微螺钉支抗考虑的国人正常颌骨皮质厚度CT测量分析

Objective To determine the thickness of bone cortex in upper and lower jaws where miniscrews implant was inserted.Methods Thirty chinese adults(18～40 year-old)were examined with spire CT,and three-dimensionalimages were produced.The thickness of bone cortex in upper and lower jaws was measured.The data were analyzed statistically.Results Fourty-eight measurements were from 1.73 mm to 10.67 mm on average,and the thinnest postion was 0.8 mm.34 measurements were found no significant differences on both sides and 12 measurements with significant differences between right and left side.Conclusions Implantation must be cautious for thin cortex near the center incisor apex.Because the big differences of cortex thickness existed individually,CT examination was helpful in determining the location and direction of miniscrew implants insertion.     

长春市某小学7～12岁儿童福赛斯坦氏菌和中间普氏菌分布状态调查

Objective To detect the presence of Tannerella forsythus(Tf)and Prevotella intermedia (Pi) using polymerase chain reaction(PCR) in the oral plaque samples from children and investigate the relationship between bacteria and clinical parameters. Methods A total of 151 children aged 7 to 12 years were selected from Changchun primary school. The supragingival plaque sample was collected from the mesiobuccal and labial surfaces of the right maxillary central incisor ( FDI 1 ) and the right maxillary first molar ( FDI 6 ). Extracted DNA from plaque samples was used for PCR analysis. Intraoral examination,probing depth (PD) and bleeding on probing (BOP) were performed and recorded. Results The detection rate for Tf was 40. 3% ( 118/293 ) and Pi was 46. 4% ( 136/293 ) in supragingival plaque. The detection rates for Tf and Pi in molars were much higher than those in incisors( P ＜0. 01 ). The detection rate of Tf and Pi was positively related to BOP + and PD. The detection rate for Pi decreased gradually with age, and the detection rate for Tf was highest in the group aged 7 to 8 and the detection rates for Tf and Pi were higher in the gingiva with BOP + than that with BOP - ( P ＞ 0. 05 ). The detection rates for Tf increased remarkably with BOP + and especially when PD was greater than 4 mm. Conclusions Detection rates of putative periodontal pathogens from healthy children of 7 to 12 years of age were high. The detection rates for Tf and Pi in molars were much higher than those in incisors, and the presence of Tf and Pi in supragingival plaque was related to periodontal parameters.     

非综合征性单侧完全性唇腭裂恒牙发育异常的研究

目的 经回顾性研究了解非综合征性单侧完全性唇腭裂患者恒牙发育异常的情况.方法 收集244例植骨期非综合征性单侧完全性唇腭裂患者的影像学资料,记录和统计分析恒牙发育异常.结果 在本研究中各种恒牙异常的发生率为:先天缺失163例(269颗)(163/244,66.8%),最常累及的牙位是上颌侧切牙;畸形牙82例(85颗)(82/244,33.6%),绝大多数为上颌侧切牙的小牙畸形;额外牙12例(12颗)(12/244,4.9%),多发生于裂区,表现为畸形小牙.牙位发育异常的性别比较发现,非裂侧上颌仅侧切牙缺失,男性高于女性(P<0.05).裂侧的先天缺牙、额外牙和畸形牙的发生率均高于非裂侧,差异有统计学意义(P<0.01),上下颌均有相同发现.结论 非综合征性单侧完全性唇腭裂患者各类牙齿发育异常的患病率均高于健康人群.裂侧的牙齿发育异常较非裂侧更为多见.

