Operative dentistry最新文献

The study aimed to evaluate the effect of thickness on the translucency parameter (TP) and whiteness index for dentistry (WID) of single-shade resin composites compared with a multi-shade resin composite after thermocycling. A total of 100 resin composite samples of five brands (Filtek Z250, Omnichroma, Vittra APS Unique, Zenchroma, and Charisma Diamond One) with thicknesses of 2 mm and 4 mm were prepared (n=10). CIE L*a*b* coordinates were obtained using a spectrophotometer. The resin composite samples were subjected to 10,000 thermocycles. Before and after thermocycling, TP values were calculated with the CIEDE2000 formula, and whiteness values were calculated using the WID. The influence of thickness, resin composite, and aging on these variables was analyzed using the generalized linear model (p<0.05). Omnichroma and Filtek Z250 exhibited, respectively, the highest and the lowest TP00 values compared with the other resin materials (p<0.001). The TP00 values of Zenchroma and Diamond One were similar (p>0.05). Vittra APS Unique had a lower TP than Zenchroma and Diamond One (p<0.001). Before thermocycling, the highest WID showed the combination of Vittra APS Unique with thicknesses of 2 mm (48.33±1.18). After thermocycling, the highest WID was shown in the combination of Vittra APS Unique with thicknesses of 2 mm (45.33±0.55) and 4 mm (46.23±0.94) (p<0.001). After thermocycling, the lowest WID was for the combination of Filtek Z250 with thicknesses 2 mm (21.16±0.93) and 4 mm (20.70±0.91) (p<0.001). The TP and WID values of the resin composites varied across different composites and thicknesses. Single-shade resin composites of different thicknesses demonstrated higher translucency and whiteness values than multi-shade resin composite, both before and after thermocycling.

Objectives: This study aimed to investigate bond performance of various resin luting cement (RLC) systems on enamel and dentin in different etching modes and to compare the RLC-tooth interface morphology using scanning electron microscopy (SEM).

Methods and materials: The self-adhesive RLC systems used in combination with universal adhesives were as follows: Scotchbond Universal Adhesive Plus + RelyX Universal (3M Oral Care) and Clearfil Universal Bond Quick ER + SA Luting Multi (Kuraray Noritake Dental). These RLC systems were also used alone as self-adhesive RLC systems without universal adhesives (self-adhesive mode). The conventional RLC systems for comparison materials were as follows: BeautiBond Xtream + ResiCem EX (Shofu) and Tooth Primer + Panavia V5 (Kuraray Noritake Dental). Twelve specimens were prepared for each group to measure shear bond strength (SBS) in different etching modes. A stainless-steel rod was used as a substitute for indirect restorations. Bonded specimens were allocated to baseline (stored for 24 hours) and artificially aged (thermocycling [TC] for 10,000 cycles) groups. Representative treated tooth surfaces and RLC-tooth interfaces were observed using SEM.

Results: Three-way analysis of variance (ANOVA) revealed that all the factors (etching mode, storage period, and RLC system) had a significant influence on the enamel SBS values (p<0.05). Enamel SBS was significantly higher in etch-&-rinse (ER) mode than in self-etch (SE) mode, regardless of RLC system or storage period. Three-way ANOVA showed that all the factors had a significant influence on the dentin SBS values (p<0.001). Most RLC systems showed significantly higher dentin SBS in SE mode than in ER mode, regardless of storage period. However, the combination with Scotchbond Universal Adhesive Plus and RelyX Universal showed no significant difference in SBS values between etching modes at the baseline and showed a significantly higher SBS value in ER mode than in SE mode after TC.

Conclusions: The self-adhesive RLC systems with universal adhesives tended to show higher enamel and dentin bond performance than the self-adhesive RLC systems alone. The morphology of treated tooth surfaces and resin cement-tooth interfaces were dependent on the RLC system and etching mode used. The RLC systems with primer application showed a thin, high-density layer above the intact dentin in both etching modes, suggesting chemical interaction.

The aim of this study was to evaluate the push-out bond strength and the failure mode of single adjustable posts (SPLENDOR SAP), anatomical posts (AP), or computer-aided design/computer-aided manufacturing (CAD-CAM) posts cemented to flared root canal dentin with self-adhesive dual-cure resin cement. Thirty single-rooted premolars received endodontic treatment with gutta-percha and a calcium hydroxide-based endodontic cement. After 24 hours, the canal spaces were enlarged with burs. The tooth specimens were divided equally into three groups (n=10), according to the glass fiber post (GFP) system: AP-prefabricated GFP (Reforpost #2, Angelus) was relined with composite resin (Filtek Z350 XT, 3M ESPE); SPLENDOR SAP-GFP was used with a glass fiber sleeve to adjust the adaptation (Splendor SAP, Angelus); and CAD-CAM-a resin pattern was obtained and scanned to produce a CAD-CAM GFP (Fiber CAD Lab, Angelus) milled using a subtractive technique. The three GFP systems were cemented with self-adhesive resin cement (Rely X U200, 3M ESPE). The roots were fixed to an acrylic resin plate used to section them into specimens of cervical, middle, and apical thirds. Then, the slices were attached to a universal testing machine to perform the push- out test at a speed of 0.5 mm/min and a load of 50 Kgf. The posttest specimens were examined under a stereoscopic microscope to evaluate the failure mode. The bond strength variable was analyzed using a generalized linear model, following a split-plot design. Failure mode analysis was performed using Fisher exact test. The significance level adopted was 5%. There was no significant difference among the GFP systems or among the thirds, in terms of bond strength (p>0.05), nor was there any significant association between the systems and the failure mode (p>0.05). Most specimens presented mixed or adhesive failure between resin cement and dentin. It was concluded that the bond strength to flared root dentin was not influenced by the GFP system or the root third.

