Background: Successful root canal treatment depends on the synergy between mechanical instrumentation and chemical disinfection. The internal canal geometry, particularly taper configuration, critically influences irrigant flow and penetration. Conventional taper designs tend to displace irrigants coronally, creating stagnation zones and limiting cleaning efficacy. The MEA Inverse Taper^® technique introduces a reversed taper geometry designed to retain irrigant within the canal during shaping, forming a fluid reservoir termed the Radicular Tank (RT). This proof-of-concept study aimed to experimentally demonstrate the formation of the RT generated by the MEA Inverse Taper^® design and to compare its qualitative hydrodynamic and shaping behavior with a conventional rotary system (MTWO). Methods: Standardized transparent canal models were instrumented using either the MEA Inverse Taper^® or MTWO sequence. A 1% methylene blue dye served as a visual tracer to assess potential intracanal retention at successive shaping stages. Standardized photographic documentation and digital image superimposition were used to evaluate residual dye retention, canal morphology, and taper variation. Results: The MEA Inverse Taper^® sequence maintained residual dye in the coronal and middle thirds, confirming the formation of the RT. Compared with MTWO, it produced a more conservative taper, minimized coronal and apical displacement of dye, and preserved canal curvature, removing less coronal dentin. Conclusion: The MEA Inverse Taper^® technique creates a qualitative dye-retention phenomenon (Radicular Tank) that allows continuous instrumentation within a visually persistent dye environment. This novel concept may support disinfection efficiency, alongside preserving dentin structure and reducing mechanical stress on rotary instruments, representing a potential advancement in endodontic shaping and irrigation protocols.

Background/Objectives: Single-retainer Maryland adhesive restorations provide a minimally invasive fixed option for replacing missing anterior teeth in young patients. When congenital absence of a maxillary lateral incisor is associated with a contralateral conoid lateral incisor, the clinical problem extends beyond tooth replacement to bilateral symmetry management. This case report describes a digital-restorative workflow combining a single-retainer lithium disilicate Maryland adhesive restoration with a pontic-derived stamp technique for contralateral symmetry correction. Methods: A medically healthy 13-year-old patient presented with congenital absence of the maxillary left lateral incisor (FDI 22; Universal 10) after orthodontic treatment and had been wearing a removable appliance to replace the single missing tooth. The contralateral maxillary right lateral incisor (FDI 12; Universal 7) presented with conoid morphology, further compromising anterior symmetry. Clinical assessment confirmed ideal mesiodistal space at FDI 22, a vital and unrestored FDI 21 with intact enamel and healthy periodontal support, and the absence of abnormal overjet, overbite, or excursive contact pattern. Based on the findings, a single-retainer Maryland adhesive restoration was fabricated from lithium disilicate (IPS e.max CAD) and bonded to the maxillary left central incisor (FDI 21; Universal 9) using an enamel-only preparation and adhesive cementation protocol. The fixed restoration was combined with a pontic-derived stamp workflow to guide direct composite reshaping of the contralateral conoid lateral incisor. Results: At 1-year follow-up, no debonding, sensitivity, marginal discoloration, or soft-tissue inflammation was observed. The contralateral composite reshaping remained clinically stable, and the patient and guardian reported improved comfort and esthetic satisfaction compared with the previous removable appliance. Conclusions: This case suggests the short-term clinical feasibility of combining a single-retainer lithium disilicate Maryland adhesive restoration with a pontic-derived stamp workflow to achieve minimally invasive tooth replacement and contralateral symmetry correction. Longer follow-up and broader case series are required to confirm the long-term predictability and reproducibility of this approach.