Design A prospective interdisciplinary, multi-centre, cohort study.

Cohort selection A total of 250 patients were recruited from three university departments of orthodontics and one orthodontic dental practice. The cohort size was decided by a sample size calculation performed and the participants were selected over 14 months. Four psychological questionnaires were used, each targeting specific psychological characteristics, combined with orthodontic assessments. Only questionnaires in English, with German translations, were chosen for international comparability. The COHIP-19 was used to assess Oral Health Related Quality of Life (OHRQoL), the KIDSCREEN-10 index was used to assess HRQoL, the RSES was used to assess self-esteem and the SDQ was used for behavioral problems. To record the orthodontic parameters, standardised orthodontic diagnosis consisted of detailed anamnesis, functional diagnosis, extra-oral photos, an orthopantomogram, lateral cephalomentrics and plaster impressions. The same assessor examined the questionnaires and the orthodontic measurements.

Data analysis Statistical programme (SPSS) was used to assess the data. Simple linear regression models were tested to assess the predictive values of all the specific orthodontic parameters individually (= predictors) on the COHIP-G19 (= criterion). Further to this, multiple linear regression analysis was used to assess which of the independent predictors can be assessed in combination to relate to OHRQoL.

Results The questionnaire was completed by 248 participants. From the simple linear regression, there was a statistically significantly impact on COHIP-G19 score in patients with competent lip closure, straight chin position, little-index-upper, overjet, overbite and ANB.

For the multiple linear regression analysis, age, KIDSCREEN-10 index, RSES, SDQ and all six orthodontic parameters that had a statistically significant impact on COHIP-G19 (P <0.05) in the simple linear regression were assessed. Of these five (SDQ, KIDSCREEN-10, overjet, little-index-upper and overbite) parameters resulted in a multi-linear regression model that was statistically significant and explained 32.3% of the total variance in OHRQoL. Adding additional parameters did not significantly improve the R2-change.

Conclusions Further longitudinal studies are required to investigate if the treatment of these malocclusions also improves the OHRQoL of children and adolescents.

设计前瞻性跨学科，多中心，队列研究。

同类群组选择从三个大学的正畸科和一个正畸牙科诊所招募了总共250名患者。队列大小由进行的样本大小计算决定，并在14个月内选择参与者。使用了四份心理问卷，每份针对特定的心理特征，并结合了正畸评估。为了国际可比性，只选择了英语问卷和德语翻译。COHIP-19用于评估与口腔健康相关的生活质量（OHRQoL），KIDSCREEN-10指数用于评估HRQoL，RSES用于评估自尊，而SDQ用于行为问题。为了记录正畸参数，标准化的正畸诊断包括详细的回忆，功能诊断，口腔外照片，正射影像图，外侧头颅和石膏印模。同一名评估人员检查了问卷和正畸测量值。

数据分析使用统计程序（SPSS）评估数据。测试了简单的线性回归模型，以分别评估COHIP-G19（=标准）上所有特定正畸参数（=预测值）的预测值。除此之外，还使用多元线性回归分析来评估哪些独立的预测因子可以与OHRQoL结合进行评估。

结果问卷由248名参与者完成。从简单的线性回归分析来看，有能力的嘴唇闭合，下巴笔直，下指数低，上喷射，覆牙合和ANB的患者对COHIP-G19评分有统计学上的显着影响。

对于多元线性回归分析，评估了年龄，KIDSCREEN-10指数，RSES，SDQ以及在简单线性回归中对COHIP-G19具有统计学显着影响（P <0.05）的所有六个正畸参数。在这五个参数（SDQ，KIDSCREEN-10，过喷射，小指数上偏和过咬）中，得到了一个多元线性回归模型，该模型具有统计学意义，可解释OHRQoL的总方差的32.3％。添加其他参数不会显着改善R2更改。

结论需要进一步的纵向研究来研究这些错牙合畸形的治疗是否还能改善儿童和青少年的OHRQoL。