Decay Guide
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NHANES data put the average US adult aged 20–34 at 6.4 decayed, missing, or filled teeth (mean DMFT).

No CDC, NHANES, or NIDCR report isolates a cavity figure to age 30 — the closest data covers the full 20–34 band, plus four more bands through age 75 and up.

Written by Rosa Villanueva Rosa writes about everyday dental health: how decay and gum disease progress, and what daily care does and does not prevent.
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Cover art — illustrative, not a clinical photograph

No CDC, NHANES, or NIDCR publication reports a cavity count isolated to age 30. The closest official figure covers the 20–34 age band as a whole: NHANES 2017–March 2020 puts the mean DMFT (decayed, missing, or filled permanent teeth) for that band at 6.4, and an earlier 2011–2016 cycle found 82% of adults in that band have had a cavity at some point. Both figures climb steadily through the older age bands in the table below.

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By Age Band

DMFT = mean count of decayed, missing (due to decay), and filled permanent teeth per person, among dentate adults with at least one affected tooth (US 2000 standard population, age-adjusted in 5-year groups). “Total caries experience” = % of adults with DMFT≥1 (has had a cavity, treated or not, at any point). “Untreated caries prevalence” = % with ≥1 currently decayed, unfilled tooth. Two NHANES cycles run side by side: the current oral-health surveillance report (2017–March 2020) doesn’t publish a total-caries-experience table for adults, so that column is pinned to the older 2011–2016 cycle while DMFT/DT/MT/FT severity is pinned to 2017–March 2020. The 2011–2012 rows (CDC Data Brief 197) appear only for the total/untreated trend — that brief never published DMFT.

Age Group Population Total Caries Exp. % Cycle (Total %) Untreated Caries % Cycle (Untreated %) Mean DMFT Mean DT (Untreated) Mean MT (Missing) Mean FT (Filled) Cycle (DMFT)
20–34 dentate adults 20–64 82.0 NHANES 2011–2016 21.8 NHANES 2017–March 2020 6.4 0.8 0.7 4.8 NHANES 2017–March 2020
35–49 dentate adults 20–64 92.5 NHANES 2011–2016 21.4 NHANES 2017–March 2020 8.5 0.6 1.8 6.0 NHANES 2017–March 2020
50–64 dentate adults 20–64 96.4 NHANES 2011–2016 17.3 NHANES 2017–March 2020 11.8 0.4 3.8 7.5 NHANES 2017–March 2020
20–64 (overall) dentate adults 20–64 89.9 NHANES 2011–2016 20.5 NHANES 2017–March 2020 8.6 0.7 2.0 6.0 NHANES 2017–March 2020
20–64 (overall, older cycle) dentate adults 20–64 90.9 NHANES 2011–2012 27.0 NHANES 2011–2012 — — — — not reported in this data brief
65–74 dentate adults 65+ 96.4 NHANES 2011–2016 12.4 NHANES 2017–March 2020 14.8 0.2 5.6 9.0 NHANES 2017–March 2020
≥75 dentate adults 65+ 96.0 NHANES 2011–2016 12.6 NHANES 2017–March 2020 17.4 0.2 7.4 9.7 NHANES 2017–March 2020
65+ (overall) dentate adults 65+ 96.2 NHANES 2011–2016 12.5 NHANES 2017–March 2020 16.0 0.2 6.4 9.3 NHANES 2017–March 2020
65+ (overall, older cycle) dentate adults 65+ 96.2 NHANES 2011–2012 18.9 NHANES 2011–2012 — — — — not reported in this data brief

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Decayed, Missing, And Filled Teeth By Age

Mean count of each DMFT component per person. Five non-overlapping age bands only — “overall” and older-cycle rows excluded. NHANES 2017–March 2020. The highlighted 20–34 band contains age 30; components round independently and can sum to within 0.1 of the published mean DMFT total.

0 4 8 12 16 20 20–34: Decayed 0.8 mean teeth 20–34: Missing 0.7 mean teeth 20–34: Filled 4.8 mean teeth 6.4 20–34 35–49: Decayed 0.6 mean teeth 35–49: Missing 1.8 mean teeth 35–49: Filled 6.0 mean teeth 8.5 35–49 50–64: Decayed 0.4 mean teeth 50–64: Missing 3.8 mean teeth 50–64: Filled 7.5 mean teeth 11.8 50–64 65–74: Decayed 0.2 mean teeth 65–74: Missing 5.6 mean teeth 65–74: Filled 9.0 mean teeth 14.8 65–74 ≥75: Decayed 0.2 mean teeth ≥75: Missing 7.4 mean teeth ≥75: Filled 9.7 mean teeth 17.4 ≥75 Decayed Missing Filled

