Top PDF Comparison of Shear Bond Strength of Three Generations of Resin Bonding Agents and Glass Ionomer to Dentin

Comparison of Shear Bond Strength of Three Generations of Resin Bonding Agents and Glass Ionomer to Dentin

Comparison of Shear Bond Strength of Three Generations of Resin Bonding Agents and Glass Ionomer to Dentin

demineralized dentin [22]. It has been confirmed that such strong acidity significantly decreases the bond strength of these adhesives to dentin [30-32]. However, mild self-etch adhesives have a pH of approximately 2 and cause one micrometer deep demineralization in dentin and result in the formation of a relatively thin hybrid layer [31, 33]. A new series of self-etch adhesives were recently introduced into the market and Opti Bond XTR, used in the current study, is one of them. They have a pH of approximately 1.5 and are classified as moderate acidity self-etch adhesives. They have the advantages of both mild and strong self-etch adhesives and create a hybrid layer with adequate thickness. This layer, with relative demineralization at the base of the hybrid layer, serves as a mild self-etch adhesive and enables formation of chemical bonds [22]. This may explain the higher bond strength of Opti Bond XTR in this study in contrast to previous studies. Also, the results of the current study showed that GC Fuji Bond LC showed no significant difference in SBS in two forms of pre-cure and co-cure and this result is in accord with the findings of Tulunoglu et al [27].
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The Effect of Incorporation of 0.5 %wt. Silica Nanoparticles on the Micro Shear Bond Strength of a Resin Modified Glass Ionomer Cement

The Effect of Incorporation of 0.5 %wt. Silica Nanoparticles on the Micro Shear Bond Strength of a Resin Modified Glass Ionomer Cement

Shear bond strength is a simple and widely used test to assess the bonding performance of restorative material, particularly regarding the glass ionomer ce- ments, which present low bond strength [20-21, 24, 26]. Recently, the µSBS test has become popularized as an alternative to the conventional shear bond test. In the µSBS test, the stress distribution is more concentrated at the interface compared with the conventional shear bond test. This would decrease the chance of cohesive failure in the material or enamel/dentin that does not display the true interfacial bond strength [20-21, 27-28]. This method is an especially useful test for those sub- strates that are susceptible to the specimen preparation effects and micro tensile bond strength testing condi- tions, such as glass ionomer or enamel [21, 28-29]. However, there are some questions concerning the in- terdependence of multiple specimens from the same tooth in micro test, which may exaggerate the statistical significance levels for comparison between materials. It is highly possible that the measurements originating from one tooth would be biased by the individual featur-
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In vitro Comparison of the Shear Bond Strength of Etch & Rinse vs Self-Etch Bonding Systems on Dentin after Nonvital Tooth Bleaching

In vitro Comparison of the Shear Bond Strength of Etch & Rinse vs Self-Etch Bonding Systems on Dentin after Nonvital Tooth Bleaching

Materials & Methods: Forty eight human sound premolars were selected and sectioned 5mm below the CEJ. In order to do the bleaching process, the access cavity preparation was done and after the excavation of pulp tissue, and placement of the hybrid glass ionomer base at the apex, the teeth were bleached using the 35% hydrogen peroxide for 4 times. The teeth were then embedded in a self-cured acrylic resin and polished to obtain a flat dentin surface. The teeth were assigned into 4 groups according to the adhesive system used (n=12): group 1: Single Bond (SB), group 2: Prime & Bond NT (P&B), group 3: Clearfil SE Bond (CSE) and group 4: Opti Bond (All in one) (OB). The adhesive systems were used according to the manufacturer’s instructions and a cylinder of composite resin Z100 was overlied. The teeth were thermocycled and the shear bond strength tests were performed in a universal testing machine with cross head speed of 1mm/min.
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Evaluation and Comparison of Shear Bond Strength of Glass Ionomer, Resin modified Glass Ionomer and Composite Resin in Primary Molars:  An Invitro study

Evaluation and Comparison of Shear Bond Strength of Glass Ionomer, Resin modified Glass Ionomer and Composite Resin in Primary Molars: An Invitro study

