Roots Of Mandibular First Molars Research Articles

Comparative analysis of methods for measuring root canal curvature based on periapical radiography: A laboratory study.

To evaluate the agreement between six currently available periapical radiography-based methods for measuring the root canal curvatures in mesial roots of mandibular first molars, assessed by two examiners with different proficiency levels. Non-endodontically treated mesial roots of 41 human mandibular first molars were radiographed using the parallelling technique. Two independent observers (a specialist in endodontics and radiology and a final-year dental student) assessed their root canal curvature using the methodologies described by Schneider (1971, Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology, 32, 271), Weine (1982, Endodontic therapy), Berbert and Nishiyama (1994, Revista Gaúcha de Odontología, 356), Luiten etal. (1995, Journal of Endodontics, 21, 26), Hankins and ElDeeb (1996, Journal of Endodontics, 22, 123) and Pettiette etal. (1999, Journal of Endodontics, 25, 230). Intra- and inter-examiner reliability was assessed using the intraclass correlation coefficient. The differences in curvature angle measured by the different methods were compared using the one-way anova for repeated measures test, followed by Tukey's post hoc analysis. The effect was calculated using the Cohen's d method. To determine the agreement between methods, the Bland-Altman analysis was used. The significance level was set at 5%. Agreement for the observers was excellent (>0.81) for the six methods considered. For the angle comparisons between methods, the maximum differences were for Schneider versus Weine (35.77°) and Luiten versus Hankins (35.14°), whilst the highest percentage of angles with a difference >10° were Weine versus Luiten and Berbert versus Pettiette (90%) and the comparison Weine versus Hankins presented with the lowest frequency (15%). Excellent agreement was found for five comparisons: Weine versus Luiten (0.940), Berbert versus Pettiette (0.917), Weine versus Pettiette (0.907), Luiten versus Pettiette (0.904) and Berbert versus Luiten (0.812). Compared to Schneider's method, the other methods showed a tendency of increasing difference as the angles became more acute. The other methods exhibited linear differences, remaining constant for smaller and larger angles. Reliability was excellent for all methods assessed separately. Maximum differences in curvature angles were found when comparing Schneider versus Weine and Luiten versus Hankins. Excellent agreement was found for Weine versus Luiten, Berbert versus Pettiette, Weine versus Pettiette, Luiten versus Pettiette and Berbert versus Luiten. In the presence of dilacerations, the method by Schneider was less sensitive.

Cleaning and disinfection of the root canal system provided by four active supplementary irrigation methods

This in vitro study evaluated the bacterial reduction provided by the EndoActivator (EA), Easy Clean (EC), passive ultrasonic irrigation (PUI), and XP-Endo Finisher. Eight-four mesial roots of mandibular first molars were instrumented, inoculated with Enterococcus faecalis, and divided into four groups (n. 20). Bacterial reduction in the main canals and dentinal tubules were respectively determined by MTT assays and Live/Dead BackLight technique through confocal laser scanning microscopy (CLSM) at 50, 100, and 150 µm in-depth (n. 10 per group). Statistical analyses were conducted following a significance level of 95% (P < 0.05). A significant statistical difference was just identified between XPF and EC in the main canals. In the dentinal tubules from the main root canals, at 100 and 150 µm in-depths, significant statistical differences were only observed between XPF and EC (P = 0.027) for the former and between XPF and EC (P = 0.011) and XPF and PUI (P = 0.021) for the latter. In the dentinal tubules from the isthmus, at 100 µm in-depth, statistically relevant differences did occur between XPF and EC (P = 0.038) and EC and EA (P = 0.029). At 150 µm in-depth, these differences were only significant by comparing XPF and PUI (P = 0.025) and XPF and EC (P = 0.036). Although no irrigation method could thoroughly disinfect the RCS, bacterial reduction indexes were generally better after using XPF.

Predictor factors of 1-rooted mandibular second molars on complicated root and canal anatomies of other mandibular teeth.

