carious/non-restorable tooth
• Severe periodontitis (no attachment support)
• Fractured root
• Systemic conditions (immunosuppression, bisphosphonates)
• Tooth out of socket > 60 minutes dry (poor prognosis)
• Primary (deciduous) teeth (avoid damage to underlying permanent tooth)

• Hold by crown only; never touch root surface
• If contaminated: rinse gently with saline for 10 seconds only (not scrub)

• Best: replant immediately (no storage needed)
• Hank's Balanced Salt Solution (HBSS) - best storage medium (maintains PDL viability up to 24 hours)
• Cold fresh milk - 30-60 minutes viability
• Saline - 30 minutes
• Saliva (buccal vestibule) - 30-120 minutes
• Water - worst (hypotonic, kills PDL cells)

• Irrigate socket with saline; remove coagulum gently
• Examine for alveolar fracture
• Confirm tooth viable; necrotic PDL scrubbed off only if >60 min dry

• Gentle digital pressure to reposition tooth in correct orientation
• Confirm position radiographically
• Apply flexible splinting (wire + composite or Essix splint)
• Splint duration: 7-10 days (avulsion with intact socket)
• Longer splinting causes ankylosis

• Immature tooth: Monitor; if pulp revascularizes (takes 4-6 weeks) - no RCT needed initially; if necrosis develops - apexification or regenerative RCT
• Mature tooth: RCT within 7-14 days (before splint removal); Ca(OH)2 dressing placed initially

• Soft diet, avoid trauma to area for 2-4 weeks
• Antibiotics (Doxycycline 100 mg BD for 7 days OR Amoxicillin)
• Tetanus prophylaxis (if contaminated tooth)
• Chlorhexidine mouthwash
• Review: 1 week, 1 month, 3 months, 6 months, 1 year, then annually (watch for resorption)

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5. Walking Bleach Technique

1. Pre-operative assessment:
   • Confirm completed RCT on radiograph
   • Confirm sealed apex
   • Inform patient (may need multiple visits)
2. Access cavity: Open access (if sealed) under rubber dam
3. Remove GP from pulp chamber to 2 mm below CEJ level (do NOT bleach below CEJ - risk of cervical resorption)
4. Cervical seal (Protective base):
   • Place 2 mm thick GIC or ZOE base at level of CEJ
   • This prevents bleaching agent seeping into root canal below CEJ and into periodontal ligament through cementum (prevents cervical resorption)
5. Prepare bleaching agent:
   • Sodium perborate (anhydrous or tetrahydrate) + water: Safest combination; minimal cervical resorption risk
   • Mix to thick paste consistency
   • Superoxol (30% H2O2) + sodium perborate: More effective but higher resorption risk (not recommended)
6. Place paste into pulp chamber; seal with Cavit or IRM (temporary restoration)
7. Review in 3-7 days: Check lightening; replace if needed
8. Repeat until satisfactory shade (usually 2-4 visits)
9. Final restoration: Once desired shade achieved:
   • Remove bleaching paste
   • Irrigate with saline
   • Wait 2-3 weeks before bonding composite (peroxide interferes with bonding)
   • Restore access with composite or crown

• Cervical/external root resorption (most serious): Due to H2O2 penetrating through cementum via dentinal tubules → inflammatory resorption
• Reduced bond strength if composite placed immediately
• Relapse of color (may need re-treatment)

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6. Management of Avulsed Tooth

• Replant immediately
• Flexible splint 7-10 days
• RCT within 7-14 days (mature tooth)
• Ca(OH)2 for 1 month before obturation

• PDL cells are necrotic; don't try to preserve PDL
• Soak tooth in 2% sodium fluoride for 20 min (hardens root surface against resorption)
• RCT before or after replantation
• Replant (will eventually ankylose and be lost due to replacement resorption, but maintains space in young patients)
• Decoronation when ankylosis confirmed (to maintain bone volume for future implant)

1. HBSS (Hank's Balanced Salt Solution) - best (up to 24 hours)
2. Cell culture media (ViaSpan)
3. Coconut water (emerging evidence)
4. Cold milk - 30-60 min
5. Saliva - 30-120 min
6. Saline
7. Water - worst

