Short and Extra Short Dental Implants in Osseous Microvascular Free Flaps: A Retrospective Case Series

There is limited information regarding implant and prosthetic survival after osseous microvascular free flap (OMFF). This case series aims to describe the placement of short and extra short implants in osseous microvascular free flaps to support prostheses, and present an up to 40-month retrospective follow-up. Short and extra short dental implants were placed in six fibula free flaps (FFF) and in two microvascular deep circumflex iliac artery (DCIA) flaps. In total, 27 short and extra short dental implants have been placed into two different types of free flaps. Kaplan-Meyer (K-M) survival analyses were performed to evaluate the survival and success outcomes of implants and prostheses. Out of the eight patients reconstructed with free flap, five were rehabilitated with prostheses, one patient has a temporary prosthesis, and two patients are in the process of prosthetic rehabilitation. Twenty-seven implants were followed up for up to 40 months, and K-M analyses showed 100% implant survival probability (95% confidence interval: 100%), while the implant success probability was 91.0% (95% confidence interval: 68.6-97.7%). Short and extra short dental implants placed in OMFF presented high survival and success rates in a retrospective case series after up to 40 months.

Finite element analysis (FEA) of stress distribution in platform-switched short dental implants

The distribution of stress on short platform switched dental implants is of interest. Hence, the mandibular posterior molar area was modelled using a three-dimensional finite element method (FEM) with a continuous 1.5 mm cortical bone thickness and an inner cancellous bone core. The implants used in the study were 5 mm long, 4.5 mm wide and 3.5 mm wide at the abutments. 120 N of force was applied in both the vertical and oblique (20° and 35°) directions to create a realistic simulation. ANSYS Workbench was generated for each model. Von Mises stress was assessed in the cortical and cancellous bones at varying depths. Ten noded tetrahedron elements with three degrees of freedom per node were employed to interpret translations on the x, y, and z axes. The stress-based biomechanical behaviour of platform switched short osseo-integrated implants varied across all 5 positions in FEM simulations, based on the depth of implant placement, the direction of applied force, and the shape of the bone. Data shows that opposite forces to the vertical forces caused more damage. Thus, the implantation of subcrestal implants resulted in reduced stress on the cortical and cancellous bone.

Single crown restorations supported by 6-mm implants in the resorbed posterior mandible: A 10-year prospective case series

PURPOSE

To assess marginal bone level changes, implant and restoration survival, condition of the peri-implant mucosa, and the patient's satisfaction with the single restoration supported by a 6-mm long implant in the posterior mandible after 10 years in function.

MATERIALS AND METHODS

Twenty-one consecutive patients missing premolars or molars in the posterior mandible, with a bone volume consisting of a width of at least 6 mm and an estimated height of 8 mm between the top of the ridge and alveolar nerve, were included. Each patient received one or more 6-mm implants. After 3 months, the implants were restored with custom-made titanium abutments and cemented zirconia-based porcelain crowns. The clinical examination and radiograph data were assessed at restoration placement and after 12, 60, and 120 months. The patients answered a questionnaire to score their satisfaction before treatment and after 12, 60, and 120 months with the restoration in function.

RESULTS

A total of 31 implants were placed. Implant survival was 100%. The 10-year mean marginal bone loss was 0.18 mm (SE: 0.08). The plaque, calculus, gingiva, and bleeding indices scores were low as was the mean pocket probing depth. The patients' satisfaction was high.

CONCLUSION

The 10-year follow-up data of this limited case series study reveal that 6-mm dental implants inserted in the resorbed posterior mandible provide a solid basis for single tooth restorations.

Single crowns in the posterior maxilla supported by either 11-mm long implants with sinus floor augmentation or by 6-mm long implants: A 10-year randomized controlled trial

OBJECTIVES

To compare the clinical performance of single crowns in the posterior maxilla supported by either 11-mm long implants combined with maxillary sinus floor augmentation (MSFA) surgery or by 6-mm long implants during a 10-year follow-up period.

MATERIALS AND METHODS

Subjects were randomly allocated to receive one 11-mm long implant in combination MFSA or to receive one 6-mm long implant without any grafting. Twenty-one implants in 20 patients were placed in the 6-mm group and 20 implants in 18 patients were placed in the 11-mm group. Both groups were followed by clinical and radiographic examinations up to 10 years. Patients' satisfaction was also scored before treatment.

