倒及牙，俗稱地包天、鞋揪面或月亮臉。倒及牙不僅影響美觀，還可能影響患者咀嚼與發音，給患者心理與社交帶來負面影響。亞洲人尤其是香港人口中，約15%受倒及牙困擾，這一比例明顯高於西方國家。西方國家倒及牙平均比例為3%至6.2%之間，其中歐洲地區平均發生率為6.2%，而美洲地區平均發生率為6.23%.
賭王孫女何超欣之前也有倒及牙問題，矯正前她出鏡時總是抿嘴微笑，不太願意露出牙齒。成功矯正后，她露齒笑就比之前自然許多。本文將介紹倒及牙的類型和成因，以及如何對症治療，一次性解決倒及牙矯正的大多數問題。
What Are the Signs of an Underbite?
An underbite is often described as a Class III bite. It may be noticeable when the lower front teeth sit in front of the upper front teeth. Some people may experience uneven biting, tooth wear, difficulty biting food, speech concerns or concerns about facial appearance. These signs do not confirm a diagnosis; a dentist should assess the bite and the underlying cause.
Other bite patterns can look different from an underbite. A professional assessment is important because the recommended treatment depends on whether the concern is mainly related to tooth position, jaw growth or a combination of factors.
Underbites are commonly assessed as dental, skeletal or mixed. The category helps the dentist decide which treatment approach should be discussed.
1.功能性反頜（齒性）
功能性反頜主要由牙齒排列不良或牙齒生長角度異常引起，如上門牙過度向内傾斜、下門牙過度向前傾斜。咬合存在問題也會迫使下巴向前移動。這種病症相對容易處理，通常可通過箍牙等治療方法矯正。
2.骨性反頜（骨性）
骨性反頜原因是顎骨結構或生長發育異常，如下顎骨過度發育（下顎前突），上腭骨發育不足（上顎後縮）。這些原因多與遺傳或基因問題有關。因涉及骨骼結構，嚴重骨性反頜需要通過正畸配合正頜手術才能達到理想效果。
3.混合型
混合型是顎骨性畸形與牙齒代償性傾斜的結合。這類患者有潛在的顎骨結構問題，牙齒也會因此改變傾斜角度來代償性彌補骨骼問題。此類需要綜合治療，通常是先進行正畸去代償治療，再通過外殼手術矯正頜骨結構。
倒及牙如何治療？倒及牙矯正需要多久？
倒及牙治療强調早期干預。兒童生長發育階段的顎骨具有高度可塑性，儘早進行矯正易於達到理想治療效果。
家長可以根據兒童年齡進行對應的牙齒觀察和檢查。自兒童1嵗起，家長可每年初步觀察其牙齒的發育狀況，如門牙等牙齒是否整齊，咬合時上下排牙齒是否正常。學齡前至恆齒萌出期（約6至7歲），家長可以找牙科醫生進行詳細評估，從而判斷兒童是否需要牙齒矯正。
青春期以後（約12至18歲），需留意是否出現顎骨性倒及牙。因下顎骨發育通常比上顎慢，顎骨性倒及牙往往到青春期甚至成年後才被發現。此時兒童的顎骨和牙齒尚未定形，及早開始矯正有助於引導顎骨正常生長。若發現患有嚴重的顎骨性倒及牙，一般需要進行正頜手術治療，但需要患者頜骨發育完成才能進行。男士頜骨約在19至20歲發育完成，女士大約為17嵗。
Underbite Treatment Options and Expected Timing
For children and teenagers, early assessment may help guide treatment planning while the teeth and jaws are developing. Depending on the diagnosis, options may include removable appliances, fixed braces, functional appliances or clear aligners. Treatment duration varies substantially, so a dentist should explain the approach appropriate for the individual case.
| Treatment complexity | 治療方法 | 適合年齡 | 平均療程時長 | 治療難度 | May surgery be required? |
| Dental underbite | 局部活動牙箍 / 固定牙箍 | 恆齒期（約 7–12 歲） | 6–12 個月 | ⭐ | 否 |
| Mild skeletal underbite | 功能矯正器 / 早期牽引 / 微植體輔助 | 混合齒期（6–9 歲） | 6–9 個月 | ⭐⭐ | 否 |
| 中度顎骨性倒及牙 | 上顎牽引 / 擴弓器 + 固定牙箍 | 發育期（10–14 歲） | 約 1.5 年 | ⭐⭐⭐ | 否 |
| 重度顎骨性倒及牙 | 正頜手術 + 矯正 | 發育完成後（17 歲以上） | 約 2 年 | ⭐⭐⭐⭐⭐ | 是 |
Note: This information is for general reference only and does not replace a dentist’s or orthodontist’s professional assessment. Oral condition, jaw growth and treatment needs vary between individuals. The treatment method, timing and cost should be decided after a qualified clinician has examined your case.
