Immediate Full-Arch Restorations Supported by Conventional Implants Plus Unilateral or Bilateral Zygomatic Implants:...

This study aimed to compare the short-term (3.7 ± 0.4 years) outcomes of full-arch immediately loaded fixed maxillary prostheses supported by conventional and unilateral single zygomatic implants vs those supported by two conventional and bilateral zygomatic implants. A retrospective analysis was conducted on patients suffering severe bone loss in the posterior maxilla. The success of zygomatic implants was defined following Offset-Rhinosinusitis-Infection-Stability (ORIS) criteria. The criteria used to define the success of standard dental implants were the absence of mobility, pain, discomfort, neurologic disorder, and persistent or chronic infection. The level of significance was .01. A total of 38 patients received 2 to 5 standard implants plus 2 zygomatic implants (bilateral), whereas 10 patients received 3 to 5 standard implants plus a single zygomatic implant (unilateral). In total, 108 standard and 76 zygomatic implants were placed in bilateral group patients, whereas 38 standard and 10 zygomatic implants were placed in unilateral group patients. The cumulative success rate for standard implants was 99% and 97.3% in the bilateral and unilateral groups, respectively. Four patients showed symptoms of acute rhinosinusitis (R-criterion): 1 in the unilateral group and 3 in the bilateral group. Following the O-criterion, just 2 implants in the bilateral group showed a success grade 1. One zygomatic implant in the bilateral group developed peri-implant mucositis with a success grade 3 (I-criterion). All zygomatic implants were checked individually and did not show any signs of mobility or rotation after applying forces to the implant (S-criterion). The ORIS criteria divided the implants into three groups according to the success grades I, II, and III: 32, 36, and 8 implants, respectively, for the bilateral group, and 6, 1, and 3 implants, respectively, for the unilateral group, with no significant difference between the two groups. No zygomatic implant failure occurred, and thus the same zygomatic implant success rate (100%) was recorded for both groups. A prosthetic failure was registered in the unilateral group. The overall prosthesis success rates were 89.5% and 70% in the bilateral and unilateral groups, respectively. A high degree of success was achieved for both groups treated with zygomatic implants, although in the unilateral group there was one failure of a standard implant placed in the posterior area. This suggests that the use of zygomatic implants could provide adequate support to fixed full-arch prostheses, even in the configuration with a single unilateral zygomatic implant.