Design A multi-centre, parallel-group, randomised controlled trial with blinded clinical outcome assessment. Participants were randomised to receive a dental check-up at six-monthly, 24-monthly or risk-based recall intervals. A two-strata trial design was used, with participants randomised within the 24-month stratum if the recruiting dentist considered them clinically suitable. Participants ineligible for 24-month recall were randomised to a risk-based or six-month recall interval.
Setting UK primary dental care.
Participants Practices providing NHS care and adults who had received regular dental check-ups.
Main outcome measures The percentage of sites with gingival bleeding on probing, oral health-related quality of life (OHRQoL), cost-effectiveness.
Results In total, 2,372 participants were recruited from 51 dental practices. Of those, 648 were eligible for the 24-month recall stratum and 1,724 participants were ineligible. There was no evidence of a significant difference in the mean percentage of sites with gingival bleeding on probing between intervention arms in any comparison. For those eligible for 24-month recall stratum: the 24-month versus six-month group had an adjusted mean difference of -0.91%, 95% CI (-5.02%, 3.20%); the 24-month group versus risk-based group had an adjusted mean difference of 0.07%, 95% CI (-3.99%, 4.12%). For the overall sample, the risk-based versus six-month adjusted mean difference was 0.78%, 95% CI (-1.17%, 2.72%). There was no evidence of a difference in OHRQoL (0-56 scale, higher score for poorer OHRQoL) between intervention arms in any comparison. For the overall sample, the risk-based versus six-month effect size was -0.35, 95% CI (-1.02, 0.32). There was no evidence of a clinically meaningful difference between the groups in any comparison in either eligibility stratum for any of the secondary clinical or patient-reported outcomes.
Conclusion Over a four-year period, we found no evidence of a difference in oral health for participants allocated to a six-month or a risk-based recall interval, nor between a 24-month, six-month or risk-based recall interval for participants eligible for a 24-month recall. However, patients greatly value and are willing to pay for frequent dental check-ups.
We would like to acknowledge the participating dental practice teams and patients without whose valuable contribution this study could not have taken place. The Health Services Research Unit and the Health Economics Research Unit are funded by the Chief Scientist Office of the Scottish Government Health and Social Care Directorates. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health. Ethics approval for the trial was given by the Fife and Forth Valley Research Ethics Committee on 13 January 2009 and 20 September 2011 (Research Ethics Committee reference 09/SO501/1). The trial was registered with the ISRCTN (reference number ISRCTN95933794).
None to disclose. This trial was funded by the NIHR HTA programme [project numbers 06/35/05 (Phase I) and 06/35/99 (Phase II)].