Reasons for Crown Failures in Primary Teeth: Protocol for a Systematic Review and Meta-Analysis

BACKGROUND

There is a tendency nowadays to restore large defects in primary dentition with pediatric crowns instead of conventional restorations. Thus, understanding the factors contributing to the survival or failure of dental crowns in pediatric dentistry is essential for optimizing treatment outcomes.

OBJECTIVE

The primary objective of this protocol is to outline the methodological approach for analyzing data from observational studies and randomized controlled trials to investigate reasons for the failure of dental crowns in primary teeth and to compute their survival and failure rates.

METHODS

A comprehensive literature review will be performed in electronic databases, including PubMed (MEDLINE), Cochrane, Embase, and Web of Science. As per predefined inclusion criteria, we will include observational studies (prospective clinical studies) and randomized clinical trials that have an English abstract and involve children aged 1-10 years undergoing crown restorations. Two independent reviewers will independently screen all retrieved records and full-text articles and extract data. The study's methodological quality will be appraised using suitable tools. Assessments of publication bias will be performed using funnel plots. The findings will be described qualitatively for the systematic review. If possible, a meta-analysis will be performed to estimate failure rates by dividing the number of failures by the total exposure time. A Poisson regression model, assuming constant event rates, will be used to compute 3-year and 5-year survival proportions. The Pearson goodness-of-fit statistics will be used to assess the heterogeneity of the model. A P value <.05 will be considered significant. All analyses will be performed using R Statistical software (version 4.1.2; R Core Team).

RESULTS

This systematic review and synthesis aim to assess the survival and failure rates of dental crowns in pediatric dentistry. By following this rigorous methodology, we seek to provide valuable insights into the factors contributing to the success or failure of these restorations. The results of our full review will have implications for pediatric dentists, researchers, and policy makers, helping to improve dental care for children.

CONCLUSIONS

This systematic review protocol helps in establishing a thorough approach for reviewing failures in pediatric crowns. By following this methodology, standardization and transparency of the process as well as accountability for the stated methods and outcomes will be ensured. The findings of this review and analysis will provide useful data on the survival of crowns to pediatric dentists and researchers.

TRIAL REGISTRATION

PROSPERO CRD42023442266; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=442266.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/51505.

Clinical and radiographic outcomes of implant-supported zirconia fixed dental prostheses with cantilever extension: A proof-of-principle study with a follow-up of at least 1 year

OBJECTIVES

To test the reliability of full zirconia implant-supported fixed dental prostheses with cantilever extension (FDPCs) after at least 1 year of function.

MATERIALS AND METHODS

Thirty-five patients in need of implant-supported single unit crowns (SUC) and FDPCs in posterior areas were enrolled. After implant placement, patients were rehabilitated with screw-retained full-zirconia FDPCs. Implant survival rate, pocket probing depth (PPD), presence/absence of bleeding on probing (BoP), and presence/absence of mechanical/technical complications were recorded. Mesial and distal radiographic marginal bone levels (mBLs) from baseline (i.e., recall appointment 3-6 months after implant loading [T0]) to the follow-up examination (i.e., latest recall appointment after at least 12 months after T0 [T1]), were calculated.

RESULTS

Thirty patients with 34 FDPCs (31 SUCs and 3 FDPs) supported by 37 implants were available for analysis after a mean loading time of 2.6 ± 1.5 years (range: 13-87 months). No implants were lost. MBLs and mean PPD values did not change statistically significantly from T0 to T1 from 0.92 mm ± 0.42 to 0.96 mm ± 0.38 (95% CI: -0.07/0.17; p = .418) and from 2.99 mm ± 0.70 to 3.27 mm ± 0.71 (95% CI: -0.11/0.68; p = .25) respectively. Peri-implant mucositis was diagnosed in 22 cases. Screw-loosening and zirconia chipping occurred 1× in 4 patients.

CONCLUSION

Within the limitations of the present proof-of-principle study, the use of full-zirconia FDPCs in posterior areas seems a valid and safe short-term treatment option.

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.

Clinical and radiographic outcomes of zirconia dental implants-A systematic review and meta-analysis

OBJECTIVES

For the present review, the following focused question was addressed: In patients with root-analog dental implants, what is the effect of implants made of other materials than titanium (alloy) on implant survival, marginal bone loss (MBL), and technical and biological complications after at least 5 years.

