The immediate bonding effectiveness of contemporary adhesives is quite favorable, regardless of the approach used. In the long term, the bonding effectiveness of some adhesives drops dramatically, whereas the bond strengths of other adhesives are more stable. This review examines the fundamental processes that cause the adhesion of biomaterials to enamel and dentin to degrade with time. Non-carious class V clinical trials remain the ultimate test method for the assessment of bonding effectiveness, but in addition to being high-cost, they are time- and labor-consuming, and they provide little information on the true cause of clinical failure. Therefore, several laboratory protocols were developed to predict bond durability. This paper critically appraises methodologies that focus on chemical degradation patterns of hydrolysis and elution of interface components, as well as mechanically oriented test set-ups, such as fatigue and fracture toughness measurements. A correlation of in vitro and in vivo data revealed that, currently, the most validated method to assess adhesion durability involves aging of micro-specimens of biomaterials bonded to either enamel or dentin. After about 3 months, all classes of adhesives exhibited mechanical and morphological evidence of degradation that resembles in vivo aging effects. A comparison of contemporary adhesives revealed that the three-step etch-and-rinse adhesives remain the 'gold standard' in terms of durability. Any kind of simplification in the clinical application procedure results in loss of bonding effectiveness. Only the two-step self-etch adhesives approach the gold standard and do have some additional clinical benefits.

http://www.endoexperience.com/documents/DeMunketalDurabiltyofadhesionJDR.pdf

A Critical Review of the Durability of Adhesion to Tooth Tissue: Methods and Results

In vitro tests continue to be an indispensable method for the initial screening of dental materials. Thermal cycling is one of the most widely used procedures to simulate the physiological aging experienced by biomaterials in clinical practice. Consequently it is routinely employed in experimental studies to evaluate materials' performance. A literature review aimed to elucidate test parameters for in vitro aging of adhesive restorations was performed. This study aims to assess whether or not a standardized protocol of thermal cycling has been acknowledged from a review of the literature. An exhaustive literature search, examining the effect of thermal cycling on restorative dental materials, was performed with electronic database and by hand. The search was restricted to studies published from 1998 to August 2013. No language restrictions were applied. The search identified 193 relevant experimental studies. Only twenty-three studies had faithfully applied ISO standard. The majority of studies used their own procedures, showing only a certain consistency within the temperature parameter (5-55°C) and a great variability in the number of cycles and dwell time chosen. A wide variation in thermal cycling parameters applied in experimental studies has been identified. The parameters selected amongst these studies seem to be done on the basis of convenience for the authors in most cases. A comparison of results between studies would appear to be impossible. The available data suggest that further investigations will be required to ultimately develop a standardized thermal cycling protocol.

Thermal cycling for restorative materials: does a standardized protocol exist in laboratory testing? A literature review.

Objectives: Medical and dental students experience poor psychological well-being relative to their peers. This study aimed to assess the psychological well-being among medical and dental students in Saudi Arabia, identify the high-risk groups and assess the association between the psychological well-being and the academic performance.Methods: In this cross-sectional study, 422 preclinical medical and dental students at Umm Al-Qura University, Saudi Arabia, were recruited to assess their depression, anxiety, stress, self-efficacy and satisfaction with life levels using 21-items Depression Anxiety Stress Scale (DASS-21), General Self-Efficacy (GSE) scale and Satisfaction With Life Scale (SWLS). Students’ academic weighted grades were obtained later. Descriptive statistics and univariate general linear model were used to analyse data.Results: High levels of depression (69.9%), anxiety (66.4%) and stress (70.9%) were indicated, whereas self-efficacy (mean = 27.22, sd = 4.85) and life satisfaction (mea...

https://www.tandfonline.com/doi/pdf/10.3109/0142159X.2015.1006612

Psychological well-being status among medical and dental students in Makkah, Saudi Arabia: a cross-sectional study.

Aim: The study aims to evaluate and compare marginal microleakage in deep class II cavities restored with various techniques using different composites. Materials and Methods: Sixty freshly extracted teeth were divided into six groups of 10 teeth each. Standardized class II cavities were made and were restored using composites of different consistencies with different placement techniques. Group 1 with Microhybrid composite, Group 2 with Packable composite, Group 3 Microhybrid composite with a flowable composite liner, Group 4 Packable composite with a flowable composite liner, Group 5 Microhybrid composite with precured composite insert in second increment and Group 6 Packable composite with precured insert in second increment. Specimens then were stored in distilled water, thermocycled and immersed in 50% silver nitrate solution. These specimens were sectioned and evaluated for microleakage at the occlusal and cervical walls separately using stereomicroscope. Results: The results demonstrated that in the occlusal wall, packable composite, showed significantly more marginal microleakage than the other groups. In the cervical wall, teeth restored with a flowable composite liner showed less marginal microleakage when compared to all other groups. Conclusion: Based on the results of this study, the use of flowable composite as the first increment is recommended in deep class II cavities.

