Developmental defects of enamel and bonding in orthodontics - A scoping review

Background Developmental defects of enamel (DDE) give rise to hypoplastic and/or hypomineralised enamel. The affected enamel responds differently to etch and bonding. There is a need of an overview how to best handle DDE in orthodontic treatment, aspects of shear bond strength and treatment failure. Objectives The objective was to comprehensively map existing literature on DDE and shear bond strength and treatment failure in orthodontics. Methods Reports of primary studies addressing orthodontic treated patients having DDE of treatment failure, treatment time, shear bond-strength (SBS), and bond failure, published in the period 2000-2025, written in English were considered for inclusion in this scoping review. PubMed/MEDLINE, EMBASE, Cochrane Library and Web of Science were searched. The protocol was registered with the PROSPERO International prospective register under registration number PROSPERO 2026 CRD420261283906. Results Sixteen studies were included, 14 (88%) of them being in vitro studies. Dental fluorosis (DF) was the developmental defect of enamel described. All in vitro papers referred to SBS, and there were also reports of ARI (79%). A variety of procedures increased the SBS of teeth with DF; concerning cleaning methods prior etching (43%), etching (50%), or bonding (29%). Most studies (86%) reported SBS above critical threshold of 8 MPa. Mean SBS in DF is approximately 2 MPa lower than normal enamel. Conclusions The current evidence base is limited, with a dominance of studies on dental fluorosis, methodological heterogeneity, and in-vitro shear bond strength. Several pretreatments achieve acceptable SBS in enamel with dental fluorosis, but enamel damage and clinical failure rates remain under-researched.