1,720,981 research outputs found
Prospective evaluation of zirconia posterior fixed partial dentures: four-year clinical results.
No full textPURPOSE: In this prospective clinical study, the performance of three- and four-unit fixed partial dentures (FPDs) with frameworks fabricated of yttria partially stabilized zirconia was determined after a mean observation period of 50 months. The study focused on the survival of the restoration (in situ criterion) and the success of the ceramic veneers (no defect). MATERIALS AND METHODS: Seventy-five patients with a maximum of two missing teeth and an antagonistic dentition were treated at the Department of Prosthodontics, University of Goettigen, with 99 posterior FPDs. Fifty-one specimens (experimental group) were veneered with an experimental ceramic suitable for titanium and zirconia frameworks (thermal expansion coefficient [TEC]: 8.5 microm/m K); 48 restorations (Ceram-S group) were veneered with a commercially available low-fusing ceramic optimized for zirconia frameworks (TEC: 9.5 microm/m K). All restorations were luted with zinc-phosphate cement. Statistical analysis was performed according to the Kaplan-Meier method; time-dependent success rates of the different types of ceramic veneers were analyzed using the log-rank test. RESULTS: Seven restorations were lost: 4 due to technical complications and 3 due to biologic complications. The overall survival rate after 48 months was 94% (Kaplan-Meier analysis). Twenty-three events required clinical intervention for restoration maintenance: 13 ceramic veneer chippings (polishing), 6 losses of retention (recementation), 3 caries lesions (filling therapy), and 1 loss of vitality (endodontic treatment). Between the two groups of veneering materials, no significant difference in the probability for success was determined (log-rank test, P=.81). CONCLUSIONS: Within a mean observation period of 4 years, sufficient survival rates for zirconia-based posterior FPDs could be verified. The main complications included fracture of the ceramic veneering material and decementation, which occurred mainly in the mandible
Risk factors for technical and biological complications with zirconia single crowns
No full textObjectives This practice-based study evaluated the clinical performance and risk factors for biological and technical complications with conventionally luted zirconia crowns. Materials and methods Sixty-eight patients (39 female) with a total of 323 restorations placed on 219 vital teeth, 69 endodontically treated teeth (ETT), and 41 implants (incisors, 96; premolars, 89; molars, 138; observational period, 79.7 +/- 14.2 months) underwent a clinical follow-up examination and were included in the study. Time-dependent survival (in situ), success (event free), and veneering ceramic fracture (VCF) rates were calculated and analyzed relative to the following risk factors: smoking status, location of the crown, and type of abutment. Results Fifty-three complete failures were recorded. A significant influence of the abutment type on survival could be detected (p = 0.033): ETT demonstrated a significantly (p = 0.029) lower 7-year survival rate (73.8 %, 95 % confidence interval [95 % CI] 0.600-0.876) than crowns placed on implants (90.0 %, 95 % CI 0.814-0.990). The success rate of the crowns was significantly influenced by the location of the restoration (p = 0.0058). A total of 75.6 % (95 % CI 0.648-0.864) of the anterior crowns remained event free, compared to 50.4 % (95 % CI 0.388-0.621) of the molar crowns. Furthermore, the location of the crowns affected the VCF rate (p = 0.018, event-free anterior teeth 95.2 % (95 % CI 0.880-1), event-free molars 80.9 % (95 % CI 0.706-0.913)). Conclusions Survival and success rates were significantly influenced by the type of abutment and the location of the restoration.DeguDent GmbH, Hanau, German
A practice-based clinical evaluation of the survival and success of metal-ceramic and zirconia molar crowns: 5-year results
No full textThis practice-based study evaluates the survival and success of conventionally luted metal-ceramic and zirconia molar crowns fabricated by using a prolonged cooling period for the veneering porcelain. Fifty-three patients were treated from 07/2008 to 07/2009 with either metal-ceramic crowns (MCC) or zirconia crowns (ZC). Forty-five patients (26 female) with 91 restorations (obser-vational period: 640 +/- 48 months) participated in a clinical follow-up examination and were included in the study. Estimated cumulative survival (ECSv), success (ECSc) and veneering ceramic success (ECVCSc) were calculated (Kaplan-Meier) and analysed by the crown fabrication technique and the position of the restoration (Cox regression model) (P < 005). Five complete failures (MCC: 2, ZC: 3) were recorded (5-year ECSv: MCC: 976%, (95% confidence interval (95%-CI): [93%; 100%]/ZC: 940%, (95%-CI): [87%; 100%]). Of the MCCs (n = 41), 850%, [95%-CI: (77%; 96%)] remained event-free, whereas the ECSc for the ZCs (n = 50) was 743% (95%-CI): [61%; 87%]. No significant differences in ECSv (P = 051), ECSc (P = 043) and ECVCSc (P = 036) were detected between the two fabrication techniques. Restorations placed on terminal abutments (n = 44) demonstrated a significantly lower ECVCSc (P = 0035), (5-year VCF-rate: 148%) than crowns placed on tooth-neighboured abutments (n = 47), (5-year VCF-rate: 43%). In the present study, zirconia molar crowns demonstrated a 5-year ECSv, ECSc and ECVCSc comparable to MCCs. Irrespective of the fabrication technique, crowns on terminal abutments bear a significantly increased risk for VCFs. Clinical investigations with an increased number of restorations are needed.DeguDent GmbH; Dentsply DeTre
