Lecture 9 Restoration Of Compromised Dentition PDF

Restoration Of Compromised Dentition Dr Stuart Lee BDS Cert. Adv Pros ◉ Fall 2024 Compromised dentition? Caries Trauma Tooth surface loss Periodontal...

Restoration Of Compromised Dentition Dr Stuart Lee BDS Cert. Adv Pros ◉ Fall 2024 Compromised dentition? Caries Trauma Tooth surface loss Periodontal disease Assess The Restorability of the Tooth During extirpation in endo or emergency clinic After removing compromised tooth structure During caries clean out Restorability check should be done BEFORE any other treatment (e.g. RCT) is initiated  Assess The Restorability of the Tooth What to look out for? Remaining sound tooth structure De nitive restoration Ferrule Material Retention of an indirect Bonding? restoration Any other treatment needed Pulpal involvement / elective RCT Periodontal disease Surgical crown lengthening Ortho (Uprighting, extrusion) fi Remaining Sound Tooth Structure The strength of a tooth is directly related to the amount of remaining sound tooth structure No process except uoride application can strengthen a tooth Remaining sound tooth structure may dictate the position of the restorative nish line e.g. going sub-gingival to increase wall height Minimal height of rst plane of axial wall for retention needed Horizontal thickness of tooth structure to avoid perforating the pulp chamber fi fi fl Remaining Sound Tooth Structure Visualize preparation of the nal restoration Imagine how much tooth structure left AFTER preparation of the nal restoration fi fi  Ferrule Effect Ferrule Effect Ferrule: ❖ Definition: A 360˚ metal collar of the crown surrounding the parallel el Aofband walls or ring the dentine usedcoronal extending to encompass the to the shoulder root or crown of a of the tooth which preparation (GPT-9) will improve the resistance form of the crown. (Sorensen JPD 1984) A 360° metal collar of the crown surrounding the parallel wall ❖ of the A metal banddentine extending or ring used coronal to fit the root or crown to of athe toothshoulder of the (GPT-8) ) preparation which will improve the resistance form of the crown (Sorensen JPD 1984) Ferrule Effect Ferrule How much tooth structure is enough for “Ferrule Effect” Thickness 1-1.5mm 360°! Ferrule effect for: Improved fracture resistance Tooth ht 1.5 -2mm For retention, wall height needs to be augmented ❖ Definition: A 360˚ metal collar of th Ferrule Effect Ferrule Effect No Ferrule Effect Compromised dentition may have pulpal involvement Compromised dentition may Elective endodontic treatment have pulpal involvement Post and core Caries into the pulp Further required preparation of Necrotic pulp sound tooth structure may Trauma involving pulp compromise the pulp Courtesy of Dr E. Sheh Restoration of Endodontically Treated Teeth Before RCT initiated Ferrule Effect Restorability check of the tooth Post and Core Restorative plan for the tooth Different Post and Core systems Global restorative plan What happens to the tooth after RCT? RCT involves removing tooth structure in an already compromised tooth Shaping of the canal walls Access to pulp chamber Leads to a loss of stiffness in teeth Endodontic procedures => 5% lower stiffness MOD cavity preparation => 63% lower stiffness Largest losses in stiffness were related to the loss of marginal ridge integrity Restoration after RCT After RCT, tooth may be restored with a direct or indirect restoration Depends on the amount of sound tooth structure lost Cuspal coverage of posterior (premolar and molar) root treated teeth enhances their survival Anterior teeth in intact marginal ridges or small proximal restoration may be restored with composite (Shillingburg) Bhuva B, Giovarruscio M, Rahim N, Bitter K, Mannocci F. The restoration of root lled teeth: a review of the clinical literature. Int Endod J. 2021 Apr;54(4):509-535. Consideration: Good, long term coronal seal!! Stavropoulou AF, Koidis PT. A systematic review of single