Description of the condition

Periodontal diseases

Periodontal diseases are multifactorial oral health conditions (Llorente 2006; Timmerman 2006), consisting of a diverse family of pathological conditions affecting the periodontium (a collective term that comprises gingival tissue, periodontal ligament, cementum and alveolar bone), that commonly affect the population (Adult Dental Health Survey 2009; Eke 2012). Periodontal diseases include two main conditions: gingivitis and periodontitis. Gingivitis is defined as the presence of gingival inflammation without loss of connective tissue attachment and appears as red, puffy, shiny gums that bleed easily (Mariotti 1999). Periodontitis is defined as inflammation and destruction of the supportive tissues of teeth and is, by its behaviour, characterised as aggressive or chronic (Armitage 1999). Susceptibility to periodontal disease is variable and depends upon the interaction of various risk factors, for example genetic makeup, smoking, stress, immunocompromising diseases, immunosuppressive drugs, and certain systemic diseases, for example diabetes (Van Dyke 2005). Socioeconomic factors, for instance educational and income levels, have been found to be strongly associated with the prevalence and severity of periodontal diseases (Borrell 2012).

The prevalence of periodontitis is difficult to establish across studies because of non‐standardised criteria, different study population characteristics, different clinical measurements, and the use of partial versus full mouth examinations (Cobb 2009; Savage 2009). Of particular concern are the differing definitions and clinical measurements being used (Cobb 2009; Savage 2009). Recent national studies have assessed oral cleanliness, periodontal disease and oral hygiene behaviour. In the UK only 17% of adults had healthy gums; 66% had visible plaque; and of those with plaque, 65% had bleeding gums compared with 33% with no plaque (Adult Dental Health Survey 2009). Whilst more severe forms of periodontal disease, with alveolar bone loss, are much less common, gingivitis is prevalent at all ages and is the most common form of periodontal disease (Mariotti 1999). Some form of periodontitis affects the majority of the population (Adult Dental Health Survey 2009; Eke 2012). Periodontitis can influence quality of life through psychosocial impacts as a result of negative effects on comfort, function, appearance and socialisation (Durham 2013; Needleman 2004). It can also lead to tooth loss (Broadbent 2011), which negatively impacts on both aesthetics and function. Since periodontal diseases are inflammatory, bacterially mediated diseases that trigger the host's immune system, it is postulated that the individual's oral health status may influence their systemic health. Studies have shown some possible associations between periodontal diseases and coronary heart disease (Machuca 2012), hyperlipidaemia (Fentoğlu 2012), preterm births (Huck 2011), and lack of glycaemic control in people with diabetes mellitus (Columbo 2012; Simpson 2010).

Dental plaque is the primary aetiological factor in the development of periodontal diseases and dental caries (Dalwai 2006; Kuramitsu 2007; Marsh 2006; Periasamy 2009; Selwitz 2007). Dental plaque is a highly organised and specialised biofilm comprising of an intercellular matrix consisting of various micro‐organisms and their by‐products. The bacteria found within dental plaque mutually support each other, using chemical messengers, in a complex and highly evolved community, that protects them from an individual's immune system and chemical agents such as antimicrobial mouth rinses. Bacteria in biofilm are 1000 to 1500 times more resistant to antibiotics than in their free‐floating state, reducing the effectiveness of chemical agents as a solo treatment option. Therefore disruption of the oral biofilm via mechanical methods remains one of the best treatment options (Chandki 2011). Calcified plaque (calculus) is not involved in the pathogenesis of periodontal disease but it provides an ideal surface to collect further dental plaque and acts as a 'retention web' for bacteria, protecting plaque from appropriate preventive and therapeutic periodontal measures (Ismail 1994; Lindhe 2003).

Dental caries

Dental caries is a multifactorial, bacteriologically mediated, chronic disease (Addy 1986; Richardson 1977; Rickard 2004). According to the World Oral Health Report 2003 (Petersen 2003), dental caries affects 60% to 90% of school children and the vast majority of adults, making it one of the most common diseases in the world population (WHO 1990). Although the prevalence and severity of dental caries in most industrialised countries has substantially decreased in the past two decades (Marthaler 1996), this preventable disease continues to be a common public health problem for other parts of the world (Burt 1998).

