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Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet]. York (UK): Centre for Reviews and Dissemination (UK); 1995-.

Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet].

Skeletal and dental changes in class II division 1 malocclusions treated with splint-type Herbst appliances: a systematic review

C Flores-Mir, A Ayeh, A Goswani, and S Charkhandeh.

Review published: 2007.

Link to full article: [Journal publisher]

CRD summary

The authors concluded that use of the splint-type Herbst appliance improved a range of facial, mandibular and maxillary measures and that both dental and skeletal changes are important in achieving the final occlusal result. Given the poor quality of the primary studies and of the reporting and methodology in the review, these conclusions might not be reliable.

Authors' objectives

To evaluate skeletal and dental changes obtained after the sole use of splint-type Herbst appliances in class II division 1 malocclusions in growing individuals, as seen with lateral cephalograms.

Searching

MEDLINE, EMBASE, LILACS, Scopus, the Cochrane Database of Systematic Reviews, the Cochrane CENTRAL Register, ACP Journal Club, DARE and the Web of Science were searched up to January 2006; the search terms were reported. The reference lists of retrieved articles were examined. Articles only available as meeting abstracts were excluded.

Study selection

Study designs of evaluations included in the review

Controlled studies were eligible for inclusion.

Specific interventions included in the review

Studies of splint-type Herbst appliances, used without concurrent orthodontic or surgical interventions, compared with no treatment were eligible for inclusion. No details of the included interventions were given.

Participants included in the review

Studies of growing individuals with class II division I malocclusion without syndromic characteristics were eligible for inclusion. No details of the included participants were given.

Outcomes assessed in the review

Studies were eligible for inclusion if they reported skeletal or dental changes evaluated through linear or angular measurements on lateral cephalograms. A very wide range of dental and skeletal measurements were reported in the included studies; these related to cranial base, facial proportion and growth direction, mandibular measurements, maxillary measurements and intermaxillary relationships.

How were decisions on the relevance of primary studies made?

Four reviewers independently evaluated retrieved articles, apart from those retrieved from the LILAC database which were evaluated by a single author. Authors agreed on the final selection by unanimous consensus.

Assessment of study quality

The reviewers assessed the study design, outcome measures and statistical methods. The factors assessed in relation to study design were objectives, population, inclusion criteria, sample size, baseline comparability of the groups, whether randomised and/or prospective, and follow-up; outcome measures were assessed in relation to type, blinding and reliability; and statistical methods were assessed in relation to drop-outs, analytical methods, handling of confounding, reporting of p-values and confidence intervals. Both the appropriateness and quality of reporting of these factors were considered.

The authors did not state how the validity assessment was performed.

Data extraction

The authors did not state how the data were extracted for the review, or how many reviewers performed the data extraction.

Methods of synthesis

How were the studies combined?

The studies were combined in a narrative, with results grouped by outcomes.

How were differences between studies investigated?

Some differences between the studies were discussed in the text.

Results of the review

Three case-control studies were included in the review, one prospective and two retrospective (number of participants not stated).

None of the studies were blinded or analysed by intention-to- treat. Only one study was prospective, two had no long-term follow-up, and overall they fulfilled only 45 to 55% of the 20 quality criteria assessed.

There were statistically significant changes in the intervention group for the following outcomes:

the anteroposterior length of the mandible (mandibular protrusion: 2 studies, increase 1.2 to 2.9 degrees; mandibular dimensions: 3 studies, increase 0.7 to 2.7 mm);

the vertical height of the ramus;

the lower facial height (change in vertical dimensions for posterior and lower anterior facial heights: 1.4 to 2.5 mm and 1.2 to 3 mm, respectively; 2 studies of each);

mandibular incisor proclination;

mesial movement of the lower molars; and

distal movement of the upper molars.

Post-treatment relapse in the overjet and molar relationships was observed.

Authors' conclusions

Use of the splint-type Herbst appliance increased anteroposterior length of the mandible, the vertical height of the ramus, lower facial height, mandibular incisor proclination, mesial movement of the lower molars and distal movement of the upper molars. Dental changes are as important as skeletal changes in achieving final occlusal results; more research is needed to support these conclusions.

CRD commentary

The review had clear objectives and inclusion criteria. The search was thorough but unpublished studies were excluded, so publication bias might have been introduced into the review. Four reviewers independently evaluated the retrieved articles but no other steps to minimise reviewer error and bias were reported. There was no information about the included studies, such as the sample sizes, participant characteristics or specific outcomes measured. A large number of outcomes were described in the narrative synthesis but it was not always clear what the exact results were, whether these were statistically and/or clinically significant, or what the magnitude of effect was. The authors noted that two of the three studies reported relapse during post-treatment observation, but it is unclear whether the cited results took this into account. The validity of the studies was systematically assessed.

It is unclear whether the authors' conclusion regarding the importance of both dental and skeletal changes in achieving final occlusal results follows directly from the findings in the included studies. Given the deficiencies in the design and quality of the primary studies, and the poor quality of reporting and methodology used in the review, these conclusions might not be reliable.

Implications of the review for practice and research

Practice: The authors did not state any implications for practice.

Research: The authors stated that long0term double-blinded randomised controlled trials are needed to evaluate skeletal and dental changes associated with class II division I malocclusions treated with splint-type Herbst appliances.

Bibliographic details

Flores-Mir C, Ayeh A, Goswani A, Charkhandeh S. Skeletal and dental changes in class II division 1 malocclusions treated with splint-type Herbst appliances: a systematic review. Angle Orthodontist 2007; 77(2): 376-381. [PubMed: 17319777]

Indexing Status

Subject indexing assigned by NLM

MeSH

Case-Control Studies; Facial Bones /anatomy & histology /growth & development /radiography; Humans; Malocclusion, Angle Class II /radiography /therapy; Mandible /anatomy & histology; Orthodontic Appliances, Functional; Recurrence; Vertical Dimension

AccessionNumber

12007005292

Database entry date

16/05/2008

Record Status

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.

CRD has determined that this article meets the DARE scientific quality criteria for a systematic review.

Copyright © 2014 University of York.

PMID: 17319777

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