From the Guidelines
The anatomy of a facial dimple is characterized by a small indentation or depression in the skin, typically located on the cheek or near the mouth, which is often caused by a small gap or weakness in the facial muscle, specifically the zygomaticus major [/1].
Key Features
- A facial dimple is usually a minor malformation that confers little indisposition but may enhance ascertainment
- It can be associated with other mild dysmorphic craniofacial features, such as malar flatness, upslanting palpebral fissures, and hooded eyelids
- The presence of a facial dimple can be a normal variant, but it can also be a feature of certain genetic syndromes, such as 22q11.2 deletion syndrome
Clinical Considerations
- Facial dimples can be congenital or acquired, and their presence can be influenced by genetic and environmental factors
- In some cases, facial dimples can be associated with underlying structural or functional abnormalities, such as velopharyngeal incompetence or craniosynostosis
- A comprehensive evaluation by a multidisciplinary team, including a geneticist, craniofacial specialist, and other specialists as needed, is essential to determine the underlying cause and significance of a facial dimple [/1].
From the Research
Anatomy of Facial Dimples
The anatomy of a facial dimple is closely related to the structure and variation of the zygomaticus major muscle.
- A study by 2 found that the double or bifid zygomaticus major muscle, which represents an anatomical variation of this muscle of facial expression, may explain the formation of cheek "dimples".
- The inferior bundle of the bifid zygomaticus major muscle was observed to have a dermal attachment along its mid-portion, which tethers the overlying skin, creating a dimple due to this dermal tethering effect when an individual smiles.
Prevalence of Bifid Zygomaticus Major Muscle
The prevalence of the bifid zygomaticus major muscle variant, which is associated with the formation of facial dimples, has been studied in different populations.
- A meta-analysis by 3 found that the overall prevalence of the bifid ZMj is 22.7% (95% CI 14.3%-34.2%), with significant differences in prevalence among different ethnic groups.
- The study by 3 also found that the prevalence of bifid ZMj variant was most prominent in the American subgroup (34%), followed by the Asian subgroup (27.4%) and European subgroup (12.3%).
Morphology of Dimples
The morphology of naturally occurring dimples has been studied to determine the accurate position and size of dimples for surgical creation.
- A study by 4 found that among 121 patients with dimples, unilateral cheek dimples (72.88%) were more common than bilateral (27.11%), and the mean size of dimple superoinferiorly and anteroposteriorly was measured to provide guidance for surgeons.
- The study by 4 also found that the position of the dimple varied, with 60.66% of dimples occurring at the Khoo Boo-Chai's (KBC) point and 39.33% occurring anterior to the KBC point.
Surgical Creation of Dimples
Several studies have described techniques for the surgical creation of dimples.
- A study by 5 described a new simple technique for making facial dimples using a syringe needle to guide a monofilament nylon suture through the dermis and the active facial muscles.
- Another study by 6 described a technique for dimple creation using a transcutaneous bolster stitch after scraping off the dermis of all mucomuscular attachments, which was found to be safe, reliable, and easily reproducible.