Brushing, Toothpastes, Salivation, and Remineralization

Fig. 16.1

Toothpaste ingredients. Toothpastes contain a number of ingredients that stabilize the product and/or provide esthetic benefits, in addition to the ingredients that provide therapeutic or cosmetic benefits (Adapted from Koenigs and Faller (2015). Reprinted with permission)
These components help keep the toothpaste properly mixed with a smooth consistency, and they make the product palatable to the consumer. The abrasive, humectant, and solvent ingredients typically represent about 95 % of the overall toothpaste formulation. Today’s modern toothpastes represent highly sophisticated formulation science that has enabled the inclusion of a multitude of additional benefits beyond caries prevention. These include ingredients for calculus (tartar) inhibition, plaque and gingivitis control, sensitivity reduction, erosion prevention, whitening/stain removal, and oral malodor control.

16.1.4 Fluoride and Non-fluoride Mineralization Systems

In the last few decades, significant research has focused on the use of new technologies, either alone or in combination with fluoride, to enhance the remineralization potential of toothpastes beyond the level provided by fluoride. A number of approaches have been suggested, including casein phosphopeptide and amorphous calcium phosphate, tricalcium phosphate, bioglass, arginine bicarbonate, nanoapatites, etc. Although there are a limited number of clinical studies that have been conducted to assess a few of these approaches, the majority of the available data is limited to in vitro or in situ model studies rather than properly controlled caries clinical trials (Amaechi and van Loveren 2013). As such, there is insufficient data available at this point to determine if any of these approaches provide any added clinical benefits beyond what is already being delivered with conventional fluoride sources. For a more complete discussion of fluoride and other mineralization agents incorporated into and delivered from toothpastes, see Chapter 15.
Even with the significant expansion of benefits delivered by modern toothpaste formulations, it is important to remember that the most important benefit these products deliver is with regard to caries prevention. It has been known for many years that compromising fluoride availability can adversely impact toothpaste performance. The earliest clinical trials that tested NaF in toothpaste formulations that contained a calcium carbonate abrasive demonstrated no anticaries efficacy; this was a result of the NaF interaction with the calcium abrasive system, resulting in the formation of an inactive calcium fluoride (Bibby 1948). It is therefore important to ensure that new additives do not compromise the anticaries effectiveness of any new formulation. For example, upon the introduction of a triclosan/PVM/MA copolymer system into a sodium fluoride toothpaste to aid in the control of plaque and gingivitis, three caries clinical trials were conducted to demonstrate the addition of the new agent did not adversely impact the caries benefit delivered by the fluoride active (Feller et al. 1996; Hawley et al. 1995; Mann et al. 1996). Although this level of clinical evaluation is not necessary for every new formulation, it highlights the issue that new ingredients may adversely impact overall product efficacy, and an appropriate evaluation is needed to ensure the caries benefit has not been compromised.

16.1.5 Toothpastes and Abrasivity

Toothpaste abrasives help keep teeth clean by removing stain that forms in the pellicle layer on exposed tooth surfaces (Addy and Moran 1995). One of the key focus areas of modern toothpaste development has been the cleaning potential of toothpastes, which is partly a function of the abrasivity of the individual products. A paper by Kitchen and Robinson in 1948 (Kitchin and Robinson 1948) asked a very important question: “How abrasive must a dentifrice be?” In this paper, the authors directly compared the clinical stain removal ability of toothpaste formulations with in vitro assessments of the abrasivity of these same formulations. In this study, the authors found that over 90 % of tooth stain could be removed in approximately 2 weeks using toothpastes that contained levels and types of abrasives that produced less than 1 mm of dentin wear, as measured using the in vitro method they had developed. This method included brushing tooth specimens for 100,000 strokes with a diluted dentifrice slurry. Based on the results of their work, the authors concluded:

