Reliability of new poly (lactic-co-glycolic acid) membranes treated with oxygen plasma plus silicon dioxide layers for pre-prosthetic guided bone regeneration processes

Abstract

Background: The use of cold plasmas may improve the surface roughness of poly(lactic-co-glycolic) acid (PLGA) membranes, which may stimulate the adhesion of osteogenic mediators and cells, thus accelerating the biodegradation of the barriers. Moreover, the incorporation of metallic-oxide particles to the surface of these membranes may enhance their osteoinductive capacity. Therefore, the aim of this paper was to evaluate the reliability of a new PLGA membrane after being treated with oxygen plasma (PO2) plus silicon dioxide (SiO2) layers for guided bone regeneration (GBR) processes.

Material and methods: Circumferential bone defects (diameter: 11 mm; depth: 3 mm) were created on the top of eight experimentation rabbits' skulls and were randomly covered with: (1) PLGA membranes (control), or (2) PLGA/PO2/SiO2 barriers. The animals were euthanized two months afterwards. A micromorphologic study was then performed using ROI (region of interest) colour analysis. Percentage of new bone formation, length of mineralised bone, concentration of osteoclasts, and intensity of ostheosynthetic activity were assessed and compared with those of the original bone tissue. The Kruskal-Wallis test was applied for between-group com Asignificance level of a=0.05 was considered.

Results: The PLGA/PO2/SiO2 membranes achieved the significantly highest new bone formation, length of mineralised bone, concentration of osteoclasts, and ostheosynthetic activity. The percentage of regenerated bone supplied by the new membranes was similar to that of the original bone tissue. Unlike what happened in the control group, PLGA/PO2/SiO2 membranes predominantly showed bone layers in advanced stages of formation.

Conclusions: The addition of SiO2 layers to PLGA membranes pre-treated with PO2 improves their bone-regeneration potential. Although further research is necessary to corroborate these conclusions in humans, this could be a promising strategy to rebuild the bone architecture prior to rehabilitate edentulous areas.

Figure 1

Intraoperatory picture.

Figure 2

Regenerated calvarial bone in the experimental group. Bone sample extracted from the skull after the healing period.

Figure 3

Morphometric analysis made under microscope at 2 months of follow-up. (a) TB image of the control group showing the lowest proportion of new bone formation. (b) TB image of the study group exhibiting bone in an advanced stage of formation. (c) VK image of the control group. (d) VK image of the study group confirming a larger formation of dense bone (Figs.: 2a-d; objective: 4×; bar: 250 µm; zoom: 1.5). (e) Calcein image of the control group. (f) Calcein image of the experimental group containing higher length of mineralised bone between the bone edge and the green line (Figs. 2e,f; objective: 20×; bar: 50 µm; zoom: 1.5). (g) TRAP image of the control group. (h) TRAP image of the study group with higher concentration of osteoclasts. (i) ALP image of the control group. (j) ALP image of the study group evidencing the highest ostheosynthetic activity (Figs.: 2g-j; objective: 5×; bar: 250 µm; zoom: 1.5).