Identification of Root Canal Morphology in Fused-rooted Mandibular Second Molars From X-ray Images Based on Deep Learning.

INTRODUCTION: Understanding the intricate anatomical morphology of fused-rooted mandibular second molars (MSMs) is essential for root canal treatment. The present study utilized a deep learning approach to identify the three-dimensional root canal morphology of MSMs from two-dimensional X-ray images. METHODS: A total of 271 fused-rooted MSMs were included in the study. Micro-computed tomography reconstruction images and two-dimensional X-ray projection images were obtained. The ground truth of three-dimensional root canal morphology was determined through micro-computed tomography images, which were classified into merging, symmetrical, and asymmetrical types. To amplify the X-ray image dataset, traditional augmentation techniques from the python package Augmentor and a multiangle projection method were employed. Identification of root canal morphology was conducted using the pretrained VGG19, ResNet18, ResNet50, and EfficientNet-b5 on X-ray images. The classification results from convolutional neural networks (CNNs) were then compared with those performed by endodontic residents. RESULTS: The multiangle projection augmentation method outperformed the traditional approach in all CNNs except for EfficientNet-b5. ResNet18 combined with the multiangle projection method outperformed all other combinations, with an overall accuracy of 79.25%. In specific classifications, accuracies of 81.13%, 86.79%, and 90.57% were achieved for merging, symmetrical, and asymmetrical types, respectively. Notably, CNNs surpassed endodontic residents in classification performance; the average accuracy for endodontic residents was only 60.38% (P < .05). CONCLUSIONS: CNNs were more effective than endodontic residents in identifying the three-dimensional root canal morphology of MSMs. The result indicates that CNNs possess the capacity to employ two-dimensional images effectively in aiding three-dimensional diagnoses.

Exploring the sex-associated differences in molars fused roots.

BACKGROUND: Human sexual dimorphism is associated with many biological characteristics, including dental variables. OBJECTIVES: To investigate if molars fused roots present sex-associated differences. METHODS: Panoramic radiographs were used to investigate the frequency and distribution of permanent molars fused roots. Only patients with all first and second permanent molars were included. Third molars were not investigated. Any molar with roots fused apical to the usual furcal position were considered molar fused roots. Comparisons between males and females were performed using chi-square or Fisher's and Mann-Whitney tests and the established alpha was 5% (p<0.05). Sex-differential liability models were also proposed. RESULTS: A total of 84 males and 86 females were included and 1360 molars were analyzed. Among them, 46 (26.06%) present at least one molar with fused root. Second maxillary molars were the most affected teeth. There was an association between sex and molars with fused roots. Females had a 3.4 higher chance to present fused roots than males (OR=3.4, CI 95% 1.6-6.8; p=0.0008). The female: male ratio of molars with fused roots was 2.5:1. The number of molars with fused roots ranged from 1 to 6 per patient, and the mean number of Females presented more molars with fused roots (mean = 1.01; standard deviation = 1.52) than males (mean = 0.31; standard deviation = 0.85) (p<0.05). CONCLUSIONS: Molar fused root of permanent teeth presents sex-associated differences, in which females are more affected than males. Our results support sex-differential liability models for molars fused roots.

Internal and external morphological analysis of fused-rooted mandibular second molars in the Chinese population: A micro-computed tomographic study.

This study investigated the root canal morphology of fused-rooted mandibular second molars based on the pulp chamber floor (PCF) and analysed the correlation between the external morphology of the radicular groove, and the internal morphology of the PCF and root canal configuration. A total of 291 fused-rooted teeth collected from the Chinese population were scanned using micro-computed tomography and a dental operating microscope was used for observing the PCFs. The classification of the PCF and root canal configuration were identified according to modified Min et al.'s and Gao et al.'s classifications, respectively. Additionally, a new radicular groove classification was proposed. The correlation among these morphological characteristics was investigated using the chi-square test and Fisher's exact test (p < 0.05). The results showed that 74.2% of teeth had C-shaped PCFs, while 21.0% had non-C-shaped PCFs. As for the root canal configurations, 37.5% of teeth were merging type, 40.9% were symmetrical type, and 14.8% were asymmetrical type. Statistical analysis revealed a significant correlation between the PCF types and the root canal configurations (p < 0.001). The dominant root canal types for teeth with C-shaped PCFs were merging and symmetrical types, while the asymmetrical type was not identified in non-C-shaped PCFs. In addition, significant morphological association between the root canals and radicular grooves was also revealed (p < 0.001). Teeth with different PCF morphologies exhibit specific patterns of root canal category distribution. Understanding the morphological nuances of the root canal based on the PCF can assist clinicians in predicting and identifying the canal configuration beneath the visible orifice.

