Rare Germline Variants in the Adenomatous Polyposis Coli Gene Associated with Dental and Osseous Anomalies.

APC is a tumor suppressor gene that exerts its effect through the regulation of the Wnt signaling pathway. Loss of function mutations of the gene are associated with familial adenomatous polyposis (FAP). Early diagnosis in FAP patients is essential to prevent the development of colorectal cancer. Extraintestinal manifestations often precede the formation of the polyposis; therefore, these manifestations may serve as a clinical indicator for the condition. The aim of this study was to assess genotype-phenotype associations between the location of APC mutations and various extraintestinal features, mainly focusing on osseous and dental anomalies. Analyses of our cases and the mutations available in the literature with these manifestations revealed that mutations in the N-terminal region (amino acids 1-~1000) of the protein are more frequently associated with only osseous anomalies, whereas dental manifestations are more prevalent in mutations in the middle region (amino acids 1000-~2100). In addition, supernumerary teeth were found to be the most common dental feature. Since dental abnormalities often precede intestinal polyposis, dentists have a crucial role in the early identification of patients at risk.

Three-dimensional evaluation of dental characteristics in patients with Cleidocranial dysplasia.

BACKGROUND: Cleidocranial dysplasia (CCD) is an autosomal dominant hereditary disorder. Besides skeletal abnormalities, CCD is often associated with dental complications, such as multiple supernumerary teeth and permanent teeth impaction or delayed eruption. METHODS: Supernumerary teeth of axial, sagittal and coronal CBCT view was characterized in detail and 3D image reconstruction was performed. Number and location of teeth, morphology of supernumerary teeth, positional relationship between supernumerary and adjacent permanent teeth, direction of supernumerary teeth in CCD patients were analyzed. RESULTS: The mean age of the 3 CCD patients in this study was 16.7 years. Among 36 supernumerary teeth, the majority of them were identified as apical side located and lingual side located. Normal orientation was the most common type in this study, followed by sagittal orientation, and horizontal orientation. Horizontal orientation teeth were all distributed in the mandible. Supernumerary teeth exhibited significantly shorter crown and dental-root lengths, as well as smaller crown mesiodistal and buccolingual diameters (P < 0.01). There was no difference in the number of supernumerary teeth between the maxilla and mandible, and the premolars region had the largest number of supernumerary teeth and the incisor region had the smallest number. CONCLUSIONS: This study compares number and location of teeth, morphology of supernumerary teeth, positional relationship between supernumerary and adjacent permanent teeth and direction of supernumerary teeth, this study also provides a reference for the comprehensive evaluation of CCD patients before surgery.

Clinical features of non-syndromic late developing supernumerary teeth: a sign of the third dentition?

OBJECTIVES: This study aimed to summarize the clinical features of non-syndromic late developing supernumerary teeth (LDST) and comparisons with common supernumerary teeth (ST) and explore the association between LDST and the third dentition. MATERIALS AND METHODS: This study retrospected cone-beam computed tomography (CBCT) and medical history of 41,903 consecutive patients from January to December 2021. Comparisons between ST and LDST were evaluated by Chi-square test or Fisher exact test. Correlation between chronological age and dental stage age was evaluated by Spearman's rank correlation coefficient. Binary logistic regression analysis was used to explore the features of LDST originating from the third dentition. RESULTS: Sixty patients with 126 non-syndromic LDST and 1602 patients with 1988 non-syndromic ST were identified. The prevalence of ST and LDST was 3.82% and 0.14%, respectively, with a male-female ratio of 1.78:1 and 1.31:1. LDST patients mainly had LDST in multiple (58.33%) and bilaterally (41.67%), with an average of 2.1/patient. Most LDST were normal-shaped (84.13%), vertically oriented (71.43%), located in the mandible (80.16%), and distributed in the premolar region (82.54%). The study also indicated that the development of LDST was correlated with permanent teeth, with LDST developing 6.48 to 10.45 years later. In this study, 72.22% of LDST met the clinical criteria for the third dentition. CONCLUSIONS: LDST manifested different clinical features from common ST. LDST might be closely related to the third dentition. CLINICAL RELEVANCE: This work would help to comprehend LDST from a clinical perspective, and may be complementary to the criteria of the third dentition.

