Effect of aPDT during alveolar repair: animal study

Objective: The objective of this study was to perform microscopic and molecular analyses of alveolar repair process in rats after antimicrobial photodynamic therapy (aPDT). Methods: Eight-four Wistar male rats were divided in 4 groups (n=21): C/untreated socket (control); PS+L/socket treatment with physiologic saline solution and low intensity laser therapy (660nm, 50J/cm2); TBO/socket treatment with topic application of toluidine blue-O (100µg/mL) and aPDT/socket treatment with topic application of toluidine blue-O (100µg/mL) and low intensity laser therapy (660nm, 50J/cm2). They were anesthetized and had their upper right incisor extracted. Each group was subdivided (n=7) and sacrificed at postoperative periods: 6/15/28 days. Laser thermal variation was carried out to confirm the absence of significant thermal effect (> 10 °C) in the incisor socket of one extra animal (PS+L= 2.16°C; aPDT= 4.22°C). Quantitative and qualitative microscopic analyses were performed to evaluate the connective/bone tissues, vessels, clot blood, inflammatory infiltrate. A quantitative analysis was performed using Real-Time/PCR to evaluate the gene expressions: collagen type I (COL-I), osteocalcin (OCN), alkaline phosphatase (ALP), runt-related transcription factor 2 (RUNX2) and vascular endothelial growth factor (VEGF) in the alveolar repair process. Results: The results have not showed significant differences among the groups either for microscopic or molecular analysis (ANOVA/two-way/p> 0.05). Positive correlation was found between blood clot and VEGF (Pearson/p<0.000) and negative correlations between bone tissue and ALP (Pearson/p=0.028), and blood vessels and VEGF (Pearson/p=0.018). Conclusions: It could be concluded that aPDT has not negatively affected the socket repair. Moreover, VEGF acted as angiogenesis molecular marker during socket bone neoformation and alkaline phosphatase as indicator of early bone neoformation.