Background and complications of dermal fillers: the increasing use of non-surgical facial aesthetics in dental practice

History of use

The use of paraffin and Vaseline injections to augment the face dates back to the 1800s. Their use was associated with many complications and so the search for safer, more reliable and biocompatible materials began. In 1893, autologous fat injections were used to correct facial defects, the success of which was variable, relying heavily on adequate training, sterile technique and storage. Silicone use as a permanent facial filler remains controversial owing to the material's ability to migrate and form fistulas. In 1981, bovine collagen was the first agent to be approved for cosmetic injection by the US Food and Drug Administration (FDA). Recently hyaluronic acid use has increased in popularity¹ due to its skin smoothing and volume-producing effects that can generally last between 6 and 18 months.²

The ageing face

The skin acts as a mechanical barrier to the outside world. The face is divided into superficial and deep fat compartments by various retaining ligaments and their septa, the muscles of facial expression are in between the compartments. This network of retaining ligaments arises from the deep fascia penetrating the superficial muscular aponeurotic system (SMAS). This is a continuation of the platysma/superficial cervical fascia in the neck and the temporoparietal fascia in the temple region and extends into the galeal aponeurotic layer in the scalp. When these various compartments weaken at their various supporting ligaments/septi, the face starts to lose its youthful appearance. Through these various weakened degenerated compartments, fat migrates and the characteristic features of ageing appear (Figure 1, Table 1).³

Types of dermal filler

Fillers can be classified as permanent, semi-permanent and temporary. Permanent fillers, such as silicone, can often lead to more severe, chronic complications, which are more difficult to treat. The most common type of complication associated with permanent fillers is granuloma formation, which may necessitate treatment with immunosuppressive drugs and repeated surgery.

Semi-permanent fillers, such as poly-lactic acid and calcium hydroxyapatite may be associated with granuloma formation and occasional nodule formations. The desired effect may be very short lived because its use is dependent on tissue response.

Temporary fillers, such as hyaluronic acid, may be associated with allergic reactions and an optical phenomenon known as the Tyndall effect, where a blue discolouration can form after filler injection. Some temporary fillers can stimulate fibrous tissue formation and rarely, but still quoted in literature, these types of fillers, if combined with lignocaine, can lead to anaphylaxis and death.⁴ This is a very rare complication associated with lignocaine, rather than the filler. Table 2 highlights the types of filler, material, longevity and advantages and disadvantages of each.

Dermal fillers may be used alone or in combination with other agents, such as neuromodulators, to achieve the best aesthetic result. In the placement of these agents, appreciation of the regional anatomy is essential. This is necessary to avoid inadvertent injection of these products into vital structures (eg neural and vascular), which could result in serious complications for the patient. Secondly, to gain the optimum cosmetic result, a complete understanding of anatomical compartments is required. An example is the commonly ‘overfilled’ appearance of the lips if dermal filler is injected in a vertical direction at the vermillion-cutaneous border. This can lead to inadvertent injection into the superficial compartment of the lip (anterior to orbicularis oris) rather than the intended deep compartment (by injecting posterior to the orbicularis oris). Correct injection can lead to a more youthful appearance secondary to lip eversion.⁶

Dermal fillers may be administered with a needle or a cannula: the latter often enables more precise injection of product in the desired facial plane and has a lower risk of intra-arterial injection.⁷ There are several techniques that the practitioner may use for administration:

Linear threading technique: full length of needle is inserted along centre of wrinkle and injected as the needle is withdrawn.

Serial puncture technique: multiple injections of the filler along the wrinkle length, so small deposits of the filler combine to form a smooth continuous line lifting up the skin.

Fan technique: multiple passes of the linear threading technique. Needle passes into the centre from different peripheral points.

Cross hatching technique: filler injected as regular parallel lines using the linear threading technique, then repeated at right angles.

Sandwich technique: filler injected one above another.

Dental clinicians should also bear in mind the importance of oral rehabilitation and the restoration of a full dentition as important contributory factors in leading to a more aesthetically pleasing facial profile.

Current legislation

Dermal fillers currently placed on the UK market with a medical purpose are classified under the medical devices legislation and therefore require a CE mark. The current stance from the Medicines and Healthcare Products Regulatory Agency (MHRA) is that medical devices from May 2020 will be regulated under the European Regulations EU2017/745. All dermal fillers are incorporated into this category. However, there are two main issues. First, these recommendations may not apply in the UK post-Brexit as this is an EU regulation. Secondly, no prescription is required for dermal fillers (unlike botulinum toxin) and, therefore, untrained persons can continue to administer these products, increasing the risk of post-operative complications.

An independent review of the cosmetic procedures industry in the UK recommends all practitioners to be properly qualified and an Ombudsman to be instated to oversee private healthcare complications. Enlisting onto formal registers (although not a legal requirement) may help the public form more informed decisions about cosmetic treatment. ‘Unfortunately, since the release of this report the government has failed to sufficiently respond to the recommendations set. In part, this is due to their belief that they shouldn't have to fund a register for commercial cosmetic elective procedures’.⁴

Complications

All surgical procedures carry a risk of post-operative complications and the injection of dermal fillers is no different. The nature of complications varies widely depending on the type of filler used. Up to 80% of patients who receive a temporary filler experience complications, viz, erythema from the injection site, swelling, bruising.⁸ These are generally classified as early or late complications.