Prevalence of tooth agenesis and supernumerary teeth related to different Thai cleft lip and cleft palate populations.

BACKGROUND: Pattern of dental anomalies encountered in cleft patients shows subtle signs of genetic involvement. This study aimed to evaluate the prevalence and pattern of tooth agenesis and supernumerary teeth in Thai cleft population according to the cleft type. METHODS: Data collected from patients with cleft lip and palate, who had been treated at Tawanchai Cleft Center, Khon Kaen University, Thailand, available during year 2012-2022, were investigated. Records from 194 patients with non-syndromic clefts met the inclusion criteria. Standard dental records, and at least either orthopantomogram (OPG) or cone beam computed tomography (CBCT), were examined. Statistical analysis was performed using chi-square and binominal test (p ≤ 0.05). RESULTS: Prevalence of tooth agenesis was higher (77.3%) than that of supernumerary teeth (5.7%) and was more common in bilateral cleft lip and palate (BCLP) (88.1%) than in unilateral cleft lip and palate (UCLP) (72.6%) (p = 0.017). The upper lateral incisor was more frequently affected (46.4%), followed by the upper second premolar. The number of missing teeth observed on the left side was significantly higher. Patients with left UCLP (ULCLP) had the highest prevalence of tooth agenesis. A total of 41 tooth agenesis code (TAC) patterns was found. The prevalence of supernumerary teeth was comparable with 6.6% of ULCLP, 5.1% of BCLP, and 4.5% of URCLP. Tooth-number anomalies were observed more often in the BCLP and were most likely to occur on the left side of the maxilla. Both types of anomalies could be featured in a small proportion of cleft patients. CONCLUSIONS: More than half of the patients with non-syndromic cleft lip and palate in this study, presented with tooth-number anomalies. Tooth agenesis was approximately 10-time more prevalent than supernumerary teeth. Tooth agenesis was likely to appear on the left-side of the maxilla regardless of the laterality of the cleft.

Late-forming supernumerary teeth: A case series.

The aim of this case series was to illustrate the development of late-forming supernumerary teeth (LFST) and highlight the implications for orthodontic treatment. There are limited studies relating to the aetiology, prevalence and treatment of LFST and the cases presented here demonstrate the management of LFST within a tertiary care centre. Five cases are presented, which show various presentations and chronological ages in the development of LFST. This case series emphasises the significance of maintaining a low threshold for suspecting LFST in patients where supernumerary teeth have previously been identified. It also highlights the importance of regular clinical and radiographic reviews. Timely identification can help prevent complications and optimise treatment outcomes.

Minimally invasive surgical removal of bilateral impacted mandibular supernumerary teeth using 3D surgical guide template: a case report.

Impacted supernumerary teeth are defined as the presence of one or more teeth in a patient's upper and lower jaws in addition to the normal number of teeth in the dental arch. It has an incidence rate of approximately 1%-14% and more frequently occurs in males than females, may be single or multiple, unilateral or bilateral, erupted or impacted. In this article, we describe the case of a patient with two supernumerary teeth between the roots of the mandibular second premolar and the first molar, which influenced the effectiveness of the first orthodontic treatment. The special anatomical position of the complex supernumerary teeth made tooth extraction challenging. Given the higher risk status of surgery, we implemented a novel tooth extracting technique for this patient. Thus, in this study, we describe a case of minimally invasive extraction of bilateral mandibular impacted supernumerary teeth using a digital 3D positioning guide plate.

A clinical study of the piezosurgery, high-speed contra-angle handpiece, and the combined application of both for extraction of embedded supernumerary teeth.

