Update on Methods for Oral Biofilm Disruption

Biofilms are composed of bacteria adhering to each other or to living or nonliving surfaces. They form complex communities surrounded by extracellular polymeric substances.¹ Cells within these biofilms have changing physiologic and metabolic properties that contribute to their persistence.¹ If not removed regularly, a complex and mature biofilm develops, with up to 100 bacterial species at a single site.² Oral biofilm exposed to an excess of carbohydrates contains mainly Gram-positive carbohydrate-fermenting bacteria that may cause demineralization, caries, pulpitis, and periodontitis.^2–4 Supra- and subgingival oral biofilms dominated by Gram-negative anaerobic bacteria colonize and cause gingival inflammation. Subsequently, gingivitis, chronic and aggressive periodontitis, and peri-implantitis can ensue.^2,3 There are two strategies for biofilm control: interfere with attachment, and remove or disrupt biofilm. Total removal is not possible;¹ therefore, disruption is the most practical option.⁴

TOOTHBRUSHING

Toothbrushing is the most powerful way to disrupt supragingival biofilm at home, preventing colonization of microbes subgingivally. Research shows that both manual toothbrushing and power toothbrushing result in a reduction of plaque scores.^5,6 Many types of manual toothbrushes are available. Results of randomized controlled trials found no difference in plaque removal between different types of manual toothbrushes,^7,8 and all manual toothbrushes were efficacious.⁷ A systematic review is needed to investigate the effects of filament texture and arrangement on plaque, gingivitis, and adverse events.⁹

Power toothbrushes have different modes of action to improve efficacy, such as sonic, ultrasonic, rotating, counter-oscillating, oscillating rotation, back and forth, and side to side.^6,10 Systematic reviews found that power and manual brushing are at least equally effective in removing plaque, reducing gingival inflammation,^11–13 and preventing calculus formation.¹² The key to an effective power toothbrush is the presence of a moving brush head.⁶ Both vertical and horizontal methods are effective in biofilm removal; however, one study found that the vertical method removed more plaque from the interproximal surfaces and produced lower plaque scores than the horizontal method.¹⁴ This finding is noteworthy because this clinical trial looked at brushing in regard to interproximal effectiveness.

Duration of brushing remains a key factor in efficacy of biofilm removal. After 2 minutes of brushing, a 41% reduction in plaque scores was found compared with only a 21% reduction after 1 minute of brushing.⁵ For gingivitis prevention, brushing at least 2 minutes twice per day with fluoride toothpaste was supported for all patient populations, while 2 minutes was found to be insufficient for patients with periodontitis.⁹

ANTIBACTERIAL DENTIFRICES

Toothbrushing provides the main mechanical effect of plaque removal, not toothpaste.¹⁵ However, adding antibacterial ingredients within dentifrice is helpful for biofilm management. When combined with fluoride (for caries prevention), antibacterial pastes provide an efficacious option for combating oral diseases.

Stannous fluoride has antibacterial effects against species associated with plaque, gingivitis, caries, and malodor, and it reduces plaque, gingival inflammation, and bleeding.¹⁶ Stannous fluoride and sodium hexametaphosphate inhibit calculus and stain formation.¹⁶

Triclosan/copolymer fluoride dentifrices re­duced gingival inflammation and gingival bleeding when compared with conventional fluoride dentifrices. Also, high-quality evidence demonstrated that the use of triclosan/copoly­mer fluoride dentifrices led to a small reduction in coronal caries, while weaker evidence demonstrated its effectiveness in decreasing root caries and calculus.¹⁷

INTERDENTAL AIDS

Brushing alone does not significantly disrupt biofilm from proximal surfaces, therefore, patients should be educated about interdental self-care. In fact, interdental biofilm is more prevalent, acidogenic, and readily forming than other oral biofilm.¹⁸ Evaluation of patients’ interdental space accessibility should be part of all routine oral examinations.¹⁹

Floss does not meet the intraoral and personal needs of all patients. Also, compliance with daily flossing is low.^20,21 Nevertheless, dental floss is ideal for those who can use it effectively and patients with type I gingival embrasure spaces and shallow pockets. Conversely, open embrasures and recession may be best treated with interdental brushes.

