Host genotype, pathogenic challenge and periodontal bone loss in the mouse.

Periodontal bone loss was induced in mice of different genotypes by oral inoculation with Actinomyces viscosus. Relatively high bone loss occurred in the mutant X-linked immune deficiency, implicating the humoral immune system. Maximum bone loss was always associated with inoculations of 1.6 x 10(7) colony forming units (c.f.u.), while inoculations of 1.6 x 10(6) or 1.6 x 10(9) c.f.u. resulted in bone loss little different from that in uninoculated controls. This 1000-fold range in inoculum size was not reflected in the number of A. viscosus organisms recovered from the molar teeth at the end of the experimental period, suggesting that differences in bone loss stemmed from the host response to the initial inoculum.

Coefficients of relationship by isonymy among oral cancer registrations in Scottish males.

The role of inherited susceptibility to oral cancers was studied by comparing groups of cancer patients and controls in terms of the coefficient of relationship by isonymy (Ri), both within and between Regions of mainland Scotland. Surname distributions for 3658 male cancer cases were derived from the Scottish Cancer Register for the years 1959-85. Control distributions were derived from a total of 32,468 male deaths in Scotland for 1976. For cancer of the floor of mouth, there was no evidence for increased isonymy in patients compared to controls and therefore no indication that familial factors contribute to cancer at this site. For cancer of the tongue there was a suggestion of increased isonymy within but not between Regions, perhaps reflecting environmental risk factors common to members of the same family. For cancers of the lip and salivary gland there was evidence of increased isonymy both within and to a lesser extent between Regions, suggesting a genetic contribution. There is corroborative evidence from other sources for a heritable component in salivary gland cancer but the reasons for the similar pattern of results in cancer of the lip are less clear.

Dentistry and the new genetics.

As environmental causes of disease become better controlled, so genetic factors assume relatively greater importance. Opportunities to investigate the genetic contribution to disease have increased dramatically through the remarkable technological developments of recent years. These developments have implications for both education and practice in dentistry, just as in any other branch of the biomedical sciences.

Host genes and dental caries.

With the attention now being given to molecular genetic analysis of cariogenic microorganisms, the role of host genes in influencing susceptibility to caries should not be forgotten. Increasing knowledge in this field will lead to identification of individuals at particular risk of dental decay and will help in planning rational strategies for management and prevention.

Genetic approaches in the study of periodontal diseases.

Periodontal diseases are essentially infectious in origin, their outcome depending on interaction between the pathogenic challenge and host response. Host genotype has been implicated in certain of the more unusual forms, but together these account for only a small proportion of periodontal patients. Nevertheless, the genes for these rarer conditions, some of which have already been located and/or cloned, are of considerable importance, since they may ultimately provide clues leading to a better understanding of the whole spectrum of periodontal disease. For the majority of periodontal patients, although inherited susceptibility is suspected, evidence of a significant genetic component is scanty. The priority here is therefore to establish the existence of contributing genes. This may be possible by using approaches designed to minimise the confounding effect of environmental variation that has probably been a source of confusion in the past.

Dental extractions in Paget's disease of bone.

The results of a postal questionnaire completed by 360 patients with Paget's disease of bone, on behalf of themselves and their unaffected spouses, suggest that dental practitioners have some awareness of the potential problems associated with extractions for patients with Paget's disease, but that nevertheless patients still suffer from greater difficulty at extraction and more post-extraction complications than normal.

Sweat pore count, hair density and tooth size: heritability and genetic correlation.

In 109 subjects from 50 families without major inherited disorders, sweat pore count showed the anticipated reduction with age but also unexpected systematic differences between sides and between fingers. After adjustment for age and sex, significant genetic variation was found for sweat pore count, hair density and tooth size. The three traits were not phenotypically correlated but there was a significant negative genetic correlation between hair density and sweat pore count. The findings suggest that the same genes influence these two traits in opposite directions and that genetic and environmental influences may act on them through different physiological mechanisms.

Affinities between contemporary and skeletal Jewish and non-Jewish groups based on tooth morphology.

Samples from five Jewish and six non-Jewish populations were compared in terms of the frequencies of 19 dental morphological variables. All but one of the samples came from Europe, North Africa, or the Middle East. Nine were from contemporary populations, and two were skeletal. Of the skeletal groups, one was Jewish, excavated on Mount Zion, Jerusalem, and dated at around 3,000 years old; and the other non-Jewish, excavated on the east coast of Australia, and dated at between 1,000 and 200 years old. Assessment of affinity between the different groups was based on smallest space analysis and cluster analysis. The results demonstrated relative proximity of the Jewish groups (with one exception), despite the fact that they came from a wide geographical area. In particular, the sample from Mount Zion showed greater affinity with three of the four living Jewish populations than with most non-Jewish groups. The skeletal Australian sample formed a cluster of its own, distinct from all the other groups. For six of the groups, the relationships based on tooth morphology showed good correspondence with known relationships based on single locus polymorphisms. The similarity of the Jewish groups to each other in terms of both tooth morphology and single locus polymorphisms was of special interest, since differences in other morphological and anthropometric characteristics, thought to be the result of selection, are known to exist between the Jewish populations.

Chronic atrophic oral candidiasis among patients with diabetes mellitus--role of secretor status.

Non-diabetic individuals who are non-secretors of blood group antigens are prone to superficial infections by Candida albicans. In this study, 216 patients with diabetes mellitus who were denture wearers were examined for the presence or absence of denture stomatitis. There was an overall trend for non-secretors to be prone to denture stomatitis compared with secretors. Stepwise linear discriminant analysis was used to dissect the contribution of secretor status and other variables to the development of the disease. Secretor status was found to be a contributory factor among patients with non-insulin dependent diabetes but not among those with insulin-dependent diabetes. The possible reasons for this are discussed.