Tooth resorption associated with the eruption of maxillary canines

Six cases of root resorption of lateral incisors, associated with buccally displaced maxillary canines are presented. In each case, the clinical appearance is described followed by a discussion drawing attention to the possible common features and the importance of a detailed radiographic investigation.     

Clinical conditions for eruption of maxillary canines and mandibular premolars associated with dentigerous cysts.

The aim of this study was to investigate the eruption of teeth associated with dentigerous cysts in the mandibular premolar and maxillary canine regions in preadolescents. Fifty-eight cyst-associated teeth, including 47 mandibular premolars and 11 maxillary canines, were examined retrospectively by using normalized panoramic radiographs and histological materials. The subjects were divided into 2 groups: the erupted group, in which the teeth had erupted successfully after marsupialization, and the nonerupted group, in which the teeth had undergone orthodontic traction or cystectomy with removal of the cyst-associated tooth. Eighty-one percent of the mandibular premolars and 36% of the maxillary canines in the cysts erupted successfully about 100 days after marsupialization without traction. The eruption of a mandibular premolar was significantly related to a shallow position in the alveolar bone, shallow angulation of the tooth, and young age of the patient but not to cyst size and dental space for the eruption. The eruption of the maxillary canine was significantly related to the small size of the cyst and the patient's age. The cyst walls of the erupted group showed severe inflammatory cellular infiltration. These findings present a treatment guideline for dentigerous cysts associated with mandibular premolars and maxillary canines in preadolescents.     

上颌埋伏尖牙非手术助萌的正畸治疗

[摘要] 目的 探讨上颌埋伏尖牙非手术助萌正畸治疗的适应证及其临床效果。方法 选取10～15岁上颌埋伏尖牙患者20例,应用螺旋CT三维重建技术对其进行诊断,明确埋伏尖牙颌骨内位置、方向及牙根发育情况,选取适合病例12例通过正畸手段为埋伏尖牙开辟间隙,等待其自行萌出;8例采用外科翻瓣导萌术牵引导萌。结果 12例非手术助萌患者,正畸拓展足够间隙后经3～10个月上颌埋伏尖牙均自行萌出至正常位置,牙周附着健康;8例外科手术导萌患者,上颌埋伏尖牙正畸牵引到位后均有不同程度的牙周附着丧失,影响龈缘美观。结论采用螺旋CT三维重建技术可以立体直观的提供埋伏尖牙的信息,为临床医师明确诊断及制定治疗方案提供依据,减少手术适应证,使用非手术助萌的方法可使上颌埋伏尖牙自行萌出,避免手术创伤痛苦,萌出后牙周附着好。     

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.     

Dentoskeletal characteristics in patients with palatally and buccally displaced maxillary permanent canines

The aim of this retrospective study was to analyse dentoskeletal characteristics in patients with eruption disturbances of the maxillary permanent canines. Pre-treatment panoramic radiographs and lateral cephalograms of 636 consecutive orthodontic patients were assessed. The control group included 456 patients with physiologically erupted maxillary permanent canines (261 females and 195 males, mean age 12.6 and 12.4 years, respectively). The other groups comprised 144 subjects with palatally displaced canines (PDCs) (92 females and 52 males, mean age 14.2 and 14.7 years, respectively) and 36 patients with buccally displaced canines (BDCs) (16 females and 20 males, mean age 12.4 and 12.8 years, respectively). The selected dentoskeletal parameters were compared with classic cephalometric norms using the method of analysis of variance, chi-square, and Fisher's exact tests. The PDC patients showed a significantly more prognathic maxilla, a significantly more frequent occurrence of skeletal class I, retroinclination of maxillary central incisors, hypodivergent relationship, and mandibular anteriorotation and less frequent posteriorotation. A significantly more frequent retrognathic maxilla and skeletal class III and less frequent retroinclination of the maxillary central incisors were found in the BDC patients. The results of this study indicate the existence of different facial morphology and more likely also etiopathogenesis of eruption disturbances of the canines in the PDC and BDC patients.     

