Influence of Lithium- and Zinc-Containing Bioactive Glasses on Pulpal Regeneration.

OBJECTIVE: To evaluate the potential of modified bioactive glasses containing lithium and zinc as pulp capping materials by investigating the odontogenic differentiation and mineralization response in the tooth culture model. MATERIALS AND METHODS: Lithium- and zinc-containing bioactive glasses (45S5.1Li, 45S5.5Li, 45S5.1Zn, 45S5.5Zn, 45S5.1Zn sol-gel, and 45S5.5Zn sol-gel), fibrinogen-thrombin, and biodentine were prepared to assess Axin2 gene expression at 0, 30 minutes, 1 hour, 12 hours, and 1 day and DSPP gene expression at 0, 3, 7, and 14 days in stem cells from human exfoliated deciduous teeth (SHEDs) using qRT-PCR. The experimental bioactive glasses incorporated with fibrinogen-thrombin and biodentine were placed on the pulpal tissue in the tooth culture model. Histology and immunohistochemistry were analyzed at 2 weeks and 4 weeks. RESULTS: Axin2 gene expression for all experimental groups was significantly higher than the control at 12 hours. The DSPP gene expression for all experimental groups was significantly higher than the control at 14 days. The presence of mineralization foci was significantly higher at 4 weeks for the modified bioactive glasses 45S5.5Zn, 45S5.1Zn sol-gel, and 45S5.5Zn sol-gel as well as Biodentine compared with the fibrinogen-thrombin control. CONCLUSION: Lithium- and zinc-containing bioactive glasses increased Axin2 and DSPP gene expression in SHEDs and can potentially enhance pulp mineralization and regeneration. Zinc-containing bioactive glasses are a promising candidate to be used as pulp capping materials.

Delayed light activation of resin composite affects the bond strength of adhesives under dynamic simulated pulpal pressure.

OBJECTIVE: To evaluate the effect of a time delay before the light activation of resin composite on the microtensile bond strength (µTBS) of self-etch adhesives under dynamic simulated pulpal pressure. MATERIALS AND METHODS: One hundred twenty crown segments were prepared from human third molars. Dentin surfaces were prepared with coarse diamond burs and connected to a dynamic pulpal pressure device. The self-etch adhesives used were Clearfil SE Bond (CSE), G2-Bond Universal (G2B), Clearfil Universal Bond Quick (CBQ), and G-Premio Bond (GPB). Each adhesive was divided into 3 subgroups: immediate light activation of resin composite (T0), delayed light activation for 150 s (T1), and 300 s (T2). The µTBS data were obtained after 24-h water storage. Scanning electron microscopy was used to evaluate the nanoleakage at the resin-dentin surface. The µTBS data were analyzed using two-way ANOVA and Duncan's multiple comparisons. RESULTS: All adhesives demonstrated a significant reduction in µTBS at T2, except for CBQ where the bond strength was not affected by the delayed light activation times. The two-step self-etch adhesives (CSE and G2B) demonstrated higher bond strength than the one-step adhesives at all conditions. Nanoleakage was observed in all adhesives at T2; however, nanoleakage was detected only in CBQ and GPB at T1. CONCLUSIONS: Delayed light activation of resin composite adversely affected the dentin bond strength of self-etch adhesives. Two-step self-etch adhesives had better bonding performance than one-step self-etch adhesives. CLINICAL RELEVANCE: After adhesive application, resin composite should be adapted and cured as soon as possible.

Effects of dentin surface preparations on bonding of self-etching adhesives under simulated pulpal pressure.

Objectives: This study evaluated the effects of different smear layer preparations on the dentin permeability and microtensile bond strength (µTBS) of 2 self-etching adhesives (Clearfil SE Bond [CSE] and Clearfil Tri-S Bond Universal [CTS]) under dynamic pulpal pressure. Materials and Methods: Human third molars were cut into crown segments. The dentin surfaces were prepared using 4 armamentaria: 600-grit SiC paper, coarse diamond burs, superfine diamond burs, and carbide burs. The pulp chamber of each crown segment was connected to a dynamic intra-pulpal pressure simulation apparatus, and the permeability test was done under a pressure of 15 cmH2O. The relative permeability (%P) was evaluated on the smear layer-covered and bonded dentin surfaces. The teeth were bonded to either of the adhesives under pulpal pressure simulation, and cut into sticks after 24 hours water storage for the µTBS test. The resin-dentin interface and nanoleakage observations were performed using a scanning electron microscope. Statistical comparisons were done using analysis of variance and post hoc tests. Results: Only the method of surface preparation had a significant effect on permeability (p < 0.05). The smear layers created by the carbide and superfine diamond burs yielded the lowest permeability. CSE demonstrated a higher µTBS, with these values in the superfine diamond and carbide bur groups being the highest. Microscopic evaluation of the resin-dentin interface revealed nanoleakage in the coarse diamond bur and SiC paper groups for both adhesives. Conclusions: Superfine diamond and carbide burs can be recommended for dentin preparation with the use of 2-step CSE.

