Impacted Mandibular "Double" Third Molar: Fusion or Gemination? A Case Report.

Dental fusion is defined as an abnormality in tooth shape caused by developmental tooth disturbances that produce an intimate union of dental tissues. This case report discusses treatment of a mandibular impacted "double" third molar in a 21-year-old patient that could have been related to either gemination or tooth fusion. Radiological examination allowed for careful analysis of the tooth's shape and root development, relation to the inferior alveolar nerve, and 3-dimensional position. After evaluation of therapeutic options and risks, and with the patient's consent, the authors opted to extract the tooth in question. Such favorable conditions as the incomplete development of the roots and the relatively young age of the patient, combined with the use of an antibiotic and antiseptic prophylaxis as well as a standard surgical approach, enabled a successful result to be achieved with no related complications.

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.

Impact of manual toothbrush design on plaque removal efficacy.

BACKGROUND: Effective dental plaque removal is essential for oral health. Different toothbrush parameters including head-size, filament-diameter and interdent-height and different brushing movements like horizontal, rotating and vertical may affect plaque removal efficacy. The purpose of the study was to examine plaque removal efficacy of different design parameters of manual toothbrushes. METHODS: Eight manual toothbrushes were tested using a validated robot test to examine efficacy of toothbrush on replicated human teeth. Characteristics tested were: (i) head-size, (ii) filament-diameter, (iii) cutting-height, (iv) hardness, (v) interdental-height. Each test ran five times in horizontal, rotating, vertical movements. Simulated Plaque removal was evaluated using automated plaque planimetry: 30 fields/tooth, 13 areas representing buccal, lingual, proximal tooth sites. The Kolmogorov-Smirnov-test was applied to test tooth surface variables for normal distribution of plaque removal values. Parameters were analysed by independent two-sample t-test to assess mean differences. Where null hypothesis of normality was rejected, the Wilcoxon-Mann-Whitney-U-test was used. RESULTS: Plaque removal was significantly better with toothbrush having smaller head-size (compact vs. full-size); smaller filament-diameter (0.12 mm vs. 0.15 mm); larger cutting-height (12 mm vs. 9 mm); softer filaments (0.15 or 0.18 mm vs. 0.23 mm) and greater interdent-height difference (8.5/11 mm vs. 10/11 mm). CONCLUSIONS: Manual brushes allowing filaments free to flex with longer, softer and/or having a difference in filament length overall removed significantly more simulated plaque as compared to more standard flat trim, stiff brushes with shorter, harder bristles and a larger head size. While limited by the in vitro nature of the study design, this indicates that the advances in toothbrush design can further enhance plaque removal.

Conservative management of double teeth in molar teeth with pulp or periapical disease: a report of five cases and literature review.

BACKGROUND: Double teeth are usually the result of an abnormality in the developing tooth germ. Double teeth can occur in either the primary or permanent dentition, with the majority of cases concerning permanent teeth reported in the anterior teeth and less frequently in the molar teeth. CASE PRESENTATION: This report illustrates five cases of double teeth in molars with pulp and periapical disease, including one case of geminated teeth and four cases of fused teeth. Radiographic findings revealed the presence of extra teeth on the buccal aspect of the molar in five cases, with or without communication between the two root canal systems. Root canal treatment was performed by using CBCT and a dental operating microscope. The treatment outcome was good in all five cases. CONCLUSION: The diagnosis and treatment of double teeth requires special attention. The root canal system should be carefully explored to obtain a full understanding of the anatomy, allowing it to be fully cleaned and obturated. Proper anatomical structure analysis prior to treatment facilitates the development of an appropriate treatment plan, thereby increasing the likelihood of successful treatment both aesthetically and functionally.

Analysis of congenital deciduous teeth absence and its permanent teeth phenotype.