上颌恒尖牙萌出障碍的研究进展

上颌恒尖牙(permanent maxillary canines)位于双侧口角,在人类的咀嚼、发音及美观中起着重要作用。上颌恒尖牙阻生和异位萌出需要外科开窗助萌以及复杂的正畸治疗,花费患者大量的时间和费用。该文就上颌恒尖牙的萌出过程及其阻碍因素作一综述,为尖牙阻生或异位萌出的病因研究、早期预测及阻断性治疗提供参考。     

Association between ectopic eruption of maxillary canines and first molars

The purpose of this study was to elucidate a possible association between ectopic first molar eruption causing root resorption on the distal root of the primary maxillary second molar, and ectopic canine eruption causing root resorption on the permanent maxillary incisors.The subjects consisted of 30 patients, 22 females and eight males in the age range 8.3-15.0 years in whom root resorption of the permanent maxillary lateral and/or central incisor caused by the erupting permanent canine was diagnosed, and clinical and/or radiographic information concerning maxillary first molar eruption existed.It was found that of the 30 patients, seven (23.3 per cent) also had pathological root resorption of the second primary molar caused by ectopic molar eruption.It is suggested that patients with ectopic maxillary first molar eruption leading to pathological root resorption of the maxillary second primary molar are followed closely during the period of premolar and canine eruption, as the ectopic first molar could be an early warning of an increased risk of ectopic canine eruption leading to root resorption of the maxillary permanent incisors.     

Adequacy of maxillary dental arch width in patients with palatally displaced canines.

This study investigates maxillary dental arch width in subjects with palatally displaced canines. Pretreatment dental casts of orthodontic patients with one or both maxillary canines palatally displaced (n = 31; male, 10; female, 21) were collected. This sample was matched according to sex and age with pretreatment dental casts from unaffected orthodontic patients. Arch widths were recorded between the maxillary first premolars and between the maxillary first molars. Interpremolar arch width and intermolar arch width comparisons between the sample with palatally displaced canines and the reference sample showed no statistically significant differences in their means, thus indicating that there was no statistically significant difference in the anterior and posterior arch width between the affected subjects and the control subjects. Thus, affected patients exhibit adequacy of maxillary dental arch width. This evidence refutes earlier conclusions that deficiency in maxillary transverse arch width is an associated contributing factor in the genesis of the anomaly of palatally displaced canines. Clinically, adequacy of dental arch width helps explain the "nonextraction" diagnostic appearance of most of these patients when they present for treatment.     

The use of panoramic radiographs to localize displaced maxillary canines.

OBJECTIVE: The purpose of this investigation was to develop a reliable method of diagnosing the position of a displaced maxillary canine on the basis of a single panoramic radiograph. STUDY DESIGN: A total of 115 panoramic radiographs depicting 164 displaced maxillary canines were evaluated. The ratio of the width of the displaced canine to the width of the homolateral central incisor (the canine-incisor index) and the ratio of the width of the displaced canine to the width of the contralateral canine (the canine-canine index) were calculated. The height of the crown of each displaced canine was classified in the vertical plane, relative to the adjacent incisor, as apical, middle, or coronal. RESULTS: There was an overlap in the canine-incisor index ranges of the buccal (0.94-1. 45) and palatal (1.15-1.29) canines in the apical zone. In the middle and coronal zones, a clear difference could be seen between the canine-incisor indices of labially (0.78-1.11) and palatally (1.15-1.7) located canines. A cut-off point of 1.15 was determined. CONCLUSIONS: Provided that vertical restriction and the canine-incisor index are used, the panoramic radiograph can serve as a useful indicator for determining the position of an unerupted maxillary canine.     

影响上颌埋伏尖牙导萌疗程的因素分析

目的:分析影响上颌埋伏尖牙导萌的因素,以利于导萌疗程预测。方法:以46例上颌埋伏尖牙已成功导萌的患者为研究对象,分析其导萌疗程与以下因素的关系:年龄(岁)、上颌埋伏尖牙牙尖至平面的距离(d)、牙长轴与平面的角度(α)、牙尖近远中向位置(ZB)和埋伏尖牙与侧切牙长轴角度(β)。结果:上颌埋伏尖牙导萌疗程与患者年龄及d成正相关,牙尖越靠近中线,导萌疗程越长;与α成负相关。结论:上颌埋伏尖牙的位置和患者年龄可为预测导萌疗程提供重要参考依据。     

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.