UWCScholar :: Browsing by Author "Grobler, Sias Renier"

Browsing by Author "Grobler, Sias Renier"

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Antimicrobial activity of two South African honeys produced from indigenous Leucospermum cordifolium and Erica species on selected micro-organisms
(BioMed Central, 2008) Basson, Nicolaas; Grobler, Sias Renier
Background: Honey has been shown to have wound healing properties which can be ascribed to its antimicrobial activity. The antimicrobial activity can be effective against a broad spectrum of bacterial species especially those of medical importance. It has also been shown that there is considerable variation in the antimicrobial potency of different types of honey, which is impossible to predict. With this in mind we tested the antimicrobial activity of honeys produced from plants grown in South Africa for their antibacterial properties on selected standard strains of oral microorganisms. Methods: The honeys used were produced from the blossoms of Eucalyptus cladocalyx (Bluegum) trees, an indigenous South African plant Leucospermum cordifolium (Pincushion), a mixture of wild heather shrubs, mainly Erica species (Fynbos) and a Leptospermum scoparium (Manuka) honey. Only pure honey which had not been heated was used. The honeys were tested for their antimicrobial properties with a broth dilution method. Results: Although the honeys produced some inhibitory effect on the growth of the microorganisms, no exceptionally high activity occurred in the South African honeys. The carbohydrate concentration plays a key role in the antimicrobial activity of the honeys above 25%. However, these honeys do contain other antimicrobial properties that are effective against certain bacterial species at concentrations well below the hypertonic sugar concentration. The yeast C. albicans was more resistant to the honeys than the bacteria. The species S. anginosus and S. oralis were more sensitive to the honeys than the other test bacteria. Conclusion: The honeys produced from indigenous wild flowers from South Africa had no exceptionally high activity that could afford medical grade status.
Chemical aspects of human plaque and enamel
(University of the Western Cape, 1982) Grobler, Sias Renier; van Wyk, C.W
The ideal conditions for the use of hydrazinium sulphate as a reducing agent to determine phosphorus in dental plaque were investigated. When this method was compared to the tin (II) chloride (Kuttner and Cohen, 1927) and ascorbic acid method (Chen, loribara and Warner, 1956),which is generally in use for the measurement of phosphorus in plaque, it was found to have certain advantages. Different ashing techniques were compared, as well as the influence of different acids on wet ashing. The hydrazinium sulphate method could determine as little as 1,8 ~g phosphorus per 50 ml and is recommended for the routine analysis of phosphorus in dental plaque samples with wet ashing. Today phosphorus can be determined, among other methods gravimetrically, titrimetically and spectroscopically (Williams, 1979). Through spectroscopic methods phosphate might be analysed spectrophotometrically by 3 main methods, as molybdophosphoric acid, its reducing product molybdenum blue and the yellow vanadomolybdophosphoric complex (Stuart and Duff, 1980). In addition indirect methods derived from molybdophosphoric acid might also be used (Williams, 1979). When phosphorus is spectrophotometrically determined during the reduction of a phosphomolybdate complex by means of different reducing agents (Kuttner and Cohen, 1927; Chen et aI, 1956; Fiske and Subbarow, 1925 and 1929, Taylor and Miller, 1914; Martin and Doty, 1949; Eibl and Lands, 1969; Vogel, 1961; Boltz and Mellong, 1947; Lazarus and Chou, 1972; Laws and Webley, 1959; Burton and Riley, 1955; Dickman and Bray, 1940), it is necessary to establish the optimum conditions under which the reducing agent, hydrazinium sulphate, can be used. In spite of this, many details about exact experimental procedures are not known (Taylor and Miller, 1914; Vogel, 1961; Boltz and Mellon, 1947). The present investigation is an attempt to establish the ideal conditions for the use of hydrazinium sulphate as a reducing agent during the formation of molybdenum blue (Schirmer et al, 1942) and the effectiveness of the method for the determination of phosphorus in dental plaque by different ashing techniques. The hydrazine method is also compared to that of Chen et al (1956) which is generally in use for plaque phosphate determinations by many authors (Ashley, 1975; Ashley and Wilson, 1976; Kleinberg et al, 1971; Zuniga et al, 1973), as well as to the sometimes used (Dawes and Jenkins, 1962) tin (II) chloride method of Kuttner and Cohen (1927). For the review of many other accepted methods, see Lindberg and Ernster (1956), and Williams (1979). The results are compared to the modified ascorbic acid method (Chen et al, 1956) as well as to the tin (II) chloride method (Kuttner and Cohen, 1927).
