- 學位論文
安格式二級第一分類異常咬合兒童中臉部與下顎幾何形態學分析
Geometric morphometry of the midfacial complex and mandible in children with Angle Class II,Division 1 malocclusion
摘要
台灣地區安格式二級異常咬合兒童的發生率約在17∼29 ％之間，是矯正門診中很常遇到的病人類型，且通常在混合齒列即表現出異常的顱顏結構表徵。本研究的目的，在評估混合齒列時期，二級異常咬合兒童與正常咬合兒童間，中臉部複合體和下顎骨的形態是否有所差異。使用傳統測顱分析法合併幾何形態學分析（有限元素分析法、薄板仿樣分析法），對其中形態間的變化及其發生機制將有更深入的認識，並能提供臨床醫師作為早期診斷和治療的參考。 選用9歲5個月到11歲7個月未經治療的混合齒列兒童，正常咬合者男、女孩各35位，與安格式二級第一分類異常咬合者，男、女孩各35位的側面測顱X光片。利用10個中臉部和12個下顎骨的解剖標記點進行傳統測顱項目的分析，及圖示分析法的形態定位。將普式疊 合分析法（Procrustes analysis）求得的各組平均圖形，進行之後有限元素分析（Finite element morphometry）、和薄板仿樣分析（Thin-plate spline analysis）的運算。 所得的的結果均顯示出安格式二級異常咬合兒童的中臉部與下顎骨形態，的確不同於正常咬合孩童。中臉部方面，男、女孩在上中臉部複合體水平長度和中臉部複合體高度上，二級異常咬合組與正常咬合組間並無明顯差異，但二級異常咬合男孩在上中臉部中央區域的平均尺寸是縮小的；整體而言，二級異常咬合兒童的上腭（包括齒槽骨區）相對於上中臉部是較前突的，主要的尺寸增長發生在後上腭區域（MPP-PNS周圍），女孩組的變化量較大；而前顎和齒槽骨區在形態分析圖中，均出現明顯往前下方伸展的尺寸增大量，且為中臉部構造中變異性最大的區域，這部分為男孩組間的變異程度較大。 下顎骨方面，整體而言，二級異常咬合兒童的下顎骨總長度較短，髁頭處有伸展的生長形式，下顎枝後緣整體往前壓縮，下巴較為後縮，下顎骨體下緣有逆時針方向，往上方壓縮的旋轉。而下顎體長度、下顎枝寬度在二級異常咬合組與正常咬合組間並無明顯差異。 傳統測顱分析法中，下顎角（Cd-Go-Gn，Ar-Go-Me）在二級異常咬合兒童中角度均較正常咬合兒童小；但在圖示分析法中男孩二級異常咬合者下顎角周圍的局部區域呈現出些微的尺寸增加，女孩組間的局部變化程度則不明顯。 由於下顎骨總長度較短，因此在下顎前牙區的齒槽骨有往前上方伸展的補償性（compensation）生長。另外，二級異常咬合男孩的下顎枝高度短於正常咬合組，有兩性二形的情形。
並列摘要
The incidence of Angle Class II malocclusion for children in Taiwan is between 17~29 percent. The purpose of this study was to evaluate whether the morphology of the midfacial complex and mandible differed in normal occlusion and Angle Class II, division 1 malocclusion children, and to localize differences with finite-element method and thin-plate spline analysis. This study comprised lateral cephalographs of 70 Taiwan children with normal occlusion (35 girls and 35 boys), and 70 Taiwan children with Class II, division 1 malocclusion (35 girls and 35 boys). The cephalographs were traced. 10 homologous landmarks of the midfacial complex and 12 homo- logous landmarks of the mandible were identified and digitized. The student t-test and Hotelling’s T2 statistics were used to analyze 14 linear and angular measurements of the midfacial complex, and 16 linear and angular measurements of the mandible, for evaluation of the differences at the conventional cephalometric values between normal and Class II, division 1 subjects. The average configuration of each group was generated by the Procrustes analysis. These configurations were employed for geometric morphometry: finite-element method and thin-plate spline analysis. In the midfacial complex, the results showed that the maxilla was protru- sive in the midfacial complex of Class II malocclusion subjects, and the major size-enlarged area was at the posterior horizontal length of maxilla (MPP-PNS). The average size of the middle region (around Or point) of upper middle facial complex was reduced in the Class II malocclusion boys. In the graphical analysis, the most severe shape-change of the Class II malocclusion subjects was at the premaxilla and the alveolar ridge area, and these area revealed significant extension toward downward and forward. In the mandible, the total length and the gonial angle were reduced in the Class II malocclusion subjects at the conventional cephalometric values. But in the strain tensor and thin-plate spline pictures, the area around gonial angle showed a little size increasing in the Class II boys. The mandibular body length and ramus width were no significant difference between Class II children and normal subjects. In the graphical analysis, we found that the condylar region showed extension, and the posterior border of ramus showed forward compression in the Class II malocclusion subjects. Besides, the chin was retruded and lower border of mandibular body showed counterclockwise, upward compressive rotation. Because of the reduced mandibular total length, the anterior alveolar ridge showed the compen- sative upward and forward extension in the Class II malocclusion subjects. Due to these differences, we concluded that the configurations of the midfacial complex and the mandible of the Taiwan Class II, division 1 malocclusion children were different to the normal occlusion configure- tions.
參考文獻
延伸閱讀
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