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Can a molar be left unreplaced after extraction? What can happen?｜證據鏈

km 編輯部2026-08-13About 14 min read
#證據鏈#牙醫KM#植牙#牙橋

本頁是〈Can a molar be left unreplaced after extraction? What can happen?〉的事實單元帳：每一條主張對應的來源、證據等級、地域與期間、原文引句與限制，逐條攤開。

Can a molar be left unreplaced after extraction? What can happen?｜證據鏈

F-Units (fact-unit ledger)

  • F1｜confidence: verified｜basis: peer_reviewed（PMID 17559530）｜period: published in 2007｜geo: universal｜span: 「The mean supraeruption for subjects was 1.68 mm (SD 0.79, range 0 to 3.99 mm) and for controls, 0.24 mm (SD 0.39, range 0 to 1.46 mm)」「Supraeruption was found in 92% of subjects' unopposed teeth」「The extent of supraeruption was statistically greater in maxillary unopposed teeth than in mandibular unopposed teeth」｜caveat: diagnostic-model study of 100 cases plus 100 controls, a clinical population rather than a community census
  • F2｜confidence: verified｜basis: peer_reviewed（PMID 17672834）｜period: published in 2007｜geo: universal｜span: 「A statistical significance in the degree of tipping of teeth both mesial and distal to the extraction site was detected between the subject and control groups」「Teeth mesial to the extraction site had a tendency to tip distally」｜caveat: Part 2 of the same series, using the same 100 plus 100 sample
  • F3｜confidence: verified｜basis: peer_reviewed（PMID 17927736）｜period: published in 2008｜geo: universal｜span: 「Unopposed posterior teeth are more likely to be involved in RCP contacts or interferences than their matched controls」「Initial RCP contacts have associations with the extent of supraeruption of the unopposed teeth」「Working side interferences were associated with tipping of the tooth mesial to the extraction site」｜caveat: Part 3 of the same series
  • F4｜confidence: verified｜basis: peer_reviewed（PMID 21902708）｜period: 12-year follow-up; published in 2012｜geo: universal｜span: 「unopposed molars showed 4·9 times higher risk of overeruption of ≥2 mm (95% CI 1·5-15·3)」「The average overeruption for the unopposed molars was 4·5% (s.d. 7·6), which corresponds to approximately 0·9 mm」「The average mesial tipping was 0·8° (s.d. 5·6)」「Molars facing a mesial edentulous space showed a low risk for mesial tipping」｜caveat: prospective study of 292 women; all-female sample
  • F5｜confidence: verified｜basis: peer_reviewed（PMID 17371561）｜period: published in 2007｜geo: universal｜span: 「Partial tooth contact does not appear to prevent or reduce overeruption」「partial tooth contact should not be relied on clinically to maintain vertical tooth position」｜caveat: clinical study of 91 patients
  • F6｜confidence: verified｜basis: peer_reviewed（PMID 16671988）｜period: published in 2006｜geo: universal｜span: 「when a posterior tooth has remained unopposed for 5 years or more positional changes, which cause deviation from the Broadrick curve, occur」「The extent of the deviation may be extreme, potentially leading to difficulties in restoring a harmonious occlusal scheme」｜caveat: technical study of the occlusal curve, not a patient-outcome study
  • F7｜confidence: verified｜basis: peer_reviewed（PMID 17002745; literature review）｜period: searched from 1966 to 2005-11; published in 2006｜geo: universal｜span: 「no clinically significant differences between subjects with shortened dental arches of three to five occlusal units and complete dental arches regarding variables such as masticatory ability, signs and symptoms of temporomandibular disorders, migration of remaining teeth, periodontal support, and oral comfort」「No systematic clinical study with conflicting results was found」｜caveat: narrative review, not a meta-analysis; primarily includes work from one research group
  • F8｜confidence: verified｜basis: peer_reviewed（PMID 29476794; systematic review）｜period: PROSPERO CRD42017064851; published in 2018｜geo: universal｜span: 「there is currently insufficient evidence to recommend one tooth replacement strategy over another in adult patients with reduced dentitions」｜caveat: included 10 papers; authors explicitly noted too few randomised controlled trials