Effect of brushing on surface roughness, fluoride release, and biofilm formation with different tooth-colored materials.

BACKGROUND/PURPOSE: Tooth brushing, material mechanical ageing procedure, is the most effective way in removing biofilm. The purpose of this study was to investigate the surface roughness, fluoride-release, and S. mutans biofilm formation on various tooth-colored restorative materials before and after brushing. MATERIALS AND METHODS: Discs of materials, a nanocomposite (Filtek Z350XT; CO), a giomer (Beautifil II; GIOMER), a resin-modified glass-ionomer material (Fuji II LC; RMGI), and a conventional glass-ionomer material (Fuji IX GP Extra; GI), were prepared, polished with abrasive discs (SofLex), and divided into brushed and not brushed groups. The surface roughness of specimens was observed using a contact profilometer, fluoride-release was measured using a fluoride-specific ion electrode, and S. mutans biofilm formation, biovolume and live/dead cells, was observed under a confocal laser scanning microscope. RESULTS: Higher roughness was observed on GI and RMGI than on CO and GIOMER. Brushing had no effect on the roughness. The fluoride-release of GI and RMGI was higher than that of GIOMER. The fluoride-release decreased after brushing in all materials. The biovolume of S. mutans was not significantly different between GIOMER, RMGI and GI, while CO showed the highest. Brushing resulted in a higher biovolume for all materials, except CO, which showed no change. After brushing, all the tested materials demonstrated identical biovolumes. There were no significant differences in live/dead cells among all groups. CONCLUSION: Brushing demonstrated a negative effect on the fluoride-release and biovolume of S. mutans biofilms for all tested materials except nanocomposites.

Effect of Stress Generated by Occlusal Cyclic Force on Class I Bulk-Fill Composite Restoration Microleakage.

OBJECTIVE: This study aimed to evaluate the effects of different types and restorative techniques of Class I composite restorations with a single loading force on stress distribution and cyclic loading force on microleakage formation. MATERIALS AND METHODS: Class I cavities were prepared in premolars with 4 mm depth and divided into six groups of different restorations with: (1) Filtek Z250; (2) a 3-mm-thick layer of Filtek Bulk Fill Flowable Restoration and covered with Z250; (3) a 1.5-mm-thick layer of flowable composite and covered with Z250; (4) lining all cavity with flowable composite and restored with Z250; (5) Filtek Bulk Fill Posterior Restoration; and (6) lining all cavity with flowable composite and restored with bulk-fill composite. The specimens with and without cyclic occlusal loading were subjected to microleakage observation. In addition, six different models of Class I restorations corresponding to the microleakage study were generated. Finite element analysis (FEA) was used to identify the stress distribution under a single loading force. STATISTICAL ANALYSIS: Data were statistically analyzed by two-way analysis of variance and multiple comparison. The significance level set at 0.05. RESULTS: Cavity lining or restoration with flowable composite underneath conventional composite reduced stress on composite resin based on FEA (groups 2 and 3). The cyclic stress on composite increased microleakage. Restoration with flowable composite underneath conventional composite reduced the microleakage in Class I restoration (groups 2, 3, and 4). CONCLUSION: The most effective cavity lining with a flowable composite underneath conventional composite restoration was stress reduction under loading force resulting in microleakage reduction.

The Influence of Blade Type and Feeding Force during Resin Bonded Dentin Specimen Preparation on the Microtensile Bond Strength Test.

This paper presents the effect of blade type and feeding force during resin-bonded dentin specimen preparation on the microtensile bond strength (µTBS) test. Forty resin-bonded flat middle dentin specimens were divided into four groups. The specimens of each group were sectioned according to type of blade and feeding force as follows: fine grit/20 N, fine grit/40 N, medium grit/20 N, and medium grit/40 N to obtain resin-dentin sticks with a cross-sectional area of 1.0 mm2. Four sticks from the center of each tooth were subjected to the µTBS test. Five remaining sticks of each group were selected for surface topography observation under a scanning electron microscope (SEM). As a result, the bond strength of the medium-grit group was higher than that of the fine-grit group (p < 0.001), whereas the feeding force had no influence on bond strength values (p = 0.648). From the SEM, sticks prepared with the fine-grit blade showed a smoother surface integrity and fewer defects on the specimen edges in comparison with the sticks prepared with the medium-grit blade. The grit type of the blade is one of the considerable factors that may affect the bond strength and the surface integrity of resin-dentin specimens for microtensile testing.

