Beta-tricalcium phosphate patient-specific gap implants in bilateral sagittal split osteotomy: an innovative treatment method to enhance the mandibular border contour. Part 1: concept and workflow.

Antegonial notching can occur after bilateral sagittal split osteotomy (BSSO) and may lead to unpleasant aesthetic outcomes in both young and older patients. This clinical study presents a new concept to potentially overcome this problem and describes the workflow. Beta-tricalcium phosphate patient-specific gap implants (β-TCP gap-PSIs) are biocompatible and resorbable bone grafts that are placed in the space of the osteotomy gap during orthognathic procedures; they are virtually planned and printed in 3D. Between July 9, 2017 and July 31, 2018, 14 patients received bilateral β-TCP gap-PSIs during BSSO procedures. Nine were female (64.3%) and five were male (35.7%); mean age at surgery was 32.4 ± 12.7 years and the mean sagittal advancement gap was 9.4 ± 1.74 mm. The immediate postoperative position of the β-TCP implants, as well as early and long-term complications were evaluated; the clinical follow-up was 5 years. Intraoperative placement of the β-TCP implants was achieved without early complications, and the mandibular border contour was rated as very good or good in 82.1% of sides. Two minor long-term complications occurred, resulting in a total grafting success rate of 92.9%. In conclusion, this initial study (part 1) showed the potential of the β-TCP gap-PSI concept in BSSO procedures to prevent antegonial notching, which is currently underestimated and underreported. However, further extensive quantitative assessment is mandatory and will be presented in part 2.