Factors influencing the fracture of dental implants

Bruxism and direct and indirect restorations failure: A scoping review

OBJECTIVE

To analyze and present the relationship between bruxism and the failure of direct and indirect dental restorations.

METHODOLOGY

The reporting followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR). Human studies reporting on the failure of dental restorations in relation to bruxism were included.

SOURCES

MEDLINE (Ovid), Scopus and Pub Med databases were searched from 2012 to 2024. Additional hand searching was made using Google Scholar, and Scopus were utilized for snowball searching.

STUDY SELECTION

An initial systematic search was made of bruxism and dental restorations failures based on key terms using MeSH and other thesaurus terms appropriate for each database published between 2012 and 2024. Two reviewers screened ten articles using the established criteria for inclusion and exclusion, and a level of agreement of 90 % was established. The available literature on the frequency of studies of the relationship between Bruxism and failure of direct and indirect dental restorations and also identify gaps in the literature for further investigation.

CONCLUSIONS

There were 66 manuscripts for full-text evaluation. After further exclusion, 46 manuscripts were selected for data charting. The studies were on the relationship between bruxism and restorations failure: dental implants studies were 58.7 %; mixed restorations were 10.9 %; indirect restoration (Full Coverage Crowns and Fixed Partial Dentures) 15.2 %; indirect partial coverage restoration (inlays/onlays/overlays/crowns) 6.5 %; indirect restoration (veneers) 4.3 %; direct restoration also 4.3 %. The 87.5 % of the implant studies addressed the effects of bruxism on single implant restorations failure.

LIMITATIONS OF EVIDENCE

Most of the included studies were retrospective, with few prospective studies or clinical trials. However, Bruxism is a risk factor for the failure of direct and indirect restorations.

CLINICAL SIGNIFICANCE

Clinicians should be aware that direct and indirect restorations are at risk of failure in the presence of bruxism, with the exception of indirect monolithic Zirconia.

Retrospective analysis of dental implant fracture following loading: A retrospective clinical study

STATEMENT OF PROBLEM

Fracture of an osseointegrated implant (FOI) is a rare complication that occurs primarily after loading and may lead to other complications including failure or fracture of the implant-supported prosthesis. Risk factors for FOI are not well understood.

PURPOSE

The purpose of this retrospective clinical study was to determine the frequency of occurrence of FOI among participants treated with dental implants in an academic setting and to identify and analyze the possible risk indicators and contributing factors.

MATERIAL AND METHODS

A retrospective analysis was performed using dental records of participants who received dental implant treatment at the Faculty of Dentistry, University of Toronto, from January 1979 until January 2020, and experienced post-loading FOI. A systematic search of the dental records was conducted, and clinical situations with FOI were identified. Data related to patient factors, implant factors, and prosthesis factors were collected from the identified clinical situations with FOI. The data were analyzed to determine the incidence of FOI. A descriptive analysis was used to identify the possible risk indicators for FOI.

RESULTS

A total of 7712 implants had been placed at the Faculty of Dentistry, University of Toronto, from January 1979 until January 2020. During the 41-year period, a total of 27 fractured implants were identified. The incidence of FOI following loading was 0.35%. Overall, the mean ±standard deviation time between loading and occurrence of implant fracture was 10.6 ±7 years. Implant fractures occurred in 23 different study participants; 16 men, and 7 women, with a mean ±standard deviation age of 65.4 ±8.0 years at the time of FOI. Factors associated with implant fracture include narrow-diameter implants (≤3.75 mm), implants placed in posterior mandible (molar or premolar regions), presence of a long cantilever, and unfavorable implant design (such as the Tri-Channel design). Among the 27 fractured implants, 19 were removed, 6 were buried, and 2 were adjusted or smoothed and restored with a new prosthesis.

CONCLUSIONS

The incidence rate of FOI was very low, but might have been increased by an increased presence of predisposing risk factors.

Clinical and radiographic outcomes of mini-implant-retained maxillary and mandibular overdentures: a systematic review and meta-analysis

OBJECTIVE

To assess the clinical and radiographic outcomes of overdentures and their retaining dental mini-implants, based on a single-arm systematic literature review.

METHODS

Electronic search was undertaken in three databases, last updated in October 2023, plus manual search of journals. Cumulative implant survival rate (CSR) and the estimated marginal bone loss (MBL) under different follow-up times were calculated.

RESULTS

Thirty-nine studies were included, with 3,787 mini-implants supporting 1,026 overdentures (109 maxilla, 896 mandible) in 1,005 patients, with a mean follow-up of 28.1 ± 19.8 months (min-max 0.3-84.0). 202 mini-implants failed, after a mean of 9.4 ± 11.8 months (7-year CSR 91.4%). The implant survival was lower in the maxilla in comparison to the mandible (p < 0.001), lower for early/delayed-loaded in comparison to immediately-loaded implants (p = 0.005) and lower for 2-mini-implant in comparison to 4-mini-implant-retained mandibular overdenture (p < 0.001; Log-rank test). A high rate of transversal fracture of the prosthesis and wear of the attachment parts was observed. The estimated mean MBL gradually increased from 0.518 (≤ 6 months) to 1.260 mm (58.8-90 months). There was an estimated MBL increase of 0.011 mm per additional month of follow-up.

CONCLUSION

Although presenting a high 7-year CSR, mini-implant-retained overdentures may require frequent maintenance follow-ups, due to the high rate of technical complications. The estimated MBL of mini-implants over 80 months is low.

CLINICAL RELEVANCE

The ability to anticipate outcomes is an essential part of risk management in clinical practice. The findings reported herein set some recommendations and potential strategies for minimizing failures and complications commonly associated with this mini-implant-retained overdentures.

Occlusion and Biomechanical Risk Factors in Implant-Supported Full-Arch Fixed Dental Prostheses-Narrative Review

The biophysiological differences between teeth and dental implants and the issue of occlusal overload, although controversial, form the basis for the management of occlusion in implant-supported full-arch fixed dental prostheses (ISFAFDPs). Although there is currently a lack of scientific evidence on occlusal management, it is clear that the favorable prognosis of ISFAFDPs is linked to a correct understanding of the biomechanical principles involved. In the design of ISFAFDPs, the lack of proprioceptive feedback requires special attention to biomechanical factors: minimizing overloading complications and providing biomechanical stability are among the main goals of the occlusion. In ISFAFDPs, the occlusion must be decided on the basis of several factors that influence the loads on prosthesis and implants: each case must be evaluated individually and requires a personalized occlusion. The main aim of this narrative review is to provide an overview of the occlusal principles and materials that can be used in ISFAFDPs based on the data currently available in the literature. Practical clinical recommendations for the occlusion management of ISFAFDPs and a biomechanical risk score index to personalize implant-prosthetic treatment are proposed.

A Multicenter Study of Factors Related to Early Implant Failures-Part 1: Implant Materials and Surgical Techniques

BACKGROUND

Dental implant materials, designs as well as general concepts for surgical techniques have evolved during the last decades. It has been validated that primary stability followed by bone apposition around implants is crucial for implant survival as most implant failures occur during the first year. However, new implant materials and different micro and macro designs have improved implant survival in more challenging clinical conditions. Therefore, clinical research with large patient groups is needed to investigate the effects of different implant designs and surgical protocols with the aim to improve early implant outcomes.

PURPOSE

The purpose of the study is to investigate the clinical use of dental implant materials, designs, and surgical techniques related to early implant complications and failures.

MATERIALS AND METHODS

All patients who had received implant surgery in 2007 and 2017 at three specialist centers in Sweden were identified using charge codes. Data were retrieved from a dental record system as well as from digital and analog registries on implant surgeries. Information on anamnestic data, bone status, implant materials and designs, surgery techniques, and early implant failures and complications during the first year was compiled and analyzed. Descriptive statistics were used for comparison of the time cohorts. The data were statistically analyzed with a multivariable logistic regression model with a significance level of p < 0.05 using early implant failures and complications as the dependent variables.

