The aim is to evaluate in a prospective, randomized, controlled clinical study the healing of a GTR procedure, when it is combined with an immediate orthodontic tooth movement or used alone. Clinical, radiological and reentry (histological) evaluation of a regenerative surgical method (GTR + grafting material) with different postsurgical healing patterns in the treatment of wide, non-containing intrabony defects.

There is limited histological data in literature on the behavior of xenogeneic graft materials in intrabony defects used in periodontal regenerative therapy followed by orthodontic tooth movement (OTM). This clinical study aims to clinically and histologically evaluate the healing response of the periodontal tissues and the healing pattern of a non-resorbable graft material, when they are exposed to orthodontic forces. Therefore teeth presenting non-contained intrabony defects in combination with pathologic tooth migration (PTM) are included in this prospective clinical study. Guided tissue regeneration (GTR) with the application of deproteinized bovine bone mineral (DBBM) and a resorbable collagen membrane is utilized to surgically treat the periodontal defects, which is followed by a random allocation of the patients into test or control group. Subject teeth undergo an early initiated orthodontic treatment after surgery or stay splinted without any tooth movement in the latter groups, respectively. Teeth in test group can be further divided into subgroups, depending if they are moved toward to the former defect (pressure site) or moved away from the defect (tension site). After 9 months of healing a reentry surgery is performed, when a biopsy core is removed with a microtrephine from the previous defect site. The sample is evaluated by means of histology supplemented with histomorphometry, which is the primary outcome variable. Periodontal clinical parameters measured at baseline and at 9 months serves for secondary outcomes. Several studies confirmed the success of graft materials in such comprehensive treatment approaches clinically, but we lack the human histologically proved data, whether DBBM bone substitute can be used safely when the tooth is exposed to OTM. Our main question is how orthodontic induced bone remodelling interferes with these graft particles, can they heal the same or even better compared to control sites. Tissue response might be different also in the case of the two test subgroups.

Inclusion Criteria:

• Periodontitis with intrabony defect (Intrabony component ≥ 4mm, defect radiological angulation > 25°, 1 or max. 2 bony walls (no buccal bony wall), non-containing defect), no class III. furcation involved teeth
• Selected tooth must be in a traumatic occlusion or not in a gnathologically correct bite (migrated, elongated, tilted tooth, etc.).
• Patients must not be heavy smokers (<5 cigarettes/day).
• Full mouth plaque and bleeding scores (FMPS and FMBS) of <20% (O'Leary et al. 1972).
• The patient is able to comply with the study -related procedures (i.e. good level of oral hygiene, follow-up procedures).
• The patient is able to fully understand the nature of the study, signed informed consent.

Exclusion Criteria:

• Pregnant women.
• Participation in another clinical study within 30 days prior to study start.
• Alcoholism, drug dependency, heavy smoking (>5 cigarettes/day).
• Known infection with HIV, HBV, or HCV.
• Patients requiring chemo- or radiotherapy.
• Previous or current radiotherapy of the head.
• Uncontrolled or insulin-dependent diabetes mellitus
• Clinically relevant osteoporosis or systemic disease affecting bone metabolism
• Clinically relevant cardiovascular disease e.g., decompensated cardiac insufficiency, hemodynamically relevant heart valve defects, or myocardial infarction during the last three months.
• Clinically relevant blood coagulation disorder.
• Previous or current treatment with systemic corticosteroids (within 2 months prior to screening visit) of more than 5 mg/day prednisone equivalent.
• Previous or current therapy with bisphosphonates at least for 30 days within the last 12 months before screening visit.

The histologist is blinded to the study protocol