Objective
This retrospective analysis was designed to compare the survival and success of dental implants in solely implant‐supported, double crown‐retained removable dentures (DCRDs) and combined ...tooth–implant‐supported DCRDs, due to a lack of data on the latter.
Material and methods
From 2002, patients were consecutively admitted for treatment at the Department of Prosthodontics, University of Heidelberg. Surgical and prosthodontic treatment and scheduled and unscheduled visits were recorded on standardized documentation forms. Kaplan–Meier analysis was used to estimate success (survival without major complications). Cox regression was applied to assess risk factors.
Results
From this clinical study, 139 DCRDs on 412 implants and 239 teeth met the inclusion criteria. Fifty‐three dentures were implant‐supported (213 implants). Eighty‐six were supported by teeth and implants. The DCRDs were placed in 126 patients. After an observation period of up to 11.2 years (median: 4.2 years), total implant survival was 99.5% for tooth–implant‐supported DCRDs and 93.4% for implant‐supported ones. The estimated cumulative success was 97.2% (standard error/SE ± 1.2%) and 85.9% (SE ± 2.4%) at five years, respectively. Complications included implant or tooth loss, peri‐implantitis, apical periodontitis and tooth fracture. In terms of abutments, results from multiple Cox regression revealed lower failure rates in tooth–implant‐supported dentures (p = .04). No other risk factors were identified.
Conclusions
Within the limitations of this study, survival and success are high for both treatment options. Combining teeth and implants in one DCRD might have a positive effect on the prognosis of the implant and the survival of remaining teeth.
Objectives
To investigate the long‐term performance, over a period of up to 11 years, of tooth–implant‐supported and solely implant‐supported double‐crown‐retained overdentures (DCRDs) for complete ...restoration of the jaw.
Materials and methods
Between 2002 and 2015, patients were consecutively enrolled in the study at Heidelberg University Hospital's Department of Prosthodontics. Scheduled and unscheduled visits were both documented on standardized forms. Kaplan–Meier curves were used to evaluate survival and success of the DCRDs. Mixed effects Cox regression was used to identify the potential effects of age, sex, jaw, location of implants, and the number of abutment teeth on the success of the DCRDs.
Results
One hundred and thirty‐nine DCRDs were placed in 126 participants (mean age: 65.6 ± 9.1 years; 76 60.3% men). The mean follow‐up period was 4.2 years. Fifty‐three (38%) DCRDs were solely implant‐supported (213 implants) and 86 (62%) were tooth–implant‐supported (239 teeth and 199 implants). Cumulative five‐year survival was 96.2% in the implant‐supported group and 97.7% in the tooth–implant‐supported group. Simultaneous consideration of failures and severe complications revealed cumulative five‐year success of 88.2% for implant‐supported DCRDs and 81.9% for tooth–implant‐supported DCRDs, with no significant difference between the two types of restoration. Cox regression analysis revealed a greater risk of major complications (hazard ratio: 4.87, p = .04) for maxillary DCRDs than for mandibular DCRDs.
Conclusions
Although the study design has limitations, the results show that tooth–implant‐supported and solely implant‐supported DCRDs are both recommendable treatment options. After a mean follow‐up of 4.2 years, survival and success were high. However, minor complications were common and required much aftercare.
Clinical Trial Registration
This study started in 2005 and was approved by the local review board of the University of Heidelberg. In 2005, clinical trial registration was not yet common. For this reason, the study was not registered.
Purpose
The objective of this work was to evaluate the effect of prosthetic restoration on the survival of implants and on the incidence of implant‐related complications.
Material and methods
From a ...prospectively documented clinical study, 1569 implants placed in 630 patients (mean age 59.56 years) were evaluated. Selection criteria were a conventional loading protocol, prosthetic restoration with at least one follow‐up, and a minimum observation period of 9 months. Implants that failed before prosthetic restoration were excluded. The sample included 1345 tissue‐level implants and 104 bone‐level implants (Straumann), and 120 Replace implants (Nobel Biocare). The observation period ranged between 9 months and 11 years after prosthetic restoration (mean 4.0 years; SD 2.5). The implants were restored with single crowns (n = 557), fixed dental prostheses (n = 594), or removable dental prostheses (RDP) (n = 418). In the RDP group, 356 implants were restored with telescoping crowns, 22 with bar units 24 with bar joints, and 16 with locator attachments. The incidence of implant‐related complications and failures was analyzed by use of Kaplan–Meier survival curves. Cox regression analysis was used to identify possible risk factors.
