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ABSTRACT: Metal ceramic restorations are widely used in prosthodontics, but long-term data on their clinical performance in private practice settings based on prospective trials are sparse.
This clinical trial was designed to provide realistic long-term survival rates for different outcomes related to tooth loss, crown loss, and metal ceramic defect.
Ninety-five participants were provided with 190 noble metal ceramic single crowns and 138 participants with 276 fixed dental prosthesis retainer crowns on vital posterior teeth. Follow-up examinations were scheduled 2 weeks after insertion, annually up to 8 years, and after 10 years. Kaplan-Meier survival analyses, Mantel-Cox logrank tests, and Cox regression analyses were conducted.
Because of variations in the time of the last examinations, the maximum observation period was 12.1 years. For the primary outcome 'loss of crown or tooth', the Kaplan-Meier survival rate was 94.3% ±1.8% (standard error) at 8.0 years (last outcome event) for single crowns and 94.4% ±1.5% at 11.0 years for fixed dental prosthesis retainer crowns. The difference between the survival functions was not significant (P>.05). For the secondary outcome 'metal ceramic defect', the survival rate was 88.8% ±3.2% at 11.0 years for single crowns and 81.7% ±3.5% at 11.0 years for fixed dental prosthesis retainer crowns. In Cox regression models, the only significant covariates for the outcome event 'metal ceramic defect' were bruxism in the medical history (single crowns) and signs and symptoms of bruxism (fixed dental prosthesis retainer crowns) with hazard ratios of 3.065 (95% CI 1.063 - 8.832) and 2.554 (95% CI 1.307 - 4.992).
Metal ceramic crowns provided in private practice settings show good longevity. Bruxism appears to indicate a risk for metal ceramic defects.
The Journal of prosthetic dentistry 03/2013; 109(3):149-55. · 1.22 Impact Factor
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ABSTRACT: OBJECTIVES: The use of fast-setting impression materials with different viscosities for the one-stage impression technique demands precise working times when mixing. We examined the effect of varying working time on impression precision in a randomized clinical trial. MATERIALS AND METHODS: Focusing on tooth 46, three impressions were made from each of 96 volunteers, using either a polyether (PE: Impregum Penta H/L DuoSoft Quick, 3 M ESPE) or an addition-curing silicone (AS: Aquasil Ultra LV, Dentsply/DeTrey), one with the manufacturer's recommended working time (used as a reference) and two with altered working times. All stages of the impression-taking were subject to randomization. The three-dimensional precision of the non-standard working time impressions was digitally analyzed compared to the reference impression. Statistical analysis was performed using multivariate models. RESULTS: The mean difference in the position of the lower right first molar (vs. the reference impression) ranged from ±12 μm for PE to +19 and -14 μm for AS. Significantly higher mean values (+62 to -40 μm) were found for AS compared to PE (+21 to -26 μm) in the area of the distal adjacent tooth. CONCLUSIONS: Fast-set impression materials offer high precision when used for single tooth restorations as part of a one-stage impression technique, even when the working time (mixing plus application of the light- and heavy-body components) diverges significantly from the manufacturer's recommended protocol. CLINICAL RELEVANCE: Best accuracy was achieved with machine-mixed heavy-body/light-body polyether. Both materials examined met the clinical requirements regarding precision when the teeth were completely syringed with light material.
Clinical Oral Investigations 08/2012; · 2.36 Impact Factor
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ABSTRACT: The study aim was to identify predictors of impaired oral health-related quality of life (OHRQoL). Employees of five companies were offered a clinical full-mouth examination. Oral health-related quality of life was measured with the German version of the Oral Health Impact Profile (OHIP) and summarized as additive scores (OHIP-ADD) and as prevalence of negative impacts (OHIP-SC). Two logistic regression models were developed for the odds of increased scores of the target variables OHIP-ADD and OHIP-SC. The target variables were dichotomized, and for the OHIP-ADD, the cut-off point for having impaired OHRQoL was heuristically defined as OHIP-ADD > 34. For the OHIP-SC, the corresponding threshold was OHIP-SC > 0. In the model for the OHIP-ADD, female gender, impaired aesthetics, few posterior occluding pairs, and painful masticatory muscles proved to be significant independent variables. For the OHIP-SC, female gender, impaired aesthetics, painful masticatory muscles, joint sounds, missing mandibular teeth, and carious teeth were significant. This cross-sectional study showed that within the models for both OHIP-ADD and OHIP-SC the high-risk person for impaired OHRQoL is a woman with impaired aesthetics and painful masticatory muscles.
