Clinically used adhesive ceramic bonding methods: a survey in 2007, 2011, and in 2015.

OBJECTIVES: The objective of the study is to evaluate practices of dentists regarding adhesive cementation of all-ceramic restorations over a period of 8 years. MATERIALS AND METHODS: The authors developed a questionnaire regarding adhesive cementation procedures for all-ceramic restorations. Restorations were distinguished between made out of silicate ceramic or oxide ceramic. The questionnaire was handed out to all dentists participating in a local annual dental meeting in Northern Germany. The returned questionnaires were analyzed to identify incorrect cementation procedures based upon current evidence-based technique from the scientific dental literature. The survey was conducted three times in 2007, 2011, and 2015 and their results were compared. RESULTS: For silicate ceramic restorations, 38-69 % of the participants used evidence-based bonding procedures; most of the incorrect bonding methods did not use a silane containing primer. In case of oxide ceramic restorations, most participants did not use air-abrasion prior to bonding. Only a relatively low rate (7-14 %) of dentists used evidence-based dental techniques for bonding oxide ceramics. CONCLUSION: In adhesive cementation of all-ceramic restorations, the practices of surveyed dentists in Northern Germany revealed high rates of incorrect bonding. During the observation period, the values of evidence-based bonding procedures for oxide ceramics improved while the values for silicate ceramics declined. Based on these results, some survey participants need additional education for adhesive techniques. CLINICAL RELEVANCE: Neglecting scientifically accepted methods for adhesive cementation of all-ceramic restorations may result in reduced longevity of all-ceramic restorations.

Effectiveness of protecting a zirconia bonding surface against contaminations using a newly developed protective lacquer.

OBJECTIVES: The purpose of this study was to test the effectiveness of a newly developed lacquer and its ability to protect pre-conditioned bonding surfaces of zirconia ceramic against contamination with saliva or silicone remnants. METHODS: Disk-shaped zirconia ceramic specimens were conditioned and cleaned using air-abrasion. Before contamination with saliva or silicone, a newly developed protective lacquer (1% ethyl cellulose in ethanol) was applied to the bonding surface. After contamination, all specimens of the test groups were cleaned in an ultrasonic bath filled with 99% ethanol for 3 min and then air-dried. A universal primer (Monobond Plus) was applied to the surfaces and then the specimens were bonded to composite resin filled acrylic tubes using a luting resin (Multilink Automix). Each group (n=16) was divided into 2 subgroups (n=8). One subgroup was stored for 3 days in 37°C tap water and the other subgroup was stored for 150 days in 37°C tap water interrupted by 37,500 thermal cycles between 5°C and 55°C. After the storage, the bond strength was measured using a material testing machine. RESULTS: The specimens of the test groups showed comparable bond strengths to the positive control group after short-term storage. After artificial aging, bond strengths of the test groups were statistically significantly lower compared to the positive control and were statistically significantly higher compared to the negative control groups. SIGNIFICANCE: Overall, the use of the newly developed protective lacquer appears to be a promising approach to protect pre-conditioned surfaces of zirconia ceramics against contamination.

Using an audience response system to improve learning success in practical skills training courses in dental studies - a randomised, controlled cross-over study.

INTRODUCTION: The aim of this study was to examine whether the use of an audience response system (ARS) in a high-quality study design, in a course in pre-clinical dentistry leads to an improvement in cognitive and psycho-motor performance. MATERIALS AND METHODS: As part of the Phantom Course I, a randomised, controlled study in cross-over design with 63 students was conducted over 4 weeks. The intervention was carried out by means of an ARS (TurningPoint(®) ), while a verbal question-and-answer session was conducted within the control group. Differences in learning success were determined via a formative multiple-choice (MC) test (cognitive) and a summative practical test (psycho-motor). RESULTS: Both groups achieved significantly better results in the MC tests with the use of the intervention, when compared with the control group (group A 11.6 vs. 9.5 and group B 13.7 vs. 12.1, maximum 16 points). A further analysis of the results showed that the overall effect was induced primarily by a marked improvement in below-average students. The practical tests showed no clear effect. Despite the careful selection and set-up of the conditions for the study in the regular course of the semester, a cohort effect emerged. This was due to varying degrees of performance between the two groups, because no adequate performance parameters were available, which could have been taken into account for the stratified randomisation. CONCLUSIONS: The results indicate that the use of the ARS leads to better results in cognitive performance, especially where independent learning is required and should be encouraged. Weaker students in particular seem to benefit.