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。     

单侧上颌尖牙阻生对牙颌三维结构的影响

目的: 采用锥形束CT（CBCT）研究单侧尖牙阻生病例牙颌的三维结构特征,评估发生上颌尖牙阻生的相关风险因素,为正畸临床早期干预提供依据。方法: 选取30例单侧上颌尖牙阻生患者的CBCT,利用Romexis软件进行三维重建,测量、比较两侧牙颌三维结构特征指标,采用SPSS17.0软件包进行配对t检验和相关数据的回归分析。结果: 阻生侧尖牙和侧切牙倾斜度明显增大,尖牙牙冠更向近中、侧切牙向远中倾斜（P<0.001）;阻生侧尖牙体积更大、侧切牙体积更小（P<0.05）,当尖牙体积增大或侧切牙体积减小时,上颌尖牙的阻生概率增加;阻生侧牙弓弧形长度更短,牙弓宽度在尖牙区和前磨牙区更短（P<0.001）,而宽度在磨牙区无显著差异（P>0.05）,两侧牙弓长度在尖牙区、前磨牙区和磨牙区无显著差异（P>0.05）。结论: 上颌尖牙阻生伴随或导致同侧牙及牙槽骨三维方向发育异常,上颌尖牙阻生的严重程度与周围牙颌结构异常密切相关,提示上颌尖牙阻生可以早期预判、诊断,且可以实施有效的早期干预。     

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.     

Prediction of maxillary canine impaction using eruption pathway and angular measurement on panoramic radiographs

ObjectivesTo compare the normal eruption pattern and angulation in impacted maxillary canines using panoramic radiographs to predict maxillary canine impaction.Materials and MethodsPatients aged 6 to 15 years were classified into the normal eruption group (n = 229) and the impaction group (n = 191). At least two panoramic radiographs were taken in the normal eruption group during the eruption process of the maxillary canine. The growth pattern of the maxillary canine was analyzed using an XY coordinate system, with the tip of the maxillary lateral incisor as the origin and the tooth''s long axis as the Y-axis and measurement of the relative position of the crown tip and angulation of the maxillary canine.ResultsThe crown tips of normally erupted maxillary canines were intensively distributed along the distal surface of the maxillary lateral incisor, while those of impacted canines were widely distributed. The angulations of the normally erupted canines increased as eruption increased along the lateral incisor and then decreased at the cervical point of the lateral incisor. The angulations of the impacted canines were scattered, with no uniform pattern.ConclusionsWhile using the normal eruption path of the maxillary canine and the pattern of change in angulation based on the distal surface of the maxillary lateral incisor, early intervention or regular follow-up is needed to prevent maxillary canine impaction.     

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.     

Diagnosis and surgical removal of a rare type of permanent maxillary canine impaction: a case report.

The maxillary canine has a long path of eruption, and the frequency of its impaction is second only to that of third molars. It usually impacts palatally or buccally, and the etiologies of these two types of impaction are quite different. This article highlights the importance of a meticulous radiographic examination and describes the surgical procedure used to treat a permanent maxillary canine impacted buccally to the lateral incisor but palatally to the central incisor.     

上颌尖牙埋伏阻生的临床分析

目的对上颌尖牙埋伏阻生的患病特点及治疗结果进行分析,以期为临床治疗上颌尖牙埋伏阻生提供参考数据。方法在北京大学口腔医学院·口腔医院正畸科门诊2001年1月至2005年1月期间诊治的10505例错(牙合)畸形患者中,经CT检查选出上颌尖牙埋伏阻生患者215例(汉族),共有埋伏阻生尖牙248颗。统计上颌尖牙埋伏阻生在正畸患者中所占比例,χ~2检验分别比较患者性别、唇腭侧阻生以及相应治疗情况的差异。结果上颌尖牙埋伏阻生在正畸门诊患者中约占2．05%,女性：男性为1．8∶1,唇侧：腭侧为2．1∶1。“外科手术暴露+正畸牵引”的方式在治疗中占主导地位。“外科手术拔除”的治疗方式在腭侧埋伏阻生尖牙中的应用多于唇侧,差异有统计学意义(P＜0.01)。结论本组患者上颌尖牙埋伏阻生以女性、唇侧多见,临床对唇腭侧尖牙埋伏阻生的治疗存在一定差异。     

