Microbial contamination of dental graft materials according to post-opening storage conditions: an experimental in vitro study

Purpose: The aim of this study was to evaluate whether opened allogeneic bone grafts are subjected to microbial contamination under different storage conditions. Materials and Methods: In this experimental in vitro study, a total of 50 allogeneic bone graft samples were evaluated. The samples were divided into four experimental groups (n = 10) and one control group (n = 10). To simulate potential exposure during clinical use, all graft containers were opened in the same surgical environment and exposed to ambient conditions for approximately 30 seconds. The samples were then assigned to four different storage conditions: Group 1 (open lid, 25°C), Group 2 (closed lid, 25°C), Group 3 (closed lid and placed inside a sterilization pouch at +4°C), and Group 4 (open lid at +4°C). The grafts in the control group were kept unopened in the manufacturer’s original packaging. All samples were microbiologically evaluated after 15 days, and culture analyses were performed using Sheep Blood Agar, Eosin Methylene Blue Agar, and Sabouraud Dextrose Agar. Results: Among the 50 samples analyzed, bacterial growth was detected in only one sample (2%). Microbial growth was observed exclusively in Group 1, where grafts were stored with the lid open at room temperature, corresponding to a growth rate of 10% (1/10) in this group. The growth was observed only on Sheep Blood Agar and was phenotypically identified as Staphylococcus spp. Conclusion: The findings of this study suggest that opened allogeneic bone grafts generally present a low risk of microbial contamination under short-term storage conditions.