Dentifrice abrasiveness greater than that necessary to cut 1 mm per 100,000 strokes into the cervical area of teeth with the apparatus employed appears to be unnecessary even for very heavy strainers… Generally speaking, for stainers with cervical exposure, a dentifrice with a safety index as high as is consistent with prevention of stain accumulation is desirable. Reliable current information on dentifrice abrasion, determined by testing whole dentifrices on dentin, should be available (Kitchen and Robinson 1948).
Later efforts, primarily in the 1950s and 1960s, led to the development of formal abrasivity testing procedures, and these served as the basis for standards currently recommended by the American Dental Association (ADA) and the International Standards Organization (ISO). Given the growing consumer expectation for multi-benefit products, dentifrice formulations need to deliver a level of abrasiveness sufficient to control staining and plaque buildup, without risking the use of overly aggressive abrasive systems that could be deleterious to hard tissues after long-term use. Some researchers have proposed the use of a Cleaning Efficiency Index as one way to assess the cleaning/abrasion balance (Schemehorn et al. 2011). Further work in this area would be helpful, and it needs to incorporate human use studies as part of the evaluation. As a general rule, modern dentifrices are formulated to provide specific therapeutic/cosmetic benefits while delivering abrasivity levels that are well within the accepted limits, with the goal of ensuring consumers receive the best products possible for their specific oral health needs. A recently published paper on the history of the development of abrasivity standards for toothpastes provides an excellent summary of these efforts as well as technical insight into their interpretation regarding not only tooth cleaning potential but also with regard to other oral care issues such as dental erosion (St John and White 2015).

16.1.6 Toothpastes and Abrasivity Testing

The most widely used method for assessing toothpaste abrasivity is the Radioactive (also referred to as Relative) Dentin Abrasivity (RDA) method, an in vitro radiotracer method developed as an outcome of studies by Grabenstetter et al. (Grabenstetter et al. 1958) and Hefferren (1976). This method has served the industry well, establishing a limit of abrasivity of an RDA of 250, under which a dentifrice can be used safely on a daily basis for a lifetime. The industry has largely self-regulated since these standards were put in place, with dentifrices being used safely for the last half century. Although the method has been accepted across the industry and practiced for many years, there is a clear need for modern updating. The requirement for radiotracer capabilities significantly restricts the ability of many researchers to focus on the development of new abrasive technologies for toothpaste. Over the years, alternative methods have been proposed, such as profilometry (Addy 2010). Although one profilometry method has received some level of acceptance, until recently profilometry methods in general have not been thoroughly validated with regard to their ability to directly duplicate the accepted radiotracer method. A number of papers have suggested similar, but not direct, agreement between methods (Kinoshita et al. 1979; Davis and Winter 1976; Davis 1979; Sabrah et al. 2013). A recent study by White and colleagues, however, has provided the first evidence of a profilometry-based method that is both linearly and proportionally correlated with the conventional RDA method (White et al. 2015).
In addition to RDA measures, some researchers have suggested REA (Relative Enamel Abrasivity) measures might also be helpful to consider. REA measures are done using essentially the same techniques as RDA, with an adjustment made in the calculations that takes into account the relative differences in hardness between dentin and enamel (Addy 2010). One of the primary issues with the use of REA measures is the lack of confirmed correlation between REA and RDA values. For example, studies have demonstrated that not all toothpastes with high RDA values also have a high REA value. In fact, some toothpastes with high RDA values have been shown to provide low REA values, and others with low RDA have demonstrated high REA (Joiner et al. 2004). While dentin wear has been correlated to RDA values in the laboratory (White et al. 2015; Philpotts et al. 2005), no such correlation has been demonstrated with regard to REA measurements.