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7. Management of Root Fractures

1. Cervical third root fracture (most unfavorable prognosis)
2. Middle third root fracture
3. Apical third root fracture (best prognosis)

• Mobility, tenderness to percussion, extrusion
• Pain on biting
• Pulp may or may not be vital

• Horizontal radiolucent line across root
• Multiple periapical radiographs at different angles (90°, 45° mesial and distal)
• CBCT (most accurate for detection)

• Most favorable; PDL intact between fragments
• Pulp usually remains vital
• Monitor; no immediate treatment often needed
• If pulp necrosis develops: RCT of coronal fragment only (apical fragment need not be treated if asymptomatic)
• Prognosis: Good

• Reposition (if displaced) and flexible splint for 4 weeks
• Vitality monitoring at regular intervals
• If pulp survives: successful healing with calcified tissue/connective tissue between fragments
• If necrosis: RCT of coronal segment; Ca(OH)2 dressing; MTA at fracture level
• Prognosis: Fair

• Worst prognosis
• Options:
  • Extraction of coronal fragment + RCT of retained root (if root long enough) + post-crown
  • Orthodontic extrusion of apical fragment after coronal fragment removal
  • Surgical extrusion
  • Extraction of entire tooth
• Prognosis: Poor (often extraction needed)

• With calcified tissue (hard tissue bridge)
• With connective tissue (fibrous interposition)
• With bone and connective tissue
• With granulation tissue (inflammatory; due to pulp necrosis)

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8. Gingival Tissue Retraction

1. Retraction cord (most common): Cotton/braided cord placed in gingival sulcus
   • Plain cord: mechanical only
   • Medicated cord: impregnated with astringent/hemostatic agent (epinephrine, aluminum chloride, ferric sulfate)
2. Gingival retractor (mechanical tissue displacement without cord)

• Astringents: Aluminum chloride (15-25%), Aluminum sulfate
• Hemostatics: Ferric sulfate (20%), Epinephrine (racemic)
• Applied to cord or directly to sulcus

• Most effective combination: medicated retraction cord
• Cord impregnated with aluminum chloride or epinephrine

• Rotary curettage: Removing sulcular epithelium with rotating bur
• Electrosurgery: Cautery unit removes gingival tissue; used with caution near bone
• Laser: Diode laser for tissue removal and hemostasis

• Expasyl (aluminum chloride 15% + kaolin clay)
• Injected into sulcus; forms plug; washed away after 1-2 minutes
• Newer, easier alternative to cord

1. Select cord size (000, 00, 0, 1, 2) matching sulcus depth
2. Cut cord to length (tooth circumference)
3. Tuck cord into sulcus with packing instrument (cord packer)
4. Overlap ends slightly; leave a tail for removal
5. Leave in place 5-8 minutes (medicated cord); remove gently before impression
6. Irrigate sulcus with water/air

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9. Flap Designs in Endodontic Surgery

• Adequate access and visibility
• Blood supply preserved
• Clean incisions through healthy tissue
• Vertical releasing incisions away from bony defects
• Allow passive, tension-free repositioning
• Primary closure without tension

1. Triangular (Two-sided) Flap:
   • Horizontal incision in sulcus + ONE vertical releasing incision
   • Good access for single-rooted teeth
   • Minimal tissue trauma
2. Rectangular (Three-sided) Flap:
   • Horizontal sulcular incision + TWO vertical releasing incisions
   • Better access for multi-rooted/multiple teeth
   • Wider surgical field
   • Most commonly used in endodontic surgery
3. Trapezoidal Flap:
   • Two vertical incisions wider at base than at sulcus
   • Wider access, preserves blood supply
   • Less prone to necrosis
4. Semilunar (Luebke-Ochsenbein) Flap:
   • Curved horizontal incision in attached gingiva (not in sulcus)
   • Used when sulcular incision should be avoided (crowns, bridges)
   • Does NOT reflect marginal gingiva
   • Limitation: limited access; scar line visible; should be in attached gingiva only
5. Palatal Flap:
   • Horizontal incision on palatal aspect
   • Used for palatal roots of maxillary molars

