Roots Of Mandibular 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.

CORELATION BETWEEN PREOPERATIVE PATHOSES, POSITION OF IMPACTED MANDIBULAR THIRD MOLAR AND DEMOGRAPHIC CHARACTERISTICS

Third mandibular molars mainly appear to be in an inappropriate position in dental arch, so become the teeth which barely erupt or stay impacted in jaws. The aim of this study is to analyze the correlation between the preoperative pathologies with the position of the impacted third mandibular molar, sex and age of the patients. The sample of the study consisted of a total of 80 patients, of both sexes, diagnosed with fully or partially impacted third mandibular molars, who were followed up after the surgery for a three-month period. All the patients were clinically examined and for each of them was registered a panoramic radiography, to analyze the factors causing the pathology, which leads to the surgical extraction of the teeth. The most manifested preoperative pathologies correlating to the position of impacted mandibular third molars were: resorption of distal root of mandibular second adjacent molar, caries of second adjacent molar, pericoronitis, periodontal disease, frontal incisal mandibular crowding. All the pathologies were associated with the tooth position, some differed by age and gender. We conclude that preoperative complaints related to the position of the impacted third mandibular molar are in positive proportion to the age of the patients, i.e. subjective complaints increase with age: pain, limited opening of the mouth, local inflammation of the gingiva and paresthesia. The position of the impacted third mandibular molar affects the occurrence of preoperative pathologies: pericoronitis was most prevalent in impacted third mandibular molars with vertical position, class II, A position and partial impaction; periodontal diseases of second adjacent mandibular molar are most prevalent in impacted third mandibular molar with mesioangular position, class III, B position and partial impaction.

Effect of repetitive up-and-down movements on torque/force generation, surface defects and shaping ability of nickel-titanium rotary instruments: an ex vivo study

BackgroundThe screw-in effect is a tendency of a nickel-titanium (NiTi) rotary endodontic file to be pulled into the canal, which can result in a sudden increase in stress leading to instrument fracture, and over-instrumentation beyond the apex. To reduce screw-in force, repeated up-and-down movements are recommended to distribute flexural stress during instrumentation, especially in curved and constricted canals. However, there is no consensus on the optimal number of repetitions. Therefore, this study aimed to examine how repeated up-and-down movements at the working length affect torque/force generation, surface defects, and canal shaping ability of JIZAI and TruNatomy instruments.MethodsAn original automated root canal instrumentation device was used to prepare canals and to record torque/force changes. The mesial roots of human mandibular molars with approximately 30˚ of canal curvature were selected through geometric matching using micro-computed tomography. The samples were divided into three groups according to the number of up-and-down movements at the working length (1, 3, and 6 times; n = 24 each) and subdivided according to the instruments: JIZAI (#13/0.04 taper, #25/0.04 taper, and #35/0.04 taper) or TruNatomy (#17/0.02 taper, #26/0.04 taper, and #36/0.03 tape) (n = 12 each). The design, surface defects, phase transformation temperatures, nickel-titanium ratios, torque, force, shaping ability, and surface deformation were evaluated. Data were analyzed with the Kruskal-Wallis and Dunn’s tests (α = 0.05).ResultsThe instruments had different designs and phase transformation temperatures. The 3 and 6 up-and-down movements resulted in a smaller upward force compared to 1 movement (p < 0.05). TruNatomy generated significantly less maximum torque, force, and surface wear than JIZAI (p < 0.05). However, TruNatomy exhibited a larger canal deviation (p < 0.05). No statistical differences in shaping ability were detected between different up-and-down movements.ConclusionsUnder laboratory conditions with JIZAI and TruNatomy, a single up-and-down movement at the working length increased the screw-in force of subsequent instruments in severely curved canals in the single-length instrumentation technique. A single up-and-down movement generated more surface defects on the file when using JIZAI. TruNatomy resulted in less stress generation during instrumentation, while JIZAI better maintained the curvature of root canals.

Comprehensive Analysis of Mandibular First Molar Root and Canal Morphology in Saudi Patients Using Cone Beam Computed Tomography (CBCT).