OBJECTIVES: This study aimed to investigate the clinical characteristics of congenital deciduous teeth absence and its permanent teeth performance type by using panoramic radiographs. METHODS: A total of 15 749 panora-mic radiographs of 3-6-year-old children with deciduous dentition were collected from January 2020 to December 2021. The incidence of congenital deciduous teeth absence was observed, and the abnormality of permanent teeth was recor-ded. SPSS 24.0 software was used for statistical analysis. RESULTS: The incidence of congenital deciduous teeth absence was 2.54% (400/15 749), which was found in 217 girls and 183 boys, and the difference between the genders was statistically significant (P=0.003). The absence of one and two deciduous teeth accounted for 99.75% (399/400) of the subjects. In addition, 92.63% (490/529) of mandibular deciduous lateral incisor was congenitally absent, 44.80% (237/529) of deciduous teeth was absent in the left jaw, and less than 55.20% (292/529) was absent in the right; the difference between them was statistically significant (P=0.017). The absence of 96.41% (510/529) deciduous teeth in the mandibular was significantly more than that of 3.59% (19/529) in the maxillary, and the difference between was statistically significant (P=0.000). Furthermore, 68.00% (272/400) and 32.00% (128/400) of deciduous teeth were absent in unilateral and bilateral, respectively, and the difference was statistically significant (P=0.000). Four types of congenital deciduous teeth absence with permanent teeth were observed as follows: 1) 73.91% (391/529) of permanent teeth was absent; 2) 20.60% (109/529) of permanent teeth was not absent; 3) the number of fused permanent teeth accounted for 4.91% (26/529); 4) the number of supernumerary teeth was 0.57% (3/529). CONCLUSIONS: Although the absence of congenital deciduous teeth is less common than that of permanent teeth, it affects deciduous and permanent teeth to some extent. Dentists should pay attention to trace and observe whether abnormalities are present in the permanent teeth and take timely measures to maintain children's oral health.

Macrodontia and double teeth: a review and case series.

Macrodontia is a dental anomaly pertaining to the increased size of a tooth or multiple teeth. Double teeth are dental abnormalities concerning tooth morphology and the term traditionally refers to geminated or fused teeth. These anomalies may manifest in both primary and permanent dentitions and usually become apparent in childhood. They may cause a variety of clinical sequelae, including orthodontic complications, such as crowding, ectopic eruption of adjacent teeth and periodontal concerns. Double teeth are also at a higher risk of developing caries. The aesthetic implications of these dental anomalies can affect the psychosocial development of a patient. This, together with the range of functional repercussions, can often need dental treatment to improve quality of life. The functional and aesthetic complexities that may arise in the affected patients can require endodontic, restorative, surgical and/or orthodontic input as part of the management strategy and execution. We present four clinical cases of paediatric patients where a range of management approaches were employed for both macrodontia and double teeth.

[Considerations of the classification and treatment for fused teeth].

Fused teeth were a phenomena of teeth anomalies in shape, which can affect the dental teeth both in primary and permanent dentition. Fused teeth do not only cause problems on crowding of dentition, abnormal occlusion and aesthetic, but also increase risks of dental caries, endodontics diseases, periapical diseases and periodontal diseases. Fusion of deciduous teeth may lead to abnormality of subsequent permanent teeth. Treatment of fused teeth may require multidisciplinary approach in endodontics, periodontics, oral and maxillofacial surgery, prosthodontics and orthodontics. The aim of the present article is to review the etiology, classification, clinical manifestations and treatment of fused teeth in order to provide dental clinicians with a reference of clinical management for fused teeth.

Design of customized soft tissue substitutes for anterior single-tooth and posterior double-tooth defects: An in vitro study.

OBJECTIVE: This study aims to validate the standardized procedure for designing soft tissue substitutes (STS) adapted to optimally fit single-tooth defects in the anterior jaws and double-tooth defects in the posterior jaw and to compare mathematically modeled average shapes. MATERIALS AND METHODS: Casts from 35 patients with 17 single-tooth defects in anterior region and 21 double-tooth defects in posterior region were scanned. STS were designed and sectioned in 3D slices meshes. Thickness values were documented respecting mesial-distal and buccal-lingual orientations. Graphs were embedded into images, and hierarchical clustering was applied to group STS according to shape and thickness. RESULTS: STS clustered into two groups per defect type. For anterior single defects, STS (n = 4) were either a small and thin oval: 7 mm buccal-lingual, 4-5 mm mesial-distal direction and 1.1-1.5 mm thick or a larger oval (n = 13): 9 mm buccal-lingual, 5-7 mm mesial-distal and 1.6 m thick. For posterior double tooth defects, STS (n = 10) were either narrow, long and thick: 6-7 mm buccal-lingual, 16-20 mm mesial-distal and 2.2 thick or a wide, thinner rectangle (n = 11): 9-11 mm buccal-lingual, 12-14 mm mesial-distal and 1.1-1.5 mm thick. CONCLUSIONS: The study validated the standardized digital method to design grafts for soft tissue volume augmentation and identified four average shapes for anterior single-tooth and posterior double-tooth soft tissue defects. CLINICAL SIGNIFICANCE: We developed and validated a standardized digital method to design an optimal geometrical shape of a soft tissue substitute for oral volume augmentation and combined it with mathematical modeling to identify average shapes for single-interior, and double-posterior tooth defects. The identified average shapes offer the possibility to produce better-fitted xenografts or synthetic STS blocks requiring minimal chair-side adaptation leading to reduced clinical time and patient discomfort and potentially improving soft tissue volume augmentation outcomes.

