A comparison of dentin bond strength and degree of polymerization of bulk-fill and methacrylate-based flowable composites.

OBJECTIVE: This study aimed to evaluate the dentin bond strength and degree of polymerization of bulk-fill and methacrylate-based flowable composites. MATERIALS AND METHODS: Dentin bond strength of composites was evaluated using the microtensile bond strength (µTBS) test. Five different composites were applied on flat dentin surfaces with self-etch and etch-and-rinse adhesives. Twenty microspecimens with a 1 mm2 cross-sectional area were prepared for each group (n = 20). The µTBS test was then applied. To measure the degree of polymerization of composites, eight cylindrical blocks were prepared (n = 8) from each composite. The surface microhardness of each composite was measured on the bottom and top surfaces, and a hardness ratio (HR) was calculated. Data were analyzed using one-way ANOVA and the Tukey's honestly significant difference test (α = 0.05). RESULTS: According to the µTBS test results, the SDR Etch-and-Rinse group exhibited the highest dentin bonding strength and the Aelita self-etch group exhibited the lowest (P < 0.05). HR measurement showed that all composite groups had a sufficient degree of polymerization at a 2-mm thickness, while only the SDR and Xtra-Base groups had sufficient polymerization at a 4-mm thickness. CONCLUSIONS: Bulk-fill composite demonstrates an even higher degree of polymerization of methacrylate-based flowable composite when applied in a 4-mm thickness.

Color changes in resin cement polymerized with different curing lights under indirect restorations.

AIM: The aim of the study was to investigate the effects of different interface materials and curing units on color changes in a resin cement material. MATERIALS AND METHODS: Three interface materials and different curing systems, quartz-tungsten-halogen and polywave and monowave light-emitting diode (LED) light curing units, were studied at two-time intervals. Polystyrene strip was used as a control group. All measurements were made on a white background for standard color measurement. According to the CIE L*a*b* color space, the baseline color values of each specimen were measured. Differences between the measurements were calculated as ΔE, ΔL, Δa, and Δb. Data were analyzed using analysis of variance (ANOVA) and Duncan's tests (α = 0.05) with SPSS 20.0 software (SPSS Inc., Chicago, IL, USA). ANOVA revealed significance for interface materials and curing units and time for ΔE (P < 0.05). RESULTS: Interaction between polymerizing units, material and time was not significant (P > 0.05). Monowave LED exhibited significantly higher color changes than the other units ([P < 0.05] [ΔE 2.94 ± 0.44]). QTH promoted composite specimens significantly less color change ([P < 0.05] [ΔE 0.87 ± 0.41]). CONCLUSION: This study concluded that color of resin cement used in the adhesion of indirect restorations was affected by curing device light and indirect restoration material type.

Temperature changes caused by light curing of fiber-reinforced composite resins.

OBJECTIVE: The aim of the study is to evaluate temperature change in fiber-reinforced composite (FRC) resin photopolymerized with a light-emitting diode (LED) light-curing unit (LCU). MATERIALS AND METHODS: Forty dentine disks (1 mm thick and 8 mm diameter) were prepared from human molars. The FRC specimens (2 mm thickness and 8 mm diameter) consisted of polyethylene fiber (Construct (CT)) products or glass fiber (ever Stick (ES)) and one hybrid composite bonded to the dentin disks and polymerized with an LED LCU. Control groups were prepared using the hybrid composite. Temperature rise in dentine samples under the FRC bonded disks was measured using a K-type thermocouple, and data were recorded. Temperature change data were subjected to analysis of variance (ANOVA) and Duncan's test. RESULTS: The results show that addition of fiber (one or two layers) did not change temperature rise values at any of the exposure times (P > 0.05). The CT fiber/two layer/40 s group exhibited the greatest temperature rise (5.49 ± 0.62) and the ES/one layer/10 s group the lowest rise (1.75 ± 0.32). A significant difference was observed in temperature rise measured during 10 and 20 s exposures (P < 0.05). CONCLUSION: Maximal temperature rise determined in all groups was not critical for pulpal health, although clinicians need to note temperature rises during polymerization.

