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。     

上颌腭侧埋伏阻生尖牙 CBCT 导引下的牵引治疗

目的:探讨锥形束CT(CBCT)三维(3D)重建在上颌腭侧埋伏阻生尖牙牵引治疗中的指导作用。方法:对22例上颌尖牙(共26颗)腭侧埋伏阻生的青少年患者行CBCT检查。CBCT三维重建观察尖牙形态、腭侧埋伏状况,测量分析与邻近组织的位置关系及相邻切牙牙根吸收情况。结果:CBCT能够真实再现颌骨内埋伏的上颌尖牙。埋伏尖牙均近中倾斜,与平面平均成角61.1°±18.1°,近中异位分别为Ⅰ类埋伏尖牙8颗、Ⅱ类5颗、Ⅲ类3颗、Ⅳ类10颗。3颗相邻侧切牙及2颗中切牙因严重牙根吸收而拔除;26颗上颌腭侧埋伏尖牙均成功牵引至平面排入牙弓并建立正常咬合。结论:CBCT能立体再现上颌尖牙腭侧埋伏阻生特征及与邻近牙的关系等,对治疗方案的制定、开窗牵引具有指导作用,可提高疗效。     

上颌尖牙腭侧埋伏阻生的锥形束CT定位诊断

目的应用锥形束CT（CBCT）探讨上颌腭侧埋伏阻生尖牙的埋伏特征及邻牙牙根吸收情况。方法选取南京医科大学附属口腔医院正畸科就诊的上颌尖牙腭侧埋伏阻生的青少年患者22例,获取CBCT三维数据,应用Dolphin imaging 11.0软件,分析腭侧埋伏尖牙的埋伏状况、与邻牙位置关系并分类,观察邻牙牙根的吸收情况。结果上颌腭侧埋伏尖牙大多近中、腭向倾斜阻生,近中异位以Ⅰ类和Ⅳ类较为多见,分别占30.8%和38.5%;近中倾斜角度多在53.8°~68.5°,腭侧异位距正中矢状面多在5.4~8.4 mm。年龄越大,上颌腭侧埋伏尖牙近中腭向异位越远,近中倾斜角度越大。84.6%的相邻侧切牙及19.2%的中切牙牙根与埋伏尖牙接触;50%的相邻侧切牙及15.4%的邻中切牙牙根吸收,相邻侧切牙吸收多位于根尖1/3,而相邻中切牙吸收多位于根中1/3;相邻切牙牙根吸收概率与腭侧埋伏尖牙与切牙间的最小距离呈反比关系。结论CBCT能在三维方向诊断上颌尖牙埋伏状况及与邻近组织的关系,准确判断邻牙根吸收情况,准确测量埋伏尖牙倾斜度及埋伏深度,为上颌腭侧埋伏尖牙的治疗提供指导。     

上颌倒置埋伏阻生中切牙的序列治疗

目的探讨上颌倒置埋伏阻生中切牙的综合序列治疗方案。方法 10例患者共11颗倒置埋伏阻生上颌中切牙为研究对象,经摄片定位、拓展间隙后,采用外科开窗、隧道牵引、选择性根管治疗及根尖切除术、修复等序列治疗。结果 11颗埋伏牙通过治疗后7颗成功牵引入牙列,排列整齐,牙周健康及牙髓活力正常;1颗唇侧出现1~2 mm的牙龈退缩;2颗需配合烤瓷冠修复;1颗进行了预防性根管治疗和根尖切除术,并进行烤瓷冠修复。结论上颌倒置埋伏阻生中切牙采用序列治疗可以取得良好的美观和功能效果。     

导杆式矫治器治疗上颌唇侧倒置埋伏中切牙

目的:探讨导杆式矫治器治疗上颌唇侧倒置埋伏阻生中切牙的临床效果及治疗作用。方法:术前拍摄曲面断层片、头颅侧位片及CBCT明确诊断和定位患牙,用导杆式矫治器对16例上颌唇侧倒置埋伏中切牙进行外科-正畸联合治疗。固定保持1年后,拍CBCT评价远期疗效。测量矫治后埋伏牙和对侧同名牙的根长,用SPSS17.0软件进行配对t检验。结果:16例唇侧倒置埋伏中切牙均牵引入牙列排齐,牙髓和牙周状况良好。保持1年后X线及临床检查示埋伏牙均正常。埋伏牙的根长(8.32±1.70)mm短于对侧同名牙(10.12±1.71)mm(P<0.001)。结论:对未成年患者应保留上颌埋伏中切牙;导杆式矫治器是治疗上颌唇侧倒置埋伏中切牙的一种有效方法。     

