Abstract
Delayed postoperative infection is known as a major complication after bone surgeries using osteosynthetic biomaterial such as titanium (Ti) and bioresorbable organic materials. However, the precise cause of this type of infection is still unclear and no effective prevention has been established. The purpose of this study is to investigate the effect of irradiation with a 405 nm blue-violet laser on the bacteria adhered on the Ti and hydroxyapatite-poly-L-lactic acid- (HA-PLLA) based material surfaces and to verify the possibility of its clinical application to prevent the delayed postoperative infection after bone surgeries using osteosynthetic biomaterial. The suspension of Staphylococcus aureus FDA 209P was delivered onto the surface of disks composed of Ti or HA-PLLA. Bacterial adhesion on each disk was observed using a scanning electron microscope (SEM). After thorough washing with distilled water, the growth of bacteria attached to the material surfaces was examined with an alamar blue-based redox indicator. Moreover, a bactericidal effect of 405 nm blue-violet laser irradiation on residual bacteria on both materials was investigated using colony-forming assay. As a result, there was no significant difference in the bacterial adhesion between Ti and HA-PLLA materials. In contrast, 45 J/cm2 of irradiation with 405 nm blue-violet laser inhibited the bacterial growth at approximately 93% on Ti disks and at approximately 99% on HA-PLLA disks. This study clearly demonstrated the possibility that the irradiation with a 405 nm blue-violet laser is useful as an alternative management strategy for the prevention of delayed postoperative infection after bone surgeries using osteosynthetic biomaterials.
Highlights
Several types of biomaterials including titanium (Ti) and bioresorbable materials such as poly-L-lactic acid (PLLA) are used for osteosynthesis in the fields of orthopedics and craniomaxillofacial surgery [1, 2]
In 2006, new biomaterial for osteosynthesis was developed, which was composed of incalescent/unsintered hydroxyapatite (u-HA) particles and PLLA, and has been commonly used due to (1) its better osteoconductivity [7,8,9,10], (2) no need for secondary surgery to remove the materials [11, 12], (3) no restriction to bone growth in young patients [13,14,15], and (4) no elution of metal ions that could act as allergens [16,17,18,19]
The surface of Ti was relatively smooth and micropores were found in some places, while that of hydroxyapatite-poly-L-lactic acid- (HA-PLLA) was comparatively rougher with interspersed white particulates that seemed to be HA crystals (Figure 1)
Summary
Several types of biomaterials including titanium (Ti) and bioresorbable materials such as poly-L-lactic acid (PLLA) are used for osteosynthesis in the fields of orthopedics and craniomaxillofacial surgery [1, 2]. PLLA is one of representative bioresorbable materials, which is hydrolyzed by moisture in the environment, resulting in a decrease in the molecular weight and ultimate decomposition of the material into carbon dioxide and water. For this property, PLLA has been used as a source reagent of bioresorbable osteosynthetic materials since the 1990s [5, 6]. In 2006, new biomaterial for osteosynthesis was developed, which was composed of incalescent/unsintered hydroxyapatite (u-HA) particles and PLLA, and has been commonly used due to (1) its better osteoconductivity [7,8,9,10], (2) no need for secondary surgery to remove the materials [11, 12], (3) no restriction to bone growth in young patients [13,14,15], and (4) no elution of metal ions that could act as allergens [16,17,18,19].
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