Bone loss assessment using different parameters in the microtomographic analysis. Study in rats

Abstract

Introduction

the challenge in the use of Micro-Ct has been to establish and standardize adequate standards for scanning and image processing to obtain the maximum performance of the equipment and to allow the comparison of findings between different studies.

Objective

this study aims to compare the percentage of bone volume in regions with periodontal bone loss using different methodologies to define the area to be analysed (ROI).

Material and method

ten rats were submitted to periodontal disease induction, and, after euthanasia, the mandibles were scanned with slices of 9μ and 18μm thickness, with a rotation step of 0.3mm. The images were reconstructed using the NRecon software, and then, using the CTAnalyser - CTAn software, the areas of interest (ROI) around the second molars were defined. The first area of ​​interest (ROI1) was defined in a rectangular pattern that was restricted to the interproximal and furcation regions, where the total area of ​​bone tissue was obtained by adding the results of the 3 ROIs. The second area (ROI2) was defined in the coronal/apical direction around the second molar to its proximal limitations with the neighboring teeth, in which the percentage of bone tissue belonging to the roots was excluded from the evaluations. Analyses were performed with five different threshold values ​​(130-50, 130-60, 130-70, 130-80, 130-90, and 130-100).

Result

the analysis between the different ROIs showed that, in both analyses, there was a tendency towards a lower percentage of bone tissue the greater the grayscale contrast used. However, in the results obtained in ROI2, this difference was not statistically significant.

Conclusion

with the results obtained, it can be concluded that the use of different thresholds for bone quantification, in areas where there was a periodontal disease, can bring divergent results; the definition of the area of ​​interest interferes with the results obtained; and that obtaining an area of ​​interest with the removal of the roots, proved to be less susceptible to the variation of the scanning parameters.

Descriptors:
Computerized microtomography; Micro-Ct; periodontitis