Universal Resin Composite Research Articles

Color Change Evaluation of Three Universal Resin Composites after Storage in Water: An In Vitro Study

Aim: The aim of this in vitro study was to evaluate the color changes of three different universal resin composites after immersion in distilled water for one month. Materials and Methods: Omnichroma, Estelite Σ Quick, and Filtek Universal Restorative were investigated. Ten disk shaped specimens (6 mm diameter, 2 mm thickness) were prepared according to the manufacturers’ instructions for each material. After polishing, initial color measurements were taken followed by individual storage of the specimens in distilled water at 37 °C for one month when color measurements were repeated. The change in the color of each resin composites (Δ E00) was calculated with a digital method, using the CIEDE2000 color difference formula. The data were analyzed using one-way ANOVA followed by Tukey post-hoc test ( P < .05). Results: All resin composites exhibited acceptable color change after one month. Omnichroma exhibited the highest color change (2.26 ± 0.48) value while Filtek Universal Restorative showed the lowest (1.14 ± 0.38) value. All color parameters influenced the Δ E00 values in all groups except Filtek Universal for Δ L* and Δ b values. Conclusion: When performing composite resin restorations, especially for esthetic purposes, polymerization may lead to change in the color of restorative material over time, but it should be considered whether this is within acceptable limits.

EVALUATION OF AESTHETIC RESTORATIONS PREPARED BY UNDERGRADUATE STUDENTS ON TYPODONT MODELS

The dental school curriculum is based on theoretical and practical courses. Before real patients, students practice on secure environments like typodonts or simulators to manage the functional and aesthetic properties of tooth restorations. This study aimed to evaluate the quality of class IV aesthetic restorations prepared by undergraduate dental students across different years of training, in terms of surface gloss, anatomic form, marginal adaptation, and proximal contact. Four consecutive classes of dental students (n = 15) were tasked with restoring a class IV cavity on a typodont tooth. Restorations were performed using a universal adhesive and nanohybrid resin composite. Evaluations were performed using the modified FDI criteria. Data were statistically analyzed by Kruskal–Wallis one-way analysis of variance, along with a t-test. The FDI scores for restorations by second-, fourth-, and fifth-year dental students were not significantly different. Third-year students had less success than others only in terms of incisal marginal adaptation. Forty-seven of the 60 (78.3%) restorations were clinically sufficient in all of the evaluated criteria. There were no statistically significant differences between the restorations performed by female and male students. The two-year preclinical training along with theoretical and practical education is sufficient for students to acquire basic restorative skills needed in clinical practice.

Surface gloss, gloss retention, and color stability of 2 nano-filled universal resin composites.

This study compared the surface gloss (SG), gloss retention (GR), and color stability (CS) of 2 universal resin composites after chemical (CA) and mechanical (MA) aging. Twenty disc-shaped samples of G-ænial A´Chord (GC-Europe) and Filtek Universal (3M-ESPE) were polished with sequential abrasive papers. For CA, specimens were stored in 1 mL of 75% ethanol for 15 days at 37°C, and readings (SG, GR, and CS) were obtained at baseline and 5, 10, and 15 days. For MA, specimens were subjected to 10,750 simulated brushing cycles. SG and CS were evaluated after every 3,583 cycles. SG was measured with a glossmeter (geometrical configuration: 60°), and values were expressed in gloss units. Color was measured with a spectrophotometer using the CIE-L*a*b* color system. The Student's t-test, 1-way analysis of variance, and Scheffé test were used for statistical analysis (α = 0.05). G-ænial presented significantly higher SG values than Filtek (p = 0.02), with GR reductions of 5.2% (CA) and 5.3% (MA) for G-ænial and 7.6% (CA) and 7.2% (MA) for Filtek. The aging protocol had no statistically significant effect on SG or GR (p = 0.25) from baseline to the final readings. G-ænial-MA presented the lowest color difference (∆E = 1.8), and G-ænial-CA and Filtek-CA had the largest changes (∆E = 8.6 and ∆E = 11.8, respectively). G-ænial presented higher SG values and better CS. Both restorative materials demonstrated acceptable GR and CS. Aging protocols impacted these properties negatively.