Double Gemination or Fusion of a Permanent Mandibular Second Molar: A Case Report.

Gemination and fusion are developmental conditions affecting the shape of teeth in both primary and permanent dentition. A 12-year-old girl presented for clinical assessment and the examination revealed an unusually shaped mandibular right second molar with irreversible pulpitis. Correlation of the intraoral and radiological appearance of this tooth suggested a diagnosis of either double gemination or fusion. The favourable position of the developing third molar supported early extraction of the abnormal second molar. The present report documents the clinical and radiological presentation of a mandibular second molar with an unusual developmental alteration in shape. Well-timed extraction therapy and good communication may reduce the need for unnecessary, complex treatment.

Fusión del tercer molar inferior con un cuarto molar: reporte de tres casos / Fusion of the lower third molar with a fourth molar: report of three cases

Los dientes supernumerarios y la fusión dental son anomalías del desarrollo dental cuyas causas aún no se han dilucidado con certeza. El cuarto molar inferior, también denominado distomolar, es uno de los dientes supernumerarios con menor frecuencia de aparición clínica y su fusión con el tercer molar es una condición todavía menos común. A continuación, se reportan los casos clínicos de tres pacientes masculinos que presentaron fusión del tercer molar inferior derecho con un distomolar tratados mediante odontectomía (AU)

Supernumerary teeth and dental fusion are abnormalities of dental development whose causes have not yet been elucidated with certainty. The lower fourth molar, also called distomolar, is one of the supernumerary teeth with the least frequency of clinical appearance and its fusion with the third molar is an even less common condition. Next, the clinical cases of three male patients who presented fusion of the right lower third molar with a distomolar treated by odontectomy are reported (AU)

Fork-shaped mandibular incisors as a novel phenotype of LRP5-associated disorder.

The LRP5 gene encodes a Wnt signaling receptor to which Wnt binds directly. In humans, pathogenic monoallelic variants in LRP5 have been associated with increased bone density and exudative vitreoretinopathy. In mice, LRP5 plays a role in tooth development, including periodontal tissue stability and cementum formation. Here, we report a 14-year-old patient with a de novo non-synonymous variant, p.(Val1245Met), in LRP5 who exhibited mildly reduced bone density and mild exudative vitreoretinopathy together with a previously unreported phenotype consisting of dental abnormalities that included fork-like small incisors with short roots and an anterior open bite, molars with a single root, and severe taurodontism. In that exudative vitreoretinopathy has been reported to be associated with heterozygous loss-of-function variants of LRP5 and that our patient reported here with the p.(Val1245Met) variant had mild exudative vitreoretinopathy, the variant can be considered as an incomplete loss-of-function variant. Alternatively, the p.(Val1245Met) variant can be considered as exerting a dominant-negative effect, as no patients with truncating LRP5 variants and exudative vitreoretinopathy have been reported to exhibit dental anomalies. The documentation of dental anomalies in the presently reported patient strongly supports the notion that LRP5 plays a critical role in odontogenesis in humans, similar to its role in mice.

Targeted Endodontic Microsurgery: A Novel Approach to Anatomically Challenging Scenarios Using 3-dimensional-printed Guides and Trephine Burs-A Report of 3 Cases.

