Hyaluronic acid on collagen membranes: An experimental study in rats.

OBJECTIVE: The aim of this study was to evaluate the effect of hyaluronic acid (HA) in the structure and degradation patterns of BioGide® and OsseoGuard™ collagen membranes. HA mediates inflammation and acts in cell migration, adhesion, and differentiation, benefitting tissue remodeling and vascularization. These are desirable effects in guided regeneration procedures, but it is still unknown whether HA alters the barrier properties of absorbable membranes. DESIGN: Bone defects were created in the calvaria of rats, which were treated with HA gel 1% (HA group) or simply filled with blood clot (control group), and covered with BioGide® or OsseoGuard™. The animals were euthanized after 1, 30, and 60days, and their calvarias were processed for histological analysis. RESULTS: BioGide®, in both HA and control groups, showed vascularization, intense cell colonization, bone formation, and tissue integration at 30 and 60days. In contrast, Osseoguard™ presented minimal cellular colonization, and inflammatory reaction associated to foreign body reaction in both time points and groups. The HA group of BioGide® showed higher cell colonization (574.9±137.6) than the control group (269.1±70.83) at 60days (p<0.05). Despite this finding, the structure and degradation pattern were similar for BioGide® and Osseoguard™ in the HA and control groups. CONCLUSION: The results suggest that HA did not interfere with tissue integration and structural degradation of BioGide® and Osseoguard™ membranes.

Stromal myofibroblasts in focal reactive overgrowths of the gingiva

Focal reactive overgrowths are among the most common oral mucosal lesions. The gingiva is a significant site affected by these lesions, when triggered by chronic inflammation in response to microorganisms in dental plaque. Myofibroblasts are differentiated fibroblasts that actively participate in diseases characterized by tissue fibrosis. The objective of this study was to evaluate the presence of stromal myofibroblasts in the main focal reactive overgrowths of the gingiva: focal fibrous hyperplasia (FFH), peripheral ossifying fibroma (POF), pyogenic granuloma (PG), and peripheral giant cell granuloma (PGCG). A total of 10 FFHs, 10 POFs, 10 PGs, and 10 PGCGs from archival specimens were evaluated. Samples of gingival mucosa were used as negative controls for stromal myofibroblasts. Oral squamous cell carcinoma samples, in which stromal myofibroblasts have been previously detected, were used as positive controls. Myofibroblasts were identified by immunohistochemical detection of alpha smooth muscle actin (α-sma). Myofibroblast immunostaining was qualitatively classified as negative, scanty, or dense. Differences in the presence of myofibroblasts among FFH, POF, PG, and PGCG were analyzed using the Kruskal-Wallis test. Stromal myofibroblasts were not detected in FFH, POF, PG, or PGCG. Consequently, no differences were observed in the presence of myofibroblasts among FFH, POF, PG, or PGCG (p > 0.05). In conclusion, stromal myofibroblasts were not detected in the focal reactive overgrowths of the gingiva that were evaluated, suggesting that these cells do not play a significant role in their pathogenesis.

Processos proliferativos não neoplásicos gengivais / Focal reactive overgrowths of the gingiva a review of the literature

A mucosa gengival pode desenvolver processos proliferativos não neoplásicos secundários ao processo inflamatório desencadeado pela ação de irritantes locais. Entre esses processos, destacam-se hiperplasia fibrosa focal, granu- loma piogênico, fibroma ossificante periférico e lesão periférica de células gigantes. 0 objetivo desta revisão foi abordar etiopatogenia, características clínicas, características histopatológicas, tratamento e prognóstico destas lesões, enfatizando a importância do conhecimento destes processos patológicos para a prática clínica odontológica.