16.2 Toothbrush: Manual vs. Power

Once a consumer has chosen which toothpaste is best suited to meet his/her individual needs, the decision as to which toothbrush to use is also an important aspect of that person’s oral hygiene routine. Although the majority of people brush their teeth with a manual toothbrush, many fail to achieve optimal gingival health. This is primarily due to the fact that most people do not brush long enough or using the proper technique, even if brushing twice-per-day (Beaglehole et al. 2009; Tedesco 1995). Numerous brushing implements are available to the consumer, including a wide range of brush head sizes and geometries and bristle filament stiffness and design (end-rounded or not) and brushes which are manually powered, battery-powered, rechargeable, sonic, oscillation-rotation, and others. Combining the range of the various toothbrush designs with individual brushing techniques provides a rather complex mix of potential brushing scenarios.
Brushing teeth properly is important for maintaining healthy teeth and gums, and it reduces the risk of developing tooth decay and gingival disease, which are the major causes of tooth loss. From the standpoint of plaque removal, better cleaning can generally be achieved with the use of power toothbrushes (see discussions that follow). There are a number of differences between manual and power brushes, and each user must decide which option best meets their individual needs (Table 16.1).

Table 16.1

Each individual user must evaluate the key differences and options provided by the various types of toothbrushes available
Benefits of manual and powered toothbrushes
Manual brush
 Widely available in retail outlets
 Wide variety of designs available
Power brush
 Certain technologies provide more effective plaque removal and gingivitis reduction than manual brushes
 Some models have compliance-enhancing features (e.g., timer, pressure sensor, different brushing modes)
 Advanced models with Bluetooth technology provide real-time feedback, track brushing sessions, and allow the patient and oral health professional to customize the brushing session based on the patient’s individual needs

16.2.1 Brushing Techniques

To brush properly with a manual toothbrush, oral health professionals generally recommend the use of fluoride toothpaste along with a soft-bristled brush, which should be replaced about every three months. Most dental health professionals recommend brushing for at least two minutes, twice per day using a standard brushing technique. This includes brushing all tooth surfaces (buccal, lingual, and occlusal) in each of the four quadrants of the mouth, for 30 s per quadrant, morning and night. With regard to the position of the brush, hold the brush at a 45-degree angle to the gumline and use short, half-tooth wide strokes, making sure to reach the back teeth. On the lingual surfaces of the anterior teeth, the brush should be placed vertically and gentle up-and-down strokes can be used. On the occlusal surfaces of the teeth, the brush should be held flat, using back and forth strokes along these surfaces. Finally, the tongue should be brushed using a back-to-front sweeping motion. This helps remove food particles and odor-causing bacteria which contribute to malodor if not removed.
Although manual toothbrushes are not able to provide many of the features that are being incorporated into many power brushes, they still are able to provide important benefits for people who prefer these types of brushes. For example, some brushes incorporate angled, extra-long or multilevel bristle tufts, all of which are designed to help clean in hard-to-reach areas. Cupped bristles, ergonomically designed handles with special grips, tapered or angled brush heads, gum stimulators, tongue cleaning pads, etc. are all manual toothbrush innovations designed to provide a better cleaning experience for individual users, all of which can help improve oral health. In addition to the design of the brush itself, the use of supplemental means, such as dental floss, interdental brushes, mouthrinses, etc., may further enhance the overall oral hygiene experience.

16.2.2 Clinical Brushing Studies

In addition to individual brushing technique, the number of brushing sessions per day, the duration of brushing, and the type of toothbrush used have a direct impact on the amount of plaque removed. Randomized clinical trials provide an important means for demonstrating the effectiveness of various toothbrush designs with regard to plaque reduction. A recent systematic review evaluating manual brush designs found that angled bristle designs demonstrate greater plaque removal efficacy compared to those with flat-trim or multilevel bristles (Slot et al. 2012). Since the introduction of power brushes, well-designed and controlled clinical trials have measured the relative ability of power vs. manual brush designs with regard to plaque removal. In a recent historical review of clinical studies, the independent, not-for-profit Cochrane Collaboration concluded that oscillating-rotating technology was the only type of power brush that consistently reduced plaque and gingivitis more effectively than a manual toothbrush in both the short and long term (Yaacob et al. 2014). In addition, a recent review by Grender and colleagues, in which 6 clinical trials were assessed with regard to the ability of oscillating-rotating brushes to remove plaque from specific tooth surfaces, found that oscillating-rotating brushes resulted in significantly greater plaque removal on lingual, approximal, and gingival areas compared to either sonic or manual brushes included in the studies (Grender et al. 2013).

