Orthodontic Stability: An Elusive Goal
From its earliest beginnings, orthodontics has attempted to achieve several goals: good function and occlusion, good dental and facial esthetics, stability, and long-term dental health. Quite naturally, however, at different times one or two of these goals have been emphasized more than the others. Edward H. Angle stressed the goal of an excellent occlusion without extractions. On the other side, Calvin Case, out of a concern for stability and facial esthetics, argued that extractions were necessary in some cases. Charles Tweed, dissatisfied with the protrusive faces and instability of universal nonextraction treatment, often advocated bicuspid extractions.
In recent years, there has been a renewed emphasis on facial esthetics. The increase in adult orthodontic patients is one manifestation of that concern. The upsurge in orthognathic surgery reflects a desire for both esthetics and stability. Flat faces with moderate crowding are now often treated without extractions to avoid the adverse facial changes that would accompany extraction therapy.
According to Little, significant post-treatment changes occur in approximately two-thirds of all cases, regardless of whether extractions are performed. He could not find a single criterion that would reliably predict future relapse or future stability. This suggests that stability may be an elusive goal in orthodontics, and perhaps should not be regarded as an essential ingredient in successful treatment.
The neuromuscular patterns of the perioral musculature and the tongue may preclude achieving stable tooth positions in correct occlusion and with satisfactory facial esthetics. Even rotations continue to be a problem. Supracrestal fiberotomies are not entirely successful in preventing anterior rotations from recurring. Years of retention may only postpone the day of reckoning-- slowly diastemas reappear, overbite deepens, rotations develop.
Perhaps we should acknowledge that stability is not always achievable. Permanent retention might be advisable in cases where facial esthetics demands placing teeth in unstable positions. Fortunately, the development of adhesive composites has provided us with means to splint teeth together. Flexible wires can be bonded to adjacent teeth to prevent relapse. Maryland-type splints can be used for rigid and more long-lasting retention. Nighttime removable retainers can place the responsibility with the patient for indefinite wear.
Orthodontists flagellate themselves unnecessarily. The term "relapse" has the sound of failure. Plastic surgeons never say an operation failed; they say it's time for a "revision". They explain that facelifts aren't forever, and may have to be redone in five or 10 years. Only orthodontists perform a service in the teen years and feel unsuccessful if it hasn't remained stable at age 40.
Until we know more about the biological mechanisms that determine stability, we may wish to change our presentation to the public on the nature of orthodontic correction. We can achieve an improvement in the occlusion and alignment of the teeth. There will be a tendency for crowding (or spacing) and rotations to recur. This may be prevented by using fixed and/or removable retainers indefinitely. If "permanent" retention is chosen, it will be necessary to schedule follow-up care every six months to check on the retainers.
The presence of post-treatment changes is not an indictment of the treatment. Stability simply may not be achievable in the majority of cases we treat. But even with its limitations, orthodontics makes a significant contribution to patients' health and appearance. It's time for us to tell the truth and stop feeling guilty.