Deep pits and fissures, as well as interdental spaces, represent areas of increased risk for the collection and accumulation of dental plaque and are therefore regarded as susceptible tooth surfaces for the occurrence of carious lesions. The presence and growth of dental plaque is further encouraged by compromised host response factors, for example reduced salivary flow (hyposalivation) (Murray 1989). Fermentation of sugars by cariogenic bacteria within the plaque results in localised demineralisation of the tooth surface, which may ultimately result in cavity formation (Marsh 2006; Selwitz 2007).

Patients with carious teeth may experience pain and discomfort (Milsom 2002; Shepherd 1999); and, if left untreated, may lose their teeth. In the United Kingdom, tooth decay accounts for almost half of all dental extractions performed (NHS 1999).

Prevention of dental caries and periodontal disease is generally regarded as a priority for oral healthcare professionals because it is more cost‐effective than treating it (Brown 2002; Burt 1998). Effective plaque control by toothbrushing is a key self care strategy for oral health (Addy 1986; Richardson 1977). Patients routinely use toothbrushes to remove supragingival dental plaque, but toothbrushes are unable to penetrate the interdental area where periodontal disease first develops and is prevalent (Asadoorian 2006; Berchier 2008; Berglund 1990; Casey 1988). Interdental plaque is more prevalent (Lindhe 2003), forms more readily (Igarashi 1989) and is more acidogenic than plaque on other tooth surfaces in the mouth. Therefore interdental cleaning is often recommended as an adjunctive self care therapy, particularly when caries risk is increased (Sarner 2010; Wright 1977).

Description of the intervention

Dental floss

The concept of interdental cleaning with a filamentous material was first introduced by Levi Spear Parmly, as a measure for preventing dental disease together with a dentifrice and toothbrush (Parmly 1819). Unwaxed silk floss was first produced in 1882, by Codman & Shurtleff, but it was Johnson & Johnson who made silk floss widely available from 1887, as a by‐product of sterile silk leftover from the manufacture of sterile sutures (Johnson).

Certain organisations, for example the American Dental Association, recommend that children’s teeth are flossed as soon as they have two teeth that touch. However, studies that measure compliance show that few children have their teeth flossed or use floss: a study in West Virginia found that only 21% of children had their teeth flossed (Wiener 2009). When measures are taken to increase compliance, for example using behavioural change techniques, then the proportion of adolescent flossing increases (Gholami 2015).

Since dental floss is able to remove some interproximal plaque (Asadoorian 2006; Waerhaug 1981), it is thought that frequent regular dental flossing will reduce the risk of periodontal disease and interproximal caries (Hujoel 2006). Daily dental flossing in combination with toothbrushing for the prevention of periodontal disease and caries is frequently recommended (Bagramian 2009; Brothwell 1998). However, patient compliance with daily dental flossing is low (Schuz 2009). Patients attribute their lack of dental flossing compliance to lack of motivation and difficulties using floss (Asadoorian 2006). A study of a cohort of young people at ages 15, 18 and 26 found that at age 26, only 51% of both females and males believed that using dental floss was important, with females rating flossing more important than males (Broadbent 2006).

Interdental brushes

Interdental brushes are small cylindrical or cone‐shaped bristles on a thin wire that may be inserted between the teeth. They have soft nylon filaments aligned at right angles to a central stiffened rod, often twisted stainless steel wire, very similar to a bottle brush. Interdental brushes used for cleaning around implants have coated wire to avoid scratching the implants or causing galvanic shock. They are available in a range of different widths to match the interdental space and their shape can be conical or cylindrical. Most are round in section, although interdental brushes with a more triangular cross‐section can also be found in the market. Originally, interdental brushes were recommended by dental professionals to patients with large embrasure spaces between the teeth (Slot 2008; Waerhaug 1976), caused by the loss of interdental papilla mainly due to periodontal destruction. Patients who had interdental papillae that filled the embrasure space were usually recommended to use dental floss as an interdental cleansing tool. However, with the greater range of interdental brush sizes and cross‐sectional diameters now available, they are considered a potentially suitable alternative to dental floss for patients who have interdental papillae that fill the interdental space (Imai 2011). Daily dental flossing adherence is low among patients because it requires a certain degree of dexterity and motivation (Asadoorian 2006), whereas interdental brushes have been shown as being easier to use and are therefore preferred by patients (Christou 1998; Imai 2010). Furthermore, when compared to dental floss, they are thought to be more effective in plaque removal because the bristles fill the embrasure and are able to deplaque the invaginated areas on the tooth and root surfaces (Bergenholtz 1984; Christou 1998; Imai 2011; Jackson 2006; Kiger 1991; Waerhaug 1976). However, there are conflicting study results regarding the efficacy of interdental brushes in the reduction of clinical parameters of gingival inflammation (Jackson 2006; Noorlin 2007); and whether they are only suitable for patients with moderate to severe attachment loss and open embrasures, or whether they are a suitable aid for healthy patients to prevent gingivitis who have sufficient interdental space to accommodate them (Gjermo 1970; Imai 2011).