Endodontic microsurgery (EMS) techniques have increased success rates over traditional approaches. Despite surgical advances, anatomically challenging scenarios can preclude EMS in certain cases. The aim of this article was to introduce targeted EMS, which uses 3-dimensional-printed surgical guides (3DSGs) and trephine burs to achieve single-step osteotomy, root-end resection, and biopsy in complex cases. In each of 3 cases, a 3DSG with a trephine port was printed using computer-aided design/computer-aided manufacturing implant planning software. The osteotomy site, angulation, and depth of preparation were defined preoperatively to avoid sensitive anatomic structures. The 3DSG was inserted at the target site to achieve precise osteotomy and root-end resection during surgery. A hollow trephine rotated within the 3DSG port produced single-step osteotomy, root-end resection, and biopsy. Root-end preparation and fill were accomplished, and tissues were sutured in place. Targeted EMS potentiated successful surgical treatment in 3 anatomically challenging scenarios: (1) a palatal approach to the palatal root of a maxillary second molar, (2) a facial approach to a fused distofacial-palatal root of a maxillary first molar, and (3) a mandibular second premolar in close proximity to the mental foramen. Trephine burs guided by 3DSGs produce efficient targeted osteotomies with a predictable site, angulation, and depth of preparation. Apical surgery in challenging anatomic cases such as the palatal root of the maxillary second molar, fused molar roots, and root ends in approximation to the mental nerve are possible with targeted EMS.

Primary Fused Teeth and Findings in Permanent Dentition.

OBJECTIVE: The aim of this study was to investigate the characteristics of primary fused teeth (PFT) and their effect on permanent dentition in a group of Turkish children. SUBJECTS AND METHODS: Dental records of 13,450 pediatric patients who attended the Pediatric Dental Clinic in northern Turkey between 2015 and 2017 were reviewed. Forty patients had been diagnosed with PFT and were included in the study. Clinical and radiographic examinations were conducted, and the distribution of PFT was calculated by type, sex, affected jaw, associated dental anomalies, and clinical complications. Data analysis involved descriptive statistics. RESULTS: A total of 50 PFT were detected in the 40 patients. The mean age of patients was 6.7 ± 0.3 years (range 3-10 years). The most common PFT were the mandibular lateral incisors and canines (34, 68%). The most prevalent type of PFT was type III (20, 40%). Of the 40 patients with PFT, 34 (85%) also ex-hibited other dental anomalies such as tooth aplasia, peg-shaped incisors, talon cusps, ectopic eruption, and delayed eruption in both related and unrelated areas. The most common complications of PFT were fusion-related tooth aplasia (n = 26 [76%]) and caries formation in the affected teeth (24 [48%]). CONCLUSION: In this study, PFT were frequently observed in the mandibular anterior region. Caries formation and dental anomalies, especially permanent tooth aplasia, were often encountered in areas where PFT were seen. Hence, parents should be informed about possible dental problems associated with PFT and be encouraged to schedule regular follow-up appointments.

Clinical and radiographic evaluation of double teeth in primary dentition and associated anomalies in the permanent successors.

OBJECTIVE: Understanding potential problems associated with primary double teeth (PDT) are important to provide prophylactic measures, thereby preventing or minimizing possible complications. The purposes of this study were to investigate the prevalence of PDT in a group of Turkish children and to compare the distribution of the different types of double primary teeth and their relationship to permanent successors. MATERIALS AND METHODS: A total of 17,268 children underwent a clinical examination to determine the presence of PDT. One hundred fifty-two PDT of 128 children were included in this study. All the 128 children with PDT underwent a clinical examination and had photographs taken at the time of the examination. The children underwent a further periapical or panoramic radiographic examination to determine the status of the underlying permanent successors. The PDT was classified according to Aguilo's classification. RESULTS: The prevalence of PDT was 0.74%, with no significant statistical difference between the sexes. PDT was most frequently observed between the mandibular lateral incisors and canines. Of the 152 PDT, 10.7% were Type I, 15.3% were Type II, 26.1% were Type III, and 47.9% were Type IV. Dental anomalies on the succedaneous permanent teeth were diagnosed in 69.4% of the children with affected primary dentition. Aplasia of the permanent lateral incisor was observed most frequently in association with Type I (52.7%) PDT. Caries involvement was observed most frequently in Type III (56.2%) PDT. CONCLUSION: The findings of this study have clinical relevance for the diagnosis of children with PDT. Early clinical and radiographic identification of PDT can help the clinician to evaluate the number and condition of permanent successors and draw up a proper treatment plan.

Multidisciplinary approach to the treatment of double bilateral upper permanent incisors in a young boy.