上颌埋伏并与侧切牙易位的尖牙的正畸矫治

目的：探讨上颌埋伏并与侧切牙易位的尖牙的正畸矫治。方法：采用带钩的改良Nance弓联合直丝矫治技术治疗了2例替牙期上颌埋伏并和侧切牙易位尖牙病例,首先用改良Nance弓的末端钩在高位水平地牵引尖牙冠向颊侧及后方移动,同时用直丝弓技术使侧切牙排齐、根近中移动、牙体整体腭侧移动,使尖牙冠和侧切牙根在冠状向分开。然后采用“随形弓”,在维持两者在冠状向和垂直向的距离情况下,不断改变“随形弓”置于尖牙托槽上弓丝水平臂的第二序列弯曲,使两个交叉的易位牙体不断换位。结果：2例患者尖牙及侧切牙恢复正常的排列顺序,牙髓、牙周健康,治疗时间27个月。结论：矫治上颌埋伏并与侧切牙易位的尖牙关键是创造足够的空间,使两个易位牙的牙体换位时无干扰。改良Nance弓联合直丝矫治技术是一种有效的方法。     

Unilaterally impacted maxillary central incisor and canine with ipsilateral transposed canine-lateral incisor

Concurrent impaction and transposition of maxillary anterior teeth is uncommon and poses a challenge for dentists. Early diagnosis and management of eruption disturbances benefits esthetic and functional outcomes. This article describes the treatment of a teenager who had impactions of the left maxillary central incisor and canine as well as ipsilateral canine-lateral incisor transposition. Treatment alternatives and effective orthodontic techniques are delineated. To optimize the treatment results, the impacted maxillary canine was surgically exposed and orthodontically distalized with an innovative cantilever. Subsequently, the deeply impacted maxillary central incisor was uncovered and orthodontically mesialized into the arch. Finally, the displaced maxillary lateral incisor was brought into its normal position. The combined surgical-orthodontic approach resolved a difficult clinical issue and avoided additional restorations. An esthetic, functional outcome was achieved and satisfied the patient.     

Resorption of incisors after ectopic eruption of maxillary canines: a CT study

The purpose of the study was to analyze the extent and prevalence of resorption of maxillary incisors after ectopic eruption of the maxillary canines in a sample of subjects referred to an orthodontic specialist clinic for consultation. The subjects consisted of 107 children, 39 boys and 68 girls, between 9 and 15 years of age (mean 12.5 years), with 156 ectopically and 58 normally erupting maxillary canines. All children were subjected to a basic clinical and intraoral radiographic investigation. These radiographs were supplemented with computerized tomography (CT) of the upper alveolar bones in order to get more precise information on the positions and relationships between the maxillary canines and adjacent incisors and to evaluate resorptions on the roots of the incisors. The results showed that, relative to the roots of the adjacent incisors, the crowns of 21% the ectopically positioned canines were located to the buccal, 18% to the distobuccal, 27% to the lingual, 23% to the distolingual, 5% apically and 6% between the central and lateral incisors. Ninety-three percent of the ectopically positioned canines were in contact with the roots of the adjacent lateral incisor and 19% were in contact with the central incisor. The corresponding figures for the normally erupting canines were 49%. Resorptions on the roots of the incisors adjacent to the ectopically positioned canine occurred in 38% of the laterals and in 9% of the centrals. The resorptions were graded and tended to be extensive. Among the 58 resorbed lateral incisors, resorptions were slight in 31%, moderate in 9%, and severe with pulpal involvement in 60%. The corresponding figures for the 14 resorbed centrals were 36%, 21%, and 43%, respectively. About 60% of the resorptions involved the middle and apical thirds, the tip of the apex not included. On the sides with normally erupting canines, 3 lateral maxillary incisors were slightly or moderately resorbed distally. In all, 51 of the 107 subjects with ectopically erupting maxillary canines (48%) had resorbed maxillary incisors during the eruption of the maxillary canines. There were statistically significant correlations between ectopic eruption of the maxillary canine, contacts between the teeth and resorptions on the adjacent incisors. It was concluded that resorption on maxillary incisors after ectopic eruption of the maxillary canines is a more common phenomenon than previously reported and has to be considered in all cases with seriously diverging eruption of maxillary canines. It was also concluded that the resorptions of the roots of the incisors were caused by pressure during the eruption of the adjacent, aberrant canine. Finally, it was shown that CT scanning substantially increased the detection of root resorptions on incisors adjacent to ectopically erupting maxillary canines (about 50%). The sensitivity of intraoral films was low when diagnosing the resorptions, being calculated to 0.68.     

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.     

The etiology of palatal displacement of maxillary canines.

