Identification of the Pathway and Appropriate Use of Four Zygomatic Implants in the Atrophic Maxilla: A Cross-Sectional Study.

PURPOSE: This cross-sectional study aimed to identify and characterize the pathway for appropriate placement of four zygomatic implants in the severely atrophic maxilla and to group the anatomical variations of the osteotomy trajectory for anterior zygomatic implants. MATERIALS AND METHODS: CBCT images of patients presenting indications for the use of four zygomatic implants to withstand a maxillary rehabilitation were reviewed. Cross-sectional planes corresponding to the implant trajectories, designed according to a zygoma anatomy-guided approach for implants placed in the anterior and posterior maxilla, were assessed separately. The relationship of the implant osteotomy trajectory with the correlated residual alveolar bone, nasal and sinus cavities, maxillary wall, and zygomatic bone anatomies was established. RESULTS: The study population included 122 globally recruited patients, with 488 zygomatic implants, 244 of which had their starting point on the anterior incisor-canine area and 244 on the posterior premolar-molar area. The anatomy of the osteotomy path designed for the anterior implants ("A") was named and grouped into five assemblies from zygomatic anatomy-guided ZAGA A-0 to A-4, representing 2.9%, 4.5%, 19.7%, 55.7%, and 17.2% of the studied sites. Percentages for posterior implant ("P") trajectories of the osteotomy were grouped and named as ZAGA P-0 to P-4, representing 5.7%, 10.2%, 8.2%, 18.4%, and 57.4% of the sites, respectively. Approximately 70% of the population presented anatomical intra-individual differences. CONCLUSION: The trajectory of the zygomatic implant followed different anatomical pathways depending on its coronal point being anteriorly or posteriorly located, which justifies a new zygoma anatomy-guided approach classification for anteriorly placed zygomatic implants. Topographic characteristics of the anatomical structures that are cut by an anterior oblique plane joining the lateral incisor-canine area to the zygomatic bone, representing the planned anterior osteotomy path in a quadruple-zygoma indication, have not been previously reported. Adaptation of surgical procedures and implant sections/designs to individual patients' anatomical characteristics is essential to reduce early and long-term complications.

Prospective Multicenter Clinical Cohort Study of a Novel Macro Hybrid Implant in Maxillary Anterior Postextraction Sockets: 1-Year Results.

A prospective cohort clinical study was performed to evaluate the concept and design of a novel macro hybrid implant placed into maxillary anterior postextraction sockets. Thirty-three patients with an equal number of hybrid implants were used to replace nonrestorable single anterior teeth with immediate tooth replacement therapy (immediate implant placement and immediate provisional restoration). The macro features of this hybrid implant are unique in geometry, as it combines two different shapes-a cylindrical coronal and tapered apical portion-into a singular body design, each comprising roughly half of the implant length. The hybrid design of this platform-switched implant also has a subcrestal angle correction, or Co-Axis feature, that facilitates screw-retained restorations. Mean implant survival at 1 year relative to primary stability, labial bone plate thickness with socket grafting at two reference points (L1 and L2), tooth-to-implant interproximal bone crest thickness, and pink esthetic score (PES) were evaluated. A mean insertion torque value of 65 Ncm (range 45 to 100 Ncm) was reached with the use of the tapered apical half of the implant body. No implants failed during an average healing period of 1 year. A labial plate dimension between 1.8 and 2.1 mm was attained immediately posttreatment and remained stable over time. A tooth-to-implant interdental bone crest distance and dimension of 2.3 to 2.6 mm was reached; it was also sustained at the 1-year follow-up. The average PES was 12.5 (range 9.0 to 14.0), with nearly 90% of treated sites with an "almost perfect" score. This macro hybrid implant in concept and design may be useful in immediate tooth replacement therapy of maxillary anterior postextraction sockets to achieve successful implant survival and esthetic outcomes, specifically labial plate and papilla preservation without midfacial or interdental tissue loss and discoloration.

Immediate loading of screw-retained all-ceramic crowns in immediate versus delayed single implant placement.

PURPOSE: The aim of this study was to evaluate and compare the outcomes of immediately loaded all-ceramic crown restorations supported by implants placed in both mature bone and immediate extraction sockets. MATERIALS AND METHODS: Forty-three tapered, external hex implants were placed immediately after extraction or in healed bone in a convenience sample of 38 patients from two clinics, with 23 implants immediately placed after tooth extraction and 20 placed in mature bone. Thirty implants were located in the maxilla and 13 in the mandible. Each surgical implant placement was followed by the fabrication of a screw-retained all-ceramic crown (zirconia-toughened alumina cylinder and layered with porcelain) that was then put into immediate function. Each patient was recalled annually for clinical and radiographic assessments. RESULTS: All implants were loaded immediately and all functioned successfully following a mean follow-up of 26 months. Significantly more bone loss was recorded around delayed implants compared with immediately placed ones. Smoking, platform switching, and jaw location did not influence peri-implant bone loss. Porcelain chipping was noted in the case of two crowns. CONCLUSION: The short-term outcome of prefabricated ceramic cylinders used to support a single screw-retained crown was regarded as successful. Immediate implant placement did not appear to increase the risk for implant failure and was accompanied by reduced peri-implant bone loss.

Immediate loading of 190 endosseous dental implants: a prospective observational study of 40 patient treatments with up to 2-year data.

PURPOSE: The present study was undertaken to determine the feasibility of using primary stability as a predictor of implant success in patients whose implants were immediately loaded. MATERIALS AND METHODS: The study included 40 patients, in whom a total of 190 implants were placed, 102 in maxillary sites and 88 in mandibular sites. All were loaded within 72 hours of placement. Sixteen patients were completely edentulous in the mandible and/or the maxilla. The remaining 24, who were partially edentulous, received fixed partial dentures or single-implant restorations. All of the definitive implant restorations were screw retained. The criterion for loading was clinical judgment of primary stability, verified by a "screw test." Impressions were made after implant placement to facilitate the fabrication of a laboratory-made heat-processed provisional restoration from acrylic resin. Following a 4-month period for osseointegration and soft tissue healing, definitive fixed prostheses were fabricated. RESULTS: There were no surgical complications. After 1 to 2 years, all 190 implants had survived and were considered 100% successful, as determined by independent testing of mobility and radiographic evidence of osseointegration. In 4 patients, fracture of the provisional restoration occurred during the healing period. DISCUSSION: Clinical research has shown that immediate loading is a viable treatment modality. The favorable success rate reported in this study for rough-surfaced implants suggests that adherence to a protocol, an important parameter of which is primary stability above 32 Ncm, can lead to osseointegration. CONCLUSION: The results of this limited investigation suggest that patients who are partially or completely edentulous may be immediately restored with implants and fixed provisional restorations, provided that the dental implants are adequately stable immediately after their surgical placement. This alternative therapeutic approach did not appear to affect the up-to-2-year survival of the implants in this patient population.