Restoration of Endodontically Treated Teeth PDF

# Restoration of Endodontically Treated Teeth ## Restoration of Endodontically Treated Teeth - An endodontically treated tooth present considerable amount of tooth structure has been lost due to: - Caries - Trauma - Placement of previous restorations - Endodontic treatment - These...

# Restoration of Endodontically Treated Teeth ## Restoration of Endodontically Treated Teeth - An endodontically treated tooth present considerable amount of tooth structure has been lost due to: - Caries - Trauma - Placement of previous restorations - Endodontic treatment - These factors complicate subsequent restoration and increases the likelihood of fracture during function. - **Two factors influence the choice of technique:** - The type of tooth (whether it is an incisor, a canine, a premolar, or a molar - The amount of remaining coronal tooth structure (most important indicator of prognosis) ## Treatment Planning - Because of extensive caries or periodontal disease, tooth removal may make more sense than treating it endodontically. - Severely damaged tooth occasionally can be restored after orthodontic repositioning or root resection especially when: - Loss of the tooth will significantly jeopardize the patient's occlusal function or overall treatment plan - When dental implants are not an option - The decision to treat the tooth endodontically can be made only after its restorability has been confirmed. ## Restorability - Marco Ferrari and his colleagues proposed Restorative difficulty evaluation system of endodontically treated teeth (RDES). - RDES allows to any clinician to evaluate restorative difficulties when an endodontic treated tooth must be restored, combines clinical aspects that can involve from the single tooth to a full mouth rehabilitation. - This new system is composed of eight different clinical factors that are divided into six levels of difficulties. - **The RDES is composed of:** 1. Endodontic complexity and outcome, 2. Vertical amount of coronal residual structure 3. Horizontal amount of coronal residual structure, 4. Restoration marginal seal, 5. Local interdisciplinary conditions, 6. The complexity of the treatment planning, 7. Functional need, 8. Dental wear and esthetic need. | Score | Coronal residual walls | Management | |---|---|---| | 1 | 4 walls | No need for post - Direct build up or partial crown to cover cusps | | 2 | 3 walls | Consider placing a post or not to hold core, relating other parameters. | | 3 | 2 walls | Usually need a post for the build-up. | | 4 | 1 wall | After crown lengthening and/or extrusion of the root | | 5 | Ferrule | | | 6 | No ferrule | | - The residual coronal structure is also evaluated "horizontally," considering the presence or not of a cervical lesion, and how much tooth structure was removed during the opening of root canal system | Parameters | Score 1 | Score 2 | Score 3 | Score 4 | Score 5 | Score 6 | |---|---|---|---|---|---|---| | Endodontic complexity and outcome | Vital tooth | Necrotic single root with a periapical lesion | Necrotic multi-root with a periapical lesion | Complex anatomy (calcified and/or additional canals, etc.) | Retreatment | Complex retreatment (with modification of the root anatomy) | | Vertical amount of coronal residual structure and dimension pulp chamber | Four coronal residual walls | Three coronal residual walls | Two coronal residual walls | One coronal residual wall | One coronal residual wall | No ferrule | | Horizontal amount of coronal residual structure | Absence of cervical lesions or excessive internal structure removal | A slight cervical lesion, not requiring restoration, and absence of excessive internal structure removal | Cervical lesion requiring restoration and absence of excessive internal structure removal | Absence of cervical lesions and presence of excessive internal structure removal | A slight cervical lesion, not requiring restoration, and presence of excessive internal structure removal | Cervical lesion requiring restoration and presence of excessive internal structure removal | | Restoration marginal seal | Margins in the enamel and completely supra-gengivally placed | Margins partially in the enamel and dentin and iuxta-gengivally placed | Margins in dentin and supra-gengivally placed | Margins placed iuxta-gingival | Margins placed into the sulcus | Margins placed deeply into the sulcus | | Local interdisciplinary conditions | No need for interdisciplinary treatment (single tooth) | Loss of attachment without the need for periodontal treatment, (single tooth) | Need for crown lengthening (single tooth) | Need for ortho extrusion and crown lengthening (single tooth) | Need for ortho extrusion and crown lengthening (single tooth) | Need for periodontal surgical therapy (bridge) | | The complexity of the treatment planning | A single tooth in a virgin