Chin augmentation with various alloplastic materials: a comparative study.

This retrospective study of 62 patients compared three alloplastic materials used in chin augmentation: Proplast I (PI), Proplast II (PII), and porous block hydroxyapatite (PBHA). There were 25 patients with PI implants (average follow-up of 44.8 months), 25 patients with PII implants (average follow-up of 32.8 months), and 12 patients with PBHA implants (average followup of 19.1 months). Average bone resorption was 1.25 mm (range 0.00 to 3.30 mm) beneath the PI and PII implants and 0.00 mm beneath the PBHA implants. Average posterior settling was 0.46 mm (range 0.00 to 2.00 mm) for the PI and PII implants and 0.03 mm (range 0.00 to 0.17 mm) for the PBHA implants. The percentage of soft tissue change at pagonion relative to the size of the implant was 83.0% (range 66.7% to 100.0%) for PI and PII and 86.8% (range 77.3% to 100.0%) for the PBHA implants. When PI or PII implants were used, younger patients had more resorption than older patients. Slightly more resorption was found with PI and PII implants when maxillary surgery was performed. The size of the PI or PII implants made no difference in the amount of bone resorption, although there was slightly less soft tissue change when larger implants were used. Males had slightly more bone resorption than did females. The bone resorption beneath the PI and PII implants occurred within the first 12 months postsurgery. It can be concluded from this study that PI and PII implants are acceptable materials for chin implants, but some resorption can be expected during the first 12 months postsurgery. The absence of detectable resorption and the excellent soft tissue change make PBHA an attractive alternative as a chin implant material, although it is technically more difficult to use.