Department of Orthodontics

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https://hdl.handle.net/10566/406

The discipline of Orthodontics focuses on the growth and development of the craniofacial complex and dental occlusion, and the treatment of abnormalities related to these structures.

The Department of Paediatric Dentistry conducts an undergraduate and a postgraduate programme to enable students to manage the child dental patient. The postgraduate programmes consist of a postgraduate diploma in dentistry part-time and a masters programme full time.

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The prediction of the size of unerupted canines and premolars in a contemporary orthodontic population
(1974-04) Tanaka, Marvin; Johnston, Lesley
Linear regression equations for the prediction of the mesiodistal widths of unerupted canines and premolars were calculated for a large sample of recent orthodontic patients. The form of the equations, as well as the size of the various confidence belts, were generally similar to those in the widely used but incompletely characterized Michigan Mixed Dentition Analysis. Although either set of tables would seem equally appropriate, a simple approximation— half the width of the mandibular incisors plus either 11.0 for the maxillary canine-premolar segments, or 10.5 for the mandibular segments— is of comparable accuracy. The
The Physical and Mechanical Aspects of Orthodontic Appliances
(University of the Western Cape, 1978) Bibby, R.E; Bibby, R.E
These laws were first published in Latin,in 1687.The first law may be literally translated thus, Every body continues in its state of reat or of uniform motion in a straight line ,unless it is compelled to change that state by impressed force. This meano that if a body is at rest it will remain so unless some force acts on it,if in motion ,the velocity of motion must continue uniform unless some force acts to increase it or diminish it. Also the direction of motioA mast continue unchanged and therefom rectilinear unless some force causes it to be diverted. This law therefore supplies us with a definition of force; Force is that which produces or tends to produce, motion 0.' change of motion. Newton's second law of motion may be translated as follows:- Newton's second law of motion may be translated as follows:- The change of motion (produced)is proportional to the impressed force producing it,and pursues the direction in which that force is impressed. This law leads to a method of measuring forces. If we change the velocity with which a mass is moving,we also change its momentum. Change in momentum will serve to measure force.lt seems obvious that whatever change in momentum is produced by a force, twice the force will produce twice the change ,etc.i.e. the change is directly proportional to the force. For a given mass,m,change of momentum ,mv,means change of velocity;the change of velocity per unit time is aceeleration,a;the change in momentum per unit time is therefore malf we employ absolute units (poundals or dynes)this can be shown as; Newton's third law of motion states that 'to every action there is an equaI and opposite reaction'.This law recognises the dual aspect of forces It a tooth is pushed by a finger spring ,the spring is also pushed by the tooth,and an eqpal counter force acts towards the spring unti1 the biology of the system intervenes. This dual stress is called pressure. Retracting incisors against posterior segments it is apparent that the reaction of the posterior segments must be equal and opposite to the incisors.In this case the two forces act away trom each other,and tG this dual stress we give the name tension.
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).
Research related to clinical dentistry (1967 - 1983)
(University of Stellenbosch, 1984) Retief, Daniel Hugo; Prins, F. X.
Four spectrophotometric procedures for the analysis of phosphorus were evaluated (1F1). The phosphorus concentrations in saliva and dentine were determined. All four analytical procedures were accurate but the one method was the most sensitive. An acid etch enamel biopsy procedure which was originally developed in Switzerland was modified in our laboratory (#2). It was subsequently shown by other investigators that the modified technique was much more accurate for the determination of the fluoride concentration in enamel than the original procedure.
A comparison of lay and professional opinion on treatment need and treatment outcome
(A comparison of lay and professional opinion on treatment need and treatment outcome, 1997) Vally, Ismail M.; Jones, M.L.
