A comparative evaluation of fractural strength and marginal discrepancy of direct composite veneers using four different tooth preparation techniques: An in vitro study.

Background: The direct composite veneers follow the concept of no preparation or minimal preparation that has developed an appropriate enamel bonding procedure. The composite veneers can be easily repaired and thus they are economically favorable. The long-term clinical performance of direct composite veneers depends on a number of factors, with fracture resistance and marginal adaptation being one of the significance.

Aim and Objective: The aim of the present study was to evaluate the fractural strength and marginal discrepancy of direct composite veneers using four different tooth preparation techniques (window preparation, feather preparation, bevel preparation, and incisal overlap preparation).

Settings and Design: The present study is an in vitro study with the sample size of 75 participants. A total of 75 human extracted maxillary central incisors were collected and then divided into four experimental groups and one control group (n = 15 each).

Materials and Methods: A total of 75 human extracted maxillary central incisors were collected and then divided into four experimental groups and one control group (n = 15 each). Four tooth preparation techniques were performed followed by direct composite veneering. All the study samples were then splitted into two equal halves. One half of all the samples was subjected to a cell load from 0 N to 100 KN at a crosshead speed of 1 mm at 90° angulation using universal testing machine to evaluate the fractural strength. The other halves were sectioned longitudinally, and the samples were then subjected under the travelling microscope at ×200 magnification to measure the marginal discrepancy at cervical, middle, and incisal locations.

Statistical Analysis: The data obtained were subjected to statistical analysis using SPSS Version 20.0.

Results: The fractural strength showed the maximum strength in Group V: Control group (273.33 ± 81.01), Group III: Bevel preparation (193.80 ± 66.59), Group IV: Incisal overlap preparation (188.93 ± 76.14), Group II: Feather preparation (160.33 ± 53.59), and least in Group I: Window preparation (147.74 ± 48.95). The marginal discrepancy showed maximum discrepancy in Group IV: Incisal overlap preparation (49.11 ± 6.33), Group II: Feather preparation (48.44 ± 6.01), Group III: Bevel preparation (46.67 ± 7.07), and least in Group I: Window preparation (45.33 ± 6.31).

Conclusion: The fractural strength was maximum in Group V, followed by Group III, Group IV, Group II, and the least mean value score was found for the Group I, and the marginal discrepancy was maximum in Group IV, followed by Group II, Group III, and the least mean value score was found for the Group I.