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

Abstract

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. The aim of this study was to characterize the rheologic properties of polymethylmethacrylate (PMMA)-collagen gel for comparison with other available fillers. Commercially available PMMA-collagen gel, hyaluronic acid (HA), and calcium hydroxylapatite (CaHA) fillers were obtained from their respective manufacturers. Measures of complex viscosity (η*) 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°C on a Peltier plate (500-μm gap). The measured η* and G' values for HA and CaHA fillers were in agreement with previously published data. The difference in η* 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). PMMA-collagen gel exhibited the highest η* 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.