Short vs standard implants associated with sinus floor elevation: a randomized controlled trial

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. 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 4months 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. Thirty-three patients were assigned to the TG and 20 to the CG. Forty-five implants were inserted in each group. At 3years, 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 1year (71.0 vs. 71.5, P=0.1); at 3years, 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 1year (0.14mm vs. 0.21mm, P=0.006) and at 3years (0.20mm vs. 0.27mm, 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. 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.

Data sourcesPubMed/Medline, Embase and Cochrane Library databases supplemented by searches of the journals; Clinical Implant Dentistry and Related Research, Clinical Oral Implants Research, International Journal of Oral and Maxillofacial Implants, International Journal of Oral and Maxillofacial Surgery, Journal of Clinical Periodontology, Journal of Dentistry, Journal of Oral and Maxillofacial Surgery, Journal of Oral Implantology, Journal of Oral Rehabilitation, Journal of Periodontology, Periodontology 2000.Study selectionRandomised controlled trials (RCTs) and prospective studies with at least ten patients, published in the last ten years that compared short and standard implants and published in English were considered.Data extraction and synthesisA single author abstracted data with checking by a second reviewer. Methodological quality was assessed using the Jadad Scale and the Cochrane risk of bias tool. Risk ratios (RR) were calculated for implant survival rates, complications and prostheses failures and marginal bone loss was evaluated using mean difference (MD).ResultsThirteen studies consisting of ten RCTs and three prospective studies were included. The ten RCTs were considered to be of high quality. Two thousand six hundred and thirty-one implants were placed in 1269 patients (981 short and 1650 standard implants). Thirty-eight short implants failed (3.87%) and 45 standard implants (2.72%). Random effects meta-analysis found no statistically significant difference between standard implants and short implants placed in the posterior regions; RR =1.35 (95% CI; 0.82-2.22: P=0.24). Marginal bone loss was evaluated in nine studies and no differences in marginal bone loss were observed. Complications were reported by seven studies and no significant difference was seen between standard and short implants; RR= 0.54 (95% CI; 0.27-1.09: P = 0.08). There was also no significant difference in prosthesis failures between standard and short implants; RR= 0.96 (95% CI: 0.44-2.09: P = 0.92)ConclusionsShort implants showed marginal bone loss, prosthesis failures and complication rates similar to standard implants, being considered a predictable treatment for posterior jaws, especially in cases that require complementary surgical procedures. However, short implants with length less than 8 mm (4-7 mm) should be used with caution because they present greater risks for implant failures when compared to standard implants.

BackgroundNowadays, short dental implants are being increasingly applied in extremely resorbed posterior regions. The recent studies have indicated that short implants present a similar success rate to conventional implants. It is assumed that short implants can avoid additional surgical morbidity and are less technically demanding. However, high-quality evidence (≥Ib: evidence from at least one randomized controlled trial) on comparing the clinical outcome of short implants and longer implants combined with osteotome sinus floor elevation (OSFE) technique is limited.Methods/DesignThe proposed study is designed as a prospective single-center, three-arm parallel group, randomized controlled trial. We plan to enroll 150 patients in need of dental implant treatment in the posterior maxilla. The inclusion criteria include: age ≧18 years, partial edentulism in the posterior maxilla for at least 3 months from tooth loss, residual bone height ranging from 6 to 8 mm, sufficient bone width (≥6 mm) in the edentulous region. The patients will be divided into three groups according to a table of random numbers: group 1: short implants (6 mm) alone; group 2: short implants (8 mm) combined with osteotome sinus floor elevation (OSFE); group 3: standard implants (10 mm) combined with OSFE. The assignment will be concealed from the clinical operators until the beginning of implant surgery. The outcome examiners and patients will be kept blinded to the assignment. Implant survival rates, implant success rates, complications, resonance frequency analysis (RFA) measurements, marginal bone level, treatment time and patient-reported outcome (visual analogue scale for intraoperative discomfort and postoperative pain) will be recorded. Clinical re-evaluations will be performed at 12, 24, 36 and 60 months after crown placement.DiscussionThe results of the trial will support better decision-making for dental implant treatment in atrophic maxillary ridges. If favorable, the use of short implants may avoid adjunct procedures used for implant insertion, thus reducing operative time, complexity and postoperative discomfort.Trial registrationClinicaltrials.gov identifier: NCT02350075 (registered on 17 February 2015).

