Confirming the Diagnosis
- Diagnosis: Prominent mandibular angle (사각턱). A medical term describing facial contours; causes vary, including masseter (chewing muscle) hypertrophy or overdevelopment of the mandibular angle (jawbone). Imaging tests and a dental occlusion evaluation are needed to determine the exact cause.
1) Disease Description (Causes and Symptoms)
- Definition: A condition in which both sides of the lower jaw appear broad when viewed from the front, and the jaw angle appears angular from the side, making the face look wider (an external finding).
- Main causes
- Masseter hypertrophy (particularly the masseter muscle): The muscle becomes enlarged due to bruxism, frequent chewing (tough foods or gum), genetic predisposition, and other factors.
- Overdevelopment of the jawbone (mandibular angle): The jaw angle becomes wider due to bony changes.
- Mixed type: It is common for both the muscle and bone to be enlarged.
- Pathophysiology: Chronic functional overload (chewing, bruxism) → masseter hypertrophy and bony remodeling (bone resorption/increase) → formation of a prominent mandibular angle in appearance.
- Main symptoms
- Primarily a cosmetic issue (changes in facial shape).
- When masseter hypertrophy is the cause, tension headaches, temporomandibular joint (TMJ) pain and dysfunction, and oral symptoms related to bruxism may occur.
- When there is only a bony cause, there may be no pain.
2) Treatment Methods
- Diagnosis (before selecting treatment)
- Intraoral and cranial radiographs (panoramic X-ray), PA view, maxillofacial CT (3D), and, if necessary, MRI (for evaluation of soft tissue and the TMJ).
- Dental occlusion evaluation is essential before surgery (to determine whether orthodontic treatment is needed).
- Nonsurgical treatment
- Botulinum toxin (Botox) injection: When masseter hypertrophy is the main cause, induces muscle atrophy (cosmetic improvement and relief of muscle-clinic symptoms). The effect lasts for several months (usually repeated every 3–6 months).
- Occlusal protective device (splint): Relieves bruxism and teeth clenching.
- Lifestyle modification: Limit gum and tough foods, and manage stress (to reduce nighttime bruxism).
- Surgical treatment
- Mandibular angle reduction (mandibular angle reduction surgery): Reduces the angle and width through outer cortical bone resection or osteotomy.
- Genioplasty: When the chin is short or long, balance is achieved through implant placement, bone resection, or bone grafting.
- Approach: An intraoral incision is mainly used to minimize scarring. The surgery is performed under general anesthesia.
- Hospitalization and recovery: Hospitalization for 4–5 days is generally recommended (this varies according to the institution’s and hospital’s guidelines). Bandage fixation for about 1 week and a liquid diet for about 2 weeks are recommended.
- Precautions (during and after treatment)
- Facial swelling, bruising, and decreased sensation (which may be temporary or permanent) may occur after surgery.
- With botulinum toxin use, decreased muscle strength, difficulty chewing, and, rarely, problems with speaking or swallowing may occur.
- If orthodontic treatment is needed, consultation before and after surgery is required.
- Complications (important)
- Sensory nerve injury (mental nerve, inferior alveolar nerve) → decreased sensation or numbness.
- Bleeding, infection, asymmetry, scarring (rarely, problems caused by intraoral scarring), recurrence or an unsatisfactory cosmetic result, and possible worsening of TMJ symptoms.
- Prognosis
- When the cause is identified and appropriate treatment is selected, cosmetic and functional improvement is generally favorable. However, nerve injury may persist long term, so prior explanation is necessary.
3) Outpatient Visit Checkpoints (Including Preparation Items and Example Questions)
- Preparation items
- List of current medications (including anticoagulants and antiplatelet agents), and allergy records (particularly those related to anesthetics, antibiotics, and Botox).
- Records of previous surgeries and dental treatments (particularly maxillofacial surgery and orthodontic treatment).
- Any recent imaging tests available (such as panoramic X-ray or CT) or records of imaging referrals.
- Records of symptom changes (when they began, aggravating factors, changes in pain, headaches, chewing strength, etc.) and lifestyle habits (frequency of gum and tough-food consumption, and whether nighttime bruxism occurs during sleep).
- Items to be checked during the outpatient visit
- Dental occlusion, palpation of the masseter (to assess hypertrophy), temporomandibular joint examination (opening, sounds, and pain), and photographs (front and side views).
- Example questions (for submission to the doctor)
- Do I have a recent panoramic X-ray or CT? What additional tests are needed?
- Are there any procedures that may be delayed or prohibited because of the medications I am currently taking (for example, anticoagulants)?
4) Examples of General Questions to Ask the Doctor
- "What do you think is the main cause of this condition (muscle versus bone)?"
- "What are the advantages and disadvantages of the treatment options you recommend (Botox versus surgery)?"
- "What is the expected recovery time after surgery, and when can I return to daily activities?"
- "What are the main complications of surgery or Botox, and approximately how often do they occur?"
- "How likely is recurrence after treatment? If retreatment is needed, how will it proceed?"
5) Examples of Condition-Specific Questions
- "In my case (firmness on masseter palpation/attached photograph), is botulinum toxin alone sufficient, or is mandibular angle resection necessary?"
- "If I undergo surgery, how high is the risk of decreased sensation (in the lower lip and chin area of the mandible), and how likely is it to be permanent?"
Notes
- Diagnosis and the treatment plan are determined based on an individual patient evaluation (clinical examination, imaging, and occlusion evaluation).
- The choice between botulinum toxin and surgery should be discussed with a specialist, taking into account the cause (muscular versus bony), the patient’s expectations, and general health status.