The purpose of this study was to determine and compare the shear bond strength of a conventional glass- ionomer cement (Fuji IX), a resin modified glass ionomer cement (Fuji II LC) and a composite resin (Filtek Z-250). Dentin of the buccal surfaces from ninety extracted human primary molars were prepared for shear bond strength testing. The specimens were randomly divided into 3 groups of 30 each. Dentinal surfaces were treated according to the instructions of manufacturers for each material. Each restorative material was placed inside a plastic matrix 2mm high with an internal diameter of 3mm, which was placed perpendicular to dentin surfaces. Shear bond strength was tested using an Universal Testing Machine at crosshead speed of 0.5mm/minute in a compression mode.
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The Effect of Disinfection with Chlorhexidine on the Shear Bond Strength of Equia Resin-Modified Glass Ionomer Cement to Dentin in Permanent Teeth after Two Thermocycling Protocols

The Effect of Disinfection with Chlorhexidine on the Shear Bond Strength of Equia Resin-Modified Glass Ionomer Cement to Dentin in Permanent Teeth after Two Thermocycling Protocols

In comparison with composite resins, RMGICs self-adhere to hard tissue, thanks to the micromechanical interlocking of their constituents. Moreover, their mechanism of attachment to dentin is somewhat different; so that they attach to the dentin through a chelation reaction, followed by metal ion exchange, and formation of a layer between the GI and tooth structure. [15-17] Yet, it is still unclear how CHX may affect the quality of GI-tooth structure interactions. In a study on Vitremer, 2% CHX did not interfere with the microtensile bond strength of RMGI to the primary tooth dentin. [18] Few studies on Fuji II LC restorative material showed that disinfection with CHX had no negative effect on its bond strength to permanent tooth dentin after 24 hours. [19- 20] Yet, the long-term bond strength between this material and dentin was reported to have significantly decreased. [20]
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Shear Bond Strength of Resin Bonded to Bleached Enamel Using Different Modified 35% Hydrogen Peroxides

Shear Bond Strength of Resin Bonded to Bleached Enamel Using Different Modified 35% Hydrogen Peroxides

Various methods have been suggested to improve the compromised bond to the bleached enamel and dentin, including using antioxidant materials [26-27], postponing the procedure for 24 hours to three weeks [20,28-30], and applying whitening agents with fluoride [31]. CPP-ACP has been demonstrated in animal and human studies to significantly reduce caries activity and promote the enamel subsurface remineralization. CPP-ACP advances remineralization by giving a supply of Ca 2+ and PO4 2- ions near the tooth surface and permits mobilization of these ions in regions of acid challenge [11,32]. The result of our study revealed that the concomitant use of CPP-ACP and hydrogen peroxide couldn’t improve the compromised bond to the bleached enamel. Enamel treated with CPP- ACP has been found to be more resistant to a subsequent acid challenge. It seems that the reduced bond strength to the CPP-ACP treated enamel may be due to the inability of Clearfil SE Bond as a mild self-etch adhesive to effectively etch and penetrate to the hyper-mineralized enamel surface. Moreover, the remaining CPP-ACP complexes may stay on the enamel surface and be consolidated into the bonding layer or restrain the bond between the Clearfil SE Bond and enamel. Chuang et al. [33] revealed that treatment with 0.37% fluoridated carbamide peroxide maintained the microtensile bond strength as effectively as the unbleached enamel. The result of our study revealed that the concomitant use of fluoride and hydrogen peroxide couldn’t improve the compromised bond to the bleached enamel. A study also revealed that fluoride treatment post-bleaching did not prevent the reduction in the enamel/resin shear bond strength in the time-period from immediately after treatment to 14 days after treatment [34]. The results of this study revealed that using modified bleaching agents acts as unmodified bleaching agents in decreasing the bond strength of the composite resin to the enamel if it was used immediately before composite restoration. However, if the enamel was bleached one week before restoration, the bond strength of
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In vitro comparison of shear bond strength of a flowable composite resin and a single-component glass-ionomer to three different pulp-capping agents

