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。     

Effects of impacted maxillary canines on root resorption of lateral incisors

Objectives

The aim of this study was to analyze the amount of root resorption of maxillary lateral incisors by relating the position, location, and angulation of the impacted canine using cone-beam computed tomography (CBCT).

Materials and methods

The study sample consisted of panoramic and CBCT radiographs of 46 patients with a unilateral impacted canine (16 males and 30 females; mean age: 19.53 ± 6.66 and 19.44 ± 5.77 years, respectively). Sector location and canine angulation were measured in panoramics. All tomographs were obtained using CBCT (NewTom 5G, QR, Verona, Italy) and three-dimensional (3D) reconstructions of the maxillary laterals assessed by Mimics 14.01 image analysis software.

Results

Upper lateral incisor volume was smaller on the impacted side (401.95 ± 83.69 mm³) than on the nonimpacted side (433.54 ± 92.6 mm³, P < 0.05). There were no significant differences of lateral root resorption volume when comparing the impacted canines being on the labial or palatal sides (P > 0.05), but impacted canine angulation was significantly steeper on the labial side (70.85°) than on the palatal side (46.09°, P < 0.05). The volume of root resorption of laterals when comparing the various positions of the canine in different sectors or canine angulation in 30^o intervals was not statistically significantly different (P > 0.05).

Conclusions

The impacted canines caused root resorption of lateral incisors. The angulation of the canine was steeper on the labial side than on the palatal side but root resorption of adjacent laterals was not different. There were no statistically significant differences in the amount of root resorption of the laterals when the canine was evaluated according to localization and angulation.

     

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??Objective    To evaluate the position of maxillary impacted canines and resorption of neighboring incisors with cone beam computed tomography ??CBCT??. Methods    Impacted maxillary canines in sixty-seven patients were selected and scanned by the Planmeca ProMax 3D at Stomatological Hospital of Jilin University from Dec.2015 to Jan.2017. The three-dimensional images were obtained by Invivo 5.4.5 software. Each impacted canine was positioned and the root resorption of adjacent incisors was observed in sagittal??coronal and axial views. Results    In sagittal plane view??except 10 horizontal impacted canines ??12.0%?? and 1 inverted impacted canine ??1.2%????33.7% of impactions were labial??30.1% were palatal??and 22.9% were middle. In coronal plane view??12.0% of the cusp tips of maxillary impacted canines were near the crown of the adjacent incisor??42.2% were near cervical third of the root of the adjacent incisor??24.1% were near middle third of the root of the adjacent incisor??9.6% were near apical third of the root of the adjacent incisor??and 12.0% were near the root tip of the adjacent incisor.In axial plane view??65.1% of impactions were mesial??12.0% of impactions were distal??and 9.6% were middle. About 17.9% lateral incisors had root resorption??and 9.7% central incisors ??13?? had root resorption??the difference being statistical ??P < 0.05??. Conclusion    CBCT is a better way in the diagnosis and analysis of the position and root resorption of maxillary impacted canines??which provides guidance to the treatment.     

上颌阻生尖牙牵引治疗后邻近切牙牙根吸收情况的研究

目的 分析上颌阻生尖牙正畸牵引治疗后邻近切牙的牙根吸收情况及可能的相关因素。方法 选取上颌尖牙阻生且符合标准的43例患者,年龄10～23岁,共60颗上颌埋伏阻生尖牙。上颌阻生尖牙正畸牵引治疗前后分别拍摄锥形束CT,分析阻生尖牙邻近切牙的牙根吸收程度,并对可能存在的相关因素进行分析。结果 上颌阻生尖牙正畸牵引治疗后,上颌中切牙发生轻、中、重度牙根吸收的概率分别为71.7%、15.0%、13.3%,上颌侧切牙发生轻、中、重度牙根吸收的概率分别为48.3%、36.7%、15.0%,上颌中切牙与侧切牙牙根吸收严重程度存在差异(P<0.05)。位于腭侧及颌骨内、低位且靠近面中线的阻生尖牙,在正畸牵引治疗后,侧切牙牙根吸收程度较重(P<0.05)。低位阻生尖牙牵引治疗后,中切牙牙根吸收较重(P<0.05)。牵引时间较长时,中切牙牙根吸收程度较重(P<0.05)。治疗前已发生牙根吸收的切牙,在阻生尖牙牵引治疗后发生的牙根吸收程度较重(P<0.05)。结论 上颌侧切牙在阻生尖牙正畸牵引治疗后,发生的牙根吸收程度较重。上颌阻生尖牙正畸牵引治疗后,邻近切牙牙根吸收情况与阻生尖...     

