Disease Name
- Disease name: Prognathism (Class III malocclusion) — This is a medically used term and is also called mandibular prognathism (mandibular protrusion) or Class III malocclusion.
1) Disease Description (Causes and Symptoms)
- Causes
- Mainly caused by excessive growth of the mandible (lower jawbone).
- Genetic factors (family history) play an important role.
- Habits such as mouth breathing, tongue thrusting, and resting the chin on the hand, congenital anomalies (such as cleft lip), or certain systemic diseases may be causes.
- Pathophysiology
- The mandible is positioned relatively forward, causing a skeletal imbalance between the maxilla and mandible; compensatory movement of the teeth (dental compensation) may also occur.
- This may lead to malocclusion, temporomandibular joint (TMJ) imbalance, reduced chewing function, speech problems, and worsening of sleep apnea.
- Main symptoms
- Anterior crossbite, in which the lower front teeth appear to be positioned in front of the upper front teeth.
- Difficulty closing the mouth, difficulty chewing, speech abnormalities (such as alveolar sound production), and temporomandibular joint pain or sounds.
- In severe cases, aesthetic dissatisfaction and psychosocial effects (reduced self-esteem).
2) Treatment Methods and Precautions
- Nonsurgical treatment
- Patients who are still growing: Improvement may be attempted with functional appliances (e.g., maxillary protraction using a face mask) and orthodontic treatment (dental compensation using orthodontic appliances).
- In adults, dental compensation (orthodontic camouflage) is limited in its ability to improve aesthetics and function and has limitations in cases of severe skeletal imbalance.
- Surgical treatment (standard)
- Orthognathic surgery combined with orthodontic treatment is the standard treatment.
- A representative procedure is sagittal split ramus osteotomy (SSRO), which moves the mandible backward.
- Depending on the case, maxillary advancement and genioplasty (parotid gland and chin-only surgery) may also be performed.
- The total treatment period may be long because it includes preoperative orthodontic treatment and postoperative finishing orthodontic treatment.
- Surgery-related information
- The surgery is performed under general anesthesia through incisions inside the mouth. Hospitalization is usually 4–5 days; swelling peaks after 2–3 days and then gradually improves.
- Temporary sensory loss may occur after surgery (related to inferior alveolar nerve injury), and in rare cases it may persist long term.
- Diet: Soft foods are recommended for 3–4 weeks after surgery. Oral hygiene (such as gargling) is important.
- Complications and precautions
- Bleeding, infection, nerve injury (sensory loss), problems with bone union, unsatisfactory occlusion, or relapse (a tendency to return backward).
- Smoking delays healing and increases the risk of complications. Smoking cessation is recommended.
- Additional evaluation is needed if sleep apnea or severe TMJ symptoms are present.
- Prognosis
- Combined orthodontic and surgical treatment provides excellent functional and aesthetic improvement. However, relapse is possible in some patients, so long-term follow-up is necessary.
3) Checklist Before an Outpatient Visit (Items to Bring and Examples of Medical History Information)
- Items to bring
- A list of medications currently being taken (especially anticoagulants and antithrombotic agents) and a history of allergies.
- Previous treatment history (prior orthodontic treatment and dental or maxillofacial surgery records); bring existing radiographs (panoramic radiographs, cephalometric radiographs, CT scans, etc.) if available.
- A record of symptom changes (when they began, aggravating factors, associated symptoms such as pain, sensory abnormalities, or sleep problems) and facial photographs (side and front views).
- Lifestyle information (smoking, alcohol consumption, sleep patterns, and habits such as thumb sucking or tongue positioning).
- Examples of information to tell the doctor in advance during the outpatient visit
- Whether surgery is desired and the expected outcomes (priorities between aesthetics and function).
- Whether sleep apnea or snoring is present (including observations by a sleep partner).
- Current difficulty chewing, speech problems, or temporomandibular joint pain.
4) Examples of General Questions to Ask the Doctor
- "Can I expect satisfactory results with nonsurgical treatment for my condition?"
- "What is the specific surgical process, and what is the expected recovery period?"
- "What are the main complications of the surgery, and how frequently do they occur?"
- "What should I be careful about regarding daily life, diet, and exercise before and after surgery?"
5) Examples of Condition-Specific Questions
- For children who are still growing: "My child is still growing. Should we start orthodontic treatment now, or should we consider surgery after growth is complete?"
- Regarding surgery: "How long is sensory loss expected to last after sagittal split ramus osteotomy (SSRO), particularly reduced sensation in the lower lip and chin?"
Note: Diagnosis is based on a clinical oral examination (occlusion assessment), radiographs (cephalogram, panoramic radiograph, and, if necessary, 3D CT), and a comprehensive orthodontic and maxillofacial surgical evaluation.