Mary Lynn Bosma

The effect of brushing time and dentifrice quantity on fluoride delivery in vivo and enamel surface microhardness in situ

While the clinical anticaries efficacy of fluoride toothpaste is now without question, our understanding of the relation of fluoride efficacy to brushing time and dentifrice quantity is limited. The aim of this in situ study was to determine how differences in brushing time and dentifrice quantity influence (i) fluoride distribution immediately after brushing, (ii) clearance of fluoride in saliva, (iii) enamel fluoride uptake (EFU) and (iv) enamel strengthening, via the increase in surface microhardness. The study compared brushing times of 30, 45, 60, 120 and 180 s with 1.5 g of dentifrice containing 1,100 µg/g fluoride as sodium fluoride. In addition, 60 s of brushing with 0.5 g dentifrice was evaluated. A longer brushing time progressively reduced retention of dentifrice in the brush, thereby increasing the amount delivered into the mouth. A longer brushing time also increased fluoride concentrations in saliva for at least 2 h after the conclusion of brushing, showing that increased contact time promoted fluoride retention in the oral cavity. There was a statistically significant positive linear relationship between brushing time and both enamel strengthening and EFU. Compared to 0.5 g dentifrice, brushing with 1.5 g dentifrice more than doubled the fluoride recovered in saliva after brushing and increased EFU. In conclusion, the results of this preliminary, short-term usage study suggest for the first time that both brushing time and dentifrice quantity may be important determinants both of fluoride retention in the oral cavity and consequent enamel remineralization.

The effect of dentifrice quantity and toothbrushing behaviour on oral delivery and retention of fluoride in vivo

While toothpaste F(-) concentration and rinsing regimen have well-characterised impacts on fluorides effectiveness, other aspects of brushing regimen have much less well-established effects, in particular, dentifrice quantity and brushing duration. An in vivo study (n = 42) of oral fluoride delivery (i.e. oral disposition post-brushing), and retention (i.e. concentration of F(-) in saliva post-brushing, a known efficacy predictor), was performed to compare effects observed with those of dentifrice F(-) concentration and rinsing regimen. Subjects brushed with a NaF-silica dentifrice (Aquafresh Advanced, 1,150 ppm F(-) ) or a control dentifrice (250 ppm F(-) , same base), for 45, 60, 120 or 180 seconds with 0.5 or 1.5 g dentifrice, and rinsed with 15 ml water once or three times in a cross-over design. The F(-) concentration was measured in post-brushing expectorate, rinse and toothbrush washing samples, and in saliva between 5-120 minutes after brushing. Using 1.5 g versus 0.5 g dentifrice increased F(-) in all samples: oral retention of F(-) was almost doubled by this increase. Increasing duration of brushing had more complex effects. The amount of F(-) in the expectorate increased but decreased in both rinse and toothbrush washing samples. Oral F(-) retention increased, but only in the period 30-120 minutes after brushing. Over the ranges investigated, the order of importance on oral F(-) retention was: dentifrice F(-) concentration > quantity > rinsing regimen > brushing duration. Hence, increasing dentifrice quantity and, to a lesser extent, the duration of brushing, can elevate oral fluoride post-brushing. Evidence is accumulating that the importance of these variables to fluoride efficacy may have been underestimated.

A randomised clinical trial to assess maintenance of gingival health by a novel dentifrice containing 0.1%w/w o‐cymen‐5‐ol and 0.6%w/w zinc chloride

OBJECTIVES To assess the ability of 0.1%w/w o-cymen-5-ol/ 0.6%w/w zinc chloride dentifrice to maintain gingival health compared to a sodium fluoride control dentifrice. DESIGN Following a baseline examination, subjects went through a regimen to bring them to a high level of gingival health. This included a professional prophylaxis supported by oral hygiene instruction prior to commencing study treatment. Subjects brushed twice daily for 12 weeks with either the test or control dentifrice. Examinations for gingival inflammation (MGI), bleeding and plaque were performed after 6 and 12 weeks. RESULTS 224 subjects were included in the efficacy analysis. Relative to the sodium fluoride/ silica control dentifrice group the o-cymen-5-ol/ zinc chloride dentifrice exhibited statistically significant reductions (p<0.0001) in MGI, bleeding and plaque of 12.3%, 18.5% and 13.2% respectively after six weeks and 38.1%, 37.8% and 24.2% after 12 weeks. CONCLUSION The results of the present clinical study demonstrate that the use of the 0.1%w/w o-cymen-5-ol/ 0.6%w/w zinc chloride dentifrice over a 12 week period provides a statistically significant benefit in maintaining gingival health compared to a sodium fluoride control dentifrice.