The psychological, social, and cultural aspects of facial and dental attractiveness is an integral part of health care. Lay persons perceptions of facial and dental attractiveness are influenced by many factors including age, gender, geographic location (nationally or international), ethnic status, employment status, cultural differences and social class will effect the social impact of the anomalies. In addition, the public response to dental anomalies will vary according to experience of good health or ill health of the individual, relatives and friends. The perception of malocclusion is often seen differently between orthodontists, patients and lay public. The differing perceptions of patients and dental practitioners may influence the delivery of orthodontic care. It has been reported that 70% of orthodontic treatment is dentist induced and that orthodontic treatment may be undertaken without the patient or parents perceiving a problem with the teeth. (DHSS, Schanscheiff Report, 1986). The thresholds of entry and exit for orthodontic care may be different as perceived by orthodontists and lay persons. Orthodontists may pursue full alignment and perfect occlusion whereas lay persons may accept varying degrees of deviation from normal. This current study has assessed and recorded the differences in opinions of professional orthodontists and lay persons on dento-facial aesthetics, orthodontic treatment need and orthodontic treatment outcome. The study was carried out at the Orthodontic Department, University of Wales, College of Medicine, School of Dentistry. The opinions of 56 lay persons (dental technicians, dental nurses and lay persons not involved in the clinical process) and 97 orthodontists was collected by recording judgements using various patient records as stimuli. For each set of records examined, each member of the panel indicated their opinion using Likert scales. Judgements were made by assessments of 68 study casts in respect of:- * the need for orthodontic treatment on dental health grounds. the need for orthodontic treatment on dental aesthetic grounds. deviation from normal occlusion. the decision whether to treat. ** * In addition, judgements were made on a sample of 50 pairs of outline facial profiles before and after treatment in respect of: * * deviation from normal facial aesthetics comparison of aesthetics pre-treatment and post-treatment. Furthermore, assessments on 50 pairs of pre-treatment and post-treatment study casts in respect of: * * degree of improvement as a result of treatment. acceptability of result. Orthodontists subjective judgements are more reliable than lay persons in their assessments of dental aesthetics, dental health and deviation from normal. The level of agreement for the decision to recommend treatment is similar between orthodontists and lay groups ie. lay persons are as reliable as orthodontists in the decision to recommend treatment. Orthodontists tend to recommend 10 - 12 % more treatment than lay persons. The orthodontist group were more reliable than the lay group in assessing degree of improvement and assessment of outcome. Orthodontists reject approximately 25% of cases deemed acceptable by the lay group. Dental aesthetics appeared to be the most important feature in the assessment of treatment outcome by both orthodontists and lay groups.
Applicability of tooth size predictions in the mixed dentition analysis in a Kenyan sample
(University of the Western Cape, 2004) Ngesa, James Lwanga; Theunissen, E.T.L; Shaikh, A.B; Dept. of Orthodontics; Faculty of Dentistry
Mixed denticentition space analysis forms a critical aspect of early orthodo However, the applicability of these methods in other ethnic groups has been varied and questionable. The aim of this study is to evaluate the accuracy of the Tanaka and Johnston (1974) and the Moyers (1988) methods in a Kenyan sample. Mesio-distal tooth widths of 131 sets of dental casts obtained from randomly selected patients (50 males; 81 females) attending Kenyatta National Hospital were measured. The mean sum of the four mandibular incisors was used to determine the sum of canine and the two premolars in one quadrant. The predicted values of the mesio-distal widths were statistically compared with their respective actual sum of the canine and premolars of the same quadrants. The results of paired t tests and scatterplots indicated that there were highly significant differences (p<0.003) between actual measurements (Σ 3, 4 & 5) and their accurate among the non-radiographic prediction methods in the mixed dentition analysis in the Kenyan sample. treatment. The two most widely used non-radiographic tooth size prediction methods were derived from populations of Northern European ancestry. predicted values from Moyers (1988) prediction method except at 85% and/or 95% confidence levels. However, Tanaka and Johnston (1974) failed to show any statistically significant differences for either sex and combined sexes at p<0.05. The Tanaka and Johnston (1974) method was the most SAMPLE .
Perception of occlusal appearance in 11 to 12 year-old school children in Nairobi, Kenya
(University of the Western Cape, 2004) Psiwa, Nathan Kitio; Shaikh, A; Ferguson, M; Lalloo, R; Dept. of Orthodontics; Faculty of Dentistry
A public orthodontic system generally is designed to prioritize patients so that those who have the greatest need receive treatment. The aim of this study was to compare the subjective perceptions of the occlusal appearance of 11 to 12 year-old schoolchildren of Nairobi with the modified Aesthetic Component (AC) scale of the Index of Orthodontic Treatment Need (IOTN). The objectives were to assess the children’s perception of their occlusal appearance, categorise the occlusal appearance using the AC scale, by both the children and researcher; and to compare the children’s’ perception and the AC of the IOTN.
