1,720,979 research outputs found
Development of a novel bioceramic root canal sealer and its effect on the dislodgement resistance and dentinal tubule penetration
Full text linkThe present study aimed to fabricate and characterise novel algin-incorporated
bioactive glass 58S calcium-silicate root canal sealer (Bio-G) and evaluate its effect
on the dislodgement resistance and dentinal tubule penetration to root dentinal walls
in comparison to commercially available bioceramic-based sealers (BioRoot RCS and
iRoot SP). Three groups of bioactive glass (BG) 58S powders were synthesised using
sol-gel method and characterised using SEM, HRTEM and FTIR for optimisation:
BG-1 (no ammonia), BG-2 (3 ml of ammonia), and BG-3 (5 ml of ammonia).
Optimised BG-3 was used to fabricate the powder form of experimental Bio-G sealer
with the addition of calcium silicate, zirconia dioxide, calcium carbonate and alginic
acid powder. Meanwhile, the liquid form composed of 5% calcium chloride solution.
The experimental 0-5% algin Bio-G sealers were then compared with BioRoot RCS
and iRoot SP. Standardised disc specimens of mixed sealer materials (n=5 per group)
were prepared and placed in an incubator to allow setting before characterising under
SEM, HRTEM, EDS, FTIR and XRD. Next, one-hundred-and-seventy-six mandibular
premolars were randomly assigned (n=16 per group): control, gutta-percha + 0-5%
algin Bio-G, gutta-percha + BioRoot RCS, and gutta-percha + iRoot SP groups, with
the exclusion of the control group in adhesive pattern and dentinal tubule penetration
tests. They were instrumented, obturated and placed in an incubator for 72 hours to
allow sealer set. For the dentinal tubule penetration test, sealers were mixed with 0.1%
of rhodamine B dye. Subsequently, teeth were cut into a 1-mm-thick cross-section at 5-mm and 10-mm levels from the root apex, respectively. Push-out bond strength,
adhesive pattern and dentinal tubule penetration tests were performed. Experimental
Bio-G sealer revealed irregular micro-sized particles with a higher content of oxygen,
silicon, and calcium, as well as trace of aluminium and chloride. Meanwhile, FTIR
and XRD findings suggested that all sealers predominantly contained calcium silicate
hydrate, calcium carbonate, and zirconium dioxide, while calcium aluminium silicate
oxide was detected in 0-5% algin Bio-G. 5% algin Bio-G showed the highest mean
push-out bond strength (p<0.05) with more favourable adhesion pattern, while iRoot
SP showed the greatest sealer penetration (p<0.05). In addition, no significant
association was noted between the dislodgement resistance and dentinal tubule
penetration (p>0.05). In conclusion, the present novel Bio-G sealer demonstrated
desirable particle size distribution and acceptable degree of purity. Algin-incorporated
Bio-G showed favourable adhesive pattern with comparable dislodgement resistance
and dentinal tubule penetration values to commercialised bioceramic-based sealers
Polymerization shrinkage, degree of conversion of zirconia reinforced rice husk nanohybrid composite and its fracture strength on the endodontically treated maxillary incisors
Full text linkThe present study aimed to compare the polymerization shrinkage, degree of
conversion and fracture strength of endodontically treated maxillary lateral incisors
restored using novel zirconia reinforced rice husk nanohybrid composite with
commercialized microhybrid and nanofilled composites. 180 samples were used for
polymerization shrinkage and degree of conversion tests, divided into Group 1 –
nanofilled composite (Filtek-Z350-XT), Group 2 – microhybrid composite (Zmack-
Comp) and Group 3 – experimental nanohybrid composite (Zr-Hybrid). The test for
polymerization shrinkage was performed using buoyancy and optical methods. For the
buoyancy method, samples were weighed in air and water to calculate the shrinkage
value, while for the optical method, images of samples before and after light-curing were
captured using a microscope to calculate the shrinkage value. The conversion degree was
tested using the FTIR spectrometer. Eighty mature permanent lateral maxillary incisors
were selected for the fracture strength test and divided into: Group 1 – ET + Filtek-Z350-
XT, Group 2 – ET + Zmack-Comp, Group 3 – ET + Zr-Hybrid and Group 4 – Intact teeth
(control). Standardised MPD cavity was prepared, and endodontic treatment was
performed using crown-down technique up to size 30. Obturation was completed using
single cone technique with gutta-percha and AH Plus sealer. Cavity access was restored
with respective composite resins. Next, the teeth were stored in the incubator for 24 hours
and subdivided into aged and non-aged subgroups. Teeth in aged subgroups underwent
2,500 thermal cycles. Subsequently, all teeth were tested under the Universal Testing
Machine until fractures occurred. They were then examined under a microscope to
determine the fracture pattern and type of fracture. Data were analysed using One-way
ANOVA for polymerization shrinkage, conversion degree and fracture strength. The
fracture pattern and fracture type were analysed using the Chi-square test. Zr-Hybrid
showed comparable shrinkage (p>0.05) to Filtek-Z350-XT, but lower shrinkage (p<0.05)
than Zmack-Comp. Zr-Hybrid showed a higher conversion degree (p<0.05) than Filtek-
Z350-XT and a comparable conversion value with Zmack-Comp. Besides, ET + Zr-
Hybrid demonstrated the highest fracture strength in both aged and unaged subgroups.