crowns on endodontically treated teeth. J Dent. 2007 Oct;35(10):761-7. Courtesy of Dr E. Sheh fi Retention of Core & Crown BUT Little/no tooth structure to retain the Problem: restorative material (core buildup) Wall height needs to be lengthened for A post will be needed to retain the core retention Crown Solution: Core Restorative material (core) placed to lengthen wall height Post Gutta-Percha Courtesy of Dr E. Sheh Endodontic Dowel/Post Connects the replacement (restorative “ A post-core does not increase the material) for the missing coronal portion fracture resistance of endodontically of the tooth to the remaining root treated teeth” structure Guzy GE: J Prosthet Dent 1977 Function of a post: “Preparing a post space signi cantly Stress distribution (along the root) weakened endodontically treated Retention of core teeth” Does NOT reinforce the tooth structure Trope M, et al: Endodont Dent Traumatol 1985 fi Post and Core Indications and Considerations Remaining tooth structure Types of tooth Variability in post & core survival: Adequate RCT 98.6% after 10 years (Weine et al. 1991) 77.6% 5.2 years (Roberts et al. 1970) Overall treatment plan Type of restoration Even when restored with a post and core, it is Patient factor still a compromised tooth! Prognosis is not ideal! Post and Core Indications and Considerations Courtesy of Dr C. Park Prerequisites for tooth to receive post and core Good apical seal No sensitivity to pressure No exudate Good quality endodontic therapy! No stula No apical in ammation No active in ammation fi fl fl Ideal Properties of a Post and Core 1. Physical properties similar to dentin 2. Retention & preservation 7. Retrievability 3. Esthetics 8. High core retention 4. Minimal stress during delivery 9. Post compatibility with core 5. Resistance to dislodgment 10. Ease of use and reliability 6. Distribution of functional stresses evenly 11. Reasonable cost along the root surface How Long Should the Post Be? Apical Seal When Cementing 3-5mm apical GP Increased length (imbedment) increases retention Equal or exceed the length of the Post (Dowel) length ≥ Crown length crown (~8-11mm) As long as possible without disturbing the apical seal! Standlee JP, Caputo AA, Hanson EC. Retention of endodontic dowels: Effects of cement, dowel length, Shillingburg HT. Fundamentals of Fixed Prosthodontics. 4th ed. Quintessence Pub.; 2012. diameter, and design. The Journal of prosthetic dentistry. 1978;39(4):401-405. How Long Should the Post Be? When Bonding Apical Seal still needed!! Rely on adhesive bonding for 3-5mm apical GP retention ½ distance into bone E.g if 10mm root in bone, post needs to be min 5mm If there is 3mm crestal bone loss, 8mm post is needed May be calculated or estimated radiographically  How Long Should the Post Be? Apical Seal 3-5mm apical GP Crestal Bone Level Crestal Bone Level Length of post into bone: Length of post into bone: 50% Additional length of post within Apical Seal: 5mm Apical Seal: 3mm bone How Long Should the Post Be? Apical Seal still needed!! 3-5mm apical GP How to calculate? Based on the working length obtained during endo treatment You MUST know the reference point used to calculate working length! How Wide Should the Post Be? Diameter NOT related to retention Increased diameter decreases strength of tooth Increased diameter increases stress in the tooth As wide as it can be with as little preparation Standlee JP, Caputo AA, Hanson EC. Retention of endodontic dowels: Effects of cement, dowel length, diameter, and design. The Journal of prosthetic dentistry. 1978;39(4):401-405.  