Stability of orthodontic treatment outcomes after 1-year treatment with the eruption guidance appliance in the early mixed dentition: A follow-up study

Objectives:To investigate occlusal stability from the early mixed to the permanent dentition in children after early treatment with the eruption guidance appliance (EGA).Materials and Methods:Of 46 participants who received 1-year early EGA treatment, 35 attended a follow-up examination at age 12. Group 1 (n = 21) started their EGA treatment at mean age 7.7 years, and group 2 at 9.1 years. Following 1-year treatment, the EGA was used as a retainer. Changes in overjet, overbite, sagittal molar relationship, and anterior crowding were measured on casts obtained before EGA treatment, after EGA treatment, and at follow-up to evaluate occlusal stability.Results:Mean overjet, overbite, sagittal molar relation, and mandibular crowding improved significantly during the study period. Participants with good compliance during the retention period had significantly smaller overjet and overbite values than those with poor compliance.Conclusions:Early correction of increased overjet, overbite, and class II molar relation with the EGA is maintainable and can also be effective in the permanent dentition, provided the EGA is worn regularly as a retainer.     

PAR指数评价萌出诱导器对混合牙列中期错的矫治疗效

目的采用PAR指数研究萌出诱导器对混合牙列中期错畸形患者的矫治疗效。方法采用前瞻性队列研究设计,纳入混合牙列中期牙列轻度拥挤、安氏I类或II类患儿56例。试验组(29例)采用萌出诱导器进行矫治,直至上前牙排齐;对照组(27例)不作处理,仅随访观察。采用PAR指数评价试验组治疗前后、对照组随访前后模型数据。结果试验组患者矫治后PAR加权后总分减少率为67.49%±13.47%,对照组随访前后PAR加权后总分减少率为18.69%±12.99%。两组患者在前牙排列、磨牙关系、覆覆盖关系改善上的差异均存在明显统计学意义(P<0.05)。结论萌出诱导器可以改善混合牙列中期患者上下前牙排列,纠正磨牙关系,明显减少患儿覆盖。     

Prevalence of malocclusions in the early mixed dentition and orthodontic treatment need

Early interceptive treatment for the elimination of factors inhibiting dental arch development and mandibular and maxillary growth is applied varyingly by orthodontists, possibly because there is little scientific evidence that such interventions are of actual benefit. The aim of this study was to determine specific factors for treatment need in the early mixed dentition period in order to obtain basic data to support early intervention. The study was part of a larger survey of 8768 children aged between 6 and 17 years. From this sample, 1975 children aged between 6 and 8 years were used to estimate the prevalence of malocclusions using the Index of Orthodontic Treatment Need (IOTN) during the early mixed dentition period. The results showed that deep overbite and overjet, both more than 3.5 mm, were the most frequent discrepancies, affecting 46.2 and 37.5 per cent of patients, respectively. An anterior open bite was registered in 17.7 per cent, crossbite in 8.2 per cent, and a reverse overjet in 3.2 per cent. A tooth width to arch length discrepancy was recorded in 12 per cent of teeth in the upper arch and in 14.3 per cent in the lower arch. The proportion of children estimated using the Dental Health Component of the IOTN to have a great or very great treatment need (grades 4 and 5) was 26.2 per cent. The higher values of treatment need during the mixed dentition period may account for temporary changes in the dentition and for the discrepancy in overjet and overbite. These discrepancies will be compensated in part during mandibular growth and development of the dental arch. Nevertheless, the findings indicate the early development of progressive malocclusion symptoms which are evidenced in the IOTN and concur with the acronym 'MOCDO' hierarchy (missing, overjet, crossbite, displacement, overbite). This early formation of progressive symptoms inhibiting or disturbing mandibular or maxillary growth or the development of the normal dental arch, i.e. crossbite, reverse overjet and increased overjet with myofunctional disorders, should be treated at an early stage.     

Occurrence of malocclusion and need of orthodontic treatment in early mixed dentition

This study analyzed the occlusions of 489 children at the onset of the mixed dentition period (mean age 5.1 years, range 4.0-7.8 years). These children participate in an ongoing clinical trial that is investigating the effects of orthodontic intervention in the early mixed dentition. The aim was to report the occlusal findings at the baseline. The frequencies of mesial step, flush terminal plane, and distal step were 19.1%, 47.8%, and 33.1%, respectively. The canine relationship was Class I in 46.1%, Class II in 52.4%, and Class III in 1.5% of the sides examined. An asymmetrical canine relationship was found in 30.1% of the children, significantly more often on the right side than on the left (P <.001). Overjet ranged from -2 to +10 mm with a mean of 2.9 mm. Overbite ranged from -5 to +8 mm with a mean of 2.8 mm. Excessive (> or =4 mm) overjet was found in 26.7% and overbite in 33.8% of the children; in 15.5% of the children, both variables were 4 mm or more. Anterior crowding was detected in the maxillary arch in 11.6% and in the mandibular arch in 38.9% of the children. Girls showed mandibular crowding more often than boys (P <.01). A posterior crossbite was found in 7.5% of the children, unilaterally in 6.4% and bilaterally in 1.1%. Scissors-bite was detected in 1.1% and an anterior crossbite in 2.2% of the children. The mean maximal opening was 40.3 mm. Joint sounds were registered in 5.2% of the children. The prevalence of malocclusion was between 67.7% and 92.7%, depending on the values of unacceptable parameters used for each occlusal characteristic.     

