Introduction
Class III malocclusion affects between 5% and 15% of our population. The 2 most common dilemmas surrounding Class III treatment are the timing of treatment and the type of appliance. A number of appliances have been used to correct a Class III skeletal discrepancy, but there is little evidence available on their effectiveness in the long term. Similarly, early treatment of Class III malocclusion has been practiced with increasing interest. However, there has been no solid evidence on the benefits in the long term. The aim of this systematic review was to evaluate the effectiveness of orthodontic/orthopedic methods used in the early treatment of Class III malocclusion in the short and long terms.
Methods
Several sources were used to identify all relevant studies independently of language. The Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Embase (Ovid), and MEDLINE (Ovid) were searched to June 2016. The selection criteria included randomized controlled trials (RCTs) and prospective controlled clinical trials (CCTs) of children between the ages of 7 and 12 years on early treatment with any type of orthodontic/orthopedic appliance compared with another appliance to correct Class III malocclusion or with an untreated control group. The primary outcome measure was correction of reverse overjet, and the secondary outcomes included skeletal changes, soft tissue changes, quality of life, patient compliance, adverse effect, Peer Assessment Rating score, and treatment time. The search results were screened for inclusion, and the data extracted by 2 independent authors. The data were analyzed using software (version 5.1, Review Manager; The Nordic Cochrane Centre, The Cochrane Collaboration; Copenhagen, Denmark). The mean differences with 95% confidence intervals were expressed for the continuous data. Random effects were carried out with high levels of clinical or statistical heterogeneity and fixed affects when the heterogeneity was low.
Results
Fifteen studies, 9 RCTs and 6 CCTs, were included in this review. In the RCT group, only 3 of 9 studies were assessed at low risk of bias, and the others were at high or unclear risk of bias. All 6 CCT studies were classified as high risk of bias. Three RCTs involving 141 participants looked at the comparison between protraction facemask and untreated control. The results for reverse overjet (mean difference, 2.5 mm; 95% CI, 1.21-3.79; P = 0.0001) and ANB angle (mean difference, 3.90°; 95% CI, 3.54-4.25; P <0.0001) were statistically significant favoring the facemask group. All CCTs demonstrated a statistically significant benefit in favor of the use of each appliance. However, the studies had high risk of bias.
Conclusions
There is a moderate amount of evidence to show that early treatment with a facemask results in positive improvement for both skeletal and dental effects in the short term. However, there was lack of evidence on long-term benefits. There is some evidence with regard to the chincup, tandem traction bow appliance, and removable mandibular retractor, but the studies had a high risk of bias. Further high-quality, long-term studies are required to evaluate the early treatment effects for Class III malocclusion patients.
Trial registration number: PROSPERO CRD42015024252.
Highlights
- 1.
Early facemask treatment produces skeletal and dental changes in the short term.
- 2.
Evidence on long-term benefits of early Class III treatment is lacking.
- 3.
Chincup, tandem traction, and removable retractors showed skeletal changes.
- 4.
Results should be interpreted with caution due to risk of bias in studies.
- 5.
Long-term studies of early orthopaedic treatment for Class III patients are needed.
Early treatment of Class III malocclusion has been attempted with varying success. The main advantage of early Class III malocclusion treatment is to avoid surgical intervention and thus reduce the morbidity of the surgery. The timing of early treatment is crucial for a successful outcome. Some studies have reported that treatment should be carried out in patients less than 10 years of age to enhance the orthopedic effect. In contrast, other studies have found that patient age had little influence on treatment response and outcome. Hence, there is no strong evidence to support that early treatment would be beneficial.
The main goals of early intervention are to provide a more favorable environment for growth and to improve the occlusal relationship: eg, correcting the crossbite and facial esthetics. Many orthopedic appliances have been explored including protraction facemask, chincup, FR-3 appliance of Frankel, bionator, reverse Twin-block, removable mandibular retractor, double-piece corrector, Class III elastics, and mandibular headgear to achieve this goal. Among these, the protraction facemask is favored by many to correct a retronagthic maxilla. On the other hand, the chincup is believed to retard or redirect the growth of a prognathic mandible. The previous Cochrane systematic review concluded that although there was some evidence for the effectiveness of the facemask appliance in the short term, there is no evidence that the results are maintained in the long term. Furthermore, the review included only 3 randomized controlled trials (RCTs). When there are not many high-quality RCTs in the literature, it is appropriate to look at prospective controlled clinical trials (CCTs). Additionally, further randomized studies have been published since the review. Hence, this systematic review is to update the Cochrane review and also to include prospective CCTs to evaluate the evidence base for Class III early treatment.
