Stability and Relapse Results from The University of Washington Studies DR. ROBERT M. LITTLE Dr. Little's paper was exciting and informative and very useful clinically. If you desire a copy of his bibliography , please contact the CDABO Executive Director and request a copy Literature Review: Peter Sinclair found that untreated normals show ALD and widths all decrease slightly to age 20. Nance in the forties taught us about leeway space and to hold on to this space and that it may be possible to hold amount of ALD not more than leeway space. Arthur Dugoni found leeway space can be held and used to correct anterior crowding. With borderline ALD: maintain leeway and try to do non-extraction, can't enlarge widths. To accomplish this he used lingual arch to hold mandibular space and maxillary appliance and headgear to modify Class II occlusion. Space versus Crowding: Excess ALD - spacing typically will close even though we do not fully close these spaces, much like untreated ideals. We still need to retain excess space cases. Studies show that arch length and widths decrease with time. With retention lower space did not reopen and there was good stability. In inadequate arch length cases extraction or non-extraction decision is best made early. Stability is still unpredictable. Some cases with minimum ALD relapse and some with strong ALD are stable. Some cases are expanded and are fine while others are not. Keep lower canine width stable. Keeping the lower 3 X 3 on until the 8's have been resolved was thought to be the answer. But this has not been found to be predictable. From an earlier study, 2/3 of the cases seemed to crowd later, 1/3 were stable. Conclusions: Long term results from orthodontic treatment are not predictable as far as stability and relapse are concerned. Recommendation: Long term permanent retention or removable retention. Permanent retention is preferred as many variables are then removed and success of long term stability is increased. A recent study shows that all types of cases are stable with long term fixed retention. Overview: Typically decrease continues with all dimensions with time, AL continues to get worse even 30-40 years out of retention. Majority of change seems to happen in first 5-10 year period out of retention, regardless of age. The early 20's show the most change, more subtle changes occur from age 30 and beyond. There is never a point of increased stability. Typically upper arch is more stable. In a study done where ABO cases were compared to adequately treated cases there was no difference in long term stability when retention was discontinued. When lower retainer is removed, even if it was worn for ten years, the teeth seem to move at the same rate as if the retainer was only worn for two years. Orthodontists tend to believe that their results are permanent. As in other medical fields where results are continually changing "the treatment that we accomplish is changing continually, this is normal physiology. If we want to maintain a long term result we have to use retention in some form." Serial Extraction alone with no orthodontic treatment had even poorer stability than treated cases. In untreated adult malocclusions widths as well as arch length decrease over time. Changes seem to be less, but this is not yet a certainty. Comparing early extraction versus later extractions, both groups show nearly the same post retention stability. One third will be winners, two thirds will not. Treat to the ideal standard. However neither growth direction or amount or achieving cephalometric norms in treatment seem to have any correlation with long tern stability. Original malocclusion is not necessarily repeated in relapse. It was once thought enlarging the lower in the mixed dentition utilizing a lip bumper or such and then complete treatment would produce better stability. His study showed these cases had the worst irregularity scores of any sample. Less than 10% were winners. Permanent retention is essential. Maintaining the lower arch length is a better strategy than trying to make the arch bigger. Typically orthodontists round out the arch form with orthodontic treatment, and in time, this rounded shape tends to revert back to a more tapered shape. The more change we accomplish the more relapse occurs after retention is discontinued. Using the patient's natural arch form seems a better choice than conforming to an ideal arch form. Untreated patients have no better retention results, than treated cases. All cases, which have inadequate arch length, including extraction cases, have the same failure percentages, about 2/3rds, over ten years after retention is discontinued. Short term stability , after retention is discontinued, is not a predictor of long term stability. So we will have one-third with good stability but we won't be able to predict which cases will remain stable. Upper lingual anatomy has no correlation to stability of lower anterior crowding or open bite occlusions. Serial extraction cases with some anterior alignment in this early phase seem to have a better retention success, according to a recent study. Overcorrection does not help in maintaining alignment necessarily. 20% of the time, relapse will occur in the direction of the over-correction rather than the original malocclusion. The role of third molars in relapse: Cases with extracted third molars, missing third molars, fully erupted third molars and impacted third molars were compared at the end of treatment. Surprisingly there was no significant difference in retention between these groups in long term stability. Size of incisors seems to have no association to long term success rate. Narrow incisors no better than wider incisors. Stability in single incisor or two incisor extractions is surprisingly good. There seems to be no difference in long term periodontal health in patients that have fixed retainers that have been worn for a number of years versus patients with removable retainers worn for an equal number of years. Long term retention in some form is essential if we are to maintain an ideal result.