Long-term clinical performance of short 6-mm implants supporting single crowns in the posterior region: A 10-year cohort study

INTRODUCTION

Long-term clinical success of non-splinted, posterior, and short implants still is unclear. This prospective cohort study reports the 10-year follow-up of 6-mm implants supporting single crowns in the posterior region, and patient-reported outcomes.

METHODS

Baseline sample comprised 20 patients treated with 46 screw-retained crowns supported by 6-mm implants with moderately rough implant surface. Participants were recalled for a 10-year clinical follow-up to assess survival rates, biologic and mechanic conditions, quality of life (OHIP-14), and treatment satisfaction. Data were collected with clinical-radiographic exams and analyzed using descriptive and inferential statistics.

RESULTS

Fourteen patients with 35 implant-crown units were examined after 127.6 ± 11.8 months. For the entire cohort period, 7/46 implants were lost (survival estimate: 77.7% at 133 months), and mechanic complications occurred in 14/46 units (survival estimate: 66.4% at 116 months). In the Cox models, "maximum occlusal force" had a significant effect for implant loss (p = 0.038) and for prosthetic screw loosening (p = 0.038); "arch" and "bruxism" were not significant. Peri-implant bone loss was 0.4 ± 0.6 mm at 10 years. For peri-implant bone level, "crown-to-implant ratio" (p < 0.001) and "time" (p = 0.001) were significant. Bone levels differed from baseline to 12, 48, and 120 months. Satisfaction VAS was 94.0 ± 7.9 mm and OHIP-14 was 2.3 ± 2.2.

CONCLUSION

Single screw-retained crowns supported by 6-mm implants have an acceptable long-term clinical performance, with stable peri-implant bone levels after 10 years of function.

A naïve comparison to assess the success of ultra-short implants

Introduction

Conventional implants are associated with ridge augmentation/sinus lift procedures in vertically insufficient ridges, which increase morbidity and healing time. Short implants provided some hope in this context. The present study considered the use of ultra-short implants in vertically insufficient posterior mandibular ridges and evaluated their success. Hence, study was done to evaluate the success of ultra-short implants in partially edentulous posterior mandible clinically and radiographically.

Materials and Methods

The study is a "Naïve direct comparison" of ultra-short implants to conventional implants for assessing their success in vertically insufficient posterior mandibular ridges. A total of 10 ultra-short implants were placed in a partially edentulous posterior mandibular ridge with at least 8-mm horizontal (at crest) and vertical dimensions. A delayed loading was done at three-month follow-up. Data acquisition was done at baseline (immediately after loading), 6-, 9-, 12-month intervals. Parameters assessed were marginal bone loss (MBL), probing pocket depth reduction (PPDR), modified plaque index (mPI), modified gingival index (mGI).

Results

All the placed 10 implants survived, and no failure was observed. "Independent sample t-test" and "paired sample t-test" was done for intergroup and intragroup analysis, respectively. Intergroup comparison between the ultra-short and conventional implants presented a statistically insignificant difference between all the parameters at all the follow-up visits (baseline, 6-, 9-, 12 months).

Conclusions

Within the limitations, it was thus concluded that ultra-short implants may be considered as a viable treatment option for vertically insufficient mandibular ridge. Further, long-term randomized controlled trials are required to establish the evidence.

Clinical, Radiographic Peri-Implant Parameters and Patient Satisfaction with Splinted and Non-splinted Short Dental Implants in the Maxillary Premolar-Molar Region: A Long-Term Retrospective Clinical Study

PURPOSE

The goal of this study was to assess the peri-implant condition, peri-implant bone loss (PBL), and complication rates of short dental implant-supported splinted crowns (SDI-SCs) and non-splinted crowns (SDI-NSCs) in the maxillary premolar-molar region.

MATERIALS AND METHODS

Patients who had short implants placed near their maxillary sinuses were evaluated. Both patient satisfaction and presence of any technical complication, e.g. porcelain wear and chipping, loss of retention and loosening of the abutment, fixture or screw, were noted. The peri-implant plaque index (PIPI), probing depth (PIPD), bleeding on probing (PIBP), and peri-implant bone loss (PBL) were evaluated. To assess the impact of prosthesis type and SDI placement on technical problems, a log-rank test was computed. p < 0.05 was considered statistically significant.

RESULTS

A total of 72 patients agreed to be followed-up, showing a mean follow-up time of 3.1 years. Ninty-five implants in total (55 SDI-SCs, and 40 SDI-NSCs) with moderately rough surfaces were evaluated. The average PBL score for implant and patients was 1.27 (0.02-3.97) and 1.25 (0.03-4.41), respectively. More technical complications were observed with single crowns than with splinted crowns. There were no statistically significant differences in the peri-implant parameters between SDI-SCs and SDI-NSCs (p > 0.05). PBL at molar sites was substantially higher than at premolar sites (p = 0.048). Sixty patients (83.3%) were satisfied with the appearance of the crowns, while 57 patients (79.1%) were satisfied with the crowns' performance.

CONCLUSION

The peri-implant conditions, bone levels, technical complication rates and patient satisfaction were comparable between the SDI-SCs and SDI-NSCs. However, implants placed in the molar sites had statistically significantly greater bone loss in comparison to those at the premolar sites.

Insertion Torque, Removal Torque, and Resonance Frequency Analysis Values of Ultrashort, Short, and Standard Dental Implants: An In Vitro Study on Polyurethane Foam Sheets

Short implants were introduced to reduce morbidity, treatment duration, and complex bone regeneration interventions in atrophic jaws and to improve patient-reported outcomes. This study aimed to determine the insertion torque (IT), removal torque (RT), and resonance frequency analysis (RFA) values of ultrashort (3 mm length), short (7 mm length), and standard implants (10 mm length) inserted in 1-, 2-, 3-, and 4-mm thickness polyurethane sheets with densities of 10, 20, and 30 pounds per cubic foot (PCF). Standard-length implants were the gold standard (control). Overall, short-length implant IT values were higher or similar to the control in most experimental conditions. Those inserted into a 3 mm/30 PCF lamina showed the highest IT values, whereas 5 mm diameter ultrashort-length implants inserted into 2 and 3 mm/20 PCF laminas were higher than other implants. RT values followed the same trend and RFA values were more appreciable in short- and standard-length implants in all the scenarios. However, ultrashort-length implants reached a primary stability comparable to that of standard implants in lower thicknesses. In conclusion, although further studies are needed to corroborate this in vitro model with preclinical and clinical studies, our data shed light on short- and ultrashort-length implants geometries to a potential application in critical atrophy of the posterior jaws.

Radiographic density changes may be associated with overloading and implant loss on short implants: A 5-year analysis of a randomized controlled clinical trial

OBJECTIVES

To analyze changes in radiographic bone density around short implants with and without cantilevers at 5 years post-loading.

MATERIALS AND METHODS

Thirty-six patients with two adjacent posterior missing teeth participated in this randomized controlled clinical trial. All patients were randomly allocated to receive either two short implants (6 mm) with single-unit restorations (group TWO) or one single short implant (6 mm) with a cantilever restoration (group ONE-C). Patients were followed up at 6 months, 1, 3, and 5 years. Radiographic analysis was performed, through an arbitrary gray scale value (GSV) of the peri-implant bone, assessing the changes in radiographic density between groups and between time points. Differences in GSV between groups and over time were calculated using a generalized estimating equation to allow for adjustments for the correlation within individuals and between time points.

