Avaliação do reparo tecidual em defeitos ósseos críticos preenchidos com biomaterial matriz de PLGA/rhGH e submetidos a terapia com LLLT : estudo em ratos

Abstract

(Artigo 1 : The use of growth hormone in bone regeneration : review of the literature) The present study had the objective of reviewing the literature on the use of Growth Hormone in bone regeneration. It was done a search in the PubMed database with the following mesh terms: "Growth hormone", "bone regeneration", "Dentistry", with the Boolean operator "AND". We also consulted the Cochrane database, in which no study was found. We found 33 articles and after reading the titles and abstracts and applying the inclusion and exclusion criteria, 11 studies were selected. These articles were grouped in the following categories: use of GH in osseointegration and use of GH in bone repair. Data were tabulated according to the type of sample, usage form of GH and time of observation. Analyzing the selected articles, it has been observed that the mode of GH use in most studies is topical and doses range from 2UI to 4UI. Most studies have evaluated the effect of GH on Peri-implant bone healing, with only 3 of these articles evaluating this effect in cases of osteogenic distraction, and only one study was performed on critical bone defects by administering GH in a systemic way. Within the limits of this review, it has been observed that GH has been shown to be a good alternative to accelerate bone regeneration. (Estudo 2 : Assessment of tissue repair in critical bone defects filled with matrix biomaterial of PLGA/rhGH and submitted to LLLT therapy : study in rats) This study evaluated bone regeneration in critical bone defects filled with a polymeric biomaterial and submitted to the application of low-power laser (LLLT). The biomaterial was made with PLGA, a copolymer derived from lactic acid (PLA) and glycolic acid (PGA), and recombinant human growth hormone (rhGH). Thirty-six male Wistar rats were divided into two groups (GI: without LLLT and GII: with LLLT), each group had 3 subgroups (7, 14 and 21 days, with 6 animals each). In the cranial bone of each animal, 2 critical bone defects were made, where one of the defects was filled by the biomaterial and the other by a blood clot (control). At the end of the surgical procedure, group II received the first dose of LLLT. Irradiation was performed every 48 hours, in a total of 7 application sessions, during the period of 15 days, totaling 70 J/cm2. The results showed that: the cavities with biomaterial presented a greater area of regenerated tissue than the control cavities, but this difference was not statistically significant; and Group I, no laser, showed a lower percentage of regeneration in relation to the group that received LLLT except at 14 days. Thus, it is possible to consider the use of the proposed biomaterial for the regeneration of critical bone defects, both in association with laser therapy and isolated.