Temperature rise during polymerization of different cavity liners and composite resins.

OBJECTIVE: The purpose of this study was to evaluate the thermal insulating properties of different light curing cavity liners and composite resins during light emitting diode (LED) curing. MATERIALS AND METHODS: Sixty-four dentin discs, 1 mm thick and 8 mm in diameter, were prepared. Specimens were divided into four groups. Calcium hydroxide (Ca[OH]2), resin-modified glass ionomer cement, flowable composite and adhesive systems were applied to dentin discs according to the manufacturers' instructions. The rise in temperature during polymerization with a LED curing unit (LCU) was measured using a K-type thermocouple connected to a data logger. Subsequently, all specimens were randomly divided into one of two groups. A silorane-based composite resin and a methacrylate-based composite resin were applied to the specimens. Temperature rise during polymerization of composite resins with LCU were then measured again. Data were analyzed using one-way ANOVA and post hoc Tukey analyses. RESULTS: There were significant differences in temperature rise among the liners, adhesives, and composite resins (P < 0.05). Silorane-based composite resin exhibited significantly greater temperature rises than methacrylate-based resin (P < 0.05). The smallest temperature rises were observed in Ca(OH)2 specimens. CONCLUSION: Thermal insulating properties of different restorative materials are important factors in pulp health. Bonding agents alone are not sufficient to protect pulp from thermal stimuli throughout curing.

Effect of water storage on the translucency of silorane-based and dimethacrylate-based composite resins with fibres.

OBJECTIVES: The purposes of this study were (1) to determine the translucency of silorane and dimethacrylate-based composite resins and (2) to evaluate the effect of water storage and reinforcement with fibre on the translucency of composite resins. METHODS: Two light-cured composite resins (A2 shade), Filtek Silorane (silorane-based composite) and Valux Plus (dimethacrylate-based composite), were used in this study. The first group was used as the control with no reinforcements, the second was reinforced with polyethylene (Ribbond THM) and the third was reinforced with a glass fibre (Everstick Net) for each composite resin. Colour measurements were measured against white and black backgrounds with a Shadepilot (Degu Dent Gmbh, Hanau, Germany) spectrophotometer and recorded under a D65 light source, which reflects daylight. CIELAB parameters of each specimen were recorded at baseline and at 24 h, 168 h and 504 h. Translucency of materials was calculated using the translucency parameter (TP) formula. Data were analyzed using repeated measures ANOVA and LSD post hoc tests (α=0.05). RESULTS: The highest baseline TP value was in the Valux Plus/non-fibre reinforced group (14.06±1) and the lowest in the Filtek Silorane/Ribond THM group (8.98±1.11). Repeated measures ANOVA revealed significant effects from the factors storage time, composite resin, composite resin×storage time and fibre×time (p=0.047; p=0.001; p=0.013; p=0.022, respectively). CONCLUSION: Within the limitations of the study, we concluded that inclusion of polyethylene and glass fibres did not alter the translucency of the different-based composite resins. The longest storage time resulted in the greatest change in translucency values of Filtek Silorane composite resins. CLINICAL SIGNIFICANCE: Considering the translucencies of composites with different formulations in the selection of composite resins for aesthetic restorations is important in terms of obtaining optimal aesthetic outcomes.

Comparing the shear bond strength of direct and indirect composite inlays in relation to different surface conditioning and curing techniques.

