Assessment of Mesiobuccal Canals in Endodontically Treated Teeth in Indore Population by Cone Beam Computed Tomography: A Cross-Sectional Study.

BACKGROUND: Owing to the complicated anatomical nature of maxillary molars, untreated root canals may directly affect the outcome of root canal therapy. Therefore, cone beam computed tomography (CBCT) scan is an important tool in the evaluation of root canal systems, particularly for the detection of the second mesiobuccal (MB2) canal in maxillary molars. AIMS AND OBJECTIVES: The current study was undertaken to detect and evaluate filled/unfilled MB2 canals in endodontically treated, asymptomatic maxillary molars, and its correlation with periapical pathology by utilizing cone beam computed tomography (CBCT). MATERIAL AND METHOD: A retrospective study of 80 CBCTs of patients underwent scanning for various treatment modalities, with asymptomatic endodontically treated permanent maxillary first molars selected. Data collection occurred between January and June 2023. CBCT machine used was KODAK 9000 (Rochester, NY: Carestream Health) (Complementary Metal Oxide Semiconductor {CMOS} sensor, continuous mode and 12-28 sec scan time, 90-500 µm voxel size, and 5x3.5 cm field of view {FOV}). The axial images at mid-root level were used to assess the presence of the MB2 canal. RESULT: The study included 39 (48.8%) right maxillary first molars and 41 (51.3%) left maxillary first molars. Overall, in 62 (77.5%) maxillary first molars, MB2 was missed by the practicing dentist, and in 13 (16.3%) maxillary first molars MB2 canal was not present. Of all the maxillary first molars with MB2 canal (n=67), 53 (79.1%) canals had a periapical infection, five (7.5%) showed widening of periodontal ligament space whereas nine (13.4%) had no abnormality. CONCLUSION: MB2 canals were present in the majority of cases and most of the unfilled MB2 canals showed evidence of periapical radiolucencies and showed a direct impact on the prognosis.

Comparative evaluation of canal transportation and canal centering ability in oval canals with newer nickel-titanium rotary single file systems - A cone-beam computed tomography study.

Context: The purpose of this study was to evaluate and compare the centering ability and canal transportation of TruNatomy, OneCurve, and Jizai file systems to assess their performance in oval-shaped canals using cone-beam computed tomography imaging. Materials and Methods: Forty-two fully formed single-rooted mandibular premolars were selected with a buccolingual canal size 2-2.5 times the mesiodistal size at 5 mm from the apex, with 0°-10° canal curvature with a 5-6 mm radius, at 5 mm from the apex. The teeth were divided into three groups (n = 14) and prepared with TruNatomy, OneCurve, and Jizai files based on the manufacturer's instructions. Cone-beam computed tomographic images were taken before and after instrumentation. The canal transportation and centering ability was calculated at 3, 6, and 9 mm from the apex in both mesiodistal and buccolingual directions. Statistical Analysis: Intergroup comparison was done using Kolmogorov-Smirnov test. Intragroup comparison was done using Freidman test. A comparison of categorical variables was done using the Chi-square test. Results: The results obtained did not present any statistically significant difference between the three groups, with TruNatomy and OneCurve showing relatively lesser canal transportation and better centering ratio when compared to the Jizai file system. Conclusions: It can, therefore, be concluded that all three systems used in the study are capable of safely preparing root canals with minimal errors.

Evaluating the Effect of Different Intra-Orifice Barriers and Various Bleaching Agents on the Fracture Resistance of Teeth After the Walking Bleach Procedure: An In Vitro Study.

Objective This study aimed to evaluate the effect of three different commercially available intra-orifice barriers and bleaching agents on root canal-treated teeth. Materials and methods Forty-five freshly extracted single-rooted incisors, canine, and premolars were collected and stored in 10% formalin. Root canal procedures were performed on the extracted teeth and these were classified into three groups and three subgroups (n=5). Group 1: resin-modified glass ionomer cement (RMGIC); placed at the level of cemento-enamel junction (CEJ) and cured for 20 seconds. Group 2: BiodentinTM (Septodont Ltd., Saint Maur des Fausse´s, France); powder and liquid were mixed according to the manufacturer's instructions and placed at the level of CEJ, and waited for 15 minutes to set. Group 3: bulk-fill composite; placed at the level of CEJ. Group A was treated with 35% carbamide peroxide (Ultradent Opalescence 35% PF regular). Group B was bleached with 35% hydrogen peroxide (Pola Office). Group C, which was the control group, was treated with distilled water. The bleaching procedure was repeated once every seven days for a period of three weeks. After bleaching, every sample was sectioned 2 mm above the level of CEJ to remove the crown. Auniversal testing machine (UTM) was used for the evaluation of the fracture resistance of teeth. Data were analyzed for significance by using analysis of variance (ANOVA) and further pair-wise comparison was performed by pos-hoc analysis. The level of significance was set at p<0.05 Results There was a significant difference between the fracture resistance of the three materials when bleached using distilled water (p<0.05). The fracture resistance of Group 3 was significantly greater than that of Group 2 and Group 1 (p<0.05). The difference in the fracture resistance between Group 1 and Group 2 was nonsignificant (p>0.05). Conclusion Walking bleach performed via bleaching agents 35% carbamide peroxide and 35% hydrogen peroxide leads to a reduction in the fracture resistance of endodontically treated teeth; 35% hydrogen peroxide causes more fracture resistance reduction than carbamide peroxide of the same concentration. The presence of intra-orifice barriers leads to greater fracture resistance and reinforcement of endodontically treated teeth that undergo the walking bleach procedure. Bulk-fill composite can be used as an intra-orifice barrier with good fracture resistance.