Evaluation of push-out bond strength of different concentrations of chitosan nanoparticles incorporated composite resin and eighth-generation bonding agent for class II restoration: An in vitro study.

The aim of this study is to evaluate the push-out bonding strength of class II cavities of maxillary molars restored with different concentrations of chitosan nanoparticles (CSN) incorporated in universal composite resin and eighth-generation dentin bonding agent (DBA). Seventy extracted human maxillary first molar teeth were cleaned and mounted in acrylic mold up to 2 mm below cementoenamel junction and mesio-occlusal Class II cavities with standard measurements were prepared. CSN 2% and 0.25% powder were added to the DBA and composite resin. The samples then arbitrarily divided into three groups for restoration: Group 1: composite restoration without CSN (control group) (n = 10), Group 2: 2% CSN (n = 30), and Group 3: 0.25% CSN (n = 30). Groups 2 and 3 were further subdivided into three subgroups (n = 10 each) subgroup A. CSN incorporated in composite resin. B. CSN incorporated in DBA and C. CSN incorporated in composite and DBA. After restoration, push-out bond strength was evaluated in each sample using a universal testing machine, and data collected were statistically analyzed by one-way analysis of variance and Post hoc Tukey tests (P ≤ 0.05). Subgroup 3A (0.25% CSN + composite) has shown an increase in bond strength among all experimental groups with no significant difference between group 1 (control group). CSN 0.25% incorporated in composite or DBA exhibits no harmful effect on the bond strength of class II restorations. Hence, it can be used to improve the antibacterial action and longevity of composite resin.

Effects of storage time and restoration depth on instrumental color adjustment potential of universal resin composites.

To determine the instrumental color adjustment potential (CAP-I)of 3 universal composites at 2 time intervals and 2 depths. Omnichroma, Estelite Sigma Quick, and Filtek Universal Restorative were tested. Two types of specimens were prepared. For dual specimens, Class V restorations were created in anterior denture teeth and restored with resin composites. For single specimens, replications were fabricated with resin composites (n = 10). Unrestored teeth were used for comparison. Color was measured with a spectrophotometer at 24 h and 1 month, and CAP-I was calculated. Data were compared by analysis of variance followed by the Student t-test and paired sample t-test. The CAP-I of tested materials ranged from 0.11 to 0.27 at 24 h and from 0.60 to 0.76 at 1 month. At 24 h, Omnichroma yielded the highest values, followed by Estelite Sigma Quick and Filtek Universal Restorative (P < 0.05). CAP-I was significantly higher at 1 month than at 24 h in all groups. In all groups, restorations with a depth of 3.0 mm yielded better results than restorations with a depth of 2.0 mm (P < 0.05). Storage time and restoration depth were positively associated with CAP-I. Single-shade and multi-shade universal composites are good alternatives for color-matched, esthetically satisfying restorations.

Clinical performance of one shade universal composite resin and nanohybrid composite resin as full coronal esthetic restorations in primary maxillary incisors: A randomized controlled trial.