In adults, jaw growth is generally complete. A dentist should assess the severity and cause of an underbite before discussing whether orthodontic treatment alone or combined orthodontic and jaw treatment is appropriate. When the concern is mainly related to tooth position, braces or clear aligners may be considered. More complex skeletal cases may need specialist assessment.
Clear Aligners for Adult Underbite Treatment
Adult underbite treatment depends on the cause and severity of the bite. Where the issue is mainly related to tooth position, braces or clear aligners may be considered. More complex jaw-related cases may require referral or combined treatment. Clear aligners are removable and may be convenient for eating and oral hygiene, but suitability must be confirmed by a dentist.
Lulusmilesprovides clear-aligner treatment for adults. Each plan is tailored after clinical assessment and may use AI algorithm tools for measurement and design. Treatment plans are reviewed by an in-house orthodontist and further confirmed by the attending doctor before treatment begins.
Clear aligners are made from medical-grade TPU and PETG materials and are BPA-free. Your dentist can explain the material characteristics, wear schedule and care instructions for your individual treatment plan.
The aligner material is designed to maintain corrective force for longer than regular materials, helping to provide more stable force for tooth movement. Aligner wear and performance depend on the prescribed wear schedule, treatment plan and proper care. Follow the instructions provided by your dentist.
Lulusmiles also provideswhite-coloured aligners, including natural-white and off-white options. These aligners may help mask the appearance of stains and yellowing while they are worn.
Frequently Asked Questions About Underbite Treatment
1.1. Do I need treatment for a mild underbite?
Not always. Whether treatment is recommended depends on the bite, symptoms, dental health and the person’s goals. Some mild underbites may not cause immediate problems, but a dentist can explain whether monitoring or treatment is appropriate after examining the teeth and jaws.
2.2. Does treatment hurt? How long does it take?
Comfort and treatment time vary with the treatment method and the individual plan. Some people experience temporary pressure or tenderness when teeth are being moved. Your dentist can explain what to expect, how to manage discomfort and the likely treatment timeline for your case.
3.3. Can adults have jaw surgery for an underbite? What are the risks?
In some adults with a significant jaw-related underbite, orthognathic (jaw) surgery may be considered as part of a combined orthodontic treatment plan. It is not suitable for everyone. A specialist assessment is needed to discuss the expected benefits, alternatives, recovery and surgical risks, which can include swelling, infection, altered sensation and bite-related complications.
4.Will orthodontic treatment affect everyday life or eating?/eating?
It can, particularly during the first days after an appliance is fitted or adjusted. The effect varies with the treatment type. Your dentist may recommend temporary food or activity adjustments and can explain how to care for the appliance. Contact the clinic if discomfort is severe or does not improve as advised.
5.5. If I only want to improve appearance, can I choose a simpler treatment?
Possibly, but only after the bite has been assessed. Treatment should not focus on appearance alone if it could compromise function, tooth health or long-term stability. A dentist can explain which options are appropriate and whether a simpler approach would meet your goals safely.
6.6. Is orthodontic treatment covered by insurance?
Insurance cover varies by insurer, plan and the reason for treatment. Before starting treatment, check directly with your insurer for the current terms, exclusions, pre-authorisation requirements and reimbursement limits.14.7%的十二歲學生受家長牙科保險保障，而只有19.7%的5歲兒童家長表示受牙科保險或福利計劃保障。
Summary
An underbite can affect the way the teeth meet and, for some people, may be associated with biting, speech, tooth-wear or appearance concerns. Early assessment may help guide planning while children and teenagers are growing. For adults, the appropriate approach depends on the cause and severity of the bite. A qualified dentist or orthodontist can explain the benefits, limitations and alternatives for an individual case.
If you are considering treatment for an underbite, arrange an assessment with a qualified dentist or orthodontist. At Lulusmiles, the clinical team can assess your bite, explain suitable next steps and discuss an individual treatment plan.倒及牙發展階段綫上評估You can also learn more about the type of underbite and the possible next steps.