Bond strength of self-etching adhesives to dentin surface after smear layer removal with ultrasonic brushing.

This study determined the micro-shear bond strength (µSBS) of two self-etching adhesives to dentin surface after smear layer removal with a novel ultrasonic brushing method. Ninety-five dentin discs were ground flat with diamond burs and divided into 5 groups; no treatment (control), brushing with a custom-made brush for 10 and 30 s without and with ultrasonic application. The smear layer thickness was evaluated using SEM. The 24 h µSBS of Clearfil SE Bond (CSE) and Clearfil Tri S Bond (CTS) to these dentin surfaces were evaluated. Smear layer thickness decreased significantly from control, brushing without, and brushing with ultrasonic groups, respectively. The µSBS of CSE were higher than CTS in all groups. The µSBS were improved with ultrasonic brushing for 30 s for both adhesives. Ultrasonic brushing is the effective method in mechanical smear layer removal which can improve bond strength of self-etching adhesives to ground dentin.

Effect of smear layer and surface roughness on resin-dentin bond strength of self-etching adhesives.

The purpose of this study was to evaluate the effect of surface roughness and smear layer on the micro-shear bond strength (µSBS) of two self-etching adhesives, Clearfil SE Bond (SE) and Clearfil Tri-S Bond (S3). Flat dentin surfaces were prepared with SiC papers (600-, 180- and 120-grit) and diamond burs (extra fine, medium and coarse). They were further divided into smear-covered and smear-free surfaces and bonded with respective adhesives. µSBS test was performed after water storage at 37ºC for 24 h. Smear layer thickness measurement was evaluated by scanning electron microscope (SEM). Surface roughness was examined by contact stylus profilometer. Smear layer thickness and surface roughness were significantly different among all groups (p<0.05). No difference in µSBS was observed among surface prepared by SiC whereas bur-cut smear layer had negative effect on µSBS, especially for S3. Surface roughness from different surface preparations had no influence on µSBS (p<0.05).

Effect of thermocycling on the durability of etch-and-rinse and self-etch adhesives on dentin.

The objective was to compare bond strengths of adhesives with/without thermocycling and to analyze the micromorphology of resindentin interfaces. Flat dentin surfaces were prepared and divided into eight groups to bond with four etch-and-rinse adhesives (Optibond FL, Adper Scotchbond Multi-Purpose, Optibond Solo Plus, and Single Bond 2) and four self-etch adhesives (Clearfil SE Bond, Adper SE Plus, Clearfil S(3) Bond and Adper Easy Bond). Specimens were further divided into two subgroups subjected for with/without thermocycling and then subjected to both micro-tensile test and resin-dentin interface evaluation. The results revealed that there were significant differences in bond strength between the groups with and without thermocycling for all etch-and-rinse groups and for the Adper Easy Bond self-etch group (p<0.01). Clearfil SE Bond demonstrated highly durable bond strengths. Furthermore, more silver ion uptake was observed at the resin-dentin interfaces for all etch-and-rinse adhesives and Adper SE Plus and Adper Easy Bond after thermocycling.

Stress relieving behaviour of flowable composite liners: A finite element analysis.

The purpose of this study was to investigate the consequences of using flowable composite as a liner beneath class I resin composite restorations on polymerization shrinkage stress and occlusal force. Models of class I resin composite restorations were generated. A control model received no flowable composite liner. Thirteen test models received different flowable composite liners with varying elastic modulus. Finite element analysis was used. The polymerization shrinkage of the resin composite and an occlusal force were simulated in the models. The stress and strain energy density in each model were investigated. The results demonstrated that all flowable composite linings were able to reduce polymerization shrinkage stress and occlusal force in enamel, dentin, the hybrid layer, and the adhesive layer to various degrees in tooth-restoration systems. Therefore, additional techniques may be applied to reduce the remaining stress and to ensure the long-term success of restorations.

Effect of dentinal tubule orientation on the modulus of elasticity of resin-infiltrated demineralized dentin.

