Assessment of the soft tissue thickness at the lower anterior face in adult patients with different skeletal vertical patterns using cone-beam computed tomography

Objective:To evaluate and compare the soft tissue thickness values at the lower anterior face among adult patients with different vertical growth patterns using cone-beam computed tomography.Material and Methods:The study sample consisted of 105 adult patients (54 women and 51 men) with a normal sagittal skeletal pattern divided into three groups according to the vertical growth pattern: high-angle (women/men, 22/13; mean age, 24.54 ± 4.45 years), low-angle (women/men, 14/21; mean age, 24.62 ± 5.08 years), and normal-angle (women/men, 18/17; mean age, 24.22 ± 5.40 years) groups. The soft tissue thickness measurements at the lower anterior face in each group were done and analyzed using the one-way analysis of variance and Tukey tests.Results:Soft tissue thickness values were the lowest in the high-angle group for both women and men. For women, the thickness values at the labrale superius, labrale inferius, and pogonion were found to be statistically significantly smaller in the high-angle group (11.49 ± 1.05 mm, 12.70 ± 1.92 mm, and 11.64 ± 2.65 mm, respectively) compared with the values in the normal-angle group (13.31 ± 2.01 mm, 15.08 ± 1.94 mm, and 14.69 ± 3.08 mm, respectively) (P < .05, P < .05, and P < .01, respectively). For men, however, no statistically significant differences were found among the vertical growth patterns (P > .05).Conclusion:Women had statistically significantly thinner thickness at the labrale superius, labrale inferius, and pogonion in the high-angle group compared with the normal-angle group.     

不同骨面型成人颏部软组织厚度的CBCT初步研究

目的 利用CBCT结合Dolphin Imaging 11.0软件对不同骨面型成人颏部软组织厚度进行探讨研究。 方法 选择拍摄CBCT影像的骨性Ⅰ类、骨性Ⅱ类、骨性Ⅲ类患者各20例,利用Dolphin Imaging 11.0图像分析软件进行三维重建,并对重建后的3D图像进行定位,建立三维参考系,定位硬组织颏前点（Po）、软组织颏前点(Pos)的三维坐标等,利用公式计算颏部软组织厚度即（Po-Pos）之间的距离及在各个坐标轴上的差异。 结果 颏部软组织厚度在骨性Ⅰ类、骨性Ⅱ类、骨性Ⅲ类的男、女性别间无统计学差异（P>0.05）,颏部软组织厚度计算数值在骨性Ⅰ类、骨性Ⅱ类、骨性Ⅲ类未发现显著性差异,但在三维坐标系中,硬组织颏前点Po (x1,y1,z1)在Z轴上骨性Ⅰ类与骨性Ⅱ类和骨性Ⅱ类与骨性Ⅲ类存在显著性差异（P<0.05）,在X轴的线距上,骨性Ⅰ类与骨性Ⅲ类、骨性Ⅱ类与骨性Ⅲ类之间存在显著性差异（P<0.05）。 结论 不同骨面型人群颏部软组织厚度在三维坐标系中存在一定差异,主要体现在水平面上的差异,硬组织颏前点在冠状面上骨性Ⅰ类与骨性Ⅱ类和骨性Ⅱ类与骨性Ⅲ类间有一定的差异,这对正畸治疗的临床诊断、治疗计划的制定等提供一定的参考价值。     

下颌前突患者术后软组织侧貌美学缺陷分析

目的研究下颌前突畸形患者术后软组织侧貌与中国美貌人群的差异,分析其存在的美学缺陷,为进一步提高治疗效果提供参考。 方法选取经正畸-正颌联合治疗术后6个月以上的下颌前突畸形患者52例（男31例、女21例）,拍摄头颅定位侧位片进行软组织侧貌测量,并与王兴所测中国美貌人群之测量结果进行比较分析,男女两组分别与美貌人群组数据进行独立样本t检验。 结果与美貌人群相比,男女两组下颌前突畸形患者术后软组织侧貌测量项目均有多点差异,主要表现为：（1）男性患者Ns、Prn、Cm及Sn X坐标值均较小（P<0.05）,女性仅Ns点X坐标值较小（P<0.05）,提示鼻根部较扁平;（2）两组颏唇沟角增大（P<0.05）,Si点、UL点至"审美平面"距离减小（P<0.05）,LL点基本位于"审美平面"右侧,为负值（P<0.05）,提示术后颏唇沟变浅,下唇较突,颏部轮廓欠佳;（3）两组患者面中份与面下份软组织线距比减小（P<0.05）,提示面中份与面下份比例不协调,面下三分之一长度相对较长;（4）两组患者C-Gn′软组织线距减小（P<0.05）,同时C-Gn′/Sn-Gn′线距比减小（P<0.05）,提示侧面观下颌缘长度减小。 结论患者上下颌发育不协调、手术方案的选择及正畸治疗等均影响其术后的侧貌美观。下颌前突畸形患者单行下颌后退手术其软组织侧貌存在不同程度美学缺陷,有必要行进一步综合治疗以提高美学效果。     