RESULTS

For 2007, 799 patients with 2473 implants were identified. For 2017, 1076 patients with 2287 implants were identified. However, 74 (3.7%) patients were excluded, mainly due to lack of data. Differences were observed when comparing the two cohorts. In 2017, fewer preoperative antibiotics were prescribed, more incidences of exposed implant threads were reported, more non-submerged implant surgeries were performed, shorter implant lengths were used, more implants were placed in augmented bone, and tapered implants with a variable design were used. Implants of commercially pure titanium (CP Ti) Grades 1-4 with moderately and minimally rough surfaces were used in 2007, whereas CP Ti Grade 4 and alloy titanium zirconium (TiZr) with moderately rough surfaces were used in 2017. Significantly higher number of implant failures were reported in 2017 at the implant level: 56 (2.4%) in 2017 compared to 26 (1.1%) in 2007. Eleven variables were shown to increase the risk of failure including exposed implant threads OR 3.56 (1.60, 7.91) p = 0.0018 and increased number of implants per patients 1.26 (1.14, 1.39) p < 0.001 analyzed at the patient level. Nine variables were shown to increase the risk of early implant complications, including exposed implant threads OR 4.52 (2.60, 7.87) p < 0.001, sinus membrane perforations OR 8.14 (2.46, 26.93) p < 0.001, and no prescription of preoperative antibiotics OR 4.52 (2.60, 7.87) p < 0.001 analyzed at the patient level.

CONCLUSIONS

This study reports on changes in implant materials, designs, and surgical techniques between 2007 and 2017. Significantly higher numbers of implant failures and complications were reported in 2017. Factors related to early implant complications and failures were identified.

The Effect of Patient-associated Factors on Long-Term Survival of Dental Implants

Dental implant therapy has developed over the past half century to have documented successful outcomes in most patients who receive treatment. The long-term survival of dental implants depends upon a variety of factors including patient, surgeon, restorative dentist, and materials-related factors. The impact of patient-associated factors may impact significantly on the success of dental implants including diabetes mellitus, medications, smoking, parafunctional habits, oral hygiene, head and neck radiation, and the use of bisphosphonates, antiangiogenic, and antiresorptive medications.

Dental Implant Failure Risk in Patients with Bruxism-A Systematic Review and Meta-Analysis of the Literature

Background/Objectives: Recent research has indicated that placing dental implants in patients diagnosed with bruxism has led to higher rates of implant failure. This study aimed to provide more accurate knowledge about the relationship between bruxism and implant loss in patients (number, age, gender) with different numbers of implants and prosthetic restorations, considering the follow-up time, compared to non-bruxers. Methods: A systematic search was conducted in PubMed and Cochrane Library using the keyword combination "dental implant", "bruxism", and "implant failure". This search had no language or time restrictions. Results: The review included 15 papers, which were divided into four groups. The first group focused on studies regarding implant loss regardless of the superstructure. In the second group, research on implant-supported removable prostheses was examined. The third group consisted of a single study specifically addressing implant-supported single crowns. Lastly, the fourth group comprised two studies investigating implant-supported single crowns and fixed partial dentures. Only three out of the fifteen studies failed to find a correlation between bruxism and implant failure. The meta-analysis shows a significant pooled effect across the included studies, with an odds ratio of 4.68. Conclusions: Bruxism is a probable risk factor for mechanical issues in implant-supported prostheses and implant-supported crowns. Additionally, elevated failure rates have been documented in patients with bruxism.

Treatment strategies for dental implant removal: A literature review

Dental implants have been widely used with success, but long-term usage sometimes leads to implant loss. The purpose of this review was to summarize the etiology of early and late failure requiring dental implant removal and the treatment strategies for the removal of failed implants and reimplantation. Early failures are often caused by patient-related factors, such as smoking, diabetes, radiotherapy, bone quality, and periodontitis of the remaining natural teeth. The most common cause of late failure is peri-implantitis, followed by implant fracture and implant malpositioning. Implants should be removed if they are mobile or if their superstructure cannot be maintained (e.g., implant fracture). For peri-implantitis, implant removal should be determined based on the patient's age and esthetic needs, the implant site, and the severity of bone loss. Many reports have been published on implant removal techniques. The reverse torque technique should always be the first choice because of its low invasiveness. The weighted survival rate for the replacement of failed implants is 86.3%, with a much lower survival rate after the second or subsequent implantations. Therefore, patient-specific problems, such as smoking habits and bruxism, should be checked before reimplantation and controlled to the greatest extent possible.

Fracture rate and risk factors associated with the fracture of narrow diameter implants: A long-term retrospective analysis

OBJECTIVES

The objective of this long-term retrospective study was to evaluate the fracture rate and the risk factors associated with the fracture of 3.3 mm narrow diameter implants (NDIs).

MATERIALS AND METHODS

A total of 524 records of patients rehabilitated with 3.3 mm NDIs between 1997 and 2015 were assessed. Data on patients, implants, and prostheses were collected, and descriptive analysis of the variables was performed. NDIs were separated into 2 groups: "fractured" and "non-fractured", and a multilevel logistic regression model was applied to identify the risk factors associated with NDI fracture.

RESULTS

Eighty-four patients were removed from the analysis for interrupting follow-up or presenting failures other than fractures. Of the 440 patients included (64.66 ± 13.4 years), 272 were females (61.8%), and 168 males (38.2%), and mean follow-up time was 129 ± 47.1 months. Of the 1428 NDIs, 15 (1.05%) in 9 patients (2.04%) fractured during the studied period. Ten fractures (66.66%) happened in 6 patients (66.66%) showing signs of parafunction. NDI with modified sandblasted, large grit, acid-etched surface was the only implant variable to show a protective statistical significance (p = .0439).

CONCLUSIONS

NDI fracture was a rare event in the studied sample. NDIs manufactured with modified sandblasted, large grit, acid-etched surface may provide extra protection against NDI fracture. Patient-specific factors and implant characteristics should be carefully considered to limit the risk of fracture of 3.3 mm NDIs.

Investigation of Phase Transformation and Fracture Pattern as a Result of Long-Term Chewing Simulation and Static Loading of Reduced-Diameter Zirconia Implants

While zirconia implants exhibit osseointegration comparable to that of titanium, concerns arise regarding low-temperature degradation and its potential impact on fracture strength. This study investigated the phase transformation and fracture characteristics of zirconia dental implants after aging through chewing simulation and subsequent static loading. The experimental setup involved 48 one-piece monobloc zirconia implants with diameters of 3.0 mm and 3.7 mm that had straight or angled abutments, with crown restorations, which were divided into six groups based on intraoral regions. The specimens underwent chewing simulation equal to five years of oral service, which was followed by static loading. Statistical analyses were performed for the data obtained from the tests. After dynamic and static loadings, the fractured samples were investigated by Raman spectroscopy to analyze the phase composition and micro-CT to evaluate fracture surfaces and volume changes. According to the results, narrow-diameter zirconia implants have low mechanical durability. The fracture levels, fracture patterns, total porosity, and implant fracture volume values varied according to the implant diameter and phase transformation grade. It was concluded that phase transformation initially guides the propagation of microcracks in zirconia implants, enhancing fracture toughness up to a specific threshold; however, beyond that point, it leads to destructive consequences.

Biomechanical effects of different materials for an occlusal device on implant-supported rehabilitation in a tooth clenching situation: A 3D finite element analysis

PURPOSE

The purpose of this 3D finite element analysis was to evaluate the biomechanical effects of different materials used to fabricate occlusal devices to achieve stress distribution in simulated abutment screws, dental implants, and peri-implant bone tissue in individuals who clench their teeth.

MATERIALS AND METHODS

Eight 3D models simulated a posterior maxillary bone block with three external hexagon implants (Ø4.0 × 7.0 mm) supporting a 3-unit screw-retained metal-ceramic prosthesis with different crown connection (splinting), and the use of an occlusal device (OD). The OD was modeled to be 2-mm thick. ANSYS 19.2 software was used to generate the finite-element models in the pre-and post-processing phases. Simulated abutment screws and dental implants were evaluated by von Mises stress maps, and simulated bone was evaluated by maximum principal stress and microstrain maps by using a finite element software program.

RESULTS

The highest stress values in the dental implants and screws were observed in single crowns without OD (M1). Furthermore, the highest stress values and bone tissue strain were found in single crowns without OD (M1). The simulated material for the OD did not cause many discrepancies in terms of the stress magnitude in the simulated dental implant and abutment screw for both single and splinted crowns; however, more rigid materials exhibited lower stress values.

