Objectives: Fibre posts are frequently used for esthetic restorations. The aim of this study was to evaluate the effect of cyclic loading on the bond strength of the fibre post D.T. Light Post using different post diameters. Methods: Sixty caries free single rooted teeth that were selected for standardized size and quality were endodontically prepared and coronally reduced to the cemento-enamel junction. Post holes were prepared using the corresponding burs (10 mm in length). The specimens were randomly assigned to three experimental groups: (A): insertion of DT Light Post #1, (B): DT Light Post #2; (C) DT Light Post #3. Fibre posts were luted with Panavia F according to the manufacturers instructions. The restored teeth were stored in water at 37°C for at least 1d. Tensile tests were performed using a universal testing machine. Each group was subdivided into two subgroups (1 and 2): 1: immediate loading to maximum bond strength; 2: maximum load after 100 cycles (between 10 and 20 N). Data were analyzed with SPSS 12.0. Results: Following mean retentive strengths were evaluated:
|
|
|
A1 |
A2 |
B1 |
B2 |
C1 |
C3 |
|
Mean value and standard deviation |
in N |
127.58 (+/- 28.56) |
98.28 (+/- 15.77) |
163.37 (+/- 35.85) |
124.39 (+/- 26.41) |
200.98 (+/- 28.66) |
161.73 (+/- 28.29) |
|
in MPa (N/mm²) |
12.51 (+/- 2.80) |
9.63 (+/- 1.54) |
14.26 (+/- 3.13) |
10.86 (+/- 2.30) |
14.68 (+/- 2.09) |
11.91 (+/- 1.90) |
Analysis of variances test revealed that the post diameter did not affect the bond strengths the fibre posts of the D.T. Light Post system (p< 0.05, Tukeys test). Pairwise comparison showed that loading after 100 cycles decreased the bond strengths of the posts (p< 0.05, Tukeys test). Conclusions: The D.T. light post system showed acceptable tensile bond strengths. Cyclic loading decreased the bond strengths of all diameters of fibre posts used.