Alveolar bone response to maxillary incisor retraction using stable skeletal structures as a reference

ObjectivesTo evaluate alveolar bone change in relation to root position change after maxillary incisor retraction via cone-beam computed tomography (CBCT) using stable skeletal structures as a reference.Materials and MethodsA total of 17 subjects (age 24.7 ± 4.4 years) who required retraction of the maxillary incisors were included. Labial and palatal alveolar bone changes and root change were assessed from preretraction and 3 months postretraction CBCT images. The reference planes were based on stable skeletal structures. The Kruskal-Wallis test and Wilcoxon signed-rank test were used to compare changes within and between groups, as appropriate. Spearman rank correlations were used to identify the parameters that correlated with alveolar bone change. The significance level was set at .05.ResultsThe labial alveolar bone change after maxillary incisor retraction was statistically significant (P < .05), and the bone remodeling/tooth movement (B/T) ratio was 1:1. However, the palatal bone remained unchanged (P > .05). The change in inclination was significantly related to labial alveolar bone change.ConclusionsUsing stable skeletal structures as a reference, the change in labial alveolar bone followed tooth movement in an almost 1:1 B/T ratio. Palatal alveolar bone did not remodel following maxillary incisor retraction. The change in inclination was associated with alveolar bone change.     

Alveolar bone changes after asymmetric rapid maxillary expansion

Objective:To quantitatively evaluate the effects of asymmetric rapid maxillary expansion (ARME) on cortical bone thickness and buccal alveolar bone height (BABH), and to determine the formation of dehiscence and fenestration in the alveolar bone surrounding the posterior teeth, using cone-beam computed tomography (CBCT).Materials and Methods:The CBCT records of 23 patients with true unilateral posterior skeletal crossbite (10 boys, 14.06 ± 1.08 years old, and 13 girls, 13.64 ± 1.32 years old) who had undergone ARME were selected from our clinic archives. The bonded acrylic ARME appliance, including an occlusal stopper, was used on all patients. CBCT records had been taken before ARME (T1) and after the 3-month retention period (T2). Axial slices of the CBCT images at 3 vertical levels were used to evaluate the buccal and palatal aspects of the canines, first and second premolars, and first molars. Paired samples and independent sample t-tests were used for statistical comparison.Results:The results suggest that buccal cortical bone thickness of the affected side was significantly more affected by the expansion than was the unaffected side (P < .05). ARME significantly reduced the BABH of the canines (P < .01) and the first and second premolars (P < .05) on the affected side. ARME also increased the incidence of dehiscence and fenestration on the affected side.Conclusions:ARME may quantitatively decrease buccal cortical bone thickness and height on the affected side.     

Changes of anterior maxillary alveolar bone thickness following incisor proclination and extrusion

Objective:To investigate changes in maxillary alveolar bone thickness after maxillary incisor proclination and extrusion during anterior crossbite correction in a group of growing patients with Class III malocclusion.Materials and Methods:Maxillary incisors of 15 growing patients with anterior crossbite were proclined and extruded with 0.016″ beta-titanium advancing loops and Class III elastics. Lateral cephalograms were recorded before advancement (T₀) and 4 months after a normal overjet and overbite were achieved (T₁). Changes in alveolar bone thickness surrounding the maxillary incisors at the crestal (S1), midroot (S2), and apical (S3) levels were measured using cone-beam computed tomography (CBCT). Paired t-tests were used to determine the significance of the changes. A Spearman rank correlation analysis was performed to explore the relationship between thickness changes and the rate and amount of incisor movements.Results:Although statistically significant decreases were observed in palatal and total bone thickness at the S2 and S3 level (P < .05), the amounts of these changes were clinically insignificant, ranging from 0.34 to 0.59 mm. Changes in labial bone thickness at all levels were not significant. Changes in palatal bone thickness at S3 were negatively correlated with changes in incisor inclination. (r  =  −0.71; P < .05).Conclusion:In a group of growing patients with Class III malocclusion undergoing anterior crossbite correction, controlled tipping mechanics accompanied by extrusive force may produce successful tooth movement with minimal iatrogenic detriment to the alveolar bone.     