OBJECTIVES: To test the hypothesis that palatal displacement of the maxillary canine is completely under genetic influence. DESIGN: A randomized controlled design studied cases affected by a severe expression of lateral incisor anomaly on one side and by milder expression of the same anomaly on the other. Comparison of frequency of occurrence of unilateral palatally displaced canine measured in each. Each side acted as control for the other within the same individual. SETTING AND SAMPLE POPULATION: The Departments of Orthodontics of the Universities of Jerusalem and Tel Aviv and in private practice. From approximately 12,000 consecutively treated patients, all those exhibiting an anterior maxilla with a missing lateral incisor on one side, a peg-shaped or reduced lateral incisor on the other, and a palatally displaced canine (n = 19). OUTCOME MEASURE: Missing lateral incisors, peg-shaped, and reduced lateral incisors (all genetically determined characters) have been shown to be associated with palatal displacement of the canine. The canine displacement is presumed by some authorities to be similarly genetically determined. If this is so, then the impacted canine should occur with equal frequency on either side in the patient with a missing lateral incisor on one side and a peg-shaped or reduced lateral incisor on the other. RESULTS: The canine aberration occurred far more frequently on the side of the diminutive lateral incisor. CONCLUSION: There is an environmental factor involved in the palatal displacement of maxillary canines.     

Treatment of a transmigrated and an impacted mandibular canine along with missing maxillary central incisor: A case report

IntroductionTreatment of a case with impacted canines is complex and numerous options are available ranging from disimpaction to forced eruption.ObjectiveThe objective of this case report was to describe the treatment of a 19-year-old male, with a skeletal Class II, dental Class II Division 1 malocclusion, prognathic maxilla, proclined maxillary incisors, with missing left maxillary central incisor and bilateral mandibular canine impaction.MethodologyThe orthodontic treatment plan included forced eruption of the impacted canines and conversion of maxillary left lateral incisor to central incisor.ConclusionProper diagnosis and implementation of orthodontic biomechanics can minimize the amount of prosthetic and surgical intervention needed in the management of transmigrated canine and smile designing.     

The etiology of maxillary canine impactions

The etiology of tooth impactions has long been related to an arch-length deficiency. This is valid for most impactions, but not for palatal impaction of the maxillary canine. This study shows that 85 percent of the palatally impacted canines have sufficient space for eruption. The bud of the maxillary canine is wedged between the nasal cavity, the orbit, and the anterior wall of the maxillary sinus. The buds of the lateral incisor and the first premolar are located behind the canine's palatal surface. An arch-length deficiency will not allow the maxillary canine to "jump" the buds, the nasal cavity, or the sinus in order to reappear in the palate. A canine can be palatally impacted if an extra space is available in the maxillary bone. This space can be provided by (1) excessive growth in the base of the maxillary bone, (2) space created by agenesis or peg-shaped lateral incisors, or (3) stimulated eruption of the lateral incisor or the first premolar. In those conditions the canine is free to "dive" in the bone and to become palatally impacted. A dysplasia in the maxillary-premaxillary suture can also modify the direction of the maxillary canine's eruption.     

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.     

A retrospective study on the influence of maxillary canine impaction on premolar root morphology

Objectives

The root morphology of the maxillary first premolar differs from the other premolars by presenting a high incidence of separated roots. This study addressed the spatial conditions during root development as a possible influencing factor. Therefore, maxillary computed tomographic (CT) scans of patients with regularly erupted or impacted permanent canines were evaluated on the root morphology of the premolars.

Methods

The following parameters were retrospectively analysed in 250 maxillary CT scans (100 patients with regular erupted permanent canines, 150 patients with at least one impacted permanent canine): sex, status of the canines (erupted/impacted), position of the impacted canines (buccal/palatal; vertically inclined inside/outside the dental arch/horizontally inclined) and root morphology of the premolars.

Results

Of the patients, 68 % with at least one impacted canine were female; the canine was impacted palatally in 75.6 % and in a horizontally inclined position in 58.4 %. In patients with an impacted canine, the number of first and second premolars with separated roots was significantly reduced on the ipsilateral as well as on the contralateral side (all p values?<?0.01).

Conclusions

The present study detected an influence of maxillary canine impaction on the root morphology of all premolars, in that impaction and the associated surplus of space resulted in decreased root separation. This supports the hypothesis that root development is at least partly influenced by increased spatial conditions of the dental arch. However, root development can be regarded as a multifactorial event, influenced by space, direct mechanical interferences, as well as genetic predetermination. The retrospective nature of this observational study did not allow for conclusive differentiation between these factors. Alternatively, root separation and the mesial concavity of the first premolar may represent a path for canine eruption similar to the lateral incisor.

Clinical relevance

A single-rooted maxillary first premolar might represent an additional risk factor for canine impaction.     

