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What is Sugar restricted to diet was beneficial in presence of unfavorable hygiene was from which study? and explain in detail?
HOPEWOOD HOUSE STUDY 
(Sullivan and Harris- 1958, Harris- 1963 ) 
The dental status Of children between 7 to 14 years of age residing at Hopewood House, Bowral New South Wales, was studied longitudinally for 10 years. Almost all these children had lived from early infancy at Hopewood House. 
All lived on a strictly natural diet, that, with the exception of on occasional serving of egg yolk, was entirely vegetable in nature and largely raw. The absence of meat and restriction of refined carbohydrate were the principal features of the Hopewood House diet. 
The meals were supplemented by vitamin concentrates and an occasional serving of nuts and a sweetening agent such as honey. The fluoride content of water and food was insignificant and no tea was consumed. 
TURKU SUGAR STUDY 
(Scheinin and Makinen in 975) 
The study was carried outin Turku, Finland. 
Aim Of the study 
To compare the cariogenicity of sucrose, fructose and Xylitol. 
Basis of the study 
XylitoI is a sweet substance not metabolized by plaque micro organisms.
Key Concept:
In Hopewood house study : the children's oral hygiene was poor, calculus is uncommon,  but  gingivitis  was  prevalent  in 75%  of  children. This work  showed  that,  in institutionalized  children  at  least,  dental caries  can  be  reduced  by  a  spartan  diet, without the beneficial effects of fluoride  and in the presence of unfavorable oral hygiene.
Ref: Soben Peter , 4th ed page no 96