The English are often mocked for their terrible teeth. Why are their teeth so bad? What is the history of dental hygiene in England?

A clarification more than an answer: the question is probably based on a myth (but I'll have to break the 20 year rule to cite the evidence): Austin Powers bites back: a cross sectional comparison of US and English national oral health surveys. Link is not paywalled (but the abstract and a bit of the introduction are pasted below for pdf avoiding convenience).

That's not to say the (probable?) myth is not interesting from a historical point of view (nor that the quoted study is the last word on the question). The paper includes some discussion of possible causal mechanisms, for both the myth and the reality, but it's written by medics not historians.

Abstract

Objective To compare oral health in the US and England and to assess levels of educational and income related oral health inequalities between both countries.

Design Cross sectional analysis of US and English national surveys. Setting Non-institutionalised adults living in their own homes. Participants Oral health measures and socioeconomic indicators were assessed in nationally representative samples: the Adult Dental Health Survey 2009 for England, and the US National Health and Nutrition Examination Survey 2005-08. Adults aged ≥25 years were included in analyses with samples of 8719 (England) and 9786 (US) for analyses by education, and 7184 (England) and 9094 (US) for analyses by income.

Main outcome measures Number of missing teeth, self rated oral health, and oral impacts on daily life were outcomes. Educational attainment and household income were used as socioeconomic indicators. Age standardised estimates of oral health were compared between countries and across educational and income groups. Regression models were fitted, and relative and absolute inequalities were measured using the relative index of inequality (RII) and the slope index of inequality (SII).

Results The mean number of missing teeth was significantly higher in the US (7.31 (standard error 0.15)) than in England (6.97 (0.09)), while oral impacts were higher in England. There was evidence of significant social gradients in oral health in both countries, although differences in oral health by socioeconomic position varied according to the oral health measure used. Consistently higher RII and SII values were found in the US than in England, particularly for self rated oral health. RII estimates for self rated oral health by education were 3.67 (95% confidence interval 3.23 to 4.17) in the US and 1.83 (1.59 to 2.11) in England. In turn, SII values were 42.55 (38.14 to 46.96) in the US and 18.43 (14.01 to 22.85) in England.

Conclusions The oral health of US citizens is not better than the English, and there are consistently wider educational and income oral health inequalities in the US compared with England

Introduction

There is a longstanding belief in the United States that the British have terrible teeth, much worse than US citizens. This view dates back at least 100 years, with toothpaste adverts extolling the virtues of American smiles.1 Contemporary examples of this belief in popular US culture range from The Simpsons2 to the Hollywood character Austin Powers and his repugnant smile.3 The perceived terrible state of British teeth is also perpetuated in contemporary literature. For example, Everett, the annoying and dull English love rival in Donna Tartt’s Pulitzer Prize winning novel The Goldfinch, is disparagingly noted for his “rabbit teeth.”4

Few studies have directly compared the oral health of US and UK populations. Two descriptive studies have indicated that US adults had better oral health than their British counterparts.5 6 However, these studies did not statistically assess these differences.