A critique of the index of the complexity, outcome and need
(University of the Western Cape, 2005) Ferreira, Dominique Abergail; Ferguson, M; Dept. of Orthodontics; Faculty of Dentistry
The development of a uniform method of epidemiological assessment and grading of malocclusion has been of interest for several decades. Recently, Daniels and Richmond (2000) proposed a new orthodontic index namely the Index of Complexity, Outcome and Need (ICON). Their aim was to develop a single index for assessing treatment inputs and outcomes.The aim of this study was to critique the ICON and to assess to the extent to which each component of the ICON fulfils the ideal requirements of the ideal index as identified in a World Health Organization Report (WHO, 1966). The study was performed in three parts: 1) a gold standard was established to test reliability and validity of the ICON; 2) to assess ease of use and simplicity of the index; 3) and to test the applicability of the index on patients and study casts. The results showed that the ICON identified 25% of the cases as ‘no treatment’, as apposed to the 100% of the gold standard. Validity of the index was shown to be ‘poor’ for complexity (? = 0.2) and degree of improvement (? = 0.34) and ‘excellent’ for outcome. Reliability was high for all the components except for treatment need (? = 0.63). This study concluded that except for complexity and degree of improvement, the index performed well with respects to reliability, validity (of treatment outcome), ease of use and simplicity and applicability to patient and study casts.
Dental maturation of the permanent mandibular teeth of South African children and the relation to chronological age
(University of Western Cape, 2008) Phillips, Vincent; Nortjie, CJ
Age estimation of the skeletal remains of children can be accomplished by examination of the ossification centres and the fusion of the epiphyseal plates of long bones. Dental age estimation is done by examining the eruption of the deciduous and permanent teeth. Both these methods are inaccurate and are subject to the nutritional status of the individual. A more accurate method of age estimation is by the examination of radiographic images of the developmental stages of the tooth crown and root formation. Two methods of dental age estimation used are those of Moorrees, Fanning and Hunt (1963) (MFH) and that of Demirjian, Goldstein and Tanner (1973) (DGT). These methods were tested on a sample of 913 Tygerberg dental patients; a random mixture of Caucasoid and Khoisanoid children. The MFH method under-estimated the ages of the sample by an average of 0.91 years and the DGT method over-estimated the ages by an average of 0.89 years. Samples of Indian and Negroid children from Kwa-Zulu Natal were tested in a similar manner and the results showed similar under and over-estimation of the ages by these methods. The Negroid children were labelled the Zulu sample. Correction factors were derived for the MFH and DGT methods of dental age estimation when used on Tygerberg, Indian and Zulu children. These correction factors were tested on the samples and found to improve the accuracy of the age estimation methods of MFH and DGT significantly. A second sample group of Tygerberg, Indian and Zulu children were then tested firstly using the standard method of MFH and DGT and the using the correction factors. The results showed that the correction factors improved the age estimation on these samples except in the case of the DGT method on Zulu children. A sample of Xhosa speaking children were added to the two Zulu samples and made an Nguni sample. The Tygerberg samples were combined as were the Indian samples to form data bases for the construction of dental age related tables for Tygerberg, Indian and Nguni children. These tables show that there are distinct differences in the ages at which the teeth develop in the different sample groups and that dental age related tables are necessary for children of different population origins. Statistical analysis of the age related tables from this study (Phillips Tables) show these tables are more accurate in the age estimation of South African children.
Characteristics of children under 6 years of age treated for Early Childhood Caries at Tygerberg Oral Health Centre, South Africa
(Tufts University, School of Dental Medicine, 2008) Mohamed, Nadia; Barnes, Jo
Objective: This retrospective survey highlighted the characteristics of children less than six years of age presenting with early childhood caries(ECC) who had two or more teeth extracted under intravenous sedation at the Tygerberg Oral Health Centre in Cape Town, South Africa. This survey was carried out in order to plan a community-appropriate intervention strategy. Methods: Records of 140 patients kept by the pediatric Dentistry Division met the inclusion criteria and were included in this survey. Most of the patients originate from economically disadvantaged areas. Results: Diet, feeding and oral hygiene habits were shown to be the most significant factors that contributed to the development of ECC in these patients. All the children were either breast- or bottle-fed past one year of age. 93.6% of the children went to sleep with the bottle or while on the breast and 90% of them were fed on demand during the night. On average, breastfeeding was stopped at 9 months of age compared to bottle-feeding that, on average, was stopped at a much later mean age of 23 months. Where oral hygiene practices were concerned, 52.6% of children brushed their own teeth without supervision. Frequency of brushing varied between subjects. Conclusion: The results of this study have demonstrated that there is a need for culturally appropriate education campaigns to inform parents (especially those in disadvantaged communities) about the importance of oral health and the prevention of oral disease.
