Rheology of Polymethylmethacrylate-Collagen Gel Filler: Physiochemical Properties and Clinical Applications

Background: Soft tissue fillers are comprised of a range of materials with differing physiochemical and rheologic (ie, flow) properties. These properties can inform treatment selection for specific anatomic areas, planes of injection, and clinical applications. Objectives: The aim of this study was to characterize the rheologic properties of polymethylmethacrylate (PMMA)-collagen gel for comparison with other available fillers. Methods: Commercially available PMMA-collagen gel, hyaluronic acid (HA), and calcium hydroxylapatite (CaHA) fillers were obtained from their respective manufacturers. Measures of complex viscosity (eta*) and elastic modulus (G') for each filler were collected at 0.7 Hz in triplicate according to standard procedures on a rotational rheometer fitted with a 40-mm steel plate at 25 degrees C on a Peltier plate (500-mu m gap). Results: The measured eta* and G' values for HA and CaHA fillers were in agreement with previously published data. The difference in eta* between CaHA (mean [standard deviation], 358.9 [21.56] Pa-s) and PMMA-collagen gel (656.41 [68.03] Pa-s) was statistically significant (P < 0.0001), as was the difference between the G' of CaHA (1424.8 [83.3] Pa) and the G' of PMMA-collagen gel (2815.27 [304.07] Pa; P < 0.0001). Conclusions: PMMA-collagen gel exhibited the highest eta* and G' of all tested fillers. These properties likely underpin an increased capacity for lifting and support in areas where long-lasting revolumization is appropriate. In practice, PMMA-collagen gel is well suited for treatment of acne scars, as well as injection into the supraperiosteal plane in the temple, chin, mandible, and piriform by a retrograde linear threading technique. Additional clinical considerations are discussed.