OBJECTIVES: To compare the effectiveness of three methods: high-speed contra-angle handpiece (HSCAH), piezosurgery, and combined in the extraction of different locations and types of embedded supernumerary teeth. METHODS: Sixty cases with different locations and different types of embedded supernumerary teeth were randomly divided into three groups for extraction by HSCAH, piezosurgery, and the combination of both, and the intraoperative and postoperative conditions of the three groups were compared and analyzed. RESULTS: In the extraction of embedded supernumerary teeth in the inverted, horizontal, and root tip positions, the piezosurgery group required significantly longer operative time and reduced intraoperative bleeding compared with the HSCAH and the piezosurgery combined with the HSCAH; it could effectively relieve postoperative pain and facial swelling. In the extraction of oblique, orthodontic, middle, and crown segments of embedded supernumerary teeth, the use of a piezosurgery combined with an HSCAH can effectively reduce the operative time, while the factors of bleeding, postoperative pain, and facial swelling not statistically significant when compared with a piezosurgery. Compared with the HSCAH and combined piezosurgery, piezosurgery can significantly reduce the fear of patients. CONCLUSION: Piezosurgery is effective in extracting embedded supernumerary teeth in inverted, horizontal, and apical positions, effectively reducing intraoperative and postoperative trauma and shortening the time required for healing. The piezosurgery combined with an HSCAH can effectively reduce intraoperative and postoperative trauma when extracting embedded supernumerary teeth in oblique, orthodontic, middle, and crown positions. piezosurgery is a technique suitable for the treatment of patients with fear.

Nance-Horan Syndrome: characterization of dental, clinical and molecular features in three new families.

BACKGROUND: Nance-Horan syndrome (NHS; MIM 302,350) is an extremely rare X-linked dominant disease characterized by ocular and dental anomalies, intellectual disability, and facial dysmorphic features. CASE PRESENTATION: We report on five affected males and three carrier females from three unrelated NHS families. In Family 1, index (P1) showing bilateral cataracts, iris heterochromia, microcornea, mild intellectual disability, and dental findings including Hutchinson incisors, supernumerary teeth, bud-shaped molars received clinical diagnosis of NHS and targeted NHS gene sequencing revealed a novel pathogenic variant, c.2416 C > T; p.(Gln806*). In Family 2, index (P2) presenting with global developmental delay, microphthalmia, cataracts, and ventricular septal defect underwent SNP array testing and a novel deletion encompassing 22 genes including the NHS gene was detected. In Family 3, two half-brothers (P3 and P4) and maternal uncle (P5) had congenital cataracts and mild to moderate intellectual deficiency. P3 also had autistic and psychobehavioral features. Dental findings included notched incisors, bud-shaped permanent molars, and supernumerary molars. Duo-WES analysis on half-brothers showed a hemizygous novel deletion, c.1867delC; p.(Gln623ArgfsTer26). CONCLUSIONS: Dental professionals can be the first-line specialists involved in the diagnosis of NHS due to its distinct dental findings. Our findings broaden the spectrum of genetic etiopathogenesis associated with NHS and aim to raise awareness among dental professionals.

Determination of the range of intervention timing for supernumerary teeth using the Korean health insurance review and assessment service database.

This study aimed to identify the frequency of complications during the diagnosis, observation, and treatment of supernumerary teeth or odontomas and evaluate the relationship between complications and the timing of surgical intervention. This study was conducted based on data from the Korea Health Insurance Review and Assessment Service between January 2008 and December 2019. A 2-year washout period was applied, and a follow-up period of at least 2 years was also included. During the observation period, the age at diagnosis of supernumerary teeth and odontomas was analyzed using major diagnostic codes, and the treatment codes were used to determine the interval between diagnosis and surgical intervention. The incidence rates of supernumerary teeth (1.21%) and odontomas (0.36%) were comparable to that reported in previous studies. The frequency of supernumerary teeth was the highest in the anterior region, followed by the premolar and molar regions. The average ages at diagnosis according to the location of the supernumerary teeth were 7.25, 13.98, and 16.11 years in the anterior, premolar, and molar regions, respectively. The age at diagnosis correlated with the maturity period of the teeth at the corresponding location. For the supernumerary tooth group, surgical intervention was more likely to occur when malocclusion (p < 0.0001) or tooth eruption disturbances (p < 0.0001) were present or dentigerous cysts were absent (p = 0.006). For the odontoma group, malocclusion (p = 0.251) was not correlated with surgical intervention. When tooth eruption disturbances (p = 0.002) and dentigerous cysts (p < 0.0001) were present, surgical intervention was more likely to occur. Pediatric dentists should conduct timely clinical checks and periodic follow-ups to prevent complications and unnecessary orthodontic treatments in patients with supernumerary teeth or odontomas.

The Prevalence and Morphology of Supernumerary Teeth in Children With Nonsyndromic Cleft Lip and Palate.