BACKGROUND The goal of conventional endodontic therapy is to clean the root canal system thoroughly, restore tooth function, and prevent re-infection. Success depends on understanding root canal morphology, resolving apical periodontitis, and using proper techniques. Studies highlight variations in root canal anatomy, with cone-beam computed tomography (CBCT) being crucial for accurate diagnosis despite its high cost and limited availability. MATERIAL AND METHODS This retrospective study reviewed CBCT images of 1820 (907 male, 913 female) patients aged 18 to 78 years. Analysis included 2081 mandibular first molars for variations in root and canal morphology and right- and left-side symmetry. Inter-orifice distance was measured, along with distance from the cementoenamel junction (CEJ) to the level of canal bifurcation. RESULTS In this study, 96.01% of teeth had 2 roots and 3.89% had 3 roots. The percentages of canal configuration were 77.70% for 3 canals, 21.58% for 4 canals, 0.67% for 2 canals, and 0.05% for 1 canal. The inter-orifice distance was 2.07 mm for 2 canals in 1 root and 2.86 mm for 2 canals in separate distal roots. Distance from the CEJ to canal bifurcation varied significantly between 2 canals within 1 distal root (3.35 mm), 2 canals in separate distal roots (1.60 mm), as well as between distal (3.35 mm) and mesial roots (1.10 mm). CONCLUSIONS In mandibular first molars, only 3.89% have additional distolingual roots. Sex and ethnicity showed no influence on number of roots and canals. Distal canals showed a deeper bifurcation and greater inter-orifice distance than did mesial canals.

Cone-beam computed tomographic analysis of canal convolution in mesial root of mandibular second molars and a proposed new classification.

The aim is to evaluate the anatomical characteristics of mesiolingual and mesiobuccal canals in mandibular second molars particularly in terms of its exit direction, distance of confluence from the minor constriction, and the angle of confluence. The cone-beam computed tomography images of hundred mandibular second molars were analyzed. Endodontically treated teeth and those with anatomical variations such as C-shaped canal configuration were excluded from this study. The distance of the confluence from the minor constriction, angle of confluence, and the exit direction of the mesiobuccal and the mesiolingual canals were assessed. Data were analyzed using an independent t-test. The course of the mesiobuccal and mesiolingual canals beyond the confluence was towards the center of the root. The average angle of confluence was 32.75°-35.28°. The average distance of confluence from the minor constriction was 2.19 to 2.68 mm. The mesiolingual canal was straighter whereas the mesiobuccal canal had a tortuous course. Considering the results of the present study, a new classification has been proposed for the root canal morphology of the mesial root of mandibular second molars. The variation in the morphology of mandibular second molars highlights that the mesiolingual canal presented a mild curvature through and beyond the confluence when compared to the mesiobuccal canal which exhibited a tortuous course through the confluence.

Management of additional roots in mandibular molars: report of radix entomolaris and radix paramolaris cases

Achieving a favorable outcome after endodontic treatment depends on a clear understanding of tooth anatomy, identification of variations, and precise root canal location. Multi-rooted mandibular molars often deviate from the expected configuration, sometimes featuring additional roots, such as radix entomolaris (RE) and radix paramolaris (RP), posing challenges during treatment. Detecting these variations is challenging due to their proximity to the distal root, and overlooking them can lead to complications. This study presents three cases involving RE and RP and offers insights into their clinical management, encompassing thorough clinical assessment, diagnosis, and root canal treatment. At follow-up examinations, patients were asymptomatic with no radiographic evidence of persistent infection. Therefore, clinicians must be aware and informed about the potential presence of additional roots in mandibular molars during root canal procedures, as understanding and addressing anatomical variations like RE and RP is crucial for achieving favorable outcomes in root canal treatments.

Morphological study of distal furcation in mandibular first molars based on cone beam computed tomography images in Beijing population.

This retrospective study explored the incidence of independent distal-lingual root (DLR) in mandibular first molars and the morphologic features of distal furcations through cone beam computed tomography (CBCT) in Beijing population. A total of 401 CBCT images of both mandibular first molars existed were included. The sex of the patients, the incidence of DLR, the distal root trunk length (DRT), the locations of distal furcation entrance (DFE), and the separation angle of distal furcation (ADF) were recorded. The incidence rates of DLR were 33.2% on the subject level and 26.8% on the tooth level. The incidence of DLR was not different between genders but was higher on the right sides. The DRT values were 4.15 mm±1.02 mm. The ADF was 65.56°±11.56°. The DFE was located lingually, and 97.2% DFE was located more apically than buccal/lingual furcations. A high incidence of DLR was found in the Beijing population. The DRT was longer than buccal and lingual sites. The DFE was located lingually with a wide separation. Understanding the morphological features of distal furcation can help clinicians to make proper treatment plans.

Biomechanical impact of different isthmus positions in mandibular first molar root canals: a finite element analysis.

