Twins and twinning, dentists and dentistry

Comparisons of physical features within identical (monozygous) and non-identical (dizygous) twin pairs have provided valuable insights into the relative contributions of genetic and environmental influences to observed variability. The special nature of the twinning process itself also provides an opportunity to learn more about early human development, including how body symmetry is determined. The mechanisms of twinning, mortality and morbidity in twins, determination of body symmetry including the phenomenon of mirror-imaging, postnatal growth and development of twins, and zygosity determination are discussed. Twin studies with direct relevance to clinical dentistry are reviewed and illustrated by examples from an ongoing investigation of dentofacial morphology in South Australian twins.     

The effect of public or private management on patients with temporomandibular joint pain dysfunction

Australians may receive free dental treatment via the public sector if they have a health care card but otherwise must seek treatment via the private sector. These two modes of dental delivery have different objectives, facilities, and patient populations. Two groups of patients, one public and one private, who presented to the same clinicians with temporomandibular joint dysfunction were studied. There were differences in age, numbers of natural teeth and some psychological features. However, the outcome to simple non-surgical management resulted in similar levels of successful treatment.     

The dental health of Indo-Chinese and Australian-born adolescents

Since 1975, more than 100,000 Indo-Chinese refugees from Vietnam, Kampuchea, and Laos have been resettled in Australia. This dental survey was undertaken to compare the dental health of 104 Australian-born and 126 Indo-Chinese adolescents from a State high school within a high migrant area of Melbourne. The mean DMFT score for the Australian-born group was 3.37 teeth, compared with 6.05 for the Vietnamese group, and 3.10 for the Kampuchean-Laotian group. More restorations and extractions were required by the Vietnamese subjects compared with the Australian-born and Kampuchean-Laotian subjects. Almost all subjects had gingivitis, however the proportion of Indo-Chinese subjects with shallow and deep pockets was greater than that of the Australian-born subjects. The periodontal health of the Kampucheans and Laotians was the most severe of the Indo-Chinese groups. These findings indicate that the Indo-Chinese adolescent refugees represent a high risk group for dental problems within the Australian population.     

The evolution of the complete denture base. Theories of complete denture retention — A review. Part 1

The history of denture base materials and the accompanying development of impression techniques are traced from the earliest times to the present day (Part 1) as a prelude to a study (Part 2–4) of the various theories that have been advanced to explain retention of the base without mechanical support. These theories are critically reviewed and tabulated in chronological order. Some areas for further investigation are identified.     

Parallel bonded cast attachments for removable partial dentures

The original design of a semi-precision extra-coronal attachment for partial dentures is illustrated, and its fabrication in a cast non-precious bondable alloy is described. A step-by-step method is also described of bonding multiple attachments in parallel for the retention and support of removable partial dentures. Clinical cases are illustrated. The results of trials indicate that the method is clinically viable and, in selected cases, appears to offer distinct advantages over existing retention systems.     

Colour stability of composite resins: A clinical comparison

Ninety three Class III cavities were prepared in 66 patients, and restored with one of three resin-based restorative materials; a hybrid self-cure material, a microfine self-cure material, or a microfine light-cure material. Standard sets of clinical colour transparencies were used to evaluate colour match with the surrounding tooth and marginal discoloration over five years. After five years, all materials had become slightly darker, the microfine self-cure material significantly more so than the light-cure material. There was no significant development of marginal discoloration.     

Oral submucous fibrosis. Case report and review of the literature

A case history and brief literature review of oral submucous fibrosis is presented. This condition is most frequently found in the Indian subcontinent and only rarely encountered elsewhere. The aetiology is considered to be related to dietary habits and customs found in the population. The condition has a known malignant potential. With increasing migration to Australia from the Indian subcontinent the condition should be known and recognized by clinicians.     

Langerhans cell disease associated with pathological fracture of the mandible

A 27-year-old male suffered a fractured mandible following extraction of a tooth. It was subsequently found that the fracture occurred in an area pathologically weakened by a localized lesion of Langerhans cell disease. Since lesions of the jaws may be seen either as the first manifestation or as a complication of widespread Langerhans cell disease, the dentist has a major role in the diagnosis and management of such cases.     

Cariostatic effect of glass ionomer cement: a five-year clinical study

Composite resin and glass ionomer cement were used to restore 67 and 65 Class V carious lesions, respectively. The restorations were assessed each year for recurrent caries and marginal staining. After five years, 1 per cent of glass ionomer and 6 per cent of composite restorations had become carious, and there was approximately twice as much marginal staining around the composite as around the glass ionomers. There appear to be significant benefits in using glass ionomer to restore Class V carious lesions.     

Comparison between two Procion dyes and Alizarin Red to assess marginal leakage in resin restorations. A laboratory study

To assess the width of the gaps that may occur in resin restorations bonded to dentine, buccal and lingual cavities were prepared in 18 caries- and restoration-free extracted molar teeth. All teeth were restored with composite resin. Nine of the teeth were then thermocycled for five hours. All teeth were stained with 0.5 per cent, 1.0 per cent or 1.5 per cent solutions of chloro-s-triazinyl dyes (Reactive Red and Reactive Orange 14) or Alizarin Red in order to assess the effectiveness of each stain in detecting marginal leakage. Quantitative assessment indicated that Reactive Orange 14 was superior to the other two stains as it more clearly defined the marginal gaps of the restorations. This superiority was evident for both thermocycled and nonthermocycled teeth.