In vitro comparison of shear bond strength of a flowable composite resin and a single-component glass-ionomer to three different pulp-capping agents

were prepared. Mineral trioxide aggregate, CEM cement and Biodentine were placed in the cavities (n = 24 in each group) and incubated for 24 h. The blocks were subdivided into the composite resin and glass- ionomer subgroups. Cylindrical plastic molds, measuring 3 mm in height and diameter, were used to place the restorative materials on the samples. The shear bond strength test was performed at a strain rate of 1 mm/min in a universal testing machine. The samples were evaluated under a stereomicroscope at × 25 magnification for fracture modes. The data was analyzed with the one-way analysis of variance
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Effect of four different conditioners on the shear bond strength of composite to glass ionomer: An In vitro study

Effect of four different conditioners on the shear bond strength of composite to glass ionomer: An In vitro study

Sheth et al 1989 16 has conducted a two-part study to evaluate the tensile bond strengths of composite resin to several glass-ionomer cements that were (a) unetched but allowed to set in air and (b) etched for 30 s with orthophosphoric acid, and to compare them with the cohesive strength of the respective cement. Using a silver nitrate staining technique, they also evaluated the microleakage of class V cavities restored with composite resin under a base of etched or unetched glass ionbomer cement. Although there were significant differences among three cements between their cohesive strength and the resin bond strength after the two surface treatments, the bond to the unetched surface was generally comparable to that of the etched surface of the cement. The remaining groups showed no statistical difference. The microleakage was similar in the two groups. SEM micrographs showed a rough topography of the unetched cement that resembled that of the etched surface. This in vitro study suggests that acid-etching a glass-ionomer base for resin-bonding may not be necessary for specific materials.
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Comparison of Shear Bond Strength of Composite to Primary and Permanent Enamel Using Dentin bonding and Enamel Bonding Agents

Comparison of Shear Bond Strength of Composite to Primary and Permanent Enamel Using Dentin bonding and Enamel Bonding Agents

In this experimental study, 12 primary and 12 per- manent recently extracted teeth were selected. Ac- cording to the results of a study by Krifka and con- sidering G=0.05 and H=0.2, difference of 10 MPa and standard deviation of 8.2, number of speci- mens in each group was calculated to be 12. The selected teeth had intact buccal surfaces with no caries or anomaly. After prophylaxis and cleaning the crowns and the roots, the teeth were mounted in resin blocks measuring 2.5cm in length, 1.8cm in width and 1.2cm in depth. The buccal surfaces of the teeth were then polished with 400 grit abra- sive papers to achieve a smooth enamel surface 3mm in diameter. Then, 37% phosphoric acid (Ul- tra-Etch, Ultradent Product Inc., USA) was applied to the surfaces for 20s and rinsed for 15 seconds. Air spray was checked on a dental mirror to ensure that it is free from water and oil. Dental surfaces were dried for 5 seconds to obtain a chalky appear- ance on the etched surface.
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Shear Bond Strength of Molar Tubes to Enamel Using an Orthodontic Resin-Modified Glass Ionomer Cement Modified with Amorphous Calcium Phosphate

Shear Bond Strength of Molar Tubes to Enamel Using an Orthodontic Resin-Modified Glass Ionomer Cement Modified with Amorphous Calcium Phosphate

with Fuji Ortho LC glass ionomer modified with ACP had borderline SBS for use in the clinical setting. However, a comparison of their study and ours is difficult since we used buccal tubes and Fuji Ortho LC glass ionomer instead of orthodontic bands and a conventional glass ionomer. Dandachli [38] reported a 15.7% rate of clinical bond failure when using RMGI cement for bonding of ceramic brackets to the enamel, which was higher than the 7% failure rate in the group bonded with Transbond XT. This finding was also confirmed in our study. Similar to the samples in group 2 of our study, the most common location of debonding of the tubes in the cited study was at the enamel-adhesive interface, which is attributed to the weak bond strength of the glass ionomer cement to the enamel [38].
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Shear bond strength of Biodentine, ProRoot MTA, glass ionomer cement and composite resin on human dentine ex vivo

