Sven Rinke

Prospective evaluation of zirconia posterior fixed partial dentures: 7-year clinical results.

PURPOSE 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.

Range of indications for translucent zirconia modifications: clinical and technical aspects.

Translucent zirconia modifications offer esthetic improvement for manually veneered zirconia structures, as they do not lead to a shining through of the substructure material, even in cases with a pronounced anatomic core design for maximum support of the veneering ceramics. Moreover, these zirconia modifications allow the production of fully anatomic zirconia crowns and fixed dental prostheses in the posterior region. The clinical advantage of these restorations is defined by a significantly reduced material thickness in comparison with veneered restorations or other monolithic materials. As the restoration can be colored individually prior to sintering, followed by characterization by staining, good esthetic results in the posterior region are achieved, even in cases with substantially reduced space. The results of laboratory studies performed so far seem to justify the clinical application of fully anatomic restorations. However, additional clinical studies are required to support these new material modifications.

Long-term results of implant-supported over-dentures retained by double crowns: a practice-based retrospective study after minimally 10 years follow-up

BACKGROUND Different concepts regarding the number of implants and attachment systems for the preparation of implant-supported over-dentures (IODs) have been discussed. Nonetheless, long-term results for double-crown-retained IODs with an observational period of more than 10 years are still rare in the literature. OBJECTIVE The aim of this practice-based study was to retrospectively evaluate the long-term clinical outcome (success/survival rates, technical/biological complications) of IODs retained by double crowns. MATERIAL AND METHODS In a private practice, 36 non-smoking edentulous patients were restored between 1991 and 2002 with double-crown-retained IODs supported by 2-6 implants. For the retrospective evaluation of implant and prosthetic survival (in-situ criterion) and success (event-free observational period), only those patients were included who regularly (at least once a year) participated in a professional maintenance programme and who had a functional period for the restoration of more than 10 years. RESULTS Twenty-two patients (12 Women/10 men, mean age 60.1 ± 9.8 years) with 89 implants supporting nine maxillary and 13 mandibulary dentures (mean number of implants/prosthesis = 4) met the inclusion criteria. The mean follow-up period was 14.1 ± 2.8 years. One implant failed after 4.9 years (cumulative-survival rate: 98.9%). Seven implants in two patients showed peri-implantitis (prevalence: patient-based = 9.1%/implant-based = 8%). Five dentures were renewed (prosthetic-survival rate 77.3% Maintenance procedures (i.e. screw loosening or acrylic fractures) were required at a rate of 0.31/year and patient. CONCLUSION This study indicates that IODs retained with double crowns offer predictable long-term performance with a limited incidence of biological and technical complications.

A practice-based clinical evaluation of the survival and success of metal-ceramic and zirconia molar crowns: 5-year results

This 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: 64.0 ± 4.8 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 < 0.05). Five complete failures (MCC: 2, ZC: 3) were recorded (5-year ECSv: MCC: 97.6%, (95% confidence interval (95%-CI): [93%; 100%]/ZC: 94.0%, (95%-CI): [87%; 100%]). Of the MCCs (n = 41), 85.0%, [95%-CI: (77%; 96%)] remained event-free, whereas the ECSc for the ZCs (n = 50) was 74.3% (95%-CI): [61%; 87%]. No significant differences in ECSv (P = 0.51), ECSc (P = 0.43) and ECVCSc (P = 0.36) were detected between the two fabrication techniques. Restorations placed on terminal abutments (n = 44) demonstrated a significantly lower ECVCSc (P = 0.035), (5-year VCF-rate: 14.8%) than crowns placed on tooth-neighboured abutments (n = 47), (5-year VCF-rate: 4.3%). 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.

Double Crown‐Retained Maxillary Overdentures: 5‐Year Follow‐Up

BACKGROUND There is a lack of data concerning implant-supported overdentures (IODs) retained by double crowns in the edentulous maxilla. PURPOSE To perform a retrospective evaluation of clinical outcomes (survival/success rates) of maxillary overdentures retained on four implants via double crowns. MATERIAL AND METHODS Between 1993 and 2011, 28 patients with edentulous maxillae were restored with overdentures supported by four implants with a Morse taper connection (Ankylos, Dentsply Friadent, Mannheim, Germany) and double crowns according to the Marburg Double Crown (MDC) technique in a private practice. For retrospective evaluation of implant and prosthetic survival (in situ criterion) and success (event-free observational period), only patients attending a professional maintenance program were included (n = 20). RESULTS Twenty patients (13 female/ seven male, mean age: 63.45 ± 7.18 years) with 80 implants met the inclusion criteria. The mean follow-up period was 5.64 ± 3.50 years. One implant was lost (cumulative survival rate: 98.75%). Eight implants (10.1%) in two patients (10%) showed peri-implantitis; both patients were active smokers (cumulative success rate: 88.75%). All dentures were still functional (prosthetic survival rate 100%) at the time of investigation. Technical maintenance procedures (e.g., abutment loosening, screw loosening, acrylic fracture or relining) were required at a rate of 0.222/patient-year. CONCLUSIONS Within the limitations of this study, we conclude that MDC-IODs are a promising treatment alternative for edentulous maxillae offering high implant and prosthesis survival rates > 98% and a limited incidence of biological and technical complications after a mean observational period of >5 years.