OBJECTIVE: The aim of this study was to test the null hypothesis that different surface conditioning (etch and rinse and self-etch) and curing techniques (light cure/dual cure) had no effect on the shear bond strength of direct and indirect composite inlays. MATERIALS AND METHODS: A total of 112 extracted human molar teeth were horizontally sectioned and randomly divided into two groups according to restoration technique (direct and indirect restorations). Each group was further subdivided into seven subgroups (n = 8) according to bonding agent (etch and rinse adhesives Scotchbond multi-purpose plus, All-Bond 3, Adper Single Bond and Prime Bond NT; and self-etch adhesives Clearfil Liner Bond, Futurabond DC and G bond). Indirect composites were cemented to dentin surfaces using dual-curing luting cement. Shear bond strength of specimens was tested using a Universal Testing Machine. Two samples from each subgroup were evaluated under Scanning electron microscopy to see the failing modes. Data was analyzed using independent sample t-tests and Tukey's tests. RESULTS: Surface conditioning and curing of bonding agents were all found to have significant effects on shear bond strength (P < 0.05) of both direct and indirect composite inlays. With direct restoration, etch and rinse systems and dual-cured bonding agents yielded higher bond strengths than indirect restoration, self-etch systems and light-cured bonding agents. CONCLUSIONS: The results of the present study indicated that direct restoration to be a more reliable method than indirect restoration. Although etch and rinse bonding systems showed higher shear bond strength to dentin than self-etch systems, both systems can be safely used for the adhesion of direct as well as indirect restorations.

Effect of water storage and additional polymerization on the color parameters of flowable resin composites.

AIMS: Tooth colored dental restorative materials should maintain their chromatic properties throughout their service period. The aim of this study was to examine the possible color changes of flowable resin composite filling materials following water storage. The effect of additional light curing on color stability of restorative materials was also investigated. MATERIALS AND METHODS: Six brands of light-cured flowable resin composites of the same shade (A3) were prepared from two groups generated by curing for 20 or 60 seconds. The initial color parameters of the flowable composite samples were measured with a dental colorimeter according to the CIELAB color scale, and the samples were stored in distilled water at 37°C. Following 2 weeks' water storage, the measurements were repeated. The color differences (ΔE*(ab)) were calculated according to the CIELAB formula. Statistical differences between the measurements were analyzed by ANOVA and Duncan's tests. RESULTS: No initial color variation between the samples cured for 20 seconds and 60 seconds was perceptible (ΔE*(ab)<3.3). However, after 2 weeks' water storage, a noticeable color change, ΔE*(ab)>3.3, was detected in Eco-flow, Filtek Supreme and Grandio samples in both polymerization groups. CONCLUSION: Flowable resin composites may exhibit a significant color change as a result of water storage. Sixty seconds exposure period does not influence the final color. CLINICAL SIGNIFICANCE: Clinicians should be aware of color shifts in flowable resins.

Does peritoneal dialysis affect halitosis in patients with end-stage renal disease?

OBJECTIVE: There are various causes of halitosis, one of which is chronic renal failure. The objective of this study was to investigate halitosis levels in end-stage renal disease (ESRD) patients before and after peritoneal dialysis (PD) therapy. METHODS: 42 subjects with ESRD were included in this study. The presence of halitosis was assessed using an organoleptic measurement and compared with blood urea nitrogen (BUN) levels and salivary flow rates. Decayed, missing, and filled teeth (DMFT) index and Community Periodontal Index (CPI) were calculated. All measurements were done before and after patients had received 3 months of PD therapy. RESULTS: Mean serum BUN level was found to be lower (46.05 ± 13.30 vs 91.24 ± 31.28 mg/dL), salivary flow rate higher (0.34 ± 0.07 vs 0.26 ± 0.04 mL/minute), and halitosis level lower (2.39 ± 0.60 vs 3.90 ± 0.37) at the end of 3 months of PD therapy than at the beginning of PD therapy. There was no significant difference in CPI or DMFT index before and after PD therapy (p > 0.05). There was statistically significant positive correlation between the presence of halitosis and BUN levels (r = 0.702, p = 0.001 before PD; r = 0.45, p = 0.002 after PD) and a negative correlation between the presence of halitosis and salivary flow rates (r = -0.69, p = 0.000 before PD; r = -0.37, p = 0.01 after PD). CONCLUSION: High BUN levels and low salivary flow rates were found to be associated with halitosis. PD may play an important role in decreasing the level of halitosis in ESRD patients.