RESULTS

Two patients died and eight patients moved during the follow-up. Two patients lost an implant in the 6-mm group and one implant was lost in the 11-mm group (implant survival 89.5% and 90.9%, respectively). From loading to 10 years' follow-up, mean ± SE marginal bone loss in the 6-mm group and 11-mm group was 0.18 ± 0.10 mm and 0.26 ± 0.12 mm, respectively, without a significant difference between the groups at 10 years (p = .650). In both groups, indices scores for plaque, calculus, gingiva and bleeding were low as well as mean pocket probing depth. Patients' satisfaction at 10 years was high in both groups; mean overall satisfaction in the 6-mm group and 11-mm group was 9.6 ± 0.6 and 9.2 ± 0.8, respectively (p = .168).

CONCLUSIONS

Placement of 6-mm implants or 11-mm implants combined MFSA are equally successful during a 10-year follow-up period when applied for supporting a single restoration.

Extra-Short 4-mm Implants Splinted to 10-mm Implants in the Posterior Maxilla: 3-year Results

PURPOSE

To evaluate the 3-year success and survival rates of fixed prostheses supported by 4-mm extra-short implants splinted to 10-mm implants in patients with shortened maxillary arches and low maxillary sinus floors.

METHODS

A total of 11 patients with reduced alveolar bone heights due to low maxillary sinus floors received two or three titanium-zirconium tissue-level implants: one or two extra-short (4 mm) implants, and one implant 10 mm in length. After 6 months, prosthetic rehabilitation with splinted crowns connecting the 4- and 10-mm implants was performed. Follow-up visits and maintenance protocols were implemented every 4 to 6 months.

RESULTS

The 11 patients were treated with 11 10-mm implants and 17 4-mm implants. One extra-short implant failed and was removed before loading, and its planned design was modified from three splinted crowns to a bridge between the 10- and 4-mm implants. After 36 months, all (11/11) prosthetic rehabilitations connecting the 10-mm (11/11) and 4-mm (16/16) implants were functional. At the 10-mm implant sites, the median (interquartile range [IQR]) probing depth and marginal bone loss measured 2.9 mm (2.3 to 3.2) and 1.3 mm (1.0 to 1.5), respectively. At the 4-mm implant sites, the median (IQR) probing depth and marginal bone loss measured 2.9 mm (2.4 to 3.1) and 0.3 mm (0.1 to 0.5), respectively.

CONCLUSION

Prosthetic rehabilitation with splinted crowns connecting 4-mm and 10-mm implants showed promising outcomes in shortened maxillary dental arches after 3 years. Additional studies are needed to further validate these findings.

Clinical performance of splinted 4.5-mm extra-short implants. A controlled retrospective cohort study

PURPOSE

To compare survival, marginal bone loss (MBL) and prosthetic complications of 4.5-mm extra-short implants and longer implants splinted to the same type of implant.

MATERIALS AND METHODS

A retrospective controlled cohort study was performed. The 4.5-mm extra-short group (study group; SG) included 48 consecutively placed implants that met inclusion criteria. Control group (CG) included 48 implants splinted to them. The same surgical team treated the 39 patients included, and all the implants were restored with a screw retained fixed restoration and intermediate abutments. Immediate and conventionally loaded implants were included.

RESULTS

All the implants were in function during the follow-up period (14 ± 3.4 SD and 17 ± 13 SD months for SG and CG). No differences in technical complications were observed between both groups (1 and 2 screw loosening for SG and CG; 2 fractures in provisional prosthesis for SG; p=0.310). Marginal bone stability was similar for SG and CG at mesial level (SG: Mean -0.01 ± 0.28 SD mm Vs CG Mean -0.18 ± 0.72 SD mm; p=0.270) and at distal level (SG: Mean 0.02 ± 0.39 SD mm Vs CG Mean -0.18 ± 0.68 SD mm; p=0.076).

CONCLUSIONS

The same good clinical performance could be observed for 4.5-mm implants and longer implants under the same prosthesis.