Practice-based clinical evaluation of metalceramic and zirconia molar crowns: 3-year results
No full textThis practice-based study evaluates the clinical performance of conventionally luted metalceramic and zirconia molar crowns fabricated with pronounced anatomical core design and a prolonged cooling period of the veneering porcelain. Fifty-three patients were treated from 07/2008 until 07/2009 with either metalceramic crowns (MCC) (high-noble alloy+low-fusing porcelain) or zirconia crowns (Cercon System, DeguDent, Germany). Forty-nine patients (30 women/19 men) with 100 restorations (metalceramic: 48/zirconia: 52, mean observational period: 36 center dot 5 +/- 6months) participated in a clinical follow-up examination and were included in the study. Time-dependent survival (in situ criteria), success (event-free restorations) and chipping rates (defects of the veneering ceramics) were calculated according to the KaplanMeier method and analysed in relation to the crown fabrication technique, using a Cox regression model (P<0 center dot 05). Three complete failures (metalceramic: 1, zirconia: 2) were recorded (survival rate after 3years: metalceramic: 97 center dot 6%, zirconia: 95 center dot 2%). Of the metalceramic restorations, 90 center dot 9% remained event-free (two ceramic fractures, one endodontic treatment), whereas the success rate for the zirconia was 86 center dot 8% (two ceramic fractures, one endodontic treatment, one secondary caries). No significant differences in survival (P=0 center dot 53), success (P=0 center dot 49) and ceramic fracture rates (P=0 center dot 57) were detected. The combination of a pronounced anatomical core design and a modified firing of the veneering porcelain for the fabrication of zirconia molar crowns resulted in a 3-year survival, success and chipping rate comparable to MCC.DeguDent GmbH; Dentsply DeTre
Tissue distribution of perlecan domains III and V during embryonic and fetal human development
No full textA major component of basement membranes (BMs) is perlecan, a five-domain heparan sulphate proteoglycan. During murine embryogenesis, nearly all BMs of mesenchymal origin express perlecan, and it is believed to participate in the supramolecular assembly of BMs. However, the distribution of perlecan in human embryonic and fetal tissues is widely unknown, except for cartilage anlagen of developing extremities and the fetal spine. Clinical syndromes, caused by perlecan-associated mutations or gene-defects, suggest its multifunctional involvement during human development. Here we reveal the immunohistochemistry of perlecan domains III and V during human development from gestational weeks (gw) 6 to 12 in basement membrane zones (BMZs) of the developing brain, nervous system, blood vessels, skin, lung, heart, kidney, liver, intestine and skeletal system. Interestingly, a difference in the distribution of the two perlecan domains was found in the endoneurium of ganglia. Domain III is strongly present from gw 6 onwards, while domain V shows attenuated expression at this stage and has been detected abundantly only from gw 8 onwards, possibly indicating vascularization of the endoneurium during this early stage. We found perlecan to be present particularly at those stages of human development where epithelial-mesenchymal interactions occur
Clinical outcome of double crown-retained implant overdentures with zirconia primary crowns
No full textPURPOSE. This retrospective study aims at the evaluation of implant-supported overdentures (IODs) supported by ceramo-galvanic double crowns (CGDCs: zirconia primary crowns + galvano-formed secondary crown). MATERIALS AND METHODS. In a private practice, 14 patients were restored with 18 IODs (mandible: 11, maxilla: 7) retained by CGDCs on 4 - 8 implants and annually evaluated for technical and/or biological failures/complications. RESULTS. One of the 86 inserted implants failed during the healing period (cumulative survival rate (CSR) implants: 98.8%). During the prosthetic functional period (mean: 5.9 +/- 2.2 years), 1 implant demonstrated an abutment fracture (CSR-abutments: 98.2%), and one case of peri-implantitis was detected. All IODs remained in function (CSR-denture: 100%). A total of 15 technical complications required interventions to maintain function (technical complication rate: 0.178 treatments/patients/year). CONCLUSION. Considering the small sample size, the use of CGDCs for the attachment of IODs is possible without an increased risk of technical complications. However, for a final evaluation, results from a larger cohort are required
Prospective Evaluation of Zirconia Posterior Fixed Partial Dentures: 7-Year Clinical Results
