The goal of this observational study is to evaluate the effect of adenoid hypertrophy on the masseter muscle in children aged 3 to 8 years. The primary objectives are:

• To assess whether adenoid hypertrophy affects the thickness or structure of the masseter muscle.
• To determine whether there is a measurable difference in masseter muscle characteristics between children with and without adenoid hypertrophy.

Researchers will compare children diagnosed with adenoid hypertrophy and scheduled for adenoidectomy to healthy controls without adenoid hypertrophy.

Each participant will:

• Undergo ultrasonographic examination of the masseter muscle using a 9L linear probe (6-15 MHz), and
• Have their occlusal relationship, dental findings, age, sex, and adenoid hypertrophy grade recorded.

Hypotheses

H0 (Null Hypothesis): There is no difference in masseter muscle thickness or the visibility of internal echogenic bands between children with adenoid hypertrophy and healthy controls.

H1 (Alternative Hypothesis): There is a difference in masseter muscle thickness or the visibility of internal echogenic bands between children with adenoid hypertrophy and healthy controls.

Sample Size Calculation No prior studies were identified comparing masseter muscle thickness between children with adenoid hypertrophy and healthy controls. The sample size was calculated using G*Power software. Assuming a medium effect size (0.6), an alpha level of 0.05, and a power of 0.80, the required total sample size was determined to be 72 participants.

Ultrasound Evaluation of the Masseter Muscle

Masseter muscle thickness and the visibility of internal echogenic bands will be assessed bilaterally at rest and during maximum clenching (intercuspal position). Evaluations will be performed with participants in the supine position. The ultrasound probe will be placed:

• Transversely: Parallel to the inferior mandibular border along a line connecting the oral commissure and the tragus.
• Longitudinally: Perpendicular to the mandibular body.

Thickness measurements (mm) will be taken from the thickest part of the muscle in both positions. Visibility of internal echogenic bands will be classified as follows:

• Type 1: Clear visibility of thin transverse bands.
• Type 2: Thickened bands with reduced echogenicity.
• Type 3: Disappearance or reduction in the number of bands.

Evaluations will be performed by the investigator (SY) at the Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Aydın Adnan Menderes University.

Clinical Examination The principal investigator (BMA) will record each participant's age, sex, adenoid hypertrophy grade, occlusion type, molar relationship classification, overjet, overbite, number of carious, missing, and filled teeth, and the presence of mouth breathing and bruxism.

Statistical and Analytical Methods Data will be analyzed using SPSS version 19.0 (IBM Corp.). The Kolmogorov-Smirnov test will be used to assess normality of distribution. Categorical variables will be expressed as frequencies and percentages; continuous variables will be presented as means and standard deviations. The independent samples t-test will be used to compare measurement data between groups. The chi-square test will be used to evaluate associations between categorical variables and adenoid hypertrophy.

Inclusion Criteria:

• Children aged between 3 and 8 years
• Children diagnosed with adenoid hypertrophy
• Children without any systemic disease

Exclusion Criteria:

• Children with a history of surgery for adenoid hypertrophy
• Children who are uncooperative during clinical examination
• Children with syndromes involving the maxillofacial region
• Children with multiple missing teeth

Children aged 3 to 8 years, with or without adenoid hypertrophy. The adenoid hypertrophy group will include pediatric patients diagnosed by the Department of Otorhinolaryngology at Aydın Adnan Menderes University Faculty of Medicine and scheduled for surgery. The control group will include healthy children without systemic disease who present to the Department of Pedodontics at Aydın Adnan Menderes University Faculty of Dentistry for routine dental examination.