Mechanical Cleaning Work

Why doesn’t mechanical cleaning work as well as it should?

Mechanical cleaning with a toothbrush and floss/interdental cleaning is a mainstay of patient self-care and such techniques are the best way for a patient to remove plaque, and yet more than 60% of the population still has visible plaque.1

Plaque is often left behind after brushing/interdental cleaning due to:
• Inaccessibility of hard-to-reach areas2,3
• Inadequate technique2–4
• Implants, crowns, braces, etc, may hamper mechanical efforts5,6
• Patient may have limited dexterity7
• Lack of motivation5,7
• Lack of time2,7
• Loss of patient motivation over time2
• Loss of patient compliance over time2

The dental literature contains various reports of the efficacy of mechanical plaque removal. A systematic review of manual toothbrushing found that "The efficacy in plaque removal following a brushing exercise is a reduction from baseline plaque scores of 42% on average, with a variation of 30–53% dependent on the plaque index used". The mean reductions in plaque by brushing duration were only 27% after 1 minute, rising to 41% after 2 minutes.8 A Cochrane review of powered brushing found that powered toothbrushes with a rotation oscillation action reduce plaque and gingivitis more than manual toothbrushing. At 1 to 3 months, an 11% difference in the plaque index and a 6% reduction on gingival index was observed.9

The data is less clear on flossing and other interdental cleaning methods. A 2008 review found that the greater part of the studies considered did not show a benefit for flossing on plaque and clinical parameters of gingivitis.10 A Cochrane study from 2011 found that there was some evidence from 12 studies that flossing, in addition to toothbrushing reduces gingivitis versus brushing alone. 11 Adding interdental brushes to toothbrushing alone removes more plaque than adding floss.12 Woodsticks have been shown to reduce interdental bleeding, but without an effect on visible interdental plaque or gingival index.13 Generally, the effectiveness of most interdental cleaning methods is limited by the ability and motivation of the patient, rather than by the method itself.

Even well-trained patients may miss hard-to-reach areas at the back of the mouth or near the gumline. Elderly patients, those with physical or mental limitations, and those with malpositioned teeth, bridgework or orthodontic appliances may find flossing especially difficult.2–6 It can be concluded that mechanical plaque control is not a complete solution. Indeed, "... inherent problems exist in all attempts to educate, train, and motivate patients to achieve reduction of plaque solely by mechanical means."7

For the above reasons, chemotherapeutic agents may have a key role as adjuncts to mechanical methods for preventing and treating periodontal disease.7


  1. Chadwick B et al. 5: Preventive behaviour and risks to oral health - a report from the Adult Dental Health Survey 2009. NHS. The Health and Social Care Information Centre. 2011.
  2. Santos A. Evidence-based control of plaque and gingivitis. J Clin Periodontal 2003; 30(Suppl. 5): 13–16.
  3. Warren PR, Chater BV. An overview of established interdental cleaning methods. J Clin Dent 1996; 7(3 Spec No): 65–69.
  4. Lang WP at al. The relation of preventive dental behaviors to periodontal health status. J Clin Periodontol 1994; 21: 194–198.
  5. American Academy of Periodontology - Research, Science, and Therapy Committee. Treatment of plaque-induced gingivitis, chronic periodontitis, and other clinical conditions. American Academy Of Pediatric Dentistry 2004; 34(6): 317–326.
  6. Ciancio SG. Use of mouthrinses for professional indications. J Clin Periodontol 1988; 15: 520–523.
  7. DePaola LG et al. Chemotherapeutic inhibition of supragingival dental plaque and gingivitis development. J Clin Periodontol 1989; 16: 311–315.
  8. Slot DE et al. The efficacy of manual toothbrushes following a brushing exercise: a systematic review. Int J Dent Hygiene 2012; 10: 187–197.
  9. Robinson PG et al. Manual versus powered toothbrushing for oral health. Cochrane Database Syst Rev 2005; 18(2): CD002281.
  10. Berchier CE et al. The efficacy of dental floss in addition to a toothbrush on plaque and parameters of gingival inflammation: a systematic review. Int J Dent Hyg 2008; 6(4): 265–279.
  11. Sambunjak D et al. Flossing for the management of periodontal diseases and dental caries in adults. Cochrane Database Syst Rev 2011; 7(12): CD008829.
  12. Slot DE et al. The efficacy of interdental brushes on plaque and parameters of periodontal inflammation: a systematic review. Int J Dent Hyg 2008; 6(4): 253–264.
  13. Hoenderos NL et al. The efficacy of woodsticks on plaque and gingival inflammation: a systematic review. Int J Dent Hyg 2008; 6(4): 280–289.