曲面体层片和螺旋CT三维重建对上颌埋伏中切牙唇腭向定位的对比研究

目的应用曲面体层片(panoramic tomography,PTG)和螺旋CT三维重建(three-dimensional reconstruction of spiral computed tomography,3D CT)对上颌埋伏中切牙(impacted maxillary central incisors,IMCIs)进行唇腭向定位,比较两者的差异,探讨应用PTG对上颌埋伏中切牙进行唇腭向定位的方法。方法对25例上颌埋伏中切牙使用PTG和3D CT成像,3D CT成像包括表面遮盖技术(shaded surface display,SSD)和多平面重建技术(multiplanar reformation,MPR)。在3D CTMPR矢状位图像上测量埋伏中切牙唇腭向的倾斜角度(labial-palatalangle,LPA),综合MPR及SSD图像对埋伏牙冠根唇腭向分布进行评估;在PTG图像上通过反三角函数测算埋伏中切牙的LPA,并对埋伏牙冠根在唇腭向的分布进行评估;对两种成像方法得到的上述结果用SPSS11.5进行统计学分析。结果通过PTG测算的埋伏中切牙的LPA与在3D CT图像上测得的LPA显著相...     

上颌中切牙与尖牙同时阻生的临床特征分析

目的分析上颌中切牙与同侧尖牙同时阻生病例的临床特征。方法选择上颌中切牙与同侧尖牙同时阻生病例21例,分析上颌中切牙阻生类型与尖牙阻生情况,测量阻生侧及对侧侧切牙发育或萌出异常情况。结果与中切牙阻生同时发生的尖牙76.2%为唇侧阻生,其中完全易位与不完全易位占唇侧阻生尖牙的68.8%,尖牙唇侧阻生病例中侧切牙根远中倾斜和伴牙冠近中倾斜者占87.5%,尖牙唇侧或腭侧阻生病例中,出现锥形或过小等畸形侧切牙的比例分别为31.25%和40.00%。上颌中切牙与尖牙不同阻生类型患者,前牙反牙合比例都超过40%,且多为牙型反牙合。结论与中切牙阻生同时发生的尖牙阻生多为唇侧阻生,与中切牙阻生类型无关,与侧切牙根远中倾斜高度相关,尖牙完全易位与过小或锥形等畸形侧切牙有关。     

倒置埋伏阻生上颌中切牙的临床矫治效果研究

目的 探讨倒置埋伏阻生上颌中切牙的矫治时机和矫治方法.方法 选择10例患者共10颗上颌单侧倒置埋伏阻生中切牙为研究对象.矫治前常规拍摄全口曲面断层片、CT片,确定倒置埋伏牙的冠根形态及其与邻牙的关系.根据埋伏牙的翻转角度选择面弓式前方牵引器或主弓丝牵引.牵引结束测试牙髓活力.结果 通过7～14个月牵引,倒置埋伏阻生的上颌中切牙基本达到牙列的正常位置;埋伏牙牙髓活力测试结果为25.9±2.8,对侧同名牙为25.0±3.3,差异无统计学意义(t=1.15,P=0.159).结论 倒置埋伏阻生的上颌中切牙并非一定需要拔除,选择恰当的时机对倒置埋伏阻生的上颌中切牙给予有效的外科-正畸联合治疗,效果较好.     

