Application of Calcium Phosphate Ceramics to Periodontal Therapy

4. Radiographic Quantitative Analysis for Judgement on Prognosis of Hydroxyapatite Application

Abstract

This study was carried out in order to establish a reliable method of radiographical quantitative analy sis, which provided a correct judgement on the prognosis after hydroxyapatite application. Hydroxyapatite was applied to experimental periodontitis in beagle dogs, then chronological radiographs were taken with a grey-scale under a standardized method. After densitometric measurements of images on the standardized dental radiographs were transformed into micrometers of copper equivalents by microphotometer on-lined with microcomputer, changes of the objective sites were expressed in numerical value.
The results obtained were as follows.
1. Alterations in density of bone defects due to hydroxyapatite-filling were quantitatively estimated.
2. Fluctuations of the numerical value measured on control case and hydroxyapatite-filling case were different, though bone repair seemed to finish similarly in both cases. The numerical value at the bottom of the bone defect in control case became lower than in coronal parts. On the other hand, the value of each part of hydroxyapatite-filling case presented approximation. These findings suggested that hydroxyapatite brought more natural feature to the bone repair.
3. Chronological changes of the numerical value after the filling of hydroxyapatite were classified into three patterns, which were related with situations of hydroxyapatite in the bone defects. The first pattern, which was seen at coronal part of the defect was that the numerical value increased gradually. It was speculated that in this part hydroxyapatite was discharged and the bone repair would not be expected. The second pattern was observed at central part. The numerical value which was elevated initially showed decrease in the passage of time, perhaps this change was resulted both from loosening of hydroxyapatite granules and advance of the bone repair. The numerical value at the bottom of the defect presented the third pattern that it was reduced by degrees and this findings suggested that the bone repair had been in progress.