Applications of PRP and PRF in Endodontics

Overview: What are PRP and PRF?

• PDGF (Platelet-Derived Growth Factor) - stimulates cell proliferation and migration
• TGF-β (Transforming Growth Factor beta) - promotes matrix synthesis
• VEGF (Vascular Endothelial Growth Factor) - stimulates angiogenesis
• IGF-1 (Insulin-like Growth Factor) - cell differentiation
• EGF (Epidermal Growth Factor) - epithelial and fibroblast stimulation
• FGF (Fibroblast Growth Factor) - tissue healing and neovascularization

Applications in Endodontics

1. Regenerative Endodontic Procedures (REPs) / Revascularization

1. Disinfection of the root canal with irrigants (NaOCl, EDTA) and triple antibiotic paste (TAP) or calcium hydroxide as intracanal medicament
2. Induction of bleeding into the canal (blood clot as natural scaffold) OR placement of PRP/PRF as scaffold
3. Sealing with MTA at the cementoenamel junction followed by permanent restoration

• Replace or supplement the natural blood clot, which can be unreliable
• PRF/PRP provide a structured fibrin matrix that supports migration and proliferation of stem cells from the apical papilla (SCAP) and mesenchymal stem cells (MSCs)
• Release of growth factors promotes angiogenesis and tissue organization within the canal
• PRP as scaffold has been shown to increase periapical healing, promote radiographic root development, increase root length and width, and achieve complete apical closure
• PRF structure allows sustained 7-14 day growth factor release - superior to the abrupt burst from PRP

2. Vital Pulp Therapy (VPT) - Direct Pulp Capping and Pulpotomy

• PRP/PRF can be placed directly over an exposed pulp to stimulate dentinogenesis and bridge formation
• Growth factors (especially TGF-β and BMP) in the concentrate promote odontoblast differentiation and tertiary dentin formation
• Serves as an alternative or adjunct to calcium hydroxide and MTA

• PRF membrane placed over the amputated radicular pulp surface
• Provides growth factor-rich environment to preserve radicular pulp vitality
• Stimulates a reparative dentinal bridge
• Studies show comparable outcomes to MTA-based pulpotomy
• The scoping review (2025) ranked pulpotomy/pulp protection as the third most reported endodontic application for platelet concentrates

3. Periapical Surgery (Surgical Endodontics / Apicoectomy)

• Placement of PRF membrane in the bony defect after apicoectomy and root-end filling
• Acts as a scaffold and barrier membrane to support bone regeneration in the periapical defect
• Promotes hemostasis and reduces post-operative bleeding
• Accelerates soft tissue closure and bone healing
• Can be used in conjunction with root-end filling materials (e.g., MTA, Biodentine)

• Faster reduction in periapical lesion size on radiographs
• Accelerated healing in cases of large radicular cysts post-enucleation
• PRF used with apicoectomy for radicular cyst treatment resulted in accelerated healing rates (case evidence, Dimensions of Dental Hygiene, 2025)

4. Root Perforation Repair

• As a matrix/scaffold placed at the perforation site before or alongside MTA/Biodentine
• The fibrin matrix helps hold the repair material in place
• Growth factors promote regeneration of the surrounding periodontal tissues
• Reduces inflammation of the periodontium adjacent to the perforation
• Particularly useful in furcal perforation repair where access to surrounding bone is limited

5. Non-Surgical Endodontics - Root Canal Treatment Support

• PRF can be used in combination with calcium hydroxide as intracanal medicament for enhanced periapical healing
• PRF combined with irrigants improves post-treatment healing response
• The anti-inflammatory and antibacterial properties of PRP (via RANTES, platelet factor-4) reduce postoperative pain after root canal treatment
• Clinical trial evidence shows PRP significantly decreases postoperative pain and increases healing rate through revascularization in mature necrotic molars with chronic periapical periodontitis

6. Root Amputation and Hemisection

• PRF can be placed in the socket or bone defect after root amputation or hemisection procedures
• Supports alveolar bone regeneration and soft tissue healing
• Acts as a natural membrane to separate the bone repair site from the oral environment
• Reduces the need for synthetic barrier membranes (e.g., Gore-Tex, collagen) in selected cases

7. Socket Preservation / "Sticky Bone"

• PRF can be mixed with bone graft particles (autograft, xenograft) to create "sticky bone" - a cohesive, malleable graft material
• This composite is used for socket preservation after tooth extraction before implant placement
• The fibrin network holds graft particles together while releasing growth factors that accelerate bone formation
• Particularly relevant post-apicoectomy or post-tooth extraction in endodontically compromised sites

