Original Research Article Indian Journal of Conservative and Endodontics, October-December,2016;1(3):93-96 93 In vitro evaluation of the strength of endodontically treated teeth after preservation of soffit and pericervical dentin Ashwini Gaikwad 1,* , Varsha Pandit 2 1 Professor, 2 Associate Professor, Dept. of Conservative Dentistry and Endodontics, Bharati Vidyapeeth Deemed University Dental College and Hospital, Pune *Corresponding Author: Email: aagaikwad931@gmail.com Abstract Aim: To evaluate the strength of an endodontically treated tooth after preservation of peri-cervical dentin and soffit. Methodology: 30 human molars having well developed cusps and morphology were extracted for periodontal reasons were included in this study. They were divided in two groups. In gp. A, Clark- Khademi access was made and endodontic treatment was carried out with 2% NiTi K-files and in gp. B, Straight line access was made and endodontic treatment was carried out with 2% NiTi K-files. Normal endodontic treatment was carried out with 2% flexible NiTi K-files with 17% EDTA as chelating agent and 5.25% Sodium Hypochlorite solution for irrigation. Obturation was carried out using the lateral condensation technique with gutta- percha coated with sealer. After this, the pulp chamber was cleaned thoroughly with cotton and all-in-one bonding agent was applied and scrubbed with an applicator tip for 30 seconds. Next, Composite restoration was done as post-obturation restoration. Specimens were then tested with a universal testing machine, set to deliver an increasing load until failure. Failure was defined as a 25% drop in the applied load. The load was applied parallel to the long axis of the tooth. The variable of interest was the load at failure measured in Newtons. The data thus obtained was subjected to statistical analysis and was analysed using one way ANOVA test for significance with Bonferroni corrections. Result: The teeth with Clark-Khademi access preparation with 2% taper of the endodontic files were more efficient at resisting the fracture than the teeth with straight line access preparation with 2% taper of the endodontic files. Conclusion: The teeth after preservation of pericervical dentin and soffit were found to be structurally reinforced as compared to the teeth with straight line access. Clark-Khademi access preparation was found to be more effective at dentin preservation and strengthening the tooth when compared to straight line access. Keywords: Soffit, pericervical dentin, Strength of endodontically treated teeth. Introduction Access cavity preparation is the first and arguably the most important phase of root canal treatment. A well- designed access preparation is essential for a good endodontic result. Without adequate access, instruments and materials become difficult to handle properly in the highly complex and variable root canal system. (1) A properly prepared access cavity creates a smooth, straight- line path to the canal system and ultimately to the apex. Ideal access results in straight entry into the canal orifice, with the line angles forming a funnel that drops smoothly into the canal(s). (2) A Traditional access cavity generally has tapering walls with its widest dimension at the occlusal surface. Stainless steel files were used which were stiffer and were not so efficient in negotiating the curvatures of the root canal. To counter this, a large wider access preparation was advised. (3,4,5) But, wider access preparation done traditionally, resulted in unnecessary dentin removal and hence weakening of the tooth structure. The advent of Nickel-titanium instruments paved way for more conservative access preparations, as these files are super elastic and flexible which can negotiate the canal curvatures easily. Drs. Clark and Khademi have described a concept of conservative endodontic access cavity preparation. This concept negates the traditionalist straight-line access protocol and the total deroofing of the pulp chamber. (6) Drs. Clark and Khademi have coined the term “soffit”, which is a small piece of dentin roof around the entire pulp chamber, to preserve the critical region of peri-cervical dentin (PCD) that is 4mm above and below the crestal bone, without compromising debridement and without inducing iatrogenic misadventure. This type of more constrained, constricted and conservative access cavity encourages the preservation of dentin, thus increasing the strength of the remaining tooth structure and thus prevents the chances of fracture of the tooth. (3,6) The prognosis of endodontically treated teeth depends not only on the success of the treatment but also on the amount of remaining dentin. Fractures of restored endodontically treated teeth are a common occurrence in clinical practice, due to excessive removal of dentin. (7) So improvement in the access cavity preparation to save the unnecessary removal of dentin is required. (6) In light of these observations, we had planned to evaluate the strength of an endodontically treated tooth after preservation of dentin at the soffit region and at the pericervical area.