Results
Twenty‐seven failures (1.8%; loosened or removed implants) were observed after prosthetic restoration; the incidence of failure was 3% for implants placed in males and 1% for implants placed in females. Other factors had no effect on the incidence of failure. Peri‐implantitis (n = 29) and marginal bone loss >2 mm without acute inflammation (n = 6) also resulted in a 4% incidence of severe implant‐related complications (62 of 1569; success 96%). Cox regression analysis revealed combined tooth–implant‐supported restorations as a significant risk‐reducing factor for severe implant‐related complications (hazard ratio, HR = 0.34; P = 0.04). There was, furthermore, a tendency toward a greater incidence of complications for implants restored with RDPs than for single crowns (P = 0.08). Other factors, for example location (anterior/posterior, maxilla/mandible), age, sex, or implant placement combined with bone augmentation, had no significant effect on the incidence of implant‐related complications (P values ranging between 0.16 and 0.94).
Conclusions
The type of support has a small but significant effect on implant prognosis. For detailed analysis of the effects of loading by different types of prosthetic restoration, larger sample sizes are required.
Abstract
Population stratification is usually corrected relying on principal component analysis (PCA) of genome-wide genotype data, even in populations considered genetically homogeneous, such as ...Europeans. The need to genotype only a small number of genetic variants that show large differences in allele frequency among subpopulations—so-called ancestry-informative markers (AIMs)—instead of the whole genome for stratification adjustment could represent an advantage for replication studies and candidate gene/pathway studies. Here we compare the correction performance of classical and robust principal components (PCs) with the use of AIMs selected according to four different methods: the informativeness for assignment measure ($IN$-AIMs), the combination of PCA and F-statistics, PCA-correlated measurement and the PCA weighted loadings for each genetic variant. We used real genotype data from the Population Reference Sample and The Cancer Genome Atlas to simulate European genetic association studies and to quantify type I error rate and statistical power in different case–control settings.
In studies with the same numbers of cases and controls per country and control-to-case ratios reflecting actual rates of disease prevalence, no adjustment for population stratification was required. The unnecessary inclusion of the country of origin, PCs or AIMs as covariates in the regression models translated into increasing type I error rates. In studies with cases and controls from separate countries, no investigated method was able to adequately correct for population stratification. The first classical and the first two robust PCs achieved the lowest (although inflated) type I error, followed at some distance by the first eight $IN$-AIMs.
Abstract
Least absolute shrinkage and selection operator (LASSO) regression is often applied to select the most promising set of single nucleotide polymorphisms (SNPs) associated with a molecular ...phenotype of interest. While the penalization parameter λ restricts the number of selected SNPs and the potential model overfitting, the least-squares loss function of standard LASSO regression translates into a strong dependence of statistical results on a small number of individuals with phenotypes or genotypes divergent from the majority of the study population—typically comprised of outliers and high-leverage observations.
Robust methods have been developed to constrain the influence of divergent observations and generate statistical results that apply to the bulk of study data, but they have rarely been applied to genetic association studies. In this article, we review, for newcomers to the field of robust statistics, a novel version of standard LASSO that utilizes the Huber loss function. We conduct comprehensive simulations and analyze real protein, metabolite, mRNA expression and genotype data to compare the stability of penalization, the cross-iteration concordance of the model, the false-positive and true-positive rates and the prediction accuracy of standard and robust Huber-LASSO.
Although the two methods showed controlled false-positive rates ≤2.1% and similar true-positive rates, robust Huber-LASSO outperformed standard LASSO in the accuracy of predicted protein, metabolite and gene expression levels using individual SNP data. The conducted simulations and real-data analyses show that robust Huber-LASSO represents a valuable alternative to standard LASSO in genetic studies of molecular phenotypes.