CONCLUSION

The use of OD was effective in reducing stress in the simulated implants and abutment screws and stress and strain in the simulated bone tissue. The material used to simulate the OD influenced the biomechanical behavior of implant-supported fixed prostheses, whereas splints with rigid materials such as PEEK and PMMA exhibited better biomechanical behavior.

Occlusal considerations in maintaining health of implants and their restorations

Dental implants are a regular feature in daily clinical practice and there is a need to undertake routine assessment and maintenance of implants and their restorations on par with that provided for natural teeth. Occlusal checks form an important part of the maintenance regime for preserving the integrity of implants, their restorations, and health of the peri-implant tissues. Implant restorations are subjected to the full characteristics and magnitude of occlusal forces, including those associated with parafunction. Compared with the periodontal ligament around teeth, the biophysical response to occlusal forces of osseointegration is different through the more rigid link of implant to bone and reduced proprioception. Risks attributable to occlusal forces primarily affect implant restorations and they are elevated in the presence of bruxism. The occlusal guidelines recommended by the literature are aimed at reducing these risks and regular assessment and maintenance of the occlusion is essential. A four-step sequence is presented to ensure that the annual occlusal checks include the patient's input and evaluation of restoration integrity, occlusal scheme, additional protection, and spatial changes.

Clinical Outcomes of Maxillary Sinus Floor Perforation by Dental Implants and Sinus Membrane Perforation during Sinus Augmentation: A Systematic Review and Meta-Analysis

The aim of the present systematic review was to investigate the clinical outcomes after the perforation of the maxillary sinus by dental implants, or after maxillary sinus membrane perforation during sinus lift procedure. Twenty-nine publications were included. Failure rates of implants in cases where perforation of sinus floor had happened (11 studies) was generally low, and only one case of transient sinusitis was reported. The estimated failure rate of these implants was 2.1% (SE 1.0%, p = 0.035). There were 1817 implants (73 failures) placed in augmented sinuses in which the sinus membrane was perforated and 5043 implants (274 failures) placed in sinuses with no perforated membrane, from 18 studies. The odds of implant failure difference between the groups were not significant (OR 1.347, p = 0.197). log OR of implant failure between perforated and non-perforated membrane groups did not significantly change with the follow-up time (-0.004/month; p = 0.500). In conclusion, implant failure rate is generally low either for implants penetrating in the floor of the maxillary sinus or implants placed in augmented sinuses in which the sinus membrane was perforated. The prevalence of postoperative infection/sinusitis is low, and it may depend either on the dimensions of the perforation or on the anatomical predisposition.

Clinical outcomes of implant- versus abutment-level connection in screw-retained fixed dental prostheses: A 5-year randomized controlled trial

AIM

The aim of the study was to evaluate the 5 years clinical outcomes associated with implant-level connection (IL) versus abutment-level connection (AL) for implants with an internal conical connection (ICC) supporting a screw-retained fixed partial denture.

MATERIALS AND METHODS

Fifty patients with 119 implants were randomly allocated to either the AL or IL group. Radiographic (Marginal bone loss) and clinical outcomes (Bleeding on Probing, probing pocket depth, plaque accumulation, incidence of peri-implantitis and peri-implant mucositis as well as prosthetic complications) were collected and compared at 1, 2, 3, and 5 years. A linear mixed model was used to evaluate the differences between groups.

RESULTS

Five years after treatment, the MBL change was not significantly different between the groups at any point. The MBL was 0.23 ± 0.64 mm (AL) and 0.23 ± 0.29 mm (IL). The bleeding on Probing was 44% (AL) and 45% (IL) (p = .89). The mean probing depth was 2.91 ± 1.01 mm (AL) and 3.51 ± 0.67 mm (IL). This difference between the groups was statistically significant but clinical insignificant. Presence of plaque was slightly higher (p = .06) in the IL group (34.4%) compared with the AL group (26.3%). The overall technical, biological, and prosthetic complication rates were similar between groups. None of the implants developed peri-implantitis during the entire follow-up period.

CONCLUSION

The results of this clinical trial indicated that all clinical and radiographical parameters were clinically comparable between the study groups.

Hypertension and Dental Implants: A Systematic Review and Meta-Analysis

PURPOSE

The aim of the present systematic review was to investigate the influence of hypertension on the dental implant failure rate.

METHODS

An electronic search was undertaken in four databases, plus a manual search of journals. The I2 statistic was used to check heterogeneity and the inverse-variance method was used for the meta-analysis. The estimate of relative effect for dichotomous outcome was expressed as an odds ratio (OR).

RESULTS

The review included 24 publications. There were 4874 implants (257 failures) placed in hypertensive patients and 16,192 implants (809 failures) placed in normotensive patients. A pairwise meta-analysis showed that implants in hypertensive patients did not have a higher risk of failure than implants placed in normotensive patients (OR 1.100, p = 0.671). The log OR of implant failure between hypertensive and normotensive patients did not significantly change with the follow-up time (p = 0.824).

CONCLUSIONS

This review suggests that implants in hypertensive patients do not present higher odds of failure in comparison to normotensive patients. However, further research on this topic, with the use of more rigorous criteria to diagnose patients as being hypertensive, as well as clearer information about the pharmacological management of the condition in the patients, is recommended.

Bruxism and dental implants: A systematic review and meta-analysis

BACKGROUND

Overload from bruxism may affect survival of dental implants.

OBJECTIVES

To evaluate implant failure and marginal bone loss (MBL) in patients presenting with probable bruxism compared to non-bruxers. The study was registered in PROSPERO (CRD42021238397).

METHODS

An electronic search September 2022 in PubMed/Medline, Web of Science and Science Direct was combined with a hand search. Two independent reviewers carried out abstract screening, full-text assessment, quality assessment (National Institutes of Health tool) and data extraction. Only studies that provided information on self-report and clinical examination needed for the diagnosis of at least 'probable' bruxism were included. A pairwise random-effect meta-analysis was carried out.

RESULTS

In total 1338 studies were identified, and after screening and full-text assessment 27 studies that presented data on 2105 implants in probable bruxers and 10 264 implants in non-bruxers were included, with 138 and 352 implant failures in respective groups. the meta-analysis showed that implants placed in probable bruxers had a higher risk of failure than in non-bruxers (OR 2.189; 95% CI 1.337, 3.583, p = .002). A meta-regression showed that follow-up time did not affect this OR. Eighteen studies provided general data on MBL but did not report results separated between bruxers and non-bruxers. Therefore, an analysis of MBL was not possible.

CONCLUSION

The results of the present systematic review show that implants placed in probable bruxers present a significantly higher risk of failure than implants placed in non-bruxers. This should be considered in treatment planning and management of implant patients.

Clinical outcomes of zirconia implants: a systematic review and meta-analysis

PURPOSE

To assess the clinical outcomes of zirconia dental implants based on an updated systematic literature review.

METHODS

An electronic search was performed in three databases, last updated in June 2023, supplemented by hand searching. The eligibility criteria were clinical studies reporting patients rehabilitated with zirconia implants. The cumulative survival rate (CSR) of implants was calculated. A meta-analysis for marginal bone loss (MBL) under different follow-up times and a meta-regression assessing the relationship between mean MBL and follow-up were done.

RESULTS

Twenty-five studies were included (4017 implants, 2083 patients). Seven studies had follow-up longer than 60 months. 172 implants failed, after a mean of 12.0 ± 16.1 months (min-max 0.3-86.0), of which 47 early failures, and 26 due to implant fracture, the majority in narrow-diameter implants. The 10-year CSR was 95.1%. Implants with coronal part prepared by drills presented statistically significant lower survival than non-prepared implants (p < 0.001). Two-piece implants presented lower survival than one-piece implants (p = 0.017). Implants discontinued from the market presented lower survival than the commercially available ones (p < 0.001). The difference in survival was not significant between implants in maxilla and mandible (p = 0.637). The mean MBL fluctuated between 0.632 and 2.060 mm over long periods of observation (up until 132 months). There was an estimated MBL increase of 0.005 mm per additional month of follow-up.

CONCLUSION

Zirconia implants present high 10-year CSR and short-term low MBL. The review was registered in PROSPERO (CRD42022342055).

CLINICAL RELEVANCE

The clinical outcomes observed for zirconia dental implants are very promising, although these have not yet been extensively studied as titanium alloy implants.