The position of maxillary canine impactions and the influenced factors to adjacent root resorption in the Korean population

The purpose of this study was to evaluate the position and aspects of maxillary canine impactions in the Korean population and investigate its comparison with the previous reports, while aiding in the establishment of diagnosis and treatment planning by revealing the influential factors of root resorption associated with such impactions. The subjects of this study consisted of 186 teeth from 148 patients, who had visited Seoul National University Dental Hospital due to impacted canines and had taken computerized tomographic images and panorama radiographic images. As a result, maxillary canine impaction in the Korean population occurred 1.5 times more often in females (F:M = 89:59) than males. Regarding the position of impaction, there were three times more buccal impactions (B:P = 140:46) than palatal impactions. The occurrence of root resorption was as high as 49.5 per cent. In evaluating the influential factors affecting adjacent root resorption, the significance of the impacted angulation was insufficient (P = 0.652). However, the buccopalatal position (P < 0.0001) and mesiodistal placement (P = 0.006, 0.037) of the impacted tooth were determined to be significant factors. Therefore, the adjacent root resorption caused by impacted maxillary canines can be stated to exhibit a greater amount of resorption as the positional proximity of the canine crown and lateral incisor root increases.     

曲面断层片和锥形束CT对上颌阻生尖牙的定位分析

目的:通过对曲面断层片中上颌阻生尖牙近远中向和垂直向的影像学分区,判定其与锥形束CT (cone-beam computed tomography, CBCT)中相应尖牙唇腭侧位及相邻恒切牙根吸收之间的关系。方法:对68例患者的94颗上颌阻生尖牙进行曲面断层片的拍摄和CBCT扫描。将曲面断层片中上颌阻生尖牙近远中向牙尖所处的位置分为5区(Ⅰ区-Ⅴ区),将牙冠所处的垂直向高度分为3部分(牙冠段,根中段,根尖段),其唇腭侧位置和相邻恒切牙的根吸收情况则由CBCT判定。结果:曲面断层片中上颌阻生尖牙近远中向的区域定位与CBCT中相应阻生牙的唇腭侧位之间有显著相关(P＜0.001),唇侧阻生的尖牙常出现在曲面断层片中的Ⅰ、Ⅱ、Ⅲ区域,正中牙槽阻生的多在Ⅳ区域,腭侧阻生的常在Ⅴ区域,而垂直向的分段与之无显著相关。CBCT中相邻恒切牙的根吸收常发生在Ⅳ、Ⅴ区域和根中段、根尖段。曲面断层片中阻生尖牙近远中向和垂直向的区域划分均与CBCT中相邻恒切牙的根吸收之间有统计学意义(P＜0.05)结论:利用曲面断层片中上颌阻生尖牙近远中向的区域定位可以预测其唇腭侧位和相邻恒切牙的根吸收,垂直向的分段可用来判断相邻恒切牙的根吸收,而不可推测其唇腭侧阻生情况。     

The morphological studies of root resorption of maxillary primary canines and their relation with the position of successive permanent teeth using Micro-CT

The purpose of this study is to clarify the root resorption of maxillary primary canines in relation to the development of successive permanent teeth. It was observed the maxilla of dry skulls of Indian children, using Micro-CT, and measured shortest distance between the root surface of maxillary primary canine and the bony crypt of maxillary canine. The bony crypt including successive canine was positioned almost directly above the root of primary canine and located superior to another bony crypts in the primary dentition stage. When the first molars reached the alveolar crest in addition to the primary dentition stage, the bony crypt of canine grew, showing the distal inclination of the superior margin and mesial inclination of the inferior margin. After the stage which is central incisors reached the alveolar crest, root resorption of primary canines was observed on the lingual side nearby the root apex and the bony crypt of canine was adjacent to the nasal cavity. It was quantitatively shown that the distance between the roots of primary maxillary canine and canine bony crypts reduced from central incisors reached the alveolar crest to lateral incisors reached that.     