Purpose: This study aimed to evaluate the effects of two desensitizers and the Er,Cr:YSGG laser on human dentin tubules, applied alone or in combination.

Methods: Ninety-six dentin specimens were obtained from extracted third molars and divided into six groups: Group 1: no-treatment (Control); Group 2: nano-hydroxyapatite desensitizer (NhapD); Group 3: NhapD+Er,Cr:YSGG laser (L); Group 4: Er,Cr:YSGG laser (L); Group 5: glutaraldehyde desensitizer (GD); and Group 6: GD+L, respectively. All specimens were evaluated using scanning electron microscopy. The diameter and the number of open dentin tubules, the tubules' occluding ratio, and the mineral coverage area were measured via the Image J software at 2000× magnification. Atomic force microscopy was used to determine the blocking mechanism of desensitizing treatments and the surface morphology of dentin specimens. One-way ANOVA and Tukey tests were used for statistical analysis.

Results: The number of open tubules and the mean diameter of tubules for all treatment groups showed statistically significant differences from the control group The NhapD+L group had a significantly lower number of open tubules than the L and GD groups. The NhapD+L and L groups significantly had higher occluding ratios than the other groups.

Conclusions: The present study showed that the Er,Cr:YSGG laser alone was effective in terms of tubule occlusion and also contributed to increasing the occluding ratio of nano-hydroxyapatite. It may be recommended to use the Er,Cr:YSGG laser with nano-hydroxyapatite desensitizers to achieve effective tubule occlusion.

This study evaluated the fracture resistance of teeth with mesio-occluso-distal (MOD) resin composite restorations using universal adhesive (Single Bond Universal; SBU) in three different manipulation modes compared with those using two-step self-etch (Clearfil SE bond; CSE) and 3-step etch-and-rinse (Scotchbond Multi-Purpose; SBMP) adhesives at 24 hours and after thermocycling. One hundred and sixty maxillary premolars were assigned into eight groups of 20 each. Intact teeth and nonrestored cavity-prepared teeth served as controls. For the remaining specimens, cavities were restored with resin composite using different adhesives-SBU in self-etch, etch-and-rinse, or selective enamel etching modes; CSE in self-etch or selective enamel etching; and SBMP. Specimens from each group were either stored in 37°C water for 24 hours or further submitted to thermocycling for 30,000 cycles (n=10), then subjected to axial compression stress until fracture. Fracture patterns were observed microscopically. Data were statistically analyzed at a 95% confidence level. Among the restored teeth, mean failure load of the group using SBMP was the highest at both short-term and long-term evaluation periods (p<0.05). Fracture strengths of the SBU groups where enamel was etched with phosphoric acid prior to the adhesive application were similar and were greater than in those specimens without pre-etching (p<0.05). After thermal aging, a significant decrease in fracture resistance value was detected only for the group using SBU in etch-and-rinse application mode (p<0.05). For the self-etch strategy, SBU demonstrated lower load to fracture than CSE following thermocycling; all specimens failed at and beneath the crestal level (p<0.05). Application of SBU universal adhesive in selective enamel etching mode provided higher and more stable fracture resistance of teeth with MOD resin composite restorations than in self-etch mode.

This study examined the influence of cariogenic environments on the surface roughness of ion-releasing restorative materials (IRMs). Custom-made stainless steel molds with holes of 5 mm × 2mm were used to fabricate 60 disc-shaped specimens of each of the following materials: Activa Bioactive (AV), Beautifil Bulk Restorative (BB), Cention N (Bulk-fill) (CN), and Filtek Z350XT (FZ) (Control). Baseline surface roughness (Ra) measurements were obtained using an optical 3D measurement machine (Alicona Imaging GmbH, Graz, Austria). The specimens were then randomly divided into five subgroups (n=12) and exposed to 10 ml of the following mediums at 37°C: distilled water (DW), demineralization solution (DM), remineralization solution (RM), pH cycling (PC) and air (AR) (control). Ra measurements were again recorded after one week and one month, followed by statistical evaluations with two-way analysis of variance (ANOVA) to determine interactions between materials and mediums. One-way ANOVA and post hoc Games Howell tests were performed for intergroup comparisons at a significance level of 0.05. Mean Ra values ranged from 0.085 ± 0.004 (µm) to 0.198 ± 0.001 µm for the various material-medium combinations. All IRMs showed significant differences in Ra values after exposure to the aqueous mediums. The smoothest surfaces were observed in the AR for all materials. When comparing materials, AV presented the roughest surfaces for all mediums. All IRM materials showed increased surface roughness over time in all cariogenic environments but were below the threshold value for bacterial adhesion, except for AV 1-month post immersion with pH cycling. Therefore, besides AV, the surface roughness of IRMs did not deteriorate to an extent that it is clinically relevant.