Alveolar bone thickness and height changes following incisor retraction treatment with microimplants:: A cone beam computed tomography study

ObjectivesTo evaluate alveolar bone remodeling following incisor retraction treatment with microimplants and to examine the relationship between crown/root distal movement and thickness/height changes of the alveolus.Materials and MethodsA total of 24 patients (mean age, 19.29 ± 4.64 years) with bialveolar protrusion treated by incisor retraction with microimplants were included. The distances of the crown and root tip movements as well as the thickness (alveolar bone thickness [ABT]; labial, lingual, and total) and vertical level (vertical bone level [VBL]; labial and lingual) of the alveolar bone were assessed using cone-beam computed tomography images obtained before treatment (T1) and after treatment (T2). All T1 and T2 variables were compared, and further comparisons of alveolar bone changes were conducted between the two groups based on the distance of the crown (low-crown-movement and high-crown-movement groups) and root movements (low-root-movement and high-root-movement groups). To determine the correlation of the crown or root movement with the variables of alveolar bone changes, Pearson correlation coefficients were calculated.ResultsSignificant differences were found in all VBL and ABT variables after treatment in both jaws but not in total ABT. Based on the crown and root movements, alveolar bone change significantly differed between the root-movement groups, whereas there was no significant difference between the crown-movement groups. In addition, root movement showed significant correlations with the variables.ConclusionsRemarkable changes in the height and thickness of alveolar bone were found after microimplant-aided incisor retraction treatment in all groups except for total ABT. Root movement was significantly correlated with the alveolar bone changes.     

Alveolar bone changes after molar protraction in young adults with missing mandibular second premolars or first molars

ObjectivesTo assess the changes in alveolar bone of the mandibular second molars following molar protraction and investigate the factors associated with the alveolar bone changes.Materials and MethodsCone-beam computed tomography of 29 patients (mean age 22.0 ± 4.2 years) who had missing mandibular premolars or first molars and underwent molar protraction were reviewed. Alveolar bone level was measured as the distance from the cementoenamel junction at six points, buccal, lingual, mesiobuccal (MB), mesiolingual (ML), distobuccal (DB), and distolingual (DL), of the second molars at pretreatment (T0) and after molar protraction (T1). Factors associated with alveolar bone changes at the distal and mesial of the second molars were assessed.ResultsMean alveolar bone changes ranged from −1.2 mm (bone apposition) to 0.8 mm (bone resorption). The presence of a third molar impaction at T0 (P < .001), third molar angulation at T0 (P < .001), and Nolla''s stage of third molar at T0 (P = .005) were significantly associated with alveolar bone level changes distal to the second molars. Treatment duration (P = .028) was significantly associated with alveolar bone level changes mesial to the second molar.ConclusionsPatients with impacted third molars, third molars at an earlier stage of development, and mesially angulated third molars at pretreatment may have less alveolar bone resorption distal to the second molars following protraction. Patients with increased treatment time may have reduced alveolar bone resorption mesial to the second molars.     

成人前牙内收前后切牙牙槽骨高度变化的研究

目的：研究成人双颌前突患者前牙内收前后切牙区唇侧、舌侧牙槽骨高度的变化。方法：选取双颌前突成人患者15例,治疗需拔除4颗第一前磨牙行前牙内收,内收前后分别拍摄 CBCT 片,对其上、下颌8颗切牙唇舌侧牙槽骨高度进行测量和对比分析。结果：上、下颌切牙内收后唇侧牙槽骨高度均有不同程度升高,以下颌更为显著（P ＜0．05）,舌侧牙槽骨高度降低（P ＜0．05）。结论：成人双颌前突患者切牙行大范围舌向移动时舌侧牙槽骨高度降低,临床治疗中应予以关注。     

慢性牙周炎基础治疗前后牙槽骨锥形束CT评价

目的 应用锥形束CT(CBCT)评价慢性牙周炎牙周基础治疗前后牙槽骨的改变.方法 选择重度慢性牙周炎患者30例,对牙周基础治疗前、后上颌前磨牙牙槽骨进行临床疗效观察及拍摄CBCT片,利用CBCT随机软件测量牙槽骨高度和相对骨密度变化.结果 重度慢性牙周炎基础治疗后,患者牙周袋探诊深度、附着丧失明显好转,较治疗前差异均有统计学意义(P＜0.05).牙槽骨密度升高差异有统计学意义(P＜0.05),牙槽骨吸收程度变化差异无统计学意义(P＞0.05).不同阅片者之间对牙槽骨密度及牙槽骨吸收状况的测量,一致性检测结果显示组内相关系数大于0.9,差异无统计学意义.结论 CBCT可用于重度慢性牙周炎牙周基础治疗前、后牙槽骨状态的评价,定点方法具有可行性和可重复性.     