Difference in marginal bone loss around implants between short implant-supported partial fixed prostheses with and without cantilever: a retrospective clinical study

PURPOSE

To investigate the influence of cantilever prosthetic arm on the marginal bone loss (MBL) over time around dental implants supporting short fixed partial dentures (FPDs), in a record-based retrospective study.

METHODS

All cases of 3-unit implant-supported FPDs, supported by 2-3 implants, from the database of cases treated at one specialist clinic were considered for inclusion. Only implants with a minimum of 36 months of radiological follow-up were considered. Univariate linear regression models were used to compare MBL over time between 12 clinical covariates, after which a linear mixed-effects model was built.

RESULTS

One-hundred-thirty-nine patients (64 men, 75 women) with 164 3-unit implant-supported FPDs (333 implants supporting non-cantilevered FPDs, 94 supporting cantilevered FPDs) were included in the study. The patients were followed up clinically and radiographically for a mean of 154.1 ± 78.0 (min-max, 37.3-364.6) and 132.9 ± 77.3 months (min-max, 36.8-329.9), respectively. The total number of marginal bone level double measurements (mesial and distal sides of each implant) was 2909. FPDs with cantilever presented an estimated greater MBL over time compared to FPDs without cantilever. Bruxism, sex (women), implant (modified) surface, and (poor) bone quality were also associated with higher MBL over time.

CONCLUSIONS

The use of a cantilever extension is suggested to negatively affect the bone marginal level over time around implants supporting 3-unit FPDs. Due to the small difference of the estimated MBL over long periods of follow-up between the groups, it is a matter of debate if the observed negative effect may be of clinical significance.

Characteristics and Risk Factors for the Fracture of One-Piece Implants

Objective

The one-piece dental implant was originally designed to overcome the structural weaknesses of the two-piece implant. However, a fractured one-piece implant requires removal because the abutment cannot be repaired or replaced to support new prosthetic restorations. The aim of this study was to clarify the features and risk factors for fracture of the one-piece implant.

Methods

This study was designed as a retrospective case series research. The subjects were patients who were treated for fractures of the one-piece implant at a clinic in Japan between 2012 and 2021. Fractures of the one-piece implant were diagnosed by cone-beam computed tomography, and the association between age and duration from implant placement to fracture was analyzed by one-way ANOVA followed by the Tukey test.

Results

Eighteen patients and 20 one-piece implants (under 39 years: 5 patients and 6 implants; 40-59 years: 7 patients and 7 implants; over 60 years: 6 patients and 7 implants) had fractures in their one-piece implants. Of the fractured implants, 11 had a diameter of 3 mm, and 9 had a diameter of 4 mm. The mean durations up to implant fracture were 662 days in the younger group, 1467 days in the middle group, and 1239 days in older group, and the duration was significantly shorter in the younger group. In addition, 83.3% of fracture implants in the younger group were in the molar region. All fractures of the one-piece implants occurred under the bone margin. Two patients had torus mandibularis, and 1 patient was had bruxism.

Conclusions

One-piece implants in younger patients that are located in the lower molar position are the most susceptible to implant fracture, and the fracture occurred under the bone margin in all cases.

Prosthetic complications and failures of implant-supported fixed partial dentures: A scoping review

STATEMENT OF PROBLEM

Although high survival rates of implant-supported fixed partial dentures (ISFPDs) have been reported, evidence for complications, failures, and factors that interfere with their longevity is lacking.

PURPOSE

The purpose of this scoping review was to review the literature to investigate the most common failures and complications of ISFPDs.

MATERIAL AND METHODS

This review followed the preferred reporting items for systematic reviews and meta-analyses scoping review (PRISMA ScR) guidelines, and the methodology was registered on the open science framework (osf.io/5xqkp). An electronic search was conducted in PubMed/MEDLINE, Embase, Cochrane Library, Scopus, and Web of Science databases and nonpeer-reviewed literature for articles published from 2013 to January 2023. Studies that evaluated the clinical performance of ISFPDs with at least 1 year of follow-up and described the concepts of failure and success were included.

RESULTS

The search yielded 5695 studies. Fourteen articles were included in this review for data extraction. Veneering porcelain fracture, screw fracture, and implant loss were the most common failures reported. Technical complications mainly involved screw loosening, loss of retention, and wear of the screw-access restoration.

CONCLUSIONS

Bruxism, mismatch of the thermal expansion coefficient, unsatisfactory support of the framework, choice of cement, shape of the titanium abutments, and extended length of the cantilever were associated with the longevity of the ISFPD. Despite the high survival rate of ISFPDs, data must be carefully interpreted because of the variation in the materials used to manufacture the ISFPD and the heterogeneity of the studies in this review.

Risk Factors Associated with Failure and Technical Complications of Implant-Supported Single Crowns: A Retrospective Study

Background and Objectives: Implant-supported single crowns have become a routine approach for the replacement of missing single teeth, being considered as one of the most common ways of rehabilitation when adjacent teeth are healthy. The present retrospective study aimed to investigate the risk factors possibly associated with failure and technical complications of implant-supported single crowns and their supporting implants. Materials and Methods: Patients treated at one faculty (2009-2019) were considered for inclusion. Complications investigated included ceramic fracture/chipping, crown loss of retention/mobility, crown failure/fracture, loosening/loss/fracture of prosthetic screw, and implant failure/fracture. Any condition/situation that led to the removal/replacement of crowns (implant failure not included) was considered prosthesis failure. Univariate/multivariate Cox regression models were used to evaluate the associations between clinical covariates and failure. Results: 278 patients (358 crowns) were included. Mean ± SD follow-up was 56.5 ± 29.7 months. Seven implants (after a mean of 76.5 ± 43.7 months) and twenty crowns (21.3 ± 23.5 months) failed. The cumulative survival rate (CSR) for crowns was 93.5% after 5, remaining at 92.2% between 6 and 11 years. The most common reasons for crown failure were porcelain large fracture (n = 6), crown repeatedly loose (n = 6), and porcelain chipping (n = 5). Men and probable bruxism were identified in the Cox regression model as being associated with crown failure. The most common observed technical complications were mobility of the crown and chipping of the ceramic material, with the latter being observed even in crowns manufactured of monolithic zirconia. Cases with at least one technical complication (not considering loss of screw hole sealing) were more common among probable bruxers than in non-bruxers (p = 0.002). Cases of ceramic chipping were more common among bruxers than in non-bruxers (p = 0.014, log-rank test). Conclusions: Probable bruxism and patient's sex (men) were factors associated with a higher risk of failure of implant-supported single crowns.

Bisphosphonates and Dental Implants: A Systematic Review and Meta-Analysis

The purpose of the present systematic review was to investigate the influence of bisphosphonates (BPs) on the dental implant failure rate and marginal bone loss (MBL). An electronic search was undertaken in three databases, plus a manual search of journals. Meta-analyses were performed, besides a meta-regression in order to verify how the log odds ratio (OR) was associated with follow-up time. The five- and ten-year estimated implant survivals were calculated. The review included 33 publications. Altogether, there were 1727 and 21,986 implants placed in patients taking and not taking BPs, respectively. A pairwise meta-analysis (26 studies) showed that implants in BP patients had a higher failure risk in comparison to non-BP patients (OR 1.653, p = 0.047). There was an estimated decrease of 0.004 in log OR for every additional month of follow-up, although it was not significant (p = 0.259). The global estimated implant survival in patients taking BPs after 5 and 10 years was 94.2% (95% CI, 94.0-94.4) and 90.1% (95% CI, 89.8-90.3), respectively. It was not possible to make any reliable analysis concerning MBL, as only two studies reported MBL results separated by groups. There is a 65.3% higher risk of implant failure in patients taking BPs in comparison to patients not taking this class of drugs.

Marginal bone loss around dental implants: comparison between diabetic and non-diabetic patients-a retrospective clinical study

OBJECTIVES

The aim of the present retrospective study was to compare the marginal bone loss (MBL) around dental implants in a group of diabetic patients in relation to a matched group of non-diabetic patients.

MATERIALS AND METHODS

The present dental record-based retrospective study included patients selected from individuals treated with dental implants at one specialist clinic in Malmö, Sweden. Patients were excluded if they had history of periodontitis and/or were treated for periodontal disease. The study group included 710 implants installed in 180 patients (mean age 60.3±13.0 years), 349 implants in 90 diabetic (21 T1DM and 69 T2DM patients), and 361 implants in 90 non-diabetic patients.