COPY-MILLED ALUMINOUS CORE CERAMIC CROWNS : A CLINICAL REPORT

Copy-milled, all-ceramic crowns were produced in a clinical setting. The advantages of this new technique are shortening of processing time and reduction in defects during processing through the use of an industrially prefabricated material.

Fabrication of Zirconia-Reinforced Lithium Silicate Ceramic Restorations Using a Complete Digital Workflow

This case report describes the fabrication of monolithic all-ceramic restorations using zirconia-reinforced lithium silicate (ZLS) ceramics. The use of powder-free intraoral scanner, generative fabrication technology of the working model, and CAD/CAM of the restorations in the dental laboratory allows a completely digitized workflow. The newly introduced ZLS ceramics offer a unique combination of fracture strength (>420 MPa), excellent optical properties, and optimum polishing characteristics, thus making them an interesting material option for monolithic restorations in the digital workflow.

Detection of five potentially periodontal pathogenic bacteria in peri-implant disease: A comparison of PCR and real-time PCR

The aim of this study was to compare the microbial analysis methods of polymerase chain reaction (PCR) and real-time PCR (RT-PCR) in terms of detection of five selected potentially periodontal pathogenic bacteria in peri-implant disease. Therefore 45 samples of healthy, mucositis and peri-implantitis (n = 15 each) were assessed according to presence of the following bacteria using PCR (DNA-strip technology) and RT-PCR (fluorescent dye SYBR green-system): Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Treponema denticola (Td), Tanerella forsythia (Tf), and Fusobacterium nucleatum (Fn). There were no significant correlations between the bacterial and disease patterns, so the benefit of using microbiological tests for the diagnosis of peri-implant diseases is questionable. Correlations between the methods were highest for Tf (Kendalls Tau: 0.65, Spearman: 0.78), Fn (0.49, 0.61) and Td (0.49, 0.59). For Aa (0.38, 0.42) and Pg (0.04, 0.04), lower correlation values were detected. Accordingly, conventional semi-quantitative PCR seems to be sufficient for analyzing potentially periodontal pathogenic bacterial species.

MicroRNAs as Salivary Markers for Periodontal Diseases: A New Diagnostic Approach?

The aim of this review is to discuss current findings regarding the roles of miRNAs in periodontal diseases and the potential use of saliva as a diagnostic medium for corresponding miRNA investigations. For periodontal disease, investigations have been restricted to tissue samples and five miRNAs, that is, miR-142-3p, miR-146a, miR-155, miR-203, and miR-223, were repeatedly validated in vivo and in vitro by different validation methods. Particularly noticeable are the small sample sizes, different internal controls, and different case definitions of periodontitis in in vivo studies. Beside of that, the validated miRNAs are associated with inflammation and therefore with various diseases. Furthermore, several studies successfully explored the use of salivary miRNA species for the diagnosis of oral cancer. Different cancer types were investigated and heterogeneous methodology was used; moreover, no overlap of results was found. In conclusion, five miRNAs have consistently been reported for periodontitis; however, their disease specificity, detectability, and expression in saliva and their importance as noninvasive markers are questionable. In principle, a salivary miRNA diagnostic method seems feasible. However, standardized criteria and protocols for preanalytics, measurements, and analysis should be established to obtain comparable results across different studies.

Evaluation of removal forces of implant-supported zirconia copings depending on abutment geometry, luting agent and cleaning method during re-cementation

PURPOSE To evaluate the effects of different abutment geometries in combination with varying luting agents and the effectiveness of different cleaning methods (prior to re-cementation) regarding the retentiveness of zirconia copings on implants. MATERIALS AND METHODS Implants were embedded in resin blocks. Three groups of titanium abutments (pre-fabricated, height: 7.5 mm, taper: 5.7°; customized-long, height: 6.79 mm, taper: 4.8°; customized-short, height: 4.31 mm, taper: 4.8°) were used for luting of CAD/CAM-fabricated zirconia copings with a semi-permanent (Telio CS) and a provisional cement (TempBond NE). Retention forces were evaluated using a universal testing machine. Furthermore, the influence of cleaning methods (manually, manually in combination with ultrasonic bath or sandblasting) prior to re-cementation with a provisional cement (TempBond NE) was investigated with the pre-fabricated titanium abutments (height: 7.5 mm, taper: 5.7°) and SEM-analysis of inner surfaces of the copings was performed. Significant differences were determined via two-way ANOVA. RESULTS Significant interactions between abutment geometry and luting agent were observed. TempBond NE showed the highest level of retentiveness on customized-long abutments, but was negatively affected by other abutment geometries. In contrast, luting with Telio CS demonstrated consistent results irrespective of the varying abutment geometries. Manual cleaning in combination with an ultrasonic bath was the only cleaning method tested prior to re-cementation that revealed retentiveness levels not inferior to primary cementation. CONCLUSION No superiority for one of the two cements could be demonstrated because their influences on retentive strength are also depending on abutment geometry. Only manual cleaning in combination with an ultrasonic bath offers retentiveness levels after re-cementation comparable to those of primary luting.