Aim
To undertake a systematic review of the evidence supporting early treatment (before the age of 10) of Class II malocclusion, with special reference to short and long-term outcomes: correction of overjet, dental relationships, improvement in intermaxillary relationships, soft tissue profile, associations to Temporomandibular Disorders (TMD), quality of life, incidence of trauma and cost-effectiveness.
Material and methods
Four databases were searched, from January 1960 to October 2017. Inclusion criteria were randomized controlled or controlled trials reporting short or long-term effects on dental or basal relationships, soft tissue profile, associations to TMD, quality of life, incidence of trauma, or costs. The quality of evidence was scored according to GRADE.
Results
297 studies were identified and 23 satisfied the inclusion criteria for full evaluation. The quality of evidence was high in 5 studies, moderate in 3, and low in 15. There is lack of data on long-term outcomes and stability, thus all evidence is based on short-term results. There is high level of evidence that early treatment of Class II malocclusion with functional appliances reduces overjet and improves skeletal relationships, moderate evidence that headgear reduces overjet and restrains forward growth of the maxilla, but insufficient evidence to determine how early treatment influences soft tissue profile, TMD, quality of life, incidence of trauma or treatment-related costs.
Conclusion
There is moderate to high evidence that in the short term, early treatment of Class II malocclusion division 1 reduces overjet and improves skeletal relationships.
Class II malocclusion is one of the more common malocclusions in children. The reported prevalence ranges from 14 to about 25% depending on the age of the children observed [1,2].
Various dental and basal deviations may result in a Class II malocclusion. Mandibular retrusion is common finding [3], as are pronounced overjet and prominent maxillary incisors with incomplete lip closure. Pronounced overjet and incomplete lip closure has been shown to increase the risk for dental trauma [4]. Recent Cochrane review reported that early treatment with a functional appliance achieved a statistically significant reduction in the incidence of incisal trauma [2]. This finding has however been further discussed due to a high degree of uncertainty [5]. Also Temporomandibular Disorders (TMD) has claimed to be associated with Class II malocclusions [6] but the effect treatment of Class II malocclusions may have on development of TMD is insufficient [7].
Early versus late orthodontic treatment has been debated. Proponents of early intervention have claimed that treatment is easy to perform, there is better use of growth potential, the extent of treatment in the permanent dentition is reduced and there should be less damage to teeth and tissues [8]. Furthermore, early treatment of Class II malocclusion has also claimed to have positive influence on self-esteem [9].
Comparison of one and two-phase treatment of Class II malocclusion showed no difference with respect to final overjet, basal relationship or the overall treatment success as scored by Peer-Assessment-Rating (PAR) [10]. Additionally, systematic reviews have concluded that compared to one-phase treatment, two-phase treatment offers no advantage, except for the reduction in the incidence of incisor trauma. Most of the available research is based on study populations that start their treatment from the age of ten and up to early teens [2].
Treatment recommendations, whether formulated as public policies or for the individual patient, should be based on the best available research evidence. A Randomized Controlled Trial (RCT) is often the preferred study design for evaluating treatment, because it reduces bias. By assessing the overall quality of the research and exposing potential knowledge gaps, a systematic review of research into a specific question is a valuable aid to the clinician [11].
A broad approach is of interest to evaluate the full effects of a treatment. A focus on patient centred outcomes, such as quality of life and dental trauma should be put in relation to dental and basal effects as well as a socio-economic aspect. Therefore, the aim of the present study was to undertake a systematic review of the evidence supporting early treatment (before the age of 10) of Class II malocclusion, with special reference to short and long-term outcomes: correction of overjet, dental relationships, improvement in intermaxillary relationships, soft tissue profile, associations to TMD, quality of life, incidence of trauma and cost-effectiveness.
Participants |
Children starting orthodontic treatment for Class II malocclusion before the age of 10 years. |
Interventions and comparators |
Any intervention provided to treat Class II malocclusion in the early mixed dentition.Two-phase orthodontic treatments for Class II malocclusion when short-term outcomes are specifically reported after completing first phase of treatment.Controls are comparable non-treated children or children receiving another intervention. |
Outcomes |
Short and long-term effects measured as: success in correction of overjet, dental relationship, improvement in intermaxillary relationship, soft tissue profile, incidence of trauma, quality of life and cost-effectiveness. |
Study design |
RCT or prospective controlled trials |
Figure 1: Flow of information through the different phases of the systematic review.