To evaluate the long-term survival, incidence of prosthetic/technical and biological complications and the oral-health-related quality of life in patients with an edentulous mandible who were fitted ...with overdentures on two immediately loaded implants in the symphyseal area.
Forty-six patients with edentulous mandibles received two immediately loaded implant-retained dentures with either two Locator attachments or egg-shaped bar attachments. Implant outcomes were recorded after a period of observation of 9 years and included prosthetic complications, modified gingiva index (mGI), modified plaque index (mPI), oral health impact profile (OHIP-G) and radiographic estimation of bone loss.
In 2020/2021, 27 patients with 54 implants were still available for follow-up. In total, nine implants in six patients were lost. Survival was 89.1% in the bar group and 91.3% in the Locator group. Implant success was 84.6% in the Locator group and 76.9% in the bar group. The mPI values were significantly higher in the bar group than in the Locator group, whereas no difference was seen in the mGI values. During the observation period, 152 prosthetic complications occurred, but the OHIP-G score did not differ significantly.
There was no difference in implant survival between Locator or joint bar attachments over a 9-year observation period. Joint bar attachments were associated with slightly more complications, while patients in the Locator group were able to maintain better oral hygiene. The study was registered in the German Register of Clinical (Trials DRKS00004245).
Objectives
To determine implant survival and success of four conventionally but initially asynchronously loaded implants in implant‐supported overdentures for the edentulous maxilla, in participants ...with opposing mandibular two‐implant overdentures.
Material and methods
Twenty‐six participants received four implants in the region of the maxillary canines and molars. After healing, 24 of these participants (mean age: 68.3 years) were randomly allocated to one of two treatment groups, and the adapted overdenture was attached to two unsplinted cylindrical attachments. The other two matrixes remained unattached to the implants for 3 months. After this period, the other two implants were loaded for 3 months (cross‐over design). Then, all four implants were loaded for another 3 months. Kaplan–Meier curves were used to evaluate survival and success of implants and dentures.
Results
During the active prosthetic study phase, three participants lost one implant. Two participants lost three implants during the recall period. Implant survival after loading was 93.8% after a mean observation period of 3.1 years. Denture survival was 100%, but denture success was 95.8%, due to major prosthetic complications. Most participants preferred four implants to two.
Conclusions
Within the limitations of the study, it can be concluded that maxillary implant overdentures on two or four implants are both recommendable treatment options. Two posterior implants are not superior to two anterior implants under overdentures retained by unsplinted cylindrical attachments. Implant and prosthetic complications and aftercare measures are common but are mostly easy to handle. However, 23 of the 24 participants preferred the 4‐implant maxillary overdenture.
To identify new tumor‐suppressor gene candidates relevant for human hepatocarcinogenesis, we performed genome‐wide methylation profiling and vertical integration with array‐based comparative genomic ...hybridization (aCGH), as well as expression data from a cohort of well‐characterized human hepatocellular carcinomas (HCCs). Bisulfite‐converted DNAs from 63 HCCs and 10 healthy control livers were analyzed for the methylation status of more than 14,000 genes. After defining the differentially methylated genes in HCCs, we integrated their DNA copy‐number alterations as determined by aCGH data and correlated them with gene expression to identify genes potentially silenced by promoter hypermethylation. Aberrant methylation of candidates was further confirmed by pyrosequencing, and methylation dependency of silencing was determined by 5‐aza‐2′‐deoxycytidine (5‐aza‐dC) treatment. Methylation profiling revealed 2,226 CpG sites that showed methylation differences between healthy control livers and HCCs. Of these, 537 CpG sites were hypermethylated in the tumor DNA, whereas 1,689 sites showed promoter hypomethylation. The hypermethylated set was enriched for genes known to be inactivated by the polycomb repressive complex 2, whereas the group of hypomethylated genes was enriched for imprinted genes. We identified three genes matching all of our selection criteria for a tumor‐suppressor gene (period homolog 3 PER3, insulin‐like growth‐factor–binding protein, acid labile subunit IGFALS, and protein Z). PER3 was down‐regulated in human HCCs, compared to peritumorous and healthy liver tissues. 5‐aza‐dC treatment restored PER3 expression in HCC cell lines, indicating that promoter hypermethylation was indeed responsible for gene silencing. Additionally, functional analysis supported a tumor‐suppressive function for PER3 and IGFALS in vitro. Conclusion: The present study illustrates that vertical integration of methylation data with high‐resolution genomic and transcriptomic data facilitates the identification of new tumor‐suppressor gene candidates in human HCC. (HEPATOLOGY 2012;56:1817–1827)
To evaluate failure rates and incidence of chipping for metal–ceramic and all-ceramic implant-supported single crowns (SCs).
