Chalcone T4, a novel chalconic compound, inhibits inflammatory bone resorption in vivo and suppresses osteoclastogenesis in vitro.

OBJECTIVE: This study aimed to assess the effect of a novel synthetic chalcone, Chalcone T4, on a murine model of periodontitis and on RANKL-induced osteoclastogenesis in vitro. BACKGROUND: Chalcones are natural compounds with anti-inflammatory properties, and its synthetic analogs with enhanced biological effects have potential as therapeutic agents. Periodontitis is characterized by chronic inflammation of the periodontium and alveolar bone resorption. Safe and effective anti-inflammatory agents can have an important additive effect in the treatment in this disease. METHODS: Periodontitis was induced via the installation of a ligature around the first molar. Rats (n = 32) received Chalcone T4 (5 and 50 mg/kg) or distilled water by gavage daily for 15 days. Outcomes assessed were bone resorption (µCT), TNF-α production (ELISA), cellular infiltrate, and collagen content (stereometric analysis, CD45+ cells by immunohistochemistry), and activation of NFATc1 and NF-kB (immunohistochemistry). In vitro, RAW 264.7 were treated with Chalcone T4 and stimulated with RANKL for assessment of osteoclast differentiation (actin ring staining) and activity (pit assay). RESULTS: Chalcone T4 significantly reduced periodontitis-associated bone resorption, as well as the cellular infiltrate, while increasing the collagen content. Production of TNF-α, infiltration of CD45-positive cells, and NF-kB activation were markedly reduced. In vitro, chalcone T4 inhibited both osteoclast differentiation and activity. CONCLUSION: Chalcone T4 significantly inhibited alveolar bone resorption and inflammation in vivo and RANKL-induced osteoclastogenesis in vitro, suggesting a therapeutic role for this compound in the treatment of periodontitis.

Antioxidant activity of apple extract protects against rat tongue carcinogenesis induced by 4-nitroquinoline 1-oxide.

Several studies have shown that apple (Malus sp.) has many components able to exert chemopreventive activity. The aim of this study was to evaluate the chemopreventive potential of apple extract following medium-term oral carcinogenesis assay induced by 4-nitroquinoline 1-oxide (4NQO) by means of histopathological analysis and gene expression of antioxidant enzymes, such as CuZnSOD, MnSOD and catalase. A total of 30 male Wistar rats were distributed into five groups, as follows (n = 6 per group): Group 1 - negative control group (non-treated group); Group 2 - received 4NQO during 8 weeks in drinking water and treated with apple extract by gavage between the 1st and 4th weeks daily (initiation phase); Group 3 - received 4NQO for 8 weeks in drinking water and treated with apple extract by gavage between the 5th and 8th weeks daily (promotion phase); Group 4 - received apple extract by gavage for eight consecutive weeks only; and Group 5 - received 4NQO for 8 weeks in drinking water daily. Histopathological analysis revealed that apple extract protect oral lesions induced by 4NQO at initiation or promotion phase. Higher gene expression of CuZnSOD and MnSOD enzymes were noticed in groups treated with apple extract as well. Taken together, our results demonstrate that the apple extract is able to modulate medium-term oral carcinogenesis assay as a result of antioxidant activity.

Wound healing of dehiscence defects following different root conditioning modalities: an experimental study in dogs.