Root resorptions related to ectopic and normal eruption of maxillary canine teeth – A 3D study

Abstract

Objective. To assess the incidence and severity of root resorption of maxillary incisors caused by ectopically and normally erupting maxillary canines and to analyse factors influencing root resorption of incisors using cone beam computed tomography. Subjects and methods. The study sample comprised 59 patients with a total of 80 canines. Forty-six of the canines, in 37 patients, were defined as ectopic and 34 canines, in 22 patients, were defined as normal. The severity of root resorptions were analysed according to studies by Ericson and Kurol. Multiple logistics regression was used to evaluate the association between various factors and root resorptions. Results. The prevalence of root resorptions was significantly higher in the ectopic canine group, 11.0% of the central incisors and 67.6% of the lateral incisors in comparison to 0% and 36.2% in the normal erupting group. Most resorptions were defined as ‘slight’ and were located in the middle third of the root. There was a statistically significant relationship between canines located mesial to the midline of the lateral incisor and root resorption on the maxillary incisors. Conclusion. The present results show that root resorption of maxillary lateral incisors was common in patients referred to CBCT imaging due to maxillary canine eruption disturbances. Although significantly more frequent in patients with ectopically erupting canines, lateral incisor resorption was also found in association with approximately every third of the normally erupting canines. The best predictor for root resorption seemed to be location of the canine mesial in relation to the midline of the lateral incisor root.     

Dental Anomalies as a Microsymptom of Palatal Canine Displacement

AIM: A retrospective study was performed to investigate whether palatal canine displacement is associated with other dental features permitting early clinical diagnosis of the eruption disturbance. PATIENTS AND METHODS: The study was based on the complete records of 235/8556 patients at the Department of Orthodontics, School of Dental Medicine, University of Freiburg i.Br. (mean age = 14.11 years) with at least one palatally displaced permanent canine. These patients were examined for ten different morphologic parameters, e.g. impaction and congenital absence of further teeth, hypoplastic, peg-shaped, rotated and congenitally missing upper lateral incisors, supernumerary teeth, Angle classification, and cover-bite (= "Deckbiss"). The data were compared with those of a control sample of the same size with physiologic upper canine eruption (mean-age = 10.0 years). Furthermore, in a right/left comparison the local influence of anomalies of the upper lateral incisors on palatal canine displacement was evaluated by multiple linear regression analysis. RESULTS: The statistical analyses revealed that the risk of palatal canine displacement was significantly higher in patients with hypoplasia, peg shape or congenital aplasia of upper lateral incisors, further impacted and congenitally missing teeth and cover-bite. The intergroup differences in terms of gender, rotation of upper lateral incisors and Angle classification were not statistically significant. The right/left comparison revealed a significantly higher risk of palatal canine displacement in association with an adjacent hypoplastic or peg-shaped lateral incisor and with aplasia of the contralateral upper incisor. CONCLUSION: The clinical significance of the study is that the occurrence of palatally displaced canines is often closely linked with other dental anomalies. In this context, anomalies of upper lateral incisors, aplasia or impaction of further teeth, and the anomaly of cover-bite may serve as indicators of palatal canine displacement. A retarded development of the upper lateral incisor seems to be more disturbing for physiologic canine eruption than aplasia. In patients exhibiting the stated microsymptoms, close clinical follow-up of the maxillary permanent canine eruption during the late exfoliation period is strongly recommended.     

Maxillary sinus volume in patients with impacted canines

Objectives:To evaluate the maxillary sinus volumes in unilaterally impacted canine patients and to compare the volumetric changes that occur after the eruption of canines to the dental arch using cone beam computed tomography (CBCT).Materials and Methods:Pre- (T0) and posttreatment (T1) CBCT records of 30 patients were used to calculate maxillary sinus volumes between the impacted and erupted canine sides. The InVivoDental 5.0 program was used to measure the volume of the maxillary sinuses. The distance from impacted canine cusp tip to the target point on the palatal plane was also measured.Results:Right maxillary sinus volume was statistically significantly smaller compared to that of the left maxillary sinus when the canine was impacted on the right side at T0. According to the T1 measurements there was no significant difference between the mean volumes of the impaction side and the contralateral side. The distance from the canine tip to its target point on the palatal plane were 17.17 mm, and the distance from the tip to the target point was 15.14 mm for the left- and right-side impacted canines, respectively, and there was a significant difference between the mean amount of change of both sides of maxillary sinuses after treatment of impacted canines.Conclusions:Orthodontic treatment of impacted canines created a significant increase in maxillary sinus volume when the impacted canines were closer with respect to the maxillary sinus.     

3 '2' 1: Orthodontic re-positioning of canines into central incisors

Resorption of lateral incisors caused by impacted maxillary canines is frequently reported. However, resorption of the central incisor is less common and management of such a finding can prove to be a challenge for the clinician. This article reviews the literature of impacted canines and incisor resorption. The management of two cases of severe central incisor resorption caused by an impacted maxillary canine is also described.