Stability of the chin after advancement genioplasty using absorbable plate and screws with template devices.

[PURPOSE] The purpose of this study was to compare the stability of the chin between absorbable plate and screws with a template device and titanium plate after advancement genioplasty in class II patients.

[PATIENTS AND METHODS] The subjects consisted of 22 Japanese class II patients who underwent genioplasty advancement in combination with bi-maxillary surgery. After genioplasty horizontal osteotomy, the template plate and screws were fixed at the central region of the chin temporarily. Then, two absorbable bi-cortical screws (uncalcined and unsintered hydroxyapatite and poly-l-lactic acid: uHA/PLLA) were used and fixed bilaterally. After removal of the template plate and screws, one absorbable plate and screws were added to fix the segment in the advancement genioplasty (n = 14). The remaining 8 patients underwent genioplasty advancement surgery with the conventional titanium plate. For all patients, lateral cephalograms were obtained pre- and immediately after surgery and at 1 year after surgery. Change in the Pogonion (Pog) and Menton (Me) points and the corresponding soft tissue points (PogS and MeS) were evaluated.

[RESULTS] Although there were no significant differences in the change from before to immediately after surgery between the absorbable and titanium groups, there were significant differences in the Pog (Y) (P = 0.0379) and PogS (Y) (P = 0.0379) from immediately after surgery to after 1 year between both groups.

[CONCLUSION] This study shows that predicted advancement of the chin in the absorbable group could be achieved by using a template and screws, and likewise in the titanium group. However, this study suggested that vertical relapse to the inferior site or resorption at the antero-superior edge of the segment could occur in the absorbable group.