The aim of this systematic review was to evaluate the effectiveness of orthodontic methods used in the early treatment of Class III malocclusion in the short and long terms.
Material and methods
Protocol and registration
This systematic review protocol was registered under the PROSPERO register with the number CRD42015024252 ( www.crd.york.ac.uk/prospero ).
Eligibility criteria
The criteria for considering studies for this review (PICO) were the following: (1) types of studies: RCTs and prospective CCTs; (2) participants: studies of subjects with Class III malocclusion between 7 and 12 years of age; (3) intervention: orthodontic treatment with a removable or fixed orthodontic/orthopedic appliance for early correction of Class III malocclusion; (4) comparison: no treatment, delayed treatment, or intervention with the same appliance with different forces, different mechanics, or a different appliance; and (5) primary outcome: correction of reverse overjet (measured in millimeters or by other index of malocclusion) with the measurements based on study models, or cephalometric or clinical assessment.
Secondary outcomes were skeletal changes, soft tissue changes, quality of life, patient compliance, adverse effects, Peer Assessment Rating score, and treatment time.
Information sources, search strategy, and study selection
Several sources were used to identify all relevant studies independently of language. The Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Embase, and MEDLINE (Ovid) were searched to April 2016. To identify relevant records, 3 basic sets of terms were used. These included those that identified records related to early Class III malocclusion treatment, records related to intervention involved, and records related to outcome. Details of the MEDLINE search are provided in Table I . Hand searching was carried out for the journals that were identified on the Cochrane Oral Health Group Web site ( http://ohg.cochrane.org ). Articles not in English from the search were translated. References in the full-text articles selected were scanned for relevant studies. Unpublished studies were searched on ClinicalTrials.gov .
| #1 Malocclusion-Angle-Class-III (ME) |
| #2 (Class III AND (Angle OR bite)) |
| #3 Orthodontic-Appliances-Functional (ME) |
| #4 Facemask OR chin cup |
| #5 ((Extraoral OR extra oral OR extra-oral) AND appliance*) |
| #6 reversehead gear OR reverse headgear |
| #7 growth modif* AND maxilla* |
| #8 (early AND (treatment OR therapy)) AND orthodontic* |
| #9 ((orthopedic* OR orthopaedic*) AND (orthodontic* OR facial)) |
| #10 #1 OR #2 AND #3 OR #4 OR #5 OR #6 AND #7 OR #8 OR #9 |
| #11 Randomised controlled trial.pt. |
| #12 Controlled clinical trial.pt. |
| #13 Randomised.ab. |
| #14 Clinical trials as topic.sh. |
| #15 Randomly.ab |
| #16 #11 OR #12 OR #13 OR #14 OR #15 |
| #17 #10 AND #16 |
Articles and abstracts from the search were examined to exclude irrelevant studies. The article selection process was carried out independently by both authors. All doubts and disagreements were resolved after discussion.
Full texts of the potentially eligible studies were retrieved and examined carefully for compliance with the inclusion and exclusion criteria independently by both authors. All disagreements were resolved after discussion.
Data items and collection
A customized data collection form was created and used to gather information from the selected studies. This information included authors, year of publication, details of the trial, details of the interventions, characteristics of participants, duration of treatment, and outcome measures. The data extraction was performed by both authors independently and in duplication. An attempt to contact the authors was made for any missing information.
Risk of bias and quality assessment in the studies
The risk of bias for the RCTs was evaluated using the Cochrane Collaboration’s tool for assessing the risk of bias, as described in the Cochrane Handbook for the Systemic Reviews of Interventions . For the CCTs, the quality assessment was adopted from the checklist described by Downs and Black. We pilot tested a subset of our studies with the Downs and Black and the Newcastle-Ottawa scales. Although both have been widely used for quality assessment, we found the former to be a more comprehensive asessment with a 27-point scale.
Summary measures, approach to synthesis and analysis
The data were grouped and classified according to the study methodology into 2 categories: RCT and CCT.
The collected data were analyzed using Review Manager software (version 5.1; The Nordic Cochrane Centre, The Cochrane Collaboration; Copenhagen, Denmark). Risk ratios with 95% confidence intervals (95% CI) were shown for dichotomous data and mean differences with 95% CI for continuous data.
