Edward Lynch

Reversal of primary root caries using dentifrices containing 5,000 and 1,100 ppm fluoride.

This study compared the ability of two sodium fluoride dentifrices, one containing 5,000 ppm fluoride (Prevident 5000 Plus) and the other 1,100 ppm fluoride (Winterfresh Gel), to reverse primary root caries lesions (PRCLs). A total of 201 subjects with at least one PRCL each entered the study and were randomly allocated to use one of the dentifrices. After 6 months, 186 subjects were included in statistical analyses. At baseline and after 3 and 6 months, the lesions were clinically assessed and their electrical resistance measured using an electrical caries monitor. After 3 months, 39 (38.2%) of the 102 subjects in the 5,000 ppm F– group and 9 (10.7%) of 84 subjects using the 1,100 ppm F– dentifrice, had one or more PRCLs which had hardened (p = 0.005). Between baseline and 3 months, the log10 mean ± SD resistance values of lesions for subjects in the 1,100 ppm F– group had decreased by 0.06±0.55, whereas those in the 5,000 ppm F– group had increased by 0.40±0.64 (p<0.001). After 6 months, 58 (56.9%) of the subjects in the 5,000 ppm F– group and 24 (28.6%) in the 1,100 ppm F– group had one or more PRCLs that had become hard (p = 0.002). Between baseline and 6 months, the log10 mean ± SD resistance values of lesions for subjects in the 1,100 ppm F– group decreased by 0.004±0.70, whereas in the 5,000 ppm F– group, they increased by 0.56±0.76 (p<0.001). After 3 and 6 months, the distance from the apical border of the root caries lesions to the gingival margin increased significantly in the 5,000 ppm F– group when compared with the 1,100 ppm F– group. The plaque index in the 5,000 ppm F– group was also significantly reduced when compared with the 1,100 ppm F– group. The colour of the lesions remained unchanged. It was concluded that the dentifrice containing 5,000 ppm F– was significantly better at remineralising PRCLs than the one containing 1,100 ppm F–.

In vivo absorption, metabolism, and urinary excretion of alpha,beta-unsaturated aldehydes in experimental animals. Relevance to the development of cardiovascular diseases by the dietary ingestion of thermally stressed polyunsaturate-rich culinary oils.

Thermal stressing of polyunsaturated fatty acid (PUFA)- rich culinary oils according to routine frying or cooking practices generates high levels of cytotoxic aldehydic products (predominantly trans-2-alkenals, trans,trans-alka-2,4-dienals, cis,trans-alka-2, 4-dienals, and n-alkanals), species arising from the fragmentation of conjugated hydroperoxydiene precursors. In this investigation we demonstrate that typical trans-2-alkenal compounds known to be produced from the thermally induced autoxidation of PUFAs are readily absorbed from the gut into the systemic circulation in vivo, metabolized (primarily via the addition of glutathione across their electrophilic carbon-carbon double bonds), and excreted in the urine as C-3 mercapturate conjugates in rats. Since such aldehydic products are damaging to human health, the results obtained from our investigations indicate that the dietary ingestion of thermally, autoxidatively stressed PUFA-rich culinary oils promotes the induction, development, and progression of cardiovascular diseases.

Generation of lipid peroxidation products in culinary oils and fats during episodes of thermal stressing: a high field 1H NMR study.

The oxidative deterioration of glycerol‐bound polyunsaturated fatty acids (PUFAs) in culinary oils and fats during episodes of heating associated with normal usage (30–90 min at 180°C) has been monitored by high field 1H NMR spectroscopy. Thermal stressing of PUFA‐rich culinary oils generated high levels of n‐alkanals, trans‐2‐alkenals, alka‐2,4‐dienals and 4‐hydroxy‐trans‐2‐alkenals via decomposition of their conjugated hydroperoxydiene precursors, whereas only low concentrations of selected aldehydes were produced in oils with a low PUFA content, lard and dripping when subjected to the above heating episodes. Samples of repeatedly used, PUFA‐rich culinary oils obtained from restaurants also contained high levels of each class of aldehyde. The dietary, physiological and toxicological ramifications of the results obtained are discussed.

The use of ozone in dentistry and medicine.

There is growing interest in the use of ozone in oral healthcare and the National Institute for Clinical Excellence (NICE) is at present reviewing the evidence for its effectiveness in the management of occlusal and plain surface caries. These are only two of the clinical problems for which ozone can, and has, been used; it has also been employed for a wide variety of other purposes in both dentistry and medicine. This pale blue-coloured gas plays an important role as a natural constituent in the higher layer of the Earths atmosphere. There is growing evidence that it can be employed as a useful therapeutic agent. This paper reviews its therapeutic uses to date and suggests its possible future clinical applications. Consumer demands for this strong oxidant may increase as the general public becomes increasingly aware of its therapeutic capacity and the non-invasive manner in which it can be administered.

1H and 13C NMR Spectroscopic Analysis of Human Saliva

We have explored the ability of high-resolution NMR techniques to (1) index salivary biomolecules and (2) provide valuable data regarding intra- and inter-subject variability in the concentrations of a series of components readily determinable by this technique (organic acids and malodorous amines). Experiments were conducted on ‘whole’ saliva samples collected from 20 patients, either randomly during their daily activities, or, for investigations involving the quantification of salivary biomolecules, immediately after they woke in the morning throughout a three-day period. These NMR techniques permitted us to detect greater than 60 metabolites, together with agents arising from dietary, oral health care product, and pharmaceutical sources. Highly significant “between-subject” differences in the a.m. waking salivary metabolite concentrations were found for 9 out of 11 components monitored. It is concluded that NMR spectroscopy serves as a powerful technique for the multicomponent analysis of human saliva.

