Stephanie Chen DDS, MSD; Greg Huang DMD, MSD, MPH
For patients with prominent upper front teeth, the evidence suggests that an early phase of orthodontic treatment followed by full treatment is no more effective than a single comprehensive phase of orthodontic treatment.
Relatively good evidence indicates no major differences in one vs two-phase treatment.
In children with prominent front teeth, is two-phase orthodontic treatment more effective than one-phase treatment, as assessed by dental and skeletal relationships?
The authors conducted an all-language search of 4 databases from 1966 to February 2007. Inclusion criteria were: randomized and controlled clinical trials; children or adolescents (up to 16 years) receiving orthodontic treatment to correct prominent upper front teeth; active interventions of any orthodontic appliance; and control of no or delayed treatment or another active intervention. Exclusion criteria were: trials including patients with cleft lip or palate, or other craniofacial deformity/syndrome; trials recruiting less than 80% children or adolescents; and patients who had previously received surgical treatment for Class II malocclusion. Primary outcome was prominence of the upper front teeth, and secondary outcomes included the relationship between upper and lower jaws, self esteem, patient satisfaction, injury to the upper front teeth, jaw joint problems, and number of attendances required to complete treatment. The authors performed a hand search of reference lists and 7 orthodontic journals. All primary authors were contacted to obtain additional information. Two individuals independently reviewed studies for inclusion, extracted data, and assessed study quality. Meta-analysis was conducted to synthesize effect size.
The authors identified 185 titles and abstracts, of which 105 full reports were selected. Eight trials based on data from 592 patients with Class II Division 1 malocclusion were included. Of the 8 trials, four were assessed as having low risk of bias and the other four as having moderate risk of bias. Three trials compared patients who received early treatment with a functional appliance with those who were untreated. These trials demonstrated a significant difference in overjet, final ANB, and change in ANB. Two trials that compared patients who received early treatment with a headgear and those were untreated showed that headgear significantly reduced final overjet and ANB. Two trials showed no significant difference in overjet or ANB between patients who received early treatment with headgear and functional appliances. Three trials found no significant differences in overjet, final ANB or PAR score between children who had received one-phase or two-phase treatment at the end of adolescent treatment. One trial found a significant reduction in overjet and ANB for adolescents receiving 1-phase treatment with functional appliance as compared with an untreated control. Two trials found that the Twin Block appliance resulted in a small but statistically significant reduction of ANB as compared with other functional appliances. However, no significant difference in overjet was found among the different types of appliance.
Based on the available evidence, early treatment of Class II Division 1 malocclusion followed by comprehensive treatment is no more effective than a single phase of treatment in adolescence. Early treatment results showed no significant difference in effectiveness between headgear and functional appliances. The twin block appliance does not appear to have any advantage over other functional appliances in adolescents.
Source of Funding:
The Royal Liverpool and Broadgreen University Hospitals NHS Trust, UK; The university of Manchester, UK; Cochrane Oral Health Group, UK; NHS National Primary Dental Care R&D programme PCD97-303, UK.
Importance and Context:
Prominent upper front teeth is a common type of malocclusion in children. Their gingival health and psychological well-being may be adversely affected,1 and they often are more susceptible to traumatic injury.2 One- and two-phase treatments using various types of appliances can correct a Class II Division 1 malocclusion. Given the additional burden of time and money for two-phase treatment, it is important to determine how outcomes compare with a single phase of comprehensive treatment.
Strengths and Weaknesses of the Systematic Review:
The review was thorough. The authors searched 4 databases for materials in any language, also hand searched reference lists and 7 orthodontic journals. Authors were contacted to identify unpublished studies and obtain additional information. The authors stated their inclusion and exclusion criteria, and provided lists of included and excluded studies along with characteristics. Two independent reviewers assessed studies for inclusion, performed data extraction, and judged the quality of the included studies. Meta-analysis was performed with methods of synthesis and details of results reported.
Strengths and Weaknesses of the Evidence:
The conclusions are drawn from 8 randomized controlled trials involving 592 patients, 4 trials of high quality and 4 of moderate quality. The trials focused on several different aspects of comparison; in most of the comparisons, the conclusions were drawn from 2 or more trials. The findings of these studies are consistent and amenable to meta-analysis. One weakness of the evidence was the limited information on trauma to the incisors. Only 1 study provided data on this topic.
Implications for Dental Practice:
The evidence suggests there are no differences in treatment effects between one-phase and two-phase treatment for Class II Division 1 malocclusion when assessed at the end of comprehensive treatment. Therefore, either treatment may be appropriate for a particular patient. The clinician should consider treatment factors such as esthetics, trauma susceptibility, psychosocial implications, compliance, oral hygiene, and costs, as well as the preferences of patients and parents. Regarding the type of intervention, the evidence suggests that there is no significant difference between the treatment effects of headgear and functional appliances when used in early treatment.