AbstractAimTo assess the potential benefits of minimally invasive non‐surgical therapy (MINST) in teeth with intrabony defects and to explore factors associated with the outcomes.Materials and MethodsA multi‐centre trial was conducted in 100 intrabony defects in periodontitis patients in private practice. Steps 1 and 2 periodontal therapy including MINST were provided. Clinical and radiographic data were analysed at baseline and 12 months after treatment, with the primary aim being change in radiographic defect depth at 12 months.ResultsEighty‐four patients completed the 12‐month follow up. The mean total radiographic defect depth reduced by 1.42 mm and the defect angle increased by 3° (both p < .05). Statistically significant improvements in probing pocket depth (PPD) and clinical attachment level (CAL) were seen at 12 months compared to baseline (p < .001). Fifty‐six defects (66.7%) achieved pocket closure (PPD ≤ 4 mm) and 49 defects (58.3%) achieved the composite outcome (PPD ≤ 4 mm and CAL gain ≥3 mm). Deeper and narrower angled defects were positively correlated with radiographic and clinical improvements, respectively.ConclusionsImprovements in clinical and radiographic outcomes were seen after MINST. This study highlights the generalizability and wide applicability of this approach, further supporting its effectiveness in the treatment of intrabony defects. Clinical trial registration: NCT03741374. https://clinicaltrials.gov/study/NCT03741374?cond=minimally%20invasive%20non%20surgical%20therapy&locStr=UK&country=United%20Kingdom&distance=50&rank=2.