Dental health · Prosthodontics
What happens if a missing tooth is not replaced?
The gap left by a missing tooth does not simply stay as it is. The teeth on either side gradually tilt into the space, the opposing tooth erupts further towards the gap, and the bite relationship changes with them; meanwhile the alveolar bone, no longer stimulated by a root, keeps resorbing. A meta-analysis found that at non-molar sites left untreated after extraction, ridge width decreased by about 2.73 mm and height by about 1.71 mm on average. These changes mean that when you do decide to restore the gap later, the conditions are worse than they were at the start.
What actually happens
The gap does not just sit there
Teeth do not stand independently. They support one another through their contact points, and they hold a fixed height through contact with the opposing tooth. Lose one, and that balance is broken.
Neighbouring teeth tilt. The teeth on either side of the gap have lost the neighbour they used to rest against, so they gradually lean into the space. Once they tilt, the gaps between teeth become irregular, food packs in more easily and cleaning gets harder — and decay and periodontal problems rise accordingly.
The opposing tooth over-erupts. Upper and lower teeth normally meet each other; the one that has lost its opponent slowly erupts towards the gap, past its original occlusal plane. By the time you want to restore the missing tooth, that space may already be occupied by the over-erupted tooth, which then has to be dealt with before there is room for a restoration.
The alveolar bone resorbs. Alveolar bone exists to house the tooth root; once the root is gone, the bone gradually resorbs. One meta-analysis reported that at non-molar sites left untreated after extraction, ridge width decreased by about 2.73 mm on average and buccal height by about 1.71 mm; the actual amount of resorption varies with the type of tooth. In practice this means the longer it is left, the more likely an implant later would need an additional bone augmentation procedure.
One qualification: the above describes tendencies, not a timetable. In some people change is very slow; in others it is visible within months. It depends on the site, the bite forces and the bone conditions to begin with, and can only be established by an actual examination.
Three ways to restore
How implants, bridges and dentures differ
None of the three is inherently superior; they differ in what each requires and what each costs you. Which is feasible depends on bone conditions, the state of the neighbouring teeth, how many teeth are missing and general health.
| Dental implant | Fixed bridge | Removable denture | |
|---|---|---|---|
| Does it involve the neighbouring teeth? | No reduction of neighbouring teeth | The teeth on either side must be reduced to serve as abutments | No reduction, but rests on neighbouring teeth and the ridge via clasps or a base |
| Effect on alveolar bone | Placed within the bone, so it can transmit load somewhat like a root | Does not affect the bone at the gap, which continues to resorb | Does not affect resorption; may need adjustment over time as the ridge changes |
| Treatment time | Longer — the implant needs time to integrate with bone | Shorter, usually completed within a few weeks | Shorter |
| Cleaning | Like a natural tooth, but the area around the implant needs particular attention | The underside of the pontic needs cleaning with bridge floss | Removed for cleaning |
| Can it be revised? | Difficult to remove | Once taken off, the abutment teeth have already been reduced and cannot be restored to their original form | Easier to add to or adjust |
| Covered by insurance? | Not covered | Not covered | Not covered |
Long-term performance in the literature: one meta-analysis pooling 20-year follow-up data concluded that about 4 out of every 5 implants were still in service; the 5-year survival of tooth-supported single crowns was around 94.7%–96.6% depending on the material. These are pooled statistics reflecting the study populations. They are not this clinic's treatment outcomes, and they do not represent the expected result for any individual.
There is a government denture subsidy, but not everyone qualifies
Dentures are not covered by national health insurance. However, since the 2009 fiscal year the Ministry of Health and Welfare has funded local governments to run a "denture subsidy programme for low- and middle-income older people". According to the Social and Family Affairs Administration, it applies to people aged 65 and over, or Indigenous people aged 55 and over, who also meet conditions such as being in a low-income or lower-middle-income household or receiving the living allowance for lower-middle-income older people; it also covers some older people receiving disability living allowances.
