Short implants (≤6 mm) versus longer implants with sinus floor elevation in atrophic posterior maxilla: a systematic review and meta-analysis

Short (≤6 mm) compared with ≥10-mm dental implants in different clinical scenarios: A systematic review of randomized clinical trials with meta-analysis, trial sequential analysis and quality of evidence grading

AIM

To systematically identify, synthesize and critically summarize the available scientific evidence from randomized controlled trials (RCTs) regarding whether short (≤6 mm) perform as well as long (≥10 mm) implants regarding implant survival, marginal bone loss, and biologic and prosthetic complications in different clinical scenarios.

MATERIALS AND METHODS

Cochrane Collaboration's risk of bias tool and the GRADE approach were applied. Results were synthesized using random-effects meta-analyses assessed by trial sequential analyses.

RESULTS

Forty reports on 19 RCTs comprising 2214 (1097 short; 1117 long) implants were included. Moderate/high certainty/quality evidence demonstrated similar 5-year survival rates for ≤6-mm and ≥10-mm implants in non-augmented bone and full-mouth rehabilitation in either jaw, and for 6-mm implants in the maxilla instead of sinus lift. Nevertheless, the evidence for 5-year survival rates remains inconclusive or insufficient for the remaining combinations of implant lengths and clinical scenarios. They include 4-mm and 5-mm implants as alternatives to sinus lift as well as placing all implant lengths ≤6 mm instead of vertical ridge augmentation with long implants. Marginal bone level and short- and long-term biologic or prosthetic complications were similar.

CONCLUSIONS

Based on moderate/high certainty/quality evidence from 5-year RCTs, implants ≤6 mm may be viable alternatives to ≥10-mm implants in either jaw in native bone and full-arch rehabilitation, and 6-mm implants may be used as an alternative to sinus lift.

TRIAL REGISTRATION

PROSPERO ID: CRD42021254365.

Are short implants (≤8.5 mm) reliable in the rehabilitation of completely edentulous patients: A systematic review and meta-analysis

STATEMENT OF PROBLEM

Limited data are available regarding the reliability of short implants (≤8.5 mm) in patients with resorbed completely edentulous jaws.

PURPOSE

The purpose of this systematic review and meta-analysis was to compare the clinical outcomes of short implants (intervention) versus long implants (≥10 mm, comparison) in the rehabilitation of completely edentulous jaws.

MATERIAL AND METHODS

The PubMed, Embase, and Cochrane CENTRAL databases were searched for randomized controlled trials (RCTs) comparing short and long implants supporting fixed or removable prostheses in completely edentulous jaws. Outcome measures included implant survival, marginal bone loss (MBL), and biological and technical complications. The risks of bias within and across the studies were assessed, and meta-analyses, sensitivity analyses, and subgroup analyses by types of prostheses, jaw locations, and follow-up length were performed.

RESULTS

A total of 4 RCTs with 158 participants were included. No significant difference was found between short implants and long implants regarding implant survival (RR=1.01, 95% CI: 0.97 to 1.05, P=.710, I2=70%) or MBL (MD=-0.19 mm, 95% CI: -0.39 to 0.02, P=.070, I2=94%). In subgroup analyses, when supporting fixed prostheses, short implants showed significantly less MBL than long implants (P<.001). In the mandible, short implants showed higher implant survival (P=.008) and less MBL (P<.001). Participants receiving long implants combined with bone augmentation procedures reported more postsurgery pain.

CONCLUSIONS

For completely edentulous jaws, short implants provide a reliable treatment alternative, as survival and MBL were not different when compared with those of long implants. However, additional high-level evidence is still needed to determine the long-term clinical outcomes of short implants in completely edentulous jaws.

Clinical performance of additively manufactured subperiosteal implants: a systematic review

PURPOSE

The aim of this study was to assess implant survival and complications rate of modern subperiosteal implants (CAD designed and additively manufactured).

METHODS

A systematic review was conducted using three electronic databases; Medline (Pubmed), Cochrane library, and SCOPUS, following the PRISMA statement recommendations to answer the PICO question: "In patients with bone atrophy (P), do additively manufactured subperiosteal implants (I), compared to subperiosteal implants manufactured following traditional approaches (c), present satisfactory implant survival and complication rates (O)? The study was pre-registered in PROSPERO (CRD42023424211). Included articles quality was assessed using the "NIH quality assessment tools".