  • F9｜confidence: verified｜basis: peer_reviewed（PMID 28370239; systematic review and meta-analysis）｜period: searched from 1980 to 2016-11; published in 2017｜geo: universal｜span: 「There was no statistically significant difference in OHIP summary scores between SDA and RPDP at 6 (SWMD = 0·24) or 12 (SWMD = 0·40) months post-treatment」「516 participants」｜caveat: only 2 RCTs plus 1 non-RCT; short-term (12-month) results
  • F10｜confidence: verified｜basis: peer_reviewed（PMID 24992473; systematic review）｜period: published in 2014｜geo: universal｜span: 「The shortened dental arch as a treatment option is encouraging in terms of functioning, patient satisfaction and cost-effectiveness」「some of the included studies had to be downgraded due to methodological errors」｜caveat: narrative synthesis; no meta-analysis performed
  • F11｜confidence: verified｜basis: peer_reviewed（PMID 37001792; systematic review）｜period: searched to 2022-11-06; published in 2023｜geo: universal｜span: 「No significant difference was recorded in the nutritional status of patients rehabilitated using the SDA concept compared with RPDs」「Higher costs for treatment provision and maintenance for patients in the RPD group was found when compared to SDA treatment」｜caveat: only 4 reports from 2 RCTs; no meta-analysis possible; the cost conclusion cannot be converted into prices in any region
  • F12｜confidence: verified｜basis: peer_reviewed（PMID 22733244; multicentre RCT, 5 years）｜period: published in 2013｜geo: universal｜span: 「the Kaplan-Meier survival rates at 5 years were 0.74 (95% CI 0.64, 0.84) in the PRDP group and 0.74 (95% CI 0.63, 0.85) in the SDA group」「For tooth loss in the study jaw, the survival rates at 5 years were 0.88 … and 0.84 …. The differences were not significant」｜caveat: 152 people received treatment and 132 reached 5-year follow-up; German multicentre study
  • F13｜confidence: verified｜basis: peer_reviewed（PMID 29316570; same RCT, 10 years）｜period: published in 2018｜geo: universal｜span: 「the survival rates for tooth loss at 10 years were 0.44 (95% confidence interval [CI]: 0.30 to 0.56) in the PRDP group and 0.52 (95% CI: 0.37 to 0.65) in the SDA group」「The number of teeth lost was higher than expected」「The results suggest an overestimation of the influence of the prosthetic management of the bilateral SDA」「For tooth loss in the study arch, the survival rates were 0.67 (95% CI: 0.52 to 0.78) in the PRDP group and 0.60 (95% CI: 0.45 to 0.73) in the SDA group.」｜caveat: 82 of 152 people reached the 10-year examination; attrition was high
  • F14｜confidence: verified｜basis: peer_reviewed（PMID 26066662; systematic review）｜period: searched from 2003 to 2014; published in 2015｜geo: universal｜span: 「Subjects with (E)SDA had a 30-40% reduced masticatory performance」「Comminution or mixing ability in subjects with (E)SDA was 28-39% lower compared to that of subjects with complete dentitions」「distal-extension RDPs could compensate this reduction partially (some 50%)」「more artificial teeth in RDPs resulted in better performance」｜caveat: SDA means 3 to 5 posterior occlusal pairs and ESDA means 0 to 2; few studies were included
  • F15｜confidence: verified｜basis: peer_reviewed（PMID 34761421; systematic review）｜period: searched from 1966 to 2020; published in 2022｜geo: universal｜span: 「Two retrospective studies indicated that RDPs increased the risk of tooth loss compared to FDPs in patients with a history of periodontitis」「Several studies indicated that RDP increased plaque accumulation」「There is no strong evidence that RDPs per se will cause periodontal destruction including tooth loss」｜caveat: heterogeneous data; no meta-analysis; population limited to patients with periodontitis
