Metallic crown-induced occlusal trauma as a protocol to evaluate inflammatory response in temporomandibular joint and periodontal tissues of rats.

OBJECTIVES: The goal of this study is to propose a standard protocol of experimental occlusal trauma to evaluate the inflammatory hyperalgesia induced by metallic crowns on orofacial tissues of rats. MATERIALS AND METHODS: Thirty animals were randomly divided into six groups (n = 5 per group). Detailed methodology on the manufacturing of metallic crowns is described. The inflammatory hyperalgesia induced by occlusal interference was evaluated by intra-articular injection of a low dose of 0.5% formalin (30 µl) or vehicle (saline) into temporomandibular joint, 21 or 28 days after metallic crown cementation. Posteriorly, pro-inflammatory cytokines were evaluated by enzyme-linked immunosorbent assay to assess the effect of occlusal interference on periodontium. RESULTS: The cementation of metallic crowns with dental anatomy on the lower molar of rats does not show signs of stress and lack of feeding. Metallic crown-induced occlusal trauma results in a temporomandibular joint inflammatory hyperalgesia (P < 0.05: ANOVA, Tukey's test). Otherwise, it was observed that occlusal trauma results in the increase of protein level of pro-inflammatory cytokines TNF-alpha and IL-1beta in the gingival tissues (P < 0.05). CONCLUSION: This study demonstrates in detail a methodology of occlusal trauma resulting from the cementation of metallic crowns in the lower molars of rats, mimicking occlusal interferences commonly evaluated in the dental clinic. This methodology makes new studies to better understand the mechanisms involved in the occlusal trauma of orofacial tissues possible. CLINICAL RELEVANCE: The standardization of an experimental occlusal interference model will allow us to understand the deleterious effect and mechanisms that affect the orofacial tissues.

Influence of salivary washout on drug delivery to the oral cavity using coated microneedles: An in vitro evaluation.

The objective of this study was to determine whether in buccal tissues, after insertion and removal of coated microneedles, the presence of saliva over the insertion site can lead to loss of the deposited drug, and if saliva can influence in vitro permeation of the drug across the tissue. Microneedles were coated with sulforhodamine (SRD), which was used as a model drug, and inserted in to porcine buccal mucosa in vitro. Fluorescence microscopy was used to study microneedle coating quality and the diffusion of SRD through the mucosa. Permeation experiments were conducted for simulated dynamic or static salivary flow by adding 100µL/h or 100, 200 or 300µL of phosphate buffered saline (PBS) in the donor compartment of the Franz diffusion cells, into which buccal tissue after insertion of SRD-coated microneedles was placed. Microscopy showed that microneedles were uniformly coated with SRD and that SRD was successfully delivered in to the mucosa. Some SRD remained in the tissue even after 24h, despite presence of PBS on top of the coated microneedle insertion site. It was found that salivary washout can result in loss of drug that has been deposited in oral cavity mucosal tissues using coated microneedles, and presence of fluid over the coated microneedle insertion site can increase flux across the tissue. Thus, it is advisable to include salivary flow during in vitro studies related to the use of coated microneedles for drug delivery to the oral cavity in order to not obtain misleading results.

15d-PGJ2-Loaded Solid Lipid Nanoparticles: Physicochemical Characterization and Evaluation of Pharmacological Effects on Inflammation.

15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2), a peroxisome proliferator-activated receptor-γ (PPAR-γ) agonist, has physiological properties including pronounced anti-inflammatory activity, though it binds strongly to serum albumin. The use of solid lipid nanoparticles (SLN) can improve therapeutic properties increasing drug efficiency and availability. 15d-PGJ2-SLN was therefore developed and investigated in terms of its immunomodulatory potential. 15d-PGJ2-SLN and unloaded SLN were physicochemically characterized and experiments in vivo were performed. Animals were pretreated with 15d-PGJ2-SLN at concentrations of 3, 10 or 30 µg·kg-1 before inflammatory stimulus with carrageenan (Cg), lipopolysaccharide (LPS) or mBSA (immune response). Interleukins (IL-1ß, IL-10 and IL-17) levels were also evaluated in exudates. The 15d-PGJ2-SLN system showed good colloidal parameters and encapsulation efficiency of 96%. The results showed that the formulation was stable for up to 120 days with low hemolytic effects. The 15d-PGJ2-SLN formulation was able to reduce neutrophil migration in three inflammation models tested using low concentrations of 15d-PGJ2. Additionally, 15d-PGJ2-SLN increased IL-10 levels and reduced IL-1ß as well as IL-17 in peritoneal fluid. The new 15d-PGJ2-SLN formulation highlights perspectives of a potent anti-inflammatory system using low concentrations of 15d-PGJ2.

