下颌第二磨牙近中阻生的局部牙列及颌骨形态的三维分析

doi:10.13591/j.cnki.kqyx.2023.11.008

Abstract

Abstract:

Objective To investigate the morphological differences of localized dentition and mandible between patients with mesio-impacted mandibular second molars(MM2) and non-impacted patients in three dimensions and analyze the morphological characteristics. Methods A total of 148 patients who underwent cone-beam computed tomography(CBCT) were included and divided into three groups. Group 1(G1) included 50 patients with unilaterally mesio-impacted MM2; group 2(G2) was composed of 48 patients with bilaterally mesio-impacted MM2, and group 3(G3) was made up of 50 age- and gender-matched controls. Fifteen measurements were selected, including 10 dental measurements and 5 bony measurements. Results The length and width of MM2 were significantly higher in G1 and G2 than in G3, while the height of localized mandibular bone was smaller in G1 and G2. The length and width of localized mandibular bone were statistically smaller in patients with bilaterally impacted MM2 than those with unilaterally impacted MM2. The length and height of localized mandibular bone on unilaterally impacted side were smaller than those on the non-impacted side(P<0.05). Conclusion The crown of MM1 and MM2 were larger in patients with mesio-impacted MM2. The eruption space of MM2 was insufficient, and the space in bilaterally impacted area was narrower than in unilaterally impacted area. Besides, the presence of the mandibular third molar and gender were not significantly associated with mesial impaction of the mandibular second molar.

Key words: impacted mandibular second molar, mandibular morphology, three dimensional measurement

CLC Number:

R783.5

ZHOU Zhijie, HONG Yueyang, XU Yan.

Three dimensional analysis of localized dentition and mandibular morphology in patients with mesio-impacted mandibular second molars

[J]. Stomatology, 2023, 43(11): 1008-1013.

Figures/Tables 4

Tab.1

Tab.2

Tab.3

Tab.4

References 22

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指标	定义
牙性指标
L6	下颌第一磨牙牙冠长度——近远中接触点之间的距离
W6	下颌第一磨牙牙冠宽度——过近远中接触点线段中点(O点)并垂直于该线段的颊舌向距离
L7	下颌第二磨牙牙冠长度
W7	下颌第二磨牙牙冠宽度
∠6-7	下颌第一磨牙和下颌第二磨牙牙体长轴之间的夹角
∠7-MR	下颌第二磨牙牙体长轴和下颌升支长轴之间的夹角
L6-7	下颌第一磨牙O点与下颌第二磨牙O点到Z平面的距离之差
H6-7	下颌第一磨牙O点与下颌第二磨牙O点到X平面的距离之差
W6-Y	下颌第一磨牙O点到Y平面的距离
W7-Y	下颌第二磨牙O点到Y平面的距离
骨性指标
L6-MR	下颌第一磨牙O点与下颌升支前缘转折点(MR点)到Z平面的距离之差
L7-MR	下颌第二磨牙O点与下颌升支前缘转折点(MR点)到Z平面的距离之差
L7-B	下颌第二磨牙萌出间隙长度——下颌第一磨牙远中牙槽嵴顶到下颌升支前缘转折点之间的距离
W7-B	下颌第二磨牙萌出间隙宽度——取L7-B线段的中垂线与颊舌侧牙槽嵴顶两个交点之间的距离
H7-B	过下颌第二磨牙O点作下颌平面Go-Me垂线反向延长线与牙槽嵴顶和下颌下缘的两个交点之间的距离

