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.