Degradation characteristics of α and β tri‐calcium‐phosphate (TCP) in minipigs

Abstract

In seven Goettingen minipigs 3.5--4.7-ml cancellous bone defects were created in the area of the tibial head on both sides. The defects were filled with alpha-TCP or beta-TCP (tricalciumphosphate). ITI implants (Straumann, Freiburg, Germany) of 3.2 x 12-mm length were inserted into the underlying ceramic substitutes. Two additional pigs were used as control. Within the periods of observation (4, 16, 20, 28, 46, 68, and 86 weeks) fluorescent dyes were applied. Nondecalcified thin-sliced sections were examined by means of light and fluorescence microscopy. In addition microangiography and microradiography were performed. Bony regeneration occurred basally and on the sides of the defect according the angiogenetic reossification pattern. Resorption was due to a hydrolytic and cellular degradation process. After 46 weeks histomorphological evaluation showed an incomplete osseointegration of the simultaneously implanted dental implants. The bone contact surface ratio was lower than 25%. After 86 weeks 95--97% of both alpha- and beta-TCP were resorbed. Ceramic residuals stayed within the newly formed trabeculae thus resisting further degradation until remodeling occurred. Both alpha- and beta-TCP show a comparable degradation process. At the 86-week postoperative point only small residuals of the ceramic can be found. These residuals stay within the newly formed trabeculae, which show a functional orientation. In comparison control defects showed only sparse reossification. The beta-TCP material shows an accelerated degradation mode and has an optimal reactivity with the surrounding tissues. According to the results of this animal experiment both materials can be classified as bone-rebuilding materials.

Effect of grain size and microporosity on the in vivo behaviour of β-tricalcium phosphate scaffolds

“…Nevertheless, it is important to mention that α-TCP is expected to convert to calcium-deficient hydroxyapatite (CDHA) once implanted, and that CDHA has a solubility very close to that of β-TCP (Driessens and Verbeeck, 1990;Liu et al, 1999). In addition, there is evidence showing that the composition does not play much of a role in the present animal model and that α-TCP and β-TCP have similar in vivo behaviours (Wiltfang et al, 2002).…”

Evaluation of Bone Regeneration by porous Alpha-Tricalcium Phosphate/Atelocollagen Sponge Composite in Critical-Sized Rat Calvarial Defects

“…-tricalcium phosphate ( -TCP, -Ca 3 (PO 4 ) 2 ) is receiving growing attention as a raw material for several injectable hydraulic bone cements, biodegradable bioceramics and composites for bone repair 8) . -TCP particles have outstanding bone regeneration ability, but the -TCP material tends to remain in the defect, which can lead to severe inflammatory response or delaying bone healing [9][10][11] .…”

Interlaboratory studies on in vitro test methods for estimating in vivo resorption of calcium phosphate ceramics

“…Resorbable calcium phosphates include β-tricalcium phosphate (β-TCP), α-tricalcium phosphate, carbonated hydroxyapatite, low-crystalline hydroxyapatite, and a certain range of biphasic hydroxyapatite and β-TCP. These calcium phosphates are not only osteoconductive but are also gradually resorbed in a long period of time after implantation [1][2][3][4][5][6][7][8][9][10]. The rate of resorption needs to be optimized depending on the intended purpose and be balanced with bone tissue regeneration for successful clinical treatments.…”