Extra short dental implants supporting an overdenture in the edentulous maxilla: a proof of concept

An implant-supported overdenture for a mandibular defect after tumor resection guided by 3-dimensional finite element analysis: A clinical report

This clinical report describes the rehabilitation of a mandibular defect after tumor resection with an implant-supported overdenture and the attachment selection as guided by 3-dimensional finite element analysis. Autologous bone grafting was declined by the patient who demanded the restoration of lateral appearance and mastication function. Three implants were placed based on the condition of the bone, and a satisfactory definitive prosthesis was provided that corresponded with the results of the finite element analysis.

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.

The evaluation of stress on bone level and tissue level short implants: A Finite Element Analysis (FEA) study

PURPOSE

This study aimed to evaluate the difference between the stress level and distribution around the BL and TL short implants, and their surrounding structures, using finite element analysis.

METHODS

Two different study models were constructed: BL model and TL model. Two dental implant systems (ITI (Straumann, Waldenburg, Switzerland) and NTA Short) with a diameter of 4.1 mm and 4 mm and with a length of 6 mm were used in this study. In each model, implants were placed in the mandibular 1st molar region. The von Mises stress and maximum principal (tensile) and minimum principal (compressive) stresses were evaluated.

RESULTS

The highest stress values recorded in the BL implants (von Mises: 342.77 MPa), in the peri‑implant bone around the BL implants (maximum principal stress: 114.1 MPa), as a result of oblique loading, and overall stress values were found to be higher in the BL model. However, these measured values appeared to be low to cause a fracture, when considering the yield strengths of the materials and bone.

CONCLUSIONS

The stress values were higher in the BL model, but not high enough to cause failure. Short implants could be an effective method of treatment for patients unsuitable for advanced surgical techniques.

Impact of the extension of the anterior-posterior spread on quality of life and satisfaction of patients treated with implant-retained mandibular overdentures - a randomized clinical trial

OBJECTIVES

To compare the degree of satisfaction (SD) and the impact on oral health-related quality of life (OHRQoL) of edentulous patients treated with conventional complete dentures (CCDs) and mandibular overdentures (IODs) with a short anteroposterior spread (S-APS) or a large antero-posterior spread (L-APS).

MATERIALS AND METHODS

Edentulous patients were treated with CCDs and subsequently randomly allocated to receive a bar clip mandibular overdenture retained by 2 interforaminal implants (Control) or 4 (Test: 2 additional implants distal to the mental foramen). The Oral Health Impact Profile Edent questionnaire (OHIP-20E) and the Visual Analogue Scale (VAS) were applied at a mean follow-up of 38.5 months to assess the impact on OHRQoL and DS, respectively. Comparisons between the type of prosthesis and the extension of the AP spread were made with Student's t test for paired samples and for independent samples, respectively, at a significance level of 5%.

RESULTS

The IODs had significantly lower OHRQoL values ​​in the dimensions "functional limitation" (p=0.03), "physical pain" (p=0.02), "psychological discomfort" (p<0.01), "disability physical" (p<0.01) and "general score" (p<0.01) (n=20 patients). The IODs presented DS values ​​significantly for "aesthetics" (p=0.04), "stability" (p=0.03), "masticatory capacity" (p<0.01), "function" (p<0.01) and "oral condition" (p=0.03). The S-APS group (control) resulted in significantly lower values ​​in the dimensions "physical pain" (p<0.01) and "general score" (p<0.01) and no domain with statistical difference in the VAS scale.

CONCLUSIONS

IODs significantly improved OHRQoL and DS. The increase in AP spread did not result in benefits for the patient's OHRQOL and DS in this clinical study. (Study Protocol Number: 1.452.492) CLINICAL SIGNIFICANCE: Implantology has experienced in the last 20 years a permanent evolution that aim at increasing predictability and improving long-term clinical performance. Placement of short implants distally to the mental foramen, for instance, and the resulting increase of the anterior-posterior spread, is a promising approach and is worthy of investigation.

