Processing and properties of strong and non-rigid calcium phosphate cement

A calcium phosphate cement (CPC) sets to form hydroxyapatite and has been used in dental and craniofacial applications. However, when CPC was used in periodontal repair, tooth mobility resulted in the fracture and exfoliation of the brittle implants. The aim of this study was to develop CPC-chitosan lactate composites with higher strength and increased strain before failure. It was hypothesized that the incorporation of chitosan lactate would render CPC non-rigid with improved properties. Two-way ANOVA showed significant effects of chitosan lactate and powder:liquid ratio (p < 0.001) on flexural strength, strain-at-peak-load, work-of-fracture, and elastic modulus. At powder:liquid = 2, the strength (mean +/- SD; n = 6) at 20% chitosan lactate was 15.7 +/- 1.3 MPa, higher than 4.9 +/- 1.4 MPa of CPC without chitosan lactate. At powder:liquid = 1, the strain-at-peak-load was 0.2% for CPC without chitosan lactate; it increased to 15.8% for CPC containing 15% chitosan lactate. The work-of-fracture was increased by more than ten times. The novel strong and non-rigid CPC may provide compliance for tooth mobility without fracturing the implant, and may also extend the use of CPC into the repair of larger defects in stress-bearing locations.