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Anesthesia for Dermal Filler Injections
In facial esthetics, as in dentistry, patients often assess the quality and success of treatment based not on the outcome, but on the process. Dentists know, perhaps better than most medical professionals, that pain control is an integral part of the process: The more attention given to pain management, the more likely the patient will feel happy and satisfied with the outcome. Pain control and the methods used to achieve it play a central role in the practice of facial cosmetic rejuvenation.1
Aside from reducing patient discomfort, proper anesthesia administration minimizes tissue alteration of the treatment site, increases injection/application accuracy, and optimizes esthetic outcomes. The choice of anesthetic method depends on a number of factors, including patient pain tolerance, treatment site sensitivity, type of filler used, tissue plane of the dermal injection, and amount of product injected. In general, the more sensitive the site, the more likelihood there is that injectable anesthesia should be used. Understanding the available armamentarium is critical in determining which method or methods are best for the patient and practitioner. This chapter offers a detailed review of pain control methods, from least to most invasive.
Noninvasive Anesthesia Techniques
Cooling therapy and vibration
As most dentists know, a calm demeanor and gentle touch can go far in reducing the fear and anxiety that many patients experience before an injection. This approach is even more effective when combined with other noninvasive modalities of pain control.
There are many different forms of cooling therapy that offer safe, simple, and effective pain control at the site of the injection. Ice packs, vapocoolants, and contact cooling devices can be used alone or in conjunction with topical anesthetics as a pretreatment for pain. Covered ice can be applied to the skin for about 1 to 2 minutes to numb injection sites.2,3 While this method will only blunt the pain at best, it is safe, inexpensive, and easy. Spraying the injection site with a vapocoolant, such as topical ethyl chloride (Fig 2-1) or dichlorotetrafluoroethane skin refrigerant, desensitizes topical nerves immediately upon application. A randomized split-face study found a statistically significant reduction in pain of 64% when patients were treated with vapocoolant spray prior to dermal filler injections.4 This method is less cumbersome than ice packs, fast-acting, and cost-effective. However, the spray should only be used in the cheek and nasolabial folds area, and caution should be exercised for those at risk for reactive hyperpigmentation.2 Alternatively, contact cooling devices (Fig 2-2), again applied to the injection site for only 1 to 3 minutes until the skin is erythematous, not only anesthetize the treatment area, but can also reduce posttreatment ecchymosis and swelling at the site due to the vasoconstrictive effects of the cold. Patients who participated in a split-face trial experienced a 61% decrease in immediate pain and a 66% reduction in ecchymosis as measured 1 day after receiving dermal filler injections.5 However, prolonged contact at one site can result in injury to the epidermis.
FIG 2-1 Topical ethyl chloride (Gebauer) can be used to numb the injection site prior to injection of dermal fillers.
FIG 2-2 A contact dermal cooling device (ArTek Spot, ThermoTek) not only numbs the skin but reduces posttreatment bruising and swelling as well.
Vibration (Fig 2-3) has also been shown to be an effective method to minimize the pain of dermal filler injections.2 The application of a vibration device to an area adjacent to the injection site is thought to reduce pain through stimulation-induced analgesia—a concept associated with the gate control theory of pain—and by relaxing facial muscles.3,6 The vibration is applied concurrently with the injection (Fig 2-4) or just before it is administered, depending on the model used, and it is completely safe.
FIG 2-3 A vibration anesthesia device (Blaine Labs) achieves its effect through stimulation-induced analgesia and muscle relaxation.
FIG 2-4 Vibration anesthesia device applied concurrently with anesthesia injection.
Topical anesthesia
Topical anesthetics offer the same nerve-blocking qualities as injectables and can increase patient comfort when used separately or in conjunction with injectable anesthetics.7 Lidocaine, alone or in combination with another anesthetic, is the most widely used topical anesthetic.8 Today, many commercially prepared dermal fillers add lidocaine to the product, allowing patients with high resistance to pain the option to receive topical anesthetics alone in lieu of injectable anesthetics.
The effectiveness of a topical anesthetic depends on the depth of skin penetration, the location of the skin surface, the length of exposure time, and the concentration of the ingredients (Table 2-1).8 Table 2-2 lists several properties of different topical anesthetic types.9 The topical anesthetic favored by the authors is a compounded formula of 10% benzocaine, 20% lidocaine, 10% tetracaine (commonly referred to as BLT and widely used in cosmetic procedures1), and 10% dimethyl sulfoxide (DMSO) in a Lipoderm (Professional Compounding Centers of America) base. DMSO is added to the standard formula not only for its anti-inflammatory effects, but also because of its capacity to rapidly and easily penetrate the skin. This formula can be ordered from any compounding pharmacy.2 Most topical anesthetics take effect within 15 minutes of administration of a 0.5-mg dose.
