Abstract: We included two studies with 1711 participants in the analyses. Both studies were conducted in UK general dental practices and involved adults without severe periodontitis who were regular attenders at dental appointments. One study measured outcomes at 24 months and the other at 36 months. Neither study measured adverse effects, changes in attachment level, tooth loss or halitosis. Comparison 1: routine scaling and polishing versus no scheduled scaling and polishing Two studies compared planned, regular interval (six- and 12-monthly) scale and polish treatments versus no scheduled treatment. We found little or no difference between groups over a two- to three-year period for gingivitis, probing depths, oral health-related quality of life (all high-certainty evidence) and plaque (low-certainty evidence). The SMD for gingivitis when comparing six-monthly scale and polish treatment versus no scheduled treatment was –0.01 (95% CI –0.13 to 0.11; two trials, 1087 participants), and for 12-monthly scale and polish versus no scheduled treatment was –0.04 (95% CI –0.16 to 0.08; two trials, 1091 participants). Regular planned scale and polish treatments produced a small reduction in calculus levels over two to three years when compared with no scheduled scale and polish treatments (high-certainty evidence). The SMD for six-monthly scale and polish versus no scheduled treatment was –0.32 (95% CI –0.44 to –0.20; two trials, 1088 participants) and for 12-monthly scale and polish versus no scheduled treatment was –0.19 (95% CI –0.31 to –0.07; two trials, 1088 participants). The clinical importance of these small reductions is unclear. Participants' self-reported levels of oral cleanliness were higher when receiving six- and 12-monthly scale and polish treatments compared to no scheduled treatment, but the certainty of the evidence is low. Comparison 2: routine scaling and polishing at different recall intervals Two studies compared routine six-monthly scale and polish treatments versus 12-monthly treatments. We found little or no difference between groups over two to three years for the outcomes of gingivitis, probing depths, oral health-related quality of life (all high-certainty evidence) and plaque (low-certainty evidence). The SMD for gingivitis was 0.03 (95% CI -0.09 to 0.15; two trials, 1090 participants; I2 = 0%). Six- monthly scale and polish treatments produced a small reduction in calculus levels over a two- to three-year period when compared with 12-monthly treatments (SMD –0.13 (95% CI –0.25 to –0.01; 2 trials, 1086 participants; high-certainty evidence). The clinical importance of this small reduction is unclear. The comparative effects of six- and 12-monthly scale and polish treatments on patients' self-reported levels of oral cleanliness were uncertain (very low-certainty evidence). Comparison 3: routine scaling and polishing provided by dentists compared with dental care professionals (dental therapists or hygienists) No studies evaluated this comparison. The review findings in relation to costs were uncertain (very low-certainty evidence). For adults without severe periodontitis who regularly access routine dental care, routine scale and polish treatment makes little or no difference to gingivitis, probing depths and oral health-related quality of life over two to three years follow-up when compared with no scheduled scale and polish treatments (high-certainty evidence). There may also be little or no difference in plaque levels over two years (low-certainty evidence). Routine scaling and polishing reduces calculus levels compared with no routine scaling and polishing, with six-monthly treatments reducing calculus more than 12-monthly treatments over two to three years follow-up (high-certainty evidence), although the clinical importance of these small reductions is uncertain. Available evidence on the costs of the treatments is uncertain. The studies did not assess adverse effects.

Plain-language summary: We included two studies with a total of 1711 participants in our review. Both studies involved adults without severe periodontitis who were regular attenders at dental appointments in the UK. The studies were conducted in general dental practices, which is the most appropriate setting to evaluate 'routine scale and polish' treatments. One study measured outcomes at 24 months and one study at 36 months. The studies found little or no difference between regular planned scale and polish treatments compared with no scheduled scale and polish for the early signs of gum disease (gingivitis or bleeding gums; plaque deposits; and probing depths or gum pockets). There was a small reduction in calculus (tartar) levels, but it was uncertain if this is important for patients or their dentists. Participants receiving six-monthly and 12-monthly scale and polish treatments reported feeling that their teeth were cleaner than those who were scheduled to receive no treatment. However, there did not seem to be a difference between groups in terms of quality of life. Available evidence on the costs of the treatments was uncertain. Neither of the studies measured side effects (such as damage to tooth surfaces and tooth sensitivity), changes in attachment level, tooth loss or halitosis (bad breath). Neither study compared scale and polish treatments provided by different professionals, e.g. dentists, dental therapists and hygienists. We judged the certainty of the evidence to be high for gingivitis, probing depths, calculus and quality of life, but low for plaque, and low to very low for patient perception of oral cleanliness. The certainty of evidence for costs was very low. The high-certainty evidence for gingivitis means that we can be confident that routine scale and polish does not significantly reduce the signs of mild gum disease when measured up to three years.