上颌前牙牙龈厚度与牙槽骨厚度相关性的数字化测量分析

目的用数字化方法探讨分析上颌前牙唇侧牙龈厚度和牙槽骨厚度的相关性,为上颌前牙区美学修复及种植治疗提供参考。方法根据纳入及排除标准,选取2020年5至10月于第四军医大学口腔医学院口腔修复科行后牙种植修复的患者,共纳入57例,其中男性23例,女性34例,年龄(25.8±4.5)岁。采用口内扫描仪进行口内扫描,并拍摄锥形束CT,利用种植导板软件进行口内扫描数据和锥形束CT数据的拟合配准,测量并记录上颌中切牙、侧切牙和尖牙唇侧龈缘下2 mm处牙龈厚度以及牙槽嵴顶下2、4 mm处牙龈厚度及牙槽骨厚度。结果57例患者上颌中切牙、侧切牙、尖牙龈缘下2 mm处牙龈厚度分别为(1.42±0.21)、(1.19±0.17)和(1.23±0.20)mm(F=12.47,P<0.001);男性上颌前牙龈缘下2 mm和牙槽嵴顶下4 mm处牙龈厚度[分别为(1.31±0.21)和(0.67±0.22)mm]分别显著大于女性相应测量项目[分别为(1.26±0.22)和(0.58±0.19)mm](t=2.01和3.97,P<0.05);上颌前牙唇侧牙槽嵴顶下2、4 mm处牙龈厚度与牙槽骨厚度均呈正相关(r=0.387和0.344,P均<0.05)。结论上颌中切牙牙龈厚度大于侧切牙和尖牙;男性牙龈厚度大于女性;上颌前牙唇侧牙槽嵴顶下2、4 mm处牙龈厚度与牙槽骨厚度呈正相关,即牙龈越厚,牙槽骨也越厚。     

Tooth and bone changes after initial anterior dental alignment using preformed vs customized nickel titanium archwires in adults: A randomized clinical trial

Objectives:To compare tooth movement achieved, time required for alignment, root resorption, and alveolar bone thickness changes during initial dental alignment between groups treated with 0.012-inch preformed heat-activated or customized nickel titanium (NiTi) archwires.Materials and Methods:Thirty-two subjects (mean age 19.8 ± 1.7 years) with severe crowding of maxillary anterior teeth had premolar extractions and were randomly allocated into control and experimental groups receiving preformed heat-activated and customized NiTi archwires, respectively. Limited field of view cone-beam computed tomographies were taken initially (T₀) and three months after final alignment (T_F) to evaluate bone changes. Digital model analysis assessed tooth movement at monthly intervals. Time to achieve alignment was assessed in months. Wilcoxon signed-rank tests and Mann–Whitney U-tests were used to compare changes within and between groups, as appropriate.Results:Central incisor tooth movement was significantly different (all P ≤ .003) between groups at all time points. T_F-T₀ showed labial movement (0.75 ± 1.42 mm) in the control group and palatal movement (−0.96 ± 0.41 mm) in the experimental group. The experimental compared to control group showed significantly more canine distal movement (0.60 ± 0.28 mm; P ≤ .049), less labial bone thickness changes (P ≤ .004), less root resorption of the central and lateral incisors (P ≤ .007), and a longer time to achieve alignment (P = .01).Conclusions:The experimental group exhibited palatal movement of the central incisors, more canine distal movement with less bone thickness changes, and less root resorption but took more time to achieve alignment than the control group.     