MATERIALS AND METHODS

An electronic (Medline, Embase, Web of Science) search was performed to identify observational clinical studies published from January 2000 investigating a minimum of 20 commercially available zirconia implants with a mean follow-up of at least 60 months. Primary outcome was implant survival, secondary outcomes included peri-implant MBL, probing depths (PDs), and technical and biological complications. Meta-analyses were performed to evaluate implant survival, MBL, and PD.

RESULTS

From 5129 titles, 580 abstracts were selected, and 111 full-text articles were screened. Finally, 4 prospective and 2 retrospective observational clinical cohort studies were included for data extraction. Meta-analyses estimated after 5 years of loading mean values of 97.2% (95% CI 94.7-99.1) for survival (277 implants, 221 patients), 1.1 mm (95% CI: 0.9-1.3) for MBL (229 implants, 173 patients), and 3.0 mm (95% CI 2.5-3.4) for PDs (231 implants, 175 patients).

CONCLUSIONS

After 5 years, commercially available zirconia implants showed reliable clinical performance based on survival rates, MBL, and PD values. However, more well-designed prospective clinical studies and randomized clinical trials investigating titanium and zirconia implants are needed to confirm the presently evaluated promising outcomes.

Long-Term Effect of Guided Implant Surgery on Clinical Outcomes and Peri-Implantitis of Maxillary Implants-An Observational Cohort Study

(1) Although the accuracy of static computer-aided implant surgery (sCAIP) is well reported, information on its long-term effect on peri-implant health and complications is scarce. (2) Twenty-six patients initially treated were recalled. Implant survival, radiographic bone level, peri-implant health, and complications were registered. A multilevel regression model was applied to study the relationship between the research variables. (3) Sixteen patients participated in this study (average age 58.5 years; range 27.8-73.8). The mean follow-up time was 9.1 years (range 7.3-11.3). Two implants failed, resulting in a survival rate of 97.1%. The mean bone level change corresponded to a loss of 0.63 mm (SD 1.90) for the whole group, 0.17 mm (SD 1.46), and 0.91 mm (SD 2.09) for tooth- and mucosa-supported guides, respectively. The mean PPD for the total group was 4.24 mm (SD 1.25), and 3.79 mm (SD 0.97) and 4.51 mm (SD 1.33) for the tooth- and mucosa-supported guides, respectively. Four implants (6.3%) were diagnosed with peri-implantitis. Coronal deviation was slightly associated with having a negative impact on bone level at follow-up, but this was not statistically significant. Seven patients (43.8%) experienced technical complications. Biological complications were seen in 3/16 patients (18.75%). (4) SCAIP may contribute to more predictable implant placement; the long-term clinical outcome is similar to conventional nonguided surgery.

Incidence of Peri-Implantitis, Technical and Biological Complications of Single Implants Placed with Flap or Flapless Surgery-A 10-12-Year Case-Series

BACKGROUND

Long-term follow-up of single implants and crowns is scarce, especially when inserted using flapless surgery.

AIM

Evaluate survival, peri-implantitis incidence, and technical/biologic complications of solitary implants/crowns after 10-12 years of function.

MATERIAL AND METHODS

49 patients with 53 single implants, initially operated with a one-stage flap (F) or flapless (FL) surgery and delayed loading, were recalled. Implant survival, radiographic bone-level changes compared to baseline, peri-implant health, and soft tissue aesthetics were registered. Differences in implant level between and within groups were statistically tested using the Mann-Whitney U-Test and Wilcoxon Signed Ranks Test, respectively.

RESULTS

36 patients with 40 implants were reassessed, yielding 100% implant and 97.5% crown survival. The bone loss in F (n = 19) was 0.56 mm (SD 0.89; range -0.9-2.02) and -0.85 mm (SD 0.98; range -2.84-0.53) in FL (n = 21), indicative of bone gain in FL (p = 0.003), the latter due to a difference at baseline but bone-level was comparable (p = 0.126). Groups were comparable for probing pocket depth (PPD); (3.32 vs. 3.19 mm), Bleeding Index (BI); (0.15 vs. 0.22), and gingival recession; (0.38 vs. 0.17 mm). According to international criteria, the peri-implantitis incidence was 0%, but 32.5% of the implants/crowns experienced biological or technical complications irrespective of surgical technique.

CONCLUSIONS

Solitary implants and crowns show good long-term clinical outcomes and peri-implant health. Flapless surgery is a good alternative to conventional in straightforward cases with sufficient bone volume and proper treatment planning.

