Introduction: The complexity of malocclusions, such as anterior dental irregularity, is important in determining the outcome of treatment with a removable orthodontic appliance. Little’s Irregularity Index is used to assess alterations of anterior teeth. Material and methods: This was a descriptive study done on 47 patients’ dental casts before and after treatment using a removable orthodontic appliance, between 2013 and 2017. Measurements were made using Little’s Irregularity Index. Results: Patients who presented most often for removable orthodontic appliance treatment had minimal and moderate anterior dental irregularity. After treatment completion, the condition of the patients’ anterior teeth was altered to having either no or minimal irregularities, and no further patients had severe irregularities. Conclusions: The condition of patients’ maxillary and mandibular anterior teeth improved after undergoing removable orthodontic appliance treatment provided by dental students at our dental hospital between 2013 and 2017. Thus, the treatment given can be considered appropriate and in accordance with removable orthodontic appliance indications and functioning. © 2018 Polish Dental Association