The effect of tubule orientation of dentin on the elastic modulus of resin-infiltrated dentin was evaluated. Rectangular cylindricalshaped dentin specimens with their long axis parallel to and perpendicular to dentinal tubules were prepared from extracted premolars. Twenty-five mineralized specimens of each orientation were evaluated. The remaining specimens were then demineralized. The demineralized specimens and the demineralized following by infiltration with one of these adhesives; Optibond Solo Plus, Single Bond 2 or Prime & Bond NT, from each orientation were evaluated (25 specimens per group). The tubular orientation only affected the elastic modulus of mineralized dentin. The highest elastic modulus was observed for the mineralized dentin when the tensile force was applied parallel to the direction of tubules. The elastic modulus of demineralized dentin was the lowest. The adhesive resins increased the elastic modulus of demineralized dentin, but the differences among the three were insignificant.

Shear and micro-shear bond strengths of four self-etching adhesives measured immediately and 24 hours after application.

This study measured the immediate and 24 h shear (SBS) and micro-shear bond strengths (MSBS) to dentin of four self-etching adhesives. A resin composite was bonded using each adhesive to the area of 5-mm diameter for SBS test or 0.75-mm diameter for MSBS test of flat bovine dentin. The bond strengths of all adhesives at 10 min were lower than at 24 h for both tests. The mean SBS (MPa, 10 min, 24 h) were similar in ranking order at both time periods that is: Clearfil SE Bond (21.2, 25.3) >Clearfil TriS Bond (12.7, 19.5)=i Bond (11.7, 19.5)=G Bond (11.1, 16.6). For the MSBS test, G Bond provided equivalent mean bond strength (35.0) to Clearfil SE Bond (36.9) and higher than the other adhesives at 24 h [i Bond (26.3), Clearfil TriS Bond (28.5)]. In conclusion, the MSBS test was slightly more discriminating than the SBS test.

Generation of gaseous sulfur-containing compounds in tumour tissue and suppression of gas diffusion as an antitumour treatment.

BACKGROUND AND AIMS: The mechanisms of cancer cell growth and metastasis are still not entirely understood, especially from the viewpoint of chemical reactions in tumours. Glycolytic metabolism is markedly accelerated in cancer cells, causing the accumulation of glucose (a reducing sugar) and methionine (an amino acid), which can non-enzymatically react and form carcinogenic substances. There is speculation that this reaction produces gaseous sulfur-containing compounds in tumour tissue. The aims of this study were to clarify the products in tumour and to investigate their effect on tumour proliferation. METHODS: Products formed in the reaction between glucose and methionine or its metabolites were analysed in vitro using gas chromatography. Flatus samples from patients with colon cancer and exhaled air samples from patients with lung cancer were analysed using near-edge x-ray fine adsorption structure spectroscopy and compared with those from healthy individuals. The tumour proliferation rates of mice into which HT29 human colon cancer cells had been implanted were compared with those of mice in which the cancer cells were surrounded by sodium hyaluronate gel to prevent diffusion of gaseous material into the healthy cells. RESULTS: Gaseous sulfur-containing compounds such as methanethiol and hydrogen sulfide were produced when glucose was allowed to react with methionine or its metabolites homocysteine or cysteine. Near-edge x-ray fine adsorption structure spectroscopy showed that the concentrations of sulfur-containing compounds in the samples of flatus from patients with colon cancer and in the samples of exhaled air from patients with lung cancer were significantly higher than in those from healthy individuals. Animal experiments showed that preventing the diffusion of sulfur-containing compounds had a pronounced antitumour effect. CONCLUSIONS: Gaseous sulfur-containing compounds are the main products in tumours and preventing the diffusion of these compounds reduces the tumour proliferation rate, which suggests the possibility of a new approach to cancer treatment.

Biodegradation of all-in-one self-etch adhesive systems at the resin-dentin interface.

This study evaluated the effects of two exogenous enzymes on the resin-dentin interface. Collagenase (Col) and acetylcholinesterase (Ach) were used to simulate salivary enzymes and accelerate the aging process of the bonding interfaces. Four adhesives, Adper Single Bond 2 (SB), Clearfil SE Bond (SE), Clearfil tri-S Bond (S3) and G-Bond (G), were bonded to the dentin surfaces. After storage in water with collagenase or acetylcholinesterase, the specimens were examined using a microtensile bond strength test (MTBS). Nanoleakage patterns were observed with a scanning electron microscope (SEM). The MTBS results demonstrated significantly lower bond strengths in the groups stored with either enzyme than in water. SB exhibited severe degradation after exposure to collagenase, while G showed severe degradation after exposure to acetylcholinesterase. All of the self-etch systems (SE, S3 and G) exhibited water-tree patterns within the adhesive layer when immersed in water for three months. The etch-and-rinse system (SB) showed nanoleakage within the hybrid layer and the adhesive.