Imaging characteristics of the gubernaculum tracts in successional teeth related to deciduous fused teeth on computed tomography.

The purpose of this study was to elucidate the imaging characteristics of the gubernaculum tracts in successional teeth related to fused deciduous teeth on computed tomography. The imaging findings of 15 gubernaculum tracts in successional teeth related to fused deciduous teeth were retrospectively analyzed using cone-beam computed tomography or multidetector computed tomography. In cases without a congenitally defected successor, the two gubernaculum tracts of two successional teeth related to fused deciduous teeth were fused into one. Gubernaculum tracts (GTs) in mesial successors were vertical, but in distal successors they were inclined to mesial. The major abnormalities of the successional teeth related to fused deciduous teeth were delayed eruption and delayed formation. No inclined mesial successors were found, whereas most of the distal successors were inclined to mesial along with the inclined GT. The gubernaculum tracts of successors with a congenital defect of the other successors were vertical, and such successors had no abnormalities. The present study showed the imaging characteristics of gubernaculum tracts in successional teeth related to fused deciduous teeth. The abnormal eruption of successional teeth related to fused deciduous teeth may be associated with the characteristics of their gubernaculum tracts.

Dental pathologies in lamniform and carcharhiniform sharks with comments on the classification and homology of double tooth pathologies in vertebrates.

Double tooth pathologies are important indicators of trauma, disease, diet, and feeding biomechanics, and are widely documented in mammals. However, diagnosis of double tooth pathologies in extinct non-mammalian vertebrates is complicated by several compounding factors including: a lack of shared terminology reflecting shared etiology, inconsistencies in definitions and key features within and outside of mammals (e.g., gemination, fusion, twinning, concrescence); differences in tooth morphology, heterodonty, regeneration, and implantation between mammals and non-mammalian vertebrates; and the unmet need for diagnostic criteria that can be applied to isolated teeth, which are common in the fossil record. Here we report on double tooth pathologies in the lamniform and carcharhiniform Cenozoic sharks Otodus megalodon (NCSM 33639) and Carcharhinus leucas (NCSM 33640, 33641). All three teeth bear a singular bifid crown with mirrored halves and abnormal internal microstructure-a single, bifurcating pulp cavity in C. leucas and a more than tripling of vessels in O. megalodon (from two to seven main ascending canals). We identify these abnormalities as likely examples of gemination due to their symmetry, which rules out fusion of tooth buds in one tooth file in different developmental stages in polyphyodont taxa; however, we note that incomplete forms of mesiodistal tooth fusion can be morphologically indistinguishable from gemination, and thus fusion cannot be rejected. We further compile and recategorize, when possible, the diversity of tooth pathologies in sharks. The identification of double tooth pathologies in O. megalodon and C. leucas has paleobiological implications. Such pathologies in sharks are largely hypothesized to stem from trauma to developing tooth buds. Carcharhinus leucas is known to feed on prey documented to cause feeding-related oral traumas (e.g., rays, sawfish, spiny fish, and sea urchins). However, O. megalodon, is considered to have largely fed on marine mammals, and perhaps turtles and/or fish, raising the possibility that the dietary diversity of this species is, as of yet, underappreciated. The genetic underpinnings of tooth morphogenesis and regeneration is highly conserved throughout vertebrate evolution, suggesting a homologous framework can be established. However, more research is needed to link developmental, paleobiological, and/or paleoenvironmental factors to gemination/fusion in polyphyodont taxa. We argue that the definitions and diagnostic criteria for dental pathologies in vertebrates require standardization in order to advance macroevolutionary studies of feeding trauma in deep time.

Management of Fused Anterior Teeth: Review and Clinical Report.

The phenomenon of fusion is a type of tooth dysplasia, but few studies have systematically described the treatment of this kind of abnormality. This paper summarizes the treatment methods for fused teeth and classifies the management schemes according to whether the pulp is fused. Then, the treatment for a patient with bilateral anterior tooth fusion is reported. After orthodontic treatment, porcelain veneers were used to restore the normal shape and aesthetic appearance of the anterior teeth.

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.

Evaluation of Newly Developed Double-layer Composite Resin Teeth for Crown Preparation Training.