Dose–response effect of fluoride dentifrice on remineralisation and further demineralisation of erosive lesions: A randomised in situ clinical study

OBJECTIVE The objective was to evaluate the ability of fluoride in a conventional, non-specialised sodium fluoride-silica dentifrice to promote tooth remineralisation and enamel fluoride uptake (EFU), and assess the resistance of the newly formed mineral to attack by dietary acid, across the concentration range used in mass-market dentifrices. METHODS Subjects wore a palatal appliance containing eight polished bovine enamel specimens, each including an early erosive lesion. In a randomised full-crossover sequence, 62 healthy subjects were treated with dentifrices containing four different fluoride concentrations: no fluoride; 250ppm, 1150ppm and 1426ppm fluoride. At each treatment visit, under supervision, subjects brushed with 1.5g dentifrice and rinsed once while wearing the appliance; the appliance was removed after a 4-h remineralisation period and effects on the enamel specimens determined. The primary efficacy variable was surface microhardness recovery (SMHR); others included EFU, relative erosion resistance (RER) and comparative erosion resistance. RESULTS Highly significant linear and, with the exception of SMHR, quadratic dose-response relationships were observed between all efficacy variables and fluoride concentration. For SMHR, EFU and RER, values for the different fluoride concentrations were statistically resolved from one another, with the exception of the two highest fluoride concentrations. The degree of remineralisation and the acid resistance of enamel after treatment were closely related to EFU. CONCLUSION After a single brushing, conventional non-specialised sodium fluoride-silica dentifrices promoted remineralisation of early enamel lesions, and imparted increased acid-resistance to the enamel surface, in a dose-dependent manner at least up to 1500ppm fluoride. CLINICAL SIGNIFICANCE Enamel erosive tissue loss is an increasing concern, associated with modern diets. This study demonstrated that sodium fluoride, in a conventional non-specialised dentifrice formulation, can promote repair of the earliest stages of enamel erosion after a single application, in a dose-dependent fashion across the fluoride concentration range used in mass-market dentifrices. This study is registered in the GlaxoSmithKline Study Register (ID RH01299), available at: www.gsk-clinicalstudyregister.com/study/RH01299.

A randomised clinical trial to assess maintenance of gingival health by a novel gel to foam dentifrice containing 0.1%w⁄w o-cymen-5-ol, 0.6%w⁄w zinc chloride

OBJECTIVES To assess the ability of 0.1%w/w o-cymen-5-ol/ 0.6%w/w zinc chloride gel to foam dentifrice to maintain gingival health compared to a sodium fluoride control dentifrice. DESIGN Following a baseline examination, subjects went through a regimen to bring them to a high level of gingival health. This involved a professional dental prophylaxis supported by oral hygiene instruction prior to commencing study treatment. Subjects brushed twice daily for 12 weeks with either the test or control dentifrice. Examinations for gingival inflammation (MGI), bleeding and plaque were performed after 12 weeks. RESULTS 205 subjects were included in the efficacy analysis. Relative to the sodium fluoride/ silica control dentifrice group the o-cymen-5-ol/ zinc chloride gel to foam dentifrice exhibited statistically significant reductions (p<0.0001) in MGI, bleeding and plaque of 32.2%, 26.3% and 20.7% respectively after 12 weeks. CONCLUSION The results of the present clinical study demonstrate that the use of the 0.1%w/w o-cymen-5-ol/ 0.6%w/w zinc chloride gel to foam dentifrice over a 12 week period provides a statistically significant benefit in maintaining gingival health compared to a sodium fluoride control dentifrice.

A randomised clinical trial to assess control of oral malodour by a novel dentifrice containing 0.1%w/w o-cymen-5-ol, 0.6%w/w zinc chloride

OBJECTIVES To assess the ability of a 0.1% w/w o-cymen-5-ol/ 0.6% w/w zinc chloride/ sodium fluoride dentifrice to control oral malodour compared to a sodium fluoride control dentifrice. DESIGN Following baseline measurement of oral volatile sulfur compounds (VSCs), the subjects brushed twice daily for 1 week with either the test or control dentifrice. The VSC concentration in breath samples was monitored up to 12 hours post-treatment, by gas chromatography (GC). RESULTS 75 subjects were included in the efficacy analysis. Relative to the sodium fluoride control dentifrice group the o-cymen-5-ol/ zinc chloride/ sodium fluoride dentifrice exhibited statistically significant reductions (P<0.0001) in hydrogen sulfide, methyl mercaptan and total measured VSCs immediately and after 1, 2, 3 and 12 (overnight) hours post-treatment. CONCLUSION The results of the present clinical study demonstrated that the use of the 0.1% w/w o-cymen-5-ol/ 0.6% w/w zinc chloride/ sodium fluoride dentifrice over a one week period provided a statistically significant benefit in controlling oral malodour for up to 12 hours post-treatment compared to a sodium fluoride control dentifrice.

