Flow Charateristics of Fillers Elasticity and Viscosity (Rheologic Properties of Fillers)

Posted by Dr. Anil R. Shah

Facial fillers are some of the most popular plastic surgery procedures. This has created newer products on the market, each with its own specific qualities. One way clincians try to define the “feel” of a filler is through its physical properties.

One way fillers are quanitfied by their “feel” is their G prime or elasticity. The G’ (G prime) or elasticy describes how the filler is able to retain its shape when a force is applied. G primes are firmer to palpate, more contour stable, and lift tissue better. Fillers with lower G primes are softer, spread through tissues easer and move with the face better. For a nasal labial fold or smile line, a firmer product will be a better choice due to the amount of movement and need for contouring. Along the lower lid of the eye, a lower G prime may be better suited. An analogy of higher G prime product would be Jello versus a lower G prime product of pudding.

Another property measured for filler is the viscous nature of the filler. The viscocity is related to the flow of the filler and how spreadable the filler is. The more viscous filler is able to keep its shape better while a thinner filler will conform to the underlying tissues better. Keep in mind there is an artistic element to fillers where experience with fillers not quantifiable with a number. The following chart demonstrates the properties of fillers as a general guide.

So what facial filler does Dr. Shah recommend? He choses facial fillers based on patient’s individual anatomy and goals and customizes the product to better suit a specific area and places the product in an artisic manner.

Radiesse 1,407 349,830 Radiesse + lidocaine 554 143,100 Restylane L 565 131,310 Perlane 549 127,090 Restylane 514 119,180 Juvederm Voluma 274 92,902 Juvederm Ultra Plus XC 139 32,152 Juvederm Ultra XC 11 27,034 Juvederm Ultra Plus 75 17,699 Belotero Balance 30 9,217 Juvederm Ultra 28 7,307

Table taken in part from data from Sundaram H, et al. Dermatol Surg 2012;11(8 suppl)S12-24.