Direct laminate veneers with resin composites: two case reports with five-year follow-ups.

AIM: The aim of this report is to present five-year follow-ups of two different applications for the use of direct laminate resin-based composite veneers to improve esthetics. BACKGROUND: Defects in the maxillary anterior teeth, such as enamel hypoplasia and peg lateral, can present esthetic challenges. Furthermore, a treatment plan that can be completed in a single appointment is highly desirable. This case report presents two different clinical cases involving the use of direct laminate resin-based composite veneers with five-year follow-ups. CASE REPORT: Case 1: A 17-year-old female patient was referred for treatment of her anterior teeth, which were unesthetically altered due to enamel hypoplasia and dental caries. A treatment plan was developed that included restoring the affected teeth with direct resin-based composite laminate veneers to improve the patient's appearance. The six maxillary anterior teeth were prepared for and restored with direct resin-based composite laminate veneers. At the five-year follow-up, the patient was satisfied with the restorations both esthetically and functionally. Case 2: A 15-year-old female patient also was referred for treatment to improve the appearance of her maxillary anterior teeth. A treatment plan was developed with two objectives: (1) to restore the undersized supernumerary crown in the area of the maxillary right lateral incisor and (2) to close the anterior diastemas. The facial surfaces were conservatively prepared and resin-based composite was applied with the aid of transparent crown forms. After completion of the treatment, the patient was recalled at six-month intervals. At the five-year follow-up appointment, the restorations were intact, no adverse effects were noted, and the resultant appearance was highly satisfactory for the patient. SUMMARY: The use of direct resin-based composite laminate veneers and adhesive bonding systems has been shown to provide an esthetic alternative to metal-ceramic or all-ceramic crowns for the rehabilitation of anterior teeth. This treatment option offers another advantage, namely a lower cost compared to an indirect technique. Other more complex and costly treatment options in the future are not ruled out. CLINICAL SIGNIFICANCE: In the present two cases, the initial and five-year follow-up results support the use of direct resin-based composite laminate veneers with minimal altering of healthy tooth structure. Such results should encourage clinicians to seek a cost-effective technique such as direct resin restorations to improve a patient's esthetic appearance in a single appointment.

Quantitative EDXRF analysis of Ca, K, Mn and Na in normal and pathological adult-human teeth.

This work relates to the measurement of calcium, potassium, manganese and sodium levels in adult-human teeth from female and male patients and normal subjects. Energy dispersive X-ray fluorescence (EDXRF) technique was used for the measurements. Pathological and non-pathological adult-human teeth samples were collected from one male human patient and one female human patient who attended the dental clinic. The standard addition method was used to determine concentrations. Experimental results are presented and discussed in this work.

Cytotoxic effects of TEGDMA on THP-1 cells in vitro.

OBJECTIVE: Resin based dental materials are not stable in the oral environment and may release their components into biological media. These components may include substances such as triethylene glycol dimethacrylate (TEGDMA), which is a major co-monomer of dental resin materials. This release can trigger host immune and inflammatory responses against foreign materials, mediated by monocytes. The aim of this study was to investigate the possible cytotoxic effects of TEGDMA on human THP-1 monocytes. MATERIAL AND METHODS: THP-1 cells were exposed to various concentrations of TEGDMA (0.5 mM, 1 mM, 2 mM, 4 mM, or 8 mM) for 48 hours. An untreated group was used as control. The effects of TEGDMA on cell proliferation, cell viability and apoptosis were analyzed by light microscopy. RESULTS: Cell proliferation was inhibited by 4 mM and 8 Mm TEGDMA. Increasing TEGDMA concentrations caused a decrease in cell viability. All TEGDMA concentrations used in this study had an apoptotic effect on THP-1 cells when compared with the control group. CONCLUSIONS: The dental monomer TEGDMA had an adverse effect on cell proliferation and exerted an apoptotic and toxic effect on THP-1 cells in a concentration-dependent manner.