European Journal Of Oral Sciences 12/2011; 119(6):481-8. · 1.88 Impact Factor
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Ralph G Luthardt,
Birgit Marré,
Achim Heinecke,
Joachim Gerss,
Hans Aggstaller,
Eckhard Busche,
Paul Dressler,
Ingrid Gitt,
Wolfgang Hannak,
Sinsa Hartmann,
Guido Heydecke,
Florentine Jahn,
Matthias Kern,
Torsten Mundt,
Peter Pospiech,
Helmut Stark,
Bernd Wöstmann, Michael H Walter
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ABSTRACT: Various treatment options for the prosthetic treatment of jaws where all molars are lost are under discussion. Besides the placement of implants, two main treatment types can be distinguished: replacement of the missing molars with removable dental prostheses and non-replacement of the molars, i.e. preservation of the shortened dental arch. Evidence is lacking regarding the long-term outcome and the clinical performance of these approaches. High treatment costs and the long time required for the treatment impede respective clinical trials.
This 14-center randomized controlled investigator-initiated trial is ongoing. Last patient out will be in 2010. Patients over 35 years of age with all molars missing in one jaw and with at least both canines and one premolar left on each side were eligible. One group received a treatment with removable dental prostheses for molar replacement (treatment A). The other group received a treatment limited to the replacement of all missing anterior and premolar teeth using fixed bridges (treatment B). A pilot trial with 32 patients was carried out. Two hundred and fifteen patients were enrolled in the main trial where 109 patients were randomized for treatment A and 106 for treatment B. The primary outcome measure is further tooth loss during the 5-year follow-up. The secondary outcome measures encompassed clinical, technical and subjective variables. The study is funded by the Deutsche Forschungsgemeinschaft (German Research Foundation, DFG WA 831/2-1, 2-2, 2-3, 2-4, 2-5).
The particular value of this trial is the adaptation of common design components to the very specific features of complex dental prosthetic treatments. The pilot trial proved to be indispensable because it led to a number of adjustments in the study protocol that considerably improved the practicability. The expected results are of high clinical relevance and will show the efficacy of two common treatment approaches in terms of oral health. An array of secondary outcome measures will deliver valuable supplementary information. If the results can be implemented in the clinical practice, the daily dental care should strongly profit thereof.
The trial is registered at ClinicalTrials.gov under ISRCTN68590603 (pilot trial) and ISRCTN97265367 (main trial).
Trials 02/2010; 11:15. · 2.02 Impact Factor
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ABSTRACT: In dentistry, ceramic materials with high fracture resistance are needed for all-ceramic fixed partial dentures (FPDs). The sophisticated processing of advanced ceramics that can be used for such dental restorations demands the application of CAD/CAM technologies. These techniques necessitate digitizing of the prepared teeth or the planned restoration itself and surfacing of the acquired digital data before milling paths can be generated. As precision in fit is crucial for dental restorations, a computer-aided method for the quantitative and qualitative 3D analysis has been developed and applied. Factors influencing the obtainable precision in the application of CAD/CAM techniques were taken into consideration.
Computers in Biology and Medicine 06/2007; 37(5):579-87. · 1.09 Impact Factor
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ABSTRACT: Aspects of oral health related quality of life (OHQOL) are attracting increased attention in dentistry. Knowledge in this field is limited, especially in terms of significant indicators and predictors of impaired OHQOL. The aim of this cross-sectional study was to examine the influence of various sociodemographic and clinical variables on OHQOL in the setting of outreach clinics in northern Alberta, Canada.
