## 2 Materials and Methods  
### Study Design  
A specific questionnaire was developed to evaluate the impact of orthodontic treatment on patients with ASD who were referred to the Paediatric Dentistry and Special-Needs Patients Unit of the Umberto I Polyclinic Hospital in Rome. The questionnaire consisted of 8 questions. The questions aimed to evaluate the overall satisfaction level related to the service provided and the path followed, as well as any mood or behavioral changes and the management of home hygiene resulting from the use of orthodontic devices.  
The questionnaire was created using Google Forms, a web-based software program that allows the development and publication of online surveys using a web-based interface. Before being administered online, the questionnaire was submitted to a focus group made up of dentists, hygiists, and caregivers to evaluate the correct understanding of the questions.  
In June 2022, the form was sent via an email link to the parents of patients undergoing orthodontic treatment at the time of the survey, for a total of 20 families, inviting them to participate and complete the anonymous online questionnaire. A reminder email was sent approximately two weeks after the initial invitation to participate, and a third and final reminder was sent in September 2022. All data collected were anonymous.  
The pilot study consisted of an exploratory qualitative/quantitative investigation through an analysis relative to the answers of parents with special-needs children and clinical data collection performed by 2 specialized and calibrated dentists using the Frankl scale for evaluating the degree of collaboration and the IOTN scale for evaluating malocclusion, or misalignment, of the teeth and jaws.  
The study underwent a formal review and received approval from the Council of the Department of Oral and Maxillofacial Sciences, Paediatric Dentistry and Special-Needs Patients Unit, Umberto I Polyclinic Hospital, Rome, Italy (No. 15/2020 Prot. n. 0000216 dated 6 February 2020). This study was performed in line with the principles of the Declaration of Helsinki.  
The Frankl scale, a reliable behavior-rating system in common use in both clinical dentistry and research on ASD patients, was used to measure the level of cooperativeness at the first dental visits. Each child was classified by a dentist experienced in treating ASD children into one of the four categories of the Frankl scale: definitely negative--refusal of treatment, crying forcefully, being fearful, or any other evidence of extreme negativism; negative--reluctance to accept treatment, being uncooperative, or some evidence of a negative attitude but not pronounced, i.e., sudden withdrawal; positive--acceptance of treatment, at times cautiously, willingness to comply with the dentist, at times with reserve, but following the dentist's directions cooperatively; and definitely positive--good relationship with the dentist, interested in the dental procedures, or laughing and enjoying the situation [24].  
The Index of Orthodontic Treatment Need (IOTN) scale is a commonly used system for evaluating malocclusion, or misalignment, of the teeth and jaws. It is designed to help orthodontists and dental professionals assess the severity of a patient's malocclusion and determine the appropriate level of orthodontic treatment required. The IOTN scale takes into account both dental health and aesthetic factors. The IOTN scale consists of two components: Dental Health Component (DHC) and Aesthetic Component (AC) [25]. Two orthodontists performed clinical evaluation and collected all raw data.