γ‐Radiation‐induced changes in structure and properties of tetracalcium phosphate and its derived calcium phosphate cement

Abstract

The purpose of the present study was to investigate the ␥-radiation effect on the structure and properties of the single-phase tetracalcium phosphate (TTCP) powder and its derived calcium phosphate cement (CPC). Experimental results show that low-dosed (0 -30 kGy) CPC has a setting time of 10 -12 min, while high-dosed (40 -120 kGy) CPC has a setting time of 8 -10 min. The low dose ␥-radiation does not significantly change porosity volume fraction or compressive strength of the CPC. The pH values of all CPC samples fell in a relatively narrow band, with a band width of 8.5-9.1 (in terms of pH value). With a dose of 10 or 20 kGy ␥-radiation, the TTCP-apatite conversion ratio does not change much. With 30 kGy the conversion ratio significantly increases and reaches a maximum value. With further increases in dose, the conversion ratio quickly declines. With increasing ␥-ray dose, the CPC morphology becomes more porous/loose and apatite particles become larger in size. When exposed to a high dose (120 kGy) of ␥-radiation, TTCP structure is radiation-damaged, and ␥-ray-induced formation of apatite is confirmed by transmission electron microscopic/selected-area diffraction/lattice imaging analyses.

Effect of Gamma Radiation on Properties of a Calcium Phosphate-Calcium Sulfate Composite Cement

“…At a dosage of 50 kGy or higher, however, the working time and setting time significantly decreased respectively from 5.5 and 7.0 min to 4.0 and 5.5 min (p < 0.05). According to an early study of Tsai et al, 23) the setting time of their £-ray-sterilized TTCPderived CPC decreased significantly at higher doses (40 120 kGy) due to radiation-induced defects and/or preferential growth of apatite crystals. Same explanation may apply to the observed decrease in working/setting times in the present study.…”

“…The non-sterilized sample had a significantly higher apatite conversion ratio (74%) than those of £-ray-sterilized samples (6467%), indicating that the exposure of the cement powder to £-ray had slowed down TTCP/DCPA-HA phase transformation process. Although the reason is not yet clear, one possible explanation is that the £-ray-induced apatite phase on the powder surface 23) may somewhat hinder the TTCP/DCPA-HA phase transformation.…”

Self-Setting Calcium Orthophosphate Formulations

“…Due to the fact, that only one calcium orthophosphate is used; the solid part of such formulations might be called as a single-phase (or single-component) cement powder [192]. Self-setting formulations made of ACP + an aqueous solution [193,194], α-TCP + an aqueous solution [23,24,27,195,196,197,198,199,200,201,202,203], β-TCP + an aqueous solution [199,204], DCPA + an aqueous solution [40], CDHA + an aqueous solution [41], OCP + an aqueous solution [42], TTCP + an aqueous solution [43,205,206] or γ-radiated TTCP + an aqueous solution [207,208,209] are the typical examples; the majority of them are re-crystallized to CDHA during setting: Ca x H y (PO 4 ) z · n H 2 O + H 2 O → Ca 10- x (HPO 4 ) x (PO 4 ) 6- x (OH) 2- x + n H 2 O 3(α- or β-)Ca 3 (PO 4 ) 2 + H 2 O = Ca 9 (HPO 4 )(PO 4 ) 5 (OH) 3Ca 4 (PO 4 ) 2 O + 3H 2 O = Ca 9 (HPO 4 )(PO 4 ) 5 (OH) + 3Ca(OH) 2 …”

Self-Setting Calcium Orthophosphate Formulations: Cements, Concretes, Pastes and Putties

“…Due to the fact, that only one calcium orthophosphate is used; the solid part of such formulations might be called as a single-phase (or single-component) cement powder [168]. Cements made of ACP + an aqueous solution [169,170], α-TCP + an aqueous solution [171][172][173][174][175][176][177][178], β-TCP + an aqueous solution [175,179], DCPA + an aqueous solution [24], CDHA + an aqueous solution [25], TTCP + an aqueous solution [26,180,181] or γ-radiated TTCP + an aqueous solution [182][183][184] The experimental details on TTCP hydrolysis under a near-constant composition condition might be found elsewhere [185]. The details on α-TCP hydrolysis are also available.…”