RESULTS

Thirteen articles were finally selected (5 cohort studies and 8 case series), including 227 patients (121 female / 106 male; weighted mean age 62.4 years) and 227 implants. After a weighted mean follow-up time of 21.4 months, 97.8% of implants were in function (5 failures reported), 58 implants (25.6%) presented partial exposure, 12 patients (5.3%) suffered soft tissue or persistent infection. Fracture of the interim prosthesis was reported in 8 of the155 patients (5.2%) in which the use of a provisional prosthesis was reported. A great heterogeneity was found in terms of study design and methodological aspects. For this reason, a quantitative analysis followed by meta-analysis was not possible.

CONCLUSIONS

Within the limitations of this study, modern additively manufactured subperiosteal implants presented a good survival in the short-time, but a noticeable number of soft-tissue related complications were reported. Further studies are needed to assess the clinical behavior in the medium- and long-term.

Restoratively driven planning for implants in the posterior maxilla - Part 2: implant planning, biomechanics and prosthodontic planning a proposed prosthodontic complexity index

Restoratively driven implant planning in the posterior maxilla requires a comprehensive understanding of the anatomical and physiological changes of the alveolar bone following tooth extraction and sinus augmentation. As a part of restoratively driven planning, alveolar bone, inter-arch relationships, proposed crown-implant ratio and anticipated non-axial loading should be assessed pre-operatively. This helps determine the prosthodontic and surgical aspects of implant treatment, such as prosthesis design, implant number, implant angulation, implant length and the necessity for additional bone grafting procedures. However, currently no implant planning classification is restoratively driven and include these important prosthodontic considerations. Therefore, a new index - the Posterior Maxilla Prosthodontic Index - is defined to encourage restoratively driven implant planning in the posterior maxilla.

Maxillary sinus floor augmentation: a review of current evidence on anatomical factors and a decision tree

Maxillary sinus floor augmentation using lateral window and crestal technique is considered as predictable methods to increase the residual bone height; however, this surgery is commonly complicated by Schneiderian membrane perforation, which is closely related to anatomical factors. This article aimed to assess anatomical factors on successful augmentation procedures. After review of the current evidence on sinus augmentation techniques, anatomical factors related to the stretching potential of Schneiderian membrane were assessed and a decision tree for the rational choice of surgical approaches was proposed. Schneiderian membrane perforation might occur when local tension exceeds its stretching potential, which is closely related to anatomical variations of the maxillary sinus. Choice of a surgical approach and clinical outcomes are influenced by the stretching potential of Schneiderian membrane. In addition to the residual bone height, clinicians should also consider the stretching potential affected by the membrane health condition, the contours of the maxillary sinus, and the presence of antral septa when evaluating the choice of surgical approaches and clinical outcomes.

Radiographic feature changes in an antral pseudocyst that existed prior to sinus floor augmentation and dental implant placement, 15 years after initial detection - a case report

INTRODUCTION AND IMPORTANCE

Maxillary sinus floor augmentation is acceptable and safe for bone augmentation prior to insertion of dental implants in atrophied maxillary bones. Anatomical variations and lesions of the maxillary sinus, including antral pseudocysts, are common radiological findings that can affect the outcomes of maxillary sinus augmentation. We show the changes in the radiological features of an antral pseudocyst that existed before maxillary sinus augmentation and 15 years after the insertion of dental implants.

CASE PRESENTATION

The patient was a 69-year-old male with an unremarkable medical history. The initial orthopantomogram revealed a very large antral pseudocyst in the left maxillary sinus. After upper left second molar extraction and maxillary sinus augmentation, two dental implants were inserted in regions 26 and 27. The pseudocyst had changed radiologically 15 years later, but a biopsy showed no characteristic changes, and the dental implants showed no functional failures.

CLINICAL DISCUSSION

We present a case of an antral pseudocyst that was not removed before or during sinus floor augmentation. A debate is ongoing regarding whether antral pseudocysts affect maxillary sinus augmentation, and various strategies have been applied to prevent intraoperative and postoperative complications, including removal of pseudocysts 3-12 months before maxillary sinus augmentation, removal during maxillary sinus augmentation, and leaving them alone when the floor is raised.