Author |
Year |
Stamenkovi? et al. [27] |
2015 |
Landázuri et al. [22] |
2013 |
Silvestrini-Biavati et al. [26] |
2012 |
de Almeida et al.* [19] |
2008 |
Quintão et al. [25] |
2006 |
de Almeida et al.* [18] |
2005 |
Janson et al. [21] |
2003 |
de Almeida et al. [17] |
2002 |
Mills and McCulloch** [24] |
2000 |
Mills and McCulloch** [23] |
1998 |
Dann et al. [16] |
1995 |
Wieslander [30] |
1993 |
Wieslander*** [28] |
1984 |
Wieslander *** [29] |
1984 |
Harvold and Vargenvik [20] |
1971 |
Author, Year |
Study Design |
Study Population |
Outcome Measures |
Results |
Study Quality/Comments |
|
Chen et al., 2011 [32] |
RCT |
93 Headgear/biteplane |
Modified Ellis injury classification |
A significant number of children (25%) had already experienced incisor trauma before treatment were initiated. |
Moderate |
|
O´Brien et al., |
RCT |
20 twin-block |
Attractiveness graded by Likert-scale |
After twin-block treatment, the profile was rated as more attractive when compared to untreated controls. |
High |
|
O´Brien et al., |
RCT |
89 twin-block |
Piers-harris children´s |
At onset and at 15 months follow-up, both groups reported medium- to high self-esteem. |
High |
|
O´Brien et al., 2003 [30] |
RCT |
89 twin-block |
Cephalometrics: |
Twin-block treatment resulted in a reduction of overjet, 70% of the correction due to dentoalveolar changes. |
High |
|
Koroluk et al., |
RCT |
52 bionator |
Incidence of trauma |
Trauma to maxillary incisors was found in all groups. Most injuries were minor and related costs were estimated as low. |
High |
|
Keeling et al., |
RCT |
90 headgear/biteplane |
Cephalometrics: |
Bionator and headgear groups showed significantly more skeletal Class II correction than untreated controls. Early treatment with headgear resulted in significant dental Class II correction, affecting maxillary incisors and molars. |
Moderate |
|
Tulloch et al., |
RCT |
53 bionator |
Cephalometrics: |
Overall, early treatment showed a reduction in overjet and a 75% chance for improving the jaw relationship. Basal improvement was achieved through different mechanisms. |
High |
|
Jakobsson, |
RCT |
20 headgear |
Cephalometrics: |
Early treatment reduced overjet. Activator and Headgear treatment appeared to affect positioning of the maxilla, most pronounced by Headgear treatment. Both treatments significantly increased facial height. Activator treatment had an effect within the dento-alveolar area of the mandible, but no support for an orthopaedic effect was found. |
Moderate |
The main finding for this systematic review was a high level of evidence that early treatment of Class II malocclusion and specifically Class II division 1, using a functional appliance reduces overjet and improves antero-posterior basal relationships in the short-term. There is a moderate level of evidence, also in the short-term, that headgear reduces overjet and restrains forward growth of the maxilla. Evidence was insufficient with respect to the effect of early treatment of Class II malocclusion on soft tissue profile, quality of life, incidence of trauma or treatment related costs. Though insufficient evidence found in this review, current research points to Class II treatment not being a risk factor for TMD development [7], further well-designed studies may add knowledge to this question. Finally, no conclusions with respect to long-term outcome and stability of early treatment could be drawn.
Under the GRADE system for scoring evidence, study quality is denoted as high or moderate. Because there were few studies of adequate quality covering the same outcome, no evidence base emerged with respect to the effects of early treatment of Class II malocclusion on soft tissue profile, quality of life related measures or cost-effectiveness. However, when few relevant high quality studies are identified, it is important to bear in mind that insufficient or limited evidence does not imply lack of effect. Although it must be noted that every single case must be planned individually, with special consideration on patient’s needs and desires which also implies that a large proportion of patients with Class II malocclusion might not benefit from two-phase treatment [2], it is still important to identify the variables which characterize children in whom an early treatment approach would be advantageous [38]. Therefore, in order to evaluate existing results and to fill potential knowledge gaps in this field, there is still a need for further methodologically well-designed studies.
It was notable that three [9,32,33] of the five high quality studies were based on the same study population and that the other two [31,34] also originated from one and the same population. This could be considered problematic because the weighted result is based on a rather small number of study populations. The difference in outcome measures for the high quality studies as well as differences in methodology made it difficult to compare treatment results. Therefore, only a general conclusion regarding antero-posterior basal relationships could be drawn.
From the initial 297 articles generated by the literature search, only 23 studies satisfied the eligibility criteria and were included in the final evaluation. This is not uncommon in a systematic review, as the purpose of the search strategy is to identify all relevant studies related to the research question. Furthermore, in order to avoid subjectivity in the assessments, independent observers evaluated the quality of separate studies and the overall level of evidence. Consistency among the observers was high (95%); any conflicting assessments were resolved by discussion to reach consensus. Moreover, using Goodman’s model [12] fulfilled the criterion of repeatability and minimized the risk that chance or arbitrariness would affect the conclusions.
With reference to methodology, one of the most common reasons for exclusion was retrospective study design. Furthermore, because the objective was to evaluate early treatment, the composition of the study population was of great importance. A frequent reason for exclusion was the wide age range of the children who constituted the study group. This made it impossible to ensure an early treatment approach. One aspect which should be addressed is the fact that chronological age and dental age do not necessarily correlate. However, studies reporting dental age were seldom identified and an age span of several years was a common finding. An inclusion criterion limiting chronological age was considered appropriate in order to meet the definition of early treatment.
An important determinant of success with removable appliance therapy is patient compliance, yet this factor was inadequately addressed in basically all studies. At best, there were statements describing how the patients were instructed to use the different appliances. Reports as to if, or how, this was controlled were lacking. To fully assess treatment outcome, the results should be considered in relation to patient cooperation and compliance.
Finally, the findings of this systematic review are in accordance with a recent meta-analysis of cephalometric assessment of the treatment results for removable functional appliance therapy in the mixed dentition [39]. With a broader focus, the aim of this systematic review was to evaluate treatment effects on dental and basal relationships as well as cost-effectiveness, incidence of trauma and impact on quality of life.
It has been concluded that a two-phase treatment approach offers no final advantage compared to one-phase when looking at dental and basal variables [2]. Whether early treatment can be justified from a psychosocial, socioeconomic or trauma preventive aspect is not yet validated scientifically. Therefore, further research is needed.
This study has been supported by the Swedish Dental Society and the TePe Eklund Foundation Scholarship for research at Faculty of Odontology, Malmö University, Sweden.
Citation: Kallunki J, Bondemark L, Paulsson L (2018) Outcomes of Early Class II Malocclusion Treatment - A Systematic Review. J Dent Oral Health Cosmesis 3: 009.
Copyright: © 2018 Jenny Kallunki, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.