Clinical evaluation of three dentine bonding agents

Three commercial dentine bonding agents were used with composite resin to restore non-undercut Class V abrasion lesions without enamel etching. Patients were reviewed at 3, 6 and 12 months and the integrity and marginal staining of restorations was assessed. The loss incidence of restorations ranged from 18 to 40 per cent at one year, and there was increasing evidence of marginal staining over the evaluation period. Comparisons are made with other commercial dentine bonding agents from previous studies in this series.     

Study of gypsum-bonded casting investments. Part 1

In order to develop analytical methods for identifying plaster or dental stone (calcium sulphate hemihydrate) and quantifying its content in gypsum-bonded dental casting investments, six dental gypsum products were studied by means of simultaneous differential thermal analysis-thermogravimetry (DTA-TG). Under the same analytical conditions employed in the present study, a phase change in calcium sulphate anhydrite (III-CaSO₄ to ll-CaSO₄) was shown to occur at about 220°C for four dental stones manufactured by various wet methods and at about 350°C for two plasters manufactured by dry methods. This confirms the general view that the two types of calcium sulphate hemihydrate manufactured by dry or wet method could be identified by the DTA method. A reasonable estimate of chemically bound water could be made from the TG results at 300°C. The present DTA-TG method can be used to identify the plaster or dental stone and calculate its content in gypsum-bonded casting investments.     

Factors influencing long-term restoration survival in three private dental practices in Adelaide

Very little is known of dentist and patient factors which may influence the survival or longevity of dental restorative materials placed in private practices. The present retrospective study investigated during 1992 the effects of six factors on the long-term survivals of five types of restorations placed by 20 male dentists in 100 adult patients, at 3 selected Adelaide dental practices. There were no significant effects on restoration survival from change of dentist, and generally only one or two types of restorations had their survivals influenced significantly either by dental practice location, or by patient age, frequency of patient attendance, experience of dentist, and whether or not the restorations were replacements during the study period. Restoration survival was not influenced significantly by whether, or not, any replacements were made by the dentist who placed the initial restorations. The median survival times for amalgams were 22.52 years, resin composites 16.72 years, castings 13.75 years, and crowns an estimated 26 years. For glass-ionomers, 75 per cent were still present at 11.25 years.     

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.     

The effect of dentine conditioning with polyacrylic acid on the clinical performance of glass ionomer cement — 3-year results

Forty cervical abrasion lesions were restored with a self-cure Type 2A glass ionomer cement. Prior to placement of the restorations, 20 lesions were scrubbed for 15 seconds with 25 per cent polyacrylic acid and 20 lesions were cleaned with a pumice and water slurry on a rubber cup. After three years, there was negligible marginal staining, and one restoration from each group was partly lost. There was no evidence to suggest that polyacrylic acid was preferred to pumice and water in the restoration of cervical abrasion lesions with glass ionomer cement.     

Study of gypsum-bonded casting investments. Part 2

The simultaneous differential thermal analysis — thermogravimetry (DTA-TG) method used in Part 1 of this two-part study was extended to analyse two gypsum-bonded dental casting investments, Kerr Cristobalite Inlay and GC Cristobalite Micro. Both investments had a similar cristobalite content of about 70 per cent. The remaining 30 per cent was dental stone in GCM, and a mixture of plaster and dental stone in KCI. Inclusion of plaster in KCI appeared responsible for the greater amount of water required for mixing this investment. The DTA-TG method used in the present study can be applied to identify the type and amount of hemi-hydrate, and the type of silica, in currently available gypsum-bonded investments.     

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.