Cone-beam computed tomography evaluation of the morphology and resorption of premolar and molar roots in response to rapid maxillary expansion

Aim: The purpose of this study was to compare the dental and skeletal sequelae of both tooth supported and implant supported expansion devices via CBCT, including buccal tipping, dental and skeletal expansion, and root resorption. Methods: 40 patients prescribed RME therapy were divided into two groups. Group 1 received a traditional tooth supported hyrax style expander. Group 2 had 4 implants placed palatally and an expander seated directly on the implants. Each patient had CBCT images taken prior to expander placement and after 3 months of passive retention. Multiplanar coronal and axial slices were used to measure linear transverse dimensions, inclinations of teeth, thickness of the buccal plate, and root length. Two-way ANOVA and a paired t test were used to compare the results of the two treatment methods.;Results: Increases in expansion were achieved for all transverse measurements. The implant supported group experienced greater expansion in all skeletal measurements than the conventional group. Significantly greater increases in expansion occurred in molar nasal cavity width, incisive foramen width, premolar sutural width, and molar sutural width in the implant group than the conventional group. Traditional RME had greatest gains in the incisive foramen and smallest gains in the molar suture in the classic RME wedge shape, while the implant supported RME had greatest gains in the premolar region and very similar gains in the incisive foramen and molar suture, revealing a more parallel sutural opening. Implant supported RME subjects experienced greater skeletal changes than dental changes, while the tooth supported RME subjects experienced greater dental changes. Conventional tooth supported RME subjects experienced significantly more buccal bone loss and greater buccal inclination than the implant supported counterparts. No significant differences were reported for root lengths or for total amount of root length change.;Conclusion: The implant supported expander group produced significantly more skeletal expansion than the conventional tooth supported expander group. More dental tipping and buccal bone loss was found in the conventional tooth supported expander group. Root lengths remained relatively stable, with no significant differences in resorption observed between the two groups.