Efficacy of tooth-supported compared to implant-supported full-arch removable prostheses in patients with terminal dentition. A systematic review

AIMS

To compare tooth- (TSRP) and implant-supported (ISRP) removable prostheses in terms of abutment and prosthesis survival (PICO 1) and estimated cumulative survival of teeth/implants and prostheses (PICO 2) at ≥12-month post-prosthesis delivery in patients with stage IV periodontitis.

MATERIALS AND METHODS

Five databases were searched to identify RCTs, CCTs, single arms, prospective cohort studies, case series and retrospective studies. Duplicate screening was performed, and ranges for abutment and prosthesis survival were calculated.

RESULTS

Twenty-six studies were included in the qualitative assessment. Only one study with critical risk of bias comparing the two treatment modalities reported similar survival rates at 2 years. Overall, prospective studies on ISRPs indicated an implant survival rate ranging from 96.4% to 100% and a prosthesis survival rate of 100% with a follow-up from 12 to 54 months. Prospective studies on TSRPs indicated a tooth survival ranging from 85.71% to 100% at 1- to 10-years follow-up.

CONCLUSIONS

The available evidence is of poor quality, and it does not allow to make robust conclusions on the efficacy of these rehabilitations in stage IV periodontitis patients. Particularly for TSRPs, careful patient selection is crucial and a certain number of biological and prosthetic complications should be expected.

Efficacy of rehabilitation with different approaches of implant-supported full-arch prosthetic designs: A systematic review

AIM

To evaluate the efficacy of different types of rehabilitation with fixed or removable full-arch implant-supported prosthesis designs in terms of implant loss and success in patients with at least one edentulous jaw, with tooth loss mainly due to periodontitis.

MATERIALS AND METHODS

Clinical studies with at least 12 months reporting on implant loss and implant success were searched. Meta-analysis was conducted to estimate cumulative implant loss considering different prostheses designs.

RESULTS

A total of 11 studies with unclear to low risk of bias were included in the analysis. Estimated cumulative implant loss for fixed prostheses within 1 year and 5 years was 0.64% (95% confidence interval [CI]: 0.31%-1.31%) and 1.85% (95% CI: 0.85%-3.95%), respectively. The corresponding values for removable prostheses amounted to 0.71% (95% CI: 0.22%-2.28%) and 4.45% (95% CI: 2.48%-7.85%). Peri-implantitis affected 10%-50% of the patients restored with implant-supported fixed prostheses.

CONCLUSIONS

Based on the limited low-quality data, the present analysis points to a low and similar cumulative implant loss within 1 year for patients with tooth loss mainly due to stage IV periodontitis restored with either removable or fixed implant-supported full-arch prosthesis. At 5 years of functioning, there was a tendency for better outcomes using fixed designs.

A review of the recent literature on maxillary overdenture with dental implants

The recent literature on maxillary implant overdenture (IOD) was reviewed in order to clarify its predictability and establish treatment guidelines. Electronic searches were performed using PubMed, and articles about maxillary IOD written after 1990 were reviewed, focusing on the following items: I. implant survival rate, II. maxillary IOD survival rate, III. number of implants, IV. attachment type, V. follow-up period, VI. implant system, and VII. opposing dentition. The review revealed an implant survival rate of 61-100% and an overdenture survival rate of 72.4-100%. The attachments used included bars, balls, locators, and telescope crowns. The minimum and maximum observation periods were 12 months and 120 months, respectively, and the number of implants used for supporting IOD ranged from 2 to 8. At present, there is no strong evidence to indicate that maxillary IOD is clearly superior for all the items examined. However, the existing data indicate that maxillary IOD has almost the same therapeutic effect as fixed implant superstructures, and is a treatment option that can be actively adopted for patients in whom fixed superstructures cannot be applied for various reasons.

Patient satisfaction and survival of maxillary overdentures supported by four or six splinted implants: a systematic review with meta-analysis

Background

Implant-supported overdentures offer enhanced mechanical properties, which lead to better patient satisfaction and survival rates than conventional dentures. However, it is unclear whether these satisfaction levels and survival rates depend on the number of implants supporting the overdenture. Therefore, this systematic review aimed to compare maxillary overdentures supported by four or six splinted implants in terms of patient satisfaction, implant survival, overdenture survival, and prosthodontic complications.

