The purpose of this study was to evaluate the color stability of light cured composite resins according to the resin matrices. Three kinds of resin matrices such as Bis-GMA (Venus® Diamond; VD), Silorane (FiltekTM P90; P90), and Ormocer (Admira; Ad) were selected. Each of them were used to prepare 30 specimens. The initial CIE L*a*b* values were measured by means of a Spectrophotometer (NF999, Nippon Denshoku, Japan). For accelerated aging process, the specimens were immersed in a circulating water bath with distilled water at 60℃. Spectrophotometric analyses were made after immersion of 8, 16, 24, 41 days and the color difference (ΔE*) was calculated. The L* value increased compared with initial L* value. VD had the greatest L* value change and Ad had the smallest L* value change (p<0.05). Ad had the greatest a* value change and VD had the smallest a* value change (p<0.05). The b* value of P90 increased steadily in positive value (+)(p<0.05). ΔE* of Ad had the smallest value and that of P90 had the greatest change with time. According to this study, the value of light cured composite resins was increased with water sorption and color of those changed into greenish and yellowish. And according to the evaluation of color stability, Ad with Ormocer as resin matrices had the best color stability with time in oral environment and P90 with Silorane as resin matrices had the lowest color stability with time. And VD had the greatest initial ΔE*.
Aging ; Baths ; Bisphenol A-Glycidyl Methacrylate ; Composite Resins ; Diamond ; Immersion ; Organically Modified Ceramics ; Silorane Resins ; Water

OBJECTIVETo evaluate the microtensile bond strength of one-step self-etching adhesives to dentin in vitro.

METHODSThree commercially available one-step self-etching bonding systems (group A: Adper Prompt, group B: Clearfil S(3) Bond, group C: Xeno III) were compared with two-step self-etching adhesive (group D: Clearfil SE Bond) in this study. The microtensile bond strength was determined with microtensile tester and the fractured bonding surfaces were observed under stereomicroscope and scanning electronic microscope (SEM). The mean bond strengths were analyzed using one-way ANOVA test (P < 0.05).

RESULTSMean microtensile bond strengths of group C, B, A and D were (34.59 +/- 3.46), (30.46 +/- 3.82), (23.36 +/- 2.55) and (45.06 +/- 5.29) MPa, respectively. Group D showed the highest bond strength (P < 0.01).

CONCLUSIONSTwo-step self-etching adhesive had a higher bond strength than one-step self-etching adhesive systems, although all of them can satisfy the clinical requirements.

Bisphenol A-Glycidyl Methacrylate ; Composite Resins ; Dentin-Bonding Agents ; Humans ; Organophosphates ; Resin Cements ; Tensile Strength

This study was undertaken to compare by Atomic Force Microscope the effects of various finishing and polishing instruments on surface roughness of filling and veneering composite resins. Seven composite resins were studied : Silux Plus (3M Dental Products, U.S.A.), charisma (Heraeus Kulzer, Germany), Prisma THP (L.D.Caulk, Dentsply, U.S.A.), Photoclearfil (Kuraray, Japan), Cesead (Kuraray, Japan), Thermoresin LC (GC, Japan), Artglass (Heraeus Kulzer, Germany), samples were placed and polymerized in holes (2mm thick and 8.5mm in diameter) machined in Teflon mold under glass plate, ensuring excess of material and moulded to shape with polyester matrix strip, Except control group (polyester mztrix strip), all experimental groups were finished and polishied under manufacturer's instructions. The finishing and polishing procedure were : carbide bur (E.T. carbide set 4159, Komet, Germany), diamond bur (composite resin polishing bur set, GC, Japan), aluminum-oxide disc (Sof-Lex Pop-On, 3M Dental Products, U.S.A.), diamond-particle disc (Dia-Finish, Renfert Germany), white stone bur & rubber point(composite finishing kit, EDENTA, Swiss), respectively. Each specimens were evaluated for the surface roughness with Atomic Force Microscope (AutoProbe CP, Park Scientific Instruments, U.S.A.) under contact mode and constant height mode. The results as follows : 1. Except Thermoresin LC, all experimental composite resin groups showed more rougher than control group after finishing and polishing(p<0.1). 2. A surface as smooth as control group was obtained by Al2O3 disc all filling composite resin groups except Charisma and all veneering composite resin groups except Thermoresin LC(p<0.05). 3. In case of Thermoresin LC, there were no statistically significant differences before and after finishing and polishing(p>0.1). 4. Carbide bur, diamond bur showed rough surfaces in all composite resin groups, so these were inappropriate for the final poslishing instruments.
Bisphenol A-Glycidyl Methacrylate ; Composite Resins* ; Dental Instruments ; Fungi ; Glass ; Polyesters ; Polymers ; Polytetrafluoroethylene ; Rubber

