Reliability of a method for the localization of displaced maxillary canines using a single panoramic radiograph

The present study was initiated to determine the validity and reproducibility of a method previously reported for localization of displaced maxillary canines by panoramic radiographs. Eleven dental specialists (five orthodontists, five surgeons, and one radiologist) and five (final year) dental students were asked to interpret initial panoramic radiographs of 20 patients with 26 unerupted canines. The method contends that, provided that the radiographic image of the unerupted canines superimposes on the root of the lateral incisor at a height coronal to the apical third, a ratio between the widest mesiodistal dimension of the affected canine and the homolateral central incisor [Canine-Incisor Index (CII)] of more than 1.15 indicates palatal displacement. Among the observers, the measurement error was small, insufficient to cause overlap between the ranges of values for the CII of buccal and palatal canines. Inter-observer reproducibility was high. Without exception, all observers correctly diagnosed the location of each of the impacted canines. The CII cut-off point of 1.15, which was arbitrarily chosen in the previous work, was shown to be valid to differentiate buccal from palatal displacement. The present method is rapid, simple, accurate, and easily taught to dental students or dental specialists, with the simplest of initial instruction. While confirmations with other radiographic techniques is strongly advised before a definitive treatment is undertaken, this method has merit in providing more information than has been available from the panoramic radiograph hitherto, to satisfy the needs of an initial orthodontic consultation.     

上颌埋伏阻生尖牙与牙弓及腭部形态的相关性

埋伏阻生尖牙是临床上常见的牙齿畸形,多种因素可导致尖牙骨内移位形成颊、腭侧阻生.近年来,有研究发现埋伏阻生尖牙与上牙弓及腭部形态之间有密切联系,牙弓宽度、长度、腭穹隆深度及腭面积、腭体积均可能与埋伏阻生牙相关.对上颌形态的研究有助于在临床工作中对尖牙阻生进行早期诊断和干预,减少治疗并发症.本文就埋伏阻生尖牙相关的上牙弓...     

Dental age in maxillary canine ectopia

An etiologic connection between palatally ectopic canines and small and missing teeth is well established in the literature. Additionally, it has been observed that patients with palatally ectopic canines have a delayed dental development. The present study was designed to examine the validity of this latter observation. We radiographically assessed the subjects' dental ages using criteria of tooth calcification, rather than tooth eruption pattern. A similar determination was made in relation to subjects in whom buccally ectopic canines were present. The experimental group consisted of panoramic radiographs of 55 consecutively treated patients with palatally displaced maxillary canines and of 47 consecutively treated patients with buccally displaced canines. They were compared with a control group of 57 consecutively treated patients with normally placed canines. Approximately half the subjects with palatal displacement exhibited a late-developing dentition, whereas the timing of dentition in the remaining subjects appeared to be normal. Buccal displacement was not associated with a retarded dental development, and the ranges of the dental age values were similar to those seen in the control group. The results support the idea that there are different etiologies for the occurrence of buccal versus palatal ectopia in maxillary canines. They also suggest that dentitions with a palatal canine appear to be of 2 distinct varieties, with different dental characteristics and, perhaps, different etiologies.     

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.     

Interceptive treatments (ages 6-10) of transverse deformities: posterior crossbite

By means of a review of the literature, the authors argue the case for early treatment of posterior cross bites. They outline the particularities and advantages of various therapeutic techniques including grinding down the interfering cusps of deciduous canines and palatal expansion in the mixed dentition.     

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。     

Orthodontics. Part 10: Impacted teeth

This section deals with the important issue of impacted teeth. Impacted canines in Class I uncrowded cases can be improved by removal of the deciduous canines. There is some evidence that this is true for both buccal and palatal impactions. Treatment of impacted canines is lengthy and potentially hazardous. Interceptive measures are effective and preferred to active treatment. Supernumerary teeth may also cause impaction of permanent incisors, their early diagnosis and appropriate treatment is essential to optimise final outcomes. If there are any doubts about impacted teeth it is better to refer too early than too late, this latter option may unnecessarily extend the length of treatment as well as the treatment required.     

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。     

Periodontal status of orthodontically treated impacted maxillary canines.

Thirty-four unilateral palatal impacted maxillary canines were brought down by orthodontic means after a radical surgical exposure. The contralateral canines which had erupted unaided served as controls during the study. Measurements of the gingival pocket depths showed that the distal pocket on the treated teeth was significantly deeper than on the control teeth. The treated canines displayed significantly more loss of periodontal support on the buccal and palatal surfaces than did the untreated teeth. Radiographically, there was more alveolar bone loss on the mesial surfaces of the corrected than on the uncorrected canines, the mean distance being 2.06 and 1.51 millimeters, respectively. The age of the patients at the start of treatment did not seem to have any profound influence on the loss of attachment, but the individual variation was considerably greater in adults.     

The palatally impacted canine: a new approach to treatment.

A method for the application of traction to misplaced maxillary canines in the palate is described. The treatment approach is from the palatal side, with initial traction applied in a lingually downward direction to prevent interference with the neighboring teeth. Emphasis is placed on the suitability of the method as an adjunct to almost any of the established techniques. In this way improving their efficiency in treating the over-all orthodontic problem.     

