A comparison of the effectiveness of three methods of anchorage reinforcement in the treatment of maximum anchorage patients : a randomised clinical trial

The primary intention of this study was to add to the body of scientific evidence by determining whether a recently introduced method of anchorage reinforcement, namely Temporary Anchorage Devices (TADs), is effective. It is clear that there are several commonly used methods for anchorage support but some of these are totally dependent for success upon good patient compliance. Orthodontic clinicians would enthusiastically welcome as an alternative, an effective and efficient method that is less dependent upon patient co-operation. The introduction of new orthodontic techniques is rarely supported by high quality evidence on efficiency or effectiveness, in advance of them being promoted for widespread clinical use. New appliances and techniques are often promoted based upon very low levels of clinical evidence. Temporary Anchorage Devices were first introduced in 1983. Since then many papers have referred to Temporary Anchorage Devices as a source of stationary anchorage yet to date, few Randomised Clinical Trials (RCTs) have been carried out into this treatment method. AIMS To evaluate the effectiveness of Temporary Anchorage Devices for orthodontic anchorage when compared with the Nance button palatal arch and to Headgear. METHOD The TADs assessment trial is a prospective, dual-centre RCT involving 78 ‘maximum anchorage’ patients between 12 and 18 years of age with 39 males and 39 females. The three treatment arms of the study were Headgear, a Nance button palatal arch and TADs. Outcomes recorded included: anchorage loss measured both on lateral cephalometric radiographs and 3D model scanning, length of treatment, number of visits, quality of the outcome and the patients’ perception of the various treatment methods. RESULTS Sample summary showed the groups to be matched in terms of age, start PAR score and SNA. There was a statistically significant (p=0.002) overall effect of treatment when the right molar position was assessed on cephalograms. The Nance group lost 2.03mm (0.81-3.25) more anchorage than the Headgear group. No other statistically and clinically significant results were recorded between the groups on the cephalograms or on the superimposed digital models. Mean treatment times in months varied from 26.83 (SD 9.35) to 28.01(SD 5.38) and the total number of visits from 18.38 (SD 5.95) to 21.77 (SD 4.41). Casual visits and DNAs were almost identical between the groups but PAR scores were nearly 4 points better with TADs than Headgear and Nance. This result was statistically and clinically significant. From the patient questionnaires, the comfort levels both on placement and removal were similar with TADs and the Nance, and both techniques were highly recommended by the patients. Headgear was more troublesome and much less popular with the patients. CONCLUSIONS 1) There is no difference in the effectiveness of temporary anchorage devices, Nance button palatal arches and headgear in reinforcing anchorage in orthodontic treatment. 2) Patients’ perceptions suggest that there were greater problems with headgear and Nance buttons, than with temporary anchorage devices. 3) The quality of treatment as measured by PAR scores was significantly better with TADs than with headgear 4) Temporary anchorage devices may be the preferred method of choice for reinforcing orthodontic anchorage