Comparison of the bond strength of five different composites used in the production of clear aligner attachments.

AIM

The aims of this study were to measure and compare shear bond strength (SBS) and manipulation time (MT) among five different composite resins (CR; two flowable and three highly viscous) which are used in the production of clear aligner attachments.

MATERIAL AND METHODS

This in vitro experiment study comprised of 150 extracted premolars which were divided into 5 equal groups. Predictor variables were CRs; Tetric Evo Ceram (Ivoclar VivadentAG, Liechtenstein) (Group 1), Tetric NCeram; (Ivoclar VivadentAG, Liechtenstein) (Group 2), Tetric N-Flow (GC Dental Products, Tokyo, Japan) (Group 3), G-aenial Universal Injectable (GC Dental Products, Tokyo, Japan) (Group 4), GC Aligner Connect (GC Dental Products, Tokyo, Japan) (Group 5), respectively. Outcome variables were; SBS and MT for each CR attachment in each group of teeth. Oneway ANOVA was used to compare the groups. Levene's test was used to determine variance homogeneity. In terms of variance homogeneity, Bonferroni tests were used as a post-hoc test for multiple group comparisons.

RESULTS

SBS was statistically different between study groups (p < 0.001). Average SBS values ​​are found to be 16.6 ± 3.6 MPa for Tetric Evo Ceram; 20.7 ± 5.4 MPa for Tetric NCeram; 21.0 ± 4.0 MPa for Tetric N-Flow; 18.9 ± 5.0 MPa for G-aenial Universal Injectable; and 17.4 ± 3.5 MPa for GC Aligner Connect. The values ​​in the Tetric Evo Ceram group were significantly lower than the Tetric N-Ceram group (p = 0.004) and the Tetric N-Flow group (p = 0.001). Mean value of shear bond strength in the GC Aligner connect group were significantly lower than in the Tetric N-Ceram group (p = 0.047) and in the Tetric N-Flow group (p = 0.017). Flowable composite had a significantly shorter manipulation time than the high viscous one; mean 1,08 ± 0,22 min to mean 4,57 ± 0,51 min, respectively.

CONCLUSION

Although SBSs of CRs tested in the study was found to be statistically different, they all quite exceeded the accepted clinically sufficient value of 6-8 MPa. Besides, flowable composite required substantially less time to manipulate than the high viscosity composite.