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Biomedical subjects

W A Wiltshire

Publications and source records attributed to W A Wiltshire.

At least 19 recordsLinked to original sources
PubMed2001

Fluoride release from new light-cured orthodontic bonding agents.

The purpose of this study was to compare the rates of fluoride release with time from 1 nonfluoridated and 3 fluoride-containing orthodontic bonding materials in distilled water and artificial saliva. Materials tested were Assure (Reliance Orthodontic Products, Itasca, Ill), Fuji Ortho LC (GC, Tokyo, Japan), Python (TP Orthodontics, LaPorte, Ind), and Transbond XT (3M Dental Products, Monrovia, Calif). Ten specimens of each material type were stored in distilled water, and 10 of each type were stored in artificial saliva at 37 degrees C. Fluoride release was measured with an ion-specific electrode. Readings were taken periodically for a total time period of 6 months. At day 1, Assure released the most fluoride into distilled water (66.2 microg/cm(2)) and into artificial saliva (65.8 microg/cm(2)), followed by Fuji Ortho LC (25.9 microg/cm(2); 18.8 microg/cm(2)), Python (6.3 microg/cm(2); 4.2 microg/cm(2)), and Transbond (0.1 microg/cm(2); 0.1 microg/cm(2)). The fluoride release rates were highest during the first days of testing, declining to lower but more stable levels. At the end of 6 months, Fuji Ortho LC released the most fluoride (3.8 microg/cm(2); 3.5 microg/cm(2)) followed by Assure (3.1 microg/cm(2); 2.8 microg/cm(2)), Python (2.6 microg/cm(2); 1.7 microg/cm(2)), and Transbond (0.1 microg/cm(2); 0.1 microg/cm(2)). The type of storage medium did not dramatically affect fluoride release. The second part of the study, undertaken after a year of sample storage, tested the 20 samples of Assure for a further 2-week period, after exposure to running and still distilled water. Although fluoride release rates declined with time, they were still higher than the 1.5 microg/cm(2) level that is referenced as inhibiting decalcification of enamel in a clinical environment. Release rates were similar in running and still water at all time points. Throughout the 6-month period, all 3 fluoride-containing materials had rates of fluoride release that could theoretically inhibit decalcification of enamel.

Acrylic Resins↗
PubMed2000

Occlusal and oral health status of a group of 3-8-year-old South African black children.

This study determined the oral health status of a group of 3-8-year-old South African black children, comprising a total of 214 children from the townships of Garankuwa, Shosanguwe, Mabopane, Hebron and Erasmus who attended a school in Akasia, Greater Pretoria Metropolitan Substructure. The decayed, missing and filled teeth (dmft), oral hygiene status, dental IQ and malocclusion status were determined. The study found that the children's oral health status and occlusal status were unacceptable. The level of their dental IQ scores was low, their oral hygiene poor, and they were in urgent need of primary and secondary dental care. In addition they were in need of both preventive and interceptive orthodontic care. A national strategy to address primary dental health care is recommended.

Ankylosis↗
PubMed1999

In vitro and in vivo fluoride release from orthodontic elastomeric ligature ties.