OBJECTIVES: This study evaluated the influence of chlorhexidine (CHX) on the microtensile bonds strength (microTBS) of resin core with two adhesive systems to dentin in endodontic cavities. MATERIALS AND METHODS: Flat dentinal surfaces in 40 molar endodontic cavities were treated with self-etch adhesive system, Contax (DMG) and total-etch adhesive system, Adper Single Bond 2 (3M ESPE) after the following surface treatments: (1) Priming only (Contax), (2) CHX for 15 sec + rinsing + priming (Contax), (3) Etching with priming (Adper Single Bond 2), (4) Etching + CHX for 15 sec + rinsing + priming (Adper Single Bond 2). Resin composite build-ups were made with LuxaCore (DMG) using a bulk method and polymerized for 40 sec. For each condition, half of specimens were submitted to microTBS after 24 hr storage and half of them were submitted to thermocycling of 10,000 cycles between 5degrees C and 55degrees C before testing. The data were analyzed using ANOVA and independent t-test at a significance level of 95%. RESULTS: CHX pre-treatment did not affect the bond strength of specimens tested at the immediate testing period, regardless of dentin surface treatments. However, after 10,000 thermocycling, all groups showed reduced bond strength. The amount of reduction was greater in groups without CHX treatments than groups with CHX treatment. These characteristics were the same in both self-etch adhesive system and total-etch adhesive system. CONCLUSIONS: 2% CHX application for 15 sec proved to alleviate the decrease of bond strength of dentin bonding systems. No significant difference was shown in microTBS between total-etching system and self-etching system.
Adhesives ; Bisphenol A-Glycidyl Methacrylate ; Chlorhexidine ; Composite Resins ; Dental Cements ; Dentin ; Molar ; Polymers

OBJECTIVE: The purpose of this study was to investigate the effect of tribochemical silica coating on the shear bond strength (SBS) of rebonded ceramic brackets using nano-filled flowable composite resin. METHODS: A total of 60 premolars were prepared and divided into 4 equal groups as follows: Tribochemical silica coating (TC) + Transbond XT (XT), TC + Transbond supreme LV (LV), Sandblast treatment (SA) + XT, SA + LV. Treated ceramic brackets were rebonded on the premolars using each adhesive. All samples were tested in shear mode on a universal testing machine. RESULTS: SBS of silica coated groups were high enough for clinical usage (TCLV: 10.82 +/- 1.82 MPa, TCXT: 11.50 +/- 1.72 MPa). But, SBS of the sandblast treated groups had significantly lower values than the tribochemical silica coated groups (SALV, 1.23 +/- 1.16 MPa; SAXT, 1.76 +/- 1.39 MPa; p< 0.05). There was no difference between the shear bond strength by type of adhesive. In the silica coated groups, 77% of the samples showed bonding failure in the adhesive. In the sandblast treated group, all bonding failures occurred at the bracket-adhesive interface. CONCLUSIONS: The result of this study suggest that newly introduced nano-filled flowable composite resin and tribochemical silica coating application on debonded ceramic bracket bases can produce appropriate bond strengths for orthodontic bonding.
Adhesives ; Bicuspid ; Bisphenol A-Glycidyl Methacrylate ; Ceramics ; Collodion ; Composite Resins ; Resin Cements ; Silicon Dioxide