Data collection was completed without missing data from the eligible studies during the review. If there were any missing data, an attempt was made to contact the original author.
Clinical heterogeneity was assessed by examining the participant types, interventions, and outcomes. Statistical heterogeneity among the trials was assessed by chi-square test where a P value of <0.1 was considered as significant heterogeneity. The I 2 test was also carried out. The studies with more than 50% I 2 were assessed as having significant heterogeneity. Random effects were carried out with high levels of clinical or statistical heterogeneity, and fixed affects when the heterogeneity was low.
Results
Study selection and characteristics
A total of 2417 records were identified from the initial search. A further search was carried out in April 2016. From the records that were identified, 26 full-text articles were retrieved for further evaluation ( Fig 1 ). Eleven articles were subsequently excluded with reasons for exclusion shown in Table II . A total of 15 articles—9 RCTs and 6 CCTs —were included in the final analysis.
| Author/year | Reason of exclusion |
|---|---|
| Sheera et al (2012) | Retrospective comparative study |
| Kidner et al (2003) | Case series |
| Liu et al (2011) | Studies included in systematic review were prospective cohort |
| Kurt et al (2011) | Did not fulfill inclusion criteria |
| Minami-Sugaya et al (2012) | Studies included adult sample |
| Solano-Mendoza et al (2012) | Literature review that included retrospective studies |
| Arun and Erverdi (1994) | Did not fulfill inclusion criteria |
| Saleh et al (2013) | Did not fulfill inclusion criteria |
| Lione et al (2015) | Did not fulfill inclusion criteria |
| Ngan et al (2015) | Retrospective comparative study |
The characteristics of the included studies are shown in Tables III and IV .
| Method | Participants | Age | Inclusion criteria | Exclusion criteria | Setting | Interventions | Outcomes |
|---|---|---|---|---|---|---|---|
| Abdelnaby and Nassar 25 (2010) | |||||||
| Parallel group RCT | 50 randomized (26 boys, 24 girls) Groups 1 and 2 were intervention groups; group 3 was control group Group 1: n=20 Group 2: n=20 Group 3: n=10 |
Group 1: 9.6 years Group 2: 10.1 years Group 3: 9.2 years |
1. Patients with skeletal Class III (ANB<1°) 2. Mandibular prognathism (SNB >80°) 3. Anterior crossbite |
Not reported | Patients recruited from the Faculty of Dentistry, Mansoura University, Mansoura, Egypt | Comparison between chincup and control Patients divided into 3 groups Intervention groups: Group 1: treated with chincup and occlusal bite plane using 600 g of force per side Group 2: treated with a chincup and occlusal bite plane using 300 g of force per side Control group: Group 3: no treatment provided |
Skeletal changes: ANB All measurements taken before treatment and after 1 year |
| Atalay and Tortop 6 (2010) | |||||||
| Parallel group RCT | 45 randomized (26 boys, 19 girls) Patients divided into treatment and control groups Groups 1 and 2 were intervention groups, group 3 was control group Group 1: 15 patients Group 2: 15 patients Group 3: 15 patients |
Group 1: 8.18 years Group 2: 11.75 years Group 3: 7.90 years |
1. Skeletal Class III (ANB < 0°), due to maxillary retrusion or a combination of maxillary retrusion and mandibular protrusion 2. Angle Class III malocclusion with anterior crossbite. 3. Optimum SN/GoGn angle (between 26° and 38°) 4. Fully erupted maxillary incisors 5. No congenitally missing teeth or congenital syndromes such as a cleft lip/palate |
1. Congenitally missing teeth or congenital syndromes 2. Previous orthodontic treatment |
Patients recruited from Gazi University, Turkey | Comparison between modified tandem traction bow appliance and untreated group Intervention: Group 1: early treatment group treated with modified tandem traction bow appliance Group 2: late treatment group treated with modified tandem traction bow appliance Control: Group 3: observation without treatment for 8 months |
1. Dental changes: overjet 2. Skeletal changes: ANB All measurements taken before and after treatment |
| Keles et al 26 (2002) | |||||||
| Parallel group RCT | 20 randomized (10 boys, 10 girls) Group 1: 9 patients Group 2: 11 patients |
Group 1: 8.58 years Group 2: 8.51 years |
1. Healthy patients without any hormonal or growth discrepancy 2. Anterior crossbite with Class III molar relationship 3. True Class III patients (pseudo or functional Class III patients excluded) 4. Class III patients with maxillary retrognathism were selected for treatment. |