This study used image-based finite element analysis (FEA) to assess the biomechanical changes in mandibular first molars resulting from alterations in the position of the root canal isthmus. A healthy mandibular first molar, characterized by two intact root canals and a cavity-free surface, was selected as the subject. A three-dimensional model for the molar was established using scanned images of the patient's mandibular teeth. Subsequently, four distinct finite element models were created, each representing varied root canal morphologies: non-isthmus (Group A), isthmus located at the upper 1/3 of the root (Group B), middle 1/3 of the root (Group C), and lower 1/3 of the root (Group D). A static load of 200 N was applied along the tooth's longitudinal axis on the occlusal surface to simulate regular chewing forces. The biomechanical assessment was conducted regarding the mechanical stress profile within the root dentin. The equivalent stress (Von Mises stress) was used to assess the biomechanical features of mandibular teeth under mechanical loading. In Group A (without an isthmus), the maximum stress was 22.2MPa, while experimental groups with an isthmus exhibited higher stresses, reaching up to 29.4MPa. All maximum stresses were concentrated near the apical foramen. The presence of the isthmus modified the stress distribution in the dentin wall of the tooth canal. Notably, dentin stresses at specific locations demonstrated differences: at 8mm from the root tip, Group B: 13.6MPa vs. Group A: 11.4MPa; at 3mm from the root tip, Group C: 14.2MPa vs. Group A: 4.5MPa; at 1mm from the root tip, Group D: 25.1MPa vs. Group A: 10.3MPa. The maximum stress in the root canal dentin within the isthmus region was located either at the top or bottom of the isthmus. A root canal isthmus modifies the stress profile within the dentin. The maximum stress occurs near the apical foramen and significantly increases when the isthmus is located closer to the apical foramina.

Effect of Multiple Glide Path Files on Apical Debris Extrusion in Severely Curved Mesial Roots of Mandibular Molars: An In Vitro Study

Effect of Multiple Glide Path Files on Apical Debris Extrusion in Severely Curved Mesial Roots of Mandibular Molars: An In Vitro Study

Influence of root shape on canal complexity at the mandibular molar apical surgical resection level: A micro-CT study

ObjectivesThis study aimed to investigate the relationship between the aspect ratios of mandibular molar roots at the apical 3-mm level and their root canal complexity. DesignThis study used micro-CT imaging to analyze 163 two-rooted mandibular molars. The aspect ratios of the roots at the apical 3-mm level were categorized as "< 2.75" or "≥ 2.75" (mesial) and "< 1.75" or "≥ 1.75" (distal). A two-dimensional (2D) analysis focused on four apical axial cross-section levels to determine the presence of main and accessory canals and isthmus. Additionally, a three-dimensional (3D) assessment of the apical 4-mm of both roots examined main and accessory canals, apical foramina, apical deltas, and middle mesial canals. ResultsMesial roots with aspect ratios ≥ 2.75 showed a higher number of main canals at all levels compared to those with aspect ratios < 2.75 at the 3-mm level. Additionally, the ≥ 2.75 group exhibited more accessory canals and a higher average number of accessory canals. The 3D assessment confirmed significantly more accessory canals and apical foramina in the ≥ 2.75 group. The prevalence of roots with apical deltas was nearly double in the ≥ 2.75 group, and middle mesial canals were exclusively found in this group. In the distal root, the ≥ 1.75 group showed a significantly higher number of main canals at all axial levels. No significant differences were observed between groups in terms of accessory canals, apical foramina, or deltas. ConclusionsA higher root aspect ratio is related to higher anatomical complexity.

Clinical relevance of distolingual roots and periodontal status in mandibular first molars: a cross-sectional study employing CBCT analysis.

OBJECTIVES: Distolingual root of the permanent mandibular first molar (PMFM-DLR) has been frequently reported, which may complicate the treatment of periodontitis. This study aimed to assess the morphological features of PMFM-DLR and investigate the correlation between the morphological features of PMFM-DLR and periodontal status in patients with Eastern Chinese ethnic background. MATERIALS AND METHODS: A total of 836 cone beam computed tomography (CBCT) images with 1497 mandibular first molars were analyzed to observe the prevalence of PMFM-DLR at the patients and tooth levels in Eastern China. Among them, complete periodontal charts were available for 69 Chinese patients with 103 teeth. Correlation and regression analyses were used to evaluate the correlation between the morphological features of DLR, bone loss, and periodontal clinical parameters, including clinical attachment loss (CAL), probing pocket depth (PPD), gingival recession (GR), and furcation involvement (FI). RESULTS: The patient-level prevalence and tooth-level prevalence of DLR in mandibular first molars were 29.4% and 26.3%, respectively. Multiple linear regression analysis suggested that bone loss at the lingual site and CAL were negatively affected by the angle of separation between distolingual and mesial roots in the transverse section, while they were significantly influenced by age and the angle of separation between distobuccal and mesial roots in the coronal section. CONCLUSIONS: The prevalence of PMFM-DLR in Eastern China was relatively high in our cohort. The morphological features of DLR were correlated with the periodontal status of mandibular first molars. This study provides critical information on the morphological features of DLR for improved diagnosis and treatment options of mandibular molars with DLR.

