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.

In Vivo Strain Alterations in Mandibular Molars after Root Canal Treatment Procedures.

INTRODUCTION: The aim of this investigation was to determine the coronal strain variations in mandibular molars under an in vivo bite load after root canal treatment procedures. METHODS: The coronal strain in carious mandibular first molars with symptomatic irreversible pulpitis (experimental group) was compared with that of intact contralateral teeth (control group) in patients 20-40 years old. Experiments were conducted in 2 stages. In stage 1, the maximum bite force on the first molar region was determined on the experimental and control teeth using a customized load cell. In stage 2, strain gauges were bonded to the buccal aspect of teeth, and the strain was recorded after the application of a bite load on the intact (control) teeth; and the experimental teeth before and after endodontic access cavity preparation, cleaning/shaping procedures, root filling, and composite core restoration. RESULTS: The mean maximum bite force on the experimental teeth (91 ± 48 N) and the contralateral control teeth (91 ± 49 N) was not significantly different (P = .989). The preoperative strain (microstrain) in the experimental teeth was significantly higher (125 ± 36, P = .001) than in the contralateral intact teeth (46 ± 17). Access cavity preparation significantly increased the strain (327 ± 98, P = .019) on the experimental teeth compared with the preoperative strain. Cleaning/shaping (355 ± 113) and root filling (346 ± 89) did not significantly increase (P = 1.00) the strain compared with the strain determined after endodontic cavity preparation. Composite core restoration in the experimental teeth (106 ± 41) resulted in a significant reduction in the strain compared with the values recorded after an endodontic access cavity (P = .002) and was similar to the preoperative strain values (P = 1.00) but was significantly higher than the strain values in contralateral intact teeth (P = .001). CONCLUSIONS: The coronal strain on the buccal surface of mandibular first molars significantly increased with access cavity preparation, which did not increase further after cleaning/shaping or root filling. A significant reduction in the strain induced by root canal treatment steps was evident after composite core restoration.

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.

The effect of three desensitizing agents on dentin hypersensitivity: A randomized, split-mouth clinical trial.

OBJECTIVES: This randomized clinical trial tested the effect of three different desensitizing agents on reduction of pain due to hypersensitive cervical dentin lesions. MATERIALS AND METHODS: Twenty-eight individuals with 84 teeth diagnosed with cervical dentin hypersensitivity (DH) in at least one tooth in any three of the four quadrants were selected. Patients exhibiting pain scores of two or more on the visual analog scale (VAS) were included in the study. Each quadrant in an individual was randomly assigned to one of the three treatment groups based on computer-generated random number. The desensitizing agents used were Profluorid Varnish (Voco: Cuxhaven Germany), Admira Protect (Voco: Cuxhaven Germany), and PRG-Barrier Coat (Shofu: japan). One operator recorded the baseline sensitivity scores after evaporative and tactile stimuli by visual analog score system. The second operator who was not aware of the baseline values applied the desensitizing agents and recorded the sensitivity scores. VAS scores for both the stimuli were noted immediately after application, 1 week, and after 1 month. The data were analyzed using repeated measure ANOVA and post hoc Tukey's multiple comparison tests (P < 0.05 was considered statistically significant). RESULTS: There was a significant reduction in VAS scores from baseline in all the three groups at all the time intervals (P < 0.001). Admira Protect showed significant reduction of hypersensitivity scores at 1 month compared to other groups (P < 0.001). CONCLUSION: Admira Protect was proved to be better in reducing pain due to DH than PRG-Barrier Coat and Profluorid Varnish after 1 month of application.