Dr Tim Pearce
Rheology remains a somewhat debated topic in aesthetic medicine. The biggest challenge lies in measuring something outside of the body that you then put in and interacts intimately with multiple different molecules that also have rheological properties. It’s the interaction between these that really forms the ultimate degree of projection or definition that you get.
Translating laboratory physics to actual patient outcomes presents a significant challenge. Rather than focusing solely on laboratory measurements, practitioners should observe:
It’s crucial to understand the difference between FDA and CE approval when selecting products. CE approval doesn’t mean much in terms of human bodies or aesthetic results – it’s comparable to a toothbrush manufacturing approval. It simply means the materials are approved and the process is clean, but it doesn’t test interaction in human bodies and long-term aesthetic outcomes at all.
What practitioners really need is long-term study data, ideally spanning five years, to understand what happens over time. Currently, most products only have six-month studies, if any at all. FDA approval, while more comprehensive than CE marking, focuses more on medical safety than aesthetic outcomes. The key concerns are whether people react to the product, if there are infections or unusual complications, and whether it’s easily reversible.
Water attraction proves to be one of the most important considerations in filler rheology. Experience with Juve Ultra 2 for fine lines in upper lips demonstrates this clearly: while it looks acceptable on the day, seeing the same patient two years later often reveals unexpected puffiness in the top lip. Initially, practitioners might suspect patients had sought treatment elsewhere, but over time it becomes clear that the product itself attracts moisture over time.
Different products exhibit varying levels of water attraction. For instance, Dr. Harris uses Juvenile Ultra 3 in very low volumes (0.3 mils maximum) specifically because of its significant water attraction. Using larger volumes – for example, putting a mill of Ultra 3 in someone’s lips – likely won’t look good in six to nine months unless they have very good structure or break down products quickly.
In contrast, products like Volift or Volbella appear to hold their shape better and show less water attraction over time. This understanding comes only through long-term observation of product behavior in actual patients. You can use a product in one way that ends up in a stable result for many years, while exactly the same product used differently will ruin someone’s lips.
There are significant doubts around more superficial styles of injecting, particularly the Teoxane approach using cannulas more superficially. While this might look fine initially, concerns exist about how it will appear in three to five years’ time, given its proximity to the surface where irregularities and pockets become more visible. This is particularly relevant given the dynamic nature of facial tissue.
This isn’t just a belief system – it’s a mental model based on observing how products behave over time. While we don’t have extensive scientific data, we do have clinical experience showing how different placement depths affect long-term outcomes.
Don’t ask about the best filler – instead, become really good at understanding your filler. As demonstrated by the example of an artist who creates amazing pictures with a barbell, success comes from understanding how to use your tool to create beautiful results. This artist understands how to use that specific tool to create a beautiful result, and that’s really the skill. It’s not necessarily about the filler itself – you can create amazing results with any FDA-approved product, but you need to understand that product really well.
It typically takes about two years to get to know a product properly. Most experienced practitioners have only used two or three types of products throughout their careers, understanding them slowly over time. This deep understanding allows practitioners to:
Different manufacturers make various claims about their products. For example, Restylane might comment on another product’s lack of cohesivity. While these comparisons can be intriguing, personal experience with each product over time provides the most valuable insights into how they actually perform in patients. Long-term data about aesthetics outcomes is woefully lacking in our industry.
Understanding filler rheology requires more than laboratory data – it demands real-world observation of how products behave in tissue over time. Success comes not from having access to every available product, but from thoroughly understanding your chosen range and how it behaves in different clinical situations.
Remember that while CE and FDA approvals provide basic safety assurance, they don’t guarantee long-term aesthetic outcomes. The key lies in developing deep familiarity with your chosen products through careful observation and long-term patient follow-up.
The most successful practitioners aren’t those with the largest product selection, but those who thoroughly understand their chosen products and can use them skillfully to create beautiful, lasting results. Each practitioner needs to figure this out through personal experience with their chosen products, as long-term aesthetic data remains limited in our field.
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Dr Tim Pearce MBChB BSc (Hons) MRCGP founded his eLearning concept in 2016 in order to provide readily accessible BOTOX® and dermal filler online courses for fellow Medical Aesthetics practitioners. His objective was to raise standards within the industry – a principle which remains just as relevant today.
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