Methods

Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (PubMed), and EMBASE databases were systematically searched and complemented by hand searching from 2000 to 2019, employing a combination of specific keywords. Studies comparing the use of four versus six implants for supporting overdentures with at least one-year of follow-up after prosthesis installation and including ten fully edentulous patients were included. The risk of bias (RoB) was analyzed with Cochrane’s RoB 2 and Newcastle–Ottawa tools. Implants and prosthesis survival rates were analyzed by random-effects meta-analysis and expressed as risk ratios or risk differences, respectively, and by the non-parametric unpaired Fisher’s test.

Results

A total of 15 from 1865 articles were included, and reported follow-up times after implant placement ranged from 1 to 10 years. Irrespective of the number of implants used, high scores were reported by all studies investigating patient satisfaction. Meta-analysis and non-parametric Fisher’s test showed no statistical differences regarding the survival rate of implants (P = 0.34, P = 0.3) or overdentures (P = 0.74, P = 0.9) when using 4 versus 6 splinted implants to support overdentures, and no significant differences regarding prosthodontic complications were found between groups. Randomized studies presented high RoB and non-randomized studies presented acceptable quality.

Conclusions

Within the limits of this systematic review, we can conclude that the bar-supported overdenture on four implants is not inferior to the overdenture supported by six implants for rehabilitating the edentulous maxilla, in terms of patient satisfaction, survival rates of implants and overdentures, and prosthodontic complications.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-021-01572-6.

Prospective, Clinical Pilot Study with Eleven 4-Mm Extra-Short Implants Splinted to Longer Implants for Posterior Maxilla Rehabilitation

In many clinical situations, rehabilitation with implants in the posterior maxillary region is complicated by limited bone availability. In this context, the use of 4 mm long implants (known as extra-short implants) may be used thanks to the concept of osseointegration enhancement. It has been demonstrated that short implants offer an alternative to the regeneration procedures involved in placing longer implants in areas where bone height is compromised. This prospective pilot study tested a treatment protocol in which 11 extra-short (4 mm) implants were splinted to 11 mesially placed longer (8 mm) implants in the posterior maxillary regions of partially edentulous patients, without using supplementary bone regeneration procedures. Eleven patients were included in this single cohort study. The clinical performance of the extra-short implants was assessed during a two-year follow-up period, obtaining a 100% survival rate and mean bone loss of 0.3 mm. Implant stability measured by resonance frequency analysis (RFA) at the time of placement was 54.9 ± 4.9, increasing to 77.0 ± 2.6 at 24 months. The study demonstrated the gradual consolidation of osseointegration in bone of less-than-ideal quality in the posterior maxillary region. The results obtained show that a partially edentulous maxilla with reduced bone height may be rehabilitated by using an extra-short implant splinted to a mesial implant of 8mm length or longer. Despite the small sample size, this pilot study observed that extra-short implants achieved adequate bone stability and clinical performance after a 24-month follow-up.

Extra-short implants in the prosthetic rehabilitation of the posterior maxilla

AIM

To compare clinical outcomes of 'extra-short' and regular bone level implants in the posterior maxilla for 12 months after loading.

MATERIALS AND METHODS

Twenty-three systemically healthy, non-smoking patients received 30 extra-short, 24 regular bone level implants. Acrylic stents were fabricated for each patient for correct implant positioning. Implant lengths were 4-6 mm in the test, 8/10 mm in the control group. Radiographic evaluation was performed at baseline, 6, and 12 months after loading. Crestal bone level (CBL), CBL change (CBLC), true crown length (TCL), implant/crown ratio (ICR) and residual bone height (RBH) below maxillary sinus floor were calculated digitally. Data were tested statistically.

RESULTS

Residual bone height was significantly lower, and TCL and ICR were higher in the test than the control group (P < 0.0001). CBL measurements at baseline were 0.19 ± 0.18 mm and 0.31 ± 0.37 mm and at 12 months, 0.24 ± 0.24 mm and 0.41 ± 0.31 mm, respectively in the test and control groups. CBL values at 12 months were significantly lower in the test than the control group (P < 0.05). CBLCs were similar at all times (P > 0.05). No correlation was found between the CBLC and implant/prosthetic parameters.

