Dense cancellous bone as evidenced by a high HU value is predictive of late implant failure: a preliminary study

Objectives

The mechanism of late implant failure is unclear. This study examined the association between sclerosing cancellous bone images and the risk of late implant failures using multi-detector row computed tomography (CT) imaging data.

Methods

We performed a case–control study. The study group consisted of consecutive patients with implant failures treated at Kyushu Dental University between 2001 and 2016. CT data for late failure of 36 implants in 16 patients were available. The study cohort consisted of 16 patients with 36 late failed implants and 28 patients with 113 successful implants.

Results

The mean survival rate was 6.9 months for early implant failure, 76.6 months for late failure with marginal bone resorption, inflammation symptoms, and so-called peri-implantitis, and 95.0 months for late failure caused by implant fracture. The mean HU value for cases in the control group was 507 compared with 1231 for cases with late failure implants. Logistic regression was used for analysis. There were signs of high radiodensity of peri-implant cancellous bone when comparing adjusted radiodensity per 100 HU using CT data (OR 2.35; 95% CI 1.73–3.20; p < 0.001).

Conclusions

Within the limits of our study, the presence of high radiodensity and cancellous bone consolidation on imaging may be related to risk factors for late implant failure. Therefore, CT images of the host cancellous bone status for observation of visible sclerosis could be a useful diagnostic indicator for late implant failure.

     

Immediate implant placement in molar regions: risk factors for early failure

Objectives: To identify risk factors for early failure of immediately placed implants in molar regions associated with three bone regenerative techniques. Methods: Ninety‐two patients (44 women and 48 men; mean age 50 years, 35 smokers and 57 non‐smokers) in need of a single implant crown to replace a molar were included. After placing the implant, patients were randomized to one of three treatment groups for bone reconstruction of remaining periimplant defects: Autologous bone (AB) chips, Ossix membrane (OM) or a combination of AB chips and OM. The implant was submerged, and after 4 months of healing a re‐entry surgery was made to connect a healing abutment. Implants with a dehiscence on ≥2 sites (mesial/distal/oral/buccal) together with≥50% visible threads, were judged as failures. A series of simple logistic regression analyses were performed to identify risk factors for failure among the following independent variables: sex, jaw, smoking status, plaque, bleeding on probing, fistula, extraction reason, mean initial periimplant defect size, treatment group, implant length, buccal bone dehiscence (BBD), soft‐tissue dehiscence and infection. The identified risk factors entered a multiple logistic regression analysis. Results: Fifteen implants failed before abutment operation (13 explantations/two non‐osseointegrated). Treatment group had no impact on failure. Risk factors for failure were: Smoking >10 cigarettes/day (odds ratio [OR]=9.29, confidence interval [CI]=1.21–71.16), BBD (OR=11.43, CI=1.34–97.74) and infection (OR=36.7, CI=2.75–489.31). Conclusions: Implants placed immediately after extraction of a molar were associated with a high risk for failure at abutment operation. There was no difference in failure rate between three bone reconstructive techniques. To cite this article:
Urban T, Kostopoulos L, Wenzel A. Immediate implant placement in molar regions: risk factors for early failure.
Clin. Oral Impl. Res. 23 , 2012; 220–227.
doi: 10.1111/j.1600‐0501.2011.02167.x     

Postoperative infections after dental implant placement: Variables associated with increased risk of failure

1 Background

Wound infections after dental implant placement are a rare finding that might lead to early implant failure. However, the available information on this topic is scarce.

2 Methods

This retrospective cohort study was conducted to determine factors that may increase the failure rate of dental implants that presented a postoperative infection during the osseointegration period. Postoperative infections were defined as the presence of pus or fistula in the surgical area, with pain or tenderness, swelling, redness, and heat or fever, before prosthetic loading. A bivariate and multivariate analysis of the data using Cox proportional‐hazards regression was performed to detect prognostic factors for implant failure in patients that suffer infections.