1. Pseudo or functional Class III | Patients recruited from Marmara University, Istanbul | Comparison between Nanda facemask and conventional facemask Group 1: Conventional facemask. Force was applied intraorally from canine region in a forward and downward direction at 30° angle to occlusal plane Group 2: Modified protraction headgear. Force was applied extraorally 20 mm above the maxillary occlusal plane In both groups a unilateral 500 g force was applied; patients were instructed to wear the facemask for 16 h/d for the first 3 months and 12 h/d for the next 3 months |
Skeletal changes: ANB All measurements were taken before and after treatment on lateral cephalograms |
| Mandall et al 28,29 (2010, 2013) | |||||||
| Parallel group RCT | 73 randomized (34 boys, 39 girls) Group 1: 35 patients Group 2: 38 patients |
Group 1: 8.7 years Group 2: 9.0 years |
1. Age 7 -9 years old at registration 2. Three or 4 incisors in crossbite in intercuspal position 3. Clinical assessment of Class III skeletal problem |
1. Nonwhite origin 2. Cleft lip/ palate or craniofacial syndrome 3. Maxillo-mandibular plane angle >35° or lower face height >70 mm 4. Previous history of TMJ signs or symptoms 5. Lack of consent |
Patients recruited through UK orthodontic departments at 5 district general hospitals and 3 university hospitals | Comparison between facemask and untreated group Intervention Group 1: facemask Control: Group 2: untreated patients followed for 15 months. Initial and post-15-month records were taken |
1. Skeletal changes: ANB 2. Reverse overjet 3. Self-esteem (Piers Harris) and OASIS scores 4. TMJ problem 5. PAR score |
| Vaughn et al 27 (2005) | |||||||
| Parallel group RCT | 46 randomized (24 boys, 22 girls) Patients divided into 2 groups: intervention and control. Intervention group subdivided into 2 subgroups: expansion and nonexpansion Group 1: 15 patients Group 2: 14 patients Group 3: 17 patients |
Group 1: 7.83 years Group 2: 8.10 years Group 3: 6.62 years |
Zero or negative overjet on 2 or more incisors and Class III molar relationship with mesiobuccal cusp of maxillary permanent first molar distal to buccal groove of mandibular permanent first molar, or mesial step terminal plane relationship of 3.0 mm or more if deciduous molars were present (measured clinically) When clinical or dental criteria were borderline, cephalometric criteria of ANB angle of 0° or less, Wits analysis of 3 mm or more, and nasion perpendicular to A-point of 2 mm or less were used |
Any craniofacial anomaly, psychosocial impairment, or skeletal open bite | University hospitals in United States | Comparison between facemask and observation group Intervention: Group 1: Expansion group. Palatal expansion with facemask therapy Group 2: Nonexpansion group. Passive palatal appliances with facemask therapy Control: Group 3: Untreated patients followed up 1 year. Initial and after-1-year records were taken |
Skeletal changes: ANB |
| Xu and Lin 24 (2001) | |||||||
| Parallel group RCT | 60 randomized (27 boys, 33 girls); 20 patients later excluded Group 1: 20 patients Group 2: 20 patients |
Mean age: 9.3 years | Skeletal anterior crossbite and skeletal Class III | Dental or functional Class III | Patients were recruited from hospital in Beijing, China | Comparison between facemask and untreated group Intervention: Group 1: facemask Control: Group 2: observation only |
Skeletal changes: ANB |
| Showkatbakhsh et al 23 (2013) | |||||||
| Parallel group RCT | 50 randomized (24 boys, 26 females) Group 1: 24 patients Group 2: 23 patients |
Group 1: 9 years Group 2: 9.1 years |
1. SNA 80°, SNB 80°, ANB 0° 2. No syndromic or medically compromised patients 3. No previous surgical intervention 4. No other appliances before or during functional treatment 5. No skeletal asymmetry 6. Class III molar relationship 7. Prepubertal (CS1, CS2, and CS3) according to recently improved CVM |
Department of Orthodontics, SB University of Medical Sciences Dental School, Tehran, Iran | Comparison between facemask and tongue plate group Intervention: Group 1: facemask Group 2: tongue plate Active treatment times 18 mo (SD 3) for facemask and 16 mo (SD 2) for tongue plate |
1. Skeletal changes: ANB | |
| Saleh et al 22 (2013) | |||||||
| Parallel group RCT | 67 randomized (32 boys, 35 girls) Group 1: 33 patients Group 2: 34 patients |
Group 1: 7.5 years Group 2: 7.3 years |
