Aim: To investigate by a longitudinal retrospective study the stability of the transverse maxillary expansion after SPSMO in CLP patients. A second aim was to compare these data with non-CLP adult patients receiving a surgically assisted rapid palatal expansion.

Materials and methods: 31 CLP patients treated with SPSMO followed by hyrax expansion. The dental casts were analyzed at different time points: before treatment, maximum expansion, during orthodontics, at completion and 2 years post-orthodontic treatment and measured at canine, premolar and molar level. Non-CLP adult patients enrolled in the prospective study of Chamberland et al., 2011 served as a control group.

Results: The maxillary expansion within the study group was significant ( P < 0.05) at all measured levels when compared to the maxillary arch pre-treatment. No significant relapse could be measured 2 years post-orthodontic treatment. When comparing study and control group, the only statistical difference was that the canine expansion was significantly greater in the study group.

Conclusion: SPSMO based maxillary expansion is a valid treatment option to correct the transversally collapsed maxilla in CLP patients. The overall treatment effect of SPSMO expansion is comparable with the effects of SARPE, with the canine expansion being greater in the SPSMO group.