ABSTRACT
INTRODUCTION: In cases of severe hard tissue loss, 2 mm circumferential ferrule is difficult to achieve which leads to incorporation of different ferrule designs. AIM: To compare and evaluate the effect of different crown ferrule designs on the fracture resistance of mandibular premolars restored with fiber posts, composite cores, and crowns. MATERIALS AND METHODS: Fifty freshly extracted mandibular premolars were endodontically treated and divided into five groups: Group I - 2 mm circumferential ferrule above the cementoenamel junction (CEJ); Group II - 2 mm ferrule on the facial aspect above CEJ; Group III - 2 mm ferrule on the lingual aspect above CEJ; Group IV - 2 mm ferrule on the facial and lingual aspects above CEJ with interproximal concavities, and Group V - no ferrule (control group) and were later restored with fiber posts, composite cores, and crowns. Specimens were mounted on a universal testing machine, and compressive load was applied at a crosshead speed of 1 mm/min until fracture occurred. RESULTS: The results showed that circumferential ferrule produced the highest mean fracture resistance and the least fracture resistance was found in the control group. CONCLUSION: Circumferential ferrule increases the fracture resistance of endodontically treated teeth restored with bonded post, core, and crown.
ABSTRACT
OBJECTIVE: Analysis of shaping ability of four different rotary endodontic instruments using spiral computed tomography (CT). MATERIALS AND METHODS: Eighty freshly extracted human mandibular first molars were used in the present study. Samples were randomly divided into four experimental groups with twenty samples in each group. Images of mesiobuccal canal of each sample were obtained pre- and post-operatively using spiral CT. All samples were prepared using their respective endodontic file systems (group I - ProTaper, group II - K3, group III - RaCe, and group IV - Mtwo). Image analyses were done using image analysis software for evaluation of canal transportation and centering ability. Data was then statistically analyzed using analysis of variance. RESULTS: There was no statistically significance in transportation in their intergroup difference at any of the three locations (coronal, middle, and apical third). In centering ability there was no statistically significance in the coronal and middle third of the intergroup. However, there was a statistically significance of (P = 0.044) at the apical third between all the groups. CONCLUSION: Canals prepared with ProTaper had more canal transportation at all the three levels of root canal (coronal, middle, and apical third). Canals prepared with Mtwo were well centered at coronal and middle third whereas with RaCe canals were centered only at the apical third. All instruments showed some degree of canal aberrations in terms of shaping ability.
ABSTRACT
AIM: The purpose of this in vitro investigation was to evaluate the influence of hydrophobic layer and delay in placement of composite on marginal adaptation of two self-etch adhesive systems (XENO-III and ALL-BOND SE). MATERIALS AND METHODS: Eighty class V cavities were prepared on intact, extracted human premolars and were divided into 4 groups of 10 teeth each. Group 1: Application of bonding agents as per manufacturer directions and immediate placement of composite; Group 2: Application of bonding agent and composite similar to group1, with hydrophobic layer curing before composite placement; Group 3: Application of bonding agent similar to group 1, with 2 min delay in composite placement; and Group 4: Application similar to group 2 with 2-min delay in composite placement. The specimens were restored and light cured. After thermocycling and immersion in 2% basic Fuchsin dye solution, the teeth were sectioned and dye penetration was observed under a stereomicroscope at 20x magnification. All the samples were scored and results were analyzed using Kruskal-Wallis and Mann-Whitney tests. RESULTS: In group 1, the microleakage along the both enamel and dentin margin was significantly higher than the other groups for both the adhesive systems. There is no significant difference between groups 2, 3 and 4. CONCLUSION: The addition of a more hydrophobic resin layer and delay in composite placement significantly improves the marginal adaptation of self-etch adhesive resin systems.