The soft tissue cover of the mandibular condyle

Age-related changes of the composition of the extracellular matrix of the soft tissue cover of the mandibular condyle (STC), especially of the large proteoglycans, have been investigated. Proteoglycans were extracted from the STC of neonatal, juvenile and adult domestic pigs, fractionated by density gradient centrifugation and analyzed by electrophoresis/Western blotting.Experiments revealed firstly that a large CS/KS proteoglycan (aggrecan) is an essential constituent of the STC at all ages. This proteoglycan is required for nutrition of avascular tissues, and age-related changes in its average size and substitution with KS (keratan sulfate) may be a response to altered functional loading and tissue architecture of the STC. Secondly it was shown that a large CS/DS (chondroitin sulfate/dermatan sulfate) proteoglycan characterized by a doublet of core proteins at 200 and 250 kDa, thereby resembling perlecan, is present in the tissue of adults, but not of neonates and juveniles. Thirdly a large CS/DS proteoglycan characterized by core proteins at 350, 450 and 550 kDa, thereby resembling versican, was present in juveniles. It was detectable only weakly in neonates and not in adults. Results of core protein analysis were confirmed by results of agarose gel electrophoresis/Western blotting of the undigested proteoglycans isolated directly from the tissue extracts.Versican is believed to destabilize cell-matrix interactions required for cell proliferation and differentiation. In this context, presence of versican-like proteoglycans in the STC of growing individuals and its disappearance in adults appears to be related to the growth potential of the mandibular condyle.     

Nance弓支抗下双颌前突患者拔牙矫治后软组织变化及与硬组织关系的研究

目的 探讨传统支抗下双颌前突拔牙患者正畸治疗后软组织的变化及与硬组织变化的关系.方法 应用回顾性研究方法,对满足纳入标准的29例拔除四个第一双尖牙并应用Nance弓增加支抗的女性成人双颌前突患者进行治疗前后的手工X线头影测量分析.测量软硬组织项目35项,应用SPSS 15.0软件进行统计分析.治疗前后的变化用配对t检验,软组织变化的相关分析用Pearson相关分析.结果 软组织测量项目显示,经过正畸治疗患者的上、下唇突度、软组织A点及B点的突度减小,颏唇沟深度增加,差异有统计学意义（P＜0.01）;上、下唇基底厚度减小,上唇突厚度增大,下唇突厚度减小,差异有统计学意义（P＜0.01）.而上唇长度、软组织颏前点突度在正畸治疗前后差异无统计学意义.与上唇突度变化（ ΔUL-SL）相关的硬组织测量项目为ΔU1-SL（r=0.469,P＜0.01）;与下唇突度变化（△LL-SL）相关的硬组织测量为ΔSNA（r=0.436,P＜0.05）、ΔU1 -SL（r=0.374,P＜.05）、△L1-SL（r=0.478,P＜0.01）;上、下唇突度变化正相关.鼻唇角的变化与ΔU1-SL（r=-0.534,P＜0.01）、△UL-E（r=-0.394,P＜0.05）负相关,与△A’-SL（r=0.478,P＜0.05）、ΔULL（r=0.474,P＜0.05）及ΔA’-A（r=0.423,P＜0.05）正相关.颏唇沟深度（B’-E）与下切牙的内收（ΔL1-SL）及下唇突度变化（ΔLL-SL）正相关.上唇突度减小与上前牙内收的关系为1∶0.6（以审美平面评价）或1∶0.62（以蝶鞍点垂线评价）.下唇突度减小与下切牙内收关系是1∶1.13;而下唇变化与上前牙内收的关系则是1∶（0.83±0.21）（LL-SL/U1-SL）.结论 传统支抗控制下拔除四个双尖牙后双颌前突成人侧貌改善显著.面下部软硬组织间存在中度相关关系.     

