A randomised clinical in situ study to evaluate the effects of novel low abrasivity anti-sensitivity dentifrices on dentine wear.

OBJECTIVES: To compare the abrasive wear on human dentine in an in situ model associated with use of an experimental low abrasivity anti-sensitivity dentifrice containing 1% alumina and 5% sodium tripolyphosphate (STP) with an experimental ultra-low abrasivity non-alumina 5% STP dentifrice, a higher abrasivity daily-use whitening dentifrice, and water as controls. METHODS: This was a single-centre, single-blind, randomised, split-mouth, four-treatment, two-period, crossover in situ study in 29 healthy subjects. Subjects wore bilateral lower buccal appliances, each fitted with four dentine specimens. Study treatments were applied ex vivo (three times daily). Dentine loss was measured by non-contact profilometry after 5, 10 and 15days' treatment. RESULTS: All 29 subjects were included in the efficacy analysis. Significantly less dentine loss was associated with brushing with the low and ultra-low abrasivity dentifrices than with the higher abrasivity dentifrice at all timepoints (p<0.01). Brushing with ultra-low abrasivity dentifrice or water resulted in statistically significantly less dentine loss compared with brushing with the low abrasivity dentifrice at all timepoints (p<0.05). Dentine loss after brushing with ultra-low abrasivity dentifrice was not significantly different from brushing with water. CONCLUSIONS: The degree of dentine loss observed in this in situ model reflected the abrasivity of the study dentifrices. Brushing with low or ultra-low abrasivity STP-containing anti-sensitivity dentifrices resulted in significantly less dentine loss (equating to dentine wear) than with a higher abrasivity daily-use whitening dentifrice.

The role of toothpaste in the aetiology and treatment of dentine hypersensitivity.

Dentine hypersensitivity (DH) is a common, painful dental condition with a multi-factorial aetiology. The hydrodynamic mechanism theory to explain dentine sensitivity also appears to fit DH: lesions exhibiting large numbers of open dentinal tubules at the surface and patent to the pulp. By definition, DH can only occur when dentine becomes exposed (lesion localisation) and tubules opened (lesion initiation), thus permitting increased fluid flow in tubules on stimulation. Erosion, particularly from dietary acids appears to play a dominant role in both processes. Toothbrushing with most toothpaste products alone cause clinically insignificant wear of enamel but are additive, even synergistic, to erosive enamel loss. Additionally, toothbrushing with toothpaste is implicated in 'healthy' gingival recession. Toothbrushing with most toothpastes removes the smear layer to expose tubules and again can exacerbate erosive loss of dentine. These findings thereby implicate toothbrushing with toothpaste in the aetiology of DH. Management of the condition should have secondary prevention at the core of treatment and therefore, must consider first and foremost the aetiology. Fluoride toothpaste at present appears to provide little primary or secondary preventive benefits to DH; additional ingredients can provide therapeutic benefits. Potassium-based products to block pulpal nerve response have caused much debate and are considered by many as unproven, which should not translate to ineffective. Several toothpaste technologies formulated to block tubules are from studies in vitro, in situ and controlled clinical trials considered proven for the treatment of DH.

In situ randomised trial to investigate the occluding properties of two desensitising toothpastes on dentine after subsequent acid challenge.

OBJECTIVES: The aim of the study was to determine in situ the relative abilities of two desensitising toothpastes to occlude dentinal tubules with or without acid challenge. MATERIALS AND METHODS: The study design was a single centre, randomised, split mouth crossover model examining four treatments over two periods. The primary outcome was the degree of occlusion proffered by two desensitising toothpastes [Sensodyne® Rapid Relief (8% strontium acetate, 1040 ppm sodium fluoride) and Colgate® Sensitive Pro-ReliefTM daily (8% arginine, 1450 ppm sodium monofluorophosphate)], a standard toothpaste (1450 ppm sodium fluoride) and water, after acid challenge. Healthy adult volunteers wore bi-lateral lower buccal appliances each with two dentine sections, receiving two treatments per study period. Samples were brushed twice a day with treatment, with two additional 3-min extra-oral acidic challenges applied ex vivo on days 3 and 4. A secondary outcome was the degree of occlusion attained in the absence of acid challenge. Examiners blinded to the study assessed occlusion by visual score of post-treatment scanning electron microscope images. RESULTS: All 28 participants completed the study. In the absence of acid challenge, occlusion scores for both desensitising toothpastes were similar and significantly better than control scores (p < 0.02). After acid challenge both desensitising toothpastes occluded more effectively than controls; however, occlusion scores for the strontium acetate paste were significantly greater than those of the arginine paste (p < 0.02). CONCLUSIONS: The occluding properties of the strontium acetate toothpaste were significantly more robust after acid challenge than those of the arginine toothpaste. CLINICAL RELEVANCE: Patients with hypersensitivity, regularly imbibing dietary acidic drinks, should be advised that Sensodyne® Rapid Relief provides robust tubule occlusion despite repeated acidic challenges.

