Reinforcement of anchorage during orthodontic brace treatment with implants or other surgical methods

The term anchorage in orthodontic treatment refers to the control of unwanted tooth movement. This is conventionally provided either by anchor sites within the mouth, such as the teeth and the palate or from outside the mouth (headgear). Orthodontic implants which are surgically inserted to bone in the mouth are increasingly being used as an alternative form of anchorage reinforcement in orthodontics.

The primary objective of this review was to evaluate the effectiveness of surgical methods for preventing unwanted tooth movement compared with conventional anchorage reinforcement techniques. The secondary objectives were to examine patient acceptance, discomfort and failure rates associated with these techniques.

The Cochrane Oral Health Group's Trials Register, CENTRAL, MEDLINE and EMBASE were searched. No language restrictions were applied. Authors were identified and contacted to identify unpublished trials. The most recent search was conducted in February 2006.

Randomised or quasi-randomised clinical trials involving the use of surgically assisted means of anchorage reinforcement on orthodontic patients. Inclusion and exclusion criteria were applied when considering the studies to be included in this review.

Data extraction was performed by two review authors working independently using a previously piloted data collection form. Data were entered into RevMan with planned analysis of mean differences (MD) and 95% confidence intervals (CI) for continuous outcomes and risk ratios (RR) and 95% CI for dichotomous outcomes. Pooling of data and meta-analysis were not performed due to an insufficient number of similar studies.

At present few trials have been carried out in this field and there are little data of adequate quality in the literature to meet the objectives of the review. The review authors were only able to find one study assessing the use of surgical anchorage reinforcement systems. This trial examined 51 patients with 'absolute anchorage' requirements treated in two centres. Patients were randomly allocated to receive either headgear or a mid-palatal osseointegrated implant. Anchorage loss was measured cephalometrically by mesial movement of dental and skeletal reference points between T1 (treatment start) and T2 (end of anchorage reinforcement). All skeletal and dental points moved mesially more in the headgear group than the implant group. Results showed significant differences for mesial movement of the maxillary molar in both groups. The mean change in the implant group was 1.5 mm (standard deviation (SD) 2.6; 95% CI 0.4 to 2.7) and for the headgear group 3.0 mm (SD 3.4; 95% CI 1.6 to 4.5). The trial was designed to test a clinically significant difference of 2 mm, so the result was not statistically significant, but the authors conclude that mid-palatal implants do effectively reinforce anchorage and are an acceptable alternative to headgear in absolute anchorage cases.

There is limited evidence that osseointegrated palatal implants are an acceptable means of reinforcing anchorage. The review authors were unable to identify trials addressing the secondary objectives of the review relating to patient acceptance, discomfort and failure rates. In view of the fact that this is a dynamic area of orthodontic practice we feel there is a need for high quality, randomised controlled trials. There are financial restrictions in running trials of this nature. However it would be in the interest of implant manufacturers to fund high quality, independently conducted, trials of their products.