Implant rehabilitation of a posterior maxilla with 4-mm long implants splinted to a 10-mm long implant in a patient with osteopenia taking antiresorptive drugs: A 5-year follow-up case report

The report describes the rehabilitation of a maxillary arch with limited bone volume in a 67-year-old female taking antiresorptives due to osteopenia. One 10-mm and two extra-short 4-mm implants were inserted, and implant-supported splinted crowns were fabricated. The 5-year follow-up showed stable bone levels, despite poor initial stability (ISQ: 14-51).

Biomechanical analysis of different fixed dental restorations on short implants: a finite element study

OBJECTIVES

Although the use of short implants is becoming more common for patients with atrophic alveolar ridges, their use is still quite limited. This is due to the lack of data of long-term survival compared to standard-length implants. The aim of this study was to determine the load in the bone and implant system with different superstructures.

METHODS

Three kinds of prosthetic restorations were created on short implants based on CT-Data. Two short implants with different macro-geometries were used. The implants were inserted in idealised posterior lower mandibular segments and afterwards restored with a crown, a double splinted crown, and a bridge.

RESULTS

The analysis was performed under load of 300 N either divided between a mesial and distal point or as a point load on the pontic/mesial crown. The different design of the implant systems had a noticeable influence on the stress in the cortical bone, in the implant system, and the displacement of the superstructure as well.

CONCLUSIONS

Compared with implants of standard length, higher stresses were observed, which can lead early failure of the implant during the healing period or a late cervical bone resorption. Precise indications are essential for short implants to avoid the failure of short implants.

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

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

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

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

Randomized clinical trial evaluating the effect of splinting crowns on short implants in the mandible 3 years after loading

OBJECTIVE

To compare the radiographic marginal bone loss and clinical parameters of splinted and non-splinted fixed dental prostheses on short implants in the posterior region of the lower jaw 3 years after loading.

MATERIAL AND METHODS

Twenty patients, 15 female and five males, with uni- or bilateral free-end situations in the mandible participated in the study. Two short implants (7 mm) in the posterior mandible were placed and patients were randomized to receive splinted (n = 11) or non-splinted (n = 13) cemented crowns. Marginal bone loss (MBL) was assessed on radiographs taken with customized positioning jigs at baseline, 1 and 3 years after loading. Plaque index (PI), gingival index (GI), probing depth (PD), and bleeding on probing (BOP) were measured. (ClinicalTrials.gov; identifier: NCT03558347).

RESULTS

After 3-year survival rate of altogether 48 implants was 100% for both groups. Success rate (according to Papaspyridakos, Chen, Singh, Weber, & Gallucci, 2012) was 84.6% for non-splinted and 86.4% for splinted implants. At restoration level survival rate was 100% for both groups. Marginal bone level changes showed mean gain of 0.3 ± 0.8 mm for non-splinted and 0.1 ± 0.5 mm for splinted implants 3 years after loading. Statistical analysis showed no significant difference in PI, GI, PD, BOP, and marginal bone loss between both groups (p > .05).

CONCLUSION

Within the limitations of this study it can be concluded that splinting crowns on short implants neither seems to affect the amount of marginal bone loss nor peri-implant health 3 years after loading.

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.

Single crown restorations supported by 6-mm implants in the resorbed posterior mandible: A five-year prospective case series

Purpose

To assess clinical performance of single restorations supported by 6‐mm long implants in the posterior mandible after 5 years in function.

Materials and Methods

Twenty‐one consecutive patients with the absence of premolars or molars in the posterior mandible and an estimated bone volume of at least 6 mm in width and an estimated height of 8 mm between the top of the ridge and alveolar nerve were included. Each patient received one or more 6‐mm implants. Custom‐made titanium abutments with cemented zirconia‐based porcelain crowns were placed after a 3‐month osseointegration period. Data of clinical examinations and radiographs were assessed at placement of the restoration and 12 and 60 months thereafter. The patients answered a questionnaire to score the satisfaction before treatment and after 12 and 60 months with the restoration in function.

Results

Implant survival was 100%. Five‐years' mean marginal bone loss was 0.14 mm (SD: 0.4). Indices scores for plaque, calculus, gingiva, and bleeding were low as well as mean pocket‐probing depth. Patients' satisfaction was high.

