جستجوی مقالات مرتبط با کلیدواژه "براکت سرامیکی" در نشریات گروه "پزشکی"

Friction between the archwire and bracket is the main problem during tooth movement. Self-ligating bracket systems have become common in recent years. The aim of this study was to investigate and compare the effect of active and passive esthetic self-ligating brackets on static frictional force with different orthodontic archwires under wet conditions.

This in vitro study included 180 ceramic self-ligating brackets, 90 passive brackets (Damon Clear), and 90 active brackets (Empower Clear), which were tested for frictional resistance using three different types of 0.018-inch archwires, namely copper NiTi archwires and two esthetic archwires (Epoxy- and rhodium-coated NiTi archwires). According to the types of brackets and archwires, six groups of ten were defined. An experimental model with three non-leveled brackets in wet condition using artificial saliva was adopted. The friction test was conducted by Instron Tinius Olsen testing device. The test was performed at a room temperature ranging from 24-25°C.

Empower clear with Cu NiTi archwire showed the highest mean value of static frictional force with the mean value of (327.85±53.43) and Damon clear with epoxy coated NiTi archwire showed the lowest mean value (58.06±10.87). There were significant differences in the static frictional forces generated in both bracket systems when coupled with the Epoxy wires (p=0.000) and when coupled with the CuNiTi and Rhodium archwires (p=0.001).

The result of this study showed that the Damon Clear brackets produce lower frictional forces than Empower Clear brackets and Epoxy-coated NiTi archwires can produce lower static frictional force compared to Rhodium-coated NiTi and CuNiTi archwires.

The bonding process is highly important in orthodontic treatment for its fast speed. The purpose of this study was to compare the shear bond strength of ceramic and metallic brackets between three stage (transbondTM XT) and two stage (GC ortho connectTM) light cure composites.

In this experimental study, 80 maxillary and mandibular first and second premolar teeth, extracted for the purpose of orthodontic treatment, were randomly divided into four groups (n=20 per group). All teeth were etched using 35% phosphoric acid. They were then bonded with metallic brackets with GC ortho connectTM composite (group I), and TransbondTM XT composite (group II), and ceramic brackets with GC ortho connectTM composite (group III) and TransbondTM XT composite (group IV). The shear bond strength of the brackets was measured by universal testing machine 24 hours after thermocycling and mounting procedures. The amount of resin remained on the tooth surface was determined by stereomicroscope. Data were analyzed by SPSS V22 applying Kruskal–Wallis one-way analysis of variance.

The average shear bond strength in groups I, II, III, and IV were 18.71±1.99, 19.82±8.75, 18.4±5.78, and 18.5±52.42 MPa, indicating no significant differences between the groups studied (P> 0.05). Also, we found no significant differences in adhesive remnant index (ARI) between all groups (P=0.641).

The shear bond strength of GC ortho connectTM composite was similar to that of the TransbondTM XT composite in both metallic and ceramic brackets. Therefore, GC ortho connectTM can serve as a substitute for TransbondTM XT.

Debonding of ceramic brackets results in enamel damage and bracket fracture due to a strong bond of ceramic brackets and low fracture resistance. The aim of this study was to compare enamel damage upon debonding of ceramic brackets with and without CO2 laser in orthodontic treatment. Materials &

In this experimental study, 44 extracted first premolar teeth were selected and randomly divided into two groups (n = 22). After bonding, the teeth were divided into two group with and without the use of CO2 laser for debonding of brackets. A stereomicroscope was used at ×10 to determine the exact number and length of enamel cracks before and after debonding of the brackets. Data were analyzed with paired t-test and t-test using SPSS 23 (α = 0.05).

In the group without laser, the rate of enamel fracture was 4.5% and in 9.1% of the cases there were fractures in the bracket base. There were no fractures or cracks in the enamel or bracket bases. In this group, the mean length of cracks was significantly low (p value < 0.001). There were significant differences in the lengths of the cracks in both groups before and after debonding (p value < 0.018). Although the number of cracks in the enamel in both groups increased after debonding, this increase was not significant in the laser group (p value < 0.001).

Debonding of ceramic brackets with CO2 laser resulted in a decrease in enamel damage during debonding.

Statement of the problem: 

New techniques have recently been employed to reduce the time used for clinical procedures and multi-step polishing systems have been replaced by one-step systems.

Determination of the effect of multi-step and one-step polishing systems on microhybrid and nanofilled composites and ceramic restorations.

Point-4 and Premise composites and Colorlogic porcelain were selected for this study. 33 specimens of each material were prepared. Composite specimens were cured with LED-Starlight. Porcelain specimens were prepared according to the manufacture's instruction. All the specimens were roughened with 25 diamonds and then polished with Enhance (3 steps), Super-Snap (4 steps) and One-Gloss (1 step) polishing systems. Roughness was measured with Taylor-Hobson-Surtronic profilometer. The data was analyzed with one-way ANOVA and Duncan's tests.

Mean surface roughness of cured or glazed surfaces, roughened surfaces, surfaces polished with Enhance, Super-Snap and One-Gloss were 0.39, 2.49, 0.54, 0.44 and 0.45 for Point-4 and 0.31, 2, 0.42, 0.38, 0.39 for Premise and 1.19, 1.38, 0.65, 0.64, 0.57 for Colorlogic, respectively. The difference of surface roughness between roughened subgroups and other subgroups in the composite group was significant. Also, glazed and roughened porcelain specimens were significantly different. Differences between glazed porcelain, cured composites and roughened surfaces of the three materials were significant. The specimens polished with Enhance had a significant difference (P<0.05).

Multi-step polishing systems can be replaced by one-step systems for polishing of composite and porcelain restorations.