上颌埋伏阻生中切牙的临床研究

目的统计温州医学院附属口腔医院正畸科门诊病例中上颌埋伏阻生中切牙的患病率、唇腭侧的比例及治疗情况。方法选取2005年1月至2008年1月期间,在温州医学院附属口腔医院正畸科就诊的错殆患者中,所有在放射科拍摄过螺旋CT的上颌中切牙埋伏阻生的患者。统计其发病、治疗情况。结果2005年1月至2008年1月期间,在温州医学院附属口腔医院正畸科共有8763名患者,上颌中切牙埋伏阻生者共103名。男性50名,女性53名。唇侧阻生71名（其中3名为双侧阻生）,腭侧阻生20名,垂直阻生12名。其中76颗埋伏牙采用外科手术结合正畸牵引治疗,27颗采取外科拔除,3颗采用减阻助萌术。结论在温州医学院附属口腔医院正畸门诊患者中上颌中切牙埋伏阻生约占1．18％,男女比例基本一致,唇侧阻生最常见,上颌埋伏阻生中切牙的治疗以外科手术结合正畸治疗为主。     

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目的比较手术—正畸联合治疗唇侧和腭侧上颌埋伏阻生尖牙的临床疗效。方法对广东省深圳市宝安区人民医院口腔正畸门诊2004—2009年收治的60例埋伏阻生尖牙患者(均为单颗埋伏阻生尖牙患者,共60颗牙),根据全口曲面断层片和X线定位片分为唇侧组和腭侧组各30颗牙,通过手术开窗去除阻力骨、暴露部分牙冠、黏结正畸附件,在固定矫正技术的牵引下将埋伏阻生的尖牙纳入正常牙弓内。对比两组治疗的成功率和治疗所需的时间。结果治疗成功率唇侧组为80.0%,腭侧组为96.7%,两组比较差异有统计学意义(P<0.01)。术后正畸牵引的时间腭侧组为(9.2±3.2)个月,而唇侧组为(15.1±4.1)个月,明显长于腭侧组,两组比较差异亦有统计学意义(P<0.01)。结论经手术开窗正畸牵引,上颌埋伏阻生尖牙的成功率腭侧组大于唇侧组,牵引到位的时间腭侧组也较唇侧组短。     

上颌尖牙埋伏阻生患者牙弓形态及拥挤度的研究

目的 上颌尖牙唇侧和腭侧埋伏阻生患者的牙弓宽度、长度、拥挤度与正常(牙合)个体之间是否存在差异.方法 经CT检查上颌尖牙埋伏阻生患者104名,年龄11-28岁.尖牙唇侧阻生患者57名,腭侧阻生患者47名,对其牙弓宽度、长度、拥挤度进行测量,并和正常(牙合)个体进行对照研究.结果 上颌尖牙唇侧埋伏阻生患者82.5%伴有牙弓中重度拥挤,上颌尖牙腭侧埋伏阻生患者57.4%的牙弓基本无拥挤.上颌尖牙埋伏阻生患者中,无论是唇侧埋伏还是腭侧埋伏,其牙弓长度与正常(牙合)无差异.双尖牙区牙弓宽度减小.结论 国人上颌尖牙埋伏阻生患者的牙弓宽度、长度、拥挤度的特点与白种人不同.     

上颌埋伏阻生尖牙在锥形束CT和曲面体层片中的位置分布及特征研究

目的　通过分析上颌埋伏阻生尖牙在曲面体层片上牙冠和牙根所在区域、牙轴倾斜度及牙齿长度,对照其在锥形束CT（cone-beam computed tomography,CBCT）上的位置,找出上颌埋伏阻生尖牙的曲面体层片预测因素。方法　选取2006—2018年于中国医科大学附属口腔医院正畸科就诊的单侧上颌埋伏阻生尖牙患者135例,共计上颌埋伏阻生尖牙135颗为研究组,同一患者对侧非埋伏阻生尖牙135颗为对照组。（1）采用NNT Viewer软件、Planmeca Dimaxis Pro软件分别对患者的CBCT图像和曲面体层片进行测量,将曲面体层片中上颌埋伏阻生尖牙近远中向位置分为5区（Ⅰ ~ Ⅴ区）,其唇腭侧位置由CBCT判定,分析两者相关性。（2）在曲面体层片中测量分析研究组与对照组牙冠及牙根的近远中向位置分布、牙轴倾斜度以及牙齿长度的差异。结果　（1）不同性别患者上颌埋伏阻生尖牙唇腭侧位置分布的差异有统计学意义（χ2 = 13.542,P = 0.001）。曲面体层片中上颌埋伏阻生尖牙牙根近远中向的区域定位与CBCT中相应阻生尖牙的唇腭侧位之间有显著相关性（r = 0. 225,P = 0.009）;但其牙冠间无相关性（r = 0.001,P = 0.991）。（2）两组尖牙牙冠及牙根近远中向位置分布差异有统计学意义（χ2值分别为219.263、68.447,均P < 0.001）。研究组较对照组尖牙牙齿长度短,牙轴倾斜度大（均P < 0.05）。结论　利用曲面体层片中上颌阻生尖牙牙根近远中向的区域定位可预测其唇腭侧位。在曲面体层片中牙根近远中向位置和牙齿长度的测量结果可用于预测上颌埋伏阻生尖牙的发生。     