3 Results

The patient‐based prevalence of postoperative infections after implant placement was 2.80% (95% confidence interval (95%CI): 2.04% to 3.83%). Thirty‐three out of 37 (89.19%) patients with infections had to be surgically retreated because of antibiotic failure and 65% of the infected implants were removed. The bivariate analysis showed a significant association between implant failure and the collar surface (HR: 3.12; 95% CI: 1.16 to 8.41; P = 0.014). Cox proportional‐hazards regression indicated that rough‐surfaced collars increased 2.35 times the likelihood of failure (95% CI: 0.87 to 6.37; P = 0.071).

4 Conclusions

The survival of implants placed in the maxilla, with smooth collar, and late‐onset of infection was higher than those placed in the mandible, with a rough collar and early onset of infection. In general, signs of infection after dental implant placement compromises the survival rate of the affected fixtures.     

Influence of MMP-8 promoter polymorphism in early osseointegrated implant failure

Objective

Dental implants consist in the treatment of choice to replace tooth loss. The knowledge that implant loss tends to cluster in subsets of individuals may indicate that host immuneinflammatory response is influenced by genetic factors. In fact, genetic polymorphisms influence the osseointegration process. The objective of this study was investigate the possible relationship between C-799T polymorphism in matrix metalloproteinase 8 (MMP-8) gene and early implant failure in nonsmoker patients.

Methods and materials

Subjects were divided into two groups: control group (100 patients with one or more healthy implants) and test group (80 patients that had suffered one or more early implant failures). Genomic DNA from oral mucosa was amplified by PCR and analyzed by restriction endonucleases. The significance of the differences in observed frequencies of polymorphisms was assessed by Chi-square.

Results

Statistical analysis shows that in the MMP-8 gene, the T allele in 76.25% in the test group and the T/T genotype, 63.75% in the same group, may predispose to early loss of implants osseointegrated.

Conclusion

These results suggest that polymorphism in the promoter region of MMP-8 gene is associated with early implant failure. This polymorphism can be a genetic marker to risk of implant loss.

Clinical relevance

The determination of this genetic pattern in osseointegration would enable the identification of individuals at higher risk to loss implant. Thus, genetic markers will be identified, contributing to an appropriate preoperative selection and preparation of strategies for prevention and therapy individualized to modulate the genetic markers and increase the success rate of treatments.     

Occurrence of Progressive Bone Loss Around Anodized Surface Implants and Resorbable Blasting Media Implants: A Retrospective Cohort Study

Background: This study evaluates occurrence of progressive bone loss (PBL) around implants with different implant surfaces. Methods: Retrospective examination of 2,517 implants was performed in 903 patients, including 1,147 anodized‐surface implants in 454 patients and 1,370 resorbable blasting media (RBM)‐surface implants in 449 patients, which were placed from January 2006 to December 2010. Through regular check‐up radiographs and records, presence of PBL (up to >50% of fixture length) was investigated. Implant removal for any reason was regarded a failure. Results: In total, 2,186 implants (979 anodized implants and 1,207 RBM implants) in 793 patients were included in this study. PBL was more frequently observed among anodized implants (n = 36 in 21 patients; 4%) than among RBM implants (n = 19 in 14 patients; 2%), and this difference was statistically significant (P <0.001). Occurrence of PBL was significantly influenced by surface modification and implant diameter (odds ratio [OR] of anodized surface = 4.40, 95% confidence interval [CI] = 1.78 to 10.89, P = 0.001; OR of wide implants = 9.62, 95% CI = 1.13 to 81.68, P = 0.038; determined by mixed‐effects logistic regression analysis with random patient effect). However, total survival rate was significantly influenced by implant diameter and not by surface modification (P = 0.019), although effect of implant diameter was observed to be significant on anodized implants (P = 0.030). Conclusion: Implant surface modification and implant diameter are significantly associated with occurrence of PBL.     

Impact of different placement depths on the crestal bone level of immediate versus delayed placed platform-switched implants

Purpose

The preservation of peri-implant bone is one requirement for long-term success of dental implants. The purpose of this study was to evaluate the impact of subcrestal placement on the crestal bone level of immediate versus delayed placed implants after loading.

