Interventions for replacing missing teeth: zygomatic implants for the rehabilitation of the severely atrophic edentulous maxilla.

rationaleDental implants are widely used to replace missing teeth but require sufficient bone for support. In people with severe maxillary (i.e. upper jaw) bone loss, zygomatic implants provide an alternative to bone augmentation by anchoring in the cheekbone instead of the upper jaw. Potential advantages include avoiding bone grafting and enabling immediate or early placement of a fixed prosthesis. However, the procedure is technically demanding and may be associated with serious complications.

objectivesTo assess the effects of zygomatic implants for the rehabilitation of people with severely atrophic maxillae requiring implant-supported prostheses by comparing: (1) zygomatic implants with or without bone augmentation procedures versus conventional dental implants in augmented bone; (2) zygomatic implants with or without conventional implants versus subperiosteal implants; (3) one type of zygomatic implant or technique versus another type or technique. SEARCH

methodsWe used CENTRAL, MEDLINE, Embase, and two trial registers, together with reference checking and contact with study authors to identify the studies included in the review. We conducted searches in November 2025. ELIGIBILITY CRITERIA: We included randomised controlled trials (RCTs), with either a parallel-group or split-mouth design, involving at least 10 participants per arm, with at least one year of follow-up. Participants had severely resorbed maxillae and could not receive conventional dental implants. OUTCOMES: Our outcomes were prosthesis and implant failures, complications, patient satisfaction or preference, and cost-effectiveness, assessed as time required to rehabilitate the patient. RISK OF BIAS: We used Cochrane's RoB 2 tool to assess bias in the RCTs. SYNTHESIS

methodsWe did not synthesise data because we included only one study each for two comparisons. We used GRADE to assess the certainty of the evidence. INCLUDED STUDIES: We included two RCTs, each with a three-year follow-up. One parallel-group RCT included 71 participants and compared zygomatic implants-used either alone or in combination with conventional implants and immediately loaded-with delayed placement of conventional implants in bone augmented with bone substitutes (comparison 1). The other split-mouth RCT included 20 participants and compared the placement of zygomatic implants using conventional rotary drills with piezoelectric preparation on the contralateral side (comparison 3). SYNTHESIS OF

resultsComparison 1: zygomatic implants with and without bone augmenting procedures versus conventional dental implants in augmented bone After three years, zygomatic implants may reduce prosthetic failures compared with conventional dental implants placed in grafted bone (odds ratio (OR) 0.29, 95% confidence interval (CI) 0.05 to 1.56; 66 participants; low-certainty evidence). Zygomatic implants probably reduce implant failures compared with conventional implants (OR 0.23, 95% CI 0.06 to 0.96; 61 participants; moderate-certainty evidence). Zygomatic implants probably increase complications (OR 4.53, 95% CI 1.47 to 13.98; 66 participants; moderate-certainty evidence). Zygomatic implants may have little to no effect on patient satisfaction compared with conventional implants in grafted bone (MD 0.40, 95% CI -3.05 to 3.85; 60 participants; low-certainty evidence). As a measure of cost-effectiveness, time to rehabilitation is probably shorter with zygomatic implants compared with conventional implants in grafted bone (MD -442.98 days, 95% CI -518.64 to -367.32; 64 participants; moderate-certainty evidence), corresponding to approximately one day (1.3 days) with zygomatic implants versus more than one year (444 days) with bone grafting. Comparison 3: different zygomatic implants and techniques: piezoelectric surgery compared with rotary drills After three years, preparation with piezoelectric surgery may have little to no effect on prosthetic failures compared with rotary drills, and the evidence is compatible with benefit, no effect, and harm (OR 1.00, 95% CI 0.02 to 50.40; 17 participants; low-certainty evidence). Piezoelectric surgery may have little to no effect on implant failures compared with rotary drills, with very wide confidence intervals compatible with benefit, no effect, and harm (OR 1.00, 95% CI 0.02 to 50.40; 17 participants; low-certainty evidence). Complications may be similar between rotary drills and piezoelectric surgery (OR 1.50, 95% CI 0.25 to 8.99; 20 participants; low-certainty evidence). Patient preference may favour piezoelectric surgery, but the estimate is very imprecise and compatible with both a strong preference for piezoelectric surgery and equal preference for the two approaches (OR 9.00, 95% CI 0.48 to 167.26; 20 participants; low-certainty evidence). As a measure of cost-effectiveness, implant placement is probably faster with rotary drills than with piezoelectric surgery (MD -9.15 minutes, 95% CI -10.41 to -7.89; 20 participants; moderate-certainty evidence), corresponding to approximately 14 minutes with rotary drills versus 24 minutes with piezoelectric surgery. The certainty of the evidence for both comparisons ranged from moderate to low. We downgraded mainly for serious imprecision resulting from small sample sizes and wide confidence intervals. The risk of bias was generally low, although we judged one outcome (patient satisfaction) in one study to be at high risk of bias due to missing outcome data. AUTHORS'

conclusionsAt three years, zygomatic implants probably reduce time to rehabilitation compared with bone grafting (1.34 versus 444.32 days). They probably reduce implant failures and probably increase the risk of complications. Zygomatic implants may reduce prosthetic failures, but the estimates are imprecise. The effect on patient satisfaction remains uncertain. Compared with piezoelectric surgery, rotary drills probably reduce implant placement time. For prosthetic failures, implant failures, complications, and patient preference, piezoelectric surgery may have little to no effect, and important benefit or harm cannot be ruled out because of very wide confidence intervals. Implant site preparation with piezoelectric surgery is probably slower and may not always be feasible in the presence of very dense bone. Overall, the evidence base for both comparisons is limited and is affected by imprecision, which restricts the confidence with which these findings can be applied in clinical settings. More well-designed RCTs are needed to reduce the current uncertainty.

fundingThis Cochrane review was funded (in part) by Vita-Salute San Raffaele University, Milan. REGISTRATION: Protocol: (2003): 10.1002/14651858.CD00415 Original review (2003): DOI: 10.1002/14651858.CD004151 Review update (2005): DOI: 10.1002/14651858.CD004151.pub2 Review update (2013): DOI: 10.1002/14651858.CD004151.pub3.