上颌尖牙埋伏阻生患者上颌切牙牙齿宽度改变的研究

目的探讨中国人上颌切牙宽度与尖牙阻生是否存在内在的联系.方法选择103名上颌尖牙埋伏阻生患者,分为46名腭侧阻生组和57名唇侧阻生组.选择年龄、性别匹配,上颌尖牙正常萌出的患者60名,作为对照组.测量这些患者的上颌切牙近远中宽度,并进行统计学分析.结果尖牙阻生患者的左右侧中切牙及侧切牙的近远中宽度基本一致,无统计学差异.尖牙唇侧阻生患者的侧切牙宽度大于对照组,腭侧阻生患者的侧切牙宽度小于对照组,均有统计学差异.唇腭侧阻生患者的侧切牙宽度有显著性差异.结论尖牙埋伏阻生患者的上颌切牙宽度变化和尖牙阻生的位置有着高度的相关性.     

利用锥形束CT研究单侧上颌尖牙埋伏阻生患者牙弓形态特点

目的 利用锥形束CT(Cone beam computed tomography,CBCT)研究单侧上颌尖牙埋伏阻生患者牙弓形态特点,为研究其病因及预防继发病症提供参考.方法 39名单侧上颌尖牙埋伏阻生患者,其中腭侧埋伏19名,唇侧埋伏20名,另设正常对照20名.三组患者年龄无显著性差异.三组患者拍摄CBCT并对牙弓的影像进行测量,比较三组之间以及阻生侧与非阻生侧的牙弓形态特点.结果 尖牙阻生患者的双侧牙弓比较显示,阻生侧前段及整侧牙弓长度均比非阻生侧小(P＜0.001).腭侧组第一磨牙到腭中缝距离(24.06±1.68) mm小于唇侧组(24.86±1.31)mm和对照组(24.88±1.12) mm,腭侧组牙弓周长(72.29±3.50) mm小于唇侧组(75.96±5.26) mm,P＜0.05.结论 上颌尖牙埋伏阻生可能与牙弓长度(尤其是前段)较短有关,且腭侧阻生可能还与牙弓宽度较小有关.     

腭侧埋伏尖牙闭合牵引助萌的临床研究

目的：观察腭侧埋伏尖牙闭合牵引助萌的临床疗效。方法：对20例上颌腭侧尖牙埋伏阻生病例,采取局麻下开窗,暴露埋伏牙唇面,粘接正畸托槽,复位黏骨膜瓣后进行牵引,应用固定正畸技术进行矫治。结果：本组20例中18例达到满意效果,牙髓活力测试正常,牙龈外形正常,1例埋伏牙牙髓产生炎症后行根管治疗得以保存,1例治疗失败,牙根吸收1／2,后拔除。结论：腭侧开窗助萌术配合固定正畸技术可有效矫治上颌腭侧埋伏阻生尖牙。     

青少年尖牙高位埋伏阻生的多学科联合治疗1例

<正>除第三磨牙外，上颌尖牙最常见发生异位埋伏阻生，发病率约1%～2.5%,且女性发病率要高于男性约2～3倍。尖牙埋伏阻生的病因较多，如牙列拥挤、缺乏间隙、软硬组织疾病、萌出通道最长、侧切牙牙根异常或缺失、根骨黏连等^[1,2]。尖牙埋伏阻生治疗主要包括：自体牙移植、拔除阻生尖牙联合正畸关闭间隙、拔除阻生尖牙联合修复治疗、外科手术开窗联合正畸牵引和姑息治疗等^[3-5]。本文将报道1例尖牙高位埋伏阻生患者多学科联合治疗病例。     