Coverage error of gingival shade guide systems in measuring color of attached anterior gingiva.

STATEMENT OF PROBLEM: It remains unclear which gingival shade guide is most effective in producing the best visual shade match. PURPOSE: The purpose of this study was to determine and compare the coverage errors (CEs) of 2 different gingival shade guides and their combination in a selected population. MATERIAL AND METHODS: The CEs of the following gingival shade guides were evaluated: (1) Lucitone 199, (2) IPS Gingiva, and (3) a combination of the 2 shade guide systems. The spectral reflectance values of the center of each gingival shade tab (1.5 mm in diameter) were measured (without a backing) with a spectroradiometer and an external light source at wavelengths from 380 nm to 780 nm at 2-nm intervals. All spectral reflectance measurements were made using 0-degree observer and 45-degree illumination and then converted to CIE values. The attached gingiva of 120 subjects was measured with the same protocol. The CEs of each of the 120 subjects' attached gingiva for each of the 2 shade guide systems and their combination were determined and averaged. The mean minimum CEs were analyzed with repeated measures ANOVA and the post hoc Tukey HSD for multiple comparison (alpha=.05). RESULTS: A significant difference (P<.001) was found among the mean minimum CEs of the 2 gingival shade guide systems and their combination. The Tukey HSD test revealed that the mean minimum CEs for Lucitone 199 (Delta E 10.8 +/-4.4) were significantly different from the IPS Gingiva (Delta E 8.6 +/-3.6) shade guide system. However, the combination of the 2 gingival shade guide systems (Delta E 7.9 +/-3.4) was not significantly different from the IPS Gingiva system, but a significant difference was found among races (P=.016). No interactions were found between the other tested groups. The mean CE for white individuals (Delta E 8.3 +/-2.5) is significantly different and less than the mean CE for African Americans (Delta E 10.0 +/-4.4). The CEs for Asians (Delta E=9.1 +/-4.3) and others (Delta E 9.0 +/-4.4) are not significantly different from CEs for whites or African Americans. CONCLUSIONS: The IPS Gingiva shade guide system resulted in the lowest CEs compared to the Lucitone 199 shade guide system. The mean CE for Lucitone 199 was significantly greater than the mean CE for IPS Gingiva and for the combination of the 2 guides. The mean CE for whites is significantly different and less than the mean CE for African Americans. The CEs for Asians and others are not significantly different from CEs for whites or African Americans.

The Association of HLA Class I and II Antigens in Teenagers with Caries Experience.

OBJECTIVE: There have been reports of a relationship between human histocompatibility antigen types and increased incidence of dental caries. The association between specific patterns of HLA genetic inheritance is not clear and not well studied. The aim of the study was to investigate the relationship between MHC alleles and DMFT index in 65 teenagers. MATERIALS AND METHODS: Sixty-five teenagers were recruited from the students of elementary school of the university campus and the patients of the Ataturk University Dental School hospital. Low-resolution typing for the HLA-A, B, C and HLA-DR/DQ were performed by PCR-SSP method using SSP HLA class I generic DNA Typing Tray. RESULTS: The results showed that HLA-DRB1*04 and -DRB1*07 frequencies were significantly higher (30.4% and 26.08% respectively) in DMFT≥1 group as compared with DMFT:0 group (10.5% and 5.26%), (p:0.168, OR:3.719; p:0.117, OR:6.353). Although frequencies of HLA-A*2, -B*27 and -B*51 alleles were increased in DMFT≥1 group, they were not statically important. HLA-DRB1*11 were found to be more common in DMFT: 0 groups. CONCLUSIONS: The pathogens involve in caries induce immune systems and response via the given HLA alleles could be important.