Clinically, demineralization of enamel around orthodontic attachments can occur after only 1 month. Fluoride incorporation into elastomeric ligature ties may provide additional protection against decalcification through fluoride release. This study compared the fluoride release of fluoride-impregnated and nonfluoride elastomeric ligature ties (Ortho Arch Company) both in vitro and in vivo. A total of 260 fluoride-impregnated and 260 nonfluoride elastomerics were evaluated in this study, 400 in vitro and 120 in vivo. For the in vivo part of the study, six patients had fluoride and nonfluoride elastomerics placed in cross-quadrant fashion in their mouths; these were removed and tested for residual fluoride release after 1 month. With the use of the potentiometric analytical method, the fluoride release of the elastomerics was determined in distilled water as the 24-hour residual release, to compare the in vitro and in vivo fluoride leached into solution. The data was analyzed with the Wilcoxon matched-pairs signed ranks test. The distilled water control yielded an F- reading of 0.03 +/- 0.01 microgram/F/mL. In the in vitro part of the study, an average of 0. 38 microgram/F/mL/elastomeric was released over the 1 month period by the fluoride-impregnated elastomerics; this decreased significantly (P <. 05) to a 24-hour residual value at 1 month of 0.02 microgram/F/mL/elastomeric ligature, which is in the same order of magnitude as the distilled water control solution. The nonfluoride ties produced a calculated 24 hour residual fluoride release of 0. 003 microgram/F/mL/elastomeric after 1 month; this is much less than the distilled water control and would not be possible to measure accurately. After 1 month in vivo, significantly greater (P >.05) amounts of 24-hour residual fluoride were apparent: F- elastomerics = 1.43 microgram/F/mL/elastomeric and nonfluoride elastomerics = 0.44 microgram/F/mL/elastomeric. Fluoride ties gained weight intra-orally. Residual, leachable fluoride was present in fluoride-impregnated and nonfluoride elastomeric ligature ties after 1 month of intraoral use, due to imbibition. The clinical efficacy of fluoride-impregnated elastomeric ligature ties to prevent decalcification in the presence of plaque needs to be investigated.

Female↗
PubMed1998

The epidemiology of malocclusion in Zambian urban school children.

This survey was undertaken to determine the occlusal status of a selected group of urban Zambian Black 9-12 year old children at 5 different schools in the same geographical area in order to determine their need for orthodontic treatment. The examination criteria of the Occlusal Index of Summers (1966) were used. Six hundred and one children who had not previously received orthodontic treatment were examined. The data were analysed statistically by using the calculated Summers Index. The results showed that 83 per cent of the subjects required no orthodontic treatment. Of the 17 per cent who did require orthodontic treatment, 5.2 per cent needed specialized treatment. The malocclusion status of Black Zambian children is very similar to that recorded in epidemiological studies on South African and Swazi Black children. This study indicates that only a small need exists for orthodontic treatment amongst Black Zambian children.

Black People↗
PubMed1997

Orthodontic probability tables for black patients of African descent: mixed dentition analysis.

Mixed dentition space analyses form an essential part of orthodontic diagnostic procedures to determine the amount of space available for the accommodation of permanent teeth. The Moyers' probability tables for computing the sizes of unerupted canines and premolars were formulated at the University of Michigan from a sample consisting of northern European white subjects and are currently used worldwide. Because tooth sizes vary significantly between different population groups, it was the purpose of this study to construct relevant probability tables that would be more applicable to black subjects. Data were collected from a series of 100 randomly selected study models of black patients. The sample was equally subdivided by gender and all subjects had Angle Class I molar relationships with only minor malocclusions such as minor crowding, rotations, or diastemas. Two investigators independently measured the teeth on the study casts with a Vernier gauge that had sharpened calliper tips. Intraexaminer and interexaminer reliability was determined at 0.2 mm. All teeth to and including the first molars were measured. These data were then utilized in regression equations for both maxillary and mandibular arches, to enable the prediction of the mesiodistal widths of the canines and two premolars. The equations and predicted values were compared with those of the Moyers' probability tables, and significant differences (p <0.05) were found (except for the prediction of maxillary canines and premolars in females at the 85 and 95 percentile probability level). New probability tables for black subjects were formulated. It is envisaged that the proposed probability tables would be more accurate for black patients of African ancestry.

Adolescent↗
PubMed1997

Manual and computer-aided space analysis: a comparative study.