  • F16｜confidence: verified｜basis: peer_reviewed（PMID 23062124; systematic review and meta-analysis）｜period: searched from 2006 to 2011; published in 2012｜geo: universal｜span: 「Based on the meta-analysis, survival of implants supporting SCs at 5 years amounted to 97.2% (95% CI: 96.3-97.9%), and at 10 years amounted to 95.2% (95% CI: 91.8-97.2%).」「The survival of implant-supported SCs was 96.3% (95% CI: 94.2-97.6%) after 5 years and 89.4% (95% CI: 82.8-93.6%) after 10 years.」「8.8% (95% CI: 5.1-15.0%) for screw-loosening, 4.1% (95% CI: 2.2-7.5%) for loss of retention, and 3.5% (95% CI: 2.4-5.2%) for fracture of the veneering material」「technical, biological, and aesthetic complications were frequent」「For biological complications, a 5-year cumulative soft tissue complication rate of 7.1% (95% CI: 4.4-11.3%) and a cumulative complication rate for implants with bone loss >2 mm of 5.2% (95% CI: 3.1-8.6%) were calculated.」「Based on the meta-analysis, survival of implants supporting SCs at 5 years amounted to 97.2% (95% CI: 96.3-97.9%), and at 10 years amounted to 95.2% (95% CI: 91.8-97.2%).」｜caveat: included 46 studies; survival is not success and does not equal an individual expectation
  • F17｜confidence: verified｜basis: peer_reviewed（PMID 25935732; systematic review and meta-analysis）｜period: searched from 2006 to 2013; published in 2015｜geo: universal｜span: 「an estimated 5-year survival rate of metal-ceramic FDPs of 94.4% (95% CI: 91.2-96.5%)」「densely sintered zirconia FDPs was 90.4%」「A significantly higher incidence of caries in abutment teeth was observed for densely sintered zirconia FDPs compared to metal-ceramic FDPs」「framework fractures … reinforced glass ceramic FDPs (8.0%) and glass-infiltrated alumina FDPs (12.9%) compared to metal-ceramic FDPs (0.6%) and densely sintered zirconia FDPs (1.9%)」「The estimated survival rate of reinforced glass ceramic FDPs was 89.1% (95% CI: 80.4-94.0%), the survival rate of glass-infiltrated alumina FDPs was 86.2% (95% CI: 69.3-94.2%) and the survival rate of densely sintered zirconia FDPs was 90.4% (95% CI: 84.8-94.0%) in 5 years of function.」｜caveat: multiple-unit fixed dental prostheses; substantial differences by material
  • F18｜confidence: verified｜basis: peer_reviewed（PMID 23062127; systematic review）｜period: published in 2012｜geo: universal｜span: 「Initial costs for single implant crowns and FDPs on teeth were similar, but varied between tariff systems」「Failure rates reported with single implant crowns and FDPs on teeth were similar」「The utility for the patient to keep healthy adjacent teeth unprepared makes the implant crown more economic」｜caveat: economic review; payment systems vary by country; this card cites no monetary amount
  • F19｜confidence: verified｜basis: peer_reviewed（PMID 35258700; systematic review and meta-analysis）｜period: published in 2022｜geo: universal｜span: 「The meta-analytic study of overall survival included a total of 14 studies, yielding an overall survival rate of 97.9%」「the 5- and 10-year survival rates were 95.9% and 96.9%」｜caveat: limited to transplanted teeth whose roots had not completed development; not applicable to closed apices
  • F20｜confidence: verified｜basis: peer_reviewed（PMID 25903060; systematic review and meta-analysis）｜period: published in 2015｜geo: universal｜span: 「Teeth with open apex were less likely to be extracted in comparison to teeth with closed apex (3 studies; 413 teeth; relative risk 0.3; 95% confidence interval 0.2-0.6)」「Reported complications included the need for extraction, failure, hypermobility, pulp necrosis, pulp obliteration, and root resorption」「no firm conclusions can be drawn」｜caveat: authors explicitly said firm conclusions cannot be drawn because of few studies, methodological limitations, and heterogeneity
  • F21｜confidence: verified｜basis: peer_reviewed（PMID 36898857; umbrella review）｜period: searched to 2022-09-25; published in 2023｜geo: universal｜span: 「Seventeen SRs met the inclusion criteria」「The 5-year and 10-year survival rates were >95%」「Five SRs were rated as 'low quality' and 12 SRs were rated as 'critically low quality' in the AMSTAR 2 RoB assessment」｜caveat: quality ratings of included reviews were low; figures require cautious interpretation