ß-Glucans (Saccharomyces cereviseae) Reduce Glucose Levels and Attenuate Alveolar Bone Loss in Diabetic Rats with Periodontal Disease.

The objective of this study was to assess the effects of oral ingestion of ß-glucans isolated from Saccharomyces cereviseae on the metabolic profile, expression of gingival inflammatory markers and amount of alveolar bone loss in diabetic rats with periodontal disease. Diabetes mellitus was induced in 48 Wistar rats by intraperitoneal injection of streptozotocin (80 mg/kg). After confirming the diabetes diagnosis, the animals were treated with ß-glucans (by gavage) for 28 days. On the 14th day of this period, periodontal disease was induced using a ligature protocol. ß-glucans reduced the amount of alveolar bone loss in animals with periodontal disease in both the diabetic and non-diabetic groups (p < 0.05). ß-glucans reduced blood glucose, cholesterol and triacylglycerol levels in diabetic animals, both with and without periodontal disease (p < 0.05). Furthermore, treatment with ß-glucans reduced the expression of cyclooxygenase-2 and receptor activator of nuclear factor kappa-B ligand and increased osteoprotegerin expression in animals with diabetes and periodontal disease (p < 0.05). It was concluded that treatment with ß-glucans has beneficial metabolic and periodontal effects in diabetic rats with periodontal disease.

Low dose propranolol decreases orthodontic movement.

OBJECTIVE: Low dose propranolol has previously been demonstrated to suppress bone remodelling. Therefore, its effect on orthodontic movement was tested. DESIGN: Rats were assigned as follows (n=5): animals with no orthodontic appliance (G1); the remaining groups were fitted with a Ni-Ti closed-coil spring ligated to the upper left first molar and connected to the incisors using metal and resin and received vehicle only (G2), 0.1mg/kg (G3) or 20mg/kg (G4) of propranolol orally. Cone Beam Computed Tomography was performed using high resolution for image capture. The distance between the first and second upper molars, both with and without the orthodontic appliance, was measured in millimetres. Gingival tissue was harvested and assessed for IL-1ß and IL-6 using ELISA and for ICAM-1 and RANKL by Western blotting. RESULTS: The orthodontic appliance induced a significant tooth movement in G2 when compared to the animals without an orthodontic appliance (G1) (p<0.05). The animals from G3 showed a significantly reduction in tooth movement (p<0.05) when compared with rats from G2. Animals treated with 20mg/kg of propranolol (G4) showed tooth movement similar to that of G2. The reduced tooth movement observed in the animals treated with 0.1mg/kg of propranolol (G3) occurred due to decreased amounts of IL-1ß and IL-6, in addition to lower ICAM-1 and RANKL expression. CONCLUSIONS: Low dose propranolol inhibits bone remodelling and orthodontic movement.

Secreted osteoclastogenic factor of activated T cells (SOFAT), a novel osteoclast activator, in chronic periodontitis.

A novel activated human T cell-secreted cytokine, referred as secreted osteoclastogenic factor of activated T cells (SOFAT), that induce osteoclastogenesis in a RANKL-independent manner was recently described. This study evaluated the role of SOFAT in periodontal tissues and periodontitis. Gingival biopsies were harvested from systemically healthy non-periodontitis (n=15) and chronic periodontitis patients (n=15). The mRNA and protein levels of SOFAT were measured by qPCR and by enzyme-linked immunosorbent assay, respectively. Moreover, RAW 264.7 cells were cultured with SOFAT or Receptor activator of nuclear factor-kB ligand (RANKL) and stained for tartrate-resistant acid phosphatase (TRAP). Also, mice received a palatal injection between the first and second upper molar of SOFAT (100 ng/ml) or saline solution (0.9%). The upper jaw was removed, histologically processed and stained with hematoxilin and eosin to observe the presence of osteoclast-like cells. The mRNA and protein levels of SOFAT were significantly higher in the gingival tissue of the periodontitis group when compared to non-periodontitis one (p<0.05). In addition, SOFAT potently induced TRAP-positive multinucleated cell formation by RAW 264.7 cells as well as induced the formation of osteoclast-like cells in the periodontal ligament in mice. The present study demonstrated that SOFAT may play an important role in periodontitis.