Prof. Yusuf Osman
Permanent URI for this collection
| Position: | Dean |
| Faculty: | Faculty of Dentistry |
| Qualifications: | B.Ch.D , M.Ch.D, Hons BBA, MBA, PGDHM |
| My publications in this repository | |
| More about me: | here, and here |
| Tel: | 021 937 3001 |
| Fax: | 021 931 2287 |
| Email: | yosman@uwc.ac.za |
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Item Volumetric change of flowable composite resins due to polymerization as measured with an electronic mercury dilatometer(Herbert Publications Ltd., 2013) Mulder, Riaan; Grobler, Sias Renier; Osman, Yusuf IsmailBACKGROUND: To determine the total volumetric change and the relative speed of shrinkage of bulk fill flowable composites during polymerization. MATERIALS AND METHODS: A specially designed electronic mercury dilatometer was used to determine the volumetric change. The light intensity was 500mW/cm2. The mercury dilatometer measured the volumetric change every 0.5 seconds during the 35 second irradiation exposure time. The materials tested were Z250 as standard and control. Four bulk fill flowable composites were tested. RESULTS: The sequence of total volumetric change was found to be: Z250 < Filtek bulk fill < Xtra-Base bulk fill < SDR < Venus bulk fill. The speed of shrinkage of the bulk fill flowables was faster than that of Z250, while the 2 flowables with the highest shrinkage speed (SDR and Venus) also had the highest total volumetric change. Of the different materials tested the volumetric change of Z250 (1.13%) was the lowest and significantly less (p<0.05) than that of SDR (1.55%) and Venus (1.72%). The material with the highest filler content (Z250) also showed the lowest shrinkage (1.13%) but this effect could not be seen in the flowables. In general, it was found that a 35 second irradiation period (with a light intensity of 500mW/cm2) was satisfactory for complete polymerization of the resins. CONCLUSIONS: The volumetric changes and speed of shrinkage were higher for all 4 bulk fill flowable composites than for Z250. SDR and Venus flowables had the fastest and highest volumetric shrinkage. Clinical significance: The manufacturers of bulk fill flowable composites advocate filling layers of 4mm. However, because of the high shrinkage values found in this study it should be suggested that the standard 2mm layer increments still be used.Item Guidelines for the selection of tooth whitening products amongst those available on the market(South African Dental Association, 2013) Basson, Reneda; Grobler, Sias Renier; van Wyk Kotze, Theuns; Osman, Yusuf IsmailBackground: Several tooth whiteners are available on the market, and the ideal choice should be determined by ef ficacy and optimal clinical results. Objectives: The purpose of this study was to compare the reported clinical success rates of different tooth whitening products. Search strategy: The relevant literature (1998 - 2011) was studied, using as sources the databases: Google Scholar, Science Direct, Medline and Pubmed. Selection criteria: The material was clearly identified, the manufacturers' instructions were respected and the sample size stated. Results and conclusions: This descriptive report on 49 papers focuses on the total colour change, measured with a calibrated shade guide and also numerically {colourime ter, chromameter or spectrophotometer), the relapse of the colour change and tooth sensitivity. In general, the dentist supervised at-home bleaching and the in-office treatment gave approximately the same initial percentage improvement of tooth whitening. However,the relapse after a four week or longer period was significantly higher for the in-office treat ment. The treatment of choice should be a dentist super vised at-home bleaching product which generally contains -1096 carbamide peroxide applied over about 14 days for about eight hours per night. Tooth sensitivity should not be a general problem although some subjects might choose to discontinue treatment as a result of sensitivity.Item Cytotoxicity of seven recent dentine bonding agents on mouse 3T3 fibroblast cells(Scientific Research Publishing, 2012) Olivier, Annette; Grobler, Sias Renier; Osman, Yusuf IsmailToday it is generally accepted that most bonding agents are cytotoxic. In this study the relative cyto-toxicity of seven recent dentine bonding agents on mouse 3T3 fibroblast cells were investigated. Materials and Methods. Near-confluent mouse 3T3 fibro- blast cells were exposed to Dulbecco Modified Eagle’s Medium containing extractions from the seven different bonding agents. The cell survival rate was then determined using the standard MTT assay. Results. The cell survival rate ranking is: iBond (94%) < Gbond (78%) < Xeno V (71%) < Adper Easy Bond (63%) < Xeno V+ (61%) < Adper Scotchbond SE (33%) < XP Bond (32%). Part A of Adper Scotchbond SE had a survival rate of 35% and part B 38%. These two parts did not differ significantly. Adper Scotchbond SE and XP Bond do not differ significantly. While Xeno V+, Xeno V and Adper Easy Bond do not differ. (p < 5%; Tukey-Kramer Multiple-Comparison Test). Conclusion. All of the tested adhesive bonding agents were cytotoxic with survival rate of 3T3 cells between 94% to 31%. Of the 7 bonding agents tested iBond was found to be only slightly toxic and by far the least toxic. The two bonding agents (XP Bond and Adper Scotchbond SE) containing UDMA plus TEGDMA plus HEMA plus camphorquinone were found to be the most toxic.