Sources

  1. NCHS Data Brief No. 197: Prevalence of Total and Untreated Dental Caries Among Adults: United States, 2011–2012
    CDC / National Center for Health Statistics · primary
    Direct fetch 403’d; content retrieved via reader proxy. Supplied total and untreated caries prevalence by age (20–34, 35–49, 50–64, 65–74, 75+, and overall) for NHANES 2011–2012. No DMFT scores in this brief.
  2. Dental Caries (Tooth Decay) in Adults (Age 20 to 64) | NIDCR
    National Institute of Dental and Craniofacial Research (NIH) · primary
    Fetched directly (200 OK). Supplied total caries experience % by age band for NHANES 2011–2016 and overall mean DMFT/DT/MT/FT for NHANES 2017–March 2020.
  3. Dental Caries (Tooth Decay) in Seniors (Age 65 and Over) | NIDCR
    National Institute of Dental and Craniofacial Research (NIH) · primary
    Fetched directly (200 OK). Supplied total caries % (2011–2016) and untreated %/DMFT (2017–March 2020) for ages 65–74 and ≥75.
  4. 2024 Oral Health Surveillance Report, Table 11 — Prevalence of untreated tooth decay among dentate adults aged 20–64
    CDC (Division of Oral Health) · primary
    Direct fetch 403’d; retrieved via reader proxy. Untreated caries prevalence by age band and overall, NHANES 2017–March 2020, with standard errors.
  5. 2024 Oral Health Surveillance Report, Table 12 — Mean DMFT/DT/MT/FT among dentate adults aged 20–64
    CDC (Division of Oral Health) · primary
    Direct fetch 403’d; retrieved via reader proxy. Mean DMFT and components by age band and overall, NHANES 2017–March 2020, with standard errors.
  6. 2024 Oral Health Surveillance Report, Table 13 — Prevalence of untreated tooth decay among dentate adults aged 65+
    CDC (Division of Oral Health) · primary
    Direct fetch 403’d; retrieved via reader proxy. Untreated caries prevalence for ages 65–74, ≥75, and overall, NHANES 2017–March 2020.
  7. 2024 Oral Health Surveillance Report, Table 14 — Mean DMFT/DT/MT/FT among dentate adults aged 65+
    CDC (Division of Oral Health) · primary
    Direct fetch 403’d; retrieved via reader proxy. Mean DMFT and components for ages 65–74 and ≥75, NHANES 2017–March 2020.
  8. 2024 Oral Health Surveillance Report: Tables (index)
    CDC (Division of Oral Health) · primary
    Direct fetch 403’d; retrieved via reader proxy. Used only to confirm exact table numbers/titles referenced above.

Method

Ran 8+ distinct web searches (NIDCR dental caries by age; CDC NCHS data brief mean DMFT adults; NHANES untreated caries prevalence by age group; mean DMFT NHANES 2017-2020 by age table; decayed missing filled teeth 20-34/35-49/50-64; CDC OHSR table 11; table list for the 2024 report; mean DMFT NHANES age group) before treating a single-year age-30 figure as nonexistent. Every cited number was fetched with WebFetch. cdc.gov PDF and 2024-oral-health-surveillance-report table pages returned HTTP 403 on direct fetch; each was retried through a reader proxy and the returned text used instead (noted per source above). NIDCR’s summary pages fetched without a proxy. No values were computed or interpolated — all figures are copied as published; dashes mark cells NHANES/CDC did not report for that cycle.

Gaps

We couldn’t find a DMFT or cavity-count figure isolated to the single age of 30 in any CDC/NCHS/NIDCR/NHANES publication — NHANES adult tables are only ever released in 15-year bands (20–34, 35–49, 50–64) for working-age adults and 10-year/open bands (65–74, ≥75) for seniors; age 30 sits inside the 20–34 band. The CDC’s current (2017–March 2020 cycle) Oral Health Surveillance Report also does not publish a “percent of adults 20–64 who have ever had a cavity” table at all — only untreated-decay prevalence and DMFT severity — so that specific “total caries experience” percentage in the table above necessarily comes from the older 2011–2016 cycle, not the same survey years as the DMFT figures. We did not find a peer-reviewed NHANES 2015–2018 or 2021–2023 analysis with a directly comparable by-age DMFT breakdown beyond what’s cited (several PMC articles referencing DMFT in that window came up in search but were not opened/verified, so they are omitted rather than cited secondhand).

How this guide is written

Decay Guide is written by a health writer, not by a dentist, and no article here has been reviewed by a clinician. We work from public patient-education sources — the NHS, the CDC, the American Dental Association and hospital patient guides — and link to them so you can check what we say. Figures such as pocket depths are quoted as the educational benchmarks those sources use, not as thresholds you can apply to yourself. Nothing here replaces an examination.