OBJECTIVE: To evaluate and compare the crown preparation performance of preclinical dental students training with conventional composite resin teeth and newly developed double-layer composite resin teeth. METHODS: The newly developed composite resin teeth consisted of two layers with different colours and hardnesses. Twenty third-year undergraduate dental students (8 men, 12 women) were randomly assigned to the control group (Group 1, using conventional composite resin teeth; n = 10) or the experimental group (Group 2, using double-layer composite resin teeth; n = 10) to prepare metal-ceramic crowns. To practice, each student prepared one tooth per day for 2 days. For the baseline test and final test before and after the practice period, both groups used traditional teeth. The operation time was recorded and the prepared teeth were scored blindly by two experienced instructors. The time and scores were compared within and between groups to determine the difference (α = 0.05). RESULTS: Students in both groups spent less time (P < 0.05) and achieved better scores (P < 0.001) on the final test than the baseline test (P < 0.01). In the final test, no significant difference in operating time was found between the two groups (P > 0.05), but Group 2 yielded significantly higher scores (P < 0.05). CONCLUSION: Training with the double-layer composite resin teeth enabled students to progress more quickly in terms of operating time and achieve higher scores. Use of this newly-developed tooth in crown preparation teaching practice therefore yields highly promising results.

Aesthetic correction of double tooth: simplified technique.

The aim of this study is to report aesthetic conservative treatment of double tooth anomaly. Case report: A 7.5-year-old patient presents an anomaly of the maxillary right upper central incisor with a bifid crown and an increased mesio-distal width and a central incisal notch, probably amenable to a gemination. Single tooth anesthesia and conservative enameloplasty procedure was performed, with universal adhesive and a single shade universal composite restorative material. Adhesive aesthetic restorations allow to resolve dental anomalies quickly, cheaply and asily for pediatric dentistry.

Cone beam computed tomography aided endodontic and aesthetic management of fused mandibular incisors with communicating canals.

Endodontic treatment of fused teeth needs special care and attention due to its complex anatomy. The aim of this article is to highlight the problems encountered and the strategy in treating such cases. We report a case of unilateral fusion of the left mandibular central incisor and lateral incisor, with a single pulp chamber. The single pulp chamber separates into two root canals and a large communication exists at the apical third of the root canals. This is the first time fused teeth with a large communication is reported. CBCT analysis was effective in confirming the morphological aberrations and aided in accurate planning and treatment. Chemomechanical preparation with manual dynamic irrigation coupled with passive ultrasonic activation of the irrigant and obturation with thermoplasticised gutta percha helped in successful outcome of the case.

Clinical management of fusion in primary mandibular incisors: a systematic literature review.

Objective: Dental anomalies occurring in deciduous teeth can affect the eruption of the permanent dentition and the occlusion stability. The occurrence of dental anomalies such as double teeth during the primary dentition in the daily practice might be frequent. The study aimed to qualitatively summarize the therapeutic management of double teeth in primary incisors.Material and Methods: A systematic review regarding the therapy of primary fused incisors in the mandible was performed and the obtained data were assessed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The following electronic databases were screened from 1st January, 1996 until 30th July, 2019: PubMed, Scopus, EBSCO and the archives of paediatric dental journals. The search terms were grouped in anatomic entity: (tooth OR teeth OR incisor), pathological condition: (fused OR fusion OR geminated OR double), intervention: (treatment OR intervention OR therapy OR prevention OR control OR management OR restoration), observed parameters: (primary dentition OR primary tooth OR primary teeth).Results: Ten articles met all inclusion criteria. The data disclosed the occurrence of double teeth in mandibular incisors. The main management of this clinical condition is either preventive or surgical involving the extraction of fused teeth, based on the deciduous nature of the teeth, the degree of caries and malocclusion development risk.Conclusion: An early diagnosis of dental anomalies is fundamental for the application of proper preventive strategies to avoid a potential malocclusion in permanent dentition and to maintain these teeth sound and caries-free until the eruption of the permanent dentition.

Conservative Management of Fused and Geminated Permanent Anterior Teeth.

The purpose of this case report is to present an eight-year-old patient with a permanent right central incisor that was fused with a supernumerary tooth as well as a geminated permanent left central incisor, and to describe the surgical-orthodontic-restorative management of the resultant malocclusion in the developing dentition. The fused teeth were split, mesiodistal widths of both central incisors were reduced, and the incisors were orthodontically aligned into an ideal occlusion. Both maxillary central incisors maintained vitality and normal masticatory function. We also discuss the physiological basis of the treatment plan, the clinical considerations, and how problems associated with double teeth can be managed conservatively with minimally invasive treatments for an esthetically pleasing result. (J Dent Child 2019;86(3):164-8).