The Effect of Timing on Orthodontic Treatment - Studied by Randomized Clinical Settings

1. Background In spite of the fact that about 30 to 50% of the children in Europe undergo orthodontic treatment during growth, negligible amount of evidence based data is available concerning these treatments.

The most used treatment method in Finland, and one of the most popular in the world, is to treat dental crowding and class II malocclusion with the headgear (Mäntysaari et al., 2004; Pirttiniemi et al., 2005; Pietilä et al., 2008).

The goal of the HG treatment is variously listed as to inhibit maxillary growth, to stimulate mandibular growth, or to ease the crowding. During the recent years McNamara (2002) and Fenderson et al (2004) have emphasized the advantages of the lateral expansion of dental arches in the treatment of crowding, especially stressing the stability of the results.

The views of the effects of cervical headgear (HG) are to some extent obscure, at least when the long-term effects are concerned. Most reports that are based on a short-term follow-up, describe a restricted maxillary anterior growth. During the later growth, it is not clear what is the general association of early orthodontic treatment on crowding, but our earlier results show that in the final outcome there is no significant difference in stability of the treatment if crowding is treated with early headgear or later with fixed appliances only, at least when the long-term effects of the treatment are concerned (Krusinkiene et al., 2008).

A valid evidence based data is rare and the thus exact conclusions are very difficult to be set (Petrén and Bondemark, 2008). 2. Preliminary Studies We conducted a randomized clinical study with an early headgear treatment, where the control group was treated with a camouflage treatment in the adolescence. The main difference between the groups was broader dental arch with less extractions in the headgear group, the differences between the groups being relatively small when the craniofacial differences or the stability are concerned (Mäntysaari et al.,2004; Pirttiniemi et al.,2005; Krusinskiene et al., 2008). There were, however, some distinct profile differences between the groups and the canine eruption pattern was found to be more favorable in the early headgear group (Silvola et al., 2008; Virkkula et al., 2008). 3. Experimental Design and Methods