quadrant | A single tooth in a quadrant with other restored teeth | Tooth as the abutment of a multiunit bridge | Tooth as the terminal distal abutment of a multiunit bridge | Tooth as the abutment of a full arch rehabilitation | Tooth as the distal terminal abutment of a full arch rehabilitation | | Functional need | Free-standing restoration in the favorable occlusal environment | Free-standing restoration in the unfavorable occlusal environment | Short/medium (up to 20 mm) span bridge in the favorable occlusal environment | Short/medium (up to 20 mm) span bridge in the unfavorable occlusal environment | Long span bridge in the favorable occlusal environment | Long span bridge in the unfavorable occlusal environment | | Dental wear and esthetic need | No dental wear and no esthetic needs | Slight esthetic need and slight dental wear | Esthetic needs and mild dental wear | High-esthetic need and heavy dental wear | High-esthetic need and heavy dental wear | Compromised function due to dental wear | ## Restoration Marginal Seal | Score | Margin | |---|---| | 1 | Margins in the enamel and completely supra-gingivally | | 2 | Margins partially in the enamel and juxta-gingivally placed in dentin | | 3 | Margins in dentin and supra-gingivally | | 4 | Margins placed juxta-gingival | | 5 | Margins placed into the sulcus | | 6 | Margins placed deeply into the sulcus | - For Subgingival margins: - If the sulcus probes 1.5 mm or less: place the restoration margin 0.5 mm below the gingival tissue crest - If the sulcus probes more than 1.5 mm: place the margin one half the depth of the sulcus below the tissue crest - If a sulcus greater than 2 mm is found: evaluate to see whether a gingivectomy could be performed to lengthen the teeth and create a 1.5 mm sulcus - There is general agreement that a minimum of 2.5-3 mm distance, should exist between the restorative margin and the alveolar bone, allowing for 2 mm of biologic width space and I mm for sulcus depth. - For post and core margins: - at least 4-5mm of sound tooth structure should be available above the osseous crest → 3 mm from the alveolar crest to the restorative margin and 1.5-2mm ferrule length ## Decisions Regarding the Need for Cuspal Coverage for Endodontically Treated Posterior Teeth - Endodontically treated teeth are thought to be more susceptible to fracture as a result of the loss of tooth vitality and tooth structure. - Understanding which part of tooth is most important in keeping fracture resistance and stiffness - factors such as the creation of an endodontic access cavity along with the loss of marginal ridges serve as significant static parameters, resulting in maximum tooth fragility - The extent of cuspal flexure following endodontic and restorative procedures has important consequences for potential fracture. - Cuspal deflection occurs in the posterior teeth due to their morphological shape. Whilst mesio-occlusal-distal (MOD) cavities are done, cuspal deflection is increased due to the diminishing in the stiffness of the tooth - Deciding when cuspal coverage is needed for posterior teeth is considered a challenge for dentists. ## Decision Making Regarding the Need for Cuspal Coverage - **Minimally destructed teeth:** occlusal cavity or MO or DO + thick axial walls (22 mm) → No need for cuspal coverage - Direct Composite Restoration - **Moderately destructed teeth:** MO or DO + Thin axial walls (<2 mm) or MOD → Cuspal coverage is needed (Onlay - overlay) - **Severely destructed teeth:** structure loss beyond an MOD cavity → Cuspal coverage is needed (Post & core - Endocown) ## Measurement Of Cuspal Thickness 1. Arte Cusp Misura 2. Caliber 3. Digital ## Guidelines for Full Occlusal Coverage - Palatal and lingual cusps can be simply reduced by 2 to 3 mm with a butt-joint. - For buccal cusps, there are 3 options: - The ultra-conservative buccal cusp coverage (1.5 mm) - The conventional buccal cusp coverage (2-3 mm) - The full buccal cusp coverage. ## Options for Restoration of Endodontically Treated Teeth | Restoration | |---|---| | Direct Restoration | Partial indirect adhesive restoration | Post and Core restoration | | | Onlay | | | | Overlay | Metal post | | Campasite | Endecrown | Fiber post | ## Decision Tree for Restoring ETT - Following choosing the best matching category, an account for key modifying factors, which lead to unfavorable occlusal forces, should be made. - Most recommended type of composite as final restoration and core build up is Bulk fill and Fiber reinforced composite ## Modifying Factors for Treatment Planning - **The first modifying factor is parafunctional habits.** - Which subject the tooth to increased occlusal forces, such as bruxism. - People who grind their teeth can subject their teeth and restorations to significant amount of destructive occlusal forces. - Parafunctional habits should be taken into consideration when a decision is made about the need for cuspal coverage and the restorative material which could withstand such forces. - **The second modifying factor is lateral occlusal forces.