歯科インプラントはヒト下顎頭の骨形態と骨密度を変化させる：パイロットスタディ

Dental implantation affects masticatory bite and muscle forces. The temporomandibular joint (TMJ) bears a substantial amount of these masticatory forces. Thus, the objective of the current study was to investigate whether dental implantation alters the human mandibular condyle. Among 556 images, 54 and 22 CBCT scans were successfully identified from 27 patients (10 males and 17 females; 54.93 ± 19.46 years) in the control group and 11 patients (3 males and 8 females; 51.32 ± 13.13 years) in the implant group, respectively. In the control group, CBCT images were obtained longitudinally at the time of implantation and after the post-implantation healing period, both prior to crown placement. In the implant group, CBCT images were obtained at the time of crown placement on a single-tooth implant and after the functional loading period following crown placement. Left and right mandibular condyles were digitally isolated from the images. The bone mineral density (BMD) parameters and morphological changes were assessed using frequency plots of BMD and TMJ osteoarthritis (OA) counts, respectively. In the control group, BMD values were not significantly different between the first and second scans. In contrast, the implant group showed a significant decrease in BMD values, along with a marginal increase in TMJ OA counts after the functional loading period. The TMJ OA counts were highest in the anterior regions, followed by the middle and posterior regions. Most regions showed significantly reduced BMD values, except the antero-lateral and antero-central regions. The current findings give an insight that dental implantation may alter the morphology and BMD of human mandibular condyles. The TMJ OA counts increased, while BMD decreased during the functional loading period of more than 3 months following implantation. Masticatory loading associated with the dental implant likely increases the load on the TMJ, which could stimulate new bone formation to balance the load distribution on the mandibular condyle.