Aim:To aim of this study is to investigate the root canal characteristics of mandibular incisors in a North East Indian population using a canal staining and tooth-clearing technique.Materials and Methods:Four hundred and eighty extracted mandibular incisors, collected from dental clinics within North East India were selected for this study. Following pulp tissue removal, the teeth were decalcified with 5% nitric acid, dehydrated with ascending concentrations of alcohol and rendered clear by immersion in methyl salicylate. After staining of the canal systems with India ink, cleared teeth were examined under 5X magnification and the following features were evaluated: (i) number and type of root canals; (ii) presence and location of lateral canals and intercanal communications; (iii) location of apical foramina; and, (iv) Bifurcation of canals.Results:The majority of mandibular incisors had a single canal (63.75% of teeth possessed a Type I canal system). Although 36.25% of the roots possessed two canals, only 6.25% had two separate apical foramina.Conclusions:The prevalence of two canals in this group (of North East Indians) of mandibular incisors was 36.25% and is within the range of previous studies performed on populations of different racial origin.

Aim:The in-vitro study compared the shear bond strength (SBS) of three recently introduced dual-cure resin based core build-up materials namely ParaCore, FluoroCore, and MultiCore.Materials and Methods:One hundred twenty extracted permanent human mandibular molar teeth were taken and sectioned horizontally beneath the dentinoenamel junction to expose the coronal dentin. The specimens obtained were divided into three main groups based on the materials used and then further divided into four sub-groups based on time interval with ten samples each. The dentin surface was treated with the respective adhesives of the groups and then bulk filled with core build-up materials. The attained samples were than subjected to shear loading in Instron Universal Testing Machine. The data were tabulated and statistically analyzed using analysis of variance (ANOVA), Tukey's HSD, and Levene's test.Results:The mean SBS was highest in MultiCore at all time periods as compared to FluoroCore and ParaCore and was also higher at 48 h thermocycling in all three groups studied.Conclusion:MultiCore dual-cure resin based core build-up material showed the highest mean SBS as compared to FluoroCore and ParaCore. SBS was not negatively affected by thermocycling.

Objectives:The objective of this study was to evaluate the influence of caries detection dye on the in-vitro tensile bond strength of adhesive materials to sound and carious affected dentin.Materials and Methods:Forty healthy and carious human molars were ground to expose superficial sound dentin and carious affected dentin. Caries Detector dye was applied to sound and carious affected dentin and rinsed. Subsequently the dentin was etched with 37% phosphoric acid and rinsed leaving a moist dentin surface. The adhesive (Single bond) was applied in single layers and light cured. A posterior composite (Filtek Z 250) were used to prepare the bond strength specimens with a 3 mm in diameter bonding area. Control and experimental groups were made with and without application of dye respectively. Each group includes both sound and carious affected dentin. After 24 hour immersion in distilled water, tensile bond strength (MPa) was measured using an Instron testing machine.Results:Analysis of variance (ANOVA) was used to evaluate the data. The tensile bond strength were significantly less in experimental subgroup than control subgroups.Conclusion:The tensile bond strengths were higher in sound and carious affected dentin without application of caries detection dyes.

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Aim:This in-vitro study compared the shear bond strength of a dual-cure core build-up composite bonded to dentin using a twostep self-etch adhesive, with two, single step self-etch universal adhesive systems. Materials and Methods:In the present in-vitro study, sixty extracted permanent human mandibular molar teeth, decoronated below the dentino-enamel junction to expose the coronal dentin, were taken and later mounted in self-cure acrylic resin. The specimens were randomly divided into three groups of twenty samples each, based on the dentin bonding agents used namely ParaBond (a two-step self-etch adhesive) and two one-step universal adhesives i.e. Single Bond Universal and Tetric N-Bond Universal. The dentin surface of samples was treated with the respective adhesives of the groups according to manufacturer's instructions. The bonded surface was bulk filled using ParaCore dual-cure composite. The attained samples were stored in distilled water at 37 0 C for 24hrs and subsequently put through thermocycling (5 0 C to 55 0 C for 500 cycles). The samples were than subjected to shear loading in Instron Universal testing machine. The data were tabulated and statistically analyzed using analysis of variance (ANOVA) and Tukey's HSD test. Results: Tetric N-Bond Universal adhesive showed the highest mean Shear Bond Strength (SBS) of 20.78 MPa, followed by Single Bond Universal 19.07 MPa and ParaBond Adhesive 5.44 MPa. Conclusion: Tetric N-Bond Universal showed the highest mean SBS and a predictable relationship was found between the formulation of dentin adhesive systems and their shear bond strength values. Clinical Significance: The universal adhesives showed high shear bond strength as compared to conventional 2-step self-etch adhesives. High acidic pH of self-etch adhesive affected their bond strength. So for stake of bond stability, a mild self-etch / universal adhesive is recommended for adhesion, because higher the bond strength, higher it can withstand the stress resulting in a successful restoration.