BACKGROUND: A double tooth is a rare developmental anomaly referring to the fusion of two adjacent tooth buds or the gemination of a single bud. CASE REPORT: This case report describes the multidisciplinary approach to an 11-year-old patient with two double upper permanent incisors. The clinical intraoral examination showed a mixed dentition with bilateral double maxillary central incisors, molar Class I malocclusion and palatal ectopy of two lateral upper incisors. Computed tomography of the upper dental arch revealed the presence of double central incisors with two distinct roots. The clinical choice consisted of an innovative treatment including surgical, endodontic, orthodontic and restorative treatments. This management protocol produced good aesthetic, healthy and functional results that were stable also two years post-treatment.

Endodontic Management of Dilacerated Maxillary Central Incisor fused to a Supernumerary Tooth using Cone Beam Computed Tomography: An Unusual Clinical Presentation.

AIM: The purpose of this report is to present a case of endodontic management of a dilacerated maxillary central incisor fused to supernumerary tooth unusually appearing as a labial tubercle using cone beam computed tomography (CBCT) as a diagnostic aid. BACKGROUND: Anterior teeth are commonly encountered with aberrant anatomical variations in the crown, number of roots, and root canals. Fusion is an infrequent developmental abnormality in shape of the tooth caused by the union of two adjacent tooth germs. A complete knowledge of such complex anatomies is mandatory for a successful root canal treatment. It highlights the endodontic and restorative approach in the functional and esthetic rehabilitation of the involved tooth. CASE REPORT: Three-dimensional imaging using CBCT was used in this case to differentiate single labial canal and palatal C-shaped canal. The endodontic treatment was performed with the aid of dental operating microscope, and the root canals were obturated with a combination of single cone, carrier based, and cold flowable gutta-percha obturation system. The tooth remained asymptomatic without reinfection and symptoms of failure for 18 months. CONCLUSION: Cone beam computed tomography is indispensable in treatment planning for cases where the radiographs cannot reveal useful information regarding the root canal shape. Postobturation CBCT has helped in avoiding further retreatment of the tooth, which otherwise is a challenging task. CLINICAL SIGNIFICANCE: The use of sophisticated equipment, such as dental operating microscope and CBCT has helped in accurate diagnosis and treatment planning of fused central incisor respectively.

Caracterización de la Impactación de Segundos Molares Mandibulares Permanentes en una Población Sudamericana / Characterization of Permanent Mandibular Second Molars Impaction in a Southamerican Population

El objetivo de este estudio fue describir las características epidemiológicas de segundos molares mandibulares permanentes impactados unilateralmente en una muestra de la ciudad de Medellín, Colombia. Se trató de un estudio retrospectivo en el cual se evaluaron radiografías panorámicas de 6785 pacientes, de las cuales se analizaron un total de 28 radiografías en la muestra final. Fueron correlacionados el segundo molar mandibular impactado (grupo de estudio) y el contralateral no impactado (grupo control) con respecto a tres ángulos de referencia (intermolar, del plano oclusal e interplanar), el sexo y lado de impactación. Se encontró una prevalencia de 3,5 por cada 1000 radiografías evaluadas. El lado de mayor impactación fue el derecho; dos de los tres ángulos analizados (intermolar e interplanar) fueron los que arrojaron las diferencias más grandes entre el grupo de estudio y el grupo control. No se encontraron diferencias estadísticamente significativas según el sexo. Se concluyó que la prevalencia de segundos molares mandibulares permanentes impactados es baja, siendo mayor en el lado derecho, sin diferencias por sexo, y de preferencia el uso del ángulo interplanar como medida para la evaluación del riesgo de impactación (>7,9°).

The objective of this study was to describe the epidemiological characteristics of unilateral permanent mandibular second molars impacted, in a sample from Medellín, Colombia. It was a retrospective study in which we evaluated panoramic radiographs of 6785 patients, for a total of 28 radiographs analyzed in the final sample. The mandibular second molar impacted (study group) and the contralateral not impacted (control group) were correlated, with respect to three reference angles (intermolar, of the oclussal plane and interplanar), sex and impaction side. We found a prevalence of 3.5 for every 1000 radiographs evaluated. The most frequent side of impaction was the right side; two of the three angular measurements (intermolar and interplanar) had the biggest differences between the study and control group. We did not find significant statistical differences between males and females. It was concluded that the prevalence of impacted permanent mandibular second molars is low, there is a highest impaction in the right side, there are no differences between genders, and the use of the interplanar angle is preferable as a measurement to predict the impaction of permanent mandibular second molars (>7.9°).

