Injectability evaluation of tricalcium phosphate bone cement

Abstract

Calcium phosphate cements are biomaterials made from a mixture of calcium phosphate powder in aqueous solutions that forms a paste that reacts at the body temperature and hardens as a result of precipitation reactions. These cements are commonly used in dentistry and orthopedic bone filling surgeries, which require extremely invasive procedures. The challenge consists in formulating an injectable paste by additives incorporation. In this work, three different additives (carboxymethylcellulose, agar polymer and sodium alginate) were incorporated to tricalcium phosphate, in concentrations of 0.4, 0.8, 1.6, 3.2 and 6.4 wt.%. Injectability was evaluated through a new method developed for this purpose. Results showed that it was possible to obtain injectable compositions of alpha-tricalcium phosphate cement. It was verified that the injectability depends on the rheological behavior of the pastes and injection time. In this study, pastes with viscosity suitable for good homogenization and injection were obtained.

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.…”

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: (6) As seen from the amount of publications, α-TCP is the most popular compound to produce self-setting single-phase calcium orthophosphate formulations.…”

“…These additives promote dissolution of the initial solids by lowering the solution pH. In such cases, a setting time in the range of 10-15 min can be obtained [193][194][195][196][197][198][199][200][201]238]. The influence of soluble orthophosphates (e.g., Na 2 HPO 4 or NaH 2 PO 4 ) on the setting time is explained by the fact that dissolution of DCPA and formation of CDHA during setting occur in a linear fashion, thus avoiding early formation of CDHA.…”

“…For example, an appropriate cohesion was achieved when no disintegration of the paste was observed in the fluid [153,308]. This can be accomplished by keeping a high viscosity for self-setting pastes [22] or using cohesion promoters (e.g., 1% aqueous solution of sodium alginate [200,310,311], as well as other chemicals [200,[312][313][314] (Table 3) are not injectable and blood must be kept away from the implanting site until setting [4,5]. A poor cohesion has been associated to a poor biocompatibility that might lead to inflammatory reactions [309].…”

Alpha-tricalcium phosphate cement in the reconstruction of bone defects in rats

“…Calcium phosphate cements (CPCs) have been widely used for facial reconstruction because of some important characteristics: biocompatibility (their chemical composition is similar to that of mineral bone); bioactivity; osteoconductivity; easy handling and molding (and therefore the possibility of intraoperative preparation and optimal adaptation to the defect); direct contact with bone tissue since the first stages of implantation; and in situ-setting ability, without heating, which prevents tissue necrosis at the implantation site [2][3][4] . Jackson and Yavuzer 5 have considered CPC to be the most promising and well-tolerated alloplastic biomaterial currently available.…”