Efficacy of polyphasic calcium phosphates as a direct pulp capping material.
OBJECTIVE
Polyphasic calcium phosphates (Poly-CaP), a complex of hydroxyapatite (HAp) and soluble calcium phosphates including alpha-tricalcium phosphate and tetracalcium phosphate, demonstrate promoting effects on hard tissue formation by osteoblasts. We hypothesized that a Poly-CaP block with a soluble calcium phosphates phase on one side and an insoluble HAp phase on the other side is useful for vital pulp therapy as it may promote dentin regeneration and provide the surface effective to achieve sealing. The purpose of this study was to investigate the efficacy of Poly-CaP as a direct pulp capping material by examining the Ca-release profile, the in vivo ability to induce reparative dentinogenesis, and the bonding of HAp surface with adhesive systems.


METHODS
Poly-CaP prepared by annealing crude HAp disc was immersed in buffer solution at pH 7.4 or 4.0, and the concentration of Ca released was measured until 15 days. The pulp of 9-week-old Wister rat molar was exposed and capped with Poly-CaP or HAp block, and dentin bridge formation and pulpal inflammation was evaluated histopathologically after 2 or 4 weeks. Etch & rinse or self-etching adhesive was bonded to HAp surface, and the interface was observed using SEM.


RESULTS
Poly-CaP exhibited continuous release of Ca with significantly greater amount than HAp at both pH conditions (P<0.05, Student's t-test). Animal tests demonstrated formation of complete dentin bridge at higher rate for Poly-CaP compared with HAp after 4 weeks (P<0.05, Steel-Dwass test). Impregnation of resin into etched HAp surface, with production of intimate contact at the bonding interface, was seen for all adhesives.


CONCLUSIONS
Poly-CaP is a potentially useful material for direct pulp capping with the advantages to promote dentin bridge formation and to provide tight sealing by adhesives.
Kiba
Wakako
W
Department of Restorative Dentistry and Endodontology, Osaka University Graduate School of Dentistry, Suita, Japan.
Imazato
Satoshi
S
Takahashi
Yusuke
Y
Yoshioka
Seisuke
S
Ebisu
Sigeyuki
S
Nakano
Takayoshi
T
D000134:Acid Etching, Dental / Q000379:methods; D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry / Q000627:therapeutic use*; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002118:Calcium / Q000737:chemistry; D002130:Calcium Phosphates / Q000737:chemistry / Q000627:therapeutic use*; D001840:Dental Bonding; D003789:Dental Pulp Exposure / Q000628:therapy; D003809:Dentin, Secondary / Q000187:drug effects / Q000473:pathology; D017220:Dentin-Bonding Agents / Q000737:chemistry; D004058:Diffusion; D017886:Durapatite / Q000737:chemistry / Q000627:therapeutic use*; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D057872:Pulp Capping and Pulpectomy Agents / Q000737:chemistry / Q000627:therapeutic use*; D011671:Pulpitis / Q000145:classification; D051381:Rats; D017208:Rats, Wistar; D012038:Regeneration / Q000187:drug effects; D019279:Resin Cements / Q000737:chemistry; D013997:Time Factors; D016896:Treatment Outcome; D014961:X-Ray Diffraction
D001672:Biocompatible Materials; D002130:Calcium Phosphates; C503075:Clearfil Protect Bond; D017220:Dentin-Bonding Agents; C408584:Prompt L-Pop; D057872:Pulp Capping and Pulpectomy Agents; D019279:Resin Cements; C511238:Single Bond Plus; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; D017438:Bisphenol A-Glycidyl Methacrylate; D017886:Durapatite; D002118:Calcium