Dentofacial changes from fan-type rapid maxillary expansion vs traditional rapid maxillary expansion in early mixed dentition: A prospective clinical trial

Objective:To test the null hypothesis that there is no difference between the effects of fan-type rapid (FRME) and rapid maxillary expansion (RME) used with an acrylic bonded expansion appliance on dentofacial structures in early occlusal stages.Materials and Methods:This was a prospective clinical trial. The FRME group had an anterior constricted maxillary width with a normal intermolar width, and the RME group had bilateral constricted maxillary width. The FRME group consisted of 20 patients (mean age, 8.96 ± 1.19 years), and the RME group consisted of 22 patients (mean age, 8.69 ± 0.66 years). Lateral and frontal cephalometric radiographs and dental casts were taken before and after expansion and 3 months after completing treatment for each patient. The data were compared using repeated-measures analysis of variance. The paired-samples t-test was used to evaluate treatment and retention effects, and the independent samples t-test was used to consider the differences between the two groups.Results:The maxilla moved downward and forward in both groups. The nasal cavity and maxillary width were expanded more in the RME group, and there were only a few relapses in this group during the retention period. There was significant labial tipping of the upper incisors in the FRME expansion group. The expansion of intercanine width was similar in both groups, but the expansion of intermolar width was significantly greater in the RME group.Conclusion:The null hypothesis was rejected. There was a difference between the effects of FRME and RME used with an acrylic bonded expansion appliance on dentofacial structures in the early occlusal stages.     

Lateral incisor root resorption and active orthodontic treatment in the early mixed dentition.

AIM: To evaluate the presence of root resorption in the lateral incisor after active orthodontic treatment in the early mixed dentition. METHODS: Twenty-six children treated at the Children's Clinic of the Schulich School of Medicine and Dentistry at the University of Western Ontario were examined radiographically for lateral incisors root resorption before and after early active treatment to align upper incisors (2 x 4 appliance). In addition, canine inclinations to the midline and to the long axis of the lateral incisor as well as the most medial position of the canine crown were measured as potential risk factors for root resorption. RESULTS: 8% (4) of the lateral incisors exhibited root resorption and the mean crown-to-root ratio of these teeth was significantly higher than that for lateral incisors not exhibiting root resorption. Similarly, mean canine inclinations to the midline and to the long axis of the lateral incisor were also significantly higher for the root resorption group. No association could be found between the most medial position of the canine crown and root resorption in the lateral incisor. CONCLUSION: This study showed that active orthodontic treatment in the early mixed dentition does not increase the risk for root resorption in the lateral incisors as long as the clinician takes into consideration canine inclinations and their potential effect on root resorption. Limitations inherent to radiographic assessment are acknowledged.     

Mandibular pendex spring appliance for use in mixed dentition

Loss of space in the mandibular arch is a common occurrence due to several different causes such as caries, trauma or iatrogenic damage. This paper describes a new TMA spring used in mixed dentition for space regaining in the mandibular arch. A clinical report is presented and the advantages of the method are discussed.     

A lip-activated appliance in early orthodontic treatment

After reviewing the modes of action and types of lip-activated appliances, three cases were reported. A mandibular lip-activated appliance was used to gain space among the incisors and mesial to the mandibular permanent first molars; a maxillary lip-activated appliance was used to correct an anterior crossbite by labial movement of the incisors; and a modified lip-activated appliance was used to expand maxillary molars buccally.     

恒牙期前牙反固定矫治前后颌面软硬组织的变化

目的研究固定矫治器矫治恒牙期前牙反病例的矫治效果。方法选择11例恒牙期前牙反的病例,应用固定矫治器进行矫治,矫治前后拍摄头颅侧位片进行头影测量,并对软硬组织变化情况进行配对t检验。结果U1-SN平均增加6.5°,L1-MP平均减小5.23°,鼻唇角平均减小4.95°,上下唇角平均减小4.45°,软硬组织侧貌得到明显改善。结论采用固定矫治器通过唇倾上前牙、舌倾下前牙可以快速解除恒牙期前牙反,固定矫治器是矫治恒牙期前牙反的有效手段。     

Short-term treatment effects produced by the Herbst appliance in the mixed dentition

This prospective clinical investigation evaluates the dentoalveolar and skeletal cephalometric changes produced by the Herbst appliance during treatment of mixed dentition patients with Class II division 1 malocclusion. Thirty individuals (15 male and 15 female individuals; initial mean age nine years 10 months) were treated with the Herbst appliance for a period of 12 months. For comparison, the records of 30 untreated Class II children (15 boys, 15 girls; initial mean age nine years eight months) were followed without treatment for a period of 12 months. The results indicated that the treatment effects produced in the mixed dentition patients were primarily dentoalveolar in nature. The mandibular incisors were tipped labially, and the maxillary incisors were retruded; a significant increase in mandibular posterior dentoalveolar height occurred, and there was a restriction in the vertical development of the maxillary molars. There was no difference in the forward growth of the maxilla between the two groups. In comparison with the controls, however, the Herbst treatment produced a modest but statistically significant increase in total mandibular length. This increase in total mandibular length, however, was less than that observed in adolescent Herbst patients in other studies.