How Wide Should the Post Be? Very wide posts! Courtesy of Dr E. Sheh Post Systems Threaded Smooth Sided Serrated (Active) Custom Tapered Shape Surface Type Con guration Prefabricated Parallel fi Post Systems Resin-Matrix Wax Metal Zirconia Ceramic Cemented Material Retention Bonded Figure from Alkhatri R, Saleh ARM, Kheder W. Evaluating Fracture Resistance And Failure Modes Of Root Filled Teeth Restored With CAD/CAM-Fabricated Post And Core. Clin Cosmet Investig Dent. 2019 Nov 14;11:349-355. Post Systems- Shape & Surface Configuration Threaded Smooth Sided Serrated (Active) Failure: Post Retention (Standlee 1978): Tapered posts: exhibit a wedging effect Tapered < Parallel Sided and produce the highest shoulder Smooth sided < Serrated < Threaded stresses Stress Distribution Parallel: failure of the cement layer Parallel posts resist tensile force 4.5x Parallel-serrated posts have most of the cement adhering to the more than tapered posts (Johnson & dowel Sakumura 1978) Threaded posts: fail by dentinal fracture usually with one clean Standlee JP, Caputo AA, Hanson EC. Retention of endodontic dowels: Effects of cement, dowel length, diameter, and design. The Journal of prosthetic dentistry. longitudinal split in the root 1978;39(4):401-405. doi:10.1016/S0022-3913(78)80156-5 Post Systems Metallic Non-Metallic Zirconia Fiber reinforced Polyethylene bers Custom Prefabricated epoxy or methacrylate resin in resin composite Cast post & core Titanium Stainless steel Carbon - black Quartz ber Glass ber Rigid Flexible fi fi fi Custom Cast Post & Core Custom Post & Core pattern invested and cast Usually used when theres less than ideal ferrule effect There is no pulp chamber to help retain the core Usually cemented Requires 2 visits Courtesy of Drs C. Park and E. Sheh Custom Cast Post & Core Usually anteriors or premolars In multirooted premolars Dowel of optimal length made for most desirable (straightest) canal Second canal accommodates a short key that serves as an anti rotation feature (adds little or no retention) Molars have divergent canals which may require elaborate interlocking multi-piece casting Custom Cast Post & Core ** Uses Parapost system.These drills are DIFFERENT from the ber post drills you will use in the integrated course! Parallel sided! Courtesy of Dr C. Park fi Custom Cast Post & Core Post Space Prepared Post tried in Courtesy of Dr C. Park Custom Cast Post & Core Insert (to prepared If needed add more to Apply a small amount of Once doughy, pump in length) into canal. cover pulp chamber, leaving Duralay on the post and out some post exposed Courtesy of Dr C. Park  Custom Cast Post & Core Build up the remaining coronal aspect Once fully set, the preparation for the de nitive restoration is completed with the pattern in place Courtesy of Dr C. Park fi Custom Cast Post & Core Courtesy of Dr C. Park Custom Cast Post & Core Courtesy of Dr C. Park Custom Cast Post & Core- Interlocking Post Molars Multiple, Divergent roots Courtesy of Dr E. Sheh Other “Posts” you might meet when fabricating a custom cast post and core Burnout post- serrated surface, parallel walled Temporary post- smooth sided Impression post- plastic, smooth sided Mimics the surface of the de nitive post Easy to remove Pick-up impression fi Prefabricated Metal Posts 2.5-3mm Cement prefabricated post in a large main canal Posts should be avoided in mesial root of mandibular molars & buccal roots of maxillary molars. Mostly used as a temporary post Top of post: 2.5-3 mm from the opposing occlusion. Usually serrated, parallel sided Shortening the post from the top is usually necessary The prefab post need to be in the core build up Prefabricated Metal Posts Prefab. Metal post in Amalgam core buildup palatal canal Courtesy of Dr E. Sheh Zirconia Posts Advantages: Limited data on zirconia posts Favorable esthetics over 10-year retrospective study metal showed a survival probability of Disadvantages: 81.3% (Bateli et al. 2014) Rigid - possible root fractures 3-6 year Survival rate: 96%; Does not bond to composite Success rate 92.4% (Ying et al. 2022) Ying, S., Chen, S., Wang, S. et al. Outcome of teeth restored with CAD/CAM zirconium dioxide post-cores: a retrospective study with a follow-up period of 3–6 years. BMC Oral Health 22, 236 (2022). Problems with Rigid Posts- Catastrophic Failure Rigid posts have an elastic moduli much higher than dentine Stress is transmitted internally and concentrates towards the apical level Increases risk for vertical root fracture Goracci C, Ferrari M. Current perspectives on post systems: a literature review. Aust Dent J. 2011 Jun;56 Suppl 1:77-83. doi: 10.1111/j.1834-7819.2010.01298.x. PMID: 21564118.  