Conclusion

Five‐year follow‐up data of this limited case series study revealed that 6‐mm dental implants inserted in the resorbed posterior mandible provide a solid basis for single tooth restoration.

Clinical and radiographic peri-implant outcomes of short dental implants placed in posterior jaws of patients with treated generalized aggressive periodontitis: A 3-year follow-up study

BACKGROUND

Studies assessing clinical and radiographic peri-implant parameters around short dental implants (SDIs) in treated generalized aggressive periodontitis (GAgP) patients are scant.

OBJECTIVES

This 3-year follow-up study aimed to compare the clinical peri-implant and radiographic bone status around SDIs placed in partially edentulous patients treated for GAgP and periodontally healthy patients and to assess the implant success rate between both the groups.

MATERIALS AND METHODS

A total of seven patients clinically diagnosed with GAgP and seven periodontally healthy patients was included in the clinical study. Forty-eight (29 maxilla; 19 mandible) and 11 (8 maxilla; 3 mandible) SDIs were placed in the GAgP group and healthy group, respectively. Plaque index (PI), bleeding on probing (BOP), probing depth (PD), and clinical attachment level (CAL) were recorded at six sites around all teeth and implants. Marginal bone loss (MBL) was studied incorporating in a specialized software and examined on a calibrated computer display screen with the help of an image analyzer. Patient satisfaction was recorded using a questionnaire sheet that contained questions regarding esthetics and function of the restorations.

RESULTS

The implant survival rate after 3 years was 81.25%. BOP and CAL around SDIs of GAgP patients were significantly higher than in periodontally healthy subjects (P = .01) throughout the follow-up. CAL around the teeth of GAgP patients was significantly greater during the follow-up than around the teeth of periodontal healthy subjects (P = .02). The PI and BOP between the teeth and implants showed no statistical significant difference. The mean PD at teeth was 0.4 mm greater than at implants. Implants showed significantly increased attachment loss than teeth (P = .01). The overall mean satisfaction of visual analogue scale was 12.8 ± 1.45.

CONCLUSION

This short-term follow-up study indicates SDIs remain functionally stable in the posterior jaws of treated GAgP patients.

Posterior atrophic jaws rehabilitated with prostheses supported by 6-mm-long 4-mm-wide implants or by longer implants in augmented bone. Five-year post-loading results from a within-person randomised controlled trial

PURPOSE

To evaluate whether 6-mm-long by 4-mm-wide dental implants could be an alternative to implants at least 10-mm long placed in bone augmented with bone substitutes in posterior atrophic jaws.

MATERIALS AND METHODS

A total of 20 patients with bilateral atrophic mandibles and 20 patients with bilateral atrophic maxillae, having 5 to 7 mm of bone height below the maxillary sinus or 6 to 8 mm above the mandibular canal, had their sides of the jaws randomly allocated according to a split-mouth design. They were allocated to receive one to three 6-mm-long and 4-mm-wide implants, or implants at least 10-mm long in augmented bone by two different surgeons in different centres. Mandibles were vertically augmented with interpositional equine bone blocks and resorbable barriers, and implants were placed 3 months later. Maxillary sinuses were augmented with particulated porcine bone via a lateral window and implants were placed simultaneously. All implants were submerged and loaded, after 4 months, with provisional prostheses. Four months later, definitive prostheses were delivered. Outcome measures were prosthesis and implant failures, any complication and radiographic peri-implant marginal bone level changes. The follow-up was 5 years after loading for all patients.

RESULTS

Eight patients (five treated in mandibles and three in maxillae) dropped out before the 5-year post-loading follow-up. Four short implants (two maxillary and two mandibular) affected by peri-implantitis failed together with their prostheses versus three mandibular prostheses which could not be placed on implants at least 10-mm long due to graft failures; one was associated with the loss of three implants because of infection. There were no statistically significant differences in implant (P = 1.0) and prosthesis failures (P = 1.0). In total, 19 complications occurred in 14 patients at augmented sites versus five complications in four patients with 6-mm-long implants (P = 0.118). More complications occurred at grafted sites both in mandibles (P = 0.727), and maxillae (P = 0.063), although the differences were not statistically significant. In mandibles, patients with 6-mm-long implants lost an average of 1.34 ± 0.35 mm of peri-implant bone at 5 years versus 2.11 ± 0.59 mm in patients with implants at least 10-mm long. The difference was statistically significant (mean difference = 0.77 ± 0.70 mm; 95% CI: 0.32 to 1.21 mm; P = 0.003). In maxillae, patients with 6-mm-long implants lost an average of 1.52 ± 0.47 mm of peri-implant bone at 5 years versus 1.85 ± 0.51 mm in patients with implants at least 10-mm long. The difference was statistically significant (mean difference = 0.33 ± 0.36 mm; 95% CI: 0.14 to 0.53 mm; P = 0.002).