** - Lateral occlusal forces are more destructive to the tooth than axial occlusal forces. - When testing premolars using different loading directions, premolars which were subjected to lateral occlusal loads were at higher risk of fracture than those subjected to axial occlusal loads. - This factor could be crucial for the longevity of ETT and their restorations, which should be considered in the decision-making process. - **The third modifying factor is the number of proximal contacts for the tooth.** - Having proximal contacts was reported to favorably dissipate the occlusal load to the adjacent teeth. - Therefore, ETT with only one proximal contact or without adjacent proximal contacts are subjected to unfavorable distribution of occlusal forces. - This has been shown to impact the survival rates of ETT. - **Any of these modifying factors might alter the clinical decision regarding the most appropriate treatment option.** - A tooth which falls under the minimally destructed category might be considered for cuspal coverage in the presence of any of these modifying factors - Depending on the category selected for the tooth, the most conservative treatment option which provides the tooth with predictable longevity should be selected ## Direct Restorations for Endodontically Treated Teeth - Direct restoration with composite resins is mainly indicated for teeth with minimal to moderate loss of tooth structure. - The amount of remaining tooth structure is crucial for success - A high-filled bulk-fill composite can be recommended for composite build-up in ETT to reduce cuspal strain and stress after polymerization - Recently, advanced short-fiber-reinforced composite (SFRC) materials have been described as providing structural and chemical reinforcement to weaker teeth and even having the potential to prevent fractures in ETT ## Adhesive Indirect Partial Restorations - Bonded indirect ceramic crowns, in the form of "Onlays," "Overlays," have been documented as minimally invasive treatment options for Moderately destructed ETT (teeth with an MO/DO cavity with thin axial walls (≤2 mm) or an MOD cavity) - Adhesive indirect restorations have the advantage of providing cuspal coverage, while preserving the maximum amount of tooth structure - Rationale for the choice of the proper therapeutic option for ETT. - It is important to underline thickness of remaining walls, dimension of the cavity and above all the occlusal context. - Onlays: a partial-coverage restoration that restores one or more cusps and adjoining occlusal surfaces - Overlays: is used to refer to a full cuspal-coverage restoration. - Endocrowns: - A type of restoration for ETT that consists of a core and a crown as a single unit, and extends into the pulp chamber. - Retention is mainly obtained through adhesive resin cement (micro-mechanical retention). Extra retention and stability is provided through the pulp chamber's axial walls (macro-mechanical retention). - They are indicated for restoration of Severely destructed ETT (teeth with structure loss beyond an MOD cavity) in case of: - Pulp chamber at least 2 mm depth - Limited IOD - Short clinical crown ## Post and Core Restoration - **Definitions:** - **Post:** highly rigid part accurately fits the prepared root canal. - **Core:** it is the part outside pulp chamber which rebuilds the loss part of the coronal tooth. - **Indications for post-core system:** 1. Endodontically treated badly mutilated anterior and posterior teeth that can not be restored by any type of restorations 2. Endodontically treated teeth with: - Biologically sound root (no resorption / no fracture) - Perfect apical seal. - Long/ thick / strong root - No any periapical pathosis. - Healthy P.D and alveolar support. - **Classification of post and core system:** - **According to material:** 1. Metallic: metal post with amalgam core 2. Non metallic: fiber/ceramic post with composite/ceramic core 3. Combination: metal post with composite core - **According to attachment:** - a. Attached - b. Detached - **According to Fabrication:** - a. Ready-made (prefabricated) - b. Custom-made - **Ready made posts: (prefabricated posts)** - Supplied in different sizes / shapes → available with special drills. - ↓ rotational resistance because of their cylindrical shape. - →therefore auxiliary pins are inserted to prevent rotaion. - The coronal part of the post contains retention mechanism for the core-materials (amalgam / composite / reinforced G.I) - Advantage → simplicity of the technique. - **Classification:** - **According to post design:** - Sided post: ↑ Retention - Tapered post: ↑ Conservatism - **According to post surface configuration:** - Smooth posts: Least