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。     

唇、腭向倾斜上中切牙桩核冠修复有限元模型的构建

目的：建立唇、腭向不同倾斜角度上颌中切牙经纤维桩、树脂核和全瓷冠修复后的三维有限元模型.方法：对完整上颌中切牙、预备后牙体和纤维桩进行Micro-CT扫描,结合Mimics、Geomagic Studio、SolidWorks 和Abaqus软件建立三维有限元模型.结果：通过Micro-CT扫描结合Mimics、Geomagic Studio、SolidWorks 和Abaqus软件,建立了上颌中切牙在0°冠根夹角及向唇侧或腭侧倾斜10°、20°、30°时纤维桩核冠修复的三维有限元模型共7个.结论：本研究成功建立唇、腭向不同倾斜角度上颌中切牙经纤维桩、树脂核和全瓷冠修复后的三维有限元模型.     

Use of the apically repositioned flap in the management of labially impacted maxillary central incisors

Management of labially impacted maxillary central incisors often requires a coordinated surgical and orthodontic approach. In such cases, the treatment objective is surgical exposure of the unerupted incisor, preferably with a functional width of keratinized gingiva on the labial surface. Tooth exposure is then followed by orthodontic intervention to move the tooth to the line of occlusion. This paper describes three cases where the apically repositioned flap technique was used to manage labially impacted maxillary central incisors.     

The impacted maxillary canine. Further observations on aetiology, radiographic localization, prevention/interception of impaction, and when to suspect impaction

A bstract — Adjacent anomalous or missing maxillary lateral incisors have been implicated in the aetiology of palatally displaced canines by not providing proper guidance to the canine during its eruption. However, a recent review of the literature suggests that the aetiology of palatally displaced canines is genetic in origin. The aetiology of labially impacted canines differs, being due to inadequate arch space. Vertex occlusal radiographs have been recommended for localization but have limitations, and a case is illustrated where this radiograph is deceptive. The prevention/interception of a palatally displaced canine by the extraction of the deciduous canine is best carried out as early as the displacement is detected, mostly soon after 10 years of age. Usually, prevention/interception will avoid the surgical and orthodontic treatment needed to align a palatally impacted canine and may help prevent resorption of the adjacent incisor root. Suspicions that an impaction could occur or has occurred arise a) before the age of 10 years if there is a familial history and/or the maxillary lateral incisors are anomalous or missing; b) after the age of 10 years if there is asymmetry in palpation or a pronounced difference in eruption of canines between the left and right side; or, the canines cannot be palpated and occlusal development is advanced; or, the lateral incisor is proclined and tipped distally; and, on a panoramic radiograph of the late mixed dentition if the incisal tip of the canine overlaps the root of the lateral incisor.     

J钩牵引方向对上颌切牙牙周膜初始应力影响的三维有限元分析

目的 分析J钩牵引方向变化对上颌切牙牙周膜应力分布的影响,探讨J钩牵引过程中的力学机制,为临床正畸提供客观的理论依据。方法 建立上颌牙齿及矫治器的三维有限元模型;在弓丝定点上以1.5 N的力保持与矢状面颊向30°不变,与牙合平面角度从0°~90°之间每5°加载一次,描绘出上颌切牙牙周膜应力图。结果 随着牵引角度增大,上切牙牙周膜压应力区由腭侧近颈缘和唇侧近根尖逐渐变为腭侧近根尖和唇侧近颈缘;牵引角度65°~75°时,中切牙牙周膜应力比较均匀,牵引角度45°~55°时,侧切牙牙周膜应力较均匀。结论 随着角度的增大,切牙由舌倾趋势变为唇倾趋势。     

Impaction of the central maxillary incisor associated with supernumerary teeth: initial position and spontaneous eruption timing

The aim of the retrospective study was to evaluate the influence of the initial vertical position of the impacted maxillary incisor on spontaneous eruption frequency and timing after surgical removal of the supernumerary tooth. Records of 33 patients with unilateral impaction of upper central incisor caused by supernumerary teeth with the average age 9.58+/-1.54 years were analyzed. Impacted teeth were distributed into 3 groups on the basis on their initial vertical position on the orthopantomograms. The results indicate that impacted maxillary central incisors spontaneously erupt in 63.6% of cases after removal of supernumerary teeth. The average time of the spontaneous eruption of impacted maxillary central incisors was 16.05+/-9.3 months (from 3 to 30 months). Statistically significant differences in the spontaneous eruption time were found between the groups with different initial vertical position of the impacted central maxillary incisor. Maxillary central incisor impacted at the projection level of the apical third of the contralateral completely erupted central maxillary incisor should be treated by the surgical-orthodontic approach, because spontaneous eruption is unlikely to expect.     