改良横腭杆作支抗协助导萌腭侧埋伏阻生尖牙10例报告

目的：探讨使用改良的横腭杆正畸临床矫治腭侧埋伏阻生尖牙的疗效。方法：选择2010～2012年在周口市口腔医院正畸科就诊的腭侧埋伏阻生尖牙10例,均经螺旋CT检查确诊为腭侧埋伏,并有较大把握导萌者。所有患者都采用了改良横腭杆的矫治方法。结果：经过平均7.6个月的导萌治疗（最短4.6个月,最长8.4个月）10个病例共12颗埋伏阻生尖牙均导萌成功,埋伏阻生的尖牙均移至理想的位置,咬合关系良好,牙龈附着满意,未见有牙根吸收现象。结论：改良横腭杆协助正畸临床导萌腭侧埋伏阻生尖牙是一种行之有效的治疗方法。     

上颌唇侧水平埋伏阻生尖牙正畸导萌的力学原理分析

目的：分析上颌唇侧埋伏阻生尖牙正畸导萌的力学原理，探讨上颌唇侧埋伏阻生尖牙的矫治力方向设计以及改良Nance弓的作用。方法：采用自行设计的改良Nance弓辅以直丝矫治器，对5例上颌唇侧水平埋伏阻生尖牙进行正畸一外科联合治疗，比较分析了直接牵引和改良Nance弓辅助牵引二种方式的矫治力方向，埋伏牙的移动方式及其力学原理。结果：5例上颌唇侧水平埋伏阻生尖牙顺利萌出至正常位置，尖牙及邻近侧切牙牙髓、牙周健康。力学原理分析显示采用改良Nance弓矫治方法，埋伏牙的移动方式更合理，所需矫治力更轻，支抗负荷更小。结论：矫治上颌唇侧水平埋伏阻生尖牙时，要合理设计矫治力方向，改良Nance弓是一种符合生理力学需要的辅助装置。     

The sequential hypothesis of impaction of maxillary canine – A hypothesis based on clinical and radiographic findings

The aetiology of impacted maxillary canines remains obscure. Numerous researchers have focused on identifying specific and non-specific aetiological factors responsible for canine displacement. Currently, the two most popular hypotheses that have gained consensus worldwide are the guidance theory and the genetic theory. However, no single hypotheses, can completely explain the aetiology of impaction of maxillary canines. This retrospective study was used to develop and postulate the aetiology of both buccally and palatally impacted maxillary canines. The study was conducted on a sample of 533 patients for whom the pattern and distribution of the impacted maxillary canines, sex differences, the dental age of the patients, dental anomalies and various geometric measurements which were made on the panoramic radiographs were recorded. Based on these findings, the sequential hypothesis of impaction of the maxillary canine was postulated. The hypothesis states that both buccally and palatally impacted canines have similar aetiological factors leading to their impaction. It is suggested that genetic mechanisms strongly influence the potential of the maxillary canine to be impacted and the guidance from the lateral incisor and the stage of development plays a vital role in determining the ultimate position of the impacted canine.     

Dental age in patients with impacted maxillary canines related to the position of the impacted teeth

The aim of the study was to determine whether there are differences in dental age (DA) using the method of Demirjian, in patients with impacted buccal or palatal maxillary canines in relation to unaffected controls. DA was estimated using Demirjian's method on panoramic radiographs of two groups of Caucasian patients. The study group consisted of 116 patients aged from 12 to 16 years (80 females and 36 males) that was further divided into 54 patients with unilateral or bilateral palatally impacted maxillary canines and 62 patients with buccally positioned canines. The control group of 116 subjects without canine impaction was matched to the study group by age and gender. Calculated DAs and differences between dental and chronological age (CA) were compared between the groups. Statistical analysis was performed using Shapiro-Wilk, Mann-Whitney U, and Student's t-test. DA was significantly lower in patients with impacted maxillary canines than in healthy controls and also when palatal or buccal ectopia was considered. The rate of dental development in patients with palatally impacted canines did not differ from that of subjects with buccal canine displacement. The differences between DA and CA were higher in healthy controls (increase in DA) than in patients with impacted maxillary canines. DA estimation using Demirjian's method may be lower than expected in subjects with maxillary canine impaction.     