Effect of Radiotherapy and Taper of Root Canal Preparation on the Biomechanical Behavior of Mesial Roots of Mandibular Molars

IntroductionThis study aimed to investigate the effect of radiotherapy and taper of root canal preparation on the biomechanical behavior of mesial roots of mandibular molars. MethodsEighty mandibular molars with 2 canals in the mesial root were randomly allocated into 2 groups (n = 40): one group underwent irradiation (60 Gy), while the other did not. Subsequently, the mesial roots were sectioned and each group was subdivided into 5 subgroups (n = 8), according to the preparation taper: no preparation (control); 25.03; 25.04; 25.06; and 25.08. All groups were considered homogeneous regarding their dimensions, weight, and morphology. The prepared specimens were embedded in cylindrical plastic molds and subjected to a cyclic fatigue test. A failure analysis was performed according to the extension and course of the fractures. Two-way ANOVA, Tukey's post-hoc, Fisher's exact, and Kaplan–Meier tests were conducted to evaluate the obtained data (α = 5%). ResultsFatigue resistance decreased as the taper of the preparation increased (P < .05). Preparation 25.03 presented significantly higher values only than 25.08 (P < .05), while 25.04, 25.06, and 25.08 were considered similar (P > .05). Irradiation significantly reduced the biomechanical performance (P < .05). Survival analysis corroborated these findings. There were no differences in the distribution of fracture types among the groups (P > .05). ConclusionThe biomechanical behavior of the mesial roots of the mandibular molars decreased significantly in the face of irradiation and as the taper of the preparation increased.

The effect of root canal preparation tapers on planktonic bacteria and biofilm reduction in the apical third: A correlative microtomography and microbiological laboratory study.

To evaluate the influence of different preparation tapers on the reduction in planktonic bacteria and biofilms of Enterococcus faecalis and Candida albicans in the apical third (4 mm) of the mesial roots of mandibular molars, correlating decontamination with canal shape. After microtomography analysis for morphological standardization of the canals, 48 mandibular molar roots, each containing two canals (96 canals), were contaminated with E. faecalis and C. albicans and divided into four groups (n = 11) for canal instrumentation using ProDesign Logic 2 files with different tapers G (.03): # 25.03; G (.04): # 25.04; G (.05): # 25.05; and G (.06): # 25.06 and irrigation with 2.5% sodium hypochlorite. Four roots were examined under a scanning electron microscope (SEM) to qualitatively assess biofilm formation. Eight roots were used as the negative control group (samples were not contaminated). Bacteriological samples were taken exclusively from the apical third of the roots before and after chemical-mechanical preparation and bacterial counts were determined (CFU/mL). The final micro-CT scan was used to quantify the volume variation and unprepared canal area in the apical third. Statistical analysis was performed using the Kruskal-Wallis, Student-Newman-Keuls and Wilcoxon tests for analysis of microbiological data. anova and the Tukey or Games-Howell test were used for analysis of micro-CT data and Spearman's test for correlations (α = 5%). All groups showed a significant reduction in bacteria (p < .05), with no statistically significant difference between groups. There was no significant difference in per cent volume increase between groups. The unprepared area (Δ%) was affected by the file used (p = .026) and was significantly lower for G (.06) compared to G (.03). There was no statistically significant correlation among bacterial reduction, volume and unprepared area (p > .05). The different preparation tapers influenced root canal shaping in the apical third but did not improve decontamination in this region.

How Does Intentional Apical Foraminal Enlargement Affect the Foramen and Root Canal Morphology?