Abstract：

Objective To investigate the prevalence of dentM anomalies in Chinese children with complete unilateral cleft lip and palate(UCLP).Methods Dental histories and radiographs of 244 Chinese children with UCLP were collected.The diagnosis of dental anomalies waft based on panoramic radiographs before alveolar bone grafting.All patients were over 8 years old.Results In the UCLP group,66.8% of the patients was presented with hypodontia.The maxillary lateral incisors were the most common teeth affected,followed by maxillary second premolars,mandibular incisors and mandibulax second premolars.A total of 33.6%the patients Was presented with dental malformation,most were mierodontic laterel incisors.A total of 4.9% the patients was presented with hyperdontim The supernumerary teeth were more frequently found in the cleft region.The prevalence of missing maxillary lateral incisor in the noneleft side was statistically different between genders,which was higher in male(P<0.050).This group of Chinese children with UCLP demonstrated significantly higher prevalence of hypodontia,hyperdontia,and malformation on the cleft side than on the noncleft side(P<0.01).Conclusions Hypodontia is the most common type of dental anomalies.The prevalence of dental anomalies is higher in the UCLP patients than in the normal population.Dental anomalies occur more frequently on the cleft side than on the nonclefi side.     

(牙合)面厚度与肩台宽度连续变化的下颌第一磨牙全瓷冠三维有限元分析

目的 探讨(牙合)面厚度和肩台宽度同时连续变化情况下下颌第一磨牙全瓷冠的优化设计,以期为全瓷冠的临床设计提供理论基础.方法 运用逆向工程及计算机辅助设计技术建立(牙合)面厚度和肩台宽度连续变化的下颌第一磨牙三维有限元模型,设定(牙合)面厚度变化范围为1～3 mm,肩台宽度变化范围为0.4～1.2 mm,并在全瓷冠颊尖垂直向(牙合)面加载225 N的力,观察验面厚度和肩台宽度同时变化对全瓷冠、粘接剂、基牙、牙周膜和牙槽骨等效应力峰值的影响,同时进行灵敏度分析.结果 随着(牙合)面厚度和肩台宽度的增加,除牙周膜和牙槽骨的等效应力峰值无明显变化外,全瓷冠、粘接剂和基牙的等效应力峰值均下降.当(牙合)面厚度≥1.87 mm、肩台宽度≥0.66 mm时,全瓷冠、粘接剂和基牙的应力响应曲线斜率均位于-1～1之间,即在此区间内等效应力峰值变化相对较小.灵敏度分析显示,肩台宽度对全瓷冠和基牙等效应力峰值的影响较大,(牙合)面厚度对粘接剂等效应力峰值的影响较大.结论 在本项研究所设定的参数范围内,下颌第一磨牙全瓷冠的(牙合)面厚度应不小于1.87 mm,肩台宽度应不小于0.66 mm.

Abstract：

Objective To investigate the effect of different occlusal thickness and shoulder finish line depth on stress distribution of all-ceramic crowns and to select optimal occlusal thickness and shoulder finish line depth using continuous variation of parameters. Methods This analysis was performed using mandibular first molar finite element modl. The range of occlusal thickness was set from 1 mm to 3 mm, and that of shoulder finish line depth was from 0. 4 mm to 1.2 mm. Load of 225 N was applied perpendicularly to the occlusal surface of the tooth at all buccal cusps to simulate functional occlusal force. The maximum equivalent stresses in crown, cement layer, abutment, periodontal ligament, alveolar bone were calculated, and the sensitivities of stresses to the variables were also evaluated. Results The maximum equivalent stresses in crown, cement layer and abutment decreased as occlusal thickness and shoulder finish line depth were increased, while no obvious change were found in maximum equivalent stresses in periodontal ligament and alveolar bone. When occlusal thickness exceeded 1.87 mm and shoulder finish line depth exceeded 0. 66 mm,the tangent slope rate of the maximum equivalent stress response curves ranged from - 1 to 1. Data indicated that occlusal thickness played a more important role in reducing maximum equivalent stress in cement layer than finish line depth did, and shoulder finish line depth was a more effective parameter in reducing maximum equivalent stress in crown and abutment than occlusal thickness was. Conclusions Occlusal thickness exceeding 1.87 mm and shoulder finish line depth exceeding 0. 66 mm are optimal design for ceramic crown on mandibular first molar from biomechanical point of view.     