A comparative evaluation of accuracy of three electronic apex locators using histological section as gold standard: An ex vivo study.

INTRODUCTION: The aim of the present study was to comparatively evaluate the accuracy of iRoot, iPex II, and Propex pixi apex locator using histological sections as the gold standard. MATERIALS AND METHODS: Thirty patients indicated for extraction of single-rooted permanent teeth with single canal system were selected. Working lengths (WLs) of teeth were determined using iRoot, iPex II, and Propex pixi. Teeth were then extracted, and the files were reintroduced to the anatomic apex to measure anatomic canal length (ACL) and fixed at the ACL using flowable composite. The apical 4 mm of the roots were longitudinally shaved away to visualize the canal under a stereomicroscope at ×24 magnification. Digital photographs were evaluated to measure the distance between the major diameter and minor diameter. Thus, the WL, that is, the minor diameter length (MDL) was ascertained. RESULTS: Measurements of mean WLs within ±0.5 mm of minor diameter were 90% acceptable for iRoot, 86.66% for iPex II, and 80% for Propex pixi when compared with mean MDL as obtained from the histological sections. CONCLUSIONS: All apex locators have been shown to produce acceptable level of accuracy which clearly indicates their reliability in determining the WL.

Perception of Acceptable Range of Smiles by Specialists, General Dentists and Lay Persons and Evaluation of Different Aesthetic Paradigms.

INTRODUCTION: One of the most important goals of restorative dentistry is to restore the patient's aesthetic. Smile analysis is subjective and it differs from person to person. An aesthetic smile involves a harmonious relationship between various parameters including the hard and soft tissues. AIM: The aim of the study was to identify the acceptable range of several smiles (alone and in conjunction with the face) by specialists, general dentists as well as lay persons; and to identify the values of different criteria i.e., the Golden Proportion (GP), the Recurrent Esthetic Dental proportion (RED), Width to Height ratio (W/H ratio), the Apparent Contact Dimension (ACD), and lateral incisor position in a smile. MATERIALS AND METHODS: Hundred photographs of 50 subjects were taken, 50 of the smile alone and 50 of the individual's frontal view of face. The photographs of the smiles and the faces were assessed for the aesthetic acceptability by 30 evaluators including 10 specialists with advanced training, 10 general dentists and 10 lay persons. Irreversible hydrocolloid impressions were made of the dentitions of all the individuals using stock trays and were poured in dental stone. Measurements were made on the facial surface of the teeth on the models and were recorded in millimeters using a sharp tipped digital vernier calliper. Data was analyzed to evaluate the presence of different parameters assessed in the smiles. Mean and standard deviation values for the percentage of only the agreeable smiles were calculated in both individual smile analysis and in conjunction with the face. The non agreeable smiles were excluded from further statistical analysis. Pearson Correlation Coefficient was calculated to compare the values obtained in all the three groups. RESULTS: More number of smiles were considered agreeable by the general dentists when compared to the specialists and the number even increased in case of evaluation by lay persons. Greater number of smiles was found to be agreeable when they were evaluated in conjunction with the face. CONCLUSION: Rather than assessment of individual numeric parameter that defines an ideal aesthetic smile, a smile to be aesthetic should harmonize with the composition of the face.

Evaluation of the incidence of microcracks caused by Mtwo and ProTaper Next rotary file systems versus the self-adjusting file: A scanning electron microscopic study.

INTRODUCTION: To evaluate the incidence of microcrack formation canal preparation with two rotary nickel-titanium systems Mtwo and ProTaper Next along with the self-adjusting file system. MATERIALS AND METHODS: One hundred and twenty mandibular premolar teeth were selected. Standardized access cavities were prepared and the canals were manually prepared up to size 20 after coronal preflaring. The teeth were divided into three experimental groups and one control group (n = 30). Group 1: The canals were prepared using Mtwo rotary files. Group 2: The canals were prepared with ProTaper Next files. Group 3: The canals were prepared with self-adjusting files. Group 4: The canals were unprepared and used as a control. The roots were sectioned horizontally 3, 6, and 9 mm from the apex and examined under a scanning electron microscope to check for the presence of microcracks. The Pearson's Chi-square test was applied. RESULTS: The highest incidence of microcracks were associated with the ProTaper Next group, 80% (P = 0.00), followed by the Mtwo group, 70% (P = 0.000), and the least number of microcracks was noted in the self-adjusting file group, 10% (P = 0.068). No significant difference was found between the ProTaper Next and Mtwo groups (P = 0.368) while a significant difference was observed between the ProTaper Next and self-adjusting file groups (P = 0.000) as well as the Mtwo and self-adjusting file groups (P = 0.000). CONCLUSION: All nickel-titanium rotary instrument systems were associated with microcracks. However, the self-adjusting file system had significantly fewer microcracks when compared with the Mtwo and ProTaper Next.