Shear bond strength of Biodentine, ProRoot MTA, glass ionomer cement and composite resin on human dentine ex vivo

[6]. This is in contrast to most other dental cements like GIC, which are highly acidic during the setting reaction [16]. The exact mechanism regarding the bonding of CSCs to dentine is still unclear. Discussed is a chemical bond as well as a micromechanical anchorage via ce- ment tags in the dentinal tubules [16-19]. E.g. after placement of MTA on dentine, hydroxyapatite crystals nucleate and grow, filling the microscopic space between MTA and the dentine surface. Initially this seal is mech- anical. Over time, the reaction between hydroxyapatite and dentine leads to a chemical bonding [19]. Hence, MTA appeared to bond chemically to dentine via diffusion-controlled reaction between its apatitic surface and dentine, forming an adherent interfacial layer that was firmly attached to the dentin wall [19]. It was shown that MTA trigger the precipitation of carbonated apatite, promoting a controlled mineral nucleation on dentine that was observed as the formation of an interfacial layer with tag-like structures [18]. This mechanism, theoretically, could initially lead also to the retention of the cement by the dentine through a micromechanical bonding system [20]. The alkaline Biodentine may induce a caustic denaturation and permeability of the organic col- lagen component of interfacial dentine [16]. Hence, for Biodentine a recent study showed the formation of intra- tubular tags in conjunction with an interfacial mineral interaction layer referred to as the “mineral infiltration zone” [16]. The interfacial layer formed between Bio- dentine and dentine may be comparable to that formed between dentine and MTA [21]. In contrast to Atmeh et al. [16] the migration of ions into dentine was not shown for Biodentine by Gjorgievska et al. [21] This leads to the conclusion that the adhesion of Biodentine is mainly micromechanical, and not ion-exchange based. Nevertheless, Biodentine showed excellent adaptability to- ward dentine [21].
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Comparison of shear bond strength of three adhesive liners to nanocomposite: an in vitro study

Comparison of shear bond strength of three adhesive liners to nanocomposite: an in vitro study

Nanoionomer: The chemistry of Ketac N100 restorative, a resin modified glass ionomer (RMGI), is based on the methacrylate modified polyalkenoic acid. The filler content of the system consists of an acid reactive fluoroaluminosilcate glass (FAS) and a unique combination of nanofillers.Flowable resin-based materials have been used as liners beneath composites due to their low viscosity, high elasticity and wettability. Xie H, Zhang F, Wu Y, Chen C, Liu W. Dentine bond strength and microleakage of flowable composite, compomer and glass ionomercement. Aust Dent J 2008;53:325-31. Currently nano-filled flowable composites that have better physical properties are available. Due to its low viscosity and since it is a bond between two resin layers,flowable composite is expected to bond well with the more viscous resin composite. Castaneda-Espinosa JC, Pereira RA, Cavalcanti AP, Mondelli RF. Transmission of composite polymerization contraction force through a flowable composite and a resin-modified glass ionomer cement. J Appl Oral Sci 2007;15:495-500. Esthet X flow:Liquid micro-hybrid composite material which can be used as a liner under direct and indirect restorative material. The resin matrix consists of urethane modified BisGMA adduct, BisGMA and diluents. The filler matrix consists of barium fluoroalumino- borosillicate glass with a mean particle size of approximately 1 µm and nanofiller silica. However, the higher shrinkage of flowable composites indicates a potential for higher interfacial stresses; (Suprabha BS, Simi B. A comparative study of shear bond strength of two adhesive liners to nanocomposite.Journal of Interdisciplinary Dentistry. 2012;2(3))
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An In Vitro Evaluation of the Antibacterial Efficacy and Mechanical Properties of Glass Ionomer Cement - Fuji IX Incorporated with Three Antibiotics