Three-dimensional evaluation of angular,linear, and resorption features of maxillary impacted canines on cone-beam computed tomography

Objectives

The aim of this study was to evaluate the localization, angulation, and resorption features of maxillary impacted canines on cone-beam computed tomography (CBCT).

Methods

This retrospective study examined the CBCT scans of 140 maxillary impacted canines in 102 patients (43 males, 59 females; mean age: 16.25 ± 6.31 years). The following impacted canine-related parameters were analyzed on the CBCT images: impaction side; location; root resorption levels of adjacent teeth; occlusal plane and midline distances of impacted canines; and angulations of impacted canines to midline, lateral incisor, and occlusal plane.

Results

Bilateral canine impaction was found in 38 subjects, and unilateral canine impaction was present in 64 subjects. Severe resorption was found in 14 canines. There were no significant differences between the occlusal plane and midline distances to the impacted canine cusp tip and root apex (p > 0.05). The midline angulation of right maxillary impacted canines was significantly higher than that of left maxillary impacted canines (p < 0.05), while the occlusal plane angulation of left maxillary impacted canines was significantly higher than that of right maxillary impacted canines (p < 0.05).

Conclusions

Maxillary canine impaction was more frequently seen in female subjects than in male subjects. Lateral incisors were more frequently affected than first premolars, and slight resorption was more frequently seen in adjacent teeth. CBCT assessment of maxillary impacted canines can provide accurate measurements of angular, linear, and resorption parameters.

     

Long-term follow-up of severely resorbed maxillary incisors after resolution of an etiologically associated impacted canine

BACKGROUND: Resorption of maxillary incisor roots because of an impacted canine is a well-recognized phenomenon that occurs in a surprisingly high proportion of patients with impacted canines. In this retrospective study, we studied a sample of patients in whom the resorption was particularly severe. METHODS: The sample consisted of 11 patients (age, 11.8 +/- 1.2 years) with 20 severely resorbed maxillary incisors. The amount of resorption was measured at the outset (T1), when the impacted canine was distanced from the incisor root area (T2), at the completion of the orthodontic treatment (T3), and at a follow-up appointment at least 1 year posttreatment (T4). RESULTS: A 17.2% increase in the crown/root ratio occurred due to aggressive continued resorption between T1 and T2. The resorption rate reduced to an almost insignificant level, despite continued and often appreciable orthodontic movement of the resorbed teeth from T2 to T3. CONCLUSIONS: Patients with impacted canines should be screened for resorption and the impacted tooth treated as soon as possible. The resorption process can be halted and the affected tooth moved orthodontically without further risk of resorption. In the long term, with early treatment, even severely resorbed teeth do not suffer from increased mobility or discoloration and might not require splinting.     

The prevalence of root resorption of maxillary incisors caused by impacted maxillary canines

Objectives

The aim of this study was to evaluate the prevalence of root resorption of maxillary incisors caused by impacted maxillary canines using low-dose dental computed tomography and to gain additional knowledge of the underlying aetiology and the progression of root resorption.

Materials and methods

A total of 440 patients (mean age, 24.7 years) with 557 impacted maxillary canines were examined regarding their location and the occurrence of root resorption of maxillary incisors.

Results

The frequency of root resorption was 2 % of central and 7.7 % of lateral maxillary incisors. The location of the 557 impacted canines within the dental arch was palatal in 67.5 %, buccal in 15.4 % and central in 17.1 %. No significant differences could be shown with respect to the width and the shape of the dental follicle of the impacted maxillary canines and the presence of root resorption of incisors. The presence of root resorption of central (p?<?0.0001) and lateral (p?<?0.023) maxillary incisors was significantly correlated with an existing contact relationship of the impacted maxillary canines.

Conclusions

Our investigation confirms the theory of prior reports comprising a much larger patient population, hypothesising that the dental follicle of impacted maxillary canines does not cause resorption of adjacent maxillary incisors per se.

Clinical relevance

Root resorption of maxillary incisors is correlated with effects of contact of the impacted maxillary canines, and these findings should be considered in treatment planning. Our findings are consistent with other reports and may develop new treatment approaches for the treatment of this sequela.     