PURPOSE: The purpose of this study was to investigate the diametral tensile strength of polymer-based temporary crown and fixed partial denture (FPD) materials, and the change of the diametral tensile strength with time. MATERIAL AND METHODS: One monomethacrylate-based temporary crown and FPD material (Trim) and three dimethacrylate-based ones (Protemp 3 Garant, Temphase, Luxtemp) were investigated. 20 specimens (the empty set 4 mm x 6 mm) were fabricated and randomly divided into two groups (Group I: Immediately, Group II: 1 hour) according to the measurement time after completion of mixing. Universal Testing Machine was used to load the specimens at a cross-head speed of 0.5 mm/min. The data were analyzed using one-way ANOVA, the multiple comparison Scheffe test and independent sample t test (alpha = 0.05). RESULTS: Trim showed severe permanent deformation without an obvious fracture during loading at both times. There were statistically significant differences among the dimethacrylate-based materials. The dimethacrylate-based materials presented an increase in strength from 5 minutes to 1 hour and were as follows: Protemp 3 Garant (23.16 - 37.6 MPa), Temphase (22.27 - 28.08 MPa), Luxatemp (14.46 - 20.59 MPa). Protemp 3 Garant showed the highest value. CONCLUSION: The dimethacrylate-based temporary materials tested were stronger in diametral tensile strength than the monomethacrylate-based one. The diametral tensile strength of the materials investigated increased with time.
Acrylic Resins ; Bisphenol A-Glycidyl Methacrylate ; Collodion ; Composite Resins ; Crowns ; Denture, Partial, Fixed ; Methacrylates ; Polymethacrylic Acids ; Tensile Strength

OBJECTIVE: The purpose of this study was to investigate the viscoelastic properties related to handling characteristics of composite resins. METHODS: A custom designed vertical oscillation rheometer (VOR) was used for rheological measurements of composites. The VOR consists of three parts: (1) a measuring unit, (2) a deformation induction unit and (3) a force detecting unit. Two medium viscous composites, Z100 and Z250 and two packable composites, P60 and SureFil were tested. The viscoelastic material function, including complex modulus E* and phase angle delta, were measured. A dynamic oscillatory test was used to evaluate the storage modulus (E'), loss modulus (E") and loss tangent (tandelta) of the composites as a function of frequency (omega) from 0.1 to 20 Hz at 23degrees C. RESULTS: The E' and E" increased with increasing frequency and showed differences in magnitude between brands. The E*s of composites at omega = 2 Hz, normalized to that of Z100, were 2.16 (Z250), 4.80 (P60) and 25.21 (SureFil). The magnitudes and patterns of the change of tandelta of composites with increasing frequency were significantly different between brands. The relationships between the complex modulus E*, the phase angle delta and the frequency omega were represented by frequency domain phasor form, E* (omega) = E*e(idelta) = E* 45 degree angle delta. CONCLUSIONS: The viscoelasticity of composites that influences handling characteristics is significant different between brands. The VOR is a relatively simple device for dynamic, mechanical analysis of high viscous dental composites. The locus of frequency domain phasor plots in a complex plane is a valuable method of representing the viscoelastic properties of composites.
Composite Resins

OBJECTIVEThis study investigated the shear bond strength and the ability of resin adhesive containing different amounts of bioactive glass (BG) to prevent dentin demineralization.

METHODSBG bonds at 30%, 40%, and 50% concentrations comprised a mixture of coupling agents modifying BG and Single Bond 2. Forty permanent premolars extracted for orthodontic treatment were randomly divided into four groups, namely, control group (BG-free), 30% BG group, 40% BG group, and 50% BG group. Composite resin and dentin were prepared into bonding specimens by using respective adhesives and then immersed in artificial saliva at pH 4 for 1 week. Changes in the pH values of the solution were measured every 24 h. The microtensile bond strength (TBS) of each specimen was examined after immersion in distilled water at 37 °C for 24 h.

RESULTSThe TBS values of the control group, 30% BG group, 40% BG group, and 50% BG group were (27.76±0.29), (27.05±0.58), (26.95±0.69), and (25.12±0.24) MPa, respectively. The TBS of the control group was not significantly different from that of the 30% BG group (P=0.06) but significantly higher than that of the 40% BG and 50% BG groups (P=0.04 and P=0.00, respectively). In addition, TBS was significantly higher in the 30% BG and 40% BG groups than in the 50% BG group (P=
0.00 and P=0.00, respectively). The pH values of the solution increased with increasing BG content.

CONCLUSIONSBG bonds are useful in the prevention of dentin demineralization. However, in this study, the 30% BG group did not affect the short-term bond strength. The 50% BG group displayed the optimum ability to inhibit demineralization but showed the worst bond strength.