Localization of the unerupted maxillary canine: how to and when to.

Reasons for localizing impacted maxillary canines are outlined and methods of localization described. The favored method of radiographic localization is the parallax method (image/tube shift method). Tube shifts can be carried out in both the horizontal and the vertical planes. For a horizontal tube shift, two occlusal radiographs are recommended; for a vertical tube shift, a rotational panoramic radiograph and an occlusal radiograph are recommended. This latter combination is usually the combination of choice because the panoramic radiograph, which provides information about all the teeth in both arches, the two jaws, and the surrounding structures, is often taken as an initial radiograph and this combination only requires one additional exposure, the occlusal radiograph. To facilitate the interpretation of a vertical tube shift, the angle of the tube in the occlusal radiograph should be increased from the customary 60 degrees to 65 degrees to 70 degrees to 75 degrees. Less accurate methods of radiographic localization are to use (1) image magnification of the impacted maxillary canines and (2) image superimposition of the impacted maxillary canines on the central or lateral incisor. Reasons why periapical radiographs are not recommended to be used for a horizontal tube shift or for a vertical tube shift in combination with a panoramic radiograph are explained. Indications to suspect palatal impaction may occur in the future if the patient is less than 10 years of age, and indications to suspect impaction may have occurred if the patient is more than 10 years of age are discussed. Patient questionnaires are advocated to aid the clinician in anticipating palatal impaction, the most frequent impaction.     

Familial trends in palatal canines, anomalous lateral incisors, and related phenomena

Our previous studies have established a strong link between small, peg-shaped and missing lateral incisors, and palatally-displaced maxillary canine teeth. Since these anomalies of lateral incisor development are known to be under strong genetic control, the hypothesis was that first degree relatives of patients with palatal canines would themselves show a raised prevalence of the anomalies. The present study also investigated a possible link between palatal canines and lateness in development of the dentition, and a relative absence of crowding, both of which are phenomena that have been mentioned both by us and elsewhere as similarly linked phenomena. Results showed that anomaly of the lateral incisors was found to be four times that of the general population and that positive links with late development of the dentition and a relative absence of crowding were also seen.     

Radiographic assessment of dental anomalies in patients with ectopic maxillary canines

Background.  The aetiology of palatally and labially located ectopic maxillary canines is multifactorial. Accordingly, early prediction of this eruptional disturbance is in most cases not possible.
Aim.  The purpose of this study was to analyse dental deviations in cases with either palatal or labial ectopic canines.
Design.  Panoramic and intra-oral radiographs from 50 patients with palatally located (38 females and 12 males) and 19 patients with labially located ectopic canines (11 females and 8 males), aged 10 years, 2 months–18 years, 1 month, were analysed. Dental deviations registered were crown and root malformations, agenesis, and eruption deviations. Registrations were performed in the maxillary incisor field and in the dentition in general.
Results.  The study documented that palatally as well as labially located ectopic canines can occur in dentitions without other dental deviations. Dental deviations occurred in approximately two-thirds of all cases, more often in females and in cases with palatally located canines. More than half of the females with palatally located canines had deviations in the maxillary incisors and in the dentition in general.
Conclusion.  Dental deviations may be considered a risk factor for maxillary canine ectopia. Early identification of patients at risk and appropriate interceptive treatment may reduce ectopic eruption of maxillary canines.     

Relationship of the maxillary canines to the incisive papilla

The positioning of denture teeth in a completely edentulous patient is dependent on many factors. Anatomic landmarks are frequently valuable in complete denture fabrication. The topography of the palatal soft tissue in relationship to tooth position in dentate patients may be an aid in the placement of denture teeth. By using casts formed from irreversible hydrocolloid impressions, 50 subjects were examined to determine the orthographic distance from the posterior of the incisive papilla to a line intersecting the distal contact points of the maxillary canines. In 92% of subjects the posterior point of the incisive papilla was approximately 3 mm anterior to the line between the distal points of the canines. Neither gender, age, nor maxillary tooth arch form affected this distance.     

腭侧埋伏阻生尖牙与鞍桥的相关性研究

目的:比较腭侧埋伏阻尖牙生和尖牙正常萌出患者的蝶鞍大小,检测鞍桥和腭侧埋伏阻生尖牙之间是否存在关联。方法:选择腭侧埋伏阻生尖牙患者的头颅侧位片作为实验组,共103例,尖牙正常萌出者作为对照组,共103例。测量蝶鞍的长度、深度、直径,依据蝶鞍的钙化程度将其分为Ⅰ、Ⅱ、Ⅲ型。结果:除蝶鞍深度外,蝶鞍长度、直径两组间比较差异均有统计学意义。实验组男性的蝶鞍深度大于女性,蝶鞍长度及蝶鞍直径男女无统计学差异。而对照组男性与女性间蝶鞍的大小比较均无统计学差异。实验组鞍桥部分和完全钙化的发生率分别为41.75％和15.53％,但性别间比较差异无统计学意义;对照组鞍桥部分和完全钙化的发生率分别为8.73%和4.85％ 。实验组鞍桥发生率是对照组的8.52倍。结论:腭侧埋伏阻生尖牙患者的蝶鞍长度、直径均较对照组大,其鞍桥的发生率显著增加,但无性别差异。     