An In Vitro Evaluation of the Antibacterial Efficacy and Mechanical Properties of Glass Ionomer Cement - Fuji IX Incorporated with Three Antibiotics

control. Three antibiotic mixtures, ciprofloxacin, metronidazole and minocycline, were added to powdered GIC (Fuji IX) to obtain concentration ratios of 1.5, 3.0 and 4.5% w/w. The antibacterial activity of each GIC was evaluated against Streptococ cus mutans or Lactobacillus casei using agar-diffusion methods.All tested groups showed a significantly greater inhibition with growth of the selected bacteria in comparison to the control groups (p < 0.01). However, the 3% and 4.5% concentration ratios of antibiotics had significantly lower compressive strength and lower bond strength to dentin than the control group (p = 0.003). The GIC-containing antibiotics were effective in inhibiting S Mutans and L Casei. The addition of a 1.5% antibiotic mixture was optimal to giving appropriate physical and bonding properties.
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Shear Bond Strength of Self-Adhesive Flowable Composite, Conventional Flowable Composite and Resin-Modified Glass Ionomer Cement to Primary Dentin

Shear Bond Strength of Self-Adhesive Flowable Composite, Conventional Flowable Composite and Resin-Modified Glass Ionomer Cement to Primary Dentin

Thus, it may be concluded that high viscosity, less wettability and limited penetration of self- adhesive composites can result in lower bond strength compared to the use of conventional composites and total etch bonding systems [23]. Our findings also revealed lower SBS of RMGIC than that of conventional flowable composite, which was in line with the findings of a previous study [13]. Studies comparing the bond strength of RMGIC and self-adhesive composite are scarce. In our study, the SBS values of RMGIC and self-adhesive composite were comparable; this finding was in agreement with that of Pacifici et al, [13] and Scaminaci et al [14]. RMGIC and self-adhesive composite have easier application than the conventional composite. Application of self-adhesive composite is even easier and faster than RMGIC. Although self- adhesive composite does not release fluoride, it has high filler content and is believed to have a higher wear resistance than RMGIC. Moreover, Vertise Flow composite has a less porous surface than RMGIC, which can result in higher esthetics and less plaque accumulation. Decreased postoperative tooth hypersensitivity is another advantage of Vertise self-adhesive composite [7,13]. Scaminaci et al. [15] reported that the SBS of Vertise Flow was significantly higher than that of glass ionomer cement, which was in contrast to our finding. This difference in the results may be due to the use of conventional cement (Ketac Fil), which has a lower SBS than RMGIC used in our study because the HEMA molecule in the composition of RMGIC increases the bond strength. However, Scaminaci et al, [14] in another study compared the SBS of restorative materials to permanent dentin and found results in line with our findings. Although the SBS of Vertise Flow was slightly higher than that of GIC, this difference was not significant. Since the type of tooth (primary versus permanent) was different in the two studies by Scaminaci et al, [14,15] it may be stated that in addition to difference in sample size, difference in structure of permanent and primary dentin is another reason explaining the difference in the results of the two studies.
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Evaluation of Shear Bond Strength of Methacrylate- and Silorane-based Composite Resin Bonded to Resin-Modified Glass-ionomer Containing Micro- and Nano-hydroxyapatite

Evaluation of Shear Bond Strength of Methacrylate- and Silorane-based Composite Resin Bonded to Resin-Modified Glass-ionomer Containing Micro- and Nano-hydroxyapatite

A few studies investigated the bonding of si- lorane-based composite resin to RMGI. Boushell et al. reported no significant difference in the shear bond strength of silorane-based composite resin (Filtek LS) to RMGI versus Z250/Adper Scotch Bond SE. [33] It has been reported that the silorane composite resin had sig- nificantly lower bond strength to RMGI compared to methacrylate composite resin. [34] But in the current study, silorane composite resin exhibited higher bond strength to RMGI in comparison to Z350. The differ- ence observed in this study might be related to the use of self-etch adhesive system with methacrylate compo- site resin in the above-mentioned studies; whereas, in this study no etching system was used with Z350 spec- imens and Adper Single Bond was applied alone. Si- lorane adhesive system is considered a mild self-etching adhesive due to its high pH value (2.7). It can create mechanical interlocking between the bonding agent and the porosity caused through mildly etching of the RMGI surface. [35] Consequently, silorane adhesive system can increase the bond strength in comparison with the Adper Single Bond which includes no etching proce- dure. In this regard, Kasraie et al. showed that applica- tion of the self-etch system resulted in greater increase in micro shear bond strength between the RMGI and composite resin compared with the use of etch-and-rinse system. [26]
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Comparison of Two Methods of Chlorhexidine Application of Shear Bond Strength Degradation between Composite Resin and Dentin