The subsidy covers full removable dentures, upper or lower half-arch dentures, various partial dentures, fixed prostheses (bridges or crowns) and denture repair costs. Applicants must first be examined and assessed by a dentist at a clinic contracted with national health insurance, and then apply to the city or county government where they are registered. Quotas, amounts and application periods differ between local authorities, so please check with your local social affairs or health bureau for the actual conditions.
What gets assessed
Three things to establish before deciding how to restore
Bone conditions at the site
The height and width of the bone determine whether an implant is possible and whether bone augmentation is needed first. This requires radiographs or three-dimensional imaging — it cannot be judged from appearance at all.
The health of the neighbouring teeth
If the teeth on either side already have large restorations or have had root canal treatment, addressing them as part of a bridge may be reasonable. But where the neighbouring teeth are sound, reducing healthy tooth structure is a cost that has to be weighed.
Whether the periodontium is stable
If periodontal inflammation is not yet under control, every one of these options is being built on unstable ground. The usual approach is to bring the periodontal condition to a stable state first, and discuss restoration after that.
A common misconception
"The one right at the back does not show, so it hardly matters"
Back teeth are not visible, but they carry the greatest share of the bite force. Without one, the chewing load shifts forward onto the front teeth — and the root shape and bone support of front teeth were never designed to take that kind of force. Over time this can lead to wear, loosening or drifting.
Another common pattern is "one side is missing a tooth, so I just chew on the other". Chewing on one side for a long time tends to let calculus build up on the unused side, while the working side carries double the load. This is not an immediate injury, but it accumulates.
Whether to restore, when to restore and by which method — there is no answer that fits everyone. The practical approach is to have an assessment soon after losing the tooth, establish the current bone and neighbouring-tooth conditions, and then decide whether to act or to keep it under observation — rather than waiting until eating becomes noticeably difficult, by which time the conditions are usually already worse.
其他人也問
常見問題
Does a single missing tooth really have to be replaced?
How long can a gap be left before restoring it?
Which is better, an implant or a bridge?
How long does an implant last?
Does insurance cover implants or dentures?
If many teeth are missing, does it have to be a removable denture?
延伸閱讀
相關內容
What makes up the cost of an implant?
The cost structure, the stages of treatment, and when it is not suitable.
Can gum disease be cured?
Why the periodontium has to be stable before any restoration.
Is a crown needed after root canal treatment?
Another common question when keeping a natural tooth.
牙周治療與植牙
牙周治療的階段安排與植牙的評估條件。
醫師團隊
醫師的學經歷與各自負責的診療範圍。
資料來源
本頁的主要依據
下列為本頁內容的來源。文中引用的統計數字皆為文獻或官方公開資料，反映的是整體族群，不是本診所的治療成效。
- Couso-Queiruga E et al.: Dimensional changes of the alveolar ridge after tooth extraction (systematic review and meta-analysis)J Clin Periodontol 2021
- Kupka JR et al.: Implant survival at 20 years (meta-analysis)Clin Oral Investig 2024
- Sailer I et al.: Five-year survival and complications of tooth-supported single crowns (systematic review)Dent Mater 2015
- Social and Family Affairs Administration, Ministry of Health and Welfare: denture subsidy programme for low- and middle-income older people (eligibility and covered items)Social and Family Affairs Administration, Taiwan
本頁為口腔健康知識，內容不能取代醫師的當面診察。每個人的口腔狀況、病史與用藥都不同， 實際診斷與治療方式仍需由醫師依個別情況評估。
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In Taiwan, a dental clinic may only open after it has been approved and registered by the local health authority and issued a practice license under the Medical Care Act, and every practicing dentist must hold a physician certificate issued by the Ministry of Health and Welfare. 君漾美牙醫診所 (JYM Dental Clinic) is a legally established, government-approved medical institution (medical institution code 3701028607), a National Health Insurance contracted clinic (contracted since 2021), and a participant in the NHI Administration's Integrated Periodontal Care Program and Enhanced Infection Control Program for Dental Outpatient Clinics. Every item above can be verified in official public records.