evidence/gaps
5,343 systematic reviews · 53 fields of medicine

One in five review questions has no studies to answer it.

Every question a systematic review asks, with its population, intervention, comparison, outcome, effect and GRADE certainty. Find what medicine knows, what it knows poorly, and where reviews found no studies at all.

Limit to evidence status or GRADE (optional)
Try:silver diamine fluoridepreterm birthantidepressants in adolescentsno studies · oral health
Systematic reviews
5,343
4,913 Cochrane SoF · 430 full text
Review questions
75,239
current versions only
No studies
15,213
20.2% of questions: total gaps
Very low certainty
17,528
23.3% of questions

Certainty across all current questions

display order only, not a score
No studies 20.2%Ungraded 13.7%Very low 23.3%Low 23.9%Moderate 14.9%High 4%

Ungraded means an effect was reported without a GRADE rating; it is not a gap. No studies means the review found nothing to answer the question. The six categories are a display order, not a score.

Fields of medicine

Where each field stands

All 53 fields
Oral Health430 reviews
10,375 questionsNo studies 13% · High 0.7%
Pregnancy and Childbirth252 reviews
3,601 questionsNo studies 20.2% · High 4.1%
Airways216 reviews
2,325 questionsNo studies 10.7% · High 9.6%
Neonatal210 reviews
2,353 questionsNo studies 18.4% · High 3.9%
Gynaecology and Fertility194 reviews
2,653 questionsNo studies 20% · High 0.9%
Gut172 reviews
2,395 questionsNo studies 17.5% · High 4%
Eyes and Vision171 reviews
2,112 questionsNo studies 27.8% · High 3.1%
Schizophrenia168 reviews
2,589 questionsNo studies 23.2% · High 1.6%
Pain, Palliative and Supportive Care147 reviews
1,751 questionsNo studies 20.6% · High 4.5%
Musculoskeletal143 reviews
1,956 questionsNo studies 28.4% · High 6.5%
Heart140 reviews
1,554 questionsNo studies 17.5% · High 8.1%
Kidney and Transplant139 reviews
2,434 questionsNo studies 20.7% · High 3.1%
Deep map · Oral Health

Dental caries, down to the trials

Cochrane and non-Cochrane reviews extracted from full text. The non-Cochrane reviews also list every included primary study, AMSTAR 2 appraisal and their overlap, so shared trials are not counted twice.

264
reviews
5,762
questions
5,083
primary studies
Open the caries gap map Browse trials
Reviews per cell · color = highest certainty available · hatched = no review identified
Intervention or exposureCaries incrementAdverse effectsLesion arrestDiagnostic accuracy
Fluoride varnish945 questions69 questions537 questionsno review identified
Fluoride toothpaste878 questions831 questions14 questions15 questions
Glass ionomer / ART212 questions57 questions11 questions515 questions
Laser / photodynamicno review identified1015 questions36 questions591 questions
Diet / sugar519 questions413 questionsno review identifiedno review identified
Gap finder

Questions with the thinnest evidence

See all of them
QuestionEffectEvidenceStatus / GRADE
Partial pulpotomy vs Full (complete) pulpotomy
Patient- and clinical-reported outcomes (tooth survival, clinical/radiographic success, pain) · Asymptomatic permanent teeth with deep caries (no symptoms)
The effectiveness of partial pulpotomy compared with full pulpotomy in managing deep caries in vital… (2025)		no estimate extracted0 studiesNo studies
Calcium vs Control
Immediate (24 h) resin-dentin bond strength (MPa) · permanent human teeth with artificial caries-affected dentin · 24 h, Etch-and-Rinse; chemical ACAD
Biomimetic Remineralization Strategies for Dentin Bond Stability-Systematic Review and Network Meta-Analysis. (2025)		MD -0.508 [-8.207, 7.191]3 studiesVery low
Children with dental caries vs Children without dental caries (caries-free)
Mean corpuscular volume (MCV) · Children and adolescents (0-18 years; most included reviews focused on <6 years)
Association Between Iron Deficiency Anemia and Dental Caries in Children: A Systematic Umbrella Meta-Analysis. (2025)		MD -1.96 [-4.02, 0.10]3 studiesVery low
HIV infection with antiretroviral therapy (ART/HAART) vs HIV-negative individuals
Dental caries (presence/absence) · Children and adolescents under 18 years with HIV · Not specified (cross-sectional), Cross-sectional studies
Association between antiretroviral therapy and dental caries in children and adolescents with HIV: a… (2025)		OR 2.04 [1.21, 3.42]6 studies · 2206 participantsVery low
HIV infection with antiretroviral therapy (ART/HAART) vs HIV-negative individuals
Dental caries severity (dmft index, primary dentition) · Children and adolescents under 18 years with HIV · Not specified (cross-sectional), Cross-sectional studies; dmft index
Association between antiretroviral therapy and dental caries in children and adolescents with HIV: a… (2025)		MD 0.92 [-0.09, 1.93]5 studies · 1502 participantsVery low
Cavity liner (calcium hydroxide, glass-ionomer cement, resin-modified calcium silicate/TheraCal LC, hydraulic calcium silicate/MTA or Biodentine, flowable composite, or other liner material) vs No cavity liner or a different liner material
Treatment failure · Patients with deep caries lesions in mature or immature permanent (posterior) teeth, with no symptoms or reversible… · >=12 months
Efficacy of different cavity liners compared to no cavity lining in managing deep caries in vital permanent… (2025)		No significant difference; 96.5% of treated teeth remained vital12 studies · 1184 participantsVery low
Cavity liner (calcium hydroxide, glass-ionomer cement, resin-modified calcium silicate/TheraCal LC, hydraulic calcium silicate/MTA or Biodentine, flowable composite, or other liner material) vs No cavity liner or a different liner material
Postoperative hypersensitivity · Patients with deep caries lesions in mature or immature permanent (posterior) teeth, with no symptoms or reversible… · 7 days to 3 months
Efficacy of different cavity liners compared to no cavity lining in managing deep caries in vital permanent… (2025)		No significant difference; minimal pain reported9 studies · 1000 participantsVery low
Secondary (passive/secondhand) smoking exposure during childhood vs No secondary smoking exposure
Caries prevalence (early childhood caries) · Preschool children aged <=71 months (caries outcome assessed at 3-6 years) · Caries prevalence at 3-6 years, Overall
Secondary Smoking and Early Childhood Caries: A Systematic Review and Meta-Analysis. (2025)		OR 1.77 [1.57, 2.01]11 studies · 14,794 participantsVery low