Three-dimensional evaluation of the relationship between jaw divergence and facial soft tissue dimensions

Objective:To evaluate the relationship between mandibular divergence and vertical and transverse dimensions of the face.Materials and Methods:A sample was recruited from the orthodontic clinic of the University of Otago, New Zealand. The recruited participants (N  =  60) were assigned to three different groups based on the mandibular plane angle (hyperdivergent, n  =  20; normodivergent, n  =  20; and hypodivergent, n  =  20). The sample consisted of 31 females and 29 males, with a mean age of 21.1 years (SD ± 5.0). Facial scans were recorded for each participant using a three-dimensional (3D) white-light scanner and then merged to form a single 3D image of the face. Vertical and transverse measurements of the face were assessed from the 3D facial image.Results:The hyperdivergent sample had a significantly larger total and lower anterior facial height than the other two groups (P < .05), although no difference was found for the middle facial height (P > .05). Similarly, there were no significant differences in the transverse measurements of the three study groups (P > .05). Both gender and body mass index (BMI) had a greater influence on the transverse dimension.Conclusions:Hyperdivergent facial types are associated with a long face but not necessarily a narrow face. Variations in facial soft tissue vertical and transversal dimensions are more likely to be due to gender. Body mass index has a role in mandibular width (GoGo) assessment.     

Do masticatory functional changes influence the mandibular morphology in adult rats

Objective

This study aimed to investigate the effect of masticatory functional changes on the lateral view morphology of the mandible in adult rats.

Design

Sixty 21-day-old male Sprague–Dawley rats were divided into two groups. Sixteen received ordinary (hard) food during the whole experimental period (normal group). The remaining 44 received a soft diet during 21 weeks to develop a hypofunctional masticatory system. Then, the now adult animals were divided into two equal groups: one continued on a soft diet (hypofunctional group), and the other changed to an ordinary diet with the aim of functionally rehabilitating their masticatory system (rehabilitation group). After another 6 weeks all animals were sacrificed and their left mandible was dissected, photographed and customised cephalometric software was used to perform morphometric measurements.

Results

The area of the mandible was smaller in the hypofunctional compared to the normal group. Interestingly, the alveolar process was shorter in the normal group. Morphometric analysis revealed significant differences such as the area of the angular process and the inclination of the condylar process. The rehabilitation group was only marginally different compared to the hypofunctional group, although a general tendency to approach (catch-up) the normal group was observed, and one morphometric variable (condylar base inclination) was indeed significantly different.

Conclusions

Morphometric analysis revealed only marginal changes of the adult rat mandibular morphology during a 6-week period of masticatory function rehabilitation. However, the observed catch-up tendency might suggest that a longer rehabilitation period may have significant effect on mandibular morphology.     

高角拔牙病例治疗前后牙齿位移与软组织颏部改变的相关性研究

目的 分析高角拔牙病例正畸治疗前后牙齿位移与软组织颏部位置及曲线形态改变的相关性.方法 对60例高角拔牙病例(Ⅰ或Ⅱ类骨面型)正畸治疗前后的头颅定位侧位片进行7项牙性指标,3项骨性指标及2项软组织指标的定点测量分析,再通过Pearson简单直线相关分析,偏相关分析以及多元线性回归分析研究软硬组织变化的相关性.结果 Pearson简单直线相关分析证实,7项牙性指标中与软组织指标面角的改变相关的指标为U6-PP距与L6-MP距之和及U1-PP距;与软组织指标颏沟倾角的改变相关的为U6-PP距与L6-MP距之和、L1-NB距、U1-PP距及L1-MP距.偏相关分析显示U6-PP距与L6-MP距改变之和与面角和颏沟倾角的改变为强相关,且为间接相关.多元线性回归分析筛选出对面角和颏沟倾角的改变影响力较大的牙性指标:对面角影响大的只有U6-PP距与L6-MP距之和;对颏沟倾角影响大的有2项牙性指标,并按影响力大小排序:U6-PP距与L6-MP距之和的影响力大于L1-NB距.结论 在高角拔牙病例的正畸治疗中磨牙高度的改变与颏部位置及曲线形态的改变密切相关.     

