Continuous Monitoring of Salivary Flow Rate and pH at the Surface of the Dentition following Consumption of Acidic Beverages

Abstract

Use of a splint-mounted flexible pH electrode has allowed reliable continuous monitoring of pH at the surface of the dentition whilst still enabling subjects to drink normally. pH was monitored at the palatal upper left central incisor and upper right first permanent molar sites after drinking 1% (w/v) citric acid. A maximal decrease in pH to values of 2–3 was observed after 1 min followed by a slower recovery which was above pH 5.5 within 2 min at the former site and in 4–5 min at the latter site. A sharp rise in parotid saliva flow rate was seen at 1 min after drinking the same concentration of citric acid by glass, straw or feeder cup, which returned to resting levels within 6 min although the fall-off of flow rate was slower with the feeder cup. Thus, after dietary acid intake the pH at the surface of the dentition is below the critical pH for enamel dissolution for shorter periods than previously suggested, which is probably a reflection of salivary neutralisation and washing.

Tooth surface pH during drinking of black tea

“…The decreases in pH observed after drinking tea were minimal compared with those previously observed after drinking 1% citric acid (similar concentration to some fruit-based acidic drinks) where pHs as low as 2 were reached. 20 Not only were the pH decreases very small but also, they occurred very rapidly (maximal at 20 to 25 seconds) and resting pH levels were restored within approximately 2 minutes. Although there was a greater decrease in the incisor region compared with the molar region, this would not be clinically significant.…”

“…The influence of black tea on tooth surface pH was assessed using an in situ pH monitoring approach previously reported by our group. 20 Essentially, this involved the manufacture of vinyl splints from individual alginate impressions and plaster casts of the subjects' maxillary dentition. Short lengths of small-bore plastic tubing were mounted on the splints at two positions with cold cure acrylic to provide mounting points for a micro-pH electrode (0.6 mm diameter).…”

“…The pH changes in the presence of such acids have been previously reported. 20 All measurements were made at the same time of day (midday) to avoid diurnal variation and subjects refrained from drinking or eating for 3 hours prior to the experiment. Each subject was calibrated to the pH meter with two standard pH buffer Objectives To investigate the composition of black tea in terms of its erosive potential.…”

The effect of saliva substitutes on enamel erosion in vitro

“…The flow rate in the artificial mouth during erosion with citric acid was applied in order to mimic oral conditions during consumption of a beverage. 20 Since it was suggested that exposure to the acidic environment without salivary interaction should not exceed a period of 2 min/cycle, the specimens were subjected to 6 x 30 s of erosion daily. These in vitro conditions simulate intra-oral real-life conditions as closely as possible.…”

Mild dehydration: a risk factor for dental disease?

“…Associations between unstimulated salivary flow rate and buffering capacity with dental erosion have been reported (Hellström, 1977;Woltgens et al, 1985;Bevenius & l'Estrange, 1990;Järvinen et al, 1991;Gudmundsson et al, 1995), although such associations were not observed in patients with reflux disease (Meurman et al, 1994) or in a recent case-control study of children (Al-Dlaigan et al, 2002). Nevertheless, both salivary flow and buffering capacity appear to be important in neutralising dietary acid as demonstrated by the restoration of resting pH at the tooth surface within a few minutes of acid consumption (Millward et al, 1997). Considerable intersubject variation appears to exist in the ability to buffer acidic drinks, although intrasubject variation is less (McCay & Will, 1949).…”