Survival rates, patient satisfaction, and prosthetic complications of implant fixed complete dental prostheses: a 12-month prospective study

PURPOSE

To determine the survival rate, incidence of prosthetic complications, and patient satisfaction of implant fixed complete dental prostheses (IFCDPs) after a mean observation period of 1.4 years.

MATERIALS AND METHODS

Twenty-eight (28) eligible participants were recruited according to specific inclusion and exclusion criteria. The definitive metal-acrylic resin IFCDPs consisted of titanium bars veneered with acrylic resin and acrylic denture teeth. Prosthodontic complications, divided into major and minor, were monitored. Parameters such as gender, jaw location, bruxism, and occlusal scheme were evaluated. Moreover, a questionnaire was administered throughout the study to assess patient satisfaction. Poisson regression as well as repeated measures ANOVA were used for statistical analysis.

RESULTS

Fourteen (14) males and 14 females were enrolled and followed-up at 3, 6, and 12 months. All IFCDPs survived (100% survival rate). The most frequent minor complication was the loss of material used to close the screw access hole (20% out of total complications). The most frequent major complication was chipping of the acrylic denture teeth (77.14% out of total complications). Gender (p = 0.008) and bruxism (p = 0.030) were significant predictors for the total major complications (major wear and major chipping) while occlusal scheme was a significant predictor for major chipping events (p = 0.030).

CONCLUSIONS

While IFCDPs demonstrated high prosthetic survival rates, they also exhibited a high number of chipping events of the acrylic veneering material, especially in males, bruxers, and individuals with canine guidance occlusion. However, the occurrence of these prosthetic complications did not negatively affect patient satisfaction.

Technical Complications of Removable Partial Dentures in the Moderately Reduced Dentition: A Systematic Review

The aim of this study was to conduct a systematic literature review with a subsequent meta-analysis on the technical complications and failures of removable partial denture (RPD) therapy in the moderately reduced dentition. A systematic literature search of established medical databases, last updated 06/2022, was conducted. RCTs and prospective and retrospective studies were included that had information on technical complications and failures of RPDs, at least 15 participants, an observation period of at least two years and a drop-out rate of less than 25%. Publications were selected on the title, abstract and full-text level by at least three of the participating authors. The evidence of the included studies was classified using the GRADE system. The bias risk was determined using the RoB2 tool and the ROBINS-I tool. Of 19,592 initial hits, 43 publications were included. Predominantly, retention of the prosthesis, retention loss of anchor crowns (decementations), fractures/repairs of frameworks, denture teeth, veneering or acrylic bases, and a need for relining were reported depending on prosthesis type and observation time. Focusing on technical complications and failures, only very heterogeneous data were found and publications with the highest quality level according to GRADE were scarce. Whenever possible, data on technical complications and failures should be reported separately when referencing the tooth, the prosthesis and the patient for comparability. Prostheses with differing anchorage types should be analyzed in different groups, as the respective complications and failures differ. A precise description of the kinds of complications and failures, as well as of the resulting follow-up treatment measures, should be given.

Five-year randomized controlled clinical study comparing cemented and screw-retained zirconia-based implant-supported single crowns

Objectives

To compare screw‐retained and cemented all‐ceramic implant‐supported single crowns regarding biological and technical outcomes over a 5‐year observation period.

Materials and methods

In 44 patients, 44 two‐piece dental implants were placed in single‐tooth gaps in the esthetic zone. Patients randomly received a screw‐retained (SR) or cemented (CR) all‐ceramic single crown and were then re‐examined annually up to 5 years. Outcome measures included: clinical, biological, technical, and radiographic parameters. Data were statistically analyzed with Wilcoxon–Mann–Whitney, Wilcoxon, and Fisher's exact tests.

Results

During the observation period, three patients (6.8%) were loss to follow‐up. Eight restorations (18.2%, CI (8.2%, 32.7%)) were lost due to technical (6 patients, 13.6% (CI (5.2%, 27.4%)), 2 CR and 4 SR group, intergroup p = .673; implants still present) or biological complications (2 patients, 4.5% (CI (0.6%, 16.5%)), only CR group, intergroup p = .201, both implants lost). This resulted in a survival rate of 81.2% (CI (65.9%, 90.1%)) on the restorative level (18 SR; 15 CR, 3 lost to follow‐up). At the 5‐year follow‐up, the median marginal bone levels were located slightly apical relative to the implant shoulder with 0.4 mm (0.5; 0.3) (SR) and 0.4 mm (0.8; 0.3) (CR) (intergroup p = .582). Cemented restorations demonstrated a significantly higher biological complication rate (36.8%, SR: 0.0%; intergroup p = .0022), as well as a significantly higher overall complication rate (68.4%, SR: 22.7%, intergroup p = .0049). All other outcomes did not differ significantly between the two groups (p > .05).