RESULTS

The results suggested that jaw (greater MBL in the maxilla), diabetes (greater MBL for diabetic patients, and worse for T1DM patients), bruxism (greater MBL for bruxers), and smoking (greater MBL for smokers and former smokers) had a statistically significant influence on MBL over time.

CONCLUSIONS

Patients with diabetes have an estimated greater MBL over time compared to non-diabetic patients. The difference was greater in patients with diabetes type 1 compared to patients with diabetes type 2. Bruxism, smoking, and implant location (maxilla) were also associated with a higher loss of marginal bone around implants over time.

CLINICAL RELEVANCE

Awareness of the possible influence of diabetes on the long-term outcomes of dental implant treatment is important, in order to be able to minimize the possibility of a high MBL with time, which can eventually lead to the loss of the implant.

Influence of Crown-Implant Ratio and Implant Inclination on Marginal Bone Loss around Dental Implants Supporting Single Crowns in the Posterior Region: A Retrospective Clinical Study

The aim of this present record-based retrospective study was to investigate the influence of the crown-implant ratio (CIR) and implant inclination in relation to the occlusal plane on the marginal bone loss (MBL) around dental implants supporting single crowns in the posterior region of the jaws. All the cases of implant-supported single crowns in the premolar and molar regions were initially considered for inclusion. Only implants not lost, with baseline radiographs taken within 12 months after implant placement and with a minimum of 36 months of radiological follow-up, were considered for the analysis of MBL. Univariate linear regression models were used to compare MBL over time between 12 clinical covariates, after which a linear mixed-effects model was built. After the exclusion of 49 cases, a total of 316 implant-supported single crowns in 234 patients were included. The results from the statistical models suggested that implant inclination and anatomical- and clinical CIR (the main related factors investigated in the study) were not statistically significantly related to MBL over time. Age (older people), tooth region (premolar), and bruxism (bruxers) had a statistically significant influence on MBL over time.

Up to a 15-Year Survival Rate and Marginal Bone Resorption of 1780 Implants with or without Microthreads: A Multi Center Retrospective Study

The effect of microthreads at the implant neck on the amount of marginal bone resorption is controversial. This multicenter retrospective study compared the implant survival rate and amount of marginal bone resorption between two platform-switching internal connection implant systems with or without microthreads. Patient-related (age and sex), surgery-related (implant installation site, type, diameter, and length), and prosthesis-related (prosthesis type) data were collected from patient charts from the implant placement surgery to the final recall visit. A total of 1780 implants, including 1379 with microthreads and 401 without microthreads, were placed in 804 patients. For implants with and without microthreads, the longest follow-up period after prosthesis delivery was 15 and 6 years, respectively. Twenty implants failed during the 15-year follow-up period (98.8% survival rate) due to failed osseointegration, peri-implantitis, implant fractures, and non-functioning implants. The mean marginal bone loss was < 0.1 mm for both implant systems at the 1-year follow-up and 0.18 mm and 0.09 mm at the 4-year follow-up for implants with and without microthreads, respectively, without statistical significance. Microthreads did not significantly affect the amount of marginal bone loss or the implant survival rate for implants with an internal connection with a platform-switching design.

Marginal bone loss around dental implants: comparison between matched groups of bruxer and non-bruxer patients: A retrospective case-control study

PURPOSE

To compare marginal bone loss (MBL) around dental implants in a group of bruxers in relation to a matched group of non-bruxers.

METHODS

The present record-based retrospective study included patients selected from individuals treated with dental implants at one specialist clinic in Malmö. Only implants not lost and with baseline radiographs taken within 12 months after implant placement and with a minimum of 36 months of radiological follow-up were considered for inclusion. Univariate linear regression models and a linear mixed-effects model were performed.

RESULTS

Two hundred and four patients (104 bruxers, 100 non-bruxers), with a total of 811 implants (416 in bruxers, 395 in non-bruxers) were included in the study. The results of the linear mixed-effects model suggested that bruxism, smoking, age, region of the jaws, implant diameter, and prosthesis type had a statistically significant influence on MBL over time. Individuals who are both bruxers and smokers showed greater MBL when compared to individuals who are either a bruxer or smoker, or neither (p < 0.001).

CONCLUSIONS

Bruxism is suggested to increase the risk of MBL over time, as well as higher age, smoking, and the combination of bruxism and smoking. Other factors that showed a correlation with increased MBL were implant diameter, region of the jaws, and prosthesis type, but it is not possible to draw robust conclusions for these factors, as the categories of these variables were very unbalanced.

Dental Reimplantation Treatment and Clinical Care for Patients with Previous Implant Failure-A Retrospective Study

(1) Objectives: This study evaluated the clinical outcomes of dental implants placed in previously failed sites and discussed the risk factors that mattered in reimplantation. (2) Methods: All the cases by one specific implantologist during his first five years of clinical practice were screened, with a focus on those who received reimplantation. The clinical outcomes were assessed, including the implant survival, peri-implant health, and patients' satisfaction. (3) Results: 28 patients (31 implants) were recorded as failures from 847 patients (1269 implants), with a 2.4% overall failure rate at the implant level, of whom 19 patients (21 implants) received reimplantation treatment. After a mean follow-up of 33.7 ± 10.1 months (95% CI 29.1-38.3 months), 20 implants remained functional, but 1 implant revealed a secondary early failure, indicating a 95.2% overall survival rate. The mean probing depth (PD), modified sulcus bleeding index (mSBI), and marginal bone loss (MBL) of the surviving reinserted implants were 2.7 ± 0.6 mm (95% CI 2.5-3.0 mm), 0.7 ± 0.5 (95% CI 0.5-1.0), and 0.5 ± 0.6 mm (95% CI 0.3-0.8 mm), respectively. Embedded healing occurred more frequently in the reinserted implants than in the primary implants (p = 0.052). The patients' satisfaction suffered from implant failure, but a successful reimplantation could reverse it with close doctor-patient communication. (4) Conclusions: Reimplantation treatment was recommended, based on a thorough evaluation and consideration of the risk factors combined with effective communication with the patients.

Sleep bruxism and obstructive sleep apnea: association, causality or spurious finding? A scoping review

STUDY OBJECTIVES

To evaluate the available evidence on the putative relationships between sleep bruxism (SB) and, obstructive sleep apnea (OSA) to assess the extent of research on this topic, and to formulate suggestions for future research.

METHODS

A scoping review including studies examining temporal and overall association and prevalence of SB and OSA was performed. Six main databases and gray literature were searched. The studies selection was conducted by three independent reviewers. A narrative synthesis of the results was carried out.

RESULTS

Thirteen studies in adults and eight studies in children were finally included. The median of concomitant conditions prevalence was 39.3% in adults and 26.1% in children. Marked methodological variability was identified among studies in adults and even more when we compared detection methods in children. No significant association between OSA and SB emerged in most studies in adults, while an association may be possible in children.

CONCLUSIONS

Based on the current literature, it is not possible to confirm that there is a relationship between SB and OSA in adults. In patients under pediatric care, although this association seems plausible, there is currently insufficient supportive evidence. Standardized validated methodologies for identifying SB should be consistently used in both populations before reaching any conclusion regarding such association. Furthermore, assessment of shared phenotypes between patients with SB and patients with OSA may reveal new insights that will contribute to personalized approaches aiming to optimize the management of such comorbidities.

Tissue Surface Adaptation and Clinical Performance of CAD-CAM Milled versus Conventional Implant-Assisted Mandibular Overdenture

Purpose

To evaluate the surface adaptation and maximal biting force of CAD-CAM milled mandibular overdenture (CAD-CAM MOD) compared to conventional compression mold mandibular overdenture (CC MOD).

Materials and Methods

Ten completely edentulous subjects with persistent complaints of their complete mandibular dentures were received four dental implants in the anterior mandible. Three months after osseointegration, subjects were randomly received either conventional compression mold or CAD-CAM MOD in a crossover design. To assess tissue surface adaptation, the fitting surfaces of each denture base were scanned and placed on the reference master cast. Three and six months after each overdenture was inserted, clinical performance in the form of maximum biting force was evaluated.