Comparison of Two Methods of Chlorhexidine Application of Shear Bond Strength Degradation between Composite Resin and Dentin

Background: Chlorhexidine could have effect on shear bond strength of composite resin-dentin. Objective: The purpose of this study is to compare two methods of chlorhexidine application of shear bond strength degradation between composite resin and dentin. Methods: Thirty samples of dentin were taken from the crown of premolars and then divided into three groups (n = 10). Group 1 were applied bonding without chlorhexidine, group 2 were applied with liquid chlorhexidine and followed by bonding, group 3 were applied bonding which contains chlorhexidine. Each group was divided into two sub-groups (n = 5): the group with and without 10% NaOCl immersion for one hour. Then, 4 samples in each sub-group were used to measure shear bond strength using Univer- sal Testing Machine, and 1 sample was examined with Scanning Electron Microscope (SEM). Data were analyzed using SPSS 17 by Mann-Whitney and Kruskal Wallis test. Results: The highest mean shear bond strength without 10% NaOCl immersion was in group 1, while the highest mean with 10% NaOCl immersion was in group 3. Significant differences occurred between the groups 1 and 2, groups 2 and 3. Conclusion: Method of using bonding contains chlorhexidine can increase and inhibit degradation shear bond strength between composite resin and dentin.
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Effect of Bleaching on Shear Bond Strength of Composite Resins to Bovine Enamel Using Three Bonding Agents

Effect of Bleaching on Shear Bond Strength of Composite Resins to Bovine Enamel Using Three Bonding Agents

site to the tooth reduced 24 hours after bleaching, which is in agreement with results found in this study [13]. Perdigo et al. point out in their studies that loss of calcium, reduction in microhardness, and changes in organic component can be impor- tant factors in reducing the bond strength to enamel after bleaching [14]. Van der Vyver P.J, Titley K.C, Dishman M.V, and Ghavam in separate stu- dies have shown that the reduction in bond strength could be due to permeation of hydrogen peroxide into enamel and formation of free-radicals, which inhibit the initiation of polymerization and forma- tion of resin tags, which concurs with the results of this study [9, 15, 12, 16]. Zho et al. in 2000 showed that peroxide ions can replace free radicals in the apatite hydroxide network, and thus, produce apatite peroxide, causing destruction of the enamel prisms structure [17]. Several methods have been proposed for prevention from the clinical problems associated with reduced bond strength after bleach- ing: the most common is delaying application of bonding agent (any type) after bleaching [16]. Shimahara M.S et al. and Van Der Vyver et al. in 2004 reported that the best time for restoration of enamel and dentin is two weeks after bleaching, since the resin bond strength to enamel be im- proved [12-18]. Bulucu et al. also found that in the samples restored two weeks after bleaching, the difference in bond strength, compared to control group was insignificant. They also stated that the type of light cure system did not affect bond strength [19]. Other studies have shown that stor- ing the samples in distilled water or in artificial saliva after bleaching and before bonding can im- prove resin bond strength by removing layer of Bonding Bleach Number Mean Standard deviation Standard error
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Effect of Caries Removal Methods on the Shear Bond Strength of Resin and Glass Ionomer Adhesives to Primary Dentin

Effect of Caries Removal Methods on the Shear Bond Strength of Resin and Glass Ionomer Adhesives to Primary Dentin

