Dr Trevor H. Grenby CChem FRSC obituary

It was during his subsequent appointment in 1961 as a research biochemist with the Association of British Flour Millers' Cereals Research Station, then located in St Albans, Hertfordshire, that he embarked on what became his lifetime's work:  the effect of various foodstuffs on dental health, particularly in regard to dental caries.

He stayed at the CRS for five years, researching the effects on teeth of consuming various breads, flour, cakes and biscuits.  In 1966, shortly after he had married and built a home in St Albans, he was offered the post of Assistant Lecturer in the Department of Oral Medicine at Guy's Hospital Dental School, where he remained for the duration of his career, pausing only to spend a period in the late 1960's as a Senior Foreign Research Fellow at the Eastman Dental Center in Rochester, NY.
 
Over the next 35 years, he devoted himself to his research into the effects of various foodstuffs on dental health, particularly in regard to caries (dental decay), progressing up the ranks to Senior Lecturer and ultimately becoming Reader in Nutrition in Relation to Dentistry at the GKT (Guy's, King's and St Thomas's) Dental Institute. 

The highlights of his dental studies included in-vitro studies on oral bacteria and in-vivo studies on laboratory animals and human volunteers.  He developed a method in demineralisation experiments conducted on hydroxyapatite, the basic component of dental enamel, by determining calcium dissolving by atomic absorption spectroscopy and phosphate concentration by UV visual spectrophotometry.   Titration of the acid content, he found, was superior over pH measurement in determining the potential dental erosiveness of the formed acids. To determine the caries score in rat molar teeth, by assessing corrosive changes on the tooth surface, he developed a digital imaging analysis (DIA). He used enamel or hydroxyapatite demineralization tests to study potential protective action of minor milk protein or protein-associated components in milk against acid attack; removal of lactose from milk had little protective effect. In another related study, he found that the mean caries score in plain chocolate was 30% higher than in a milk chocolate regime. In a food (rusks) cariogenicity study with varying concentrations of sucrose a) in rats, b) during acid production by oral microorganisms, and c) adhesion to enamel surface, he found that the cariogenicity of sucrose in the food ranged from high (31% sucrose) to low (0% sucrose). He also studied the cariogenicity of lactitol as a bulk sweetener to replace dietary sugar.   Results showed that acidogenic and polysaccharide-forming oral bacteria did not easily metabolize lactitol; the enamel-demineralizing potential in-vitro, intra-oral acid production and dental plaque formation from lactitol in human volunteers were substantially lower than from sucrose. These results were also confirmed in an in-vivo study using caries-active Osborne-Mendel rats. Lactitol produced 60% fewer caries lesions than the sugar regimen. The sugar alcohols sorbitol and mannitol did not work as well as lactitol or xylitol as compared to sucrose. In rat experiments, there was no confirmation of an active caries-reversing effect of xylitol when xylitol-containing diets were alternated with the basic high-sucrose cariogenic ration.

With a particular interest in the dental aspects of the use of artificial sweeteners, he soon became one of the world's foremost experts on the topic. Consulted by the leading international manufacturers of confectionery, soft drinks, infants' drinks, snack foods, and the like, he was labelled in a "Daily Mail" report on the results of his research as "one of the world's top tooth experts".     Trevor studied ways in which potentially erosive products, like soft drinks, might be modified by supplementing various levels of calcium, phosphate and calcium citrate malate; applications of fluoride, bicarbonates and certain constituents of milk products were also included. The potential dental effects of new types of sugar-free sweets formulated with lycasin or isomalt as bulk sweeteners instead of sugars were also evaluated, leading to an improvement of their potential dental effects. Furthermore, he also studied the efficacy of mouthwashes as compared to toothpaste to control oral bacteria formulated with chlorhexidine, fluoride and sanguinarine, the latter being a natural therapeutic product, affecting somewhat even subgingival plaque.        

During his career, he published some 90 scientific papers, as well as presenting his work to a great number of national and international scientific and bio-medical societies.   Apart from papers,  during the 1980's and 90's he edited a series of books which have remained among the definitive volumes on the subject:   'Developments in Sweeteners', Vols II and III, 'Progress in Sweeteners' and 'Advances in Sweeteners', which was reprinted in 2011.   
Trevor was a Fellow of the Royal Society of Chemistry and a member of the Biochemical Society,  the Society of Chemical Industry, the Nutrition Society, the International Association for Dental Research, the European Organisation for Caries Research, and the Bone and Tooth Society, among others. From 1988-1990, he was chairman of the Food Chemistry Group of the Royal Society of Chemistry.
His many qualities, appreciated by a wide circle of friends and colleagues across the globe, included wit, good humour, uprightness, equability, courtesy, and consideration for others. As a scientist, 

he gave generously of his time to advise students or younger colleagues, and he was always fair in peer review.  He is survived by his wife, Jeanette, his two sons, Matthew and Edmund, and four grandsons, the latest born just four days after he passed away.

Dr. Harald A.B. Linke, Professor Emeritus, New York University Dental Center

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