Early complete failures of fixed implant-supported prostheses in the edentulous maxilla: a 3-year analysis of 17 consecutive cluster failure patients

Background Clusters of implant failures in the edentulous maxilla seem to occur in some patients. To create groups for analysis with higher numbers of these patients implies large original groups for inclusion. Purpose The aim of this study was to retrospectively describe and compare a group of “cluster failure patients” with randomly selected patients treated in the edentulous maxilla. Materials and Methods From a group of 1,267 consecutively treated patients in one clinic, all patients presenting failing fixed implant‐supported prostheses within the first 3 years of follow‐up were included. All patients were treated with turned titanium implants using two‐stage surgery. A control group of equal number of patients were created for comparison. Data on patients were retrospectively retrieved from their records, and compared. Results Seventeen patients (1.3%) met the inclusion criteria in the entire group. The bone resorption index revealed less bone quantity in the study group (p < .05) during implant placement, but there was no difference regarding primary implant stability at first‐stage surgery. The distribution of short and long implants showed relatively higher number of short implants in the study group (p < .05), and more patients had a presurgical discussion on the risk of implant failure prior to treatment in this group (p < .05). Only 5 out of 102 implants (4.9%) were lost before prosthesis placement as compared to 38 and 25 lost implants during the following two years in the study group. Smoking habits and signs of bone loss related to periodontitis in the lower dentition were more frequent in the study group, but did not reach a significant level (p > .05). Conclusion The results indicate that bone quantity, reflected in fixture length, has a significant impact on increased implant failure risk. Other factors of interest as predictors for implant failures could be smoking habits and also possibly signs of periodontitis in the opposing dentition.     

Smoking interferes with the prognosis of dental implant treatment: a systematic review and meta-analysis

AIM: This systematic literature review was performed to investigate if smoking interferes with the prognosis of implants with and without accompanying augmentation procedures compared with non-smokers. METHODS: A systematic electronic and handsearch (articles published between 1989 and 2005; English and German language; search terms "dental or oral implants and smoking"; "dental or oral implants and tobacco") was performed to identify publications providing numbers of failed implants, related to the numbers of smokers and non-smokers for meta-analysis. Publications providing statistically examined data of implant failures or biologic complications among smokers compared with non-smokers were included for systematic review. RESULTS: Of 139 publications identified, 29 were considered for meta-analysis and 35 for systematic review. Meta-analysis revealed a significantly enhanced risk for implant failure among smokers [implant-related odds ratio (OR) 2.25, confidence interval (CI(95%)) 1.96-2.59; patient-related OR 2.64; CI(95%) 1.70-4.09] compared with non-smokers, and for smokers receiving implants with accompanying augmentation procedures (OR 3.61; CI(95%) 2.26-5.77, implant related). The systematic review indicated significantly enhanced risks of biologic complications among smokers. Five studies revealed no significant impact of smoking on prognosis of implants with particle-blasted, acid-etched or anodic oxidized surfaces. CONCLUSION: Smoking is a significant risk factor for dental implant therapy and augmentation procedures accompanying implantations.     

Long-term cumulative survival and mechanical complications of single-tooth Ankylos Implants: focus on the abutment neck fractures

PURPOSE

To evaluate the cumulative survival rate (CSR) and mechanical complications of single-tooth Ankylos® implants.

MATERIALS AND METHODS

This was a retrospective clinical study that analyzed 450 single Ankylos® implants installed in 275 patients between December 2005 and December 2012. The main outcomes were survival results CSR and implant failure) and mechanical complications (screw loosening, fracture, and cumulative fracture rate [CFR]). The main outcomes were analyzed according to age, sex, implant length or diameter, bone graft, arch, and position.

RESULTS

The 8-year CSR was 96.9%. Thirteen (2.9%) implants failed because of early osseointegration failure in 3, marginal bone loss in 6, and abutment fracture in 4. Screw loosening occurred in 10 implants (2.2%), and 10 abutment fractures occurred. All abutment fractures were located in the neck, and concurrent screw fractures were observed. The CSR and rate of screw loosening did not differ significantly according to factors. The CFR was higher in middle-aged patients (5.3% vs 0.0% in younger and older patients); for teeth in a molar position (5.8% vs 0.0% for premolar or 1.1% for anterior position); and for larger-diameter implants (4.5% for 4.5 mm and 6.7% for 5.5 mm diameter vs 0.5% for 3.5 mm diameter) (all P<.05).

