Suman Yadav

The effect of ferrule presence and type of dowel on fracture resistance of endodontically treated teeth restored with metal-ceramic crowns

Aim: The purpose of the present study was to comparatively evaluate the effect of presence of a 2 mm ferrule and different type of dowels on fracture resistance of mandibular premolars. Materials and Methods: Fifty uniradicular mandibular premolars were divided into five groups (n = 10). Ten teeth received no treatment (group I). Samples in group II & III were decoronated 2 mm above cemento-enamel junction and received custom cast dowel-core and fiber dowel-composite core respectively, with 2 mm ferrule. Samples in group IV & V were decoronated at CEJ and were restored using cast dowels and fiber dowel-composite cores, without any ferrule. The restored teeth received metal ceramic crowns and were mechanically loaded. The specimens were subjected to a static load, until fracture, to determine the fracture resistance and fracture mode. Results: The samples with 2 mm ferrule had a higher fracture resistance than non ferrule groups. Within non ferrule groups, there were no significant differences in the fracture resistance. Specimen restored with cast dowel had more incidence of non-repairable fracture. Conclusions: Presence of ferrule increased the fracture resistance of endodontically treated teeth. In case of absence of ferrule, fiber dowels had similar fracture resistance as that of cast dowels and showed increased incidence of repairable fracture.

Ionizing irradiation affects the microtensile resin dentin bond strength under simulated clinical conditions.

Objectives: This study evaluated the effect of ionizing radiations on resin–dentin interface in terms of marginal adaptation and micro-tensile bond strength under thermocycling and mechanical loading. Materials and Methods: Forty extracted human mandibular third molars were divided into four groups. GR I: No Irradiation and Class II MO cavities were prepared that were restored with composite restorations; GR II: Teeth were irradiated and restored; GR III: Teeth were restored and irradiated; GR IV: Teeth were restored during irradiation dosage fractions. All samples were thermal and mechanical loaded with 5000 cycles, 5 ± 2-55 ± 2°C, dwell time 30 s and 150,000 cycles at 60N. Resin–dentin slabs were trimmed into dumbbell-shaped slabs and microtensile bond strength was measured. The bond strength data was analyzed by one-way analysis of variance test. Results and Conclusions: Irradiation before tooth preparation deteriorated the microtensile bond strength.