INTRODUCTION: Cleft lip with or without cleft palate (CL/P) is congenital deformity associated with hyperdontia. OBJECTIVE: To determine the prevalence and characteristics of supernumerary teeth in patients with CL/P. DESIGN: Retrospective descriptive and correlation clinical study. PATIENTS: One hundred thirteen children with cleft (age ranged 9.3-19.2; 67 males and 46 females) treated in Clinic of Congenital Facial Deformities Medical University of Lublin were included in the study. METHODS: Records evaluation was conducted regarding age, gender, cleft type (Q36, Q37-International Classification of Diseases 10th revision), cleft side, and incidence of supernumeraries. In all supernumerary teeth, size, shape, and developmental degree were analyzed and correlation between the incidence of hyperdontia with different variables was checked. Correlations were detected using chi-square and the Yates correction. RESULTS: The majority of the examined group were males-59.29% with Q37 (67.26%) and the cleft on the left side (62.83%). Hyperdontia was noted in 26.55%. Only upper lateral incisors were affected. They usually had atypical shape (56.67%), reduced size (83.33%), and delayed development (56.67%). CONCLUSIONS: The prevalence of supernumerary permanent teeth in patients with cleft was higher than in the general population. Anomaly was more frequent in male patients and occurred mainly on the cleft side. The severity of the cleft did not influenced the frequency of supernumerary teeth, their shape, size, and developmental degree. Supernumerary teeth were characterized by reduced crown size, abnormal structure, incorrect inclination, and delayed development phase.

Detecting the presence of supernumerary teeth during the early mixed dentition stage using deep learning algorithms: A pilot study.

BACKGROUND: Supernumerary teeth are a common anomaly and are frequently observed in paediatric patients. To prevent or minimize complications, early diagnosis and treatment is ideal in children with supernumerary teeth. AIM: This study aimed to apply convolutional neural network (CNN)-based deep learning to detect the presence of supernumerary teeth in children during the early mixed dentition stage. DESIGN: Three CNN models, AlexNet, VGG16-TL, and InceptionV3-TL, were employed in this study. A total of 220 panoramic radiographs (from children aged 6 years 0 months to 9 years 6 months) including supernumerary teeth (cases, n = 120) or no anomalies (controls, n = 100) were retrospectively analyzed. The CNN performances were assessed according to accuracy, sensitivity, specificity, receiver operating characteristic (ROC) curves, and area under the ROC curves for a cross-validation test dataset. RESULTS: The VGG16-TL model had the highest performance according to accuracy, sensitivity, specificity, and area under the ROC curve, but the other models had similar performance. CONCLUSION: CNN-based deep learning is a promising approach for detecting the presence of supernumerary teeth during the early mixed dentition stage.

Assessment of risk factors and molecular biomarkers in children with supernumerary teeth: a single-center study.

BACKGROUND: Supernumerary teeth are considered one of the commonly observed dental anomalies in children. Several theories have been proposed to explain the presence of supernumerary teeth, including environmental and genetic factors. This study aimed to identify the different risk factors and molecular biomarkers in patients presented with supernumerary teeth. METHODS: This case-control study included 240 children, 6 to 12-year-old. They were divided into a test group (n = 120 children presented with supernumerary teeth) and a control group (n = 120 children with no supernumerary teeth). Questionnaires were distributed to assess demographics and exposure to several environmental factors. Ten extracted supernumerary teeth from the test group were processed for histopathological analysis. RESULTS: Male gender, dental history of severe oral infection or medical history of chemotherapy treatment, previous history of taking medication or illness during pregnancy, family history of neoplastic disorders, use of electronic devices, and living beside agricultural fields or industrial areas were found to be statistically significant associated with the risk of supernumerary teeth development. Immunohistochemistry panel revealed that supernumerary teeth showed enhanced expression of wingless (Wnt) and sonic hedgehog (SHH) proteins as well as a reduced expression of adenomatous polyposis coli (APC) protein, denoting molecular derangement in a group of pathways classically believed to be involved in its pathogenesis. CONCLUSIONS: Males were more frequently affected by supernumerary teeth than females. Several risk factors were notably correlated with the existence of supernumerary teeth. Additionally, molecular biomarkers assessment demonstrated a high expression level of pro-tumorigenic proteins such as Wnt and SHH in patients with supernumerary teeth.