Dynamometric assessment of the mechanical resistance of porcelain veneers related to tooth preparation: a comparison between two techniques

STATEMENT OF PROBLEM: There is little agreement regarding a palatal extension of the preparation for porcelain veneers, as it represents a more invasive technique than a preparation limited to the facial surface of a tooth. PURPOSE: The purpose of this study was to detect the stress in maxillary anterior teeth restored with porcelain veneers and compare the resistance to fracture of porcelain veneers prepared using different preparation designs. MATERIAL AND METHODS: Forty-five maxillary anterior teeth were restored with porcelain veneers and divided into 9 groups as follows: Ca, canines with no preparation; Ca-Ch, canines with palatal chamfer preparation; Ca-W, canines with window preparation; LI, lateral incisors with no preparation; LI-Ch, lateral incisors with palatal chamfer preparation; LI-W, lateral incisors with window preparation; CI, central incisors with no preparation; CI-Ch, central incisors with palatal chamfer preparation; CI-W, central incisors with window preparation. Shear-flexural fracture tests were performed. The fractured specimens were subjected to scanning electron microscope (SEM) analysis. Data were statistically analyzed with univariate analysis of variance and the Tukey post hoc test for multiple comparisons (alpha=.05). RESULTS: The following mean fracture load values (N) were recorded: Ca, 395 +/- 6; Ca-Ch, 310 +/- 8; Ca-W, 322 +/- 8; LI, 309 +/- 8; LI-Ch, 242 +/- 6; LI-W, 225 +/- 8; CI, 298 +/- 8; CI-Ch, 255 +/- 8; CI-W, 221 +/- 6. The SEM analysis showed that both adhesive and cohesive fractures were primarily concentrated at the cervical region. Statistical analysis showed that both the type of tooth and the design of the preparation significantly influenced the resistance to fracture of the restored teeth (P<.001). CONCLUSION: The chamfer preparation is recommended for central incisors, whereas the window preparation showed better results for canines. Both preparations can be adopted in the restoration of lateral incisors.     

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.     

Space conditions,palatal vault height,and tooth size in patients with and without palatally displaced canines: A prospective cohort study

Objectives:To assess palatal vault height, tooth size, and dental arch dimensions in patients with unilateral and bilateral palatally displaced canines compared with a control group.Materials and Methods:A sample of 66 patients (mean age: 11.5 ± 1.0 years) with 22 unilateral palatally displaced canines (UPDCs), 22 bilateral palatally displaced canines (BPDCs), and 22 controls (C) were consecutively recruited. All three groups had dental casts that were scanned digitally using the OrthoX three-dimensional model scanner. Tooth size, palatal vault height, dental arch width, dental arch depth, dental arch length, and dental arch space were measured by the same examiner using the GOM software. Remeasurements were made in 10 randomly identified patients.Results:The palatal vault height was significantly lower in the BPDC group compared with controls. A significantly smaller mesial-distal crown width and, in general, more spacing in the maxilla were found in the UPDC and BPDC groups. No differences in arch length or arch width at the molar region were seen between the groups, while the arch length at the canine region was smaller in the UPDC and BPDC groups. However, this was observed in BPDC patients with both deciduous canines present and in most UPDC patients where the deciduous canine was present, compared with the control group, who had more permanent canines present.Conclusions:Patients with PDC had greater reduction in tooth size compared with the control group. The arch length and arch width were similar in patients with and without PDC.     

Rapid canine distalization using distraction of the periodontal ligament: a preliminary clinical validation of the original technique

The process of rapid canine distalization through the distraction of the periodontal ligament is similar to the process in the midpalatal suture during rapid palatal expansion. Rapid canine distalization can be achieved in three weeks with this technique. The aim of this research was to evaluate the effects of rapid canine distalization on dentoalveolar tissues during the rapid distalization of canine teeth with semirigid, individual tooth-borne distractors. The study was carried out on 43 canine teeth in 18 (seven male and 11 female) patients who required first premolar extractions. The mean age of the patients was 16.7 years. The second premolars and first molars were used as anchor units. Orthodontic models, cephalometric and panoramic radiographs, and standard photographs of all the patients were taken before treatment and after the consolidation period. Periapical radiographies of the canines and anchor units were obtained once a week during the distalization period. The distractors were activated 0.25 mm three times a day, and the canines were distalized efficiently an average of three weeks. The within-group differences were evaluated with the Wilcoxon test. The maxillary canines were distalized an average of 5.76 mm with 11.47 degrees distal tipping. The maxillary first molars moved mesially 0.56 mm and extruded 0.64 mm. The maxillary incisors showed 1.44 degrees of palatal tipping. The mean distal movement of the mandibular canines was 3.5 mm with 7.16 degrees distal tipping. Anchorage loss was not observed in the mandibular first molars.     

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.