The purpose of this study was to investigate a group of patients and the treatment strategies of the Department of Orthodontics and Dentofacial Orthopaedics at the Humboldt University of Berlin. The study was also conducted to determine the overall quality and duration of orthodontic treatment as well as to identify factors affecting both features. The treatment records of 100 consecutively finished pa­tients were evaluated retrospectively. Therefore, the number and percentage of patients are identical

The Peer Assessment Rating (PAR) Index was used to score pre- and post-treat­ment dental casts of the same patient. The individual scores for various dental and occlusal components were weighted and summed. A PAR of zero indicates good alignment, and higher scores indicate higher levels of irregularity. It must be mentioned, as with any occlusal index, that other indicators of a successful treat­ment outcome are not considered.

Results:

The Kruskal-Wallis H test and the Mann-Whitney U test were used to compare the results. Statistical significance was set at p ≤ 0.05.

• The sample comprised of more female patients (62%) and a lesser per­cent­age of male patients. The average age at the start of treatment was 14.9 years (7.4 - 42.2 years). Most of the patients who started treatment were between the ages of 9 and 10 years old, 24 patients were over the age of 18. At the start of treatment, 71 patients had an Angle Class II, 21 an Angle Class I and 8 patients an Angle Class III. There were 77 patients who failed at least once to show up for their appointments and 38 patients had nega­tive chart entries regarding appliance wear.

• There was a wide range of appliance types used in this sample. The treat­ment involved fixed appliances for 95 patients. 52 patients were treated only with this type of appliance, 33 were treated with removable and fixed appliances successively and 5 patients were treated solely with removable functional appliances. 10 patients received combined orthodontic treatment and orthognatic surgery. 31 patients had extractions of permanent teeth as part of their treatment. The extraction patterns differed widely and were in­flu­enced by former extractions or congenitally missing teeth.

• To assess treatment standards, the PAR score difference between pre-treat­ment and post-treatment study casts was not appropriate due to a high correlation between PAR difference and the initial PAR score. The post-treatment PAR score is more favourable.

• The examined orthodontic department seemingly produced a high stan­dard of orthodontic care. The average pre- and post-treatment PAR scores were 23.9 and 5.2, respectively. The mean percentage reduction in PAR score was 75.6 percent. Post-treatment, 65 patients fell into the 0 - 5 PAR score group, and 89 patients had a PAR score of 10 or less.
  However, only 4 patients scored 0 at the end of treatment. This was mainly due to minor discrepancies in the anterior-posterior buccal occlusion and most likely the result of the criteria used in assessing this component.
  Accor­ding to the “nomogram” 33 patients have been “greatly improved”, 65 patients “improved” and 2 ranked “worse or no different”.

• Within different types of treatment strategies and Angle Classes, there was a significant difference in the initial PAR score.

• When treatment quality was analysed, of all the factors examined (type of therapy, extractions/agenesis, Angle Classes, compliance and gender) none showed a significant influence.

• The mean active treatment duration was 39.1 months (8 – 85 months). As expected, the sequence of removable and fixed appliances required the longest treatment time (56.2 months). Fixed appliance therapy alone took 30.3 months, a combination of orthodontics and orthognatic surgery lasted for 27.1 months on average.

• When treatment duration was analysed, with all the factors examined (pre-treatment PAR score, type of treatment, extractions/agenesis, Angle Classes, compliance, gender and age at treatment start) only pre-treat­ment PAR score in the fixed appliance group, type of treatment, compliance and age at treatment start, were significantly related.

• Evaluating appliance types, best results were achieved by using removable appliances followed by fixed appliances (4.6 PAR) but with longest treat­ment times. Fixed appliance therapy alone showed almost the same result (5.2 PAR) but required much less treatment time. Removable appliances were exclusively used only on 5 patients and yielded the poorest result (7.6 PAR). Patients treated in combination with orthognatic surgery showed the highest pre-treatment PAR scores and shortest treatment duration.

• Extractions and/or congenitally missing permanent teeth showed no signi­ficant effects on treatment quality or duration, anyhow a tendency to higher pre-treatment PAR scores and treatment lengths was noticeable.

• Angle Classes showed no statistically significant effect on treatment quality or duration of the whole sample beside Angle Class III. Class III yielded the highest pre-treatment PAR scores and shortest treatment duration. This group consisted of 8 patients, of whom 6 were treated surgically. However, analysis separated for appliance types showed longer treatment times for Angle Class II in the fixed appliance group.

• While compliance did not seem to be related to treatment quality, inade­quate compliance did significantly prolong treatment duration.

• There were no significant differences between males and females in treat­ment quality or duration.