Recently, computers have been used to measure key landmarks from photocopies of upper and lower study models to increase simplicity, accuracy, and informatics. This is a comparative study to evaluate the accuracy and reliability of computer-aided space analysis. Data were collected from a series of randomly selected study models. All subjects had Angle Class I molar relationships with minor malocclusions such as crowding, rotations, or diastemas. Two investigators independently measured teeth on models with a Vernier gauge that had sharpened caliper tips. Intraexaminer and interexaminer reliability was determined at 0.2 mm. All teeth, to and including the first molars, were measured. Two photocopies of each set of models were made on a photostat machine (Xerox, Japan) and were coded. A template with a ruler was used, to allow the investigator to compensate for any reduction or enlargement error during the photocopying process. The mesiodistal sizes were measured with a digitizer, and results were processed by using a dedicated computer program. Evaluations were done in a double-blind manner. The nonparametric Wilcoxon signed rank test for paired observations to compare median differences between measurements was used. Intraexaminer digitized measurements were almost identical and differed (p < 0.0001) for only one measurement. However, interexaminer manual and digitized measurements differed significantly (p < 0.001) for 20 of the 24 teeth. Nineteen of these digitized tooth measurements were smaller. The mean arch length measurements differed by 4.7 mm (p < 0.0001) in the maxilla and by 3.1 mm (p < 0.0001) in the mandible. The difference between the manual and digitized analyses may be due to the photocopying process. The inability to accurately measure a three-dimensional study cast that has been duplicated in two dimensions, convex structure of teeth, curve of Spee, tooth inclination, and tooth position may play a role. The computer-aided measuring system is reliable, but accurate mesiodistal measurements cannot be made from photocopies of dental models. Manual measurements that use a calibrated gauge produce the most accurate, reliable, and reproducible results.

Calibration↗
PubMed1996

Determination of fluoride from fluoride-releasing elastomeric ligature ties.

Unaesthetic white spot lesions or larger unsightly areas of decalcification around orthodontic brackets remain a significant problem during fixed appliance treatment. This study determined the in vitro fluoride release from 200 fluoride-containing elastomeric ligature ties. With the potentiometric analytic method, the fluoride release was determined in distilled water, for 10 groups of 20 elastomerics, representing the clinical usage in a patient. Readings were taken every 24 hours for 5 days and then every second week for 6 months. The data were analyzed with the Wilcoxon matched pairs signed ranks test. Fluor-I-Ties (Ortho Arch Company Inc., Hoffman Estates, III.) released significant amounts of fluoride compared with the control readings. The fluoride release was characterized by an initial burst of fluoride during the first day and second day, followed by a logarithmic decrease. By the end of the second week 88% of the total fluoride had been leached from the elastomerics, but adequate magnitudes of fluoride were released over the remainder of the test period to aid theoretically in the prevention of demineralization and enhance remineralization of enamel through calcium fluoride and fluorapatite formation. For optimum clinical benefit, Fluor-I-Ties should be replaced monthly. Future prospective longitudinal clinical studies are indicated.

Apatites↗
PubMed1996

Allergies to dental materials.

Allergies related to dentistry generally constitute delayed hypersensitive reactions to specific dental materials. Although true allergic hypersensitivity to dental materials is rare, certain products have definite allergenic properties. Extensive reports in the literature substantiate that certain materials cause allergies in patients, who exhibit mucosal and skin symptoms. Currently, however, neither substantial data nor clinical experience unequivocally contraindicate the discontinuance of any of the materials, which include dental amalgam and nickel- and chromium-containing metals. The dentist forms a vital link in the team approach to the differential diagnosis of allergenic biomaterials that elicit symptoms in a patient, not only intraorally, but also on unrelated parts of the body.

Acrylic Resins↗
PubMed1995

Fluoride release from four visible light-cured orthodontic adhesive resins.

Decalcification of enamel during fixed orthodontic appliance treatment remains a problem. This study determined the in vitro fluoride (F) release from four light-cured orthodontic adhesives since cariostatic potential of such adhesives is related to their F releasing ability. Two nonfluoride and two fluoride-containing adhesives were tested. By means of the potentiometric analytical method, the F release of each resin was determined daily for 7 days and thereafter weekly for a month and then monthly until week 85. The data were analyzed with Kruskal-Wallis, Mann-Whitney, and Wilcoxon matched-pairs tests. The F release of all the resins were characterized by an initial burst of F release during the first day, followed by a tapering down in magnitude. FluorEver (MacroChem, Billerica, Mass.) outperformed the other adhesives in all aspects of F release and continued to release F for up to 85 weeks. Fluorapatite formation resulting from F release from orthodontic adhesives could be more advantageous in reducing decalcification during fixed appliance treatment than other preventive modalities.

Adhesives↗
PubMed1995

The status of the developing occlusion of 8-9 year-old children from a lower socio-economic group in a developing country.