Maxillary canine impactions related to impacted central incisors: two case reports

AIM: The purpose of this case report is to describe the combined surgical and orthodontic treatment of two cases with an impacted maxillary central incisor and canine in the same quadrant and to discuss the causal relationship between them. BACKGROUND: The most common causes of canine impactions are usually the result of one or more factors such as a long path of eruption, tooth size-arch length discrepancies, abnormal position of the tooth bud, prolonged retention or early loss of the deciduous canine, trauma, the presence of an alveolar cleft, ankylosis, cystic or neoplastic formation, dilaceration of the root, supernumerary teeth, and odontomas. Although impaction of the maxillary central incisor is almost as prevalent as impacted canines its etiology is different. The principal factors involved in causing the anomaly are supernumerary teeth, odontomas, and trauma. REPORTS: Case #1: A 10.5-year-old girl in the early mixed dentition stage presented with a chief complaint of the appearance of her anterior teeth. She had a Class I skeletal pattern and a history of trauma to the maxillary central incisors at age five with premature exfoliation. Radiographs revealed an impacted upper right central incisor in the region of the nasal floor, delayed eruption of the maxillary permanent central incisor, and the adjacent lateral incisor was inclined toward the edentulous space. Treatment was done in two stages consisting of surgical exposure and traction of the impacted central incisor and fixed orthodontic treatment. Case #2: An 11.5-year-old girl presented for orthodontic treatment with the chief complaint of an unerupted tooth and the appearance of her upper anterior teeth. She was in the late mixed dentition period with a Class III skeletal pattern along with an anterior cross-bite with some maxillary transverse deficiency. The maxillary right canine and central incisor were absent, but the maxillary right deciduous canine was still present. Treatment included arch expansion followed by surgical exposure and traction of the impacted teeth and fixed orthodontic treatment. SUMMARY: This case report provides some evidence of a significant environmental influence of an impacted maxillary central incisor on the path of eruption of the ipsilateral maxillary canine. When an impacted maxillary central incisor exists, the maxillary lateral incisor's root might be positioned distally into the path of eruption of the maxillary canine preventing its normal eruption. Ongoing assessment and early intervention might help to prevent such adverse situations from occurring.     

倒位埋伏阻生上中切牙的临床矫治探索

目的 探索倒位埋伏阻生上颌中切牙的矫治方法,以提高临床矫治效果和保留更多的倒位阻生牙.方法对8例患者的9颗倒位埋伏阻生的上中切牙采用开拓间隙、手术开窗牵引、固定人工支点协助调向、排齐、反向控根等方法进行矫治.结果9颗倒位阻生的上中切牙中,有8颗经过15～30个月的矫治达到正常位置,牙齿稳定,功能正常.剩余1颗因牵引15...     

改良Nance弓在矫治上颌腭侧埋伏尖牙的作用

目的 探讨改良Nance弓在矫治上颌腭侧埋伏尖牙时矫治力方向设计及支抗设计的作用.方法 7例单侧上颌腭侧埋伏尖牙均采用外科-正畸联合治疗.手术暴露埋伏尖牙牙冠,粘接舌侧扣;戴入改良Nance弓,利用改良Nance弓位于腭侧不锈钢丝上的附钩,先将尖牙冠向后牵引绕过侧切牙的牙根,直到位于正常尖牙间隙的腭侧,如尖牙间隙不足,则粘结上颌托槽,预备尖牙间隙;再采用直丝弓技术将埋伏尖牙向唇侧移动,排齐牙列,调整咬合关系.对治疗后牙齿的松动度、牙髓活力等进行观察.结果 7位埋伏尖牙均被牵引至牙弓的正常位置;牙髓活力测试正常,牙周附着良好.结论 改良Nance弓在矫治上颌腭侧埋伏尖牙时,在矫治力方向设计和支抗控制方面有独特优点和作用.