CONCLUSION

The present case showed a preexisting antral pseudocyst at maxillary sinus floor augmentation and insertion of the implants, which changed radiologically 15 years later, but did not affect the function of the dental implants.

Large Grafting Void Resembling a Surgical Ciliated Cyst following Maxillary Sinus Augmentation. Four Case Reports with Histological Observation

The cause and pathogenicity of grafting voids following lateral maxillary sinus augmentation (MSA) have not yet been elucidated. The first purpose of this case series is to introduce an unusually large grafting void that radiologically resembles a surgical ciliated cyst (SCC) at the sinus augmented site; the second is to observe the histological findings of these grafting voids. In four patients, MSA was performed using the lateral window technique. An unusually large grafting void appeared on cone-beam-computed tomography (CBCT) taken one week after surgery and except for one patient, there were no clinical symptoms. On CBCT taken six months after surgery, the grafting voids were slightly smaller in size but showed radiographic findings similar to those of SCC. During uncovering, grafting voids were removed through the lateral window site. Histologically, the grafting void was empty or filled with dense connective tissue, and no ciliated columnar epithelium or inflammatory cells were observed. Within the limitations of this case series, the large grafting voids generated after MSA was not converted to SCCs. Rather, they remained scar tissue, which could infringe the sinus bone graft and affect the apical bone support of the implant.

Short versus standard implants at sinus augmented sites: a systematic review and meta-analysis

BACKGROUND

Short implants are proposed as a less invasive alternative with fewer complications than standard implants in combination with sinus lift. The aim of this systematic review and meta-analysis was to state the efficacy of placing short implants (≤ 6 mm) compared to standard-length implants (≥ 8 mm) performing sinus lift techniques in patients with edentulous posterior atrophic jaws. Efficacy will be evaluated through analyzing implant survival (IS) and maintenance of peri-implant bone (MBL).

METHODS

Screening process was done using the National Library of Medicine (MEDLINE by PubMed), EMBASE, the Cochrane Oral Health, and Web of Science (WOS). The articles included were randomized controlled trials. Risk of bias was evaluated according to The Cochrane Collaboration's tool. Weighted means were calculated. Heterogeneity was determined using Higgins (I²). A random-effects model was applied. Secondary outcomes such as surgical time, patient satisfaction, mucositis and peri-implantitis, pain, and swelling were analyzed.

RESULTS

Fourteen studies (597 patients and 901 implants) were evaluated. IS was 1.02 risk ratio, ranging from 1.00 to 1.05 (CI 95%) (p = 0.09), suggesting that IS was similar when both techniques were used. MBL was higher in patients with standard-length implants plus sinus lift elevation (p = 0.03). MBL was 0.11 (0.01-0.20) mm (p = 0.03) and 0.23 (0.07-0.39) mm (p = 0.005) before and after 1 year of follow-up, respectively, indicating that the marginal bone loss is greater for standard-length implants.

DISCUSSION

Within the limitations of the present study, as relatively small sample size, short dental implants can be used as an alternative to standard-length implants plus sinus elevation in cases of atrophic posterior maxilla. Higher MBL was observed in the groups where standard-length implants were used, but implant survival was similar in both groups. Moreover, with short implants, it was observed a reduced postoperative discomfort, minimal invasiveness, shorter treatment time, and reduced costs.

CLINICAL CLINICAL RELEVANCE

The low MBL promoted by short implants does contribute to a paradigm shift from sinus grafting with long implants to short implants. Further high-quality long-term studies are required to confirm these findings.

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.

Intraoperative complications and early implant failure after transcrestal sinus floor elevation with residual bone height ≤5 mm: A retrospective multicenter study

OBJECTIVE

Clinical indications for maxillary sinus floor elevation with transcrestal techniques have increased in recent years even in sites with minimal residual bone height (RBH). Nevertheless, limited information is currently available on incidence of intraoperative complications and early implant failure in these cases.

