Reciprocating instrumentation in a maxillary primary central incisor: A protocol tested in a 3D printed prototype

Background Efficient endodontic instrumentation of primary teeth is a challenge for paediatric dentists. Aim To evaluate biomechanical outcomes of endodontic instrumentation with a reciprocating system in a polymer-prototyped primary maxillary central incisor. Design The specimen was systematically instrumented and micro-CT scanned before and after each file. The amount of debris, percentage of non-instrumented areas, removed dentin volume, and lower dentin thickness at specific points along the root canal were analyzed. Results A 10% increase in removed dentin volume was observed when R40 was compared to R25 (14.5% vs 4.2%). When comparing R50 with R40, this increase was only 3.4% (17.9% vs 14.5%). In the root cervical third, there was substantial reduction in dentin thickness with R50 (48.8%), followed by R40 (39.5%) and R25 (18.6%). There was no difference between R25 and R40 in the removal of dentin at the apical third (15.8%), while R50 resulted in 39.8% reduction in dentin thickness. Percentage of non-instrumented areas were the same for all files. Accumulated debris with R40 and R50 was the same (0.19 mm(3)) while for R25 was 0.11 mm(3). Conclusions The Reciproc((R)) system was effective for instrumentation of a prototyped primary maxillary central incisor. The most suitable file for apical preparation was R40.