RESULTS

At 5 years, 26 patients remained in the study (15 in group ONE-C; 11 in group TWO). Implant survival rates were 80.4% in group TWO and 84.2% in group ONE-C (p = 0.894). The radiographic analysis revealed that GSVs increased in both groups over time (p < 0.001). The overall radiographic density was higher in group ONE-C than in group TWO in the maxilla (p = 0.030). Conversely, in the mandible, these significant differences between the groups were not found (p > 0.05). Compared to the implants that survived, the implants that failed demonstrated a distinct radiographic density pattern (p < 0.05).

CONCLUSION

Within the limitations of the present study, the radiographic bone density in the maxilla appears to increase distinctly around short implants when cantilevers are used. In contrast, the radiographic density in the mandible appears to be unaffected by the use of a cantilever, suggesting a lower threshold of adaptation to occlusal forces and thus a higher susceptibility to overload and implant loss at earlier time points.

One-stage versus two-stage technique using two splinted extra-short implants: A multicentric split-mouth study with a one-year follow-up

OBJECTIVE

To compare the clinical outcomes of extra-short implants (≤6.5 mm) inserted with one-stage versus two-stage technique in adjacent sites of the upper or lower jaw.

MATERIALS AND METHODS

In this split-mouth multicenter study, implants were randomly divided into two groups according to the healing phase: two-stage and one-stage technique. Primary outcome measures were implant survival, implant success, and prosthodontic complications. Secondary outcome measurements were: implant stability quotient (ISQ) collected at surgery time (T0), and after 3 (T3) and 12 (T12) months, marginal bone level (MBL) evaluated at T0, T3, T6, and T12, marginal bone loss evaluated at T6 and T12, plaque index (PI), probing depth (PD), bleeding on probing (BoP) evaluated at T3, T6, and T12. Significances of differences between groups were tested by linear mixed model with random intercept.

RESULTS

Nineteen patients (8 males and 11 females) were included. A total of 38 implants were inserted. At T12 implant cumulative survival and implant success rate were 100% in both groups. No statistically significant differences were recorded for any of the analyzed parameters between the two groups at any time point. ISQ values were similar at T0 (two-stage: mean 67.53 ± SD 19.47; one-stage: mean 66.53 ± 19.07 p = 0.8738) and increased in both groups at the 12-month follow-up appointment (two-stage: 81.1 ± 7.04; one-stage: 81.39 ± 0.9266). MBL values were similar in the two groups at any time point. At T12 marginal bone loss was 0.46 ± 0.41 (two-stage) and 0.45 ± 0.38 (one-stage) mm (p = 0.9417), while mean PD was 2.7 ± 0.85 (two-stage) and 2.69 ± 0.89 (one-stage) mm.

CONCLUSIONS

Within the limits of the present short-term report, extra-short implants demonstrated optimal clinical outcomes using the one-stage technique, without statistically significant differences compared with the traditional two-stage approach.

Evaluation of the survival rate of short implants placed in the posterior atrophic mandible: 5-year clinical study

OBJECTIVE

The aim of the study was to assess the long-term prognosis of short implants (5 to 6 mm) placed in the posterior region of the atrophic mandible.

METHOD AND MATERIALS

The study included 81 patients with severe vertical atrophy of the bone in the posterior region. The patients had 248 short implants (5 to 6 mm) implants placed in the mandibular posterior region and 256 implants with length greater than 10 mm in the mandibular anterior region. Analysis of implant and prosthesis failures, cumulative survival rate, and marginal bone loss was determined at 1 year and 5 years of follow-up (58 ± 7 months).

RESULTS

Mean marginal bone loss after 1 year of prosthetic loading was 0.74 mm for short implants and 0.72 mm for implants with length greater than 10 mm; after 5 years of prosthetic loading this was 1.27 mm for short implants and 1.31 mm for implants with length greater than 10 mm. Of 248 short implants (5 to 6 mm), six failed: four due to peri-implantitis and two due to lack of osseointegration (early rejection). Of 256 implants with length greater than 10 mm, five failed: three due to peri-implantitis and two due to lack of osseointegration (early rejection). On average, over the observation period (58 ± 7 months), the 5-year cumulative implant survival rate was 97.8% in short implants, and 98.1% in longer implants; the prosthesis cumulative survival rate was 98.2%.

CONCLUSIONS

Based on the results, it was concluded that the prognosis of the use of short implants for prosthetics in the posterior resorbed mandible can be considered favorable and reasonable.

Converting Bilateral Free-End Removable Partial Dentures to Implant-Assisted Removable Partial Dentures Using 6 mm Short Implants: Patient-Reported Outcomes of a Prospective Clinical Study

The study assessed oral health-related quality of life (OHRQoL) of patients who received two 6 mm short implants in mandibular molar sites, converting existing bilateral free-end removable partial dentures (RPDs) to implant-assisted RPDs (IARPDs). After a postsurgical healing period of 4 months, the participants received a non-retentive dome abutment for 8 weeks, and then a retentive ball abutment for another 8 weeks. Afterwards, the participants made their final choice on which abutment to keep. The final follow-up was 1 year after implant placement. OHRQoL was evaluated with the 49-items version of the Oral Health Impact Profile (OHIP-49) at the abutment exchanges and the final follow-up. Furthermore, numerical rating scales were used to analyze patient satisfaction after 1 year. Questionnaire data of 13 participants were evaluated. Overall, OHRQoL increased with both the dome (p = 0.02) and the ball abutments (p < 0.001), without a significant difference between the abutments (p = 0.953). The questionnaires revealed an improvement in terms of oral situation, quality of life, and masticatory capacity (all p < 0.01). Patients showed a significant preference for the ball abutments (p < 0.001). Converting RPDs to IARPDs resulted in significant improvement of OHRQoL. Patients seem to prefer retentive over non-retentive abutments, although no differences in terms of OHRQoL were observed.

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.

Long-term clinical outcomes of short implant (6mm) in relation to Implant Disease Risk Assessment (IDRA)

AIM

To evaluate the long-term survivals of short implants and to investigate the association of the Implant Disease Risk Assessment (IDRA) with the occurrence of biological complications.

MATERIAL AND METHODS

This study was designed as a cohort study with a median follow-up of 10.0 years. Patients who had received 6-mm implants were reviewed and assigned into low-, moderate- and high-risk groups (Group L, M and H) based on the IDRA tool. The implant survival, biological complications, soft tissue condition, hardware complications and marginal bone loss (MBL) were evaluated. Kaplan-Meier curves and Cox regression were performed for survival analysis.

RESULTS

A hundred and ten patients were included. The overall cumulative survival rate was 90.9% (L:100.0%, M: 93.3% and H: 80.6%). A higher risk profile was significantly associated with a decreased implant survival (hazard ratio: 4.11, 95% CI: 1.17-14.36, p<0.05). Higher risk profile (hazard ratio: 2.63, 95% CI: 1.32-5.25, p<0.05) was a potential risk factor for biological complications. At follow-up, significant differences in bleeding index, modified plaque index and peri-implant probing depth were found among groups (p<0.01). No significant difference was found in MBL.

CONCLUSION

Acceptable long-term clinical outcomes could be achieved after 10 years for short implants. Despite a statistically nonsignificant difference in MBL, patients with a high-risk profile of IDRA seem to be at greater risk of implant loss and biological complications.

