Comparing 4-mm dental implants to longer implants placed in augmented bones in the atrophic posterior mandibles: One-year results of a randomized controlled trial

Survival Rates of Short Dental Implants (≤6 mm) Used as an Alternative to Longer (>6 mm) Implants for the Rehabilitation of Posterior Partial Edentulism: A Systematic Review of RCTs

Short dental implants have been proposed as an alternative treatment option to bone regeneration procedures for the rehabilitation of resorbed alveolar ridges. The aim of this paper was to systematically review randomized controlled trials (RCTs) comparing short implants (≤6 mm) and longer implants (>6 mm) in atrophic alveolar ridges in terms of implant survival rates, peri-implant marginal bone loss (MBL), prevalence of peri-implantitis and technical complications. A thorough electronic search was performed until September 2023. RCTs with follow-up of at least 1-year post-loading comparing short implants with rough surfaces to longer implants in the posterior jaws of systemically and periodontally healthy, partially edentulous adults were considered. Studies with incomplete information on the number of patients, follow-up or definition of "short implants" were excluded. The revised Cochrane risk-of-bias tool for randomized trials was used for Risk of bias assessment. Fixed-effects meta-analysis of the selected studies was applied to compare the outcome variables. Random-effect meta-analysis was performed, on the basis of within-study comparisons. In total, 16 articles were selected for meta-analysis and incorporated 408 short implants and 475 longer implants inserted in 317 and 388 patients, respectively. The survival rates of longer implants in pristine or augmented bone were significantly increased compared to short implants (95%CI: 2-5%, p < 0.001). Standard-length implants displayed increased, although non-statistically significant MBL (95%CI: -0.17-0.04, p > 0.05), and prevalence of peri-implantitis (95%CI: 0-5%, p > 0.05). No statistically significant differences were observed between short and long implants in terms of technical complications (implant-level 95%CI: -4-6%, p > 0.05). Short implants represent a promising alternative treatment option for the rehabilitation of posterior jaws to avoid additional bone augmentation procedures. Nonetheless, they should be selected cautiously due to a potentially limited survival rate compared to longer implants. A major limitation of this study is the variability in the included studies regarding sample size, patient profile, type of bone, loading protocol, definition of peri-implantitis, among others. This study received no external funding. The study protocol was registered in PROSPERO (CRD42023485514).

Outcome Difference between Short and Longer Dental Implants Placed Simultaneously with Alveolar Bone Augmentation: a Systematic Review and Meta-Analysis

Objectives

This systematic review and meta-analysis aim to provide detailed insights into the clinical performance of short and longer dental implants placed simultaneously with bone augmentation.

Material and Methods

The search for literature was performed across MEDLINE (PubMed), ScienceDirect and the Cochrane Library databases, adhering to specific selection criteria and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Only articles published in English between 2014 and 2024 were considered for data collection. Primary outcomes were survival rate (SR), marginal bone loss (MBL) and complications. Clinical outcomes were as follows: bleeding on probing (BOP), periodontal pocket depth (PPD), and implant stability quotient (ISQ). Quality and risk of bias assessment were evaluated by the Critical Appraisal Checklist tool for randomized controlled trials developed by the Joanna Briggs Institute.

Results

A total of 14678 articles were screened, with 9 meeting the inclusion criteria and being utilized for this systematic review and meta-analysis. A total of 495 patients with 984 implants (491 short and 493 longer implants) showing a SR of 93.91% for the short implants and 91.83% for the longer implants. Meta-analysis revealed statistically significant difference between short implants and longer implants simultaneously placed with alveolar bone augmentation in relation to MBL (-0.513 mm, 95% CI = -0.93 to -0.096; P = 0.02), and in PPD (-0.247, 95% CI = -0.515 to 0.022; P = 0.07).

Conclusions

When comparing the results of treatment with short and longer dental implants combined with alveolar bone augmentation, short implants showed better clinical results regarding the parameters of survival rate, marginal bone loss and complications.

The influence of vertical ridge augmentation techniques on peri-implant bone loss: A systematic review and meta-analysis

INTRODUCTION

The primary aim of this systematic review was to investigate and compare the outcomes of different vertical ridge augmentation (VRA) techniques in relation to peri-implant bone loss (PBL), after at least 12 months of functional loading.

MATERIAL AND METHODS

The search was conducted to find all the studies about VRA and measurements of PBL with at least 12 months follow-up. Three pairwise meta-analysis (MA) was performed to completely evaluate the outcomes.

