Reasons for failures of oral implants

This study reviews the literature regarding the factors contributing to failures of dental implants. An electronic search was undertaken including papers from 2004 onwards. The titles and abstracts from these results were read to identify studies within the selection criteria. All reference lists of the selected studies were then hand-searched, this time without time restrictions. A narrative review discussed some findings from the first two parts where separate data from non-comparative studies may have indicated conclusions different from those possible to draw in the systematic analysis. It may be suggested that the following situations are correlated to increase the implant failure rate: a low insertion torque of implants that are planned to be immediately or early loaded, inexperienced surgeons inserting the implants, implant insertion in the maxilla, implant insertion in the posterior region of the jaws, implants in heavy smokers, implant insertion in bone qualities type III and IV, implant insertion in places with small bone volumes, use of shorter length implants, greater number of implants placed per patient, lack of initial implant stability, use of cylindrical (non-threaded) implants and prosthetic rehabilitation with implant-supported overdentures. Moreover, it may be suggested that the following situations may be correlated with an increase in the implant failure rate: use of the non-submerged technique, immediate loading, implant insertion in fresh extraction sockets, smaller diameter implants. Some recently published studies suggest that modern, moderately rough implants may present with similar results irrespective if placed in maxillas, in smoking patients or using only short implants.

Factors Influencing Early Dental Implant Failures

The purpose of the present study was to assess the influence of local and systemic factors on the occurrence of dental implant failures up to the second-stage surgery (abutment connection). This retrospective study is based on 2,670 patients who received 10,096 implants and were consecutively treated with implant-supported prostheses between 1980 and 2014 at 1 specialist clinic. Several anatomic-, patient-, health-, and implant-related factors were collected. Descriptive statistics were used to describe the patients and implants. Univariate and multivariate logistic regression models were used at the patient level as well as the implant level to evaluate the effect of explanatory variables on the failure of implants up to abutment connection. A generalized estimating equation method was used for the implant-level analysis to account for the fact that repeated observations (several implants) were available for a single patient. Overall, 642 implants (6.36%) failed, of which 176 (1.74%) in 139 patients were lost up to second-stage surgery. The distribution of implants in sites of different bone quantities and qualities was quite similar between implants lost up to and after abutment connection. Smoking and the intake of antidepressants were the statistically significant predictors in the multivariate model (ClinicalTrials.gov NCT02369562).

Initial and long-term crestal bone responses to modern dental implants

Successful osseointegration is the result of a controlled foreign body reaction to dental implants. Osseointegrated implants have demonstrated excellent long-term survivability, although they may be subject to limited marginal bone loss. Marginal bone loss during the first few years after implant placement seldom represents disease, but is instead the result of an adaptive bone response to surgical trauma and implant loading. It is not uncommon for implants with early marginal bone loss to enter a long-lasting state of bone stability. Extensive bone resorption after the first year is generally due to an exacerbation of adverse body reactions caused by non-optimal implant components, adverse surgery or prosthodontics and/or compromised patient factors. Disease in the form of peri-implantitis is a late complication that affects some implants with suppuration and rapid loss of crestal bone, and is probably caused by bacterial pathogens and immunological reactions. Unfortunately, the literature is not consistent with respect to the type or magnitude of clinical implant problems, including how they are defined and diagnosed. If the peri-implantitis diagnosis is confined to cases with infection, suppuration and significant bone loss, the frequency of the disease is relatively low, which is in sharp contrast to the frequencies reported with unrealistic definitions of peri-implantitis. We suggest that when modern implants are placed by properly trained individuals, only 1-2% of implants show true peri-implantitis during follow-up periods of 10 years or more. Peri-implantitis must be separated from the initial and self-limiting marginal bone loss.

Intraoral Digital Impression Technique Compared to Conventional Impression Technique. A Randomized Clinical Trial

PURPOSE

To compare digital and conventional impression techniques in a randomized clinical trial; specifically, procedure times, patient-centered outcomes, and clinical evaluation of the restorations.

MATERIALS AND METHODS

Forty-two patients in need of tooth-supported single crowns and/or fixed partial prostheses up to six units were randomly allocated to one of the impression techniques. The procedure times, dentists' and patients' assessments using a visual analog scale (VAS), and clinical evaluation of the restorations were compared between the two groups.