  • F22｜confidence: verified｜basis: peer_reviewed（PMID 26696138; systematic review and meta-analysis）｜period: studies with follow-up of 6 years or more; published in 2016｜geo: universal｜span: 「Survival rates ranged from 75.3% to 91% and the meta-analysis showed an effect size of 81%」「The percentage ankylosis ranged from 4.2% to 18.2% and the effect size was 4.8%」「Root resorption percentages ranged from 3% to 10% and the effect size was equal to 4%」｜caveat: only 6 studies included; long-term figures are lower than short-term studies, so this card presents both rather than choosing one
  • F23｜confidence: verified｜basis: peer_reviewed（PMID 16527628; retrospective study）｜period: published in 2006｜geo: universal｜span: 「The subjects were 48 patients who had 128 permanent second molars extracted during or before orthodontic treatment. Their ages at extraction were 11 to 23 years」「The median time of eruption was 3 to 4 years」「A total of 96.2% of the maxillary and 66.2% of the mandibular third molars erupted in good positions」「Unsuccessful third-molar eruptions occurred in older patients who had higher Nolla developmental stages」｜caveat: population limited to adolescents and young adults undergoing orthodontic treatment; cannot be applied to general adult patients
  • F24｜confidence: verified｜basis: peer_reviewed（PMID 22211303; systematic review）｜period: published in 2012; included 20 papers｜geo: universal｜span: 「horizontal dimensional reduction (3.79 ± 0.23 mm) was more than vertical reduction (1.24 ± 0.11 mm on buccal, 0.84 ± 0.62 mm on mesial and 0.80 ± 0.71 mm on distal sites) at 6 months」「Percentage vertical dimensional change was 11-22% at 6 months. Percentage horizontal dimensional change was 32% at 3 months, and 29-63% at 6-7 months」「Soft tissue changes demonstrated 0.4-0.5 mm gain of thickness at 6 months」｜caveat: limited to untreated, naturally healing extraction sockets; same-family anchor as this site’s card #28
  • F25｜confidence: verified (HTTP 200 and verbatim match verified on 2026-08-05; same anchor as card #9 C2 and card #28 F16)｜basis: law｜period: current text｜geo: TW｜span: 《全民健康保險法》第 51 條「下列項目不列入本保險給付範圍：……十一、義齒、義眼、眼鏡、助聽器、輪椅、拐杖及其他非具積極治療性之裝具。」｜caveat: individual coverage is subject to current National Health Insurance Administration notices; this card makes no coverage determination
  • F26｜confidence: verified (HTTP 200 and verbatim match verified on 2026-08-05)｜basis: law｜period: current text｜geo: TW｜span: 《醫療法》第 81 條「醫療機構診治病人時，應向病人或其法定代理人、配偶、親屬或關係人告知其病情、治療方針、處置、用藥、預後情形及可能之不良反應。」｜caveat: quotation of the statute, not legal advice
  • F27｜confidence: verified (HTTP 200 verified on 2026-08-05)｜basis: official_statement｜period: dataset’s current status｜geo: TW｜span: 政府資料開放平臺資料集「臺北市醫療收費標準」，提供機關臺北市政府衛生局｜caveat: example from one city; each other city or county page must be individually verified before scale-up; same anchor family as card #9 C3
  • F28｜confidence: verified (entry point accessible; HTTP 200 verified on 2026-08-05)｜basis: official_statement｜period: entry point’s current status｜geo: TW｜span: 健保署醫材比價網入口 info.nhi.gov.tw/INAE2000/INAE2010S01｜caveat: page contents load dynamically with JS and cannot be compared verbatim with curl; whether missing-tooth-reconstruction items are within the searchable scope must be verified before publication (same unverified remainder as card #9 C4); OP correction after testing on 2026-08-05: the site does not include dental items, so missing-tooth-reconstruction items cannot be checked there
  • F29｜confidence: verified｜basis: internal_data｜period: GSC from 2025-03 to 2026-08｜geo: TW｜span: backlog #34「第二大臼齒拔掉不補」等 7 詞項合計曝光 107,506，跨 4 站｜caveat: impressions are asset-level figures, not deduplicated traffic; clinic list follows the #34 column of the queue page and must not be added to or deleted from
  • F30｜confidence: structural editorial synthesis (not an external factual claim)｜basis: editorial_framework｜period: 2026-08-05｜geo: universal｜span: 「三個問題的拆解」與「短牙弓適用／不適用條件對照」為本站依 F1 至 F24 文獻整理的溝通用架構｜caveat: not a clinical criterion or diagnostic tool; does not replace a dentist’s assessment