The aim of this study was to determine the percentage of developing malocclusions that are present at the age of 8-9 years. This data will be used for a follow-up study on the same sample two years hence, in order to formulate soundly based recommendations to Public Health Authorities on the implementation of a community directed, preventive and interceptive orthodontic programme. A total of 936 children were examined by 3 investigators, at 9 primary schools in the lower socio-economic suburbs of a large urban area. The majority of subjects (66.5 per cent) presented with Class I malocclusions. A significantly higher percentage of white children however, presented with Class II malocclusions, while black children showed a higher tendency toward Class III malocclusion. Well circumscribed anterior openbites were found in 27.8 per cent of black children, but no specific causative factors could be identified. Early loss of primary molars and canines occurred in both groups. There was a statistically significant difference (p < 0.05) between the mean posterior arch lengths of the two groups, the black children having on average 2.2 mm longer arch lengths.

Child↗
PubMed1994

Shear bond strengths of a glass ionomer for direct bonding in orthodontics.

This study was undertaken to compare the shear bond strengths of mesh-backed orthodontic buttons bonded to human enamel using a glass ionomer marketed for direct bonding in orthodontics, both in conjunction with, as well as without, enamel etching and to compare the results with a no-mix composite bonding resin. Freshly extracted noncarious human premolar crowns were used, to which mesh-backed metal orthodontic buttons were bonded to the lingual surfaces with one of three methods: group 1, glass ionomer without enamel etching; group 2, glass ionomer with enamel etching; and group 3, with a no-mix orthodontic bonding resin with enamel etching. After being stored in water for 48 hours at 37 degrees C, the samples were tested to failure in an Instron with the Bencor testing system. The data were statistically analyzed with the Mann-Whitney U test. The debonded specimens were visually inspected in respect of failure mode. The no-mix bonding resin had a significantly higher shear bond strength than the glass ionomer cement. Enamel etching with 37% orthophosphoric acid increased the mean shear bond strength of the glass ionomer, however, not significantly. Less cement remained on enamel after debonding when the glass ionomer was used when compared with residual resin when the no-mix bonding resin was used. Clinical research by several investigators is advised to determine the bond failure rate of glass ionomers when used in conjunction with orthodontic bracket bonding.

Acid Etching, Dental↗
PubMed1994

The effect of soft laser irradiation on fluoride release of two fluoride-containing orthodontic bonding materials.

Laser technology offers new treatment possibilities in dentistry. The effect thereof on dental biomaterials is however not yet known. Two fluoride (F) containing orthodontic bonding materials were investigated in this study. Group A = FluorEver OBA (Macro Chem) and group B = Light-Bond (Reliance Orthodontic Prod. Inc.). A galium arsenide aluminium (Ga As Al) low level laser with an energy transmission of 5.45 J (30 mW for 180 seconds) and an energy density of 27.54 J/cm" was used to irradiate the orthodontic bonding materials. SEM evaluation showed that the laser irradiation had no superficial physical ultrastructural effects on either of the two materials. In addition, the F release of Group A could be enhanced for up to seven months by a sole laser treatment (p < 0.05). Although the F release in the lased Group B was also higher, it was not statistically significant (p > 0.05). The difference in the F release of the two materials after laser irradiation may be due to differences in the composition of the orthodontic bonding materials, but cannot be adequately explained.

Dental Cements↗
PubMed1994

The occlusal status of disabled children.

The occlusal status of children in 6 schools for the handicapped was determined using the Occlusal Index (O.I.) of Summers (1966). Two dentists examined 381 children who had not previously received orthodontic treatment. An additional questionnaire investigating treatment interests and habits was also completed for each child. The study showed that 74,5 per cent required treatment, 10,5 per cent had good occlusions and 15 per cent had slight malocclusions where treatment was not considered essential. The mean O.I. was 7,92 +/- 4,33. Schools with mainly cerebral and mentally disabled children had a slightly higher O.I. but the difference in values was not statistically significant. The analysis also showed that 40,6 per cent of children were interested in receiving orthodontic treatment, but only 0,5 per cent were planning to seek it. There is a need for orthodontic treatment amongst disabled children and this should be taken into account in future oral health care planning.