This study aimed to determine the effects of 1-rooted mandibular second molar (MnSM) teeth on root canal anatomy complexities of the mandibular central incisor (MnCI), mandibular lateral incisor (MnLI), mandibular canine (MnCn), mandibular first premolar (MnFP), mandibular second premolar (MnSP), and mandibular first molar (MnFM) teeth. Cone-beam computed tomography images of 600 patients with full lower dentition were examined. Individuals with 1-rooted MnSMs were determined, and the complexity of root canal anatomy of other teeth was compared with individuals without 1-rooted MnSMs (Group-1; subjects with at least one 1-rooted MnSM, Group-2; subjects with more than a single root in both MnSMs). A second canal in MnCIs, MnLIs, MnCns, MnFPs, and MnSPs indicated a complicated root canal. The presence of a third root in MnFMs was recorded as complicated. The prevalence of 1-rooted MnSMs was 12.2%, with the C-shaped root type being the most prevalent (9%). There were fewer complicated root canals in MnCIs (p = 0.02), MnLIs (p < 0.001), and MnFPs (p < 0.001) in Group 1. The other teeth showed no difference between the groups (p > 0.05). According to logistic regression analysis, 1-rooted right MnSMs had a negative effect on having complex canal systems of MnLIs and MnFPs. Left MnSMs were explanatory variables on left MnLIs and both MnFPs. In individuals with single-rooted MnSMs, a less complicated root canal system was observed in all teeth except the MnFMs.

Evaluation of the Canal Transportation by OneShape and Neolix Rotary Systems in the Mesial Root of Mandibular First Molars by Cone Beam Computed Tomography

Background and Objective: One of the most important stages of root canal treatment is the correct and complete preparation of the root canal. This study aimed to compare the amount of canal transportation in two nickel titanium files, OneShape and Neolix. Materials and Methods: In this experimental study, 30 extracted mandibular first molar teeth with 25-35-degree curvature were selected for periodontal reasons and randomly divided into two groups (n=15 each). A cone beam computed tomography (CBCT) scan was obtained from the teeth before the intervention. Followingly, the teeth of each group were prepared by the desired file (OneShape and Neolix) according to the manufacturer's instructions. Another CBCT scan was obtained from the teeth at the same angle. The amount of transportation was analyzed from the mesiodistal aspect at two distances of 3 and 9 mm from the apex. The preparation time of each tooth was also recorded by a chronometer. Data were analyzed by independent t-tests (α=0.05). Results: The mean transport at a distance of 3 mm from the apex in the OneShape and Neolix groups was 0.19 and 0.1 mm, respectively. The mean transport at a distance of 9 mm from the apex was 0.2 and 0.1 mm in the OneShape and Neolix groups, respectively. Statistically, there was no significant difference in the amount of transportation between the two groups at the distance of 3 mm (P=0.055) and 9 mm (P=0.39). The mean preparation time was longer in the OneShape group than in the Neolix one; however, it did not show a statistically significant difference (P=0.73). Conclusion: Both Neolix and OneShape files can maintain the curvature of the canal and are suitable for curved canals in terms of shaping ability.

Shaping outcomes of Reciproc Blue and Rotate in roots canals with band-shaped isthmuses: micro-CT study.

This study assessed the outcome of shaping the mesial roots of mandibular first molars containing band-shaped isthmuses with an isthmus floor located at the apical third with Reciproc Blue and Rotate instruments in terms of canal transportation, canal aberrations and unprepared apical canals. Pair-matched mesial roots of mandibular first molars according to their isthmus location (distance from apical foramina) and size were constructed based on quantitative measurements (length, major and minor diameter at isthmus roof and floor) on preoperative micro-CT scanning (n = 10). The pair-matched specimens were prepared either using Reciproc Blue R25 (25.08v) or Rotate (15.04, 20.05, 25.06) instruments and then subjected to a second micro-CT scanning. Micro-CT scans were analysed to evaluate the canal transportation at the apical foramen and isthmus floor levels and the frequency of procedural errors (separated instruments, artificial canal preparation, cross shaping and unprepared apical canals). Canal transportation values were compared using Mann-Whitney U, and the distribution of procedural errors was compared with chi-square tests with a 5% significance threshold. Greater transportation values were detected in the apical foramen level compared to the isthmus floor in both groups. No significant difference was detected between Rotate and Reciproc Blue groups in terms of absolute transportation values and the incidence of procedural errors (p > .05). Preparation of mesial root canals containing a band-shaped isthmus at the apical portion with Reciproc Blue and Rotate instruments caused transportation of the original canal position at the isthmus floor and the apical foramen levels and resulted in procedural errors. This ex vivo micro-CT study using controlled pair-matched specimens showed that presence of a band-shaped isthmus complicates canal preparation procedure irrespective of the preparation systems.

