1,720,987 research outputs found
Intraoral sensor-based monitoring of stabilization splint therapy in patients with myofascial pain
No full textThe present study aimed to evaluate intraoral microsensors for the objective measurement of patient compliance during splint therapy and to comparatively analyze the duration of mandibular and maxillary splint application in patients with myofascial pain
Intraoral sensor-based monitoring of stabilization splint therapy in patients with myofascial pain
No full textThe present study aimed to evaluate intraoral microsensors for the objective measurement of patient compliance during splint therapy and to comparatively analyze the duration of mandibular and maxillary splint application in patients with myofascial pain
Reparatur statt Austausch
No full textZiel der Studie: Amalgam kommt bei der Anfertigung neu- er Restaurationen immer seltener zur Anwendung, jedoch verfügen viele PatientInnen über bereits bestehende Amal- gamrestaurationen. Dementsprechend bedarf es Reparatur- techniken, die geeignet sind, partiell insuffiziente Amalgam- restaurationen zu reparieren. Ziel dieser Studie war es daher, die Reparierbarkeit von Komposit und Amalgam in Abhängig- keit von verschiedenen mechanischen und chemischen Ober- flächenvorbehandlungen zu untersuchen und zu vergleichen.
Material und Methode: Komposit- und Amalgamprüfkörper wurden im Thermolastwechselverfahren (10.000 Zyklen, 5 – 55°C) künstlich gealtert und per Zufallsverfahren drei verschiedenen mechanischen Oberflächenbearbeitungen zugeführt: Anrauen, Sandstrahlen mit Aluminiumoxid oder Silikatisieren. In den entsprechenden Kontrollgruppen fand keine mechanische Oberflächenbearbeitung statt. Anschlie- ßend wurde entweder ein konventionelles Bonding oder ein Universaladhäsiv und darauffolgend ein Reparaturkomposit aufgebracht (je Untergruppe n = 16). Nach erneuter Alterung wurden die Scherfestigkeiten bestimmt und die Versagens- muster untersucht. Die statistische Auswertung erfolgte mit- tels ANOVA, Zweistichproben-t-Tests, Weibull-Statistik und Chi2-Test (p < 0,05).
Ergebnisse: Unabhängig von der Art der Vorbehandlung wa- ren die Reparaturfestigkeiten auf Amalgam signifikant gerin- ger als auf Komposit (p < 0,02). Verglichen mit der jeweiligen Kontrollgruppe führte eine mechanische Vorbehandlung sowohl auf Komposit als auch auf Amalgam zu signifikant höheren Haftwerten. Die Applikation des Universaladhäsivs führte auf Amalgam-Prüfkörpern in allen Untergruppen zu signifikant besseren Haftwerten als das konventionelle Bon- ding. Dies war bei Komposit nur in der Kontrollgruppe und bei Anrauen der Oberfläche der Fall. Die Versagensmuster waren signifikant abhängig vom Material sowie der mechanischen und chemischen Vorbehandlung (p < 0,001). Die mechanische Oberflächenvorbehandlung führte dabei zu einem signifikant geringeren Anteil adhäsiver Versagensmuster.
Zusammenfassung: Insuffiziente Amalgamrestaurationen sind potenziell für Reparaturen mit Komposit geeignet, aller- dings werden geringere Reparaturhaftwerte als auf Komposit erzielt
The influence of surface texture and wettability on initial bacterial adhesion on titanium and zirconium oxide dental implants
No full textAbstract Background This study aims to investigate bacterial adhesion on different titanium and ceramic implant surfaces, to correlate these findings with surface roughness and surface hydrophobicity, and to define the predominant factor for bacterial adhesion for each material. Methods Zirconia and titanium specimens with different surface textures and wettability (5.0 mm in diameter, 1.0 mm in height) were prepared. Surface roughness was measured by perthometer (R a ) and atomic force microscopy, and hydrophobicity according to contact angles by computerized image analysis. Bacterial suspensions of Streptococcus sanguinis and Staphylococcus epidermidis were incubated for 2 h at 37 °C with ten test specimens for each material group and quantified with fluorescence dye CytoX-Violet and an automated multi-detection reader. Results Variations in surface roughness (R a ) did not lead to any differences in adhering S. epidermidis, but higher R a resulted in increased S. sanguinis adhesion. In contrast, higher bacterial adhesion was observed on hydrophobic surfaces than on hydrophilic surfaces for S. epidermidis but not for S. sanguinis. The potential to adhere S. sanguinis was significantly higher on ceramic surfaces than on titanium surfaces; no such preference could be found for S. epidermidis. Conclusions Both surface roughness and wettability may influence the adhesion properties of bacteria on biomaterials; in this context, the predominant factor is dependent on the bacterial species. Wettability was the predominant factor for S. epidermidis and surface texture for S. sanguinis. Zirconia did not show any lower bacterial colonization potential than titanium. Arithmetical mean roughness values R a (measured by stylus profilometer) are inadequate for describing surface roughness with regard to its potential influence on microbial adhesion
Influence of the Manufacturing Method on the Adhesion of Candida albicans and Streptococcus mutans to Oral Splint Resins
