Glass-ionomer cement is known for its biomimetic properties, because of its similarity to the mechanical properties of dentine. This, along with the benefits of adhesion and release of fluoride, render it an ideal material in many restorative situations. But due to its reduced mechanical properties it should only be used as a final restorative material in low stress areas, and it must be protected by resin composite or amalgam in areas of high stress. Resin modified GIC has proved to be a material with improved properties and aesthetics as compared to the conventional glassionomer. As there is always possibility of fracture at the resin – GIC interface, surface conditioners have been used to enhance the adhesion of the same. This is an in vitro experimental study to investigate the effect of fourdifferentconditioners on the shearbondstrength of composite to resin modified glassionomer.
Abstract- Objective: to evaluation the effect of different surface treatment on shearbondstrength between composite increments to determine the most effective procedure that increase bondstrength between composite increments Methods: four groups used in this study and each group consist of 20 blocks of composite, The block made at the same dimension: (3mm, 3mm, 2 mm) made from 3M Nano Hybrid Z 250XT.1 st group: include Oxygen polymerization inhibited samples. 2 nd group: include sample that inhibit the formation of Oxygen polymerization inhibited layer by utilize strip.3 rd group: include the samples that uses3M one bottle self etch bond that contain silane . 4 th group: include surface grinding of first composite increment by turbine diamond bur, each of these four groups composite from 20 block of composite . Using VALO Cordless curing light for composite increment curing. Results: the mean of bondstrength for first group is 32.14 ± 1.148 Mpa , second group 30.75 ± 1.854 Mpa, third group 13.73 ± 1.301 Mpa and last group 19.67 ± 1.919 Mpa. The one way ANOVA (F-test) utilized to identify the significant differences between the four groups , L.S.D was apply to compare the differences of two groups as multiple comparison. The higher shearbondstrength in group cotain oxygen inhibiter layer and group use one bottle bond (saline) group,and lowest mean result of group that Inhibit oxygen inhibiter layer formation and surface grinding groups. Conclusions: the shearbondstrength between composite increment increase when there is oxygen inhibiter layer on the composite surface and also increase when used one bottle bond agent contain silane while the absence of oxygen inhibiter layer lower the bondstrength between the increment when add another composite layer. also the rough surface gave better bondstrength result compared to smooth surface.
Wettability is one of the most important physico- chemical surface properties and NaOCl is a non-specific proteolytic material which can remove organic materials and magnesium and carbonate ions.  Previous stud- ies have shown that after NaOCl treatment of dentin, an increase in wettability is expected because collagen removal produces a hydrophilic surface. The complete removal of organic components of the demineralized collagen matrix by NaOCl also increases the porosity of the intact dentin. The present study showed that the use of 5% NaOCl significantly decreased shearbondstrength of single bond and silorane adhesive to dentin (p< 0.05). This is in accordance with the findings of the previous studies. [23-24, 28]
Studies on the shearbondstrength of tooth-colored restorative materials following the use of antibiotics are scarce. Some studies, similar to ours, have shown positive effects of antibiotics on bondstrength. However, this may vary depending on the type of antibiotic, and further investigations are required on this topic. Mortazavi et al. Reported that combination of tetracycline, 1.3% sodium hypochlorite and detergent according to a protocol did not significantly decrease the compositebond to dentin, which was in contrast to the effect of 35% phosphoric acid with the self-etch technique . Elkassas et al. compared different disinfectants and reported no significant effect of antibiotics on tensile bondstrength. They used 5.25% sodium hypochlorite, 2% chlorhexidine, 0.1% benzalkonium chloride and 3% doxycycline. Their results showed that sodium
Materials and Methods: Two caries removal methods including mechanical (handpiece) and chemomechanical (Carisolv) techniques and two types of ad- hesives including one resin adhesive (Clearfil SE Bond; CSEB, Kuraray) and one resin-modified glassionomer adhesive (Riva Bond LC; RBLC, SDI) were used in this study. Ten extracted healthy primary teeth were used for the control group. The teeth were sectioned bucco-lingually and mesio-distally in order to obtain four specimens from each tooth. Thirty suitable specimens were selected as the “control” and randomly divided into two groups of “sound dentin” based on the type of the adhesive used. Sixty extracted caries affected teeth were used for the carious group; sectioned as mentioned above and sixty suitable specimens were selected as the “treatment”. Then the specimens were arbitrarily divided into four groups based on caries removal techniques and the type of ad- hesive used (n = 15). After bonding with either CSEB or RBLC, the specimens were restored with a resin composite by means of PVC tubes and subjected to the shearbondstrength test. The data was analyzed using ANOVA and Tukey’s test.
