A tooth with a deep intrabony defect, pathologic migration, probing depth of 7 mm or more: the classic candidate for extraction. This prospective study asks whether, two decades on, that tooth can instead be kept. Forty-eight patients with Stage IV periodontitis, each contributing one severely compromised non-molar test tooth, followed a staged protocol: instrumentation; regenerative surgery with enamel matrix derivative (EMD) alone or combined with a bone graft and membrane; orthodontic treatment started 8-12 months later to correct the malposition; and tailored supportive periodontal care.

Thirty-three patients reached the 20-year visit, a 31% drop-out over twenty years. Estimated tooth survival at T20 was 89.1%, with an 86.3% complication-free probability; only four test teeth were lost. The periodontal numbers moved decisively: full-mouth plaque fell from 48.8% to 14.6%, bleeding from 55.5% to 10.2%, and sites with probing depth (PPD) ≥7 mm dropped from 25.8 to 0.9. At the test tooth, mean PPD went from 6.3 to 3.0 mm. Treatment success, defined as survival with PPD ≤4 mm, reached 81.8%.

The message is disciplined optimism. Moving a tooth orthodontically after regeneration does not undo the regenerative gain; it can preserve severely compromised teeth for twenty years, on one condition the authors keep returning to: a stringent, individually tailored maintenance program. Regeneration plus orthodontics is a credible alternative to extraction, but only inside that program.