Dental anomalies and their therapeutic implications: retrospective assessment of a frequent finding in patients with cleft lip and palate.

BACKGROUND: Orofacial clefts are characterized by a frequent occurrence of dental anomalies. Numerous studies demonstrate the high prevalence of dental aplasia, supernumerary teeth, and hypoplastic teeth in patients with cleft lip with/without cleft palate (CL/P), yet the therapeutic consequences are rarely discussed. This study explores prevalence, localization, and association between primary and secondary dentition in a large European collective and begins to evaluate the significance of dental anomalies in the therapeutic course of patients with CL/P. METHODS: The medical reports of 1070 patients with different entities of CL/P who presented to our clinic within a 15-year investigation period were evaluated retrospectively. Dental anomalies were classified into three different diagnostic groups: dental aplasia, supernumerary teeth and hypoplastic teeth. The statistical analyses included studies of the frequency and localization of dental anomalies in different cleft entities as well as of the association between primary and secondary dentition and the therapeutic consequences. RESULTS: Uni- or bilateral cleft lip and palate (CLP) (47.5%) occurred most frequently, followed by cleft palate only (CPO) (32.9%) and cleft lip with or without alveolus (CL ± A) (19.6%). Dental anomalies were found significantly more often on the side of the cleft. Aplastic permanent teeth were mostly found in patients with CLP (54.8%), while supernumerary permanent teeth occurred primarily in patients with CL ± A (21.7%). Patients with CPO presented dental aplasia but no patient with CPO showed supernumerary teeth. The occurrence of dental aplasia in the primary dentition significantly increases the probability of aplastic teeth in the permanent dentition. Dental anomalies, in particular dental aplasia, significantly increase patients' need for subsequent orthodontic therapy and orthognathic surgery. CONCLUSION: Dental aplasia and hypoplasia are common in patients with CL/P not only in the cleft area but in the whole dentition. In the event of dental aplasia in the primary dentition, the frequency of aplastic teeth in the permanent dentition is significantly higher. Additionally, the need for therapeutic interventions, especially concerning orthognathic surgery, seems to be significantly higher in patients with CL/P who are affected by dental anomalies. Clinicians should take this into account when creating long-term treatment plans.

Clinical, radiographic, and genetic observations in 2 families with cleidocranial dysplasia.

The clinical, radiographic, and molecular alterations in 7 individuals belonging to 2 families with clinical characteristics of cleidocranial dysplasia (CCD) were investigated. The patients underwent karyotype and genetic sequencing examinations. Cytogenetic analysis did not demonstrate any alterations. The next-generation sequencing technique employed for the molecular analysis revealed sequence variations in the RUNX2 gene: c.568C>T (p.Arg190Trp) in exon 4 in family A and c.1205del (p.Pro402Argfs*82) in exon 9 in family B. Incomplete closure of anterior fontanels, hypoplastic clavicles, and dental changes were observed in all 7 patients. Uncommon clinical findings, such as partial hearing loss and bilateral clavicular agenesis, were noted in some patients. According to the literature consulted, this is the first time that the total absence of the pubic bone in a study subject is being reported. The variable expression among individuals of the same family and between families A and B suggests the absence of a genotype-phenotype relationship. Early diagnosis allows the dentist to minimize the effects of changes associated with CCD by monitoring and providing appropriate treatment, and the identification of genetic sequence variations enables appropriate family genetic counseling.

Computer-designed surgical templates improve the extraction of impacted supernumerary teeth in the hard palate.

OBJECTIVES: The surgical procedure of bony impacted supernumerary teeth (SNT) in hard palate is commonly done with poor visualization and uncomfortable posture. This study aims to introduce our primary practice of presurgical evaluation and guiding exodontia of bony impacted supernumerary teeth (SNT) in the hard palate to reduce surgical trauma, duration and uncertainty. STUDY DESIGN: Twelve patients with impacted supernumerary teeth in hard palate were included. Intraoral scan and the three-dimensional (3D) reconstruction of the cone beam computed tomography (CBCT) file was superimposed, and virtual simulation of flap elevation and osteotomy was conducted on the rebuilt 3D model. A couple of surgical templates were designed with surgical planning software Mimics, fabricated by a 3D printer and were used to guide the extraction of the impacted SNT. RESULTS: The surgical templates fitted well to the teeth and operation site. All the impacted SNTs were accurately located and extracted without damaging the adjacent vital anatomical structures. All patients had an uneventful postoperative recovery without infection or sensory disturbance. CONCLUSIONS: The application of 3D printed surgical templates reduced trauma and increased the accuracy and predictability of surgical extraction of bony impacted SNT in hard palate. The results of this study increased the accuracy and predictability of surgical extraction of bony impacted SNT in hard palate, and reduced the surgeon's embarrassment and surgical trauma because of location difficulty.