CONCLUSIONS

Results at 5 years after loading indicate that 6-mm-long implants with a conventional diameter of 4 mm achieved similar results to longer implants placed in augmented bone. Short implants might be a preferable choice to bone augmentation, especially in posterior mandibles since the treatment was faster, cheaper and associated with less morbidity. However, 10-year post-loading data are necessary before making reliable recommendations.

Single crowns in the resorbed posterior maxilla supported by either 11-mm implants combined with sinus floor elevation or 6-mm implants:A 5-year randomised controlled trial

PURPOSE

To assess the clinical performance of single crowns in the posterior maxilla supported by either 11-mm-long implants combined with maxillary sinus floor elevation surgery or 6-mm-long implants during a 5-year follow-up period.

MATERIALS AND METHODS

A total of 38 consecutive patients, missing a premolar or a molar in the posterior maxilla and residual bone height underneath the maxillary sinus between 6 to 8 mm, were included. Subjects were randomly allocated to receive one 11-mm-long implant in combination with maxillary sinus floor augmentation or to receive one 6-mm-long implant without any grafting. A total of 41 implants (21 implants in 20 patients in the 6-mm group, and 20 implants in 18 patients in the 11-mm group) were placed and subsequently restored after 3 months with custom-made titanium abutments and cemented zirconia-based porcelain crowns. Both groups were followed by clinical (implant survival, restoration survival, complications, pocket probing depth and presence of plaque, calculus, bleeding and peri-implant inflammation) and radiographic examinations up to 5 years. The patient satisfaction was scored before treatment, and 12 and 60 months after functional implant restoration.

RESULTS

One patient (11-mm group) died before the 12-month evaluation and one patient (6-mm group) moved away. In addition, one patient in the 6-mm group lost one implant and no implants were lost in the 11-mm group. Two patients lost three restorations in the 6-mm group and no restorations were lost in the 11-mm group. From loading until the 60-month assessment, the mean marginal bone loss in the 6-mm group and the 11-mm group was 0.12 ± 0.36 mm and 0.14 ± 0.63 mm, respectively, without a significant difference (mean difference 0.02 mm; 95% CI -0.32 to 0.37; P = 0.884). Implant loss, restoration loss, screw loosening and porcelain chipping were defined as complications. Four patients in the 6-mm group and one patient in the 11-mm group had one or more complications, without a significant difference between the groups (95% CI 0.019 to 0.244; P = 0.198). The patient satisfaction was high in both groups (mean overall satisfaction in the 6-mm and the 11-mm groups was 9.4 ± 0.8 and 9.2 ± 0.8, respectively; mean difference 0.2; 95% CI -0.33 to 0.76; P = 0.434).

CONCLUSIONS

Reconstructions performed using an 11-mm implant combined with maxillary sinus floor augmentation or a 6-mm implant in the resorbed posterior maxilla are equally successful in supporting a single restoration over 5 years.

Five-year results from a randomised controlled trial comparing prostheses supported by 5-mm long implants or by longer implants in augmented bone in posterior atrophic edentulous jaws

PURPOSE

To evaluate whether 5-mm short dental implants could be an alternative to augmentation with anorganic bovine bone and placement of at least 10-mm long implants in posterior atrophic jaws.

MATERIALS AND METHODS

Fifteen patients with bilateral atrophic mandibles (5 to 7 mm bone height above the mandibular canal) and 15 patients with bilateral atrophic maxillae (4 to 6 mm bone height below the maxillary sinus), and bone thickness of at least 8 mm, were randomised according to a split-mouth design to receive one to three 5-mm short implants or at least 10-mm long implants in augmented bone. Mandibles were vertically augmented with interpositional bone blocks and maxillary sinuses with particulated bone via a lateral window. Implants were placed after 4 months, submerged and loaded, after another 4 months, with provisional prostheses. Four months later, definitive provisionally cemented prostheses were delivered. Outcome measures were: prosthesis and implant failures, any complication and peri-implant marginal bone level changes.