CONCLUSION

Extra-short and regular implants might provide similar clinical outcomes in prosthetic rehabilitation of atrophic maxilla, during 12 months follow-up.

A Finite Element Analysis to Compare Stress Distribution on Extra-Short Implants with Two Different Internal Connections

Background: The goal of this study was to analyze the stress distribution on two types of extra-short dental implants with 5 mm of length: An internal hexagon (IH) and morse taper connection (MT). Methods: The three-dimensional model was composed of trabecular and cortical bone, a crown, an extra-short dental implant and their components. An axial load of 150 N was applied and another inclined 30° with the same magnitude. Results: Stress concentrations on the IH implant are observed in the region of the first threads for the screw. However, in the MT implant the highest stress occurs at the edges of the upper implant platform. Conclusions: In view of the results obtained in this study the two types of prosthetic fittings present a good stress distribution. The Morse taper connections presented better behavior than the internal in both loading configurations.

Four or six implants in the maxillary posterior region to support an overdenture: 5-year results from a randomized controlled trial

OBJECTIVE

To compare clinical and patient-reported outcomes when providing maxillary overdentures on four bar- and six bar-connected implants placed in the posterior region during a 5-year follow-up period.

MATERIALS AND METHODS

Sixty-six fully edentulous patients with functional maxillary denture complaints and insufficient bone volume to allow implant placement were scheduled for a maxillary sinus floor elevation procedure with bone from the anterior iliac crest and randomized to receive either four or six implants in the posterior maxilla and four implants in the mandible. After 3 months of osseointegration, a bar-supported overdenture was constructed. Maxillary implant survival, overdenture survival, clinical scores, peri-implant bone height changes and patient satisfaction were assessed.

RESULTS

Sixty patients completed the 5-year follow-up. Implant survival was 100% in the four-implant group and 99.5% in the six-implant group. No new overdentures had to be made in the four-implant group, and three new overdentures were made in the six-implant group due to excessive wear of the denture base and teeth (90.9% overdenture survival). Clinical parameters did not differ significantly between groups. Mean marginal bone loss compared to baseline was 0.58 ± 0.51 mm in the four-implant group and 0.60 ± 0.58 mm in the six-implant group, respectively. Overall, patient satisfaction improved significantly, but did not differ between groups.

CONCLUSION

Following a bilateral maxillary sinus floor elevation procedure, a bar-supported overdenture on four implants in the posterior maxillary region is not inferior to an overdenture supported by six implants after a 5-year evaluation period in patients with functional maxillary denture complaints and marked posterior resorption (Clinical trial registration number: NTR2969).

The number of implants required to support a maxillary overdenture: a systematic review and meta-analysis

PURPOSE

The number of implants needed to support a maxillary overdenture is still a controversial issue. The aim of this systematic review was to investigate the number of implants required to support a maxillary overdenture in order to obtain optimal treatment outcomes in terms of implant survival, overdenture longevity and patient satisfaction.

STUDY SELECTION

Pubmed and EMBASE databes were systematically searched and complemented by hand searching from 2000 to 2017. The Prisma statement and a PICOS approach were adopted. All selected articles provided at least two-year follow-up and 10 totally edentulous patients. Survival rate of implants and overdentures were statistically analyzed according to number of implants and according to splitting technique, employing non-parametric Fisher Test for unpaired data. For the pooled analysis of implant failures, the odds ratio between group of 4 splinted implants and group of more than 4 splinted was calculated.

RESULTS

A total of 28 articles were included. Data analysis of the included studies showed that the survival rate of implants appeared higher in ≥ 4 implants group, whereas the high survival rate of overdentures and patient satisfaction were not significantly influenced by the number of implants.

CONCLUSIONS

The findings of our analysis indicate that overall the most frequent tendency is to place at least four implants, splinted or unsplinted, in order to ensure a higher survival rate of implants. However, the relationship between overdenture survival, the patient's quality of life, and the number of implants required to support a maxillary overdenture has yet to be clarified.