中重度慢性牙周炎上颌中切牙区解剖形态的锥形束CT测量分析

目的应用锥形束CT（CBCT）测量分析中重度慢性牙周上颌中切牙区牙槽骨的骨量和牙齿偏移度,为上颌中切牙区的种植治疗和方案制定提供解剖学依据。 方法选取2015年1月至2017年12月深圳爱康健口腔医院内150例中重度牙周炎患者的CBCT影像资料,测量共290颗上颌中切牙唇/腭侧骨壁厚度、牙槽骨骨宽/高度、骨内根长、牙体长轴和牙槽骨走行方向的夹角共7个项目,采用SPSS 19.0统计软件包对测量结果进行相关统计分析。 结果中重度慢性牙周炎上颌中切牙牙槽嵴顶处和根尖处的唇腭向骨厚度分别为（7.68 ± 0.78）mm和（8.52 ± 1.55）mm,牙槽骨高度平均为（18.35 ± 3.45）mm,骨内根长1/2处的唇侧和腭侧的骨壁厚度分别为（0.62 ± 0.45）mm和（3.18 ± 1.00）mm,牙体长轴与牙槽骨走行方向夹角的平均值为18.80° ± 5.46°。不同性别间对比测量结果,在牙槽嵴顶骨宽度和根尖区骨宽度处差异均有统计学意义（P<0.05）,男性优于女性。 结论中重度慢性牙周炎上颌中切牙的唇侧骨壁菲薄甚至缺如,骨量条件不理想,牙体长轴与牙槽骨偏移度明显,在制定种植方案时有必要充分利用CBCT了解骨量情况并评估解剖形态,为达到上颌中切牙种植效果长期美观、稳定的需求应有更多的考量。     

上切牙区腭平面角与牙槽嵴顶唇腭径的相关性分析

目的：利用CBCT分别测量不同错颌类型的患者上切牙区腭平面角,切牙牙槽嵴顶颌骨唇腭径,为前牙区种植手术提供数据支持。方法：从CBCT数据库中收集符合条件的180例患者资料,其中安氏Ⅰ类者60例,Ⅱ类60例,Ⅲ类60例。利用NNT Viewer软件进行三维重建,并利用软件自带的角度测量工具进行测量。结果：单因素方差分析表明,在安氏Ⅰ、Ⅱ、Ⅲ类患者之间,切牙区牙槽嵴顶唇腭径(χ2=4.758, P=0.014)及腭平面角(χ2=47.546, P=0.000)均存在显著性差异。安氏Ⅲ类唇腭径数值低于安氏Ⅰ、Ⅱ类。腭平面角与对应区颌骨唇腭径呈直线相关关系(OR=0.733, P＜0.01;回归方程：唇腭径=9.609-0.026*腭平面角)。结论： CBCT是较理想的研究前牙种植手术区的工具,在种植手术中不同牙颌类型患者应注意种植方向的选择。     

Evaluation of maxillary buccal alveolar bone before and after orthodontic alignment without extractions: A cone beam computed tomographic study

Objectives:To assess the changes in the maxillary buccal alveolar bone during alignment without extractions. Secondarily, to evaluate the changes in arch dimensions and buccolingual inclinations of teeth and to identify risk factors for bone loss.Materials and Methods:Twenty-two adolescents with crowded permanent dentitions were treated without extractions with Damon 3MX brackets. Cone beam computed tomographic scans were taken before treatment (T0) and after alignment (T1). Bone thickness (BT) and height from the cementoenamel junction to the alveolar crest (BH) were evaluated at the maxillary central incisors, second premolars, and buccal roots of first molars. Changes in all variables from T0 to T1 were assessed. Correlations between bone changes and initial bone thickness, initial arch widths, initial crowding, amount of expansion, amount of tipping, and amount of molar rotation were calculated.Results:BT decreased and BH increased significantly for the incisors and mesiobuccal root of the first molars. Arch dimensions generally increased together with tipping. Bone loss was correlated with crowding and amount of expansion in the premolar region. Initially thinner BT was correlated with greater apical migration of bone for the incisors.Conclusions:Nonextraction alignment with self-ligating brackets led to arch expansion associated with tipping of teeth. Expansion related to alignment resulted in horizontal and vertical bone loss at the incisors and mesiobuccal root of the first molars. Thinner BTs and more severe crowding before treatment increased the risk for buccal bone loss.     