西安地区陕西籍正常成人软组织X线头影测量研究

目的:建立西安地区陕西籍正常牙合成人软组织X线头影测量正常值标准,并与西安地区正常牙合青少年软组织X线头影测量值进行比较。方法:选取西安市18～22岁的在校学生正常牙合120名(男、女各半)。所有研究对象均在头颅定位仪的严格定位下,摄取其正中咬合位时的X线头颅侧面定位片;用绘图铅笔在透明硫酸纸上定点、描图,然后经由图形数值化仪输入计算机内进行测量并进行统计处理。结果:获得3种头影测量软组织分析法的正常值;其中有一些角度及线距测量结果与西安地区正常牙合青少年相比有显著性差异。结论:通过上述方法获得3种头影测量软组织分析法的正常值,可以用于指导临床。     

颏部骨移植及延期种植修复治疗成人齿槽裂的临床研究

目的：研究采用下颌骨颏部骨移植修复成人先天性齿槽裂骨缺损,延期行种植修复缺失牙,以探索成人齿槽裂序列治疗的方法。方法单侧齿槽裂成人患者10例,应用自体下颌骨颏部（正中联合处）取骨块行植骨修复裂隙骨缺损,骨愈合5个月后延期植入Dentinum植体11颗,经过5个月骨结合后行Ⅱ期手术,更换愈合基台,2周后取模,完成牙冠修复。结果齿槽裂区域成骨良好,种植体骨结合良好,种植牙戴牙半年后,种植体周围骨无吸收,美观功能效果良好。结论采用下颌骨颏部骨块修复成人齿槽裂骨缺损后延期种植修复可以作为先天性齿槽裂序列治疗中一种良好的治疗手段。     

双颌手术后颜面软组织侧貌改变的研究

目的 研究下颌前突伴上颌骨发育不全患者术后颜面软组织侧貌改变.方法 对20例下颌前突伴上颌骨发育不足病例进行术前后Χ线头影测量研究,用SPSS软件对测量值进行统计分析.结果 下唇突点(LI点)、颏唇沟点(Si点)软组织颏前点(PG点)分别以下中切牙点(li点)下牙槽座点(B点)硬组织颏前点(pg点)的92%、97%、92%后移而后移,并得出了相应的回归方程.结论 上颌软硬组织改变无明显相关性,下颌软硬组织改变有非常显著相关性.     

Evaluation of long-term soft tissue changes after bimaxillary orthognathic surgery in Class III patients

Objective:To assess soft tissues in the short and long term after bimaxillary surgery in Class III patients by comparing the hard tissue changes and results between time periods.Materials and Methods:Twenty-six Class III adult patients treated with bimaxillary surgery were included in the study. Cephalometric records were taken before surgery (T1) and 5 months (T2), 1.4 years (T3), 3 years (T4), and 5 years (T5) after surgery.Results:There was no significant relapse in skeletal parameters. Overjet was significantly reduced between T4-T3 time intervals (P < .01). There were significant increases in Sn-HR, ULA-HR, LLA-HR, B-B^∧ (P < .01), and B^∧-HR (P < .05) between T4-T3 time intervals. There was no significant change in the soft tissue parameters between T5-T4 time intervals.Conclusion:Soft tissue vertical relapse occurs in skeletally stabile Class III bimaxillary surgery patients in the first 3 years after surgery.     

颏部突度改变对面部美学的影响

目的 通过3D图像研究颏部突度改变对面部美学的影响,比较正畸医师、口腔全科医师及普通大众对颏部突度变化的美学认知差异,为临床治疗方法的选择提供定量参考。方法 使用3dMD立体摄影技术,获取志愿者的三维面部图像,使用Geomagic Wrap 2015软件,以2 mm为梯度,使软组织颏前点沿矢状轴前后移动,移动幅度为零子午线前后10 mm。选取正畸医师、口腔全科医师及普通大众3组评价者,以VAS评分对图像进行评价,使用SAS 9.4建立线性混合效应模型,对数据进行方差分析。结果 纳入调查对象243人,其中口腔正畸医师90人,口腔全科医师101人,普通大众52人。研究发现,颏部突度变化对VAS评分有显著影响,软组织颏前点位于零子午线上时评分最高,颏部每后缩2 mm,VAS评分下降0.8910;每前突2 mm,VAS评分下降1.0958,有显著差异（P<0.01）。正畸医师组及普通大众组在颏部后缩超过6 mm、口腔全科医师组在颏部后缩超过4 mm时平均VAS评分低于5,3组人群在颏部前突达到6 mm时平均VAS评分低于5,需要进行治疗。颏部突度变化时,3组人群评分变化无统计学差异,性别及年龄亦无显著影响。结论 颏部突度变化对面部美学有显著影响,软组织颏前点位于零子午线时美学效果最佳,颏部前突达到6 mm或颏部后缩超过6 mm时治疗需求较大。正畸医师、口腔全科医师及普通大众对颏部突度变化的美学认知程度无显著差异。     

