This cross-sectional study aims to evaluate how interdental spacing and crown width discrepancies in primary dentition influence the perception of smile esthetics. Standardized smile photographs obtained from children with physiologic spacing patterns will be digitally modified to create different dental scenarios, including variations in interdental spacing, midline deviation, and crown width discrepancies. The images will be presented to adult participants, including dental students and parents, who will evaluate the esthetic appearance of each smile using a visual analog scale (VAS). The study seeks to determine how different spacing patterns and tooth size discrepancies affect the perception of smile esthetics in primary dentition.

This cross-sectional study was designed to evaluate the impact of interdental spacing and crown width discrepancies in primary dentition on the perception of smile esthetics. The study design was developed based on previously published studies that assessed smile esthetics using digitally modified photographs.

Selection of Photographic Samples and Photography Protocol:

Smile photographs will be obtained from two cooperative children in the primary dentition stage who present with healthy anterior teeth and no caries, restorations, enamel defects, history of trauma, or other dental pathology. One child will present with physiologic interdental spacing representing ideal primary dentition (Baume Type I), and the other will present with contact relationships without physiologic spacing (Baume Type II) but without crowding. Prior to photography, written informed consent will be obtained from the parents both for participation in the study and for the use of smile photographs showing the region between the tip of the nose and the lower border of the chin. Standardized smile photographs will be taken under controlled conditions to ensure reliable esthetic evaluation. Images will be captured using a Canon 750D digital camera with a 100-mm macro lens under natural lighting conditions, avoiding direct sunlight, at an approximate distance of 60 cm. Participants will be positioned in natural head position and asked to produce a natural smile with visible teeth. To ensure confidentiality and eliminate distracting facial features, photographs will be cropped between the tip of the nose and the lower border of the chin, and the eye region will be covered with a black bar.

Digital Image Modifications: The original smile photograph representing Baume Type I dentition will be digitally modified using image editing software (Photoshop CC, Version 25.12.0 Mac; Adobe) to create different dental scenarios. The following conditions will be generated:

Baume Type I: Physiologic interdental spacing in the anterior region with a symmetrical and pathology-free appearance.

Baume Type II: Symmetrical appearance with contact relationships between primary incisors and no interdental spacing.

Midline diastema: Presence of a midline diastema with all other teeth in contact.

Midline deviation: General physiologic spacing combined with midline deviations of 1, 2, and 3 mm.

Crown width discrepancy between central incisors: General physiologic spacing with crown width discrepancies of 1, 2, and 3 mm between the central incisors.

Unilateral crown width discrepancy: Asymmetric crown width changes affecting the central incisor, lateral incisor, and canine on one side, with compensatory enlargement on the contralateral side, creating total asymmetry of 1, 2, and 3 mm.

Before digital modifications, measurements will be calibrated using the crown length of a primary central incisor as a reference to ensure standardization of size and proportions across all images. This approach follows methodologies used in previous smile esthetic perception studies.

Presentation of Images: The prepared images will be presented to participants in a randomized order on a single tablet device (HONOR MagicPad 2). Each image will be displayed for 10 seconds, followed by a neutral gray screen with a central fixation point for 4 seconds. This presentation protocol is consistent with previous esthetic perception studies and is intended to minimize visual adaptation and ensure independent evaluation of each image.

Participants and Esthetic Evaluation: The images will be evaluated by adult participants aged 18 years and older. Participants will be divided into two groups: 1)Dental students (3rd-5th year students). 2)Parents

This grouping is based on previous studies indicating that esthetic perception may vary depending on the observer group. Smile esthetic perception will be assessed using a Visual Analog Scale (VAS), a validated and reliable method for evaluating esthetic perception. Participants will be asked to rate the esthetic appearance of each smile using a 0-100 mm VAS, where 0 represents "very unattractive" and 100 represents "very attractive." Participants will respond to the question: "How esthetic do you find this smile?"

Inclusion Criteria:

• For photographic records (two children):
• Children without any systemic disease
• Children in the primary dentition stage
• Children able to cooperate during the photographic procedure
• Children whose parents or legal guardians have provided written informed consent for participation and for the use of smile photographs
• One child presenting physiologic interdental spacing
• One child presenting no physiologic interdental spacing

For esthetic perception evaluation:

• Third-, fourth-, or fifth-year dental students
• Parents presenting to the Department of Pediatric Dentistry for their children's routine dental treatment
• Individuals who voluntarily agree to participate and provide informed consent

Exclusion Criteria:

• Photographs that do not comply with the standardized photography protocol defined in the study
• Multiple photographs taken of the same teeth or the same tooth surfaces
• Out-of-focus or blurred images
• Images that are overexposed, underexposed, or taken under inadequate lighting conditions
• Photographs with saliva contamination or other artifacts affecting image quality
• Participants who do not complete the evaluation of all images

The study population will consist of adult participants aged 18 years and older, including dental students and parents attending the Department of Pediatric Dentistry for their children's routine dental treatment. Participants will evaluate digitally modified smile photographs representing different interdental spacing patterns and crown width discrepancies in primary dentition using a visual analog scale (VAS).

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.