Age-dependent effects of Delaire facemask therapy for class III malocclusion : Impact on maxillary sutures and palatal morphology.

Background and aim: Treatment effects of a combined rapid maxillary expansion (RME) and Delaire facemask (DFM) therapy have so far only been scientifically investigated through cephalometric analyses. The combination of cephalometric, dental cast and cone-beam computed tomography (CBCT) scan analysis was not yet used for investigating morphologic changes of the tooth-bearing palate. The aim of the present study was to determine whether patient age at treatment begin has an influence upon palatal length changes after RME/DFM therapy, and to what extent transverse palatal sutures contribute to these.

Patients and methods: In n = 6 patients (min 10.5 years, max 14.7 years) from a total group of n = 40, CBCT datasets showing all palatal sutures were visually assessed, and palatal morphology was compared with a dental cast analysis. In addition, lateral cephalograms and dental casts of n = 40 patients were divided into two groups (PG1: < 12 years, n = 20; PG2: ≥ 12 years, n = 20), and an analysis was performed to investigate changes in the tooth-bearing palate after RME/DFM treatment.

Results: The CBCT analysis showed that the median and transverse palatine sutures were always open. On the contrary, the pterygopalatomaxillary sutures were partially open only in the youngest patients. The transverse palatal suture showed age-dependent morphologic changes in the transverse and sagittal planes. The changes of the palatal width and length show clear differences between the two younger and the four older patients in the corresponding dental cast analysis. The cephalometric analysis showed that a significant improvement of the sagittal jaw relation due to ventral displacement of the maxilla during treatment occurred only in younger patients (< 12 years) despite similar initial findings in both patient groups. The dental cast analysis also revealed that changes are age-dependent: In PG1, the width increases posteriorly more than anteriorly; in PG2, this is reversed. The length increases are always significant in both patient groups, whereby the anterior, posterior, and total amounts are greater in PG1 than in PG2. In relative terms, the increases in both groups are greater posteriorly than anteriorly. There is a significant difference between the groups posteriorly and overall.

Conclusions: Morphological changes of the sutures appear to have a decisive influence on the success of RME/DFM therapy. The age-dependent reactions of pterygopalatomaxillary and transverse palatine sutures represent a further main therapeutic effect of DFM treatment in addition to those described by Delaire and explain the different changes in palate length before and after the age of 12. If the maximum effect of RME/DFM treatment is desired, it should be started before the age of 12. Treatment success is age-dependent.