Influence of implant number, length, and tilting degree on stress distribution in atrophic maxilla: a finite element study

This study aims to evaluate the stress values, created in peri-implant region as a consequence of loading on fixed hybrid dentures that was planned with different implant numbers, lengths, or tilting angulations. Thirteen three-dimensional (3D) finite element analysis models were generated with four, five, or seven implants (group A, B, and C). Except the distal implants, all implants were modeled at 4.1 mm (diameter) and 11.5 mm (length) in size. Distal implants were configured to be in five different lengths (6, 8, 11.5, 13, and 16 mm) and three different implant inclination degrees (0°, 30°, and 45°). A 150-N load was applied vertically on prosthesis. Released stresses were evaluated comparatively. The lowest von Mises stress values were found in group C, in the 11.5-mm implant model. Tilting the distal implants 30° caused higher stress values. In 45°-tilting implant models, lower stress values were recorded according to the 30°-tilting models. The ideal implant number is seven for an edentulous maxilla. Tilting the implants causes higher stress values. A 45° inclination of implant causes lower stress values according to the 30° models due to a shorter cantilever. The ideal implant length is 11.5 mm.

Evaluation of four designs of short implants placed in atrophic areas with reduced bone height: a three-year, retrospective, clinical and radiographic study

The aim of the present study was to evaluate retrospectively the clinical and radiographic behaviour of four commercially-available short implants with different macrodesigns and microdesigns in areas in which the height of the bone was reduced. We took into account the success and survival, peri-implant crestal bone loss, and the level of probing at which the gum bled. Patients were included if they had been given one or more short implants (≤8.5mm long) in the posterior jaws at least three years earlier. Three hundred and ninety-one short implants were placed in 170 subjects, and were divided in four groups based on the brand of implant. The implants were evaluated one, two, and three years after they had been inserted. Short implants had a three-year survival and success rate of 90% in all groups, and bone loss was acceptable after three years with no significant differences between them. These results support the use of short implants as an effective and safe treatment. However, within the limitations of this study, the design of the implant does seem to influence the behaviour of peri-implant bone at the crestal level.

Transalveolar Osteotomy of the Mandibular Canal Wall for the Treatment of Severely Atrophied Posterior Mandible

PURPOSE

Treatment of severe bone atrophy of the posterior mandible requires an advanced surgical bone augmentation technique. This report describes a minimally invasive approach for a residual alveolar height less than 5 mm.

MATERIAL AND METHODS

A retrospective case series was conducted in a single private dental clinic. Outcome variables were dental implant survival rate, intraoperative complications, occurrence of neurosensory disturbances, and marginal bone loss. Descriptive analysis was performed for patients' demographic data, postoperative healing, and implant details. Kaplan-Meier method was used to assess the implant survival rate.

RESULTS

The mean age of the 19 patients was 60 ± 13 years. Twenty-eight implants (5.5 mm long) were placed in a residual alveolar bone height of 4.5 ± 0.6 mm. The implant survival rate was 96% at 5-year follow-up.

CONCLUSIONS

Extra-short implants and transalveolar preparation of the inferior alveolar cortical bone could be a safe and effective treatment of severe mandibular atrophy.

Dental Implant Length and Diameter: A Proposed Classification Scheme

PURPOSE

To propose a length-and-diameter-based classification scheme for dental implants to standardize terminology in the dental literature and communication between interested parties.

MATERIALS AND METHODS

This study was mainly based on searching two major resources: published scientific research papers and 14 of the most popular dental implant manufacturers. Indexed databases were searched from January 2004 up to and including February 2016 using the keywords "dental implant length" and "dental implant diameter." Retrieved titles and abstracts were screened, and related full-text articles were reviewed. Full-text articles that clearly stated the terms and measurements of implants used were included and considered for proposing this classification scheme.

RESULTS

The initial search for implant diameter and length yielded 1007 and 936 articles, respectively. A total of 85 studies (41 about diameter, 44 about length) were selected and reviewed. The remaining studies (966 about diameter, 892 about length) that did not abide by the eligibility criteria were excluded. The terms "long," "short," "standard," "wide," and "narrow" were the most commonly used terms in the literature. A classification scheme for implants by diameter and length was proposed.

CONCLUSIONS

Indexed publications contain a variety of terms used by authors to describe diameter and length of dental implants without conformity and standardization. The classification scheme proposed in this article could serve as a reference for interested parties.

