A ruler template with the respective magnifications was used, considering 25 to 0 % for panoramic and periapical radiographs, respectively. Additionally, the radiographic criteria recommended by Buser et al. were included to determine the success of the implants. These criteria consist of the absence of persistent radiolucency around the implant. The zygomatic implants were assessed only to verify their correct position, with acceptable maintenance of the apical third of the implant inside the zygomatic bone or small apical exteriorizations that did not exceed 1 mm, evaluated by a cone-beam CT scan (Figs. 4 and 5). A single and calibrated investigator collected the data in two different occasions.

Clinical evaluation

Group I patients went through full intraoral and health history examination with the purpose of analyzing the periimplant health. The data collected included spontaneous pain or pain on palpation; mucosa color; and presence of purulent secretion, presence of mobility, and presence of oral-antral fistula in the area of the zygomatic implants. The data were also supplemented probing the zygomatic implants using a WHO periodontal probe (Fig. 6). The probing examination took into consideration three parameters:

• Bleeding on probing: the probe was inserted with light pressure, avoiding overextension into the healthy tissues in the mesial, distal, buccal, and palatal implant surfaces. In cases where the probing was negative for bleeding, the periimplant site was considered healthy and stable.

• Probing depth: probing the periimplant sulcus was done with slight pressure. In cases of healthy mucosa or mucositis, the probing depth should not be greater than 5.0 mm.

• Presence of purulent secretion on probing.

Evaluation of the maxillary sinus health

The evaluation of the maxillary sinus health was performed by a single otolaryngologist at the hospital. The clinical exam also included questions on signs and symptoms of sinus disease. Cone-beam computed tomography was performed on all patients.