Morphotypes of the apical constriction of maxillary molars: a micro-computed tomographic evaluation.

Objectives: The aim of this study was to evaluate and compare the apical constriction (AC) and apical canal morphology of maxillary first and second molars, using micro-computed tomography (micro-CT). Materials and Methods: The anatomical features of 313 root canals from 41 maxillary first molars and 57 maxillary second molars of patients with known age and sex were evaluated using micro-CT, with a resolution of 26.7 µm. The factors evaluated were the presence or absence of AC, the morphotypes, bucco-lingual dimension, mesio-distal dimension, and the profile (shape) of AC and the apical root canal. The apical root canal dimensions, location of the apical foramen (AF), AC to AF distance, and presence of accessory canals in the apical 5 mm were also assessed. Descriptive and analytical statistics were used for data evaluation. Results: AC was present in all 313 root canals. Patients' age and sex did not significantly impact either AC or the apical canal dimensions. The most common AC morphotype detected was the traditional (single) constriction (52%), followed by the parallel (29%) morphotype. The mean AC dimensions in maxillary first molars were not significantly different from those in maxillary second molars. Sixty percent of AF were located within 0.5 mm from the anatomic apex. Conclusions: The most common morphotype of AC detected was the traditional constriction. Neither patients' age nor sex had a significant impact on the dimensions of the AC or the apical root canal. The majority of AF (60%) were located within 0.5 mm from the anatomic apex.

Diagnosis of Vertical Root Fractures by Cone-beam Computed Tomography in Root-filled Teeth with Confirmation by Direct Visualization: A Systematic Review and Meta-Analysis.

INTRODUCTION: The purpose of this review was to determine the diagnostic accuracy of cone-beam computed tomographic (CBCT) imaging in detecting vertical root fractures (VRFs) in root-filled teeth compared with a reference standard (direct visualization). METHODS: Electronic searches were performed in Medline, Scopus, Cochrane, and gray literature for English language articles until June 2020. Prospective and retrospective clinical studies using CBCT imaging to diagnose VRFs in root-filled teeth were included. Case reports and in vitro studies were excluded. The Quality Assessment of Diagnostic Accuracy Studies 2 tool was used to assess the risk of bias and applicability concerns. Meta-analysis was performed using Stata 16.1 software (StataCorp, College Station, TX) via the MIDAS v.3.0 package and METANDI module. Publication bias was evaluated using Deeks' funnel plot analysis. Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) was performed to evaluate the certainty of evidence. This systematic review was registered in the Open Science Framework (10.17605/OSF.IO/7JKE2). RESULTS: Eight articles were included in this systematic review and meta-analysis. Risk of bias assessment showed that 5 articles in the patient selection domain had low risk of bias with low applicability concern. In the index test and reference standard domains, 7 articles had moderate risk of bias with moderate applicability concern. Three articles had high RB in the flow and timing domain. There was no publication bias. CBCT imaging had a pooled sensitivity and specificity of 0.78 (95% confidence interval [CI], 0.64-0.88) and 0.80 (95% CI, 0.63-0.91), respectively, and an accuracy of 0.86 (95% CI, 0.83-0.89). CBCT imaging also had pooled positive and negative likelihood ratios of 4 and 0.2, respectively. In GRADE analysis, the quality of evidence was low for sensitivity and moderate for specificity when CBCT imaging was used for the diagnosis of VRF. CONCLUSIONS: The overall quality assessment of the included articles showed that in the patient selection domain, the risk of bias was low, and it was moderate in the index test and reference standard domains. Evidence from this systematic review and meta-analysis indicates that CBCT imaging is still not a good tool for diagnosing VRFs in root-filled teeth compared with direct visualization.

The time taken for retrieval of separated instrument and the change in root canal volume after two different techniques using CBCT: An in-vitro study.

Introduction: Retrieval of separated instrument from a root canal may lead to increased dentin loss and prolonged treatment time. Aim: The aim of this study was to evaluate the retrieval time and increase in root canal volume after instrument retrieval with two retrieval techniques under dental operating microscope. Materials and Methods: Forty extracted human mandibular molars with 30°-40° mesiobuccal root canal curvature were selected based on cone-beam computed tomography (CBCT) and divided into two groups (n = 20 each). Group 1: Terauchi group (Terauchi ultrasonic tips) and Group 2: Satelec group (Satelec ET25 ultrasonic tip) based on the retrieval technique. Groups 1 and 2 were further divided into two subgroups (n = 10 each) based on the size of the separated instrument; Groups 1a and 2a with ProTaper Gold (PTG) F1 and Groups 1b and 2b with PTG F2. The time taken for retrieval was calculated and increase in root canal volume was evaluated using CBCT. Results were statistically analysed with paired t-test and post hoc analysis by Tukey's HSD test. Results: All separated instruments were successfully retrieved. The mean time for instrument retrieval was lower in Terauchi group than in the Satelec group (P > 0.05) but not significantly. The mean increase in total root canal volume post-retrieval as well as the mean volume corresponding to the coronal part of the separated instrument was significantly lower in Terauchi group than in Satelec group (P < 0.05). Conclusion: Terauchi ultrasonic instruments resulted in reduced instrument retrieval time with lower loss of root dentin.

Dentinal defects before and after rotary root canal instrumentation with three different obturation techniques and two obturating materials.

AIM: To evaluate the role of rotary root canal instrumentation followed by obturation with three different techniques and two different materials on the incidence of dentinal defects. MATERIALS AND METHODS: One hundred and sixty mandibular premolars were divided into eight groups (n = 20). Group I was left untreated and served as control. The other seven groups were prepared with profile rotary instruments till #40.06 taper. After preparation, group II was left unfilled, groups III, IV, and V were obturated with Gutta-percha and AH Plus sealer using passive technique, lateral compaction and warm vertical compaction, respectively. Groups VI, VII, and VIII were obturated with Resilon and Realseal sealer using passive technique, lateral compaction, and warm vertical compaction, respectively. Roots were then sectioned at 3, 6, and 9 mm from the apex and inspected under a stereomicroscope (50×) for dentinal defects. Chi-square test was performed to compare the incidence of dentinal defects between the groups (P < 0.05). RESULTS: The unprepared control group had no dentinal defects. The instrumentation group (group II) and the obturation group (groups III-VIII) showed significantly more defects than the uninstrumented control group (group I) (P < 0.001). There was no significant difference between the root canal obturating techniques (group III-VIII) when compared with the instrumentation group (group II). On inter group comparison among the obturation groups the number of defects after lateral compaction with Gutta-percha (group IV) was significantly larger than passive Gutta-percha obturation (group III) (P < 0.05). CONCLUSIONS: The results suggest that root canal instrumentation significantly influenced the incidence of dentinal defects or fracture. Dentinal defects were more significantly attributed to the role of root canal instrumentation rather than the type of obturation technique or material. Lateral compaction with Gutta-percha significantly produces more defects than passive Gutta-percha obturation.