16.2.3 Power Brush Options

Power toothbrushes currently on the market include battery-powered as well as rechargeable electric brushes. Rechargeable electric toothbrushes are more sophisticated, and these differ significantly in the type of cleaning technology used. Many different types and designs are available, with various modes of action, including side-to-side, ultrasonic, counter-oscillation, circular, and oscillation-rotation. A 2011 Cochrane review compared the efficacy of various power technologies (Deacon et al. 2010). Three hundred and ninety-eight studies were included; 17 trials with 1369 subjects met selection criteria and were ultimately evaluated. Seven studies compared rotation-oscillation and side-to-side (sonic) technologies. The review found, “Brushes with a rotation oscillation action reduced plaque and gingivitis more than those with a side-to-side (sonic) action in the short term (4–12 weeks).”
One of the benefits of electric toothbrushes is the amount of technology and features that can be integrated into their design. Brushing techniques vary, depending on the type of toothbrush used. Some of the currently available models incorporate multiple brushing modes that are specifically designed for sensitive teeth, provide whitening benefits, or even to massage gums. Some models include sensors that signal when too much pressure is applied, timers to help ensure a sufficient duration of brushing, and digital reminders to replace the brush head at regular intervals, among others. Most recently models have been introduced with Bluetooth technology to provide real-time brushing feedback, track brushing sessions, and allow the patient and oral health professional to customize brushing areas based on the patient’s individual needs. Importantly, all of these features can help consumers improve their routine brushing habits (Walters et al. 2007).

16.3 Saliva and Saliva Substitutes

Saliva is necessary, not only for lubrication of the mouth but also for buffering bacterial acids, providing proteins that deposit onto tooth surfaces and form the protective pellicle, delivering key minerals required for remineralization processes, providing protection against a range of microbes that we are constantly exposed to through our mouths, and other key oral functions that are critical to long-term oral health. Saliva is also important for the dispersion of actives in toothpaste during the process of brushing (Turssi et al. 2010; Stookey et al. 2011). A reduction in salivary flow, often the result of salivary gland hypofunction or xerostomia, is a common occurrence. This is particularly true in the elderly, as a result of the intake of a wide range of routine medications. Significant reduction in salivary flow can lead to discomfort, difficulty in eating, and an increase in oral diseases, such as caries (Deng et al. 2015). While the diagnosis of salivary gland hypofunction and xerostomia is relatively easy to make, treatment of these conditions can be rather difficult. The primary objective, beyond ensuring proper medical treatment, is to provide as much hydration as possible, to reduce all unnecessary medications, and to provide topical remedies, such as saliva substitutes when possible. When salivary flow is severely diminished, as is often the case with head-and-neck radiation patients, parasympathomimetic drugs are sometimes used to help alleviate the problem. The increased caries incidence in individuals suffering from hyposalivation is often the result of a reduced buffer capacity, compromised ability to clear the mouth of debris, and a reduced potential for remineralization, coupled with a diet that may be high in carbohydrates and cariogenic salivary stimulants (Kielbassa et al. 2006; Dreizen et al. 1977; Vissink et al. 2003). Fluoride mouthrinses, as well as high fluoride concentration toothpastes, are often recommended in cases where saliva flow is restricted (Meyerowitz et al. 1991; Su et al. 2011).
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Sep 10, 2016 | Posted by in General Dentistry | Comments Off on Brushing, Toothpastes, Salivation, and Remineralization
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