IntroductionThis study assessed the effect of intentional foraminal enlargement on the foramen and the apical root canal morphology. MethodSixty mesial roots of mandibular molars were scanned by micro-computed tomography. Their apical foramina were photographed with a stereomicroscope before and after preparation. Three groups were formed (n = 20) according to the working length (WL). G-1: foramen - 1 mm; G0: foramen; and G+1: foramen + 1 mm. Each group originated 2 subgroups (n = 10): G-1: Buchanan's patency (size 10 K-type file) and foraminal debridement (sizes 20, 25 and 30 K-type files); G0 and G+1: rotary foraminal enlargement (ProDesign S size 25/.08) or reciprocating foraminal enlargement (R25). The area, perimeter, transportation, and noninstrumented walls of the foramen were evaluated. The root canal transportation and the centering index of preparation at 1, 3 and 5 mm from the foramen were also assessed. Data were compared statistically (α = 5%). ResultsThe instruments used at the foramen and 1 mm beyond promoted foraminal enlargement and transportation. Regarding NIW, there was no difference between mechanized foraminal enlargements performed at the foramen or 1 mm beyond, similar to the manual foraminal debridement group (P > .05). There was no difference in transportation and centralization at 1-, 3-, and 5-mm apical levels, regardless of the instrumentation systems. ConclusionMechanical preparation at the foramen, or 1 mm beyond, resulted in foraminal enlargement, transportation and were not able to touch all root canal walls that delimit the foramen.

Efficacy of the GentleWave System in the removal of biofilm from the mesial roots of mandibular molars before and after minimal instrumentation: An exvivo study.

To compare the efficacy of Enterococcus faecalis biofilm removal using the GentleWave System (GWS) (Sonendo Inc, CA) on non-instrumented versus minimally instrumented root canal systems. Thirty-four mandibular molars were autoclaved and allocated to four groups: Negative control (n = 5); positive control (n = 5); Group 1: non-instrumentation + GWS (NI + GWS) (n = 12); and Group 2: minimal instrumentation + GWS (MI + GWS) (n = 12). Of 34 samples, 24 samples with Vertucci type 2 configuration within the mesial root of each sample were allocated to Groups 1 and 2 and then matched based on the working length and root canal configuration. After inoculation of samples with E. faecalis for 3 weeks, the GWS was used on Group 1 without any instrumentation and Group 2 after instrumentation of mesial canals until size 20/06v. CFU and SEM analysis were used. Log10 (CFU/mL) from the positive control, and Group 1 and 2 were 7.41 ± 0.53, 3.41 ± 1.54, and 3.21 ± 1.54, respectively. Both groups showed a statistically significant difference in the reduction of viable E. faecalis cells compared to the positive control (Group 1 [p = .0001] and Group 2 [p < .0001]), whilst showing no significant difference between the two tested groups (p < .05). The use of GWS on the non-instrumented root canal system could be an effective disinfection protocol in removing the biofilm without dentin debris formation.

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.

Accuracy of artificial intelligence-assisted growth prediction in skeletal Class I preadolescent patients using serial lateral cephalograms for a 2-year growth interval.

To investigate the accuracy of artificial intelligence-assisted growth prediction using a convolutional neural network (CNN) algorithm and longitudinal lateral cephalograms (Lat-cephs). A total of 198 Japanese preadolescent children, who had skeletal Class I malocclusion and whose Lat-cephs were available at age 8 years (T0) and 10 years (T1), were allocated into the training, validation, and test phases (n = 161, n = 17, n = 20). Orthodontists and the CNN model identified 28 hard-tissue landmarks (HTL) and 19 soft-tissue landmarks (STL). The mean prediction error values were defined as 'excellent,' 'very good,' 'good,' 'acceptable,' and 'unsatisfactory' (criteria: 0.5 mm, 1.0 mm, 1.5 mm, and 2.0 mm, respectively). The degree of accurate prediction percentage (APP) was defined as 'very high,' 'high,' 'medium,' and 'low' (criteria: 90%, 70%, and 50%, respectively) according to the percentage of subjects that showed the error range within 1.5 mm. All HTLs showed acceptable-to-excellent mean PE values, while the STLs Pog', Gn', and Me' showed unsatisfactory values, and the rest showed good-to-acceptable values. Regarding the degree of APP, HTLs Ba, ramus posterior, Pm, Pog, B-point, Me, and mandibular first molar root apex exhibited low APPs. The STLs labrale superius, lower embrasure, lower lip, point of lower profile, B', Pog,' Gn' and Me' also exhibited low APPs. The remainder of HTLs and STLs showed medium-to-very high APPs. Despite the possibility of using the CNN model to predict growth, further studies are needed to improve the prediction accuracy in HTLs and STLs of the chin area.

