Fixed full‐arch maxillary prostheses supported by four versus six implants with a titanium CAD/CAM milled framework: 3‐year multicentre RCT

Abstract

ObjectivesThis RCT compares marginal bone level (MBL) change and the clinical parameters after a 3‐year function in maxillary implant‐supported fixed complete dentures (FCDs) treated with four‐implants (4‐I) or six‐implants (6‐I).Material and methodThree centres treated 56 patients with 280 implants allocated to the 4‐I or 6‐I group. Radiographic and clinical examinations were performed. The primary outcome was to investigate MBL change between the groups.ResultsImplant survival rates were 100% and 99% in the 4‐I and 6‐I groups, respectively. Considering the clustering effects, the MBL change was not significantly different between the groups over the 3‐year follow‐up. The MBL in the 4‐I group was 0.30 ± 0.50 mm at baseline, 0.24 ± 0.31 mm at 1 year and 0.24 ± 0.38 mm at 3 years. In the 6‐I group, MBL was 0.14 ± 0.32 mm at baseline, 0.16 ± 0.35 mm at 1 year and 0.12 ± 0.26 mm at 3 years. There was a statistically significant difference between the groups at BL and 3Y. No significant differences between the groups were reported for clinical parameters at each time point as well as in between the visits. The technical and biological complications rates were 1.6% and 6.0%, respectively. Prosthetic complications affected 25 FCDs (47.2%).ConclusionMarginal bone level change revealed a stable condition in the 3‐year period in the two groups. Few technical and biological complications occurred apart from the chipping/fracture of the prosthetic teeth. Four‐implant is a feasible solution if the rehabilitation is oriented towards the most cost‐effective treatment and towards avoiding bone augmentation procedures. Clinicians have to consider the potential required visits for prosthetic maintenance.

Comparison of 4‐ or 6‐implant supported immediate full‐arch fixed prostheses: A retrospective cohort study of 217 patients followed up for 3–13 years

“…These results were in accord with the previous studies by Tallarico and colleagues and Toia and colleagues 1,23 and dental prostheses. Toia and colleagues also proposed that convenience of hygienic maintenance, financial exposure, extra bone regeneration procedure (surgical invasiveness), and cost of repairing should be taken into consideration.…”

“…These results were in accord with the previous studies by Tallarico and colleagues and Toia and colleagues 1,23 Although the studies showed comparable outcomes between All‐on‐4 and All‐on‐6, Tallarico and colleagues stated that patient demand, compliance, dexterity, financial capability, skeletal maxillomandibular relationship, and residual bone anatomy had to be taken into consideration to customize the proper implant number, position, and dental prostheses. Toia and colleagues also proposed that convenience of hygienic maintenance, financial exposure, extra bone regeneration procedure (surgical invasiveness), and cost of repairing should be taken into consideration.…”

“…Toia and colleagues 23 stated that the hygienic maintenance of All‐on‐6 was more complicated than All‐on‐4 owing to the reduced inter‐implant space. The more implant number and the more distal position of the posterior implants in All‐on‐6 also increased the difficulty and time to clean each implant carefully and thoroughly.…”

“…1,[69][70][71] The clinicians chose to place six implants in the maxillae in the fear of the possible implant loss especially for low bone density condition, and in order to reduce the cantilever and undesirable occlusal force conducted to the implants. Toia and colleagues 23 stated that when choosing the protocol of a reduced number of implants, one common concern was that losing an implant may require an extra surgical procedure in order to substitute it, which was often considered unnecessary for All-on-6. As for All-on-4, only 1 implant loss may cause the inability of using the complete fixed prosthesis.…”

“…An RCT study by Tallarico and colleagues 1 in 2016 reported that, there was no significant difference in the clinical outcomes (implant failure rate, complications and marginal bone loss [MBL]) between All‐on‐4 and All‐on‐6 in maxillae. Toia and colleagues 23 also reported that in maxillae, using 4 or 6 implants to support FAFPs showed no significant difference in implant survival rate, MBL and incidence of complications. The results in these studies might challenge the necessity of All‐on‐6.…”