The aim of this in vitro study was to compare three orthodontic band cements for gaps remained between tooth and band surfaces, at the cervical margin, which possibly caused after banding procedure. Sixty freshly extracted human mandibular third molars were randomly divided into 3 equal groups. Micro-etched molar bands were cemented to the teeth using each of the orthodontic band cements (Ketac Cem®, 3M Multi-Cure® and Transbond Plus®). The teeth were placed in preformed boxes (2.5X2.5X2.5 cm); crowns were on the bottom and perpendicular to the ground. Samples were capped with black colored plaster on a vibration machine. After hardening of the plasters, samples were removed from the boxes and were trimmed in the bucco-lingual dimension for evaluation. The mean of four parallel sections examined under a stere-omicroscope was noted as the score of that sample, for buccal and lingual sides, separately. Statistically analyses were performed by using analysis of variance and paired-samples t-test. When buccal and lingual gap formations were compared, Transbond Plus® and Ketac Cem® groups were found to have larger gaps in the lingual side than buccal at p<0.05 and p<0.01 level, respectively. Thus, buccal and lingual gaps of three cements were compared separately, and no statistically significant difference was determined among three investigated cement types at buccal and lingual sides. However no differences were found among different types of band cements, it is clear that large gaps were observed under molar bands at cervical margin; where it is not easily possible to clean. Further studies should be conducted to determine a favorable strategy to eliminate these gaps and maintain a gap-free adaptation and cementation between band and tooth structure.

Keywords: Band, Cement, Gap formation.