Sources

All sources were accessed on 2026-08-05. PubMed abstracts were retrieved through E-utilities efetch for verbatim comparison, and each record page was tested individually for an HTTP 200 response.

  1. Craddock HL, Youngson CC. Occlusal changes following posterior tooth loss in adults. Part 1. J Prosthodont. 2007. PMID 17559530
  2. Craddock HL, et al. Occlusal changes following posterior tooth loss in adults. Part 2. J Prosthodont. 2007. PMID 17672834
  3. Craddock HL, et al. Occlusal changes following posterior tooth loss in adults. Part 3. J Prosthodont. 2008. PMID 17927736
  4. Christou P, Kiliaridis S, et al. Changes in molar position associated with missing opposed and/or adjacent tooth: a 12-year study in women. J Oral Rehabil. 2012. PMID 21902708
  5. Craddock HL. An investigation of overeruption of posterior teeth with partial occlusal contact. J Oral Rehabil. 2007. PMID 17371561
  6. Craddock HL, et al. Deviation from the Broadrick occlusal curve following posterior tooth loss. J Oral Rehabil. 2006. PMID 16671988
  7. Kanno T, Carlsson GE. A review of the shortened dental arch concept focusing on the work by the Käyser/Nijmegen group. J Oral Rehabil. 2006. PMID 17002745
  8. McKenna G, et al. Effectiveness of prosthodontic interventions and survival of remaining teeth in adult patients with shortened dental arches — A systematic review. J Dent. 2018. PMID 29476794
  9. Reissmann DR, et al. Shortened dental arch and prosthetic effect on oral health-related quality of life: a systematic review and meta-analysis. J Oral Rehabil. 2017. PMID 28370239
  10. Khan SB, et al. Differences in functional outcomes for adult patients with prosthodontically-treated and -untreated shortened dental arches: a systematic review. PLoS One. 2014. PMID 24992473
  11. Impact of shortened dental arch therapy on nutritional status and treatment costs in older adults: A systematic review. J Dent. 2023. PMID 37001792
  12. Walter MH, et al. The randomized shortened dental arch study: tooth loss over five years. Clin Oral Investig. 2013. PMID 22733244
  13. Walter MH, et al. The Randomized Shortened Dental Arch Study: Tooth Loss Over 10 Years. Int J Prosthodont. 2018. PMID 29316570
  14. Effects of removable dental prostheses on masticatory performance of subjects with shortened dental arches: A systematic review. J Dent. 2015. PMID 26066662
  15. Efficacy and risks of removable partial prosthesis in periodontitis patients: A systematic review. J Clin Periodontol. 2022. PMID 34761421
  16. Jung RE, et al. Systematic review of the survival rate and the incidence of biological, technical, and aesthetic complications of single crowns on implants reported in longitudinal studies with a mean follow-up of 5 years. Clin Oral Implants Res. 2012. PMID 23062124
  17. Sailer I, et al. All-ceramic or metal-ceramic tooth-supported fixed dental prostheses (FDPs)? Part II: Multiple-unit FDPs. Dent Mater. 2015. PMID 25935732
  18. Brägger U, et al. Implants versus short-span fixed bridges: survival, complications, patients' benefits. A systematic review on economic aspects. Clin Oral Implants Res. 2012. PMID 23062127
  19. Autotransplantation of teeth with incomplete root formation: systematic review and meta-analysis. Clin Oral Investig. 2022. PMID 35258700
  20. Machado LA, et al. Autotransplantation of teeth in humans: a systematic review and meta-analysis. Clin Oral Investig. 2015. PMID 25903060
  21. Tooth autotransplantation: An umbrella review. Dent Traumatol. 2023. PMID 36898857
  22. Almpani K, et al. Long-term prognosis of tooth autotransplantation: a systematic review and meta-analysis. Int J Oral Maxillofac Surg. 2016. PMID 26696138
  23. Spontaneous third-molar eruption after second-molar extraction in orthodontic patients. Am J Orthod Dentofacial Orthop. 2006. PMID 16527628
  24. Tan WL, et al. A systematic review of post-extractional alveolar hard and soft tissue dimensional changes in humans. Clin Oral Implants Res. 2012. PMID 22211303
  25. Taiwan National Health Insurance Act, Article 51 (Laws & Regulations Database of the Republic of China (Taiwan))
  26. Taiwan Medical Care Act (official English translation; Article 81) (Laws & Regulations Database of the Republic of China (Taiwan))
  27. Government Open Data Platform: Taipei City Medical Fee Standards (provided by the Taipei City Department of Health)
  28. National Health Insurance Administration Medical Materials Price Comparison Website (entry point)
  29. Internal data: `analysis/reports/km-dental-backlog.md`, appendix #34 (query × site × impression records can be reconciled line by line)
  30. Editorial framework: this site’s “three questions” breakdown and SDA applicability comparison (no external source; labelled as structural synthesis)

