Abstract: Objective: To evaluate the operation time and clinical bonding failure of four types of bonding materials (Filtek Z350 XT nano filling composite resin, Filtek Z350 XT nano flowable composite resin, Tetric N-flow composite resin, Tetric N-cerum filling composite resin) in bonding attachment of removable thermoplastic appliance. Methods: Sixty malocclusion patients using removable thermoplastic appliances were randomly divided into four groups. 3M Z350 nano filling composite resin and Z350 nano flowable composite resin were used in group A and B, respectively. Tetric N-flow composite resin and Tetric N-cerum filling composite resin were bonded in group C and D, respectively. The operation time of each group was recorded. Failure rates of adhesion were evaluated at the end of adhesion, and 1 month, 6 months, 9 months, and 12 months after adhesion. Results: The operation time of flow composite resin group was shorter than that of filling composite resin group (P<0.01). The adhesion failure rates were not significant different among four groups in the first 6 months. Significant difference was found between flow composite resin group and filling composite resin group after 9 and 12 months (P<0.01). However, no difference was found between optimized attachment and traditional attachment. Conclusion: The attachment stability of four types of materials could achieve satisfactory effect in the first 6 months. After 9 months, filling composite resin was more stable than nano flowable composite resin. However, the operation time of nano flowable composite resin was more efficient.

Key words: Removable thermo plastic appliances, Attachment, Composite resin