Adolescent↗
PubMed1992

The occlusal status of an urban and a rural Venda group.

The occlusal status of Venda school children of the town of Thohoyandou, and of a rural community in the Tshikundamalema district was determined. This comparison made it possible to eliminate racial differences as a contributing factor to malocclusions. The occlusal index of Summers was used to determine the occlusal status of 342 subjects. Positive O.I. scores were obtained for 78.9 per cent of the subjects. Twenty-eight per cent of the children required orthodontic treatment and 12 per cent treatment of a specialised nature with fixed appliances. Syndrome D (tooth displacement) occurred in 42 per cent of those requiring treatment. Class I molar relationships were seen in 96.8 per cent. The difference in positive O.I. scores between urban and rural children was highly significant (p < 0.01). The mean O.I. scores also differed significantly (p < 0.05) between the two communities. A highly significant difference (p = 0.0002) in orthodontic treatment needs was also demonstrated between urban and rural children. This study shows that environmental factors and extraction of teeth in areas where a comprehensive dental service is not available could contribute to malocclusion.

Adolescent↗
PubMed1990

Staining of light-cured aesthetic resin restorative materials by different staining media: an in vitro study.

Aesthetic restorative resins have been characterised by clinical discolouration. New light-cured anterior and posterior resins are currently available to the profession and this study investigated the in vitro colour stability at 24 hours and 7 days of ten such resins in three different staining media. Disc specimens were prepared and stained at 37 degrees C and 100 per cent R. H. and then evaluated by double blind visual assessment. All the materials undergo some staining in coffee and red wine. Coca-Cola, however, does not cause any staining of the restorative resins. Adaptic II is the most stain-resistant material and most of the staining occurs within the first 24 hours after immersion in the staining media.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1990

[In vitro uptake of fluoride from South African fluoride gel dentifrices].

An increasingly difficult situation in obtaining imported products has led to the development of a locally-manufactured topical fluoride gel. In order to evaluate the anticariogenic potential of the gel an in vitro study was conducted to compare the fluoride (F) uptake into the enamel from the locally-manufactured gel with that of two overseas products. Sound, unerupted third molar teeth were used in the study. One half of the buccal surface of each tooth was used as a control and the remaining half for conducting the experiment. Enamel biopsies (0.5 N HCLO4 3,143 mm2; 15 sec) were conducted prior to the F treatment (control halves) as well as 24 hours after F treatment (experimental halves). The fluoride concentrations ([F]) of the etching solutions were analyzed according to the potentiometric analytical method. The calcium concentrations were determined by means of a flame spectrophotometer. The [F] of the control halves of the teeth were used as a reference to determine the actual F uptake in the experimental halves after F treatment. The results obtained from the study showed that the teeth treated with the locally-manufactured F gel, revealed a significant uptake of fluoride in the enamel as well as an increased resistance to acid dissolution. Only one of the imported products showed a statistically significant higher fluoride uptake than the acidulated South African manufactured phosphate fluoride gel. There was a favourable overall comparison of the locally manufactured F gel with that of the overseas products.

Dentifrices↗
PubMed1990

Orthodontic treatment in general dental practice in South Africa.

There is an increased demand for orthodontic treatment in South Africa and the general practitioner is showing increasing interest in implementing orthodontic treatment in private practice. The present study investigated the scope of orthodontics undertaken by the private practitioner in South Africa, in order to study the desirability of more comprehensive undergraduate training in orthodontics and continuing education for general practitioners. A questionnaire was completed by 1,012 dental practitioners. The data were analysed statistically by means of the SAS software. The results indicated that general practitioners are engaged in a wider range of orthodontic treatment modalities. The competence of the general practitioner to treat the spectrum of dental malocclusions and the ability of continuing education courses to produce "instant general-practitioner orthodontists", remains a cause for concern. Curricular restructuring requires realistic surveying of sociodemographics, including changes in birthrate and the need and demand for orthodontics in the unique South African situation, if it is to be the goal of the profession to strive for the highest standards. The educational institutions in South Africa should give attention to realistic orthodontic curricular restructuring in view of the changing dental treatment patterns currently being experienced in this country.

Education, Dental, Continuing↗