How Many Days Will a Root Canal Hurt? How Long Does the Whole Course Take?｜證據鏈

How Many Days Will a Root Canal Hurt? How Long Does the Whole Course Take?｜證據鏈

F-Units (fact ledger)

• F1｜Topic-selection basis: reconciled full GSC data from 14 clinic sites; the 3 query terms 「牙齒抽神經會痛幾天」 and 「牙齒抽神經要多久」 total 114,830 impressions across 2 sites .｜Source #19｜confidence=high｜basis=internal_dataset｜period=GSC retention window (from 2025-03-22)｜geo: TW｜caveat: impressions are attribute-level figures, not deduplicated traffic; internal data, not a medical claim, and not for the published visible layer.
• F2｜Pain prevalence: 81% before treatment (standard deviation 28), 40% at 24 hours (standard deviation 24), 11% at one week (standard deviation 14); pain intensity on a 0-to-100 scale was respectively 54 (standard deviation 24), 24 (standard deviation 12), and 5 (standard deviation 5); the review meta-analysed 72 studies.｜Source #1｜confidence=moderate｜basis=peer_reviewed (systematic review and meta-analysis)｜period=2011 (search on 2026-08-06 found no newer general-prevalence review superseding this one)｜geo: universal｜caveat: parenthetical values are standard deviations, not confidence intervals; population average with large individual variation; this card does not cite the paper's supplementary anaesthesia figures (different original notation and percentages).
• F3｜Same paper's conclusion: pretreatment root-canal-associated pain prevalence was high, declined moderately within one day after treatment, and declined substantially to minimal levels within 7 days; intensity declined in the same direction.｜Source #1｜confidence=moderate｜basis=peer_reviewed｜period=2011｜geo: universal｜caveat: a population-level directional conclusion; must not be restated as a number-of-days promise to an individual.
• F4｜Current Cochrane review outcome framework: primary outcomes were extraction and radiological failure (periapical radiolucency) at least one year after treatment; secondary outcomes were postoperative and postobturation pain, swelling or flare-up, analgesic use, and sinus tract or fistula after at least one month. No difference was detected in pain through 72 hours after obturation (risk ratio 0.97, 95% confidence interval 0.81 to 1.16; I²=70%; 12 studies, 1329 teeth; low certainty), nor in pain at one week (risk ratio 1.05, 95% confidence interval 0.67 to 1.67; 9 studies, 1139 teeth; very low certainty).｜Source #2｜confidence=high (outcome framework)／moderate (figures)｜basis=peer_reviewed (Cochrane SR/MA, current pub4)｜period=2022 (search cut-off 2022-04-25; PubMed search of CD005296 on 2026-08-06 found only the 2007／2016／2022 editions, no pub5)｜geo: universal｜caveat: used for the time-point framework and no-difference findings, not as an efficacy-comparison conclusion.
• F5｜Proportion of participants reporting pain within one week was higher with single visits: risk ratio 1.55 (95% confidence interval 1.14 to 2.09; I²=18%; 5 studies, 638 teeth; moderate certainty); vital-teeth subgroup risk ratio 2.16 (2 studies, 316 teeth).｜Source #2｜confidence=moderate｜basis=peer_reviewed｜period=2022｜geo: universal｜caveat: full discussion belongs to KM-DENTAL-18; this card only summarises and links to it. Its direction is not completely aligned with the F10 umbrella review, so both are presented.
• F6｜No difference was detected in swelling or flare-up incidence (risk ratio 0.56, 95% confidence interval 0.16 to 1.92; I²=0%; 6 studies, 605 teeth; very low certainty), nor in analgesic use (risk ratio 1.25, 95% confidence interval 0.75 to 2.09; I²=36%; 6 studies, 540 teeth; very low certainty).｜Source #2｜confidence=low (very-low certainty in original)｜basis=peer_reviewed｜period=2022｜geo: universal｜caveat: very-low-certainty evidence, used only to show these are followed events and not controlled by choosing visit number; must not be used to infer any management recommendation. The analgesic item only identifies an outcome; this card gives no medication advice.
• F7｜Same authors' conclusion: as with the preceding two editions, there is no evidence that either single- or multiple-visit treatment is more effective; neither regimen can prevent pain and other complications during the 12-month postoperative period.｜Source #2｜confidence=high｜basis=peer_reviewed｜period=2022｜geo: universal｜caveat: statement of no difference and inability to prevent, not evidence that either arrangement is superior.