No full textMicrobial adhesion to oral splints may lead to oral diseases such as candidiasis, periodontitis or caries. The present in vitro study aimed to assess the effect of novel computer-aided design/computer-aided manufacturing (CAD/CAM) and conventional manufacturing on Candida albicans and Streptococcus mutans adhesion to oral splint resins. Standardized specimens of four 3D-printed, two milled, one thermoformed and one pressed splint resin were assessed for surface roughness by widefield confocal microscopy and for surface free energy by contact angle measurements. Specimens were incubated with C. albicans or S. mutans for two hours; a luminometric ATP assay was performed for the quantification of fungal and bacterial adhesion. Both one-way ANOVA with Tukey post hoc testing and Pearson correlation analysis were performed (p < 0.05) in order to relate manufacturing methods, surface roughness and surface free energy to microbial adhesion. Three-dimensional printing and milling were associated with increased adhesion of C. albicans compared to conventional thermoforming and pressing, while the S. mutans adhesion was not affected. Surface roughness and surface free energy showed no significant correlation with microbial adhesion. Increased fungal adhesion to oral splints manufactured by 3D printing or milling may be relevant for medically compromised patients with an enhanced risk for developing candidiasis
Time of day-dependent deviations in dynamic and static occlusion: A prospective clinical study
No full textHow to register static occlusion – Correlation of contemporary techniques
No full texthttp://dx.doi.org/10.13039/501100003385 Georg-August-Universität GöttingenOpen-Access-Publikationsfonds 202
Use of Multiple-Select Multiple-Choice Items in a Dental Undergraduate Curriculum: Retrospective Study Involving the Application of Different Scoring Methods
No full textBackground: Scoring and awarding credit are more complex for multiple-select items than for single-choice items. Forty-one different scoring methods were retrospectively applied to 2 multiple-select multiple-choice item types (Pick-N and Multiple-True-False [MTF]) from existing examination data.
Objective: This study aimed to calculate and compare the mean scores for both item types by applying different scoring methods, and to investigate the effect of item quality on mean raw scores and the likelihood of resulting scores at or above the pass level (≥0.6).
Methods: Items and responses from examinees (ie, marking events) were retrieved from previous examinations. Different scoring methods were retrospectively applied to the existing examination data to calculate corresponding examination scores. In addition, item quality was assessed using a validated checklist. Statistical analysis was performed using the Kruskal-Wallis test, Wilcoxon rank-sum test, and multiple logistic regression analysis (P<.05).
Results: We analyzed 1931 marking events of 48 Pick-N items and 828 marking events of 18 MTF items. For both item types, scoring results widely differed between scoring methods (minimum: 0.02, maximum: 0.98; P<.001). Both the use of an inappropriate item type (34 items) and the presence of cues (30 items) impacted the scoring results. Inappropriately used Pick-N items resulted in lower mean raw scores (0.88 vs 0.93; P<.001), while inappropriately used MTF items resulted in higher mean raw scores (0.88 vs 0.85; P=.001). Mean raw scores were higher for MTF items with cues than for those without cues (0.91 vs 0.8; P<.001), while mean raw scores for Pick-N items with and without cues did not differ (0.89 vs 0.90; P=.09). Item quality also impacted the likelihood of resulting scores at or above the pass level (odds ratio ≤6.977).
Conclusions: Educators should pay attention when using multiple-select multiple-choice items and select the most appropriate item type. Different item types, different scoring methods, and presence of cues are likely to impact examinees' scores and overall examination results.Open-Access-Publikationsfonds 202
Antibacterial coating of orthodontic elastomeric ligatures with silver and bismuth nanofilms by magnetron sputtering: A feasibility study
No full textAbstract
Objectives
Magnetron sputtering was evaluated to equip surfaces of orthodontic elastomeric ligatures with silver and bismuth nanofilms.
Material and Methods
Antibacterial properties were evaluated by the adhesion of
Streptococcus mutans
. Polyurethane‐based elastomeric ligatures were coated with silver and bismuth nanofilms via direct current magnetron sputtering. Surface roughness (
R
a
) and surface‐free energy (SFE) were assessed. Coated specimens were incubated with
S. mutans
for 2 h. Adhering bacteria were visualized by Hoechst staining and quantified by an ATP‐based luminescence assay. One‐way analysis of variance with Tukey post hoc testing and Pearson correlation analysis were performed (
p
< .05) to relate bacterial adhesion to surface roughness and surface‐free energy.
Results
Elastomeric ligatures were successfully coated with silver and bismuth nanofilms.
R
a
was significantly reduced by silver coating. Silver and bismuth coatings showed significantly higher SFE than controls. Adhesion of
S. mutans
was significantly decreased by silver coating. No correlation between bacterial adhesion and SFE was found. Correlation between bacterial adhesion and
R
a
was positive but not statistically significant.
Conclusions
Magnetron sputtering proved to be a feasible method to equip orthodontic elastomeric ligatures with silver and bismuth nanofilms. Silver coatings of elastomeric ligatures may reduce white spots and carious lesions in orthodontic patients. Future research is required to stabilize coatings.Open-Access-Publikationsfonds 202
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