Similar locations of impacted and supernumerary teeth in monozygotic twins: a report of 2 cases

Prevalence of Impacted Teeth: A Radiographical Retrospective Rio de Janeiro Population-Based Study

Background

The early detection of impacted teeth is essential for the prevention of future malocclusions and possible lesions. The aim of this study is to assess the prevalence of impacted teeth and associated pathological lesions.

Methods

One thousand six hundred and two panoramic radiographs were analyzed for this retrospective study. The prevalence of impacted teeth, the presence of supernumerary teeth and cystic or tumoral lesions associated, and the type of angulation of third molars using Winter's classification were accessed. The descriptive statistics and the Chi-squared test were performed (P < 0.05).

Results

One thousand three hundred and ninety-seven panoramic radiographs fulfilled impacted criteria. A prevalence of 541 (38.7%) impacted teeth was observed, with the female gender significantly higher (P < 000.1). Of the total impacted teeth (n = 541), the overall mean impacted of lower third molars was 55.6%. Twenty-nine (5.3%) supernumerary teeth and four lesions were verified. The angulations most observed in the upper (76.6%) and lower (39.2%) third molars were vertical (P < 000.1) and mesioangulated (P < 000.1), respectively.

Conclusion

The impacted tooth prevalence was 38.7%, more common in females than in males. The lower third molars presented the highest prevalence of impacted, and the most common angulations were vertical and mesioangulated. Only four associated lesions were observed.

Rare Variants in LRP4 Are Associated with Mesiodens, Root Maldevelopment, and Oral Exostoses in Humans

BACKGROUND

Low density lipoprotein receptor-related protein 4 (LRP4; MIM 604270) modulates WNT/β-catenin signaling, through its binding of WNT ligands, and to co-receptors LRP5/6, and WNT inhibitors DKK1, SOSTDC1, and SOST. LRP4 binds to SOSTDC1 and WNT proteins establishing a negative feedback loop between Wnt/β-catenin, Bmp, and Shh signaling during the bud and cap stages of tooth development. Consistent with a critical role for this complex in developing teeth, mice lacking Lrp4 or Sostdc1 have multiple dental anomalies including supernumerary incisors and molars. However, there is limited evidence supporting variants in LRP4 in human dental pathologies.

METHODS

We clinically, radiographically, and molecularly investigated 94 Thai patients with mesiodens. Lrp4 mutant mice were generated in order to study the effects of aberrant Lrp4 expression in mice.

RESULTS

Whole exome and Sanger sequencing identified three extremely rare variants (c.4154A>G, p.Asn1385Ser; c.3940G>A, p.Gly1314Ser; and c.448G>A, p.Asp150Asn) in LRP4 in seven patients with mesiodens. Two patients had oral exostoses and two patients had root maldevelopments. Supernumerary incisors were observed in Lrp4 mutant mice.

CONCLUSIONS

Our study implicates heterozygous genetic variants in LRP4 as contributing factors in the presentation of mesiodens, root maldevelopments, and oral exostoses, possibly as a result of altered WNT/β-catenin-BMP-SHH signaling.

Does craniofacial morphology affect third molars impaction? Results from a population-based study in northeastern Germany

Objectives

It is still not clear why impaction of third molars occurs. Craniofacial morphology and facial parameters have been discussed to be strong predictors for third molar impaction. Thus, this study aimed to investigate the effect of craniofacial morphology on erupted or impacted third molars in a German population sample.

Materials and methods

Erupted and impacted third molars in 2,484 participants from the Study of Health in Pomerania were assessed by whole-body magnetic resonance imaging. Markers of facial morphology were determined in 619 individuals of those participants in whose 421 participants (16.7%) had at least one impacted third molar. Craniofacial morphology was estimated as linear measurements and was associated in a cross-sectional study design with impacted and erupted third molars by multinomial logistic regression models. Erupted third molars were used as reference outcome category and regression models were adjusted for age and sex.

