Fluoride was introduced into dentistry over 70 years ago, and it is now recognized as the main factor responsible for the dramatic decline in caries prevalence that has been observed worldwide. However, excessive fluoride intake during the period of tooth development can cause dental fluorosis. In order that the maximum benefits of fluoride for caries control can be achieved with the minimum risk of side effects, it is necessary to have a profound understanding of the mechanisms by which fluoride promotes caries control. In the 1980s, it was established that fluoride controls caries mainly through its topical effect. Fluoride present in low, sustained concentrations (sub-ppm range) in the oral fluids during an acidic challenge is able to absorb to the surface of the apatite crystals, inhibiting demineralization. When the pH is re-established, traces of fluoride in solution will make it highly supersaturated with respect to fluorhydroxyapatite, which will speed up the process of remineralization. The mineral formed under the nucleating action of the partially dissolved minerals will then preferentially include fluoride and exclude carbonate, rendering the enamel more resistant to future acidic challenges. Topical fluoride can also provide antimicrobial action. Fluoride concentrations as found in dental plaque have biological activity on critical virulence factors of S. mutans in vitro, such as acid production and glucan synthesis, but the in vivo implications of this are still not clear. Evidence also supports fluoride’s systemic mechanism of caries inhibition in pit and fissure surfaces of permanent first molars when it is incorporated into these teeth pre-eruptively.

Mechanisms of action of fluoride for caries control.

Purpose: This review integrated the current literature on diffusion of whitening agents, their interactions with stain molecules, and changes to the surface, with the aim of establishing a better understanding of the mechanism underlying tooth whitening. Materials and Methods: An electronic PubMed database search, with combinations of the following terms was performed:Tooth Bleaching,Tooth Bleaching Agent, Hydrogen Peroxide, Pharmacokinetics,Tooth Permeability, Oxidation-Reduction,Tooth Demineralization, and Color. Results: Tooth whitening is a dynamic process that involves diffusion of the whitening material to interact with stain molecules and also involves micromorphologic alterations on the surface and changes within the tooth that affect its optical properties.The interaction seems not to be limited to stain molecules, but rather an affinity-based interaction process that also accompanies effects on sound enamel and dentin structures. Conclusions: This review underlines that supervision by dental health professionals as recommended by the American Dental Association (ADA) Council on Scientific Affairs is critical to achieving a successful and safe whitening outcome. CLINICAL SIGNIFICANCE The mechanism that underlies tooth whitening with the use of peroxide-based materials is a complex phenomenon encompassing diffusion, interaction, and surfaces changes within the tooth.Therefore, supervision by dental health professionals as recommended by the ADA Council on Scientific Affairs is imperative to achieve a successful and safe whitening outcome. (J Esthet Restor Dent ••:••-••, 2015)

Review of the Mechanism of Tooth Whitening

BACKGROUND: Removing dental plaque may play a key role maintaining oral health. There is conflicting evidence for the relative merits of manual and powered toothbrushing in achieving this. This is an update of a Cochrane review first published in 2003, and previously updated in 2005. OBJECTIVES: To compare manual and powered toothbrushes in everyday use, by people of any age, in relation to the removal of plaque, the health of the gingivae, staining and calculus, dependability, adverse effects and cost. SEARCH METHODS: We searched the following electronic databases: the Cochrane Oral Health Group's Trials Register (to 23 January 2014), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2014, Issue 1), MEDLINE via OVID (1946 to 23 January 2014), EMBASE via OVID (1980 to 23 January 2014) and CINAHL via EBSCO (1980 to 23 January 2014). We searched the US National Institutes of Health Trials Register and the WHO Clinical Trials Registry Platform for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases. SELECTION CRITERIA: Randomised controlled trials of at least four weeks of unsupervised powered toothbrushing versus manual toothbrushing for oral health in children and adults. DATA COLLECTION AND ANALYSIS: We used standard methodological procedures expected by The Cochrane Collaboration. Random-effects models were used provided there were four or more studies included in the meta-analysis, otherwise fixed-effect models were used. Data were classed as short term (one to three months) and long term (greater than three months). MAIN RESULTS: Fifty-six trials met the inclusion criteria; 51 trials involving 4624 participants provided data for meta-analysis. Five trials were at low risk of bias, five at high and 46 at unclear risk of bias.There is moderate quality evidence that powered toothbrushes provide a statistically significant benefit compared with manual toothbrushes with regard to the reduction of plaque in both the short term (standardised mean difference (SMD) -0.50 (95% confidence interval (CI) -0.70 to -0.31); 40 trials, n = 2871) and long term (SMD -0.47 (95% CI -0.82 to -0.11; 14 trials, n = 978). These results correspond to an 11% reduction in plaque for the Quigley Hein index (Turesky) in the short term and 21% reduction long term. Both meta-analyses showed high levels of heterogeneity (I(2) = 83% and 86% respectively) that was not explained by the different powered toothbrush type subgroups.With regard to gingivitis, there is moderate quality evidence that powered toothbrushes again provide a statistically significant benefit when compared with manual toothbrushes both in the short term (SMD -0.43 (95% CI -0.60 to -0.25); 44 trials, n = 3345) and long term (SMD -0.21 (95% CI -0.31 to -0.12); 16 trials, n = 1645). This corresponds to a 6% and 11% reduction in gingivitis for the L�e and Silness index respectively. Both meta-analyses showed high levels of heterogeneity (I(2) = 82% and 51% respectively) that was not explained by the different powered toothbrush type subgroups.The number of trials for each type of powered toothbrush varied: side to side (10 trials), counter oscillation (five trials), rotation oscillation (27 trials), circular (two trials), ultrasonic (seven trials), ionic (four trials) and unknown (five trials). The greatest body of evidence was for rotation oscillation brushes which demonstrated a statistically significant reduction in plaque and gingivitis at both time points. AUTHORS' CONCLUSIONS: Powered toothbrushes reduce plaque and gingivitis more than manual toothbrushing in the short and long term. The clinical importance of these findings remains unclear. Observation of methodological guidelines and greater standardisation of design would benefit both future trials and meta-analyses.Cost, reliability and side effects were inconsistently reported. Any reported side effects were localised and only temporary.