• Less commonly used; leaves periosteum on bone

• Use No. 15 blade in one stroke
• Avoid incision over bony defects or prominences
• Vertical releasing incisions must be in attached gingiva (not in frenum or papilla)
• Base of flap must be wider than apex for vascular supply

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10. Vital Bleaching of Teeth

• Intrinsic staining (mild fluorosis, age-related yellowing)
• Extrinsic staining resistant to polishing
• Tetracycline (Grade I-II)
• General tooth lightening

• Pregnancy/lactation
• Children under 18 (pulps large)
• Unrealistic patient expectations
• Tetracycline Grade III-IV (bleaching alone insufficient)
• Active caries, periodontal disease

• 35-40% hydrogen peroxide gel
• Applied to teeth; light/laser activation (optional - evidence equivocal)
• Rubber dam or liquid dam to protect gingiva
• Multiple sessions (3 x 15 minutes in one appointment)
• Fastest results
• Side effects: Significant sensitivity, gingival irritation

• 10-22% carbamide peroxide in custom tray
• Worn overnight or 2-4 hours/day
• 2-6 weeks
• Gold standard for safety and efficacy

• Whitening strips (6-14% H2O2)
• Whitening toothpastes (abrasive + low peroxide)
• Less effective than professional bleaching

• Tooth sensitivity (most common) - temporary; use desensitizing toothpaste (potassium nitrate 5%)
• Gingival irritation (tray leakage)
• Cervical resorption risk (with intracoronal use of 30% H2O2)
• Enamel surface changes (minimal with professional products, remineralizes)
• Reduced bond strength immediately after bleaching (wait 2-3 weeks before bonding)

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11. Role of Ultrasonics in Endodontics

1. Acoustic streaming - fluid flow patterns around vibrating file; enhances irrigant penetration and kill bacteria
2. Cavitation - formation and implosion of micro-bubbles in irrigant; releases energy that disrupts bacterial cells and debris

• Passive Ultrasonic Irrigation (PUI): Ultrasonic file in canal after shaping, with NaOCl; greatly enhances cleaning vs. syringe irrigation alone
• Disrupts smear layer and biofilm

• Ultrasonic tip placed alongside fragment
• Vibration loosens fragment; can be retrieved
• Most commonly successful method

• Ultrasonic tips to remove calcific deposits at canal orifice
• Troughing around calcified orifices

• Cleaning perforation site before MTA placement

• Ultrasonic retrotip (micro-sonic tip) creates 3 mm deep, centered cavity in root end
• Far superior to bur-prepared retrograde cavity (better centered, less microcrack formation)

• Ultrasonic energy loosens cemented posts

• Ultrasonic tips (e.g., Endo-Chuck) for refining access, troughing

• Creating troughs to locate MB2 canal in upper molars

• Magnetostrictive (Cavitron, Amdent): metal stack converts energy
• Piezoelectric (most common, more precise): crystal stack; less heat generated; preferred in endodontics

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12. Root Resection (Root Amputation)

• Hemisection: Cutting tooth in half (crown + root)
• Bicuspidization: Splitting mandibular molar into two premolar-like units

• Severe vertical bone loss on one root only (furcation-involved root)
• Root fracture on one root
• Perforation on one root (non-repairable)
• External root resorption on one root
• Inaccessible canal (calcified, curved) on one root causing failure
• Furcation involvement (Class III) where one root can be sacrificed

• RCT must be completed on all remaining roots
• Adequate bone support for remaining roots
• Periodontal health of remaining roots
• Restorable tooth

1. RCT of all canals first
2. Reflect mucoperiosteal flap
3. Identify root to be removed
4. Sectioning with fissure bur at furcation level
5. Remove root with extraction forceps/elevator
6. Round off sharp edges of remaining root trunk
7. Irrigate, suture flap
8. Final restoration: crown on remaining roots

