Efectos de la administración local de pth 1-34 a bajas dosis en un modelo experimental de periodontitis: estudio piloto

Abstract

Periodontitis is a chronic and highly prevalent disease that induces a progressive loss of alveolar bone (HA) that, over time, leads to the loss of the tooth. Current treatments are quite inefficient. Intermittent administration of PTH has anabolic and anti-inflammatory effects, two properties necessary to achieve bone recovery. Periodontitis can be experimentally induced in rats in a few days by placing a cotton thread ligature in the gingival sulcus around the neck of the mandibular first molar, this increases the accumulation of biolm and damage to the gingival epithelium, activating osteoclastogenesis and the bone loss. Our objective was to evaluate if the intermittent administration of low doses (to avoid systemic effect) of PTH 1-34 in rats can block the loss of HA observed in the experimental periodontitis model. Twenty-four female Wistar rats (221±15 g) with normal dentition were used. Periodontitis was induced in 16 rats under light anesthesia while 8 rats did not undergo the procedure and were taken as healthy controls (C). The ligature was replaced every 4 days. The 16 animals with ligation were randomly divided into two groups that were injected locally subcutaneously every 48 h for 18 days with: G1 saline solution and G2 1.2 μg of PTH 1-34. After sacrifice, the right hemimandibles and tibiae were removed and were fixed in 10% formalin buffer for 48 h for histomorphometric analysis. Both tibiae and hemimandibles were decalcified by EDTA pH 7 for 45 days and then embedded in para na. Longitudinal cuts were made for the tibiae and mesodistal cuts for the hemimandibles. Sections were stained with H&E. Subchondral bone volume (BV/TV%) in tibias and interradicular HA and periodontal space height (PSA) were measured on photomicrographs (20x magnification, OLYMPUS CX31 Germany, Infinity1 Lumenera, Canada) using the software Image Pro plus 4.5. The BV/TV% was defined as the percentage of cancellous bone within the total area measured. Statistical analysis: Infostat software version 2020. Results (expressed as mean ± standard deviation, different letters indicate p<0.05): BV/TV% Tibias: C 38.77±2.59; G1 38.29±3.9 and G2 37.75±1.45. BV/TV% HA C 50.3±3.6c; G1 35.6±4.3a and G2 42.0±1.5b. AEP (mm): C 0.196±0.057a; G1 0.809±0.115b and G2 0.706±0.065c. The BV/TV% of the tibia show that the animals did not present systemic effects during the treatment with PTH 1-34. The HA of G2 shows a significant recovery of the trabecular bone while the AEP shows a small recovery of the HA but the bone tissue presents a higher percentage of osteoid compared to G1 (data not included in the summary). Conclusions: the intermittent administration of PTH 1-34 at low doses decreases the loss of HA but increases the formation of osteoid material, suggesting that this treatment attenuates the loss of HA resulting from experimental periodontitis, inducing the regeneration of bone tissue. UNRN grant: PI UNRN 40-A-467.