RESULTS

The mean total procedure times for digital and conventional impression technique were 14:33 ± 5:27 and 20:42 ± 5:42, respectively (p < 0.0001). Mean impression times were 7:33 ± 3.37 and 11:33 ± 1.56, respectively (p < 0.0001). Mean VAS scores for the dentist's assessment of difficulty (0 to 100; very difficult = 100) were 24.00 ± 18.02 and 48.02 ± 21.21, respectively (p < 0.0001). Mean VAS scores for the patients' assessment of discomfort (0 to 100; very discomforting = 100) was 6.50 ± 5.87 and 44.86 ± 27.13, respectively (p < 0.0001). Occlusal contacts showed a better result for the digital technique.

CONCLUSION

The results of this study demonstrated that the digital technique was more efficient and convenient than the conventional impression technique.

Survival and Complications of Zygomatic Implants: An Updated Systematic Review

PURPOSE

To assess the survival rate of zygomatic implants (ZIs) and the prevalence of complications based on previously published studies.

MATERIALS AND METHODS

An electronic search of 3 databases was performed in December 2015 and was supplemented by manual searching. Clinical series of ZIs were included. Interval survival rate and cumulative survival rate (CSR) were calculated. The untransformed proportion of complications (sinusitis, soft tissue infection, paresthesia, oroantral fistulas) was calculated by considering the prevalence reported in the studies.

RESULTS

Sixty-eight studies were included, comprising 4,556 ZIs in 2,161 patients with 103 failures. The 12-year CSR was 95.21%. Most failures were detected within the 6-month postsurgical period. Studies (n = 26) that exclusively evaluated immediate loading showed a statistically lower ZI failure rate than studies (n = 34) evaluating delayed loading protocols (P = .003). Studies (n = 5) evaluating ZIs for the rehabilitation of patients after maxillary resections presented lower survival rates. The probability of presenting postoperative complications with ZIs was as follows: sinusitis, 2.4% (95% confidence interval [CI], 1.8-3.0); soft tissue infection, 2.0% (95% CI, 1.2-2.8); paresthesia, 1.0% (95% CI, 0.5-1.4); and oroantral fistulas, 0.4% (95% CI, 0.1-0.6). However, these numbers might be underestimated, because many studies failed to mention the prevalence of these complications.

CONCLUSION

ZIs present a high 12-year CSR, with most failures occurring at the early stages postoperatively. The main observed complication related to ZIs was sinusitis, which can appear several years after ZI installation surgery.

Bone Quality and Quantity and Dental Implant Failure: A Systematic Review and Meta-analysis

PURPOSE

The aim of this study was to test the null hypothesis that there is no difference in implant failure rates, marginal bone loss, and postoperative infection for implants inserted in bone with different qualities and quantities according to the classification of Lekholm and Zarb.

MATERIALS AND METHODS

An electronic search was undertaken in January 2015 for randomized and nonrandomized human clinical studies.

RESULTS

A total of 94 publications were included. When bone sites of different qualities were considered, the results suggested the following comparative implant failure rates: 1 > 2, 1 > 3, 3 > 2, 4 > 1, 4 > 2, and 4 > 3. Sensitivity analyses suggested that when implants inserted in bone qualities 1 and 2 and 1 and 3 were compared, oxidized and sandblasted/acid-etched surfaces showed a decrease in significant difference in failures compared with turned implants. The same is not true for failure of implants inserted in bone quality 4 compared to failure of implants in all other bone qualities. When bone sites of different quantities were considered, the following comparative implant failure rates were observed: A > B, A > C, A < D, B < C, B < D, C < D, E > A, E > B, E > C, E > D. Due to insufficient information, meta-analyses for the outcomes postoperative infection and marginal bone loss were not performed.

CONCLUSION

Sites with poorer bone quality and lack of bone volume may statistically affect implant failure rates. Implant surfaces may play a role in failure of implants in different bone qualities.

