Why is this study being done? People with dental crowns often develop inflamed gums because bacteria accumulate in the tight spaces between teeth that a regular toothbrush cannot reach. Interdental brushes can clean these spaces, but patients frequently use them incorrectly. This study tested whether a personalised, hands-on instructional method called Touch-to-Teach produces healthier gums compared with standard dental hygiene advice.

Who participated? 40 adults with at least one porcelain-fused-to-metal crown in the molar region with supragingival margins took part at Thumbay University Hospital, Ajman, UAE. Four participants withdrew; 36 completed the three-month study.

What did participants do? All participants received full-mouth scaling and standardised toothbrushing instruction. Group 1 (Touch-to-Teach) additionally received probe-guided, site-specific interdental brush selection and guided in-mouth training, with correctly sized brushes provided for home use. Group 2 (Conventional Instruction) received verbal advice, educational videos, and a model-based demonstration, with brush size selected empirically and no brushes provided for home use. Follow-up visits were conducted at one, two, and three months.

What was measured? A blinded examiner recorded gum inflammation, plaque levels, gum pocket depth, and bleeding at each visit. Both groups completed a questionnaire on brush comfort, perceived efficacy, and satisfaction at one and three months.

What were the key results? The Touch-to-Teach group showed significantly greater reductions in plaque accumulation, gingival inflammation, and probing depth compared with the control group. Both groups showed meaningful reductions in gingival bleeding over time, with no statistically significant difference between groups at three months. Patient-reported outcomes consistently favoured the Touch-to-Teach group. These findings suggest that calibrated, personalised interdental brush instruction may offer advantages for patients with fixed dental prostheses.

Background Patients with fixed dental prostheses are at increased risk of interproximal plaque accumulation due to altered crown contour and interdental geometry. Although interdental brushes are the most effective adjunct to toothbrushing for interproximal plaque removal, no randomised trial had previously evaluated the impact of instructional method on gingival outcomes in this patient population. The Touch-to-Teach method combines chairside probe-guided brush size calibration with hands-on guided in-mouth training, offering a more individualised approach than conventional model-based instruction.

Study Design Single-blind, parallel-group randomised controlled trial conducted at Thumbay University Hospital, Ajman, UAE. Ethics approval: IRB-COD-STD-69-FEB-2024. Written informed consent obtained from all participants prior to enrolment.

Interventions All participants received standardised full-mouth debridement and toothbrushing instruction before baseline. The test group received probe-guided, site-specific interdental brush selection using the Curaprox CPS Colorimetric Probe System, followed by guided in-mouth training until proficiency was demonstrated; size-calibrated brushes were provided for home use. The control group received empirical brush size selection, verbal instruction, access to EFP patient portal educational videos, and model-based demonstration; no brushes were provided for home use.

Outcomes Primary outcome: change in Gingival Index from baseline to three months. Secondary outcomes: Plaque Index, Bleeding on Probing, Probing Depth, and patient-reported outcome measures, assessed at baseline, one, two, and three months by a blinded examiner.

Sample Size Minimum 32 participants required (α = 0.05, power = 80%). Inflated by 25% to 40 participants to account for attrition. Sixty patients screened; 40 enrolled; 36 completed the three-month follow-up (18 per group; 4 withdrew).

Statistical Analysis Continuous outcomes analysed using independent t-tests or Mann-Whitney U test depending on normality. Categorical variables compared using Fisher's exact test. Intragroup BOP changes assessed using Cochran's Q test. Multiple comparisons corrected using Holm's sequential method. Significance set at p < 0.05. Analyses performed in R version 4.3.2.You've used 75% of your weekly limitGet more usageSonnet 4.6Adaptive

Inclusion Criteria:

• Adults aged 18 years and older

• Presence of at least one porcelain-fused-to-metal (PFM) crown in the molar region with supragingival margins, in occlusal function for a minimum of 3 months prior to enrollment

• Prosthesis does not interfere with the supracrestal attachment apparatus (biologic width preserved)

• Clinically healthy periodontium confirmed at screening, with no signs of periodontal disease as per the 2017 World Workshop classification criteria

• Systemically healthy with no conditions known to affect periodontal healing or gingival response

• Ability and willingness to attend all scheduled study visits at baseline, 1 month, 2 months, and 3 months

• Willing and able to provide written informed consent

  -- Exclusion Criteria:

• Uncontrolled diabetes mellitus

• Use of interdental brushes within the previous 6 months

• Current smoker or any tobacco user

• Use of systemic antibiotics or anti-inflammatory medications within the previous 3 months

• Regular use of anti-plaque or antimicrobial mouth rinses within the previous 3 months

• Currently pregnant or breastfeeding

• Fractured or defective fixed prosthesis requiring repair or replacement prior to enrollment

• Inability to attend scheduled follow-up visits

Single-blind study design. The clinical examiner performing periodontal measurements (PI, GI, PD, BOP) at baseline and follow-up visits was blinded to group allocation. Participants could not be blinded due to the distinct nature of Touch-to-Teach hands-on instruction versus conventional verbal guidance. The treating clinician delivering interventions was not blinded. Allocation concealment maintained using sequentially-numbered opaque envelopes.