# **Restoration of Endodontically Treated Teeth** The University of Western Australia Oral Health Centre of Western Australia  The University of Western Australia Oral Health Centre of Western Australia Clinical photo showing a restored endodontically treated tooth against a red background. The image demonstrates the final restoration, highlighting the crown structure and the interface between the tooth and the restoration material. # Lecture 4: Clinical Considerations    #### Lecture 4: Clinical Considerations Clinical photo showing an extracted tooth with a crown. The tooth root is stained dark brown/black, and the crown appears intact. Clinical photo of an intraoral view showing an extraction socket between two adjacent teeth. The surrounding gingiva appears pink and healthy. Clinical photo showing another extracted tooth with visible staining on the root surface. # **Learning outcomes** By the end of this lecture, you should be able to: - Plan post cementation aims, material options, and step-by-step clinical tips. - Describe indications and fabrication of temporary post crowns. - Perform cast post-and-core try-in and cementation safely. - Select aesthetic post options and understand their limitations. - Estimate mechanical failure risk based on remaining tooth structure and ferrule. - Recognise common modes of failure in post-and-core restorations. - Apply basic restorative principles, occlusal management, and consider alternatives (including implants). By the end of this lecture, you should be able to: - Plan post cementation aims, material options, and step-by-step clinical tips. - Describe indications and fabrication of temporary post crowns. - Perform cast post-and-core try-in and cementation safely. - Select aesthetic post options and understand their limitations. - Estimate mechanical failure risk based on remaining tooth structure and ferrule. - Recognise common modes of failure in post-and-core restorations. - Apply basic restorative principles, occlusal management, and consider alternatives (including implants). **Refresh: Post & Core (What they do—and don’t do)** Post: typically metal or fibre-reinforced composite placed in a prepared root canal to retain a core. Core: foundation restoration that replaces missing coronal tooth structure and provides form for the definitive restoration. Important: post space preparation removes internal tooth structure: so posts are used only when needed for retention. Clinical goal: preserve dentin, achieve a coronal seal, and design for ferrule and occlusal control.  #### Functional Roles - **Post**: Typically metal or fibre-reinforced composite placed in a prepared root canal to retain a core. - **Core**: Foundation restoration that replaces missing coronal tooth structure and provides form for the definitive restoration. #### Clinical Considerations - **Preservation**: Post space preparation removes internal tooth structure; therefore, posts are used only when needed for retention. - **Goals**: Focus on preserving dentin, achieving a coronal seal, and designing for ferrule and occlusal control. Summary diagram box with the header 'Refresh:'. It contains two main definitions and their sub-components. First, 'Post:' is defined as retaining a core for the definitive prosthesis; its arrows point to 'Post space preparation = removal of internal tooth structure' and 'Minimal coronal tooth structure: post & core may prevent coronal fractures'. Second, 'Core:' is defined as replacing lost coronal tooth structure for optimal preparation geometry; its arrows point to 'Composite or amalgam restoration (+ pre-fabricated post)' and 'Metal alloy (cast post & core)'. This visual structure organizes the concepts of Post and Core hierarchically. # **Basic Principles for Restoring ETT (Clinical Checklist)** Establish restorability early (periodontal, endodontic, restorative factors). Be conservative: preserve sound, supported tooth structure, especially peri-cervical dentin. Ferrule and residual walls drive biomechanics; posts retain cores but do not replace dentin. Post / core / crown are not always necessary: choose the least invasive restoration that protects the tooth. Aim for a durable coronal seal and manage occlusal risk. <b>Clinical cue: if residual wall height < 2 mm, plan ferrule creation and/or cuspal coverage early.