Effect of local injection of injectable platelet-rich fibrin on bone remodeling during orthodontic tooth movement in dogs.

Background: This study aimed to assess the effect of local injection of injectable platelet-rich fibrin (i-PRF) on bone remodeling during orthodontic tooth movement in dogs. Materials and Methods: In this animal study, the maxillary first premolars of four adult male mixed-breed dogs were bilaterally extracted, and a nickel-titanium closed coil spring with 150 g force was placed between the canine and second premolar teeth. One quadrant of the maxilla was randomly selected as the test quadrant, and 0.5 cc i-PRF was injected into the periodontal ligament (PDL) around the second premolar at 1, 21, and 42 days. The other quadrant served as the control group and received saline injections. The dogs were sacrificed after 63 days, histological sections were prepared, and changes in bone remodeling were assessed by comparing the percentage of osteogenesis and number of osteoblasts and osteoclasts between the two groups by the Wilcoxon and Mann-Whitney U-tests (α = 0.05). Results: The percentage of osteogenesis (16.0% ± 4.96% in i-PRF and 13.5% ± 4.43% in the control), the percentage of newly formed lamellar bone (10.25% ± 2.87% in i-PRF and 8.75% ± 2.36% in the control), the percentage of woven bone (5.75% ± 2.21% in i-PRF and 4.75% ± 2.36% in the control), the number of osteoblasts (15.0 ± 3.46 in i-PRF and 11.75 ± 2.36 in the control), and the number of osteoclasts (11.25 ± 4.34 in i-PRF and 6.25 ± 2.62 in the control) were not significantly different between the two groups (P > 0.05). Conclusion: PDL injection of i-PRF around the second premolars of dogs under orthodontic force had no significant effect on bone remodeling.

Effect of local administration of injectable platelet-rich fibrin on root resorption during orthodontic tooth movement in dogs.

Background: This study aimed to assess the effect of local administration of injectable platelet-rich fibrin (i-PRF) on root resorption during orthodontic tooth movement in dogs. Materials and Methods: This animal study was conducted on 4 adult male mongrel dogs. The right and left maxillary first premolars of the dogs were extracted, and a Nickel-Titanium closed coil spring was used to connect the canine to the second premolar with 150 g load. Next, 0.5 cc of i-PRF was injected in one quadrant of the maxilla around the second premolar into the periodontal ligament. The other quadrant of the maxilla served as the control group and received saline injection. Injections were performed at 1, 21, and 42 days, and the dogs were sacrificed after 63 days. Histological sections were prepared and cementum resorption, secondary cementum formation, and number of cementoblasts and cementoclasts were compared between the two groups by the Friedman test, Wilcoxon test, and Mann-Whitney test (α = 0.05). Results: The mean percentage of cementum resorption (17.75% ± 5.56%) and secondary cementum formation (14.50% ± 6.65%), and the mean number of cementoblasts (10.25 ± 2.36) and cementoclasts (9.75 ± 4.71) were insignificantly higher in the i-PRF group than the corresponding values (13.75% ± 4.34%, 8.50% ± 2.88%, 7.75 ± 1.25, and 6.50 ± 3.10, respectively) in the control group (P > 0.05). Conclusion: Administration of i-PRF insignificantly increased the percentage of cementum resorption, secondary cementum formation, number of cementoblasts, and number of cementoclasts.

The effect of laser irradiation and doxycycline application on the production of matrix metalloproteinase-8 and collagen I from cultured human periodontal ligament cells.

BACKGROUND: Periodontal ligament fibroblasts (PDLF) play a key role in periodontal wound healing and tooth-supporting structures. Various approaches have been tried to enhance the fibroblastic activity such as laser irradiation or doxycycline application. The current study explored the influence of laser irradiation and doxycycline application on human PDLF. The aim of the study was the effect of low-level laser treatment and doxycycline application on the expression of collagen I and matrix metalloproteinase-8 (MMP8) from cultured human periodontal ligament cells. MATERIALS AND METHODS: In this experimental study After preparation of human PDLF in three replications, they were divided into five treatment groups. The first group was day 0, which was used for standardization. The second group was the control group, which received no treatment within 4 days of the study. The third group was treated with doxycycline 30, daily for 4 consecutive days. The fourth group was treated with diode laser 2 daily for 4 consecutive days. The fifth group was treated with both doxycycline and laser irradiation pertaining to the third and fourth groups. After 4 days of treatment, cells were tested for collagen I and MMP-8 secretion through real-time-polymerase chain reaction and ELISA reader. The data were analyzed using the ANOVA and least significant difference pair tests ( P < 0.05 ). RESULTS: Treatment of human PDLF either with diode laser or doxycycline reduced the secretion of MMP-8 significantly. The maximum reduction was related to doxycycline application. Regarding collagen, I, only doxycycline application significantly increased collagen I secretion. Other groups showed no significant increase in collagen I secretion. CONCLUSION: This study showed that treatment of human PDLF either with diode laser or doxycycline significantly reduced MMP-8. Treatment with doxycycline significantly increased the secretion of collagen I.