Conclusions

All‐ceramic single‐tooth restorations on two‐piece dental implants resulted in a relatively low survival rate. Cemented restorations were associated with a higher biological and overall complication rate than screw‐retained restorations.

Health economic aspects of implant-supported restorative therapy

BACKGROUND

It is poorly understood how much additional dental care patients consume subsequent to implant therapy. The aim of the present study is to evaluate costs associated with implant-supported restorative therapy during the long-term follow-up.

MATERIAL AND METHODS

Costs associated with preventive measures and complication-related procedures over a mean follow-up period of 8.2 years were assessed in patient files of 514 Swedish subjects provided with implant-supported restorative therapy. The restorative therapy and each of the subsequent interventions were assigned a specific cost. Accumulated costs were calculated in three categories: (i) total cost including initial restorative therapy and complication-related interventions, (ii) cost of preventive measures alone, and (iii) cost of complication-related procedures alone. Potential differences by background variables were analyzed using growth curve models.

RESULTS

In the whole sample, costs during follow-up ranged from 878 € (95% CI 743; 1,014) for patients with single-tooth restoration(s) to 1,210 € (95% CI 1,091; 1,329) for subjects with full-jaw restoration(s). The majority of costs during follow-up originated from preventive measures (741 € 95% CI 716; 766). Among individuals receiving ≥1 intervention dealing with a complication (n = 253), complication-related costs amounted to 557 € (95% CI 480; 634). For patients with full-jaw restorations, the corresponding amount was 769 € (95% CI 622; 916). Procedures related to peri-implantitis and technical complications resulted in costs similar to each other. Implant loss generated greater costs than any other type of complication.

CONCLUSIONS

Costs related to implant-supported restorative therapy during follow-up were associated with the extent of initial therapy. The higher costs during follow-up noted in patients provided with full-jaw restorations were explained by complication-associated procedures. Implant loss was the most costly type of complication.

Occurrence and clustering of complications in implant dentistry

OBJECTIVES

The aim was to evaluate the overall occurrence and potential clustering of biological and technical complications in implant dentistry.

MATERIAL AND METHODS

596 patients provided with implant-supported reconstructions were evaluated for the occurrence of (a) technical complications, (b) peri-implantitis and (c) implant loss during a period of 9 years. Time and type of event were scored, and potential risk factors were explored through parametric modelling of survival and hazards. Clustering of complications was assessed at the patient level, and patient satisfaction was evaluated by questionnaire completed at the 9-year examination.

RESULTS

42% of patients were affected by technical and/or biological complications during the 9-year observation period. Extent of therapy (Hazard Ratio 2.5: patients with partial jaw restorations; HR 3.9: patients with full jaw restorations) and a history of periodontitis (HR 1.6) were identified as risk factors. While technical complications occurred mostly as isolated events, 41% of subjects identified with peri-implantitis and 52% of subjects with implant loss also presented with other complications. The hazard for technical complications and implant loss peaked at 0.7 years and 0.2 years, respectively, while the hazard for peri-implantitis was consistent throughout the observation period. The overall proportion of satisfied patients at 9 years was high (95%), and only minor differences between individuals with and without complications were noted.

CONCLUSIONS

Complications following implant-supported restorative therapy were common findings. Extent of therapy and periodontitis were identified as risk factors. While technical complications occurred in an isolated pattern, peri-implantitis and implant loss demonstrated clustering with other types of complications.

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.

Prosthesis Survival Rates and Prosthetic Complications of Implant-Supported Fixed Dental Prostheses in Partially Edentulous Patients

PURPOSE

To determine the prevalence and distribution of prosthetic complications affecting implant-supported fixed dental prostheses (ISFDPs).

MATERIALS AND METHODS

Subjects previously treated with one or more ISFDP(s) were identified from an electronic health record search and recalled for comprehensive clinical examination. Past prosthesis failures and complications were identified from the patient records while any existing complications, not previously recorded, were assessed during examination. ISFDP survival and failure rates were calculated with Kaplan-Meier curves and life table analysis, while regression Poisson analysis was used to identify associations between outcomes and possible patient- and prosthesis-based risk factors.

