Adult Orthodontic Treatment
Adults are seeking orthodontic treatment more often. The proportion of older patients being treated in a specialist practice has become greater and will continue to increase. There are special aspects of treatment of this kind that justify devoting a separate chapter to its discussion.
Adults for whom orthodontic treatment is contemplated can be divided into four types according to periodontal conditions: (1) patients with healthy intact periodontal tissues, (2) patients with inflammation and intact periodontal tissues, (3) patients with healthy tissues that have receded, and (4) patients with inflamed periodontal tissues that have receded.
In this chapter the subjects dealt with are general aspects such as psychological factors, oral hygiene and cooperation, the structure of bone and collagen, and magnitude and direction of forces. Specific aspects concerning the periodontal tissues such as preparatory treatment, periodontal therapy, appliances and tooth movements that conserve the periodontal structures, and regeneration potential are dealt with separately.
Therapy is divided into late treatment of orthodontic anomalies, treatment as it applies to restorative dentisty, treatment after spontaneous tooth migrations, and treatment where there are disturbances of function. Then follows discussion of surgical-orthodontic treatment and retention.
Psychological factors play an important part in treatment of adults. Oral hygiene and cooperation are often better than when treating children. Because the structure of bone and collagen changes with age, adults react to orthodontic treatment somewhat differently from children. The size and direction of appliance forces need to be adapted to adult conditions.
With the growth of welfare services and the increased availability of orthodontic care, the demand for treating adults has also grown. In past decades a visibly abnormal arrangement of the teeth was not much remarked upon. Currently the emphasis is on retaining one’s natural teeth; the transition to a partial or full denture as the response to unesthetic teeth is no longer considered an appropriate mode of treatment.
Children generally accept wearing an orthodontic appliance. The increase in dental awareness has reduced the disinclination of adults to wear appliances. People are more and more willing to accept the inconvenience with the prospect of a significant improvement in their appearance and a better chance of keeping their own teeth.
Adult orthodontic treatment can give great satisfaction to the treating dentist, and the patients are usually very interested and thankful for the improvements.56 In general, wearing of orthodontic appliances by those who have requested them creates no problem, certainly when the appliance is hardly visible. Even though the sensitivity of the oral structures is greater in adults than in children, this is seldom a source of difficulty.
Adults are usually more aware than children of the importance of good oral hygiene. This applies particularly to those who seek orthodontic treatment. At the same time, the consequences for an adult of neglected oral hygiene are more serious than for children. Particularly when periodontal pockets are present and plaque is allowed to accumulate, pathologic processes can develop. With adults it is irresponsible to undertake orthodontic treatment if oral hygiene is not optimal. Moreover, under such circumstances the cooperation in other respects (e.g., good wearing of, manipulation of, and respect for appliances) often is insufficient.
The most important difference between orthodontic treatment of adults and children is that with adults there is no prospect of using the possibility to change the relationships of individual facial bones, such as can be done in a growing child with facial orthopedic techniques. Purely orthodontic tooth movement is all that is possible, and there are also some limits compared with what is possible with children.
The bone of adults and especially of older people is different in structure and composition and reacts differently from that of children. The activity of osteoblasts and osteoclasts is reduced. The cortical bone is denser and after middle age it becomes thinner in cross section.67 The quantity of bone formed no longer matches that broken down. The total amount of bone diminishes as a result.
In trabecular bone the number and thickness of the trabeculae reduce. The cortical bone not only becomes thinner but fenestration in the cortical plates appears.136 Further, the turnover rate of collagen becomes smaller with age also. In addition, the space for the periodontal membrane becomes narrower.
The above changes that occur with age result in orthodontic treatment of adults that is slower than that of children. Specifically, it takes longer before the first tooth movements can be observed.
Moreover, it is essential with older patients to avoid major movements in a labial (buccal) or lingual direction. Otherwise, undesirable bone loss will occur. This is related to the reduced cell activity and denser structure of the cortical plate.37 In general one should aim to confine adult tooth movements to within the cortical plates, and to prevent root resorption as much as possible.208
Even more than with children it is important with adults that orthodontic forces be small and long-acting. The reduced cell activity, the thinner periodontal membrane, and the usually reduced area of attachment between root and alveolar bone demand very small forces.37, 56, 129, 209, 237 Hyalinisation and necrosis must be avoided as much as possible.167 The appliances used in adult orthodontics should be activated less often and less strongly than for children.
