A temporary filling material during endodontic treatment may cause tooth fractures in two-surface class II cavities in vitro.

OBJECTIVES: To investigate the effect of a zinc oxide/zinc sulphate-based cement as a temporary filling material during root canal treatment on the occurrence of cracks within the filling material or the tooth. MATERIALS AND METHODS: Root canals of 122 extracted human molars were prepared using ProTaper instruments. Standardized occlusal-distal cavities were prepared. After placing calcium hydroxide into the root canals, the teeth were divided randomly into four groups containing 33 specimens each. In the Coltosol group, the cavity was completely filled with Coltosol® F. In the Coltosol-Clearfil group, a 2-mm layer of Coltosol® F was placed into the apical part of the pulp chamber, and in the Clearfil group, a foam pellet was placed into the coronal pulp chamber. The remaining cavities were filled with Clearfil™. In the control group, the cavities were not restored. The teeth were stored at 37 °C for 14 days and examined every 24 h under a stereomicroscope. RESULTS: Fractures of the filling and/or the tooth were only observed in the Coltosol group. All Coltosol® F restorations had cracks after 24 h. Tooth fractures were found in 25 (76 %) teeth. Among these teeth, 21 (84 %) had crown fractures, four (16 %) had root-crown fractures. All root-crown fractures were vertical. CONCLUSION: Coltosol® F when used alone led to tooth fractures in two-surface class II cavities in teeth undergoing root canal treatment. CLINICAL RELEVANCE: Coltosol® F solely used as restorative material may lead to tooth fractures in two-surface class II cavities.