Diabetes and oral implant failure: a systematic review

The aim of this systematic review and meta-analysis was to investigate whether there are any effects of diabetes mellitus on implant failure rates, postoperative infections, and marginal bone loss. An electronic search without time or language restrictions was undertaken in March 2014. The present review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Eligibility criteria included clinical human studies. The search strategy resulted in 14 publications. The I (2) statistic was used to express the percentage of total variation across studies due to heterogeneity. The inverse variance method was used for the random effects model when heterogeneity was detected or for the fixed effects model when heterogeneity was not detected. The estimates of an intervention for dichotomous outcomes were expressed in risk ratio and in mean difference in millimeters for continuous outcomes, both with a 95% confidence interval. There was a statistically significant difference (p = .001; mean difference = 0.20, 95% confidence interval = 0.08, 0.31) between diabetic and non-diabetic patients concerning marginal bone loss, favoring non-diabetic patients. A meta-analysis was not possible for postoperative infections. The difference between the patients (diabetic vs. non-diabetic) did not significantly affect implant failure rates (p = .65), with a risk ratio of 1.07 (95% confidence interval = 0.80, 1.44). Studies are lacking that include both patient types, with larger sample sizes, and that report the outcome data separately for each group. The results of the present meta-analysis should be interpreted with caution because of the presence of uncontrolled confounding factors in the included studies.

Osteoradionecrosis of the jaws--a current overview--part 1: Physiopathology and risk and predisposing factors

PURPOSE

The aim of this paper is to explore the current theories about definition, classification, incidence and physiopathology of osteoradionecrosis (ORN) of the jaws. Moreover, it is discussed the predisposing and risk factors for the development of osteoradionecrosis based on the literature review.

DISCUSSION

Osteoradionecrosis is one of the most serious oral complications of head and neck cancer treatment. Osteoradionecrosis is a severe delayed radiation-induced injury, characterised by bone tissue necrosis and failure to heal. Osteoradionecrosis either stabilises or gradually worsens and is notoriously difficult to manage. The most widely accepted theory to explain its cause until recently was the theory of hypoxia, hypovascularity and hypocellularity. A new theory for the pathogenesis of osteoradionecrosis was proposed. The clinical presentations of osteoradionecrosis are pain, drainage and fistulation of the mucosa or skin that is related to exposed bone in an area that has been irradiated. The tumour size and location, radiation dose, local trauma, dental extractions, infection, immune defects and malnutrition can predispose its development.

CONCLUSIONS

A better understanding of risk factors for the development ORN and of the underlying pathophysiology may improve our ability to prevent this complication and help to improve the prognosis for those being treated for osteoradionecrosis.

1,454 mandibular fractures: a 3-year study in a hospital in Belo Horizonte, Brazil

OBJECTIVE

To analyze the mandibular fractures which presented over a 3-year period at an emergency hospital in Belo Horizonte, Brazil.

METHODS

The data collected included age, sex, aetiology, date of trauma, associated maxillofacial trauma, anatomic site of fracture, and treatment. The analysis involved descriptive statistics and the Pearson's chi-square, Bonferroni, Kolmogorov-Smirnov, Kruskal-Wallis and Mann-Whiney tests, and analysis of variance.

RESULTS

There were 1,454 mandibular fractures in 1,023 patients. Males of 20-29 years of age sustained the majority of fractures. Traffic accidents were the major causes of trauma, followed by violence and falls. A high incidence of fractures in women due to violence was observed. The condyle region was found to be the most common fracture site in the mandible. A surgical approach was performed in most cases. There were more accidents causing mandibular fractures on the weekends.

CONCLUSION

The individuals with mandibular fractures due to "traffic accidents" were younger than those due to "violence" and "falls". There was a significant statistical association between age and aetiology as well as between sex and aetiology of mandibular fractures.

A retrospective study on clinical and radiological outcomes of oral implants in patients followed up for a minimum of 20 years

BACKGROUND

Very long-term follow-up of oral implants is seldom reported in the literature.

PURPOSE

To assess oral implant failure rates and marginal bone loss (MBL) of patients followed up for a minimum of 20 years.

MATERIALS AND METHODS

Implants placed in patients followed up for 20+ years were included. Descriptive statistics, survival analyses, generalized estimating equations were performed. Three-hundred implants were randomly selected for MBL.

