[Selection of restorative strategies for extensive tooth defects in young permanent molars]

Restoration of extensive defects in young permanent molars is more complex than that in mature permanent teeth. Young permanent teeth are characterized by insufficient enamel mineralization, large pulp chambers, short occlusogingival distance, and unstable gingival margins, limiting both mechanical retention and bonding conditions. In addition, individual factors such as patient cooperation, caries risk, and orthodontic needs further complicate treatment planning. Based on current clinical evidence, this review summarizes the indications, advantages, and limitations of direct adhesive restorations, preformed crowns, provisional crowns, inlays/onlays/overlays, endocrowns, and computer-aided design and computer-aided manufacturing (CAD/CAM) indirect restorations, proposing a clinical decision-making framework for extensive defects in young permanent molars. The proposed pathway follows a "three-level assessment and integrated decision-making" approach, in which the physiological characteristics of young permanent teeth, the objective condition of the affected tooth, and patient-and treatment-related factors are comprehensively evaluated to develop an individualized restorative plan. When moisture control is achievable and tooth conditions are favorable, adhesive restorations with cusp coverage can be selected. When moisture control is difficult or rapid restoration of coronal integrity is required, preformed metal crowns may serve as interim restorations. For non-vital teeth with short occlusogingival distance and insufficient retention, endocrowns may be considered. At present, CAD/CAM resin-ceramic indirect adhesive restorations have shown favorable short-to medium-term outcomes over 18-24 months; however, the long-term performance still requires further validation through multicenter studies with larger sample sizes.