Fiber reinforced Epoxy or methacrylate resin Advantages: Contemporary adhesively luted Similar elastic properties to dentine bre-reinforced composite posts Allow for a relatively uniform stress have manifested satisfactory survival distribution to the tooth and rates surrounding tissues Attributed to less rigid- fewer root Favorable esthetics over metal fractures Made of carbon, quartz of glass bers, Ease of use Restorable failures such as post embedded in a matrix of epoxy or Disadvantages: debonding more likely to occur methacrylate resin Both post and core rely on dentine bonding Isolation important Goracci C, Ferrari M. Current perspectives on post systems: a literature review. Aust Dent J. 2011 Jun;56 Suppl 1:77-83. fi fi  Fiber reinforced Epoxy or methacrylate resin Posts are bonded Post space preparation important for success Most reliable results in bre post bonding are Bond strength affected by: obtained by etch-and-rinse adhesives in Sodium hypochlorite, EDTA, hydrogen peroxide, combination with dual-cure resin cements RC Prep, as well as calcium hydroxide and Dual-cure resin cement eugenol of medicaments and sealers Dif culty getting the light to fully penetrate post space, even with translucent posts Goracci C, Ferrari M. Current perspectives on post systems: a literature review. Aust Dent J. 2011 Jun;56 Suppl 1:77-83. doi: 10.1111/j.1834-7819.2010.01298.x. PMID: 21564118. fi fi ParaPost Taper Lux- 60% Glass Fiber in 40% Resin Matrix Post drill burs with Resin cement ParaPost Taper Lux Kit corresponding post +/- core build up material Bur is tapered too Tapered Serrated Technique will be covered in the Integrated course  Polyethylene Fiber Posts Ultra-high molecular weight polyethylene Modulus of elasticity similar to bers coated with dentine bonding agent dentine Flexible and is able to adapt to the root More favorable stress distribution canal along the root No canal enlargement needed (according Few clinical studies and short follow to manufacturer) up periods Website: https://ribbond.com/applications-post-and-core.html#anchor Goracci C, Ferrari M. Current perspectives on post systems: a literature review. Aust Dent J. 2011 Jun;56 Suppl 1:77-83. doi: 10.1111/j.1834-7819.2010.01298.x. PMID: 21564118. fi Does every tooth need a Post? Anterior teeth in intact marginal ridges or small proximal restoration may be restored with composite (Shillingburg) Think about how severely compromised the tooth was to begin with NO! How conservative is the access and endo prep? Is there enough coronal tooth structure to retain a core? What are the forces against this tooth? Core Material Resin Composite: Amalgam: Shrinkage & dimensional change Less technique sensitive Low elastic modulus Higher initial strength Reliability of dentine bonding Time consuming and technique sensitive Amalgam Dowel & Core (“Nayyar Core”) Amalgam Coronal-Radicular Dowel & Core Technique Eliminates need for preparation, impression and Described by Dr Arun Nayyar in 1980 cementation of post and core Contraindicated when 2-4mm of GP removed from each Insuf cient depth in the remaining pulp canal and amalgam is condensed in chamber for retention Inadequate wall thickness for strength Divergent canals and natural undercuts in the pulp chamber provide retention for the core Courtesy of Dr E. Sheh fi FPD abutments? Should compromised dentition be used as FPD abutments? How compromised? Remember, almost any tooth can be restored with determination. But is it worth it? What are the forces against it? Can we offer a more predictable treatment? Will the patient accept the alternative treatment? Fin