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13. Trephination

• Severe acute abscess with inaccessible canal (calcified, failed instrumentation)
• Acute abscess where drainage cannot be established through canal
• Phoenix abscess with cortical bone intact (no fluctuance)
• Emergency pain relief when conventional drainage not possible

1. Local anesthesia
2. Identify abscess location radiographically
3. Reflect small flap or needle through soft tissue
4. Drill through cortical bone with round bur at apex location
5. Allow pus to drain
6. Irrigate with saline
7. Suture

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14. Gingival Retraction Cord

• Cotton or braided synthetic cord placed in gingival sulcus
• Sizes: 000 (finest) → 0 → 1 → 2 (thickest)
• Types: Braided, twisted, knitted
• Medications: Aluminum chloride (15-25%), epinephrine, ferric sulfate
• Brands: Gingi-Pak, Ultradent UltraPak, Gingibraid
• Purpose: Laterally displace gingiva + reduce crevicular fluid for accurate impressions
• Duration: 5-8 minutes (medicated); 10-15 min (plain)
• Caution: Epinephrine-impregnated cord avoided in cardiovascular patients

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15. Post and Core

1. Post: Extends into root canal; provides retention for core
2. Core: Replaces lost coronal tooth structure; serves as foundation for crown

• Less than 50% of coronal tooth structure remaining
• Insufficient dentin for core retention
• Anterior teeth with little remaining structure

• Fabricated in lab from impression of canal
• Gold alloy (traditional) or nickel-chromium
• Excellent fit; used for severely damaged teeth
• Time-consuming, requires 2 visits

• Remove GP with Peeso reamers/hot plugger
• Leave 4-5 mm apical seal (GP remaining)
• Post length: 2/3 of root length OR equal to crown length OR half the bone-supported root
• Post diameter: maximum 1/3 of root diameter (risk of root fracture if wider)

• Resin cements (Panavia, RelyX) preferred
• Glass ionomer cements also used

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16. Fiber-Reinforced Composite (FRC) Post

• Carbon fiber posts: Black colored; earliest FRC; high strength but opaque (esthetics poor)
• Glass fiber posts: White/translucent; allows light transmission; most widely used
• Quartz fiber posts: Superior aesthetics; highest translucency; flexible

1. Esthetic (tooth-colored)
2. Lower modulus of elasticity → root fracture risk reduced
3. Allows light transmission (glass/quartz) for tooth-colored restorations
4. Retreatment easier (can be drilled out)
5. No corrosion
6. Radiopaque (glass fiber posts)

• Cannot be custom-adapted to irregular canal shape
• Lower fracture resistance than metal in some studies
• Debonding (adhesive failure)

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17. McInnes Solution (Mcinne's Solution)

• Hydrochloric acid (30%): 5 parts
• Ether: 5 parts
• 30% hydrogen peroxide: 1 part

1. Rubber dam placement
2. Pumice polish
3. Apply McInnes solution on cotton pellet for 5 minutes
4. Re-apply 3-5 times
5. Neutralize with sodium bicarbonate solution
6. Polish
7. Apply fluoride varnish

• Works only for superficial discoloration (fluorosis)
• Removes enamel surface (enamel loss ~25-30 μm per treatment)
• Severe cases need composite/veneer
• Multiple sessions may be needed

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18. Hydrogen Peroxide [2M]

• 3%: Irrigant (effervescent), wound cleansing
• 30% (Superoxol): Walking bleach (historical); in-office bleaching
• 35-40%: In-office power bleaching (gels)

1. Canal irrigant (3%): Releases O2 bubbles → effervescent action → loosens debris; bactericidal
2. Component of walking bleach: 30% H2O2 mixed with sodium perborate (not recommended alone due to cervical resorption)
3. Hemostatic: Controls pulp hemorrhage
4. Bleaching agent (in-office): 35-40% H2O2 gels

• Should NOT be used together sequentially: forms gas (Cl2) + reduces efficacy of both
• Rinse with saline between these two agents

• Cervical resorption risk with high-concentration H2O2 (30%)
• Gingival and periapical tissue irritation
• Store in dark bottles (decomposes in light)