RESULTS

In five augmented mandibles the planned 10-mm long implants could not be placed and shorter implants (7.0 and 8.5 mm) had to be used instead. Five years after loading, six patients, five treated in the mandible and one in the maxilla, dropped out. Three prostheses (one mandibular and two maxillary) failed in the short-implant group versus none in the long-implant group. In mandibles one long implant failed versus two short implants in one patient. In maxillae one long implant failed versus three short implants in two patients. There were no statistically significant differences in implant (n = 26; P = 1.00, difference = 3.85%, 95% CI: -12.95% to 20.64%) and prosthetic (n = 26; P = 0.250, difference = 11.54%, 95% CI: -0.74% to 23.82%) failures. Eleven patients had 16 complications at short implants (one patient accounted for six complications) and 12 patients had 14 complications at long implants. There were no statistically significant differences in complications (n = 28; P = 1.00, difference = -3.57%, 95% CI: -30.65% to 23.51%). Five years after loading, patients with mandibular implants lost on average 1.72 mm at short implants and 2.10 mm at long implants of peri-implant marginal bone. This difference was statistically significant (difference = 0.37 ± 0.43 mm; 95% CI: 0.07 to 0.68 mm; P = 0.022). In maxillae, patients lost on average 1.31 mm at short implants and 1.79 mm at long implants. This difference was statistically significant (difference = 0.48 ± 0.43 mm; 95% CI: 0.22 to 0.74 mm; P = 0.002).

CONCLUSIONS

Five years after loading, 5-mm short implants achieved similar results to longer implants in augmented bone. The choice of short implants might be preferable to vertical bone augmentation, especially in mandibles, since the treatment is faster and cheaper.

Group 1 ITI Consensus Report: The influence of implant length and design and medications on clinical and patient-reported outcomes

OBJECTIVES

The aim of Working Group 1 was to address the influence of different local (implant length, diameter, and design) and systemic (medications) factors on clinical, radiographic, and patient-reported outcomes in implant dentistry. Focused questions on (a) short posterior dental implants (≤6 mm), (b) narrow diameter implants, (c) implant design (tapered compared to a non-tapered implant design), and (d) medication-related dental implant failures were addressed.

MATERIALS AND METHODS

Four systematic reviews were prepared in advance of the Consensus Conference and were discussed among the participants of Group 1. Consensus statements, clinical recommendations, and recommendations for future research were based on structured group discussions until consensus was reached among the entire expert Group 1. The statements were then presented and accepted following further discussion and modifications as required by the plenary.

RESULTS

Short implants (≤6 mm) revealed a survival rate ranging from 86.7% to 100%, whereas standard implant survival rate ranged from 95% to 100% with a follow-up from 1 to 5 years. Short implants demonstrated a higher variability and a higher Risk Ratio [RR: 1.24 (95% CI: 0.63, 2.44, p = 0.54)] for failure compared to standard implants. Narrow diameter implants (NDI) have been classified into three categories: Category 1: Implants with a diameter of <2.5 mm ("Mini-implants"); Category 2: Implants with a diameter of 2.5 mm to <3.3 mm; Category 3: Implants with a diameter of 3.3 mm to 3.5 mm. Mean survival rates were 94.7 ± 5%, 97.3 ± 5% and 97.7 ± 2.3% for category 1, 2 and 3. Tapered versus non-tapered implants demonstrated only insignificant differences regarding clinical, radiographic, and patient-reported outcomes. The intake of certain selective serotonin reuptake inhibitors and proton pump inhibitors is associated with a statistically significant increased implant failure rate. The intake of bisphosphonates related to the treatment of osteoporosis was not associated with an increased implant failure rate.

