Will there be greater mandibular growth in class II patients with retrognathism treated with functional appliances than in non-treated individuals?

The search strategy of this systematic review was developed in order to identify the studies that evaluated mandibular growth in treated and not treated class II patients with retrognathism with functional appliances. It included studies published between January 1966 and January 2012 with the use of MEDLINE (www.ncbi.nlm.nih.gov/pubmed), Cochrane, Siencedirect and Lilacs data bases- The search strategy was the following:

#1 “Malocclusion, Angle Class II"[Mesh] OR "Retrognathism"[Mesh] AND ("humans"[MeSH Terms] AND (Clinical Trial[ptyp] OR Meta-Analysis[ptyp] OR Randomized Controlled Trial[ptyp] OR Review[ptyp] OR Clinical Trial, Phase III[ptyp] OR Clinical Trial, Phase IV[ptyp] OR Controlled Clinical Trial[ptyp]) AND ("child"[MeSH Terms] OR "adolescent"[MeSH Terms])

#2 ("Malocclusion, Angle Class II/therapy"[MAJR]) AND "Orthodontic Appliances, Functional"[MAJR]) AND "Mandible/growth and development"[MeSH Terms] AND (Humans[Mesh] AND (Clinical Trial[ptyp] OR Meta-Analysis[ptyp] OR Randomized Controlled Trial[ptyp] OR Clinical Trial, Phase I[ptyp] OR Clinical Trial, Phase II[ptyp] OR Clinical Trial, Phase III[ptyp] OR Controlled Clinical Trial[ptyp]) AND (English[lang] OR French[lang] OR Spanish[lang] OR Portuguese[lang]) AND (jsubsetaim[text] OR jsubsetd[text]) AND (child[MeSH] OR adolescent[MeSH]) AND ("1966"[PDat] : "2010"[PDat]))

- Randomised controlled clinical trial, non radomised clinical trial, cohort studies.

- Articles published between January 1966 and January 2012

- Articles in English, Spanish, French or Portuguese

- Studies in humans

- Studies in patients in growth.

- Studies evaluated with cephalometric radiographs that included mandibular length measurements using Co-Gna, Co-Po or Co-Mn.

Class II malocclusion occurs due to a variety of dento-skeletal situations which can be due to increased maxillary length and anterior maxillary position, decreased mandibular length and retrognathism or a combination of both with vertical excess or deficiency.

Inclusion Criteria:

- Patients of both sexes, aged betwen 6 and 18 years old.

- Patients with Class II malocclusion by retrognathism

Exclusion Criteria:

- Deficient quality of the studies

- Studies which evaluated mandibular length with point Ar

- Studies evaluated with MRI.

- Studies which utilized the Herbst appliance.

- Insufficient data for analysis

-Treatment combined with extractions.

-Treatment combined with fixed appliances.

- Surgical treatment

- Minimum 6 months in treatment.

-Treatment group: any of follow appliances: Bionator, Twin Block, Activator or Frankel.

- Minimum 6 months in treatment.

- Control group: patients with untreated class II malocclusion

Primary outcomes

Increase in mandibular length between Co-Gna or Co-Pog

Secondary outcomes

None

The data collected for each of the studies will include: title of the study, author, year of publication, duration of treatment, cephalometric points used to measure mandibular length, type of study, and sample size for each of the groups, type of appliance used and evaluation method for skeletal maturation.

Prior to evaluating the quality of the study, its structure will be reviewed based on the 2010 CONSORT guidelines for RCT and CCT studies, or STROBE for cohort studies, with the purpose of verifying that the essential aspects of an interventional or observational study were described. Four reviewers will apply the CONSORT and STROBE guidelines in an independent form and afterwards discuss the individual results in order to resolve significant differences by consensus. During this process none of the studies will be excluded due to the quality of the reports

- Funnel plots will be used to demonstrate the existence of publication bias among the included studies.

- Reviewers defined the following criteria in order to evaluate the quality of studies: explanation of calculation of sample size, description of mechanism for patient selection, explanation of the causes for withdrawal of patients, statistical analysis adequate to the type of data, description of the control for confusing factors, blindness for the evaluation of results and the use of p values or confidence intervals to accompany the effect of the estimation measure. Each of the criteria was valued by category assigning a value of 1 if the criterion is met and 0 when it is not met. Once the criteria are valued, the total sum for each study will be calculated and the scores obtained classified as low, medium or high quality depending if the scores are less than 4, between 4 and 5, or greater than 5. As in the application of the CONSORT and STROBE guidelines, the reviewers will carry out an independent evaluation and afterwards resolve any differences by consensus

The results for the estimation of the effect will be expressed as differences of means in millimeters on mandibular growth between treatment and control groups obtained from each of the studies selected. In addition, all identifying variables such as author, year of publication, type of appliance and type of study will be record. This data will be supplemented with records of duration of treatment and timing of treatment. Some identifying variables and supplemental variables will be use for the stratified analysis of the combined estimate of the effect.

The heterogeneity analysis between studies will be carried out using the Q Cochrane Test, using a critical value of p< 0.05 with the objective of determining the model of analysis by fixed or random effects.

The subgroup analysis will be conducted based on the type of appliance, timing of treatment, type of study and treatment duration.

Adriana Santamaria

Carrera 43A No. 7-50 Of. 1301 - Medelln - Colombia

adrisantamaria@hotmail.com

CES University

www.ces.edu.co

Professor Adriana Santamaria, CES University
Professor Emery Alvarez, CES University
Professor Ruben Manrique, CES University
Professor Diego Muñoz, CES University

14 February 2012

15 September 2012

CES University

None known

English

Colombia

Subject indexing assigned by CRD

Humans; Malocclusion, Angle Class II; Mandible; Mandibular Advancement; Retrognathism

28 August 2012

28 August 2012