Internal links

  • Post-extraction alveolar-bone changes and bone-grafting management: Can bone-graft material have after-effects? What if it fails? (KM-DENTAL-28)
  • How to ask about costs and read an estimate: How much does one implant really cost? (KM-DENTAL-09)
  • Separating the meanings of “dental crown” (orthodontic appliance versus prosthetic crown): How much does a “dental crown” cost? (KM-DENTAL-08)
Publication-gate reminder: this card is a draft. It must not enter km_entries until all four languages (zh-Hans/en/ja) exist. Until the scope of missing-tooth-reconstruction items in F28 is verified, retain the sentence as a “way to check” and do not rewrite it as a price statement.

FAQ

Is it really okay not to replace an extracted second molar?
**The literature does discuss maintaining function without replacement, but only under conditions.** SDA literature concerns people with three to five occlusal units and intact anterior and premolar occlusion; it generally found no clinically significant difference in masticatory ability, temporomandibular symptoms, migration of remaining teeth, or periodontal support [F7]. At the same time, 92% of unopposed teeth in the study population showed overeruption (with large individual variation in amount) [F1], and masticatory performance declines more as fewer occlusal pairs remain [F14]. Whether it is “okay” depends on your remaining occlusion and requires a dentist’s assessment.
第二大臼歯を抜いて補わなくても、本当に大丈夫ですか？ — **補わずに機能を保てるという文献上の議論はありますが、条件付きです。** SDA 文献の場面は、三から五の咬合単位があり、前歯と小臼歯の咬合が保たれた人です。咀嚼能力、顎関節症状、残存歯の移動、歯周支持には一般に臨床的有意差がないとされます [F7]。一方、研究対象の対合歯のない歯の 92% に挺出があり（量の個人差は大きい）[F1]、残る咬合対が少ないほど咀嚼能率の低下は大きくなります [F14]。大丈夫かは残る咬合状態によるため、歯科医師の評価が必要です。
Is it really okay not to replace an extracted second molar? — **The literature does discuss maintaining function without replacement, but only under conditions.** SDA literature concerns people with three to five occlusal units and intact anterior and premolar occlusion; it generally found no clinically significant difference in masticatory ability, temporomandibular symptoms, migration of remaining teeth, or periodontal support [F7]. At the same time, 92% of unopposed teeth in the study population showed overeruption (with large individual variation in amount) [F1], and masticatory performance declines more as fewer occlusal pairs remain [F14]. Whether it is “okay” depends on your remaining occlusion and requires a dentist’s assessment.
If I do not replace it, when will teeth start to shift?
**The literature does not give one universal point such as “after a certain number of months,” but it provides several time frames.** The 12-year study records long-term accumulation: unopposed molars had 4.9 times the risk of overeruption of 2 mm or more and a mean of approximately 0.9 mm [F4]. Another study recorded deviation in the occlusal curve after a posterior tooth had been unopposed for 5 years or more [F6]. Alveolar-bone changes can be measured within 6 months after extraction (horizontal reduction 3.79 ± 0.23 mm) [F24]. Individual rates vary greatly.
補わないと、いつから歯が動きますか？ — **文献に「何か月後から」という共通の時点はありませんが、複数の時間尺度があります。** 12 年研究は長期の蓄積を記録し、対合歯のない大臼歯で 2 mm 以上の挺出リスクは 4.9 倍、平均は約 0.9 mm でした [F4]。別研究では後方歯に 5 年以上対合歯がないと咬合曲線の位置逸脱が記録されました [F6]。歯槽骨の変化は抜歯後 6 か月以内にも測定可能で、水平減少は 3.79 ± 0.23 mm でした [F24]。個人差は大きいです。