Detection of aldehydes and their conjugated hydroperoxydiene precursors in thermally-stressed culinary oils and fats: investigations using high resolution proton NMR spectroscopy.

High field (400 and 600 MHz) proton NMR spectroscopy has been employed to investigate the thermally-induced autoxidation of glycerol-bound polyunsaturated fatty acids present in intact culinary frying oils and fats. Heating of these materials at 180 degrees C for periods of 30, 60 and 90 min. generated a variety of peroxidation products, notably aldehydes (alkanals, trans-2-alkenals and alka-2,4-dienals) and their conjugated hydroperoxydiene precursors. Since such aldehydes appear to be absorbed into the systemic circulation from the gut in vivo, the toxicological significance of their production during standard frying practices is discussed.

Reversal of Primary Root Caries Using a Dentifrice with a High Fluoride Content

Root caries is a widespread problem and can be quite serious in older populations. The restoration of root carious lesions is often difficult. Compared to enamel caries, there has been limited research into the pharmaceutical management of primary root caries lesions (PRCLs), and many of these studies have been carried out in vitro, with limited numbers of clinical trials. Fluoride is presently a cornerstone in dentifrice formulations for cost-effective and anticaries therapy. It is generally accepted that fluoride ions promote remineralization of tooth substances and reduce the rate of demineralization. The use of a dentifrice with a high fluoride content may be considered to reverse PRCLs, since more fluoride is required for the remineralization of roots than for enamel. This paper reviews the effects of dentifrices with high fluoride contents on the management of root caries.

The use of ozone in dentistry and medicine. Part 2. Ozone and root caries.

A previous paper, recently published in Primary Dental Care, gave an overview of the medical uses of ozone and outlined some of its uses in dentistry. The current paper focuses on a description of use of ozone in the management of root caries and considers recent studies in this area. There has been relatively limited research into the non-invasive (pharmaceutical) management of root caries. The best management strategy still remains to be developed. Initial studies have indicated that an application of ozone for a period of either 10 or 20 seconds is capable of clinically reversing leathery root carious lesions. It is suggested that, subject to confirmation from extensive trials, this simple and non-invasive technique may benefit many patients with root caries throughout the world since this approach to treat root caries can easily be employed in primary care clinics and in the domiciliary treatment of home-bound elderly people and immobile patients in hospices and hospitals.

Multicomponent Spectroscopic Investigations of Salivary Antioxidant Consumption by an Oral Rinse Preparation Containing the Stable Free Radical Species Chlorine Dioxide (CIO2)

A multicomponent evaluation of the oxidative consumption of salivary biomolecules by a commercially-available oral rinse preparation containing an admixture of the stable free radical species chlorine dioxide (ClO2.) with chlorite anion (ClO2-) has been investigated using high resolution 1H NMR spectroscopy. The results obtained demonstrated that ClO2. and/or ClO2- present in this preparation effected the oxidative decarboxylation of salivary pyruvate (to acetate and CO2). Experiments conducted on chemical model systems confirmed the oxidative decarboxylation of pyruvate by this oral rinse, and also demonstrated that urate, thiocyanate anion, and the amino acids cysteine and methionine (precursors to volatile sulphur compounds responsible for oral malodour), were oxidatively consumed. The biochemical, periodontal and therapeutic significance of the results are discussed.

1H-NMR analysis of microbial-derived organic acids in primary root carious lesions and saliva

In addition to lowered pH values, the molecular profile and concentrations of microbial‐derived organic acids in carious dentin are important demineralization parameters involved in the induction, development and progression of dental caries. High‐resolution proton (1H) NMR spectroscopy was employed to examine the organic acid status of primary root carious lesions. 1H‐NMR analysis of post‐neutralized perchloric acid extracts of active carious lesions revealed that at an operating frequency of 600 MHz, the 1H‐NMR‐detectable organic acid composition of carious dentin samples (mean molecular percentage content ± standard error; the mean molecular percentage content is defined here as the mean of the concentration of each 1H‐NMR‐visible organic acid/anion expressed as a percentage of total 1H‐NMR‐detectable organic acid/anion level in each sample) was acetate 51 ± 2%, formate 37 ± 2%, lactate 5 ± 1%, propionate 3 ± 0.8%, pyruvate 2.4 ± 0.3%, n‐butyrate 1.2 ± 0.2%; succinate 0.1 ± 0.1%; iso‐butyrate, n‐ and iso‐valerate, and n‐ and iso‐caproate (total) <0.2%. Further components detectable included alanine, glycine, choline, phosphorylcholine, trimethylamine oxide, methanol, glycolate and assorted saccharides. In view of their high dissociation constants (Ka), our results demonstrate that formic and pyruvic acids (Ka = 1.77 × 10−4 and 3.20 × 10−3 mol/dm3, respectively) contribute substantially to the decreased pH values associated with active caries lesions (cf. lactate Ka = 1.40 × 10−4 mol/dm3), and hence the pathogenesis of primary root caries. Copyright