Polymethylmethacrylate dermal fillers: evaluation of the systemic toxicity in rats.

This study evaluated local and systemic reactions after an intravascular injection of polymethylmethacrylate (PMMA) at two concentrations in a murine model. Thirty rats were divided equally into three groups: 2% PMMA, 30% PMMA, and a control group (normal saline only injection). The filler was injected into the ranine vein. The rats were sedated at 7 and 90 days and a clinical evaluation performed. After euthanasia, the right lung, liver, and right kidney were removed, weighed, and microscopically analyzed. The submandibular lymph nodes and tongue were removed and examined microscopically. Serum was subjected to liver and kidney function tests. No groups showed clinical alterations. Microspheres were not observed at any distant organ. Two samples from the 2% PMMA group showed a local inflammatory response at day 7 and another two samples from the 30% PMMA group at day 90. The group injected with 30% PMMA presented higher levels of alanine aminotransferase (P = 0.047) after 90 days when compared with the other groups. The data obtained in this study demonstrate that intravascular injections of PMMA fillers show potential health risks such as chronic inflammation at the implantation site.

Clinical and pathological characteristics of polymethylmethacrylate and hyaluronic acid in the rat tongue.

Adverse effects on the oral mucosa after the use of dermal fillers have been increasingly reported due to their increased use for facial aesthetics. The objective of this study was to evaluate the clinical and histologic effects of two types of product, 10% polymethylmethacrylate and 20mg/ml hyaluronic acid, locally and at long distance, examining initial and late reactions. Each substance was randomly and separately injected in rats' tongues (polymethylmethacrylate, n = 16; hyaluronic acid, n = 18). They were compared with the control group (n = 16) at 3 observation times (7, 60 and 90 days) for clinical analysis, intensity of local inflammatory response (haematoxylin and eosin staining), amount of newly formed blood vessels and macrophages (immunohistochemical assays), density of collagen fibres (picrosirius staining) and systemic migration of the product to the liver and kidney (haematoxylin and eosin staining). The results showed inflammation triggered by the injection of the material, suggesting that both substances cause responses in local tissue, although there was biocompatibility with hyaluronic acid. This research highlights the importance of experimental studies on this subject, since adverse reactions have been observed routinely in dental practice.