Answer: Complications are very rare with dermal fillers, but probably the most common complication is overfilling. There is a tendency to overfill, especially in the central face near the eyes. There are a few rare complications such as infection, particularly in darker skin. Herpetic infections can occur in patients who have a history of cold sores after an injection around the mouth or the lips. The most dreaded complication is intravascular injection of product, which can then cause embolization or occlusion of blood vessels, resulting in necrosis. This complication is fortunately very rare with hyaluronic acid fillers; in 8 years of using these agents I have only seen it in 2 or 3 patients. These patients had been treated outside of my practice. This complication can be avoided by not injecting under a lot of pressure and not overfilling in areas that could constrict blood vessels, such as the base of the nose. If overfilling does occur, we can prevent necrosis by using hyaluronidase to break down hyaluronic acid fillers. It takes about 24 hours for hyaluronidase to literally melt the filler.

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Answer: As a starting point, we can look at averages. Most patients will present with a class 2 or class 3 nasolabial fold and in those cases the average is between 2 and 3 syringes on both sides. But the answer to the question in practice is highly variable, depending on skin quality and elasticity. Patients with loose skin may require more product to get the desired effect, while those with rejuvenated skin or who have had a facelift may require less. Expertise and training with dermal fillers is critical in making these decisions.

We also need to factor in patient preference. Some patients will want the fold or the wrinkle to be completely erased, and others will want to have most of it erased or have some sign of the wrinkle or fold for a more natural effect. Again, I like to fill one side to what I think is ideal for that patient, and then have the patient evaluate. This approach accomplishes two things: 1) It allows the patients to have a real-life opportunity to assess the results; and 2) it also maps out how much product we will need to achieve the desired result. For example, if I use one syringe on one side, it's fair to say that I’ll use another syringe on the other side.

Good technique – not injecting under pressure, not trying to put too much product into a given area – is essential to ensure safety and to achieve optimal effects.⁴ Of course, good sterile technique is also key to avoiding complications.

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Answer: I look at the G prime (G’) of each product, which gives us insight on the turgor or stiffness of the given filler or the ability of the product to lift a given amount of weight (Table 1). All the available fillers have different lifting capacity.² G’ is determined by HA concentration, particle size, degree of crosslinking, as well as the presence of uncrosslinked HA.

We can use the G’ factor to select the appropriate filler for the area being treated. For example, products with a higher G’ are not suited for shallow areas, since the product is likely to be palpable under the skin. I tend to only use product with high G’ deep in the cheek, almost like an implant. For areas with a deeper crease, like a heavy etched line on the forehead, or a deep nasolabial fold, I'll use the heavier G’ products. I would not try to use a product with a high G’ in a shallow area, such as the glabella. There are a lot of important blood vessels in that area that can lead to embolization.

Products with a medium G’ are my work horse. I have the most experience with these products, have done research with them, and find they are very versatile. All the fillers can work for nasolabial folds, but the differences show up when you start looking at superficial versus deep filling in other areas of the face.

Products with a low G’ are good options for lips, especially if a patient is looking for a soft enhancement. Typically I use lower G’ fillers for shallow wrinkles or folds, or a superficial area of treatment.

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