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19. Indications and Contraindications of Endodontic Surgery

• Apicoectomy (root-end resection)
• Root-end cavity preparation and filling (retrofilling)
• Root resection
• Intentional replantation

• Persistent periapical pathology despite adequate RCT
• Failure to heal after 1-2 years of observation

• Calcified/obliterated canals inaccessible by non-surgical means
• Separated instrument in apical third (non-retrievable)
• Ledge/perforation in apical third (non-manageable conservatively)
• Anatomical variations (severe dilacerations)
• Well-fitting, functional crowns/bridges where removal would be destructive

• Large periapical lesion (cyst vs granuloma) requiring histopathological diagnosis
• Suspected malignancy

• Root fracture (apical fragment removal)
• External root resorption (surgical access)
• Post-traumatic complications
• Exploration of questionable cases

• Medically compromised patient (uncontrolled diabetes, hemophilia, recent MI within 6 months, severe immunosuppression)
• Inadequate bone support (insufficient bone volume for surgery)
• Short root (insufficient root length after resection)
• Non-strategic tooth (easier to extract and place implant)
• Teeth with poor periodontal support

• Poor patient cooperation
• Limited mouth opening
• Anatomical limitations (proximity to maxillary sinus, inferior alveolar nerve, mental foramen)
• Uncontrolled hypertension
• Anticoagulant therapy (adjust, consult physician)

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20. Transport Medium for Avulsed Teeth

1. HBSS (Hank's Balanced Salt Solution / Save-A-Tooth kit) - up to 24 hours viability
2. Viaspan (University of Wisconsin cold storage solution) - 24+ hours
3. Coconut water (emerging evidence - up to 24 hours)
4. Cold whole milk - 30-60 minutes
5. Saline - 30 minutes
6. Saliva (buccal vestibule) - 30-120 minutes (concern: bacteria)
7. Water - worst; hypotonic, kills PDL cells quickly

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21. Advantages of Dental Operating Microscope (DOM)

1. Enhanced visualization of tooth anatomy (magnification + illumination)
2. Detection and location of additional canals (MB2 of upper molars - found in >70% with DOM vs. 30% without)
3. Location of calcified canal orifices
4. Detection of cracks and fractures (transillumination)
5. Improved accuracy of retrograde cavity preparation (more centered, conservative)
6. Better management of perforations, separated instruments, resorptions
7. Negotiation of calcified/complex canals
8. Improved access cavity preparation

• ADA and AAE recommend use of DOM in endodontic practice
• Significantly improves success rates of complex cases
• Allows conservative access (smaller access cavities - "ninja access")

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22. Cavitation and Acoustic Streaming

• Rapid, circular movement of fluid caused by a vibrating ultrasonic instrument in a liquid medium
• Creates shear forces in the fluid
• Disrupts bacterial biofilm, loose debris, and dentin chips from canal walls
• Enhances penetration of irrigant into lateral canals, fins, isthmuses
• Occurs even without cavitation

• Formation, growth, and implosive collapse of micro-bubbles (cavities) in liquid around vibrating ultrasonic tip
• Two types:
  • Stable cavitation: Bubbles oscillate without collapsing; acoustic streaming dominant
  • Transient (inertial) cavitation: Bubbles collapse violently → shock waves, micro-jets, extreme local temperature/pressure
• Disrupts and kills bacteria
• Loosens debris, smear layer

• Ultrasonic file (activated but NOT cutting) placed in NaOCl-filled canal after shaping
• Acoustic streaming + cavitation greatly enhance NaOCl penetration and bacterial kill
• Superior debridement compared to syringe irrigation alone
• Recommended as adjunct in complex anatomy (isthmuses, fins)

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23. Hemisection

• Root amputation/resection: Only root removed, crown retained
• Bicuspidization: Both halves RETAINED (splitting but keeping both)
• Radisection: Same as hemisection (some authors use this term)

• Severe vertical bone loss on one root of a mandibular molar
• Furcation involvement (Class III) on one root
• Root fracture involving one root
• Perforation (non-repairable) on one root
• Caries extending below bone level on one root only