Farklı tek eğe sistemlerinin alt çene birinci büyük azı dişlerinin tehlike alanındaki dentin kalınlığına etkisi

Background: To compare the dentin thickness in the danger zone of mandibular molars after preparation with one rotating (XP-endo Shaper) and two reciprocating (One Reci and Reciproc Blue) single file systems using a cone beam computed tomography (CBCT).&#x0D; Materials and Methods: Thirty-six mesial roots of mandibular first molars having two independent canals were selected. After initial CBCT scans were provided, teeth were assigned into 3 groups related to the single file used: XP-Endo Shaper (XPS), One Reci (OR) and Reciproc Blue (RB). The roots were scanned again after preparation with respective single file systems. The minimum dentine thickness in the danger zone, at 4, 5, 6 and 7 mm below the furcation level, were measured in CBCT scans. Initial and final measurements were used to calculate the removed dentin thickness in the danger zone. Data was analyzed using Repeated-measures ANOVA (p=0.05).&#x0D; Results : No significant differences were found related with remaining and removed dentin thickness among single file systems at any level from the furcation (p&gt;0.05). &#x0D; Conclusions: The evaluated single file systems showed similar cutting efficiency in the danger zone of mandibular molars.

Age-related changes in the morphology of the root canal system of mandibular first molars: a micro-CT study.

This study aimed to evaluate changes on root canal morphology in patients with different ages using micro-CT technology. Mandibular first molars (n = 150) were scanned at a pixel size of 13.68µm, categorized into 3 groups according to patient's age and analyzed regarding configuration, orifices, apical foramina, root length, canal volume, and surface area. Morphological 2D and 3D parameters were evaluated in distal roots with Type I configuration (n = 109) as well as the morphology of isthmuses Types I and III in 68 mesial roots. One-way ANOVA post hoc Tukey and Kruskal-Wallis tests were used for statistical analyses (α = 5%). A great variation in the canal configuration was found. No difference was observed in roots' length (p > 0.05). Canal volume reduced with age (p < 0.05), while surface area increased (p < 0.05) in patients ≤ 30years. There was no difference in canal/root length, area, and from foramen to the apex in distal roots with Type I configuration (p > 0.05), but 2D and 3D parameters significantly decreased with age (p < 0.05). Overall, the diameter of the isthmuses' roof reduced with age (p < 0.05). In patients ≥ 31years with Type III isthmus the distance from the isthmus floor to the foramen of the mesiolingual canal also decreased (p < 0.05). Overall, the internal morphology of the mesial roots of mandibular first molars was more affected by aging than distal canals. The most relevant tested parameter that significantly reduced in both roots was the volume of the root canal systems. A detailed evaluation of fine anatomical aspects of the root canal system of mandibular first molars of patients with different ages showed that the internal morphology of mesial roots is more affected by aging than distal canals.

Prevalence of Third Root in the Permanent Lower First Molar (in vivo study)

Introduction: Successful endodontic treatment requires complete information about the morphology of the tooth’s root canals. Our research aims to assess the prevalence of a third root in permanent mandibular first molars among Iraqi people. Methods: Two hundred fifty-seven patients (161 females and 96 males) were involved. All patients required endodontic treatment of the permanent mandibular first molar. Regular teeth examinations were performed by two experienced Endodontists over a period of 18 months. Digital radiography and CBCT were used to investigate the presence of radix entomolaris (RE). The prevalence of a third root between males and females was compared. Statistical evaluation of the data obtained was conducted using a chi-square test with SPSS version 20, P ≤ 0.05 indicates a significant difference. Results: The total prevalence of RE was five teeth among 257 patients or 1.9%. Statistical analysis revealed a non significant difference (P &gt; 0.05) in the prevalence of a third root between females (2/161) and males (3/96) (1.2% and 3.1% respectively). Conclusion: Third roots in mandibular first molars among Iraqi people are not rare; therefore endodontists should keep attention to detect such morphological variations when performing endodontic treatment.

