*3.1.2 Fractured teeth and forced eruption*

Trauma to the upper anterior is the most common occurrence in children and adolescents. This trauma can be (a) fracture of the crown or (b) fracture of crown and root. If the fracture is restricted to the crown, then endodontics and restorative procedures will be sufficient to manage. If the fracture extends into the biological width, then any restoration will cause irritation and inflammation to the marginal gingiva. Alternatively, extrusion of the tooth followed by restoration may be possible depending on the amount of tooth structure [34]. If the fracture extends to the root, then, depending on the level of involvement the tooth may have to be extracted. There are six criterias used to determine the direction of treatment to choose:


If all the above criteria are favorable, forced eruption of teeth can be considered. It can be carried out with orthodontic brackets or with composite extension with elastics. If the tooth movement is faster, the bone will not follow the root, hence circumferential fibrotomy would be necessary. If the tooth movement is slow, the bone follows the root and crown lengthening procedure may be required for the restorative phase.

After the forced extrusion, teeth must be stabilized to prevent re-intrusion, which may occur due to the orientation of the oblique fibers, which will allow intrusion with any compressive force, until 6 months post treatment [33].

Usually during forced eruption, the clinical crown length may be shortened. This is because the gingiva follows the direction of eruption of the teeth. If there is a mismatch in the bone levels with the adjacent teeth, flap elevation and bone recontouring followed by gingivectomy can be considered. If the mismatch is limited only to the gingival heights then gingivectomy is sufficient [32, 34].

Post gingival surgery, embrasures due to the difference in the widths of root and crown may be seen. These can be corrected either by re- contouring the teeth or by reshaping the crowns during space closure. The latter is preferred because it improves the overall shape of the final crown [35].

#### *3.1.2.1 Hopeless teeth maintained for orthodontic anchorage*

In certain cases, moderate to severe periodontally compromised teeth may be used for anchorage. Even though the tooth is compromised, with sufficient bone it may be used for anchorage. Flap surgery and root debridement can improve the quality of this anchorage unit and post orthodontics, these can be maintained as are or extracted and replaced [36].

#### *3.1.3 Orthodontic treatment of gingival discrepancies*

#### *3.1.3.1 Uneven gingival margins*

The gingival margins of the anterior teeth play an important role in esthetics. The four factors that need to be considered for good esthetics are: (a) The height of the gingival margins of upper central incisors should be equal, (b) Gingival margin of lateral incisor should be coronal to the central incisor, (c) The gingival contour should follow the shape of CEJs in the anterior region, (d) Gingival papilla should occupy half the distance from the highest point of gingival contour to the incisal edge; the remaining half should be tooth contact [37].

The cause of the marginal discrepancies should be appropriately diagnosed and treated by either orthodontics or gingival surgery.

Four steps that can be considered for planning the treatment are: [36, 37]

Lip line: When the patient smiles, if the gingival discrepancy is not visible, it can be left untreated. If it is visible, then step two should be evaluated.

Labial sulcular depth: in the presence of an uneven gingival margin, if the labial sulcular depth is greater than 1 mm, then gingivectomy is possible. If the labial sulcular depth is less than 1 mm, then step three should be evaluated.

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

Relationship to the adjacent incisors: If the Central incisor is longer than the adjacent lateral incisor, orthodontic extrusion of this incisor will allow the gingival margins to move apically. The extruded tooth will have to be leveled with the adjacent teeth. If the Central incisor is shorter than the adjacent lateral incisor, then step four should be evaluated.

Abrasion: The incisal edges should be checked in the occlusal view. If this is thicker than the adjacent central incisor, then extrusion has taken place. Then the treatment of choice would be intrusion of the affected central incisors which will move the gingival margin apically. Followed by restoration of incisal edges. This step should be completed 6 months prior to the appliance removal as the periodontal fibers need time for re-orientation.

#### *3.1.3.2 Significant abrasion and over eruption*

When the patient reports with an abraded anterior, it can be managed either by orthodontic extrusion and restoration of the anterior tooth or by orthodontic intrusion of the adjacent anterior teeth followed by restoration of incisal edges. The extrusion option is not preferred as it may alter the crown: root ratio (1:1). It is advisable to intrude the anteriors. Extrusion of posterior teeth is not possible due to the occlusal forces. Once the intrusion has been achieved it is followed by a retention phase for 6 months after which restorations on the incisal edges can reestablish the ideal crown height [38].

#### *3.1.3.3 Open gingival embrassures*

The gingival embrasures can be deficit or open due to several reasons such as: (1) root position, (2) underlying bone loss, and (3) shape of the crown. If the problem is due to divergent roots, then orthodontic correction with modification of bracket position is an option. Once the root position is corrected, changes in the incisal contact can be modified. If the open gingival embrasure is due to other reasons, intrusion of the teeth would be ideal. Orthodontic intrusion will lead to compression of spaces which will in turn lead to an occlusal push of interdental gingiva, thus achieving the ideal ratio of 1:1, embrasure to tooth contact [34].

#### **4. Conclusion**

Adjunctive orthodontic treatment for patients with periodontal disease has some unique effects. Orthodontic treatment should only be done on a clinically sound periodontium. It is essential for dentists to have adequate knowledge on perio-ortho interrelationship. Maintaining a good oral hygiene and receiving regular basic periodontal care is of outmost importance to achieve a more effective orthodontic treatment. A better outcome can be achieved along with good maintenance, through a close collaboration between the orthodontist and the periodontist.

#### **Acknowledgements**

We would like to acknowledge the contribution of Dr. Kavarathapu Avinash, Periodontist and Implantologist, and Dr. Joseph Abraham, Orthodontist for generously sharing their clinical case photographs for our chapter.

Last but not the least, we would like to thank our parents and families, our teachers and mentors for their never-ending support and guidance.
