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Hudson, Athol; Grobler, Sias; Harris, Angela (Master Publishing Group, 2011)[more][less]
Abstract: The purpose of the study was to assess the relative base designs of three different maxillary molar stainless steel brackets with reference to the shear bond strength of three different adhesive resins. The molar brackets used were Victory series (3M Unitek), Upper Molar (GAC) and Optimesh XRT (Ormco). The adhesives used were Transbond XT (3M Unitek), Enlight (Ormco) and Sure Ortho Light Bond (Sure Orthodontics). The human enamel specimens (144) were randomly divided into nine groups and each group (n=16) was allocated to a bracket/adhesive combination. The contact surface of each of the bracket bases was measured three dimensionally using a reflex microscope. The base designs were also subjected to further microscopic investigations. The brackets were bonded to the enamel, temperature cycled and the shear bond strength was measured. The size and design of each of the brackets was different. The base size, surface treatment, mesh strand diameter and aperture size of the bracket base mesh have a significant effect on the shear bond strength at the bracket/adhesive interface. The shear bond strengths of all three Ormco bracket/adhesive resin combinations (5.8-6.8 MPa) were significantly lower (p<0.05; Kruskal-Wallis) than the other six bracket/adhesive combinations (9.4-12.1 MPa). The different adhesive types (3 types) could not be mainly responsible for the low shear bond values found for the Ormco bracket. The 3M Unitek combination of the Victory series bracket and Transbond XT adhesive proved to have a high shear bond strength without enamel damage. URI: http://hdl.handle.net/10566/558 Files in this item: 1
HudsonOrthodonticMolarBrackets2011.pdf (1.831Mb) -
Grobler, Sias; Chikte, Usuf; Westraat, Jaco (Hindawi Publishing Corporation, 2011)[more][less]
Abstract: The purpose of this study was to determine the pH levels of 29 different samples of methamphetamine on the street market in Cape Town. The sample was dissolved in water and the pH of each sample determined. The pH levels varied from 3.02 to 7.03 with an average of 5.0. Seventy-two percent (21) of the samples had a pH level below the saliva “critical pH point of 5.6” and therefore should cause significant damage to enamel, especially in hyposalivation subjects without a saliva flow. However, about 26% of the samples had a pH level close to the neutral point and should cause minor damage to enamel. To lessen enamel damage, subjects should exercise good oral hygiene practice, rinse with a fluoride-containing mouth rinse, drink artificially sweetened drinks, and eat cheese. It is concluded that most of the methamphetamine samples have a low enough pH to cause direct damage to enamel especially in hyposalivation subjects. URI: http://hdl.handle.net/10566/560 Files in this item: 1
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Majeed, Abdul; Grobler, Sias; Moola, Mohamad H. (South African Dental Association, 2011)[more][less]
Abstract: OBJECTIVES: The purpose of this in vitro study was to investigate the pH of 21 commercially available tooth-whitening products. METHODS: Tooth-whitening products were divided into four categories: dentist supervised-home bleaching products (n = 5); in-office bleaching products (n = 5); over-the-counter bleaching products (n = 4) and whitening toothpastes and rinses (n = 7). The pH of three samples of each product was measured using an Orion Expandable Ion Analyzer EA940 with a Sure-Flow, Epoxy-body combination pH electrode. The group data were analysed using one way ANOVA (significant at p < 0.05). RESULTS: The five dentist supervised-home bleaching products had a mean pH of 6.21 +/- 0.76 and ranged from 4.88 to 6.81. The five in-office bleaching products had a mean pH of 6.26 +/- 1.19 and ranged from 5.30 to 7.85. The four over-the-counter whitening products had a mean pH of 5.07 +/- 1.74 and ranged from 3.76 to 8.03 and the seven whitening toothpastes had a mean pH of 7.66 +/- 1.19 and ranged from 6.61 to 9.68. The pH of the over-the-counter category was significantly lower (more acidic) than all other categories (p < 0.05). The whitening gel of Rapid-White had the lowest acidic pH of 3.76 and Colgate Advanced Whitening toothpaste showed the highest alkaline pH of 9.68. CONCLUSIONS: The pH of all tooth-whitening products showed a wide range from 3.76 (highly acidic) to 9.68 (highly alkaline). Over-the-counter whitening products showed the lowest pH levels and in general these can be expected to damage enamel more than the other products. Dentists should be vigilant with regards to products used outside their surgeries and should warn their patients accordingly. CLINICAL IMPLICATIONS: The acidic pH of many of the whitening products other than in-office bleaching products is of concern and the general public should be better informed by the dental professionals of the dangers of these products. URI: http://hdl.handle.net/10566/579 Files in this item: 1
Majeedtoothwhiteningproducts2011.pdf (1.207Mb) -
Grobler, Sias; Louw, Adrian; Chikte, Usuf; Rossouw, Roelof; van Wyk Kotze, Theuns (Bentham Science Publishers, 2009)[more][less]