1. Age 5-9 years at assessment with permanent first molars erupted 2. Class III molar relationship 3. Anterior crossbite on 2 or more incisors with or without mandibular displacement or closure 4. Clinical assessment of skeletal Class III relationship 5. No cleft lip/palate or other craniofacial syndromes 6. No or minimal facial asymmetry 7. No previous orthodontic treatment 8. Syrian ancestry |
Department of Orthodontics, University of Al-Baath Dental School, Hamah, Syria | Comparison between removable mandibular retractor and untreated control Intervention: Group 1: removable mandibular retractor Control: Group 2: untreated control Treatment times for both removable mandibular retractor groups, 14.5 mo (SD 0.1) |
1. Skeletal changes: A and B points (linear measurement) | |
| Liu et al 21 (2015) | |||||||
| Parallel group RCT* | 43 randomized (20 boys, 23 girls) Groups 1 and 2 were intervention groups Group 1: 21 patients Group 2: 22 patients |
Group 1: 9.8 years Group 2: 10.1 years |
1. Age 7-13 years before treatment with midface soft tissue deficiency 2. Fully erupted maxillary first molars, Class III malocclusion, and anterior crossbite 3. ANB less than 0°, Wits appraisal less than -2 mm (corrected cephalometric tracing technique applied for patients with functional shift), and distance from Point A to nasion perpendicular less than 0 mm |
1. Previous orthodontic treatment 2. Other craniofacial anomalies, such as cleft lip and palate 3. Maxillary dentition unsuitable to bond hyrax expander |
Patients were recruited from the Department of Orthodontics, Peking University, Beijing, China | Comparison between facemask protraction combined with alternating rapid palatal expansion and constriction (RPE/C) vs rapid palatal expansion (RPE) alone Patients divided into 2 groups Group 1: treated with RME for 1 week followed by facemask maxillary protraction, delivering force of 400-500 g per side Group 2: treated with RME/C for 7 weeks (7 days expansion, 7 days constriction) followed by facemask maxillary protraction, delivering force of 400-500 g per side |
Skeletal changes All measurement taken before treatment and when positive overjet with Class I or Class II molars were achieved |
| Method | Participants | Age | Inclusion criteria | Exclusion criteria | Setting | Interventions | Outcomes |
|---|---|---|---|---|---|---|---|
| Barrett et al 30 (2010) | |||||||
| CCT Note: Sample size calculation not described Groups not balanced for sex and age Inclusion and exclusion criteria were unclear Patients were not treated equally: 12 of 26 were treated with quad helix |
46 patients (17 boys, 29 girls) included Treatment group: 26 patients Control group: 20 patients |
Treatment group: 8.5 years Control group: 7.3 years |
Occlusal signs of Class III malocclusion with Wits appraisal of –2 mm or more | Patients recruited from hospitals in Ann Arbor, Mich, and Florence, Italy | Comparison between light force chincup and control group Intervention: light force chincup Control: observation only Posttreatment cephalograms were taken on average 2.6 years later |
Dental changes: reverse overjet Skeletal changes: ANB |
|
| Cozza et al 32 (2010) | |||||||
| CCT Note: Sample size calculation was adequate: 85% Groups were not well balanced for sex and age Exclusion criteria were not described P values not provided |
34 patients (16 boys, 18 girls) included Treatment group: 22 patients Control group: 12 patients |
Treatment group: 8.9 years Control group: 7.6 years |
1. Class III malocclusion in the mixed dentition characterized by Wits appraisal of –2 mm or less, anterior crossbite or incisor end-to-end relationship, and Class III molar relationship 2. No permanent teeth were congenitally missing or extracted before or during treatment 3. No transverse discrepancy between the dental arches |
Patients recruited from Department of Orthodontics at the University of Rome, Rome, Italy | Comparison between facial mask and bite-block appliance and control group Intervention: Facial mask and bite-block appliance Lateral cephalograms were taken at beginning and end of treatment Control: observation only Treated sample was collected prospectively; control sample was collected retrospectively |
Dental changes: reverse overjet Skeletal changes: ANB |
|
| Cozza et al 33 (2004) | |||||||
| CCT Note: Sample size calculation not described Statistical analysis incomplete |
54 patients (31 boys, 23 girls) included Treatment group: 30 patients Control group: 24 patients |
