Success rate and duration of orthodontic treatment for adult patients with palatally impacted maxillary canines.

This study was undertaken to examine the success rate and the length of orthodontic treatment of impacted maxillary canines in adult patients. A sample of 19 adults (mean age, 28.8 +/- 8.6 years; range, 20-47 years), who had been treated for a total of 23 impacted maxillary canines, was compared with a younger control group (mean age, 13.7 +/- 1.3 years; range, 12-16 years). The control subjects were chosen for a similar degree of impaction difficulty by carefully matching the positions of the impacted canines in the 3 planes of space. The success rate among the adults was 69.5% compared with 100% among the younger controls. The lower success rate was due to 5 canines that had failed to erupt and 2 canines that had been partially extruded but could not be aligned in the arch. The duration of treating the overall malocclusion of the adults and young subjects did not materially differ. However, the adults showed significant increases in the duration and number of treatment visits required for resolving the canine impaction, in both the simpler and the more difficult cases. When further divided by age, all the failed canines were found in the older (over 30) adult subgroup. It was concluded that the prognosis for successful orthodontic resolution of an impacted canine in an adult is lower than that in a younger patient and that the prognosis worsens with age. Furthermore, when such treatment is undertaken, its successful completion should be expected to take considerably longer.     

Orthodontic treatment of palatally impacted maxillary canines

The aim of this study was to determine the feasibility of treating children with impacted maxillary canines by orthodontic treatment alone. The subjects were 28 children (mean age: 13.5 years, range 11.4-16.1 years) with between them 32 palatally impacted canines. The overlying primary canines were extracted between 0 and 42 months before the start of appliance treatment to open space in the arches for the impacted teeth. No other surgical procedures were carried out prior to the start of appliance treatment. Appliance treatment was deferred for at least six months if an impacted canine was the main reason for treatment, otherwise treatment was commenced according to the needs of the patient. In 94% of the cases, the severity of impaction lessened following extraction of the overlying primary canines and orthodontic treatment. The deepest impactions tended to occur in the oldest children. The majority (75%) of the canines emerged following orthodontic treatment to create space for them in the arch; the remainder were surgically exposed. Appliance treatment tended to take longer in children with the deepest impactions. It is concluded that fixed appliance treatment to create space for a palatally impacted canine is an effective management option for children with impacted maxillary canines.     

Predictable method to deliver physiologic force for extrusion of palatally impacted maxillary canines

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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。     

Orthodontic treatment acceleration with corticotomy-assisted exposure of palatally impacted canines

OBJECTIVE: To evaluate the effectiveness of a new surgical technique in the treatment of palatally impacted canines. MATERIALS AND METHODS: Six consecutive patients presenting with bilaterally impacted canines were compared. One canine was surgically exposed using a conventional surgical technique while the contralateral canine was exposed using a corticotomy-assisted technique. RESULTS: After tooth movement was completed, statistical comparisons of the two methods revealed a reduction of treatment time of 28-33% for the corticotomy-assisted canines. No significant differences were observed in final periodontal condition between the canines exposed by these two methods. CONCLUSION: This preliminary study supports the concept that a corticotomy-assisted surgical technique helps reduce orthodontic treatment time for palatally impacted canines.     

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.     

上颌腭侧阻生尖牙非手术与手术助萌的比较研究

目的探讨上颌腭侧阻生尖牙通过正畸开辟间隙等非手术助萌的适应证、矫治时间及其临床效果。方法选取9例患者的12颗上颌腭侧阻生尖牙为研究对象,通过曲面全景及头颅侧位片判断阻生尖牙在颌骨内的位置、牙齿的发育阶段及患者骨成熟阶段,通过正畸治疗配合头帽口外弓为阻生尖牙开辟间隙,定期拍摄曲面全景片观察阻生尖牙的萌出潜力。结果 7颗阻生尖牙自动萌出,3颗阻生尖牙采取外科开窗联合正畸牵引治疗,2颗阻生尖牙选择外科拔除。结论正畸开辟间隙后阻生尖牙成功萌出的主要因素可以概括为:萌出路径无干扰、骨成熟早期,根尖孔未闭合,而骨发育阶段比牙发育阶段更有指导意义。     

