This prospective study aims to compare two different orthodontic treatment modalities-clear aligners and removable appliances-in children aged 6 to 12 years during the mixed dentition period. The primary focus of the research is to evaluate treatment-related changes in oral hygiene status assessed using the Simplified Oral Hygiene Index (OHI-S), oral health-related quality of life, pain and anxiety levels, and speech function. In addition, orthodontic treatment need will be assessed using the Index of Orthodontic Treatment Need (IOTN), including both the Dental Health Component (DHC) and Aesthetic Component (AC). By assessing multiple dimensions associated with early orthodontic intervention, the study seeks to provide a comprehensive understanding of how different appliance types influence clinical, functional, and psychosocial outcomes in pediatric patients.

This prospective study aims to compare two different orthodontic treatment modalities-clear aligners and removable appliances-in children aged 6 to 12 years during the mixed dentition period. The primary focus of the research is to evaluate treatment-related changes in oral hygiene status assessed using the Simplified Oral Hygiene Index (OHI-S), oral health-related quality of life, pain and anxiety levels, and speech function. In addition, orthodontic treatment need will be assessed using the Index of Orthodontic Treatment Need (IOTN), including both the Dental Health Component (DHC) and Aesthetic Component (AC). By assessing multiple dimensions associated with early orthodontic intervention, the study seeks to provide a comprehensive understanding of how different appliance types influence clinical, functional, and psychosocial outcomes in pediatric patients.

The mixed dentition period, occurring approximately between the ages of 6 and 12, represents a transitional developmental stage during which primary and permanent teeth coexist. In this phase, early diagnosis and treatment of orthodontic anomalies are particularly important to support functional, aesthetic, and psychosocial development and to minimize the need for more complex treatment in later stages.

Removable orthodontic appliances have traditionally been used to guide dental arch development, correct minor malocclusions, and eliminate harmful oral habits. Advances in digital technology have introduced clear aligners as an alternative treatment option that offers aesthetic and removable features. Despite their differences in design and material characteristics, both approaches are commonly used during early orthodontic treatment planning.

Orthodontic appliances may influence various aspects of oral function, including oral hygiene maintenance, periodontal health, caries risk, pain perception, anxiety levels, and speech performance. In growing children, treatment experiences may additionally shape cooperation, adaptation, and overall quality of life. Therefore, evaluating orthodontic interventions during the mixed dentition period requires consideration of not only mechanical efficiency but also broader functional and psychosocial parameters.

Orthodontic treatment need and malocclusion severity may also influence oral hygiene maintenance during treatment. Therefore, the present study additionally evaluates the relationship between orthodontic treatment need assessed using the IOTN and oral hygiene status assessed using the OHI-S at baseline and during the early treatment period. Appliance-related changes in intraoral volume and tongue movement may alter speech production, potentially affecting articulatory patterns and acoustic characteristics. Contemporary acoustic analysis methods, such as the use of specialized speech software, allow the objective measurement of frequency- and time-based acoustic parameters and provide complementary information to clinical observations.

This prospective study was designed to investigate how clear aligners and removable appliances influence oral hygiene status, pain and anxiety perception, oral health-related quality of life, orthodontic treatment need, and speech performance in children. Through standardized clinical assessments, validated questionnaires, and acoustic analysis, the study aims to generate multidimensional data that may guide clinical decision-making in early orthodontic treatment planning.

Inclusion Criteria:

- Children aged between 6 and 12 years who applied to the Clinics of the Departments of Pedodontics and Orthodontics at Marmara University Faculty of Dentistry were included in the study.

• Patients were required to present with anterior cross-bite type malocclusion.
• Participants had to be cooperative, native Turkish speakers, and have no systemic disease, syndrome, craniofacial anomaly, or known allergy.
• Individuals with no apparent oro-facial anomaly, no hearing or speech impairment, and no reading or language difficulties were included.
• Based on clinical and radiographic evaluations, only patients whose malocclusions were determined to be dental in origin (not skeletal) were selected.
• Patients who did not require maxillary (palatal) expansion were also included in the study.

Exclusion Criteria:

• The study excluded patients who had severe periodontal disease, a history of systemic illness, a known allergy to any of the materials used in the study, poor oral hygiene, insufficient cooperation, or who did not agree to attend regular follow-up appointments during the study period.

Additionally, individuals with craniofacial anomalies or skeletal-origin malocclusions were not included. Participants with hearing impairments, non-native Turkish speakers, or those with any disease or history of surgery that could affect voice or speech quality were also excluded from the study.

The study population consisted of systemically healthy children aged 6-12 years who presented to the Clinics of the Departments of Pediatric Dentistry and Orthodontics at Marmara University Faculty of Dentistry with an initial need for orthodontic treatment.

De-identified individual participant data (including intraoral photographs and clinical evaluation scores) may be shared in scientific publications or presentations. Data will be limited to information relevant for scientific analysis and will not include any personal identifiers.

De-identified individual participant data (IPD), along with supporting documents such as the study protocol and statistical analysis plan, will be available beginning 6 months after publication of the primary study results and will remain available for 5 years following the publication date.

Requests for access to de-identified individual participant data and supporting documents will be considered for academic or scientific research purposes. Interested researchers must submit a written proposal detailing the planned analysis, including objectives and statistical methods. Requests will be reviewed by the principal investigator and institutional review board (IRB) representatives to ensure ethical compliance and scientific merit. A data use agreement must be signed prior to data release. Requests can be submitted via email to the corresponding author listed in the publication.