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
A comparative study to determine the shock absorption ability of two popular mouth guards available on the South African market
(Electronic Doctor (E-Doc) Publishers & SADA, 2017) Mohamed, Nadia; Grobler, Sias Renier; Basson, N. J.; Osman, Yusuf Ismail; Mulder, Riaan
It is expected that most mouth guards will provide some level of protection to teeth. In this study a device was developed to measure the relative impact absorption of two different mouth guards (Proform, Type III vacuum-formed and Max, Type IV pressure laminate). Seven of each of the two types of mouth guards were made and each batch was exposed to between six and 10 impact trials.
Comparison of colour components between maxillary central incisors - an in vivo study
(South African Dental Association, 2015) Moodley, Desi; Grobler, Sias Renier; Osman, Yusuf Ismail; Kotze, T.J.v.W.
Objectives: The purpose of this study was to determine the relationship of colour in the CIE L a b scale between the maxillary central incisors. Methods: The colour of the maxillary central incisors of 83 patients was measured (in vivo) using a spectrophotometer. Three measurements (6 mm diameter) at the centre of the crown of each of the maxillary central incisors were performed. Results: The total colour difference (?E ab) showed wide variability with the average ?E ab = 1.79. The Wilcoxon Signed Rank Test showed statistically significant differences (p < 0.05) between maxillary right (11) and left central incisors (21) in both the L and b colour components. In the a scale no significant difference was noted. Conclusion: Small colour differences exist between the maxillary central incisors in the same individual when evaluated with a spectrophotometer. Clinical significance: As there is often a difference between the colours of the two central incisors in the same patient, the colour of both the central incisors should be taken into consideration when shade matching anterior teeth.
Cytotoxicity of seven recent dentine bonding agents on mouse 3T3 fibroblast cells
(Scientific Research Publishing, 2012) Olivier, Annette; Grobler, Sias Renier; Osman, Yusuf Ismail
Today 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.
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).
Effect of four over-the-counter tooth-whitening products on enamel microhardness
(South African Dental Association, 2011) Majeed, Abdul; Grobler, Sias Renier; Moola, Mohamad H.; Oberholzer, Theunis
OBJECTIVES: This in vitro study evaluated the effect of four over-the-counter tooth-whitening products on enamel microhardness. METHODS: Fifty enamel blocks were prepared from extracted human molar teeth. The enamel surfaces were polished up to 1200 grit fineness and the specimens randomly divided into five groups. Enamel blocks were exposed to: Rapid White (n=10); Absolute White (n=10); Speed White (n=10) and White Glo (n=10) whitening products, according to the manufacturers' instructions. As control, ten enamel blocks were kept in artificial saliva at 37 degrees C without any treatment. Microhardness values were obtained before exposure (baseline) and after 1, 7 and 14-day treatment periods using a digital hardness tester with a Vickers diamond indenter. Data were analysed using Wilcoxon Signed Rank Sum Test, one-way ANOVA and Tukey-Kramer Multiple Comparison Test (p<0.05). RESULTS: Both Rapid White and Absolute White reduced enamel microhardness. Speed White increased the microhardness of enamel, while White Glo and artificial saliva had no effect on hardness. CONCLUSIONS: Over-the-counter tooth-whitening products might decrease enamel microhardness depending on the type of product.
Effect of various tooth-whitening products on enamel microhardness
(South African Dental Association, 2009) Grobler, Sias Renier; Majeed, Abdul; Moola, Mohamad H.