Pattern and prevalence of dental anomalies among a paediatric population in Lagos, Nigeria.

Background: Dental anomalies are craniofacial abnormalities in the size, structure or number of the teeth. This study was conducted to assess the prevalence of dental anomalies among children aged 0-16 years attending the Paediatric Dental Clinic at the Lagos University Teaching Hospital, Lagos, Nigeria. Methods: A cross-sectional design was used and data were obtained from the dental records of the Dental Clinic from January 2014 to August 2019 by two calibrated examiners, who are co-authors of the manuscript. To test for statistical differences, Chi-squared test was utilised for the categorical variables. The prevalence of the different dental anomalies was estimated and presented with frequencies. P < 0.05 was considered statistically significant. Results: Among the 6175 patients' dental records reviewed, 50.85% (n = 3150) were male and the highest proportion of 45.4% (n = 2807) were aged between 6 and 10 years, with a mean age of 8.62 ± 3.85 years. A total of 1090 (17.52%) had dental anomalies; 465 (7.53) anomalies were in the maxilla, 263 (4.6) were in the mandible while 360 (5.83) were in both. The most common anomaly was hypoplasia 550 (9.06%), followed by retained primary tooth 546 (8.84%) and hypodontia 84 (1.36%). Dentinogenesis imperfecta 1 (0.02) and transposition 1 (0.02) were the least prevalent anomalies. Retained primary teeth (5.8%) and the cusp of Carabelli (0.4%) were slightly more prevalent among males. However, females had a higher prevalence of natal/neonatal teeth (0.4%), fusion/germination (0.4%), hypodontia (1.5%) and peg-shaped lateral incisors (0.9%). Conclusion: Dental anomalies' prevalence in this study was 17.52%, with a higher occurrence of anomalies in the maxilla. Hypoplasia was the most prevalent anomaly, after which was retained primary tooth, then hypodontia. Prompt diagnosis and preventive interventions are crucial for the appropriate management of these dental anomalies.

Epidemiological, clinical, radiographic characterization of non-syndromic supernumerary teeth in Chinese children and adolescents.

OBJECTIVE: This retrospective study was purposed to evaluate epidemiological, clinical, and 3D radiological features of supernumerary teeth (ST) in a non-syndromic Chinese children and adolescent dental population. MATERIALS AND METHODS: Original cone-beam CT (CBCT) data from 18,861 patients aged from 6 to 17 years with dental maxillofacial diseases treated in a Chinese dental hospital from June 2012 to December 2018 were utilized to screen patients with ST. Diagnosis and characterizations of ST were analyzed by CBCT coupled with 3D reconstruction. All relevant epidemiological, clinical, and radiographic details about ST were collected and statistically analyzed. RESULTS: Among total 18,861 patients, 2,768 ST were identified in 1984 subjects with a prevalence of 10.52% and a male:female ratio of 1.86:1. Majority of ST were single, conical, inverted, impacted, and located in maxilla anterior region. ST-associated complications mainly included malposition, rotation, and impaction of adjacent teeth, which were notably associated with morphology and position of ST. CONCLUSION: The prevalence of ST in Chinese children and adolescent dental population was 10.52% and tended to present as single, conical, inverted, and impacted, which resulted in abnormalities of neighboring teeth. Our outcomes are beneficial for clinicians to more comprehensively understand the incidence, characterization, and clinical treatment planning of ST in dental children and adolescents.

FAM20B-catalyzed glycosaminoglycans control murine tooth number by restricting FGFR2b signaling.