• F8｜Prospective clinical study: 270 patients receiving single-visit root-canal treatment recorded pain and analgesic use at 4, 8, 16, 24, 48, and 72 hours on a 0-to-10 cm visual analogue scale; mean postoperative pain was 2.58 (standard deviation 2.80); authors concluded preoperative pain presence most influenced postoperative pain prevalence.｜Source #3｜confidence=low｜basis=peer_reviewed (single-centre prospective study)｜period=2016｜geo: universal｜caveat: the original marked P>.05 in comparisons of related variables (sex, mandible, molar); this card therefore uses only the measurement points and mean, and presents preoperative pain as a directional observation, not a conclusion.
• F9｜2024 systematic review and meta-analysis (57 studies qualitatively synthesised, 3 meta-analysed): moderate-to-severe postoperative pain was more common at 48 through 72 hours after root-canal treatment; severe-pain frequency was very low in both vital-pulp-therapy and root-canal-treatment groups.｜Source #4｜confidence=moderate｜basis=peer_reviewed (SR/MA)｜period=2024 (searched to 2022-06-30)｜geo: universal｜caveat: primary comparison was vital pulp therapy versus single-visit root-canal treatment, not this question; the original sentence covers both treatments. This card uses only the root-canal timing distribution and infrequent severe pain, with no between-group inference.
• F10｜2026 umbrella review (databases searched from inception to 2025-12) included 12 systematic reviews: postoperative pain was usually measured with visual-analogue or numeric-rating scales at prespecified points; flare-up outcomes were inconsistently reported and variably defined; higher-confidence reviews showed no consistent or clinically important difference in postoperative pain between single and multiple visits; visit strategy may instead be guided by case complexity, infection control, patient preference, and logistics.｜Source #5｜confidence=moderate｜basis=peer_reviewed (umbrella review)｜period=2026｜geo: universal｜caveat: authors state confidence is limited by heterogeneous outcome definitions and primary-study overlap.
• F11｜Prospective clinical study: flare-up is operationally defined as pain and/or swelling requiring emergency treatment between appointments; incidence was 1.71% among 408 teeth receiving endodontic therapy; chi-square testing showed a direct correlation with presence of periradicular radiolucency.｜Source #6｜confidence=low｜basis=peer_reviewed (single-institution prospective study)｜period=2010 (enrolment 2006-06 to 2007-06)｜geo: universal｜caveat: one dental institution and 408 teeth; must not be treated as a general-population incidence. Used to define flare-up and show it is a recorded event. ⚠️ Terminology check (span reread 2026-08-06): this source says `periradicular radiolucency` (around the root), while F4 says `periapical radiolucency` (at the apex); they are different terms from different sources and must not be substituted or merged.
• F12｜Narrative review: flare-up is acute exacerbation of an initially asymptomatic pulpal and/or periradicular pathologic condition; interappointment pain results from mechanical, chemical, and/or microbial injury to pulp or periradicular tissues, including root-canal overinstrumentation and filling-material extrusion through the apical foramen.｜Source #7｜confidence=low｜basis=peer_reviewed (narrative review, not meta-analysis)｜period=2014｜geo: universal｜caveat: no quantified risk; used only for definition and cause categories. ⚠️ Terminology check (span reread 2026-08-06): `overinstrumentation of the root canal` is translated as “root-canal overinstrumentation.” Earlier prose made it specific to exceeding a length; the source gives no length reference, so it was restored to the source's general wording (old wording intentionally not reproduced).
• F13｜Systematic review and meta-analysis (12 qualitative, 9 quantitative studies): occlusal adjustment did not show reduced postoperative pain at 6, 12, 24, and 48 hours after instrumentation or at 6 and 12 hours after obturation; GRADE certainty was moderate.｜Source #8｜confidence=moderate｜basis=peer_reviewed (SR/MA)｜period=2021 (searched to 2021-04; same-topic search on 2026-08-06 found two 2020 reviews and no update after 2022)｜geo: universal｜caveat: “no difference detected,” not “must not be done”; bite adjustment is a clinical judgement.