CONCLUSIONS

It is concluded that short implants (≤6 mm) are a valid option in situations of reduced bone height to avoid possible morbidity associated with augmentation procedures; however, they reveal a higher variability and lower predictability in survival rates. Narrow diameter implants with diameters of 2.5 mm and more demonstrated no difference in implant survival rates compared to standard diameter implants. In contrast, it is concluded that narrow diameter implants with diameters of less than 2.5 mm exhibited lower survival rates compared to standard diameter implants. It is further concluded that there are no differences between tapered versus non-tapered dental implants. Certain medications such as selective serotonin reuptake inhibitors and proton pump inhibitors showed an association with a higher implant failure rate.

Do short implants have similar survival rates compared to standard implants in posterior single crown?: A systematic review and meta-analysis

BACKGROUND

Short implants have been presented as an option for posterior rehabilitation in cases of poor bone height.

PURPOSE

To compare the survival rate of short implants and standard implants when used in posterior single crowns, in addition to reporting marginal bone loss, prosthetic failures, and surgical complications.

MATERIALS AND METHODS

Electronic search (PubMed, LILACS, Cochrane Library, Scopus, and Web of Science) and hand search were performed to identify all randomized controlled trials (RCTs) and controlled clinical trials (CCTs) that evaluated both short and standard implants in posterior single crowns.

RESULTS

Out of 345 articles identified by both electronic and hand search, four studies were selected (one CCT and three RCTs). The meta-analysis for the survival rate showed that there was no significant difference between the short implants and the standard ones (P = 1.00; RR:1.00; CI:0.97-1.03) performed with three RCTs for a one-year follow-up. The mean marginal bone loss ranged from 0.1 mm to 0.54 mm. Only one study reported the presence of prosthetic failures and surgical complications.

CONCLUSIONS

The survival rate of short implants was similar to the standard ones in posterior single crowns, for the one-year follow-up period. They also presented low surgical complications, prosthetic failures and marginal bone loss, being a predictable treatment for single rehabilitation in posterior tooth loss.

Immediate loading of fixed cross-arch prostheses supported by flapless-placed 5 mm or 11.5 mm long implants: 5-year results from a randomised controlled trial

PURPOSE

To compare the outcome of cross-arch prostheses supported either by 5 mm long or 11.5 mm long implants placed flapless and immediately restored with a metal-resin screw-retained cross-arch prostheses.

MATERIALS AND METHODS

Thirty patients with edentulous or to-be- rendered edentulous mandibles, and 30 with edentulous maxillas, having sufficient bone to allow the placement of four and six implants respectively, of at least 11.5 mm long, were randomised according to a parallel group design into two equal groups and received either 5 mm or 11.5 mm long implants at one centre. Implants had a diameter of 5 mm, were to be placed flapless, and with an insertion torque of at least 50 Ncm. Mandibles received four implants between the mental foramina. Implants were to be immediately loaded with metal-resin definitive prostheses the same day as implant placement. Patients were followed to 5 years post-loading and the outcome measures were: prosthesis and implant failures, complications, and peri-implant marginal bone level changes.

RESULTS

Four patients per group dropped out. Two prostheses were remade, one on short maxillary implants and one on long mandibular implants (difference in proportions = 0; 95% CI: -0.15 to 0.15; P = 1.000). Three patients lost six short implants vs three patients who lost four long implants (difference in proportions = 0; 95% CI: -0.19 to 0.19; P = 1.000). Four short implant patients were affected by complications vs five patients with long implants (difference in proportions = 0.04; 95% CI: -0.17 to 0.25; P = 1.000). There were no statistically significant differences for prostheses failures, implant failures and complications. Patients with mandibular short implants lost on average 0.22 mm of peri-implant bone at 5 years while patients with long mandibular implants lost 0.83 mm. Patients with maxillary short implants lost on average 0.30 mm of peri-implant bone at 5 years and patients with long maxillary implants lost 0.89 mm. Short implants showed less bone loss when compared with long implants and the differences up to 5 years were statistically significant both in maxillae (mean difference = 0.59 mm, 95% CI: 0.33 to 0.86 mm, P < .0001) and in mandibles (mean difference = 0.61 mm, 95% CI: 0.36 to 0.86 mm, P < 0.0001).

CONCLUSIONS

Flapless-placed 5 mm long implants achieved similar results as 11.5 mm long implants when supporting immediately loaded cross-arch prostheses both in maxillae and mandibles up to 5 years after loading. These results must be confirmed by other trials, and 10 years post-loading data is necessary before making reliable recommendations.