Results

Maximum Cranial Width (Eurion-Eurion distance) was significantly associated with impacted third molars (RR: 1.079; 95% confidence interval 1.028–1.132). This association was even more pronounced in the mandible. Individuals with a lower total anterior facial height (Nasion-Menton distance) and a lower facial index also have an increased risk for impacted third molars in the mandible (RR 0.953; 95% confidence interval 0.913–0.996 and RR: 0.943; 95% confidence interval 0.894–0.995). No significant associations of third molar status with facial width (Zygion-Zygion distance), and sagittal cranial dimension (Nasion-Sella distance; Sella-Basion distance) were observed.

Conclusion

Individuals with an increased maximal cranial width have a higher risk for impaction of third molars in the mandible and in the maxilla. Individuals with a lower anterior total anterior facial height and lower facial index also have an increased risk for third molars impaction in the mandible. These findings could help orthodontic dentists, oral surgeons and oral and maxillofacial surgeons in decision-making for third molars removal in their treatment. These findings highlight the necessity of an additional analysis of the maximal cranial width by the Eurion- Eurion distance.

Predictors of Third Molar Impaction

The objective of this meta-analysis was to evaluate the prevalence of third molar (M3) impaction worldwide in individuals ≥17 y, from either sex, who had undergone oral radiography and presented with no orofacial syndromes or defects. We performed a literature search using PubMed, ISI Web of Science, and Google Scholar and retrieved English and non-English articles from any period for review. We included studies reporting M3 impaction prevalence based on radiographic examination. Risk of bias was assessed regarding individuals with craniofacial syndromes, prior extraction of permanent teeth, multiple effect size estimates, and studies conflating lack of eruption with impaction. Our search yielded 49 studies involving 83,484 individuals. Worldwide M3 impaction prevalence was found to be 24.40% (95% confidence interval [95% CI]: 18.97% to 30.80%). The odds of M3 impaction in the mandible were 57.58% (95% CI: 43.3% to 68.3%, P < 0.0001) higher than in the maxilla, but we did not detect any difference in the odds of impaction between men and women (18.62%, 95% CI: –4.9% to 48.0%, P = 0.12). Mesioangular impaction was most common (41.17%, 95% CI: 33.8% to 49.0%), followed by vertical (25.55%, 95% CI: 20.0% to 32.0%), distoangular (12.17%, 95% CI: 9.1% to 16.0%), and horizontal (11.06%, 95% CI: 8.3% to 14.6%). Impaction of 1 (42.71%, 95% CI: 30.0% to 56.5%) or 2 (29.64%, 95% CI: 19.5% to 42.3%) M3s was much more common than 3 (12.04%, 95% CI: 7.2% to 19.3%) or 4 (8.74%, 95% CI: 5.2% to 14.5%). There were small differences among impaction prevalence depending on geographic region ( F test, P = 0.049). Selection bias was evident because individuals had to undergo radiographic examination to be included in the analysis. The subgroup analysis by sex was underpowered. Worldwide M3 impaction prevalence is lower than previously reported. The percentage of individuals with impacted M3s is much smaller than the percentage that undergoes clinical treatment for M3 problems.

Mirror imaging of impacted and supernumerary teeth in dizygotic twins: A case report

Background: Mesiodens is the most common type of supernumerary tooth found in the premaxilla. It might be discovered by the clinical examination by chance on a radiograph or as the cause of an unerupted maxillary central incisor. The genetic transmission of supernumerary and impacted teeth is poorly understood. Mirror imaging in twins has been reported frequently in relation to several unilateral dental anomalies including mesiodens. This phenomenon is the appearance of an asymmetrical feature or anomaly occurring on the right side of one twin but on the left side of the other twin. The event of mesiodens mirror imaging in monozygotic twins has been described in literature. Results: This is the first reported case of mesiodens mirror images in dizygotic twins. The de-scribed mesiodens caused the eruption failure of maxillary permanent incisors. The super-numerary teeth were removed to facilitate the spontaneous eruption of the impacted perma-nent maxillary incisors. Clinical Implications: Studies related to supernumerary teeth can be useful to clinicians in the early diagnosis of this anomaly. Clinical and radiographic examinations provide a correct therapeutic approach.

Key words:Supernumerary teeth, twins, dental development.

Odontomas and supernumerary teeth: is there a common origin?