Treatment group: 5.85 years Control group: 5.9 years |
1. Skeletal Class III relationship caused by maxillary retronagthism without other craniofacial anomalies or history of orthodontic treatment | 1. Craniofacial anomalies 2. History of orthodontic treatment |
Patients recruited from university hospital and private practice in Rome, Italy | Comparison between Delaire facemask and Bionator III appliance and control group Intervention: Delaire facemask and Bionator III Lateral cephalogram obtained before treatment, after facemask removal, and at end of retention Control: observation only Three series of cephalometric registrations with 1-year interval |
Skeletal changes: ANB |
| Kajiyama et al 33 (2000) | |||||||
| CCT Note: Sample size calculation not described |
54 patients (21 boys, 33 girls) included Treatment group: 29 patients Control group: 25 patients |
Treatment group: 8 y 7 mo Control group: 8 y 1 mo |
1. Anterior crossbite (negative overjet) 2. Stage III-B of Hellman’s developmental stages (4 maxillary and mandibular incisors have erupted) 3. Angle Class III molar relationship 4. No previous orthodontic treatment |
History of orthodontic treatment | Patients treated at orthodontic clinic, Kyushu University Dental Hospital, Fukuoka, Japan | Comparison between maxillary protraction bow appliance and control group Intervention: Maxillary protraction bow Two cephalographs for each subject, 1 before and 1 after treatment Control: observation only Two cephalographs of each control subject were taken Mean treatment period to achieve normal overjet was 10.2 mo (range, 5-18 mo) |
Dental changes: correction of the reverse overjet in angular measurement Skeletal changes: ANB |
| Kajiyama et al 34 (2004) | |||||||
| CCT Note: Sample size calculation not described |
120 patients (42 boys, 78 girls) included Treatment and control groups were subdivided into deciduous and mixed groups Treatment group: Deciduous dentition: 34 patients Mixed dentition: 29 patients Control group Deciduous dentition: 32 patients Mixed dentition: 25 patients |
Treatment group: Deciduous dentition: 5 y 6 mo Mixed dentition: 8 y 7 mo Control group Deciduous dentition: not reported Mixed dentition: not reported |
1. Anterior crossbite (negative overjet) 2. Class III deciduous canine relationship 3. Bilateral mesial step type of terminal plane or Class III permanent molar relationship 4. No craniofacial anomalies (cleft lip or palate) 5. No previous orthodontic treatment |
Patients treated at orthodontic clinic, Kyushu University Dental Hospital, Fukuoka, Japan | Comparison between modified maxillary protractor (deciduous and early mixed dentitions) and control Intervention: modified maxillary protraction Lateral cephalograms taken at beginning of treatment without appliance and at removal of maxillary protraction bow appliance after achieving positive overjet Control: observation only. 2 cephalograms taken at start and end of observation periods, corresponding with timing in treatment group Mean periods of treatment were 5.2 months in patients with deciduous dentition and 10.2 months in those with mixed dentition |
Skeletal changes: ANB | |
| Lin et al 35 (2010) | |||||||
| CCT Note: Sample size calculation not described |
40 patients (20 boys, 20 girls) included Treatment group: 20 patients Control group: 20 patients |
Treatment group: 9 y 11 mo Control group: 9 y 6 mo |
1. SNA = 78°- 81°, sella-nasion-B (SNB) = 81°- 84° and ANB = –6°- 0° for Class III patients with both midface deficiency and mandibular prognathism 2. Negative incisal overjet and Class III molar relationship 3. ANB angle not smaller than –7°. |
Patients recruited from Kaohsiung Medical University, Taiwan | Comparison between occipitomental anchorage appliance plus chincup and control Intervention: occipitomental anchorage appliance plus chin cup Lateral cephalometric radiographs taken at 2 times: pretreatment or initial stage and posttreatment or final stage Control: observation only Mean observation period, 1 y 5 mo |
Dental changes: correction of the reverse overjet Skeletal changes: ANB |
|
Risk of bias in studies
The quality assessments of the RCTs are given in Figures 2 and 3 .
Selection bias
Nine of the 15 included studies were RCTs. Randomization and allocation concealment were adequate for Mandall et al, Liu et al, and Showkatbakhsh et al. The remaining studies were judged as either high risk or unclear on allocation concealment.
