Impact of Oral Hygiene Instructions in the Resolution of Peri-Implant Mucositis. A Randomized Controlled Trial.

To determine whether oral hygiene instructions (OHI) alone can be effective in the treatment of peri-implant mucositis (PM). A randomized clinical trial with 56 PM patients was conducted. Participants were assigned to OHI (n = 28) or OHI + Mechanical Instrumentation (MI) (n = 28). Clinical [modified bleeding index (mBI), disease resolution] and microbiological parameters were assessed at baseline (T1), 1 month (T2), and 3 months (T3). Standardized periapical radiographs were taken at T1 and T3. Outcomes were analyzed at patient- and implant-level. 48 patients with 118 implants were analyzed (52 in OHI; 66 in OHI + MI). At T3, success rates were 39.1% (OHI) and 56% (OHI + MI) at the patient level, and 36.4% (OHI) versus 67.3% (OHI + MI) at the implant level. Both groups showed a significant reduction in mBI (p < 0.001). Intergroup differences were not statistically significant, though greater divergence was noted at T3. At the patient level, higher FMPI/FMBI at 3 months predicted lower success (p < 0.05), whereas compliance improved outcomes (OR = 11.4, p = 0.004). At the implant level, failure was associated with OHI-only therapy, non-compliance, and higher mPI (all p = 0.001). History of periodontitis was a negative prognostic factor, linked to higher mBI at T3 (p = 0.010). OHI achieved resolution of PM in a considerable proportion of patients, particularly among compliant individuals. However, a history of periodontitis and posterior implant location negatively influenced outcomes. These findings highlight the importance of patient adherence and implant accessibility, while reaffirming the critical adjunctive role of MI in optimizing therapeutic success.