指标	单侧阻生(G1)	双侧阻生(G2)	对照组(G3)	F/Welch	P	P
指标	单侧阻生(G1)	双侧阻生(G2)	对照组(G3)	F/Welch	P	G1 vs. G3	G2 vs. G3	G1 vs. G2
牙性指标
L6/mm	10.53±0.55	10.60±0.54	10.36±0.47	5.55	0.004^*	0.053	0.001^*	0.461
W6/mm	9.05±0.50	9.00±0.44	8.68±0.39	18.17	0.000^*	0.000^*	0.000^*	0.481
L7/mm	10.47±0.61	10.58±0.69	10.17±0.55	11.00	0.000^*	0.005^*	0.000^*	0.338
W7/mm	8.95±0.58	8.85±0.54	8.57±0.50	11.26	0.000^*	0.000^*	0.000^*	0.289
∠6-7/(°)	47.73±21.38	45.18±18.36	10.65±5.43	217.93	0.000^*	0.000^*	0.000^*	0.856
∠7-MR/(°)	65.81±15.94	65.48±14.66	36.42±7.73	196.41	0.000^*	0.000^*	0.000^*	0.999
L6-7/mm	8.06±2.17	8.16±1.62	10.45±0.87	92.55	0.000^*	0.000^*	0.000^*	0.991
H6-7/mm	2.35±3.44	2.24±3.51	-2.34±1.54	99.31	0.000^*	0.000^*	0.000^*	0.997
W6-Y/mm	21.74±1.87	21.69±1.92	21.64±1.77	0.07	0.936	0.724	0.830	0.861
W7-Y/mm	24.90±1.97	25.30±2.18	24.74±1.85	1.93	0.147	0.654	0.054	0.256
骨性指标
L6-MR/mm	14.92±3.15	13.60±2.84	15.02±2.86	6.65	0.002^*	0.846	0.001^*	0.010^*
L7-MR/mm	6.86±3.73	5.44±3.40	4.56±3.13	7.79	0.001^*	0.000^*	0.069	0.017^*
L7-B/mm	18.00±1.68	17.26±1.43	18.61±1.04	28.27	0.000^*	0.068	0.000^*	0.027^*
W7-B/mm	15.00±0.91	15.51±1.00	15.63±1.06	6.83	0.001^*	0.000^*	0.397	0.004^*
H7-B/mm	21.94±2.22	22.39±2.42	24.68±2.52	30.81	0.000^*	0.000^*	0.000^*	0.287

测量值	阻生侧	非阻生侧	Z	P
牙性指标
L6/mm	10.53±0.55	10.38±0.42	-2.59	0.010^*
W6/mm	9.05±0.50	9.10±0.51	-1.01	0.311
L7/mm	10.47±0.61	10.28±0.56	-2.57	0.010^*
W7/mm	8.95±0.58	8.88±0.44	-1.00	0.315
∠6-7/(°)	47.73±21.38	14.72±10.36	-5.91	0.000^*
∠7-MR/(°)	65.81±15.94	33.89±14.80	-5.97	0.000^*
L6-7/mm	8.06±2.17	10.61±1.90	-5.36	0.000^*
H6-7/mm	2.35±3.44	-1.93±1.34	-5.98	0.000^*
W6-Y/mm	21.74±1.87	21.88±1.70	-0.50	0.619
W7-Y/mm	24.90±1.97	25.40±2.17	-0.97	0.334
骨性指标
L6-MR/mm	14.92±3.15	15.44±3.42	-0.91	0.363
L7-MR/mm	6.86±3.73	4.82±3.50	-4.59	0.000^*
L7-B/mm	18.00±1.68	18.33±1.65	-3.14	0.002^*
W7-B/mm	15.00±0.91	15.07±0.96	-0.56	0.577
H7-B/mm	21.94±2.22	23.15±2.38	-4.46	0.000^*

观察指标		下颌第三磨牙		总计	χ²	P	性别		总计	χ²	P
观察指标		存在	不存在	总计	χ²	P	男	女	总计	χ²	P
下颌第二磨牙近中阻生	是	87	11	98	0.239	0.625	40	58	98	0.696	0.404
下颌第二磨牙近中阻生	否	43	7	50	0.239	0.625	24	26	50	0.696	0.404
总计		130	18	148			64	84	148

Three dimensional analysis of localized dentition and mandibular morphology in patients with mesio-impacted mandibular second molars

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