RESULTS

1,045 implants (227 patients) were included. Implant location, irradiation, and bruxism affected the implant survival rate. Thirty-five percent of the failures occurred within the first year after implantation, and another 26.8% in the second/third year. There was a cumulative survival rate of 87.8% after 36 years of follow-up. In the last radiological follow up, 35 implants (11.7%) had bone gain, and 35 implants (11.7%) presented at least 3 mm of MBL. Twenty-six out of 86 failed implants with available radiograms presented severe MBL in the last radiological register before implant failure.

CONCLUSIONS

Most of the implant failures occurred at the first few years after implantation, regardless of a very long follow up. MBL can be insignificant in long-term observations, but it may, nevertheless, be the cause of secondary failure of oral implants in some cases.

Survival and complications of zygomatic implants: a systematic review

PURPOSE

This systematic review attempted to answer the focused questions: "What is the survival rate of zygomatic implants (ZIs)?" and "What are the most common complications related to surgery of zygomatic implants?"

METHODS

An electronic search without date or language restrictions was undertaken in PubMed in March 2012. Titles and abstracts from these results (n = 123) were read for identifying studies that meet the eligibility criteria. Eligibility criteria included studies reporting clinical series of zygomatic implants (ZIs). Because of the scarcity of articles with high-level grades of evidence, all articles, including studies with few case reports, were considered for inclusion. All reference lists of the selected and review studies were hand-searched for additional papers that might meet the eligibility criteria. Simple case report articles were not included. Review articles without original data were excluded. Quantitative data extracted from the included studies that provided data for the period of failure of ZIs were used for the calculation of interval survival rate during each follow-up period and cumulative survival rate (CSR) over a 12-year period.

RESULTS

Thirty-seven studies were identified without repetition and five more studies were included by hand-searching, giving a total of 42; 12 evaluated the use of ZI applied with immediate function protocols and 3 for rehabilitating patients after maxillary resections for tumor ablations. These latter three studies showed smaller ZI success. Postoperative complications reported were as follows: 70 cases of sinusitis, 48 of soft tissue infection, 15 of paresthesia, and 17 cases of oroantral fistulas. However, this number may be underestimated, since most of the studies did not mention the presence or absence of these complications. Most ZI failures were detected at the abutment connection phase (6 months after the surgery of implant placement) or before. The CSR over a 12-year period was 96.7 %.

CONCLUSIONS

Despite the high survival rate observed, there is an impending need for conducting randomized controlled clinical trials to test the efficacy of these implants in comparison with the other techniques to treat the atrophic maxilla. Thus, the findings reported in the review must be interpreted with considerable caution. Moreover, more studies with longer follow-up periods involving adequate number of ZIs are needed. This will help to obtain a better understanding of the survival of ZIs in a long term. It is suggested that multicenter, randomized controlled clinical trials and longer clinical studies should be implemented in this area, before recommending routine use of ZIs for patients could be given. The placement of zygomatic implants requires very experienced surgeons because it is not risk free since delicate anatomic structures such as the orbita and brain may be involved.

Factors influencing the incidence of maxillofacial fractures

PURPOSE

Maxillofacial injuries occur in a significant proportion of trauma patients. Trauma causes considerable economic expense due to procedural costs, the time a patient is off work, and the associated loss of income. For these reasons, it is an important health and economic issue. The aim of this study is to discuss the factors that may influence the incidence of maxillofacial fractures. As it is necessary to determine trends to help guide the development of new methods of injury prevention, preventative measures are also discussed.

METHODS

An electronic search was undertaken in March 2011, including articles published between 1980 and 2011 with the terms "facial fractures" and "maxillofacial fractures" in the title. The texts of epidemiological studies were reviewed in order to identify factors that may influence the incidence of maxillofacial fractures.

RESULTS

From the selected articles, ten factors were identified: age, gender, geographic region and cultural aspects, socioeconomic status, temporal and climatic influence, use of alcohol and drugs, compliance with road traffic legislation, domestic violence, osteoporosis, and etiology of the maxillofacial trauma.

