下顎非対称の患者における顎関節形態と顆頭運動の3次元的特徴

Three-dimensional characteristics of temporomandibular joint morphology and condylar movement in patients with mandibular asymmetry.

抄録

背景:

下顎非対称（MA）の形態的・機能的影響を調べることは、咀嚼機能障害の発生過程を理解するだけでなく、根拠に基づいた咬合治療への示唆を与えるために重要である。

BACKGROUND: Investigating the morphological and functional effects on mandibular asymmetry (MA) is important not only to understand the developmental process of masticatory dysfunction, but also to provide suggestions for evidence-based occlusal treatment.

目的:

MA患者の3次元的な顎関節形態と非対称な顆頭運動との関係を評価する。

AIM: To evaluate three-dimensional temporomandibular joint (TMJ) morphology and its relationship to asymmetrical condylar movement in MA patients.

材料と方法:

50名の被験者を、正中矢状面からのmenton deviation 4mmに応じてMA群とコントロール群（各n=25）に分けた。顎関節の形態（顆頭、関節窩、顎関節腔）を3次元解析プログラムにより評価した。3次元的な顆頭運動（矢状面と水平面からの）を記録し、突出時のコンピュータアキシオグラフィで測定した。左右の非対称性は、各パラメータについて測定された。顎関節の形態と臼歯部の動きの相関を評価するために，非対称性指数値を算出した．統計解析には，Wilcoxonの符号付順位検定，Mann-WhitneyのU検定，Spearmanの順位相関を用いた．

MATERIALS AND METHODS: Fifty subjects were divided into MA and control groups (n = 25 each) according to a menton deviation of 4 mm from the mid-sagittal plane. TMJ morphology (condyle, glenoid fossa and TMJ spaces) were evaluated using a three-dimensional analysis programme. Three-dimensional condylar movements (from the sagittal and horizontal planes) were recorded and measured by computerized axiography on protrusion. Side-to-side asymmetry was measured for each parameter. The asymmetry index value was calculated to assess the correlation between TMJ morphology and condylar movement. For the statistical analysis, Wilcoxon's signed-ranked test, the Mann-Whitney U test, and Spearman's rank correlation were used.

結果:

MA群のシフト側では、非シフト側およびコントロール群の平均値と比較して、関節窩体積、表面積、前後長、顆頭体積が有意に小さく、関節稜角度、関節窩、顆頭軸角が有意に大きかった（P<0.05）。TMJスペースは，MA群では両側で差がなかったが，コントロール群に比べ，内側，上側，前側の関節スペースが有意に狭かった（P＜0.05）．顆路長および矢状顆路傾斜は有意に非対称的であった．顆路長の非対称性指標と顆路長の非対称性指標は有意に相関した（P=0.005）．関節窩の体積と関節稜の角度の非対称性指数は、矢状顆路の傾きと有意な相関があり（それぞれP=0.009、P=0.002）、関節窩の体積の非対称性指数は、両側横顆路の傾きと有意な相関があった（それぞれ、P=0.006、P=0.016）。

RESULTS: Glenoid fossa volume, surface area, anteroposterior length, and condylar volume were significantly smaller, and articular eminence angle, glenoid fossa, and condylar axial angle were significantly larger, on the shifted side of the MA group when compared with those on the non-shifted side and the mean values of the control group (P < 0.05). The TMJ spaces of the MA group showed no bilateral difference but were significantly narrower in the medial, superior, and anterior joint spaces when compared with the control group (P < 0.05). Condylar path length and sagittal condylar inclination were significantly asymmetrical. The asymmetry index of the condyle volume was significantly correlated with that of the condylar path length (P = 0.005). The asymmetry index of the glenoid fossa volume and the articular eminence angle were significantly correlated with that of the sagittal condylar inclination (P = 0.009 and P = 0.002, respectively), and the asymmetry index of glenoid fossa volume was significantly correlated with the bilateral transverse condylar inclination (P = 0.006 and P = 0.016, respectively).

結論:

顎関節の形態的非対称性は、シフト側と非シフト側で有意に異なり、MA患者における顆頭運動の機能的非対称性と密接な関係があることが示された。(350/350).

CONCLUSIONS: Morphological asymmetry of the TMJ is significantly different between the shifted and non-shifted sides and is closely related to functional asymmetry of condylar movement in MA patients. (350/350).