1. By the tissue or structure involved

1. Skeletal asymmetry
   • Unequal size, shape, position, or growth of facial bones.
   • May involve maxilla, mandible, chin, zygoma, orbit, or cranial base.
   • Examples: mandibular laterognathism, condylar hyperplasia/hypoplasia, hemifacial microsomia.
2. Dental asymmetry
   • Asymmetry limited mainly to teeth and dental arches, with relatively symmetrical basal bones.
   • Examples: unilateral missing tooth, ectopic eruption, unilateral crossbite, asymmetric arch form, dental midline shift.
3. Soft-tissue asymmetry
   • Due to skin, subcutaneous fat, muscles, salivary glands, or facial nerve function.
   • Examples: masseter hypertrophy, hemifacial atrophy, facial paralysis, scars, soft-tissue tumor.
4. Functional asymmetry
   • Positional deviation, usually of the mandible, during closure rather than a fixed skeletal discrepancy.
   • Commonly caused by premature occlusal contacts or unilateral posterior crossbite.
   • Often called a functional mandibular shift.
5. Combined dentofacial asymmetry
   • More than one component is present, such as skeletal asymmetry with dental compensation and soft-tissue imbalance.
   • This is common in clinically significant cases.

2. By region of the face

• Upper-third asymmetry: forehead, orbital, and cranial asymmetry
• Middle-third asymmetry: nose, zygoma, maxilla, cheeks
• Lower-third asymmetry: mandible, chin, lower lip, occlusal plane
  • Lower-face and chin deviations are the most commonly noticed in orthodontic patients.

3. By cause or time of origin

• Congenital/developmental: hemifacial microsomia, craniofacial syndromes, condylar growth disturbance
• Acquired: trauma, infection, tumor, temporomandibular joint ankylosis, facial nerve palsy
• Iatrogenic: surgery-related or treatment-related changes

4. By severity

• Mild: detectable only on detailed examination or photographs
• Moderate: visible clinically but with limited functional effect
• Severe: obvious deformity, often with malocclusion, functional impairment, or psychosocial concern