Orthodontic space closure without counterbalancing extractions in patients with bilateral aplasia of the lower second premolars.

BACKGROUND

Orthodontic space closure in situations with bilateral aplastic lower second premolars without maxillary extractions is a rarely practiced treatment method. Due to the high risk of severe side effects, preference is currently given to the maintenance of deciduous second molars and subsequent prosthodontic solutions. As a combination of Class I push and Class II pull mechanics seemed likely to reduce secondary effects by transferring the anchorage site from the reactive lower anterior teeth to the more resistant upper arch, a clinical study was carried out in order to investigate effects and secondary effects of the mechanics.

PATIENTS AND METHOD

Casts, panoramic radiographs and lateral headfilms of 13 consecutively treated, non-selected adolescents (seven boys, six girls, mean age at start of treatment 13 years 4 months) were evaluated. In six patients a Jasper Jumper trade mark was inserted in addition for a mean period of 6 months.

RESULTS

The treatment outcome after a mean period of 3 years and 1 month showed in almost all cases the desired Class III molar occlusion of one cusp width (+/- 1/4 cw) with overbite and overjet within the normal range. Analyses of static and dynamic occlusion revealed anterior/canine protected articulation and a satisfactory number of centric contact points. A significant space gain (p </= 0.01) distal to the lower second molars (right side: 4.9 mm, left side: 5,3 mm) confirmed a relevant movement of the lower molars to mesial and an increased probability of being able to save the lower third molars as a natural substitute for the aplastic second premolars. Mean reductions in incisor inclination were low (0.5 degrees ) in the upper and moderate (4.3 degrees ) in the lower arch.

CONCLUSION

Bearing in mind that supporting anchorage measures may be needed to compensate for unfavorable cofactors, the investigated treatment method can be recommended for those patients giving preference to a prosthetic-free dentition and to avoiding surgical interventions.