The Journal of the Dental Association of South Africa = Die Tydskrif van die Tandheelkundige Vereniging van Suid-Afrika最新文献

A comprehensive clinical examination followed by a radiographic assessment of the edentulous areas is a prerequisite to placing dental implants. Although radiographic assessment of the mandible is accurate using plain film radiography this is not so for the maxilla for which computed tomography is often necessary. In this study patients requiring the placement of maxillary implants were referred for multi-planar cross-sectional oblique and panoramic computed tomography (CT scan) in addition to standard radiographic views. After interpretation of the CT scans patients could be categorized into two groups. One group comprised those patients who could be treated with a standard protocol for implant placement; the second group required augmentation procedures to supplement bone volume. After implant placement, a minimum healing period of 24 weeks was adhered to prior to placing healing abutments. By 27 months 95.5 per cent of Brånemark System fixtures were osseo-integrated.

An in vitro study was performed to ascertain the marginal seal elemental composition of amalgam restored extracted teeth of known marginal leakage. Occlusal cavities were cut in 400 caries free extracted teeth and left unlined or lined with one of 5 bases. A varnish was applied to half the cavities followed by restoration with a low copper or high copper amalgam to produce 20 restoration combinations. The teeth were stored in 1 per cent NaCl and thymol for 3 and 12 months at 20 degrees C whereafter a standard fluorescent dye marginal leakage test was performed on 320 specimens (eight teeth per treatment). Restoration combinations were grouped into 4 seal classes depending on percentage marginal seal achieved for each combination: 0-25 per cent; 26-50 per cent; 51-75 per cent and 76-100 per cent. The 80 remaining teeth (2 teeth per treatment) were fractured to expose the restoration and cavity surface, covered with marginal seal material and this was analysed by energy dispersive X-ray analysis. Elemental seal composition was compared to percentage marginal seal achieved using ANOVA and Tukey's test with significance set at p < 0.05. Numbers of elemental analysis specimens falling into each marginal seal class was 0-25 per cent = 48; 26-50 per cent = 18; 51-75 per cent = 10; 76-100 per cent = 4. Of the 16 elements detected, nine were significantly linked to sealing/leakage: Ca, Cl, Cu, Mg, Hg, P, Ag, Sn and Zn. The findings have a bearing on the improved longevity of amalgam restorations.

A structured questionnaire was administered to a random sample of general dental practitioners in Natal, South Africa in 1994, to ascertain the precautions they use against cross-infection and to gauge the attitudes and behaviour towards the treatment of HIV-infected individuals. An interview was conducted covering 5 broad topics: demographic details, personal barrier protection, instrument sterilization and disinfection, sharps disposal and incidence of needlestick injuries and the extent of the knowledge, attitude and behaviour of the practitioners toward the treatment of HIV-infected individuals. The key findings were: routine glove wearing, for all patients, was practised by 87 per cent. The most common heat sterilization method was by autoclave (68 per cent), although a dry heat sterilizer and water boiler were used by 22 per cent of the respondents. Of the 18 respondents reporting a needlestick injury in the past 6 months only one sought after-care. 42 per cent of the respondents would continue to treat carriers of HIV in their practices. This survey shows that a significant number of dentists are using unacceptable cross-infection control procedures. Educational efforts should be made to improve their knowledge and to alleviate anxiety of health workers to treat HIV-infected patients.

Bonding systems make use of different types and concentrations of enamel etchants. The purpose of this in vitro investigation was to determine the shear bond strength of composite resin to etched enamel using different enamel etchants. The following etchants were used: 35 per cent phosphoric acid for 30 seconds, (Group 1, control), 10 per cent phosphoric acid for 20 seconds (Group 2), 10 per cent maleic acid for 15 seconds (Group 3), 65 per cent phosphoric acid for 30 seconds (Group 4) and 10 per cent citric acid/3 per cent ferric chloride for 30 seconds (Group 5). Composite (Z100) stubs were bonded to the adhesively treated etched enamel surfaces using a rubber split mould. The bonded specimens were stored in distilled water for 24 hours before they were stressed to failure using a shear load in an instron testing machine. Data were analysed statistically (Student-t-test). The micromorphology of the enamel etched with the different etchants was also evaluated in a SEM. Shear bond strength (MPa) for the different groups were as follows: group 1 (23.9), group 2 (18.9), group 3 (18.0), group 4 (20.4) and group 5 (15.6). Ten per cent maleic acid, 10 per cent phosphoric acid and 10 per cent citric acid/3 per cent ferric chloride demonstrated lower enamel bond strengths than conventional 35 per cent phosphoric acid.