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

Objectives: This study aimed to assess the effect of cyclic loading on the amount of fixture-abutment microgap in short implants compared to standard implants. Materials and Methods: This in vitro experimental study was conducted on two groups of short and standard implants (n = 10). The microgap at the fixture-abutment interface was measured under a light microscope at ×75 magnification. The implants were mounted in an acrylic resin to simulate the jawbone. They were then subjected to cyclic loading by applying 75 N load with 1 Hz frequency along the longitudinal axis of each implant (perpendicular to the abutment surface). After 500,000 cycles, corresponding to 20 months of mastication in the oral environment, the implants were removed from the acrylic resin, and the microgap at the fixture-abutment interface was measured again under a stereomicroscope by a blinded examiner. Data were then analyzed by t-test using SPSS version 22 (α = 0.05). Results: The mean microgap was 13.59 ± 3.80 µm in the standard and 20.41 ± 11.30 µm in the short implants before cyclic loading (p=0.087). These values changed to 15.22 ± 5.44 and 24.53 ± 21.85 µm, respectively, after cyclic loading. No significant difference was noted in the amount of microgap between the standard and short implants after cyclic loading (p=0.222). Conclusion: Cyclic loading increased the amount of fixture-abutment microgap in both the standard and short implants. However, the difference in this respect was not significant between the two implant lengths. Thus, short implants could be reliably used in patients with limitations for surgery to restore function and esthetics.

The use of short implants (5 mm diameter × 6 mm length) has increased in recent years, and they have mostly been indicated in the posterior maxillary areas in cases of insufficient bone height, as an alternative to sinus lift procedures. Short implants have rarely been proposed in cases of early failure (less than one month) of maxillary first molar standard implants placed after sinus lifting. We are reporting a 64-year-old female smoker who was referred for consultation concerning the extraction and implantation of tooth #16. The periodontal preparation and smoking cessation were followed by a sinus lifting. After a 10-month post-graft period, a standard implant (4.7 × 11.5 mm; Zimmer Biomet®, Warsaw, IN, USA) was placed. One month postoperatively, early failure occurred due to failure in osseointegration, and the implant was removed; three months later, a short implant (5 mm diameter × 6 mm length) was placed. The second stage of surgery was carried out at six months postoperatively. After four weeks, a crown was set. The control at 13 months showed a bone-integrated implant without lateral bone loss. The main risk factors associated with implant failure are low bone density, sinus grafting, and chronic smoking. In this case report, the association of these three risk factors led to standard implant failure. A short implant was proposed in order to avoid a new bone graft. A 2:1 crown-to-implant ratio has no impact on marginal bone loss or implant survival. In conclusion, the short implant (5 mm diameter × 6 mm length) may be a minimally invasive alternative in cases of early loss (less than one month) of a standard implant placed after sinus lifting without any additional bone grafting procedure. This data must be confirmed with a cohort study.

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

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. 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. Sixty implants were inserted in ten patients. Mean insertion torque was slightly lower for 4-mm implants than 10-mm implants (38.1Ncm vs. 42.2Ncm) 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. Within the limitations of this study, we conclude that short dental implants (8mm 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.

This study evaluated long-term effectiveness UV functionalised short implants (≤ 6mm) placed in the posterior segments of the atrophied maxilla. The study included 47 patients from 2018 to 2023 (aged 27 to 56years, 24 women and 23 men) without any systemic diseases, with unilateral/bilateral missing teeth and vertical atrophy of the posterior maxillary area. Total installed were 64 short UV-functionalized implants and 62 standard implants over 10mm in length in segments maxilla with sufficient bone parameters. Clinical, laboratory and cone beam computed tomography (CBCT) methods were used to plan implant therapy. The clinical indices included the following parameters: ISQ, MBL, OHIP-G scale. For short implants, the median ISQ at placement was 62.2 for primary stability and the median ISQ at 5months was 69.6 ISQ. For standard implant, the mean ISQ at placement was 64.3 ISQ, and ISQ after 5months was 71.6 ISQ. After 6months mean MBL short implants 0.87mm, after 1year 1.13mm, after 5years was 1.48mm. After 6months mean MBL standard implants 0.84mm, after 1year 1.24mm, after 5years was 1.58mm. Mean OHIP-G scores-patients satisfaction with the implant at 4.8 ± 0.3, satisfaction with the operation 4.6 ± 0.4; satisfaction with prosthetics 4.7 ± 0.5. Cumulative success rate 5years short implants was 96.7%, standard implants was 97.4%, and prosthesis cumulative survival rate was 97.2%. Short ultraviolet functionalized implants used in the posterior resorbed segment of maxilla have been shown to be a reliable alternative to sinus lift, demonstrating fewer complications, reduction in the number of additional surgical interventions and showed satisfactory long-term survival.

Short and mini dental implants have been widely used as treatment alternatives in certain selected clinical situations. However, a profound scientific analysis of the mechanical and biomechanical impact of the reduced length and diameter of these implant geometries has not been published until now. Using finite element analysis, a series of different experimentally designed short and mini implants have been analysed with regard to their load transfer to the alveolar bone and have been compared to respective standard commercial implants. Mini implants have been inserted in an idealised bone bed representing the anterior mandibular jaw region and loaded with a force of 150N. An immediate loading condition was assumed and analysed using the contact analysis option of the FE package MSC.Marc/Mentat. Short implants were inserted in an idealised posterior bone segment and loaded in osseointegrated state with forces of 300N. Clearly increased bone loading was observed for the short and mini dental implants compared with standard implants, clearly exceeding the physiological limit of 100MPa. The determined biomechanical characteristics could explain the slightly increased failure rate of short and mini dental implants.