Taper 0.06 Versus Taper 0.04: The Impact on the Danger Zone

IntroductionThis study aimed to evaluate the effects of root canal enlargement on the danger zone (DZ) of mandibular molars. MethodsThirty mesial roots of mandibular first molars were scanned in micro-computed tomography (S1). Canals were sequentially enlarged with rotary instruments up to sizes 30/0.04 (S2) and 30/0.06 (S3). The dentin thickness was measured at 0.1-mm intervals after each preparation step (n = 2964 slices). Root level and position of the DZ were also recorded. Data were compared using analysis of variance with Bonferroni pairwise comparison, Cochran's Q method, and Pearson's test (α = 5%). ResultsComparing the specimens before (S1) and after (S2 and S3) preparations showed a significant reduction in the thickness of the DZ (P < .05), as well as between S2 and S3 steps (P < .05). At S1, the DZ was mostly located in the middle third of the root, but after preparation, it shifted toward the coronal direction (P < .05). Both S2 (P = .004, r = 0.508) and S3 (P = .004, r = 0.506) preparation steps showed a positive correlation between canal length and the root level of the DZ. At S1, the DZ was positioned toward the distal and mesial in 73.4% (n = 22) and 26.6% (n = 8) of the specimens, respectively. After S3, the number of specimens with DZ positioned toward the mesial aspect of the root significantly reduced to 3.3% (n = 1), whereas none of the specimens with DZ positioned toward the distal changed its position after root canal enlargements (P > .05). ConclusionOverall, the enlargement of mesial canals of mandibular first molars with final instruments sizes 30/0.04 and 30/0.06 affected the thickness, root level, and position of the DZ.

Dentin Thickness of the Danger Zone in the Mesial Roots of the Mandibular Molars: A Cone Beam Computed Tomography Analysis

Mandibular first molars appear to be the most commonly tooth subjected to a root canal treatment, therefore a better understanding of the anatomy critical zones for resistance of this teeth may decrease the treatment's failure rate. So, this study was conducted to evaluate the dentin thickness of the danger zone in mesial roots of mandibular first molars using cone beam computed tomography in an Iranian population. In this cross-sectional study, 210 Cone Beam Computed Tomography acquisition of the mandibular first molars were collected from a radiology center in Qazvin. The dentin thickness of the mesial roots (mesiobuccal and mesiolingual canals) was measured from the furcation to 5 mm below. The relationship between the dentin thickness in the danger zone and parameters, like age, gender, placement side, root length, the curvature of the canal, canal type, presence of middle mesial canal, and distance between the orifices of the mesial canals was investigated. Frequency, mean and standard deviation for variables were calculated, and data analysis was done by SPSS using simple and multiple linear regression and Pearson correlation coefficient. Also, two-sample t-test was used to compare mesiobuccal and mesiolingual on two sides. The significant level was also considered at (p < 0.05). The average minimum thickness of danger zone dentin was found to be 0.885 ± 0.259 mm in the mesiobuccal canal and 0.906 ± 0.206 mm in the mesiolingualcanal. Also, the minimum thickness of dentin in the mesiobuccal and mesiolingual canals in the range of 0 to 1 mm from the furcation was more than in other areas. There was no significant relationship between the minimum dentin thickness of the danger zone with gender, placement side, root length, canal type, and mesial canal entrance distance. But with increasing age, the thickness of dentin in the danger zone in the mesiolingualcanal increased significantly (p = 0.008). It was also observed that with the increase in the curvature of the canal, the thickness of the dentin in the danger zone in the mesiobuccal canal decreased (moderately curved (p = 0.008), severely curved (p = 0.046)). In addition, the thickness of the dentin in the mesiobuccal and mesiolingual canal was less in the samples with the middle mesial canal (p = 0.047, 0.044). Less dentin thickness in the danger zone in the mesial roots of mesiolingual mandibular first molars was seen in younger patients in mesiolingual canal, with a greater degree of canal curvature in the mesiobuccal canal and teeth with a middle mesial canal. Therefore, it is suggested that large taper instruments should be used with more precision to prevent complications.

Internal morphology of distal roots of mandibular first molars revealed by computed microtomography.

To evaluate the internal morphology of 100 distal roots of mandibular first molars using micro-CT. Teeth were scanned to characterise: Vertucci type, root length, canal shape, presence and location of accessory canals, and the number of foramina at 4 mm from the apex, presence of root isthmus and the length from the primary canal to the apical foramen. Vertucci type I was found in 57% of cases, followed by V (27%). The most common cross-section 1 mm from the apex was oval (49%) and circular (38%). The average root length was 16.06 mm (16.61-19.02 mm). The mean foramen size was 0.32 and 0.53 mm for the minor and major diameters, respectively. The volume, surface area and SMI were 7.84 mm3 , 68.87 mm2 and 1.52 mm, respectively. Root isthmi were found in 47% of the samples, and the length mean from the primary canal to the apical foramen was 2,03 mm. The internal morphology of the distal roots of mandibular first molars may be complex and shows variations.