Clinical effects of Angle's Ⅱ1 cases in Alignment with Incognito System

Objective The aim is to reveal the dentofacial changes of Angle Ⅱ1 cases during alignment phase using Incognito lingual orthodontic appliance. Methods Nineteen patients (8 Male and 11 female, aging from 12y to 23y) with Angle Ⅱ1 malocclusion were selected for lingual orthodontic treatment with four premolars extraction. Customized lingual orthodontic appliance (IncognitoTM) was used. Cephalometric radiographs and alginate impressions were taken before treatment and at the end of alignment. The comparison between pre-treatment and post-alignment were analyzed by Paired-Sample Wilcoxon Signed Rank Test through SPSS Statistical Package.Results From the Cephalometric analysis, the following changes were found significantly different (P＜0.05). U1/SN decreased 7.70°. U1/NA decreased 7.94°with 2.85 mr. L1/NB decreased 4.60°with 1.8mm. MP/SN increased 1.52°. L6-MP increased 0.51 mm. L1-MP decreased 1.29mm. OB decreased 1.18mm. From the model analysis, the following changes with significant differences were demonstrated. Upper and lower intercanine widths and lower intermolar widths increased 2.39mm,2.60mm and 1.26mm respectively. Upper arch depth from molar to incisor decreased 2.42mm. The curve of spee became shallow by 1.11mm. Conclusion During alignment phase, the upper and lower incisors tipped lingually with profile improved. The overbite decreased with lower incisors intruded, and the lower molars extruded with mandibular plane angle increased. It implied that lingual appliance would be helpful for lower angle cases with deep overbite, and cautions should be taken from the initial phase during lingual orthodontic treatment in high angle cases.     

Clinical effects of Angle's Ⅱ1 cases in Alignment with Incognito System

Objective The aim is to reveal the dentofacial changes of Angle Ⅱ1 cases during alignment phase using Incognito lingual orthodontic appliance. Methods Nineteen patients (8 Male and 11 female, aging from 12y to 23y) with Angle Ⅱ1 malocclusion were selected for lingual orthodontic treatment with four premolars extraction. Customized lingual orthodontic appliance (IncognitoTM) was used. Cephalometric radiographs and alginate impressions were taken before treatment and at the end of alignment. The comparison between pre-treatment and post-alignment were analyzed by Paired-Sample Wilcoxon Signed Rank Test through SPSS Statistical Package.Results From the Cephalometric analysis, the following changes were found significantly different (P＜0.05). U1/SN decreased 7.70°. U1/NA decreased 7.94°with 2.85 mr. L1/NB decreased 4.60°with 1.8mm. MP/SN increased 1.52°. L6-MP increased 0.51 mm. L1-MP decreased 1.29mm. OB decreased 1.18mm. From the model analysis, the following changes with significant differences were demonstrated. Upper and lower intercanine widths and lower intermolar widths increased 2.39mm,2.60mm and 1.26mm respectively. Upper arch depth from molar to incisor decreased 2.42mm. The curve of spee became shallow by 1.11mm. Conclusion During alignment phase, the upper and lower incisors tipped lingually with profile improved. The overbite decreased with lower incisors intruded, and the lower molars extruded with mandibular plane angle increased. It implied that lingual appliance would be helpful for lower angle cases with deep overbite, and cautions should be taken from the initial phase during lingual orthodontic treatment in high angle cases.     

Peer assessment rating index analysis of different extraction modality in skeletal Class Ⅲ malocclusions

Objective To assess the effect of different extraction modalities on treatment outcomes in skeletal Class Ⅲ malocclusions. Methods One hundred and nine skeletal Class Ⅲ patients (50 males and 59 females) with a mean age of 16.11±4.47 years were collected. The subjects were divided into four groups according to the extraction modality. They were T0 (non-extraction group), T1 (premolar extraction group), T2 (molar extraction group) and T3 (lower incisor extraction group). The PAR (peer assessment rating) index of each of the pre- and post-treatment cast was assessed. The differences of pre- and post-treatment weighed PAR score, reduction in weighed PAR score, percentage reduction in weighed PAR score and the degree of improvement between the four groups were compared. Results (1) Significant differences (P＜0.001＝ of the reduction in weighed PAR score and percentage reduction in weighed PAR score existed between different extraction modality groups. And the order of reduction from high to low was premolar extraction group, molar extraction group, non-extraction group and lower incisor extraction group.(2) There were no "Worse-no different" cases among the four groups. 97 cases were greatly improved and accounted for 89%. There were 12 cases (11%) in improved category. (3) Greatest improvement was found in premolar extraction group and the least improvement was found in lower incisor extraction group. Conclusions Treatment outcomes of the four extraction modalities in skeletal Class Ⅲ were all satisfied. Cautions should be paid in lower incisor extraction.     

