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 mm³) while for R25 was 0.11 mm³.

Conclusions: The Reciproc^® system was effective for instrumentation of a prototyped primary maxillary central incisor. The most suitable file for apical preparation was R40.