Reproducibility of Three-Dimensional Density Measurements in Teeth Using Micro-Computed Tomography: An Image Acquisition Protocol

Abstract

The use of micro-computed tomography (micro-CT) has become widespread in the examination of dental tissue due to its great precision in small-scale work. Its usefulness in measuring tissue mineral density has been demonstrated; however, it is necessary to develop image acquisition protocols that ensure the reproducibility of observations and offer a detailed step-by-step process. This study proposes a standardised protocol to quantify mineral density using volumetric measurements from micro-CT images, evaluating the reproducibility of density measurements at different points of enamel and dentine. The sample comprised 30 bovine incisors that were scanned using a micro-CT system. Using the MIMICS software v.26, seven reference points in enamel and dentine (crown, cervix, and root) were identified, and mineral density was calculated by using Hounsfield units. The reproducibility of the measurements among the three observers was assessed by calculating Lin’s concordance correlation coefficient (CCC). There was substantial to almost perfect correlation for the enamel (CCC = 0.986–0.995) and dentine (CCC = 0.965–0.997), with the latter showing better results for the cervix (CCC = 0.987–0.997) and crown (CCC = 0.987–0.995) compared with the root (CCC = 0.965–0.985). In the lingual area, the concordance results were broader (CCC = 0.965–0.997) compared with the buccal area (CCC = 0.979–0.995). Despite this difference, the proposed volumetric measurements reached a high level of agreement, which demonstrates the replicability of the present protocol.

Keywords

• dental volume
• image acquisition protocol
• Hounsfield units
• interobserver error
• MIMICS software