正常(牙合)青年(牙合)平面与咀嚼运动轨迹的相关性分析

Objective To investigate the characteristics of and relationship between occlusal plane and masticatory path in young adults with individual normal occlusion, and to provide clinical implications on both morphological and functional reference of occlusal plane location Methods Forty-three young adults with individual normal occlusion were included. Lateral projections of cephalometric radiographs were taken. The parameters of anatomical landmarks were analyzed. The BioEGN mandibular kinesiography analyzer was used to record the path of incisal edge of mandibular central incisor movement during mastication. The Pearson's linear correlation analysis was performed to analyze the relationship of inclination of occlusal plane and data mentioned above with SPSS13. 0 software. Results The inclination of occlusal plane (the angle between occlusal plane and Camper's line OP-CP) was (2. 1 ± 3. 8) ° in youth with normal occlusion. Means of maximal distances of 3-dimensional masticatory mandibular movement paths were as follow; the vertical length was ( 20. 22 ± 4. 28) mm, the anterior-posterior width was ( 11.42 ± 2. 45) mm, and the lateral width was (8. 62 ± 1. 52) mm. The inclination of occlusal plane was negatively correlated to the lateral width of masticatory path in frontal plane (r = -0. 39, P <0. 05). Occlusal plane was approximately vertical to the opening and closing path in the vicinity of intercuspal position during mastication. The inclination of occlusal plane was positively related to occlusal plane-closing angles in the upper segments of closing path during mastication(P<0. 05). Masticatory axis angle was (66. 50 ±7. 98)° with no significant correlation to the inclination of occlusal plane (P >0. 05).Conclusions These results suggest that the sagittal inclination of occlusal plane can influence 3-dimensional morphology of masticatory path. The inclination of occlusal plane has a guiding effect on masticatory movement in the upper segments of closing path.     

OSAHS患者戴用口腔矫治器后颅面、上气道改变的追踪研究

Objective To investigate dental and skeletal changes of oral appliance treating of obstructive sleep apnea and hypopnea syndrome in long-term treatment. Methods A total of 25 patients were included in the study.The cephalometric study was used to investigate the dental,skeletal and airway changes.Results 25 patients were treated with an oral appliance for a mean duration of 5 years.Significant retroclination of the maxillary incisors(3.34±3.36°,P＜0.001)and proclination of the mandibular incisors(1.78±3.06°,P=0.008)were accompanied by reductions in overbite(1.46±1.12 mm,P＜0.001)and oveoet(1.12±0.99 mm,P＜0.001).The MP-FH,MPSN angles increased 1.3°,the face height and the distance between the hyoid and FH plane increased.Conclusions The orthodontic side-effects on the dental,skeletal and airway are sinail during the treatment of patients with OSAHS.     

Peer assessment rating index analysis of different extraction modality in skeletal Class Ⅲ malocclusions

Objective To assess the effect of different extraction modalities on treatment outcomes in skeletal Class Ⅲ malocclusions. Methods One hundred and nine skeletal Class Ⅲ patients (50 males and 59 females) with a mean age of 16.11±4.47 years were collected. The subjects were divided into four groups according to the extraction modality. They were T0 (non-extraction group), T1 (premolar extraction group), T2 (molar extraction group) and T3 (lower incisor extraction group). The PAR (peer assessment rating) index of each of the pre- and post-treatment cast was assessed. The differences of pre- and post-treatment weighed PAR score, reduction in weighed PAR score, percentage reduction in weighed PAR score and the degree of improvement between the four groups were compared. Results (1) Significant differences (P＜0.001＝ of the reduction in weighed PAR score and percentage reduction in weighed PAR score existed between different extraction modality groups. And the order of reduction from high to low was premolar extraction group, molar extraction group, non-extraction group and lower incisor extraction group.(2) There were no "Worse-no different" cases among the four groups. 97 cases were greatly improved and accounted for 89%. There were 12 cases (11%) in improved category. (3) Greatest improvement was found in premolar extraction group and the least improvement was found in lower incisor extraction group. Conclusions Treatment outcomes of the four extraction modalities in skeletal Class Ⅲ were all satisfied. Cautions should be paid in lower incisor extraction.     

