The periodontal phenotype influences treatment outcomes across dental specialties, as tissues of different thickness respond differently to chemical, bacterial, and mechanical insults. In pediatric patients, understanding the gingival phenotype is particularly relevant: a thin phenotype may predispose to dehiscence, fenestration, and gingival recession-especially at the mandibular incisors-when tooth movement exceeds the biological limits of the bony housing.

During the mixed dentition phase, significant changes in soft and hard tissues affect tooth position and periodontal stability, making early phenotype assessment essential. Interceptive orthodontics can reduce the long-term risk of mucogingival defects; early identification of a thin biotype allows for preventive strategies, including soft tissue grafting before critical orthodontic movements.

No studies have examined the association between dental crowding severity and periodontal phenotype in children. Adult data remain inconsistent: Kaya et al. found no correlation between phenotype and skeletal malocclusion, while Kong et al. reported a site-specific association between thin biotype and skeletal Class I/III at the mandibular central incisor. No predictive model exists for periodontal risk related to severe crowding in childhood.

This study aims to assess the periodontal phenotype in pediatric patients across different stages of dental transition and to investigate a possible association between a thin periodontal biotype and severe dental crowding.

Background and Rationale

The periodontal phenotype-defined by the bucco-lingual thickness of the gingiva, the width of keratinized tissue, and the underlying bone morphology-plays a central role in the response of periodontal tissues to orthodontic forces, bacterial insults, and restorative or surgical procedures. Thin-scalloped phenotypes are associated with a higher risk of gingival recession, dehiscence, and fenestration, especially when teeth are moved beyond their bony envelope.

During the mixed dentition phase, significant changes occur in both soft and hard tissues as part of the normal development of the stomatognathic system. These changes may affect tooth position and the stability of periodontal tissues, making evaluation of the gingival phenotype particularly relevant in pediatric patients. Mandibular incisors have been identified as the most vulnerable teeth for the development of labial gingival recession following orthodontic treatment.

Interceptive orthodontics aims to prevent or limit the severity of malocclusions at an early age. Early identification of a thin gingival phenotype enables clinicians to consider preventive measures-such as restricting tooth movement within biological limits or planning soft tissue augmentation procedures prior to critical orthodontic movements.

Genetic, anatomical, and functional factors influence the gingival response to orthodontic forces; therefore, personalized orthodontic planning that integrates periodontal assessment is essential for long-term treatment outcomes and periodontal health.

Gap in the Literature

No studies currently available in the literature have evaluated the relationship between the severity of dental crowding and the periodontal phenotype in pediatric patients. Data in the adult population remain inconsistent: Kaya et al. found no correlation between gingival phenotype and skeletal malocclusion in adults, while Kong et al. reported an association between a thin biotype and skeletal Class I and III, specifically at the left mandibular central incisor, as well as a significant association between thin phenotype and normodivergent and hypodivergent patterns. No predictive model currently exists for identifying patients at periodontal risk due to severe crowding in childhood.

Study Objectives

Primary objective: To assess the periodontal phenotype in pediatric patients at different stages of dental transition (early, middle, and late mixed dentition) and to investigate the association between a thin periodontal biotype and severe dental crowding.

Secondary objectives: To evaluate the distribution of periodontal phenotype subtypes across different stages of dental development; to identify potential clinical predictors of a thin phenotype in the pediatric population; and to provide preliminary data for future longitudinal studies on periodontal outcomes in patients undergoing interceptive orthodontic treatment.

Study Design

This is a cross-sectional, observational study conducted in pediatric patients presenting for routine dental examination. Periodontal phenotype will be assessed using validated clinical and/or ultrasound-based methods. Dental crowding will be classified according to standard indices. Data on dental development stage, skeletal pattern, and relevant clinical variables will be collected. Statistical analyses will include descriptive statistics and appropriate tests of association.

Inclusion Criteria:

• Pediatric patients attending the Pediatric Dentistry and/or Orthodontics clinic (consultation and/or outpatient appointment).
• Parents and/or legal guardians have signed the informed consent for participation in the study.
• Age between 5 and 16 years.
• Clinical dentition criteria by group:

Group 1 (Primary Dentition): Presence in the mandibular arch of deciduous teeth from canine to canine. Group 2 (Early Mixed Dentition): Presence in the mandibular arch of at least two permanent mandibular incisors, fully erupted (incisal edge at occlusal level) or partially erupted (≥50% of the crown), with no clinical attachment loss, and healthy gingiva or mild gingivitis (Gingival Index, GI ≤ 1). Group 3 (Late Mixed Dentition): Presence in the mandibular arch of all four permanent mandibular incisors fully erupted (incisal edge at occlusal level), with no clinical attachment loss, and healthy gingiva or mild gingivitis (GI ≤

1). Group 4 (Permanent Dentition): Presence in the mandibular arch of all four permanent mandibular incisors fully erupted (incisal edge at occlusal level), with no clinical attachment loss, and healthy gingiva or mild gingivitis (GI ≤ 1).

Exclusion Criteria:

Patient-related:

• Parents and/or legal guardians have not signed the informed consent.
• Patients who are not sufficiently cooperative to allow a routine dental examination.
• Non-cooperative patients, including those with special needs.
• Children with systemic diseases or undergoing medication that affects gingival tissues.
• Patients who have already undergone orthodontic treatment or are currently undergoing orthodontic treatment.

Tooth-related:

• Presence of dental agenesis or dental anomalies.
• Dental sites with mucogingival problems.

Pediatric population of both sexes, aged between 5 and 16 years.