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Dental floss as an adjuvant of the toothbrush helps gingival health


Design and aim This randomised controlled clinical trial assessed the efficacy of using dental floss in addition to toothbrushing in reducing gingival and plaque indices.

Intervention The participants received oral hygiene instruction and supervised personal and professional plaque removal every week for two months. The research team instructed the participants to perform toothbrushing twice daily - groups 'toothbrushing and flossing' (TB + DF) and 'toothbrushing alone' - and use dental floss once daily - group TB + DF. Gingival index (GI) and plaque idex (PI) were evaluated at baseline and after one and two months.

Case selection The authors invited the participants via the Federal University of Santa Maria screening service, social media and public posters. The participants were 18 years and older, without interproximal clinical attachment loss, with papillae completely filling the interproximal space and with at least 24 teeth remaining. The participants were included if they had a gingival index score of two at more than 15% of the interproximal sites. The authors excluded dental students, patients with xerostomia or diabetes, pregnant women, smokers, patients with orthodontic appliances and restraints, patients requiring antimicrobial prophylaxis, patients having used antibiotics/anti-inflammatory agents within the last three months and those with psychomotor disorders.

Experimental groups and data analysis The authors used a block randomisation sequence with block sizes of ten. Randomisation confidentiality was maintained using serially sealed, numbered, opaque envelopes. At baseline, all the participants received oral prophylaxis and their GI, probing depth (PD), clinical attachment loss (CAL) and bleeding on probing (BOP) were assessed. A clinical staff member disclosed the experimental group assignments, distributed scheduled oral hygiene materials and conducted assigned study interventions. Each participant received a soft toothbrush (Colgate Twister Compact Head, New York, NY, USA) and fluoride dentifrice (Colgate Triple Action, 90 g, New York, NY, USA). Patients were instructed to brush their teeth twice daily. Subjects from the TB + DF group also received dental floss and were asked to use it once daily (Colgate, Tarpaulin, New York, NY, USA). The research team supervised the oral hygiene practices at day zero and recalled the patients to provide them with personalised oral hygiene instruction and dental plaque removal. Individual patients were considered as units of analysis. PI, GI, CAL, PD, gingival bleeding (GI = 2), BOP and percentage sites with different GI scores were presented as means, standard deviations and standard errors. The authors used multiple imputations to replace missing data and mixed linear models to analyse and compare the experimental groups.

Results In total, 75 participants were randomised. Both groups showed a significant reduction in gingival inflammation (GI = 2) in the first month, albeit no change was seen in the second month. Adding flossing to toothbrushing significantly reduced the GI = 2 by the end of the first month (37.7 to 15.9%), maintaining optimised overall oral health through day 60 (15.1%) compared with toothbrushing alone. No significant differences were noted between the two groups from the first to the second month. Interproximal dental plaque was reduced for both groups from baseline to day 30 with no marked change from then to day 60. Plaque reduction was similar in both groups.

Conclusions Toothbrushing reduces interdental plaque build-up and halts its progression while improving gingival health in adults with no interdental attachment loss. Dental flossing as an adjuvant to toothbrushing also enhances these benefits.

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  1. Wasserstein R L, Lazar N A. The ASA Statement on pValues: Context, Process, and Purpose. Am Stat 2016; 70: 129-133.

  2. Bosma M L, McGuire J A, Sunkara A et al. Efficacy of Flossing and Mouthrinsing Regimens on Plaque and Gingivitis: A randomized clinical trial. J Dent Hyg 2022; 96: 8-20.

  3. Hujoel P P, Cunha-Cruz J, Banting D W, Loesche W J. Dental flossing and interproximal caries: a systematic review. J Dent Res 2006; 85: 298-305.

  4. Sambunjak D, Nickerson J W, Poklepovic T et al. Flossing for the management of periodontal diseases and dental caries in adults. Cochrane Database Syst Rev 2011; DOI: 10.1002/14651858.CD008829.pub2.

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Shamsoddin, E. Dental floss as an adjuvant of the toothbrush helps gingival health. Evid Based Dent 23, 94–96 (2022).

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