Thesis (M. Dent.(Orthodontics))--University of Limpopo (Medunsa Campus), 2010 / Good occlusion requires that teeth be proportional in size. If large upper teeth occlude with small lower teeth, it would be almost impossible to achieve ideal occlusion. The concept of ideal intercuspation assumes a strict relationship between tooth size and the size of maxillary and mandibular arches. Specific dimensional relationships must exist between the maxillary and mandibular teeth to ensure proper interdigitation, overbite, and overjet. It is important to determine the amount and location of tooth size discrepancies that may exist as a part of treatment planning. The relationship between maxillary and mandibular tooth sizes were established by Wayne A. Bolton in 1958 on a Caucasian sample. Bolton’s anterior ratio was 77.2% (SD 1.65) and the Bolton overall ratio was 91.3% (SD 1.91) (Bolton, 1958). Previous studies have shown that populations differ with respect to inter-arch tooth size relationships, and Blacks have larger teeth than Caucasians (Schirmer and Wiltshire, 1997; Khan, Seedat, and Hlongwa, 2007). A ratio that has been formulated on a Caucasian sample will over calculate or over predict tooth size discrepancies when used on a Black sample (Richardson and Malhotra, 1975; Smith, Buschang and Watanabe, 2000). The purpose of this study was to establish mesio-distal tooth width ratios for a select sample of South African Blacks. One hundred study models of untreated cases with excellent occlusion were obtained from the Department of Orthodontics archive records at the Medunsa Oral Health Centre, University of Limpopo. This sample were of South African Blacks (50 males and 50 females) selected according to a set criteria. The mesio-distal widths of permanent teeth up to and including the xvii first permanent molar in each arch were measured using a digital vernier caliper. The anterior and overall tooth width ratios were calculated on this sample. The mean, range and standard deviation were calculated for the size of the teeth, and a co-efficient of variation was obtained for the tooth size ratio. The results indicated that the male and female groups did not differ significantly and were therefore combined into one group. A 2-sample t-test was used to test for the statistical difference between means. The tooth size ratios obtained were compared to the Bolton’s ratios. Ninety five percent confidence intervals were calculated for the anterior and overall tooth width ratios for the select sample of South African Blacks. The anterior ratio was found to be 77.26% (SD 2.65), equivalent to Bolton’s anterior ratio 77.2% (SD 1.65), whereas the overall ratio was 92.31% (SD 2), significantly larger than Bolton’s overall ratio of 91.3% (SD 1.91). These results indicated that an overall tooth size ratio of this select sample differed from that of Bolton’s overall ratio and therefore, Bolton’s overall ratio may not be fully applicable to this select sample. KEY WORDS: Tooth size, tooth size discrepancy, Bolton’s ratios, South African Blacks.

Thesis (doctoral)--Universität Hamburg, 1979.

Thesis (M.Sc.(Dent.))--University of the Witwatersrand, Faculty of Health Sciences, 2012 / This retrospective research study evaluated the skeletal, dental, soft tissue profile and occlusal changes that took place in the craniofacial structures in the correction of Class II malocclusions using the Tip Edge technique and involving the extraction of first-premolars. These data were compared with those reflecting changes that took place in a similar sample which had been treated using an Edgewise technique and including the extraction of first premolars. Thirty Tip- Edge and thirty Edgewise cases were studied. Pre-treatment and end of treatment cephalograms of both samples were examined. Soft and hard tissue landmarks were identified and traced on each cephalogram. Twenty-four measurements were read using a special digital computerized system. The data were analyzed with the intention of determining the relative efficacy of the two treatment techniques under comparison. Data reflecting a one-year follow-up of the Tip Edge cases were also evaluated to assess the clinical stability as well as the cephalometric changes that had taken place. The changes in these data were statistically analysed and statistically compared. The second part of this research examined the characteristics of occlusion demonstrated on the pre- and post- treatment study models of both samples and graded the occlusions using the eleven components of the Peer Assessment Rating (PAR Index). The data were statistically analyzed to identify the degree of change that had occurred, pre- to post- treatment and to compare the changes effected by the two techniques. The first part of this study demonstrated that treatment with the Tip-Edge technique produced changes similar to those demonstrated by the Edgewise sample following treatment. However, the Tip-Edge cases enjoyed far greater incisal retraction than did the Edgewise cases. The upper incisor to NA and the lower incisor to NB angles for the Edgewise samples remained almost unchanged following treatment. The lower incisors in the Tip-Edge sample were positioned almost ideally after treatment. In the Tip Edge cases, the mandibular length increased on average by 7mm and this change was highly significant. The Edgewise cases demonstrated a decrease in maxillary length whereas the Tip-Edge cases displayed continuous growth during treatment. It appears that the maxilla was held back by the use of extra-oral traction in the Edgewise sample. The use of light elastic forces in the Tip-Edge sample does not appear to impede maxillary growth. The Y-axis, mandibular plane, occlusal plane and palatal planes were not altered to any significant extent in either technique, although the mandibular plane decreased in the Edgewise sample. Examination of the Tip-Edge cases one- year post-treatment demonstrated stability of the treatment effects and in some parameters, there were favourable improvements following “settling-in”. The Tip-Edge and Edgewise samples both exhibited similar favourable soft tissue changes. The assessment of occlusal characteristics demonstrated an average PAR index improvement of 90% following treatment for the Tip-Edge cases, whilst the Edgewise cases recorded an 80% change. The difference was significant. This study confirms that the Tip-Edge technique, together with first premolar extractions, is effective in the correction of Class II malocclusions when compared with a similar sample treated with an Edgewise technique. It produces comparable and stable, if not more favourable, changes.

Thesis (M.S.)--University of Michigan, Ann Arbor, 1972. / Typescript (photocopy). Includes bibliographical references (leaves 29-30). Also issued in print.

Thesis--Doctor of Public Health. The University of Michigan, School of Public Health, Department of Epidemiology. 1966. / Includes bibliographical references.

Thesis (M.S.)--University of Michigan, Ann Arbor, 1974. / Typescript (photocopy). Includes bibliographical references (leaves 50-52). Also issued in print.

Thesis (M.S.)--University of Michigan, 1965.

Thesis (M.S.)--University of Michigan, 1977.

Thesis (M.S.)--University of Michigan, 1965.

Thesis (M.S.)--University of Michigan, 1977.