Randomized in situ clinical study comparing the ability of two new desensitizing toothpaste technologies to occlude patent dentin tubules.

OBJECTIVE: To compare the ability of two new desensitizing toothpaste technologies (one a 5% NovaMin-based toothpaste and the other an 8% arginine-based toothpaste) to occlude patent dentin tubules in a clinical environment relative to a negative control of water and a control toothpaste after four days of twice-daily brushing and dietary acidic challenges. METHODS: The study design was a single-center, single-blind, randomized, split-mouth, four-treatment, two-period, crossover, in situ clinical study. Healthy subjects wore two lower intra-oral appliances, retaining four dentin samples for four treatment days for each period of the clinical study. Samples were brushed twice daily with a test product (days 1-4), with an additional acidic challenge introduced on two selective days. Scanning electron microscopy (SEM) images were taken of the dentin surface, and dentinal tubule occlusion assessed using a categorical scale. RESULTS: The results demonstrated that the 5% NovaMin toothpaste was statistically superior at occluding patent dentin tubules compared to water (p = 0.009) and the control toothpaste (p = 0.02) at day 4. In contrast, the treatment effect resulting from the 8% arginine toothpaste did not demonstrate the same degree of occlusive propensity, showing no significant difference to the water and control toothpaste at the day 4 time point. CONCLUSION: Application of the 5% NovaMin toothpaste to dentin showed better dentin tubule occlusion and retention abilities in an oral environment under dietary acid challenge conditions, more so than the 8% arginine toothpaste technology. Given modern dietary habits and practices, these results highlight differences in the acid resistance properties of occlusion technologies, and a potential impact on clinical performance.

The protective effects of toothpaste against erosion by orange juice: studies in situ and in vitro.

OBJECTIVES: There has been a monumental increase in the consumption of soft drinks, fruit juices and sport drinks in the UK, the US, and many other countries. Previous investigations have demonstrated the erosive nature of these acidic soft drinks. The aim of this investigation was to determine the protective effects of an experimental fluoride-based toothpaste, containing sodium hexametaphosphate, against an erosive challenge on tooth enamel. METHODS: The erosion of enamel by orange juice compared the experimental toothpaste with a benchmark sodium fluoride paste and negative control, water, in a 15-day in situ model; and the same in an in vitro enamel erosion model. Flat, polished human enamel samples with a surface profile of +/-0.1mum, were exposed to the three regimens in the single blind, crossover clinical study mimicked in vitro. Depths of the resulting eroded areas were measured using a profilometer. RESULTS: There was significantly more erosive damage on the specimens exposed to the benchmark paste and water compared to the test paste in both the in situ and in vitro studies. CONCLUSIONS: The data provide further support for tooth brushing before meals. Results of this study further suggest the sodium hexametaphosphate containing paste could be used to provide significant erosion protection in susceptible individuals over that provided by conventional fluoride products.

Dentine hypersensitivity: the effects of brushing toothpaste on etched and unetched dentine in vitro.

Although many people have exposed dentine, only a percentage exhibit symptoms of dentine hypersensitivity. This has been ascribed to opening and closing of the dentinal tubules by for example, smear layer changes or tubular occlusion. The aims of this study were to examine the surface morphological changes of etched and unetched dentine in vitro, attributed to the effects of toothbrushing with and without toothpastes designed for the alleviation of dentine hypersensitivity. A total of 96 etched and 96 unetched human dentine specimens were brushed with various toothpastes and water for 1, 2, 5 or 10-min periods in a toothbrushing machine and subsequently examined under scanning electron microscopy for surface changes. Analyses of brushed etched specimens demonstrated that time and treatment were significant variables (P < 0.05) for tubule occlusion. Further, the interaction between time and treatment was significant (P < 0.05). The artificial silica based paste was significantly better for all time intervals at occluding the dentine tubules. All toothpastes investigated caused dynamic changes to the smear layer of the unetched dentine, opening tubules. However, the artificial silica based paste resulted in occluded rather than patent tubules. All of the pastes evaluated had the capacity to remove the smear layer but some could then occlude tubules through the contained abrasives.