外力方向对防护牙托性能影响的有限元分析

目的: 运用有限元分析评估外力方向对牙托缓冲能力的影响。方法: 采集仿真模型锥形束CT（CBCT）影像资料,利用MIMICS软件建立分析模型。运用ABAQUS软件模拟研究在牙托厚度不同的情况下（分别为0、1.5、3、4.5和6 mm）,经不同方向外力（撞击方向与牙长轴交角分别为30°、60°、90°和120°）撞击后,牙体表面的应力变化情况,进而评价牙托的缓冲能力。结果: 在研究实验条件下,当牙托厚度较薄时（1.5 mm和3 mm）,与其他方向相比,牙托缓冲效率在60°交角时最低,在120°交角时最高。而在牙托厚度增加后（4.5 mm和6 mm）,牙托缓冲效率在90°交角时最低,在30°交角时最高。外力方向不同时,牙托的应力缓冲效率随着牙托厚度的增加而提高。结论: 外力方向对防护牙托的缓冲能力有一定影响,但其易受牙托厚度的影响。     

上颌种植钉配合摇椅曲内收前牙的三维有限元应力分析

目的:通过改变摇椅曲度和游离牵引钩高度来分析牙齿的受力情况.方法:采用螺旋CT扫描,Mimics建模软件和Ansys分析软件,建立上牙列及其支持组织、以及不同曲度摇椅曲(5°、10°、15°、20°、25°)和不同高度的牵引钩(2.1mm、4.0 mm、5.5 mm)模型,施加1.5N向后的内收力.结果:牙齿受到的应力值大于牙周膜,牙齿应力集中区主要在托槽和颊面管区域,牙周膜主要在牙颈部.尖牙受到的应力值最大,其次是侧切牙.结论:牙齿和牙周膜所受到的最大应力都是随着摇椅曲和游离牵引钩高度的增加而增大.     

安氏I类拔牙病例关闭间隙时切牙移动方式分析

目的:探讨安氏I类错牙合拔牙病例关闭间隙时切牙的移动方式。方法:安氏I类错牙合牙列拥挤病例20例,均拔除4个第一前磨牙,采用方丝弓细丝弓技术矫治,牙性支抗(弱支抗)。矫治前后摄X线头颅定位侧位片,对切牙位置及硬、软组织进行测量分析。结果:上颌切牙牙冠平均后移2.55mm;牙根平均后移0.20mm,下颌切牙牙冠平均后移1.78mm、牙根平均后移0.28mm。结论:牙性支抗控制下,安氏I类错牙合拔牙病例关闭间隙时切牙移动是有控制的倾斜移动。     

New attachment following surgical treatment of human periodontal disease

Abstract The present experiment was undertaken to test the hypothesis that new connective tissue attachment may form on a previously periodontitis involved root surface provided cells originating from the periodontal ligament are enabled to repopulate the root surface during healing. A mandibular incisor with advanced periodontal disease of long standing (the distance between the cemento-enamel junction and the alveolar bone crest was 9 mm) was subjected to periodontal surgery using a technique which during healing prevented the dentogingival epithelium and the gingival connective tissue from reaching contact with the curetted root surface. Preference was hereby given to the periodontal ligament cells to repopulate the previously diseased root surface. After 3 months of healing a block biopsy containing the incisor and surrounding tissue was sampled. The histological analysis revealed that new cementum with inserting principal fibers had formed on the previously diseased root surface. This new attachment extended in coronal direction to a level 5 mm coronal to the alveolar bone crest. This finding suggests that new attachment can be achieved by cells originating from the periodontal ligament and demonstrates that the concept that the periodontitis affected root surface is a major preventive factor for new attachment is invalid.     

