成人骨性Ⅲ类错(牙合)下颌骨联合形态与下切牙位置的关系

目的了解成人严重骨性Ⅲ类错（牙合）患者下颌骨联合形态结构与下切牙位置的相关关系。方法选择需接受正颌手术的严重骨性Ⅲ类错（牙合）患者70人（ANB〈-3°）,男性37名,女性33名,年龄范围18—28岁。根据下颌平面角的大小将患者分为均角（43例）及高角（27例）二组。利用X线头影测量进行下颌骨联合形态结构与下切牙位置的相关分析。结果高角组较均角组下颌骨联合形态更高、更窄,高角组下切牙倾斜程度与下颌骨联合长轴的倾斜度有密切关系（r=0．78117）,而均角组下切牙倾斜程度与下颌骨联合牙槽骨长轴倾斜度有密切关系（r=0．81774）,同时下颌骨联合基骨唇侧骨板的舌倾角度在高角组较均角组有减小的趋势。结论治疗骨性Ⅲ类错（牙合）患者时需考虑下颌骨联合的形态,尤其高角病例由于下颌骨联合的形态较高较窄,提示我们去代偿或代偿性移动下切牙的范围可能要小。     

Effect of the inclination of a maxillary central incisor on periodontal stress: Finite element analysis

Objective:To determine the effect of labiolingual inclination of a maxillary central incisor on the magnitude and distribution of stresses within the periodontal space.Materials and Methods:Five three-dimensional finite element models of a right maxillary central incisor were created with 0°, 10°, 20°, 30°, and 40° inclination. Each incisor model was subjected to a 1 N lingual-directed force and 6–12 N·mm countertipping moment on the labial surface. The stress level within the periodontal ligament was calculated in terms of maximum principal stresses.Results:With increased inclination, compressive stresses tended to increase whereas tensile stresses tended to decrease. The location where compressive stress was prevalent changed from the midroot area to the apical area on the lingual side, while the area where tensile stresses were predominant changed from the midroot area to the cervical area on the labial side.Conclusion:There are more compressive stresses concentrated at the apex of incisors with a high degree of inclination than in incisors that are more upright. This may be associated with the higher clinical incidence of apical root resorption found in inclined maxillary central incisors.     

不同倾斜度体位对腹腔镜全子宫切除患者眼内压和术后舒适度的影响

目的：观察不同倾斜度头低臀高位对腹腔镜全子宫切除患者眼内压和术后舒适度的影响。方法选择80例妇科腹腔镜手术患者作为研究对象,均为美国麻醉协会（ ASA）麻醉分级Ⅰ级。按随机数字表法将患者随机分为头低位15＆#176;组和头低位30°组,每组40例。监测患者基础眼内压（ T0）、气腹并改变体位后30 min（ T1）、60 min（ T2）和气腹结束后10 min（ T3）时的眼内压。24 h内随访患者,询问患者术后舒适度。结果头低位15°组患者T1、T2时眼内压分别为（18．16±2．16）,（19．60±2．18）mmHg,分别低于头低位30°组的（19．21±2．17）与（20．87±2．17）mmHg,差异有统计学意义（t值分别为2．1689,2．6113;P＜0．05）。头低位15℃;组患者术后眼部不适、肩痛的发生率分别为2．5％,7．5％,分别低于头低位30°组的20．0％,25．0％,差异有统计学意义（χ2值分别为4．5075,4．5006;P＜0．05）。两组恶心、呕吐和小腿疼痛的发生率比较,差异无统计学意义（χ2值分别为0．2381,0．0000;P＞0．05）。结论妇科腹腔镜手术15°头低位比30°头低位对患者眼内压影响更小,术后舒适度更高。     

Finite Element Analysis of Mobile-bearing Unicompartmental Knee Arthroplasty: The Influence of Tibial Component Coronal Alignment

Background:

Controversies about the rational positioning of the tibial component in unicompartmental knee arthroplasty (UKA) still exist. Previous finite element (FE) studies were rare, and the results varied. This FE study aimed to analyze the influence of the tibial component coronal alignment on knee biomechanics in mobile-bearing UKA and find a ration range of inclination angles.

Methods:

A three-dimensional FE model of the intact knee was constructed from image data of one normal subject. A 1000 N compressive load was applied to the intact knee model for validating. Then a set of eleven UKA FE models was developed with the coronal inclination angles of the tibial tray ranging from 10° valgus to 10° varus. Tibial bone stresses and strains, contact pressures and load distribution in all UKA models were calculated and analyzed under the unified loading and boundary conditions.

Results:

Load distribution, contact pressures, and contact areas in intact knee model were validated. In UKA models, von Mises stress and compressive strain at proximal medial cortical bone increased significantly as the tibial tray was in valgus inclination >4°, which may increase the risk of residual pain. Compressive strains at tibial keel slot were above the high threshold with varus inclination >4°, which may result in greater risk of component migration. Tibial bone resection corner acted as a strain-raiser regardless of the inclination angles. Compressive strains at the resected surface slightly changed with the varying inclinations and were not supposed to induce bone resorption and component loosening. Contact pressures and load percentage in lateral compartment increased with the more varus inclination, which may lead to osteoarthritis progression.