Comparison: PRP vs. PRF in Endodontics

Advantages Shared by Both PRP and PRF

1. Autologous origin - no risk of immune rejection or disease transmission
2. Biocompatibility - derived from patient's own blood
3. Multi-functional - angiogenesis, cell proliferation, hemostasis, antimicrobial
4. Cost-effective - especially PRF (minimal consumables)
5. Ease of preparation - chairside, no lab required
6. Anti-inflammatory - reduces postoperative pain and swelling
7. Promotes dentin-pulp complex regeneration - via PDGF, TGF-β, BMP-2 signaling

Limitations and Considerations

• Significant heterogeneity in preparation protocols - centrifugation speed/time varies across studies, affecting platelet/growth factor yield
• Most evidence is from case reports and small RCTs - large multicenter trials are lacking
• Complete histological pulp regeneration remains elusive; what forms post-REP is often cementum-like or bone-like tissue, not true pulp
• PRF must be used immediately after preparation
• Not suitable when systemic platelet disorders are present or patient is on antiplatelet therapy
• Long-term outcomes beyond 12-24 months are insufficiently documented

Summary

• Rebimbas Guerreiro et al. (2025) - Scoping Review, PMID 40564941 - 412 articles, most comprehensive mapping of PRP/PRF in endodontics
• Kawthar et al. (2025) - Systematic Review of RCTs, PMID 41040033 - confirms regenerative efficacy in periapical lesions
• PRF Applications in Endodontics - Sabeti et al., Quintessence Publishing (clinical reference textbook)

Biomechanics of Post-Retained Restorations

Why Biomechanics Matters in Endodontically Treated Teeth (ETT)

• Loss of tooth structure - from caries, trauma, access cavity preparation, and post space preparation
• Desiccation effect - removal of pulp tissue alters hydration of dentinal tubules, reducing the organic matrix contribution to toughness (historically overstated; the dominant factor is structural loss)
• Loss of proprioceptive feedback - no pulp means reduced sensory warning of overload
• Altered stress distribution - the post occupies what was the pulp space with a rigid material, fundamentally changing how forces are transmitted through the root

1. Forces Acting on Post-Retained Restorations

• The cervical region of the root (most common fracture site)
• The apical end of the post
• The post-cement-dentin interface

2. The Ferrule Effect (Most Important Biomechanical Concept)

Definition

Mechanism

• Braces the root against lateral forces that would otherwise lever against the post tip
• Distributes stress along the cervical root rather than concentrating it at one point
• Prevents core debonding by hugging the tooth structure
• Reduces wedging forces transmitted by the post to the root apex

Requirements

• Minimum height: 2 mm of sound vertical coronal dentin (circumferential, at or above the CEJ) is the universally accepted minimum
• Minimum thickness: The dentin must be at least 1 mm thick to be functional
• The ferrule must engage parallel walls - flared or tapered walls provide less resistance
• Must be on natural tooth structure - core material does not count as ferrule

Incomplete Ferrule

• Even an incomplete ferrule (present on only 1-3 walls) significantly increases fracture resistance compared to no ferrule
• The number of residual axial walls affects fracture resistance and failure mode
• An incomplete ferrule is an acceptable alternative when a complete 360° ferrule is unachievable

Key Principle

With an adequate 2 mm circumferential ferrule, post length and post design become secondary factors. Without a ferrule, no post design can fully compensate.

3. Post Design and Its Biomechanical Implications

A. Post Shape (Taper)

• Parallel posts are more retentive than tapered ones (Standlee et al., classic studies)
• Tapered posts closely follow root anatomy, requiring less dentin removal - clinically preferred when canal anatomy is favorable
• Tapered posts create a wedging effect under axial loading: they act like a wedge being driven into the root, which generates hoop stresses that can cause vertical root fracture
• Parallel posts generate high apex stresses but distribute lateral stress more evenly

B. Post Length

• Post should be at least as long as the clinical crown (crown-to-post ratio ≥ 1:1)
• Classically: post length = 2/3 of root length OR root length minus 5 mm (to preserve apical seal)
• Minimum 5 mm of apical gutta-percha must be preserved to maintain the apical seal
• As post length increases, retention increases (not linear) and stress is distributed over a larger root area, reducing concentration

• Stress concentrated over a smaller area
• Greater risk of post dislodgment and core failure
• Lever arm effect amplified

• Risk of perforation in curved canals
• Disruption of apical seal
• Weakening of remaining radicular dentin in the apical third

C. Post Diameter

• Increasing post diameter minimally improves retention but significantly weakens the root by removing dentin
• Remaining dentin thickness is the key - thinner dentin = higher fracture risk
• A dentin wall of at least 1 mm thickness should be preserved circumferentially around the post