Intrusion injuries of primary incisors. Part II: Sequelae affecting the intruded primary incisors.

Luxation injuries to incisors, including intrusive displacement, occur with a high frequency in the primary dentition. Intrusion injuries are associated with damage to the pulpal and periodontal structures and possible fracture of the alveolar bone. The pulpal tissue of the intruded tooth sustains a severe shock during displacement, which may be reflected later by sequelae ranging from mild discoloration to pulpal necrosis and infection. Disintegration of pulpal tissue may result in periapical tissue inflammation, which in turn may induce developmental disturbances in the germ of the permanent successor tooth. Additionally, severe injury to the periodontal ligament during intrusion may lead to ankylosis of the primary incisor and consequently to delayed or ectopic eruption of its permanent successor. This article will review the possible sequelae affecting primary incisors following their intrusion.     

骨性安氏II类1分类成年患者拔牙矫治前后牙周表型的评估分析

目的　分析不同牙周表型的骨性安氏II类1分类成年患者拔牙矫治后上切牙区唇侧骨开裂、骨开窗及牙根吸收情况。方法　研究纳入24例骨性安氏II类1分类成年患者，通过术前CBCT和数字化印模数据的重叠，对前牙牙龈厚度进行无创的定量测量。根据术前上中切牙牙龈厚度将研究对象分为薄龈生物型组（牙龈厚度<1.5mm）和厚龈生物型组（牙龈厚度≥1.5mm）。使用CBCT测量正畸治疗前后上切牙唇侧牙槽骨骨开裂、骨开窗及牙根吸收的程度。结果　骨性安氏II类1分类成年患者术前骨开裂和骨开窗的发生率为31.2%和18.8%，经拔牙正畸治疗后增加至75%和20.8%。薄龈生物型组术后上前牙唇侧牙槽嵴顶至釉牙骨质界距离为3.19 ± 0.43mm，显著高于厚龈生物型组（2.16 ± 0.11mm），但该距离与牙龈厚度无显著相关性（r= -0.1108，P= 0.6146）。牙根吸收程度和牙龈厚度呈正相关（r=0.4223，P=0.0447），且厚龈生物型组牙根吸收量为2.24 ± 1.24mm，显著高于薄龈生物型组（1.08 ± 0.73mm）。结论　骨性安氏II类1分类成年患者经拔牙正畸治疗后上切牙区唇侧牙槽骨骨开窗、骨开裂及牙根吸收均加重，其中薄龈生物型组垂直牙槽骨吸收风险较大，厚龈生物型组骨开窗及牙根吸收风险较大。     

Non-linear viscoelastic finite element analysis of the effect of the length of glass fiber posts on the biomechanical behaviour of directly restored incisors and surrounding alveolar bone

The study aimed at estimating the effect of insertion length of posts with composite restorations on stress and strain distributions in central incisors and surrounding bone. The typical, average geometries were generated in a FEA environment. Dentin was considered as an elastic orthotropic material, and periodontal ligament was coupled with nonlinear viscoelastic mechanical properties. The model was then validated with experimental data on displacement of incisors from published literature. Three post lengths were investigated in this study: root insertion of 5, 7, and 9 mm. For control, a sound incisor model was generated. Then, a tearing load of 50 N was applied to both sound tooth and simulation models. Post restorations did not seem to affect the strain distribution in bone when compared to the control. All simulated post restorations affected incisor biomechanics and reduced the root's deforming capability, while the composite crowns underwent a higher degree of deformation than the sound crown. No differences could be noticed in incisor stress and strain. As for the influence of post length, it was not shown to affect the biomechanics of restored teeth.     

Secondary trauma from occlusion: three-dimensional analysis using the finite element method.