Results

The results of this study indicated that the tissue surface adaptation of the CAD-CAM MOD bases was significantly better than the conventional (compression mold technique) processed bases where (P=0.0001). Regarding clinical performance (maximum biting force), the CAD-CAM MOD exhibited better clinical performance (P=0.0001).

Conclusions

In denture processing methods, the CAD-CAM overdenture delivered more precise adaption and clinical performance than the compression mold technique.

Osteotomy combined with the trephine technique for invisible implant fracture: A case report

BACKGROUND

Implant fracture is one of the most serious mechanical complications of dental implants. Conventional treatment necessitates visibility of the apical portion of the fractured implant, whereas for deep and invisible implant fractures, the traditional trephine method has been ineffective. Surgical removal of the marginal bone to expose the fracture surface would be a time-consuming and extensively damaging procedure. Here, we propose a novel technique to address invisible implant fractures.

CASE SUMMARY

A 50-year-old woman was referred to our department with the chief complaint that her right mandibular implant tooth had fallen out 3 mo earlier. Cone-beam computed tomography examination showed an implant fracture with a fracture surface 5.1 mm below the crestal ridge. The patient was treated with osteotomy combined with the trephine technique to expose the surgical field and remove the implant. The invisible fractured implant was successfully removed, with minimal trauma. A modified Wafer technique-supported guided bone regeneration treatment was then administered to restore the buccal bone wall and preserve the bone mass. Six months later, fine regenerative bone and a wide alveolar crest in the edentulous area were observed, and a new implant was placed. Four months later, restoration was completed using a cemented ceramic prosthesis. Clinical and radiographic examinations 12 mo after loading fulfilled the success criteria. The patient reported no complaints and was satisfied.

CONCLUSION

Osteotomy combined with the trephine technique can be effectively used to address deep and invisible implant fractures.

Stability of Cantilever Fixed Dental Prostheses on Zirconia Implants

Background: The objective was to determine the optimal connector size and position within zirconia disks for implant-supported cantilever fixed dental prostheses (ICFDP). Methods: Two-unit ICFDPs (n = 60) were designed for the premolar region with connector sizes of either 9 or 12 mm² and positioned in the enamel or dentin layer of two different types of zirconia disks. The restorations were milled and cemented onto zirconia implants. After simulated chewing for 1.2 Mio cycles, the fracture load was measured and fractures were analyzed. Results: No fractures of ICFDPs or along the implants were detected after simulated aging. The mean fracture load values were significantly higher for a connector size of 9 mm² (951 N) compared with 12 mm² (638 N). For the zirconia material with a higher biaxial flexural strength, the fracture load values were increased from 751 to 838 N, but more implant fractures occurred. The position within the zirconia disk did not influence the fracture load. Conclusions: A connector size of 9 mm² and a zirconia material with a lower strength should be considered when designing ICFDPS on zirconia implants to reduce the risk of fractures along the intraosseous implant portion.

Management and sequelae of dental implant removal

Inappropriate and unnecessary implant therapy driven by an erroneous belief that dental implants provide enhanced function and esthetics over diseased or failing teeth has led to a growing burden of implant complications across the globe. Specifically, esthetic and biological complications frequently lead to the unfavorable prognosis of dental implants. Often, these cannot be managed predictably to improve the condition or satisfy patients' demands. In such circumstances, implant removal needs to be considered. Currently, minimally invasive methods based on reverse torque engineering are key to preserve peri-implant soft and hard tissues. Implant replacement is now feasible, as evidenced by the high survival rates of implants placed at previously failed sites. Notwithstanding these data, clinicians should still consider carefully the expendability of an implant and whether its replacement will satisfy the prosthetic, biomechanical, and esthetic demands of the patient. In the scenario where future implant placement is desired, protocols undertaken for soft/hard tissue grafting and implant placement should be based upon defect morphology and soft and hard-tissue characteristics. Currently, however, a lack of knowledge of the biological events and dimensional changes that arise following implant removal renders decision-making complex and challenging, and recommendations remain largely based upon empirical speculation. This chapter will review the indications for implant replacement for prosthetic, biomechanical, and esthetic complications, alongside considerations in decision-making, planning, implementation, and outcomes of implant replacement.

Survival and Success Rates of Monolithic Zirconia Restorations Supported by Teeth and Implants in Bruxer versus Non-Bruxer Patients: A Retrospective Study

The aim of this study was to assess retrospectively the survival and success rates of monolithic zirconia restorations supported by teeth and implants in bruxer versus non-bruxer patients. Methods: A total of 15 bruxer and 25 non-bruxer patients attended the recall appointment. The bruxer group (mean age of 61.2 ± 13.3 years and follow-up of 58.7 ± 16.8 months) were treated with 331 monolithic zirconia restorations, while the non-bruxer group, with a comparable mean age and follow-up time, were treated with 306 monolithic zirconia restorations. Clinical data were retrieved from the patients' files. At the recall appointment, all supporting teeth and implants were examined for biological and technical complications, and the restorations were evaluated using modified California Dental Association (CDA) criteria. Data were statistically analyzed using survival analysis methods. A significance level of p < 0.05 was used. A total of 31 versus 27 biologic and technical complications were recorded in the bruxer and non-bruxer groups, respectively. No significant differences were found between the two groups regarding overall complications and survival rate. Regarding the type of complication, a significantly higher rate of veneered porcelain chipping (p = 0.045) was observed in the bruxer group. With regard to biological complications, the only complications that exhibited a borderline, although not significant, difference were three fractured teeth exclusively in the bruxer group (p = 0.051), which were replaced with implant-supported restorations. Within the limitations of this study, we conclude that there were no significant differences in the overall survival and success rates of the monolithic zirconia restorations in bruxer versus non-bruxer patients, although veneered zirconia restorations and single tooth abutments exhibited a higher rate of complications in the bruxer group.

The use of implant-level connection in screw-retained fixed partial dentures: A 3-year randomised clinical trial

OBJECTIVES

This randomised controlled trial compares the 3-year outcomes, that is, marginal bone-level (MBL) changes and clinical parameters, between an abutment-level (AL) and implant-level (IL) connection for implants with an internal conical connection (ICC) supporting a screw-retained fixed partial denture.

MATERIAL AND METHODS

Fifty patients with 119 implants were randomly allocated to either the AL or IL group. Radiographic and clinical examinations were performed after one, two, and 3 years. A linear mixed model was used to evaluate the differences between groups.

RESULTS

The MBL change was not significantly different between the groups at any point. The MBL was 0.12 ± 0.31 mm (AL) and 0.23 ± 0.26 mm (IL) after 1 year; 0.15 ± 0.34 mm (AL) and 0.17 ± 0.22 mm (IL) after 2 years; 0.18 ± 0.39 mm (AL) and 0.15 ± 0.21 mm (IL) after 3 years. The bleeding on probing was 43.44 ± 39.24% (AL) and 58.19 ± 41.20% (IL) after 1 year; 35.78 ± 39.22% (AL) and 50.43 ± 41.49% (IL) after 2 years; 51.27 ± 44.63% (AL) and 49.57 ± 37.31% (IL) after 3 years and was significantly different (p = .025) between 1 and 2 years. The probing depth showed a significant difference at each time point while the plaque was not significant between the groups. The overall technical, biological and prosthetic complication rates were 5.04%, 3.36%, and 16.00%, respectively.

CONCLUSIONS

The MBL change was similar in the groups. The slight differences in the soft tissue complications between the groups are likely not of clinical relevance. An IL connection is considered to be a valid alternative to an AL set-up in ICC implants.

Implant Fracture: A Narrative Literature Review

Implants fracture is a rare but possible complication that leads to implants failure after prostheses delivery. Mechanical properties play a key role in the failure of dental implant systems. The aim of this narrative review was to evaluate the existing evidence in identifying etiology risk factors for implants fracture. The focused question was to evaluate whether there was any possible factors influencing the fracture of dental implants. A literature search of papers written in English, published from 1967 to July 2021, and reporting incidence of implants fracture in human with at least 15 participants (and one year of follow-up) was conducted using PubMed database including MeSH and free text terms and filters. Selected manuscripts were analyzed and discussed. The outcomes were the incidence of implants failure due to a fracture and the associated risk factors. A total of 96 articles were initially selected, but only eight articles were included according to the search criteria (two systematic reviews and six retrospective evaluation). Incidence of implants fracture ranged from 0.2 to 2.3%, with a mean value of 0.52%. Poor implant planning, including implant design and diameter, and occlusal overloading, were the most common variables associated with implants fracture. Implant removal is the only possible treatment and hence prevention, including stability of the marginal bone loss, is mandatory.