OHQOL was measured with the 49-item Oral Health Impact Profile questionnaire (OHIP-49), administered to adult patients attending 3 dental outreach clinics managed by the University of Alberta. Sociodemographic and clinical data were also collected. Data were analyzed using descriptive and multivariable methods.
The OHIP-49 scores were comparatively low for a patient sample. After multivariable stepwise logistic regression analysis, only gender, missing anterior teeth and need for endodontic treatment remained as significant variables in the final model for impaired OHQOL. Missing anterior teeth (regardless of replacement) had the strongest effect. Subjects with this feature had an approximately 21-fold greater risk of impaired OHQOL relative to those who retained all of their anterior teeth.
The clientele of these outreach clinics was generally young but had high treatment needs. OHQOL results can be useful in considering treatment strategies in similar rural environments, but the complexity of this indicator necessitates an individual patient-centred approach in clinical decision-making.
Journal (Canadian Dental Association) 04/2007; 73(2):153. · 1.00 Impact Factor
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ABSTRACT: The knowledge on the determinants of oral health-related quality of life (OHQoL) is still fragmentary. The aim of this study
was to examine the influence of different socio-economic, behavioral, and clinical variables on OHQoL in a cross-cultural
patient sample in Germany and Canada. The study had a cross-sectional design. It was conducted at five examination sites at
clinics managed by the Technische Universität Dresden (Germany) and the University of Alberta (Canada), with the sites representing
different cultural and socio-economic variables. Incoming patients satisfying the defined inclusion and exclusion criteria
were asked to participate. Subjects who had been to a dentist within the last 3months were excluded to avoid bias related
to recent experiences associated with ongoing treatment. OHQoL was measured with the 49-item version of the OHIP (Oral Health
Impact Profile) questionnaire (OHIP-49) together with age, gender, attendance and a set of oral health variables. The OHIP
questions are organized into seven dimensions: functional limitation, physical pain, psychological discomfort, physical disability,
psychological disability, social disability, and handicap. All questions refer to the experiences of the subject in the preceding
12months. Descriptive, univariate, and multivariate methods were applied in data analysis. Based on the results of the multivariate
logistic regression analysis, only gender, removable denture wearing, and treatment need in endodontics, surgery, and prosthetics
remained as significant explanatory variables in the final model for impaired OHQoL. With the OHIP subscale handicap being
the dependent variable, missing anterior teeth (regardless of replacement), treatment need in surgery, and the time of the
last dental visit were significant indicators of high – i.e. unfavorable – scores. In this patient sample, impaired OHQoL
was associated with several factors. The examination site, however, was not among the explanatory variables in the final models,
as had been expected, thus indicating the absence of cross-cultural differences.
Journal of Public Health 01/2007; 15(1):43-50. · 2.06 Impact Factor
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ABSTRACT: Clinical investigations dealing with the precision of different impression techniques are rare. Objective of the present study was to develop and evaluate a procedure for the qualitative analysis of the three-dimensional impression precision based on an established in-vitro procedure. The zero hypothesis to be tested was that the precision of impressions does not differ depending on the impression technique used (single-step, monophase and two-step-techniques) and on clinical variables.
Digital surface data of patient's teeth prepared for crowns were gathered from standardized manufactured master casts after impressions with three different techniques were taken in a randomized order. Data-sets were analyzed for each patient in comparison with the one-step impression chosen as the reference. The qualitative analysis was limited to data-points within the 99.5%-range. Based on the color-coded representation areas with maximum deviations were determined (preparation margin and the mantle and occlusal surface). To qualitatively analyze the precision of the impression techniques, the hypothesis was tested in linear models for repeated measures factors (p < 0.05).
For the positive 99.5% deviations no variables with significant influence were determined in the statistical analysis. In contrast, the impression technique and the position of the preparation margin significantly influenced the negative 99.5% deviations.
The influence of clinical parameter on the deviations between impression techniques can be determined reliably using the 99.5 percentile of the deviations. An analysis regarding the areas with maximum deviations showed high clinical relevance. The preparation margin was pointed out as the weak spot of impression taking.