Dilacerated distolingual root of mandibular first molar mimicking cementoblastoma: case report by radiographic findings

Objectives: This case report aimed to report an extra root number of mandibular first molars that are mimicking benign cementoblastoma in the periapical radiograph and clarified using cone beam computed tomography (CBCT) examination.&#x0D; Case Report: A 22-year-old female patient was referred from private clinic to Radiology Department of Universitas Padjadjaran Dental Hospital for a CBCT examination of the left mandibular first molar with benign cementoblastoma as the provisional diagnosis.&#x0D; Conclusion: It is necessary to consider CBCT examination in order to obtain accurate diagnosis of the presence of distolingual root.

Shaping ability of waveone primary reciprocating files and oneshape rotary files in severely curved root canals

Introduction: This study compared the amount of canal transportation, canal centering ability after instrumentation and time required for shaping of canal with WaveOne Primary Reciprocating file and OneShape Rotary file. Method: Thirty intact mesial roots of mandibular first molars were divided into Group I and Group II. Specimens in Group I were shaped with WaveOne Primary reciprocating files to the working length (WL) and specimens in Group II were shaped with OneShape Rotary file to the WL. Time required to prepare each canal was recorded. All the specimens were submitted to micro-computed tomography (µCT) unit for Pre- and post-instrumentation scan. Images were reconstructed and cross-sections corresponding to distances 3, 6 and 9 mm from the anatomic apex were selected for analysis. Statistical analysis was performed with Kruskal Wallis and paired t test. Results: Overall, both rotary files maintained root canal curvatures well. During canal preparation, OneShape file performed significantly better in the apical third when compared to the WaveOne Reciprocating file. WaveOne file required reasonably less time to prepare canal when rather than OneShape file.

Mandibular incisors with two canals are associated with the presence of the distolingual root in mandibular first molars: a cone-beam computed tomographic study

BackgroundThis study aimed to evaluate the root canal configurations and the association between mandibular first molars and distolingual root (DLR) and mandibular incisors using cone-beam computed tomography (CBCT).MethodsMandibular first molars and incisors were evaluated using CBCT images of 150 patients. Mandibular first molars were classified according to the presence or absence of DLR. The curvature of the DLR was evaluated using Schneider’s method in buccolingual and mesiodistal orientations. The angle of the mesiolingual–distolingual–distobuccal canal orifices (ML–DL–DB) was evaluated at the pulpal floor level. The mandibular central and lateral incisors were classified as either single canal or two canals. The association between the root canal system of the mandibular first molar and mandibular incisors was evaluated. Data were analyzed using the Chi-square test, Student’s t-test, and odds ratios from binary logistic regression. The significance level was set at 5%.ResultsThe frequency of mandibular first molars with DLR was 27.0% and that of mandibular incisors with two canals was 25.8%. The curvature of the DLR was 37.1° in the buccolingual orientation and 10.4° in the mesiodistal orientation. The angle of ML–DL–DB was 79.0°. The presence of two canal systems in mandibular incisors was associated with the presence of DLR in the mandibular first molar (left central incisors: p = 0.001, odds ratio = 4.25; left lateral incisors: p < 0.001, odds ratio = 3.8; right central incisors: p = 0.003, odds ratio = 3.86; right lateral incisors: p = 0.001, odds ratio = 3.44) but not with the curvature of the DLR or angle of the ML–DL–DB orifice (p > 0.05).ConclusionsThe mandibular first molar showed a high incidence of separate DLRs. It was confirmed that DLR in the mandibular first molar is highly associated with the presence of two-canal system in the mandibular incisors. This association can aid clinicians in successful endodontic treatments.