Effect of different placement techniques on marginal microleakage of deep class-II cavities restored with two composite resin formulations

Background and Objectives

The purpose of this study was to assess the performances of a single-component adhesive system when an Er:YAG laser was used to prepare cavities.



Study Design/Materials and Methods

Shear bond strength tests were performed on composite rods bonded with a single-component adhesive system to dentin surfaces prepared using either bur+acid, Er:YAG laser (fluence = 44 J/cm2), or Er:YAG laser+acid. Class V cavities were prepared differently according to the molar surface: buccal surfaces were prepared using a diamond bur, and lingual surfaces using the Er:YAG laser. In group 1, cavity walls were not acid treated after Er:YAG laser preparation. In group 2, only the enamel walls were acid treated. In group 3, all the enamel and dentin walls were acid treated. Microleakage was assessed using a methylene blue dye penetration method.



Results

Bond strength values did not differ significantly between the three groups (P = 0.162). Better marginal adaptation was obtained between the composite resin and cavity walls when Er:YAG laser preparation was followed by a total acid etching (P = 0.008).



Conclusions

Our results supported the use of single-component adhesive systems in cavities prepared using Er:YAG laser. The step of acid etching must be maintained for the whole cavity walls in regard of the microleakage values. Lasers Surg. Med. 38:615–623, 2006. © 2006 Wiley-Liss, Inc.

Er:YAG laser cavity preparation and composite resin bonding with a single-component adhesive system: Relationship between shear bond strength and microleakage

Statement of the problem Microleakage is a major factor contributing to the occurrence of secondary carious lesions around composite restorations. Purpose of study This in vitro study investigated the effect of thermocycling on microleakage of several composite Class V restorations. Material and methods One hundred twenty molars were randomly distributed into 6 groups of 20 teeth. Class V preparations were made in the buccal and lingual surfaces of each tooth and restored in bulk by use of 6 composites (Arabesk, Silux-Plus, Solitaire 2, Durafill VS, Charisma, and Renew) according to the manufacturers' recommendations. The teeth were stored in distilled water at room temperature for 24 hours. The teeth in each group were divided randomly into 2 subgroups: (a) thermocycled for 500 cycles between 5° and 55°C with a dwell time of 30 seconds, (b) no thermocycling treatment. All restored teeth were immersed in 1% methylene blue dye for 4 hours and sectioned buccolingually with a diamond wheel. Dye penetration was scored by use of a stereomicroscope at original magnification ×4. The generalized linear models statistical analysis was used (α=.05). Results The preparation margins (enamel/dentin) and thermocycling had a significant effect on microleakage ( P =.0351, P P =.1689). Conclusions Thermocycling significantly increased the microleakage ( P P =.0351).

The effect of thermocycling on microleakage of several commercially available composite Class V restorations in vitro.

The quarantine associated with the COVID-19 pandemic forced dental schools to suspend their clinical training and to shift to distant learning methods. The aim of this study is to investigate the impact of quarantine on the self-perceived preparedness of dental graduates and to explore the efficacy of online education from students’ perspectives. The questionnaire distributed to dental students comprised of two main sections. The first part covered the online education experience, and the second part measured the level of self-perceived preparedness for a range of cognitive, communication and professional skills. The survey yielded a response rate of 72%. The majority of students (77%) agreed that they missed educational experiences as a result of the lockdown. More than half of them felt less motivated to follow-up with distant e-learning and believed that online assessment is not a good method for evaluation. A high percentage of the students (66%) thought that online group discussions had a positive value while 67% preferred online lectures compared to theatre lectures. Majority of students particularly 5th year (78.7%) (p < 0.001) stated that the quarantine increased their collaboration with their colleagues. According to 87% of students, the experience most negatively affected was their clinical training. In general, students showed satisfactory self-perceived preparedness related to a range of attributes and professional skills. The data showed that students partially appreciated the online system, whereas they did not consider it a substitute for face to face clinical practice. The overall self-perceived preparedness level was promising; however students had reservations regarding independent practice following graduation.

/pdf/impact-of-covid-19-pandemic-on-dental-education-online-4k6zk340em.pdf

Impact of COVID-19 pandemic on dental education: online experience and practice expectations among dental students at the University of Jordan.