Flossing in addition to toothbrushing enhances interproximal biofilm disruption by 70% compared with 25% by brushing alone.⁸Although the quality of evidence about flossing’s efficacy is low, regular flossing with toothbrushing is effective in preventing gingivitis.²² Floss with 5% CHX resulted in additional reductions in supragingival biofilm when compared with waxed floss on the anterior teeth of a well-motivated and well-instructed popu­lation.²³ It would be useful for future studies to focus on antimicrobials in floss for the general population to assess if regular use would be valuable.

Interdental brushes come in different widths to match a patient’s interproximal anatomy. Brushes for use around implants have a coated wire to avoid scratching and prevent galvanic shock. In general, interdental brushes as an adjunct to toothbrushing are more effective in removing plaque compared with brushing alone.^24–26

Patients should approach the interdental space from both the buccal and lingual aspects to adequately disrupt the biofilm, particularly with spaces that are partially occluded with gingiva. Flexible interdental cleaners with rubber bristles are effective when compared with other interdental brushes and may offer increased patient comfort when compared with metal-core brushes.²⁷

Few studies have looked at the efficacy of wood sticks on oral biofilm removal, periodontal diseases, or caries. A systematic review about triangular wood sticks in addition to toothbrushing showed no effect on plaque or gingival indexes.²⁸ The review did find, however, an advantage in reducing interdental gingival bleeding.²⁸ Wood sticks may be a viable alternative for patients who have not had success with other interdental aids.

ORAL IRRIGATORS 

Oral irrigation can be used for supragingival or subgingival biofilm disruption or both, and with water alone or an antimicrobial. Two systematic reviews revealed that while the oral irrigator and toothbrushing did not reduce visible plaque biofilm, their use did improve gingival health.^29,30 It may be that irrigation alters the composition of key pathogens, interferes with biofilm maturation, or changes the subgingival microbial environment due to the pulsating action.³¹ These effects are worth future investigation. Oral irrigators may be well suited for site-specific concerns, such as crowns, malocclusion, or other localized areas where persistent inflammation exists. In regard to implant care, CHX irrigation was found to be more effective in reducing biofilm and marginal bleeding scores when compared with rinsing with CHX alone.³²

Water flossing is a relatively new term to de­scribe oral irrigation. Results of two studies found the water flosser to be more effective than interdental brushes in removing plaque biofilm after a single use,³³ and in reducing gingival bleeding over 2 weeks.³⁴ Although these results are limited in scope, they do show promise for water flossing’s efficacy.

MOUTHRINSES

Evidence supports the use of antimicrobial mouth­rinses in addition to mechanical biofilm disruption for most patients. These antiseptic rinses act on the oral biofilm’s ability to form, grow, and mature.³⁵ In fact, toothbrushing in combination with any CHX mouthrinse was more effective than toothbrushing alone in biofilm reduction.³⁶

Evidence supports the efficacy of CHX and essential oils (EO).^36–39 Benefits for plaque and gingivitis were also shown with cetylpyridinium chloride (CPC).³⁹ Patients with orthodontic appliances, mental or physical disabilities, systemic diseases, and smokers may particularly benefit from antimicrobial mouthrinse use.

CHX is an effective antimicrobial that has positive implications for both caries and gingivitis. CHX is active against Gram-positive and Gram-negative bacteria, yeasts, and viruses, and is bacteriostatic vs bactericidal.⁴⁰ CHX mouthrinse is released slowly, has sustained release, and remains in the oral cavity for extended periods. It, therefore, has the ability to adsorb to oral mucosa, hydroxyapatite, and salivary glycoprotein. CHX mouthrinses are now formulated without alcohol.

EOs have been used as antimicrobials in mouth­rinses for many years, and have been shown to have anti-plaque and anti-gingivitis properties. They are easy to use and purchase (no prescription needed) and there is no residual staining, as is the case with
CHX.^41–43

While not an antimicrobial, delmopinol hydro­chloride inhibits plaque and bacteria formation on the tooth surface.⁴⁴ Other mouth­rinse ingredients, such as chitosan-argininamide, tea tree oil, peppermint oil, lemon peel oil, and aloe vera, may provide benefits but more research is needed.