The aim of the present work is to analyze all scientific evidence to verify whether similarities supporting a unified explanation for odontomas and supernumerary teeth exist. A literature search was first conducted for epidemiologic studies indexed by PubMed, to verify their worldwide incidence. The analysis of the literature data shows some interesting similarities between odontomas and supernumerary teeth concerning their topographic distribution and pathologic manifestations. There is also some indication of common genetic and immuno-histochemical factors. Although from a nosological point of view, odontomas and supernumeraries are classified as distinct entities, they seem to be the expression of the same pathologic process, either malformative or hamartomatous.

Twins and the paradox of dental-age estimations: a caution for researchers and clinicians

The biological age difference among twins is frequently an issue in studies of genetic influence on various dental features, particularly dental development. The timing of dental development is a crucial issue also for many clinicians and researchers. The aim of this study was therefore to verify within groups of twins how dental development differs, by applying Demirjian's method, Mincer's charts of development of third molars and two of Cameriere's methods for dental age estimation, which are among the most popular methods both in the clinical and the forensic scenario. The sample consisted of 64 twin pairs: 21 monozygotic, 30 dizygotic same-sex and 13 dizygotic opposite-sex with an age range between 5.8 and 22.6 years. Dental age was determined from radiographs using the mentioned methods. Results showed that dental age of monozygotic twins is not identical even if they share all their genes. The mean intra-pair difference of monozygotic pairs was low and similar to the difference in dizygotic same-sex twins; the maximum difference between monozygotic twins, however, was surprisingly large (nearly two years). This should lead to some circumspection in the interpretation of systematic estimations of dental age both in the clinical and forensic scenario.

Aetiology of supernumerary teeth: a literature review

BACKGROUND

Supernumerary teeth are teeth, or tooth-like structures that have either erupted or remain unerupted in addition to the 20 primary and 32 permanent teeth.

AIMS

This paper attempts to (a) provide an overview of the proposed hypotheses and the current understanding of the aetiology of supernumerary teeth, and (b) review the published cases of supernumerary teeth occurring in families.

REVIEW

No studies have been able to distinguish between different aetiologies for the different locations of supernumerary teeth, while, from a developmental or molecular perspective, the proposed hypotheses may be plausible and explains the origin of different types of supernumerary teeth.

CONCLUSION

The only clearly evident feature, based on the existing published reports, is that it is logical to state that supernumerary teeth have a genetic component in their aetiology.

The genetic basis of dental anomalies and its relation to orthodontics

The interruption of odontogenesis by any etiological factor may result in dental anomalies. Apart from the environmental factors, the impact of genetics in dental anomalies was found to be a factor in different levels. Many authors had questioned a common genetic defect resulting in different phenotypic conditions such as absent, malformed, malposed or ectopic teeth. Because the multidisciplinary treatment of these dental anomalies such as hypodontia, impaction etc., involves orthodontic intervention, orthodontists must be aware of the etiology and possible correlative conditions with dental anomalies.

Bilateral Mesiodens in Monozygotic Twins: 3D Diagnostic and Management

Mesiodens is the most frequent type of supernumerary tooth and may occur in several forms, causing different local disorders, such as impaction of the anterior permanent teeth. High-resolution three-dimensional (3D) images have improved the diagnosis and treatment plan of patients with impacted and supernumerary teeth. The purpose of this paper was to report a case of two mesiodens in monozygotic twin boys with appropriate 3D diagnostic and treatment plan.

Bilateral hamartoma of tonsils bearing ectopic teeth: a case report

Ectopic teeth presenting in bath the tonsils with hatnartomatous lesion has not been reported earlier. We present here a case of benign hamartoma of both the tonsils bearing 7 teeth in a 13 year old girl and also discuss about unusual Ectopic sites of tooth eruption as well as benign lesions of tonsil.

Nonsyndromic multiple hyperdontia in a series of 13 patients: epidemiologic and clinical considerations

BACKGROUND

The authors conducted a retrospective-casuistic study to determine the prevalence of nonsyndromic multiple hyperdontia in a sample of the population of Madrid, as well as possible complications associated with the presence of such supernumerary teeth.

