Quantifying Machining Outputs Relevant to the Removal of Dental Caries in Human Teeth

Dental caries are a common ailment affecting human teeth. The short supply of locally-trained dentists in developing countries places a socio-economic burden on their communities. A possible solution to this problem is to explore minimally-assisted tooth repair systems that could substitute for the skill of a dentist and provide overall dental care at a lower cost. This thesis explores the first step towards the development of such systems by quantifying machining outputs relevant to the removal of dental caries in human teeth. The cutting forces obtained in this study were matched to the CT-scans of the tooth workpieces in order to observe the transition of the cutting forces between the enamel and dentin regions of the tooth. Anisotropy of the enamel region was captured by the orientation-dependent variations of the cutting forces. Cutting forces in the dentin region were shown to be less sensitive to orientation. Stalling of the dental bur, or cutting tool, (due to the low torque of the dental handpiece, or spindle) was observed to occur at high cutting speeds (greater than 50 krpm), combined with high feed per tooth values (greater than 0.5 ?m) and affected the surface morphology of the machined surface. The type of fit present on the shank of the dental bur affects the cutting force signal and rotational speed of the bur during the cutting process. This type of fit, in turn, also affects the wear pattern on the cutting edges of the dental bur. Finally, the development of a phase-specific mechanistic machining model applied to the structure of teeth is described as a future pathway that can be explored in order to further develop these minimally-assisted tooth repair systems.