Abstract: This field study included the whole population of children aged 10–15 years (77 from a 0.19 mg/L F area; 89 from a 3.00 mg/L F area), with similar nutritional, dietary habits and similar ethnic and socioeconomic status. The fluoride concentration in the drinking water, the bone mineral content, the bone density and the degree of dental fluorosis were determined. The left radius was measured for bone width, bone mineral content, and bone mineral density. The mean fluorosis score was 1.3 in the low fluoride area and 3,6 in the high fluoride area. More than half the children in the low fluoride area had no fluorosis (scores 0 and 1) while only 5% in the high fluoride area had none. Severe fluorosis (30%) was only observed in the high fluoride area. The Wilcoxon Rank Sum Test indicated that fluorosis levels differed significantly (p < 0.05) between the two areas. No relationships were found between dental fluorosis and bone width or between fluorosis and bone mineral density in the two areas (Spearment Rank correlations). A significant increase in bone width was found with age but no differences amongst and boys and girls. A significant positive correlation was found in the high fluoride area between bone mineral density over age. In the 12-13 and 13-14 year age groups in the high fluoride area, girls had higher bone mineral densities. However, a significant negative correlation (p<0.02) was found for the low fluoride area (0.19 mg/L F) over age. URI: http://hdl.handle.net/10566/404 Files in this item: 1
GroblerDrinkingWater2009.pdf (114.0Kb) -
Grobler, Sias; Hayward, R; Wiese, S; Moola, Mohamad H.; van Wyk Kotze, Theuns (Elsevier, 2010)[more][less]
Abstract: Objectives: To evaluate the effectiveness of Opalescence PF 10% just after treatment, at 6-month follow-up and at a 14-month follow-up period. Methods: Opalescence PF 10% was applied nightly for 14 days. The color of teeth 11 and 21 of 17 subjects were measured with a spectrophotometer (L*; a*; b*) before treatment, just after treatment (14 days), after 6 months and after 14 months. Subjects were instructed to take note of any tooth sensitivity. Results: For all three components (L*, a* and b*) statistical significant differences (p < 0.05) in the values between base-line, after treatment (14 days later), after 6 months and after 14 months were found (Wilcoxon Signed Rank Sum Test). The decrease in L* was about 20% after 6 months and about 50% after 14 months. The a* value decreased approximately 14% after 6 months but was worse after 14 months than at the beginning. The b* value decreased the least with about 9% after 6 months and about 8% after 14 months. The decrease in View the MathML source was ∼20% after 14 months. Less than 20% of the subjects experienced mild tooth sensitivity just after treatment. Conclusion: Significantly whiter teeth were found after treatment as well as after a 6-month follow-up period. The whiteness/brightness (L*) decreased with ∼50% after 14 months and the a* value with ∼50% after 7 months, while the yellowness (b* value) remained even after 14 months. Clinical implications: The product is an effective tooth whitener resulting in only low tooth sensitivity. Re-bleaching could be done at about 14 months. URI: http://hdl.handle.net/10566/556 Files in this item: 1
GroblerSpectrophotometric2010.pdf (957.3Kb) -
Khan, Sadika; Geerts, Greta (South African Dental Association (SADA), 2008)[more][less]
Abstract: This study aims to evaluate the acceptance of light-cured acrylic resin for custom trays by dental students. A questionnaire addressing the use and handling properties of both light-cured (Megatray, Megadent, Germany) and chemically-cured (Excel, Wright Health Group, UK) custom tray materials was distributed amongst undergraduate dental students of the University of the Western Cape. Of a total of 196 dental students, 38 were absent on the day of the survey. Of the 158 questionnaires that were distributed and returned, 18 did not meet the inclusion criteria and 1 person chose not to participate. Of the 139 participating students, 98 were in 4th year, 41 in 5th year. With regards to the light-cured acrylic custom tray material, 77% used it most often, 64% said it saved time and 62 % said that it was easier to handle. Fifty two percent indicated that both types of materials should be taught in undergraduate training, 26% preferred the light-cured acrylic resin custom tray material, 20% suggested that only the light-cured resin be used and no one suggested the chemically-cured resin exclusively. The study concluded that most undergraduate students positively accepted the light-cured resin, but training in the use of both materials was recommended. Description: Presented at IADR 2005 – Kuwait (1st African Middle-Eastern IADR Conference) URI: http://hdl.handle.net/10566/222 Files in this item: 1
KhanLight-curedAcrylicResin2008.pdf (591.5Kb) -
Hudson, Athol; Harris, Angela; Mohamed, Nadia; Joubert, Jo-Anne (South African Dental Association, 2012)[more][less]
Abstract: Leeway space preservation in the mixed dentition is a well-documented method of space management. In the mandibular arch it may be saved for utilization in the correction of minor anterior crowding by the placement of a passive lower lingual arch (LLA) during the transition from the mixed dentition to the permanent dentition URI: http://hdl.handle.net/10566/569 Files in this item: 1
HudsonLingArch2013.pdf (299.6Kb)
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