METHODS

The study included a data assessment of all patients seeking dental care at a hospital's department of oral surgery across four years. The authors studied data from patients who had nonsyndromic multiple hyperdontia. We used univariate and bivariate analysis to make comparisions between variables.

RESULTS

The authors identified nonsyndromic multiple hyperdontia in the records of 13 patients (0.1 percent) of the total population studied. These patients had 55 supernumerary teeth. Premolars were the most frequently seen type of supernumerary tooth and constituted 45.5 percent of the sample.

CONCLUSIONS

Nonsyndromic multiple hyperdontia usually is diagnosed as a coincidental radiographic finding in the course of routine examination rather than as the result of an associated disease. However, the authors found a higher percentage of comorbidity than they initially expected; mechanical or obstructive pathology was associated with 20.0 percent of the supernumerary teeth and enlargement of the follicular sac of more than 3 millimeters was present in 23.6 percent of the sample.

CLINICAL IMPLICATIONS

The early diagnosis and follow-up of patients with multiple supernumerary teeth should help clinicians prevent the diseases associated with this kind of hyperodontia.

Genetic basis of non-syndromic anomalies of human tooth number

Teeth organogenesis develops through a well-ordered series of inductive events involving genes and BMP, FGF, SHH and WNT represent the main signalling pathways that regulate epithelial-mesenchymal interactions. Moreover, progress in genetics and molecular biology indicates that more than 300 genes are involved in different phases of teeth development. Mutations in genes involved in odontogenesis are responsible for many dental anomalies, including a number of dental anomalies that can be associated with other systemic skeletal or organic manifestations (syndromic dental anomalies) or not (non-syndromic dental anomalies). The knowledge of the genetic development mechanisms of the latter is of major interest. Understanding the mechanisms of pathogenesis of non-syndromic teeth anomalies would also clarify the role of teeth in craniofacial development, and this would represent an important contribution to the diagnosis, treatment and prognosis of congenital malformations, and the eventual association to other severe diseases. Future research in this area is likely to lead to the development of tests for doctors to formulate an early diagnosis of these anomalies.

Identical unerupted maxillary incisors in monozygotic twins

Mesiodens is the most common type of supernumerary tooth found in the premaxilla. It might be discovered by the orthodontist by chance on a radiograph or as the cause of an unerupted maxillary central incisor. The genetic transmission of supernumerary and impacted teeth is poorly understood. The occurrence of identical unerupted maxillary central incisors and mesiodentes in monozygotic twins suggests that genetic factors might influence the etiology of this problem. In this case report, we discuss the treatment of unerupted maxillary permanent incisors caused by mesiodentes in monozygotic twins.

Multiple supernumerary premolars in two siblings: a case report

The presence of three or more supernumerary teeth in one patient is uncommon. Genetic as well as environmental causes have been suggested as possible aetiological factors in the pathogenesis of supernumerary teeth. This report describes the dental findings and management of multiple supernumerary premolars in two siblings. The number and locations of the supernumeraries in both cases were almost identical. The findings from these cases give further support to the important role of genetic factors in the aetiology of supernumerary teeth. Primary care dentists who treat children should be aware of the possibility of familial occurrence of supernumerary teeth.

Impacted maxillary central incisor, canine, and second molar with 2 supernumerary teeth and an odontoma

This report describes the orthodontic treatment of a 14-year-old boy who had 3 impacted maxillary teeth (right canine, left central incisor, and left second molar), 2 supernumerary teeth, and an odontoma. The treatment protocol involved surgical intervention followed by sequential traction of the 3 impacted teeth. The patient's smile dramatically improved after orthodontic treatment. Good posterior occlusion was achieved. However, long-term monitoring of the stability and periodontal health is critical.

Posttraumatic impaction of both maxillary central incisors

Dental impactions are one of the problems orthodontists see that will usually require surgery along with orthodontic treatment. In most cases, a single tooth is impacted, and a single surgical procedure is performed. We present a case of posttraumatic bilateral impaction of both maxillary central incisors with complete inversion after combined 2-step surgery and orthodontic treatment.