Dental age of children and adolescents with impacted maxillary canines

INTRODUCTION: It is generally perceived that patients with palatally impacted canines experience a delay in dental development, while patients with buccally impacted canines do not. Nevertheless, there is little scientific data on the subject, and no data at all on Chinese populations. The objectives of this study were, thus, to determine whether patients with impacted canines would demonstrate delayed dental development. DESIGN: Retrospective radiographic study. SETTING: Dental hospital. METHODS: Our study enrolled southern Chinese children and adolescents with unilaterally impacted maxillary canines. A total of 281?panoramic radiographs were available to assess dental age. Demirjian's method was utilized to determine the dental age. RESULTS: The discrepancy between dental and chronologic ages was then calculated, revealing a mean difference of 0.4?years (±?0.2?years), indicating advanced dental development. The cumulative difference between dental age and chronologic age showed that 42.2% of the patients with a buccally impacted canine and 30% with a palatally impacted canine experienced a delay in dental development, or coincided with their chronologic age. CONCLUSION: Less than half of the patients with both buccally and palatally impacted canines showed delayed dental development. Their dental maturity was on average slightly but clinically insignificantly advanced.     

Orthodontic treatment of palatally impacted maxillary canines

The aim of this study was to determine the feasibility of treating children with impacted maxillary canines by orthodontic treatment alone. The subjects were 28 children (mean age: 13.5 years, range 11.4-16.1 years) with between them 32 palatally impacted canines. The overlying primary canines were extracted between 0 and 42 months before the start of appliance treatment to open space in the arches for the impacted teeth. No other surgical procedures were carried out prior to the start of appliance treatment. Appliance treatment was deferred for at least six months if an impacted canine was the main reason for treatment, otherwise treatment was commenced according to the needs of the patient. In 94% of the cases, the severity of impaction lessened following extraction of the overlying primary canines and orthodontic treatment. The deepest impactions tended to occur in the oldest children. The majority (75%) of the canines emerged following orthodontic treatment to create space for them in the arch; the remainder were surgically exposed. Appliance treatment tended to take longer in children with the deepest impactions. It is concluded that fixed appliance treatment to create space for a palatally impacted canine is an effective management option for children with impacted maxillary canines.     

The closed eruption technique in cases of impaction of permanent maxillary canines

The impaction of permanent maxillary canines occurs frequently. In recent decades, research has led to 2 methods of treatment: the modified window technique and the closed eruption technique. Although these methods have been described in detail, it is still not clear which method is most effective. In a study involving 73 orthodontic patients with an impacted, palatally displaced permanent maxillary canine, this cuspid was exposed by means of a gingival flap and an orthodontic bracket was immediately fixed on the exposed canine, after which the gingival flap was repositioned using sutures. The patients were clinically and radiographically examined 3 months after the orthodontic treatment. In a control group consisting of 93 orthodontic patients, there were no cases of impacted permanent maxillary cuspids. The overall success rate for the treatment in the study group was 63%. Problems in adjacent teeth were correlated significantly with older age among the patients. There was a significant difference in the number of pockets around the teeth adjacent to the canines in the study group and in the control group.     

Dental anomalies and clinical features in patients with maxillary canine impaction: A retrospective study

Objective:To analyze the prevalence, distribution, clinical features, and relationship with dental anomalies of maxillary canine impaction.Materials and Methods:The complete pretreatment records of 1674 orthodontic patients were examined. Subjects with maxillary impacted canines were divided into two study groups: a palatally displaced canine (PDC) group (114 patients) and a buccally displaced canine (BDC) group (37 patients). These were compared to a control group of 151 patients who were randomly selected from the initial sample without maxillary canine impaction. The significance of associations between canine impaction and dental and clinical features and anomalies was examined with the chi-square test.Results:PDC patients presented with normal overjet and facial profile and a lower degree of dental arch crowding in comparison to the control patients. PDC patients showed a higher prevalence of impaction of other teeth, dental aplasia, transposition, and peg-shaped maxillary lateral incisors (odds ratios 3.3, 2.6, 8.3, and 5.8, respectively).Conclusion:PDC was frequently the only orthodontic problem of patients. BDC group patients did not present with notable differences in clinical and dental features or dental anomalies compared to control subjects.     

