State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, 14 Renmin South Road Third Section, Chengdu, 610041, China.
Discipline of Orthodontics, Department of Oral Sciences, Faculty of Dentistry, Sir John Walsh Research Institute, University of Otago, Dunedin, New Zealand.
BMC Oral Health. 2020 Apr 15;20(1):108. doi: 10.1186/s12903-020-01099-2.
To investigate the area and morphological changes around the soft tissue chin after orthodontic incisor retraction.
Fifty-nine female adults with bimaxillary protrusion requiring extraction of four premolars were included in the study. Cephalograms were taken before (T0) and after (T1) orthodontic treatment. The soft tissue changes, including the area, thickness and morphology were measured. Paired-t tests were performed for statistical comparisons. Pearson correlation analyses and backward multivariate regression analyses were used to identify the relationship between the soft tissue changes and incisor retraction.
Following the incisor retractions (5.35 ± 1.79 mm and 4.42 ± 1.62 mm for the upper and lower, respectively), there was a significant increase in the soft tissue thickness of L1c-LL (0.64 ± 1.67 mm, P = 0.025) and Pog-Pog' (0.44 ± 1.10 mm, P = 0.022), and a significant decrease in the soft tissue thickness of B-B' (1.21 ± 1.34 mm, P < 0.01). Changes in the area of soft tissue chin and lower lip were not statistically significant (P > 0.05). Pearson coefficient between the thickness changes of B-B' and the retraction of lower incisors was - 0.376. The multiple correlations between the soft tissue thickness changes and incisor retractions were Y = 1.02-0.42a + 0.42b for L1c-LL, and Y = 0.17-0.31b for B-B'.
The orthodontic incisor retraction could cause soft tissue thickness changes (i.e. an increase in L1c-LL and Pog-Pog' and a decrease in B-B') without area changes.
研究正畸切牙内收后颏部软组织区域和形态的变化。
本研究纳入 59 名需要拔除四颗前磨牙的双颌前突成年女性。在正畸治疗前（T0）和治疗后（T1）拍摄头颅侧位片。测量软组织的变化，包括面积、厚度和形态。采用配对 t 检验进行统计学比较。采用 Pearson 相关分析和向后多元回归分析来确定软组织变化与切牙内收的关系。
切牙内收（上切牙 5.35±1.79mm，下切牙 4.42±1.62mm）后，L1c-LL（0.64±1.67mm，P=0.025）和 Pog-Pog'（0.44±1.10mm，P=0.022）软组织厚度显著增加，B-B'（1.21±1.34mm，P<0.01）软组织厚度显著减少。颏部和下唇软组织面积的变化无统计学意义（P>0.05）。B-B'厚度变化与下切牙内收的 Pearson 系数为-0.376。软组织厚度变化与切牙内收的多元相关系数为 L1c-LL 为 Y=1.02-0.42a+0.42b，B-B'为 Y=0.17-0.31b。
正畸切牙内收可引起软组织厚度的变化（即 L1c-LL 和 Pog-Pog'增加，B-B'减少），而不引起面积的变化。
