Periodontal Blood Flow Protects the Alveolar Bone from Thermal Injury during Thermoplasticized Obturation: A Finite Element Analysis Study.

INTRODUCTION: The purpose of this study was to investigate the heat transfer during thermoplastic obturation and the cooling capacity of blood flow in the periodontal ligament (PDL) using finite element analysis (FEA).

METHODS: A 3-dimensional digital tooth model was constructed based on micro-computed tomographic scanning of a mandibular first molar after chemomechanical preparation in vitro. A layer of PDL with or without simulated blood flow was built on the root portion of the tooth in software. Two heat-assisted obturation techniques (ie, the single-wave condensation technique and the warm vertical compaction technique followed by backfilling with injectable gutta-percha) were examined using an FEA package.

RESULTS: In the model without blood flow, the highest temperature at the alveolar bony aspect of the PDL was 50.0°C along the distal canal and 52.5°C for the mesiolingual canal when the single-wave technique was used. With the warm vertical compaction technique, the highest temperature was 47.3°C for the distal canal and 47.8°C for the mesiolingual canal. In the model with simulated periodontal blood flow, a notable drop in the peak temperatures at the root surface and at the adjoining alveolar bone was observed for both the distal and mesiolingual canals; all peak temperatures at the PDL fell below 47°C regardless of the obturation techniques used. The greatest rise in temperature was situated at the furcation aspect of the middle third of both roots.

CONCLUSIONS: The cooling capacity of blood flow in the PDL is a factor that must be considered in the investigation of heat transfer during thermoplastic obturation.