Evaluation of extrashort 4-mm implants in mandibular edentulous patients with reduced bone height in comparison with standard implants: a 12-month results

OBJECTIVE

The aim of this research was to evaluate the primary stability, the marginal bone loss, the survival, and the success criteria, of 4-mm-length implants compared with implants of conventional length supporting fixed prostheses.

MATERIALS AND METHODS

Ten patients were selected for treatment of their atrophic edentulous jaws. Each patient received the following treatment: six dental implants were inserted, two anterior implants of conventional length (10-mm) in the interforaminal area and four posterior short implants of 4-mm length (Standard Plus, Roxolid, SLActive, Institut Straumann AG). The implants supported screw-retained fixed complete dentures. Examinations were conducted at day 0, three, six, and twelve months after surgery for the evaluation of the implant primary stability, secondary stability, crestal bone loss and survival by clinical evaluations, insertion torque values, resonance frequency analysis (RFA), and periapical radiography, respectively.

RESULTS

Sixty implants were inserted in ten patients. Mean insertion torque was slightly lower for 4-mm implants than 10-mm implants (38.1 Ncm vs. 42.2 Ncm) but without statistically significant difference. Implant stability was similar for extrashort and conventional implants. Marginal bone loss was similar for both groups for all the time periods. One short implant was lost before loading. The survival rates twelve months after implant placement were of 97.5% and 100% for short and conventional implants, respectively. Similarly, implant stability as measured by RFA was nonsignificantly lower for the 4-mm implants compared to the 10-mm implants. The marginal bone loss was lower for short implants three, six, and twelve months after the surgery without statistical significant difference.

CONCLUSIONS

Within the limitations of this study, we conclude that short dental implants (8 mm or less in length) supporting single crowns or fixed bridges are a feasible treatment option with radiographic and clinical success rates similar to longer implants for patients with compromised ridges. Long-term data with larger number of implants and subjects are needed to confirm these preliminary results.

Implant-Guided Vertical Bone Augmentation Around Extra-Short Implants for the Management of Severe Bone Atrophy

The purpose of this study is to describe the conservative treatment of severe vertical bone atrophy by combining the insertion of extra-short implants and implant-guided bone augmentation. For that, a low-speed drilling protocol was selected to facilitate the collection of bone particles and to maintain graft osteogenic properties. Extra-short implants were incompletely inserted because of the severe atrophy, and the denuded implant surface was covered by autologous bone particles held together by the adhesive properties of plasma rich in growth factors. The surgical site was then covered with resorbable fibrin membrane, and the flap was repositioned and sutured. Eight patients with a mean residual bone height of 4.19 ± 0.97 mm were treated according to the described treatment protocol. The distance between the implant shoulder and the bony crest was 1.77 ± 0.18, 2.16 ± 0.23, and 1.97 ± 0.26 mm at the mesial, central, and distal aspects, respectively. Vertical bone augmentation resulted in the coverage of 85% of exposed surface by stimulating 1.6 ± 0.5 mm of supra-alveolar bone growth. All 10 extra-short implants placed were successfully osseointegrated. After a mean of 5 ± 1.6 months, provisional screw-retained prostheses were placed. Within the limitations of this study, we conclude that the minimally invasive approach described may successfully rehabilitate extreme vertical bone atrophy in the posterior mandible.

Immediate loading short implants inserted on low bone quantity for the rehabilitation of the edentulous maxilla using an All-on-4 design

More studies evaluating the outcome of short-length dental implants in immediate loading are needed. To evaluate the use of short-length tapered implants in immediate loading for complete edentulous maxillae rehabilitations using an All-on-4 design. This retrospective clinical study included a cohort of 43 patients with 172 implants (74 short-length implants) inserted in low bone quantity. The patients were followed between 4 months and 6 years (average = 3 years). Outcome measures were implant survival, marginal bone remodelling, biological and mechanical complications. Two patients with four short-length implants were lost to follow-up during the first year. Three short and three long implants failed in four patients, rendering an overall cumulative survival rate implant and patient level, respectively, of 95.7% and 95.1% for short implants, 100% for regular implants and 96.6% and 95.2% for long implants. The average marginal bone remodelling at 1 and 3 years was 0.97 and 1.25 mm for the short implants, 0.82 and 0.87 mm for regular implants and 0.87 and 0.98 mm for long implants. Three patients presented 4 short-length implants with peri-implant pockets (3 implants in 2 patients were pseudo-pockets). Mechanical complications were registered in 13 patients (7 provisional prostheses fractures and 6 abutment screw loosening). All complications were treated successfully. Within the limitations of this clinical study, the short-term outcome of fixed prosthetic complete edentulous maxillae rehabilitations supported by short-length implants inserted in low bone quantity areas is viable. Long-term clinical studies are necessary for evaluating the outcome of these implants.