Short versus Longer Implants in Sites without the Need for Bone Augmentation: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

OBJECTIVES

The present systematic review and meta-analysis aims to analyse the clinical performance of short compared to longer implants inserted in sites without the need for bone augmentation.

METHODS

The protocol of the present PRISMA-driven meta-analysis was registered on PROSPERO (CRD42021264781). Electronic and manual searches were performed up to January 2022. All Randomized Controlled Trials (RCTs) comparing short (≤6 mm) to longer (≥8.5 mm) implants placed in non-atrophic and non-augmented sites were included. The quality of the included studies was assessed using the Cochrane risk of bias tool for randomized clinical trials (RoB 2) and the quality of evidence was determined with the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. A meta-analysis was performed on implant survival rate, marginal bone level change (MBLc), and technical and biological complications at the available follow-up time points. The power of the meta-analytic findings was determined by trial sequential analysis (TSA).

RESULTS

From 1485 initial records, 13 articles were finally included. No significant difference was found in the survival rate between short and long implant at any follow-up (moderate quality of evidence). Significantly more bone loss for long implants at 1 and 5 years from implant placement and more technical complications with short implants at 10 years were found. No other significant inter-group differences in terms of MBLc and biological complications were detected.

CONCLUSIONS

Moderate evidence exists suggesting that short implants perform as well as longer ones in the rehabilitation of edentulous sites without the need for bone augmentation. Further long-term, well-designed RCTs, however, are still needed to provide specific evidence-based clinical recommendations for an extended use of short implants in non-atrophic sites.

A 5-year randomized controlled clinical trial comparing 4-mm ultrashort to longer implants placed in regenerated bone in the posterior atrophic jaw

BACKGROUND

Short implants (up to 5-mm long) have shown good results when compared to longer implants placed in augmented bone.

PURPOSE

To evaluate if 4-mm ultrashort implants could also be an alternative to bone augmentation in the severely atrophic posterior jaws. The primary aim of the study was to compare implant survival rates between study groups.

MATERIALS AND METHODS

Eighty partially edentulous patients with posterior atrophic jaws (5-6 mm of bone above the mandibular canal and 4-5 mm below the maxillary sinus) were included: 40 patients in the maxilla and 40 in mandible. The patients were randomized to receive one to three 4-mm ultrashort implants or one to three implants at least 10-mm long in augmented bone. Results are reported 5 years after loading with the following outcome measures: implant and prosthetic failures, complications and peri-implant marginal bone level changes.

RESULTS

Thirty-two complications were reported for the control group in 18 patients versus 13 complications in 10 patients in the test group, the difference being not statistically significant (p = 0.103). In the augmented group, 12 implants failed in 6 patients versus 7 short implants in 6 cases, and 9 prostheses failed in the control group while 4 in the test one, without statistically significant differences (p = 1.000 and 0.363, respectively). At 5 years after loading, short implants lost on average 0.58 ± 0.40 mm of peri-implant marginal bone and long implants 0.99 ± 0.58 mm, the difference was statistically significant (p = 0.006).

CONCLUSION

Four-millimeter ultrashort implants showed similar if not better results when compared to longer implants placed in augmented jaws 5 years after loading. For this reason, their use could be in specific cases preferable to bone augmentation since the treatment is less invasive, faster, cheaper and associated with less morbidity. However, longer follow-ups and larger trials are needed.

Two short implants versus one short implant with a cantilever: 5-Year results of a randomized clinical trial

Aim

To test whether or not the use of a short implant with a cantilever results in similar clinical and radiographic outcomes compared to two adjacent short implants with single tooth reconstructions.

Materials and methods

Thirty‐six patients with two adjacent missing teeth in the posterior region were randomly assigned to receive either a single 6‐mm implant with a cantilever (ONE‐C) or two 6‐mm implants (TWO). Fixed reconstructions were inserted 3–6 months after implant placement and patients were re‐examined up to 5 years (FU‐5).

Results

A total of 26 patients were available for re‐examination at FU‐5. The survival rate amounted to 84.2% in ONE‐C and to 80.4% in TWO (inter‐group: p = .894). Technical complication rates amounted to 64.2% (ONE‐C) and to 54.4% (TWO) (inter‐group: p = 1.000). From baseline to FU‐5, the median changes of the marginal bone levels were 0.13 mm in ONE‐C and 0.05 mm in TWO (inter‐group: p = .775). Probing depth, bleeding on probing, and plaque control record values showed no significant differences between the two treatment modalities (p > .05).

Conclusions

Short implants with a cantilever render similar clinical and radiographic outcomes compared to two adjacent short implants at 5 years, however, they tend to fail at earlier time points suggesting an overload of the implants. Considering the modest survival rates, the clinical indication of either treatment option needs to be carefully evaluated. ClinicalTrials.gov (NCT01649531).

Clinical outcomes of short implants (≤ 6 mm) placed between two adjacent teeth/implants or in the most distal position: A systematic review and meta-analysis

PURPOSE

To investigate whether implant position (adjacent to teeth/implants vs most distal position in the arch) influences the clinical outcomes of short (≤ 6 mm) non-splinted implants.

MATERIALS AND METHODS

A systematic electronic search of human randomised clinical trials and prospective cohort studies was performed using the PubMed, Embase and Cochrane Central Register of Controlled Trials (Central) databases. A manual search of implant-related journals was also performed. A meta-analysis was conducted to compare survival rate, marginal bone loss and prosthetic complications based on implant position.

RESULTS

Overall, 11 studies were included to give a total of 388 non-splinted short implants (269 adjacent, 119 distal) followed up over a period ranging from 12 to 120 months. No significant differences in survival were found when comparing adjacent and distal positioning for both arches, and no significant differences were found for marginal bone loss or prosthetic complications between groups regardless of position.

CONCLUSIONS

Short implants supporting single crowns presented similar outcomes when placed in the most distal position in the arch or between adjacent teeth or other implants.

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.

Survival Rates of Splinted and Nonsplinted Prostheses Supported by Short Dental Implants (≤8.5 mm): A Systematic Review and Meta-Analysis

PURPOSE

To evaluate and compare the implant survival rates, marginal bone loss, and mechanical complications of prostheses supported by splinted and nonsplinted short implants (≤8.5 mm).

MATERIAL AND METHODS

Electronic database (MEDLINE, CENTRAL, Web of Science, and EMBASE) and manual searches up to May 2021 were conducted to identify studies comparing splinted and nonsplinted short implants (≤8.5 mm). The primary outcome was implant survival rate. Secondary outcomes were marginal bone loss and mechanical complications. The quality of included studies and risk-of-bias were assessed according to the Newcastle-Ottawa Scale. A random-effects model was used to analyze the data.

RESULTS

Twelve studies fulfilled the inclusion criteria and featured 1506 short implants (596 nonsplinted and 910 splinted) with a follow-up time ranging from 1 to 16 years. Quantitative analysis found no statistically significant differences between splinted and nonsplinted short implants (≤8.5 mm) for survival rate (RR = 0.98; 95% CI 0.96, 1.01; p = 0.26)) and marginal bone loss (SMD = -0.08; 95% CI - 0.23, 0.07; p = 0.28). Veneer chipping, abutment screw breakage, screw loosening, and loss of retention were reported in the selected studies as common complications. However, no statistically significant difference was found between splinted and nonsplinted short implants (RR = 0.56; 95% CI 0.20, 1.54; p = 0.26).