CONCLUSION

The Ankylos® implant is suitable for single-tooth restoration in Koreans. However, relatively frequent abutment fractures (2.2%) were observed and some fractures resulted in implant failures. Middle-aged patients, the molar position, and a large implant diameter were associated with a high incidence of abutment fracture.     

Multicenter Randomized Clinical Trial: Early Loading of Implants in Maxillary Bone

Purpose: The aim of this study was to show prognostic equivalence between implant loading in the maxilla after 12 weeks versus 4 weeks. Materials and Methods: One hundred four patients, from four centers in this open‐labeled randomized multicenter prospective controlled clinical trial, were assigned to either 12 weeks or 4 weeks of unloaded healing. Two hundred sixty‐nine implants (sand blasted large‐grid, acid etched [SLA] surface, ≥4.1 mm diameter; ≥10 mm length) were inserted and evaluated during an individual 5‐year follow‐up. Primary outcome was implant success after 12 months; prognostic equivalence was characterized by a maximum difference of ±5% in implant failure rates. Results: Implant‐wise 1‐year failure rates were estimated 3.1% (5/163 implants) in the 4 weeks group versus 3.6% (4/112 implants) in the 12 weeks group (95% confidence interval [CI] for the difference ?3.2 –+4.2%); implant‐wise evaluation demonstrated statistically significant prognostic equivalence of 4 and 12 weeks loading. Patient‐wise 1‐year failure rates were estimated 6.7% (n = 4 patients) in the 4 weeks group versus 5.1% (n = 2 patients) in the 12 weeks group (95% CI for the difference ?9.6 –+6.5%). All implant failures occurred within the first 3 months of the individual observation period. Prior bone augmentation, underdimensioned drilling, bone quality, implant type, implant length, implant diameter, residual teeth, and fixing of the restoration did not reveal associations with the implant outcome: trial site, posterior jaw region, and splinting were associated with a higher failure rate. Resonance frequency analysis did not serve as a predictor of implant failures at the time of implant insertion. Conclusion: Loading of standard SLA implants in the maxilla 4 weeks versus 12 weeks after insertion resulted in statistically equivalent failure patterns within a 1‐year follow‐up period; nevertheless, the observed patient‐wise failure patterns of the interim analysis requires further understanding of patient‐individual aspects of the early loading concept.     

A prospective,multi‐center study assessing early loading with short implants in posterior regions. A 3‐year post‐loading follow‐up study

Background

Few prospective studies about early loading of short implant have been available and very little evidence exists on the outcomes longer than 3 years.

Purpose

To assess clinical and radiographic outcomes of 6 mm‐short implants placed in the posterior maxilla and mandible applying an early loading protocol.

Materials and methods

Ninety‐five short implants (6 mm‐short, Ø 4 mm) were placed in 45 subjects at 3 study sites, 2 or 3 implants per subject, using a one‐stage surgical procedure and loaded with a screw‐retained splinted fixed prosthesis 6 weeks later. Follow‐up took place at 6, 12, 24, and 36 months after loading. Marginal bone level changes, implant survival, clinical variables, and adverse events were assessed.

Results

The survival rate for all implants placed was 95.8%. From implant loading to 3 years follow‐up, mean marginal bone level changes were minimal (0.07 ± 0.49 mm) and the peri‐implant soft tissue status was healthy. No major technical or biological complications occurred except for the 4 early implant losses.

Conclusion

Three‐year data indicates that the use of splinted 6 mm‐short implants is a viable treatment in posterior regions with low marginal bone resorption. Early loading after 6 weeks should be taken cautiously in patients with known risk factors.     