</b> #### Assessment and Strategy - Establish restorability early by evaluating periodontal, endodontic, and restorative factors. - Be conservative: preserve sound, supported tooth structure, especially peri-cervical dentin. - Ferrule and residual walls drive biomechanics; posts retain cores but do not replace dentin. #### Restoration Selection - Post, core, and crown are not always necessary: choose the least invasive restoration that protects the tooth. - Aim for a durable coronal seal and manage occlusal risk. #### Clinical Cue - If residual wall height is less than 2 mm, plan ferrule creation and/or cuspal coverage early. **Ferrule Effect and Mechanical Risk (Clinical Decision Aid)** **The University of Western Australia** Ferrule height and thickness are major predictors of survival. Risk rises as the number of residual walls decreases and lateral loads increase. Use this decision aid to classify cases and plan ferrule creation, cuspal coverage, occlusal control, or alternative treatment. **Classification of Ferrule Effect** $\downarrow$ **Risk of Mechanical Failure** A. Jotkowitz and N. Samet 2010 #FerruleEffect Height > 2mm | Thickness > 1mm ---|--- 4 walls 3 walls | Distal or Mesial missing 2 walls | Buccal | Light lateral loads Lingual 3 walls | Buccal or Lingual missing | Light lateral loads Heavy lateral loads 2 walls | Mesial Distal --- | --- Heavy lateral loads 2 walls (adjacent) 1 wall 0 ferrule A: No anticipated risk B: Low risk C: Medium risk D: High risk Non restorable  #### Predictors of Survival - Ferrule height and thickness are major predictors of survival. - Risk rises as the number of residual walls decreases and lateral loads increase. - Use the following classification to plan ferrule creation, cuspal coverage, or alternative treatment. #### Classification of Ferrule Effect and Mechanical Risk | Ferrule Dimensions | Residual Walls | Load Conditions | Risk Category | | :--- | :--- | :--- | :--- | | Height > 2mm / Thickness > 1mm | 4 walls | - | A: No anticipated risk | | Height > 2mm / Thickness > 1mm | 3 walls (Distal or Mesial missing) | - | B: Low risk | | Height > 2mm / Thickness > 1mm | 2 walls (Buccal or Lingual) | Light lateral loads | B: Low risk | | Height > 2mm / Thickness > 1mm | 3 walls (Buccal or Lingual missing) | Light lateral loads | C: Medium risk | | Height > 2mm / Thickness > 1mm | 3 walls (Buccal or Lingual missing) | Heavy lateral loads | D: High risk | | Height > 2mm / Thickness > 1mm | 2 walls (Mesial or Distal) | Heavy lateral loads | D: High risk | | - | 2 walls (adjacent) | - | High risk | | - | 1 wall | - | High risk | | - | 0 ferrule | - | Non-restorable | Flowchart diagram titled 'Classification of Ferrule Effect' leading to 'Risk of Mechanical Failure'. It visualizes the decision-making process for dental crown preparation survival. The chart starts with initial criteria (Height > 2mm, Thickness > 1mm) and branches based on the number of residual walls (4, 3, 2, 1, 0). Specific wall configurations are detailed, including missing surfaces like 'Distal or Mesial', 'Buccal', 'Lingual', and 'Mesial/Distal'. Lateral load conditions ('Light lateral loads', 'Heavy lateral loads') further influence the outcome. The flow concludes with risk classifications: A (No anticipated risk), B (Low risk), C (Medium risk), D (High risk), or Non restorable. **Session Planning: Prefabricated vs Cast Post–Core** **Prefabricated post:** * Often cemented in the same session as post space preparation. * Temporary post crown usually not required if definitive restoration proceeds promptly. **Cast post and core:** * Post space prep and cementation occur in different sessions $\rightarrow$ requires a reliable temporary seal. * Temporary post crown often needed in anterior teeth; cast try-in is required before cementation.   #### Prefabricated Post - Often cemented in the same session as post space preparation. - Temporary post crown usually not required if definitive restoration proceeds promptly. #### Cast Post and Core - Post space preparation and cementation occur in different sessions, requiring a reliable temporary seal. - Temporary post crown often needed in anterior teeth. - Cast try-in is required before cementation. Clinical photo showing a tooth with a prefabricated post inserted into the root canal space. The post is visible extending from the crown portion down into the prepared root, demonstrating immediate cementation as described in the text. Clinical photo showing a tooth with a cast post and core being tried in. The restoration appears custom-fitted to the prepared root canal space, illustrating the 'cast try-in' step mentioned for anterior teeth before final cementation. **Temporary Post Crown:** Practical Tips **Indication**: between appointments for cast post-core/ crown which fabricated using indirect (Impression) or direct/ indirect(Burn-out resin) technique. **Technique concept**: temporary post + resin temporary crown as one unit. **Clinical pearls**: * Temporary post should fit passively and precisely in the canal. * Avoid temporary cement deep inside the canal (reduces cleanup and bonding issues). * Re-seat repeatedly until resin is fully polymerised to prevent locking.   #### Indications and Concept - **Indication**: Used between appointments for cast post-core/crown fabricated via indirect (impression) or direct/indirect (burn-out resin) techniques. - **Concept**: The temporary post and resin temporary crown function as a single unit. #### Clinical Pearls - The temporary post should fit passively and precisely in the canal. - Avoid placing temporary cement deep inside the canal to reduce cleanup and bonding issues. - Re-seat the unit repeatedly until the resin is fully polymerized to prevent locking. Close-up photograph of a metallic temporary post against a yellow background. The post is cylindrical with a flat top and an angled cut-off end. Schematic diagram illustrating the placement of a dental post within a tooth. It shows a cross-section of a tooth with a root canal containing a gray post extending into the dentin, surrounded by pink pulp tissue at the apex. **Try-In: Cast Post and Core (Checklist)** Confirm the preparation is free of temporary cement and debris. Seat the post–core passively—never force; check path of insertion. Use fit-checker / disclosing media to identify high spots; adjust conservatively. Verify complete seating and margins; take a radiograph if any doubt. Only cement when seating is fully confirmed. The University of Western Australia  #### Verification Steps - Confirm the preparation is free of temporary cement and debris. - Seat the post–core passively; never force the fit. - Check the path of insertion. - Use fit-checker or disclosing media to identify high spots and adjust conservatively. - Verify complete seating and margins. - Take a radiograph if any doubt exists regarding seating. - Only proceed to cementation when seating is fully confirmed. Labeled procedure diagram for 'TRY-IN - CAST POST AND CORE'. The visual sequence demonstrates the clinical steps: first, confirming the preparation is free of temporary cement and debris (left image); second, seating the post-core passively using a fit-checker or disclosing media to identify high spots (middle image); third, verifying complete seating and margins before final cementation (right image). Arrows indicate the progression through the checklist items. **Post Cementation: Roles and Objectives** The University of Western Australia • Enhance retention of the post–core complex. • Improve stress distribution (supports fracture resistance when dentin is preserved). • Seal irregularities between tooth and post to reduce bacterial contamination and leakage. • Clinical reminder: cement cannot compensate for inadequate ferrule or overly thinned dentin. **POST CEMENTATION AND CORE BUILD-UP TECHNIQUE*** 1. Isolate tooth. Self-etch or total-etch post space. Rinse thoroughly. 2. Remove excess water with a brief burst of air. Remove any pooled water. 3. Dispense UNIVERSAL PRIMER. Mix adhesive. 4. Rub 2 coats of UNIVERSAL PRIMER into the canal. Air dry to remove excess solvent. 5. Determine the post length according to the manufacturer's instructions. 6. Coat the post with UNIVERSAL PRIMER, air dry. 7. Inject CORE-FLO DC Lite into the canal. 8. Coat the apical end of the post with CORE-FLO DC Lite. Seat the post into the canal gently.  #### Objectives of Cementation - Enhance retention of the post–core complex. - Improve stress distribution (supports fracture resistance when dentin is preserved). - Seal irregularities between tooth and post to reduce bacterial contamination and leakage. - **Note**: Cement cannot compensate for inadequate ferrule or overly thinned dentin. #### Post Cementation and Core Build-Up Technique 1. Isolate the tooth. Self-etch or total-etch the post space, then rinse thoroughly. 2. Remove excess water with a brief burst of air; ensure no water is pooled. 3. Dispense and mix the universal primer/adhesive. 4. Rub two coats of primer into the canal. Air dry to remove excess solvent. 5. Determine post length according to manufacturer instructions. 6. Coat the post with primer and air dry. 7. Inject dual-cure core material (e.g., CORE-FLO DC Lite) into the canal. 