Maximum Decrease In pH Research Articles

Effect of glucose polymers in water, milk and a milk substitute on plaque pH in vitro

Glucose polymers are widely used as an energy supplement in dietetic practice and are increasingly being used in commercially available products, such as some infant formulae and dried baby foods. Information on the effect of glucose polymers on dental health does not exist, yet is essential in order to advise how these carbohydrates should be incorporated into the diet with least risk to dental health. This study aimed to investigate whether glucose polymers taken as 10% solutions in water, in cow's milk, or in a solution of a milk substitute (Calogen) are acidogenic and, if so, whether these solutions decrease plaque pH to levels associated with enamel demineralization. The solutions alone and with 10% sucrose served as negative and positive controls, respectively. Plaque was collected from the teeth of 14 adult subjects before and at 3, 7, 11, 15, 23 and 27 minutes after rinsing the mouth with one of the solutions. pH curves were compiled and acidogenicity expressed as: pH area, minimum pH reached, maximum pH decrease and length of time below pH 6.0. Glucose polymers caused a decrease in plaque pH but, for some of the measures of acidogenicity, to a significantly lesser extent than sucrose. Glucose polymers showed equal acidogenicity when given in water, milk or Calogen. In view of their potential cariogenicity, advice for mode of consumption of glucose polymers and products containing glucose polymers should be the same as that for non-milk extrinsic sugars.

PH Measurements of Human Dental Plaque after Consumption of Starchy Foods Using the Microtouch and the Sampling Method

The aim was to study the effect of different starch-containing food items on pH changes in dental plaque. The pH was, in 10 subjects, simultaneously measured at various occasions up to 60 min in: (1) two approximal spaces in the premolar-molar region with the microtouch method, and (2) pooled samples of dental plaque with the sampling method. Six starchy products were tested: (1) spaghetti, (2) macaroni, (3) potato, (4) rice, (5) unsweetened bread, and (6) sweetened bread. A glucose chewing tablet and a mouthrinse with 10% sucrose served as controls. Saliva was collected for HPLC analysis of maltose and maltotriose when testing the spaghetti, rice and unsweetened bread. The glucose tablet and the sucrose solution resulted in the greatest pH drops. However, all starchy products resulted in obvious pH falls, which were most pronounced for sweetened bread, followed, in order, by unsweetened bread and potato. Significantly more maltose and maltotriose were found in saliva after consumption of unsweetened bread compared to spaghetti. There seemed to be a relationship between the amount of starch hydrolysates in saliva and the area of the plaque pH curve (AUC). The microtouch method gave consistently lower pH values than the sampling method. Both methods, however, ranked the eight test products roughly in the same order with respect to minimum pH, maximum pH decrease and AUC.

Salivary clearance of sugar and its effects on pH changes by Streptococcus mitior in an artificial mouth.

We recently developed a computer model of oral sugar clearance (Dawes, 1983), and an artificial mouth has now been constructed which will allow variation in the salivary parameters identified in the model and the study of their effects on bacterial acid production. Using a thin layer of S. mitior, strain 572, over a miniature Sb electrode to measure bacterial pH changes during sugar clearance from the "mouth", we found that three consecutive sets of "Stephan curves" could be obtained with the same bacteria during one day. In each of several experimental series, one salivary parameter was varied, while other parameters were held constant. The maximum pH decrease and the surface area of the registered Stephan curve (delta pH.min) were used as measures of acid production. The results indicate that the volume of "saliva" in the mouth before and after swallowing, the unstimulated salivary flow rate, and the buffer capacity had significant influences on the extent of the pH changes. Other factors, such as the maximum flow rate, the delay between start of stimulation and maximum flow, the volume of saliva in the mouth at time zero, and the taste threshold for sugar, were of lesser importance, confirming some predictions from the computer model.

Changes in the interstitial pH of dog myocardium in response to local ischemia, hypoxia, hyper- and hypocapnia, measured continuously by means of glass microelectrodes.

In open-chest dogs the pH changes of the myocardial interstitium were measured during local ischemia, hypoxia, hyper- and hypocapnia. Microglasselectrodes (Corning 0150) were inserted into the wall of the left ventricle. Simultaneously we recorded the local myocardial blood flow, the arterial blood pressure, the heart rate and the expiratory CO2 concentration. Local ischemia was produced by transient occlusion of the left descending coronary artery. In the ischemic region a decrease in pH occurred after 15–30 sec, the magnitude of which depended on the occlusion time, and on the extent of the ischemic region. When the occlusion time was short, the maximum decrease in pH was found after the release of blood flow. Mean values varied from about 0.1 pH (1 min occlusion) to 0.65 pH (30 min occlusion). After fibrillation the pH fell by 1.2 units (mean value) below the initial level. Hypoxia (10% for 5–13 min) was accompanied by an increase in pH by 0.05–0.1 units. After 2–3 min the pH reached a steady state or decreased again. After ventilation with sufficient O2 concentration an acidotic overshoot occurred (0.03-0.1 pH). When shifts in the interstitial pH similar to those during ischemia and hypoxia were produced by varying the arterialpCO2, no comparable changes in local blood flow and in the other parameters could be observed.