Design of customized soft tissue substitutes for posterior single-tooth defects: a proof-of-concept in vitro study.

Objectives Soft tissue volume augmentation treatments do not provide satisfactory long-term functional and aesthetic outcomes. The aim of the study was to develop a standardized digital procedure to design individual soft tissue substitutes (STS) and apply mathematical modeling to obtain average shape STS for single posterior tooth defects. Material and methods Thirty-three casts from 30 patients were scanned. STS were designed with a computer-aided-design software and a systematic procedure standardized the measurements across all STS using 3D analysis software. The occlusal, mesial-distal and buccal-lingual planes were defined to partition each STS and produce a mesh. The thickness values of each 3D slice were documented in a coordinate system chart to generate a scatter graph. Graphs were embedded into images (Orange software) and images were analyzed via hierarchical clustering. Results Three STS groups were identified according to shape. Two shapes corresponded to the maxilla defects: a square (n=13) with dimensions of 10mm in a lingual-buccal (length) and 7-10mm in a mesial-distal (width) direction; a rectangle (n=11) of 11mm in length and 4-7mm in width. The average shape for mandible defects (n=9) was smaller (6-8mm in length, 5-10mm in width). The highest thickness in all STS was in the buccal portion, above the alveolar ridge, with median values of 2mm. The lowest thickness of 0.2mm was at the edges. Conclusions The study developed novel methodology to design customized as well as average shape STS for volume augmentation. Future STS harboring adapted geometry might increase volume augmentation efficiency and accuracy, while reducing surgical time.