Effect of post-brushing mouthrinse solutions on salivary fluoride retention

Fluoride (F) toothpaste is one of the most effective means of caries prevention. There is also evidence that mouthrinse solutions with antimicrobial agents reduce plaque formation and gingivitis and may be used as adjuncts to daily self-performed oral hygiene for risk patients. The authors hypothesize that using these solutions--without or with just a low F concentration after brushing--will have a "wash-out" effect on F toothpaste. Mouthrinse solutions with more F might be beneficial in this respect. Two groups of 10 (Series 1) and 12 (Series II) healthy subjects were recruited. They brushed for 1 min with toothpastes containing either 1450 or 5000 ppm F. After brushing and spitting out the toothpaste, the participants in Series I rinsed for 30 sec with 10 ml of a variety of products with various F concentrations (0, 100, 226 or 900 ppm F). In Series II, they first rinsed with water after the brushing and directly thereafter with 20 ml of the post-brushing rinsing solution for 30 sec. Saliva samples in both series were collected at different time points up to 1 h and the F concentration was measured. There was significantly less F in saliva after rinsing with no F or with a low F concentration (100 ppm) compared with just brushing with a F toothpaste. Rinsing with 226 ppm F displayed significantly higher F concentrations in saliva compared with only toothbrushing. Products with a high F concentration (i.e. toothpaste with 5000 ppm F or a mouthrinse solution with 900 ppm F) produced the highest F retention in saliva compared with all other protocols. The quantity of mouthrinse solution (20 vs. 10 ml) did not seem to have any effect on the F retention. The results from both test series show that a post-brushing rinsing solution without F or with just 100 ppm F exerts a "wash-out" effect on toothbrushing with either 1450 or 5000 ppm F, which may be negative for all patients, especially those with a risk of caries. The general population will benefit more from higher concentrations of F in mouthrinse solutions and, based on the results of the present investigation, 226 ppm F (corresponding to 0.05% NaF) should be the lowest concentration used. Furthermore, caries risk patients are recommended to use a high-F toothpaste (5000 ppm F) or a post-brushing mouthrinse solution with 900 ppm F (corresponding to 0.2% NaF).