Enamel hypoplasia in the primary dentition of monozygotic and dizygotic twins compared with singleton controls

BACKGROUND

The study of enamel hypoplasia (EH) and opacity in twins provides insights into the contribution of genetic and environmental factors in the expression of enamel defects.

AIM

This study examined prevalence and site concordance of EH and opacity in the primary dentition of 2- to 4-year-old twins and singleton controls to assess the relative contribution of genetics and the environment to the aetiology of these defects.

DESIGN

The study sample consisted of 88 twin children and 40 singletons aged 2-4 years of age. Medical histories were obtained and the children examined for enamel defects.

RESULTS

The prevalence of EH by teeth was 21% in monozygotic twins (MZ), 22% in dizygotic twins (DZ), and 15% in singleton controls. Twins showed a higher prevalence of EH compared with singletons (P < 0.05). Factors contributing to increase EH in twins were neonatal complications including intubation. There were no significant differences in site concordance of EH within the MZ twin pairs compared with DZ twin pairs when only presence of EH was considered, whereas a greater concordance was noted between MZ twin pairs compared with DZ twin pairs when both presence and absence of EH were considered.

CONCLUSIONS

The results suggest that both genetic and environmental factors contribute to observed variation of EH, although it is likely that environmental factors exert a greater influence.

Congenital aplasia of the major salivary glands: literature review and case report

Congenital aplasia of the major salivary glands is rare, and there have been few cases of the condition reported to date. In many cases, absence of the salivary glands is associated with syndromes involving the ectodermal tissues. The xerostomia encountered in affected children is usually associated with increased risk for caries and infections of the soft tissues. The purpose of this paper was to describe the case of a 10-year-old boy with bilateral aplasia of the submandibular and parotid salivary glands and the preventive and restorative treatment rendered. This case study demonstrates the importance of timely diagnosis of this condition in order to prevent the serious oral complications from xerostomia.

A controlled study of dental erosion in 2- to 4-year-old twins

BACKGROUND

Dental erosion (DE) in children is a significant oral health issue and has become a focus for research in clinical paediatric dentistry.

AIM

This study investigated DE in the primary dentition of 2- to 4-year-old twin and singleton children with regard to the genetic, medical and dietary factors associated with the condition.

DESIGN

The 128 subjects consisted of 88 twin children (31 monozygous, 50 dizygous, 7 unknown zygosity) and singletons (n = 40) aged 2-4 years. Medical, dental, and dietary histories were obtained. The children were examined for DE using a modified index.

RESULTS

The prevalence of DE by subject affected was 77% in monozygotic twins (MZ), 74% in dizygotic twins (DZ), and 75% in singleton controls (P > 0.1). Of the teeth scored, 12% had mild, 10% moderate, and 1% severe lesions, and DE was more severe in the older age group (P < 0.05). Concordance rates for erosion lesions in MZ and DZ co-twins were not statistically significant.

CONCLUSIONS

The prevalence of DE and the concordance of erosion lesions were similar between MZ and DZ twins and singleton children, suggesting that the contribution of genetic factors to DE is negligible.

ADRF Trebitsch Scholarship. The microbial contamination of toothbrushes. A pilot study

Ten individuals were each supplied with a new toothbrush of the same type and brand, together with identical tubes of fluoridated toothpaste. After a three-week period, during which subjects were asked to follow their usual oral hygiene practices, the toothbrushes were collected and assayed for microbial contamination using a range of selective growth media. The total microbial load per toothbrush was found to be 10(4) to 10(5) colony forming units. Staphylococci were found on all toothbrushes and streptococci on all but one. These two genera were also quantitatively dominant. Candida, corynebacteria, pseudomonads and coliforms were identified in 70, 60, 50 and 30 per cent of toothbrushes, respectively. However, mutans streptococci, lactobacilli and black-pigmented Gram-negative anaerobic rods were not detected on any of the toothbrushes. For each individual, information on variables such as toothbrush rinsing practices and post-brushing storage methods and environment was collected. No obvious relationship between such variables and microbial load was apparent but it is suggested that more extensive studies are needed, taking into account additional parameters such as age and degree of toothbrush wear and the use of pre-brushing mouthwashes.