Studies have examined the physical alteration after bleaching to find a possible explanation for decrease in enamel bondstrength caused by bleaching agents. Titley KC et al also suggested that the reduction in bondstrength might be related to the presence of residual hydrogen peroxide at or near the enamel surface which interfered with resin attachment and inhibited resin polymerization. (28) There are more studies that have described this effect. (29,85) The loss of calcium and alterations in the organic substance might be important factors to cause a decrease in enamel bond strengths. (37) Rotstein I et al suggested that bleaching agents changed the original ratio between the organic and inorganic components of the tissues and increased their solubility. (41) Also, Bistey T et al reported that at-home and in-office peroxide- containing bleaching agents are capable of causing structural alteration in enamel at low and high concentrations as well. (62) These studies probably explains the reduction in shearbondstrength after office bleaching.
Materials and Methods: Forty flat enamel surfaces were prepared from freshly extracted human premolars using a low speed diamond saw. Then the specimens were divided into four random groups (n = 10). All the groups were treated with 30% H2O2. The specimens in Group I were bonded immediately after bleaching, whereas Group II, III and IV were treated with antioxidants Sodium ascorbate, Pomegranate peel extract and Grape seed extract respectively. After preparation, a standard shaped resin composite was applied to all specimens. The teeth were stored in deionized water for 24hrs at 37°C and a universal testing machine determined their shearbondstrength. The data were evaluated using ANOVA and Tukey Post Hoc tests.
structure simultaneously and need to Ketac primer (Ket- ac primer; 3M ESPE, USA) to improve the wettability of dentin and monomer penetration into dentin sub- strate. It could be speculated that nano ionomer perhaps behaves more like a resin composite rather than a true glassionomer [3, 33-34]. Additionally, Ketac N100 (Ketac N100/Ketac Nano; 3M ESPE, USA) is based on a prior RMGI from the same manufacturer (Vitremer), which was lower than Fuji II LC in terms of shearbondstrength [3, 5, 34]. In other ways, lower bondstrength of non-primed nano ionomer to dentin, may be related to the very superficially interaction of nano ionomer with dentin without evidence of demineralization and/or hy- bridization [3, 33]. In our study, we utilized poly acrylic acid as cavity conditioner that led to partially demineral- ization of smear layer and enhanced HEMA penetration to dentin [3, 35]. Generally, the various bondstrength values found in different studies can be possibly at- tributed to several factors such as the type of material, application method, tooth preparation methods, storage conditions, and aging protocols [21, 24, 26].
For group Enlight, mean bondstrength was found to be 10.2MPa, highest among all other groups at time interval 24 hours after tray removal (see Table 1.c) followed by Transbond XT with mean SBS of 6.95MPa and Orthofix with a mean SBS of 5.2MPa. Orthosource was found to have mean SBS of 3.50MPa, and Discover was found to have least mean SBS of 2.67MPa among all other adhesives. Sujoy Banerjee et al 69 , also found Enlight having higher bondstrength than Transbond XT .But, Ashita Talwar et al 67 , found Transbond XT having the highest shearbondstrength followed by Orthofix, and Enlight having the least shearbondstrength. These variations may be due to the type of curing unit used, the site where debonding forces are applied or presence of any air inclusions between the base composite and the sealant during placement of transfer tray over the natural teeth.
In this in-vitrostudy, 60 maxillary anterior teeth extracted 3 months before the study were selected. The teeth had no cracks, carious lesions or coronal restorations. After removing the tissue remnants, the teeth were rinsed under running water and im- mersed in 0.5% chloramine T solution. Then the teeth were immersed in distilled water (Shahid Ghazi Co., Tabriz, Iran) at room temperature for 24 hours before the experiment. The roots were cut at 2 mm apical to the CEJ using M016-878 di- amond bur (SS White Inc, Lack Wood, USA) and high-speed handpiece with air and water spray. The pulp of the coronal segment was removed. The samples were placed in molds measuring 35×25×10 mm, containing translucent acrylic resin (Marlic Med Co., Tehran, Iran), with the labial surfaces facing outward. The samples were placed in cold water in order to control the heat generated during the polymerization of the acrylic resin. The enamel labial surfaces with 4×4 mm dimensions were polished with wet 400- and 600-grit silicone papers to achieve a flat homogeneous labial sur- face in all specimens.
