Interalveolar bone defects: intrabony defects, hemisepta, or craters.
Crater: the lingual and buccal walls are left by the mesial and distal are gone.
Hemisepta: the mesial or the distal wall of the interdental bone is present (marginal bone is intact).
Intrabony defect: the mesial or the distal wall plus the buccal and the lingual walls are present. The tooth wall forms the fourth wall.
Marginal bone defects: when the bone is thick, the defect can occur between the bone and the tooth. If not, it causes inconsistencies on the bony contour. These defects are often associated with interalveolar bony defects.
It is important to give defects their proper names in order to have a better scientific communication.
Pathogenesis: the form of the dental arches and the vascular pathways determine the topography of osseous defects. Craters and intrabony defects are present where arch is wide; marginal defects are present where bone is thin.
Inflammation follows the blood vessels into the bone marrow causing bone destruction.
Trauma from occlusion is one of the factors that can direct the destruction of interalveolar bone to one side, but it is not an essential factor. If the marginal bone is thick, a circumferential defect may take place. Thin marginal bone is resorbed totally when inflammation occurs; in thick marginal bone the destruction takes place between the tooth and the cortical plate.
Diagnosis: the exact topography of osseous defects can be done only during surgery, although an idea of the defect can be taken from X-rays.
Therapy: the objective is the formation of a new attachment apparatus. Usually an intern beveled incision is used. The defect should be curetted out and ostectomy may have to be performed in case of a hemisepted defect. Root planing should not be very aggressive because cementum forms more easily on old cementum than dentin. Occlusal adjustment and splinting may be necessary. Endodontic therapy may be necessary because the pulp may become infected through lateral canals. Foil and dressing are placed over the area and antibiotics are prescribed.
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