Surface hardness properties of resin-modified glass ionomer cements and polyacid-modified composite resins.

In this study the top and bottom surface hardness of two polyacid-modified composite resins (PMCRs), one resin-modified glass ionomer cement (RMGIC), and one composite resin were evaluated. The affect of water storage on their hardness was also investigated. The study was conducted using four different groups, each having five specimens obtained from fiberglass die molds with a diameter of 5 mm and a height of 2 mm. Measurements were made on the top and bottom surface of each specimen and recorded after 24 hours and again at 60 days. All tested materials showed different hardness values, and the values of top surfaces of the specimens were found to be higher than the bottom surface in all test groups. There was no statistical difference in the Vickers hardness (HV) values when the test specimens were kept in water storage. In conclusion Hytac displayed microhardness values higher than Vitremer and Dyract. We found the order of HV values to be Surfil > Hytac > Dyract > Vitremer, respectively. Vitremer presented the lowest microhardness level and Surfil the highest.

Bond strength of permanent cements in cementing cast to crown different core build-up materials.

The purpose of this laboratory investigation was to evaluate the bond strength of permanent cement (Duo-cement Kit, Meron, Durelon) to commonly used core build-up materials (President, Dyract AP, Ionofil, Vitremer). Sixty specimens (five of each product) were fabricated as a canine core build- up. Full crown castings were made to fit each core specimen. Full crown castings were cemented to core samples and stored at 37 degrees C and 100% humidity for 10 days. After storage, the bond strength was measured with a Haunsfield tensometer in tensile mode at a crosshead speed of 5 mm/min. Statistical evaluation was performed with univariate analysis of variance (P<0.001). The cement types affected the bond strength of full crown castings to core materials (F: 14.80; P<0.001). The interaction between the cement and core materials was significant (F: 3.69; P<0.01). According to the Duncan's test it was found that the values of Duo-cement were statistically different from the other cements.

Effect of eugenol and non-eugenol containing temporary cement on permanent cement retention and microhardness of cured composite resin.

This present study had three aims: 1) to evaluate the bond strengths of carboxylate and resin cements in cementing cast Co-Cr crowns to pretreatment of composite resin cores with eugenol and non-eugenol containing temporary cements, 2) to determine the microhardness of composite resin treated with temporary cement, 3) to view the surface differences of composite resin with SEM. The composite cores were divided into three experimental groups for the following pretreatments: Group 1, No treatment was provided, Group 2, The external walls of the composite cores were covered with eugenol-containing temporary cement, Group 3, The external walls of the composite cores were covered with non-eugenol containing temporary cement. Analysis of variance results showed that there was a significant difference between all three groups. Temporary cement with eugenol was significantly reduced the bond strength of full crown casting with resin cement compared with non-eugenol. The resin specimens treated with the eugenol-containing temporary cement showed the lowest microhardness values, the non-eugenol-containing temporary cement was not significantly different from those of the control groups.

The effect of "soft-start polymerization" on surface hardness of two packable composites.

It has been reported that light-initiated prepolymerization at low intensity followed by a post-light-cure at full intensity (soft-start polymerization) may lead to light-cured composite fillings with improved marginal integrity. The aim of this study was to examine the influence of softstart polymerization with different protocols on Vickers hardness of different packable composites. Vickers hardness of packable composites ALERT, and Definite were measured with a Vickers indenter and were evaluated. The results suggested that independent of the applied curing mode and curing tip, Alert showed significantly higher Vickers hardness than did Definite (p<0.05). There was no significant influence of curing mode or light guide on Vickers hardness of the samples tested. In conclusion, we found that soft-start polymerization does not have a significant influence on the degree of conversion, when compared with the conventional method. In addition, different light tips showed no significant improvement on surface hardness.