Research Outputs (Oral Health Sciences)
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Item Base solubility and marginal sealing in amalgam restored teeth(1991) Grossman, E. S.; Witcomb, M. J.; Matejka, J. M.Item Growth and morphogenetic factors in bone induction: role of osteogenin and related bone morphogenetic proteins in craniofacial and periodontal bone repair.(1992) Ripamonti, Ugo; Reddi, A. H.Bone has considerable potential for repair as illustrated by the phenomenon of fracture healing. Repair and regeneration of bone recapitulate the sequential stages of development. It is well known that demineralized bone matrix has the potential to induce new bone formation locally at a heterotopic site of implantation. The sequential development of bone is reminiscent of endochondral bone differentiation during bone development. The collagenous matrix-induced bone formation is a prototype model for matrix-cell interactions in vivo. The developmental cascade includes migration of progenitor cells by chemotaxis, attachment of cells through fibronectin, proliferation of mesenchymal cells, and differentiation of bone. The bone inductive protein, osteogenin, was isolated by heparin affinity chromatography. Osteogenin initiates new bone formation and is promoted by other growth factors. Recently, the genes for osteogenin and related bone morphogenetic proteins were cloned and expressed. Recombinant osteogenin is osteogenic in vivo. The future prospects for bone induction are bright, and this is an exciting frontier with applications in oral and orthopaedic surgery.Item Advances in osteogenin and related bone morphogenetic proteins in bone induction and repair(1992) Luyten, F. P.; Cunningham, N. S.; Vukicevic, S.; et alBone matrix is a repository of growth and differentiation factors as demonstrated by the induction of local cartilage and bone formation in rats. The bone inductive activity, termed osteogenin, can be dissociatively extracted, and it was isolated by heparin affinity, hydroxyapatite and molecular sieve chromatography. Osteogenin has been purified to homogeneity from bovine bone matrix and the sequences of several tryptic peptides have been determined. The sequences were similar to portions of the amino acid sequence deduced from the cDNA clone of bone morphogenetic protein-3 (BMP-3). The carboxyl-terminal quarter of osteogenin has sequence identity to the corresponding regions of two related proteins BMP-2A and BMP-2B. The bone inductive proteins are members of the TGF-beta superfamily, by virtue of the location of the highly conserved cysteines in their carboxyl-terminal region. Osteogenin and related BMPs initiate cartilage and bone formation in vivo. The study of the mechanism of action of these proteins will add considerable new information on the molecular signals controlling endochondral bone formation. In vitro data indicate that osteogenin stimulates the expression of the osteogenic and chondrogenic phenotypes. Our results demonstrate their profound influence on proteoglycan synthesis and degradation in bovine cartilage explant cultures. High affinity specific binding sites have been identified in both MC3T3 cells and articular chondrocytes. In vivo experiments demonstrate the efficacy of primate osteogenin in restoring large calvarial defects in adult baboons, establishing a primary role for osteogenin in therapeutic initiation and promotion of osteogenesis.Item Social class, parents' education and dental caries in 3- to 5-year-old children(1990) Chosack, A.; Cleaton-Jones, P.; Matejka, J.; et alThe caries prevalence of 1273-, 4- and 5-y-old white children was determined with mirror and probe under natural light at mother and child clinics. The social class of the family, the educational level of the mother and that of the father were determined from a questionnaire filled in by the accompanying adult at the time of examination. Both social class and parent's education had a statistically significant influence on the caries prevalence: those in the lower social classes and with parents without tertiary education had a much higher prevalence of cariesItem Plaque quantitiation through protein measurement(1992) Smit, A. M.; Cleaton-Jones, P. E.; Boardman, M. E.This study was undertaken to establish whether the quantitation of dental plaque protein by a dye-binding method (Coomassie G-250) may be used as an index of the amount of dental plaque sampled. Ten sites were sampled in 34 children on 5 occasions at 4 month intervals. The mean protein concentration in 1391 plaque samples was 6.9 +/- 4.1 micrograms (micrograms) (mean +/- standard deviation). A three-way analysis of variance showed that the plaque protein concentration was similar at the different sampling sites in the same child (p = 0.14), but statistically significant differences were observed with respect to time of sampling (F = 36.24; p = 0.0001) and individual sampled (F = 5.69; p = 0.0001). These observations indicate that plaque bacterial counts may be expressed as units of protein concentration and this method may be useful to relate the number of viable bacteria to an estimate of the amount of plaque collected. This ratio allows standardisation for any variation in the amount of plaque collected.Item Should impacted third molars be removed? A review of the literature(1993) van der Linden, W. J.; Lownie, J. F.; Cleaton-Jones, P. E.Item Item Dental caries in 11-year-old Indians in four religious groups(1990) Dockrat, M.; Cleaton-Jones, P.Item Permanent denition caries in KwaZulu and Namibia 11-year-olds(1990) Hargreaves, J. A.; Cleaton-Jones, P.; Matejka, J.; et alThe permanent dentitions of 11-year-old children in Namibia (n = 295) and KwaZulu (n = 308) living in rural and urban areas were examined using WHO caries diagnostic criteria. In low fluoride areas (less than 0.15 ppmF) significantly more caries was present in rural compared to urban KwaZulu but the prevalences in rural and urban Namibia were similar although significantly higher than in an area with 1.56ppmF in the drinking water. There was significantly more caries in rural Namibia than KwaZulu but the urban prevalences in both regions were similar. It is suggested that the urban findings are useful predictors for the needs of 11-year-old black children but local baseline surveys should be undertaken before considering dental programmes, treatment or preventive, for different rural communities in South Africa.Item Comparison of three fluorosis indices in a Namibian community with twice optimum fluoride in the drinking water(1990) Cleaton-Jones, P.; Hargreaves, J. A.In Otjiwarongo, a town in Namibia with twice the optimum fluoride in the drinking water (1.56 ppm) the Dean (Dean, Arnold and Elvove, 1942), Thylstrup and Fejerskov (Thylstrup and Fejerskov, 1978) and TSIF (Horowitz et al, 1984) indices of fluorosis were compared in permanent teeth of the children aged 11 y living in the region. Fluorosis severety was skewed in all instances to lower scores within each index. With the Thylstrup and Fejerskov and TSIF indices it was possible to compare fluorosis by individual teeth; the former was significantly more sensitive in diagnosis (56 per cent vs 50 per cent prevalence). It is recommended that the aims of a fluorosis investigation be carefully detailed before selecting the fluorosis index to be used. If detailed information on individual teeth related to fluoride ingestion is needed the Thylstrup and Fejerskov index is recommended, especially in areas with raised fluoride intakes where it is anticipated that the fluorosis levels will be mainly in the low levels of severity