Initial vertical and horizontal position of palatally impacted maxillary canine and effect on periodontal status following surgical-orthodontic treatment

OBJECTIVE: To evaluate the impact of surgical-orthodontic treatment and the initial vertical and mesiodistal position of palatally impacted maxillary canines on the periodontal health of impacted canines and adjacent teeth. MATERIALS AND METHODS: The study group consisted of 32 patients with unilateral palatally impacted maxillary canines. The initial position of the impacted canines was assessed on panoramic images. The treatment protocol of the impacted canines included surgical exposure with the closed-eruption technique and fixed orthodontic appliances. RESULTS: A significant increase in pocket depth was found at the canine mesiopalatal point after surgical-orthodontic treatment. Also, a correlation was found between the initial mesiodistal and vertical position of the impacted canine and the posttreatment periodontal status of the impacted canine, the adjacent lateral incisor, and the first premolar. CONCLUSIONS: A combined surgical-orthodontic approach in the treatment of impacted maxillary canines produces clinically acceptable periodontal conditions. The average increase in pocket depth was less than 4 mm and clinically unimportant for most patients.     

泸州地区青少年尖牙阻生的X线分析

目的：通过X线全景片分析泸州地区青少年的尖牙阻生情况。方法：选取2011年1月。2012年12月在泸州医学院附属口腔医院接受x线检查的1800例12—14岁青少年的X线全景片,统计分析阻生尖牙所占比例以及患者的性别、尖牙阻生部位和阻生类型的差异。结果：尖牙阻生在所有患者中所占比例为3．72％（67／1800）,男性：女性为1：1．79;上颌尖牙阻生占3．33％（60／1800）,下颌尖牙阻生占0．33％（6／1800）,上下颌尖牙同时阻生1例;近中向阻生在阻生尖牙中占92％（69／75）,迁徙尖牙占0．22％（4／1800）。结论：本组患者尖牙阻生以女性、单侧上颌尖牙阻生多见,且以近中向阻生为主。     

埋伏上尖牙与侧切牙发生不完全易位的矫治方法研究

目的 探讨埋伏阻生上尖牙与侧切牙发生不完全易位后的导萌方法,将易位的尖牙牵引至正常位置,以达到美观效果,行使正常功能.方法 选择不完全易位的单侧埋伏阻生上尖牙患者12例（男6例,女6例）,年龄11.5～21.0岁,平均14.5岁,其中尖牙偏腭侧阻生7例,偏颊侧阻生5例.外科手术暴露埋伏牙,应用固定矫治技术,调整牵引方向将埋伏牙牵引至正常位置.结果 易位的尖牙均与侧切牙发生位置交换,尖牙移至正常位置,且具有良好的冠根方向和咬合关系,尖牙及侧切牙均无明显根吸收.平均疗程19个月.结论 将不完全易位的埋伏尖牙牵引入正常位置的难点在于易位埋伏的尖牙翻越相邻侧切牙牙根时,二者不相互阻挡.解决此难点的关键是精确判断尖牙牙冠与侧切牙牙根的位置关系,适时调整牵引方向.     

Skeletal features in patient affected by maxillary canine impaction

Objective: To analyze the skeletal features of patients with maxillary canine impaction. Material and Methods: The complete pre-treatment records of 1674 orthodontic patients were examined. From the subjects with maxillary impacted canine 12 patients were excluded , remaining 108. The subjects with maxillary impacted canine were divided into two study groups: a palatally displaced canine group (PDCG) (77 patients) and a buccally displaced canine group (BDCG) (31 patients). The values of the skeletal features measured on the lateral cephalometric radiograph were compared with a control group (CG) of 121 subjects randomly selected from the initial sample without maxillary canine impaction. The statistical analysis of the difference between the study groups and the CG was tested using ?2 test and Fisher’s exact test. The level of significance was set at P ?0.05. Results: The CG was characterized by increased values of A point-Nasion-B point angle (ANB) and by a retro-positioned or smaller lower jaw. PDCG patients showed normal skeletal features compared to the CG, presenting mainly I class and lower rank of II and III sagittal skeletal features. PDCG subjects presented also normal values of the Steiner vertical skeletal relationship angles with normal facial divergence compared to the CG. PDCG cases were also characterized by horizontal and prognathic growth. BDCG did not present significant differences in skeletal features compared to the CG, except for an increased ANB. Conclusions: Palatally displaced canine (PDC) was frequently the only orthodontic problem of patients and was not associated whit altered skeletal features. The frequent absence of malocclusion in PDC patients explains the delayed identification of this problem. BDCG patients did not present significant differences in skeletal features with respect to the orthodontic population. The presence of both buccally displaced canine (BDC) and malocclusion makes the patient with BDC both aware of the need for, and motivated to undergo, orthodontic treatment. Key words:Canine impaction, palatal displacement, buccal displacement, skeletal features.