MECHANICAL DEBRIDEMENT

Mechanical biofilm disruption by the professional occurs both in the supragingival (oral prophylaxis/debride­ment) and the subgingival environment (scaling and root planing/debridement). Mechanical debridement of the subgingival environment remains the cornerstone of periodontal therapy. Although not a permanent solution to biofilm removal, mechanical therapy temporarily disrupts its aggregation. The American Dental Association’s (ADA) Evidence-Based Clinical Practice Guidelines on Nonsurgical Treatment of Chronic Periodontitis supports scaling and root planing as the initial nonsurgical treatment for chronic periodontitis.⁴⁵

Scaling, debridement, root planing, and polishing all mechanically disrupt biofilm, which is absolutely necessary to prevent and treat biofilm-induced infections. Although calculus and calculus-retaining entities (overhangs) are not causative factors in inflammatory diseases, they do provide the niche necessary to harbor oral biofilms.⁴⁶ Furthermore, removing only the superficial biofilm, and leaving calculus deposits underneath likely contributes to biofilm regrowth. The remaining deposit provides a niche for biofilm reformation in a rough and stagnant environment.

Burnished calculus deposits might attract oral biofilm and perpetuate inflammation.⁴⁶ Use of the dental endoscope has aided in discovering the relationship between subgingival calculus covered with biofilm and inflammation of adjacent tissue.⁴⁷ In fact, a strong correlation has been noted between bleeding on probing and subgingival biofilm and calculus post-scaling and root planing.⁴⁸

Nonsurgical anti-infective periodontal therapy is another name for reducing biofilm via mechanical means of scaling and root planing.⁴⁹ Unfortunately, nonsurgical periodontal therapy sometimes produces unfavorable results or fails where deep pockets and furcations are involved.⁵⁰ However, moderate and shallow pockets have been effectively treated with mechanical debridement by disrupting and removing oral biofilms and removing calculus and other retaining entities.^50,51

The outcomes of mechanical debridement in multirooted teeth are less favorable than single-rooted teeth.⁵² An update of periodontal therapy outcomes shows, however, that positive long-term survival rates can be accomplished in multirooted teeth based on the therapy provided.⁵³ Initial furcations (degree I) can be successfully managed by nonsurgical mechanical debridement.⁵³ 

The use of hand and power instrumentation provides similar clinical outcomes.⁵⁴ Determining which type of mechanical debridement is best depends on myriad factors such as time spent, expertise, new vs experienced operators, experience with specific instruments, instrument selection, etc. Most likely, the optimal means of mechanical debridement is the combined use of hand and power instruments.⁵⁵

A key to subgingival biofilm disruption is reevaluation and subsequent assessment of disease conditions at recare visits. These are the means by which a clinician decides, over time, when and if the root has been biologically well prepared for healing. This point of stability is different from patient to patient. The clinician’s responsibility is to determine a clinical endpoint during the mechanical debridement appointment(s) and a therapeutic endpoint at the reevaluation visit and recare appointments.⁵⁶ The addition of a dental endoscope has been shown to enhance mechanical debridement by improving the removal of subgingival calculus and healing of the periodontium.^57–60

An objective in mechanical periodontal therapy is to leave the root smooth without unnecessarily removing healthy root surface. A smooth root is thought to lend itself to less bacterial recolonization over time. When comparing instruments, curets, diamond burs, piezoceramic (used in scaling and root planing only), and piezosurgery ultrasonic instruments (used in bone surgery and root planing) in vitro, it was found that all reduced roughness of the root, however, the piezosurgery ultrasonic produced the smoothest surface.⁶¹When comparing a new sonic, piezoceramic, and double Gracey curet instruments, it was concluded that all were effective in root debridement during maintenance, and the ultrasonic resulted in the smoothest root surfaces.⁶²

CONCLUSION

Regular personal and professional biofilm removal is key to preventing and treating oral infections.² A single assault on biofilm, however, is not likely to achieve control; rather multiple strategies are needed for each individual patient (Figure 1). It is important to combine the scientific evidence, professional judgment, and patient needs to provide the best treatment and recommendations for biofilm disruption.

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From Dimensions of Dental Hygiene. December 2017;15(12):35-37.