Performance and detection bias
Because of the nature of orthodontic studies, blinding of the patients and clinicians could not be performed and therefore was not assessed. However, blinding of the outcome assessors was carried out and judged as having a low risk of bias in Mandall et al, Vaughn et al, Liu et al, and Showkatbakhsh et al, and unclear for the others.
Attrition bias
The withdrawal rates were clearly reported in Mandall et al, Liu et al, Atalay and Tortop, Showkatbakhsh et al, and Saleh et al, judged as having low risk of bias. Interestingly, Atalay and Tortop reported no loss at follow-up in their study. The remaining studies were judged as having an unclear risk.
Overall, Mandall et al, Liu et al, and Showkatbakhsh et al were assessed as having low risk of bias. One study was classified as having a high risk of bias, and the remaining 5 studies were assessed as having an unclear risk of bias.
Quality assessment of CCTs
The quality assessment criteria for the CCTs were adopted from the checklist by Downs and Black ( Table V ). All included studies showed high risk of bias, with the total quality score less than 20 ( Table V ). Although these studies had a clear objective and an intervention of interest, there were several biases including lack of sample size calculation and blinding.
| Study | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | Total |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Kajiyama et al (2000) | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 1 | 0 | 14 |
| Cozza et al (2004) | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 14 |
| Kajiyama et al (2004) | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 1 | 0 | 15 |
| Lin et al (2007) | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 13 |
| Barrett et al (2010) | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 15 |
| Cozza et al (2010) | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 13 |
-
Questions:
- 1.
Is the hypothesis/aim/objective of the study clearly described?
- 2.
Are the main outcomes to be measured clearly described in the introduction or methods section?
- 3.
Are the characteristics of the patients/samples in the study clearly described?
- 4.
Are the interventions of interest clearly described?
- 5.
Are the distributions of principal confounders in each group of subjects to be compared clearly described? ( 2 , yes; 1 , partially; 0 , no)
- 6.
Are the main findings of the study clearly described?
- 7.
Does the study provide estimates of the random variability in the data for the main outcomes?
- 8.
Have all important adverse events that may be a consequence of the intervention been reported?
- 9.
Have the characteristics of patients lost to follow-up been described?
- 10.
Have actual probability values been reported (eg, 0.035 rather than <0.05) for the main outcomes except where the probability value is less than 0.001? (external validity: 1 , yes; 0, no and unable to determine)
- 11.
Were the subjects asked to participate in the study representative of the entire population from which they were recruited?
- 12.
Were the subjects who were prepared to participate representative of the entire population from which they were recruited?
- 13.
Were the staff, places, and facilities where the patients were treated representative of the treatment the majority of patients received? (Internal validity/bias: 1 , yes; 0 , no and unable to determine)
- 14.
Was an attempt made to blind the subjects to the intervention they received?
- 15.
Was an attempt made to blind those measuring the main outcomes of the intervention?
- 16.
If any of the results of the study were based on “data dredging,” was this made clear?
- 17.
In trials and cohort studies, do the analyses adjust for different lengths of follow-up of patients, or in case-control studies, is the time between the intervention and outcome the same for subjects and controls?
- 18.
Were the statistical tests used to assess the main outcomes appropriate?
- 19.
Was compliance with the intervention reliable?
- 20.
Were the main outcome measures used accurate (valid and reliable)? (Internal validity/confounding (selection bias): 1 , Yes; 0 , no and unable to determine)
- 21.
Were the patients in different intervention groups (trials and cohort studies) or were the subjects and controls (case-control studies) recruited from the same population?
- 22.
Were study subjects in different intervention groups (trials and cohort studies) or were the subjects and controls (case-control studies) recruited over the same period of time?
- 23.
Were study subjects randomized to intervention groups?
- 24.
Was the randomized intervention assignment concealed from both patients and health care staff until recruitment was complete and irrevocable?
- 25.
Was there adequate adjustment for confounding in the analyses from which the main findings were drawn?
- 26.
Were losses of patients to follow-up taken into account?
-
Power:
- 27.
Did the study have sufficient power to detect a clinically important effect where the probability for a difference due to chance was less than 5%? Sample sizes have been calculated to detect a difference of x% and y%.
Stay updated, free dental videos. Join our Telegram channel
VIDEdental - Online dental courses