TABLE 2-1 Formulas for commonly used topical anesthetics
| Name | Ingredients |
| LMX4 (Eloquest) | Lidocaine 4% |
| EMLA | Lidocaine 2.5%, prilocaine 2.5% |
| BLT plus (compounded formula) | Benzocaine 10%, lidocaine 10%, tetracaine 10%, dimethylsulfoxide 10% in Lipoderm (Professional Compounding Centers of America) base |
TABLE 2-2 Properties of topical anesthetics9
Few complications are associated with the use of topical anesthesia (Table 2-3).8 For facial dermal filler procedures, topical anesthetic is applied on a relatively small surface area, and therefore the risk of toxicity is minor. The risk of this complication increases when these agents are used on larger surface areas, such as in certain laser treatments.8 When using a compounded formula, it is extremely important to know whether the compounding pharmacy is formulating the anesthetic with phenylephrine because this can affect dosing (as can tetracaine, the ingredient most commonly associated with toxic dosing). The addition of phenylephrine, a vasoconstrictor, reduces the risk of systemic toxicity.7,10,11
TABLE 2-3 Complications associated with topical anesthesia
| Adverse event | Signs and symptoms |
| Allergic reaction | Pruritis and papules locally, and the remote possibility of urticaria, angioedema, and anaphylaxis |
| Lidocaine toxicity of the central nervous system | Dizziness, tongue numbness, tinnitus, diplopia, nystagmus, slurred speech, seizures, respiratory distress |
| Lidocaine toxicity of the cardiovascular system | Arrhythmias, hypotension, cardiac arrest |
| Tetracaine toxicity of the central nervous system | Restlessness, agitation, seizure activity |
| Methemoglobinemia caused by lidocaine, tetracaine, or prilocaine | Cyanosis, acidosis |
In the authors’ practices, most patients receiving dermal filler treatments begin with a microdermal needling procedure for dermal rejuvenation of the entire face. As described in chapter 6, a topical anesthetic is applied before microdermal needling. For patients who have a high pain tolerance, dermal filler treatments can proceed without the need for injectable anesthetics for all of the areas covered in this text with the exception of the lips, which are highly sensitive and generally require a lip ring block prior to dermal filler treatment (see chapter 10).2 Depending on their size and depth, scars and frown lines can be treated using only a topical anesthetic in most patients.
Topical anesthetic procedures begin with the application of alcohol to remove skin oils and to boost the penetration of the anesthetic. The anesthetic can then be rubbed directly on the skin either with gloved hands or a cotton applicator (Fig 2-5). Alcohol is used again to remove the anesthetic once the nerve-blocking effect has been achieved.
FIG 2-5 A topical anesthetic cream will generally take effect within about 5 minutes and last at least 30 minutes, depending on the formulation.
Injectable Anesthesia
Administering anesthesia injections is obviously within the scope of every dentist’s daily practice. However, because the target of the anesthesia is the facial nervous system rather than the oral cavity, the dentist should thoroughly review the anatomy of the face, with special emphasis on the innervation location of each injection site in the facial nervous system network (Fig 2-6).
FIG 2-6 Sensory nerves of the face. As most dentists know, the distal portion of the inferior branch of the infraorbital nerve services the upper lip; however, the superior branches of the nerve service the medial cheek, lateral nose, and lower eyelid. Similarly, the mental nerve services the lower lip, but the distal portion of the buccal nerve services the corners of the lips. The infraorbital and mental nerves stretch vertically from the mandible to the supraorbital notch located along the upper border of the orbit. These nerves are detectable roughly 2.5 cm lateral to the midline of the face. The infraorbital foramen can be reached about 1 cm inferior to the infraorbital bony margin, whereas the mental foramen can be detected 1 cm above the mandibular margin.
Complications from injections range from patient anxiety and fainting to bruises, infections, and allergic reactions. Toxicity from the anesthetic is almost nonexistent because of the low doses given, but accidental injections to nerve or blood vessels could lead to nervous system or cardiovascular system toxicity, with possible serious results (eg, respiratory distress, cardiac arrest; Box 2-1).1
BOX 2-1 Complications associated with injectable anesthesia
Bruising
Infection
Nerve injury
Allergic reactions
Lidocaine toxicity of the central nervous system
Lidocaine toxicity of the cardiovascular system
Epinephrine adverse response
Local infiltration and ring blocks are the two most common methods of administering injectable lidocaine in small doses (0.5 to 6.0 mL). Local infiltration of a solution of 0.1-mL buffered lidocaine with epinephrine is used for most of the procedures covered in this text (Figs 2-7 and 2-8). It usually requires a series of 3 to 6 subcutaneous injection sites, which should raise the skin slightly but not dimple it. The maximum dose that should be given to an adult according to body weight is 4.5 mg/kg for lidocaine without epinephrine and 7 mg/kg for lidocaine with epinephrine.9 Patients who are especially anxious or who have a low pain threshold for needle injections can be preemptively treated with any of the noninvasive anesthetic techniques described earlier. Alternatively, the clinician can apply a topical anesthetic about 15 minutes prior to treatment.