• F14｜Systematic review and meta-analysis with trial sequential analysis: 18 studies and 1192 participants; compared with no intracanal medication, calcium hydroxide was associated with lower pain at 24 hours (standardised mean difference -0.71, 95% confidence interval -1.38 to -0.03; 4 trials, 226 participants; I²=78%; moderate certainty); authors said substantial heterogeneity limited robustness.｜Source #9｜confidence=moderate｜basis=peer_reviewed (SR/MA)｜period=2022｜geo: universal｜caveat: search on 2026-08-06 also found a 2023 same-topic review (PMID 37205901, 9 studies) with pooled mean difference -4.57 (confidence interval -16.25 to 7.11), I²=95%, and an interval crossing 0. Coexistence means the evidence has not converged; used only to explain why medication may be placed between visits, not to recommend any material or procedure.
• F15｜2026 randomised clinical trial: 59 patients with necrotic pulp and apical lesions randomised (single visit 28／two visits 31); calcium hydroxide placed intracanal for 10 to 14 days in the two-visit group; mean follow-up 2.8 years and 42 completed; healing outcome had no statistically significant difference, and authors expressly did not demonstrate superiority, noninferiority, or equivalence.｜Source #10｜confidence=low｜basis=peer_reviewed (single RCT, small sample)｜period=2026｜geo: universal｜caveat: cited only as one actual 10-to-14-day interval example; must not be read as a recommended interval or evidence that two visits are better.
• F16｜Eight-year retrospective study (posteriors treated 2008 to 2016 in an institute-level endodontic department): crowns placed after 4 months were associated with about 3 times the likelihood of extraction versus crowns within 4 months (hazard ratio 3.38, 95% confidence interval 1.56 to 6.33, P = .002); composite-resin or amalgam core buildup versus crown was 2.29 times (95% confidence interval 1.29 to 4.06, P = .005).｜Source #11｜confidence=low｜basis=peer_reviewed (single-institution retrospective study)｜period=2016｜geo: universal｜caveat: retrospective design supports association only; posterior teeth at a teaching unit; direction differs from F17, so both are presented without convergence.
• F17｜Swedish Social Insurance Agency registry study: 50314 direct restorations after first-molar root-canal treatment in 2009, grouped by time from root-canal filling to direct restoration; no statistically significant time-dependent difference in 5-year orthograde retreatment (meaning nonsurgical retreatment through the crown and existing root-canal path) (p = 0.089), apical surgery (p = 0.161), or extraction (p = 0.737); authors concluded elapsed time did not affect 5-year outcome. Background cited in-vitro leakage studies suggesting temporary restorations provide only a short-term seal.｜Source #12｜confidence=moderate｜basis=peer_reviewed (national registry retrospective study)｜period=2025 (data year 2009, 5-year follow-up)｜geo: universal (Swedish data, not institutional content)｜caveat: direct restorations, not crowns, so not the same question as F16; registry has no clinical detail; the short-term-seal point is cited in-vitro background, not this study's clinical result.
• F18｜Systematic review and meta-analysis: persistent tooth pain defined as pain at six months or longer after treatment; 26 studies, 5777 teeth enrolled, 2996 with follow-up data; estimated prevalence 5.3% (95% confidence interval 3.5% to 7.2%), high heterogeneity (I²=80%); subgroup estimates 7.6% prospective and 0.9% retrospective.｜Source #13｜confidence=moderate｜basis=peer_reviewed (SR/MA)｜period=2010 (search on 2026-08-06 found no newer meta-analysis replacing it)｜geo: universal｜caveat: high heterogeneity; used for “persistent pain needs return and reassessment,” not personal-risk estimation.
• F19｜Retrospective study: among 97 patients hospitalised for odontogenic infection, 19 (20%) had deep neck-space infection; mandibular origin 16/55 (29%) exceeded maxillary origin 3/42 (7%) (P ≤ 0.009). Authors stated that, besides classic criteria (fever, neck swelling, dyspnoea, dysphagia, trismus, leukocytosis, elevated C-reactive protein), admission criteria should include mandibular odontogenic infection and dental abscess.｜Source #14｜confidence=low｜basis=peer_reviewed (single-medical-centre retrospective cohort)｜period=2015 (enrolment 2008-01 to 2012-06)｜geo: universal｜caveat: population was already-hospitalised otolaryngology patients; these are clinician admission criteria, not a patient self-diagnosis tool. Red flags and immediate-care routing are conservative editorial decisions.