Interceptive approach to treatment of impacted maxillary canines

Impaction of maxillary canines can be prevented by early intervention in the mixed dentition phase after the correct diagnosis of malocclusion, reducing the complexity of the treatment. This article reports the case of a 10-year-old patient who possessed impacted maxillary canines and, after early extraction of primary canines, had reestablished favorable permanent successors' eruption axis. This 5-year radiographic follow-up study with panoramic radiography shows that this can be used in practice and that an effective control strategy ensures the accuracy in the inclination of the impacted canines. Treatment success is related to early diagnosis and strategic interceptive treatment choice.     

Space conditions and dental and occlusal features in patients with palatally impacted maxillary canines: an aetiological study

The aetiology of palatal canine impaction is unclear. The aim of this research was to investigate the occlusal features that could contribute to the aetiology of palatal maxillary canine impaction. The material consisted of the pre-treatment dental casts of 34 patients (27 female and seven male) with unilateral palatal canine impaction (impaction group). The average age of this group was 17.7 years (+/- 4.6). These were matched according to age, gender and type of malocclusion with a comparison group of pre-treatment dental casts from unaffected orthodontic patients. From the dental casts the following parameters were obtained: (1) dentoalveolar arch relationship, (2) missing or anomalous teeth, (3) the mesiodistal width of each maxillary tooth, (4) the upper arch perimeter, (5) the maxillary inter-premolar and inter-molar widths. The arch length-tooth size discrepancy was only calculated for subjects with no missing teeth. Palatal canine impaction occurred most frequently in subjects with a Class II division 2 malocclusion. There was an association between palatal canine impaction and anomalous lateral incisors (P = 0.01). The transverse arch dimension was significantly wider in the impaction group than in the comparison group (P < 0.01). There was no statistically significant difference in the mesiodistal width of maxillary teeth or in the arch length-tooth size discrepancy between the palatal canine impaction group and their matched comparisons (P > 0.05). These results suggest that the presence of an 'excess palatal width' and anomalous lateral incisor may contribute to the aetiology of palatal canine impaction.     

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.     

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.     

Therapeutic strategies for impacted maxillary canines

A disturbance in the normal eruption pattern of one or both of the maxillary canines is found in 1% to 2% of the teenagers aged ten to thirteen years. Frequently, dentists refer these patients to orthodontists who, in turn, seek the assistance of an oral and maxillofacial surgeon to retrieve the impacted canine, either by exposure alone or by exposure and attachment of a bracket and ligature for orthodontic extrusion. A common request in this procedure is the extraction of the persistent upper deciduous canine and/or, in case of an Angle Class II molar relationship, extraction of the upper first premolar. It has been shown, however, that on average 15% of these exposed or ligated maxillary canines fail to erupt. Therefore, one should be reluctant to extract the deciduous canine or the permanent first premolar before it is clear that the impacted maxillary canine will indeed erupt after surgical exposure and/or placing of a bracket and ligature for orthodontic extrusion.     

Forced-eruption time for palatally impacted canines treated with and without ostectomy-decortication technique

Objectives:To compare forced-eruption times for palatally impacted canines treated with and without the ostectomy-decortication technique and to assess the influence of palatally impacted canine pretreatment position and angle on forced-eruption time.Materials and Methods:The sample was composed of 118 patient-subjects with 151 palatally impacted canines treated with the ostectomy-decortication technique (n = 72) and without (n = 79). The orthopantomogram radiographs (OPGs) were analyzed for palatally impacted canine angle and horizontal and vertical position. Recovery time was measured from the start of forced eruption until the canine was within ±1 mm of final dental arch position.Results:The time of forced canine eruption with ostectomy-decortication technique was significantly shorter than without (6.6 vs 21.0 months). Pretreatment canine position significantly increased forced-eruption time in the ostectomy-decortication group but not in the control sample.Conclusions:Forced-eruption time of palatally impacted canines using the ostectomy-decortication technique was 3.2 times more rapid than without. Forced-eruption time increased significantly as a function of pretreatment palatally impacted canine position severity in the ostectomy-decortication group but not in the control.