Summary:
Purpose: to evaluate and compare the effect of access cavity preparation and 3 different root taper preparations on endodontically treated teeth (ETT) fracture resistance of maxillary molars
•Materials/Methods:
•2 samples
•n: 30 maxillary first and second molar 3 groups for (04, .06, or .08) taper
•Teeth were cleaned and shaped using twisted files rotary system
Inclusion criteria; exclusion criteria; were stated •n: 48 3 groups: intact teeth, no treatment; traditional access cavity (TAC); and conservative access cavity (CAC)
Highlights:
•04 taper showed the highest and the .08 taper showed the lowest fracture resistance values Fig.1,2
•No significant difference between CAC and TAC but significant difference with intact teeth were noted
Conclusion:
1. Increasing the tapering of root canal preparation can detrimentally affect tooth fracture resistance
2. Conservative endodontic access in maxillary molars was not shown to significantly increase fracture resistance over traditional access