Palatally impacted canines: aetiology of impaction and the scope for interception. Report of cases outside the guidelines for interception

Patients with palatally impacted canines have an increased incidence of missing or anomalous lateral incisors adjacent to the impacted canines. Their arches are often uncrowded and this, in part, is linked to the increased incidence of missing or anomalous lateral incisors. Other teeth are also more frequently missing. The present guidelines for the relief of palatally impacted canines by extraction of the deciduous canine require that the patient is aged between 10–13 years and that normal space conditions are present. Two successful case reports are presented which were outside the recommended guidelines. The technique of relieving a palatal impaction by extraction of the deciduous canine has wide application.     

Impacted upper canines: examination and treatment proposal based on 3D versus 2D diagnosis

Aim

The purpose of this diagnostic cross-over study was to evaluate whether three-dimensional (3D) diagnostics (cone-beam computed tomography, CBCT) was superior to two-dimensional (2D) diagnostics (panoramic X-ray, OPG) in patients with impacted upper canines for assessing their position and the probability of their alignment.

Materials and methods

Panoramic X-rays, CBCTs, and study casts of 21?patients with a total of 29 impacted maxillary canines were analyzed. Patients with syndromes or tooth aplasias were excluded. A total of 26?dentists of various specialist disciplines rated different parameters, such as canine position and their probability of alignment as well as their relation to and resorption of adjacent teeth. 2D X-rays and study casts were rated first; then 3D images and casts were evaluated at least 2?weeks later. The actual level of displacement was defined by two trained examiners and labeled as the master finding, according to modified criteria established by Ericson and Kurol (1988).

Results

In 64% of all patients, canine position was assessed concordantly in 2D and 3D images. 2D assessments were in slight agreement (???=?0.374), while 3D ratings were in good agreement with the master findings (???=?0.714). Two-thirds of the canines?? apical regions were judged identifiable in 2D and 3D images; more than 1/4 of the canines?? apices were not identifiable in 2D images, but were identifiable in 3D images. The diagnosis of lateral incisor root resorption in the CBCT agreed well with the master finding (???=?0.634), but examiners overlooked slight resorption in 20% of the patients. In 82% of the patients teeth, treatment suggestions (orthodontic alignment or surgical removal) were the same for 2D and 3D images. Canine inclination visible in the panoramic X-rays was the most important factor influencing the treatment proposal.

Conclusion

Small volume CBCT may be justified as a supplement to a routine panoramic X-ray in the following cases: when canine inclination in the panoramic X-ray exceeds 30°, when root resorption of adjacent teeth is suspected, and/or when the canine apex is not clearly discernible in the panoramic X-ray, implying dilaceration of the canine root. We intend to validate the results of this study in a clinical trial.     

Root resorption associated with ectopically erupting maxillary permanent canines: a computed tomography study

The aims of this retrospective computed tomography (CT) study were to determine the occurrence of severe root resorption involving the pulpal canal of adjacent permanent teeth associated with ectopically erupting canines, and to verify the existence of related factors. The sample consisted of 255 consecutive patients (159 females and 96 males, mean age 18.4 and 16.8 years, respectively). Three hundred and thirty-four ectopic maxillary canines and adjacent teeth were analysed using CT images. Statistical significance was evaluated with chi-square and Fisher's exact tests. The results showed that severe root resorption of adjacent permanent teeth occurred in 17.7 per cent of ectopic canines and was equally common in females and males. Severe root resorption affected 12.6 per cent of the lateral incisors, 4.8 per cent of the first premolars, and 2.1 per cent of the central incisors. No relationship was found between the type or side of ectopic eruption, inclination of the longitudinal axis of the ectopic canine and the occurrence of severe root resorption. A significant relationship was found between a bucco-lingual position of the ectopic canine and root resorption (P < 0.05). Root resorption mainly occurred in the apical third (57.6 per cent) and apical and middle thirds (27.1 per cent). A significant relationship existed between the occurrence of root resorption and complete loss of space for the erupting canine (P < 0.05). No association was found between alignment of the upper permanent incisor and root resorption. A widened dental follicle occurred in 15 per cent of ectopic canines but did not cause root resorption of the adjacent permanent teeth. Since root resorption is asymptomatic, early detection by radiographic examination is essential for correct diagnosis and treatment.     

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.     

