Effect of fiber orientation and placement on fracture resistance of large class II mesio-occluso-distal cavities in maxillary premolars: An in vitro study

BACKGROUND AND AIM: To analyze the outcome of fiber placement and orientation over fracture resistance in wide Class II (Mesio-occluso-distal [MOD]) cavities prepared on maxillary premolars. MATERIALS AND METHODS: After selection of 120 extracted human maxillary premolars, Class II (MOD) cavities were prepared maintaining uniform dimensions and samples were divided into six groups randomly (n = 20 each): Group I, G-aenial posterior; Group II, G-aenial posterior + Horizontal Ribbond placement on gingival and pulpal floor; Group III, G-aenial posterior + Horizontal Ribbond placement only on pulpal floor; Group IV, G-aenial posterior + vertical Ribbond placement on gingival and pulpal floor; Group V, G-aenial posterior + Ribbond chips; Group VI, Ever-X posterior. After restorations and completion of thermocycling process, universal testing machine measured the fracture resistance of all samples. Fracture modes were inspected under stereomicroscope. Analyzation of data was performed using one-way ANOVA and Tukey test at significance levels of P < 0.05. RESULTS: Fiber placement significantly increased fracture resistance. The highest fracture resistance was shown by Group 2 (1288.8 N) followed by Group 3 (976 N), group 4 (942.3 N), Group 5 (876.3 N), and Group 6 (833 N). Group 1 (No Fiber group) showed the least fracture resistance of 588.41 N. Repairable fractures were seen highest with Group 2 (80%) followed by Group 6 (70%) and least in Group 1 (30%). CONCLUSIONS: Horizontal orientation of polyethylene fiber on both pulpal and gingival floor of MOD cavities gives the highest fracture resistance in maxillary premolars and repairable mode of fracture.