Three-dimensional evaluation of soft tissue change gradients after mandibular setback surgery in skeletal Class III malocclusion

Objective:To evaluate whether mandibular setback surgery (MSS) for Class III patients would produce gradients of three-dimensional (3D) soft tissue changes in the vertical and transverse aspects.Materials and Methods:The samples consisted of 26 Class III patients treated with MSS using bilateral sagittal split ramus osteotomy. Lateral cephalograms and 3D facial scan images were taken before and 6 months after MSS, and changes in landmarks and variables were measured using a Rapidform 2006. Paired and independent t-tests were performed for statistical analysis.Results:Landmarks in the upper lip and mouth corner (cheilion, Ch) moved backward and downward (respectively, cupid bow point, 1.0 mm and 0.3 mm, P < .001 and P < .01; alar curvature-Ch midpoint, 0.6 mm and 0.3 mm, both P < .001; Ch, 3.4 mm and 0.8 mm, both P < .001). However, landmarks in stomion (Stm), lower lip, and chin moved backward (Stm, 1.6 mm; labrale inferius [Li], 6.9 mm; LLBP, 6.9 mm; B′, 6.7 mm; Pog′, 6.7 mm; Me′, 6.6 mm; P < .001, respectively). Width and height of upper and lower lip were not altered significantly except for a decrease of lower vermilion height (Stm-Li, 1.7 mm, P < .001). Chin height (B′-Me′) was decreased because of backward and upward movement of Me′ (3.1 mm, P < .001). Although upper lip projection angle and Stm-transverse projection angle became acute (Ch_Rt-Ls-Ch_Lt, 5.7°; Ch_Rt-Stm-Ch_Lt, 6.4°, both P < .001) because of the greater backward movement of Ch than Stm, lower lip projection angle and Stm-vertical projection angle became obtuse (Ch_Rt-Li-Ch_Lt, 10.8°; Ls-Stm-Li, 23.5°, both P < .001) because of the larger backward movement of Li than labrale superius (Ls).Conclusions:Three-dimensional soft tissue changes in Class III patients after MSS exhibited increased gradients from upper lip and lower lip to chin as well as from Stm to Ch.     

不同拔牙模式正畸矫治对成年女性牙弓宽度和软组织正貌的影响

目的：研究不同拔牙模式对安氏Ⅱ1错牙合成年女性治疗前后牙弓宽度和面部软组织正貌的影响。方法：将40例安氏Ⅱ1错牙合需拔牙矫治的成年女性患者随机分为两组。 A组拔除上颌2颗第一前磨牙,下颌拔除2颗第二前磨牙,B组拔除4颗第一前磨牙。分析比较两组病例治疗前后牙弓宽度和面部软组织正貌指标的变化。结果：正畸治疗后,组内比较显示两组病例上下颌尖牙间宽度均增加,上下颌第一磨牙间宽度均减小,差异有统计学意义（P＜0.05）;组间比较仅下颌尖牙和下颌第一磨牙间宽度变化有统计学意义（P＜0.05）,B组下颌尖牙宽度增加量大于A组,B组下颌第一磨牙牙弓宽度减小量小于A组。治疗前后比较,两组病例在面宽、口裂宽、下颌角间宽、容貌面长和鼻下颏下距的差异均无统计学意义（P＞0.05）。Pearson相关性分析显示牙弓宽度与软组织正貌指标之间无相关关系（P＞0.05）。结论：安氏Ⅱ1错牙合病例正畸矫治后成年女性软组织正貌的变化不受拔牙模式影响,不同拔牙模式仅影响矫治后牙弓宽度的变化。     

Soft tissue aneurysmal bone cyst of the mandible: Report of a case

We report the case of a 17-year-old boy with a soft tissue aneurysmal bone cyst (STABC) located in the posterior aspect of the right mandible. Conventional radiography revealed no positive findings. On the computed tomography scan, the lesion appeared to have a non-uniform intralesional density. Magnetic resonance imaging revealed an abnormal soft tissue masses with cystic component in the superficial part of right mandibular body and angle with intact cortex. Following histopathological examination, fibro-histiocytic proliferation, blood-filled spaces and multinucleated giant cells were seen and the lesion was diagnosed as a STABC. The mass together with underlying bone and periosteum on its periphery was surgically resected under general anesthesia. Thirty-six months after surgery the patient was assessed at outpatient clinic and found no sign of recurrence This may be only the first reported case of the mandible in the English literature of this extremely rare benign tumor occurring in soft tissue.     