CONCLUSIONS

Within the limitations of the present meta-analysis, it might be concluded that splinted short implants (≤8.5 mm) do not present superior performance in survival rate, marginal bone maintenance and prevention of mechanical complications compared with single-unit prostheses.

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.

Evaluating the effect of subcrestal placement on platform switched short dental implants and von mises stress in D3 bone-A 3D FEM study

Aim

To investigate the effect of platform switched short dental implants and subcrestal placement on von Mises stress in the maxillary anterior region (D3 bone) by using three-dimensional finite element model analyses (3D FEM).

Materials and Methods

Biomechanical behaviour of von Mises stress in maxillary anterior region (D3) bone were stimulated with the help of 3D FEM with the help of ANSYS WORKBENCH version 17.5. The bone model had a cortical core of (1 mm) surrounding the inner cancellous core, which represents D3 bone. Two models were designed model 1 (6 x 4.6 mm), (7.5 x 4.6 mm) and model 2 (6 x 5.8 mm), (7.5 x 5.8 mm). Loads of 100, 200 N were applied at an angle of 0°, 15°, 30° along the long axis of the tooth model.

Results

In all model's cortical bone exhibited greater stress than cancellous bone. Greater stress was reported in axial direction at 30° then 15° and least at 0° irrespective of load applied. An increase in implant length (7.5 mm) did not exhibit any stress reduction in both the model but implant diameter (5.8 mm) led to reduction in von Mises stress in both the groups. Greater the force applied greater was stress in both bones irrespective of direction of force applied (200N). Lastly subcrestal (0.5 mm) placement has slight reduction in stress compared to equicrestal placement in both the groups.

Conclusion

Numerical results from the current study suggest that, for short implants, implant diameter is considered more effective design parameter than implant length. Current findings state that platform switch short subcrestal implants results in conservation of marginal bone loss along with better stress distribution around peri-implant regions in D3 bone. However, all models analyzed in this study showed development of von Mesies stresses within physiological limits for human cortical bone.

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, radiographic and economic evaluation of short-6-mm implants and longer implants combined with osteotome sinus floor elevation in moderately atrophic maxillae: A 3-year randomized clinical trial

AIM

To compare the 3-year clinical, radiographic and economic outcomes of short-6-mm implants and longer implants combined with osteotome sinus floor elevation (OSFE) in the posterior maxilla.

MATERIAL AND METHODS

This study enrolled 225 patients (225 implants with diameter of 4.1 mm and 4.8 mm) with a posterior maxillary residual bone height (RBH) of 6-8 mm. Patients were randomly divided into three groups: Group 1 (6 mm implants alone), Group 2 (8 mm implants + OSFE) and Group 3 (10 mm implants + OSFE). The following outcomes were recorded at 1 and 3-year examinations: implant survival, probing pocket depth (PPD), bleeding on probing (BOP), modified plaque index (mPI), marginal bone loss (MBL), biological and technical complications, complication-free survival and treatment costs.

RESULTS

At the 3-year follow-up, 199 patients (Group 1: 67; Group 2: 62; Group 3: 70) were re-examined. Implant survival rates were 91.80%, 97.08% and 100.00% in groups 1, 2 and 3. Implant survival rate in Group 1 was significantly lower than that in Group 3 (p = 0.029). A multivariate Cox model showed that the short-6-mm implants with wide diameter had a protective effect on implant survival (hazard ratio: 0.59, p = 0.001). No significant differences in BOP%, PPD, mPI, MBL and complication-free survival rate were found among the three groups. The average costs of retreatment were 8.31%, 1.96% and 0.56% of the total costs in groups 1, 2 and 3. The cost to avoid a 1% increase in implant loss associated with 6-mm implants over a 3-year period was 369 CNY (56 USD) using a 10-mm implant with OSFE and 484 CNY (74 USD) using an 8-mm implant with OSFE.

CONCLUSION

In the moderately atrophic posterior maxillae, the three treatments showed acceptable clinical, radiographic and economic outcomes with up to 3-year follow-up. 10-mm implants combined with OSFE showed more favourable implant survival and fewer maintenance costs in comparison with short-6-mm implants, which were less expensive.

Short (6 mm) and Regular Dental Implants in the Posterior Maxilla-7-Years Follow-up Study

Short 6 mm dental implants are considered as an alternative to the maxillary sinus elevation and bone augmentation procedure where there is a reduced alveolar ridge height. The aim of this study was to compare the implant survival rate between short dental implants (6 mm) and regular length implants (11-13 mm) when placed in combination with bone grafting and loaded with a single non splinted crown, seven years after placing the implant. It was conducted as a controlled clinical study of 30 patients with partial edentulism in the posterior maxilla. The protocol included radiological and clinical evaluation of the C/I ratio (length of the superstructure divided by the length of the implant crestal part), marginal bone level (MBL), ultrasonography measurement of soft tissue surrounding implant (STT), patient-reported outcomes, and biological and technical complications. A total number of 28 implants (93%) remained integrated during follow-up period. MBL of 0.50 and 0.52 mm was observed for short implants and regular implants, respectively. MBL was checked for correlation with STT, and a negative correlation was found between MBL: STT. Our study has demonstrated a significantly lower implant survival rate for short implants compared to regular implants (87% compared to 100%). Despite the loss of several implants, good clinical results were achieved in the remaining implants in both groups. It is, therefore, worth considering short implants as an alternative to regular implants with a sinus lift surgery.

Biomechanical Evaluation of Stress Distribution in Subcrestal Placed Platform-switched Short Dental Implants in D4 Bone: In Vitro Finiteelement Model Study

The present study was carried out to assess stress distribution in the maxillary posterior bone region (D4 bone) with the help of a short platform switched subcrestal dental implants using the FEM model. Missing teeth surfaces related to the maxillary posterior region were stimulated. The bone model had a cancellous core of (0.5 mm) which represents D4 bone. A 7.5x4.6 mm screw type implant system with 3.5 platform switch abutment was selected. ANSYS WORKBENCH was used to model all the finite element structures. Force of 100 N was tested and adapted at an angle of 0º, 15º, 30º on the tooth model. Overall results from the current study showed that a high amount of stress was seen in cortical than in relation to cancellous bone. Stress values reduced from equicrestal to subcrestal (2 mm) placement of dental implants irrespective of angulation of load from 0o to 30o in both types of bone. However higher stress values were seen when force was applied in an oblique direction (30o) in comparison to a vertical load (0o). Least amount of stress was noticed when platform switched implants were placed 0.5 mm subcrestatlly irrespective of angulations of a load. Platform switched short subcrestal implants reduced the stress in the D4 cortical bone than in contrary equicrestal implant placement. This results in the preservation of marginal bone leading to implant success.

