Three-Dimensional Quantification of the Effects between Different Types of RME

Abstract

beneficial impact on class III treatment [14,15,17] and furthermore suggested that it might also be a successful alternative to conventional appliances because of its expanding forces at the centre of resistance of the nasomaxillary complex [16-18]. For the practitioner it is of particular interest at what age a specific RME-modification should be preferred, whereby the aim would always be a maximum of therapeutic effectiveness while being minimal invasive. A study compared skeletal and dental effects of Hyrax-RME and Hybrid-RME in young adults with the same age (13-14 years) [19]. The only significant difference was that the bone thicknesses of the left first premolars significantly differed between groups. Although Hybrid-RME therefore seemed to have advantages over Hyrax-RME, it should be critically questioned if the insertion of mini-implants is justified, considering the fact, that Hyrax-RME was able to lead to a comparable skeletal and dental expansion at that age.

Comparison of alveolar bone morphology after expansion with hybrid and conventional Hyrax expanders

“…Other difference is related to the amount of screw expansion that was 7mm in the present study and 10mm in a previous study [19,20]. At the palatal aspect of posterior teeth, the bone plate slightly increased in both HH and CH groups.…”

“…Regarding the skeletal effects, previous prospective and retrospective studies have not nd differences between hybrid and conventional expanders [19,20]. On the other hand, two randomized clinical trials demonstrate a greater increase of the nasal cavity and maxillary width with hybrid expanders [11,21].…”

“…These ndings are in disagreement with previous studies, since a smaller decrease of the buccal bone thickness of maxillary rst premolar with the Hybrid hyrax expander was found. [19,20]. The possible explanation are differences in sample age.…”