Browsing by Author "van Wyk Kotze, Theuns"

Now showing 1 - 7 of 7
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    A clinical study of the effectiveness of two different 10% carbamide peroxide bleaching products: a 6-month followup
    (Hindawi Publishing Corporation, 2011) Grobler, Sias Renier; Majeed, Abdul; Hayward, Roche; Rossouw, Roelof; Moola, Mohamad H.; van Wyk Kotze, Theuns
    The purpose of this study was to evaluate the efficacy of two different 10% carbamide peroxide bleaching products just after treatment and after a 6-month follow-up period. Methods. Two 10% carbamide peroxide products (Opalescence PF andNiteWhite ACP) were applied nightly for 14 days, according to the manufacturers’ instructions. The color of teeth 11 and 21 of thirty-four subjects having A2 or darker teeth were measured with a spectrophotometer (L∗; a∗; b∗) before treatment, just after treatment (14 days) and after 6 months. Results and Conclusions. Both products produced significant whitening of teeth with total color change (ΔE∗ ab) of approximately 5.20 units. There was a significant improvement in all 3 color coordinates (L∗, a∗, and b∗) for up to 6 months postbleaching (P < .05). Nite White showed a higher degree of relapse (27%) than Opalescence (18%) over the 6-month period. It is suggested that rebleaching after 6 months is not necessary
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    Effect of four different Opalescence tooth-whitening products on enamel microhardness
    (South African Dental Association, 2008) Majeed, Abdul; Grobler, Sias Renier; Moola, Mohamad H.; Rossouw, Roelof; van Wyk Kotze, Theuns
    OBJECTIVES: The purpose was to evaluate the effect of various Opalescence tooth-whitening products on enamel. METHODS AND MATERIALS: Enamel blocks were exposed to Opalescence PF 10% Carbamide Peroxide (n = 10), Opalescence PF 20% Carbamide Peroxide (n = 10), Opalescence Trèswhite Supreme 10% Hydrogen Peroxide (n = 10) and Opalescence Quick PF 45% Carbamide Peroxide (n = 10) according to the manufacturer's instructions. The control group was enamel blocks (n = 10) kept in artificial saliva. The values were obtained before exposure and after the 14-days treatment period. Enamel blocks were kept in saliva between treatments. Indent marks on enamel blocks were examined using the scanning electron microscope for treatment effects. RESULTS: All four different Opalescence products damaged enamel. The most damage was done when treated for a long period (112 hours). SEM images also showed damage to enamel by all 4 products. Opalescence with 10% and with 20% Carbamide Peroxide showed the highest damage, which also differed significantly (p < 0.05) from the saliva control group (p < 0.05; Tukey-Kramer Multiple comparison test). CONCLUSION: All 4 Opalescence products damaged enamel. Higher damage was done by the 10% carbamide peroxide and 20% carbamide peroxide products because of the much longer exposure period (112 hours in comparison to 7 hours).
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    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 Ismail
    Background: 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.
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    In vivo spectrophotometric assessment of the tooth whitening effectiveness of Nite White 10% with amorphous calcium phosphate, potassium nitrate and fluoride, over a 6-month period
    (Bentham Science Publishers, 2011) Grobler, Sias Renier; Majeed, Abdul; Moola, Mohamad H.; Rossouw, Roelof; van Wyk Kotze, Theuns
    To clinically evaluate the effectiveness of Nite White 10% carbamide peroxide with amorphous calcium phosphate, potassium nitrate and fluoride over a 6-month follow-up period. Nite White was applied nightly for 14 days, according to the manufacturer’s instructions. The color of teeth 11 and 21 of twenty one subjects was measured with a spectrophotometer (L*; a*; b*). Subjects were instructed to take note of any tooth sensitivity and gingival irritation. For all three components (L*, a* and b*) statistical significant differences (p<0.05) in the values between base-line (prebleaching) and; after treatment, after 1-month, after 3-months as well as after 6-months were found (Wilcoxon Signed Rank Sum Test). Significant differences were also found amongst the 􀀁E*ab (0-14days) values and; 􀀁E*ab (0-1 month), 􀀁E*ab (0-3 months) and 􀀁E*ab (0-6 months). However, no significant differences were found between pairs of 􀀁E*ab (0-1 month), 􀀁E*ab (0-3 months) and 􀀁E*ab (0-6months). The decrease in 􀀁E*ab was the highest after 1 month (~30%). The highest decrease in L* was about 58% after 1 month. Over the 14-day treatment period tooth sensitivity was 24.5%. Conclusions: Nite White ACP demonstrated significant tooth-whitening (unit increase = 5.29) with a low tooth sensitivity (25%) probably due to the presence of amorphous calcium phosphate, potassium nitrate, and fluoride. The whitening effect decreased the most after one month and then maintained well even after a 6 month period (units 3.89).
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    The relationships between two different drinking water fluoride levels, dental fluorosis and bone mineral density of children
    (Bentham Science Publishers, 2009) Grobler, Sias Renier; Louw, Adrian; Chikte, Usuf; Rossouw, Roelof; van Wyk Kotze, Theuns
    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.
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    The significance of sub-threshold symptoms of anxiety in the aetiology of bruxism
    (South African Journal of Psychology, 2010) Basson, Reneda; Mwaba, Kelvin; Rossouw, Roelof; Geerts, Greta; van Wyk Kotze, Theuns; Stuhlinger, Martin E.
    Bruxism is an oral parafunctional habit involving clenching and grinding of the teeth. It occurs mainly unconsciously, diurnally and/or nocturnally. It is considered an important contributory factor in the aetiology of myofacial pain (MFP) and temporomandibular disorders (TMD). The etiology of bruxism is considered to be multifactorial, involving physiological and psychological factors. The aim of the study was to examine the relationship between the sub-threshold symptoms of anxiety and bruxism using a spectrum model. Firstly, levels of anxiety and stress were determined using the Spielberger State Trait Anxiety Inventory (STAI) and the Kessler-10 (K-10). Secondly, a tooth wear score was determined by means of a clinical examination, intra-oral photographs and dental casts. Thirdly, bruxism was rated on an ordinal scale according to specified bruxism criteria. A dualistic trend in the relationship between sub-threshold symptoms of anxiety, stress and bruxism was observed in the results. In approximately half of the subjects with higher than average anxiety and stress scores, bruxism behaviour was found. This indicates the possibility of two groups with separate relationships. The dentist could play a role in recognizing that a patient may be experiencing stress or anxiety, expressed through bruxing behaviour and refer the patient for therapy or counselling. An understanding of the psychological factors involved in the etiology of bruxism could encourage a more holistic approach to the treatment of patients with signs of bruxism.
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    Spectrophotometric assessment of the effectiveness of Opalescence PF 10%: a 14-month clinical study
    (Elsevier, 2010) Grobler, Sias Renier; Hayward, Roche; Wiese, S; Moola, Mohamad H.; van Wyk Kotze, Theuns
    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.