Early complications, occurring 0–14 days post-injection, include infection, immediate tissue necrosis due to vascular occlusion (VO), dysaesthesia, under/over correction of the filler, Tyndall effect, temporary and permanent visual loss due to VO (very rare),⁹ herpes simplex reactivation causing cold sores, and temporary swellings that resolve early. Late complications can occur 1 year post-operatively and are often more difficult to manage. These complications include recurrent infections due to biofilm formation, formation of chronic sinuses and granulomas.¹⁰

Typically in biofilm-related infections, there is history of a condition predisposing the patient to biofilm growth. Following implantation of a foreign body, the patient may experience pain, swelling, erythema, induration and loss of function. Symptoms of infection last more than 7 days and may resolve during antibiotic treatment, but recur later. Antibiotic treatment alone can prove ineffective.¹¹

Figures suggest that granuloma formation occurs in 0.02–0.4% of cases when hyaluronic acid fillers are used.¹² Skin necrosis is a particularly physically apparent complication, occurring where filler has been incorrectly injected into a vessel or injected in significant volume next to a vessel causing compression, leading to VO. Fortunately, hyaluronic acid can be dissolved quickly and efficiently with hyaluronidase, which can diffuse across vessel walls and can therefore penetrate intra-vascularly.¹³

We describe two cases recently treated in our department that highlight some of the complications previously discussed.

Case 1

A fit and well 46-year-old female presented to OMFS via the emergency department regarding a left-sided facial swelling. She described a 2-month history of refractory swelling in the left cheek that had occurred following placement of hyaluronic acid dermal filler.

Prior to her initial presentation to our department, she had been treated with multiple courses of antibiotics and steroids, which all had proved ineffective. Further to this, aspiration of fluid from the collection and four attempts to dissolve the filler using hyaluronidase had also proved unsuccessful.

On examination, a left buccal swelling with associated fluctuance of approximately two 1.5-cm swellings (probably due to biofilm formation) was noted in the area of placement of the dermal fillers with no associated neurosensory deficit. Repeated aspiration of the swellings cultured Streptococcus intermedius (sensitive to amoxicillin). She subsequently developed hollowing of the left cheek that was thought to be due to necrosis of the buccal fat, and an MRI was arranged.

The MRI revealed a buccal and labial collection in the cheek associated with innumerable small, relatively well-defined nodules in the subcutaneous tissues (Figure 2). Over the course of the following months, the patient had numerous incision and drainage procedures to wash out the recollection as well as a prolonged course of IV amoxicillin and clindamycin, after microbiology advice. The persistent recollection was thought to be related to the diffuse nature of residual filler in the soft tissues that acted as foreign body and was difficult to fully debride without causing further loss of buccal fat, damage to the buccal branch of the facial nerve or perforating the skin. This was a significant risk in relation to the patient's aesthetic concerns.

The eventual resolution of the infection was confirmed at subsequent outpatient review, where hollowing of the left cheek was noted due to fat necrosis. At this juncture, the patient was still actively seeking further filler treatment against which she was cautioned.

Case 2

A fit and well 48-year old female attended the emergency department complaining of a bilateral peri-orbital cellulitis 6 days following a course of botulinum toxin (BTX) as part of non-surgical aesthetic facial rejuvenation treatment. The BTX was administered to the glabella region and bilateral crow's feet area. The patient described two previous identical courses of BTX with the same practitioner without complication.

Initially the patient had noticed swelling 3 days post-administration, which spread bilaterally over the zygoma region and extended to the cervical region on the right-hand side (Figure 3).

On examination the patient was pyrexic, with a general feeling of malaise. Ophthalmological review and CT scan imaging confirmed a pre-septal cellulitis with no drainage collection involving the orbital/sinus structures (Table 3).

The patient was subsequently admitted for IV flucloxacillin and benzylpenicillin for 2 days and discharged with an oral course of flucloxacillin. At review 2 weeks later, the patient's symptoms were fully resolved with no residual deficit. The patient expressed reluctance for any further aesthetic treatment in the future.

Discussion

The reporting of complications is inconsistent, due to the loose regulations around the use of dermal fillers, and the lack of professional follow up. Similarly, minor complications are unlikely to be reported to professional authorities, as they require little intervention and can often be managed by non-professionals. Complications that require professional intervention tend to be those with a higher associated comorbidity, and as such, the reporting will be skewed.

In 2013, Sir Bruce Keogh KBE published guidance from the Department of Health for dermal fillers to have tighter post-market surveillance, with a need for an interspecialty committee of cosmetic surgery to be developed. He also called for dermal fillers to be classed as a prescription-only medicine. This would allow for complications to be thoroughly reported, investigated, and policies made to streamline investigations and treatment.

Conclusion

As the popularity of non-surgical aesthetic treatments increases, the risks cannot be ignored and proper knowledge and training is a necessity.