Short implants (<8mm) versus longer implants (≥8mm) with lateral sinus floor augmentation in posterior atrophic maxilla: A meta-analysis of RCT`s in humans

Does sinus membrane thickness influence the risk of perforation during lateral sinus lift surgery for dental implants? a systematic review and meta-analysis

BACKGROUND

We reviewed the literature to examine if the thickness of the sinus membrane is a risk factor for perforation during lateral sinus lift surgery.

MATERIAL AND METHODS

We searched Embase, PubMed, and Web of Science databases till 4th December 2023 for studies examining the risk of perforation with different sinus membrane thicknesses. Studies reporting sinus membrane thickness in perforation and non-perforation cases were also included.

RESULTS

Eleven studies were eligible. All studies used cone beam computed tomography for measuring sinus membrane thickness. Meta-analysis showed that sinus membrane thickness was significantly lower in perforation cases as compared to non-perforation cases (MD: -0.91 95% CI: -1.48, -0.33 I2=94%). Four studies used 2mm as the cut-off to define thick and thin sinus membranes. Pooled analysis failed to demonstrate any significant difference in perforation rates (OR: 0.97 95% CI: 0.44, 2.17 I2=56%). Meta-analysis of studies using 1.5mm (OR: 0.66 95% CI: 0.29, 1.48 I2=72%) and 1mm cut-off (OR: 0.93 95% CI: 0.34, 2.56) also demonstrated similar non-significant results.

CONCLUSIONS

Our study shows that the sinus membrane is significantly thinner in cases with perforations as compared to those with no perforations. However, a meta-analysis based on different membrane thickness cut-offs failed to demonstrate a relationship between thinner sinus membranes and a higher risk of perforation. There is a need for further studies examining the role of sinus membrane thickness on perforation rates.

Implant rehabilitation of a posterior maxilla with 4-mm long implants splinted to a 10-mm long implant in a patient with osteopenia taking antiresorptive drugs: A 5-year follow-up case report

The report describes the rehabilitation of a maxillary arch with limited bone volume in a 67-year-old female taking antiresorptives due to osteopenia. One 10-mm and two extra-short 4-mm implants were inserted, and implant-supported splinted crowns were fabricated. The 5-year follow-up showed stable bone levels, despite poor initial stability (ISQ: 14-51).

Clinical efficacy of extra-short implant (4 mm) placed in posterior areas: a Meta-analysis

OBJECTIVES

This study aimed to systematically evaluate the safety and clinical efficacy of 4 mm-extra-short implant (ESI) placement in severely atrophic posterior areas.

METHODS

Databases of PubMed, Embase, Cochrane Library, Web of Science, CNKI, and Wanfang from January 1, 2010, until August 31, 2022, were searched to identify randomized controlled trials or controlled clinical trials related to ESI and standard implants (SI). An additional hand search of the references of included articles was also conducted. Meta-analyses were carried out with RevMan 5.4 software.

RESULTS

A total of 11 studies were included, involving six randomized controlled trials and five controlled clinical trials. The meta-analyses indicated that when implants were placed in the posterior area, the implant survival rate between ESI and SI did not significantly differ [RR=1.23, 95%CI (0.66, 2.27), P=0.52]. ESI resulted in significantly stable marginal bone level [MD=-0.16, 95%CI (-0.25,-0.07), P=0.000 7] and less biological complications [RR=0.34, 95%CI (0.19, 0.62), P=0.000 4] but more mechanical complications [RR=2.89, 95%CI (1.05, 7.92), P=0.04].

CONCLUSIONS

Based on the limited evidence, ESI could achieve clinical outcomes similar to those of SI when the height of the posterior alveolar bone is less than 5 mm, with lower technical sensitivity and fewer postoperative clinical complications than SI. Due to insufficient evidence and limited sample size, further clinical trials are needed to verify the long-term efficacy of ESI.

Short Implants versus Longer Implants with Sinus Floor Elevation: A Systemic Review and Meta-Analysis of Randomized Controlled Trials with a Post-Loading Follow-Up Duration of 5 Years

This study compared the outcome of fixed prostheses supported by short implants (<8 mm) and longer implants (≥8 mm) with an elevated sinus floor after 5 years of follow-up. The literature searches were performed electronically and manually in PubMed, EMBASE, and Web of Science databases to identify relevant articles published from 1 January 2013 to 31 January 2020. We selected eligible studies using inclusion criteria and assessed their quality. From 1688 identified studies, five randomized controlled trials were included. Between the short implant group and the control group, the implant failure-related pooled risk ratio (RR) was 3.64 (p = 0.07). The RR for technical complications was 2.61 (p = 0.0002), favoring longer implants. Marginal peri-implant bone loss after 1 and 5 years of function showed statistically significant less bone loss at short implants (1 year: mean difference = 0.21 mm; p < 0.00001; 5 years: mean difference = 0.26 mm; p = 0.02). The implant failure and the biological failure of both groups were similar after 5 years of follow-up. Short implants could be an alternative to long implants with an elevated sinus floor for atrophic maxillae in aging populations. Studies with larger trials and longer periods of follow-up (10 years) remain essential.