RESULTS

Seventy-four subjects with 107 ISFDPs were enrolled in the study with a mean time between prosthesis delivery and exam of 3.14 years (range: 1.00-9.00 years). Four prostheses failed, resulting in a cumulative prosthesis survival rate of 96.26%. Prosthetic complications affected 48.59% of ISFDPs, the majority (94.87%) of them minor complications. Only the use of a nightguard was associated with a lower prevalence of prosthetic screw loosening (HR 0.11, 95% CI 0.02-0.59, p = 0.007) while no outcome differences were noted for other variables. Patient satisfaction was high regardless of presence or number of complications.

CONCLUSIONS

ISFDPs demonstrated a high survival rate and overall high, patient-reported satisfaction. Minor prosthetic complications were common but were only significantly associated with nightguard use.

Zirconia-ceramic versus metal-ceramic posterior multiunit tooth-supported fixed dental prostheses: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

The authors aimed to compare the survival and complication rates of zirconia-ceramic (ZC) versus metal-ceramic (MC) restorative material in multiunit tooth-supported posterior fixed dental prostheses (FDP).

TYPES OF STUDIES REVIEWED

The authors conducted a systematic search of randomized controlled trials (RCTs), with no time or language restrictions, up to May 2019 using the MEDLINE (PubMed), Scopus, Web of Science, and Cochrane Central Register of Controlled Trials databases, followed by a manual search.

RESULTS

The authors included 7 RCTs in the review and 5 RCTs in the meta-analysis. All studies had a low risk of bias. The authors included 330 participants (177 ZC and 173 MC tooth-supported FDP) in the meta-analysis, which revealed a medium-term survival rate of 95.4% (95% confidence interval [CI], 90.5% to 99.1%) for ZC FDP compared with 96.9% (95% CI, 94.3% to 99.4%) for MC FDP, with no significant differences (P = .364). The biological or technical complications did not show statistically significant differences, except in the global ceramic veneering chipping analysis (P = .023; risk difference [RD], 22.3%; 95% CI, 3.0% to 41.6%) and their subanalysis: minor chipping or chipping that can be solved with polishing (P = .044; RD, 19.5%; 95% CI, 0.5% to 38.4%), and major chipping or chipping that needs repair in the laboratory (P = .023; RD, 6.0%; 95% CI, 0.8% to 11.3%).

CONCLUSIONS AND PRACTICAL IMPLICATIONS

Posterior multiunit ZC restorations are considered a predictable treatment in the medium term, although they are slightly more susceptible to chipping of the veneering ceramic than MC restorations.

Complications of screw- and cement-retained implant-supported full-arch restorations: a systematic review and meta-analysis

PURPOSE

To assess the technical and biological complications of screw- and cement-retained implant-supported full-arch dental prostheses.

MATERIALS AND METHODS

An electronic search was conducted on Medline/PubMed and Cochrane databases in February 2019; irrespective of any time restrictions using MeSH terms. All studies were first reviewed by abstract and subsequently by full-text reading. Further hand search was performed to identify other related references. Articles only related to cement-retained and/or screw-retained reconstructions in full-arch fixed dental prostheses (FDP) were included.

RESULTS

The initial literature search resulted in 3670 papers. 3478 articles remained after removing duplicate articles, and 3439 articles were further excluded by the reviewers after the abstract screening, which resulted in a selection of 39 studies. 12 studies were further excluded due to not fulfilling the inclusion criteria. Hand searching resulted in two additional papers being included, and finally, 29 articles were included in this review. Screw-retained full-arch fixed dental prostheses have fewer complications than cemented reconstructions. Biological complications such as marginal bone loss > 2 mm occurred more frequently in cemented reconstructions, and technical complications such as screw-loosening and screw fracture occurred more in screw-retained reconstructions.

CONCLUSION

Cemented reconstructions exhibited more biological complications (implant loss, bone loss > 2 mm) and screw-retained prostheses exhibited more technical problems. Clinical outcomes were influenced by both fixations in different ways. The screw-retained restorations were more easily retrievable than cemented ones, therefore, technical and eventually biological complications could be treated more easily. For this reason, and for their higher biological compatibility, these reconstructions are preferable.

Excessive occlusal load on chemically modified and moderately rough titanium implants restored with cantilever reconstructions. An experimental study in dogs

OBJECTIVE

To evaluate the outcomes of excessively loaded implants.