CONCLUSIONS

Care of injured patients should include not only management of the acute phase, but also combine preventive programs and interventional programs aimed at reducing the incidence of maxillofacial fractures. Therefore, there is a need to ensure strict compliance of traffic rules and regulations, implement improvement in automotive safety devices, organize prevention programs to minimize assaults, implement school education in alcohol abuse and handling potentially hostile situations (especially for men), improve protection during sporting activities, and legislate wearing of protective headgear in workers. Preventive strategies remain the cheapest way to reduce direct and indirect costs of the sequelae of trauma. Societal attitudes and behaviors must be modified before a significant reduction in the incidence of maxillofacial fractures will be seen.

Bruxism and dental implant treatment complications: a retrospective comparative study of 98 bruxer patients and a matched group

OBJECTIVES

To analyze the complications of dental implant treatment in a group of patients with bruxism in comparison with a matched group of non-bruxers.

MATERIAL AND METHODS

Patients being diagnosed as bruxers were identified within a group of patients consecutively treated with implant-supported prostheses at one specialist clinic, based on the most recent listed sign and symptoms of bruxism according to the International Classification of Sleep Disorders. A diagnostic grading system of "possible," "probable," and "definite" sleep or awake bruxism was used, according to a recent published international consensus. A case-control matching model was used to match the bruxers with a group of non-bruxers, based on five variables. Implant-, prosthetic-, and patient-related data were collected, as well as 14 mechanical complications, and compared between groups.

RESULTS

Ninety-eight of 2670 patients were identified as bruxers. The odds ratio of implant failure in bruxers in relation to non-bruxers was 2.71 (95% CI 1.25, 5.88). Considering the same number of patients with the same total number of implants equally distributed between groups, the bruxers group had a higher prevalence of mechanical complications in comparison with the non-bruxers group.

CONCLUSIONS

This study suggests that bruxism may significantly increase both the implant failure rate and the rate of mechanical and technical complications of implant-supported restorations. Other risk factors may also have influenced the results.

Dental implants in irradiated versus nonirradiated patients: A meta-analysis

The purpose of the present meta-analysis was to test the null hypothesis of no difference in dental implant failure rates, postoperative infection, and marginal bone loss for patients being rehabilitated by dental implants and being previously irradiated in the head and neck region versus nonirradiated patients against the alternative hypothesis of a difference. The study suggests that irradiation negatively affects the survival of implants, as well as the difference in implant location (maxilla vs mandible), but there is no statistically significant difference in survival when implants are inserted before or after 12 months after radiotherapy. The study failed to support the effectiveness of hyperbaric oxygen therapy in irradiated patients. It was observed that there was a tendency of lower survival rates of implants inserted in the patients submitted to higher irradiation doses. The results should be interpreted with caution because of the presence of uncontrolled confounding factors in the included studies.

Bruxism and dental implant failures: a multilevel mixed effects parametric survival analysis approach

Recent studies have suggested that the insertion of dental implants in patients being diagnosed with bruxism negatively affected the implant failure rates. The aim of the present study was to investigate the association between the bruxism and the risk of dental implant failure. This retrospective study is based on 2670 patients who received 10 096 implants at one specialist clinic. Implant- and patient-related data were collected. Descriptive statistics were used to describe the patients and implants. Multilevel mixed effects parametric survival analysis was used to test the association between bruxism and risk of implant failure adjusting for several potential confounders. Criteria from a recent international consensus (Lobbezoo et al., J Oral Rehabil, 40, 2013, 2) and from the International Classification of Sleep Disorders (International classification of sleep disorders, revised: diagnostic and coding manual, American Academy of Sleep Medicine, Chicago, 2014) were used to define and diagnose the condition. The number of implants with information available for all variables totalled 3549, placed in 994 patients, with 179 implants reported as failures. The implant failure rates were 13·0% (24/185) for bruxers and 4·6% (155/3364) for non-bruxers (P < 0·001). The statistical model showed that bruxism was a statistically significantly risk factor to implant failure (HR 3·396; 95% CI 1·314, 8·777; P = 0·012), as well as implant length, implant diameter, implant surface, bone quantity D in relation to quantity A, bone quality 4 in relation to quality 1 (Lekholm and Zarb classification), smoking and the intake of proton pump inhibitors. It is suggested that the bruxism may be associated with an increased risk of dental implant failure.

Analysis of risk factors for cluster behavior of dental implant failures

BACKGROUND

Some studies indicated that implant failures are commonly concentrated in few patients.