Biomechanical comparison of implantation approaches for the treatment of mandibular total edentulism

Applying four anterior implants placed vertically or tilted in the mandible is considered to provide clinically reasonable results in the treatment of mandibular posterior edentulism. It is also reported that a combination of four anterior and two short posterior implants can be an alternative approach for the rehabilitation of severe atrophy cases. In this study, we aimed to evaluate the biomechanical responses of three different implant placement configurations, which represent the clinical options for the treatment of mandibular edentulism. Three-dimensional models of the mandible, prosthetic bar, dental implant, abutment, and screw were created. Finite element models of the three implant configurations (Protocol 1: Four anterior implants, Protocol 2: Four anterior and two short posterior implants, Protocol 3: Two anterior and two tilted posterior implants: All-on-4™ concept) were generated for 10 patients and analyzed under different loading conditions including chewing, biting, and impact forces. Protocol 2 led to the lowest stress concentrations over the mandible among the three protocols (p < 0.016). Protocol 2 resulted in significantly lower stresses than Protocol 3 and Protocol 1 over prosthetic bars under chewing forces (p < 0.016). None of the implant placement protocols consistently exhibited the lowest stress distribution over abutments. The lowest stresses over dental implants under the chewing, biting, and impact forces were obtained in Protocol 1, Protocol 2, and Protocol 3, respectively (p < 0.016). Protocol 3 was the best option to obtain the lowest stress values over the screws under all types of loading conditions (p < 0.016). In conclusion, Protocol 2 was biomechanically more ideal than Protocol 1 and Protocol 3 to manage the posterior edentulism.

Rehabilitation of a severe mandibular atrophy with four millimeter extra-short implant and guided bone regeneration (GBR): case report with 7-years follow-up

The aim of this study was to report the use of extra-short and short implants in combination with Guided Bone Regeneration (GBR) to rehabilitate a case of severe mandibular reabsorption. A 55-yearold female patient asked for a fixed implant supported rehabilitation in 4.5 - 4.6 zone which showed severe atrophy. It was decided to use an extra-short 4 mm length and 4.1 mm Ø, Roxolid and SLActive implant (Straumann Standard Plus Regular Neck, Institut Straumann AG) in 4.5 position and a short 6 mm length and 4.8 mm Ø, Roxolid and SLActive implant (Straumann Standard Plus Wide Neck, Institut Straumann AG) in 4.6 position. The implants supported cemented fixed prosthesis. Examinations were performed at the day of the surgery and up to 7-years in function to evaluate implant stability and periapical radiography. One extra-short implant and one short implant were placed. After 7 years in function no biological or prosthetic complication were recorded. Within the limitation of this case report, the use of short and extra-short implants to support fixed prosthesis seem to be a feasible treatment alternative in severe mandibular atrophy.

Retrospective clinical analysis of risk factors associated with failed short implants

BACKGROUND

With advanced technology, short implants are more commonly used and have proven to have a relatively reliable curable efficacy. A consensus has not been reached regarding potential risk factors related to the loss of short implants.

PURPOSE

This large-sample retrospective study concentrated not only on patient characteristics and medical procedures but also on the features of implants in order to uncover the risk factors associated with short implants.

METHODS

Between 2014 and 2017, a total of 7001 implants were inserted at Nanjing Stomatological Hospital, Medical School of Nanjing University. Among the all, 1236 short implants were included after being evaluated according to the inclusion and exclusion criteria. In organizing the detailed information, seven variables including bone grafting procedure, age, gender, diameter of the implant, implant position, surface treatment, and definitive restorations were taken into consideration. The χ² test, Kaplan-Meier test, logistic regression, and multifactorial Cox regression analysis were employed to explore the risk factors.

RESULTS

The cumulative survival rate of short implants was 96.36%, slightly lower than that of the standard implants (98.16%, P < .001). Most of the short implants (84.44%) were lost at the early stage, mainly because of infection. Based on the results, male gender, implants treated by titanium anodizing and single-crown restoration increased the loss rate of short implants. Comparison of the short implants inserted into the maxillary and mandibular posterior area alone showed that the maxillary molar area was a risk factor for prognosis.

CONCLUSIONS

Male gender, TA surface treatment, and the presence of a single crown were associated with an increasing rate of short implants loss. Examination of the implant location focused on the posterior area revealed the maxillary posterior area to be a risk factor.

Primary Stability of Short Implants Inserted Using Piezoelectric or Drilling Systems: An In Vitro Comparison

The primary objective of the present in vitro study was to evaluate the influence of implant site preparation technique (drills vs ultrasonic instrumentation) on the primary stability of short dental implants with two different designs inserted in simulated low-quality cancellous bone. Eighty implant sites were prepared in custom-made solid rigid polyurethane blocks with two different low cancellous bone densities (5 or 15 pounds per cubic foot [PCF]), equally distributed between piezoelectric (Surgysonic Moto, Esacrom, Italy) and conventional drilling techniques. Two short implant systems (Prama and Syra, Sweden & Martina) were tested by inserting 40 fixtures of each system (both 6.0 mm length and 5.0 mm diameter), divided in the four subgroups (drills/5 PCF density; drills/15 PCF density; piezo/5 PCF density; piezo/15 PCF density). Insertion torque (Ncm), implant stability quotient values, removal torque (Ncm), and surgical time were recorded. Data were analyzed by 3-way ANOVA and Scheffé's test (α = 0.05). With slight variations among the considered dependent variables, overall high primary implant stability was observed across all subgroups. Piezoelectric instrumentation allowed for comparable or slightly superior primary stability in comparison with the drilling procedures in both implant systems. The Prama implants group showed the highest mean reverse torque and Syra implants the highest implant stability quotient values. Piezoelectric implant site preparation took prolonged operative time compared to conventional preparation with drills; among the drilling procedures, Syra system required fewer surgical steps and shorter operative time.

Short implants and platelet-rich fibrin for transcrestal sinus floor elevation: a prospective multicenter clinical study

INTRODUCTION

Inadequacy of residual bone height due to sinus pneumatization and alveolar bone remodeling could jeopardize the option for implant supported rehabilitation in posterior atrophied maxillae.

AIM

The aim of this prospective, multi-centric clinical study is to investigate and assess the survival rate of short implants in single posterior maxillae atrophied sites with adjacent natural teeth, when augmented with leukocyte and platelet-rich fibrin (L-PRF) alone using a minimally invasive trans-crestal approach.

MATERIALS AND METHODS

Seventy-four short implants were installed in 53 patients with residual bone height (RBH) <4mm using piezoelectric ultrasonic guided sinus elevation by transcrestal approach. Six perforations of the sinus membrane occurred (11.3% perforation rate), out of which five were managed by using just L-PRF as grafting material. Postoperatively, the implants were clinically evaluated for survival rate. The cumulative implant survival rate was 93.3% at the end of first year of follow-up. Considering 2 dropouts by the end of 2nd year follow-up, and no further implant loss, the cumulative survival rate remained 93.3% up to 5 years follow-up period.

DISCUSSION

The use of L-PRF plug as grafting and careful preparation of osteotomy site with piezoelectric ultrasonic device could allow for simultaneous crestal sinus floor elevation and short implant installation in posterior atrophied maxillae with RBH <4mm, extending the indications for implant rehabilitation.

Short implants versus longer implants in vertically augmented atrophic mandibles: A systematic review of randomised controlled trials with a 5-year post-loading follow-up

PURPOSE

To compare the clinical outcome of fixed prostheses supported by 4- to 8-mm-long implants with prostheses supported by longer implants placed in vertically augmented atrophic mandibles after a follow-up of 5 years in function.

