Melbourne Dental School - Theses
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ItemEffectiveness and efficiency: systematic reflections on single- and multiple-visit root canal treatment( 2008)Single-visit root canal treatment was first documented in 1887. The controversy and debate within the dental community has been ongoing for over a century without resolution. The concept of evidence-based health practice has provided a structure on which the clinically-relevant questions in this debate can be dealt with systematically. When clinicians are faced with choices of which treatment regimen should be offered to patients, the central issues that should be considered are effectiveness, complications, patient/operator preference/satisfaction, and cost. Systematic review and meta-analysis techniques were used to reach definitive conclusions where high quality primary studies are available. The issue of satisfaction was studied using a quality of life concept, while the issue of cost was addressed by an economic evaluation (cost-minimization analysis). Treatment effectiveness and complications of single- and multiple-visit approach were similar. Patients overwhelmingly preferred single- over multiple-visit treatment with high satisfaction scores for both regimens. Australian endodontists were reluctant to embrace single-visit root canal treatment. Single-visit root canal treatment costs society less than multiple-visit treatment. On balance single-visit treatment offers substantial advantages with no identified adverse effects.
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ItemFactors affecting fracture susceptibility of tooth root: a laboratory and finite element analysis (FEA) study( 2004-11)From a fracture mechanics viewpoint, structural defects, cracks or canal irregularities are likely to play a major role in fracture susceptibility of the roots, because stresses can be exponentially amplified at these sites. By incorporating defects into a smooth round canal using rotary NiTi, theoretically the roots could be strengthened. The aims of the study were to determine whether rotary NiTi canal preparation strengthens roots, and whether the fracture pattern can be predicted by finite element analysis (FEA) models. 25 teeth were prepared using hand file and another 25 using rotary NiTi. After obturation, all teeth were subject to loading until fracture; load and patterns were recorded. Four FEA models were created from fractured roots. No significant difference of fracture load between the two techniques was found. Mesio-distal fracture occurred more often in the rotary NiTi group. Stress patterns in three of the four FEA models correlated well with the observed fracture patterns. The aim of the subsequent study was to determine the extent to which canal size, radius of curvature and proximal root concavity influence fracture susceptibility and pattern. A standardized cross-section of the mid-root region of a mandibular incisor was created by averaging the dimensions of ten extracted teeth, and the basic FEA model was created. By varying canal diameter, shape and proximal concavity, these factors could be examined for roles in fracture susceptibility and pattern. The factors all interact in influencing fracture susceptibility and pattern, with dentine thickness not the only determining factor. The removal of dentine does not always result in increased fracture susceptibility.