A SEM Evaluation of the Permeability of Different Desensitizing Methods on Occlusion of Dentinal Tubules: An In-vitro Study.

AIM: The purpose of the current research was to assess the permeability of three various desensitizing techniques on dentinal tubule occlusion using a scanning electron microscope (SEM). MATERIALS AND METHODS: For this research, 100 human sound premolar teeth that were extracted for orthodontic purposes were gathered. With the aid of a water-cooled diamond saw, the teeth were divided in a mesiodistal (vertically) orientation. A sectioned sample (5 mm long by 5 mm wide by 3.5 mm deep), including the cervical region, was taken from each buccal side. To fully open the dentinal tubules, these samples were then kept in 17% ethylenediaminetetraacetic acid (EDTA) for 40 minutes. The samples were divided into four groups (n = 25), each receiving the following dentin surface treatments: Group I: Control, Group II: Samples received NaF 5% varnish treatment, Group III: Samples received diode laser treatment, and Group IV: Samples received CPP-ACP treatment. An SEM was used to inspect each specimen at a magnification of about × 3000 and photomicrographs was assessed. RESULTS: The maximum occlusion of dentinal tubules was found in samples were treated with Diode laser (2.96 ± 0.14) followed by samples treated with NaF 5% varnish (3.38 ± 0.10), samples were treated with CPP-ACP (3.42 ± 0.06) and control group (4.26 ± 0.19). There was a statistically significant difference found between the groups. CONCLUSION: In conclusion, all three desensitizing methods used in the present study were successful in the occlusion of dentin tubules. But the application of the Diode laser was effective in the reduction of dentin permeability compared to NaF 5% varnish and CPP-ACP. CLINICAL SIGNIFICANCE: Dentin hypersensitivity (DH) is characterized by a brief period of intense discomfort. One approach to managing DH is to obstruct dentin tubules in order to decrease dentin permeability. There are many substances that can reduce hypersensitivity, but the finest commercially available substance for treating the condition by occluding the tubes should be acknowledged.

Evaluation of Radicular Dentin Microcracks Formation after Instrumentation with NiTi Hand and Rotary File System: A Stereomicroscopic Study.

AIM AND OBJECTIVE: The present study aimed to assess the formation of microcracks in root dentin post-instrumentation with nickel-titanium (NiTi) hand and rotary file system. MATERIALS AND METHODS: Totally, 80 freshly extracted mandibular premolar teeth with single roots were chosen for this study. Access opening was performed and #10 K-file was used to attain patency of canal. All specimens were divided into four groups (each group having 20 specimens), i.e., Group I: Unprepared, Group II: NiTi hand K-files, Group III: Self-adjusting file, and Group IV: XP-Shaper single file. Complete irrigation of all the canals was performed after instrumentation. All roots were cut horizontally at three levels [apical third (3 mm), middle third (6 mm), and cervical third (9 mm)] from the apex with diamond disc. A stereomicroscope was used to view the sections under 20× magnification. RESULTS: Self-adjusting file showed least number of defects with a percentage of 75% followed by XP-Shaper and NiTi hand K-files with a values of 65 and 60%, respectively. Use of hand K-files resulted in greater number of incomplete cracks (30%) and use of XP-Shaper demonstrated greater number of craze lines (15%). A statistically significant difference was found between the experimental groups in the formation of dentinal defects of root at apical third (3 mm) (p < 0.031) and middle third (6 mm) (p < 0.001), whereas the sections at cervical third (9 mm) did not show any statistically significant difference (p > 0.312). CONCLUSION: The present study concluded that the self-adjusting file system gives promising better results in cleaning ability with minimal incidence of radicular dentin microcracks than XP-Shaper and NiTi hand K-files system. CLINICAL SIGNIFICANCE: The root dentin may unavoidably get damaged during instrumentation resulting in the formation of dentinal cracks and tiny complicated fractures, thus leading to endodontic failures. Various factors cause dentinal cracks, but the flexibility of file due to heat treatment, kinematics of the file, and the basic architecture of the file are the most significant ones. Self-adjusting file system represented satisfactory results with minimal microcracks defects.

Electrochemical dissolution and retrieval of broken NiTi endodontic files from root canal using chloride based isotonic fluids as electrolytes - An in vitro study.

Objective: The electrochemical dissolution method of instrument retrieval emphasizes on the dissolution of the instrument rather than sacrificing dentine. Most of the studies conducted for electrochemical dissolution used fluoride-containing electrolytes and were performed inside a beaker. In this study, we used chloride-based fluids as electrolytes. Materials and Methods: Fifty extracted mandibular first premolars were divided into five groups based on the electrolytes used. Canals were enlarged to ProTaper Universal F2, and files were intentionally broken inside the canal. These specimens were subjected to electrochemical characterization by applying the potential of 9V for 20 min. Optical images were taken to assess the change in surface topography. The results were analyzed statistically by one-way analysis of variance (analysis of variance [ANOVA]). Results: The rate of dissolution based on the electrolyte used decreased in the following order, viz. Tyrode's solution>artificial saliva>normal saline>Ringer's lactate/physiological serum. Conclusion: Apart from fluoride, chloride-based electrolytes could be an efficient alternative.

The Effects of Various Final Irrigants on the Bond Strength of Root Dentin Exposed to Chloroform: An In vitro Study.

AIM: The aim of the study was to assess the reaction of different final irrigants to the bond strength of root dentin exposed to chloroform. MATERIALS AND METHODS: Fifty extracted maxillary central incisors were selected. Working length was determined, and canal was instrumented with ProTaper rotary system (Dentsply Maillefer) till F4 file. The specimens were then divided into five groups (n = 10). Group 1: not disclosed to any root canal solvent, Group 2: disclosed to chloroform for 5 min, Group 3: chloroform for 5 min followed by absolute alcohol, Group 4: chloroform for 5 min followed by chlorhexidine (CHX), And Group 5 - chloroform for 5 min followed by saline. The canals were obturated with F4 gutta-percha cones with AH Plus sealer. The samples will be sectioned horizontally into 1 ± 0.1 mm thick slices. The push-out bond strength was performed in a universal testing machine. Results were statistically analyzed by one-way analysis of variance. RESULTS: There existed a significant difference between the mean push-out bond strength of different groups. Irrigation with chloroform negatively affected the bonding between root canal sealer and root dentine. Absolute alcohol significantly improved the bond strength values. CONCLUSION: Exposure with chloroform during the retreatment will decrease the bonding between sealer (AH Plus) and root dentine. The use of absolute alcohol as a final irrigant improved the bonding between sealer and dentin. CHX and saline showed no improvement in bond strength.