Non-destructive assessment of cavity wall adaptation of class V composite restoration using swept-source optical coherence tomography.

The purpose of this study was to evaluate gap formations under class V restoration using swept-source optical coherence tomography (SS-OCT). Wedge-shaped cavities were prepared on the buccal surface of 40 extracted premolar teeth at 2 locations; 1) cemento-enamel junction (CEJ) with enamel and cementum margin and 2) root surfaces with cementum margin. The cavity was treated with Clearfil S(3) Bond, restored with Clearfil Majesty and polished with abrasive disks. The specimens were kept in water at 37°C for 24 hours and subjected to a thermocycling procedure. Gap formations at the tooth-restoration interface were measured with SS-OCT image and conventional dye leakage under a microscope. There was no effect of the locations of the cavity and the margins of the cavity on the gap formation. Therefore, a significant effect of the observational methods was observed. The gap formation was 0.89±0.48 mm with the SS-OCT, and the gap formation was 0.34±0.41 mm with the dye leakage. The observation with SS-OCT demonstrated a greater degree of gap formation than the observation with dye leakage.

Effects of C-factor and resin volume on the bonding to root canal with and without fibre post insertion.

OBJECTIVES: The aim of this study was to evaluate the effects of C-factor and resin volume on the regional bond strength of dual-cure luting resin to root canal dentine. METHODS: Twelve single-root human premolars were decoronated and post space prepared to a depth of 8 mm, with a diameter of 1.5 mm for six roots and 1.75 mm for the other six. Root canal dentine was treated with a dual-cure bonding system and light-cured for 20 s. Specimens were filled with a dual-cure resin composite with or without insertion of 1.4-mm-diameter light-transmitting glass fibre posts, followed by light-curing for 60s from the coronal direction. After 24 h water storage, each specimen was serially sliced into eight 0.6 mm × 0.6 mm thick beams for a microtensile bond strength test. Failure modes were observed using SEM. Bond strength data were divided into coronal and apical regions and statistically analysed. RESULTS: For both sizes of post space, bond strengths dramatically decreased when fibre posts were inserted. There were no significant differences in microtensile bond strength between 1.5 mm and 1.75 mm canal width, regardless of fibre post insertion. Regional differences in bond strength were found only in the resin-filled canals. CONCLUSIONS: The increase of C-factor of the root canal system by insertion of a fibre post had a detrimental effect on the bond strength to root canal dentine. On the other hand, the change of resin volume had no significant effect on bonding.

Effect of dentine smear layer on the performance of self-etching adhesive systems: A micro-tensile bond strength study.

This study aimed to evaluate the effect of the smear layer on the micro-tensile bond strength when two self-etching adhesives were used with different techniques. Flat dentine surfaces were prepared using either medium grit diamond burs or tungsten carbide burs. Ten specimens from each prepared surfaces were subjected for smear layer evaluation under SEM. Forty specimens from each of the prepared surfaces were further divided into two groups, bonded with either Clearfil SE Bond (SE) or Clearfil S(3) Bond (S3) using one of four applications (as manufacturer's instructions, agitation, reapplication, and increased application time), restored with composites and subjected to a micro-tensile bond strength test. Smear layers created with diamond burs were thicker than those created with tungsten carbide burs. Surfaces prepared with tungsten carbide burs produced a higher bond strength than those prepared with diamond burs and the same type of adhesive resin. SE demonstrated a higher bond strength than S3 for all surfaces. S3 applied with the agitation technique demonstrated a higher bond strength to dentine prepared with tungsten carbide and diamond burs than that applied with other techniques. SE applied with increased time on dentine treated with carbide burs produced the highest bond strength. In conclusion, a thick smear layer decreased bond strength to dentine, and this might be improved by modification of application technique.

The effect of the elastic modulus of low-viscosity resins on the microleakage of Class V resin composite restorations under occlusal loading.