Early and immediate loading protocols for overdentures in completely edentulous maxillas: a comprehensive review of clinical trials

A comprehensive review was conducted to answer the question 'Does the immediate loading of dental implants with an overdenture in the maxilla provide predictable clinical and psychological outcomes?' Detailed search strategies were used to identify pertinent articles in English that were published between 1975 and August 2013 and indexed in PubMed, MEDLINE, Embase, The Cochrane Central Register of Controlled Trials, and a personal library; in addition, relevant journals were manually searched. Only randomized controlled clinical trials (RCTs), controlled clinical trials (CCTs), and prospective studies with a follow-up period of at least one year, all involving 10 or more adult participants, were considered. Six prospective studies reporting on outcomes of up to 2 years were included, five of which employed a bar-retained overdenture, and one of which used a ball attachment as a retention mechanism. Short term reports demonstrate that immediate/early loading of dental implants with a maxillary overdenture is a predictable treatment approach and results in favorable implant/prosthesis survival, soft tissue health, and patient satisfaction outcomes. However, for a definitive conclusion, well-designed long-term trials are required to establish a consensus on treatment planning, longevity, long-term complications and maintenance, cost-effectiveness, and patients-mediated outcomes.

Clinical study on survival rate of short implants placed in the posterior mandibular region: resonance frequency analysis

OBJECTIVE

Short implants are increasingly used, but there is doubt about their performance being similar to that of regular implants. The aim of this study was to compare the mechanical stability of short implants vs. regular implants placed in the edentulous posterior mandible.

MATERIAL AND METHODS

Twenty-three patients received a total of 48 short implants (5 × 5.5 mm and 5 × 7 mm) and 42 regular implants (4 × 10 mm and 4 × 11.5 mm) in the posterior mandible. Patients who received short implants had <10 mm of bone height measured from the bone crest to the outer wall of the mandibular canal. Resonance frequency analysis (RFA) was performed at time intervals T0 (immediately after implant placement), T1 (after 15 days), T2 (after 30 days), T3 (after 60 days), and T4 (after 90 days).

RESULTS

The survival rate after 90 days was 87.5% for the short implants and 100% for regular implants (P < 0.05). There was no significant difference between the implants in time intervals T1, T2, T3, and T4. In T0, the RFA values of 5 × 5.5 implants were higher than values of 5 × 7 and 4 × 11.5 implants (P < 0.05). A total of six short implants that were placed in four patients were lost (three of 5 × 5.5 mm and three of 5 × 7 mm). Three lost implants started with high ISQ values, which progressively decreased. The other three lost implants started with a slightly lower ISQ value, which rose and then began to fall.

CONCLUSIONS

Survival rate of short implants after 90 days was lower than that of regular implants. However, short implants may be considered a reasonable alternative for rehabilitation of severely resorbed mandibles with reduced height, to avoid performing bone reconstruction before implant placement. Patients need to be aware of the reduced survival rate compared with regular implants before implant placement to avoid disappointments.

Biomechanics and load resistance of short dental implants: a review of the literature

This paper was aimed to review the studies published about short dental implants. In the focus were the works that investigated the effect of biting forces of the rate of marginal bone resorption around short implants and their survival rates. Bone deformation defined by strain was obviously higher around short implants than the conventional ones. The clinical outcomes of 6 mm short implants after 2 years showed a survival rate of 94% to 95% and lower survival rate (<80%) for 7 mm short implants after 3 to 6 years for single crown restorations. The short implants used for supporting fixed partial prostheses had a survival rate of 98.9%. Short implants can be considered as a good alternative implant therapy to support single crown or partial fixed restorations.