Clinical effects of forces applied by dental occlusion on the periodontium have been evaluated for decades. Historically, trauma from occlusion has been considered as a major etiologic factor of inflammatory periodontal diseases, while some researchers have interpreted it to be of less importance or without any detectable importance in periodontics. In this study, five three-dimensional models of a maxillary central incisor were created using ANSYS 5.40. The only difference in each model was the height of the alveolar bone that showed from normal height (13 mm of alveolar bone height) to 8 mm of alveolar bone loss (5 mm of alveolar bone height). Five-point forces of 0.3 N summing up to 1.5 N were applied in a parallel line, 1 mm apical to the incisal edge on the palatal side in a palatolabial direction. The maximum (S1) and minimum (S3) principal stresses in the nodes of the labial side of the periodontal ligament (apical to the alveolar crest) were assessed. Analysis was done using the finite element method. An increase of S1 (up to 16 times in the cervical and 11.25 times in the apical area) and S3 (up to 17.13 times in the cervical and 9.9 times in the apical area) in comparison to the normal model was shown. The highest stress levels were traced in the subcervical area, except for the last model (8 mm of the alveolar bone loss). According to the results of this study, 2.5 mm of alveolar bone loss can be considered as a limit beyond which stress alterations were accelerated. Based on the FEM analysis, alveolar bone loss increases stress (S1 and S3) produced in the PDL, in spite of applying the same force vector.     

微手术正畸治疗骨性Ⅲ类错(牙合)伴下前牙区牙槽骨发育不良的效果评价

目的:探讨微手术正畸对骨性Ⅲ类错(牙合)伴下前牙牙槽骨发育不良的术前去代偿正畸临床策略,检查矫正后下前牙槽骨和牙周组织健康状况的改善程度,提出临床对策,治疗牙槽骨发育不良.方法:从2009-2012间于上海交通大学附属第九人民医院口腔颅颌面科求治的成人连续病例中,选取下前牙区牙槽骨发育不良且有正颌手术适应证的骨性Ⅲ类错(牙合)畸形为研究对象,按照是否接受微手术正畸治疗进一步分为2组 10例接受者纳入微手术组(G1组),12例不接受者纳入对照组(G2组).通过锥形束CT(cone beam computed tomography,CBCT)测量2组术前正畸前、后左侧中、侧切牙牙根长度,唇舌侧牙槽骨高度及厚度.采用SAS 8.02软件包对数据进行统计学处理 结果:G1组术前正畸结束,唇侧牙槽骨高度降低2.60 mm,舌侧降低2.22 mm;根尖唇侧厚度增加3.05 mm,舌侧减小0.88 mm,根尖水平总牙槽骨厚度增加2.13 mm,与G2组有显著差异.较之G2组,更好地控制了术前正畸去代偿过程中下前牙牙根的吸收及牙槽骨高度、厚度的丧失.结论:微手术正畸用于下前牙区牙槽骨发育不良的骨性Ⅲ类错(牙合)术前去代偿,能够有效降低治疗过程中牙周破坏(牙根吸收、牙槽骨吸收、穿孔 等)的风险,克服下颌牙槽骨对去代偿竖直牙的限制,提高此类患者术前正畸的安全性.     

上中切牙牙周支持组织高度降低的三维有限元分析

目的:研究牙周支持高度降低状态下施加舌向集中力时,牙周组织的应力变化、分布规律和牙的初始位移。方法:采用螺旋CT扫描、数字影像传输与转录方法,获得中切牙三维形态的原始数据。通过减少牙周支持组织的高度,产生代表6种不同牙周支持高度的三维有限元模型。结果:随着牙槽骨高度的降低,上中切牙牙周膜最大等效应力和主应力逐渐增大。最大拉应力位于舌侧根尖部,最大压应力位于舌侧牙槽嵴顶。牙周膜的应力随牙槽骨高度的降低呈非等比增加。结论:随着牙周支持组织高度的逐渐降低,牙的旋转中心向根尖移动,牙周支持组织对牙的支持能力明显减弱。在正畸治疗中,所应用的力必须成比例减小,以维持正常生理的可耐受的运动而不造成支持组织的进一步损伤。