Accuracy of a flapless protocol for computer-guided zygomatic implant placement in human cadavers: expectations and reality.

BACKGROUND: This work evaluated the accuracy and safety of a protocol for minimally-invasive flapless zygomatic implant placement that uses computer-guided stereolithographic mucosa-supported surgical templates. METHODS: A total of six zygomatic implants were placed in three formalin-fixed human cadaver heads, with edentulous and severely atrophic posterior maxillae. CT scans of each cadaver head were performed after zygomatic implant placement, to evaluate the lateral error (LE) at implant tip and base, and the angular error (AE) of the implant body. RESULTS: Excluding the implant placed outside the drilling channel, the LE at the implant base was less than 1 mm in all cases. The average LE at the tip was 3.86 mm, and the AE was less than 6° in all cases, with an average of 4.5°. CONCLUSION: Computer-guided minimally-invasive flapless zygomatic implant surgery remains challenging. Careful planning and perfect stability of the surgical guide are essential.

Zygomatic implant placement with flapless computer-guided surgery: a proposed clinical protocol.

PURPOSE: The aim of the present report is to describe a procedure for zygomatic implant placement using image-guided implant surgery. This is an innovative technique and includes a new clinical approach to provide the direction to guide drilling. MATERIALS AND METHODS: The ethical committee of the University of Genoa approved the study. All patients had clinical indications of severe maxillary atrophy (Class 4 Cadwood-Howell). A total of 25 implants were placed, of which 17 were in the premaxilla, 7 in the zygomatic area, and 1 in the pterygoid bone. The treatment was performed in 2 phases. The first phase included cone-beam acquisition to exclude sinus disease and evaluate the anatomy of the residual premaxillary bone in 3 dimensions. The success of osseointegration achieved by the primary implants (PIs) was confirmed after temporary loading and before proceeding with the second phase, in which all patients were scheduled for zygomatic implants. A total of 3 or 4 regular platform MK III implants (17 in all) were placed in the premaxilla using conventional implant surgery. A model within the analogs of the PIs was prepared (master model), taking a conventional impression. Next, a radiologic template was prepared on the same master model and stabilized on the PIs, using dedicated prosthetic components. The guide was screwed onto the PIs during computed tomography acquisition to determine a fixed and repeatable position of the guide. In the second phase, after routine planning, a mucosa-supported stereolithographic SurgiGuide with sleeves for the zygomatic implants and the corresponding stereolithographic model, including the mucosa, were received from the manufacturers. The guide was repositioned on the master model to replace the sleeves for the PIs in the same position. With an original customized surgical kit, including an innovative intrasinus device, we next simulated surgery on the stereolithographic model to determine and control the direction of the osteotomies and the final depth of drilling. The SurgiGuide was anchored onto the PIs before the zygomatic osteotomy, after which flapless surgery was performed to place the zygomatic implants according to the plan. RESULTS: Two PIs in the premaxillary area failed (and were replaced before the zygomatic step). No zygomatic implants failed. The follow-up examinations at 4 to 39 months showed good esthetic, phonetic, and functional results. CONCLUSIONS: The results of the proposed surgical procedure appear to be encouraging. Although it is difficult to achieve the correct driven angle of osteotomies for zygomatic implants, in all patients we achieved correct zygomatic positioning, in agreement with previous planning. Additional research and randomized clinical trials are needed to assess the predictability of the procedure.

Accuracy of computer-aided oral implant surgery: a clinical and radiographic study.