• F20｜Article 81 of Taiwan's Medical Care Act: when treating a patient, a medical care institution shall inform the patient or the patient's legal representative, spouse, relative, or related person of the condition, treatment policy, procedure, medication, prognosis, and possible adverse reactions.｜Source #15｜confidence=high｜basis=law｜period=current text (verified live with ego-browser on 2026-08-06; page title “Medical Care Act§81—Laws & Regulations Database of the Republic of China (Taiwan)”; text matched verbatim)｜geo: TW｜caveat: statutory paraphrase, not legal advice; this card routes all medication questions back to the dentist and gives no medication advice.　[On the official page the label appears in Chinese only: 「醫療法§81-全國法規資料庫」]
• F21｜Article 87(2) of Taiwan's Medical Care Act: publication of medical knowledge or research reports, patient health education, and academic publications that do not solicit medical business are not deemed medical advertising.｜Source #16｜confidence=high｜basis=law｜period=current text (verified live with ego-browser verbatim on 2026-08-06)｜geo: TW｜caveat: basis for this card's positioning.
• F22｜Article 41(1) of Taiwan's National Health Insurance Act: medical-service benefit items and payment standards are jointly drafted by the insurer and representatives of relevant agencies, experts and scholars, insured persons, employers, and contracted providers, then submitted to the competent authority for approval and publication.｜Source #17｜confidence=high｜basis=law｜period=current text (verified live with ego-browser verbatim on 2026-08-06)｜geo: TW｜caveat: directs payment questions to the National Health Insurance Administration's current notices and the cost card; makes no individual coverage determination.
• F23 [structural editorial]｜The three-level observation framework (research-point reactions／active return visit／immediate-care red flags); the canonical division with KM-DENTAL-18／26; and the conservative safety-net wording “return if the pain trajectory reverses,” “arrange an active return visit for swelling or fistula,” and “return for a dislodged temporary filling” are this site's editorial structure and decisions, not factual claims or literature-derived thresholds.｜confidence=n/a｜basis=editorial｜geo: TW｜caveat: must not be marked pending verification (that would manufacture false verification work). ⚠️ Hard rule after CX adversarial review 29-1 on 2026-08-06: Level 1 once called F9's 48-to-72-hour population measurement window an expected range, turning it into a personal waiting range; Level 2, checklist, and FAQ also made 72 hours an action threshold. All were removed (old sentence intentionally not reproduced). This card must never use a “return only after N hours／N days” threshold. Return triggers must be stated as trajectory (worsening or worsening again after improvement) and signs (swelling, fistula); a reversal on day one and day three is handled equally.
• F24 [structural editorial]｜The four-period question framework “course = number of visits + interval between visits + definitive restoration + follow-up” is this site's editorial definition, not an institutional staging definition.｜confidence=n/a｜basis=editorial｜geo: TW｜caveat: as above, do not mark pending verification.

Sources

1. Pak JG, White SN. Pain prevalence and severity before, during, and after root canal treatment: a systematic review. J Endod. 2011 Apr;37(4):429-38. PMID 21419285. https://pubmed.ncbi.nlm.nih.gov/21419285/ (accessed 2026-08-06; efetch abstract retrieved). Verbatim span: 「provided 72 studies for meta-analysis」 “Mean pretreatment, 24-hour posttreatment, and 1-week posttreatment pain prevalences with associated standard deviations were 81 (28%), 40 (24%), and 11 (14%), respectively” “Pretreatment, 24-hour posttreatment, and 1-week posttreatment pain severities, on a 100-point scale, were 54 (24%), 24 (12%), and 5 (5%), respectively” “Pretreatment root canal-associated pain prevalence was high but dropped moderately within 1 day and substantially to minimal levels in 7 days”