MATERIAL AND METHODS

This retrospective multicenter study was performed on anonymized clinical and radiographic records of patients who underwent transcrestal sinus floor elevation in seven clinical centers. Influence of different factors related to patient, sinus anatomy and surgical technique on the incidence of intraoperative complications and early implant failure rate after transcrestal sinus lift were investigated.

RESULTS

A total of 430 patients treated with transcrestal sinus floor elevation for single implant insertion in sites with RBH ≤5 mm were included in the final analysis. After one year of loading, 418 implants out of 430 were satisfactorily in function. Early implant failure was recorded in 12 cases (2.8%), resulting significantly associated with the presence of large sinus cavities and with the occurrence of membrane perforation. The following adverse events were recorded: membrane perforation (7.2%), acute sinusitis (0.9%), implant displacement into the sinus cavity (0.7%), oro-antral fistula (0.2%) and benign paroxysmal positional vertigo (0.5% of osteotome cases). A strong direct correlation between sinus membrane perforation and bucco-palatal sinus width (p=0.000) was demonstrated.

CONCLUSIONS

Early implant failure after transcrestal sinus elevation showed significant direct correlation with bucco-palatal maxillary sinus width and the presence of membrane perforation. Sinus membrane perforation was strongly associated with bucco-palatal sinus width (extremely low perforation rate in narrow and much higher incidence in wide sinuses).

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.

Short vs. regular length implants to rehabilitate partially edentulous mandible: a 2-year prospective split-mouth clinical study

Many studies have evaluated short implants (SIs); however, it is still unclear whether SIs are reliable and can be used to simplify surgical and prosthetic protocols with successful clinical outcomes. The aim of this non-random, conveniently sampled, prospective, split-mouth study was to compare the clinical outcomes when short (SI) (≤8 mm) or regular-length implants (RIs) (>10 mm) were used in the posterior mandible two years after the delivery of splinted reconstructions. Each participant (N=10) received four implants in the posterior mandible; two SIs were placed on one side, and two RIs were placed contra-laterally. Implants were restored with splinted, screw-retained, porcelain-fused-to-metal reconstructions. Survival and success rates, peri-implant marginal bone level (MBL), and soft tissue parameters were evaluated. No participant drop-outs were recorded. Both types of implants showed 100% success and survival rates. From prosthetic delivery to 24 months post-loading, bone remineralization of +0.40 mm for the SIs and +0.36 mm for the RIs was observed without statistically significant differences in MBL between the implant types (p=0.993). SIs showed significantly higher (p=0.001) clinical attachment level (CAL) and probing depth (PD) values. Chipping occurred in one situation in the RI group resulting in a 97.5% prosthetic success rate, which was 100% for the SIs. After 2 years, SIs with splinted reconstructions showed comparable clinical outcomes to those of RIs. Further long-term controlled clinical studies with balanced experimental designs evaluating random and larger populations are required to corroborate these findings.

Ultra-short versus standard-length dental implants in conjunction with osteotome-mediated sinus floor elevation: A randomized controlled clinical trial

BACKGROUND

The ability to restore missing teeth with dental implants is dictated by the available bone and by the presence of anatomical structures. The potential to insert ultrashort implants avoids additional surgical procedures and its inherent complications. The last European Association of Dental Implantologists consensus in 2016 defined ultrashort implants and standard-length dental implants as <6 and >8 mm, respectively.

PURPOSE

The present study aimed to investigate whether single standing ultrashort dental implants (US) could provide a viable therapeutic alternative to osteotome mediated sinus floor elevation in combination with standard-length dental implants (SL) 10 mm in posterior maxillary rehabilitation with reduced bone height.

MATERIALS AND METHODS

The study was conducted as a prospective parallel group controlled clinical trial with a 12 month follow-up, where 48 implants were randomized into two groups; US-group (5.5 mm) and SL-group (10 mm) implants placed with osteotome-mediated sinus floor elevation. Crestal bone loss (CBL) was defined as the study's primary outcome, while implant survival, buccal bone thickness, implant stability, probing depth, gingival recession, and adverse effects were assessed as secondary outcomes.

