Study design: Randomised controlled three-arm parallel clinical trial set in general dental practice.
Intervention: Three hundred and sixty-nine patients were recruited to the trial. To be included patients had to be regular attenders aged 18 to 60 years with 20 or more teeth and BPE codes <3 and DT<4. They were excluded if they wore an intra-oral applicance or had systemic conditions or used medication that could predispose to periodontal disease. Participants were randomised to have single-visit scale and polish at 6 month, 12 month or 24 month intervals and treatment was carried out by nine hygienists and therapists. Randomisation was performed centrally at a distant site by the trial manager and participants were not informed for their treatment allocation until they returned for their 6-month recall. Allocation was not explicitly revealed to the dentist, and participants were asked not to reveal their allocation group to the dentist or the outcome examiner.
Outcome measure: The primary outcome measure was presence of gingival bleeding. Secondary outcome measures were presence of plaque and presence and amount of calculus.
Results: Data were collected for 83.5% of the original participants and 76.2% attended all five appointments. There were no statistically significant differences in prevalence of gingival bleeding at follow-up for each group: 6-month recall group 78.5%; 12-month group 78% and 24-month group 82% (p=0.746). There were also no differences between groups at follow-up for prevalence of plaque and calculus.
Conclusions: This trial did not identify any differences in gingival health associated outcomes for single-visit scale and polish provided at 6-, 12- and 24-month frequencies for healthy patients. However, the results are not conclusive and larger trials with more comprehensive measurements are needed.