**2. Main issue**

Dentistry requires development in hand skills throughout the undergraduate and postgraduate programs both in the pre-clinical and clinical settings (Allred, 1977). The level of expertise achieved depends on the level of training, the natural ability of the dentist and also experience. Tooth preparation for a crown is a common procedure in general dental practice and it is essential that dental students are able to perform this procedure competently before they graduate. The skill training of these techniques is in itself subjective, as there is use of "eyeballing" of the preparation rather than a definite measure. There is clearly a need to obtain more formal dimensional assessment of crown preparations. This will assist in the feedback to and the training of dentists and also in the practise of dentistry.

This chapter will describe dimensional measurements in dentistry with traditional solutions and present the use of metrology in dentistry. Metrology can benefit the teaching of dentistry by presenting three-dimensional images of teeth before and after preparation and measuring dimensional changes. This is also a benefit to the student as they are able to receive more objective measurable feedback. Metrology has also been used in dentistry to measure the amount of tooth wear on the surface of a tooth. Specifically in the preparation of crowns, it has been used previously to measure the width of the crown preparation margin, the angulation of the margin (Seymour et al.,1996, Cherukara et al., 2002) and the taper angle formed when a tooth is prepared for a crown (Rafeek et al., 2006, 2010).