A randomised clinical study to evaluate the effect of brushing duration on fluoride levels in dental biofilm fluid and saliva in children aged 4-5 years

OBJECTIVES To compare the effect of 40 seconds versus 2 minutes brushing on saliva and dental biofilm fluid fluoride in children ages 4-5 years over 1 hour. DESIGN This was a single-blind, cross-over, randomised, two-period clinical study in healthy children. Three days before the start of each treatment subjects received a thorough brushing and then refrained from all oral hygiene procedures. At treatment visits, after collecting baseline biofilm and saliva samples, staff brushed the occlusal surfaces of the subjects posterior teeth with a pea-sized amount (0.25 g) of NaF/silica toothpaste for the randomised time. Samples were taken at 5 minutes, 15 minutes, 30 minutes and 60 minutes after brushing and analysed for fluoride using a microanalytical methodology. There was a minimum 4-day washout period between treatments. RESULTS Log changes from baseline biofilm fluid and saliva fluoride were statistically significant (P < 0.05) for both brushing times at all post-brushing time-points [except 60 minutes saliva where P = 0.06 (t-test)]. Statistically significantly greater ln-AUC (area under the curve) was found for biofilm fluid and salivary fluoride after brushing for 2 minutes compared with brushing for 40 seconds over the 1-hour test period. There was a statistically significantly higher concentration of fluoride in the log change from baseline saliva levels after 5, 15, 30 and 60 minutes for the 2-minute brushing time compared with 40 seconds brushing time. There was no statistically significant difference in concentration of log change from baseline fluoride levels in biofilm fluid at each individual time-point (5, 15, 30 and 60 minutes) for the 2-minute brushing time compared with the 40-second brushing time, but significant differences were observed for 15, 30 and 60 minutes in favour of 2-minute brushing time when log biofilm fluid value was analysed. CONCLUSION The findings provide further evidence for the benefits of increased duration of brushing with respect to fluoride delivery.

Benefits of a silica-based fluoride toothpaste containing o-cymen-5-ol, zinc chloride and sodium fluoride.

Fluoride toothpastes in conjunction with tooth brushing are used to clean teeth, control plaque build-up and for anti-caries benefits. Toothpastes are designed with attractive flavours and appearances to encourage regular prolonged use to maximise these benefits. The incorporation of additional ingredients into toothpaste is a convenient way to provide supplementary protection that fits into peoples everyday oral care routine. Such ingredients should not compromise the primary health benefits of toothpaste nor discourage its use. o-Cymen-5-ol and zinc chloride have been incorporated into a sodium fluoride (NaF)/silica toothpaste at 0.1%w/w and 0.6%w/w respectively to provide additional benefits. These include improved gingival health maintenance, in terms of the reduction of plaque, gingival index and bleeding, and an immediate and long lasting reduction in volatile sulfur compounds (VSCs) measured on breath. These benefits can be attributed to the antimicrobial and neutralisation actions of the toothpaste. The use of established fluoride models demonstrated no compromise in NaF bioavailability. The toothpaste was formulated without compromising product aesthetics. The combination of o-cymen-5-ol and zinc chloride in toothpaste gave superior maintenance of gingival health and reduction in malodour related VSCs without compromising the primary health benefits of the toothpaste or diminishing attributes preferred for the products use.

Maintenance of gingival health post professional care

Oral hygiene habits are strongly associated with general health behaviours; good oral self care should result in good dental health. Clinical dental hygiene services have limited long range probability of success if the patient is not diligent in the daily procedures of personal care to remove and control dental plaque. Therefore, it is important to help make the individual aware of their own ability to control and maintain good oral health after a dental prophylaxis through oral care instruction and the use of select antimicrobials to maintain the gingival health. This paper reviews the evidence outlining the relative roles of prophylaxis and correct oral self-care in maintaining gingival health.

Quantification of gingival contour and volume from digital impressions as a novel method for assessing gingival health

OBJECTIVE To evaluate the novel assessment of gingival contour volume measurement from digital impressions compared with traditional clinical indices (Modified Gingival Index and Bleeding Index) and oral microflora following a dental prophylaxis. METHODS Following baseline examinations and full mouth digital impression using the LAVA™ Oral Chairside Scanner (COS), subjects had one maxillary quadrant and the contra-lateral mandibular quadrant randomly allocated to receive a complete dental prophylaxis. Subjects then brushed twice daily at home using a standard toothpaste. After 1, 2, 4, 6 and 12 weeks gingivitis examinations and digital impressions of the maxillary and mandibular arches were taken. RESULTS Significant improvements in gingivitis for the prophylaxis versus no prophylaxis quadrants were observed up to six weeks using both the traditional gingivitis indices and the assessment of change in gingival contour volume from the digital impressions. CONCLUSION The assessment of changes in gingival contour volume may be a promising technique for the objective and quantitative clinical evaluation of products or procedures used to treat gingivitis. The effects of a dental prophylaxis were demonstrated by both this novel measure and traditional clinical indices.