Ali Abulkasim Mohamed

Objective: CAD-CAM technology enables biomimetic dentistry by producing highly accurate, minimally invasive restorations that replicate the biomechanical behavior of intact teeth. This study evaluated the fracture resistance of overlays with margins at different supragingival levels, including a flat occlusal design and compared them with conventional full crowns. All restorations were fabricated from chairside CAD/CAM resin-matrix ceramic for maxillary premolars. Methods and Materials: Sixty-four CAD/CAM resin-matrix ceramic restorations were fabricated and randomly assigned to four groups (n = 16): (1) overlay with a margin 2 mm above the gingiva (Ov2m); (2) overlay with a 4 mm supragingival margin (Ov4m); (3) overlay with a 4 mm margin and flat occlusal surface (OvF4m); and (4) full-coverage crown with a gingival-level margin (FCC). Preparations were standardized by one operator. Restorations were adhesively cemented to resin dies, thermocycled 10,000 times (5–55 °C), and loaded to failure in a universal testing machine (1 mm/min). Data were analyzed using one-way ANOVA and post hoc tests (α = 0.001). Results: Among overlays, Ov2m showed the highest fracture resistance (1605 ± 88 N), followed by Ov4m (1403 ± 63 N). OvF4m recorded the lowest value (1257 ± 73 N). FCC exhibited the greatest overall resistance (1838 ± 106 N), significantly higher than that of any overlay group. Conclusions: Overlays with margins 2 mm above the gingiva had higher fracture resistance than those with more coronal margins or flat occlusal designs. Full-coverage crowns showed the greatest strength, highlighting the impact of margin position and preparation design on restoration performance.

Background: Replacing a maxillary central incisor and immediately placing an implant represents a clinical challenge. Methods: This case report demonstrates a full digital workflow to achieve a predictable implant placement and esthetically pleasing restoration for a 35-year-old male patient who suffered a horizontal root fracture after a sports accident. The patient’s treatment included digital implant planning, minimally traumatic tooth extraction, computer-guided implant placement, soft tissue augmentation, and a provisional restoration to contour the augmented gingival tissues. The process began with cone beam computed tomography (CBCT) evaluation and patient consultation on treatment options, with the patient opting for implant therapy. Using a 3D-printed surgical guide, the implant was placed precisely, and a soft tissue graft was used to enhance the gingival architecture and volume. A provisional restoration was designed to support the emergence profile and condition the peri implant soft tissues. A final digital impression was made, and a screw-retained all-ceramic crown was fabricated uneventfully after healing. Results: This digital approach allowed accurate planning and allowed the efficient execution of a technique-sensitive procedure such as immediate implant placement, thus providing an esthetic and functional solution while minimizing treatment time. Conclusions: The case highlights that immediate implant therapy in the esthetic zone requires meticulous planning and execution, and that incorporating advanced digital tools and techniques is required to achieve favorable clinical outcomes.