UNIVERSITY OF WASHINGTONSEATTLE

CLINICAL IMPLICATIONS ‐‐UNIVERSITY OF WASHINGTONUNIVERSITY OF WASHINGTON

POST‐RETENTION ALIGNMENT STUDIESALIGNMENT STUDIES

ROBERT M. LITTLE, DDS, MSD, PhD

PROFESSOR EMERITUSUNIVERSITY OF WASHINGTONUNIVERSITY OF WASHINGTON

SUMMARY

LESSON # 1: NATURE & EXTENT

OF POST‐RETENTION CHANGE ARE UNKNOWNARE UNKNOWN 

CLINICAL IMPLICATION:PLAN ON LIFETIME 

PERMANENT RETENTION 

LESSON # 2aLESSON # 2a: ARCH LENGTH & ARCH WIDTH 

TYPICALLY CONSTRICT POST RETENTIONTYPICALLY CONSTRICT POST‐RETENTION

CLINICAL IMPLICATION:1.   AVOID INCREASING ARCH LENGTH AND       

WIDTH DURING TREATMENT 

2.  PLAN ON LIFETIME PERMANENT RETENTION 

LESSON # 2bLESSON # 2b: ARCH LENGTH & ARCH WIDTH 

TYPICALLY CONSTRICT POST RETENTIONTYPICALLY CONSTRICT POST‐RETENTION, BUT LESS SO FOR A FEW LUCKY ONES

CLINICAL IMPLICATION:EXPECT MINIMAL RELAPSE IN CASES THAT

HAVE ADEQUATE OR EXCESS PRETREATMENTARCH LENGTH

LESSON # 3:LESSON # 3:EARLY STABILITY MAY BE A MIRAGE ‐‐FOR MOST, IN A FEW YEARS THE HONEYMOONWILL BE OVERHONEYMOON WILL BE OVER

CLINICAL IMPLICATION:

LIFETIME PERMANENT RETENTION IS THE ONLY WAY TO ENSURE ALIGNMENT STABILITY

LESSON # 4LESSON # 4ROTATIONS ARE UNPREDICTABLE

CLINICAL IMPLICATIONS:

PLAY IT SAFE

BOND EACH INCISOR TO THE MANDIBULAR FIXED RETAINER

KEEP THE FIXED RETAINER FOR LIFE

UTILIZE SUPRACRESTAL FIBEROTOMY FOR INCISORS THATWERE ROTATED PRE‐TREATMENT

LESSON # 5LESSON # 5LABIAL AND LINGUAL RELAPSE 

ARE UNPREDICTABLE

CLINICAL IMPLICATION:MANDIBULAR ANTERIOR STABILITYMANDIBULAR ANTERIOR STABILITY IS A RARE OCCURRENCE

LIFETIME PERMANENT RETENTION IS THE ONLY RELIABLE METHOD TO ENSURETHE ONLY RELIABLE METHOD TO ENSURE LONG‐TERM SUCCESS

LESSON # 6

EARLY TREATMENT CAN PAY OFF

CLINICAL IMPLICATION:

MAINTAIN LEEWAY SPACEIN CASES WHERE ARCH LENGTHIN CASES WHERE ARCH LENGTH

IS FAVORABLE(NANCE WAS RIGHT !)

LESSON # 7LESSON # 7SERIAL EXTRACTION YIELDS NO 

BETTER POST‐RETENTION RESULTS THAN LATER PREMOLAR EXTRACTIONTHAN LATER PREMOLAR EXTRACTION

CLINICAL IMPLICATION:CLINICAL IMPLICATION:

PERMANENT RETENTIONPERMANENT RETENTION EVEN IF SERIAL EXT DRIFT STAGE IS FAVORABLESTAGE IS FAVORABLE

LESSON # 8LESSON # 8ARCH DEVELOPMENT IS UNSTABLE

(THE MOST SEVERE RELAPSE THAT WE HAVE STUDIED )

CLINICAL IMPLICATION:PERMANENT RETENTION IS MANDATORY

GINGIVAL RECESSION AND DEHISCENCE ARE POSSIBLE SEQUELLAARE POSSIBLE SEQUELLA

LESSON # 9LESSON # 9A. RETENTION POSTPONES RELAPSE

C. RATE OF RELAPSE SLOWS WITH AGEB. RELAPSE IS PROGRESSIVE THROUGHOUT LIFE C. RATE OF RELAPSE SLOWS WITH AGE

CLINICAL IMPLICATION:

LIFETIME PERMANENT RETENTION TO ENSURE LONG‐TERM SUCCESS

LESSON # 10SSON # 0

QUALITY MATTERSQUALITY MATTERS

CLINICAL IMPLICATION:

STRIVE FOR THE HIGHEST QUALITY RESULT

MAINTAIN THE CORRECTION WITH LIFETIME RETENTION

STABILITY AND RELAPSE - SELECTED REFERENCES:

1. Little, R.: The Irregularity Index: A quantitative score of mandibular anterior alignment. Am J Orthod 68: 554-563, 1975.

2. Little, R., Wallen, T., Riedel, R.: Stability and relapse of mandibular anterior alignment. First

premolar extraction cases treated by traditional edgewise orthodontics. Am J Orthod 80: 349-365, 1981.

3. Sinclair, P., Little, R.: Maturation of untreated normal occlusions. Am J Orthod 83: 114-123, 1983.

4. Gilmore, C., Little, R.: Mandibular incisor dimensions and crowding. Am J Orthod 86: 493-502,

1984.

5. Sinclair, P., Little, R.: Dentofacial maturation of untreated normals. Am J Orthod 88: 146-156, 1985.

6. Little, R.: Riedel, R., Artun, J.: An evaluation of changes in mandibular anterior alignment from 10

to 20 years postretention. Am J Orthod Dentofac Orthop 93: 423-428, 1988.

7. Little, R., Riedel, R.: Postretention evaluation of stability and relapse. Mandibular arches with generalized spacing. Am J Orthod Dentofac Orthop 95: 37-41, 1989.

8. Ades, A., Joondeph, D., Little, R., Chapko, M.: A long-term study of the relationship of third

molars to mandibular dental arch changes. Am J Orthod Dentofac Orthop 97: 323-335, 1990.

9. Little, R., Riedel, R., Stein, A.: Mandibular arch length increase during the mixed dentition: Postretention evaluation of stability and relapse. Am J Orthod Dentofac Orthop 97: 393-404, 1990.

10. Little, R., Riedel, R., Engst, E.: Serial extraction of first premolars – postretention evaluation of

stability and relapse. Angle Orthod 60: 255-262, 1990.

11. Riedel, R., Little, R., Bui, T.: Mandibular incisor extraction – postretention evaluation of stability and relapse. Angle Orthod 62: 103-116, 1992.

12. Little, R.: Stability and relapse of mandibular anterior alignment - University of Washington

studies. Seminars in Orthod 5: 191-204, 1999.

13. Ormiston, J., Huang, G., Little, R., Decker, J., Seuk, G.: Retrospective analysis of long term stable and unstable orthodontic treatment outcomes. Am J Orthod Dentofac Orthop 128: 568-574, 2005.

14. Little, R., Sinclair, P.: Clinical implications of the University of Washington post-retention studies. J Clin Orthod 43: 645-651, 2009.

15. Little, R., Sinclair, P.: JCO Interviews: Dr. Robert M. Little on the University of Washington post-retention studies. J Clin Orthod 43: 723-747, 2009.