Dental Materials 01/2006; 22(1):69-76. · 3.13 Impact Factor
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ABSTRACT: Computer-Aided-Design/Computer-Aided-Manufacturing (CAD/CAM) techniques are gaining importance in fabricating crowns and fixed partial dentures (FPDs) made of yttria stabilized tetragonal zirconia polycrystals (Y-TZP). The specific aims of this study were (1) to test the hypothesis that surface flaws and microcracks are induced by the grinding of crowns (2) to analyze the material removal and the grinding-induced surface layer as well as to estimate the crack size caused by machining Y- TZP under conditions simulating the grinding of crowns.
Y-TZP disks and sectioned cylinders with polished separation planes were used for the analysis of the grinding procedure. While simulating the inner surface grinding of crowns, feed and cutting depth were varied (vw = 100, 75, 50 mm/min; ap = 0.1, 0.06, 0.02 mm). SEM was used for the quantitative assessment of the machined surface.
While the crack length is not significantly influenced by the grinding parameters, the type of material removed varied with the cutting depth as well as with the feed. Grinding induced surface flaws and microcracks were detected at the internal top surface of the crowns. Half-cylinders machined under conditions simulating the inner surface grinding of crowns showed crack lengths between 2 and 15 microm.
Sectioned specimens with polished section planes are suitable for the analysis of the grinding process using the face and peripheral grinding procedure. The inner surface grinding of fixed restorations is the most challenging step of CAM of crowns and FPDs. Most important appeared to be the diamond tool, especially the number and shape of the active diamond grains.
Dental Materials 10/2004; 20(7):655-62. · 3.13 Impact Factor
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ABSTRACT: In a 25-year-old satellite dental program, advanced dentistry and dental hygiene students provide highly supervised dental treatment for patients in government-funded clinics in 3 under-serviced communities in northern Alberta. Analysis of the performance data of the 2003 University of Alberta dentistry students in their fourth and final year was used to evaluate this program. The data showed that the undergraduate students did numerous diverse general dental procedures during the 2-week rotation, most of which were basic treatments. Students could participate in the program up to 3 times. In subsequent rotations, students tended to do fewer preventive measures, and more restorative treatment and dental extractions. Available grading data for all students indicated that treatment objectives were fulfilled in the vast majority of cases. Such community-based field experience may significantly add to the competence of students entering private practice.
Journal (Canadian Dental Association) 05/2004; 70(4):233-6. · 1.00 Impact Factor
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ABSTRACT: The quantitative evaluation of the time- or process-dependent three-dimensional stability of dental materials is a common question in dentistry. An investigation procedure has been developed based on a CAD-surface model of a prepared upper canine, as well as a high-precision physical copy (metal master die). The specific aim of this study was to test this method's reliability. Additionally, the ability of the developed procedure to determine the three-dimensional stability of resin-reinforced gypsum master casts over time was investigated.
Ten duplicate dies of improved dental stone (esthetic-rock, dentona, Germany) were manufactured, and digitized 1, 3, 7, 28 and 56 days after pouring. A three-coordinate optical measuring device was used for the data acquisition. The three-dimensional accuracy of stone dies was determined by comparing the digitized data of the stone dies made from the metal master die to its CAD-surface model (Surfacer) Version 9.0. Imageware Inc., Ann Arbor Michigan, USA). To assess the procedure, test surfaces were created from the digitized data and compared with a reference.
The mean deviation between the digitized point cloud and the test surface was less than 3 microm. During the 56 day examination period no significant three-dimensional changes in dimensional stability were found.
The procedure for the quantitative three-dimensional evaluation was shown to be suitable. Best-fit registration enabled a reliable alignment of the point cloud to the CAD-surface model. Alteration of three-dimensional accuracy over 6 weeks was insignificant and without clinical relevance.
Dental Materials 02/2003; 19(1):19-24. · 3.13 Impact Factor
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ABSTRACT: The clinical impact of posterior crown margin placement on gingival health has not been thoroughly quantified.
This study evaluated the effect of posterior crown margin placement with multivariate analysis.