Outcomes of implants and restorations placed in general dental practices: A retrospective study by the Practitioners Engaged in Applied Research and Learning (PEARL) Network

ObjectivesThe authors conducted a study to determine the types, outcomes, risk factors and esthetic assessment of implants and their restorations placed in the general practices of a practice-based research network.MethodsAll patients who visited network practices three to five years previously and underwent placement of an implant and restoration within the practice were invited to enroll. Practitioner-investigators (P-Is) recorded the status of the implant and restoration, characteristics of the implant site and restoration, presence of peri-implant pathology and an esthetic assessment by the P-I and patient. The P-Is classified implants as failures if the original implant was missing or had been replaced, the implant was mobile or elicited pain on percussion, there was overt clinical or radiographic evidence of pathology or excessive bone loss (> 0.2 millimeter per year after an initial bone loss of 2 mm). They classified restorations as failures if they had been replaced or if there was abutment or restoration fracture.ResultsThe authors enrolled 922 implants and patients from 87 practices, with a mean (standard deviation) follow-up of 4.2 (0.6) years. Of the 920 implants for which complete data records were available, 64 (7.0 percent) were classified as failures when excessive bone loss was excluded from the analysis. When excessive bone loss was included, 172 implants (18.7 percent) were classified as failures. According to the results of univariate analysis, a history of severe periodontitis, sites with preexisting inflammation or type IV bone, cases of immediate implant placement and placement in the incisor or canine region were associated with implant failure. According to the results of multivariate analysis, sites with preexisting inflammation (odds ratio [OR] = 2.17; 95 percent confidence interval [CI], 1.41-3.34]) or type IV bone (OR = 1.99; 95 percent CI, 1.12-3.55) were associated with a greater risk of implant failure. Of the 908 surviving implants, 20 (2.2 percent) had restorations replaced or judged as needing to be replaced. The majority of P-Is and patients were satisfied with the esthetic outcomes for both the implant and restoration.ConclusionsThese results suggest that implant survival and success rates in general dental practices may be lower than those reported in studies conducted in academic or specialty settings.Practical ImplicationsThe results of this study, generated in the private general practice setting, add to the evidence base to facilitate implant treatment planning.     

Narrow‐ and regular‐diameter implants in the posterior region of the jaws to support single crowns: A 3‐year split‐mouth randomized clinical trial

Objectives

The objective of this 3‐year split‐mouth randomized controlled clinical study was to compare narrow‐diameter implants (NDIs) to regular‐diameter implants (RDIs) in the posterior region of the jaws (premolars and molars) in regards to (i) the marginal bone level (MBL) and (ii) implant and prosthesis survival and success rates.

Material and Methods

A total of 22 patients were included in the study. Each patient received at least one implant of each diameter (Ø3.3 and Ø4.1 mm), placed either in the maxilla or mandible to support single crowns. A total 44 implants (22 NDIs and 22 RDIs) were placed and included in the study. Twenty‐one implants were placed in the premolar, whereas 23 were placed in molar areas. Radiographic evaluations to access the MBL were performed immediately after implant placement, 1 and 3 years after implant loading. Peri‐implant clinical variables including probing pocket depth (PPD) and bleeding on probing (BoP) were obtained after crown delivery, 1 and 3 years after loading. Furthermore, the survival and success rates of the implants and prosthesis were also evaluated.

Results

Twenty patients were able to complete the study. There was no statistically significant difference regarding MBL between groups at implant placement (p = .084), 1‐year (p = .794) and 3‐year (p = .598) time intervals. The mean peri‐implant bone loss at 3‐year follow‐up was ?0.58 ± 0.39 mm (95% CI: ?0.751 to ?0.409) and ?0.53 ± 0.46 mm (95% CI: ?0.731 to ?0.329) for NDIs and RDIs, respectively. BoP was present at 15% and 10% of NDIs and RDIs, respectively, at 3‐year follow‐up. PPD >5 mm was observed in 5% and 0% of the implants of NDIs and RDIs, respectively, at 3‐year follow‐up. At the 3‐year examination, the implant success rates were in the NDIs and RDIs sites, respectively, 95% and 100%. The corresponding values for prosthesis success rates were 90% for NDIs and 95% for RDIs.

Conclusion

The present study demonstrated that NDIs placed to support single crowns in the posterior region did not differ to RDIs in regards to MBL, implant survival, and success rates.     