预置支点介导下的上颌近远中阻生尖牙的矫治

目的 探讨预置支点在矫治上颌水平阻生尖牙的作用.方法 水平埋伏阻生上颌尖牙5例,均位于邻牙根方.用直丝弓矫治器进行间隙预备,外科开窗暴露埋伏尖牙的牙冠,将预置支点置于牙颈部,进行正畸牵引,曲面断层片观察邻牙牙根吸收情况.结果 水平阻生尖牙以预置支点为转动中心而移动至正常位置,牙髓和牙周情况良好,邻牙牙根无吸收现象.结论 预置支点水平阻生上颌尖牙的转动中心,对正畸临床治疗有指导意义.     

牙槽嵴裂患者上中切牙长度的锥形束CT测量

目的使用锥形束CT测量牙槽嵴裂患者的裂隙侧上中切牙长度,并比较其与非裂隙侧牙齿及正常对照切牙的差异。方法选取在北京大学口腔医学院放射科接受Newtom 9000 CT扫描的158名先天性牙槽嵴裂患者,包括男性101例,女性57例,平均年龄16．52岁;其中单侧牙槽嵴裂125例,双侧牙槽嵴裂33例。另选取同期接受扫描的非唇腭裂患者31名作为对照,其中男性17例,女性14例。平均年龄为15．81岁。所有患者均无累及切缘缺损,无正畸治疗史。沿上前牙长轴方向对上颌区CT扫描的原始数据进行重建。结果上中切牙长度有性别差异,男性大于女性。男性双侧牙槽嵴裂患者中切牙长度小于单侧患者的裂隙侧中切牙长度（1．55mm,P〈0．01）,但是女性中差异无统计学意义;无论男女性别,二者均小于单侧牙槽嵴裂患者的非裂隙侧中切牙长度（男1．15mm,P〈0．01;女1．44mm,P〈0．01）;另外,单侧患者的非裂隙侧中切牙长度与对照组差异无统计学意义。结论牙槽嵴裂患者裂隙侧中切牙长度较非裂隙侧牙齿及正常对照短。     

Early and unusual incisor resorption due to impacted maxillary canines.

A very early and severe case of maxillary incisor resorption caused by impacted canines is reported. An estimated 50,000 cases of ectopic eruption and impaction of maxillary canines occur each year in the United States. Although incisor resorption due to ectopically positioned permanent maxillary canines can be swift, silent, and devastating, an effective protocol has been developed for early detection and management of this condition. Palpation and, if indicated, radiographic evaluation are combined with primary canine removal in selected cases. These strategies--particularly when used early--can prevent the vast majority of palatally impacted maxillary canines and the potentially devastating resorption of adjacent incisors.     

To what extent are impacted canines associated with root resorption of the adjacent tooth?: A systematic review with meta-analysis

Background

The authors’ aim in this systematic review was to evaluate to what extent impacted canines are associated with root resorption (RR) of the adjacent tooth by using cone-beam computed tomography.

Root resorption of upper permanent incisor caused by impacted canine. An analysis of 23 cases

Unusual root resorption of 12 central and 11 lateral upper permanent incisors in 11 patients is described. The degree of resorption ranged from loss of the apical 1/4 to almost complete loss of root structure. Excepting 1 case, permanent canines were partially or completely impacted and their crowns were in close apposition to the resorbed surfaces of the incisors. The roots of the canines were either in the process of formation or completely formed. The findings suggest that the pressure from the canine which persists in moving downward despite the lack of space to permit normal eruption could cause root resorption of adjacent incisors even in the absence of systemic factors. Of 14 extracted incisors, 10 were replaced orthodontically by the impacted canines, whereas the spaces of the extracted incisors were restored by prosthetic means in the 4 other cases. 6 incisors were preserved without any treatment and 2 with the aid of a sapphire dento-osseous anchor pin. Since the resorbed incisors were mostly free of pain, early detection by radiographic examination is essential to establish a proper diagnosis.     

Morphology of anterior teeth associated with displaced canines.

Abstract

This clinical study compared tooth dimensions of maxillary central and lateral incisors on the same side as a palatally impacted maxillary canine with those of the contralateral side with a normally erupted canine, in a group of 33 consecutively referred patients. The dimensions recorded were the mesio-distal width, labio-palatal depth, obtained from models of the four upper anterior teeth and total tooth length obtained from an orthopantomographic radiograph. The results showed that there was no statistically significant evidence to support the view that palatally impacted maxillary canines are associated with diminutive maxillary lateral incisors.