Biomechanical effect of a zirconia dental implant-crown system: a three-dimensional finite element analysis.

PURPOSE: The objective of this study was to analyze and compare the stresses in two different bone-implant interface conditions in anisotropic three-dimensional finite element models (FEMs) of an osseointegrated implant of either commercially pure titanium or yttrium-partially stabilized zirconia (Y-PSZ) in combination with different superstructures (gold alloy or Y-PSZ crown) in the posterior maxilla. MATERIALS AND METHODS: Three-dimensional FEMs were created of a first molar section of the maxilla into which was embedded an implant, connected to an abutment and superstructure, using commercial software. Two versions of the FEM were constructed; these allowed varying assignment of properties (either a bonded and or a contact interface), so that all experimental variables could be investigated in eight groups. Compact and cancellous bone were modeled as fully orthotropic and transversely isotropic, respectively. Oblique (200-N vertical and 40-N horizontal) occlusal loading was applied at the central and distal fossae of the crown. RESULTS: Maximum von Mises and compressive stresses in the compact bone in the two interfaces were lower in the zirconia implant groups than in the titanium implant groups. A similar pattern of stress distribution in cancellous bone was observed, not only on the palatal side of the platform but also in the apical area of both types of implants. CONCLUSION: The biomechanical parameters of the new zirconia implant generated a performance similar to that of the titanium implant in terms of displacement, stresses on the implant, and the bone-implant interface; therefore, it may be a viable alternative, especially for esthetic regions.

Segmental osteotomy to reposition multiple osseointegrated dental implants in the anterior maxilla in a trauma patient.

A 16-year-old young man had severe loss of alveolar bone and lost four teeth in the anterior maxilla because of traumatic injury in a traffic accident. To overcome the surgically compromised condition for implant rehabilitation, the deficient ridge was augmented by autogenous bone graft from the mandibular symphysis. The augmented ridge had much improvement in width but less in vertical height. Four implants were placed to gain initial osseointegration. Segmental osteotomy was performed to occlusally reposition the implants and bone for 5-mm in the anterior maxilla. After 2 years of clinical follow-up, the rehabilitation outcome is satisfactory and stable.

A method using vestibulo-sulcoplasty combining a split-thickness skin graft and a palatal keratinized mucosa graft for peri-implant tissue secondary to oral cancer surgery.

Twelve patients presented with oral submucosal fibrosis and loss of keratinized gingiva in a compromised vestibule of a severely deficient mandibular edentulous ridge secondary to oral cancer surgery. They received implant rehabilitation with a total of 49 fixtures without major bone graft augmentation. To overcome vestibular compromise, soft tissue management consisting of simultaneous vestibulo-sulcoplasty, split-thickness skin graft (STSG), and palatal keratinized mucosa graft (KMG) was performed as a second stage when healing abutment was transferred to replace the cover screw of the dental implant. Postoperative follow-up of all patients consisted of clinical and radiographic examinations for an average of 4 years, revealing good stability of implant fixtures with a 91.8% success rate and generally healthy peri-implant tissue, the latter with an average sulcus depth of 2.9 +/- 0.6 mm. Satisfactory results were also demonstrated regarding improved morphology of the vestibule, cosmetics, and prosthetic functionality. Vestibulo-sulcoplasty combining STSG and palatal KMG offers a stable and convenient method for rebuilding peri-implant tissue without need for bone grafting in selected patients who have compromised atrophic ridges secondary to cancer surgery.

Reconstruction of the severely resorbed atrophic edentulous ridge of the maxilla and mandible for implant rehabilitation: report of a case.

We describe a case with a severely resorbed atrophic edentulous ridge in both the maxilla and mandible. The maxilla was reconstructed using a sinus-lifting procedure and onlay bone graft. The mandible was reconstructed by anterior osteotomy with an interpositional sandwich iliac bone graft at the symphysis area, subperiosteally with iliac bone chips mixed with hydroxylapatite bilaterally at the posterior atrophic ridge, and vestibuloplasty with a split thickness skin graft (STSG). After full-mouth implant rehabilitation, a 5-year follow-up of this case shows a satisfactory result.

Transpositioned flap vestibuloplasty combined with implant surgery in the severely resorbed atrophic edentulous ridge.

The use of transpositioned flap (lipswitch) vestibuloplasty combined with implant surgery in patients with severely resorbed atrophic edentulous ridges is reviewed. The cases of 17 patients with severely resorbed atrophic edentulous ridges at the mandible undergoing implant rehabilitation were reviewed. Lipswitch vestibuloplasty was followed immediately by the implant surgery. Postoperative follow-up consisted of clinical and radiographic examinations. Seventeen patients with atrophic ridges (12 class II and 5 class III) each had 2 implant fixtures placed in the mandible as abutments for a clip and bar overdenture. The average time of follow-up was 6 years. Before surgery, all patients had severely atrophic ridges with a compromised shallow vestibule of varying degrees. Satisfactory results were observed in regard to the immediate and long-term morphology of the vestibule, the health of the peri-implant tissue, the stability of implant fixtures, and the functionality of the prostheses. The lipswitch vestibuloplasty offers a safe and convenient method of surgical access for implant fixture installation, with the advantage of rebuilding the vestibule of a compromised atrophic ridge in the anterior mandible.

Rehabilitation of dental implants for the post-irradiated and marginally resected mandible in an oral cancer patient.

We describe a case with severely compromised edentulous ridge in the mandible, which previously received marginal resection and radiotherapy due to oral cancer at the mouth floor. Through careful evaluation, the patient had 30 dives of hyperbaric oxygen therapy (HBO) before implant surgery. The edentulous ridge was rehabilitated with 4 endosteal implant fixtures, and palatal mucosa grafting vestibulosulcoplasty. The case had been followed for 4 years with stability of bone and a satisfactory result of rehabilitation.