Disease Description (Causes and Symptoms)
- Definition: A condition in which an imbalance in the position and size of the jaw bones develops due to overgrowth or undergrowth of the lower jaw (mandible) or upper jaw (maxilla) (e.g., prognathism or retrognathia).
- Causes and pathophysiology: Genetic factors tend to play a major role (family history), and the condition may result from abnormal fetal development, congenital anomalies at birth (e.g., Pierre Robin sequence), childhood trauma, improper oral habits, temporomandibular joint diseases (rheumatoid arthritis, temporomandibular joint arthritis), infection or tumors, or radiation sequelae. Jawbone imbalance affects tooth alignment (occlusion), temporomandibular joint function, breathing (airway maintenance), speech, and chewing; during the growth period, it may worsen over time or partial compensation may occur.
- Main symptoms: Changes in facial appearance (protrusion or retrusion), speech abnormalities, difficulty chewing, dental malocclusion, temporomandibular joint pain or sounds, dry mouth and worsening dental caries, and an increased risk of sleep apnea (especially with retrognathia).
Treatment Methods and Precautions
- Non-surgical treatment
- During the growth period, growth may be guided or corrected with orthodontic treatment (functional appliances and orthodontic appliances).
- Non-surgical breathing and sleep support (such as CPAP when sleep apnea is suspected) and speech therapy (when speech correction is needed).
- Surgical treatment (including orthognathic surgery)
- Skeletal repositioning through anterior or posterior repositioning of the mandible (e.g., bilateral sagittal split osteotomy, BSSO), movement of the maxilla (Le Fort I), or combined double-jaw surgery.
- For retrognathia (mandibular hypoplasia), options include distraction osteogenesis (bone lengthening), mandibular advancement, genioplasty, or insertion of an implant.
- Prognathism is treated with isolated mandibular setback or double-jaw surgery (including posterior movement of the maxilla).
- Severe respiratory problems in infants or young children (such as Pierre Robin sequence) may require non-surgical positioning and airway maintenance, and, when necessary, surgical airway management or distraction osteogenesis.
- Pre- and postoperative management
- Preoperative orthodontics (or postoperative orthodontics) should be planned; 3D simulation and precise measurements are recommended.
- General anesthesia and hospitalization (several days to several weeks) are required. For a certain period after surgery, tooth fixation or dietary restrictions (soft foods for approximately 2–3 weeks), careful oral hygiene, and antiseptic gargling are recommended.
- Complications and precautions
- Complications: Infection, bleeding, nerve damage (reduced sensation due to inferior alveolar nerve injury), poor bone union and sequelae (recurrence), temporomandibular joint problems, implant-related problems, and scarring (when the incision is inside the mouth, visible external scarring is minimal).
- Timing considerations: Surgery before completion of skeletal growth (before adulthood) carries a high risk of recurrence (generally recommended surgical age: after approximately 18 years for females and after approximately 20 years for males; individual examination is necessary).
- Lifestyle management: Avoid smoking (to reduce the risk of poor bone union and infection before and after surgery), maintain thorough oral hygiene, and undergo regular checkups.
- Prognosis: When appropriate orthodontic treatment and surgery are combined, functional and aesthetic improvement is generally good; however, depending on the cause, timing, and surgical method, additional orthodontic treatment or repeat surgery may be necessary.
Outpatient Visit Checklist (Preparation and Example Questions)
- Preparations and materials
- A list of current medications (including prescriptions) and allergy history.
- Records of previous surgeries and systemic diseases (such as bleeding disorders and diabetes).
- Original copies or reports of existing dental and oral surgery photographs, panoramic X-rays, cephalometric X-rays, 3D CT scans, and other imaging, if available.
- If currently undergoing orthodontic treatment, records from the orthodontist (tooth movement plan, wire status, etc.).
- A symptom diary (speech problems, chewing discomfort, frequency of pain, suspected symptoms of apnea during sleep, etc.).
- Information to tell the doctor during the outpatient visit (examples)
- When the symptoms began and how they have progressed (whether they worsened after the growth period).
- Specific circumstances of speech, breathing, chewing, and sleep problems and their effects on daily life.
- Family history (whether parents or siblings have a similar jaw shape).
- Possibility of pregnancy (in relation to surgery and imaging tests).
General Example Questions to Ask the Doctor
- What is the exact diagnosis and cause of this condition?
- Is surgery necessary? If so, what is the recommended timing and why?
- What are the surgical methods (single-jaw versus double-jaw), expected effects, and risks (such as nerve damage and reduced sensation)?
- Is orthodontic treatment needed before or after surgery? What are the duration and process?
- Approximately how long will it take to return to daily activities and resume eating?
- Will sleep apnea or speech problems also improve?
- What is the likelihood of recurrence and repeat surgery after the operation?
Examples of Condition-Specific Questions
- If prognathism (mandibular overgrowth) is suspected
- Is isolated mandibular setback sufficient, or would a more stable result be achieved by also moving the maxilla (double-jaw surgery)?
- What additional treatments (such as orthodontics or physical therapy) are needed to improve occlusal stability and reduce the risk of recurrence after surgery?
- If retrognathia (mandibular hypoplasia) is suspected
- Which method is more appropriate for the patient’s current condition: distraction osteogenesis (bone lengthening) or genioplasty?
- For a child in the growth period, would you recommend trying adjunctive treatment (such as functional appliances or postural correction) before surgery? When is the appropriate time for surgery?
(Note: Bringing photographs and imaging materials when necessary can make consultation and surgical planning more accurate.)