BACKGROUND: The formation of supernumerary teeth is an excellent model for studying the molecular mechanisms that control stem/progenitor cell homeostasis needed to generate a renewable source of replacement cells and tissues. Although multiple growth factors and transcriptional factors have been associated with supernumerary tooth formation, the regulatory inputs of extracellular matrix in this regenerative process remains poorly understood. RESULTS: In this study, we present evidence that disrupting glycosaminoglycans (GAGs) in the dental epithelium of mice by inactivating FAM20B, a xylose kinase essential for GAG assembly, leads to supernumerary tooth formation in a pattern reminiscent of replacement teeth. The dental epithelial GAGs confine murine tooth number by restricting the homeostasis of Sox2(+) dental epithelial stem/progenitor cells in a non-autonomous manner. FAM20B-catalyzed GAGs regulate the cell fate of dental lamina by restricting FGFR2b signaling at the initial stage of tooth development to maintain a subtle balance between the renewal and differentiation of Sox2(+) cells. At the later cap stage, WNT signaling functions as a relay cue to facilitate the supernumerary tooth formation. CONCLUSIONS: The novel mechanism we have characterized through which GAGs control the tooth number in mice may also be more broadly relevant for potentiating signaling interactions in other tissues during development and tissue homeostasis.

Application of a surgical guide in the extraction of impacted mesiodentes: a randomized controlled trial.

OBJECTIVE: To explore and evaluate the application of a surgical guide in the extraction of impacted mesiodentes. MATERIALS AND METHODS: Patients with impacted mesiodentes approachable from the labial side of the maxilla were randomly divided into three groups. The surgical guide for group I was made using cone beam computed tomography (CBCT) and dental cast, whereas the surgical guide for group II was only made using CBCT data. Group I and group II were first evaluated to determine whether guide use could accurately locate the cementoenamel junction (CEJ) of the mesiodentes, and the impacted mesiodentes were extracted with the help of the surgical guide. Group III underwent an operation without a guide. For all patients, the preoperative design time, tooth searching time, operation time, complications, and costs were measured. RESULTS: The guides for group I and group II could locate the CEJ of the mesiodentes accurately, with good application effect during the operation. Group I and group II required additional preoperative design time compared with group III. However, the tooth searching time and operation time in groups I and II were significantly reduced compared with those in group III. Group I and group II showed no intraoperative complications, and two cases in group III showed imprecision during localization. The overall cost for group III was higher than that of group I or group II. But group I and group II required extra visits and costs. CONCLUSIONS: Despite some limitations, the surgical guide assisted with mesiodentes extraction and can improve the quality of the operation quality as well as reducing its economic burden, difficulty, and duration. Through proper design, we can create a high-quality surgical guide using only CBCT data. CLINICAL RELEVANCE: The surgical guide can be used as an important assistive tool in alveolar surgery.

Prevalence of hypodontia and supernumerary teeth in a German cleft lip with/without palate population.

BACKGROUND: The distribution of dental abnormalities among cleft patients concerning cleft type frequently poses ambiguity wherefore the aim of this study was to evaluate the prevalence of hypodontia and supernumerary teeth in an exemplary German cleft population dependent on the cleft type. METHODS: Radiographs and dental records of cleft patients, which had been treated and followed up in the Department of Oral and Maxillofacial Surgery, University Hospital Carl Gustav Carus Campus, Dresden, Germany (investigation period of 22 years) were evaluated concerning hypodontia and supernumerary teeth dependent on the cleft type. Out of 386 records, 108 patients met the inclusion criteria: non-syndromic cleft of the alveolus with or without palate (CL/P), at least one clear panoramic x-ray, sufficient dental records. Statistical analysis was performed using x-square and binominal test (p ≤ 0.05). RESULTS: Hypodontia was more frequent (54/50%) than supernumerary teeth (36/33.3%) and was more common in bilateral clefts of the lip and palate (BCLP) (70.1%) than in unilateral clefts of the lip and palate (UCLP) (51.6%) or clefts of the lip and alveolus (CLA) (34.5%) (p << 0.001). There was an average of 0.9 missing teeth per patient, thereof the upper lateral incisor was most often affected (23.2%). In contrast, supernumerary teeth were more frequent in CLA (51.7%; p = 0.014) than UCLP (29.0%) and BCLP patients (17.6%). CONCLUSION: The prevalence for numerical dental anomalies was significantly different among the cleft types. Hypodontia significantly increased with the extend of the cleft, whereas the prevalence of supernumerary teeth decreased.