歯周支持組織における残存骨高と根面面積の測定結果との整合性の評価

[Evaluation of the consistency between the measurement results of residual bone height and root surface area in periodontal supporting tissue].

• Jing-Jing Xu
• Jun Xu
• Ruo-Nan Xu
• Xin Guo
• Jila Palidan
• Awuti Gulinuer

抄録

目的:

曲面モデリングに基づいて歯周炎の異なるステージをシミュレーションし、歯周支持能を評価する際の残存支持高さ（Ph）と残存根面面積（Ps）の割合を探る。

PURPOSE: To explore the percentage of residual support height (Ph) and the percentage of residual root surface area (Ps) in evaluating periodontal support ability by simulating different stages of periodontitis based on the curved surface modeling.

方法:

合計420本の歯を含む15枚のコーンビームCT(CBCT)画像を収集した。データはMimicsソフトウェアを用いて3次元の歯のモデルに再構築された．PhとPsを測定して計算し、すべての歯のタイプにおけるPhとPsの結果の一貫性を評価した。データはSPSS 22.0ソフトウェアパッケージを用いて分析した。

METHODS: Fifteen cone-beam CT (CBCT) images including 420 teeth in total were collected. The data were reconstructed into 3-dimensional teeth models by Mimics software.The 3D surface model of the tooth was then optimized by Geomagic software and then imported into Solidworks software to simulate different periodontal support height. Ph and Ps were measured and calculated to evaluate the consistency of Ph and Ps results in all tooth types. The data were analyzed with SPSS 22.0 software package.

結果:

前歯、犬歯、前歯のRSA：冠状1/3>中間1/3>先端1/3。臼歯部のRSAは、中1/3＞冠状1/3＞先端1/3であった。上顎第一大臼歯のRSAが最も大きく、歯列の11.60％を占め、下顎中切歯の約3.18倍でした。すべての歯種においてPhとPの差は統計的に有意であった(P<0.01)。上顎切歯，下顎切歯，下顎犬歯におけるPhとPsの差の95%信頼区間(CI)は，臨床的整合性の限界(-15%，15%)の間であった．残りの歯種では、PhとPの差の95%CIは臨床的整合性の限界を超えていた（-15%, 15%）。

RESULTS: RSA in incisors, canines and premolars: coronal 1/3>middle 1/3>apical 1/3. RSA in molars: middle 1/3>coronal 1/3>apical 1/3. Maxillary first molar had the largest RSA, accounting for 11.60% of the dentition, which was about 3.18 times than mandibular central incisor. The difference between Ph and Ps in all types of teeth was statistically significant (P<0.01). The 95% confidence interval(CI) of the difference between Ph and Ps in the maxillary incisor, mandibular incisor, mandibular canine was between the clinical consistency limit (-15%, 15%). In the remaining tooth types, 95%CI of the difference between Ph and Ps was beyond the clinical consistency limit (-15%, 15%).

結論:

上顎犬歯を除く単根歯では、残存歯周支持高さが歯周支持領域に代わる可能性がある。多根歯では、2次元指標の歯槽骨吸収率のみで歯周支持能を判断することには大きな限界がある。歯周病の程度を判断する際には、歯根の形態的不一致に着目して十分な検討が必要である。

CONCLUSIONS: For single-root tooth, except maxillary canine, the remaining periodontal support height could replace periodontal support area. For multi-rooted tooth, judging the ability of periodontal support ability only by alveolar bone absorption ratio in 2D index has significant limitations. Full consideration is needed to focus on root morphological discrepancy when determining the extent of periodontal disease.