Ramsay 2018.

Methods	Trial design: parallel (6 arms) Location: general dental practices in Scotland and the North East of England Number of centres: 63 Study Duration: participants recruited between Febrruary 2012 and March 2013 with a 3‐year follow‐up
Participants	Participants: adults attending National Health Service general dental practices in Scotland and the North East of England Inclusion criteria: adult patients (≥ 18 years of age) with periodontal health, gingivitis or moderate periodontitis (Basic Periodontal Examination (BPE) score 0 to 3) who are dentate; have attended for a check‐up at least twice in the previous 2 years; and receive their dental care in part or fully as a National Health Service patient Exclusion criteria: patients with severe periodontal disease with a BPE score of 4 (probing depth > 6 mm and/or furcation involvements or attachment loss of 7 mm or more) in any sextant on the basis more extensive periodontal care is indicated. Patients with an uncontrolled chronic medical condition (e.g. diabetes, immunocompromised) Age at baseline (years): intervention group: mean 47.4 years (SD 16.1); control group: mean 48.3 years (SD 15.3) Gender: intervention group: 387 males (38%), 321 females (62%); control group: 290 males (33%), 576 females (67%) Number randomised: 1877 participants Number evaluated: 1237 participants
Interventions	Intervention: personalised OHA: "Personalised OHA intervention based upon Social Cognitive Theory (Bandura 1998) and Implementation Intention Theory (Gollwitzer 1999) was delivered. The content of the advice delivered was personalised according to the dentist's/hygienist's assessment of the needs of the patient. At a minimum the content included advice and instruction in self‐diagnosis (e.g. bleeding gums on brushing indicates the presence of reversible gingival inflammation) and advice and instruction on toothbrushing and flossing (frequency and technique). Upon completion of the advice, the dentist agreed an action plan with the patient. The feasibility and utility of including personalised biofeedback (Chapple 2008) in the personalised OHA intervention was considered by the research team and the Periodontal Advisory Group." "In addition, the Control and Intervention groups were further randomised at patient‐individual randomisation level to no periodontal instrumentation (PI), 6 monthly PI or 12 monthly PI" Control: routine OHA: "Routine OHA indicates current practice. There is no published information describing 'routine' OHA, but anecdotal evidence suggests that this is often the provision of minimal advice (e.g. 'you need to brush your teeth more frequently' or no advice)" Prophylaxis provided: at baseline all patients received OHA according to cluster level randomisation. A full mouth supra‐ and subgingival PI was carried out by the dentist/hygienist on all participants prior to randomisation. No time limit was set on this treatment and dentists/hygienists were instructed to scale the teeth and root surfaces until they were free of all deposits and smooth to probing Member of dental team delivering intervention: dentist or hygienist Frequency of intervention: reinforcement of OHA was provided at the discretion of the dentist/hygienist during the trial and recorded Intensity of intervention (length of time): no information available Setting: primary care setting Disease level: periodontal health, gingivitis or moderate periodontitis (Basic Periodontal Examination (BPE) score 0 to 3)
Outcomes	The primary clinical outcome was inflammation at the gingival margin measured by running a University of North Carolina probe circumferentially around each tooth just within the gingival sulcus or pocket (gingival index of Löe (Löe 1967)). After 30 seconds, bleeding was recorded as being present or absent on the buccal and lingual surface and reported as the percentage of sites (twice the number of teeth) with bleeding. Oral hygiene self‐efficacy was measured on a 1 to 7 scale with 7 being extremely confident Economic net benefits were calculated as mean willingness to pay for services and outcomes (obtained from a general population discrete choice experiment) minus mean health service perspective costs Secondary outcomes were calculus and clinical probing depth, patient‐reported dental quality of life (OHIP‐14) (Slade 1997), oral health behaviour and intention, additional private scale and polish treatments, referral and having a plan for better self‐care. Providers' beliefs relating to providing OHA and maintenance of periodontal health were collected at 3 years
Notes	Funding: "Funded by the Health Technology Assessment Programme of the National Institute for Health Research, Current Controlled Trials number ISRCTN56465715" Sample size calculation: "Oral health advice (OHA): to calculate the sample size required to estimate the main effect of OHA, it is recognised that the data are contained within a cluster RCT. Assuming a conservative estimate of the intracluster correlation (ICC) of 0.0531, a cluster RCT of 50 dentists collecting information from 25 patient participants each (25*25 = 625 patients per arm) will have 90% power to detect a difference of 7.5%. Should the correlation be 0.1, the trial will still have approximately 80% power to detect a difference of 7.5%" Adverse effects: none reported Declarations/conflicts of interest: all authors declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous 3 years; no other relationships or activities that could appear to have influenced the submitted work
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "A computer‐generated randomization system was used and managed by the Centre for Healthcare Randomised Trials (CHaRT), University of Aberdeen, UK. Both dentist and patient participants underwent randomization with even allocation. The minimization algorithms for the practice allocation were, employs dental hygienist (yes/no) and has 3 or more dentists (yes/no), and for patient allocation absence of gingival bleeding on probing (yes/no), highest BPE score 3 (yes/no) and current smoking (yes/no)"
Allocation concealment (selection bias)	Low risk	Quotes: "Dentist allocation to OHA group: recruited dentists will be allocated to routine or personalised OHA by minimisation on 2 factors ‐ (i) practice employs dental hygienist (yes/no) and (ii) practice size (2 or less dentists in practice/3 or more dentists)" and "Patient participant allocation to PI group: allocation will take place once the outcome assessor has completed the baseline outcome assessment and will be minimised on (i) absence of gingival bleeding on probing (yes/no), (ii) highest sextant BPE score (BPE less than 3/BPE 3) and (iii) current smoking (yes/no)"
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Quotes: "Both dentist and patient participants underwent randomization with even allocation. The minimization algorithms for the practice allocation were, employs dental hygienist (yes/no) and has 3 or more dentists (yes/no), and for patient allocation absence of gingival bleeding on probing (yes/no), highest BPE score 3 (yes/no) and current smoking (yes/no);" "This is a 5‐year multicentre, randomized, open trial with blinded outcome evaluation" and "Patient participant allocation to PI group...... A letter will be sent to patient participants to inform them of their trial group allocation and the practice will be contacted by the TCOD to arrange the first intervention appointment" Comments: study reported as evaluator blinded however personnel delivering intervention would know group allocation. Blinding of participants was not possible; it is unclear the influence this would have on the risk of bias for this domain
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "Clinical outcomes were recorded by blinded assessors at baseline and 3 years. Outcome assessor training was provided to ensure intra‐ and interassessor alignment"
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "Attendance (70%) at the 3‐year clinical examination and return of the final questionnaire (75%) was balanced across groups" Comment: all participants accounted for and reported on
Selective reporting (reporting bias)	Low risk	All outcomes in methods section were reported
Other bias	Low risk	No apparent other bias