Effect of C-factor on Micro-tensile Bond Strength of Bulk fill V/S Micro-hybrid Composite in Class II Restorations - An In-Vitro Study.

Background: High Configuration factor (C-factor) results into increased polymerization shrinkage causing stress at resin-dentin interface leading to failure of the restoration. The purpose of this study was to evaluate the effect of C-factor on micro-tensile bond strength (µTBS) of bulk fill composites in class-II cavities when restored in 4mm of bulk as compared to conventional composite. Methodology: A total of 90 carious, crack free extracted human mandibular permanent molars were selected and randomly divided into 3 groups (n=30). On all samples, class II cavities (3.5X 3.5cm) were made by single operator and divided as Gp1 (2.5mm), Gp2 (4mm), and Gp3 (6mm) on the basis of depth of cavities. Sampling units of 30 in each group were further randomly subdivided into 3 subgroups (n=10 each subgroup), according to the type of composite resin systems to be used for restoration. Experimental Subgroup includes SubGp1 restored with SDR Surefil (Dentsply, caulk, USA) and SubGp2 restored with Sonic fill (kerr, orange, CA, USA), whereas SubGp3 restored with FILTEK Z250 served as control. After storage in water at 37◦C, the teeth were sectioned perpendicular to the restorative tooth interface as 1×1 mm non-trimmed rectangular micro-specimens for micro-tensile bond strength (µTBS) testing. Beams (n=30 max) from each SubGp were fixed to a metal jig and subjected to micro-tensile bond strength testing. The data collected for micro-tensile bond strength (expressed in Mpa) were statistically analysed using one way ANOVA and Tukey's post hoc test. Results: In class II cavities with high C-factor, SDR Surefil showed better µTBS than SonicFill and micro-filled composite when filled in bulk of 4mm, as compared to micro-hybrid composite filled incrementally. Conclusion: There is no effect of high C-factor on µTBS of tooth restored with both SDR Surefil and Sonic Fill in class II cavities as compared to microhybrid composites.

Management of external perforating root resorption by intentional replantation followed by Biodentine restoration.

Resorption of tooth structures can occur as a result of physiological, pathological, and idiopathic factors. Early diagnosis and appropriate treatment can prevent its serious complications. This case report presents surgical endodontic management of a trauma-induced perforating external root resorption, which was diagnosed with the help of cone beam computed tomography. Following root canal treatment, intentional replantation of the tooth was performed so as to expose the opening of the resorption defect to allow for complete debridement and closure. Eighteen months follow-up showed arrest of root resorption, and progressive healing of the defect.

Assessment of dentinal damage during canal preparation using reciprocating and rotary files.

INTRODUCTION: The role of motion kinematics in creating dentinal damage during instrumentation is not very clear. The purpose of this study was to compare the formation of dentinal cracks with instruments working in continuous rotation and reciprocating motion. METHODS: One hundred twenty extracted human mandibular premolars were selected for the study. Thirty teeth served as controls, and the remaining 90 teeth were divided into 3 groups depending on the root canal preparation technique. Group 1 samples were treated with WaveOne primary files (Dentsply Maillefer, Ballaigues, Switzerland), group 2 samples with single F2 ProTaper (Dentsply Maillefer) working in reciprocating motion, and group 3 samples were prepared with sequential ProTaper (Dentsply Maillefer) until F2 working in continuous rotation motion. Roots were then sectioned at 3, 6, and 9 mm from the apex, and the cut surface was observed under a stereomicroscope for the presence of dentinal microcracks. RESULTS: The control group and WaveOne, single F2 ProTaper in reciprocating motion, and continuous ProTaper groups caused cracks in 0%, 15%, 26%, and 53% of samples, respectively. A statistically significant difference was found between 2 reciprocating file groups (WaveOne and single F2 ProTaper in reciprocating motion) and the continuous rotation group (ProTaper) (P < .05). However, no significant difference was found among the 2 reciprocating file groups (P > .05). CONCLUSIONS: Dentinal cracks are produced irrespective of motion kinematics. Within the limits of this study and the current literature, such incidence is less with instruments working in reciprocating motion compared with those working in continuous rotation.