面中部牵张成骨术软组织变化的三维预测

目的:通过建立颅颌面软硬组织三维有限元模型,预测面中部牵张成骨术的软组织变化。方法:通过1名骨性Ⅲ类面型的年轻女性的颅颌面软硬组织的三维有限元模型的建立,在该模型上模拟Le Fort Ⅰ、Ⅱ、Ⅲ型3种截骨手术加载工况,使得每种骨块分别在FH平面、功能性(牙合)平面和功能性(牙合)平面顺时针旋转10°平面3种方向上前移5mm。结果:Le Fort Ⅰ、Ⅱ、Ⅲ型手术后软组织的变化区别表现为不同范围的前移,其中Le Fort Ⅰ型术后鼻尖前移1.25mm、上唇前移4.9mm,鼻唇角增加;而Le FortⅡ型手术后鼻尖点及上唇点均前移4.9mm,鼻唇角无增加:Le FortⅢ型术后除与Ⅱ型一致的变化外,还有睑缘点前移2mm。结论:通过软硬组织三维有限元模型的建立,可成功模拟面中部牵张成骨术后软组织的变化。     

2种不同种植体植入对种植体周围软组织的影响

目的: 研究2种种植体对种植体周围软组织的影响。方法: 选择2020年12月—2021年2月普陀区眼病牙病防治所收治的单颗后牙缺失且需行种植修复的患者40例,其中植入骨水平种植体10例,软组织水平种植体30例。在完成种植冠修复当天、3个月、6个月及12个月时比较2组种植体的探诊深度,检测种植体龈沟液中天冬氨酸转氨酶（AST）和碱性磷酸酶（ALP）水平。采用SPSS 17.0软件包对数据进行统计学分析。结果: 修复完成当天、3个月、6个月及12个月,软组织水平种植体的探诊深度和ALP水平均显著低于骨水平种植体（P<0.05）。其中修复完成当天,软组织水平种植体的AST显著低于骨水平种植体（P<0.05）。随着时间增加,骨水平种植体龈沟液中的AST迅速降低,最后与软组织水平种植体接近（P>0.05）。结论: 尽管骨水平种植体和软组织水平种植体均具有良好的临床使用效果,但软组织水平种植体周围的软组织表现出更好的稳定性。     

早期应用卵圆形桥体成形缺牙区软组织形态的临床研究

目的评价拔牙后早期应用卵圆形桥体成形缺牙区软组织形态的临床效果。方法选择上颌前牙区拟拔除患牙后行固定局部义齿修复的患者16例,于拔牙后1～2周行基牙牙体预备并制作树脂临时固定桥,桥体设计为卵圆形,拔牙后3～4个月制作永久修复体。修复完成后第3、6、12和24个月复诊。记录桥体处牙龈乳头指数、龈缘水平、角化龈宽度、改良菌斑指数及改良出血指数。结果本研究随访期内所有义齿行使功能良好。拔牙前及修复后24个月时近中牙龈乳头指数分别为2．19和2．38．远中牙龈乳头指数为2．13和2．31．改良菌斑指数为1．81和0．63,改良出血指数为1．13和0．25,龈缘水平位为10．59mm和10．88mm,角化龈宽度为3．66mm和3．53mm。牙龈乳头指数、龈缘水平和角化龈宽度的差异均无统计学意义（P〉0．05）;而改良菌斑指数和改良出血指数均降低,差异有统计学意义（P〈0．01）。结论拔牙后早期应用卵圆形桥体成形缺牙区软组织形态町获得良好的临床效果。     

软组织形变建模在虚拟手术中的应用进展

虚拟现实（virtual reality, VR）技术通过其独具的沉浸感、交互性以及想象性,在医学领域正发挥着越来越重要的作用。基于VR技术的虚拟手术系统在颅颌面畸形的诊断、治疗及操作培训中能够为手术医师提供身临其境的逼真感,利用该技术可以进行术前设计、术后预测,制定个体化最佳治疗方案。在过去几十年内,世界范围内已经开发出基于虚拟现实技术的数个手术模拟系统,涵盖颅颌面整形、眼外科、神经外科、膝关节外科、腹腔镜外科等众多领域。但对于虚拟手术系统的核心—软组织的形变建模,一直是国内外学者研究的难题。本文就基于虚拟现实技术的常用的软组织建模方法的研究进展作一综述。