This study aimed to evaluate the effectiveness of various intermediate layers on the microleakage of Class V restorations under an occlusal load. Wedge-shaped cavities were prepared on the buccal surface of 72 extracted premolars, which were then treated with an adhesive system (One Up Bond F Plus), divided into three groups, and restored with: 1) Estelite Sigma resin composite, 2) a resin composite with Low Flow flowable composite, or 3) a resin composite with High Flow flowable composite. The specimens were subjected to a nano-indentation test to evaluate the elastic modulus of successive layers at the resin-dentine interface and were subjected to a microleakage test under either unloaded or loaded conditions. The elastic moduli were significantly different among substrates (p<0.05), except between the hybrid layer/Low Flow and the hybrid layer/High Flow. The elastic moduli of the Low Flow composite were higher than those of the High Flow composite. Occlusal force increased dentine leakage in the group that was restored without flowable composites.

The influence of a local anesthetic containing vasoconstrictor on microtensile bond strengths of two adhesive systems to human dentin in situ.

PURPOSE: To evaluate the bond strengths of an etch-and-rinse adhesive and a self-etching adhesive to human dentin in vitro and under two in situ conditions: non-anesthetization and anesthetization of the teeth with a local anesthetic containing vasoconstrictor. MATERIALS AND METHODS: An in situ study was performed on 49 maxillary premolars scheduled for extraction due to orthodontic reasons. For the bond strength test, occlusal cavities were prepared either with or without a local anesthetic containing vasoconstrictor. The cavities were bonded with Adper Single Bond or Clearfil SE Bond and filled with a resin composite, Filtek Z250. The teeth were then extracted, sectioned, trimmed, and tested for microtensile bond strength. For the observation of dentin surfaces, 20 premolars were used. The impressions of the cavity floors in the anesthetized and non-anesthetized groups were taken before and after acid etching. The replicas were observed under a scanning electron microscope. In vitro, the bond strength test and the SEM observation were also carried out on 24 extracted premolars with the same procedures used in the in situ study. RESULTS: The bond strengths of the two adhesives bonded to dentin in situ were significantly lower than those in vitro. When both adhesives were tested under in situ conditions, there were no significant differences between the bond strengths to dentin of anesthetized and non-anesthetized groups (p > 0.05). No fluid droplets were found on dentin on the cavity floor prepared in vitro, either before or after acid-etching. For the unetched dentin prepared in situ, fluid droplets were found and covered on the smear layer in anesthetized and non-anesthetized groups, but the droplets were slightly larger in the non-anesthetized group. In the non-anesthetized, acid-etched group, dentin surfaces were covered with coalescent dentinal fluid in most specimens. However, in the anesthetized, acid-etched group, patent tubules and some dentinal fluid were observed on the surfaces. CONCLUSION: It was concluded that in situ, dentinal fluid had a detrimental effect on the dentin bond strengths of an etch-and-rinse adhesive and a self-etching adhesive. However, reduction in dentinal fluid due to the effect of a local anesthetic containing vasoconstrictor did not improve the bond strengths in either adhesives.

The elastic moduli across various types of resin/dentin interfaces.

OBJECTIVE: The purpose of this study was to evaluate the elastic moduli of an unfilled adhesive resin (Adper Single Bond) and a filled adhesive resin (Adper Single Bond 2) used with and without a low-viscosity resin (LVR) (Filtek Flow) as an elastic cavity wall in class V composite restorations, restored with a hybrid resin composite (Z250). METHODS: Buccal class V cavities were prepared on extracted premolars and lined with (1) the unfilled adhesive resin, (2) the filled adhesive resin, (3) the unfilled adhesive resin and the flowable composite, and (4) the filled adhesive resin and the flowable composite. All cavities were restored with the hybrid resin composite. The specimens were cut bucco-lingually, embedded in epoxy resin and polished. The polished specimens were evaluated for the elastic modulus with nano-indentation test at the layer of dentin, hybrid layer, adhesive resin, low-viscosity resin and resin composite. RESULTS: The elastic moduli were 25,111 MPa for dentin, 12,243 MPa for hybrid layer of Adper Single Bond, 11,765 MPa for hybrid layer of Adper Single Bond 2, 7595 MPa for Adper Single Bond, 8430 MPa for Adper Single Bond 2, 13,543 MPa for Filtek Flow and 24,494 MPa for Filtek Z250 resin composite. The statistical analysis demonstrated that the elastic moduli were significantly different among layers (p<0.05) except between hybrid layers of unfilled and filled adhesives (p=1.0). CONCLUSION: The application of filled adhesive did not increase the elastic modulus of hybrid layer when compared with the unfilled adhesive resin. The modulus of filled adhesive resin was significantly higher than that of unfilled adhesive resin.