PURPOSE

To identify and analyze cluster behavior of dental implant failures among subjects of a retrospective study.

MATERIALS AND METHODS

This retrospective study included patients receiving at least three implants only. Patients presenting at least three implant failures were classified as presenting a cluster behavior. Univariate and multivariate logistic regression models and generalized estimating equations analysis evaluated the effect of explanatory variables on the cluster behavior.

RESULTS

There were 1406 patients with three or more implants (8337 implants, 592 failures). Sixty-seven (4.77%) patients presented cluster behavior, with 56.8% of all implant failures. The intake of antidepressants and bruxism were identified as potential negative factors exerting a statistically significant influence on a cluster behavior at the patient-level. The negative factors at the implant-level were turned implants, short implants, poor bone quality, age of the patient, the intake of medicaments to reduce the acid gastric production, smoking, and bruxism.

CONCLUSIONS

A cluster pattern among patients with implant failure is highly probable. Factors of interest as predictors for implant failures could be a number of systemic and local factors, although a direct causal relationship cannot be ascertained.

Tilted versus axially placed dental implants: a meta-analysis

OBJECTIVES

The purpose of the present review was to test the null hypothesis of no difference in the implant failure rate, marginal bone loss, and postoperative infection for patients being rehabilitated by tilted or by axially placed dental implants, against the alternative hypothesis of a difference.

METHODS

An electronic search without time or language restrictions was undertaken in July 2014. Eligibility criteria included clinical human studies, either randomised or not, interventional or observational. The estimates of an intervention were expressed in risk ratio (RR) and mean difference (MD) in millimetres.

RESULTS

The search strategy resulted in 44 publications. A total of 5029 dental implants were tilted (82 failures; 1.63%), and 5732 implants were axially placed (104 failures; 1.81%). The difference between the procedures did not significantly affect the implant failure rates (P=0.40), with a RR of 1.14 (95% CI 0.84-1.56). A statistically significant difference was found for implant failures when studies evaluating implants inserted in maxillae only were pooled (RR 1.70, 95% CI 1.05-2.74; P=0.03), the same not happening for the mandible (RR 0.77, 95% CI 0.39-1.52; P=0.45). There were no apparent significant effects of tilted dental implants on the occurrence of marginal bone loss (MD 0.03, 95% CI -0.03 to 0.08; P=0.32). Due to lack of satisfactory information, meta-analysis for the outcome 'postoperative infection' was not performed.

CONCLUSIONS

It is suggested that the differences in angulation of dental implants might not affect the implant survival or the marginal bone loss. The reliability and validity of the data collected and the potential for biases and confounding factors are some of the shortcomings of the present study.

CLINICAL SIGNIFICANCE

The question whether tilted implants are more at risk for failure than axially placed implants has received increasing attention in the last years. As the philosophies of treatment alter over time, a periodic review of the different concepts is necessary to refine techniques and eliminate unnecessary procedures. This would form a basis for optimum treatment.

Facial fractures: a 1-year retrospective study in a hospital in Belo Horizonte

A retrospective study was performed to assess facial fractures in patients treated at a public hospital in Belo Horizonte, in 2000. The data collected included age, gender, etiology, distribution of maxillofacial trauma considering day of the week and month, anatomic site of the fracture, and treatment. The analyses involved descriptive statistics and chi-squared test, Bonferroni test and analysis of variance. A total of 1,326 facial fractures were found in 911 patients. Most fractures occurred in adults with age ranging from 21 to 30 years. Men were more affected than women, with a male-female ratio of 4.69:1. Accidents causing facial fractures occurred predominantly on weekends. Bicycle and motorcycle accidents were the major cause of trauma, followed by interpersonal violence, automobile accidents, and falls. When the relation between the gender and the etiology of facial fractures was analyzed, a significant relation was noted between these variables (p < 0.001). There was also a relation between the patients' age and the site of the fractures (p = 0.0014). The mandible was found to be the most commonly fractured bone in the facial skeleton, followed by the zygomatic complex and the nose. A non-surgical approach was chosen in most cases. There were significant differences between the kind of treatment applied and the site of the fracture (p < 0.001).