2. Mergoni G, Ganim M, Lodi G, Figini L, Gagliani M, Manfredi M. Single versus multiple visits for endodontic treatment of permanent teeth. Cochrane Database Syst Rev. 2022 Dec 13;12(12):CD005296. PMID 36512807. https://pubmed.ncbi.nlm.nih.gov/36512807/ (accessed 2026-08-06; esearch for CD005296 that day found only PMID 36512807／27905673／17943848, with the 2022 edition current). Verbatim span: 「Our primary outcomes were 1. tooth extraction and 2. radiological failure after at least one year (i.e. periapical radiolucency)」 “Our secondary outcomes were 3. postoperative and postobturation pain; 4. swelling or flare-up; 5. analgesic use and 6. presence of sinus track or fistula after at least one month” “We found no evidence of a difference in the proportion of participants reporting pain until 72 hours postobturation (RR 0.97, 95% CI 0.81 to 1.16; I2 = 70%; 12 studies, 1329 teeth; low-certainty evidence)” “pain at one week postobturation (RR 1.05, 95% CI 0.67 to 1.67; I2 = 61%; 9 studies, 1139 teeth; very low-certainty evidence)” “We found evidence of a higher proportion of participants reporting pain within one week in single-visit groups compared to multiple visit groups (RR 1.55, 95% CI 1.14 to 2.09; I2 = 18%; 5 studies, 638 teeth; moderate-certainty evidence)” “which was higher in the single-visit groups for vital teeth (RR 2.16, 95% CI 1.39 to 3.36; I2 = 0%; 2 studies, 316 teeth)” “We found no evidence of a difference in swelling or flare-up incidence (RR 0.56 95% CI 0.16 to 1.92; I2 = 0%; 6 studies; 605 teeth; very low-certainty evidence)” “analgesic use (RR 1.25 95% CI 0.75 to 2.09; I2 = 36%; 6 studies, 540 teeth; very low-certainty evidence)” “Neither regimen can prevent pain and other complications in the 12-month postoperative period”
3. Alí A, Olivieri JG, Duran-Sindreu F, Abella F, Roig M, García-Font M. Influence of preoperative pain intensity on postoperative pain after root canal treatment: A prospective clinical study. J Dent. 2016 Feb;45:39-42. PMID 26678517. https://pubmed.ncbi.nlm.nih.gov/26678517/ (accessed 2026-08-06). Verbatim span: 「Two hundred and seventy patients with pulpal pathology who were scheduled for routine endodontic treatment were enrolled in this study」 “Postoperative pain and the need for analgesic consumption were assessed at 4, 8, 16, 24, 48 and 72h post-treatment” “The mean level of pain after root canal treatment was 2.58±2.80 on a VAS between 0 and 10” “the presence of preoperative pain is the variable that most influences the prevalence of postoperative pain”
4. Signor B, Poli Kopper PM, Aspesi M, Münchow EA, Scarparo RK. Postoperative pain after single-visit root canal treatment or vital pulp therapy: A systematic review and meta-analysis. J Am Dent Assoc. 2024 Feb;155(2):118-137.e1. PMID 38325970. https://pubmed.ncbi.nlm.nih.gov/38325970/ (accessed 2026-08-06). Verbatim span: 「The qualitative synthesis included 57 studies, and the authors conducted meta-analysis of 3」 “Moderate to severe postoperative pain was more common at 48 hours through 72 hours after RCT and up to 36 hours after PULP” “The frequency of severe pain was very low for both vital pulp therapy and RCT”
5. Gupta R, Abraham D, Ahmad L, Puri A. Single-visit versus multiple-visit root canal therapy: Post-endodontic pain outcomes from an umbrella review. J Dent. 2026 Jun;169:106637. PMID 41856391. https://pubmed.ncbi.nlm.nih.gov/41856391/ (accessed 2026-08-06). Verbatim span: 「Twelve systematic reviews met the inclusion criteria」 “Post-operative pain was most commonly assessed as pain intensity using visual analogue or numeric rating scales at prespecified intervals, and less often as pain incidence” “Flare-up outcomes were reported inconsistently and were defined variably across reviews” “the higher-confidence reviews did not show a consistent or clinically important difference in post-operative pain between single-visit and multiple-visit treatment” “the choice of visit strategy can be guided by other factors such as case complexity, infection control, patient preference, and logistical considerations rather than the expectation of meaningful differences in post-operative pain”
6. Alves Vde O. Endodontic flare-ups: a prospective study. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2010 Nov;110(5):e68-72. PMID 20813556. https://pubmed.ncbi.nlm.nih.gov/20813556/ (accessed 2026-08-06). Verbatim span: 「the incidence of flare-ups (pain and/or swelling requiring endodontic interappointment and emergency treatment)」 “The incidence of flare-ups was 1.71% out of 408 teeth that had received endodontic therapy” “indicated a direct correlation between the flare-up rate and the presence of a periradicular radiolucency”