retentive - Serrated posts: More retentive - Threaded posts: Most retentive | Materials | Metallic | Non Metallic | |---|---|---| | | St.St - Ni- Cr-Ti | Ceramic | Fiber | | | | Zirconia | Carbon | Glass | Quartz | Polyethylene | Silica | | | Very rigid / Ti. Poor esthetic. Non esthetic area. | Weaker than metal. Can not be etched. Difficult retrieval. | Strong, but black (less aesthetic) | Less rigid. Same modulus of elasticity (Stiffness) as dentin | High strength and excellent esthetics. Highly translucent | When extreme flexibility is needed, semi-translucent | Currently, pure silica fiber posts are still emerging in dental markets. | - **Principles of tooth preparation to receive post crown:** - **Conservation of tooth structure:** - **Preparation of the root canal:** - Minimal root canal enlargement → to remove the undercuts and enable the post to fit accurately otherwise ↓ dentin thickness → weaken the root → fracture. - Post must not be more than 1⁄2 the diameter of the root. (minimum 1mm of dentin should exist around post at cervical area) - **Coronal preparation:** - Maintain the coronal tooth structure as much as possible because → ↓ stress concentration at gingival margin. - If ↑ coronal tooth loss → extension of preparation 2mm apical to the missing tooth structure → Ferrule effect → with bind the remaining tooth structure + prevent root fracture during function. - **Ferrule effect:** - It is the extension of crown margin to be 2 mm apical to the junction between core and tooth structure→ therefore binding more tooth structure together→ better distribution of force → prevent root fracture. - In extensively damaged tooth with no ferrule → ferrule effect is created by: - Orthodontic extrusion - Surgical crown lengthening - The orthodontic extrusion is preferred than crown lengthening because it will not decrease the root length related to the coronal portion - Ferrule is mandatory in labial and palatal surface. The maximum benefit to be achieved out of having ferrule height (not less than 1.5-2mm) because of high forces directed in labio-palatal direction while ferrule can be limited proximally to 0.5 mm due to force. - Walls are considered "too thin" if they are less than 1 mm thick, meaning the minimal ferrule height is only beneficial if the remaining dentin is at least 1 mm thick - **6 features of successful design:** 1. Adequate apical seal. 2. Minimal canal enlargement (no undercuts) 3. Adequate post length. 4. Positive horizontal stop → to ↓ wedging 5. Vertical wall to prevent rotation 6. Extention of final restoration margin into sound tooth structure (ferrule) - **Factors affecting retention:** - **Preparation geometry:** - Parallel side post are ↑ retentive than tapered. - In severely tapered root canal → parallel sided post may weaken root. - **Post design:** - Smooth (least retention) - Serrated (more retention) - Threaded (most retention) → must be inserted carefully to avoid fracture - **Post length:** - ↑ post length → ↑ retention - Length of the post should be: - 1⁄2 of the root length. - Leave 3-5 mm root canal filling intact - The length of the post shouldn't be less than the length of the occluso-gingival height of the clinical crown. - **Post diameter:** - ↑ Post diameter → ↑ retention. - But post must not be more than 1 1⁄2 the root diameter → otherwise weaking the root→ fracture. - 1 mm thickness of dentin should remain around the post at midroot and cervical area. - **Luting agents:** - The choice of luting agent → have little effect on post retention. - However, adhesive resin cement is indicated if post have ↓ retention. - **Stress distribution:** - Post and core should distribute the forces over large area as much as possible. - **Effect of post design on stress distribution:** - ↑ post length → ↓ stresses. - During function → greatest stress concentration at cervical / apical part. (Therefore dentin should be conserved in these area if possible). - || sided post distribute force better than tapered post which may have wedging effect. - But || sided post → ↑ stress at apex. - The use of || sided posts with tapered end. - Avoid any sharp angles → otherwise stress concentration. - Threaded post or unvented sided post → ↑ stress during insertion. - Therefore flexi-post → stress during insertion. - **Rotational resistance:** - To prevent rotation of post with circular cross section: - If ↑ coronal tooth structure remains → rotation is prevented by vertical coronal wall. - If ↑ coronal tooth structure loss → rotation is prevented by groove in canal wall at cervical bulkiest side (lingual aspect) ## Post Selection - When choosing between a custom-made post and core and a prefabricated post, the decision depends on the clinical situation of the tooth and the amount of remaining tooth structure. Here's when to select a custom-made post and core over a prefabricated one: - **Tooth