Case Descripton: Male patient, 68 years of age, non-smoker, with type II diabetes mellitus, showed-up in the appointment with complaints of recurrent abscesses on the tooth 23. After periodontal assessment and radiographic examination (panoramic + periapical radiography), a total loss of the buccal insertion on the tooth 23 was observed, with Probing Pocket Depths (PPD) of 6mm in (MV), 12mm in (V) and 12mm in (DV), degree III mobility, not detecting, however, increased PPD's on the adjacent teeth. After non-surgical periodontal treatment, followed a discussion about the several therapeutic options, being selected the Reconstructive Periodontal Therapy (RPT) with Enamel Matrix Derivatives (EMD), bone substitute (Bio-Oss) and resorbable membrane (Bio-Gide). Previous to surgery, the tooth 23 was endodontically treated and splinted to the neighboring teeth. Postoperative recommendations and medication were prescribed. The follow-up period is 11 months. Discussion: Teeth related to infra-bony defects with deep periodontal pockets became a clinical challenge. There are several therapeutic approaches, however, RPT has proven to be suitable in the retention and healthy maintenance of the teeth, with good long-term results. It's a conservative treatment, although it demands a very strict periodontal protocol. Conclusion: RPT can be successfully used on hopeless teeth associated with infra-bony defects to or beyond the apex and has potential to modify the dental prognosis. The mid-term results are promising, however, further scientific evidence in this field is required. Schlagwörter: infrabony defects, reconstructive surgery, periodontal regeneration, prognosis, hopeless teeth