RESULTS

A total of 42 studies were included, of which 11 were randomized clinical trials (RCTs). RCTs were available only for guided bone regeneration (GBR), onlay, and inlay techniques. The weighted mean estimate (WME) of PBL value was found to be 1.38 mm (95% confidence interval [95% CI]: 1.10-1.66) after a mean follow-up of 41.0 ± 27.8 months. GBR, Inlay, Onlay, osteodistraction, and SBB represented in weight 32.9%, 30.6%, 25.0%, 7.6%, and 3.9%, respectively; and their WME (95% CI) were 1.06 (0.87-1.26) mm, 1.72 (1.00-2.43) mm, 1.31 (0.87-1.75) mm, 1.81 (0.87-1.75) mm, and 0.66 (0.55-0.77) mm, respectively. Among the secondary outcomes, the analysis was conducted for vertical bone gain, healing complication rate, surgical complication rate, implant survival, and success rate.

CONCLUSIONS

The primary findings of the meta-analysis, based on the changes between final and baseline values, showed that the peri-implant bone loss could be influenced by the type of intervention but there is a need to evaluate in RCTs the behavior of the peri-implant bone levels after long-term follow-up for all techniques.

Comparing short implants to standard dental implants: a systematic review and meta-analysis of randomized controlled trials with extended follow-up

PURPOSE

To compare the difference of marginal level changes (MBL), implant failure (IF), biological and prosthetic complications (BC and PC), and prosthetic failure (PF) of short implants (SH) and standard implants (ST).

MATERIALS AND METHODS

Electronic searches (PubMed, Web of Science, EMBASE, Scopus, Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov) and manual searches were performed to identify all randomized controlled trials (RCTs) evaluating SH to ST. Applying Stata, a meta-analysis was conducted on the weighted mean difference (WMD) and standardized mean difference (SMD) of MBL and the risk difference (RD) of the secondary outcome.

RESULTS

Twenty-four articles were involved in the present study. There were statistically significant differences in MBLs, preferring short implants in the maxilla (WMD: -0.147 (CI: -0.224, -0.070), I2: 76.6%; SMD: -0.757 (CI: -1.226, -0.289), I2: 89.2%) and in the mandible (WMD: -0.377 (CI: -0.656, -0.098), I2: 85.8%; SMD: -0.811 (CI: -1.418, -0.204), I2: 78.8%). There were no significant differences in IF (RD: 0.011 (-0.002, 0.023), I2: 0.0%), PF (RD:0.003 (-0.007, 0.014), I2: 0.0%), and PC (RD:0.001 (-0.008, 0.010), I2: 0.0%). There were significantly higher biological complications (RD: -0.071 (-0.106, -0.036), I2: 0.82.9%) for ST compared to SH in both jaws up to a 10-year follow-up.

CONCLUSION

SH and ST had comparable overall outcomes, but short implants had less marginal bone loss and lower biological complications. However, more research is needed to confirm these findings.

Comparative evidence of different surgical techniques for the management of vertical alveolar ridge defects in terms of complications and efficacy: A systematic review and network meta-analysis

AIM

To systematically appraise the available evidence on vertical ridge augmentation (VRA) techniques and estimate a treatment-based ranking on the incidence of complications as well as their clinical effectiveness.

MATERIALS AND METHODS

Searches were conducted in six databases to identify randomized clinical trials comparing VRA techniques up to November 2022. The incidence of complications (primary) and of early, major, surgical and intra-operative complications, vertical bone gain (VBG), marginal bone loss, need for additional grafting, implant success/survival, and patient-reported outcome measures (secondary) were chosen as outcomes. Direct and indirect effects and treatment ranking were estimated using Bayesian pair-wise and network meta-analysis (NMA) models.

RESULTS

Thirty-two trials (761 participants and 943 defects) were included. Five NMA models involving nine treatment groups were created: onlay, inlay, dense-polytetrafluoroethylene, expanded-polytetrafluoroethylene, titanium, resorbable membranes, distraction osteogenesis, tissue expansion and short implants. Compared with short implants, statistically significant higher odds ratios of healing complications were confirmed for all groups except those with resorbable membranes (odds ratio 5.4, 95% credible interval 0.92-29.14). The latter group, however, ranked last in clinical VBG.

