Maxillary All-on-6 Treatment Using Zygomatic Implants. Bone Loss Evaluation by CBCT: 3-Year Follow-up

To evaluate radiographic changes around six implants (two posterior zygomatic implants and four conventional implants) used with fixed detachable restorations in patients with severe maxillary posterior resorption with either polyether ether ketone (PEEK) or titanium frameworks.

In total, 12 maxillary edentulous patients were rehabilitated with six implants, including two posterior zygomatic and four conventionally placed implants for each patient following All-on-6 distribution and opposing a mandibular All-on-4 implant-retained fixed detachable prosthesis. A two-stage surgical unloaded healing protocol was performed. According to framework and teeth materials, there were two groups: group 1- CAD/CAM-milled framework from modified BioHPP PEEK bonded to PMMA crowns; and group 2-screwretained CAD/CAM-milled framework from titanium bonded to zirconia crowns. Bone loss evaluation for six implants was performed using CBCT at the time of delivery (T0), after 1 year (T1), and after 3 years (T2).

There was a statistically significant difference in bone loss between the PEEK and titanium groups. There was less bone loss in the PEEK group around anterior conventional implants at buccal (P = .01), mesial (P < .001), and distal surfaces (P < .001) and for zygomatic implants at buccal (P = .004) and palatal surfaces (P = .003).

Within the limitations of the study, the full-arch PEEK and titanium frameworks of fixed-detachable prostheses used with an All-on-6 distribution using zygomatic implants for rehabilitation of maxillary edentulous atrophied posterior arches was a promising treatment approach. Less bone loss was observed with the PEEK framework restorations combined with the PMMA crowns group.