Powered versus manual toothbrushing for oral health.

https://www.zora.uzh.ch/id/eprint/19783/2/19783.pdf

Influence of study design on the impact of bleaching agents on dental enamel microhardness: a review

The use of “red flags” (specific information from the clinical history and examination used as sentinels of disease) to guide decisions about the need for further investigation of suspected vertebral fracture in patients presenting with low-back pain is unfounded. That’s the discouraging conclusion of the latest diagnostic test accuracy review. The authors looked at eight studies and found that many red flags have high falsepositive rates. The limited evidence makes recommending specific red flags a challenge, but three (older age, significant trauma and corticosteroid use) were more promising, and combinations of red flags were more informative than individual tests (doi: 10.1002/14651858.CD008643.pub2). The primary prevention of cardiovascular disease comes under the spotlight in one new and one updated review. Selenium supplementation is aggressively marketed in some quarters, but the evidence from a new review of 12 studies involving nearly 20 000 participants does not support its use, especially in populations with adequate selenium status. Furthermore, the authors are cautious not to rule out the possibility of an increased risk of type 2 diabetes from taking selenium-only supplements (doi: 10.1002/14651858.CD009671. pub2). More definitive is the evidence to support the use of statins in people at low risk of cardiovascular disease. This comes from an updated review that now includes data on 57 000 participants from 18 randomised trials. Statins reduced major vascular events as well as all-cause mortality. Added bonuses were the absence of serious harms and the likelihood that statins are cost-effective (doi: 10.1002/14651858.CD004816.pub5). An updated review provides mixed relief for people with diabetes suffering from foot ulcers. Non-removable, pressure-relieving casts heal ulcers more effectively than removable casts or dressings alone, but this comes at the price of restricted movement and a possible decrease in quality of life (doi: 10.1002/14651858.CD002302.pub2). Hiccups are a passing nuisance for most of us, but spare a thought for the few who suffer from persistent or intractable hiccups (defined as lasting for more than 48 hours and more than 1 month, respectively). Unfortunately, there’s little relief in sight, since the four poor-quality trials reviewed all investigated treatment with acupuncture and showed that it may be no better than placebo (doi: 10.1002/14651858.CD008768.pub2). Find these and other new and updated reviews this month in The Cochrane Library at www.thecochranelibrary.com. From The Cochrane Library

Cochrane Library

Plaque levels of patients with fixed orthodontic appliances measured by digital plaque image analysis

Effects of elevated hydrogen peroxide ‘strip’ bleaching on surface and subsurface enamel including subsurface histomorphology, micro-chemical composition and fluorescence changes

The effect of strip, tray and office peroxide bleaching systems on enamel surfaces in vitro.

Recently, a novel antibacterial fluoride dentifrice containing stannous fluoride and sodium hexametaphosphate (CrestPRO-HEALTH) was introduced. A digital plaque image analysis (DPIA) technique was used to quantify in situ plaque formation in a population carrying out a phased intervention protocol that included: (1) an initial treatment regimen including toothbrushing with standard sodium fluoride dentifrice in conventional bid brushing, (2) a second treatment regimen where a modified hygiene regimen was applied using standard sodium fluoride dentifrice including a period of 24 hours of non-brushing, and (3) a third treatment regimen where the 24-hour non-brushing regimen was continued using the antimicrobial stannous fluoride/sodium hexametaphosphate dentifrice. The quantitative evaluation of plaque formation was assessed in morning measurements following either standard evening hygiene (treatment period 1) or 24 hours since brushing (treatment periods 2 and 3). Post-brushing plaque measurements were also taken in each treatment regimen. Sixteen subjects completed all three treatment regimens with no side effects or oral complaints. Morning plaque coverage in treatment period 1 was 13.3%. Plaque coverage significantly increased in treatment period 2 when pre-bedtime brushing was discontinued, with 24-hour growth covering 18.4% of the dentition. Intervention of the antimicrobial stannous fluoride/hexametaphosphate dentifrice in treatment period 3 provided significant inhibition of plaque regrowth over 24 hours (15.2% coverage, a 17% reduction vs. sodium fluoride dentifrice control). These results support the strong retention and lasting antimicrobial efficacy of high stabilized stannous fluoride/sodium hexametaphosphate dentifrices.

/pdf/a-24-hour-dental-plaque-prevention-study-with-a-stannous-2wb696rrjk.pdf

Malgorzata Klukowska

Papers

Plaque levels of patients with fixed orthodontic appliances measured by digital plaque image analysis

Effects of elevated hydrogen peroxide ‘strip’ bleaching on surface and subsurface enamel including subsurface histomorphology, micro-chemical composition and fluorescence changes

The effect of strip, tray and office peroxide bleaching systems on enamel surfaces in vitro.

A 24-hour dental plaque prevention study with a stannous fluoride dentifrice containing hexametaphosphate.

Efficacy of 3 toothbrush treatments on plaque removal in orthodontic patients assessed with digital plaque imaging: a randomized controlled trial.