7. Sipavičiūtė E, Manelienė R. Pain and flare-up after endodontic treatment procedures. Stomatologija. 2014;16(1):25-30. PMID 24824057. https://pubmed.ncbi.nlm.nih.gov/24824057/ (accessed 2026-08-06). Verbatim span: 「Flare-ups can occur after root canal treatment and consist of acute exacerbations of an asymptomatic pulpal and/or periradicular pathologic condition」 “The causative factors of interappointment pain encompass mechanical, chemical, and/or microbial injury to the pulp or periradicular tissues” “The mechanical irritation of apical periodontal tissue is caused by overinstrumentation of the root canal and filling material extrusion through the apical foramen”
8. Chagas Carvalho Alves N, Raiane Mamede Veloso S, de Andrade Silva S, et al. Influence of occlusal reduction on pain after endodontic treatment: a systematic review and meta-analysis. Sci Rep. 2021 Jul 7;11(1):14019. PMID 34234168. https://pubmed.ncbi.nlm.nih.gov/34234168/ (accessed 2026-08-06). Verbatim span: 「Twelve studies were included for qualitative analysis and nine for quantitative analysis」 “The meta-analysis results did not reveal a significant difference in the reduction of postoperative pain levels for endodontic instrumentation at 6, 12, 24, 48 h and for endodontic obturation at 6 or 12 h after occlusal reduction” “the analyzed outcome was classified as having a moderate level of certainty”
9. Ahmad MZ, Sadaf D, Merdad KA, Almohaimeed A, Onakpoya IJ. Calcium hydroxide as an intracanal medication for postoperative pain during primary root canal therapy: A systematic review and meta-analysis with trial sequential analysis of randomised controlled trials. J Evid Based Dent Pract. 2022 Mar;22(1):101680. PMID 35219466. https://pubmed.ncbi.nlm.nih.gov/35219466/ (accessed 2026-08-06). Verbatim span: 「We included 18 studies with 1192 participants」 “We found a significant improvement in postoperative pain at 24 hours in favor of CH over no intracanal medication (4 trials, n = 226: standardised mean difference: -0.71; [95% confidence interval: -1.38, -0.03]; P = .04; I2= 78%; moderate certainty evidence)” “Substantial heterogeneity limits the robustness of findings”
10. Sabeti M, Kim H, Abbaker S, Karimpourtalebi N, Azarpazhooh A. Healing Outcomes of Single-Visit and Two-Visit Endodontic Treatment for Necrotic Teeth with Apical Periodontitis: A Randomized Clinical Trial. J Endod. 2026 Jul 29 (online ahead of print). PMID 42526597. https://pubmed.ncbi.nlm.nih.gov/42526597/ (accessed 2026-08-06). Verbatim span: 「Fifty-nine patients were randomized to single-visit (n= 28) or two-visit (n= 31) treatment, with calcium hydroxide placed for 10-14 days in the two-visit group」 “At a mean follow-up of 2.8 years, 42 patients completed the study” “these findings do not demonstrate superiority, noninferiority, or equivalence”
11. Pratt I, Aminoshariae A, Montagnese TA, Williams KA, Khalighinejad N, Mickel A. Eight-Year Retrospective Study of the Critical Time Lapse between Root Canal Completion and Crown Placement: Its Influence on the Survival of Endodontically Treated Teeth. J Endod. 2016 Nov;42(11):1598-1603. PMID 27625148. https://pubmed.ncbi.nlm.nih.gov/27625148/ (accessed 2026-08-06). Verbatim span: 「Teeth that received crown 4 months after RCT were almost 3 times more likely to get extracted compared with teeth that received crown within 4 months of RCT (hazard ratio, 3.38; confidence interval, 1.56-6.33; P = .002)」 “ETT that received composite/amalgam buildup restorations were 2.29 times more likely to be extracted compared with ETT that received crown (hazard ratio, 2.29; confidence interval, 1.29-4.06; P = .005)”
12. Olsson S, Pigg M, Gustavsson J, Ekblom E, Fransson H. Immediate or delayed direct restoration does not significantly influence additional endodontic treatments and 5-year tooth survival of first molars. Acta Odontol Scand. 2025 Oct 10;84:544-548. PMID 41071168. https://pubmed.ncbi.nlm.nih.gov/41071168/ (accessed 2026-08-06). Verbatim span: 「In vitro leakage studies suggest that temporary restorations only provide a short-term seal」 “In 2009, 50,314 direct restorations were registered after RCT of the first molars in individuals aged 20 years or older” “No statistically significant time-dependent differences in registrations were found for orthograde retreatment (p = 0.089), with or without apical surgery (p = 0.161) and with or without extraction (p = 0.737)” “The time elapsed from the completion of RCT and the placement of a direct restoration did not affect the 5-year outcome of the RCT”
