Methods: One hundred and eighty standardized disc samples were prepared, of which ninety samples each were used for surface roughness and microhardness test, respectively. They were divided equally into: Group 1 (Filtek-Z350-XT), Group 2 (Zmack-Comp), and Group 3 (Zr-Hybrid). For surface roughness test, all samples were polished with aluminium oxide discs and further subdivided into aged and unaged subgroups, in which composite samples in aged subgroups were subjected to 2500 thermal cycles. Next, all the samples were subjected to surface roughness test using a contact stylus profilometer. As for microhardness test, all the aged and unaged samples were tested using a Vickers hardness machine with a load of 300 kgf for 10 s and viewed under a digital microscope to obtain microhardness value. Data were analyzed using two-way ANOVA followed by post hoc Tukey's honestly significant difference and paired sample t-test with significance level set at P = 0.05.
Results: In both the aged and unaged groups, Zr-Hybrid showed statistically significantly lower surface roughness (P < 0.05) than Filtek-Z350-XT and Zmack-Comp, but no statistically significant difference was noted between Filtek-Z350-XT and Zmack-Comp (P > 0.05). A similar pattern was noted in microhardness test, whereby Zr-Hybrid showed the highest value (P < 0.05) followed by Filtek-Z350-XT and lastly Zmack-Comp. Besides, significant differences in surface roughness and microhardness were noted between the aged and unaged groups.
Conclusion: Zr-Hybrid seems to demonstrate better surface roughness and microhardness value before and after artificial ageing.
Aims: This study aims to evaluate and compare the bond strength and load deflection rate (LDR) of three different fixed retainer wires.
Materials and Methods: The wires were divided into three Groups: A - three-stranded twisted ligature wire, B - Bond-A-Braid (Reliance Orthodontics), and C - three-stranded twisted lingual retainer wire (3M Unitek). Twenty models were prepared for each group with a passive 15 mm long lingual retainer wire bonded to two lower incisors. An occlusogingival force was applied to the wire until it debonded. For LDR, three-point bending test was done at 0.5 mm deflection. These forces were measured using a Universal Instron Testing Machine.
Statistical Analysis: Mean bond strength/LDR and pairwise comparisons were analyzed with one-way ANOVA and Tukey's honest significant differencepost hoctest, respectively.
Results: Group C exhibited the highest mean bond strength and LDR of 101.17N and 1.84N, respectively. The intergroup comparisons were all statistically significant.
Conclusion: Compared to the other two wire types, Group C might be better retained on the teeth due to its higher bond strength. With its relatively higher LDR value, it may resist deformation from occlusal forces, thereby reducing inadvertent tooth movement and yet remain flexible enough to allow physiologic tooth movements.
METHODS: With REVO-S files up to SU/0.06 taper, 48 single-rooted premolar teeth were instrumented. The teeth were randomly divided into two main groups (n = 24) based on the two root canal sealers used (AH Plus and BioRoot RCS). All teeth were obturated with h matched-taper single-cone. Each main group was then subdivided into three subgroups (A, B, and C) (n = 8). Group A served as the negative control group (no-thermocycling aging). While groups B and C were subjected to thermal changes in a thermocycler machine (15,000 and 30,000 thermal cycles, respectively), followed by two different dynamic loading periods, 3 × 105 and 6 × 105 in a masticatory simulator with a nominal load of 5 kg at 1.2 Hz which represent roughly 1½ and 3 years of clinical function respectively. 2 mm slice at 3 levels, apical, middle, and coronal, to obtain 3 sections were prepared and subjected to push-out test using a universal testing machine. Statistical analysis was performed using analysis of variance (ANOVA) followed by a Tukey post hoc comparisons test and an independent T-test. A significance level of 5% was used.
RESULTS: After thermal-mechanical cyclic aging, the two root canal sealers showed a significantly decreased in push-out bond strength (p
METHODS: To this end, we evaluated the quantitative characteristics of top cited articles in the fields with a total citation (≥50) in the Web of Science (WoS) database. Using one-way independent ANOVA, data extracted spanning a period of 1980-2015 were analyzed, while the non-parametric data analysis uses Kruskal-Walis test.
RESULTS: Articles with 11 to 20 pages attract more citations followed by those within the range of zero to 10. Articles with upward 21 pages are the least cited. Surprisingly, articles with more than two authors are significantly (P<0.05) less cited and the citation decreases as the number of authors increased.
CONCLUSION: Collaborative studies enjoy wider utilization and more citation, yet discounted merit of additional pages and limited collaborative research in disability field is revealed in this study.