Objectives: This study was designed to: 1) evaluate and compare the evidence-practice gap (EPG) in minimal intervention dentistry (MID) in Japan and Brazil by measuring concordance between dentists' clinical practice and published evidence; and 2) identify dentists' factors associated with the EPG in both countries.

Methods: We performed a cross-sectional study using a web-delivered questionnaire among 136 Japanese and 110 Brazilian dentists. The questionnaire consisted of three questions concerning "restoration diagnosis and treatment," "deep caries diagnosis and treatment," and "caries risk assessment" regarding MID. A chi-square test was used to analyze differences in concordance among clinical practice and evidence from the literature between Japanese and Brazilian dentists. Logistic regression analyses were performed to analyze dentists' factors associated with overall concordance for all three questions.

Results: Overall concordance was significantly higher in Brazil (55%) than in Japan (38%) (p<0.01). Concerning how evidence was obtained, textbooks, nonacademic journals, and seminars and workshops were used as information sources more frequently by Japanese than Brazilian dentists (p<0.001), whereas scientific journal articles in English were used more frequently by Brazilian dentists (p<0.001). On logistic regression analysis, overall concordance was higher for Japanese dentists who frequently obtained evidence from scientific journal articles in English (p<0.05), whereas Brazilian dentists who frequently obtained evidence from the Internet were associated with lower overall concordance (p<0.05).

Conclusions: Because overall concordance was significantly higher in Brazil than in Japan, Japan may have a greater EPG in MID practice. Specific characteristics of Japanese and Brazilian dentists showed significant associations with overall concordance.

Objectives: To evaluate the effect of the different radiant exposures from a multipeak light curing unit on the physical and mechanical properties of flowable and high-viscosity bulk-fill resin-based composites (RBC).

Methods: Five flowable bulk-fill RBCs (Tetric N-Flow Bulk-fill, Ivoclar Vivadent; Filtek Bulk Fill Flow, 3M Oral Care; Opus Bulk Fill Flow APS, FGM; Admira Fusion x-base, Voco and; and SDR Plus Bulk Fill Flowable, Dentsply Sirona) and five high-viscosity bulk-fill RBCs (Tetric N-Ceram Bulk-fill, Ivoclar Vivadent; Filtek One Bulk Fill, 3M Oral Care; Opus Bulk Fill APS, FGM; Admira Fusion x-tra, Voco; and SonicFill 2, Kerr) were photo-cured using a VALO Cordless light (Ultradent) for 10, 20, and 40 seconds at an irradiance of 1200, 800, or 400 mW/cm2, resulting in the delivery of 4, 8, 12, 16, 24, 32, or 48 J/cm2. Post-gel shrinkage (Shr) was calculated using strain-gauge test. The degree of conversion (DC, %) was calculated using FTIR. Knoop hardness (KH, N/mm2) and elastic modulus (E, MPa) were measured at the top and bottom surfaces. Logarithmic regressions between the radiant exposures and mechanical properties were calculated. Radiodensity was calculated using digital radiographs. Data of Shr and radiodensity were analyzed using two-way analysis of variance (ANOVA), and the DC, KH, and E data were analyzed with two-way ANOVA using split-plot repeated measurement tests followed by the Tukey test (a = 0.05).

Results: Delivering higher radiant exposures produced higher Shr values (p<0.001) and higher DC values (R2=0.808-0.922; R2=0.648-0.914, p<0.001), KH (R2=0.707-0.952; R2=0.738-0.919; p<0.001), and E (R2=0.501-0.925; R2=0.823-0.919; p<0.001) values for the flowable and high-viscosity RBCs respectively. Lower KH, E and Shr were observed for the flowable bulk-fill RBCs. All bulk-fill RBCs had a radiopacity level greater than the 4-mm thick aluminum step wedge. The radiant exposure did not affect the radiopacity.

Conclusion: The Shr, DC, KH, and E values were highly correlated to the radiant exposure delivered to the RBCs. The combination of the higher irradiance for longer exposure time that resulted in radiant exposure between 24 J/cm2 to 48 J/cm2 produced better results than delivering 400 mW/cm2 for 40 s (16 J/cm2), and 800 mW/cm2 for 20 seconds (16 J/cm2) or 1200 mW/cm2 for 10 seconds (12 J/cm2). All the bulk-fill RBCs were sufficiently radiopaque compared to 4 mm of aluminum.