Alternative EndoCrowns Designs for Chairside CAD/CAM

Clinical Performance of Alternative Preparation Designs for Chairside CAD/CAM Fabricated Advanced Lithium Disilicate EndoCrowns

This investigation will be a longitudinal clinical trial to study the association of preparation design on the internal and marginal adaptation of the resulting restorations and the long-term clinical performance of chairside CAD/CAM endocrown restorations. Advanced lithium disilicate chairside CAD/CAM endocrowns (CEREC Tessera/Dentsply Sirona) will be adhesively bonded using a selective enamel etch technique with a universal adhesive (Prime and Bond Elect/Dentsply Sirona) and a dual cure resin adhesive cement (Calibra Ceram/Dentsply Sirona). All restorations will be followed over five years of clinical service.

Endodontically treated teeth commonly present with extensive tooth structure loss due to caries, trauma, prior restorative treatment, and the endodontic access. These structural deficiencies lead to an increase in cusp deflection, crown fractures, microleakage, and decreased sensory feedback during function which greatly increases the possibility of tooth fracture.As a result, endodontically treated teeth require a full cuspal coverage restoration to prevent microleakage, restore function, and provide cuspal protection against tooth fracture. The most common restoration for endodontically treated teeth is core build-up, with or without a post, and full coverage crown. This process requires multiple appointments with many technical steps ultimately leading to more chair time, treatment cost, and potential iatrogenic damage to the tooth. An alternative treatment is the endocrown, which utilizes the internal walls of the pulp chamber for macroretention and incorporates the core and crown in a monolithic restoration. The restoration is fabricated utilizing chairside CAD/CAM technology and is adhesively bonded to the tooth with resin cement. The EndoCrown restoration is more conservative relative to tooth structure loss, less expensive, and requires less chair time to complete when compared to conventional treatment while having comparable clinical longevity in molar teeth. This investigation will be a longitudinal clinical trial to study the association of preparation design on the internal and marginal adaptation of the resulting restorations and the long-term clinical performance of chairside CAD/CAM endocrown restorations. Advanced lithium disilicate chairside CAD/CAM endocrowns (CEREC Tessera/Dentsply Sirona) will be adhesively bonded using a selective enamel etch technique with a universal adhesive (Prime and Bond Elect/Dentsply Sirona) and a dual cure resin adhesive cement (Calibra Ceram/Dentsply Sirona). All restorations will be followed over five years of clinical service.

Endocrown onlay preparation = Buccal and lingual walls are intact with an occlusal-gingival height at least equal to half the original crown height of the tooth. Remaining buccal and lingual walls maintain a thickness ≥ 2.0 mm.

Endocrown shoulder preparation = Buccal and/or lingual walls are less than half the original occlusal-gingival height of the tooth or the buccal or lingual surfaces were previously prepared axially due to a prior restoration.

Restoration failure is scored by visual loss of the crown from the tooth requiring replacement of the study crown with a new crown at any time between delivery and five years.

Loss of retention is measured as visual detachment or dislodgment of the crown from the tooth without fracture of the crown requiring recementation of the crown.

Margin staining is categorized based on modified US Public Health Service criteria using a four point scale where 1 is no staining and 4 is penetrating stain involving more than 50% of the margin.

Inclusion Criteria: Subject in need of final restoration following molar endodontic therapy Subject age 18 or above - Exclusion Criteria: Teeth with remaining symptoms following endodontic therapy Teeth which have experienced endodontic complications to include treated perforations, internal or external resorption, or separated endodontic files. Teeth with exposure of the root canal filling material to the oral environment for greater than two weeks Teeth diagnosed with symptoms of incomplete tooth fracture Teeth with no adjacent or opposing tooth Teeth serving as an abutment for fixed or removable dental prostheses Subjects with uncontrolled bruxism or parafunctional habits Subject has known allergies to any product used in this study Subject will not be available for the study duration of 5 years Subjects with significant untreated dental disease to include periodontitis and rampant caries Women who self-report that they are pregnant or lactating -