Adhesives ; Bisphenol A-Glycidyl Methacrylate ; Composite Resins ; Dental Bonding ; Dentin ; Glass ; Humans ; Materials Testing ; Saliva, Artificial ; Tensile Strength ; Tooth Demineralization

OBJECTIVETo study the types of matrix metalloproteinases (MMPs) involved in dentin bonding interface degradation.

METHODSDentin slices were prepared and treated with two adhesive systems (Single Bond 2 or Clearfil S3 Bond). The dentin surface was bonded with composite resin. All specimens were immersed in sterile artificial saliva for 0 or 6 months, and their micro-shear bond strength (muSBS) were measured. The fracture modes were observed through field emission scanning electron microscope (FE-SEM). Dentin slices with 4 mm x 3 mm x 1 mm dimensions were prepared. The slices were divided into three groups according to the treatment modes (negative control, Single Bond 2, and Clearfil S3 Bond). All specimens were stored in sterile artificial saliva for 0 or 6 months. The concentrations of MMP-1, -2, -3, -8, and -9 of each group were detected through fluorescent microsphere immunoassay.

RESULTSThe muSBS of both adhesive systems significantly decreased after storage aging. Significant differences in failure modes within the four groups tested in this study were observed. Compared with the negative control, the concentrations of MMP-1 and MMP-3 in different adhesive groups showed no significant difference after storage aging. However, the concentrations of MMP-2, -8, and -9 in Single Bond 2 group and the concentrations of MMP-8 and -9 in Clearfil S3 Bond group significantly decreased after 6 months of storage aging.

CONCLUSIONSignificant degradation occur in the dentin bonding interface of both adhesive groups under 6 months aging challenge. The concentrations ofdentinal MMP-2, -8, and -9 significantly decrease after treatment with adhesives and aging, indicating that these MMPs have an important function in dentin bonding interface degradation.

Bisphenol A-Glycidyl Methacrylate ; Composite Resins ; Dental Bonding ; Dentin ; Dentin-Bonding Agents ; Materials Testing ; Matrix Metalloproteinases ; Resin Cements ; Surface Properties

The use of flowable composite resins as liners in class II packable composite restoration has been suggested by some manufacturers. However, the contributions of this technique are unproven. The purpose of this study was to compare the gingival microleakage in class II packable composite restorations with or without the use of flowable composite resins as liners. Slot cavities were prepared on both proximals of 80 extracted human molars and randomly assigned to 8 groups of 20 each. The gingival margins were located at 1mm above CEJ in 80 cavities (group1-4) and 1mm below CEJ in 80 cavities (group5-8). The prepared teeth were mounted in the customized tray with adjacent teeth to simulate clinical conditions and metallic matrix band (Sectional matrix) and wooden wedges were applied. After acid etching and application of Single Bond, each group was restored with the following materials using incremental placement technique: Group 1,5 (Filtek P60), group 2, 3, 4 and group 6, 7, 8 (AeliteFlo, TetricFlow, Revolution/Filtek P60). All specimens were thermocycled 500 times between 5degrees C and 55degrees C with 1 mimute dwell time, immersed 2% methylene blue dye for 24 hours and then rinsed with tab water. The specimens were embedded in clear resin and sectioned longitudinally through the center of restoration with a low speed diamond saw. Dye penetration at gingival margin was viewed at 20 magnification and analyzed on a scale of 0 to 4. Kruscal-Wallis One way analysis and Mann-Whitney Rank sum test were used to analyze the results. The results of this study were as follows. 1. The leakage values seen at the enamel margin were significantly lower than those seen at the dentin margin(P<0.05). 2. On the enamel margin, packable composite resins with flowable liners showed lower leakage than those without flowable liners, but there were no significant differences among the four groups(P>0.05). 3. On the dentin margin, four groups demonstrated moderate to severe leakage, and there were no significant differences in leakage values(P>0.05).
Bisphenol A-Glycidyl Methacrylate ; Composite Resins ; Dental Enamel ; Dentin ; Diamond ; Humans ; Matrix Bands ; Methylene Blue ; Molar ; Tooth ; Tooth Cervix ; Water