RESULTS

Mesial CBL was 1.13 ± 0.52 mm in SL- and 0.72 ± 0.52 mm in US-group (P = .021), while distal CBL was 1.44 ± 0.72 mm in SL- and 0.91 ± 0.69 mm in US-group at 12 months (P = .0179). Regarding implant stability, probing depth, and gingival recession there was no statistically significant difference between the two groups. Regarding implants' survival, three implants were lost in the US-while only one implant was lost in the SL-group (P = .6085; Fisher's exact test). Nevertheless, the ultrashort implants were associated with a tripling of the failure rate and uncertainty where the true failure rate is uncertain (relative risk 3.0; confidence interval 0.3-26.8).

CONCLUSIONS

Within the current trial's limitations, US-appear appear promising as they are associated less postoperative discomfort, minimal invasiveness and less CBL. However, larger sample size is required to determine whether the ultrashort have an acceptable survival rate.

Failure Risk of Short Dental Implants Under Immediate Loading: A Meta-Analysis

PURPOSE

Currently, there is no clear clinical evidence that short implants are suitable for immediate loading. Therefore, this meta-analysis aims to evaluate whether immediate loading increases the failure risk of short dental implants.

MATERIALS AND METHODS

This meta-analysis was registered at PROSPERO (CRD 42020195890). PubMed, Embase, and Cochrane Library databases were searched to collect all clinical studies comparing the failure rates of short dental implants (<10 mm) and standard implants (≥10 mm) under the condition of immediate loading and studies comparing the failure rates of short dental implants under immediate loading versus early or delayed loading. All of the clinical studies with available relevant data were eligible for inclusion. The Cochrane Risk of Bias tool was adopted to evaluate the risk of bias for the randomized controlled trial (RCT), while Newcastle-Ottawa Quality Assessment Scale (NOS) was used for the observational studies (OS). The OR value of each included study and its 95% CI were pooled to estimate the failure risk of short dental implants under immediate loading. The heterogeneity among studies was evaluated through Cochran's Q test and I² .

RESULTS

Seventeen studies, 5 RCTs and 12 OS studies, with a total of 2461 dental implants were analyzed. Four of the RCT studies were of low risk of bias and one was of unclear risk, while all of the OS studies were of moderate or high quality. Compared with standard implants, short implants did not have an increased failure risk under immediate loading (OR: 1.38, 95% CI: 0.67-2.84, p = 0.997, fixed model). In addition, the OR value of implant failure for short implants under immediate loading compared to that for short implants under early or delayed loading was 1.22 (95% CI: 0.33-4.55, p = 0.104, random model), which was also not significantly different.

CONCLUSIONS

There is not enough evidence to show that short dental implants under immediate loading may have higher implant failure risk compared to standard implants under immediate loading and short implants under early or delayed loading. Therefore, an immediate loading protocol may not increase the failure risk of short dental implants.

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.

Short Dental Implants (≤8.5 mm) versus Standard Dental Implants (≥10 mm): A One-Year Post-Loading Prospective Observational Study

Background: Recent data have shown that short dental implants can be the preferred treatment in most of cases of posterior atrophic alveolar ridges, offering higher survival and lower complication rates than long implants. The survival rates, stability, and marginal bone level changes were compared between short implants (7 and 8.5 mm) and standard-length implants (≥10 mm). Methods: Prospective observational study in which adult patients requiring ≥1 osseointegrated implants to replace missing teeth were recruited consecutively. A clinical examination was performed on the day the definitive prosthesis was placed and after 6 and 12 months. Implant stability quotient (ISQ), marginal bone level (MBL) changes, and the correlation between these parameters and the characteristics of the implants were evaluated. Results: A total of 99 implants were inserted (47 short, 52 standard) in 74 patients. The 12-month survival rate was 100%. ISQ values showed a similar pattern for both types of implants. No correlation was found between ISQ changes after one year and MBL values, nor between the latter and the characteristics of the implants. Conclusions: With clinical treatment criteria, shorter implants (7 and 8.5 mm in length) can be just as useful as standard-length implants in atrophic alveolar ridges, demonstrating similar rates of survival, stability, and crestal bone loss.

The survival rate of transcrestal sinus floor elevation combined with short implants: a systematic review and meta-analysis of observational studies

Background

Currently, insufficient bone volume always occurs in the posterior maxilla which makes implantation difficult. Short implants combined with transcrestal sinus floor elevation (TSFE) may be an option to address insufficient bone volume.