Vertucci\u2019s root canal configuration of 11,376 mandibular anteriors and its relationship with distolingual roots in mandibular first molars in a Cantonese population: a cone-beam computed tomography study

BackgroundCone-beam computed tomography (CBCT) was used to study the root canal system of mandibular anteriors (MAs) in a Cantonese population and to evaluate the correlation between the complicated root canal configurations of mandibular lateral incisors (MLIs) and the presence of distolingual roots (DLRs) in mandibular first molars (MFMs).MethodsA total of 11,376 mandibular anterior teeth were scanned by CBCT. Those whose images met the inclusion criteria were first analysed according to Vertucci's root canal configuration and then grouped based on gender, age, and side, and their effects on root canal morphology were analysed. Finally, statistical analysis was used to evaluate the correlation between the complicated root canal configurations of MLIs and the existence of DLRs in MFMs. All statistical analyses were performed by using SPSS 25.0 software. Quantitative data are presented as the mean ± standard deviation. Student’s t tests were used to calculate statistical significance. P < 0.05 was considered statistically significant.ResultsIn MAs in the Cantonese population, all mandibular central incisors (MCIs) and MLIs had one root, and 0.37% of mandibular canines (MCs) had two roots. The most common Vertucci's root canal configuration was Vertucci I followed by Vertucci III. A total of 30.91% of MLIs and approximately 8% of MCIs and MCs have complicated root canal configurations. There were no significant differences in the prevalence of DLRs in MFMs and the incidence of complicated root canal configurations of MLIs between males and females or between the right and left teeth. However, a significant difference was found in different age groups of root canal configurations in MLIs. Moreover, significant ipsilateral and contralateral correlations between MFMs with DLRs and MLIs with complicated root canal configurations were observed on both sides.ConclusionIn Cantonese population, the possibility of complicated root canal configuration in MLIs was higher, when DLR appeared in MFMs.

Radiographic analysis of interorifice distance and canal configuration in mesial roots of mandibular first molars

Introduction: The Middle Mesial Canal (MMC) is an additional root canal that can be present in the mandibular molars of some patients with high chances of being missed. The aim of this study is to determine the inter orifice distance between Messiobuccal (MB) and Mesiolingual (ML) canal orifice and its association with the presence or absence of MMC using CBCT to help the operator clinically in identifying the presence of MMC. Methods: 50 CBCT samples consisting of 100 permanent mandibular first molar teeth were analysed. The distance between the mesiobuccal and mesiolingual orifice was recorded. Statistical Analysis such Independent T test and Pearson correlation were used to determine the association between MB and ML interorifice distance and presence of MMC and variation in the prevalence of MMC among male and female and different age groups. Results: The mean distance between MB and ML canal orifice was 3.19 ± 0.42mm, in the presence and absence of MMC the mean distance was 3.66±0.24mm and 3.07±0.38 mm respectively. The mean inter orifice distance in males was 3.29 ± 0.38 mm and in females was 3.08 ± 0.45 mm.

Correlations between additional roots in maxillary second molars, maxillary first premolars, mandibular first molars and mandibular first premolars: a retrospective cone-beam computed tomography analysis.

This study aimed to determine the prevalence of additional roots in maxillary second molar (MSM), maxillary first premolar (MxFP), mandibular first molar (MnFM) and mandibular first premolar (MnFP) teeth and evaluate the correlations between the number of roots for these teeth. Images of 630 Turkish patients, in which all dental groups examined in the study were present bilaterally, were analyzed using cone-beam computed tomography. The images for the presence of the fourth root in MSMs, third root in MxFPs, distolingual root in MnFMs and complicated-root structure in MnFPs were assessed and divided additional roots into subgroups. The Chi-square test was used for categorical variables such as sex and tooth position. Logistic regression analysis was performed to understand the predictor variability of other teeth in teeth with extra roots. A p < 0.05 was considered statistically significant. Prevalence of the fourth root in MSMs was 1.75%, third root in MxFPs was 6.35%, third root in MnFMs was 3.57%, and complicated root in MnFPs was 21.9%. Positive correlations were observed between MSM, MxFP and MnFP teeth for increasing root numbers (P < 0.05). There was no significant correlation between root numbers of MnFM teeth and other tooth groups (P > 0.05) In the tooth groups examined, there was at least one explanatory variable (except for the right MnFM) tooth in addition to the contralateral tooth for the presence of additional roots.

Laser applications in smear layer removal from posterior root canals: A comparative study.

