Suitability of calcium phosphate cement for injection laryngoplasty in rabbits

Calcium phosphate cement (CPC) consists of powder and liquid, which become an injectable paste after mixing, self-hardening and recrystallizing to calcium hydroxylapatite (CaHA) after injection into a living body. In this study, we investigated the suitability of CPC as an injectable material for injection laryngoplasty using rabbits. All rabbits underwent left recurrent laryngeal nerve section and injection laryngoplasty with CPC. At 7 days, scanning electron microscopic findings revealed that complete recrystallization from CPC to CaHA was achieved in the larynx. At 1, 3, and 6 months, injected CPC stayed in the paraglottic space and did not migrate, and the average remaining CPC volume percentage was 91.7%. Focal foreign body reaction to injected CPC was almost the same as that of autologous fat for all time periods observed. These results indicated that CPC appears to be biocompatible, nonabsorbable, nonmigratory, and suitable for injection laryngoplasty.