Anatomy:** - Irregular or Wide Canals: Custom-made posts are preferred when the root canal shape is irregular or very wide. Prefabricated posts are typically straight or tapered, which may not fit well in non-standard or large canals. A custom post can be designed to conform precisely to the shape of the canal. - **Substantial Loss of Tooth Structure:** - Minimal Remaining Tooth Structure: If most of the coronal (above the gum line) portion of the tooth is missing, a custom-made post and core may be better. This ensures a strong bond and better support for the final crown because it can be made to fit the remaining tooth more precisely. - **Better Fit and Retention:** - Customized Fit for Complex Cases: Custom-made posts are indicated when you need optimal fit and retention, especially in multi-rooted teeth or teeth with large, flared, or curved canals. A prefabricated post may not offer enough retention in these cases. - **Strength and Durability:** - Heavy Occlusal Forces: In cases where the tooth is subject to heavy biting forces (e.g., molars or patients with bruxism), a custom-made post can provide greater strength and resistance to fracture compared to prefabricated posts. - **Anterior Teeth with Aesthetic Considerations:** - Aesthetic Needs: Custom-made posts can be crafted to better support the shape of the final restoration, especially in anterior teeth where aesthetics are critical. They provide better adaptability for different tooth shapes. - **Extensive Root Canal Damage:** - When the Canal is Overprepared: If the root canal has been overprepared or altered significantly during endodontic treatment, a prefabricated post may not seat properly. A custom-made post can adapt to the canal size and offer better stability. - **When to Use Prefabricated Posts:** - Standard Canal Shapes: Prefabricated posts are suitable for teeth with relatively straight or standard-shaped canals. - Moderate Tooth Structure Loss: When a fair amount of tooth structure remains, and the canal is not irregular, a prefabricated post can be a quicker and more cost-effective option. - Speed: Prefabricated posts are quicker to place and involve fewer appointments than custom-made ones. ## Selection of Post and Core Materials in Esthetic Areas | Esthetic Zone | Post and Core Materials | |---|---| | Thick periodontium and low lip line | Metal post and composite core | | | Carbon fiber post and composite core | | Thin periodontium and high lip line | Zirconium post and composite core | | | Fiber post and composite core | ## Procedures of Tooth Preparation for Fabrication of Post and Core - **Removal of endodontic filling material:** - 3 methods for removing gutta-percha. - With warmed endodontic plugger → after obturation (same visit) - With rotary instrument: Gates glidden drill / peeso - reamers / special drills. - **Preparation of root canal:** - **For custom-made posts:** - It is used for non- circular canal or → extreme taper - Therefore slight widening of the cervical ½ of the canal → otherwise weaken the root. - **For ready made post:** - The canal is enlarged and shaped with special drills that match the shape and configuration of the post - **Preparation of coronal tooth structure:** 1. Prepare the remaining tooth as it was not damaged. 2. Remove any caries or undermined tooth structure In cast post & core → coronal prep. Should be || to post insertion. 3. The root face should be prepared to have 2 inclined planes in order to →↓ crown displacement →↓ destructive load applied to the root. 4. Providing the anti-rotational element (groove) 5. Eliminate the sharp angles + establishing smooth F.L. - **Direct technique (Core fabrication)** - **In custom made post & core** - Shaped by resin (Dura-lay) or wax →added to post pattern→casting - Therefore prevent possible failure at post-core interface. - **In ready made post:** - Core build up by amalgam / composite resin / reinforced g.l, conserve tooth st, bec. Undercuts are not to be removed. - ttt require one visit only. - Fewer laboratory procedures. - Good adaptation - **Indirect technique:** - Impression → cast → wax pattern is constructed outside the patient mouth. 1. Select a serrated st.st wire →loosely fit in the canal 2. Lubricate the canal with die lubricant. 3. Inject (light body) in the canal using special syringe or lentulo spiral 4. Seat the wire (impression post) to the full depth of the canal. 5. Put more light body around the prepared tooth → insert a previously filled tray (putty). 6) Remove the tray →evaluate it →pour the final cast. - **Post crown for multirooted teeth:** - Because no parallism between the prepared canals→ common path of insertion for custom post and core might be impossible. - Therefore we use: - The strongest and widest R.C→ distal in lower molar. - → palatal in upper molar. - To gain more retention + avoid perforation of the thin canal