Aim:The aim of the study is to evaluate erbium laser efficiency in removing smear layer from mesial roots of mandibular first molars at different laser settings.Subjects and Methods:One hundred (100) mandibular first molars were selected. Ninety six (96) mesial roots were assigned to two experimental groups according to the laser wavelength applied: I. Er, Cr: YSGG and II. erbium-doped yttrium aluminum garnet laser system. Four samples were used as control group. Samples of each group were distributed into two subgroups (A and B), following specific irrigation protocol. Each subgroup was divided into four subcategories according to the applied power laser. Each subcategory consisted of six samples. Teeth were observed under scanning electron microscope.Statistical Analysis:Results were statistically analyzed with Kruskal–Wallis and Mann–Whitney test (SPSS statistics software).Results:No statistically significant difference was observed between experimental groups I and ΙΙ. However, statistically significant difference was found among subgroups IA and ΙB and ΙIA and ΙΙΒ. In every root third, groups IIA and ΙΙB had better outcomes but it was not statistically significant. There was no statistically significant difference among subcategories of Group I (ΙΑ1-4 and ΙΒ1-4) and Group ΙΙ (ΙΙΑ1-4 and ΙΙΒ1-4).Conclusion:Erbium laser with tested parameters did not completely remove the smear layer from the root canals. Chelating factors can contribute in the laser mechanism of smear layer removal from apical part of narrow and curved root canals.

Prevalence of root canal system configurations in the brazilian population analyzed by cone-beam computed tomography – a systematic review

Objectives: This study performed a systematic review of anatomy prevalence studies using cone-beam computed tomography to comprehend the root and root canal configuration types in Brazilian sub-populations. Methods: This systematic review followed PRISMA’s statements. Four electronic databases (PubMed, ScienceDirect, Lilacs, and Cochrane Collaboration) were accessed using MeSH terms and free-text keywords. The studies were selected according to predefined criteria. References of the collected studies, three peer-reviewed endodontic journals, and two peer-reviewed evidence-based dentistry journals were hand searched. The authors were contacted for additional information, if necessary. Eligible studies were submitted to a scientific merit assessment by two evaluators independently, who reached a final consensus for each study score using the Joanna Briggs Institute Critical Appraisal tool for prevalence studies. Results: A total of 2266 studies were identified. After analysis, 20 full-text articles were accessed for eligibility and 17 were included for qualitative synthesis. A high prevalence of mandibular incisors presenting two root canals was noted (~35.0% – 40.0). Moreover, a high proportion of two-rooted (17.0% – 28.4%) and two root canals (50.1% – 75.0%) morphologies were identified in maxillary second premolars. A wide range and a high percentage of a second mesiobuccal canal were detected for both maxillary first (37.1% – 88.5%) and second molars (21.8% – 83.4%). A second root canal prevalence ranging from 12.4% to 23.4% was observed in the distal root of mandibular first molars. Conclusions: In conclusion, different Brazilian sub-populations may present divergent characteristics regarding the root and root canal configurations. Clinicians should be aware of these variations for proper planning of endodontic treatment.

Geometric Analysis of the Distolingual Root and Canal in Mandibular First Molars: A Micro–computed Tomographic Study

IntroductionThe purpose of this study was to comprehensively assess by micro–computed tomographic imaging the anatomic features of distolingual (DL) roots and canals in mandibular first molars collected from 1 population. MethodsOne hundred two specimens were examined for the location and initial direction of the DL canal and the relationship between the distance of apical deviation and the angle of root curvature. ResultsAll DL roots had only 1 canal. A new 7-category classification system is proposed for the DL roots of mandibular first molars. Most DL roots were type IV (28 teeth), type III (26 teeth), and type V (25 teeth). The average canal curvature in all root types was over 25°. There was a positive correlation between the angles of root and canal curvature for types II, IV, and V (P < .05) but not for types I and III (P > .05). In the buccolingual view, most DL roots were straight, whereas in the mesiodistal view the root curvature was close to the maximum value. The orifice of the DL canal was 4 times further from the line that bisects a line between the mesiobuccal and mesiolingual canal orifices than the distobuccal canal. The angle between the mesiobuccal-mesiolingual line and the horizontal projection of the coronal third of the DL canal on the pulp floor was 8.1° ± 10.0° and 6.1° ± 8.2° for teeth from the left and right side, respectively. The angle between the inserted simulated file and the cementoenamel junction was 57.9° ± 6.3°. Seventy-three percent of the DL canals had no constriction in the apical area. The DL canals were narrow and had a conical frustum-like shape with a 0.04 taper at the apical portion. ConclusionsThe novel classification of the DL roots helps to better understand the clinically challenging anatomy of the root and canal.