Filling material effects on root canal treatment outcomes of 83 canine teeth in cats using a taperless rotary file system

Objectives This study aimed to evaluate the clinical outcomes of root canal treatment (RCT) for canine teeth in cats by determining the optimal master apical file (MAF) size via a taperless rotary file system and comparing three different filling materials. Methods A total of 83 fractured canine teeth from 78 cats were treated with a taperless nickel–titanium file system. Three different filling materials were used: (1) a silicone-based sealer with a single gutta-percha (GP) cone; (2) a bioceramic sealer with a single GP cone; and (3) a bioceramic plug at the apex followed by a silicone-based sealer and a GP cone for the residual pulp canal. The MAF size was determined by enlarging the apical portion to three International Organization for Standardization sizes beyond the initial apical file. Treatment outcomes were classified as success, no evidence of failure and failure. Outcome-related factors were identified via multivariable logistic regression. Results The overall success rate was 91.6%. The bioceramic sealer showed the highest success rate (97%), followed by the bioceramic plug (95%) and the silicone-based sealer (83.3%). Overfill and pre-existing periapical lesions were significantly associated with reduced success. The overfill rates of bioceramic sealers and plugs were significantly lower than those of silicone-based sealers. The MAF size showed a significant positive correlation with body weight and a negative correlation with age. Conclusions and relevance A taperless file system could be used to facilitate precise apical shaping tailored to the fusiform anatomy of canine teeth in cats and thus improve treatment outcomes. These findings support the use of bioceramic sealers in a single-cone obturation technique and highlight the importance of achieving an optimal MAF size to enhance the success of RCT for canine teeth in cats.