MATERIAL AND METHODS

In five dogs, all mandibular premolars were extracted. After 3 months, six implants (three SLA® and three SLActive®) were placed (S). After 4 weeks, implants were restored: one single crown with stable occlusal contacts (SC), one crown and a cantilever unit with excessive occlusal contacts (OL), and a non-loaded implant (NL). Bleeding-on-probing (BoP), attachment level (AL), mucosal margin (GM) were assessed. Resonance frequency analysis (RFA) was assessed weekly. Standardized X-rays were taken at S, 4 and 24 weeks.

RESULTS

Similar findings were observed for SLA® and SLActive® implants regarding PlI, GI, GM, AL, and BL. No significant differences were detected between baseline and 24-weeks or between treatment modalities for all clinical parameters (p > .05). Six months after loading, RFA values were significantly greater than at implant placement. No significant differences between treatment modalities were found. Linear radiographic measurements yielded similar results between SLA® and SLActive® implants. SLA® OL implants yielded a statistically significant gain on peri-implant bone density over all other groups (p = .012). Radiographic results were confirmed by descriptive histology. Technically, loosened occlusal screws occurred in 13.3% (SC = 3.3%; OL = 10%), while abutment fractures totalized 23.3% (SC = 6.6%; OL = 16.6%).

CONCLUSIONS

Excessive occlusal load applied to implants (SLA® or SLActive®) restored with cantilevers did not cause loss of osseointegration or significant changes in their clinical, radiographic, or histologic outcomes. Early excessive occlusal load on SLA® implants promoted a gain in peri-implant bone density. Excessively loaded implants showed more technical complications.

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.

Is there an effect of crown-to-implant ratio on implant treatment outcomes? A systematic review

OBJECTIVES

High crown-to-implant ratios may lead to complications due to unfavorable occlusal forces, including nonaxial forces, on the bone surrounding the neck of the implant and within the connection of the crown and implant itself. The aim of this study was to perform a systematic review on the influence of crown-to-implant ratio of single-tooth, nonsplinted, implants on biological and technical complications.

MATERIALS AND METHODS

MEDLINE (1950-January 2018), EMBASE (1966-January 2018), and Cochrane Central Register of Controlled Trials database (1800-January 2018) were searched to identify eligible studies. Inclusion criteria were as follows: crown-to-implant ratio of single-tooth, nonsplinted, implant-supported restorations in the posterior maxilla or mandible and follow-up of at least 1 year. Main outcome measures were as follows: implant survival rate, marginal bone level changes, biological complications, and technical complications. Two reviewers independently assessed the articles. A meta-analysis was carried out for implant survival rate and peri-implant bone changes.

RESULTS

Of 154 primarily selected articles, eight studies fulfilled the inclusion criteria. Study groups presented a mean crown-to-implant ratio varying from 0.86 (with 10-mm implants) to 2.14 (with 6-mm implants). The meta-analysis showed an implant survival of more than 99% per year and mean peri-implant bone changes of <0.1 mm per year. Limited biological and technical complications were reported.

CONCLUSION

Data reviewed in the current manuscript on crown-to-implant ratio, ranging from 0.86 to 2.14, of single-tooth, nonsplinted, implants did not demonstrate a high occurrence of biological or technical complications.

Double Full-Arch Fixed Implant-Supported Prostheses: Outcomes and Complications after a Mean Follow-Up of 5 Years

PURPOSE

To retrospectively assess complications and clinical and radiographic outcomes of edentulous patients treated with double full-arch implant-supported fixed complete dental prostheses (IFCDPs) after a mean observation period of 5.1 years.

MATERIALS AND METHODS

The single-visit clinical and radiographic examination included medical and dental history review and clinical assessment of biologic and technical complications encountered with all implants and IFCDPs. Life table analysis and Kaplan-Meier survival curves were calculated. Analysis was conducted to evaluate the association between prosthesis survival and several risk factors such as type of opposing occlusion, nightguard use, and presence of bruxism.

RESULTS

Nineteen edentulous patients restored with 38 IFCDPs were included. A total of 249 implants were placed and 2 implants failed after a mean observation period of 5.1 years (range: 1-12 years), yielding an overall implant survival rate of 99.2% and prosthesis survival rate of 92.1%. Three out of 38 IFCDPs were lost, 1 after implant losses and 2 due to technical complications. The most frequent minor biologic complication was soft tissue recession with an estimated 5-year rate of 45.5% (95% CI: 39.4-57.5), while the most frequent major complication was peri-implantitis with an estimated 5-year implant-based rate of 9.5% (95% CI: 6.7-11.3). The most frequent minor technical complication was wear of the prosthetic material with an estimated 5-year rate of 49.0% (95% CI: 37.4-76.4), while the most frequent major technical complication was fracture of the prosthetic material with an estimated 5-year dental unit-based rate of 8.0% (95% CI: 6.6-10.1).

