Evaluation of the Effect of Adenoid Hypertrophy on the Masseter Muscle in Children: A Comparative Ultrasonographic Study

The masseter muscles of both groups will be evaluated using a LOGIQ S8 R4 ultrasound device with a 9L linear probe. All participants will be examined in the supine position. The probe will be placed:

Transversely: Along a line extending from the oral commissure to the ear tragus Longitudinally: Perpendicular to the mandibular body The thickness of the right and left masseter muscles will be measured in millimeters, both at rest and during maximum clenching, from the thickest region of the muscle.

Internal echogenic bands will be classified into three types:

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

Evaluations will be conducted with children in maximum intercuspation. Primary molar occlusion (mesial step, distal step, flush terminal plane) will be recorded in children with primary dentition. Angle's classification (Class I-III) will be used in children with fully erupted permanent first molars.

Primary occlusal classification will be based on the distal surfaces of the second primary molars. In a mesial step, the distal surface of the mandibular second primary molar is mesial to that of the maxillary molar. In a distal step, it is distal. In a flush terminal plane, the distal surfaces are aligned.

Angle's classification will be recorded as follows: Class I, the mesiobuccal cusp of the mandibular first permanent molar aligns with the mesiobuccal groove of the maxillary molar; Class II, the cusp is distal to the groove; Class III, the cusp is mesial to the groove.

Participants will be seated in an upright position, with the head aligned parallel to the Frankfort horizontal plane. Measurements will be performed in maximum intercuspation.

Overjet (Horizontal Measurement): The distance will be measured by drawing a perpendicular line from the incisal edge of the upper central incisor to the labial surface of the lower central incisor. A periodontal probe will be used, and the values will be recorded in millimeters (mm).

Overbite (Vertical Measurement): The vertical distance between the incisal edges of the upper and lower central incisors will be measured along the labial surface of the lower incisor using a periodontal probe and recorded in millimeters (mm).

If the upper or lower central incisors are missing or severely malpositioned, the measurements will be recorded as "not assessable."

The adenoid hypertrophy grade will be determined according to the degree of nasopharyngeal airway obstruction observed during otorhinolaryngological examination at Aydın Adnan Menderes University Faculty of Medicine, Department of Otorhinolaryngology, and will be classified into four grades. The participants with adenoid hypertrophy will consist of patients who were examined at the same department and scheduled for surgery. The degree of nasopharyngeal airway obstruction by the adenoid tissue will be assessed using endoscopic examination.

Grade 1: Adenoid tissue occupies 0-25% of the nasopharyngeal airway; airway mostly patent, minimal or no obstruction.

Grade 2: Occupies 26-50%; mild obstruction possible, nasal breathing generally intact.

Grade 3: Occupies 51-75%; moderate obstruction, mouth breathing and snoring may occur.

Grade 4: Occupies 76-100%; severe obstruction, marked mouth breathing, possible sleep-disordered breathing.

Mouth breathing will be assessed through both clinical observation and parental reporting. During clinical observation, children will be evaluated in an upright position at rest. The principal investigator will assess whether the child maintains lip closure and whether breathing occurs through the mouth. In addition, parents will be asked whether their child usually breathes through the mouth or nose during both wakefulness and sleep.

Mouth breathing present (Yes): If the child breathes through the mouth at rest or if parents report that the child predominantly breathes through the mouth.

Mouth breathing absent (No): If the child breathes through the nose at rest and parents do not report mouth breathing.

The number of carious, missing, and filled teeth will be determined through clinical and radiographic examination.

Bruxism will be assessed based on both parental reporting and clinical examination. Parents will be asked whether they have observed their child grinding or clenching their teeth during sleep or while awake. Clinical indicators such as abnormal tooth wear, masticatory muscle tenderness, and soft tissue signs (e.g., linea alba) will also be recorded to support the diagnosis.

Bruxism present (Yes): If either parental report or clinical signs are observed.

Bruxism absent (No): If neither parental reporting nor clinical signs are present.