Dental assistants in maintaining dental and oral health are required to work quickly and precisely because they are very responsible for activities before, during and after dental treatment takes place, musculoskeletal disorders are disorders that can cause muscles to not function properly due to activities that are too heavy which can cause posture unnatural body. One strategy to overcome this problem is through the ergonomic model of the dental chair side assistant "Edition" this model consists of working positions and work place stretching. The purpose of the study was to analyze the effectiveness of the ergonomic model of the Dental Chair Side Assistant "Edition" on the risk of working posture in dental and oral therapists "Edition". The method used is a quasi- experimental pre-test and post-test with control group design. Sampling using the Lemeshow formula. The research sample was divided into 2 groups, namely the intervention group and the control group which consisted of 32 people, based on the inclusion criteria. This study used a questionnaire instrument and an observation sheet. Statistical test using Intraclass correlation coefficient, Mann Whitney, and Wilcoxon. The results obtained are the ergonomic model of the chair side assistant "Edition" effectively reduces the risk of work posture (p = 0.000) so it can be concluded that the ergonomic model in the chair side assistant "Edition" is effective as a model used in reducing complaints of musculoskeletal disorders, namely the risk of work posture in dental and oral therapist.Keywords: Ergonomics, Chair Side Assistant, Musculoskeletal, Dental andOral Therapist.

Keywords : Ergonomics, Chair Side Assistant, Musculoskeletal,Dental, Oral Therapist.