MATERIALS AND METHODS

The Cochrane Central Register of Controlled Trials (CENTRAL) and MEDLINE were searched up to 1st September 2018 for randomised controlled trials (RCTs) with a follow-up of at least 5 years in function comparing fixed prostheses supported by 4- to 8-mm-long implants with prostheses supported by longer implants placed in vertically augmented atrophic mandibles. Outcome measures were prosthesis failure, implant failures, augmentation procedure failures, complications, and peri-implant marginal bone level changes. Screening of eligible studies, assessment of the risk of bias and data extraction were conducted in duplicate and independently by two review authors. The statistical unit of the analysis was the prosthesis. Results were expressed as random-effects models using mean differences for continuous outcomes and risk ratios (RR) for dichotomous outcomes with 95% confidence intervals (CIs).

RESULTS

Four eligible RCTs that included originally 135 patients were included. Two RCTs had a parallel-group design and two a split-mouth design. Short implants were 5.0 to 6.6 mm long and were compared with longer implants placed in posterior mandibles augmented with interpositional blocks of bone substitutes. All trials were judged at unclear risk of bias. Twelve (14%) bone augmentation procedures failed to achieve the planned bone height to allow placement of implants with the planned length. Five years after loading, 28 patients (21%) had dropped out from the four RCTs. There were no differences for patients having prosthesis (RR = 1.46; 95% CI: 0.52 to 4.09; P = 0.47; I2 = 0%) or implant (RR = 1.00; 95% CI: 0.31 to 3.21; P = 1.00; I2 = 0%) failures between the two interventions, but there were more patients experiencing complications (RR = 4.72; 95% CI: 2.43 to 9.17; P < 0.00001; I2 = 0%) and peri-implant marginal bone loss (mean difference = 0.60 mm; 95% CI: 0.36 to 0.83; P < 0.00001; I2 = 45%) at longer implants in augmented bone.

CONCLUSIONS

Five years after loading, prosthetic and implant failures were similar between the two interventions, but complications and peri-implant marginal bone loss were higher and more severe at longer implants placed in vertically augmented mandibles. Larger trials and longer follow-ups up to 10 years after loading are needed to confirm or reject the present preliminary findings. However in the meantime short implants could be the preferable option.

Application of Finite Element Model in Implant Dentistry: A Systematic Review

FEM was technologically innovated which initially aimed at answering structural analysis difficulties involving Mechanics, Civil and Aeronautical Engineering. FEM basically stands for a numerical model of analyzing stresses as well as distortions in the form of any agreed geometry. There for the shape is discretized into the so-called ‘finite elements’ coupled through nodes. Accuracy of the results is determined by type, planning and total number of elements used for a particular study model. 3-D FE model was designed for in-depth qualitative examination of the relations amongst implant, tooth, periodontal ligament, and bone. Scholarly work equating work reliability, validated with a 3-D modeling suggested that meticulous data can be acquired with respect to stress distribution in bone. Comparative results from 3-D FEA studies showed that 3D FEA, when matched with in-vivo strain gauge measurements were corresponding with clinical outcomes. The aim of this review of literature is to provide an overview to show the application of FEM in (Short) implant dentistry.

Long-term follow-up of single crowns supported by short, moderately rough implants-A prospective 10-year cohort study

OBJECTIVES

To evaluate prospectively the clinical and radiographic outcomes after ten years of short (6 mm) implants with a moderately rough surface supporting single crowns in the posterior region.

MATERIAL AND METHODS

Forty 6 mm modified sandblasted large-grit acid-etched (mod-SLA), soft tissue level implants were installed in the distal segments of 35 consecutive patients. After 6 weeks of healing, abutments were tightened, and single porcelain-fused-to-metal crowns were cemented. Implant survival, marginal bone loss, and clinical crown/implant ratio were evaluated at various time intervals up to 10 years after loading.

RESULTS

Two out of the 40 implants were lost before loading, one implant was lost after 7 years because of peri-implantitis. One patient with two implants died and was excluded from analysis. Two patients did not come at the 10-year follow-up and were considered as drop out (2 implants). The survival rate was 91.7% (n = 36). Thirty-three implants were available for marginal bone loss evaluation. A mean marginal bone loss after 10 years of function was 0.8 ± 0.7 mm. Between 5 and 10 years, the loss was 0.2 ± 0.4 mm. No technical complications were registered during the 10-year period. The clinical crown/implant ratio increased with time from 1.6 at the delivery of the prosthesis to 2.0 after 10 years of loading with no increase between 5 and 10 years.

CONCLUSION

Short (6 mm) implants with a moderately rough surface supporting single crowns in the posterior region and loaded after 6-7 weeks maintained full function for at least 10 years with low marginal bone resorption.

Short vs. Standard Laser-Microgrooved Implants Supporting Single and Splinted Crowns: A Prospective Study with 3 Years Follow-Up

PURPOSE

The aim of this study was to compare survival rates, marginal bone loss (MBL), and peri-implant soft tissue parameters between short and standard laser-microgrooved implants supporting single or splinted crowns 3 years after loading.

MATERIALS AND METHODS

30 subjects received 1 short ( ≤ 7 mm ) and 1 standard length ( ≥ 9 mm ) laser-microgrooved implant in adjacent sites of the premolar and molar regions of the mandible or maxilla. Peri-implant soft tissue parameters and intraoral radiographs were recorded at the delivery of definitive crowns (baseline) and 3 years later. Cumulative survival rate (CSR) and marginal bone loss (MBL) in relation to crown/implant (C/I) ratio, implant length, location, type of antagonist, and type of prosthetic design (single or splinted), were evaluated.

RESULTS

CSR of short implants was 98%, compared to 100% for standard implants, without significant statistical difference. MBL was not significantly different over the observation period, with an average of 0.23 ± 0.6 mm and 0.27 ± 0.3 mm for short and standard implants, respectively. No statistical differences were found between short and standard implants regarding plaque (14.7% vs. 15.7%), number of sites BOP (8.3% vs. 5.9%), probing depth (1.13 ± 0.6 mm vs. 1.04 ± 0.8 mm), and mean mucosal recession (0.18 ± 0.3 mm vs. 0.22 ± 0.3 mm). Analyzing MBL in relation to the C/I ratio, implant length, location, type of antagonist, and type of prosthetic design, no statistically significant differences were found.

CONCLUSION

Regardless of C/I ratio, implant length, location, type of antagonist, and type of prosthetic design, short and standard laser-microgrooved implants had similar survival rates, MBL, and peri-implant soft tissue conditions over the observation period of 3 years.

Evaluation of survival of 8 mm-length implants in posterior resorbed ridges: A pilot study

Context

Rehabilitation of jaws with reduced bone height is technically demanding and expensive. Short implants are emerging as an alternate in such cases.

Aim

This study aimed to evaluate the survival of implants of 8 mm in length (short implants), clinically and radiographically, in posterior resorbed ridges.

Materials and Methods

A total of 11 patients with single missing posterior tooth, having 9-10 mm of residual bone height determined using radiographs, were selected for the study. Twelve implants of 8 mm length were inserted in the resorbed alveolar ridges following standard operating procedure. A second-stage surgery was performed 4-6 months after implant placement for placement of gingival former. This was followed by placement of prosthesis. Twelve months after prosthesis placement, all the patients were examined clinically and radiographically.

Results

According to Albrektsson et al.'s criteria, all implants were successful with mean bone loss of 1.1 ± 0.32 mm mesially and 0.83 ± 0.35 mm distally with healthy gingival condition at 12-month follow-up.

