Clinical guidelines for rehabilitation of the severely atrophic maxilla using extended-length subcrestal angulated implants and modified trans-sinus nasal protocol: A case report

Aims: Immediate fixed full-arch implant-supported prosthetic rehabilitation of the severely atrophic maxilla is a challenging treatment modality with favourable patient interest. The delivery of the treatment is challenging due to the difficulty in providing adequate posterior implant positioning with high primary stability in the absence of alveolar bone distal to the maxillary lateral incisors. Current trends in posterior implant placement and immediate loading include the placement of zygomatic implants or distally tilted implants placed anterior to the sinus cavity. The development of an extended-length subcrestal angulated implant gives an additional option to provide posterior occlusal support for reconstruction of the severely atrophic maxilla with an immediate full-arch fixed prosthesis. Materials and methods: This article describes a trans-sinus nasal protocol for fixed full-arch rehabilitation in the severely atrophic maxilla when the residual alveolar bone does not extend distally from the permanent maxillary lateral incisors. The extended-length distally tilted implant transverses a simultaneously augmented sinus cavity and engages the anterior maxilla and bone of the lateral nasal wall. Results: The placement of an extended-length distal tilted implant placed the implant head at the crest of the alveolar ridge in the first permanent molar position, promoting favourable prosthetic biomechanics for a full-arch fixed prosthesis. Passivity of fit of the fixed prosthesis was achieved due to the 24-degree subcrestal angulation feature of the implant and use of multi-unit abutments. Conclusions: The use of extended-length subcrestal angulated implants provides surgical and prosthetic advantages for immediate fixed rehabilitation of the severely atrophic maxilla. It is potentially an alternative to the placement of zygomatic implants.