Aim This study aimed to explore the morphology and complexity of mandibular anterior teeth in a Western Saudi Arabian sub-population using cone beam computed tomography (CBCT). Methodology CBCT scans from 818 patients were evaluated, and 3193 mandibular anterior teeth were analyzed for the number of roots, canal, canal configurations, separation level, bilateral symmetry, and gender associations. Results The results showed that all examined central and lateral incisors had a single root, and the majority exhibited a single canal. The prevalence of two canals in mandibular central and lateral incisors was 20.1% and 23.2%, respectively, resulting in an overall prevalence of 21.7% for two root canals in mandibular anterior teeth. The separation level of the two canals was predominantly located in the middle third of the root. Type I canal configuration was the most common, followed by type III. A high degree of bilateral symmetry in the number of canals and canal configurations was noted. Conclusion The findings contribute to the understanding of root canal anatomy in the Saudi population and provide valuable information for endodontic treatment planning.

In recent years, cone-beam computed tomography (CBCT) has been widely used to evaluate patients\' root canal anatomy due to its high resolution and noninvasive nature. As voxel size is one of the most important parameters affecting CBCT image quality, the current study evaluated the diagnostic potential of CBCT with 4 different voxel sizes in the detection of double root canal systems and accessory canals (ACs) in permanent mandibular incisors.
A total of 106 extracted mandibular permanent incisors were collected from the dental clinics, and then were scanned by using micro-CT with a voxel size of 9 μm. The teeth were then fixed in the tooth sockets of human dry mandibles and scanned by using a CBCT device with 4 different voxel sizes (300, 200, 250, and 125 μm). Four observers detected in blind the root canal morphology of the teeth according to the CBCT images, and the presence or absence of a double root canal system, and the presence or absence of ACs, were scored according to a 5-point scale, respectively. Receiver operating characteristic (ROC) analysis was performed, and DeLong test was used to compare the area under the curve (AUC) values and the micro-CT data was taken as a gold standard.
Among 106 sample teeth, 25 specimens with a double root canal system were identified by the micro-CT. ROC curve analysis of the data obtained by the four observers showed that in the detection of double root canal systems, the AUC values ranged from 0.765 to 0.889 for 300 μm voxel size, from 0.877 to 0.926 for 250 μm voxel size, from 0.893 to 0.967 for 200 μm voxel size, and from 0.914 to 0.967 for 125 μm voxel size (all p < 0.01). In general, we observed a trend that the AUC values, sensitivity, and specialty increased with the decrease in the voxel size, and significantly higher AUC values were detected in 125 μm voxel size images. In the detection of ACs, ROC curve analysis showed that among the four observers, the AUC values ranged from 0.554 to 0.639 for 300 μm voxel size, from 0.532 to 0.654 for 250 μm voxel size, from 0.567 to 0.626 for 200 μm voxel size, and from 0.638 to 0.678 for 125 μm voxel size. CBCT images at a voxel size of 125 μm had a weak diagnostic potential (AUC: 0.5-0.7, all p < 0.05) in the detection of AC, with a lower sensitivity ranging from 36.8 to 57.9% and a higher specialty ranging from 73.6 to 98.8%.
CBCT with 300 μm voxel size could only provide moderate diagnostic accuracy in the detection of a double canal system in mandibular incisors. CBCT with a voxel size of 125 μm exhibited high diagnostic value in the detection of double canal systems, while showing low but statistically significant value in the detection of ACs.

Hypodontia is an inherited condition involving the absence of one to six teeth. The permanent dentition is the most frequently affected; however, it may also affect the primary dentition. A congenitally missing tooth (CMT) is the most common dental abnormality, with the missing mandibular second premolar, maxillary lateral incisor, maxillary second premolar, and mandibular central incisor accounting for 90% of CMT in hypodontia studies. The etiology of CMT has been attributed to environmental and genetic contributing factors, with the latter having a strong influence. It may occur in isolation or in association with syndromes. Congenitally missing mandibular incisor is more common in the Asian population and females. Depending on the number and location of missing teeth, hypodontia may be a considerable issue for the clinician since it may impact occlusal balance, mastication, speech, and esthetics and often requires a multidisciplinary approach. Missing mandibular incisors are of particular interest to orthodontists because of the possibility of mandibular retrognathism, the potential for the development of malocclusion, and difficulty in achieving a balanced occlusion. This case report describes the skeletal and dental features of a nonsyndromic familial occurrence of missing mandibular incisors in three generations. A comprehensive literature search was also performed to review the familial cases with missing mandibular incisors.
UNASSIGNED: Selvaraj M, Sennimalai K, Samrit VD, et al. A Rare Incidence of Nonsyndromic Mandibular Incisor Agenesis in a Three-generation Family: Case Report and Literature Review. Int J Clin Pediatr Dent 2023;16(2):388-395.