• Adequate bone support for remaining half
• RCT completed on root to be retained
• Restorable remaining crown
• Good patient oral hygiene

1. Complete RCT on the root/roots to be retained
2. Local anesthesia + rubber dam
3. Vertical groove cut through crown (buccal to lingual) using fissure bur - divides tooth into mesial and distal halves
4. Remove the diseased half (crown + root) with forceps/elevator
5. Round off sharp edges of remaining root trunk
6. Evaluate remaining half clinically and radiographically
7. Restore remaining half: usually with crown (or as abutment for FPD if both halves retained = bicuspidization)

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24. Superoxol

1. Component of walking bleach (sodium perborate + Superoxol): More potent bleaching; higher resorption risk
2. In-office bleaching (historical): Applied to discolored non-vital teeth
3. Hemostatic agent (control bleeding from pulp)
4. Canal irrigation (historical; effervescent action)

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25. Bicuspidization

• Severe furcation involvement (Class II-III) in mandibular molar
• Both roots are strategically viable with adequate bone support
• Both roots have completed RCT
• Adequate crown structure on both halves

1. Complete RCT on BOTH mesial and distal roots
2. Divide crown vertically (mesio-distal section) through furcation
3. Both halves retained
4. Restore each half separately (crowns or as abutments for FPD with mesial half as one abutment, distal half as another)

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26. Uses of Lasers in Endodontics

• Nd:YAG, Er:YAG, CO2, Diode (810 nm), Er,Cr:YSGG

1. Antimicrobial/debridement: Laser energy delivered via fiber optic tips kills bacteria in canal; disrupts biofilm (Nd:YAG, Er:YAG)
2. Laser-activated irrigation (LAI): Laser tip in NaOCl → photoacoustic streaming and cavitation → superior irrigation
3. Smear layer removal: Er:YAG ablates smear layer
4. Canal preparation: Er:YAG can ablate dentin (not widely used as primary shaping)

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27. Carbamide Peroxide

• Carbamide peroxide → H2O2 (3.35%) + urea (6.65%)
• Urea further → CO2 + NH3 (ammonia - elevates pH, reduces sensitivity)

1. Night guard home bleaching (primary use): 10-22% in custom trays
2. Desensitizing agent (low concentration - urea component)
3. Wound healing (urea component)

• Slower release of H2O2 → prolonged contact time
• Less irritating
• Urea raises pH → less sensitivity
• Stable in gel form for extended wear

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28. Radisection

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29. Autoclave

• Steam enters from top; gravity forces air down and out through drain
• 121°C at 15 psi for 15-20 minutes (most common cycle)
• Suitable for unwrapped instruments and liquids

• Vacuum pump removes air before steam admission
• Better steam penetration into porous materials
• 134°C at 30 psi for 3-4 minutes
• Preferred for packaged instruments

• 132-134°C for 3-4 minutes (unwrapped)
• For instruments needed immediately

1. Physical/Mechanical monitors: Gauges, temperature/pressure recording charts
2. Chemical indicators:
   • Class 1: Process indicator (autoclave tape) - confirms exposure to steam
   • Class 5/6: Integrating indicators - confirms all sterilization parameters
3. Biological indicators: Geobacillus stearothermophilus spore strips - true test of sterilization; weekly use recommended
4. Bowie-Dick test: Air removal test for pre-vacuum autoclaves (done daily)

• Corrosion of carbon steel instruments
• Repeated cycles weaken NiTi files
• Cannot sterilize heat-sensitive materials

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30. Reattachment (Fragment Reattachment)

• Fragment must be intact and available
• Fragment fits precisely
• No caries on fragment
• Pulp treated if Class III

