Injectable calcium phosphate cement as a graft material for maxillary sinus augmentation: an experimental pilot study

Current maxillary sinus augmentation techniques rely on autologous bone grafts, which have limitations including donor site morbidity. Prior research has shown that graft materials must integrate with surrounding bone without fibrous tissue barriers. This gap motivated the investigation of injectable calcium phosphate (CaP) cement as a potential alternative. The need for a graft material that promotes bone formation without fibrous encapsulation remains unmet. No prior work had resolved how injectable cements compare to autologous bone in sinus augmentation. This study aimed to address this uncertainty. The knowledge gap lies in the clinical viability of CaP cement for sinus elevation. This paper contributes by testing CaP cement in an experimental model.

The study aimed to assess injectable CaP cement's effectiveness as a graft material in maxillary sinus augmentation. The specific problem is the need for alternatives to autologous bone grafts. The motivation stems from limitations in current grafting techniques. The experimental design involved comparing CaP cement to autologous bone in sheep models. The goal was to evaluate bone formation and integration. The focus was on bone-to-implant contact and tissue response. The study sought to determine if CaP cement could stimulate bone growth without fibrous barriers. This approach addresses the need for improved graft materials in sinus augmentation.

The study used a bilateral sinus augmentation model in three sheep. Each animal received two implants per session, totaling 12 implants. Eight implants were assigned to the experimental group using CaP cement. The control group used autologous bone grafts. Histological analysis was performed after a 12-week healing period. Bone-to-implant contact (BIC) was measured in both groups. The study evaluated the presence of fibrous tissue between graft material and bone. The cortical bone thickness covering the maxillary sinus was also assessed.

Histological findings showed new bone formation around CaP cement without fibrous tissue. BIC values in the experimental group averaged 36+/-5. Control group BIC values averaged 37+/-3. The results suggest comparable bone integration between groups. The absence of fibrous tissue supports CaP cement's biocompatibility. Cortical bone thickness was less than 2-3 mm, affecting implant stability. The BIC percentages aligned with previous experimental studies. These findings indicate CaP cement's potential for bone regeneration.

The authors propose that CaP cement can stimulate bone formation in sinus augmentation. The absence of fibrous tissue suggests good integration. BIC values in both groups were statistically similar. The material's performance was comparable to autologous bone. However, the thin cortical bone layer reduced implant stability. The study suggests that cement composition needs refinement for clinical use. The findings support further research on CaP cement's properties. The authors emphasize the need for material improvements before clinical application.