Ten general dentists reviewed 240 patients with 480 metal-ceramic crowns in a prospective clinical trial. The alloy was randomly selected from 2 high gold, 1 low gold, and 1 palladium alloy. Variables were the alloy used, oral hygiene index score before treatment, location of crown margins at baseline, and plaque index and sulcus bleeding index scores recorded for restored and control teeth after 1 year. The effect of crown margin placement on sulcular bleeding and plaque accumulation was analyzed with regression models (P<.05).
The probability of plaque at 1 year increased with increasing oral hygiene index score before treatment. The lingual surfaces demonstrated the highest probability of plaque. The risk of bleeding at intrasulcular posterior crown margins was approximately twice that at supragingival margins. Poor oral hygiene before treatment and plaque also were associated with sulcular bleeding. Facial sites exhibited a lower probability of sulcular bleeding than lingual surfaces. Type of alloy did not influence sulcular bleeding.
In this study, placement of crown margins was one of several parameters that affected gingival health.
Journal of Prosthetic Dentistry 02/2002; 87(2):167-72. · 1.32 Impact Factor
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ABSTRACT: The aim of this study was to evaluate the clinical performance of metal-ceramic crowns placed in 10 private practices.
In this prospective clinical trial, 95 patients were provided with 190 noble-metal metal-ceramic single crowns.
The 7-year survival rates of the crowns were 95.5% (target event: any removal), 99.5% (target event: removal because of defective veneer), and 92.4% (target event: metal-ceramic complication of any kind). No significant explanatory variables for metal-ceramic complications could be detected by bivariate and multivariate testing. The consequences resulting from metal-ceramic defects were of minor clinical significance in most cases.
The findings support previous claims that metal-ceramic restorations perform very well clinically, including in practices outside academic environments.
The International journal of prosthodontics 19(4):397-9. · 1.38 Impact Factor
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ABSTRACT: A procedure for 3-D analysis of the internal fit of fixed restorations has been developed. This study tested this method for investigating the fit of all-ceramic crowns.
Twelve data sets of a prepared maxillary canine were acquired by direct digitizing of the metal master die (CEREC 3 camera) and by digitizing gypsum dies after conventional impression taking (CEREC 3 scan), respectively. Using these data sets, 24 all-ceramic single crowns each were machined out of two glass-ceramics. The method is based on duplicated gypsum dies of the metal master, which were made for each crown. The space between the duplicate die and the internal surface of the respective crown was filled with a low-viscosity addition silicone. These silicone films (replicas) and their corresponding dies were digitized in the same measuring position. The internal fit was calculated and quantitatively and qualitatively analyzed.
The mean and maximum positive deviations were 348 microm and 986 microm (camera), respectively, and 294 microm and 830 microm (scan), respectively, for Vitablocs Mk II and 332 microm and 920 microm (camera), respectively, and 307 microm and 852 microm (scan), respectively, for ProCAD. For both systems, the deviations were highest at the edges. CEREC scan yielded significantly better internal fit accuracy compared to the CEREC camera.
Evaluation of the internal 3-D fit using the innovative method proved to be suitable. Indirect data acquisition using impression taking showed improved internal fit compared with the direct procedure. However, the differences between the data-acquisition techniques are small compared to their absolute values.
The International journal of prosthodontics 17(6):680-5. · 1.38 Impact Factor
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ABSTRACT: The aim of the study was to evaluate the clinical performance of Procera Alumina AllCeram crowns (Nobel Biocare).
In 70 patients, 61 anterior and 46 posterior teeth were provided with single crowns and cemented with a glass-ionomer cement.
Four patients were lost to follow-up. Six crowns had to be removed, all because of nonreparable fracture. At 6 years, the cumulative survival rate was 94.3% for all crowns, 96.7% for anterior crowns, and 91.3% for posterior crowns (survival = not removed). Most of the defects occurred within the first 1.5 years.
The findings indicate a good clinical prognosis of both anterior and posterior Procera Alumina crowns.