Tooth cleaning sticks

Sticks and twigs, composed of bone, ivory, metal, plastic, quills, wood and other substances, have been used for cleaning tooth surfaces and interdentally since prehistoric times (Christen 2003). The continuing use of hard materials for cleaning interdentally has been questioned (Mandel 1990); however, they continue to be used in different parts of the world. The meswak (or miswak) is one of the most widely used tooth cleaning sticks (Saha 2012), however it is important to differentiate its use between cleaning tooth surfaces and interdentally (Furuta 2011). Toothpicks continue to be used, particularly in the United States and Scandinavia, predominantly in older age groups (Sarner 2010), whereas dental floss and interdental brushes are more likely to be used by younger people. Toothpicks are commonly used in East Asia such as in China, Korea and Japan, though the main purpose is to remove food debris in the interdental areas. Interdental rubber tip stimulators, usually consisting of a carrying handle and disposable rubber tip stimulator, are readily available and are designed to stimulate gingival blood flow and remove interdental plaque.

Oral irrigators

Oral irrigation with water under pressure has been available for just over fifty years (Lyle 2012), and the benefits are described as the removal of biofilm from tooth surfaces and bacteria from periodontal pockets. Oral irrigators were first designed to be used supragingivally, using water pressure to displace and remove plaque, relying on pressure to irrigate subgingival regions (Goyal 2012). Since then, various tips have been designed that may be used subgingivally and several manufacturers provide products to do this.

How the intervention might work

Periodontal diseases

Gingival diseases are classified as one of the periodontal diseases (Armitage 1999), and are categorised as either dental plaque‐induced diseases or non‐plaque‐induced gingival lesions. Gingival inflammation, gingivitis, induced by dental plaque is an inflammatory response of the gingival tissues caused by bacteria in dental plaque (Page 1986), and characterised by swelling, redness and bleeding on probing. If dental plaque is left in place for more than two weeks, then gingivitis will occur (Loe 1965). The severity of gingivitis can be modified by factors other than plaque (Trombelli 2013).

Periodontal diseases are complex interactions of bacteria and the immune system (Sanz 2011); and dental plaque is the primary aetiological factor (Marsh 2006). Dental plaque may be either supra‐gingival or sub‐gingival and the plaque biofilm comprises different bacterial colonies at the supra‐gingival or sub‐gingival levels.

Removal of dental plaque by mechanical interdental cleaning will remove the primary aetiological factor for gingivitis and periodontal disease.

Dental caries

Dental plaque contains many bacterial species which are acidogenic. In 1890, Miller published 'The microorganisms of the human mouth' which postulated that oral bacteria found in plaque were acidogenic, but as no specific bacteria were implicated it became known as the “non‐specific plaque hypothesis” (Ring 2002). Later, Loesche 1976 postulated a “specific plaque theory”, implicating Streptococcus mutans and Lactobacillus acidophilus as the primary bacteria involved in caries generation. Since then, the importance of the plaque biofilm has been recognised and an “ecological plaque hypothesis” proposed (Marsh 1994).

Acidogenic plaque bacteria utilise dietary sugars to demineralise dental tissues, which may progress into carious tooth lesions. The most susceptible regions of teeth to caries are the occlusal and interdental surfaces (Demirci 2010). Removal of dental plaque by mechanical interdental cleaning should reduce the frequency and degree of demineralisation interproximally and lead to decreased caries incidence.

Why it is important to do this review

Mechanical interdental cleaning, using either dental floss, interdental brushes or tooth cleaning sticks are widely recommended and advertised for interdental cleaning. It is unclear whether there is a benefit in mechanical interdental cleaning as an adjunct to toothbrushing and if a particular type of interdental cleaning is superior to others. Also, it is unknown what the benefits may be for children and adolescents.

A systematic review and meta‐analysis, combining the results of randomised controlled trials, will provide health care commissioners, practitioners and consumers with evidence about the effectiveness of mechanical interdental cleaning on oral health.

This review, which includes the previous reviews on flossing (0245) and interdental brushing (0257), was considered to be a clinically important topic to maintain on T he Cochrane Library when the prioritisation exercise was undertaken by the Cochrane Oral Health Group.