| OBJECTIVE:The study about alveolar crest’s morphological characteristics can establish a digital three-dimensional computer model of the jaw, and then to measure the thickness of labial and palatal alveolar bone and the labial plate curvature, providing a reference for orthodontic tooth movement design, tooth extraction, even forecast the result of orthodontic treatment.METHODS:Our study was carried out in 14 months, among 30 research objects.10 of the participants were maxillary dental protrusion(the experiment group A),10 of them were maxillary prognathism(the experiment group B),10 of them were normal(the control group). We chosed Planmeca Romexis cone-beam CT and its related evaluating program as the tool to measure and analysis the result.All research objects used the same mode to obtain maxillofacial CT. Then used Planmeca Romexis 3.3.3.R software to measure the required data: selected the section of 3 mm,6 mm, 9 mm,12 mm from the alveolar ridge crest vertical distance as the study planes L1、 L2、L3、L4. Taking the study planes L3 of central incisor and lateral incisor and the study planes of canine teeth as the representative planes to measure the difference among normals maxillary dental protrusion and maxillary prognathism。 In each study plane, we measured the thickness of labial and lingual alveolar bone, and the labial plate curvature of all teeth in anterior maxillary region. First, we used t test to analyze the alveolar ridge morphology of bilateral symmetric teeth. If no statistical difference, we could analyze the alveolar ridge morphology of the incisor, lateral incisor teeth, canine teeth. If with statistical difference, we analyzed the alveolar ridge morphology of each teeth in the anterior maxilla. Using ANOVA to compare the difference among groups in the morphological characteristics of alveolar ridgeRESULTS:The morphological characteristics about bilateral symmetric teeth of three study teams had no statistical difference:p>0.05, we analyzed the alveolar ridge morphology of the incisor, lateral incisor teeth, canine teeth.Results of variance analysis of morphological characteristics about the control group、the experiment group A and the experiment group B were as follows:1. The results of group A were: the thickness of labial alveolar bone about central incisor of maxilla respectively were 1.46±0.12mm、1.90mm±0.09mm、 3.56mm±1.44mm in L1、L2、L3 study planes; the thickness of palatal alveolar bone respectively were 2.10±1.25mm、2.61±1.74mm、4.17±3.60mm in L1、L2、 L3 study planes; the thickness of labial alveolar bone about lateral incisor of maxilla respectively were 1.53±1.00mm、1.95±0.46mm、2.33±1.97mm in L1、L2、L3 study planes, the thickness of palatal alveolar bone respectively were 2.06±1.22mm、 2.83±2.99mm、4.31±4.01mm in L1、L2、L3 study planes; the thickness of labial alveolar bone about canine teeth of maxilla respectively were 1.17±1.58mm、 1.19±3.06mm、1.23±3.77mm、2.30±4.07mm in L1、L2、L3、L4 study planes, the thickness of palatal alveolar bone respectively were 3.13± 1.27mm、 4.93±2.04mm、6.01±3.55mm、7.88±3.99mm in L1、L2、L3、L4 study planes. The labial plate mean curvature of central incisor was 127.76±2.88°, lateral incisor was146.43±1.89°, canine teeth was163.43±2.57°.2. The results of experiment group B were: the thickness of labial alveolar bone about central incisor of maxilla respectively were 1.13±1.66mm、0.93±1.89mm、 0.95±2.07mm in L1、L2、L3 study planes; the thickness of palatal alveolar bone respectively were 2.05±2.07mm、4.07±2.33mm、5.93±3.60mm in L1、L2、L3 study planes; the thickness of labial alveolar bone about lateral incisor of maxilla respectively were 1.00±1.33mm、0.76±0.08mm、0.88±2.42mm in L1、L2、L3 study planes; the thickness of palatal alveolar bone respectively were 1.76±1.21mm、3.01±2.41mm、4.87±3.84mm; the thickness of labial alveolar bone about canine teeth of maxilla respectively were 1.67±2.08mm、0.89±2.22mm、 0.73±3.50mm、0.88±4.12mm in L1、L2、L3、L4 study planes, the thickness of palatal alveolar bone respectively were 2.01±1.67mm、3.17±2.14mm、 4.84±2.75mm、7.37±3.15mm; The labial plate mean curvature of central incisor was 150.61±2.09°, lateral incisor was 155.57±2.10°, canine teeth was 158.18±2.52°.3. The results of the control group were:the thickness of labial alveolar bone about central incisor of maxilla respectively were 1.28±0.06mm、1.17±1.86mm、 1.45±2.92mm in L1、L2、L3 study planes; the thickness of palatal alveolar bone respectively were 2.30±1.83mm、4.53±2.88mm、6.91±3.65mm in L1、L2、L3 study planes; the thickness of labial alveolar bone about lateral incisor of maxilla respectively were 0.89±1.73mm、0.67±2.56mm、1.49±3.15mm in L1、L2、L3 study planes; the thickness of palatal alveolar bone respectively were 2.23±1.01mm、4.24±2.18mm、6.27±2.89mm; the thickness of labial alveolar bone about canine teeth of maxilla respectively were 1.50±1.59mm、0.92±2.80mm、 0.72±2.47mm、1.73±3.30mm in L1、L2、L3、L4 study planes, the thickness of palatal alveolar bone respectively were 2.21±1.51mm、4.02±2.47mm、 6.51±2.55mm、9.39±3.02mm; The labial plate mean curvature of central incisor was 152.04±2.92° lateral incisor was 156.22±2.47° canine teeth was 159.54±1.98°4. The results of the morphological characteristics of alveolar ridge in the experiment group A、the experiment group B and the control group were:(1). It was different between the experiment group A and the experiment group B (P＜0.05); it was different between the experiment group A and the control group (P<0.05); it had no difference between the control group and the experiment group B(P>0.05).(2). Central incisor: the thickness of labial alveolar bone was different among the experiment group A、the experiment group B and the control group (P＜0.05). The thickness of palatal alveolar bone was different among the experiment group A、the experiment group B and the control group (P＜0.05).(3). The lateral incisor:the thickness of labial alveolar bone was different among the experiment group A、the experiment group B and the control group (P＜0.05). The thickness of palatal alveolar bone was different among the experiment group A、 the experiment group B and the control group (P<0.05).(4). The canine teeth: the thickness of labial alveolar bone was different among the experiment group A、the experiment group B and the control group (P＜0.05). The thickness of palatal alveolar bone was different among the experiment group A、 the experiment group B and the control group (P<0.05).CONCLUSION:1.(1) The thickness of labial alveolar bone of maxillary prognathism was firstly decreased and then increased; the thickness of palatal alveolar bone showed a trend of increasing from alveolar ridge crest to root. (2) The thickness of labial and palatal alveolar bone about maxillary dental protrusion showed a trend of increasing from alveolar ridge crest to root. (3) The thickness of labial alveolar bone of normal occlusion was firstly decreased and then increased; the thickness of palatal alveolar bone showed a trend of increasing from alveolar ridge crest to root.2. The labial plate of canine teeth about maxillary dental protrusion was bent, while the labial alveolar bone of central incisor and lateral incisor about maxillary prognathism was bent. The labial alveolar bone about incisor and the alveolar bone about canine in maxillary prognathism had thinner thickness. The thickness of palatal alveolar bone in maxillary dental protrusion is thinner. In the process of orthodontic treatment, the orthodontists should pay more attention to thinner area, to avoid adverse reconstruction of periodontal supporting tissue. |
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