Since their introduction in 1972 , GICs have been widely used as dental restorative materials, luting cements and base materials [12,28]. One of their main advantages is the chemical bonding to tooth substrate by relative ease of use . This is comparable to CSCs but there is a differ- ence in the adhesive mechanism between acidic GIC and alkaline CSCs. The exact mechanism of GIC bonding to dentine is still unknown . Several bonding mechanisms are discussed in literature: GIC bonds chemically directly to dentine by ionic bonding with hydroxyapatite to tooth substrate  even in presence of a smear layer . Micromechanical bonding is also possible  and bond- ing to collagen has as well been suggested in a recent study . The application of acidic GIC on dentine resulted in a demineralising effect on inorganic dentine components . Polyalkenoic acids from the GIC is absorbed irrevers- ibly onto hydroxyapatite from the dentine surface [32,33]. GIC forms an interaction zone by movement of ions from the cement into the surface layer of the tooth [21,34,35]. Hence, an ion exchange layer appears interfacial between dentine and GIC . Whereas some authors reported about the formation of a hybrid layer and GIC tags in den- tinal tubules after dentine conditioning and smear layer re- moval . That could not be confirmed in other studies . Hence, there was little evidence of tag-like structures when GIC is applied on dentine when the smear layer was not removed .
After the 6-month storage period, the shearbondstrength values showed a statistically significant difference (p < 0.01) between the two groups, with higher values for the CHX group. Hence, CHX has a beneficial effect in maintaining the resin–dentin bondstrength over a period of 6-month. Intragroup analysis showed the bondstrength values to diminish considerably in both the experimental and the control groups and the differences were statistically significant. Since CHX primarily prevents the collagenolytic degeneration, whatever drop in values present must be due to the hydrolytic changes in the interface, in part contributed by the water from the CHX solution itself. Since a 2% aqueous solution of CHX is used in this study, water could not be eliminated completely from the interface. The persistence of lytic changes at the resin–dentin interface could thus be attributed to the compromised moisture control rather than any ineffectiveness of CHX.
a conventional composite resin control(Transbond XT), The teeth were extracted after 4 weeks, sectioned, and evaluated quantitatively by cross-sectional micro hardness testing. Fluoride levels in patients saliva were measured by the Taves diffusion method in samples taken at days 0 (baseline), 1,2,3,7,14,21 and 28 to determine whether fluoride from the glassionomer cement influenced the overall intraoral fluoride levels. The results demonstrated significantly more demineralization around the brackets of the control patients. For whole-mouth salivary fluoride levels, no significant overall difference between the group and no noticeable trend within group were found. They concluded that using fluoride- releasing glassionomer cement for bonding orthodontic brackets successfully inhibited caries in vivo. This cariostatic effect was localized to the area around the brackets and was statistically significant after 4 weeks.
Owing to adhesive restorative materials, currently tooth preparation is more conservatively done in the new dental restorative procedures. The RMGICs are a new generation of adhesive restorative materials with several positive points like fluoride releasing potential and improved marginal seal. The two constituent parts of GIs are composite resin and glassionomer. They are reported to form an amorphous zone like the hybrid layer formed by composite resins. The RMGICs also create a chemical bond to the tooth structure through the ionic interactions similar to GI. 
Nagai T, Kawamoto Y (2004) 33 studied the Effect of hydrofluoric acid etching on bondstrength of composite luting agent to lithium disilicate ceramic material. In their study, two sizes of disk specimens were made from a lithium disilicate-based ceramics (IPS Empress 2) and their surfaces were separately prepared with three methods: etching with phosphoric acid (PE), etching with hydrofluoric acid (HF), and air-borne particle abrasion with alumina (AA). Each group was further divided into two sub-groups: bonding with the Panavia F material (PF), and silane treatment followed by bonding with the Panavia F material. Shear testing was performed both before and after 20,000 thermocycles. They concluded that, hydrofluoric acid etching effectively enhanced bondstrength of the Panavia luting agent to the ceramic material, regardless of the application of silane primer.