Influence of smoking on osseointegrated implant failure: a meta-analysis

The aim of this study was to examine the influence of smoking on osseointegrated implant failure by performing a meta-analysis. A computerized literature search using PubMed database (in English) and Japana Centra Revuo Medicina (in Japanese) was carried out to identify all relevant studies. Among 175 studies identified and chosen for detailed review, 19 were appropriate for inclusion in our meta-analysis. When smokers were compared with non-smokers, odds ratio (OR) for osseointegrated implant failure was significantly elevated (OR 2.17, 95% confidence intervals (CI), 1.67-2.83). Seven studies were appropriate to examine the influence of intra-oral location (maxillary arch vs. mandibular arch) of implant failure on smoking. The OR for implant failure occurring in the maxillary arch was significantly elevated (OR 2.06, 95% CI, 1.61-2.65), whereas the OR in the mandibular arch did not demonstrate a significant increased risk associated with smoking (OR 1.32, 95% CI, 0.72-2.4). Our meta-analysis revealed a significant relationship between smoking and the risk of osseointegrated implant failure, more particularly those implants located in the maxillary arch.     

Time dependent failure rate and marginal bone loss of implant supported prostheses: a 15-year follow-up study

This study deals with 4971 implants (Brånemark system) installed in 1315 patients, either fully or partially edentulous, and followed from implant installation up to the last control. A predominance of female patients (61%) and a nearly equal number of upper and lower jaws characterised the study group. Patients were scheduled each 6–12 months for recall. The observation time varied from 0.5 to 15 years (mean 5.1). The whole cohort was split up into compromised (n=59) and non-compromised (n=1256) patients. The former are defined as grafted (autologous bone) and patients irradiated in the head and neck area. In the compromised patients 24 out of 59 patients (40.6%) showed failures, in whom 59 out of 310 (19%) implants failed. In the non-compromised patients, implant failures were observed in 11.6% of the patients, which corresponds to 5.9% of the installed implants, excluding iatrogenic failures. Failures were further divided chronologically into early (up to 1 year after abutment connection) and late failures. There were early implant failures in 12.5% of the compromised patients and in 3.4% of the others. Late implant failures occurred in 7.4 and 2% of the two patients groups, respectively. While gender did not affect the failure rate, implant lengths, corresponding to the available bone height did, since a 21.5% failure rate for the 7-mm implants contrasts with 4.1 and 3.8% for 13- and 15-mm implants, respectively. Early as well as annual late failures are more frequently found in the maxilla. Implant fractures only occurred in the fixed (both partial and full) prosthesis group but never surpassed the 0.2% annual level. Marginal bone loss, exceeding the third screw thread occurred in 1.8% of the implants at the last control. It appears that this type of implant configuration offers a high long-term predictability. Failures occur before, at or during the first year after abutment connection and in very short implants. Marginal bone as a whole is very stable over the years.     

Early implant failure. Prognostic capacity of Periotest: retrospective study of a large sample

Objectives: The objectives of this study were to determine the accuracy of Periotest^® to monitor primary implant stability at first‐stage surgery, to identify by multivariate analysis the variables associated with early implant failure and to compare Periotest^® with radiographic study in the diagnosis of implant stability at second‐stage surgery (during osseointegration period). Material and methods: A 10‐year retrospective study was conducted on 1084 Brånemark^® implants placed in 316 patients. Clinical variables, implant diameter and length, Periotest^® values (PTVs) and radiological variables were analyzed in bivariate and multivariate studies in order to determine their influence on early implant failure. Results: After examination of the sensitivity and specificity values obtained for different PTV cutoff points, a cutoff PTV of ?2 was selected (84% sensitivity and 39% specificity). In the bivariate analysis, early failure was significantly related to smoking habits, implant location, bone type, implant features and PTVs (?2 and ≥?2). In the final multiple logistic model, only age (odds ratio (OR)=4.53; 95% confidence interval (CI), 1.34–15.27), smoking habits (OR=2.5; 95% CI, 1.3–4.79), bone type (OR=1.93; 95% CI, 1.01–3.7) and PTV at first surgery (OR=3.01; 95% CI, 1.5–6.02) were independently related to early failure. Conclusions: The Periotest^® (with ?2 cutoff) at first surgery offers high sensitivity in the prognosis of early implant loss and shows a greater capacity to evaluate stability during the osseointegration period compared with radiographic study.     