Short Narrow Dental Implants versus Long Narrow Dental Implants in Fixed Prostheses: A Prospective Clinical Study

There is a paucity of studies that assess short and narrow dental implants. This prospective study aimed to evaluate the performance of both short (≤8 mm) and narrow (≤3.5 mm width) dental implants supporting fixed prostheses in the atrophic maxilla or mandible. Towards that aim, patients with short implants were included in the study. The control group was those with long and narrow dental implants (length > 8 mm and diameter ≤ 3.5 mm). Clinical and demographic variables were extracted from clinical records. During the follow-up, implant survival and marginal bone loss were evaluated and statistically analysed. Forty-one implants were included (18 and 23 implants in the test and control groups, respectively). The median follow-up time was 26 months since insertion in both groups. The results revealed that there was no implant failure and no statistically significant differences in terms of marginal bone loss. Only one screw-loosening effect occurred in the short implants group. Short, narrow dental implants could be an alternative for the restoration of severely resorbed jaws.

A meta-analysis indicating extra-short implants (≤ 6 mm) as an alternative to longer implants (≥ 8 mm) with bone augmentation

Extra-short implants, of which clinical outcomes remain controversial, are becoming a potential option rather than long implants with bone augmentation in atrophic partially or totally edentulous jaws. The aim of this study was to compare the clinical outcomes and complications between extra-short implants (≤ 6 mm) and longer implants (≥ 8 mm), with and without bone augmentation procedures. Electronic (via PubMed, Web of Science, EMBASE, Cochrane Library) and manual searches were performed for articles published prior to November 2020. Only randomized controlled trials (RCTs) comparing extra-short implants and longer implants in the same study reporting survival rate with an observation period at least 1 year were selected. Data extraction and methodological quality (AMSTAR-2) was assessed by 2 authors independently. A quantitative meta-analysis was performed to compare the survival rate, marginal bone loss (MBL), biological and prosthesis complication rate. Risk of bias was assessed with the Cochrane risk of bias tool 2 and the quality of evidence was determined with the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. 21 RCTs were included, among which two were prior registered and 14 adhered to the CONSORT statement. No significant difference was found in the survival rate between extra-short and longer implant at 1- and 3-years follow-up (RR: 1.002, CI 0.981 to 1.024, P = 0.856 at 1 year; RR: 0.996, CI 0.968 to 1.025, P  = 0.772 at 3 years, moderate quality), while longer implants had significantly higher survival rate than extra-short implants (RR: 0.970, CI 0.944 to 0.997, P < 0.05) at 5 years. Interestingly, no significant difference was observed when bone augmentations were performed at 5 years (RR: 0.977, CI 0.945 to 1.010, P = 0.171 for reconstructed bone; RR: 0.955, CI 0.912 to 0.999, P < 0.05 for native bone). Both the MBL (from implant placement) (WMD: - 0.22, CI - 0.277 to - 0.164, P < 0.01, low quality) and biological complications rate (RR: 0.321, CI 0.243 to 0.422, P < 0.01, moderate quality) preferred extra-short implants. However, there was no significant difference in terms of MBL (from prosthesis restoration) (WMD: 0.016, CI - 0.036 to 0.068, P = 0.555, moderate quality) or prosthesis complications rate (RR: 1.308, CI 0.893 to 1.915, P = 0.168, moderate quality). The placement of extra-short implants could be an acceptable alternative to longer implants in atrophic posterior arch. Further high-quality RCTs with a long follow-up period are required to corroborate the present outcomes.Registration number The review protocol was registered with PROSPERO (CRD42020155342).

Survival Rate of 1008 Short Dental Implants with 21 Months of Average Follow-Up: A Retrospective Study

This retrospective study evaluated the survival rate of short, sandblasted acid-etched surfaced implants with 6 and 8 mm lengths with at least 120 days of follow-up. Data concerning patient, implant and surgery characteristics were retrieved from clinical records. Sandblasted and acid-etched (SLA)-surfaced tissue-level 6 mm (TL6) or 8 mm (TL8) implants or bone-level tapered 8 mm (BLT8) implants were used. Absolute and relative frequency distributions were calculated for qualitative variables and mean values and standard deviations for quantitative variables. A Cox regression model was performed to verify whether type, length and/or width influence the implant survival. The cumulative implant survival rate was assessed by time-to-event analyses (Kaplan–Meier estimator). In all, 513 patients with a mean age of 58.00 ± 12.44 years received 1008 dental implants with a mean follow-up of 21.57 ± 10.77 months. Most implants (78.17%) presented a 4.1 mm diameter, and the most frequent indication was a partially edentulous arch (44.15%). The most frequent locations were the posterior mandible (53.97%) and the posterior maxilla (31.55%). No significant differences were found in survival rates between groups of type, length and width of implant with the cumulative rate being 97.7% ± 0.5%. Within the limitations of this study, the evaluated short implants are a predictable option with high survival rates during the follow-up without statistical differences between the appraised types, lengths and widths.