The fracture strength decreased significantly in ET + Filtek-Z350-XT and ET + Zmack-
Comp (p<0.05) as the thermocycles increased but no significant differences were noted
in ET + Zr-Hybrid and control Group 4. Moreover, ET + Zr-Hybrid and control Group 4
showed more favourable fracture pattern. In conclusion, Zr-Hybrid exhibited excellent
shrinkage and conversion values. Endodontically treated teeth restored with Zr-Hybrid
demonstrated superior fracture strength and favourable fracture pattern
Interdisciplinary Approaches for Integrating Materials Science and Dentistry
Full text linkDental materials science is a core course in most undergraduate dental curricula [...
Navigating the assessment landscape: dental students’ perceptions of extended-matching questions versus single-correct answers
No full textPurpose: The present study aims to evaluate students’ perceptions of different types of written assessment within the context of dental materials science and to identify how various learning styles exhibited by dental students, as well as gender and ethnicity, may influence their perceptions of these assessment methods.
Methods: The study was conducted among second-year dental students in a dental materials science class, during which students participated in a mock assessment that included extended matching questions (EMQs) and single correct answer (SCA) questions. An online questionnaire comprising three sections: demographic information, Honey and Mumford’s Learning Styles Questionnaire, and 15 closed-ended questionnaire items employing a 5-point Likert scale were administered to assess students’ perceptions of the assessment methods. Statistical analyses were conducted using the Kruskal-Wallis test, Mann-Whitney U test, and a post-hoc Bonferroni test.
Results: All 70 students participated in the study with the majority being female, Chinese, and activist learners. Median total scores among various learning styles, gender, and ethnicity did not exhibit significant differences. Analysis of individual questionnaire items revealed mixed perceptions regarding EMQs. Reflectors generally held more positive perceptions of EMQs, while theorists showed the lowest total median scores toward EMQs. Most students did not prefer EMQs over SCAs, and some students expressed confusion about EMQs, especially those with a theorist learning style.
Conclusion: Although students generally showed good perceptions towards these assessment methods, further research is needed to better understand the interplay of learning styles, assessment preferences, and educational outcomes in dental education
Innovative Pedagogical Strategies in Health Professions Education: Active Learning in Dental Materials Science
Full text linkDental materials science education is frequently delivered via traditional didactic lectures in preclinical dental programs. This review aimed to appraise the current evidence on innovative pedagogical strategies in teaching dental materials science courses. English-language articles on teaching methods for dental materials science published between January 1990 to October 2022 were searched in nine online databases (Google Scholar, PubMed, Web of Science [WoS], Science Direct, Cochrane Library, EBSCO, LILACS, Open Grey, and EMBASE) according to PRISMA guidelines. The risk of bias (RoB) was assessed using the Cochrane RoB-2 and ROBIN-I tools, whereas the level of evidence was determined based on the OCEBM guidelines. Only 12 primary studies were included. Two randomized studies (RCTs) were deemed as being of “some concern”, and one showed a high risk of bias (RoB). Three non-randomized controlled studies (NRS) demonstrated a moderate RoB, whereas the remaining seven were low. Most studies were ranked at Levels 2 and 3 of evidence. Several innovative pedagogical strategies were identified: flipped classrooms, clinical-based learning, computer-assisted learning, group discussion, microteaching with the BOPPPS (bridge-in, learning objective, pre-test, participatory learning, post-test, and summary) model, and game-based learning. The evidence suggested that students generally showed positive perceptions toward these pedagogical strategies. Dental educators should revise their current undergraduate dental materials science curricula and integrate more effective teaching methods
Students’ perceptions towards the ethical considerations of using artificial intelligence algorithms in clinical decision-making
No full textAbstract
Aim: The present study aimed to explore the perceptions of dental students regarding the ethical considerations associated with the use of artificial intelligence (AI) algorithms in clinical decision-making.
Methods: All the undergraduate clinical-year dental students were invited to take part in the study. A validated online questionnaire which consisted of 21 closed-ended questions (five-point Likert scales) was distributed to the students to evaluate their perceptions on the topic. Mean perception scores of the students from different years were analysed using a one-way ANOVA test, while independent t-tests were used to compare the scores between sexes.
Results: In total, 165 students participated in the present study. The mean age of the respondents was 23.3 (±1.38) years and the majority were female, Chinese students. Respondents showed positive perceptions throughout all three domains. Uniform and comparable perceptions were seen across various academic years and sexes, with female respondents expressing stronger agreement regarding patient consent and privacy prioritisation.
Conclusion: Undergraduate clinical dental students generally showed positive perceptions regarding the ethical considerations associated with the integration of AI algorithms in clinical decision-making. It is essential to address these ethical considerations to ensure that AI benefits patient outcomes while upholding fundamental ethical principles and patient-centred care
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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