Background and Objectives: Professional ballet dancers endure high occlusal loads, increasing cervical defect prevalence. Conventional composites fail frequently under such conditions. This randomized clinical trial (RCT) compared 24 month performance of a polymer infiltrated ceramic network (PICN, VITA Enamic) versus a self curing bioactive composite (Stela) for cervical restorations. Materials and Methods: Twenty professional ballet dancers (40 cervical defects: 21 carious, 19 abfraction) were enrolled in a split mouth RCT. Each received one PICN inlay and one self curing composite restoration on two non adjacent defects. Restorations were assessed at 6, 12, and 24 months using United States Public Health Service (USPHS) criteria (primary: marginal integrity) and a dye penetration test. Secondary outcomes included secondary caries, hypersensitivity, and Oral Health Impact Profile-14 (OHIP 14). Statistical tests: McNemar, Fisher's exact, Kaplan-Meier, log rank (α=0.05). Results: At 24 months, no PICN restoration failed (0%). Self curing composite failures were 20% (carious) and 30% (abfraction) (exploratory uncorrected p=0.031; non significant after correction). Dye penetration was lower for PICN in abfraction defects (11% vs. 60%, adjusted p=0.048) but not in carious defects (9% vs. 30%, adjusted p=0.317). Kaplan-Meier survival favoured PICN (log rank p=0.001); 24 month survival probability: PICN 100% (95% CI: 83-100%), self curing composite 75% (95% CI: 55-95%). No secondary caries or serious adverse events occurred. Conclusions: PICN hybrid ceramic provided superior marginal integrity and zero failures over 24 months in cervical restorations of professional ballet dancers, outperforming the self curing composite. PICN inlays are recommended for abfraction defects. The self curing composite may be considered for carious defects when light curing is problematic, but patients should be informed of higher failure risk. Longer studies are needed.

This prospective, split-mouth, randomized controlled trial was conducted at the Centre for Sports and Ballet Trauma and Rehabilitation of the Priorov National Medical Research Centre of Traumatology and Orthopaedics (Moscow, Russian Federation) in collaboration with the Borovskiy Institute of Dentistry, Sechenov University. The protocol was approved by the Local Ethics Committee of Sechenov University (Protocol No. 22-21, 9 December 2021) and followed CONSORT 2010 and OHStat guidelines.

Participant recruitment and screening:

Professional ballet dancers (current or retired, ≥10 years of professional experience, aged 18-50 years) were screened for the presence of at least two non-adjacent cervical defects (Class V carious or abfraction) located in different quadrants. Each defect had a depth ≥1.5 mm and width ≤4 mm. Teeth had to be vital, with probing depth ≤3 mm and no pulpal pathology. Exclusion criteria included severe bruxism requiring occlusal splint, uncontrolled systemic disease, pregnancy/lactation, known allergy to study materials, and inability to attend follow-up.

Randomization and blinding:

A computer-generated randomization sequence (1:1 allocation, block size 4) assigned the two materials to the two defects within each participant. Allocation was concealed using sequentially numbered, opaque, sealed envelopes opened immediately before the procedure. Participants and the outcome assessor (calibrated dentist) were blinded to material assignment; the operating dentist could not be blinded due to handling differences.

Restorative procedures (detailed):

All restorations were placed by a single operator under local anesthesia (4% articaine with epinephrine 1:100,000).

PICN group (VITA Enamic): After minimally invasive cavity preparation (caries removal and etching for carious defects; no preparation for abfraction), a polyvinyl siloxane impression was taken. PICN inlays were fabricated in a dental laboratory. At a second visit, the inlay was bonded with dual-cure resin cement (G-CEM ONE) following the manufacturer's instructions.

Self-curing composite group (Stela, SDI): The two-step protocol was applied: Stela Primer for 15 seconds, followed by bulk placement of Stela (single increment). No light curing was used. After setting, finishing was performed with fine diamond burs and polishing discs.

Outcome assessment schedule:

Patients were recalled at 6, 12, and 24 months post-restoration. Two calibrated, blinded examiners (intra-examiner kappa=0.86, inter-examiner kappa=0.82) independently assessed:

Marginal integrity using modified USPHS criteria (Alpha, Bravo, Charlie, Delta; failure = Charlie or Delta).

Dye penetration (Borovsky-Aksamit test): 2% methylene blue applied for 2 minutes, rinsed, and scored as present/absent.

Secondary caries (clinical + radiographic).

Postoperative hypersensitivity (Visual Analogue Scale, 0-100 mm).

Oral Health Impact Profile-14 (OHIP-14) at baseline, 6, 12, and 24 months.

Statistical analysis summary (detailed):

Paired binary outcomes were analyzed using McNemar's test with Holm-Bonferroni correction across three time points (α=0.017) and two co-primary outcomes (α=0.025). Fisher's exact or chi-square tests were used for group comparisons. Kaplan-Meier survival curves with log-rank test compared restoration survival. Subgroup analyses by defect type were exploratory; uncorrected p-values are reported. Sample size (40 defects, 20 per material) was calculated a priori (G*Power) to detect a 30% difference in marginal defects with 80% power, assuming 20% dropout (actual dropout 0%). Analyses followed intention-to-treat.

Data management:

Anonymized data are stored at Sechenov University. No missing data occurred. The dataset is available from the corresponding author upon reasonable request and ethics approval.

Inclusion Criteria:

• Current or retired professional ballet dancer with at least ten years of professional experience
• Age 18 to 50 years
• At least two non-adjacent cervical defects (Class V carious lesions or abfraction defects) located in different quadrants
• Each defect depth ≥1.5 mm and width ≤4 mm
• Teeth are vital, free of active periodontal disease (probing depth ≤3 mm), and without clinical or radiographic signs of pulpal pathology

Exclusion Criteria:

• Severe bruxism requiring occlusal splint therapy
• Uncontrolled systemic diseases (e.g., diabetes mellitus, autoimmune disorders)
• Pregnancy or lactation
• Known allergic reactions to any component of the restorative materials (PICN or Stela composite)
• Inability to attend scheduled follow-up visits (6, 12, 24 months)