A comparison of two liner materials for use in the ferric sulfate pulpotomy
(South African Dental Association, 2008) Mohamed, Nadia
Objectives: The aim of this study is to compare the success rate obtained when applying either a calcium hydroxide (Dycal) base or a zinc oxide-eugenol (Kalzinol) base following the traditional ferric sulfate pulpotomy. Methods: Patients were either treated in the chair or under general anaesthesia. All teeth had to have radiographic evidence of caries close to the pulp. After haemostasis was achieved with damp cotton pellets, ferric sulfate was applied to the pulpal stumps. Half of the cases then received a Dycal base followed by a cured layer of Vitrebond and a permanent amalgam restoration. The other half of the cases received a base of zinc oxide-eugenol (Kalzinol) followed by an amalgam restoration. The cases were followed up every 6 months for one year (ie. 2 follow-up visits). Radiographs were taken at each follow-up visit. Results: Overall, teeth treated with Dycal demonstrated a higher failure rate when compared with those that received the Kalzinol base. Abscess formation and internal resorption were the most common causes of failure. Even though the Kalzinol base demonstrated greater success, there were still quite a few failures. Conclusion: This study demonstrates that calcium hydroxide cannot be recommended as a medicament in primary tooth pulpotomies.
Oral lesions in hiv/aids patients before and after haart treatment
(2009) Masiiwa, Antonette Musara; Naidoo, Sudeshni
The initiation of highly active antiretroviral therapy has shown to result in successful suppression of viral replications followed by an increase in CD4 lymphocytes, a partial recovery of T-cell specific immune responses and decrease susceptibility to opportunistic pathogens. Aim: The aim of the present study was to determine the prevalence of oral lesions in patients before and after undergoing HAART. Methods: The study design was longitudinal and descriptive, investigating the prevalence of oral lesions presenting in HIV/AIDS patients at baseline, 3 and 6 months after taking HAART. A convenience sample size of 200 participants was targeted. Results: 210 HIV positive patients participated at baseline. At 3 months, 96 (46%) and at 6 months, 52 (25%) were available for review respectively. At baseline 210 HIV positive patients were recruited into the study from three hospitals. Two infectious disease hospitals belonged to the City of Harare and the other is a government hospital. Just over two thirds were female (64.3%) and the age ranged as follows: 21-30 (17%); 31-40 (44%); 41-50 (26% and 51-60 (9%).Discussion: HAART appears to be effective in reducing the prevalence of oral lesions in persons with AIDS likely due to the immunological reconstitution. Oral candidiasis remains the most prevalent oral opportunistic infection in immuno-suppressed individuals and hence its important predictive value for immuno-suppression defined as CD4-cell count level <200/mL of blood. All oral lesions strongly associated with HIV infection with the exception of non-Hodgkin’s lymphoma were diagnosed at baseline. CD4 cell count level increased after initiation of HAART. T-lymphocytes that are formed after the introduction of HAART may not provide sufficient protection against some lesions like parotid gland disease and HPV conditions (planar warts). HAART failure was detected in some patients who had negative CD4-cell count at 6 months compared to the baseline parameters. Conclusions: HIV-positive patients experience oral pain during the course of their disease, eating, drinking and swallowing. Further longitudinal studies are required in order to ascertain the prevalence of these lesions at three and six months and the effect of HAART.
The mixed dentition pantomogram: A valuable dental development assessment tool for the dentist
(South African Dental Association, 2009) Hudson, Athol; Harris, Angela; Mohamed, Nadia
The mixed dentition pantomogram is routinely used in paediatric patients. This paper discusses the value of the pantomogram for early identification of problems in dental development during the mixed dentition stage. Aspects regarding dental maturity, leeway space, the sequence of eruption of the permanent teeth, anomalies and the development of the canines will be reviewed.
Factors influencing sorption, solubility and cytotoxicity of a heat cured denture base polymer
(2010) Engelbrecht, Magdalena Aletta; Geerts, G.A.V.M.