Conclusions:

Static knee biomechanics after UKA can be greatly affected by tibial component coronal alignment. A range from 4° valgus to 4° varus inclination of tibial component can be recommended in mobile-bearing UKA.     

AngleII~1错矫治前后软组织侧貌与切牙倾斜度的变化及相关分析

目的探讨AngleII1错牙合面部软组织与切牙倾斜度之间的相互关系,为临床正畸治疗提供理论依据。方法对25例AngleII1错牙合病例矫治前后X线头影测量片进行分析,共测量6个硬组织项目和5个软组织项目,用SPSS10.0分析矫治前后面部软组织与切牙倾斜度的变化及相关关系。结果上下切牙倾斜度对侧貌美学指标均有相关性,但AngleII1错牙合主要是上切牙倾斜度的减小对侧貌产生影响。结论AngleII1错牙合治疗中通过减小上切牙的倾斜度可使侧貌美观。     

Preoperative Leg Length Discrepancy >2 cm in the Supine Decubitus Position May Induce Compensatory Pelvic Obliquity in Patients during Total Hip Arthroplasty

Objectives

The leg length discrepancy (LLD) in the supine decubitus position may influence the inclination angle of the acetabular component during total hip arthroplasty (THA). The relationship among LLD, pelvic obliquity, and inclination angle of the acetabular component has not been well studied. This study aimed to evaluate the relationship between LLD in supine position and changes in the inclination angle of the acetabular components during THA, and the compensatory ability of the pelvis based on LLD and inclination.

Methods

A total of 135 patients were prospectively classified into three groups according to the preoperative LLD in the supine decubitus position: the cranial type group had a positive LLD value; the fixed type group had LLD = 0; and the caudal type group had a negative LLD value. Patients in the cranial type group and caudal type group were divided into four subgroups based on the LLD value (either positive or negative): LLD >3 cm subgroup; 2 ≤ LLD ≤ 3 cm subgroup; 1 ≤ LLD < 2 cm subgroup; and LLD <1 cm subgroup. The targeted and final inclination of the acetabular component was measured intra- and postoperatively.

Results

The results showed a significant difference in the targeted and final inclination angles among the patients in the cranial type and the caudal type groups. In the caudal type group, increased inclination was observed in the patients of LLD >3 cm subgroup (mean 3.13°) and 2 ≤ LLD ≤ 3 cm subgroup (mean 5.17°) after THA, respectively. Decreased inclination (mean, 6.16°) was observed in 2 ≤ LLD ≤ 3 cm subgroup in the cranial type group after THA.

Conclusions

Our findings revealed that in patients with discrepancy greater than 2 cm, postural pelvic obliquity imposed a remarkable influence on the inclination.     

Reproducibility of gait parameters at different surface inclinations and speeds using an instrumented treadmill system

Instrumented treadmill systems allow the practical assessment of gait parameters under several walking conditions. Aim of this study was to evaluate the reproducibility of gait parameters at different surface inclinations and walking speeds using an instrumented treadmill system in healthy individuals. A total of 20 subjects (10 women) with a mean age of 31 years were evaluated with an instrumented treadmill system (FDM-T, Zebris Medical GmbH) during two identical test sessions. Spatial (step length, step width, foot rotation), temporal (cadence, single-limb support, step time) and ground reaction force (heel force, toe force, time to heel force, time to toe force) gait parameters were assessed at three treadmill inclinations (level, uphill, downhill) and five speeds (2, 3, 4, 5, 6 km/h). Between-day reproducibility was evaluated with smallest detectable changes for agreement and intraclass correlation coefficients for reliability. Low agreement and reliability were observed for (i) step length, cadence and step time during slow (2 and 3 km/h) and uphill walking and (ii) time to heel force and time to toe force under the majority of walking conditions. The instrumented treadmill system used in this study provided reproducible measurements for the majority of the evaluated spatial, temporal and ground reaction force gait parameters in healthy individuals. The assessment of time to heel/toe force should be however avoided, and particular care should be taken for some spatial (step length) and temporal (cadence and step time) parameters while walking uphill and/or at slow speeds.     

Appraisal of the relationship between tooth inclination,dehiscence, fenestration,and sagittal skeletal pattern with cone beam computed tomography

Objectives:To examine the relationship between sagittal facial pattern and dehiscence/fenestration presence in conjunction with buccolingual tooth inclination by using cone beam computed tomography.Materials and Methods:The study was carried out on the cone beam computed tomography scans of the following three groups of patients (n = 20 in each group): Class I, Class II, Class III. Buccolingual tooth inclination, buccal dehiscence/fenestration presence, and lingual dehiscence/fenestration presence were evaluated on each tooth. Analysis of variance, Kruskall-Wallis H, Scheffe, and chi-square tests were used for statistical comparisons.Results:Differences (P < .05) were observed between the groups for inclination of upper incisors and all lower teeth except for second molars. Dehiscence prevalence in the upper buccal and posterior buccal regions was higher (P < .05) in the Class I group when compared with the other groups. Lower buccal and anterior buccal regions showed higher (P = .0001) dehiscence prevalence in all groups. No difference was observed in fenestration prevalence between the groups. The upper buccal and anterior buccal regions showed higher (P = .0001) fenestration prevalence in all groups.Conclusions:Orthodontists must consider concealed alveolar defects in treatment planning to avoid gingival recession or tooth mobility.