13. Nixdorf DR, Moana-Filho EJ, Law AS, McGuire LA, Hodges JS, John MT. Frequency of persistent tooth pain after root canal therapy: a systematic review and meta-analysis. J Endod. 2010 Feb;36(2):224-30. PMID 20113779. https://pubmed.ncbi.nlm.nih.gov/20113779/ (accessed 2026-08-06). Verbatim span: 「Persistent tooth pain was defined as pain present > or = 6 months after endodontic treatment」 “A total of 5,777 teeth were enrolled, and 2,996 had follow-up information regarding pain status” “We identified 168 teeth with pain and derived a frequency of 5.3% (95% confidence interval, 3.5%-7.2%, p < 0.001) for persistent all-cause tooth pain” “In subgroup analysis, prospective studies had a higher pain frequency (7.6%) than retrospectives studies did (0.9%)”
14. Alotaibi N, Cloutier L, Khaldoun E, Bois E, Chirat M, Salvan D. Criteria for admission of odontogenic infections at high risk of deep neck space infection. Eur Ann Otorhinolaryngol Head Neck Dis. 2015 Nov;132(5):261-4. PMID 26347337. https://pubmed.ncbi.nlm.nih.gov/26347337/ (accessed 2026-08-06). Verbatim span: 「Nineteen patients (20%) presented with deep neck space infection」 “The frequency of deep neck space infection was significantly higher in patients with mandibular odontogenic infection (16/55 patients (29%) than in those with maxillary odontogenic infection (3/42 (7%); P ≤ 0.009)” “In addition to the well-known classical criteria (fever, neck swelling, dyspnoea, dysphagia, trismus, leukocytosis, elevated C reactive protein (CRP)), the criteria for admission for odontogenic infection should include mandibular odontogenic infection and/or the presence of dental abscess”
15. Taiwan Medical Care Act, Article 81. Official English translation: Laws & Regulations Database of the Republic of China (Taiwan) (verified live with ego-browser on 2026-08-06; article text matched; same anchor verified in VERIFIED-FACTS).
16. Taiwan Medical Care Act, Article 87. Official English translation: Laws & Regulations Database of the Republic of China (Taiwan) (verified live with ego-browser on 2026-08-06; both provisions retrieved verbatim).
17. Taiwan National Health Insurance Act, Article 41. Laws & Regulations Database of the Republic of China (Taiwan) (verified live with ego-browser on 2026-08-06; four provisions retrieved verbatim).
18. Supplementary verification record (not cited in body, only for evidence currency): Hegde VR, Jain A, Patekar SB. Comparative evaluation of calcium hydroxide and other intracanal medicaments on postoperative pain in patients undergoing endodontic treatment: A systematic review and meta-analysis. J Conserv Dent. 2023 Mar-Apr;26(2):134-142. PMID 37205901 (accessed 2026-08-06). Verbatim span: 「the cumulative mean difference was -4.57 (confidence interval: -16.25, 7.11)」 “The heterogeneity was significant I2 = 95%”
19. km dental topic ledger: appendix #29 of `analysis/reports/km-dental-backlog.md` (3 query terms itemised, total 114,830, across 2 sites); data source = reconciled full GSC data for 14 clinic assets.

Internal citation chain

• Related procedure card (essential): What is root-canal treatment? How many visits? (KM-DENTAL-18, draft). Canonical boundary: that card covers indications, procedure, full evidence and decision-making on single versus multiple visits, and how to read success and survival rates; this card covers postoperative-pain timing and measurement points, flare-up definition and care-routing levels, criteria for return and immediate care, and the four-part course timeline. Both share Cochrane CD005296 (current 2022 edition) and the 2026 umbrella review, with verbatim English spans identical.
• Related cost card: How much does root-canal treatment cost? Why is microscopic endodontics expensive? (KM-DENTAL-26, draft). This card's third-period “definitive restoration,” overall cost composition, and Taiwan National Health Insurance/self-pay verification route are there; this card repeats neither and gives no amount.
• Restoration extension: How much does a crown cost? (KM-DENTAL-11, draft). F16/F17 here concern the timing of restoration; that card addresses the crown's own component and material information.

Publication-gate reminder: this card is a draft. It must not enter km_entries before zh-Hans, en, and ja versions exist; because it includes red-flag criteria, the review-chain specification requires a GM third opinion for a high-risk card before final review.