Objectives: The purpose was to evaluate the effect of various tooth-whitening products on the South African market, containing carbamide peroxide (CP) or hydrogen peroxide (HP), on enamel microhardness. Methods: Enamel blocks were exposed to: Nite White® ACP 10% CP (group 2, n=10); Yotuel® Patient 10% CP (group 3, n=10); Opalescence® PF 10% CP (group 4, n=10); Opalescence® PF 20% CP (group 5, n=10); Opalescence® Treswhite Supreme 10% HP (group 6, n=10); Yotuel® 10 Minutes 30% CP (group 7, n=10); Opalescence® Quick 45% CP (group 8, n=10), Yotuel® Special 35% HP (group 9, n=10), Opalescence® Boost 38% HP (group 10, n=10) according to the instructions of the manufacturers. The control group (1) was enamel blocks (n=10) kept in artificial saliva at 37˚C without any treatment. The microhardness values were obtained before exposure and after a 14-day treatment period. Specimens were kept in artificial saliva at 37˚C between treatments. Data were analysed using Kruskal-Wallis one-way ANOVA and Tukey-Kramer Multiple Comparison Test. Indent marks on the enamel blocks were also examined under the scanning electron microscope. Results: All whitening products decreased enamel microhardness except group 10. Only Groups 2,3,4,5 and 7 showed significant decrease in enamel microhardness as compared to the control group (p<0.05). Groups 2, 3 and 7 differed significantly from all the other groups (p<0.05). The highest damage was recorded for group 2 (Nite White® ACP 10% CP), which differed significantly from groups 3 and 7. SEM images also showed damage to enamel. Conclusions: All products damaged enamel except Opalescence® Boost 38% HP. In general, the products containing carbamide peroxide were more damaging while longer treatment periods influenced the microhardness values negatively. Nite White® ACP without fluoride showed relatively more damage than all the other products containing fluoride.
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.
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).
Insights into a comparison of three different cements on the push-out bond strength of a glass-fibre post
(SADA, 2017) Grobler, Sias Renier; Patel, Naren; Fortuin, A.; Moodley, Desi
One of the main causes of failure of fibre posts is debonding of the post in the prepared post space. The adhesive properties of total etch adhesive cements were assessed by comparing the performance of cements using self-etching adhesive resins, to verify which system provided the best retentive capabilities with a double tapered post system. Extracted maxillary central incisors were endodontically treated and randomly divided into three groups: the Calibra (Dentsply), RelyX Ultimate (3M ESPE) and Panavia F2.0 (Kuraray) groups. RelyX Ultimate produced significantly the highest de-bond stress values (p<0.05) in the overall performance, as well as in the coronal, middle and apical sections of the tooth. Thus RelyX Ultimate with self-etching adhesive reliably can be used for post cementation with a double tapered post system in endodontically treated anterior teeth.
Insights into chitosan hydrogels on dentine bond strength and cytotoxicity
(Scientific Research Publishing, 2013) Perchyonok, Tamara; Grobler, Sias Renier; Zhang, Shengmiao; Olivier, Annette; Oberholzer, Theunis
Contemporary dental adhesives show favorable im- mediate results in terms of bonding effectiveness. However, the durability of resin-dentin bonds is their major problem. Materials and Methods: Preparation of 3 chitosan-antioxidant hydrogels was achieved us- ing modified hydrogel preparation method. Their effect on the bond strength to dentine both short term (after 24 hours) and long term (after 6 months) were evaluated using shear bond strength measurements using Instron Universal Testing Mascine). The SEM was used to study the surface of the hydrogels. The cell survival rate (cytotoxicity) of the antioxidants re- sveratrol, β-carotene and propolis towards Balb/c 3T3 mouse fibroblast cells was also assessed using the standard MTT assay. Results: It was found that chi- tosan-H treated dentine gives significantly (p < 0.05; Non-parametric ANOVA test) higher shear bond va- lues than dentine treated or not treated with phos- phoric acid. The anti-oxidants chitosan hydrogels improved the shear bond strength. Overall, there was a relapse in the shear bond strength after 6 months. The SEM study showed that the hydrogel formula- tions have a uniform distribution of drug content, homogenous texture and yellow color. The pH of the growth medium adjusted to relevant values had a highly significant influence (Tukey-Kramer Multiple- Comparison Test; p < 0.01) on the cell survival rate of Balb/c mouse 3T3 fibroblast cells and therefore most probably also to tooth pulp fibroblast cells. The lower the pH value the higher the negative influence. Fur- thermore, the sequence of survival rate was found to be: β-carotene (92%) > propolis (68%) > resveratrol (33%). Conclusion: the antioxidant-chitosan hydro- gels significantly improved bonding to dentine with or without phosphoric acid treatment. The pH of the growth medium had a high influence on the cell survival rate of Balb/c mouse 3T3 fibroblast cells. The release of the antioxidant β-carotene would not have an influence on the pulp cells. These materials might address the current perspectives for improving bond durability.
