CONE BEAM COMPUTED TOMOGRAPHIC EVALUATION OF FRACTURE STRENGTH OF MAXILLARY MOLARS WITH THREE DIFFERENT ACCESS CAVITY DESIGNS. - AN INVITRO STUDY

Abstract

Aim: To evaluate the fracture strength of endodontically treated extracted maxillary molars with three different access cavity designs– Traditional Endodontic Cavity (TEC), Conservative- “TRUSS” Endodontic Cavity (CEC) and Ultra conservative “NINJA” Endodontic Cavity (NEC)access preparations and to correlate it to the volume percentage of enamel and dentin removed which was measured using Cone Beam Computed Tomography.

Materials And Methods: Sixty intact human maxillary molars extracted for periodontal reasons were selected and the samples were randomly grouped (n= 20) into Group I – Traditional (TEC), Group II – Conservative (CEC) and Group III - Ninja (NEC) endodontic access cavities. All the tooth samples were subjected to a Pre- operative CBCT imaging (NEWTOM cone beam computer tomography). Using Digital Imaging and Communications in Medicine data (DICOM) software the total enamel and dentin crown volume for each tooth were calculated. Then, access cavities  of all teeth were prepared in respected groups and then subjected to a post-operative CBCT imaging. The volume percentage of coronal enamel and dentin removed by the 3 access cavity preparations were calculated using DICOM software again. The biomechanical preparations and obturation were done, followed by a post-endodontic coronal restoration with light cure composite resin. The samples were then tested for the fracture resistance using the Instron Universal Testing Machine. The loads at which the tooth crowns were fractured were recorded in Newtons. The data obtained were statistically analyzed.

Results: The results showed that as the Volume of the tooth structure removed during the cavity preparation is inversely proportional to the fracture resistance of the teeth. Hence the Group III NEC group showed statistically significant mean difference values with minimal loss of  volume % of tooth structure removed (7.92%),suggesting that this can influence positively in the increase in fracture resistance (1403.08 N) of the tooth following a coronal restoration.

Conclusion: Within the limitations of this study it can be concluded that the Group III Ultra-conservative ”NINJA” access showed increased fracture resistance of endodontically treated maxillary molars with the least mean volume percentage of tooth structure removed when compared to TEC and CEC groups.

Keywords:

Traditional Access cavity, Truss access, Ninja access, Cone beam computed tomography, Post- Endodontic Restoration, Fracture resistance.