Six hundred and fifty-two implant-supported SCs placed in 404 patients ...(mean age: 57.8 years; 193 male; mean SCs per patient: 1.6) were evaluated up to 12.8 years. The frameworks of the SCs were made from Au alloys (n = 319), CoCr (n = 37), zirconia (n = 286), or lithium disilicate (n = 10). Full-coverage ceramic veneers were placed on 319 Au SCs, 34 CoCr SCs, and 92 zirconia SCs. One hundred and fifty-two monolithic zirconia SCs were not veneered. A partial veneer was placed on the buccal surface only of a further 42 zirconia SCs.
A total of 26 failures were caused by loss of implants (n = 6), ceramic fractures and chipping (n = 15), loosening of the abutment (n = 4), or swallowing of a de-cemented SC (n = 1). Kaplan–Meier analysis revealed a probability of survival of 96% after five years and 92% after 10 years. A greater incidence of failure was observed for lithium disilicate and zirconia SCs than for metal–ceramic SCs (p < .05). Separate analysis of the most frequent complication, chipping (n = 61), revealed that zirconia and lithium disilicate frameworks were significant risk factors for chipping (p < 0.05). Furthermore, a significantly greater incidence of chipping was observed for SCs with full-coverage veneers than for monolithic zirconia SCs and for SCs with partial veneers (p < .05).
Avoidance of full-coverage veneers significantly improves the clinical performance of implant-supported crowns, primarily reduces the incidence of chipping.
Abstract Introduction This cohort study is the second phase of a previously reported trial. The primary aim was to assess the outcome of the treatment of teeth with open apices managed by the ...orthograde placement of mineral trioxide aggregate (MTA) apical plugs. The secondary goal was to identify potential outcome factors for this kind of treatment with a larger sample size and longer follow-up periods than in the first phase of the project. Methods Two hundred twenty-one patients who had been treated between 2000 and 2010 were contacted for follow-up examination 12–128 months after treatment (median, 21 months). At the time of treatment, these patients presented a total of 252 teeth with open apices caused by apical root resorption or excessive apical enlargement or with immature apices. Treatment was performed by supervised undergraduate students (12% of teeth), general dentists (49%), and dentists whose practice was limited to endodontics (39%). The investigated outcome relied on clinical and radiographic criteria and was dichotomized as healed or diseased. Results Of 252 examined teeth (88% recall rate), 90% were healed. Teeth with and without preoperative periapical radiolucencies demonstrated healed rates of 85% and 96%, respectively. Forty-five percent of the teeth (113/252) were followed up at least 2 years later and 21% (53/252) at least 4 years later. Univariate survival analyses identified 4 prognostic factors: preoperative apical periodontitis, the experience of the treatment providers, the number of treatment sessions, and the apical extrusion of MTA. Multiple regression analyses confirmed an increased risk of disease for teeth with preoperative apical periodontitis (hazard ratio = 4.59; 95% confidence interval, 1.57–13.4; P = .005). In addition, the experience of the treatment provider was found to influence the outcome (hazard ratio = 0.25; 95% confidence interval, 0.09–0.75; P = .03). Conclusions Orthograde placement of MTA apical plugs appears to be a promising treatment option for teeth with open apices. The healed rates for such teeth were high in this study, even after follow-up periods of more than 4 years. The presence of preoperative apical periodontitis was identified as an important prognostic factor.
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