Insights into the clinical effectiveness of whitening products - Part 1: Dentist-supervised-at-home bleaching product
(SADA, 2016) Grobler, Sias Renier; Osman, Y.
This section of the report is about the success of a dentist-supervised-at home tooth whitener, giving the results of a clinical study. Opalescence PF 10% was applied for 14 days and the colour change followed over a 14 month period. It could be concluded that: a) Opalescence is a good tooth whitener, b) the time of re-bleaching should actually depend on the colour choice expressed by the patient. Overall re-bleaching should only be done after six months and not on a monthly basis, otherwise enamel damage may become a problem. Remember that peroxide, which is responsible for the bleaching process, is a strong oxidizing agent. Furthermore, A2 and darker teeth showed more aesthetically observable colour changes.
Insights into the clinical effectiveness of whitening products. Dentist-supervised-at-home bleaching product (Opalescence PF). Whitening of darker teeth in contrast to the effects on relatively whiter teeth
(2017) Grobler, Sias Renier; Osman, Yusuf Ismail
This study evaluated the success of the whitening of darker teeth by comparing the results of a tooth whitening programme in two groups, subjects with darker (A2 and darker) teeth and patients with whiter teeth. Opalescence PF 10% was applied for 14 days (nightly for 6-8 hours) and the colour changes followed over a six month period. The overall effect (∆E*ab) showed a much higher improvement (p<1%) in the whitening of darker teeth (~40%) relative to teeth which at the outset had been whiter than A2. Overall (∆E*ab) a deterioration of about 19% for darker teeth and ~9% for whiter teeth was seen after six months, but a significant improvement in colour was still evident. Conclusion: The effect of Opalescence PF 10% treatment was significantly better in all components (L*, a*, b* and ∆E*ab) for A2 and darker teeth relative to whiter teeth. Despite a significant colour relapse after a six-month period, there was still an improvement compared with before treatment. Thus, it can be expected that bleaching treatment of darker teeth would result in more aesthetic observable colour changes. The significant loss of the whitening effect found after six months may suggest the recommendation to re-bleach.
Insights into the clinical effectiveness of whitening products. Part 2 Dentist-supervised-at-home LED gel bleaching product
(SADA, 2017) Osman, Y.; Grobler, Sias Renier
This section of the report is about the success of a dentist-supervised-at home LED gel tooth whitener, giving the results of a clinical study. The product (LED light gel with 44% carbamide peroxide) was applied by the dentist on teeth 11 and 21 in the chair for 10 minutes. The process was repeated three times, followed by an athome treatment period (30 minutes/day) of 14 days with 35% carbamide peroxide. The treatment was as outlined by the manufacturers. The L* value improved (more white) after the in-chair treatment with the LED system but showed no further significant increase after the 14 day at-home treatment. However, the b* value improved (less yellow), after both the LED treatment and 14 day athome treatment. The a* value did not improve significantly throughout the treatments. The LED system provides inchair tooth whitening after a 14 day treatment although not as effectively as does Opalescence.
Orthodontic molar brackets: the effect of three different base designs on shear bond strength
(Master Publishing Group, 2011) Hudson, Athol; Grobler, Sias Renier; Harris, Angela
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.
The pH Levels of different methamphetamine drug samples on the street market in Cape Town
(Hindawi Publishing Corporation, 2011) Grobler, Sias Renier; Chikte, Usuf; Westraat, Jaco
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.
The pH of various tooth whitening products on the South African market
(South African Dental Association, 2011) Majeed, Abdul; Grobler, Sias Renier; Moola, Mohamad H.
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.
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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