The International journal of prosthodontics 19(2):162-3. · 1.38 Impact Factor
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ABSTRACT: In vitro studies showed superior impression correctness for one-stage impressions. However, clinical data, especially clinical trials, are lacking in this matter. The aim of the study was to investigate the three-dimensional correctness of impressions for final restorations applying three different impression techniques.
Three impressions each were made from 48 patients with different techniques using metal stock trays. In a randomized order, one-stage putty-wash, two-stage putty-wash, and monophase impressions (respectively, Dimension Penta H and Garant L, Dimension Penta H Quick and Garant L Quick, Impregum Penta; 3M ESPE) were made with either polyvinyl siloxane or polyether materials. The double-cord technique was applied at all abutment teeth. Factors potentially influencing the correctness of the impressions were recorded. The precision of the impressions was three-dimensionally analyzed using the resulting gypsum models. Discrepancies between the impressions were calculated using the one-stage putty-wash impression as reference.
Discrepancies between the one-stage putty-wash impressions and the monophase impressions are significantly lower compared with two-stage putty-wash impressions. The depth of the most subgingival portion of the preparation margin significantly influences the discrepancies between the impression techniques.
In light of the major influence of clinical parameters on impression correctness, one-stage procedures should be favored. These findings support the results of in vitro investigations.
Quintessence international (Berlin, Germany: 1985) 41(10):845-53. · 0.64 Impact Factor
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ABSTRACT: The clinical success of fixed restorations is linked to the precise reproduction of the prepared teeth by dental impressions. The hypothesis under examination was that neither clinical parameters nor the impression technique influenced the reproduction of the finishing line during impression making.
For 48 patients who needed a fixed restoration, a 1-stage putty-wash, 2-stage putty-wash, and monophase impression were made after preparation in a randomized order. Clinical parameters (Plaque Index, probing depth, bleeding on probing, Gingival Index, location of the finishing line, bleeding during impression taking, and blood at the impression) were recorded. Master casts were manufactured and optically digitized. Using the data of the 1-stage putty-wash impression as reference, the reproduction of the finishing line was measured 3-dimensionally. Linear models were used for statistical analysis.
The finishing line was reproduced most precisely by the 1-stage putty-wash technique. Variables with significant influence were the impression technique, blood at the impression, and probing depth. The 2-stage putty-wash impressions showed significantly reduced accuracy compared with the 1-stage impressions.
Clinical parameters and the impression techniques determine the reproduction of the finishing line. The benefit of 2-stage putty-wash impressions with regard to a more complete rendering of subgingival finishing lines should be questioned in light of these results.
The International journal of prosthodontics 21(4):322-7. · 1.38 Impact Factor
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ABSTRACT: The accuracy of dental impression taking is one major factor influencing the fit of crowns and fixed partial dentures. The aim of this study was to determine the accuracy of three-dimensional (3-D) tooth surface and subgingival tooth surface reproduction using three different silicone materials and the two-stage putty-and-wash technique.
From 24 probands, three impressions each were taken with Express STD Putty/Wash (3M ESPE), Optosil/Xantopren L (Heraeus Kulzer), and an experimental ultralight body/putty material (3M ESPE) in a randomized order. The preliminary impression was cut according to established procedures for the two-stage putty-and-wash technique. Master casts were manufactured with a standardized procedure and optically digitized. The 3-D accuracy was analyzed with a computer-aided procedure. The Express STD putty-and-wash impressions were used as a reference. Linear models were used for the statistical analysis.
Mean deviations of 27.0 microm and -23.6 microm were found for Optosil/Xantopren L and 26.5 microm and -22.6 microm for the experimental material when analyzing 3-D surface reproduction. The tooth surface (buccal/oral) significantly influenced the accuracy of the surface reproduction. Optosil/Xantopren L showed a more complete reproduction of the subgingival tooth surface than either the experimental or reference materials.
The accuracy of the 3-D tooth surface reproduction as well as the reproduction of the subgingival tooth surface was not favorably influenced when the ultralight wash material was used with established cutting procedures for the preliminary impression.
The International journal of prosthodontics 22(3):296-302. · 1.38 Impact Factor