CONCLUSIONS

VRA techniques achieving greater VBG are also associated with higher incidence of healing complications. Guided bone regeneration techniques using non-resorbable membranes yield the most favourable results in relation to VBG and complications.

Fiber-reinforced composite full-arch prosthetic reconstructions supported by three standard, short or extra-short implants: a two-center retrospective study

OBJECTIVES

To evaluate the survival of implants and prostheses, and marginal bone level of fiber-reinforced composite implant supported fixed complete prostheses supported by 3 implants.

MATERIALS AND METHODS

Patients with fiber-reinforced composite fixed prostheses supported by 3 standard-length, short or extra-short implants were included in this retrospective cohort study. Kaplan-Meier survival was computed for implants and prostheses. Univariate and multivariate Cox proportional hazard regressions, clustered by patient, were used to analyze bone level differences as a function of different study covariates. Linear regressions were used to investigate the relationship between distal extension lengths and bone levels.

RESULTS

Forty-five patients with 138 implants were followed for up to 10 years after prosthesis insertion (mean 52.8; SD 20.5 months). Kaplan-Meier survival analysis showed overall survival rates of 96.5% for implants and of 97.8% for prostheses. The 10-year success rate for prostheses was 90.8%. Extra-short implants survived at similar rates to short and standard implants. Marginal bone levels surrounding implants remained stable over time, even showing slight bone gain on average (mean + 0.1 mm/year; SD ± 0.5 mm/year) Acrylic denture teeth, overdentures on the opposing arch, and implant placement in the posterior maxilla were correlated with bone gain. Screw retention, opposed to telescopic retention, was correlated with bone loss. Longer distal extensions were correlated with bone gain on the implants closest to the distal extensions.

CONCLUSIONS

Fiber-reinforced composite fixed prostheses supported by only 3 implants, most of which were extra-short, presented high survival rates with stable bone levels.

CLINICAL RELEVANCE

An encouraging prognosis can be expected for restoration of atrophic maxillary and mandibular arches, when restored with fixed fiber-reinforced composite frameworks with long distal extensions and supported on only 3 short implants.

Clinical Evaluation of Short (6 mm) and Longer Implants Placed Side by Side in Posterior Partially Edentulous Area: A 3-Year Observational Study

Background

Short implants have been proposed as an alternative solution for the rehabilitation of atrophic posterior region.

Purpose

To compare the clinical outcomes between 6 mm short implants and conventional implants placed under similar conditions of bone quality and occlusal loading.

Materials and Methods

Nine patients received atone 6 mm implant and one standard-length (8 mm length or longer) implants in a total of 10 partially edentulous areas. Implants were left submerged for 3-6 months healing period and the screw-retained splinted prostheses were delivered. When the provisional or final restoration was placed, and at each year after loading, standardized intraoral radiograph was taken for themarginal bone level (MBL) changes around the implants. Subsequently, the patients were recalled for the clinical examination evaluating the implant survival, sulcus bleeding index, suppuration, and the incidence of prosthetic complications at every 6 months after the definitive crown delivery. The observation period was continued to 3 years (mean follow-up was 3.4 ± 0.3 years) after functional loading.

Results

Nine patients (10 short implants and 10 standard length implants) were selected in this study. Cumulative survival rates of the short implants and standard-length implants were 100% in both groups, and no biological and prosthetic complication were found in 3 years observation period. Cortical bone thickness of implant insertion sites was 1.39 ± 0.45 mm at short implants and 1.38 ± 0.69 mm at standard-length implants, and trabecular bone computed tomography values of implant insertion sites was 424.1 ± 290.1 at short implants and 410.9 ± 267.9 at standard-length implants. The MBL changes were -0.30 ± 0.71 mm at short implants and -0.19 ± 0.78 mm at standard-length implants at 3 years follow-up visit. No significant difference was found in the average of MBL changes between implant length.

Conclusions

Within the limits of this study, it can be concluded that 6 mm short implants in a posterior edentulous region showed excellent results compared with conventional implants.

Vertical ridge augmentation with Ti-reinforced dense polytetrafluoroethylene (d-PTFE) membranes or Ti-meshes and collagen membranes: 3-year results of a randomized clinical trial

BACKGROUND

The present study aimed to evaluate hard and soft tissue parameters around implants placed in augmented posterior mandible, comparing Ti-reinforced d-PTFE membranes with Ti-meshes covered with collagen membranes, after 3 years of follow-up.

