中国人成人における第二大臼歯の喪失と隣接第三大臼歯の有無との対応：レトロスペクティブ・スタディ

How the Loss of Second Molars Corresponds with the Presence of Adjacent Third Molars in Chinese Adults: A Retrospective Study.

抄録

第三大臼歯（M3）は、隣接する第二大臼歯（M2）の病理学的リスクを増大させる可能性がある。しかし、M3の存在がM2の喪失に影響を及ぼすかどうかは依然として不明である。この後方視的研究は、M2喪失の理由とM2喪失が隣接するM3とどのように関連しているかを明らかにすることを目的とした。M2を抜歯した患者のカルテとX線写真を検討し、抜歯の理由と隣接するM3との関連性を分析した。最終的に908本のM2を抜歯した800人の患者が対象となった。M3を有する526の象限をM3（＋）群と呼び、M3を有しない他の382の象限をM3（-）群と呼んだ。M3（＋）群の患者の平均年齢は52.4±14.8歳、M3（-）群の平均年齢は56.7±14.9歳で、両群間の差は統計学的に有意であった（p＜0.001）。908本のM2のうち、433本（47.7％）がう蝕および後遺症により、300本（33.0％）が歯周病により抜歯された。一方、隣接するM3があるM2の14.4％は、隣接するM3と密接に関連する遠位う蝕および歯周炎が原因で除去されたが、M3がない場合はこの割合はかなり低かった（1.8％）。さらに、42.2％のM3が隣接するM2と同時に除去された。インプラントの状態にかかわらず、M3の存在は隣接するM2の早期喪失と関連していた。

Third molars (M3s) can increase the pathological risks of neighboring second molars (M2s). However, whether the M3 presence affects M2 loss remains unknown. This retrospective study aimed to reveal the reasons for M2 loss and how M2 loss relates to neighboring M3s. The medical records and radiographic images of patients with removed M2(s) were reviewed to analyze why the teeth were extracted and if those reasons were related to adjacent M3s. Ultimately, 800 patients with 908 removed M2s were included. In the included quadrants, 526 quadrants with M3s were termed the M3 (+) group, and the other 382 quadrants without M3s were termed the M3 (−) group. The average age of patients in the M3 (+) group was 52.4 ± 14.8 years and that of the M3 (−) group was 56.7 ± 14.9 years, and the difference between the two groups was statistically significant (p < 0.001). Of the 908 M2s, 433 (47.7%) were removed due to caries and sequelae and 300 (33.0%) were removed due to periodontal diseases. Meanwhile, 14.4% of the M2s with adjacent M3s were removed due to distal caries and periodontitis, which were closely related to the neighboring M3s; this percentage was much lower when M3 were absent (1.8%). Additionally, 42.2% of M3s were removed simultaneously with neighboring M2s. The presence of M3s, regardless of impaction status, was associated with an earlier loss of their neighboring M2s.