Screw stability of CAD-CAM titanium and zirconia abutments on different implants: An in vitro study

BACKGROUND

Limited information is available regarding the removal torque values (RTVs) of screws of different abutment materials when used with different implants.

PURPOSE

To evaluate the effect of implant type and abutment material (zirconia; Zir and titanium; Ti) on the RTVs of abutment screws after cyclic loading.

MATERIALS AND METHODS

Internal conical connection implants (CC, OsseoSpeed TX) and modified internal conical connection implants (MCC, OsseoSpeed EV) (n = 10) were clamped in resin dies. Zir and Ti (N = 20) custom abutments were tightened to implants (20 Ncm for CC and 25 Ncm for MCC) as specified by their manufacturers. The abutments were cyclically loaded by using a sequentially increased loading protocol; 2-million cycles under 100 N, 3-million cycles under 200 N, and 2-million cycles under 300 N loads with 2 Hz. After 7 million cycles, RTVs (Ncm) were measured by using a torque gauge. The data were analyzed with ANOVA by using the restricted maximum likelihood estimation method. Tukey-Kramer adjustment was used for any significant interaction of implant-abutment pairs (α = 0.05).

RESULTS

Two CC implants, 1 with Ti and 1 with Zir abutment, fractured during cyclic loading (under 300 N loads within the 6th and 7th million cycles) and discarded for statistical analysis. Only implant type had a significant effect on RTVs (p <0.001). Screws of Ti abutments on MCC implants had significantly higher RTVs than the screws of Ti (p = 0.003) and Zir (p = 0.005) abutments on CC implants.

CONCLUSIONS

Implant type affected the RTVs, however, the RTVs were higher than the initial torque values for all groups. Screws of Ti abutments on implant, which required greater initial torque values had higher RTVs than the screws of Ti and Zir abutments on the implant that required smaller initial torque values. RTVs were similar for Zir and Ti abutment screws within each implant type.

Microstructural Analysis of Fractured Orthopedic Implants

In this paper, fracture behavior of four types of implants with different geometries (pure titanium locking plate, pure titanium femoral implant, Ti-6Al-4V titanium alloy pelvic implant, X2CrNiMo18 14-3 steel femoral implant) was studied in detail. Each implant fractured in the human body. The scanning electron microscopy (SEM) was used to determine the potential cause of implants fracture. It was found that the implants fracture mainly occurred in consequence of mechanical overloads resulting from repetitive, prohibited excessive limb loads or singular, un-intendent, secondary injures. Among many possible loading types, the implants were subjected to an excessive fatigue loads with additional interactions caused by screws that were mounted in their threaded holes. The results of this work enable to conclude that the design of orthopedic implants is not fully sufficient to transduce mechanical loads acting over them due to an increasing weight of treated patients and much higher their physical activity.

Occlusal Schemes for Implant Restorations: Best Evidence Consensus Statement

PURPOSE

Numerous studies have focused on the various complications with implant-retained restorations and a common thread in these publications is the potential for occlusal overload. The purpose of this Best Evidence Consensus Statement on implant occlusal schemes was to review the literature to determine the level of scientific evidence upon which the articles are based.

MATERIALS AND METHODS

Limiting the search to Clinical trials, Randomized Controlled Trials, Systematic Reviews, Meta-analyses, the key words: dental implants, occlusion, found no citations. Expanding the search to Journal articles found 1,483 results, 20 of which pertained to the question. Doing a similar search including Journal Articles, the key words: dental implants and occlusal scheme found 47 citations, 17 of which were pertinent to the question.

RESULTS

After eliminating duplicates and non-relevant articles, 15 were included in the review. Nineteen additional articles were culled by going through the reference lists in the aforementioned articles.

CONCLUSIONS

There is a lack of scientific evidence regarding the occlusal scheme utilized with implant restorations that will minimize or eliminate complications. In light of this lack of scientific evidence, the style of occlusion a practitioner utilizes with tooth or mucosal supported prostheses may be used with implant-supported restorations until compelling evidence dictates otherwise.

Bruxism: Best Evidence Consensus Statement

PURPOSE

The purpose of this Best Evidence Consensus Statement is to report on the prevalence, potential causes or association, treatment and cure of bruxism.

MATERIALS AND METHODS

A literature search limited to Clinical Trials, Randomized Controlled Trials, Systematic Reviews and Meta Analyses, with the key words bruxism, and prevalence identified 22 references, bruxism and causation 21, bruxism, and treatment 117, and bruxism and cure none.

RESULTS

Prevalence received 5 references which were relevant to the question researched. Causation received 11 relevant references, treatment 34 relevant references and cure none. Eighteen additional references were culled from the reference lists in the aforementioned articles.

CONCLUSIONS

Due to variations in demographics and the dependence on anamnestic data, the true prevalence of bruxism in any specific population is unknown. There is moderate evidence that psychosocial factors such as stress, mood, distress, nervousness, and feeling blue are associated with sleep bruxism (SB) as well as caffeine, alcohol, and smoking. There is no consensus on what symptoms of SB or awake bruxism (AB) should be treated. There is some evidence that occlusal devices and bio feedback therapies can be utilized in SB treatment. There is conflicting evidence in the use of Botulinum toxin A and no compelling evidence for the use of drug therapy to treat SB. There is not an established cure for bruxism. The clinician is best served in using caution in the dental rehabilitation of patients with severe occlusal wear.

Fractures of implant fixtures: a retroscccpective clinical study

BACKGROUND

The aim of this study was to evaluate the factors that may affect implant fixture fractures.

METHODS

Patients who experienced implant fixture removal at Seoul National University Bundang Hospital from 2007 to 2015 due to implant fixture fracture were included. Implant/crown ratio, time of implant fracture, clinical symptoms before implant fracture, treatment of fractured implants, and the success and survival rate of the replaced implants were evaluated retrospectively.

RESULTS

Thirteen implants were fractured in 12 patients. Patient mean age at the time of fracture was 59.3 years. Of the 13 implants, 7 implants were placed at our hospital, and 6 were placed at a local clinic. The mean crown/implant ratio was 0.83:1. The clinical symptoms before fracture were screw loosening in five implants, marginal bone loss in five implants, and the presence of peri-implant diseases in five implants. All the fractured implants were removed, and 12 out of the 13 sites were re-implanted. Parafunctions were observed in two patients: one with bruxism and one with attrition due to a strong chewing habit.

CONCLUSIONS

Several clinical symptoms before the fracture of an implant can predict implant fixture failure. Therefore, if these clinical symptoms are observed, appropriate treatments can be taken before more serious complications result.

Influence of Bone Definition and Finite Element Parameters in Bone and Dental Implants Stress: A Literature Review

Bone plays an important role in dental implant treatment success. The goal of this literature review is to analyze the influence of bone definition and finite element parameters on stress in dental implants and bone in numerical studies. A search was conducted of Pubmed, Science Direct and LILACS, and two independent reviewers performed the data extraction. The quality of the selected studies was assessed using the Cochrane Handbook tool for clinical trials. Seventeen studies were included. Titanium was the most commonly-used material in dental implants. The magnitude of the applied loads varied from 15 to 300 N with a mean of 182 N. Complete osseointegration was the most common boundary condition. Evidence from this review suggests that bone is commonly defined as an isotropic material, despite being an anisotropic tissue, and that it is analyzed as a ductile material, instead of as a fragile material. In addition, and in view of the data analyzed in this review, it can be concluded that there is no standardization for conducting finite element studies in the field of dentistry. Convergence criteria are only detailed in two of the studies included in this review, although they are a key factor in obtaining accurate results in numerical studies. It is therefore necessary to implement a methodology that indicates which parameters a numerical simulation must include, as well as how the results should be analyzed.

Analysis of technical complications and risk factors for failure of combined tooth-implant-supported fixed dental prostheses

BACKGROUND

The oral rehabilitation with fixed restorations supported by the combination of teeth and dental implants has been advocated in some cases.

PURPOSE

To assess the clinical outcomes of these prostheses. Fixed restorations supported by the combination of teeth and dental implants.