OBJECTIVE: The purpose of this study was to investigate the periodontal healing pattern of dehiscence-type defects following different chemical root conditioning modalities. MATERIALS AND METHODS: Buccal osseous dehiscence defects were created on six teeth of seven dogs. After dental plaque accumulation, defects were treated with sterile saline solution (control group) or one chemical conditioning modality: citric acid (CA group), ethylenediaminetetraacetic acid (EDTA group), tetracycline (TTC group), citric acid + tetracycline (CA + TTC group), or tetracycline + citric acid (TTC + CA group). After 3 months of healing, clinical parameters were evaluated, and the animals were killed. Histological sections were processed, and a computer-assisted histometric analysis was used to evaluate the formation of new cementum, new bone, and epithelial apical migration. RESULTS: All treatments yielded significant improvements in terms of probing depth decrease and clinical attachment level gain compared to baseline values; however, without significant differences among the groups (p > 0.05; one-way ANOVA). The highest amount of new cementum was noted in the EDTA group (3.72 ± 0.83 mm, 77.6 %), while the lowest amount of new bone was observed in the TTC group (0.7 ± 0.94 mm, 14.3 %). However, no statistically significant differences could be observed among the groups regarding epithelial apical migration, new cementum, and alveolar bone formation (p > 0.05). CONCLUSION: Chemical root surface conditioning did not promote any significant improvement in periodontal healing pattern of dehiscence-type defects in dogs. CLINICAL RELEVANCE: Chemical root surface conditioning after surgical debridement did not promote positive or negative effects on periodontal healing pattern of dehiscence-type defects.

Different Molecular Weight Chitosan-Based Membranes for Tissue Regeneration.

Natural polymers, such as chitosan, obtained from chitin, are been widely studied for use in the tissue regeneration field. This study established a protocol to attain membranes made from this biopolymer, consisting of high or low molecular weight chitosan. The biocompatibility of these membranes was histologically evaluated, comparing them to collagen membrane surgically implanted in rat subcutaneous tissue. Fifteen Holtzmann rats were divided in three experimental groups: High and Low Molecular Weight Chitosan membranes (HMWC and LMWC) and Collagen membranes (C-control group); each of them with three experimental periods: 7, 15 and 30 days. As a result, after the seven days evaluation, the membranes were present and associated with a variable degree of inflammation, and after the 15 and 30 days evaluations, the membranes were absent in all groups. It is concluded that the chitosan-based membranes were successfully attained and presented comparable resorption times to collagen membranes.

Tecido ósseo: aspectos morfológicos e histofisiológicos / Bone issue: morphological and histophysiological aspects

O tecido ósseo tem papel importante no suporte, proteção e locomoção e está sob o controle de fatores sistêmicos, como os hormônios, e fatores locais, como os fatores de crescimentoe as citocinas. Portanto, os sistemas imune e esquelético encontram-se intimamente relacionados; aesta área interdisciplinar de estudos deu-se o nome de Osteoimunologia. A homeostase do sistema esquelético está na dependência de uma remodelação óssea equilibrada, ou seja, da dinâmicabalanceada entre a atividade dos osteoblastos, células de formação óssea, e osteoclastos, células de reabsorção óssea. Este balanço é firmemente controlado pelo sistema imune. Se este balanço inclinar-se a favor dos osteoclastos, levará a reabsorções patológicas, como nas periodontites,artrites reumatóides e doenças osteoporóticas. A compreensão deste processo, como um todo, podeser a chave para o desenvolvimento de um protocolo de tratamento que poderia levar ao equilíbrio dessas doenças ósseas. Sendo assim, nesta revisão da literatura, nós fornecemos uma visão do tecido ósseo: a composição química de sua matriz, células e componentes celulares, descrevendo como ocorre o processo de remodelação óssea e alguns fatores locais e sistêmicos que interferem neste processo, como citocinas e hormônios.

The bone tissue has an important role in the support, protection and locomotionand it is under control of systemic factors, such as hormones and local regulatory molecules, for instance, growth factor and cytokines. Therefore, the immune and skeletal systems are intimately related; this interdisciplinary branch has been referred as osteoimmunology. The homeostasis of the skeletal system depends directly on a balanced bone remodeling, i.e., the dynamic balance between the activities of the osteoblasts, bone forming cells and osteoclasts, bone resorbing cells.This balance is tightly and thoroughly controlled by some regulatory systems, such as the immune system. Tipping this balance towards the osteoclasts leads to pathological bone resorption, suchas periodontitis, autoimmune arthritis and osteoporotic diseases. The understanding this overallprocess may be the key to development of a treatment protocol, which could lead to the balance of these bone diseases. Thus, in this literature review, we provide an overview of the bone tissue composition, its cells and proteins of bone matrix, describing how the remodeling bone processoccurs, as well as some local and systemic factors that interfere in this process, such cytokines and hormones.