Clinical Comparison of CAD/CAM Nanohybrid Composite and Hybrid Ceramic Overlays in Children With Molar-Incisor Hypomineralisation

Molar-Incisor Hypomineralization (MIH) is a developmental enamel defect that primarily affects the first permanent molars and frequently the incisors. It is characterized by hypomineralized enamel with increased porosity, discoloration, and a high risk of post-eruptive enamel breakdown. Affected teeth often present with significant sensitivity, posing difficulties in achieving adequate anesthesia and effective bonding during restorative procedures. As a result, the management of MIH-affected molars in pediatric patients is both complex and clinically significant.

This prospective, randomized, split-mouth clinical study was designed to compare two different CAD/CAM materials used in semi-direct onlay restorations for the treatment of MIH-affected molars in children aged 8 to 13 years. The materials under investigation were a nano-hybrid composite block (Grandio blocs, VOCO) and a polymer-infiltrated ceramic network (PICN) hybrid ceramic block (VITA Enamic, VITA Zahnfabrik).

The study enrolled 20 pediatric patients, each presenting with at least two permanent first molars affected by MIH (classified as score 2b/c or 4b/c according to the MIH-TNI criteria). Using a split-mouth design, each patient received both interventions-one molar restored with a hybrid composite block and the other with a hybrid ceramic block. Randomization was performed using a computer-generated sequence. All procedures were carried out by a trained pediatric dentistry resident under rubber dam isolation, following a standardized adhesive protocol.

The restorative process was completed in a single session and followed a fully digital workflow. Teeth were scanned intraorally using the CEREC system, and restorations were designed and milled chairside. Immediate dentin sealing (IDS) was applied prior to cementation. The internal surfaces of the restorations were prepared using appropriate surface treatments such as sandblasting or hydrofluoric acid etching followed by silane application, in accordance with the manufacturers' guidelines. Final cementation was performed using a dual-cure resin cement.

Follow-up evaluations are planned at 6, 12, and 18 months post-operatively. At each time point, clinical assessments are conducted by two calibrated, blinded evaluators using modified United States Public Health Service (USPHS) criteria. These include evaluations of marginal adaptation, surface integrity, anatomical form, marginal discoloration, and the presence of secondary caries. Additionally, thermal sensitivity is assessed using the Schiff Cold Air Sensitivity Scale to monitor changes in dentin hypersensitivity over time.

This study aims to provide comparative data on the mid-term clinical performance of two innovative restorative materials applied in MIH-affected molars using a minimally invasive, digital workflow.

Inclusion criteria

• Children aged between 8 and 13 years
• Presence of at least two permanent first molars affected by MIH
• MIH-affected molars classified as score 2b, 2c, 4b, or 4c according to the MIH-TNI index
• Symmetrical molars suitable for split-mouth comparison
• Cooperative behavior sufficient to allow treatment under local anesthesia
• Signed informed consent obtained from parent or legal guardian

Exclusion criteria

• Presence of systemic or syndromic diseases affecting enamel development
• History of bruxism or parafunctional habits
• Presence of pulp involvement, fistula, or periapical pathology in the target teeth
• Allergies to dental materials used in the study (e.g., resin-based composites, adhesives)
• Participation in another clinical trial within the past 30 days
• Inability to attend scheduled follow-up appointments at 6, 12, and 18 months

Use of medication affecting pain perception or healing process