The purpose of this study was to see if gender-based differences exist in the performance of dental students at the University of Jordan (UJ), Amman. The retrospective analysis included data from two groups of students: 413 fourth-year dental students (178 males and 275 females) from four consecutive years (2005 through 2008) and 357 fifth-year students (128 males and 229 females) who graduated in the years 2005 to 2008. The influence of gender on the results of the fourth-year students in six theoretical and six clinical courses and the cumulative GPAs of the fifth-year students were studied. In both theoretical and clinical fourth-year courses, multivariate analysis of variance (MANOVA) revealed significant main differences in raw scores between the two gender groups. Female students were significantly better in five theoretical courses. In clinical courses, female students outscored male students in pediatric dentistry and prosthodontics, male students outperformed female students in conservative dentistry and orthodontics, and no significant gender differences were seen in oral surgery and fixed prosthodontics. The cumulative GPAs of the female graduated students were significantly higher than those of the male students. The results showed a significant relationship between gender and academic performance of dental students for these classes. The reasons for these findings should be further investigated.

Effect of gender on performance of undergraduate dental students at the University of Jordan, Amman.


 AbstractBackground: The quarantine associated with the COVID-19 pandemic forced dental schools to suspend their clinical training and to shift to distant learning methods. The aim of this study is to investigate the impact of COVID-19 quarantine on the preparedness of dental graduates and to explore the efficacy and limitations of online education from students’ perspectives. Methods: the questionnaire distributed to dental students comprised of two main sections; first part covered the online education experience and the second part measured the level of preparedness for a range of cognitive, communication and professional skills. Results: the survey yielded a response rate of 72%. The majority of students (77%) agreed that they missed educational experiences as a result of the lockdown. More than half of them felt less motivated in following-up with distant e-learning and believed that online assessment is not a good method for evaluation. A high percentage of the students (66%) thought that online group discussions has a positive value whilst 67% preferred online lectures compared to theatre lectures. Majority of students particularly 5th year (78.7%) (p<0.001) stated that the quarantine increased their collaboration with their colleagues. According to 87% of students, the experience most negatively affected was their clinical training.In general, students showed satisfactory preparedness related to a range of attributes and professional skills, however, nearly two-thirds of them prefer to be mentored and favor a structured year of residence. Conclusions: Data showed that students partially appreciated the online system, whereas they did not consider it a substitute for face to face clinical practice. The overall preparedness level was promising, however, some skills regarding evidence-based practice need consolidation. Students had reservations regarding independent practice following graduation.

/pdf/impact-of-covid-19-pandemic-on-dental-academia-students-15902v3ufs.pdf

Impact of COVID-19 pandemic on dental academia. Students’ experience in online education and expectations for a predictable practice.

Objective: This in vitro study compared the microleakage of resin composite restorations placed in Class II cavity preparations using an incremental placement technique with and without the addition of precured resin composite inserts. Method and materials: Sixty standardized mesio-occlusal and disto-occlusal cavities were prepared in 30 recently extracted molar teeth. Twenty cavities were restored by employing the incremental placement technique (group I), and 40 cavities were restored using the incremental placement in the presence of precured composite inserts of two sizes: 1X 3 mm (group II) and 1.25 X 3 mm (group III). The restored teeth were thermocycled for 250 cycles in water baths set at temperatures of 5°C and 50°C using a 30-second dwell time, stained, and sectioned horizontally at the middle of the restoration. Following sectioning, each specimen was microscopically examined at X4 magnification. The extent of dye penetration at the tooth/restoration interface was scored for each test group, and the scores obtained were subjected to one-way analysis of variance (ANOVA) and Tukey's pairwise comparison at a 95% significance level. Results: The current investigation showed statistically significant differences in dye penetration between the three test groups. Conclusion: The use of precured resin composite inserts with the incremental placement technique in the restoration of Class II cavity preparations seems to improve the marginal seal of the proximal walls of finished restorations.

Fouad Kadim Wahab

Papers

The effect of thermocycling on microleakage of several commercially available composite Class V restorations in vitro.

Impact of COVID-19 pandemic on dental education: online experience and practice expectations among dental students at the University of Jordan.

Effect of gender on performance of undergraduate dental students at the University of Jordan, Amman.

Impact of COVID-19 pandemic on dental academia. Students’ experience in online education and expectations for a predictable practice.

Evaluation of the microleakage at the proximal walls of Class II cavities restored using resin composite and precured composite inserts