Three-dimensional analysis of the mandible with impacted mandibular second molar

doi:10.7518/hxkq.2020.03.008

Abstract

Abstract:

Objective To study the developmental and morphological characteristics of the mandible in patients with impacted mandibular second molar and to predict the possible trend of mandibular development via three-dimensional (3D) measurement and analysis. Methods A total of 88 cases of impacted group and 88 cases of control group were screened out. 3D measurements were performed by using Mimics software. A total of 23 landmark points and 17 measurements were determined. The measurements were analyzed by t-test. Results The mandible length, the space between the first molars, the space between mandibular angles, and the width between the first molars in the impacted group were lower than those in the control group (P<0.05). Moreover, the value of the submandibular angle was higher than that in the control group (P<0.05). Conclusion The impacted mandible of patients with mandibular second molar showed lack of sagittal and width development, and the impacted mandibular second molar was a manifestation of its degeneration.

Key words: three-dimensional measurement, impacted mandibular second molar, mandible, degeneration

CLC Number:

R782.1

Fan Wei, Gao Deguo, Wang Yuting, Li Dandan, Wang Zhendong. Three-dimensional analysis of the mandible with impacted mandibular second molar[J]. West China Journal of Stomatology, 2020, 38(3): 274-279.

Figures/Tables 6

Tab 1

Tab 2

Fig 1

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Tab 3

Fig 3

References 19

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标记点	编号	描述
Cdla L	1	左侧髁突最外侧点
Cdla R	2	右侧髁突最外侧点
Cds L	3	左侧髁突顶点
Cds R	4	右侧髁突顶点
Fmd L	5	左侧下颌第一磨牙颊侧远中边缘点
Fmd R	6	右侧下颌第一磨牙颊侧远中边缘点
Go L	7	左侧下颌角点
Go R	8	右侧下颌角点
Id	9	正中联合处牙槽骨最上点
Ml L	10	左侧下颌升支内下颌小舌点
Ml R	11	右侧下颌升支内下颌小舌点
Me	12	颏下点
Po	13	颏前点
QIE1 L	14	过左侧乙状切迹与下齿槽平面平行的
		平面,与左侧升支相交的最前点
QIE1 R	15	过右侧乙状切迹与下齿槽平面平行的
		平面,与右侧升支相交的最前点
QIE2 L	16	过左侧乙状切迹与下齿槽平面平行的
		平面,与左侧升支相交的最后点
QIE2 R	17	过右侧乙状切迹与下齿槽平面平行的
		平面,与右侧升支相交的最后点
Sigmoid notch L	18	左侧下颌升支乙状切迹点
Sigmoid notch R	19	右侧下颌升支乙状切迹点
33 ARB	20	33牙槽嵴顶颊侧中央边缘点
43 ARB	21	43牙槽嵴顶颊侧中央边缘点
34 ARB	22	34牙槽嵴顶颊侧中央边缘点
44 ARB	23	44牙槽嵴顶颊侧中央边缘点

测量值	标记点	描述
D1	5-6	Fmd L和Fmd R的线距
D2	14-16	QIE1 L和QIE2 L的线距
D3	15-17	QIE1 R和QIE2 R的线距
D4	1-2	Cdla L和Cdla R的线距
D5	9-12	Id和Me的线距
D6	5-10	Fmd L和Ml L的线距
D7	6-11	Fmd R和Ml R的线距
D8	4-8	Cds R和Go R的线距
D9	3-7	Cds L和Go L的线距
Angle 1	∠7-12-8	由双侧下颌角点和颏下点所成角
D10	7-13	Go L和Po的线距
D11	8-13	Go R和Po的线距
D12	7-8	Go L和Go R的线距
Angle 2	∠12-7-3	由Me、Go L和Cds L所成角
Angle 3	∠12-8-4	由Me、Go R和Cds R所成角
D13	20-22	下尖牙牙槽嵴顶颊侧缘宽度
D14	21-23	下第一双尖牙牙槽嵴顶颊侧缘宽度

测量项目		阻生组	对照组	P值	95%置信区间
矢状向	D2	41.21±3.14	40.85±3.32	0.470	-0.61~1.32
	D3	41.71±3.10	41.37±3.44	0.495	-0.64~1.31
	D6	35.58±3.92	37.56±4.14	0.000	-2.28~-0.46
	D7	36.17±3.91	38.11±4.34	0.000	-2.02~-0.17
	D10	80.82±4.64	83.54±4.97	0.000	-4.16~-1.30
	D11	80.98±4.46	83.53±5.10	0.000	-3.97~-1.14
垂直向	D5	30.79±2.96	31.28±3.11	0.283	-1.40~0.41
	D8	62.08±5.86	61.82±5.35	0.133	-1.76~0.69
	D9	61.45±6.08	60.63±5.47	0.134	1.10-4.54
横向	D1	45.95±4.09	47.15±2.84	0.000	0.23~1.73
	D4	121.04±7.57	120.68±6.77	0.734	-1.71~2.50
	D12	89.46±5.41	91.42±6.19	0.008	-3.19~-0.49
	D13	28.59±2.86	28.47±2.10	0.762	-0.63~0.86
	D14	41.21±2.52	40.88±2.14	0.350	-0.37~1.02
角度	Angle 1	73.25±4.61	70.40±4.61	0.000	1.48~4.22
	Angle 2	120.79±6.18	122.14±6.30	0.153	-3.20~0.51
	Angle 3	121.58±9.22	123.11±6.36	0.202	-3.89~0.83