BackgroundAs part of the Global Strategy on Oral health, the World Health Organization (WHO) is exploring cost-effective interventions for oral health, including taxation on sugar-sweetened beverages (SSBs). To inform this process, this umbrella review aimed to identify the best available estimates pertaining to the impact of SSB taxation on the reduction of sugars intake, and the sugars-caries dose–response, such that estimates of the impact of SSB taxation on averting dental caries in both high (HIC) and low and middle (LMIC) countries be available.MethodsThe questions addressed were: (1) what are the effects of SSB taxation on consumption of SSBs and (2) sugars? (3) What is the effect on caries of decreasing sugars? and (4) what is the likely impact of a 20% volumetric SSB tax on the number of active caries prevented over 10 years? Data sources included PubMed, Embase, Web of Science, Scopus, CINAHL, Dentistry and Oral Sciences Source, Cochrane Library, Joanna Briggs Institute (JBI) Systematic Review Register, and PROSPERO. The review was conducted with reference to JBI guidelines. The quality of included systematic reviews was assessed using AMSTAR to identify best evidence.ResultsFrom 419 systematic reviews identified for questions 1 & 2, and 103 for question 3, 48 (Questions 1 & 2) and 21 (Question 3) underwent full text screening, yielding 14 and five included reviews respectively. Best available data indicated a 10% tax would reduce SSB intake by 10.0% (95% CI: -5.0, 14.7%) in HIC and by 9% (range -6.0 to 12.0%) in LMIC, and that a 20% tax would reduce free sugars intake on average by 4.0 g/d in LMIC and 4.4 g/d in HIC. Based on best available dose response data, this could reduce the number of teeth with caries per adults (HIC and LMIC) by 0.03 and caries occurrence in children by 2.7% (LMIC) and 2.9% (HIC), over a 10-year period.ConclusionBest available data suggest a 20% volumetric SSB tax would have a modest impact on prevalence and severity of dental caries in both HIC and LMIC.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12889-023-15884-5.