Effect of Sintering Temperature on Biphasic Calcium Phosphate (BCP) Biocomposite

Kasim, Shah Rizal; Muhamad, Nor Firdaus; Ramakrishan, Sivakumar

doi:10.4028/www.scientific.net/amr.1087.475

Cited by 1 publication

(6 citation statements)

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“…However, we found that the group with peak temperature lasting for 2 hours at 1250 °C showed the highest strength, both at ultimate and at fracture point. As previously shown by other authors [ 14 , 15 , 16 ], the ultimate stress achieved by samples that were sintered at the peak temperature of 1250 °C for longer times was significantly lower. This was shown to be due, for times longer than 2 hours at peak temperatures above 1200 °C, to allotropic transformation of TCP from β to α phase, shown to occur by XRD; in fact, the α phase is brittle and with reverse transformation, is not totally achieved during cooling to room temperature [ 14 , 16 ].…”

Section: Discussionsupporting

confidence: 80%

“…Compressive strengths of cancellous bone were found in the range of 2–12 MPa [ 50 , 51 ], depending on the skeletal site; thus, developing constructs as scaffolds with mechanical strength similar to the hosting bone is of paramount importance. Indeed, mechanical properties of BCP biomaterials have been studied for several years in order to increase their performance after grafting in jawbone [ 11 , 12 , 13 , 16 , 17 , 18 , 19 ]. The mechanical testing performed in the present study did not show a relevant variability depending on the time of permanence at the peak temperature for samples of groups at T = 1200 °C; conversely, for groups at T = 1250 °C, yield, ultimate, and fracture stresses seemed to decrease as the duration of the sintering increased.…”

Section: Discussionmentioning

confidence: 99%

“…In this context, the formation of α-TCP was shown to be responsible for the reduction of the hardness value of BCP biocomposites [ 16 ], hitherto making the use of temperatures above 1200 °C for sintering of scaffolds used for severe alveolar bone defects challenging. Nevertheless, while some authors showed that the key experimental variables to monitor during the allotropic α↔β-tricalcium phosphate phase transformations included the composition of the starting Ca/P ratio, the maximum heat treatment temperatures, and the cooling rates [ 52 ], no studies evaluated the inference of the sintering time at peak temperature, as we did in the present experiment.…”

Section: Discussionmentioning

confidence: 99%

“…When producing BCPs by sintering, different process regimes allow the modification of scaffold performances in customized ways, once grafted in a patient bone defect. In particular, modulation of sintering temperature was shown to change the BCP biocomposite characteristics (phase’s formation, porosity, and hardness properties) [ 14 ], also using mathematical and digital models [ 15 , 16 ]. Sintering temperature was shown to influence the formation of α-tricalcium phosphate (α-TCP; α-Ca 3 (PO 4 ) 2 ), affect the 3D porosity of the samples [ 14 , 16 ], and possibly reduce the biomaterial hardness, consequently affecting performance in patients.…”

Section: Introductionmentioning

confidence: 99%

“…In particular, modulation of sintering temperature was shown to change the BCP biocomposite characteristics (phase’s formation, porosity, and hardness properties) [ 14 ], also using mathematical and digital models [ 15 , 16 ]. Sintering temperature was shown to influence the formation of α-tricalcium phosphate (α-TCP; α-Ca 3 (PO 4 ) 2 ), affect the 3D porosity of the samples [ 14 , 16 ], and possibly reduce the biomaterial hardness, consequently affecting performance in patients. In particular, it was shown that despite an ideal porosity, there is no bone growth on α-TCP scaffolds because of its rapid dissolution, making the environment near the surface of the biomaterial more acidic [ 17 ].…”

Section: Introductionmentioning

confidence: 99%

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Integrated 3D Information for Custom-Made Bone Grafts: Focus on Biphasic Calcium Phosphate Bone Substitute Biomaterials

Giuliani

Gatto

Gobbi

et al. 2020

IJERPH

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Purpose: Several studies showed that the sintering temperature of 1250 °C could affect the formation of α-Ca3(PO4)2, which is responsible for the reduction of the hardness value of biphasic calcium phosphate biocomposites, but they did not evaluate the inference of the sintering time at peak temperature on transition of β-Ca3(PO4)2 to α-Ca3(PO4)2. This analysis explored, in an innovative way, inferences and correlations between volumetric microstructure, mechanical properties, sintering temperature, and time at peak temperature in order to find the best sintering conditions for biphasic calcium phosphate composites grafted in severe alveolar bone defects. Methods: Sintered biphasic calcium phosphates (30%-hydroxyapatite/70%-tricalcium phosphate) were tested by microCT imaging for the 3D morphometric analysis, by compressive loading to find their mechanical parameters, and by X-ray diffraction to quantify the phases via Rietveld refinement for different sintering temperatures and times at the peak temperature. Data were analysed in terms of statistical inference using Pearson’s correlation coefficients. Results: All the studied scaffolds closely mimicked the alveolar organization of the jawbone, independently on the sintering temperatures and times; however, mechanical testing revealed that the group with peak temperature, which lasted for 2 hours at 1250 °C, showed the highest strength both at the ultimate point and at fracture point. Conclusion: The good mechanical performances of the group with peak temperature, which lasted for 2 hours at 1250 °C, is most likely due to the absence of the α-Ca3(PO4)2 phase, as revealed by X-ray diffraction. However, we detected its presence after sintering at the same peak temperature for longer times, showing the time-dependence, combined with the temperature-dependence, of the β-Ca3(PO4)2 to α-Ca3(PO4)2 transition.

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