A comparison of implant complications and failures between the maxilla and the mandible

Statement of problem

Identifying factors that affect the clinical outcomes of implant therapy is important.

Interventions for Dental Implant Placement in Atrophic Edentulous Mandibles: Vertical Bone Augmentation and Alternative Treatments. A Meta‐Analysis of Randomized Clinical Trials

Background: The purpose of the current study is to assess which vertical bone augmentation techniques are most effective for restoring atrophic posterior areas of the mandible with dental implants and compare these procedures with alternative treatments. Methods: Electronic literature searches in PubMed (MEDLINE), Ovid, and the Cochrane Library were conducted to identify all relevant articles published up to July 1, 2015. Eligibility was based on inclusion criteria, and quality assessments were conducted. The primary outcome variables were implant and prosthetic failure. After data extraction, meta‐analyses were performed. Results: Out of 527 potentially eligible papers, 14 randomized clinical trials were included. Out of these 14 studies, four trials assessed short implants (5 to 8 mm) as an alternative to vertical bone augmentation in sites with a residual ridge height of 5 to 8 mm. No statistically significant differences were found in implant (odds ratio [OR]: 1.02; 95% confidence interval [CI]: 0.31 to 3.31; P = 0.98; I²: 0%) or prosthetic failure (OR: 0.64; 95% CI: 0.21 to 1.96; P = 0.43; I²: 0%) after 12 months of loading. However, complications at treated sites increased with the augmentation procedures (OR: 8.33; 95% CI: 3.85 to 20.0; P <0.001; I²: 0%). There was no evidence of any vertical augmentation procedure being of greater benefit than any other for the primary outcomes (implant and prosthetic failure). Conclusions: Short implants in the posterior area of the mandible seem to be preferable to vertical augmentation procedures, which present similar implant and prosthetic failure rates but greater morbidity. All the vertical augmentation technique comparisons showed similar intergroup results.     

Reconstruction of the atrophic edentulous maxilla with free iliac crest grafts and implants: a 3-year report of a prospective clinical study

Purpose: The purpose of this study was to perform a longitudinal follow-up study of implant stability in grafted maxillae with the aid of clinical, radiological, and resonance frequency analysis (RFA) parameters. Materials and Methods: The atrophic edentulous maxillae in 29 patients were reconstructed with free iliac crest grafts using onlay/inlay or interpositional grafting techniques. The endpoint of the resorption pattern in the maxilla determined the grafting technique used. Endosteal implants were placed after 6 months of bone-graft healing. Implant stability was measured four times using RFA: when the implants were placed, after 6 to 8 months of healing, after 6 months and 3 years of bridge loading. Individual checkups were performed at the two later RFA registrations after removal of the supraconstructions (Procera® Implant Bridge, Nobel Biocare AB, Göteborg, Sweden). Radiological follow up of marginal bone level was performed annually. Results: Twenty-five patients remained for the follow-up period. A total of 192 implants were placed and with a survival rate of 90% at the 3-year follow up. Women and an implant position with a class 6 resorption prior to reconstruction were factors with significant increased risk for implant failure (multivariate logistic regression). Twelve of the 20 failed implants were lost before loading (early failures). The change in the marginal bone level was 0.3 ± 0.3 mm between baseline (bridge delivery) and the 3-year follow up. The implant stability quotient (ISQ) value for all implants differed significantly between abutment connection (60.2 ± 7.3) and after 6 months of bridge loading (62.5 ± 5.5) (Wilcoxon signed ranks test for paired data, p=.05) but were nonsignificant between 6 months of bridge loading and 3 years of bridge loading (61.8 ± 5.5). There was a significant difference between successful and failed implants when the ISQ values were compared for individual implants at placement (Mann-Whitney U test, p=.004). All 25 patients were provided with fixed implant bridges at the time of the 3-year follow up. Conclusion: This clinical follow up using radiological examinations and RFA measurements indicates a predictable and stable long-term result for patients with atrophic edentulous maxillae reconstructed with autogenous bone and with delayed placement of endosteal implants. The ISQ value at the time of placement can probably serve as an indicator of level of risk for implant failure.