Purpose

The clinical performance of short implants combined with TSFE was compared with that of conventional implants combined with TSFE according to the survival rate.

Method

In this systematic review and meta-analysis, we followed the Meta-Analysis of Observational Studies in Epidemiology (MOOSE) guidelines. Articles were identified through PubMed, Embase, the Cochrane Library, and manual searching. Eligibility criteria included clinical human studies. The quality assessment was performed according to the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines. The odds ratio (OR) with its confidence interval (CI) was considered the essential outcome for estimating the effect of short implants combined with TSFE.

Results

The registration number is INPLASY202050092. Eleven studies met the inclusion criteria, including 1 cohort study and 10 cross-sectional studies. With respect to the 1-year survival rate, no significant effect was observed between short implants (length ≤ 8 mm) and conventional implants combined with TSFE (I²=0%, OR=1.04, 95% CI: 0.55-1.96). Similarly, no difference was seen between the two groups regarding the survival rate during the healing period (I²=10%, OR=0.74, 95% CI: 0.28-1.97) and 3-year loading (OR=1.76, 95% CI: 0.65-4.74).

Conclusion

There was no evidence that the survival rate of short implants combined with TSFE was lower or higher than that of conventional implants combined with TSFE when the residual bone height was poor and the implant protrusion length of short implants was less than or similar to conventional implants. Nevertheless, the results should be interpreted cautiously due to the lack of random controlled trials in our meta-analysis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40729-021-00325-y.

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).

The risk factors of early implant failure: A retrospective study of 6113 implants

BACKGROUND

The risk factors of early implant failure were controversial among previous studies, especially for implants in different sites.

PURPOSE

To analyze the rate and risk factors of early implant failure occurring before the placement of final prosthesis.

MATERIALS AND METHODS

A retrospective study was conducted based on electrical medical records of patients who received dental implant placement from 2015 to 2019. Generalized estimation equation analyses were used to explore potential risk factors influencing early implant failure.

RESULTS

Overall, 6113 implants in 3785 patients were included. The rate of early implant failure was 1.6% at patient level and 1.2% at implant level. The early implant failure was significantly associated with implants in the posterior maxilla, with specific surface modifications and in previously augmented sites (p < 0.05). Risk factors for maxillary implants included surface modification and bone augmentation procedures (p < 0.01), whereas risk factors for mandibular implants included gender and bone augmentation procedures (p < 0.05). For implants placed in previously augmented sites, implants placed in the anterior mandible had a higher risk of early failure (p < 0.05).

CONCLUSIONS

The risk factors for early implant failures varied among different sites; hence, they should be comprehensively considered in presurgical treatment plan.

The rehabilitation of posterior atrophic maxilla by using the graftless option of short implant versus conventional long implant with sinus graft: A systematic review and meta-analysis of randomized controlled clinical trial

Aim

The purpose of systematic review and meta-analysis was to compare the efficacy of short implant versus conventional long implant with sinus graft in patients rehabilitated for posterior atrophic maxilla.

Setting and Design

Systematic review and meta analysis.

Materials and Methods

Electronic searches were conducted in Pub Med, Embase, and Medline with supplemented by manual search up to December 2019. The randomized controlled trial (RCTs) comparing short implant (<8.5 mm) and long implant (>8.5 mm) with sinus graft were included. (Prospero CRD42020186972).

Statistical Analysis Used

Random-effect model, fixed-effect model, A funnel plot and the Egger's test.

Results

Twenty-two Randomized controlled trials (RCTs) were assessed with 667 patients and 1595 implants (short implant:767, Long implant:835). No significant difference of implant survival rate was recorded for short and long implant (at patient level: RR: 1.01, 95% CI = 0.52-2.0, P = 0.87, I2 = 0%, at implant level RR = 1.09, 95% CI = 0.6-2.0, P = 0.7, I2 = 0%). Similarly marginal bone resorption was reported no difference for short and long implant (MD = 0.16. 95% CI: -0.23 = -0.08, P = 0.00, I2 = 74.83%). Biological complications were marginally higher for long implant (RR = 0.48, 95% CI = 0.23-0.8, P = 0.13, I2 = 29.11%). and prosthetic complications were marginally higher for short implants (RR=1.56, 95% CI=0.85-3.15, P = 0.43, I2 = 0%).

