Theses and Dissertations (Dentistry)

The effect of different composite shades and curing distances on the depth of cure of the low shrink Filtek Silorane composite compared to Filtek Supreme XT and Z100

Wed, 01 Jan 2014 00:00:00 GMT

The effect of different composite shades and curing distances on the depth of cure of the low shrink Filtek Silorane composite compared to Filtek Supreme XT and Z100 Mistry, Jyotika The importance and demand for aesthetics has resulted in an increase in tooth-coloured restorations in dental practice. Composite undergoes polymerization using a curing device, after which it gains its physical and aesthetic properties. An improperly cured composite restoration is weak and prone to discolouration and secondary decay. The aim of this study was to determine and compare the effect that composite shade and curing distance would have on the depth of cure (DOC) of composite Filtek Silorane, Filtek Supreme XT and Z100. The scrape and penetrometer techniques were used to determine the DOC of the 450 specimens prepared. The DOC decreased with an increase in the curing distance and the darker shade had a lower DOC than the lighter shade for each of the composites tested. Both the scrape and penetrometer techniques yielded similar results in the DOC. Z100 had the highest DOC followed by Supreme XT and lastly Silorane. Thus a lighter composite shade in posterior teeth (non-aesthetic zone) and in deep Class II cavities will ensure an optimal depth of cure. The curing distance should be minimal and as close as possible to the composite surface to achieve an optimal depth of cure. Thesis (M Dent(Operative Dentistry))-- University of Limpopo, 2012.

Cranial base flexion and skeletal jaw relationships in a sample of black South Africans

Sat, 01 Jan 2011 00:00:00 GMT

Cranial base flexion and skeletal jaw relationships in a sample of black South Africans Nyakale, Mandla Dominic Introduction: Flexion of the cranial base plays a very crucial role in the study of the craniofacial complex, particularly with the development of skeletal jaw relationships. An understanding of growth of the cranial base has come to assume great importance in orthodontics, and successful treatment of skeletal jaw malrelationships depends largely on the growth and flexion of the patients' cranial base. The aim of this study was to determine the relationship between cranial base flexion and skeletal jaw relationships in a sample of Black South Africans. Materials and method: The sample comprised of 300 pre-treatment lateral cephalograms of Black South Africans which was equally divided into Class I, Class . II and Class III skeletal jaw relationships according to the cephalometric tracing and analysis, and each class of skeletal jaw relationship had an equal number of male and female subjects. A digital cephalometric analysis software program (Orthview 0.05). There were no statistically significant differences between the mean cranial base flexion values of the male and female subjects in all the three classes of skeletal jaw relationships (p > 0.05). The results of this study demonstrated a significantly larger mean cranial base flexion value in the Class II skeletal jaw relationship sample when it was compared with the mean cranial base flexion values of Class I and Class III skeletal jaw relationship samples respectively (p < 0.05). There was no statistically significant difference between Class I and Class III skeletal jaw relationship samples with regards to the cranial base flexion (p> 0.05). The results of this study also showed no statistically . significant difference between the average cranial base flexion values of Black South Africans of the present study as well as Black and Caucasian South Africans of the previous study (p > 0.05). Conclusion: It was concluded that, in this sample, a larger cranial base flexion value is a feature of Class II skeletal jaw relationship and a smaller cranial base flexion value is a feature of both Class I and Class 11\ skeletal jaw relationships. Keywords: cranial base flexion, skeletal classification, skeletal jaw malrelationship Thesis (M Dent (Orthodontics)) -- University of Limpopo, 2011

Prevalence of impacted mandibular third molar teeth at Medunsa Oral Health Centre

Sun, 01 Jan 2012 00:00:00 GMT

Prevalence of impacted mandibular third molar teeth at Medunsa Oral Health Centre Tsabedze, Vusumuzi Ndumiso Thesis (M.Dent.(MFOS))-- University of Limpopo, 2012

Bolton ratios on a sample of South African blacks

Fri, 01 Jan 2010 00:00:00 GMT

Bolton ratios on a sample of South African blacks Singh, Shivani 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 (M. Dent.(Orthodontics))--University of Limpopo (Medunsa Campus), 2010