MATERIALS AND METHODS

Forty eligible patients were randomly assigned to group A (Ti-reinforced d-PTFE membrane) or group B (mesh covered with collagen membrane) for vertical ridge augmentation (VRA) and simultaneous implants. Implants were evaluated using specific peri-implant parameters for bone and soft tissues: probing pocket depth (PPD), modified plaque index (mPI), bleeding on probing (BoP), modified gingival index (mGI), thickness of keratinized tissue (tKT), width of keratinized tissue (wKT), fornix depth (FD), peri-implant bone level (PBL), interproximal bone peaks (IBP), marginal bone loss (MBL), interproximal bone loss (IBL).

RESULTS

A total of 28 patients with 79 implants were evaluated after 3 years of follow-up. The mean value of MBL was 0.70 mm (group A = 0.73 mm; group B = 0.71 mm), while mean IBL was 0.54 mm (group A = 0.64 mm; group B = 0.40 mm). The treatment with meshes resulted not inferior to PTFE and their clinical results appeared similar. A strong correlation between PBL and IBP was confirmed. Both study groups showed an increase of tKT and wKT values.

CONCLUSION

In the posterior mandible, VRA using both techniques provides stable PBLs up to 3 years. A correct soft tissue management and a strict professional oral hygiene protocol play a crucial role on peri-implant health over time.

Dimensional changes of peri-implant tissue following immediate flapless implant placement and provisionalization with or without xenograft in the anterior maxilla: a study protocol for a randomized controlled trial

Background

Dental implant therapy requires the preservation of peri-implant tissue in the cosmetic zone. Various surgical procedures have been presented, including ridge preservation, flapless method, and quick provisionalization. The goal of this research was to assess the buccal bone dimensional changes following immediate flapless implant implantation in the front maxilla, with or without xenografting.

Method and design

Thirty patients who meet the inclusion criteria and have maxillary teeth (numbers 14 to 24) are candidates for the immediate implant with immediate provisionalization. Participants will be assigned randomly to one of two groups: (1) an immediate implant with xenograft and (2) an immediate implant without bone grafting. For 3 months, the temporary prosthesis will be installed shortly before the final restoration. Following temporary prosthesis insertion and 6 months after surgery, a CBCT radiograph will be used to examine bone tissue. Soft tissue will be assessed at three points: baseline, 3 months, and 6 months following implant therapy. Patients’ satisfaction, implant failure, prosthesis failure, and complications will be assessed as secondary outcomes after 6 months.

Discussion

The outcomes of this randomized clinical research will show if buccal bone augmentation with xenograft reduces vertical bone and gingiva recession. The findings and patient-reported outcomes will aid in the selection of therapy alternatives for implant treatment patients.

Trial registration

Iranian Registry of Clinical Trials IRCT20211119053106N1. Registered on 6 December 2021 and Open Science Framework (OSF) on May 20, 2022. Registration DOI https://doi.org/10.17605/OSF.IO/VUGFQ.

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.

Healing complications and their detrimental effects on bone gain in vertical-guided bone regeneration: A systematic review and meta-analysis

PURPOSE

Guided bone regeneration (GBR) utilizes a barrier membrane to allow osteogenic cells to populate a space by excluding epithelial and connective tissue cells. The purpose of this systematic review was to investigate the ratio of means (RoM) of vertical bone gained (Outcome) in vertical GBR procedures with healing complications (Intervention) and in vertical GBR procedures without healing complications (Comparison) in patients with vertically resorbed edentulous ridges that require dental implant placement (Population). A further aim was to investigate the incidence of complications after vertical GBR, and the influence of the timing of implant placement and regenerative devices on complications.

MATERIALS AND METHODS

MEDLINE (through PubMed), EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) were searched in duplicate up to, and including, November 2020 for randomized and controlled clinical trials and prospective and retrospective case series. Outcomes included patient-level and site-level RoM of vertical bone gain between healing complications and uneventful healing, and incidences of complications that occurred after vertical GBR. Random-effects and fixed-effects meta-analyses were performed where appropriate. This study was registered on PROSPERO (CRD42021226432).