UNASSIGNED: Treatment of incisors\' agenesis is challenging that arouses orthodontists\' interests. The purpose of this study was to compare the craniofacial pattern of individuals with or without congenitally missing mandibular incisors.
UNASSIGNED: This retrospective study included patients receiving orthodontic consultation between 1999 and 2019 at the Orthodontic Division of the Dental Department of Taipei Medical University Hospital. Cephalometric measurements were obtained through manual tracing and by using computer software. A total of 31 measurements were obtained to evaluate skeletal, dental and soft tissues, and chin morphology. A multivariate analysis of covariance, analysis of covariance, and Scheffé\'s post hoc tests were used to analyze the differences among a group of patients with one congenitally missing mandibular incisor (M1), a group of patients with two congenitally missing mandibular incisors (M2), and the control group. Student\'s t-test was used to analyze the differences between the M1 or M2 group and the control group. Significance was set at P < 0.05.
UNASSIGNED: Significant differences were observed between the M and control groups in terms of lower incisor angulation and facial balance. Regarding chin morphology, significant differences were noted between the M and control groups and also among the M1, M2, and control groups.
UNASSIGNED: The lower incisors of the M group are more retroclined than those of the control group, resulting in retrusive lower lips. Facial balance varies between the M and control groups. Congenitally missing mandibular incisors affect chin morphology, making the chin button prominent.

This study aimed to evaluate the prevalence of internal symmetry (the number and morphology of root canals) in the mandibular incisors using cone beam computed tomography (CBCT). A total of 302 CBCT scans involving 1,208 mandibular incisors were evaluated using the Vertucci\'s classification regarding the number and configuration of root canals. The central mandibular incisors exhibited two root canals in 22.6% of patients and lateral incisors in 24.3% of patients. Most teeth (76.4%) had a type I configuration (a single root canal, 1-1), 21.7% had type II (2-1), 1.1% had type V (1-2), and 0.8% had type IV (2-2). Teeth with a type-III configuration (1-2-1) were not found. In total, 17.5% of patients had a symmetric appearance of the two-canalled central mandibular incisors and 20.5% had a bilateral appearance of the two-canal lateral incisors. Moreover, in 12.3% of the patients, all four incisors showed two root canals. The highest degree of symmetry was found in incisors that had one root canal (central incisors: 217 of 302, lateral incisors: 229 of 302), followed by type 2-1 incisors (central incisors 50, lateral incisors 58). The influence of sex and age on the prevalence of symmetries was not significant. Concluding, the internal anatomy of the mandibular incisors cannot not be sufficiently predicted from the root canal anatomy of the contralateral tooth. Thorough clinical and radiographic inspection of each tooth remains mandatory to address the internal anatomy of the mandibular incisors correctly.

Mandibular incisors show variations in their root canal anatomy from regular pattern in some cases. Magnification plays a vital role to identify those unusual canal morphologies. A certain modification in access cavity preparation is required to locate those extra canals. Not only the functional restoration but also aesthetic harmony should be restored while treating anterior teeth. In these cases, post space preparation should be done with extra care to prevent vertical root fracture. This case report illustrates the importance of proper radiograph and magnification in the successful identification and management of complex canal systems in mandibular incisors.

OBJECTIVE: To introduce a new method to select anatomically matched teeth using micro-computed tomographic (micro-CT) technology.
METHODS: Single-rooted mandibular incisors with a single root canal (n = 60) were selected and distributed into three experimental groups according to the method used for matching 10 pairs of teeth in each group. In group 1, the pairs of mandibular incisors were randomly selected from a pool of teeth. In group 2, teeth were paired based on the measurement of canal width 5 mm from the root apex using radiographs taken from buccolingual and mesiodistal directions. In group 3, teeth were scanned (pixel size of 14.25 μm) and pair-matched based on the anatomical aspects of the root canal, named aspect ratio (AR), volume and three-dimensional canal geometry. After allocating the specimens into groups 1 and 2, the teeth were scanned and the canal morphology evaluated as in group 3. A bivariate Pearson\'s regression analysis was performed correlating the individual AR values of each pair, and the correlation coefficient was used to estimate the strength of the pair-matching process. One-way anova post hoc Tukey\'s tests were applied for pairwise comparisons at a significance level of 5%.
RESULTS: The micro-CT revealed that 100% of the samples had strong (80%) or very strong (20%) correlations with respect to AR values. Analysis of the radiographic method revealed strong correlation in two pairs (20%), but most of the samples had weak (30%) or negligible (30%) correlation coefficients. The randomization method resulted in three pairs (30%) with very strong correlations, whilst 50% had weak or negligible rates. A significant difference in correlation coefficients was observed in the micro-CT method compared to the other groups (P < 0.05), whilst no difference was detected between radiographic and randomized methods (P > 0.05). Eta-squared (η2 ) calculations demonstrated a very high effect size in the micro-CT group for selecting pairs (0.99) and lower effect sizes in the radiographic (0.67) and randomized (0.66) groups.
CONCLUSIONS: Use of Micro-CT was able to provide better control of the confounding effect that anatomical variances in tooth morphology may have on the results in experiments with matched-pair design.