D. Post Surface Texture (Active vs. Passive)

• Threaded (active) posts have the highest retention but generate the greatest stress concentrations and highest risk of catastrophic vertical root fracture - largely abandoned clinically
• Passive parallel posts with adhesive resin cement offer optimal retention-safety balance

4. Post Material and the Elastic Modulus Concept

Fiber Posts (Glass Fiber / Carbon Fiber)

• Modulus matched to dentin = homogenous, physiological stress distribution along the root
• Under load, GFP and root dentin deform similarly = no stress concentration at the post-dentin interface
• Glass fiber posts bonded with resin cement to composite resin core form a monoblock unit (post + cement + core + dentin all act together)
• Stress is mostly distributed in the cervical third of the root - this zone has the most dentin, making it relatively safe
• Favorable failure mode: GFP failures tend to be coronal (post debonding, core fracture) rather than root fracture - restorable/reparable

• High modulus = acts as a rigid lever within the root
• When lateral force is applied, the rigid post does not flex - stress is transmitted to the dentin, concentrating at the cervical margin and post apex
• Unfavorable failure mode: more likely to cause vertical root fractures - catastrophic and unrestorable
• Cast post-and-core: stress within the post, cervical and apical root regions (FEA evidence)

5. Stress Distribution Patterns (from FEA and Photoelastic Studies)

1. Cervical region (most critical) - where the crown margin meets root surface; the ferrule zone; bending moment peaks here under lateral load
2. Apical end of post - stress concentration under axial loading, especially parallel posts
3. Shoulder/finish line - particularly interproximally
4. Post-cement interface - shear stress leads to debonding

• Axial loads (along the long axis): compressive stresses distributed through crown-core-post-root; relatively benign
• Lateral loads at 45° (simulating lingual forces on anterior teeth): create bending moments - tensile stress on one side, compressive on the other; most dangerous for root fracture

• As post length increases → stress moves apically, cervical stress reduced
• Short post + no ferrule = catastrophic stress concentration at the cervical 1/3
• Long post + ferrule = most favorable distribution

6. Cement and Bonding Biomechanics

• Resin cement (e.g., Panavia, RelyX) forms the basis of the monoblock concept - adhesive bonding of GFP to root dentin creates a unified system
• Monoblock: GFP + resin cement + composite core = one integrated unit with uniform stiffness; stress is distributed like the original dentin
• Limitation: achieving perfect adhesive bonding in root canal depths is challenging (C-factor issues, moisture, incomplete curing of deep cement)

7. Anti-Rotation Design

• Circular post cross-section has no anti-rotational resistance
• Anti-rotation features include:
  • Grooves or slots in the coronal dentin
  • Flat-sided posts
  • Oval or irregular canal shapes (premolars naturally resist rotation)
  • Core extensions into pulp chamber (especially in multirooted teeth)
• Insufficient anti-rotation leads to torsional stress at the post-cement interface → cement failure

8. Failure Modes

9. When to Place a Post (Clinical Biomechanics)

• Remaining coronal tooth structure insufficient to retain a core by itself (< 50% of original coronal structure)
• Full-coverage crown required
• High occlusal load expected

• Adequate coronal structure remains (≥ 1-2 walls of adequate height and thickness)
• Core retention is achievable from the pulp chamber floor alone (e.g., molars with large chamber)
• Endodontically treated anterior tooth with only small access cavity

Summary: Key Biomechanical Principles

1. Ferrule effect is paramount - minimum 2 mm of circumferential sound coronal dentin is the single greatest determinant of long-term success
2. No post can compensate for absence of a ferrule
3. Glass fiber posts preferred - modulus matched to dentin promotes homogeneous stress distribution and favorable (reparable) failure modes
4. Post length = primary retention factor - must be at least equal to crown length; preserve 5 mm apical seal
5. Post diameter must not exceed 1/3 root width - dentin preservation is more important than retention gain from wider posts
6. Parallel posts more retentive than tapered; tapered posts have a wedging risk
7. Avoid threaded/active posts - highest fracture risk despite high retention
8. Adhesive resin cementation supports the monoblock concept with GFP
9. Lateral forces are most dangerous - they create bending moments concentrated at the cervical root; the ferrule directly resists this
10. Mode of failure matters clinically - designs that promote coronal failure (restorable) over root fracture (catastrophic) are preferred

• Dong et al., J Dent 2024 (PMID 38740250) - Systematic review: incomplete ferrule still significantly improves fracture resistance over no ferrule
• Badami et al., Biomed Res Int 2022 (PMID 9617588) - FEA review: GFP provides most homogeneous (cervical) stress distribution; metallic posts spread stress apically
• Shirani et al., J Esthet Restor Dent 2025 (PMID 40717376) - Meta-analysis: polyethylene fiber vs. glass fiber post fracture resistance comparison