1. Store fragment: In water/saline if dry until procedure
2. Pulp treatment first (if Class III - direct pulp cap / pulpotomy / RCT as indicated)
3. Rubber dam isolation
4. Rehydrate fragment (if dry): soak in water 20-30 min
5. Bevel or groove preparation (optional): slight beveling of enamel margins or internal groove on both tooth and fragment to increase bond surface area
6. Acid etch both tooth surface and fragment (37% phosphoric acid, 15-30 sec)
7. Rinse, dry (but not desiccate)
8. Apply bonding agent to both surfaces; light cure
9. Apply composite resin: flowable or paste; adapt fragment precisely
10. Light cure from multiple angles
11. Check occlusion: Adjust if high
12. Polish margins

• Excellent esthetic result (original tooth color, shape, translucency)
• Biologically conservative
• Fast, single visit
• Patient-pleasing (restores original tooth)

• Fragment may darken over time (dehydration, internal staining)
• May require replacement after several years
• Bond may fail

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31. Diagnosis of Cracked Tooth

• Sharp pain on biting (especially on release)
• Cold sensitivity (lingering)
• Difficulty localizing the tooth

1. History: Pain on biting on hard/crunchy food; pain on release of biting pressure; history of large amalgam or bruxism
2. Visual Inspection (transillumination):
   • Fiber optic transilluminator or dental microscope
   • Light directed through tooth reveals crack (dark line)
   • Magnification (DOM) greatly helps
3. Dye Staining:
   • Disclosing solution or methylene blue dye
   • Applied to tooth/grooves; crack absorbs dye; dark line reveals extent
4. Tooth Sleuth (Fracture Finder / Bite Test):
   • Patient bites on device on individual cusps
   • Sharp pain on one cusp = direction of crack
   • Helps identify the specific cracked cusp
5. Removal of Restoration:
   • Old amalgam/composite removed; crack may become visible
6. Vitality Tests:
   • Cold test: Exaggerated, lingering response
   • EPT: Variable
7. Periodontal Probing:
   • Deep narrow isolated pocket along crack (if extends to root)
8. Radiograph:
   • Usually NOT visible on conventional radiograph (crack vertical to X-ray beam)
   • CBCT may show crack in some cases
9. Operative Test:
   • Selective cusp reduction; if pain resolves, that cusp was involved

1. Craze lines (superficial enamel only, no symptoms)
2. Fractured cusp
3. Cracked tooth (extends toward pulp, not separated)
4. Split tooth (complete separation of two fragments)
5. Vertical root fracture (in roots, starts apically)

• Craze line: No treatment/bonding
• Fractured cusp: Bonding/onlay/crown
• Cracked tooth: Crown (protects tooth); RCT if pulp involved
• Split tooth: Extraction usually; or hemisection if favorable
• Vertical root fracture: Extraction or root resection if isolated to one root

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32. Light Transmitting Posts (Fiber Optic / Translucent Posts)

• High translucency/transmittance of light
• Refractive index similar to resin matrix → efficient light transmission
• Modulus of elasticity similar to dentin

1. Enables light curing of resin cement in deep canal portions → better polymerization → higher bond strength
2. Superior esthetic outcome (translucency matches dentin)
3. No light blocking in gingival region (better for all-ceramic crowns)
4. Reduced risk of root fracture (elastic modulus similar to dentin)

• Carbon = opaque (blocks light, cannot use light-cured cement)
• Glass/Quartz = translucent (transmits light → light or dual-cure cement can be used)

1. Clean post space (EDTA + NaOCl)
2. Dry canal
3. Silanate post surface (silane coupling agent improves bond between post and cement)
4. Apply dual-cure or self-cure resin cement
5. Seat post
6. Light cure from occlusal/incisal direction for translucent posts
7. Build core with composite

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Final Exam Summary for This Section:

• For trauma cases (Ellis classification), always state: classify → assess vitality → consider root development stage → choose between pulp cap/pulpotomy/RCT
• For endo-perio lesions: Simon's classification is standard; determine primary etiology first, then treat accordingly
• For surgical topics: always include indications + contraindications + step-by-step technique
• For bleaching: walking bleach = non-vital; vital bleaching = carbamide peroxide night guard; always mention cervical resorption risk and cervical seal
• Short answer topics (2M): Definition + composition/mechanism + 2-3 uses = full marks