Objectives:Substances leaching from denture- base polymers have been associated with cytotoxicity and allergic reactions. This study examined the effect of polishing,mixing ratios, water immersion temperatures and different thicknesses on the sorption and solubility of a heat-polymerized, denture-base polymer. The effect of different water immersion temperatures on the flexural strength of the denture base, was tested as well. The next component of this study, is the testing of the most significant sorption and solubility findings on in vitro cell viability. Materials and Methods:Disc shaped specimens from a heat-polymerized, denture-base polymer (Vertex®) were prepared, based on ISO 1567 specifications for sorption and solubility testing, following the manufacturers’ instructions. The following tests were performed: 1) Sorption and solubility of two groups (n = 12 each) of polished and unpolished discs were established and compared by means of the Mixed procedure; 2) Sorption and solubility of three groups (n = 12 each) with different mixing ratios were compared by means of the Mixed procedure; 3) Four groups (n = 14 each) were immersed in water at different temperatures, sorption and solubility were compared by means of pairwise comparison and the Median test; 4) Specimens with different thicknesses (n = 36) were compared, again, by means of pairwise comparison and the Median test; 5) To test the influence of different water-soaking temperatures on the flexural strength of the disc, strips were prepared from the disc used in test no. 3. The flexural strength was compared, by means of the Median test; 6) To test the influence of no postpolymerization treatment, polishing and water immersion on the cytotoxicity of mouse fibroblast cells, (n = 9) for each test group, were prepared. A preliminary test was performed beforehand, over a period of 24 hours, up to a maximum period of four weeks. The Balb/c 3T3 mouse fibroblast cells were cultured and incubated for 24 hours in Eagles medium. Eluates prepared from the disc and medium without any disc (control) replaced the medium. Cytotoxicity was assessed by MTT-assay. Optical density values were obtained at 24 and 48 hour intervals. The data was analyzed by means of the Means procedure.Results:In the entire thesis, the data was analyzed using SAS on a 0.01 probability level.Between polished and unpolished groups, no significant difference in water sorption (p> 0.01) was found, but there was a difference in solubility (p<0.01).Different mixing ratios did not alter sorption (p = 0.34) or solubility (p = 0.68).However, a difference (p<0.01) in sorption and solubility was found among the different temperature and thickness groups. Soaking the denture base in water at different temperatures did not alter its flexural strength (p = 0.48). Cell viability levels were noted in all the experimental groups in the MTT assay test. The analysis was a two-factor study, with one factor being the group, and the other, being time. The interaction between these factors was found to be significant, indicating that the effect of the groups varied by time (and vice versa).Conclusion:The processes of the soaking in warm water and the polishing of a denture-base polymer, reduce its solubility. Therefore, it is recommended that dentures are soaked in warm water before polishing. Within the limits of this study, the mixing ratios may be changed without affecting sorption or solubility. As solubility increases within the increasing denture-base thickness, it is recommended that unnecessarily thick dentures be avoided.Short- and long-term exposure to eluates of a PMMA, has a negative effect on cell viability. For water-stored and polished discs, this effect is time-dependent, with a higher viability for 48 hours’, than for 24 hours eluates. Polishing is associated with lower solubility. At 24 hours, the polished discs, indeed, had a lower cytotoxic effect than the untreated discs: it may be recommended that dentures be polished on the fitting surface as well.The cytotoxic potential of PMMA-eluates appears to fluctuate over time.
Maxillary canine management in the pre-adolescent: A guideline for general practitioners.
(South African Dental Association, 2010) Hudson, Athol; Harris, Angela; Mohamed, Nadia
This paper focuses on the identification of ectopic eruption patterns of the maxillary canines from the dental ages of approximately 8 to 12 years. The timing and suitability of interceptive treatment in pre-adolescents are discussed.
Early identification and management of mandibular canine ectopia
(South African Dental Association, 2011) Hudson, Athol; Harris, Angela; Mohamed, Nadia
Mandibular canine impaction and transmigration have serious consequences for the patient, as removal of the tooth or teeth in question is often the only solution. The loss of one or both mandibular canines complicates orthodontic treatment. Early warning signs of mandibular canine ectopia are explored in this paper as well as how to assess the potential for displacement, impaction and/or transmigration. This paper highlights the value of interceptive treatment once the early signs of an aberrant mandibular canine have been detected.
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.
