Introduction: The removal of ceramic veneers is a time-consuming procedure in a dental office. Little research has been done in alternative removal techniques for ceramic veneers. The objective of this study was to evaluate the removal of feldspathic and lithium disilicate reinforced glass ceramic veneers by Er, Cr: YSGG and to measure DEBONDING time and pulpal temperature increase during veneer removal. Methods: Fifty-seven bovine incisor teeth were prepared and divided into 3 groups. Ceramic specimens with a thickness of 0. 7mm, a width of 4mm and a length of 8 mm were fabricated from feldspathic ceramic, lithium disilicate reinforced glass ceramic HT (high translucency) and lithium disilicate reinforced glass ceramic MO (medium opacity) (19 for each group). Specimens were cemented on the labial surface of incisors using resin cement. The Er, Cr: YSGG laser was applied to each specimen at 2. 5 W and 25 Hz. DEBONDING time was measured for each specimen, and the intrapulpal temperature was detected in 3 specimens for each group. Data were analyzed via one-way analysis of variance (ANOVA) at significance level of 0. 05 (α = 0. 05). Results: Mean DEBONDING time was 103. 68 (26. 76), 106. 58 (47. 22) and 103. 84 (32. 90) seconds for feldspathic, lithium disilicate MO, and lithium disilicate HT respectively. There was no significant statistical difference among the groups (P value = 0. 96). The intrapulpal temperature increase was less than 1° C in all groups. Conclusion: Er, Cr: YSGG can successfully be used to efficiently debond feldspathic and lithium disilicate reinforced glass ceramic veneers. There was no significant difference for DEBONDING time among these ceramic materials. During ceramic laminate veneer removal by laser irradiation, no irritating temperature rise was detected.

Different techniques have been introduced for the removal of ceramic brackets. Since the early 1990s, lasers have been used experimentally for DEBONDING ceramic brackets. The goal of this study is to give a comprehensive literature review on laser-aided ceramic bracket DEBONDING. PubMed and Google Scholar databases were used to identify dental articles with the following combination of key word: Ceramic brackets, DEBONDING, and Laser. Sixteen English articles from 2004 to 2015 were selected. The selected studies were categorized according to the variables investigated including the intrapulpal temperature, shear bond strength, DEBONDING time, enamel damage and bracket failure. Most articles reported decreased shear bond strength and DEBONDING time following laser irradiation without any critical and irritating increase in pulpal temperature. There were no reports of bracket failure or enamel damage. Laser irradiation is an efficient way to reduce shear bond strength of ceramic bracket and DEBONDING time. This technique is a safe way for removing ceramic bracket with minimal impact on intrapulpal temperature and enamel surface and it reduces ceramic bracket failure.

One of the causes of prosperity and success in the construction industry and one of the most common DEBONDING is the DEBONDING of the concrete cover and the separation of the concrete surface and the reinforcement plate. This paper evaluated the beams in the experiments due to an external force applied perpendicular to the longitudinal axis. The five reinforced concrete beams test specimen dimensions were 200×140×1300 mm, with rebar 10 for the bottom and 6 for the top, rebar 8 for the girders, and the concrete grade was considered 350. The final strength of 28 days with GFRP fibers in two layers, three classic layers, two layers, and three U-shaped layers are subjected to a four-point bending test. A control specimen was used for evaluation. The experimental results showed that the three U-shaped GFRP layers performed better than the other specimens and performed better in the biaxial bending test. The three U-shaped GFRP layers sheet had the most significant effect on flexural reinforcement and prevention of DEBONDING compared to the classic U-shaped two-layer, three-layer, and two-layer GFRP sheets. In addition, Two U-shaped layers have more resistance to external load pressure than a U-shaped layer and have a more significant impact.

Introduction: Er: YAG laser is a non-destructive tool for DEBONDING of laminate veneers. This study investigated the effect of different laser powers on the pulp temperature and the time required to perform the DEBONDING of lithium disilicate laminate veneers with different thicknesses. Methods: The labial enamel of 48 maxillary central incisors was flattened and polished. The teeth were restored with flat lithium disilicate ceramic veneers (4. 0 mm × 6. 0 mm) with one of two different thicknesses (0. 5 and 1. 0 mm). Veneer DEBONDING was performed with an Er: YAG laser with a wavelength of 2940 nm, pulse duration of 100 μ, m (VSP mode), 10 Hz, and one of the three laser power settings: 1. 5 W (150 mJ), 3. 0 W (300 mJ). and 5. 4 W (540 mJ) (n = 8). Veneer detachment time and intra-pulp temperature change (Δ, T) were measured. Statistical analysis was performed using the two-way ANOVA and Bonferroni’, s post hoc test (α,= 0. 05). The correlation between DEBONDING time and temperature change was calculated using Pearson’, s correlation. Results: The longest time was recorded to remove the 1. 0-mm veneer at 1. 5 W (P < 0. 05) and the shortest time was recorded when deboning the 0. 5 mm veneer with 5. 4 W (P < 0. 05). Δ, T decreased significantly with increasing laser power. A low correlation was found between time and Δ, T (R²,= 0. 113). Conclusion: Laser power and veneer thickness are important factors for veneer DEBONDING,thinner veneers are removed faster. When DEBONDING thick veneers, 5. 4W laser power is more efficient and causes fewer changes to the pulp temperature.

Statement of Problem: The risk of the enamel damage increases if the DEBONDING fracture site shifts toward the junction between the enamel and adhesive.Purpose: The aim of this study was to determine the in-vitro bond strength and the fracture site after DEBONDING the mechanically-bonded ceramic and metallic brackets.Materials and Method: Sixty extracted premolars were randomly selected from orthodontic patients in a private clinic. All the samples were divided into two groups and 30 metallic and 30 ceramic brackets were mechanically bonded to the teeth, using light curing adhesive. After one week, all the brackets were debonded by bracket-removing pliers assembled on a testing machine. This design simulated clinically-applied DEBONDING compressive forces precisely. By the use of stereomicroscope and trans-illumination technique, the amount of adhesive remnant on the brackets' surfaces or on the teeth was evaluated and calculated using Photoshop and Auto Cat software program in the bonded areas in order to determine different fracture sites. Descriptive analysis was used to describe the findings and independent t-test was used to compare the differences between the two bracket groups.Results: DEBONDING fracture was mostly observed in the interface between brackets and adhesive and within adhesive but there were no statistically significant differences in the location of the DEBONDING fracture between the two groups.Conclusion: The risk of enamel damage after DEBONDING both metallic and ceramic brackets is low due to the minimal chance of DEBONDING failure between the enamel and adhesive.

One of the most important applications of nanomaterials in polymer resins is to achieve high fracture toughness even in small volume fractions of filler nanoparticles. Such performance is related to energy released through damage mechanisms that occur at the nano scale. Among these mechanisms, nanoparticle surface separation is more important. In the present work, considering the hierarchical structure of nanocomposites, it has been tried to investigate the effect of DEBONDING of graphene nanoparticles from the surrounding resin on the fracture toughness of the first mode of the presented epoxy/graphene nanocomposite using a multi-scale method. Therefore, a representative volume element has been selected and using the data available in the experimental works of other researchers, the effect of several parameters such as Young's modulus, weight fraction and dimensions of nanographene was investigated. Finally, it was observed that the fracture toughness has a direct relationship with the Young's modulus of the nanocomposite. Also, the smaller the dimensions of the nanoparticles used, the greater the improvement in the fracture toughness.