*3.1.1.1 Orthodontic treatment for osseous defects*

According to the literature, there are three risk groups in a population for progression of periodontal bone loss: (a) those with rapid progression (about 10%), (b) those with moderate progression (the majority, about 80%), and (c) those with no progression (about 10%) [13, 30].

Patients who have had a history with periodontal disease and bone loss, present with no contraindication to receiving orthodontic treatment if the disease has been treated and maintained adequately since. The Periodontist usually guides the Orthodontist in this regard as progression of an untreated periodontal breakdown must be anticipated, however, the patient's periodontal condition must receive attention during planning and execution of orthodontic treatment [30].

#### *3.1.1.2 Hemiseptal defects*

Hemiseptal defects are one-or two-wall osseous defects that are often seen around mesially tipped teeth or supra-erupted teeth. Usually, these defects can be eliminated with orthodontic treatment [30, 31].

Some patients have a discrepancy between both the marginal ridges and the bone levels but these discrepancies may not be of equal magnitude; orthodontic leveling of the bone in this case may not be able to level the marginal ridges. In these patients the crowns of the teeth should not be used as a guide for completing orthodontic therapy. The bone should be leveled, and any remaining discrepancies between the marginal ridges should be equilibrated. In case of a tooth that is tipped, uprighting it will level the defect [31].

If there is supraeruption, then, intrusion and leveling the tooth, can help in leveling the osseous defect. It is important that any periodontal inflammation be controlled before the start of orthodontic therapy. After the completion of orthodontic treatment, these teeth should be stabilized for at least 6 months and reassessed periodontally.

#### *3.1.1.3 Advanced horizontal bone loss*

The location of the bands and brackets on the teeth is a primary determinant of outcome after orthodontic treatment has been planned. In a periodontally healthy individual, the anatomy of the crowns of the teeth determines the position of the brackets. Incisal edges and marginal ridges form a guide to position the anterior brackets and posterior bands or brackets. If the incisal edges and marginal ridges are at the correct level, the cementoenamel junction (CEJ) will also be at the same level. This relationship creates a flat, bony contour between the teeth [13, 32].

In situations where the patient has an underlying periodontal problems and significant alveolar bone loss around certain teeth, using the anatomy of the crown to determine bracket placement is not appropriate. In vital teeth, the equilibration should be performed gradually to allow the pulp to form secondary dentin and insulate the tooth during the equilibration process [32].

The main goal of equilibration and favorable bracket placement is to provide a constructive bony level as well as a more favorable crown-to-root ratio. In some of these patients, the initially apparent periodontal defects may not need periodontal surgery after orthodontic therapy.

#### *3.1.1.4 Furcation defects*

Furcation is the place where the roots of teeth separate. Furcation defect is bone loss, commonly due to a result of periodontal disease affecting the base of the root trunk of a tooth. These furcation defects can be classified as: Class I, Class II and Class III (mild, moderate and severe respectively) [11]. Furcation lesions require special consideration because they are difficult to maintain and can worsen during orthodontic therapy. These patients ideally should be on a 2 to 3 month recall

#### *Orthodontic-Periodontics: An Interdisciplinary Approach DOI: http://dx.doi.org/10.5772/intechopen.98627*

schedule. Detailed instrumentation of the furcation can help minimize further periodontal breakdown.

The treatment modalities in a furcation defect usually involve hemisection (mostly in class III defects). After hemisection, and completion of endodontic and periodontal surgery, can the tooth serve as an abutment. Some molars with class III furcation defects, may have short roots, advanced bone loss, fused roots, or other conditions that contraindicate hemisection. In these patients, extraction and replacement with an implant is advisable [33] at any point irrespective, to the orthodontic treatment.

## *3.1.1.5 Root proximity*

When roots of the posterior teeth are in proximity, periodontal health and restorative options are limited. With the help of orthodontics, these roots can be separated allowing bone to form, which widen the embrasures, provide additional bone support, and make oral hygiene more accessible. The movements should be planned prior to bonding, so they can progress with the initial arch wires. The movements can be monitored with radiographs. A movement of 2-3 mm is usually sufficient for favorable bone response. The oral hygiene maintenance should be good. Occasional occlusal adjustments may be required in the process [31, 33].