RESULTS

A total of 31 publications were selected for the qualitative and quantitative analyses. The RoM of vertical bone gained was 0.65 [95% CI = 0.47, 0.91] and 0.62 [95% CI = 0.45, 0.85] when membrane exposure without suppuration and abscess formation without membrane exposure occurred respectively, in comparison to uneventful healing. The overall incidence proportion of healing complications occurring at the augmented site at a site- and patient-level was 11.0% [95% CI = 7.0, 15.6] and 10.8% [95% CI = 6.6, 15.7]. At a patient-level, there were no significant differences between a simultaneous or staged approach, or with the regenerative device used. The site-level incidence proportion of membrane exposure without suppuration, membrane exposure with suppuration, and with abscess formation without membrane exposure was 8.7% [95% CI = 4.2, 14.2], 0.7% [95% CI = 0.0, 2.9], and 0.5% [95% CI = 0.0, 1.7], respectively. The site-level weighted mean incidence proportion of neurologic complications occurring at the donor site was 0.8% [95% CI = 0.0, 5.3].

CONCLUSIONS

There is a significant reduction in bone gain when healing complications occur. However, healing complications are relatively uncommon surgical complications after vertical GBR.

Posterior jaws rehabilitation with < 7mm-short implants. A review

INTRODUCTION

The results with shorter and shorter implants have been revolutionizing the implantology scenario and are worthy of being well-analyzed and understood. This review aims to add further knowledge about the last 10-years observation period on < 7mm-short implants in the posterior atrophic jaws, better defining the indication of their use.

METHODS

From a Medline database research, systematic reviews, controlled and no- controlled trials (CT, n-CT) with ≥ 3years-follow-ups on <7 mm / ≥ 5mm-short implants (group A), and clinical studies with ≥ 1year-follow-up on 4mm-short implants (group B) were considered. The outcomes, in terms of implant survival rate (SR), marginal bone loss (MBL), and complications were analyzed according to the duration of follow-ups, implant site (maxilla and mandible), type of prosthesis (single crown or splinted units), vertically impaired or normal sites.

RESULTS

Thirty-four trials (28 for group A and six for group B) were selected. Group A: a mean follow up of 5,8 (3-10) years came out; pre-and post-loading SR range was 94.4- 100% and 89.6-100%, respectively; the range of MBL was 0.12-1.49; 50% of CT found less statistically significant surgical complications in comparison with standard implants (ST) in reconstructed sites, while major prosthetic problems were recorded with short -implants (SH) in 37.5% of CT; in no atrophied sites, a mean SR range of 86.7-100 % vs. 88-100 % and a total bone loss of 2 vs.1.6 for SH vs.ST emerged. Group B: the overall mean follow-up period was 2,3 years, and the pre-and post- SR ranges were 93-100 % and 87.5-100 %, respectively. The MBL range was 0.02- 0.63 mm. All RCT reported significantly fewer surgical complications with SH than with ST in reconstructed mandibles within one year. No prosthetic complications were reported for up to 5 years using no pontics or cantilevers fixed bridges.

CONCLUSIONS

Similar or even better results for SH than ST in terms of post-loading SR and MBL came out for < 7mm/ ≥ 5mm-short implants in atrophic bone regardless of the prosthetic solutions, with less surgical complications but a few more prosthetic problems; the good results up to 5 years for 4mm-short implants in mandibles are associated with splinted and no-risk prosthetic solutions.

A 4 mm-Long Implant Rehabilitation in the Posterior Maxilla with Dynamic Navigation Technology: A Case Report after a Three-Years Post-Loading Follow-Up

The use of short (<8 mm long) and ultra-short (<6 mm long) implants allows the prosthetic rehabilitation of the posterior ridges of the jaws avoiding reconstructive procedures. Nevertheless, this approach requires vast experience to ensure the primary stability of the fixture in a correct position. Computer-aided implantology (CAI) achieves better results than the free-hand one in terms of placement accuracy, reducing the surgical risks and the operative timings. Dynamic navigation (DN) allows the surgeon to track the position and movements of the drill in real-time on the CT imaging data set. It is more versatile than the computed static system, enabling the operator to change the guidance coordinates according to the intra-operative feedbacks. A mono-edentulous upper right first molar site was rehabilitated with a four mm-long implant to avoid reconstructive techniques, drastically rejected by the patients. The case was managed within a DN protocol considering the minimal available bone and the prosthetic demands. The phases of this procedure were strictly documented up to a 3-year follow-up. No intra-operative problems occurred, and adequate primary stability of the implant was obtained. The prosthetic loading was carried out within only six weeks without any complications. No variation of the baseline clinical scenario as evidenced clinically and radiographically at the end of follow-up. No similar cases are reported in the literature.