No full textPurpose: The clinical performance of three-and four-unit fixed partial dentures (FPDs) with frameworks made of yttria partially stabilized zirconia was determined after a mean observational period of 84 months. Materials and Methods: Seventy-five patients were treated with 99 posterior FPDs. Fifty-one specimens were veneered with an experimental ceramic suitable for titanium and zirconia frameworks; 48 restorations were veneered with a commercially available low-fusing ceramic optimized for zirconia frameworks. All restorations were luted with zinc-phosphate cement. Statistical analysis was performed according to Kaplan-Meier; potential risk factors were analyzed using the Cox regression analysis. Results: Nineteen restorations failed completely: 12 due to technical complications, 6 due to biologic complications, and 1 for unknown reasons. The overall survival rate after 84 months was 83.4%. Thirty-two events required clinical intervention for restoration maintenance, resulting in a time-dependent success rate of 57.9% after 84 months. Nineteen dropouts occurred during the follow-up time. None of the evaluated factors showed an association with survival or success of the restorations. Conclusions: After a mean observational period of 7 years, the survival and success rates of zirconia-based posterior FPDs were inferior to those published for metal-ceramic FPDs. The majority of failures were caused by technical complications (material fractures). The main reasons for clinical intervention to maintain function were fractures of the veneering ceramic and decementations. Int J Prosthodont 2013;26:164-171. doi: 10.11607/ijp.3229DeguDen
Restoration of the edentulous mandible with CAD/CAM-fabricated bar superstructures Literature review and 3 clinical case studies
No full textMulticenter Prospective Clinical Study on Chairside‐Fabricated Partial Crowns: 5‐Year Results for Lithia‐Zirconia Glass–Ceramic Restorations
No full textABSTRACT Objectives Clinical evaluation of chairside‐fabricated lithia‐zirconia glass–ceramic (LZGC) partial crowns (CCPCs) in a multicenter practice‐based study. Materials and Methods Seventy‐one patients were restored with 92 adhesively luted CCPCs (Cerec SW 4.2/Cerec MC XL/Celtra Duo) in three private dental clinics (C1–C3). Time‐dependent (Kaplan–Meier) survival rates (SVR) and success rates (SCR) were calculated. The following possible covariates of SVRs and SCRs were evaluated in a Cox regression model: Restoration position (premolar/molar), luting material (Variolink/Calibra), and operator (C1–C3). Results Seventy‐three CCPCs were placed in 59 patients and were included in the study (mean observational period: 58.0 ± 15 months). Four complete failures (two tooth fractures, one restoration fracture, and one endodontic failure) were recorded. All failures and interventions occurred in one of the three centers (5‐year SCR: C1 + C2: 100%; C3: 71%; 95% confidence interval: [0.55; 0.87]). Additionally, three biological, and two technical complications required clinical intervention to maintain function, and all occurred in C3. Restorations placed in C1 and C2 showed a significantly reduced risk for failure/intervention (hazard ratio = 0.103, p = 0.026) compared with restorations placed in C3. Conclusions LZGC CCPCs showed good five‐year clinical performance. However, SVRs and SCRs were significantly influenced by the operator. Additional clinical data are required for a more detailed investigation of this effect.Dentsply Sirona https://doi.org/10.13039/50110001465
The absence of one or both nidogens does not alter basement membrane composition in adult murine kidney
No full textNidogen- 1 and nidogen- 2 are major components of all basement membranes and are considered to function as link molecules between laminin and collagen type IV networks. Surprisingly, the knockout of one or both nidogens does not cause defects in all tissues or in all basement membranes. In this study, we have elucidated the appearance of the major basement membrane components in adult murine kidney lacking nidogen- 1, nidogen- 2, or both nidogens. To this end, we localized laminin- 111, perlecan, and collagen type IV in knockout mice, heterozygous (+/-) or homozygous (-/-) for the nidogen- 1 gene, the nidogen- 2 gene, or both nidogen genes with the help of light microscopic immunostaining. We also performed immunogold histochemistry to determine the occurrence of these molecules in the murine kidney at the ultrastructural level. The renal basement membranes of single knockout mice contained a similar distribution of laminin- 111, perlecan, and collagen type IV compared to heterozygous mice. In nidogen double- knockout animals, the basement membrane underlying the tubular epithelium was sometimes altered, giving a diffuse and thickened pattern, or was totally absent. The normal or thickened basement membrane of double- knockout mice also showed a similar distribution of laminin- 111, perlecan, and collagen type IV. The results indicate that the lack of nidogen- 1, nidogen- 2, or both nidogens, plays no crucial role in the occurrence and localization of laminin- 111, collagen type IV, and perlecan in murine tubular renal basement membranes
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