In addition to survival rates, the studies reported moderate complication rates between 0–24 %
The evidence is based on high-quality systematic reviews and a randomized controlled trial (RCT). However, some of the primary studies included in the reviews are retrospective. According to recent systematic reviews implant-supported fixed prostheses (single crowns, bridges and cantilever structures) in the posterior region demonstrate high survival rates. This also applies to narrow-diameter implants (NDI) as well as cantilever structures, although cantilever designs are associated with a slightly elevated risk of technical complications.
| Reference | Study type | Population | Intervention and comparison | Outcomes | Risk of bias |
|---|---|---|---|---|---|
| «Pachiou A, Tsirogiannis P, Ioannidis A, ym. Narrow...»1 | SR / MA | Total 36 studies (2741 implants). Partially edentulous patients requiring fixed prosthesis in the posterior region. | I: Narrow-diameter implants (NDI, <3.75mm) in the posterior region (premolar/molar). C: Implicit comparison to standard implants in literature or between materials/jaws. | Implant survival rate (SR), complications (technical/biological). | Moderate |
| «Vieira FL, Fontenele MNB, de Souza LM, ym. Implant...»2 | SR / MA | 11 studies (360 patients, 482 implants). Partially edentulous patients in the posterior region. | I: Implant-supported bridges with a cantilever extension in the posterior region. C: No cantilever or comparison between cantilever lengths/number of implants. | Implant/prosthesis SR, technical/biological complications, marginal bone loss (MBL). | Moderate |
| «Amato F, Spedicato GA. Immediate Loading of Three-...»3 | RCT | 63 patients (178 implants), partially edentulous in the posterior region. | I: 3-unit bridge supported by two implants (2I). C: 3-unit bridge supported by three implants (3I). |
Implant/prosthesis SRl, MBL, complications. | Low |
| Reference | Comments |
|---|---|
| «Pachiou A, Tsirogiannis P, Ioannidis A, ym. Narrow...»1 | Systematic review and meta-analysis. Included 3 RCTs and 33 observational studies. Risk of bias assessed using MINORS/Cochrane tools. Heterogeneity was low for survival rates but higher for complication reporting. Platform-switching reduced technical problems. |
| «Vieira FL, Fontenele MNB, de Souza LM, ym. Implant...»2 | Systematic review. GRADE assessment yielded "Very low" certainty for most outcomes due to bias and imprecision in primary studies (mostly retrospective), but results were consistent regarding survival. High heterogeneity in bio-complications (I2 > 80%) |
| «Amato F, Spedicato GA. Immediate Loading of Three-...»3 | Well-reported RCT with long follow-up (mean 7 years). Randomization and blinding (during analysis) described. Small sample size may affect power, but results were clear. |
Results
| Reference | Number of studies and number of patients (I/C) | Follow-up time | Absolute number of events (%) I | Absolute number of events (%) C | Relative effect (95% CI) |
|---|---|---|---|---|---|
| «Pachiou A, Tsirogiannis P, Ioannidis A, ym. Narrow...»1 | 29 studies (MA) / 2741 implants | 1–12 years | SR: 92.7–100% | N/A (pooled analysis) | Pooled SR: 97.7% |
| «Vieira FL, Fontenele MNB, de Souza LM, ym. Implant...»2 | 10 studies / 293 implants (cantilever) | 2–19 years | Failure rate: 1% (0–3%) |
N/A | N/A |
| «Amato F, Spedicato GA. Immediate Loading of Three-...»3 | 1 study / 63 patients | Mean 7 years | 1 implant loss (3I group) | 0 implant loss (2I group) | SR: 98.9% (3I) vs 100% (2I) |
| Level of evidence: High Evidence is consistent across multiple SR-level studies and an RCT: implant survival rates in the posterior region are very high. |
|||||
| Reference | Number of studies and number of patients (I/C) | Follow-up time | Absolute number of events (%) I | Absolute number of events (%) C | Relative effect (95% CI) |
|---|---|---|---|---|---|
| «Vieira FL, Fontenele MNB, de Souza LM, ym. Implant...»2 | 5 studies (tech), 6 studies (bio) | 2–19 years | Tech complications: 14% Retention loss: 13% Biological: 20% |
N/A | |
| «Pachiou A, Tsirogiannis P, Ioannidis A, ym. Narrow...»1 | 36 studies | 1–12 years | Tech complications: 0–23.5% |
N/A | |
| Level of evidence: Moderate Technical and biological complications occur moderately (especially with cantilevers and screw loosening), but they are manageable. The level of evidence is downgraded due to heterogeneity. Maximum cantilever extension size was considered to be 7 mm. The article of Vieira does not specify whether the measurement was taken from the posterior edge of the implant or another point. It directly uses the millimeter values reported by the original 11 studies, even though there were likely differences in measurement methods between these studies. Generally, in implant prosthodontics, cantilever length is often measured from the center of the last implant (center of the implant) to the most distal point of the extension, but based on this article, this cannot be confirmed as the standard used in these specific datasets. |
|||||