A comparison between 4 and 6 implants in the maxillary posterior region to support an overdenture; 1-year results from a randomized controlled trial

OBJECTIVE

To compare the treatment outcome of 4 vs. 6 bar-connected implants in the posterior region of the maxilla to support an overdenture during a 1-year follow-up period.

MATERIALS AND METHODS

Sixty-six edentulous patients with an insufficient amount of bone volume in the maxilla to place implants were asked to participate in this study. Randomization assigned patients to either 4 or 6 implants. In all patients, a maxillary sinus floor elevation procedure with bone from the iliac crest was performed, and after a 3-month healing period, 4 or 6 dental implants were inserted in the maxillary posterior region in a one-stage procedure. After 3 months of osseointegration, a bar-supported overdenture was constructed. Implant survival, overdenture survival, clinical scores, peri-implant bone height changes and patients' satisfaction were assessed. Study analysis was performed according a non-inferiority design.

RESULTS

All patients completed the one-year follow-up. After a functional period of 1-year, implant survival was 100% in the 4 implants group and 99.5% in the 6 implants group. Overdenture survival was 100% in both groups. Mean clinical scores were very low and did not significantly differ between groups. Mean marginal bone resorption was 0.35 ± 0.31 mm and 0.46 ± 0.34 mm in the 4 and 6 implants group, respectively. Patients' satisfaction improved significantly in both groups, but did not differ between groups.

CONCLUSION

A bar-supported overdenture on 4 implants in the posterior maxillary region is not inferior to an overdenture supported by 6 bar-connected dental implants.

Maxillary overdentures supported by four or six implants in the anterior region; 1-year results from a randomized controlled trial

OBJECTIVE

Comparing treatment outcome of four and six bar-connected implants in the anterior maxillary region to support an overdenture during a 1-year follow-up period.

MATERIAL AND METHODS

Fifty edentulous patients with lack of retention and stability of the upper denture, but with sufficient bone volume to place implants in the anterior maxillary region, were selected. Randomization assigned patients to either four or six implants. Implant survival, overdenture survival, clinical scores, radiographic bone height changes, and patients' satisfaction were assessed.

RESULTS

Forty-nine patients (one drop out) completed the 1-year follow-up. After 1 year, implant survival was 100% in the four implants group and 99.3% in the six implants group (one implant lost). Overdenture survival was 100% in both groups. Mean clinical scores were low and did not differ between groups (independent Student's t-test). Mean marginal bone resorption was 0.24 ± 0.32 mm in the four implants group and 0.25 ± 0.29 mm in the six implants group. Patients' satisfaction had improved in both groups (paired Student's t-test).

CONCLUSION

Bar-supported overdentures on four implants in the anterior maxillary region are not inferior to overdentures supported by six bar-connected implants. Implant survival was high, peri-implant conditions were healthy and patients' satisfaction had increased significantly in both groups.

Are short dental implants (<10 mm) effective? a meta-analysis on prospective clinical trials

BACKGROUND

This study aims to compare the survival rate of short (<10 mm) and standard (≥10 mm) rough-surface dental implants under functional loading.

METHODS

An electronic literature search using PubMed and Medline databases was conducted. Prospective clinical human trials, published in English from January 1997 to July 2011, that examined dental implants of <10 mm with a 12-month follow-up were included in this meta-analysis. The following data were retrieved from the included articles: the number of implants, implant dimensions, implant locations, types of prostheses, follow-up periods, and implant survival rates. Kaplan-Meier survival estimates and the hazard rates were analyzed and compared between short and standard implants.

RESULTS

Thirteen studies were selected, examining 1,955 dental implants, of which 914 were short implants. Short dental implants had an estimated survival rate of 88.1% at 168 months, when standard dental implants had a similar estimated survival rate of 86.7% (P = 0.254). The peak failure rate of short dental implants was found to occur between 4 and 6 years of function. This occurred at an earlier time point compared with standard dental implants, where the peak failure rate occurred between 6 and 8 years of function.

CONCLUSIONS

This study shows that in the long term, implants of <10 mm are as predictable as longer implants. However, they fail at an earlier stage compared with standard implants.