Conclusion

There was no significance difference in implant survival rate and marginal bone resorption recorded for both the short implant and long implant with sinus graft, in the patients rehabilitated with posterior atrophic maxilla. Hence, short implant is a suitable alternative to long implant with sinus graft, for the rehabilitation posterior atrophic maxilla.

A Minimally Invasive Technique for Short Spiral Implant Insertion with Contextual Crestal Sinus Lifting in the Atrophic Maxilla: A Preliminary Report

The most recently reported techniques for the rehabilitation of the atrophic posterior maxilla are increasingly less invasive, as they are generally oriented to avoid sinus floor elevation with lateral access. The authors describe a mini-invasive surgical technique for short spiral implant insertion for the prosthetic rehabilitation of the atrophic posterior maxilla, which could be considered a combination of several previously described techniques based on the under-preparation of the implant site to improve fixture primary stability and crestal approach to the sinus floor elevation without heterologous bone graft. Eighty short spiral implants were inserted in the molar area of the maxilla in patients with 4.5–6 mm of alveolar bone, measured on pre-operative computed tomography. The surgical technique involved careful drilling for the preparation of implant sites at differentiated depths, allowing bone dislocation in the apical direction, traumatic crestal sinus membrane elevation, and insertion of an implant (with spiral morphology) longer than pre-operative measurements. Prostheses were all single crowns. In all cases, a spiral implant 2–4 mm longer than the residual bone was placed. Only two implants were lost due to peri-implantitis but subsequently replaced and followed-up. Bone loss values around the implants after three months (at the re-opening) ranged from 0 to 0.6 mm, (median value: 0.1 mm), while after two years, the same values ranged from 0.4 to 1.3 mm (median value: 0.7 mm). Clinical post-operative complications did not occur. After ten years, no implant has been lost. Overall, the described protocol seems to show good results in terms of predictability and patient compliance.

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.

Short versus standard implants associated with sinus floor elevation: An umbrella review of meta-analyses of multiple outcomes

STATEMENT OF PROBLEM

Bone loss in the edentulous posterior maxilla complicates dental implant placement. In spite of the evidence available, there is continued uncertainty about the benefit of short implants for different outcomes.

PURPOSE

The purpose of this review was to evaluate the existing evidence for short and standard implants in association with sinus floor elevation regarding implant survival, marginal bone loss, and complications by using an umbrella review of the evidence across meta-analysis of interventional studies.

MATERIAL AND METHODS

Medline, Scopus, and Cochrane Library were searched to identify systematic reviews and meta-analyses comparing short implants and standard implants associated with sinus floor elevation. Data extraction and methodological quality (AMSTAR-2) was assessed by 2 authors independently. Outcomes were categorized and tabulated to assess effectiveness. Qualitative data were analyzed using thematic synthesis. The certainty of the evidence was evaluated with the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach.

RESULTS

From 2011 studies, 7 systematic reviews (66 studies) were included as per the eligibility criteria. There was no statistically significant difference between groups for implant survival (risk ratio=1.08; P=.79), and the qualitative analysis did not show differences for prosthetic outcomes. Standard implants were associated with fewer prosthetic complications in the quantitative analysis (risk ratio=3.27; P<.01), but no difference was found between the treatments in the qualitative analysis. Short implants showed reduced marginal bone loss (0.98 ±0.12 mm; mean difference=-0.22; P<.01) and better biologic outcomes (risk ratio=0.16; P<.01). Patient satisfaction was similar for both groups, whereas costs and time for the procedure favored short implants. The quality of the evidence was graded as "critically low" (57.1% of the reviews) and "low." There was a high certainty of evidence for implant survival, whereas marginal bone loss and complications had moderate certainty.

CONCLUSIONS

Short implants had a better or equal performance compared with standard implants for all outcomes assessed. However, assumptions were based on reviews with low or critically low quality of the evidence, suggesting the development of high-quality systematic reviews in this field.