8. Coat the apical end of the post with the core material and seat the post gently into the canal. Labeled diagram titled 'POST CEMENTATION AND CORE BUILD-UP TECHNIQUE' showing an 8-step clinical procedure. The image displays a tooth cross-section with annotations for each step: 1) Isolate tooth and rinse; 2) Remove excess water; 3) Dispense UNIVERSAL PRIMER; 4) Rub primer into canal; 5) Determine post length; 6) Coat post with primer; 7) Inject adhesive (CORE-FLO DC Lite); 8) Seat post gently. **Cement Options for Posts (Clinical Summary)** **Zinc phosphate:** primarily mechanical interlocking (dry field needed). **Resin-modified glass ionomer:** chemical adhesion + mechanical retention; fluoride release. **Resin cements:** mechanical + micromechanical + chemical adhesion (technique sensitive). Adhesive resin types: total-etch (3-step), self-etch, or self-adhesive systems. Choose based on isolation quality, post type, canal anatomy, and operator control.  #### Material Selection - **Zinc phosphate**: Relies primarily on mechanical interlocking; requires a dry field. - **Resin-modified glass ionomer**: Provides chemical adhesion and mechanical retention; features fluoride release. - **Resin cements**: Provides mechanical, micromechanical, and chemical adhesion; highly technique sensitive. - Types include total-etch (3-step), self-etch, or self-adhesive systems. #### Selection Criteria - Choose based on isolation quality, post type, canal anatomy, and operator control. Labeled schematic diagram illustrating the interface between a dental post and dentin. The central gray cross-hatched rectangle is labeled 'Post'. Flanking it are white vertical sections labeled 'Dentin'. The space between the Post and Dentin on both sides is filled with red outlines labeled 'Cement', demonstrating the cement layer required for retention. **Hydrostatic Pressure During Cementation** **Problem:** trapped cement can generate hydrostatic pressure → increased root stress and incomplete seating. **Clinical tips to reduce risk:** * Use cement at correct viscosity and appropriate working time. * Coat post and deliver cement into canal (avoid overfilling). * Seat slowly, along one path, with steady pressure. * Tapered posts and venting may help cement escape coronally.  #### The Problem - Trapped cement can generate hydrostatic pressure, leading to increased root stress and incomplete seating of the post. #### Clinical Risk Reduction - Use cement at the correct viscosity and within the appropriate working time. - Coat the post and deliver cement into the canal, but avoid overfilling. - Seat the post slowly along a single path with steady pressure. - Utilize tapered posts and venting to help cement escape coronally. Labeled cross-sectional diagram of a dental post and root canal illustrating hydrostatic pressure during cementation. The image shows a tapered post (blue) inside a root canal space with red cement at the bottom. A black upward-pointing arrow indicates the direction of force or displacement caused by trapped cement generating pressure, visually demonstrating incomplete seating and increased root stress as described in the OCR text. # Bonded Posts ‘Strengthen the Root’? ## (Critical Thinking) > Bonded posts can improve retention of the core, but ‘strengthening’ the root is not guaranteed. ### Challenges in the root canal: * Fluid leakage pathways (apical foramen, lateral canals). * Bonding to radicular dentin is less reliable than coronal dentin. * Technique sensitivity (cleaning, isolation, cement placement, polymerisation). > Bonding is black line -boxes > Solid white square -box > Take-home: focus on ferrule + dentin preservation; bond carefully when indicated. #### Strengthening vs. Retention - Bonded posts can improve core retention, but "strengthening" the root is not guaranteed. #### Challenges in the Root Canal - Fluid leakage pathways (apical foramen, lateral canals). - Bonding to radicular dentin is less reliable than bonding to coronal dentin. - Technique sensitivity regarding cleaning, isolation, cement placement, and polymerization. #### Take-Home Message - Focus on ferrule and dentin preservation; perform bonding carefully when indicated. # Before Cementation: Canal Cleanliness Matters **Clean the canal thoroughly**—bacterial contamination and debris reduce adhesion. Remove all temporary cement remnants (especially at the coronal third). Eugenol-free temporary cement is often preferred, but the key is complete removal of remnants. Aim: a clean dentin surface for predictable cementation and a reliable coronal seal. #### Surface Preparation - Clean the canal thoroughly; bacterial contamination and debris significantly reduce adhesion. - Remove all temporary cement remnants, particularly at the coronal third. - While eugenol-free temporary cement is often preferred, the priority is the complete removal of all remnants. - Aim for a clean dentin surface to ensure predictable cementation and a reliable coronal seal. **Before Cementation: Isolation and Moisture Control** * Dry the post space with paper points and maintain a moisture-controlled field. * Use rubber dam when possible—improves predictability and reduces contamination. * Avoid desiccation if using adhesive systems that require ‘moist dentin’—follow manufacturer guidance. **Clinical focus:** consistent technique and clear visibility.  #### Environmental Control - Dry the post space with paper points and maintain a moisture-controlled field. - Use a rubber dam whenever possible to improve predictability and reduce contamination. - Avoid desiccation if using adhesive systems that require "moist dentin"; strictly follow manufacturer guidance. #### Clinical Focus - Maintain consistent technique and clear visibility throughout the procedure. Clinical photo demonstrating the isolation and moisture control phase before cementation. The image shows a tooth prepared with a post space, isolated by a green rubber dam held in place by metal clamps. A white paper point is being used to dry the interior of the post space, illustrating the step described in the text: 'Dry the post space with paper points'. **During Cementation: Cement Delivery** * Apply cement around the post AND inside the canal (e.g., with a spiral/lentulo instrument where appropriate). * Avoid air entrapment: coat canal walls evenly and seat the post slowly. * Maintain correct orientation and path of insertion—do not ‘pump’ the post. * Immediately remove gross excess cement once initial set allows. Mannocci et al 2001    #### Application Technique - Apply cement both around the post and inside the canal (e.g., using a spiral/lentulo instrument where appropriate). - Avoid air entrapment by coating canal walls evenly and seating the post slowly. - Maintain the correct orientation and path of insertion; do not "pump" the post during seating. - Immediately remove gross excess cement once the initial set allows. Clinical photo showing a spiral/lentulo instrument holding a bead of cement against a dark background, demonstrating the application method mentioned in the text. Clinical photo showing a dental post being seated into a prepared tooth with cement visible at the interface, illustrating the 'avoid air entrapment' step. Diagram or photograph of a spiral/lentulo instrument used for applying cement inside the canal, corresponding to the instruction to apply cement 'inside the canal'. # **After Cementation: Timing and Handling** Do not disturb the post until the cement has fully set. Prefabricated post: proceed to core build-up after complete set. Cast post-core: refine crown preparation after complete set. Avoid final impression/scan in the same appointment—reduce risk of micro-movement and debonding. #### Post-Setting Protocols - Do not disturb the post until the cement has fully set. - **Prefabricated post**: Proceed to core build-up only after the complete set. - **Cast post-core**: Refine the crown preparation only after the complete set. - Avoid taking the final impression or scan in the same appointment to reduce the risk of micro-movement and debonding. **Common Failures in Post-and-Core Restorations** Most frequent: post loosening / loss of retention; caries and apical pathology also contribute. Catastrophic failures: vertical/root fracture (less frequent but usually non-restorable). Risk increases with tapered posts, long function time, and periodontal problems. Prevention focus: ferrule + dentin preservation + good cementation + occlusal management. Turner 1982 100 Post and core failures <sup>↑</sup> Post loosening –59% Apical lesion and Caries Fractured and loose crowns Fracture of root – 10% Fracture of post – 6% **Failure Frequency** <sup>↑</sup> Peutzfeldt et al 2008 Mean survival time until Failure:11 years. <sup>↑</sup> Fracture of tooth Post loosening Fracture of post  #### Failure Statistics and Types - **Most frequent**: Post loosening / loss of retention (59%), followed by caries and apical pathology. - **Catastrophic**: Vertical root fracture (10%) and post fracture (6%). - **Timeline**: Mean survival time until failure is approximately 11 years (Peutzfeldt et al 2008). #### Risk Factors - Risk increases with tapered posts, long function time, and periodontal problems. #### Prevention Focus - Prioritize ferrule and dentin preservation. - Ensure high-quality cementation and diligent occlusal management. Comparison chart displaying failure frequencies for post-and-core restorations based on two studies. Left panel (Turner 1982) lists 'Post loosening –59%', 'Apical lesion and Caries', 'Fractured and loose crowns', 'Fracture of root – 10%', and 'Fracture of post – 6%'. Right panel (Peutzfeldt et al 2008) lists 'Fracture of tooth', 'Post loosening', and 'Fracture of post'. Both panels feature upward-pointing arrows labeled 'Failure Frequency' to indicate increasing frequency from bottom to top. # **Vertical Root Fracture: Why it Happens** Potential causes: * Post placement and cementation (wedging/hydrostatic pressure). * Condensation forces during obturation (especially in thin roots). * Occlusal overload (parafunction, interferences, oblique forces). * Wedging from poorly fitting restorations. * Corrosion/expansion with some metallic posts.  #### Potential Etiology - **Procedural**: Post placement and cementation (wedging or hydrostatic pressure). - **Endodontic**: Condensation forces during obturation, especially in thin roots. - **Functional**: Occlusal overload (parafunction, interferences, or oblique forces). - **Restorative**: Wedging effects from poorly fitting restorations. - **Material**: Corrosion and subsequent expansion associated with some metallic posts. Clinical photograph showing a tooth extracted from the mouth exhibiting a vertical root fracture. The image displays a tooth with a white crown restoration and a reddish-brown root section lying on a blue textured surface. A distinct vertical crack is visible running down the length of the root, consistent with the topic 'Vertical Root Fracture' mentioned in the OCR text. # Corrosion of Metal Posts: Clinical Relevance Corrosion may contribute to root fracture in susceptible situations by expansion and stress concentration. Corrosion risk increases with access of electrolyte to the post surface (microleakage). More corrosion resistant: titanium alloys, noble metal alloys (cast post-cores). Corrosion-free: non-metallic post materials (fibre-reinforced posts). Prevention: coronal seal, appropriate material selection, and margin control. #### Clinical Impact - Corrosion can contribute to root fracture through expansion and stress concentration. - Risk increases when electrolytes access the post surface via microleakage. #### Material Resistance - **High Resistance**: Titanium alloys and noble metal alloys (used in cast post-cores). - **Corrosion-Free**: Non-metallic materials, such as fibre-reinforced posts. #### Prevention - Maintain a strict coronal seal, select appropriate materials, and ensure precise margin control. # **Aesthetic Posts: When and Why** The University of Western Australia Indicated under translucent all-ceramic crowns where the foundation colour affects final aesthetics. **Aim**: post–core colour close to natural dentin to avoid grey shine-through. Thin root walls and thin gingival tissues increase risk of discoloration from metal posts. Balance aesthetics with biomechanics and retrievability (especially for zirconia).  #### Indications - Indicated under translucent all-ceramic crowns where the foundation color impacts final aesthetics. - Aim for a post–core color close to natural dentin to prevent a grey "shine-through" effect. #### Risk Factors for Discoloration - Thin root walls and thin gingival tissues increase the aesthetic risk posed by metal posts. #### Clinical Balance - Balance aesthetic requirements with biomechanics and retrievability (particularly concerning zirconia posts). Clinical photo showing a dental model with a white ceramic post-core inserted into the root of a central tooth. The image demonstrates the aesthetic application discussed in the text, specifically illustrating how the post-core color is matched to natural dentin to prevent grey shine-through when viewed through translucent all-ceramic crowns. **Masking Metal and Aesthetic Alternatives** If a metal post is present: * **Composite core** may mask metal—requires adequate thickness. Alternative strategies: * Use an all-ceramic crown with an opaque substructure. * Apply opaque porcelain to the core portion of a cast post-core (lab technique). Consider fibre posts when bonding and anatomy allow for predictable aesthetics.  #### Managing Existing Metal Posts - A composite core may mask metal if there is adequate thickness. #### Alternative Strategies - Use an all-ceramic crown with an opaque substructure. - Apply opaque porcelain to the core portion of a cast post-core (laboratory technique). - Consider fibre posts when bonding and anatomy allow for predictable aesthetics. A composite figure demonstrating 'Masking Metal and Aesthetic Alternatives' in dentistry. The top row contains two clinical photos: the left shows a tooth with significant decay and gum recession, while the right displays a prepared tooth site with a metal post visible through the translucent restoration material, illustrating the need for masking. The bottom row features two technical images of ceramic restorations: the left shows a white opaque crown on an abutment, and the right displays a cross-section of a tooth preparation