CONCLUSIONS

After a mean use time of 5.1 years, high implant and prosthesis survival rates were observed. The most frequent major biologic complication was peri-implantitis, and the most frequent major technical complication was fracture of the prosthetic material. The 5-year estimated cumulative rates for "prosthesis free of biologic complications" was 50.7% (95% CI: 33.7-65.4) and for "prosthesis free of technical complications" was 57.1% (95% CI: 39.3-71.5).

Material-related complications in implant-supported fixed dental restorations. A systematic review

AIM

A large variety of dental materials are available for the production of implant-supported fixed restorations. Materials with different properties are likely to behave differently during clinical function, which may result in different prevalence and types of complications. The aim of the present review was to summarise, analyse and discuss the prevalence and types of complications or failures related to dental materials in implant-supported restorations.

MATERIALS AND METHODS

A strategy was set up using the PICO format and the search was performed using the PubMed database, including a hand search of reference lists. Two independent reviewers selected papers based on a set of criteria. The number of events of complications was summarised.

RESULTS

The initial search produced 2764 titles. After application of criteria, 47 publications were selected for analysis. Seventeen studies reported on 1447 single crowns and 30 studies reported on 2190 fixed dental prostheses. The most common complications were fracture or chipping of the veneer material, loss of retention and lost access hole fillings. Due to the heterogeneity of studies, and large variation in number of restorations per material group, no conclusive correlation between type of material and type of technical complication and/or failure could be established.

CONCLUSIONS

The review did not succeed in providing convincing evidence to answer the question concerning a possible relationship between restoration materials and prevalence of technical complications in implant-supported restorations.

Frequency of Prosthetic Complications Related to Implant-Borne Prosthesis in a Sleep Disorder Unit

Sleep bruxism and higher clench index have been associated with obstructive sleep apnea (OSA). However, there is no study that reports on the prosthetic complications in patients with OSA. Records of patients who had performed a sleep study to diagnose OSA were examined for the occurrence of prosthetic complications in implant-borne reconstructions. The primary outcome was the frequency of prosthetic complications. The secondary outcomes were anthropometric data, type of complication, type of prosthesis, type of retention, number of supporting implants, number of prosthetic units, and the presence of obstructive sleep apnea. Of the 172 patients, 67 had an implant-supported prosthesis, and all were included in the study. The mean age was 61 ± 10 years, and 36 were female. Thirty complications in 22 prostheses were identified in 16 patients. The complications were porcelain fracture (14 events), screw/implant fracture (8 events), screw loosening (3 events), and decementation (5 events). The follow-up time was 117 ± 90 months after placement of the prosthesis. The average time for complications to occur was 73 ± 65 months after the placement of the prosthesis. According to the apnea-hypopnea index (AHI), 49 patients had OSA. Thirteen of the 16 patients having a prosthetic complication also had OSA. The highest AHI and thus the severity of OSA was identified in patients with a fracture complication related to an implant, a screw, or a porcelain. The frequency of prosthetic complications has been higher in patients with obstructive sleep apnea.

Survival and complication rates of fixed restorations supported by locking-taper implants: a prospective study with 1 to 10 years of follow-up

PURPOSE

The aim of this 10-year follow-up study was to evaluate the implant survival and complication rates of fixed restorations supported by locking-taper implants.

MATERIALS AND METHODS

Over a 10-year period (January 2002 to December 2011) all patients referred to a single private practice for treatment with fixed restorations (single crowns, SCs; fixed partial prostheses, FPPs; fixed full arches, FFAs) supported by dental implants were considered for inclusion in the study. At each annual follow-up session, clinical, radiographic, and prosthetic parameters were assessed. The surviving implant-supported restorations were defined as "complication free" in the absence of any biological or prosthetic (mechanical or technical) complication. The cumulative implant survival and the "complication-free" survival of fixed implant-supported restorations were identified using the Kaplan-Meier method. The Log-rank test was used to identify correlations between the study variables.