Still, a major focus of research in implantology is how crown height and width affect marginal bone loss (MBL) and the long-term durability of dental implants. Maximizing the success of implants and lowering problems depends on an awareness of these elements. Following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, this systematic review searched pertinent studies across several databases using keywords unique to databases. Studies on MBL and long-term implant stability evaluated in the review included those on crown height and width, horizontal and vertical cantilevers, and prosthesis dimensions. In the chosen studies, we found that both implant success and crestal bone loss were greatly influenced by crown height and width. Particularly in the posterior sections, horizontal cantilevers were connected to both increasing MBL and mechanical problems. Vertical cantilevers also affected MBL; however, their impacts were more obvious in circumstances with greater crown heights. Greater prosthesis widths, especially in the mandibular molar area, were linked to higher MBL. Bone density and insertion torque (IT) were the main determinants of MBL, more than the primary implant stability quotient. Early MBL was influenced by abutment height, mucosal thickness, and implant insertion depth; bone levels stabilized six months later. Short implants allow single crowns to be supported, but in some cases, a higher failure rate was seen. The success and stability of dental implants were found to be mostly dependent on crown height, width, and cantilever design. MBL and long-term stability are greatly influenced by horizontal and vertical cantilevers, which calls for careful design and planning. With specific care for bone density, IT, and early MBL stabilization, both short and standard implants can produce equivalent results. These results highlight the need for customized treatment plans to maximize implant success and lifetime.

To evaluate prospectively the clinical and radiographic outcomes after 2 years of loading of 6 mm long moderately rough implants supporting single crowns in the posterior regions. Forty SLActive Straumann short (6 mm) implants were placed in 35 consecutively treated patients. Nineteen implants, 4.1 mm in diameter, and 21 implants, 4.8 mm in diameter, were installed. Implants were loaded after 6 weeks of healing. Implant survival rate, marginal bone loss and resonance frequency analysis (RFA) were evaluated at different intervals. The clinical crown/implant ratio was also calculated. Two out of 40 implants were lost before loading. Hence, the survival rate before loading was 95%. No further technical or biological complications were encountered during the 2-year follow-up. The mean marginal bone loss before loading was 0.34+/-0.38 mm. After loading, the mean marginal bone loss was 0.23+/-0.33 and 0.21+/-0.39 mm at the 1- and 2-year follow-ups. The RFA values increased between insertion (70.2+/-9) and the 6-week evaluation (74.8+/-6.1). The clinical crown/implant ratio increased with time from 1.5 at the delivery of the prosthesis to 1.8 after 2 years of loading. Short implants (6 mm) with a moderately rough surface loaded early (after 6 weeks) during healing yielded high implant survival rates and moderate loss of bone after 2 years of loading. Longer observation periods are needed to draw more definite conclusions on the reliability of short implants supporting single crowns.

Fifteen-Year Follow-up of Short Dental Implants in the Completely Edentulous Jaw: Submerged Versus Nonsubmerged Healing.

A Retrospective Multicenter Study on Short Implants With a Laser-Microgrooved Collar (≤7.5 mm) in Posterior Edentulous Areas: Radiographic and Clinical Results up to 3 to 5 Years

The goal of this study was to evaluate the cumulative survival rate and marginal bone loss (MBL) of extra-short (5- and 6-mm-long) and short (6.5-mm-long) implants inserted into severely atrophic, partially edentulous posterior maxillae and mandibles that were immediately restored with provisional fixed dental prostheses. Between October 2013 and December 2017, partially edentulous patients with severe vertical bone atrophy in the posterior area in need of replacement of premolars and/or molars with fixed prostheses were enrolled in the study. Analysis of cumulative survival rate and MBL was determined with respect to implant length at the longest, biannual follow-up period (38 ± 10 months; range: 25 to 48 months). Fifty-five patients were included in the study. A total of 62 extra-short (5 and 6 mm), 15 short (6.5 mm), and 69 standard-length (≥ 10 mm) implants were immediately placed and loaded. Cumulative survival rates were similar for all implants (99.3%). One mandibular extra-short implant failed and was removed but was replaced 2 months later with another implant of the same length and diameter and successfully reloaded. Implant length did not impart any significant differences in MBL, though the presence or absence of platform switching was influential. The cumulative survival rate and MBL reported in this study encourage the use of short and extra-short implants to immediately restore with fixed prostheses partially edentulous patients with severe vertical bone atrophy in posterior areas. Thus, it could be an alternative treatment to vertical bone augmentation.