MATERIALS AND METHODS

This retrospective study included all patients treated with combined tooth-implant-supported fixed dental prostheses (FDPs) at one specialist clinic. Abutment/prosthesis failure and technical complications were the outcomes analyzed.

RESULTS

A total of 85 patients with 96 prostheses were included, with a mean follow-up of 10.5 years. Twenty prostheses failed. The estimated cumulative survival rate was 90.7%, 84.8%, 69.9%, and 66.2% at 5, 10, 15, and 20 years, respectively. The failure of tooth and/or implant abutments in key positions affected the survival of the prostheses. There were seven reasons for prostheses failure, with the loss of abutments exerting a significant influence. Bruxism was possibly associated with failures. Prostheses with cantilevers did not show a statistically significant higher failure rate. No group had a general higher prevalence of technical complications in comparison to the other groups.

CONCLUSIONS

Although combined tooth-implant-supported FDPs are an alternative treatment option, this study has found that across 20 years of service nearly 35% the prostheses may fail.

Retrospective evaluation of implant-supported full-arch fixed dental prostheses after a mean follow-up of 10 years

OBJECTIVE

To assess the outcomes of implant-supported full-arch fixed dental prostheses (ISFAFDPs) and the supporting implants.

MATERIAL AND METHODS

This retrospective study included patients treated with ISFAFDPs at one specialist clinic. Implant/prosthesis failure and complications were the outcomes analyzed. Survival analysis methods were used.

RESULTS

A total of 709 patients with 869 ISFAFDPs (4,797 implants) were included, with a mean ± SD follow-up of 10.7 ± 7.2 years. A total of 353 implants and 62 prostheses failed. Estimated cumulative survival rates were as follows: 93.3% (95% CI 91.3, 95.3) after 10 years and 87.1% (95% CI 83.4, 90.8) after 20 years. Implants installed in bruxers, smokers, and maxilla had a lower survival than implants installed in non-bruxers, non-smokers, and mandible, respectively. A total of 415 ISFAFDPs (47.8%) presented technical complications, of which 67 (7.7%) presented only occurrences of loss/fracture of implant access hole sealing. Bruxism was a factor to exert a higher risk of screw loosening (HR 3.302; also in younger patients), screw fracture (HR 4.956), ceramic chipping/fracture (HR 5.685), and loss/fracture of acrylic teeth (HR 2.125; this last complication with higher risk also in men, in maxillae, and when the opposing jaw presented natural dentition or fixed prostheses). Patients with bruxism had a statistically significant higher risk of prosthesis failure than non-bruxers (HR 3.276).

CONCLUSIONS

ISFAFDPs presented good long-term prognosis. Failure of several supporting implants was the main reason for failure. The results of the present study strongly suggest that bruxism is an important contributor to implant and prosthesis failure, as well as to an increased prevalence of technical complications in ISFAFDPs.

Retrospective clinical evaluation of 2- to 6-unit implant-supported fixed partial dentures: Mean follow-up of 9 years

BACKGROUND

Implant-supported fixed partial dentures (ISFPDs) are one of the most common options to rehabilitate partially edentulous patients.

PURPOSE

To assess the clinical outcomes of ISFPDs.

METHODS

This retrospective study included all patients treated with ISFPDs with 2 to 6 prosthetic units at one specialist clinic. Implant/prosthesis failure and technical complications were the outcomes analyzed.

RESULTS

Six hundred and forty-two patients with 876 ISFPDs (2241 implants) were included, followed up for 108.0 ± 76.2 months. Eighty-eight prostheses and 112 implants (26 before, 86 after prosthesis installation) failed. The estimated CSR of ISFPDs at 30 years was 72.7%. Smokers presented lower implant survival than nonsmokers. Two hundred and ninety-nine ISFPDs (33.2%) presented technical complications. Bruxism was a factor to exert a higher risk of screw and implant fracture, and ceramic chipping. ISFPDs with cantilever presented higher risk of failure, and screw loosening/fracture. Prostheses supported by implants with internal abutment connection or with two pontics had higher risk of presenting ceramic chipping. Extension of the prosthesis did not seem to exert influence on prosthesis failure/complications.

CONCLUSIONS

ISFPDs presented good long-term prognosis. Implant failure was the main reason for ISFPD failure. The results suggest that bruxism and the presence of cantilever may contribute to the increased rate of mechanical complications and prosthesis failure.

Retrospective clinical evaluation of implant-supported single crowns: Mean follow-up of 15 years

OBJECTIVE

To retrospectively assess the clinical outcomes of implant-supported single crowns and the supporting implants.

MATERIAL AND METHODS

This retrospective study included all patients treated with implant-supported single crowns at one specialist clinic. Implant and prosthesis failure, and mechanical/technical complications (ceramic fracture/chipping; crown loss of retention/mobility; crown failure/fracture; loosening/loss/fracture of prosthetic screw; and implant failure/fracture) were the outcomes analyzed. Any condition/situation that led to the removal/replacement of crowns was considered prosthesis failure.

RESULTS

A total of 438 patients with 567 crowns were included. Mean ± SD follow-up of 183.4 ± 69.3 months. A total of 37 implants (6.5%) and 54 crowns (9.5%) failed. If only technical problems were considered, the crown failure rate decreased to 4.1% (23/567). Most common reasons for crown failure: esthetic issue (n = 12), crown constantly mobile (n = 9), change to another type of prosthesis together with other implants (n = 8), crown fracture (n = 7), and crown in infraposition in comparison with adjacent teeth (n = 7). The odds of crown failure were shown to be statistically significantly higher for the following factors: younger patients, maxillary crowns, and screw-retained crowns. Loose prosthetic screw was much more prevalent in screw-retained than in cemented crowns. Ceramic fracture/chipping was more prevalent in screw-retained crowns, maxillae, females. Crown fracture was more prevalent in ceramic crowns, screw-retained crowns, maxillae, posterior region, females. However, these differences were statistically significant only for crown fractures in females.

CONCLUSIONS

The odds of crown failure were significant for some factors, but one must keep in mind that non-technical complications are as common as technical ones as reasons for the replacement of implant-supported single crowns.

Are There Contraindications for Placing Dental Implants?

There are few absolute contraindications to dental implant placement. Relative contraindications include cognitive decline, American Society of Anesthesiology patient status IV or higher categories, or medical conditions that may jeopardize the life or lifespan of the patient. Precautions for placing dental implants should be viewed with respect to the evidence-based exposures that can contribute to risk of failure, including but not limited to local, behavioral, and medical factors. Risk for dental implant failure increases in association with (1) past history of periodontal disease, (2) bruxism, (3) smoking, and (4) radiation therapy.

Management of Implant/Prosthodontic Complications

Dental implants continue to grow in popularity because they are a predictable treatment to replace missing teeth. They have a high success rate; however, they are still associated with some clinical complications. This article discusses a diverse range of complications related to the restorative and mechanical aspects of dental implants and the management of such complications, as well as potential factors contributing to them.

Implant vs abutment level connection in implant supported screw-retained fixed partial dentures with cobalt-chrome framework: 1-year interim results of a randomized clinical study

BACKGROUND

Screw-retained fixed partial dentures (FPD) have shown a lower incidence of biologic complications and an easier retrievability compared with cemented FPD.

PURPOSE

To compare the marginal bone loss at conical connection implant restored with a screw retained cobalt-chrome FPD in an implant-level (IL) or an abutment-level (AL) setup.

MATERIALS AND METHODS

Patients with at least two adjacent missing teeth were randomly allocated to be restored with IL or AL FPD. Periapical radiographs and clinical examination were taken at implant placement, prosthetic connection, 6 and 12 months to evaluate marginal bone loss (MBL), and soft tissue conditions. Complications were used to calculate prognostic indexes.

RESULTS

Fifty patients were treated with 50 FPD supported by 119 implants. The difference of MBL between the IL and AL groups was statistically significant (P = 0.003). At 1 year, MBL was 0.086 ± 0.313 mm and 0.005 ± 0.222 mm in the IL and AL groups, respectively. The presence of BoP increased with time in IL, whereas it decreased in AL group (P < 0.001). A minor complication was encounted in one FPD.

CONCLUSIONS

A low grade of MBL was present after 1 year. IL showed greater amount of MBL and soft tissue inflammation indexes than AL. In FPD, AL may be a safer procedure than IL setup in order to preserve a healthy periimplant tissue.