Bilateral supplemental maxillary central incisors with double-tooth like appearance.

BACKGROUND: Supplemental teeth refer to extra teeth that resemble the normal tooth series. Bilateral supplemental central incisors in a healthy individual are rare and bilateral supplemental incisors with double-tooth like appearance are exceptionally rare and has not been previously reported in the dental literature. CASE REPORT: This clinical report describes an 8-year old healthy Indian boy referred for the management of delayed eruption of his permanent maxillary incisor teeth. Following clinical and radiographic examination the two supplemental incisors closer to the midline were extracted under local analgesia and both of them exhibited double-tooth like appearance. CONCLUSIONS: The present case refutes the conventional wisdom that "supplemental teeth are usually smaller than the normal tooth type they resemble and occur distal to the normal tooth series", illustrates that the unusual can occur and that the clinician should be aware of such variations.

Management of non-syndromic double tooth affecting permanent maxillary central incisors: a systematic review.

To assess management of non-syndromic double tooth affecting permanent maxillary central incisors, we performed a systematic review and also present 2 case reports. We searched MEDLINE via PubMed and the reference lists of included reports. Eligible studies were any type of clinical studies describing the management of non-syndromic double tooth affecting the crown of a permanent maxillary central incisor. We included 68 studies corresponding to 72 relevant case reports. Therapeutic options in descending order of priority were restorative dentistry (35%), hemisection (33%), abstention (17%) or extraction (15%). Orthodontic management resulted in 57% of cases. We report an 11-year-old boy with bilateral fusion of the two maxillary central incisors and a 9-year-old boy with a double left central incisor and a supernumerary lateral right incisor. A multidisciplinary approach is key to management of permanent maxillary central incisors affected by coronary anomalies.

Prevalence of Root Fusions and Main Root Canal Merging in Human Upper and Lower Molars: A Cone-beam Computed Tomography In Vivo Study.

INTRODUCTION: Complex root canal systems appear regularly on fused roots. The aim of this observational study was to evaluate the prevalence of fused roots and root canal merging in the first and second upper and lower permanent molars by using cone-beam computed tomography technology. METHODS: A large sample of cone-beam computed tomography examinations was accessed. Maxillary and mandibular molars were classified according to number of roots, root fusions, types of root canal system configurations, merging positions, and merging levels. The Z test for proportions was used to analyze the differences in independent groups. A value of P < .05 was considered significant. RESULTS: This study included 4120 molars. The prevalence of root fusions was 7.1% and 25.2% for the first and second upper molars, respectively; for the first and second lower molars, the prevalence was 0.7% and 12.6%, respectively. In addition, 8.6% and 10.1% of the second upper and lower molars, respectively, had fused roots with canal merging; moreover, 7.1% and 2.1% of the second upper and lower molars had single or 2 non-merging root canals, respectively. The most usual merging position for the first upper molars is between the distobuccal root and palatal root canals; for the second upper molars, the most usual merging position is between the mesiobuccal root and distobuccal root canals. Merging appears more commonly at the apical level. Significant differences were found between the teeth and gender groups. CONCLUSIONS: When approaching the second upper and lower molars, the clinician should be aware of uncommon morphologies. In our sample, 15.7% and 12.2% of the second upper and lower molars, respectively, had fused roots, which did not present the usual configurations with independent root canals.

Prevalence and Characteristics of the Maxillary C-shaped Molar.