RESULTS

In total, 1494 locking-taper implants (727 maxilla, 767 mandible) were placed in 642 patients (356 males, 286 females). Nineteen implants (12 maxilla, 7 mandible) failed. Implant failures were attributed to lack of osseointegration (14 implants), peri-implantitis (4 implants), and mechanical overloading (1 implant). An overall 10-year cumulative implant survival rate of 98.7% (98.3% maxilla, 99.1% mandible) was found. The implant survival rates did not significantly differ with respect to implant location, position, bone type, implant length and diameter, and type of restorations. Among the surviving implant-supported restorations (478 SC, 242 FPP, 19 FFA), a few biological (11/739: 1.4%) and prosthetic (27/739: 3.6%) complications were reported. The incidence of mechanical complications was low (3/739: 0.4%), with three loosened abutments in three SCs (3/478: 0.6%), and no abutment fractures; technical complications were more frequent (24/739: 3.2%), with an incidence of decementation of 2.0% (SC 2.0%, FPP 1.6%, FFA 5.2%) and ceramic/veneer chipping/fracture of 1.2% (SC 0.0%, FPP 2.8%, FFA 10.5%). A 10-year cumulative "complication-free" survival of restorations of 88.6% (SC 91.7%, FPP 83.1%, FFA 73.8%) was reported. The complication rates differ significantly with respect to the type of restoration (p < 0.05).

CONCLUSIONS

Fixed restorations on locking-taper implants seem to be a successful procedure for the rehabilitation of partially and completely edentulous arches.

Long-term outcomes of dental implants with a titanium plasma-sprayed surface: a 20-year prospective case series study in partially edentulous patients

BACKGROUND

Long-term studies of ≥10 years are important milestones to get a better understanding of potential factors causing implant failures or complications.

PURPOSE

The present study investigated the long-term outcomes of titanium dental implants with a rough, microporous surface (titanium plasma sprayed [TPS]) and the associated biologic and technical complications in partially edentulous patients with fixed dental prostheses over a 20-year follow-up period.

MATERIALS AND METHODS

Sixty-seven patients, who received 95 implants in the 1980s, were examined with well-established clinical and radiographic parameters. Based on these findings, each implant was classified as either successful, surviving, or failed.

RESULTS

Ten implants in nine patients were lost during the observation period, resulting in an implant survival rate of 89.5%. Radiographically, 92% of the implants exhibited crestal bone loss below 1 mm between the 1- and 20-year follow-up examinations. Only 8% yielded peri-implant bone loss of >1 mm and none exhibited severe bone loss of more than 1.8 mm. During the observation period, 19 implants (20%) experienced a biologic complication with suppuration. Of these 19 implants, 13 implants (13.7%) had been treated and were successfully maintained over the 20-year follow-up period. Therefore, the 20-year implant success rate was 75.8 or 89.5% depending on the different success criteria. Technical complications were observed in 32%.

CONCLUSION

The present study is the first to report satisfactory success rates after 20 years of function of dental implants with a TPS surface in partially edentulous patients.

The impact of cantilevers on biological and technical success outcomes of implant-supported fixed partial dentures. A retrospective cohort study

OBJECTIVE

To investigate the biological and technical success outcomes of implant-supported fixed dental prostheses with and without cantilevers, after a minimum of one year loading.

MATERIAL AND METHODS

One hundred and seven subjects with 128 cantilever FDPs (cFDP) supported by 132 implants were compared with 99 individuals with 144 non-cantilever FPDs (ncFDPs) supported by 203 implants. Outcomes such as marginal bone loss from FDP insertion to final follow-up as well as frequency and extent of biological and technical complications were investigated and correlated with patient, site, implant and FDP design characteristics.

RESULTS

The cFDPs were followed for average of 51 months (1551 days, SD ± 977), and ncFPDs for 49 months (1483 days, SD ± 809 days). Implant survival and success rates were 96.7% and 87.9% for implant supporting cFDPs, and 99.5% and 92.6% for ncFDPs. There was no significant difference in overall bone loss between cFDPs and ncFDPs (cantilever side: 0.58, SD ± 1.16 - non-cantilever side: 0.59, SD ± 0.99), but implants in the cantilever group lost significantly more bone in the posterior mandible (0.50 SD ± 1.3 mm for cFDPs and 0.24 SD ± 0.80 mm for ncFDPs). Within the cantilever group, cantilever arm length and implant location had an influence on bone loss. Regardless of the presence of cantilever, implants associated with technical complications had a higher rate of biological complications as well. Furthermore, the length of the cantilever arm was positively correlated with implant failure, technical complications and bone loss ≥1.5 mm (P = 0.011, <0.001, and 0.007).

CONCLUSION

Overall implants can be successfully used to support cantilever FDPs. However, there are technical and biological implications which appear inter-related.