The present findings indicated significantly higher bond strength for Carisolv than bur exca- vation for both bonding agents on the primary car- ies-affected dentin. This finding is in contrast with the results reported in other studies [1,9], in which using a bur showed a higher value of shear bond strength than Carisolv after using CSEB on the pri- mary caries-affected dentin. The differences could be due to incomplete removal of caries by Carisolv gel on those studies [1,9]; this might have interfered with bonding efficiency. Another possible reason could be the high pH level of Carisolv, which neu- tralizes acids in the adhesive and reduces the shear bond strength [1] by reducing demineralization of the tooth. Regarding the effectiveness of chemo-
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A Comparative Evaluation of the Effect of Resin based Sealers on Retention of Crown Cemented with Three Types of Cement – An In-vitro Study

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Theoretically, maximum retention is obtained if a tooth preparation has parallel walls. However, it is impossible to prepare a tooth this way by using current techniques and instrumentations. Slight undercuts are created, that prevent the restoration from seating. So, a slight convergence or taper is necessary in completed preparations [9]. The recommended convergence between op- p o sing walls is 6 degrees [10]. When convergence angle is increased, the effect of taper on crown retention is decreased and effect of luting agent on crown retention is magnified. In most clinical situations, studies have demonstrated that the degree of convergence which was found clinically was approximately 20 degrees [11]. For this reason, in present study, a convergence angle of 20 degrees was chosen. When a retentive failure occurred, cement often adhered to both the tooth preparation and the fitting surfaces of the restoration. In these cases, cohesive failures occurred through the cement layers, because the strength of the cement was less than the induced stress. A computerized analysis of these stresses revealed that they were not uniform throughout the cement, but were concentrated around the junction of the axial and occlusal surfaces [12]. Changes in the geometry of the preparation (e.g. rounding the internal line angle) may reduce stress concentrations and thus increase the retention of the restoration [13,14]. Impressions and dies of the tooth preparation were made. Die spacer was applied to provide space for the cement. The space was standardized to three coats, to provide space of 25 microns. Also, as was shown by Rosensteil and Gegauff [15] the castings made from dies which were painted with three coats of die spacer showed no effect on retention of the casting to the tooth. A dipping technique was used to make the wax patterns of thickness 1mm in lines, as per the method which was advocated by Johnson et al., [16]. When the internal surface of a restoration was very smooth, retention failure occurred, not through the cement, but at the cement restoration interface. Under these circumstances; retention will be increased if the restoration is roughned or grooved [13,14,17]. The cements which were used in the present study were Zinc phosphate cement (Harvard), Glass ionomer cement (GC, lining and luting cement), Modified glass ionomer (RelyXTm Luting 2,3M ESPE).
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Comparison of Bond Strength of Porcelain Laminate Veneers Bonded to Laser Treated Dentin and Acid Treated Dentin : An In Vitro Study

Comparison of Bond Strength of Porcelain Laminate Veneers Bonded to Laser Treated Dentin and Acid Treated Dentin : An In Vitro Study

sectioned into crowns and roots along the cem ento -enam el juncti on, and then the crowns were cut l ongi tudi nall y int o s heet s about 1.5 mm thick with a cutting machine. The denti n samples were fixed on a st age at focus pl ane. The l as er beam was irradi at ed onto the s amples through a galvanom etric s canning s ystem, so rect angula r m ovem ent could be achi eved. Aft er ablation, the sampl es were exami ned with a scanning el ect ron mi cros cope and l aser t hree -dim ensi onal profi le m easurem ent micros cope for morphology and roughnes s stud y. With increasing l as er fluence, denti n s amples exhibit ed more m elting and re -solidi fi cation of dentin as well as debris -li ke s truct ure and occluded parts of denti nal tubul es . When at t he s canni ng speed of 2400mm/ s and scanni ng distance of 24μm, the surface roughness of dentin ablated with fem tos econd puls ed l as er decreased si gnifi cantl y and varied bet ween val ues of denti n surface roughness grinded with two kinds of diam ond burs with di fferent grits. When at the scanning s peed of 1200mm/s and scanning distance of 12μm, the surface roughness decreased slightly, and the surface roughness of dentin abl at ed with fem tos econd puls ed las er was al most equal t o that grinded wi t h a low grit di amond bur.
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