INTRODUCTION: The anatomy of the maxillary C-shaped molar has been the subject of several case reports although no true prevalence research has ever been conducted. The aim of this observational study was to evaluate and characterize the incidence of these morphologies using cone-beam computed tomographic (CBCT) technology. METHODS: Patients having presurgical CBCT examination were selected. CBCT analysis was performed at 5 different axial levels, and the teeth were classified as maxillary molar C shapes according to the inclusion criteria for the present investigation. The prevalence of C-shaped anatomy was calculated. The z test for proportions in independent groups was used to analyze the differences between proportions. Intrarater reliability was also tested. RESULTS: A total of 2227 teeth (928 upper first molars and 1299 upper second molars) from 895 patients were included in this research. Five different types of C-shaped molars were found, which included fusion between mesiobuccal and palatal roots (type A), mesiobuccal and distobuccal roots (type B), distobuccal and palatal roots (type C), 2 possible palatal roots (type D), and mesiobuccal and palatal roots connecting with an independent distobuccal root canal at apical or between distobuccal and palatal roots connecting with an independent mesiobuccal root canal at apical (type E). The global prevalence was 1.1% for first molars and 3.8% for second molars. Differences were observed between sex, teeth, and some types of C shapes at P < .05. CONCLUSIONS: Maxillary C-shaped molars have low prevalence but high anatomic complexity. An understanding of their anatomic configuration and variations is important in ensuring that they are treated properly. Distinct differences exist between C-shaped configurations of upper and lower molars.

Concurrence of Gemination and Fusion in Maxillary Central Incisors: A Case Report.

This case reports the concurrence of gemination and fusion affecting the maxillary central incisors of a twelve-year-old patient and the collaboration of the pediatric dentist, endodontist, orthodontist and oral and maxillofacial surgeon. Developmental dental anomalies can occur in both primary and permanent dentitions as a result of conjoining defects. Double teeth, or cases of gemination or fusion, are not exceedingly rare, but the presence of both anomalies in a single patient is a rarity. Gemination is the division of a single tooth bud, resulting in a large single tooth with a bifid crown and common root and root canal. Fusion is the union of two separate tooth buds, resulting in a joined tooth with confluence of dentin and separate root canals. Labial apexogenesis with MTA, composite resin placement, re-contouring and orthodontic care allowed proper alignment with long-term monitoring of growth and development for possible incisor replacement.

Unilateral fusion of a supernumerary tooth to a maxillary permanent lateral incisor: a report of a rare case.

A supernumerary tooth is an additional entity to the normal series of teeth that may occur in isolation or may be fused to a normal counterpart. Diagnosis and delineation of an accurate treatment plan in cases involving supernumerary teeth are often a challenge. This report describes a case of unilateral fusion of a supernumerary tooth to a maxillary permanent lateral incisor in which a conservative approach was used to reach a favorable outcome.

Fused and Geminated Permanent Maxillary Central Incisors: Prevalence, Treatment Options, and Outcome in Orthodontic Patients.

PURPOSE: Developmental disturbances during tooth formation may cause abnormalities in tooth size and shape, resulting in poor dental and facial esthetics. The purpose of this study was to evaluate the prevalence of fused/geminated teeth in the maxillary anterior region of orthodontically treated patients, and present treatment options and their outcome. METHODS: Pre- and post-treatment facial and intraoral photographs, study models, and panoramic and periapical radiographs of 574 consecutively treated patients (mean age: 13.3 years) from the orthodontic department were examined for the presence of fusion or gemination in the maxillary anterior region. RESULTS: There were eight patients (1.4 percent) with fused/geminated teeth in the maxillary anterior region. CONCLUSIONS: The prevalence found is relatively high compared to previous reports. Esthetic consideration is a determining factor for various treatment alternatives. A multidisciplinary approach is imperative for the successful treatment of these dental abnormalities.

Concrescence: assessment of case by periapical radiography, cone beam computed tomography and micro-computed tomography.

The aim of this article was to describe imaging aspects of concrescence analyzed by three imaging modalities. A second molar joined together with a third molar was imaged using digital periapical radiography, cone beam computed tomography (CBCT) and micro-computed tomography (Micro-CT). On periapical radiograph, the mesial root of the third molar is superimposed on the distal root of the second molar. On CBCT images, a large cementum union between bulbous roots was detected, confirming the diagnosis of concrescence. On micro-CT images, the cementum union appeared limited to the apical third of the roots. In conclusion, both computed tomography modalities allowed for the diagnosis of concrescence. However, only micro-CT provided the real extension of the cementum union.