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.
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.