Conclusion

Short implants (8 mm in length) can be a viable alternative in cases of atrophic alveolar ridges.

Clinical and Radiographic Evaluation of Short Implants Placed in the Posterior Mandible: A 1-Year Pilot Split-Mouth Study

In many cases, due to anatomical limitations, the placement of regular-length implants cannot be facilitated without the performance of advanced surgical procedures. However, these are associated with morbidity, prolonged treatment time, and costs. To overcome such disadvantages, short implants were introduced. The aim of this prospective pilot split-mouth study was to compare the clinical outcome between short implants (7 mm) and regular-length (≥10 mm) implants placed in the posterior mandible after 1 year of prosthetic delivery. Ten patients received 4 implants in the posterior mandible. Two short implants were placed in one side and 2 regular-length implants were placed contralaterally. These were restored by means of splinted screw-retained metal-ceramic crowns. Marginal bone loss (MBL) and soft-tissue parameters were compared. No implant failed. Both types of implants showed success rates of 90% and survival rates of 100%. From prosthetic delivery to 1 year post-loading a bone gain of +0.29 mm for short implants and +0.19 mm for regular-length implants was present without showing any statistically significant differences in MBL between the 2 implant types ( P > .05). Bleeding on probing, clinical attachment level, probing depth, and crown-to-implant ratio did not show any statistically significant differences between the 2 implant lengths ( P > .05). One case of chipping occurred in the regular-length implant group, leading to a prosthetic survival rate of 95%. Short implants showed a prosthetic survival rate of 100%. After 1 year, short implants showed comparable clinical outcomes to that of regular-length implants, making them a viable treatment option in the posterior mandible.

Can extra-short dental implants serve as alternatives to bone augmentation? A preliminary longitudinal randomized controlled clinical trial

OBJECTIVE

A randomized trial to assess clinical and radiographic outcomes of short versus standard dental implants placed with concomitant vertical bone augmentation.

METHOD AND MATERIALS

Patients requiring dental implants were randomized to receive either 6-mm implants (experimental) or 10-mm implants with vertical augmentation (control). Custom load-bearing healing abutments were connected to allow for indirect resonance frequency analysis measurements. Standardized radiographs were taken at implant placement (baseline), and at 3 and 12 months. Implants were restored at 3 to 6 months, and final measurements were taken at 12 months.

RESULTS

Fifty patients with 25 implants per group were included. Five implants failed, four experimental and one control (84% and 96% cumulative survival rate, respectively). Short implants required significantly less surgical time (51.6 ± 23 versus 68.5 ± 35 minutes, P = .05). Implant stability quotients at baseline (67.9 ± 8.3 experimental and 70.8 ± 7.6 control, P = .215) and 12 weeks (70.17 ± 7.4 and 72.03 ± 5.9, respectively, P = .513) were similar and unchanged. Positive correlation was found between the two measurement methods (r2 = .6, P = .025). One-year average marginal bone loss was slightly lower for the experimental group (0.6 ± 0.16 mm) compared to the control group (0.86 ± 0.19 mm); however, this was not statistically significant (P = .287).

CONCLUSION

Short dental implants may offer an alternative for implant placement in an atrophic jaw; however, they are associated with reduced first-year survival rate. Short dental implants should be used judiciously in light of this potential predicament, and alternatives assessed.

Short dental implants as compared to maxillary sinus augmentation procedure for the rehabilitation of edentulous posterior maxilla: Three-year results of a randomized clinical study

BACKGROUND

Several treatment options exist for the implant-supported rehabilitation of edentulous posterior maxilla.

PURPOSE

To compare maxillary sinus floor augmentation associated to standard length implants, with direct placement of implants of reduced length in the available residual bone.

MATERIALS AND METHODS

Patients with edentulous posterior maxilla and a residual height of 4-7 mm were randomly allocated to the test (short implants [SIs], 6.5 to 8.5mm long) or the control (sinus augmentation [SA] and implants ≥10mm long) group. Anorganic bovine bone was the grafting material for the control group. In both groups pure platelet-rich plasma was used to bioactivate implant surface prior to insertion. Implant and prosthesis survival, clinical variables, radiographic bone level change, quality of life, and patient satisfaction were assessed.

RESULTS

Twenty-five patients were treated in the control group (58 standard length implants) and 27 in the test group (42 SIs). After 3 years of follow-up no implant failure and biological or mechanical complications were recorded. Marginal bone loss, soft tissue, and oral hygiene parameters were similar in the 2 groups at both 1 and 3 years' follow-up. Postoperative pain, swelling and other symptoms and daily activities were better in the SIs group than in the SA group, while patients' satisfaction after 1 year was similar.

CONCLUSIONS

In spite of comparable medium-term clinical and radiographic outcomes, when the residual ridge height is sufficient for a safe placement, SIs may be preferred due to simplified protocol, less invasiveness, shorter treatment time, and reduced postoperative discomfort as compared to SA.

The influence of crown-to-implant ratio on marginal bone levels around splinted short dental implants: A radiological and clincial short term analysis

BACKGROUND

The amount of marginal bone resorption around dental implants is considered to have a significant impact on implant stability as well as implant survival rates.

PURPOSE

The aim of this prospective study was to investigate the influence of prosthetic as well as patient specific factors on marginal bone loss around short dental implants.

MATERIALS AND METHODS

Seventy-six implants, which supported splinted crowns were included for investigation. All implants were from the same type and had an intraosseous length of 6.5 mm and a diameter of 4.0 mm. Twenty implants were additionally splinted onto longer ones. Measurements of marginal bone loss were performed at a mean of 12.38 months after prosthetic loading and the mean follow-up for clinical evaluation was 20.52 months.

RESULTS

Overall two implant failures were recorded, revealing a survival rate of 97.3%. Marginal bone resorption around 72 short implants measured 0.71 mm (SD: 0.74 mm) and was found to have a strong correlation with calculated Crown-to-Implant ratio (r = .71; P < .001). Age, gender, insertion torque, implant surface area, location, position, bone quality, and insertion torque did not influence peri-implant bone loss after one year of loading.

CONCLUSION

Within the limitations of the study, it is suggested that Crown-to-Implant ratios should not exceed 1.7 to avoid increased early marginal bone loss.

Impact of platform switching on inter-proximal bone levels around 8.5 mm implants in the posterior region; 5-year results from a randomized clinical trial

AIM

To assess the medium-term results of 8.5 mm implants supplied with a conventional platform-matched implant-abutment connection or a platform-switched design.

MATERIALS AND METHODS

Eighty patients with one or more missing teeth in the maxillary or mandibular posterior zone were randomly assigned for treatment with implants with a conventional (control group) or platform-switched (test group) implant-abutment connection. Follow-up visits were conducted 1 month, 1 year and 5 years after functional loading. Inter-proximal bone loss, assessed with standardized peri-apical radiographs, clinical parameters, survival of implants and satisfaction of patients were the outcome parameters studied.

RESULTS

After 5 years of loading, five of the 80 patients were lost to follow-up. The inter-proximal bone loss in the test group (0.38 ± 0.61 mm) was comparable to the bone loss in the control group (0.41 ± 0.47 mm; p = 0.201). Remarkably, bone loss has not progressed compared to the 1-year results. Implant survival, clinical parameters and satisfaction of the patients were favourable and comparable for the test and control group.