FIG 2-7 Locations for local anesthetic infiltration in preparation for basic dermal filler treatment.
FIG 2-8 Locations for local anesthetic infiltration in preparation for advanced dermal filler treatment.
Local infiltration method
An 18-gauge, 1.5-inch needle is used to draw 1.0 mL buffered 2% lidocaine-epinephrine into a 1.0-mL syringe; the needle is then removed and replaced with a 30-gauge, 0.5-inch needle (unless otherwise directed). After the injection site has been cleaned with alcohol, 0.1 mL of the solution is injected at a time (Fig 2-9). Subsequent injections are administered on both sides of the face in accordance with the complexity of the site. Compression of the injected solution away from the treatment site can help reduce edema.
FIG 2-9 (a and b) Administration of local anesthetic for dermal filler injection in the tear trough region.
Ring blocks
Overview
Certain areas of facial dermal treatment, such as the lips and perioral region, are particularly sensitive to skin alteration when anesthesia is applied. To minimize or eliminate anesthesia distortion in these areas, many clinicians prefer the ring block administration method to achieve a stronger anesthesia effect using shorter, small-gauge needles. The gingivobuccal margin slightly beneath the submucosa is the typical injection site for lip ring blocks. However, if the treatment area requires the distal portions of the inferior branches of the infraorbital and mental nerves, the injections are made much deeper below the submucosa along the maxilla (for the infraorbital nerve) and mandible (for the mental nerve).
A total of 1.2 mL of buffered or unbuffered lidocaine 2% with epinephrine 1:100,000 solution is applied intraorally via four injections to establish the ring block in the lower or upper lip. Because it is more sensitive, the upper lip should be pretreated at the injection sites with a topical anesthetic gel such as 20% benzocaine. The corners of the lips are barely affected by such ring blocks; therefore, a single injection of 0.1 mL lidocaine-epinephrine solution should be administered in each corner (Fig 2-10).
FIG 2-10 Ring block method for corners of lips. The white dots denote the locations where 0.1 mL lidocaine-epinephrine is injected.
Upper lip method
The patient should be placed in a 60-degree upright position, with the chin tilting upward. The upper lip is lifted to expose the gingivobuccal margin (Fig 2-11a). Topical benzocaine gel can be applied for 1 minute to anesthetize the injection points of the margin between the frenum and maxillary canines. A 30-gauge, 0.5-inch needle is inserted beneath the mucosa at an angle that is directed toward the pupil superiorly and parallel to the maxilla. Once the needle is advanced nearly its full length, 0.5 mL lidocaine solution is injected. If the solution does not flow smoothly, the needle may have been angled too superficially, placing the solution in the dermis. Once the needle is removed, the injected lidocaine should be compressed superiorly, toward the infraorbital foramen.
FIG 2-11 (a to c) Ring block method for upper lip. The black circles denote the locations where 0.5 mL lidocaine-epinephrine is injected, and the blue circles denote the locations where 1.0 mL lidocaine-epinephrine is injected.
Next, local infiltration is applied to the corners of the lips (Figs 2-11b and 2-11c). In each corner, the needle tip is inserted slightly beneath the mucosa, and 0.1 mL lidocaine is injected, followed by compression. The clinician then moves to the opposite side of the patient and repeats the injections previously made contralaterally. A period of 5 to 10 minutes is usually sufficient for the anesthesia to take effect. Absence of sensation should be confirmed before the dermal filler procedure is initiated. An additional 0.5 mL of anesthetic solution can be administered at the maxillary canine injection site.
Lower lip method
As with the upper lip ring block, the patient should be placed in a 60-degree upright position with the chin tilting upward. The lower lip is lifted to expose the gingivo-buccal margin slightly lateral to the mandibular first premolar (Fig 2-12a). This time, the needle is directed toward the mental foramen, parallel to the mandible, and the same precautions against superficial injection should be exercised as in the upper lip area. Compression of the lidocaine solution, this time toward the mental foramen, should be applied after the injection. Next, a second injection is made slightly lateral to the frenulum of the lower lip (Figs 2-12b and 2-12c). The tip of the needle is inserted just beneath the mucosa, and 0.1 mL of the solution is injected, followed by compression of the site once the needle is removed.
FIG 2-12 (a to c) Ring block method for lower lip. The black circles denote the locations where 0.5 mL lidocaine-epinephrine is injected, and the blue circles denote the locations where 1.0 mL lidocaine-epinephrine is injected.
The clinician then moves to the opposite side of the patient and repeats the injections for the contralateral side of the lower lip. Additional lidocaine can be applied at the mandibular first premolar if needed.
Conclusion
Local anesthesia is a critical component of an esthetic practice just as it is a dental practice. Although they do not receive formal training in esthetic dermal filler treatment in dental school, dentists have extensive experience in pain control and are experts on the musculature and anatomy of the face. Most dentists will find this knowledge invaluable for mastering the various methods of administering anesthesia prior to dermal filler treatment, some of which they perform in their everyday dental practices.
References
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