Accuracy of orthodontic digital study models
(University of the Western Cape, 2012) Kriel, Earl Ari Mac; Harris, Angela Manbre Poulter; Johannes, K.C.
Background: Plaster study models are routinely used in an Orthodontic practice. With the recent introduction of digital models, an alternative is now available, whereby three dimensional images of models can be analyzed on a computer. Aims and objectives: The aim of this study was to compare the measurements taken on digital models created from scanning the impression, digital models created from scanning the plaster model, and measurements done on the plaster models. The objectives were: Measurement differences between those taken directly on plaster models compared with measurements on digital models created from scanned impressions and digital models created from scanned plaster models. Methods: The study sample was selected from the patient records of one Orthodontist. They consisted of 26 pre-treatment records of patients that were coming for orthodontic treatment. Alginate impressions were taken of the maxillary and the mandibular arches. Each impression was scanned using a 3Shape R700™ scanner. Ortho Analyzer software from 3Shape was used to take the measurements on the digital study models. Within 24 hours plaster study models were cast from the impressions, and were scanned using a 3Shape R700™ scanner. On the plaster models the measurements were done with a MAX-CAL electronic digital calliper. The mesiodistal width as well as intermolar and intercanine width for both the maxillary and mandibular models were recorded.Results and discussion: Box plots used to compare the variability in each of the three measurement methods, suggest that measurements are less variable for Plaster. Plaster measurements for tooth widths were significantly higher (mean 7.79) compared to a mean of 7.74 for Digital Plaster and 7.69 for Digital impression. A mixed model analysis showed no significant difference among methods for arch width. Conclusions: Digital models offer a highly accurate alternative to the plaster models with a high degree of accuracy. The differences between the measurements recorded from the plaster and digital models are likely to be clinically acceptable.
Perceptions regarding the shortened dental arch among dental practitioners in the Western Cape Province, South Africa
(South African Dental Association, 2012) Khan, Saadika; Chikte, Usuf; Omar, Ridwaan
AIMS and OBJECTIVES: This survey was conducted to de-termine the knowledge of and opinions related to the short-ened dental arch (SDA), among dentists in the Western Cape Province, South Africa. METHODS: The study sample included two consecutive groups, drawn by a process of randomisation from the reg-istered dentist population that included general dentists, specialists, those who had emigrated and retired dentists. A self-administered questionnaire was mailed, e-mailed and/or faxed to those selected. Reminders were either e-mailed or made by telephone over a period of six months. RESULTS: A final sample of 84 respondents with a mean age of 43 years (SD=11.9) was obtained. This represented a response rate of 23% (n= 84) from the final working sample (n=368), derived from the target group (n=618) originally con-tacted. All participants completed an informed consent form in which confidentiality was assured. Several respondents (40%) said they had heard about the SDA while at university, which would be in line with the age range of respondents in relation to introduction of the concept into dental curri-cula. As many as 62% had never read any research articles related to the concept which could partly account for the low response rate. The majority (86%) felt that patients can function with a SDA and that they would recommend ac-ceptance to their patients. CONCLUSION: Respondents know of the potential benefit that the SDA may have for their patients and see it as a viable alternative treatment option for the partially dentate patient, even though their level of current knowledge of the subject must be considered questionable.
Introducing dental students to e-learning at a South African University
(Health and Medical Publishing Group, 2012) Mohamed, Nadia; Peerbhay, Fathima
This article serves to report on the introduction of an innovative ‘blended learning’ approach in the Paediatric Dentistry Department at the University of the Western Cape (UWC) in Cape Town, South Africa. This intervention was the first of its kind to be introduced at UWC’s dentistry faculty. Methods Educational resources were placed online to supplement didactic and clinical teaching and in so-doing, compensate for the lack of chair side teaching. An online learning platform was thus provided for students to engage with. Results Forty-seven percent of students accessed the site. The evaluation of the course by these 4th and 5th year students was mostly positive. Students who did not access the site provided a variety of reasons for not doing so, with the main reasons being the ‘lack of time’ (40%) and ‘lack of IT resources’ (41%). Conclusion This intervention highlighted the fact that ‘blended learning’ definitely has its place in the dentistry curriculum, especially if minor issues like access to resources can be addressed. The Paediatric Dentistry department at the University of Western Cape is continually pursuing current trends in teaching to provide an education that is on par with global standards.

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