成人期における上顎切歯の持続的萌出と関連する機能的因子．10年間の前向きコホート研究

Functional factors associated with continuous eruption of maxillary incisors in adulthood: A 10-year prospective cohort study.

• Stavros Kiliaridis
• Grethe Jonasson
• Luis Tomas Huanca Ghislanzoni

抄録

目的:

成人の上顎切歯の連続的な噴出量と咬合筋厚（MMT）および最大咬合力（MOF）から推定される機能的因子が関連しているかどうかを検討することを目的とした。

PURPOSE: To investigate whether functional factors estimated by the masseter muscle thickness (MMT) and the maximum occlusal force (MOF), were associated with the amount of continuous eruption of maxillary incisors in adults.

材料と方法:

10年間の前向きコホート研究において、24名の成人女性患者を対象に歯型を2回採取した。初診時には、MMTとMOFの超音波検査が記録された。歯型はデジタルモデルにスキャンされ、口蓋領域に重ね合わせた後、上顎切歯の噴出と臨床的冠長（CL）の測定値が計算された。一変量および多変量混合効果回帰モデルを用いて、咬合接触の有無とCLが切歯の発疹に及ぼす機能的因子の単独および共同の役割を評価した。

MATERIALS AND METHODS: Dental casts were taken twice in 24 adult female patients during a 10-year prospective cohort study. At the first appointment, ultrasonographic measures of the MMT and MOF were recorded. The casts were scanned into a digital model and measurements of the eruption and clinical crown lengthening (CL) of the maxillary incisors were calculated after superimpositions on the palatal region. Univariate and multivariate mixed effect regression models were used to assess the single and joint role of functional factors, with presence or absence of occlusal contacts and CL on incisor eruption.

結果:

線形混合効果回帰モデルを用いて、MMTとMOFの両方が上顎切歯の噴出量と相関していることが観察された。特に、咬合器が太い、または咬合力が強いほど噴火量が少ないことがわかりました。後方多変量混合効果モデルを用いて、切歯の発疹はMMTと接触の有無および臨床的CLを組み合わせたものと相関していた。その結果，歯の萌出量（平均0.32mm）はCL（平均0.29mm）と正の相関を示し，CL（歯肉後退）が大きいほど萌出量が多いことが示唆された．上顎切歯と下顎拮抗薬との咬合接触の有無は、多変量モデルにおいて噴出抑制因子として認められた。

RESULTS: By using the linear mixed effects regression model, we observed that both the MMT and MOF were correlated with the maxillary incisor eruption. In particular, the thicker the masseter or the stronger the occlusal force, the lower the amount of eruption. Using a backward multivariable mixed effects model, the incisor eruption was correlated with the MMT combined with presence or absence of contacts and clinical CL. The amount of tooth eruption (0.32 mm on average) was positively associated with CL (0.29 mm on average); therefore, the greater the CL (gingival recession), the greater the amount of tooth eruption. The presence of occlusion contact between the maxillary incisors and their mandibular antagonists was found as an inhibitor of eruption in the multivariate model.

結論:

MMTで推定される咀嚼筋の機能的能力は、上顎切歯の噴出量に一役買っている。咀嚼筋が強ければ強いほど、侵食量は減少する。

CONCLUSIONS: The functional capacity of masticatory muscles, as estimated by the MMT, plays a role in the amount of maxillary incisor eruption. The stronger the masticatory muscles, the lower the amount of eruption.