OBJECTIVE: Alveolar bone surrounding mandibular incisors dictates the range of buccolingual inclination that can be achieved with treatment. The objective of this study was to evaluate the mandibular anterior alveolar thickness and height in individuals with different sagittal and vertical skeletal relationships.
METHODS: Cone beam computed tomography scans of 53 individuals (22 males and 31 females; mean age 21.19±3.7 years) were classified into 3 groups according to the sagittal skeletal relationship (class I, class II, and class III) and the vertical growth pattern (hyperdivergent, normodivergent, and hypodivergent). The alveolar thickness and height of both mandibular central incisors were measured. Group comparisons were performed with analysis of variance and post hoc Scheffé tests. Multiple linear regression was applied to evaluate the influence of all variables on the alveolar conditions.
RESULTS: Alveolar thickness and height showed no significant differences among the class I, II and III groups (6 and 7mm regardless of the sagittal group, P>0.05). The middle and lower alveolar thicknesses were significantly smaller in hyperdivergent (5.76mm and 6.34mm) and normodivergent (6.29mm and 7.40mm) than hypodivergent individuals (6.63mm and 8.27mm respectively). The lingual alveolar height was smaller in hyperdivergent (6.04mm) than hypodivergent individuals (7.93mm) (P=0.029, 95%CI: 0.15-3.63) and the lingual bone height was smaller in hypodivergent (3.24mm) than hyperdivergent individuals (5.06mm) (P=0.029, 95%CI: 0.15-3.48). Multiple linear regression indicated a significant influence of the root length on the alveolar thickness and height.
CONCLUSIONS: The sagittal skeletal relationship showed no influence on the alveolar thickness or height, even if dental compensation was present. Hyperdivergent individuals showed smaller alveolar thicknesses and heights than hypodivergent individuals.

To analyze changes in occlusal characteristics following mandibular incisor extractions (MIE), to determine the usefulness of wax setups in treatment planning MIE cases and to compare the pre- and posttreatment dental attractiveness between MIE cases and nonextraction (NE) controls.
The Peer Assessment Rating (PAR) Index was used to score pre- and posttreatment dental casts of MIE cases (n = 14) and matched NE controls (n = 14). Occlusal characteristics were evaluated on diagnostic wax setups and posttreatment casts. Attractiveness of pre- and posttreatment cases judged on intraoral photographs of cases (n = 6) and controls (n = 6) were rated by 76 dental students and 10 laypeople using visual analogue scales (VAS).
The difference in PAR score reduction (%) between the MIE and NE groups was not significant. Between the wax setup and posttreatment casts, there were moderate correlations in overjet, overbite, and right canine classification. There was no significant difference in pre- and posttreatment change in VAS scores (%) for attractiveness between the MIE (49.8 ± 4.3 [S.E.]) and control groups (40.8 ± 4.3 [S.E.]). However, there was a significant difference (P = .000) between the observer groups.
There were no significant differences in the treatment outcomes of orthodontic cases treated with MIE or NE, indicating that MIE is a valid treatment option. A wax setup is moderately correlated with posttreatment results. Both laypeople and dental students rated posttreatment dental attractiveness higher than pretreatment in MIE and NE groups. Dental students tended to be more critical than laypeople in their ratings.

BACKGROUND: Recently, using cone-beam computed tomography (CBCT) to assess root canal morphology has become popular; however, few studies have examined its efficiency to assess the entire root canals, including the tiny lateral and accessory canals (LACs). This study aimed to assess the ability of CBCT to evaluate the root canal of mandibular incisors at three different scanning settings, compared with the canal staining and tooth clearing (CS) technique as the gold standard.
METHODS: CBCT images of 70 extracted mandibular incisors were taken using NewTom VG CBCT at high-resolution scan mode (HZ), zoom scan mode (ZS), and full scan mode (FS), with different scanning settings. A radiologist, a postgraduate student, and an endodontist assessed the root canal morphology in a blinded manner. The number of root canals (NC), canal configuration according to Vertucci\'s classification (VC), and LACs were evaluated twice by each evaluator using the CBCT images, in comparison with CS. Comparisons of the differences were used the chi-square test, and the intra-evaluator and inter-evaluator agreement were used the Kappa statistics; the significance level was set at 0.05.
RESULTS: The voxel dimension of HZ, ZS and FS modes were 0.125 mm, 0.20 mm and 0.25 mm respectively, and the HZ mode had significant increased scanning doses. For NC, the diagnostic accuracy was >90% in all three modes, with no significant difference among the evaluators and modes. VC and LAC could only be evaluated in HZ mode. For VC, the accuracies were 97.1%, 94.3%, and 92.9% respectively, with no significant differences among the three evaluators. For LAC, the accuracies were 80.0%, 13.3%, and 33.3% respectively, and there were significant differences among the three evaluators. Intra-evaluator agreement was excellent, with the kappa values indicating \"perfect\" to \"substantial\" agreement. Inter-evaluator agreement was excellent for NC and VC; however, Kappa values could not be analyzed due to LACs detected were so variable.
CONCLUSIONS: As far as possible, the HZ mode should be chosen to demonstrate the root canal system, and partial LACs could be detected using this mode; however, the potential benefit of the diagnostic information must be weighed against the increased radiation dose.