Impact of dental operating microscope, selective dentin removal and cone beam computed tomography on detection of second mesiobuccal canal in maxillary molars: A clinical study.

INTRODUCTION: Maxillary molars may frequently require root canal therapy and can have complex anatomy. It is important to locate and treat the second mesiobuccal canal to significantly improve prognosis. AIM OF THE STUDY: The purpose of this study was to evaluate direct vision, dental operating microscope (DOM), selective dentin removal under DOM, and cone beam computed tomography (CBCT) in clinical detection of second mesiobuccal root canal (MB2) in maxillary molars. MATERIALS AND METHODS: A total of 122 maxillary first and second molars indicated for root canal treatment were included in our study. Following access cavity preparation, the presence of MB2 canal orifice was assessed in four stages. Stage I: with direct vision. Stage II: under DOM, Stage III: after selective dentin removal under DOM and Stage IV: teeth in which MB2 canal was not identified by Stage III were further investigated with CBCT. The number of canals identified during each stage was analyzed statistically. RESULTS: Clinical detection of MB2 canal in our study was 90%, with 93% in maxillary first molar and 86% in maxillary second molar. 64% MB2 canals were located at Stage I (direct vision) which improved to 84% at Stage II (under DOM) and 90% at Stage III (selective dentin removal under DOM). CBCT investigation (Stage IV) further improved the identification of MB2 canal leading to overall prevalence of 93%. CONCLUSION: The results of our study demonstrated that MB2 canal can be clinically detected in up to 90% of maxillary molars by the use of DOM and selective dentin removal. CBCT investigation is indicated when MB2 canals are not clinically detected.

Evaluation of Surface Roughness, Hardness, and Gloss of Composites After Three Different Finishing and Polishing Techniques: An In Vitro Study.

Introduction The purpose of this in vitro study was to evaluate the effect of three different polishing systems on the microhardness, surface roughness, and gloss of resin composites. Materials and Methods The materials evaluated were 3M™ ESPE™ Filtek™ Z-350 XT (3M™, St. Paul, MN, USA), Grandio (Voco, Cuxhaven, Germany), 3M™ ESPE™ Filtek™ Z250 (3M™, St. Paul, MN, USA), Shofu-Beautifil Flow (Shofu, Kyoto, Japan), and RestoFill HV N-FLO (Anabond Stedman, Chennai, India). A total of 450 samples were fabricated. Three finishing and polishing systems: PoGo® (Dentsply Caulk, Milford, DE, USA), Sof-Lex Spiral, and Sof-Lex Pop-On (3M™, St Paul, MN, USA) were evaluated. Hardness, roughness, and gloss were evaluated after finishing and polishing. The surface roughness was measured with a surface profilometer, microhardness was measured with the Struers Duramin-5 microhardness tester (Struers A/S, Ballerup, Denmark) and gloss was measured using a gloss meter. The measurement values were analysed by Kolmogorov-Smirnov, Shapiro-Wilks test, and two-way ANOVA. Results The Sof-Lex Spiral group exhibited higher mean microhardness (p < 0.001), less surface roughness (p < 0.001), and higher gloss (p < 0.001). Filtek Z-250 exhibited higher mean microhardness (p < 0.001) than Grandio (p < 0.001) and Shofu Beautifil Flow (p < 0.001), and Filtek Z-350 XT exhibited more microhardness than Shofu Beautifil Flow (p < 0.001). Filtek Z-350 XT exhibited lower mean surface roughness than Filtek Z-250 (p < 0.05). Filtek Z-250 polished with Sof-Lex Spiral proved to have higher gloss (34.89 gloss units (GU)) than Grandio and RestoFill HV N-FLO (p < 0.05). Conclusions Hardest, smoothest, and glossiest surfaces were obtained with the Sof-Lex Spiral finishing/polishing system. The mean microhardness of Filtek Z-250 and Filtek Z-350 XT was found to be higher than other composites used in this study. Filtek Z-350 showed a lower mean surface roughness and Filtek Z-250 exhibited a higher mean gloss.

Remineralization ability of sodium fluoride on the microhardness of enamel, dentin, and dentinoenamel junction: An in vitro study.

AIM: Dental tissues such as enamel, dentinoenamel junction (DEJ), dentin, and root dentin can react differently to demineralization and remineralization. The aim of this study was to evaluate the remineralization ability of sodium fluoride on the microhardness of enamel, dentin, and dentinoenamel junction. MATERIALS AND METHODS: Ten extracted third molar teeth were sectioned mesiodistally to form control and test groups. For the test group, initial demineralization was done with acetic acid for 24 h followed by remineralization for 28 days by application of sodium fluoride (226 ppm) for 2 min twice a day. Vickers microhardness test was done to control and test groups at different sites after initial demineralization and on the 3rd, 5th, 7th, 14th, and 28th day of remineralization. STATISTICAL ANALYSIS USED: Data were analyzed with one-way analysis of variance and post hoc test with a significance level of P < 0.001 with SPSS (21) software. RESULTS: Microhardness values in the demineralization group were significantly lower than controls (P < 0.001). Evaluation of remineralization samples showed that microhardness similar to control values were achieved at the 3rd day in root predentin and on the 5th day in coronal dentin and coronal predentin. On the 7th day, remineralization coronal predentin was significantly higher than the control (P < 0.001). On the 14th day, DEJ axial zone and root dentin were similar to control and coronal dentin was significantly higher than the control (P < 0.001). Enamel was similar to control on the 28th day. Microhardness of DEJ-cusp tip and DEJ-center of the fissure was significantly lower than control even at the 28th day (P < 0.001). CONCLUSION: Long-term repeated application of sodium fluoride (226 ppm) can improve the microhardness of demineralized dental tissues on enamel, dentin, and DEJ-axial zone, except in the DEJ-cusp tip and DEJ-center of fissure.