Short implants versus longer implants in vertically augmented posterior mandibles: result at 8 years after loading from a randomised controlled trial

PURPOSE

To evaluate whether 6.6-mm long implants could be a suitable alternative to longer implants placed in vertically augmented atrophic posterior mandibles.

MATERIALS AND METHODS

Sixty partially edentulous patients having 7 to 8 mm of residual crestal height and at least 5.5-mm thickness measured on computed tomography scans above the mandibular canal were randomly allocated according to a parallel-group design either to receive one to three submerged 6.6-mm long implants or 9.6-mm or longer implants (30 patients per group) placed in vertically augmented bone. Bone was augmented with interpositional anorganic bovine bone blocks fixed with titanium plates and covered with resorbable barriers. Grafts were left to heal for 5 months before implant placement. Four months after implant placement, provisional acrylic prostheses were delivered, replaced, after 4 months, by definitive metal-ceramic prostheses. Outcome measures were: prosthesis and implant failures, complications, and radiographic peri-implant marginal bone level changes. Patients were followed up to 8 years after loading.

RESULTS

Eight years after loading 12 patients dropped out, five from the short implant group and seven from the augmented group. The augmentation procedure failed in two patients and only 6.6-mm long implants could be inserted. There were no statistically significant differences for prosthesis and implant failures. Four prostheses failed in three patients of the short implant group versus three prostheses in three patients of the augmented group (Fisher exact test P = 1.000; difference in proportions = 0.01; 95% CI: -0.19 to 0.22). Five short implants failed in three patients versus three long implants in three patients (Fisher exact test P = 1.000; difference in proportions = 0.01; 95% CI: -0.19 to 0.22). There were statistically more complications in augmented patients (27 complications in 22 augmented patients versus 9 complications in 8 patients of the short implant group) (Fisher exact test P < 0.001; difference in proportions = 0.64; 95% CI: 0.38 to 0.79). Both groups gradually lost peri-implant bone in a statistically significant way. Eight years after loading, short implant group patients lost an average of 1.58 mm of peri-implant bone compared with 2.46 mm in the augmented group. Short implants experienced statistically significantly less bone loss (0.88 mm, 95% CI: 0.50 to 1.26 mm) than long implants.

CONCLUSIONS

When residual bone height over the mandibular canal is between 7 and 8 mm, 6.6-mm short implants are an interesting alternative to vertical augmentation in posterior atrophic mandibles since the treatment is faster, cheaper and associated with less morbidity.

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

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

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.

The inlay osteotome sinus augmentation technique for placing short implants simultaneously with reduced crestal bone height. A short-term follow-up

OBJECTIVE

To display an inlay technique of osteotome sinus floor elevation using a trephine combined with simultaneous short implant placement where the residual bone height (RBH) is less than 5 mm, as well as to evaluate the clinical effect in a prospective study.

MATERIAL AND METHODS

Fifty short implants were installed in 32 patients in the severely atrophic posterior maxilla immediately after sinus floor elevation between January 2010 and October 2012. An inlay osteotome sinus augmentation technique using a trephine was applied in the operation. The mean residual bone height adjacent to or beneath the sinus was 3.34 mm, ranging from 0.96 mm to 4.96 mm. It was rarely necessary to add graft material from bovine sources in this therapy. With the purpose of bite training and soft tissue reforming, the temporary crowns were fixed after 6 months. The final prostheses were restored 3 months later. The stability and osseointegration of the implants were clinically evaluated, also the bone height gain around the implants was measured.

RESULTS

The survival rate was 100% during the study period with this procedure. Each of the implants, loaded without pain or any subjective sensation, was clinically stable. No implants had detectable sinus membrane perforation during operation. The radiographic results demonstrated that the bone height gain was 5.38 mm after the surgery.

CONCLUSION

Based on the results and within the limits of the present study, it can be suggested that short implant placement in conjunction with this inlay osteotome sinus augmentation technique could yield predictable clinical results for edentulous posterior maxillary region with RBH less than 5 mm. Besides, from the clinical point of view, these techniques may reduce the indication for complex invasive procedures and simplify treatment in the posterior.