Managing a complex anterior mandibular defect: a step‑by‑step case report

A 52‑year‑old female patient presented to our clinic seeking a second opinion for an infection in the lower anterior mandible. Referred by her sister, a current patient, she was unaware of the severity of the condition until both concerns about esthetics and was open to exploring advanced treatment options.

Clinical and radiographic assessment revealed a large granuloma on teeth #41, along with significant horizontal and vertical bone loss. The defect was more pronounced on the mesial aspect of tooth #42, though tooth #31 was also affected. Both adjacent teeth showed signs of compromise, prompting the need for an interdisciplinary plan to eliminate infection, restore bone and soft tissue, and maintain esthetic integrity throughout the process.

A–B Initial situation

Surgical planning and site challenges

The mandibular anterior zone presents several unique challenges for implant therapy. Narrow mesio-distal spacing and slender natural root anatomy demand precise planning and surgical execution. Additionally, the prosthetic solution must closely replicate the natural emergence profile and dimensions of the original teeth to ensure a natural-looking result.

After a thorough assessment, we decided to extract tooth #41 and to perform guided bone regeneration (GBR) using a cross xenogenic collagen bone graft material. To maintain esthetics and tissue contour, a composite provisional was placed immediately after extraction, followed by a temporary bridge restoration during the healing phase.

C GBR final situation D Preparation for provisional restoration E Provisional restoration on top of teeth before implant placement

Implant selection and transmucosal strategy

To meet the demands of this anatomically constrained site, the Nobel Biocare N1™ implant system was selected. Its slim platform and internal conical connection offered a critical advantage. Unlike traditional abutments, which can be bulky and incompatible with the narrow anterior roots, the Nobel Biocare N1 system provides a smaller prosthetic base and a tight seal at the implant abutment junction. These features are critical in minimizing soft tissue disruption and promoting bone preservation.

A 2.5 mm high base was chosen to serve as a transmucosal scaffold,1 enabling simultaneous bone grafting with creos™ xenogain collagen above the implant platform. This approach allowed for the reconstruction of the socket defect on both #31 and #42, particularly targeting the buccal and interproximal areas, without the need to disconnect the prosthetic component at the implant level. Maintaining the transmucosal base during the healing period helps preserve the graft volume and supports long-term esthetic outcomes. Following this phase, a connective tissue graft harvested from the tuberosity was placed crestally to optimize soft tissue volume and integration.

F. Implant placement.

G. creos xenogain collagen packing between implant and socket wall.

H. Insertion of the 2.5 mm Nobel Biocare N1™ Base on the Nobel Biocare N1™ implant.

I. Crestal placement of the tuberosity connective tissue graft.

J. Tuberosity CTG sutured crestally under tunneled flap and incision to access base head for prosthetics.

K. Adaptation of the provisional abutments.

L. Provisional relined onto implants

M. Final result after suturing

Healing and final reconstruction

An eight-month healing period was planned to allow for full tissue maturation. The final prosthetic design was carefully modified to replicate the natural diameter and seal of the original tooth roots, aiming to enhance both soft tissue architecture and gingival levels around the restoration. To achieve this, individual screw-retained zirconia abutments were first designed to mimic the emergence profile and gingival seal of the extracted roots, allowing for a biologically harmonious transition from implant to soft tissue. Subsequently, a three-unit bridge was constructed and bonded onto the zirconia abutments. This screw-cement-retained hybrid design was selected to optimize both white esthetics and soft tissue support. The use of zirconia as the core material not only allowed for high translucency and natural appearance but also contributed to biocompatibility and tissue stability over time.

Patient outcome

Immediate implant protocols in the esthetic zone  require thorough planning and execution in the  proper sequence.² This case shows how precise surgical planning,  appropriate choice of biomaterials, and implant  system design converge to successfully manage  complex anterior defects. By addressing biological,  functional, and esthetic demands in a coordinated  way, we can deliver predictable and visually pleasing  outcomes, even in the most challenging areas of the  mouth.

N. Situation at 6 months for final impression

O. Inconspicuous implant bridge

P. X-ray sequence of the different stage

Q. Zirconia crown, transmucosal abutment, and implant (Nobel Biocare N1 system).