584 research outputs found
Bonding with Self-etching Primers – Pumice or Pre-etch? An \u3cem\u3ein vitro\u3c/em\u3e Study
The purpose of this study was to compare the shear bond strengths (SBSs) of orthodontic brackets bonded with self-etching primer (SEP) using different enamel surface preparations. A two-by-two factorial study design was used. Sixty human premolars were harvested, cleaned, and randomly assigned to four groups (n = 15 per group). Teeth were bathed in saliva for 48 hours to form a pellicle. Treatments were assigned as follows: group 1 was pumiced for 10 seconds and pre-etched for 5 seconds with 37 per cent phosphoric acid before bonding with SEP (Transbond Plus). Group 2 was pumiced for 10 seconds before bonding. Group 3 was pre-etched for 5 seconds before bonding. Group 4 had no mechanical or chemical preparation before bonding. All teeth were stored in distilled water for 24 hours at 37°C before debonding. The SBS values and adhesive remnant index (ARI) score were recorded. The SBS values (±1 SD) for groups 1–4 were 22.9 ± 6.6, 16.1 ± 7.3, 36.2 ± 8.2, and 13.1 ± 10.1 MPa, respectively. Two-way analysis of variance and subsequent contrasts showed statistically significant differences among treatment groups. ARI scores indicated the majority of adhesive remained on the bracket for all four groups. Pre-etching the bonding surface for 5 seconds with 37 per cent phosphoric acid, instead of pumicing, when using SEPs to bond orthodontic brackets, resulted in greater SBSs
Bonding with Self-etching Primers – Pumice or Pre-etch? An \u3cem\u3ein vitro\u3c/em\u3e Study
The purpose of this study was to compare the shear bond strengths (SBSs) of orthodontic brackets bonded with self-etching primer (SEP) using different enamel surface preparations. A two-by-two factorial study design was used. Sixty human premolars were harvested, cleaned, and randomly assigned to four groups (n = 15 per group). Teeth were bathed in saliva for 48 hours to form a pellicle. Treatments were assigned as follows: group 1 was pumiced for 10 seconds and pre-etched for 5 seconds with 37 per cent phosphoric acid before bonding with SEP (Transbond Plus). Group 2 was pumiced for 10 seconds before bonding. Group 3 was pre-etched for 5 seconds before bonding. Group 4 had no mechanical or chemical preparation before bonding. All teeth were stored in distilled water for 24 hours at 37°C before debonding. The SBS values and adhesive remnant index (ARI) score were recorded. The SBS values (±1 SD) for groups 1–4 were 22.9 ± 6.6, 16.1 ± 7.3, 36.2 ± 8.2, and 13.1 ± 10.1 MPa, respectively. Two-way analysis of variance and subsequent contrasts showed statistically significant differences among treatment groups. ARI scores indicated the majority of adhesive remained on the bracket for all four groups. Pre-etching the bonding surface for 5 seconds with 37 per cent phosphoric acid, instead of pumicing, when using SEPs to bond orthodontic brackets, resulted in greater SBSs
On spatial adaptivity and interpolation when using the method of lines
The solution of time-dependent partial differential equations with discrete time static remeshing is considered within a method of lines framework. Numerical examples in one and two space dimensions are used to show that spatial interpolation error may have an important impact on the efficiency of integration. Analysis of a simple problem and of the time integration method is used to confirm the experimental results and a computational test for monitoring the impact of this error is derived and tested
Longitudinal spin-relaxation in nitrogen-vacancy centers in electron irradiated diamond
We present systematic measurements of longitudinal relaxation rates ()
of spin polarization in the ground state of the nitrogen-vacancy (NV) color
center in synthetic diamond as a function of NV concentration and magnetic
field . NV centers were created by irradiating a Type 1b single-crystal
diamond along the [100] axis with 200 keV electrons from a transmission
electron microscope with varying doses to achieve spots of different NV
center concentrations. Values of () were measured for each spot as a
function of .Comment: 4 pages, 8 figure
New supersymmetric quartet of nuclei in the A=190 mass region
We present evidence for a new supersymmetric quartet in the A=190 region of
the nuclear mass table. New experimental information on transfer and neutron
capture reactions to the odd-odd nucleaus 194 Ir strongly suggests the
existence of a new supersymmetric quartet, consisting of the 192,193 Os and
193,194 Ir nuclei. We make explicit predictions for the odd-neutron nucleus 193
Os, and suggest that its spectroscopic properties be measured in dedicated
experiments.Comment: 5 pages, 4 figures, updated figures and revised text, Physical Review
C, Rapid Communication, in pres
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