Quantitative Computed Tomography Bone Mineral Density Measurements in Irradiated and Non-irradiated Minipig Alveolar Bone: an Experimental Study

Objective: The objective of this study was to analyse the effect of irradiation on bone mineral density (BMD).

Materials And Methods: All maxillary and mandibular pre-molars and molars of six minipigs were extracted. After a 3-month healing period, the maxilla and mandibles of three minipigs received three irradiation exposures at a total dose of 24 Gy. At 3 months after irradiation, quantitative computed tomography (QCT) was performed. As a reference, a calibration bone phantom with pre-determined BMD was attached to the head of the minipigs. The QCT data were imported into a software program to calculate the BMD of the alveolar bone and the calibration bone phantom. In order to compare BMD values of individual minipigs, the so-called bone mineral density quotient (BMDQ) was created, dividing the BMD value of the alveolar bone by the BMD value of the calibration bone phantom.

Results: Mean BMDQ values appeared to be higher in irradiated than in non-irradiated minipigs. However, the difference was not significant. In both irradiated and non-irradiated minipigs, the average mandibular BMDQ values were statistically significantly higher than the average maxillary BMDQ values (P=0.003). The P-values of the Student t-test, determining the irradiation effect, were 0.11 for maxillary, 0.14 for mandibular, and 0.07 for overall peri-implant BMDQ. P-values of the non-parametric Mann-Whitney test were all 0.05.

Conclusion: It could be concluded that, 3 months after irradiation, the BMD of irradiated alveolar minipig bone was increased, when compared with non-irradiated alveolar minipig bone. However, the increase was not statistically significant.