In applying forces, account should be taken of the intra-alveolar root length. The smaller the attached part of the root, the more the centre of resistance will move apically.135
In treating adults it is important to secure and maintain as good a condition of the periodontal tissues as is possible. The appliances that will be used and the tooth movements that will be performed should be directed to this end. Furthermore, in some circumstances periodontal defects may be ameliorated by orthodontic treatment.
Orthodontic treatment of periodontally vulnerable patients should only take place after optimal oral hygiene has been achieved, supragingival and subgingival plaque and calculus have been removed, any necessary root planing performed, and the accessible surfaces polished (initial therapy). There should be no sign of inflammation. The papillary bleeding test should be negative.
If there has been any pathologic process involving the periodontal tissues, it is necessary after the initial therapy to delay use of orthodontic appliances until an acceptable situation has been achieved. If the papillary bleeding test is still positive the initial therapy should be repeated and a flap operation contemplated.40 However, it is more and more the rule to employ scaling, planing, and polishing rather than surgical intervention.
An inflamed periodontal pocket bleeds on probing. The reliability of this method of recognising inflammatory phenomena is related to the pocket depth. With 4 mm-deep pockets, blood from the pocket is easily visible. Blood from deeper pockets usually does not reach the gingival margin, hence lack of visible bleeding does not mean absence of inflammation in deep pockets. When a pocket is deeper than 4 mm a filter paper point can be inserted and checked after 30 seconds for the presence of blood.169 Because the use of orthodontic appliances in an inflamed area increases the danger of attachment loss, it is necessary to be extremely cautious when deep pockets are present. Pockets 6 to 8 mm deep can remain as they are if no further unfavourable influences appear, as long as the area is well cared for by the patient and professionally cleaned every 3 months.51 Under these conditions it is reasonable to begin orthodontic treatment.
If plaque accumulation is avoided and care is taken not to move a tooth bearing plaque or calculus, then there will be no periodontal sequelae to orthodontic treatment. However, the risk of developing undesirable periodontal changes is increased. Pockets that have been trouble-free for some time can flare up. To prevent such occurrences as much as possible, monthly professional prophylaxes can be desirable.
Especially with deep pockets it is always possible during orthodontic treatment for unexpected inflammatory phenomena to occur (blood or pus from the pocket). If this does occur immediate action is called for. According to the circumstances it must be decided whether the orthodontic appliance should be kept in place or wholly or partly removed. In patients with unusually susceptible periodontal tissues it is advisable, in addition to monthly professional prophylaxes, to irrigate the site every 2 days with chlorhexidine. In doing this a syringe should be used to irrigate only the places in most danger.
On concluding the orthodontic treatment an acceptable periodontal situation must be maintained. This will be achieved if the patient keeps up a high standard of oral hygiene and has regular (3-month) professional prophylaxes. A recall system for this purpose is recommended.
Plaque is the predominant factor in the development of periodontal disease. Its accumulation should be avoided by every means. As is well known, overhanging restoration margins are undesirable. Crown preparations should be finished some distance away from the gingival borders where possible.
Orthodontic bands seldom fit closely cervically, and even when they do there is still the obtrusive band thickness at the margin. Altogether there is an increased chance of plaque accumulation. Attachments bonded directly to the enamel have the advantage of only encroaching on a part of the buccal surface. Moreover, they can usually be placed some distance away from the gingival margin. Bonded brackets and tubes may therefore cause less loss of periodontal tissue and bone than bands.1, 244 In that respect, the use of small bonding bases and care taken to not leave excess composite resin on the tooth during the bonding process are important. Arches that are in structure and shape easy to keep clean will help the oral hygiene. In addition there are some toothbrushes that are well designed to cope with the difficulties of cleaning fixed appliances.
Despite the fact that there are few quantitative data available concerning the undesirable consequences of removable acrylic resin appliances, this is not an aspect that can be ignored. Almost all removable appliances cause irritation of the mucosa from mechanical factors, plaque accumulation, or both. When the proper measures have been taken regarding the plate and oral hygiene, a satisfactory result can be obtained in retracting maxilla/>