If I do not replace it, when will teeth start to shift? — **The literature does not give one universal point such as “after a certain number of months,” but it provides several time frames.** The 12-year study records long-term accumulation: unopposed molars had 4.9 times the risk of overeruption of 2 mm or more and a mean of approximately 0.9 mm [F4]. Another study recorded deviation in the occlusal curve after a posterior tooth had been unopposed for 5 years or more [F6]. Alveolar-bone changes can be measured within 6 months after extraction (horizontal reduction 3.79 ± 0.23 mm) [F24]. Individual rates vary greatly.
Can a wisdom tooth replace an extracted molar?
**The literature describes two routes, but both have strict conditions.** After second-molar extraction in adolescent orthodontic patients, 96.2% of maxillary and 66.2% of mandibular third molars erupted into a good position, with a median eruption time of 3 to 4 years; success was lower with older age [F23]. For tooth autotransplantation, pooled survival with open apices was 97.9% (96.9% at 10 years) [F19], but a meta-analysis with follow-up of 6 years or more reported survival of 75.3% to 91% (effect size 81%), with ankylosis 4.8% and root resorption 4%; closed-apex teeth had a greater risk of extraction [F20][F22]. Feasibility requires imaging assessment by a dentist.
親知らずで抜いた臼歯を置き換えられますか？ — **文献には二つの道がありますが、どちらも条件は厳格です。** 青年矯正患者で第二大臼歯を抜いた後、第三大臼歯が良好な位置へ自然萌出した割合は上顎 96.2%、下顎 66.2%、萌出期間中央値は 3 から 4 年で、年齢が高いほど成功は少なくなりました [F23]。自家歯牙移植では根尖未閉鎖歯の統合生存率は 97.9%（10 年 96.9%）[F19] ですが、6 年以上追跡したメタ解析では 75.3% から 91%（効果量 81%）、癒着 4.8%、歯根吸収 4% とされ、根尖閉鎖歯は抜去リスクが高いです [F20][F22]。可能性は歯科医師が画像で評価します。
Can a wisdom tooth replace an extracted molar? — **The literature describes two routes, but both have strict conditions.** After second-molar extraction in adolescent orthodontic patients, 96.2% of maxillary and 66.2% of mandibular third molars erupted into a good position, with a median eruption time of 3 to 4 years; success was lower with older age [F23]. For tooth autotransplantation, pooled survival with open apices was 97.9% (96.9% at 10 years) [F19], but a meta-analysis with follow-up of 6 years or more reported survival of 75.3% to 91% (effect size 81%), with ankylosis 4.8% and root resorption 4%; closed-apex teeth had a greater risk of extraction [F20][F22]. Feasibility requires imaging assessment by a dentist.

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km 編輯部・《Can a molar be left unreplaced after extraction? What can happen?｜證據鏈》・IDAEO 知識庫・2026-08-13・https://km.idaeo.ai/reports/dental-molar-extraction-no-replacement-evidence

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更新 2026-08-13T16:13:14.254Z · server-rendered · four-language · IDAEO 知識庫