CONCLUSION

The 5-years results showed that inter-proximal bone resorption was minor and comparable around platform-matched and platform-switched implants, and implant survival, peri-implant health and patients' satisfaction were favourable.

In Vitro Evaluation of the Primary Stability of Short and Conventional Implants

The objective of this study was to evaluate the primary stability of short and conventional dental implants with different platform types at different site densities in vitro. One hundred twenty implants were placed in polyurethane blocks that simulate different bone densities (bone types I and IV). The implants were divided into 10 groups, with 12 implants each according to the type of prosthetic connections (external hexagon, EH; morse taper, MT) and size of the implants (conventional: 4 × 10 mm; short: 5 × 5, 5.5 × 5, 5 × 6, and 5.5 × 6 mm). Insertion torque and resonance frequency analyses were performed to evaluate the primary stability. The Kruskal-Wallis test complemented by Dunn's test and the Mann-Whitney test were used for statistical analysis. These tests were applied at the confidence level of 95% (P < .05). The implants installed in blocks with density type IV exhibited reduced insertion torque compared with implants placed in blocks with density type I. Short implants with EH exhibited increased insertion torque compared with short implants with MT in blocks with bone density type I. In general, implants installed in blocks with density type I exhibited greater primary stability. The short implants with EH with a 5.5-mm diameter and the short implants with MT with a 5-mm diameter exhibited reduced primary stability. No differences between short and conventional implants were noted. Short implants have primary stability and insertion torque at least equivalent to conventional implants irrespective of the platform type and density of the site.

Short (6-mm) dental implants versus sinus floor elevation and placement of longer (≥10-mm) dental implants: a randomized controlled trial with a 3-year follow-up

OBJECTIVES

To investigate whether short (6-mm) dental implants could be an alternative to sinus floor elevation (SFE) and placement of longer (≥10-mm) implants in the posterior maxilla.

MATERIALS AND METHODS

Over a 3-year period, all patients presenting with partial edentulism in the posterior maxilla were considered for inclusion in this randomized controlled trial. Patients were randomly chosen either to receive short (6-mm) implants (test group [TG]) or to undergo SFE with simultaneous placement of standard-length (≥10-mm) implants (control group [CG]). SFE was performed using the lateral technique. In both groups, tapered implants (AnyRidge, MegaGen, Gyeongbuk, South Korea) were placed. All implants were loaded after 4 months of healing. At each annual follow-up session, clinical and radiographic parameters were assessed. Primary outcomes were implant survival, stability (measured with the implant stability quotient [ISQ]), marginal bone loss (MBL), and complications; secondary outcomes were patient satisfaction and treatment time and cost.

RESULTS

Thirty-three patients were assigned to the TG and 20 to the CG. Forty-five implants were inserted in each group. At 3 years, implant survival rates were 100% and 95.0% for the TG and CG, respectively; this difference was not statistically significant (P = 0.38). The mean ISQ values of the TG and CG did not differ at placement (68.2 vs. 67.8, P = 0.1), at delivery of the final restoration (69.5 vs. 69.4, P = 0.9), and after 1 year (71.0 vs. 71.5, P = 0.1); at 3 years, the CG had a significantly higher mean ISQ than the TG (72.4 vs. 71.6, P = 0.004). Mean MBL was significantly higher in the CG than in the TG, both at 1 year (0.14 mm vs. 0.21 mm, P = 0.006) and at 3 years (0.20 mm vs. 0.27 mm, P = 0.01). A few complications were reported. Surgical time and cost were significantly higher in the CG than in the TG (P < 0.0001). Patient satisfaction was high in both groups.

CONCLUSIONS

In this randomized controlled trial, results for short (6-mm) implants were similar to those for longer (≥10-mm) implants in augmented bone. Short implants might be preferable to SFE, because the treatment is faster and less expensive. Long-term randomized controlled trials are required to confirm these results.

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.

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.

Long-term retrospective evaluation of short implants in the posterior areas: clinical results after 10-12 years

AIM

To evaluate the long-term clinical results of short implants in the posterior areas and analyse the possible influence of different variables on implant success rate and marginal bone loss (MBL).

METHODS

A retrospective study design was used. Patients were included if they had received one or more short implants (≤8.5 mm long) in the posterior jaws at least 10 years earlier. All implants were embedded in plasma rich in growth factors (PRGF). The cumulative success rate was the primary outcome. MBL and the influence of different variables as secondary outcomes were assessed.

RESULTS

A total of 111 short implants (7.0, 7.5 and 8.5 mm in length) placed in 75 patients met the inclusion criteria. Of which, 94 were splinted to longer ones. The mean follow-up was 123.3 months (SD = 10.4 months). The mean crown-implant ratio was 1.4 (SD = 0.3). The mean MBL was 1.0 mm at mesial (SD = 0.7) and 0.9 mm (SD = 0.6) at distal aspect. One short implant failed. Success rate was 98.9% and 98.2% for the implant and patient-based analysis respectively. No relationship was observed between the studied variables and the MBL.

CONCLUSIONS

These clinical results support the use of short implants as an effective and safe long-term treatment option.

Short implants in maxillary and mandibular rehabilitations: interim results (6 to 42 months) of a prospective study

The aim of this single-cohort study was to evaluate clinical survival and success of partial rehabilitation supported by reduced-length implants in maxilla and mandible. Data from 53 short implants placed in 41 patients are presented. Before surgery mean residual bone height was 6.21 ± 1.05 mm in the upper jaw and 10.73 ± 1.63 mm in the mandible. None of the implants failed, and the cumulative survival rate was 100% at 1 year after prosthetic loading. Mean peri-implant bone loss was 0.69 ± 0.24 mm for maxillary implants and 0.73 ± 0.23 mm for mandibular implants, and there was no significant difference between the 2 jaws. No complications were recorded. Despite the limitations of this study concerning study design and sample size, short implants may be considered effective in supporting partial rehabilitation in both maxilla and mandible. More well-designed studies with a larger sample size and longer follow-up are needed to validate the use of short implants.

A 5- to 6-year radiological evaluation of titanium plasma sprayed/sandblasted and acid-etched implants: results from private practice

OBJECTIVES

This study aimed to determine bone level changes after 5-6 years of follow-up for a large group of one-stage dental implants consecutively placed in private practice. Potential confounding factors influencing crestal bone loss (CBL) were also assessed.

MATERIALS AND METHODS

A total of 378 transmucosal Straumann implants in 174 patients were examined radiographically. Half of the study population (189 implants) had a titanium plasma sprayed (TPS) surface, and the other half (189 implants) were sandblasted and acid-etched (SLA). Mean CBL was measured from 5 to 6 years post-operative radiographs on the basis of known implant landmarks. Correlations of increased CBL with various independent variables were also investigated. Statistical analyses were performed using generalized estimating equations.

RESULTS

Radiographic measurements showed a CBL ≤ 1.5 mm for 65% of studied implants. A CBL > 1.5 mm was found for 28% of implants, while 7% of implants had a CBL ≥ 3 mm. Three factors significantly influenced CBL (P < 0.05): implant surface texture (TPS > SLA), smoking status (smokers > non-smokers), and implant location (anterior > posterior).

CONCLUSIONS

CBL was ≤1.5 mm after 5-6 years for the majority of followed implants. For implants with a CBL > 1.5 mm, statistically significant correlations were found for TPS surface type, anterior jaw locations, and smoking. Implant length did not influence CBL.