Effect of orthodontic treatment on periodontal health of periodontally compromised patients:: A randomized controlled clinical trial

ObjectivesTo evaluate the effect of fixed orthodontic treatment on periodontal parameters in periodontally compromised adult orthodontic patients.Materials and MethodsThis was a prospective, randomized, controlled clinical trial. Thirty-six periodontally compromised adult patients (mean age: 29.67 ± 4.8 years) were randomly allocated to either test (perio-ortho) or control group (perio). After periodontal stabilization in both groups, orthodontic treatment was started in the test group, whereas the control group remained on periodontal maintenance only. Evaluation and comparison of clinical parameters (plaque index [PI]; gingival index [GI]; bleeding on probing [BOP]; probing depth [PD]; clinical attachment level [CAL]) of both groups was assessed at three time intervals: T0 (base line), T1 (at start of orthodontic treatment), and T2 (1 year after start of orthodontic treatment). Radiological parameters (alveolar bone levels [ABL]) were recorded using CBCT at T1 and T2.ResultsIntragroup analysis showed statistically significant improvement in all clinical and radiological periodontal parameters in both groups (P ≤ .05). Intergroup comparison revealed improvement in the periodontal parameters was not statistically significant between the groups (P ≥ .05). Subgroup analysis showed reduction in the number of moderate and severe periodontitis sites in both groups with significant more gains in ABL in the test group compared to the control group.ConclusionsOrthodontic treatment after periodontal stabilization does not have any detrimental effect on periodontal health in adult periodontally compromised orthodontic patients and may add to the benefits achieved by periodontal treatment alone.     

唇腭裂患者牙槽突裂植骨区牙移入的临床观察

目的:探讨牙槽突裂植骨区牙移入的可行性及牙移入的方式,评价移入牙的牙槽骨支持率和移植骨高度变化。方法:选取唇腭裂伴牙槽突裂患者10例,行牙槽突裂自体髂骨植骨术后,分别拍摄植骨后3个月(T1)及牙移入植骨区后(T2)的根尖片,观察牙移入植骨区的情况,测量T1和T2阶段移入牙的牙槽骨支持率,采用SPSS17.0软件包对测量数据进行配对t检验,并参照Bergland四分法评价移植骨的高度变化。结果:①牙整体移入植骨区,牙槽骨支持率为(89.85±2.51)%(T1)和(90.22±2.44)%(T2),牙移入植骨区后的牙槽骨支持率与植骨后3个月的牙槽骨支持率无显著差异(P>0.05)。②移植牙槽骨的高度在牙移入前后无显著变化。结论:唇腭裂患者植骨后,可将裂隙邻近的牙移入植骨区,获得良好的牙槽骨支持。牙的移入有助于维持移植骨高度,提高植骨的成功率。     

锥形束CT分析中国人群上颌后牙区牙槽骨及牙根与上颌窦位置关系的研究

［摘要］ 目的 利用锥形束CT三维成像分析上颌后牙区牙槽骨高度以及牙根与上颌窦底位置关系,为临床诊断和治疗提供可靠的参考依据。方法 选取500例患者的锥形束CT影像资料,测量上颌前磨牙和磨牙的牙槽骨高度、牙根至上颌窦底距离、磨牙牙根与上颌窦的位置关系（垂直和水平关系）,按照牙位和年龄将这些数据分组,分析在不同牙位和年龄段的差异。结果 上颌前磨牙的牙槽骨高度分别为（11.31±7.39）和（9.52±7.98）mm,显著高于上颌磨牙区,随着年龄的增长牙槽骨高度降低。上颌第二磨牙近颊根至上颌窦底距离最短,其平均值为（1.73±3.63）mm;第一前磨牙牙根至上颌窦底的平均值为（9.53±5.79）mm,至上颌窦底距离最长,随着年龄的增长,牙根与上颌窦底间距离变短。在牙根与上颌窦的垂直关系中,三个牙根均不与上颌窦下壁接触的情况显著高于其他分类;水平关系中,在根尖至根分叉水平观察到上颌窦最为常见;随诊年龄的增长牙根与上颌窦的关系更加密切。结论 不同年龄和牙位牙根与上颌窦的关系差异较大,利用锥形束CT可精确分析上颌后牙区解剖结构,制定个性化治疗方案,降低医源性问题的发生。