PURPOSE: Computer-aided oral implant surgery offers several advantages over the traditional approach. The purpose of this study was to evaluate the in vivo accuracy of computer-aided, template-guided oral implant surgery by comparing the three-dimensional positions of planned and placed implants. MATERIALS AND METHODS: Oral implant therapy was performed in two treatment centers on eligible patients using computerized tomography (CT)-based software planning and computer-aided design/computer-assisted manufacture stereolithographic templates. A second CT scan was obtained after surgery. Preoperative and postoperative CT images were compared (planned vs actual implant positions), and the accuracy of this type of image-guided therapy was assessed. RESULTS: Twenty-five adult patients were included in this retrospective study; 17 (11 partially and eight fully edentulous arches) were treated in center 1, and eight (six partially and two fully edentulous arches) in center 2. Of the 104 implants inserted with the computer-aided method, 100 integrated, giving a cumulative survival rate of 96% (mean follow-up, 36 months). There were no major surgical complications. With regard to accuracy, 89 implants were available for comparison; mean lateral deviations at the coronal and apical ends of the implants were 1.4 mm and 1.6 mm, respectively. Mean depth deviation was 1.1 mm and mean angular deviation was 7.9 degrees. There was a statistically significant correlation in the accuracy of any implants placed with the same guide. There was no difference in accuracy data from the two private centers; nor could a learning curve be demonstrated. CONCLUSIONS: Based upon this clinical study of 25 patients, the following observations were made: (1) computer-aided oral implant surgery used in two treatment centers provided a high likelihood (96%) of implant survival, and (2) deviations from planned implant positions existed in the coronal and apical portions of the implants as well as with implant angulation. Mean deviations were less than 2 mm in any direction and less than 8 degrees.

Maxillary single-tooth replacement utilizing a novel ceramic restorative system: results to 30 months.

This study reports on the first longitudinal results of an alumina (70%)-zirconia (30%) ceramic restorative system for implant-supported, single-tooth replacement in the anterior maxillary jaw. Eighteen patients (9 men, 9 women, mean age = 42.4 years) were treated with 22 implants placed into 19 extraction sockets and 3 residual ridges. Eight implants were immediately loaded with nonoccluding provisional prostheses. All implants were definitively loaded with fully occluding ceramic restorations after osseointegration and soft tissue maturation. Patients were monitored from 7 to 30 months (mean = 18.1 months) after loading. All implants osseointegrated and were successfully restored. One case of abutment screw loosening occurred because of patient parafunction (bruxing), and another patient reported chewing pain attributed to malocclusion. Both problems were successfully resolved without further incidence. Within the context of this study, single-tooth replacement in the anterior maxillary jaw was successfully achieved with alumina-zirconia ceramic single-tooth restorations with up to 30 months of clinical function.

Single-tooth implant restorations in the esthetic zone with PureForm ceramic crowns: 3 case reports.

The anterior maxillary jaw is frequently called the "esthetic zone" because of its high visibility and influence on facial appearance. Implant placement and single-tooth restoration in this region can present some esthetic challenges for the clinician. The underlying titanium abutment, for example, can diminish porcelain translucency and result in a darkened prosthesis. Subsequent changes in soft-tissue margins can also result in the visibility of titanium at the gingival crevice. In recent years, all-ceramic restorations have gained popularity in response to increasing patient demands for improved esthetics. This article describes the clinical use of a new, tooth-shaped, ceramic coping system in the restoration of single teeth in the esthetic zones of 3 patients. Four tapered screw implants were placed in the locations of the central incisors (n = 3) and bicuspid (n = 1). Conventional ceramic protocols were used to fabricate all-ceramic crowns that were cemented onto small core abutments attached to the implants. All prostheses restored the biomechanical needs of the patients and achieved excellent esthetic results.

Immediate tooth extraction, placement of a Tapered Screw-Vent implant, and provisionalization in the esthetic zone: a case report.

PURPOSE: This clinical report describes an immediate tooth extraction, followed by placement and provisional restoration of a dental implant in the prepared socket of a right maxillary central incisor. MATERIALS AND METHODS: The tooth was extracted with minimal hard and soft tissue trauma and without flap reflection. A flapless, transmucosal surgical approach was used to prepare the socket and insert a tapered implant. The implant was immediately restored with a provisional abutment and crown without occlusal contacts. An impression was made 22 days after implant insertion, and a definitive, all-ceramic restoration was placed 3 days later. RESULTS: During the period of provisional progressive loading, no significant soft tissue contraction was observed related to noninvasive operating techniques and the immediate insertion of the provisional restoration. The patient exhibited no clinical or radiologic complications through 8 months of clinical monitoring after loading. CONCLUSION: The Tapered Screw-Vent implant and all-ceramic restoration provided the patient with immediate esthetics, function, and comfort without any complications during the postloading follow-up period.