Materials and Methods: In this experimental in-vitrostudy, the test groups were composed of 80 dentinal samples, prepared on occlusal surfaces of 80 maxillary premolar teeth and routinely divided into 8 groups of 10. Two cylindrical molds (2.5×2mm (in groups 1, 4, 5, and 6) and 2.5×5 mm(in groups 2, 3, 7, and 8)) were filled in bulk using P60 (groups 1, 3, 4, and 8) and Ceram X (groups 2, 5, 6, and 7) composites and light cured with LED ( in groups (4, 6, 7, and 8) and QTH (in groups 1, 2, 3, and 5) light curing units .After curing and 3 months aging in 37°c water, shearbondstrength of all samples were evaluated using a universal testing machine with 1mm/min crosshead speed. One- and three-way ANOVA were used for statistical analysis using SPSS software.
Since, there is a limited information available on the use of the newer natural antioxidant agents like Oligomeric Proanthocyanidin Complexes (OPCs) that they increases the bondstrength of composite resin to bleached enamel. OPCs present in natural antioxidants like grape seed extract and pine bark extract have free radical scavenging activity 4 ,36 . Hence, the aim of this in-vitrostudy was to evaluate and compare the effect of 10% Sodium Ascorbate , 10 % pine bark extract, and Aloe vera leaf solution on the SBS of composite resin to bleached enamel.
[13-17], one study showed that sodium ascorbate had the potential of forming a three-dimensional, porous physical scaffold that would entrap the pathogenic microorganisms like Streptococcus mutans and this adverse property affected its efficacy for enhancing the bondstrength and highlighted the need for other antioxidants . Grape seed as an herbal antioxidant contains pro- antioxidant compounds and is capable of eliminating free radicals . Studies have shown that polyphenols present in green tea are rapidly metabolized and show antioxidant activity [19,20]. Catechins present in green tea such as epigallocatechin gallate (EGCG) are antioxidant compounds that can eliminate free radicals as well . Sage extract also has antioxidant capacity . Previous studies have shown that these herbal antioxidants can reverse the decreased bondstrength of composite to bleached enamel [17,22,23]. However, some studies have reported different efficacy values for herbal products in various application times [24-28]. Also, a large number of studies have compared only one or two herbal antioxidants with sodium ascorbate [23,26,27]. In order to better assess the efficacy of herbal and chemical antioxidants, this in-vitrostudy was carried out to assess the effect of sodium ascorbate, grape seed, sage and green tea extracts on the bondstrength of composite to bleached enamel.
This in-vitrostudy was conducted on 18 premolar and 18 incisor teeth extracted for orthodontic, periodontal or prosthetic treatments. The teeth had to be free from caries, restorations, enamel defects (hypoplasia or use of forceps) and fractures since the aim of this study was to assess the composite resin bond to sound enamel. After washing and removal of tissue appendages, the teeth were immersed in 0.5% chloramine T solution and then stored in saline until the experiment (maximum of 6 months). For preparation of specimens, the premolar and incisor teeth were each randomly divided into three groups of 6 and then the 3 incisor and the 3 premolar groups were randomly combined in such way that eventually 3 groups of 12 teeth including 6 premolars and 6 incisors were created. Next, enamel of the buccal surface of the teeth was ground using a disc in such way that a plastic cylinder containing composite measuring 3mm in diameter and 3mm in height could be placed on the enamel surface. Next, the specimens were mounted in Acropars auto polymerizing acrylic resin (Marlic, Tehran, Iran) in molds (specific for Instron machine) up to the level of the cementoenamel junction in such way that the composite-buccal surface interface was parallel to the lateral surfaces of the mold in order for the blade to apply load perpendicular and directly to the resin-tooth interface.
Several studies investigated the effect of adding different amounts and sizes of apatite powder to GIC for improving the physical property of this cement. [19-22] These studies demonstrated that GICs containing hy- droxyapatite exhibit better mechanical properties and higher bondstrength to dentin than the conventional GICs. A study reported that hydroxyapatite-reinforced glass-ionomer, 75wt% of glass-ionomer and 25wt% of hydroxyapatite, exhibited the highest bondstrength to dentin.  It has been demonstrated that adding nano- hydroxyapatite (nano-HA) to glass-ionomer shows higher bondstrength to tooth structure compared to mi- cro-hydroxyapatite (micro-HA). The decreased size of nano-HA particles, similar to that of the minerals in tooth, leads to increased surface area and higher solubil- ity, filling the enamel defects with higher performance ;this phenomenon occurs through releasing calcium and phosphate ions and by increasing the bondstrength be- tween the tooth and the restorative material.