Short implants without bone augmentation vs. long implants with bone augmentation: systematic review and meta-analysis

PURPOSE

Anatomical limits such as the location of the lower alveolar nerve, the maxillary sinus in atrophied jaws might extend implant surgery treatment. The purpose of this systematic literature review is to review the literature and determine whether short implants can be an effective alternative to standard-length implants after bone augmentation.

MATERIALS AND METHODS

A systematic search was performed on PRISMA wizard. Searched for clinical trials 2010-2020 in the Medline database. The keywords chosen are "short versus long implants, augmented bone, clinical trial", and their various variations.

RESULTS

Meta-analyses of the studies of implant loss after 1, 3 and 5 years showed a statistically insignificant difference between groups. The number of complications after 1 year was statistically significantly higher in the control group. Meta-analyses with follow-up periods of 3 and 5 years showed a statistically insignificant difference; Meta-analyses of studies of marginal bone loss after 1, 3 and 5 years showed a statistically insignificant difference between the groups.

CONCLUSIONS

Short dental implants may be a suitable alternative to standard length dental implants after bone augmentation. The risk of their complications is possibly lower because of the lack of need for bone augmentation.

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).

Two-Year Follow-Up of 4-mm-Long Implants Used as Distal Support of Full-Arch FDPs Compared to 10-mm Implants Installed after Sinus Floor Elevation. A Randomized Clinical Trial

BACKGROUND

In edentulous patients, bone resorption cannot allow the installation of standard implants and it is demanded to use short implants in the residual alveolar bone or longer implants in grafted bone.

AIM

To compare the survival and bone level changes of standard plus short 4-mm implants used as distal support of a maxillary full-arch fixed dental prostheses (FDPs) with standard (10-mm) implants placed in association with a bilateral sinus floor augmentation procedure.

MATERIAL AND METHODS

Full-arch FDPs supported by six implants were randomly placed in both groups. In the control group, all implants were 10 mm long and 4.1 mm in diameter. The distal implant in both sides of the maxilla was installed after 4 months from bilaterally sinus floor elevation. In the test group (short group), the distal implant in both sides of the maxilla was 4 mm long and 4.1 mm in diameter. No sinus floor elevations were performed in the test group. Clinical assessments and X-rays were taken at prosthesis delivering and after 6, 12, 18, and 24 months. Patient-reported outcome measures (PROMs) were also evaluated before surgery and after 6, 12, and 24 months.

RESULTS

The changes over time of the bone level for the short implants were -0.01 ± 0.11 mm, -0.04 ± 0.13 mm, -0.17 ± 0.29 mm, and -0.28 ± 0.37 mm after 6, 12, 18, and 24 months from prosthesis delivering, respectively. For the standard implants, bone changes were -0.21 ± 0.33 mm (p = 0.103), -0.30 ± 0.32 mm (p = 0.023), -0.40 ± 0.37 mm (p = 0.144), and -0.54 ± 0.49 mm (p = 0.128), respectively. A statistically relevant difference was found only at 12 months after loading between the two groups.

CONCLUSIONS

Similar results on implant survival rate and marginal bone loss were observed for the short and standard implants, placed in association with a bilateral sinus floor augmentation procedure, used as distal support of a maxillary full-arch FDP. A statistically relevant difference was found only at 12 months after loading between the two groups (p = 0.023).

Clinical Comparation of Extra-Short (4 mm) and Long (>8 mm) Dental Implants Placed in Mandibular Bone: A Systematic Review and Metanalysis

This systematic review (SR) aimed to evaluate implant survival rate, marginal bone loss (MBL), and biological/prosthetic complications of extra-short 4 mm dental implants. An electronic search without language or date restrictions was performed in five databases and in gray literature for articles published until August 2020. Prospective cohort studies and randomized clinical trials (RCTs) that evaluated the clinical performance of extra-short 4 mm dental implants were included. Studies were independently assessed for risk of bias using the Cochrane Collaboration’s tool. The protocol of this SR was registered in the PROSPERO database under number CRD42019139709. Four studies were included in the present SR. There was no significant difference in implant survival rate (p = 0.75) between extra-short 4 mm and long implants. After 12 months of function, the extra-short implants had a significantly (p = 0.003) lower marginal bone loss (MBL) rate when compared to long implants. Extra-short implants had a lower number of biological and prosthetic complications when compared to long implants. After 12 months of follow-up, extra-short 4 mm dental implants placed in the mandible exhibit satisfactory clinical outcomes concerning implant survival rate and MBL when compared to longer implants, with a low number of biological and prosthetic complications. A higher number of RCTs with longer follow-up is necessary for the future.

