Histocompatibility evaluation of combination of gypsum with carbonated hydroxyapatite as bone substitutes in subcutaneous tissue

Abstract

Combination of gypsum with carbonated hydroxyapatite (CHA) has shown to improve bone healing process. Soft
tissue biocompatibility test is required prior to clinical application of bone substitutes since the materials contact
with the soft tissues upon application and can cause severe inflammatory response. The aim of this study was to
evaluate histocompatibility of gypsum compared to combination of gypsum-CHA in subcutaneous tissue. Disks of
gypsum and gypsum-CHA were implanted on paravertebral subcutaneous tissue of 25 male Wistar rats. Histological
section were stained with Hematoxylin Eosin then evaluated and scored with a histological grading scale for softtissue
implants. A two-way ANOVA was used to analyze the histomorphometrical results with 95% confidence
interval (p<0.05). The results showed that acute inflammatory cells were found in both groups at 6 hour and on day
5 and 7 after implantation at similar level. Chronic inflammatory cells and capsule were observed on day 7, 14, and
21. Moreover, there was no significant difference (p>0.05) of histomorphometrics score between both implants in
each implantation periods. It could be concluded that histocompatibility level of gypsum and combination of gypsum-
CHA to soft tissue was the same until day 21 iof mplantation.
Key words: gypsum - carbonated hydroxyapatite – biocompatibility – histocompatibility - subcutaneous implant