骨再生誘導法治療後の経年的形態変化

抄録

It is important to know whether the generated bone from guided bone regeneration (GBR) treatment can be stabilized and keep its shape or whether it will change after it is made to function for the implant treatment, because it can affect the prognosis after the implant treatment.
The purpose of this study was to periodically analyze and assess the change in the shape of bone that was generated by GBR treatment.
In our method, we produced study models with the same patient, which were immediately before and after the GBR and also after three years had passed. The elapsed time for the study models after the GBR was about four months on average. We analyzed the study models for each period. When given the GBR treatment, the bones are enlarged horizontally. Therefore, the forms of the parts to which the GBR treatments were given in the study models expand horizontally. By applying trigonometric functions to these dilated forms, we represented them as GBR angles, and compared and examined them statistically by the increase or decrease in GBR angles.
The results were as follows:
(1) Four months after the GBR, the average increase of GBR angles was 80.3% in the upper jaw,49.8% in the lower jaw, and 57.8% in the upper and lower jaws. Three years after the root form implant was installed, decrease of GBR angles or absorption of the bones was observed, compared with four months after the GBR treatment.
On the other hand, compared with the condition before the GBR treatment, the increase of GBR angles was 31.7% in the upper jaw, 32.2% in the lower jaw, and 32.0% in the upper and lower jaws.
With this measuring method some conditions are modified by the thickness of mucous membranes, etc., because the form of the inner bones is predicted from the gum surfaces; however, it is suggested that by setting up exception criteria, this analytical method can be adjusted and is an effective assessment method after GBR treatment.