下顎骨海綿骨の骨質に及ぼすインプラントの影響

抄録

Purpose: Loss of teeth,loss of occlusal loading, and general skeletal status are associated with a reduced trabecular bone pattern of the mandible. Little is known about whether implant placement also has an effect. We compared the long-term changes in fractal dimension (FD) of the trabecular bone pattern in mandibular molar regions that had implant placement with others that did not.
Methods: Thirty-one subjects (12 men and 19 women) aged 54 to 91 years (mean±SD, 65.5±8.0 years) were recruited for this study.All had undergone at least two panoramic radiographs at intervals of 3 years or more. Radiographs were digitized at 300 dpi. At both baseline and follow-up, FD was calculated on digitized radiographs of 51 edentulous molar sites of the mandible, of which implants were subsequently placed in 28 sites. A linear multiple regression analysis, adjusted for possible covariates, was performed to estimate the effect of implant placement on the change in FD between baseline and follow-up radiographs. Furthermore, in 10 subjects aged 54 to 76 years (mean±SD,64.5±6.6 years) who had one implant placement site and one edentulous site, each in a different molar region of the mandible, FD of these two sites were compared through dependent sample t-tests.
Results: A multiple regression analysis of the 51 molar sites revealed a potential association between implant placement and increased FD, although it did not reach statistical significance (p=0.253). There were marginally significant differences in the changes in FD in implant placement and edentulous sites on differing sides of the mandible in 10 subjects (0.023±0.020 vs. -0.005±0.047, p=0.063).
Conclusions: Our results imply an increased complexity in the trabecular bone pattern of the mandible. Implant placement may contribute to improvement of the trabecular bone pattern of the mandible. A further investigation including a large number of subjects would be necessary to confirm our findings regarding the beneficial effect of implant placement on the internal structure of the mandible.