Ectopia or concomitant hypohyperdontia? A case report

Odontometric evaluation of mandibular premolars with tooth shape deviation: a case-control study

OBJECTIVE

To evaluate the mean dimensions and morphologic characteristics of mandibular premolars that had mesiodistally elongated and faciolingually squeezed tooth shape deviations (MnP-TSD) and determine the population prevalence of this anomaly.

MATERIALS AND METHODS

Clinical photographs and study models were made for all new patients with MnP-TSD teeth who were seen over 20 years. The mesiodistal (MD) and faciolingual (FL) dimensions of the anomalous premolars were measured. MD/FL indices and MD × FL mm(2) occlusal crown areas were calculated and means and standard deviations were derived. Male and female means from the mandibular first and second anomalous premolars (MnP1/MnP2-TSD) were statistically compared against gender-specific means derived from published normative data using Student's t-tests and chi-square tests.

RESULTS

Fifty-six individuals (33 male and 23 female) with MnP-TSD were identified, giving a male to female ratio of 1.4:1, while the prevalence rate in the indigenous British population was estimated to be 0.6%. The MD widths of the MnP1-TSD and MnP2-TSD teeth were approximately 1 mm wider than normal, while the FL diameters were about 0.5 mm and 1.5 mm narrower respectively, for the first and second premolar teeth. The MD/FL indices, instead of being under 90 as usual were above 100, while the mean MD/FL mm(2) crown surface areas were normal.

CONCLUSIONS

This study supplies odontometric dimensional and morphologic data on MnP-TSD teeth that provide a reference source for future comparisons.

Side of Dental Anomalies and Taurodontism as Potential Clinical Markers for Cleft Subphenotypes

Objective

The aim of this work was to investigate in more detail the dental clinical features that could serve to define subphenotypes of oral clefts.

Design

Dental records of oral cleft subjects from a group of 164 cases were examined, and 157 were included in this study. In addition, 65 families with two or more siblings born with clefts and 30 control families were evaluated to determine whether dental phenotypes were sporadic. Type of oral cleft and dental phenotypes (tooth agenesis, supernumerary teeth, taurodontism, dental transposition, and microdontia) outside the cleft area were investigated. Association of dental anomalies with preferential subtypes of cleft (subphenotype) was assessed.

Results

A total of 74 subjects presented at least one developmental dental anomaly. Tooth agenesis was the most common dental anomaly (28.6%), followed by taurodontism (15.2%). Supernumerary teeth were associated with cleft palate only ( p = .05). The absence of maxillary left lateral incisors was significantly associated with unilateral right cleft lip ( p = .02). Bilateral clefts were strongly associated with bilateral dental anomalies ( p < 0.001). In the cleft lip and palate group, tooth agenesis was associated with dental transposition ( p = .03) and with supernumerary teeth ( p = .009). Subjects with oral clefts have a higher risk of tooth agenesis (odds ratio = 3.33; 95% confidence interval, 1.18 to 10.13) and taurodontism (odds ratio = 3.95; 95% confidence interval, 2.28 to 6.82). Tooth agenesis, microdontic upper lateral incisors, and supernumerary teeth were most commonly found in unaffected siblings and parents of children born with clefts in comparison with families with no family history of clefts ( p = .01).

Conclusion

The preferential associations between specific cleft types with dental phenotypes suggest dental anomalies can be used as clinical markers to define the subphenotype isolated cleft lip and palate.

Studies of dental anomalies in a large group of school children

The identification of specific patterns of dental anomalies would allow testing the hypothesis that certain genetic and environmental factors contribute to distinct dental anomaly subphenotypes. A sexual dimorphism in tooth agenesis and its association with other dental anomalies has been suggested. The aim of this study was to investigate a large group of children to define dental anomaly subphenotypes that may aid future genetic studies. Orthopantamograms of 1198 subjects were examined and 1167 were used in this study. The frequency of tooth agenesis in the studied population was 4.8%. Male:female ratios varied from 2:1 in the agenesis of upper lateral incisors to 0.5:1 in premolar agenesis. The risk of infra-occlusion of primary molars and double formation of primary incisors was increased in individuals with tooth agenesis.