Pericervical Dentin Metrics in Mandibular First Molars Determined with Digital Periapical Radiography and Cone-beam Computed Tomography

IntroductionPericervical root dentin is decisive for the long-term mechanical integrity of root-filled teeth. Current treatment protocol does not include a customized step to determine the pretreatment residual pericervical root dentin. ObjectiveTo determine and compare the residual root dentin and canal width using digital periapical radiography (DPR) and cone-beam computed tomography (CBCT) at the apical limit of the pericervical area (PCA) in mandibular first molars. MethodsDPR and CBCT images of 60 patients with age between 22 and 76 years were used to determine (a) the mesiodistal widths of the root canal (pericervical dimensions [PCL]-C) and the root (PCL-R) of mandibular first molars at the apical limit of the PCA and (b) the intracanal distance from the apical limit of the PCA to the radiographic apex (intracanal distance [ICD]). The correlation between the PCL and ICD measurements obtained from DPR and CBCT were evaluated. ResultsValues between 0.10–0.80 mm and 0.00–1.10 mm were obtained for PCL-C using DPR and CBCT respectively (95% CI). The PCL values between 0.90–2.30 mm and 0.00–2.30 mm were obtained from DPR and CBCT respectively (95% CI). The ICD ranged between 4.6–12.3 mm in DPR and 4.40–12.0 mm in CBCT (95% CI). The comparative analysis showed differences from −0.9 to 0.5 mms for PCL and −2.00 to 1.5 mms for ICD between DPR and CBCT techniques respectively. ConclusionThe PCL and ICD determined from DPR and CBCT provided the pericervical dentin metrics that could be utilized clinically as a guideline for decision-making in endodontic treatment.

Root and canal morphology of mandibular second molar

Background: The mandibular second molar is the main chewing tooth and often suffer from pulp damage due to the misalignment of the mandibular third molar. In addition, it’s C-shaped root canal system is a challenge for endodontic treatment. This emphasizes the significance of tooth morphology and root canal system study which can contribute to anthropology, as well as Odonto-Stomatology. Purpose: The objective of this study was explore the morphology and root canal system of the mandibular second moalar in order to provide indicators dentistry applications. Materials and methods: Preclinical (in vitro) study was conducted on 48 mandibular socond molars which was collected in Thua Thien Hue province from December 2021 to June 2022. The teeth were measured externally and determine the shape of the roots. The canal system was examined with two methods including clearing technique and Cone Beam CT. Results: The average length of mandibular second molar was 20.37 ± 1.28 mm. 81.2% of teeth had one root, and 18.8% had two. The teeth with C-shaped roots accounted for 31.2%. The majority of distal roots possessed a simple type I (single canal) configuration. While the canal system of mesial roots was more complex which contained two canals, of which type I, II, III, IV were the most prevalent. C-shaped canal morphology was observed in 31.2% of the examined teeth. Conclusion: The root canall system of mandibular second molar was complex, the percentage of C-shaped canal was high (31.2%). There was similarlu results of two methods of clearing technique and Cone Beam CT in examining the root canal system of mandibular second molars. Key words: mandibular second molar, root canal system, C-shaped root, C-shaped root canal.

Is the assessment of the mandibular molar danger zone affected by field of view and voxel size in cone beam computed tomography examinations?

ObjectiveTo verify if assessment of the danger zone (DZ) in the mesial root of mandibular molars is affected by field of view (FOV) and voxel sizes in cone beam computed tomography (CBCT) scans. Study DesignForty mandibular molars were scanned by micro-computed tomography, creating the reference standard. The teeth were then submitted for CBCT scans with FOVs of 10 × 5.5 cm and 5 × 5.5 cm and voxel sizes of 0.4, 0.2, 0.15, and 0.075 mm3. The smallest dentin thickness in the DZ from the mesiobuccal and mesiolingual canals was measured at 2, 4, and 6 mm apical to the root furcation. Descriptive statistics, paired t-tests, and intraclass correlation coefficients were used for statistical analysis with significance established at P<0.05. ResultsAll CBCT measurements overestimated the DZ dentin thickness (P<0.001) compared to the reference standard. The greatest overestimation occurred in the 5 × 5.5 cm FOV with 0.4 mm3 voxels (P = 0.007). Dentin thickness measured with the 5 × 5.5 cm FOV and 0.075 mm3 voxels was significantly smaller and produced the best ICC value with the reference standard (0.936). ConclusionsCBCT overestimates the dentin thickness of the DZ regardless of FOV and voxel sizes. The 5 × 5.5 cm FOV showed the best performance with the 0.075 mm3 voxel size, but it performed poorly with 0.4 mm3 voxels.