or core structure, visually supporting the text's mention of all-ceramic crowns with opaque substructures. **Occlusion: Requirements for Long-Term Success** Centric and dynamic occlusion: • No premature contacts; even contacts in centric. • Mutually protected occlusion (anterior and posterior share protection). Anterior teeth with post–core: • Prefer anterior guidance distributed across multiple teeth in protrusion. Canine with post–core: • Group function may be preferred over isolated canine guidance. Key message: avoid interferences. #### Centric and Dynamic Occlusion - Ensure no premature contacts and even contacts in centric. - Aim for mutually protected occlusion where anterior and posterior teeth share protection. #### Specific Tooth Considerations - **Anterior teeth with post-core**: Prefer anterior guidance distributed across multiple teeth during protrusion. - **Canines with post-core**: Group function may be preferred over isolated canine guidance. #### Key Message - Avoid all occlusal interferences. **Occlusal Risk Modifiers (Plan Accordingly)** Opposing dentition increases load risk: natural teeth, zirconia crowns/bridges, dentures, implants. Parafunction (bruxism/clenching): prolonged excessive forces; resultant forces often horizontal. Dietary habits: hard foods increase peak forces. Management: adjust occlusion, consider protective splints, and select restorations that minimize lateral stress. #### Load and Force Factors - **Opposing Dentition**: Natural teeth, zirconia restorations, dentures, and implants increase load risk. - **Parafunction**: Bruxism and clenching create prolonged excessive forces, often in a horizontal direction. - **Dietary Habits**: Hard foods increase peak forces. #### Management Strategies - Adjust occlusion carefully. - Consider protective splints. - Select restorations designed to minimize lateral stress. **Conservative Restoration Options for ETT** Options: composite, inlay, onlay/overlay, partial crown, full crown. Use pulp chamber for retention when possible—sometimes no post and no separate core material is required. Preserve residual walls and prioritise ferrule. Posterior teeth often benefit from cuspal coverage; aim to be as conservative as risk allows.  #### Restoration Hierarchy - Options include composite, inlay, onlay/overlay, partial crown, and full crown. - Use the pulp chamber for retention when possible; in some cases, no post or separate core material is required. #### Structural Priorities - Preserve residual walls and prioritize the ferrule. - Posterior teeth often benefit from cuspal coverage. - Aim for the most conservative restoration that the clinical risk level allows. University logo for The University of Western Australia, featuring a shield with a swan and text. **When the Tooth is Unrestorable: Options** Logo: THE UNIVERSITY OF WESTERN AUSTRALIA Extraction and replacement options: • Removable partial denture (RPD). • Conventional bridge. • Resin-bonded bridge. • Implant-supported crown/bridge. • Leave the space (case-dependent). Shared decision-making: restorability, risk, cost, time, and patient priorities. #### Extraction and Replacement Options - Removable partial denture (RPD). - Conventional bridge. - Resin-bonded bridge. - Implant-supported crown or bridge. - Leave the space (case-dependent). #### Decision Making - Utilize shared decision-making based on restorability, risk, cost, time, and patient priorities. # **ETT Restoration vs Implant: Clinical Considerations** **Endo + post/core + crown:** * Preserves natural tooth and periodontal mechanoreceptors (proprioception). * Often lower morbidity and faster completion when the tooth is restorable. **Extraction + implant + crown:** * Higher cost and treatment time (healing/osseointegration). * Surgical morbidity may include bone/soft tissue grafting. * In aesthetic zones, implants may offer more predictable soft tissue outcomes in selected cases.  #### Endodontic Restoration (Post/Core/Crown) - Preserves the natural tooth and periodontal mechanoreceptors (proprioception). - Often involves lower morbidity and faster completion if the tooth is restorable. #### Dental Implant - Involves higher cost and longer treatment time due to healing and osseointegration. - Surgical morbidity may include bone or soft tissue grafting. - In aesthetic zones, implants may offer more predictable soft tissue outcomes in specific cases. Institutional logo of The University of Western Australia. It includes a shield with a swan and the university's name in blue text. ## Key Take-Home Messages **Most failures relate to retention loss, leakage, and structural factors—not 'brittle dentin'**. Preserve dentin (especially peri-cervical), maximize residual walls, and create ferrule when possible. Cementation is technique-sensitive: cleanliness, isolation, cement handling, and seating are critical. Manage occlusion: reduce lateral loads and interferences; consider parafunction protection. Choose the least invasive restoration that achieves coronal seal and biomechanical protection. #### Summary of Principles - Most failures relate to retention loss, leakage, and structural factors rather than "brittle dentin." - Preserve dentin (especially peri-cervical), maximize residual walls, and create a ferrule whenever possible. - Cementation is technique-sensitive: cleanliness, isolation, handling, and seating are critical. - Manage occlusion by reducing lateral loads and interferences; provide protection for parafunction. - Choose the least invasive restoration that achieves a coronal seal and biomechanical protection. **References (as used in this lecture)** The university of Western Australia Rosenstiel et al. Contemporary Fixed Prosthodontics (4th ed). Turner CH. Post-retained crown failure: A survey. Dent Update. 1982;9:221–234. Peutzfeldt et al. A survey of failed post-retained restorations. Clin Oral Investig. 2008;12:37–44. Fernandes et al. Factors determining post selection: A literature review. J Prosthet Dent. 2003;90:556–562. Jotkowitz & Samet. Rethinking ferrule. Br Dent J. 2010;209:25–33. Mannocci et al. Microleakage of ETT restored with fiber posts and composite cores. J Prosthet Dent. 2001;85:284–291. Petersen KB. Longitudinal root fracture due to corrosion of an endodontic post. J Can Dent Assoc. 1971;2:66–68. #### Academic and Clinical Citations - The University of Western Australia - Rosenstiel et al. *Contemporary Fixed Prosthodontics* (4th ed). - Turner CH. Post-retained crown failure: A survey. *Dent Update*. 1982;9:221–234. - Peutzfeldt et al. A survey of failed post-retained restorations. *Clin Oral Investig*. 2008;12:37–44. - Fernandes et al. Factors determining post selection: A literature review. *J Prosthet Dent*. 2003;90:556–562. - Jotkowitz & Samet. Rethinking ferrule. *Br Dent J*. 2010;209:25–33. - Mannocci et al. Microleakage of ETT restored with fiber posts and composite cores. *J Prosthet Dent*. 2001;85:284–291. - Petersen KB. Longitudinal root fracture due to corrosion of an endodontic post. *J Can Dent Assoc*. 1971;2:66–68. [^1]: Original PDF page 1: [[L4 RETT Online.pdf#page=1|L4 RETT Online, p.1]] [^2]: Original PDF page 2: [[L4 RETT Online.pdf#page=2|L4 RETT Online, p.2]] [^3]: Original PDF page 3: [[L4 RETT Online.pdf#page=3|L4 RETT Online, p.3]] [^4]: Original PDF page 4: [[L4 RETT Online.pdf#page=4|L4 RETT Online, p.4]] [^5]: Original PDF page 5: [[L4 RETT Online.pdf#page=5|L4 RETT Online, p.5]] [^6]: Original PDF page 6: [[L4 RETT Online.pdf#page=6|L4 RETT Online, p.6]] [^7]: Original PDF page 7: [[L4 RETT Online.pdf#page=7|L4 RETT Online, p.7]] [^8]: Original PDF page 8: [[L4 RETT Online.pdf#page=8|L4 RETT Online, p.8]] [^9]: Original PDF page 9: [[L4 RETT Online.pdf#page=9|L4 RETT Online, p.9]] [^10]: Original PDF page 10: [[L4 RETT Online.pdf#page=10|L4 RETT Online, p.10]] [^11]: Original PDF page 11: [[L4 RETT Online.pdf#page=11|L4 RETT Online, p.11]] [^12]: Original PDF page 12: [[L4 RETT Online.pdf#page=12|L4 RETT Online, p.12]] [^13]: Original PDF page 13: [[L4 RETT Online.pdf#page=13|L4 RETT Online, p.13]] [^14]: Original PDF page 14: [[L4 RETT Online.pdf#page=14|L4 RETT Online, p.14]] [^15]: Original PDF page 15: [[L4 RETT Online.pdf#page=15|L4 RETT Online, p.15]] [^16]: Original PDF page 16: [[L4 RETT Online.pdf#page=16|L4 RETT Online, p.16]] [^17]: Original PDF page 17: [[L4 RETT Online.pdf#page=17|L4 RETT Online, p.17]] [^18]: Original PDF page 18: [[L4 RETT Online.pdf#page=18|L4 RETT Online, p.18]] [^19]: Original PDF page 19: [[L4 RETT Online.pdf#page=19|L4 RETT Online, p.19]] [^20]: Original PDF page 20: [[L4 RETT Online.pdf#page=20|L4 RETT Online, p.20]] [^21]: Original PDF page 21: [[L4 RETT Online.pdf#page=21|L4 RETT Online, p.21]] [^22]: Original PDF page 22: [[L4 RETT Online.pdf#page=22|L4 RETT Online, p.22]] [^23]: Original PDF page 23: [[L4 RETT Online.pdf#page=23|L4 RETT Online, p.23]] [^24]: Original PDF page 24: [[L4 RETT Online.pdf#page=24|L4 RETT Online, p.24]] [^25]: Original PDF page 25: [[L4 RETT Online.pdf#page=25|L4 RETT Online, p.25]] [^26]: Original PDF page 26: [[L4 RETT Online.pdf#page=26|L4 RETT Online, p.26]] [^27]: Original PDF page 27: [[L4 RETT Online.pdf#page=27|L4 RETT Online, p.27]] [^28]: Original PDF page 28: [[L4 RETT Online.pdf#page=28|L4 RETT Online, p.28]] [^29]: Original PDF page 29: [[L4 RETT Online.pdf#page=29|L4 RETT Online, p.29]]