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

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.

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.

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.

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.