Short implants (≤6mm) as an alternative treatment option to maxillary sinus lift

The aim of this systematic review was to evaluate survival rate of short dental implants placed in the posterior area of the maxilla. The electronic literature search of studies published between January 1, 2010 and February 29, 2020 was performed using specific word combinations. The outcome was to meta-analyse the implant survival rate (ISR). The search generated 238 potential studies. After screening procedures, only nine randomized controlled trials fulfilled the inclusion criteria and were selected for qualitative and quantitative analysis. ISR of short implants ranged from 91.9% to 100%, while standard-length implants ISR ranged from 82.9% to 100% with a follow-up from 1 to 5 years in function. The risk ratio difference was 1.24 (95% confidence interval: 0.63-2.45, P=0.52) for short dental implants failure when compared with standard dental implants, and was not statistically significant. Based on the evidence of the included studies, short implants (≤6mm) reported high survival rates over short to medium follow-up in posterior maxilla, but the long-term success is as yet not demonstrated.

Vertical bone augmentation and regular implants versus short implants in the vertically deficient posterior mandible: a systematic review and meta-analysis of randomized studies

The aim of this study was to perform a systematic review and meta-analysis of randomized controlled trials (RCTs) comparing the outcomes of short dental implants (≤7mm) versus vertical bone augmentation followed by regular dental implants (>7mm) in the deficient posterior mandible. In total, eight RCTs (six using interpositional sandwich grafting and two using a guided bone regeneration technique) were reported in 17 articles at different time points. In the meta-analysis of the sandwich group, the relative risk (RR) for implant loss at 1year was in favour of short implants (RR 0.41, P=0.02), while no significant difference was found at 3 years (RR 0.65, P=0.43), 5 years (RR 1.08, P=0.86), or 8 years (RR 1.53, P=0.52). The risk of complications was in favour of short implants (RR 0.34, P=0.0002), as was the mean difference in marginal bone resorption after 1 year (-0.09mm, P=0.17), 3 years (-0.32mm, P<0.00001), 5 years (-0.65mm, P<0.00001), and 8 years (-0.88, P<0.00001). The mean residual osseointegration length of the implants was between 2.94mm and 4.44mm in the short implants group and between 7.97mm and 8.62mm in the regular implants group after 5 years. In conclusion, in the deficient atrophic posterior mandible, short implants and regular implants demonstrate comparable outcomes within the first 5 years. Patients who are fit for surgery should be informed about the risks and benefits of both options.

Comparative Analysis of Peri-Implant Bone Loss in Extra-Short, Short, and Conventional Implants. A 3-Year Retrospective Study

Objective: To evaluate the influence of implant length on marginal bone loss, comparing implants of 4 mm, 6 mm, and >8 mm, supporting two splinted crowns after 36-month functional loading. Materials and Methods: this retrospective clinical trial evaluated the peri-implant behavior of splinted crowns (two per case) on pairs of implants of the same length placed in the posterior maxilla (molar area). Implants were divided into three groups according to length (Group 1: extra-short 4 mm; Group 2: short 6 mm; Group 3: conventional length >8 mm). Marginal bone loss was analyzed using standardized periapical radiographs at the time of loading and 36 months later. Results: 24 patients (19 women and 5 men) were divided into three groups, eight rehabilitations per group, in the position of the maxillary first and second molars. The 48 Straumann^® Standard Plus (Regular Neck (RN)/Wide Neck (WN)) implants were examined after 36 months of functional loading. Statistical analysis found no significant differences in bone loss between the three groups (p = 0.421). No implant suffered biological complications or implant loss. Long implants were associated with less radiographic bone loss. Conclusions: extra-short (4 mm); short (6 mm); and conventional length (>8 mm) implants in the posterior maxilla present similar peri-implant bone loss and 100% survival rates in rehabilitation, by means of two splinted crowns after 36 months of functional loading. Implants placed in posterior positions present better bone loss results than implants placed in anterior positions, regardless of the interproximal area where bone loss is measured. Conventional length (>8 mm) implants show better behavior in terms of distal bone loss than short (6 mm) and extra-short (4 mm) implants.