Strip crowns are the first treatment of choice for restoring anterior teeth affected with early childhood caries. However, shade matching of resin composites is still an issue. The broad color matching ability of a recently introduced single shade composite, Omnichroma eliminates the need for shade-matching procedure, reduces composite inventory, and minimizes chair-side time. The aim is to evaluate the color match, color stability, and retention of one shade universal composite resin, Omnichroma and nanohybrid resin composite, Tetric-N-Ceram. The study design involves split-mouth randomized controlled trial. The study was conducted on 25 children aged 3-5 years with multi-surface caries lesions in primary maxillary anterior teeth. Teeth were allocated to two groups randomly: Group 1 - One shade universal composite, Omnichroma (n = 25), Group 2 - Nanohybrid composite, Tetric-N-Ceram (n = 25). After caries excavation and tooth preparation, teeth were restored with corresponding materials using strip crowns. Color match at baseline, color stability, and retention after 6- and 12-month follow-up were evaluated using the Modified United States Public Health Services criteria. The Mann-Whitney U test and Wilcoxon signed-rank test were used to analyze the data. On comparison of Omnichroma and Tetric-N-Ceram groups, no statistically significant difference was observed in the color match at baseline (P = 0.716) as well as color stability (P = 0.575 at 6 months and 0.990 at 12 months) and retention (P = 0.153 at 6 months and 0.226 at 12 months) at both 6- and 12-month intervals. On intragroup comparison, the difference in the color stability at 6 and 12-month interval was statistically significant (P = 0.001) for both the groups, indicating that the color stability of restorations was better at 6-month interval compared to 12-month interval. In both Omnichroma and Tetric-N-Ceram groups, retention of restorations was better at 6-month interval compared to 12-month interval and this difference was statistically significant (P = 0.025 and 0.014, respectively). The clinical performance of Omnichroma in terms of color match, color stability, and retention was comparable to nanohybrid composite, Tetric-N-Ceram.

Comparison of mechanical and optical properties of a newly marketed universal composite resin with contemporary universal composite resins: An in vitro study.

The purpose of this study was to evaluate the surface roughness, microhardness, color change, and translucency of a newly marketed universal nanohybrid composite resin (CR) (G-aenial A'CHORD) comparing with four contemporary universal CRs including two nanofilled (Filtek and Estelite Asteria) and two nanohybrid CRs (Charisma Dimond and Neo Spectra ST HV in vitro). Sixty-five specimens (8.0 mm × 2.0 mm) were fabricated (n=13, per group). After finishing and polishing, specimens were subjected to surface roughness and microhardness tests. Color and translucency of the specimens were evaluated at baseline and after darkening with coffee solution at day 1 and day 7. A representative specimen from each group was investigated under scanning electron microscopy (SEM). Data was analyzed statistically (p < .05). There were significant differences among the groups in terms of surface roughness, microhardness, color, and translucency. The surface roughness was recorded as: Charisma Diamond > Neo Spectra ST HV, Filtek > Estelite Asteria, G-aenial A'CHORD, whereas Vickers Hardness number was as: Filtek, Charisma Diamond > Neo Spectra ST HV > G-aenial A'CHORD, Estelite Asteria. Color change was as: Charisma Diamond > Neo Spectra ST HV, Filtek, G-aenial A'CHORD > Estelite Asteria and the translucency was as: Neo Spectra ST HV > G-aenial A'CHORD, Filtek > Estelite Asteria, Charisma Diamond. SEM examinations revealed smooth surfaces for G-aenial A'CHORD, Neo Spectra ST HV and Estelite Asteria. Mechanical and optical properties of universal composite resins with different compositions show variations.

Investigation of the effect of different application techniques on microhardness in bulk-fill composite resins

Aim: The aim of this study was to investigate the effect of different application techniques on microhardness in one universal resin material and three different bulk-fill composite resin materials.&#x0D; Materials and Methods: In this study, one universal composite resin (Universal Restorative 200 [U], 3M-ESPE, USA) and three different bulk-fill composite resins (Filtek-One Bulk-Fill Restorative [F]; 3M-ESPE, USA: Tetric Evo-Ceram Bulk-Fill [E]; and Ivoclar-Vivadent, Liechtenstein; Tetric N-Ceram Bulk-Fill [N], Ivoclar-Vivadent, Liechtenstein) materials were used. A total of 60 disk-shaped samples, including 20 samples from each bulk-fill composite resin group, were prepared. The polymerization of the bulk-fill composite resins in one group was completed using a 2 mm (40 sec) + 2 mm (40 sec) incremental technique, and in the other group, it was completed using a 4 mm bulk technique (40 sec). The U composite resin (control group) polymerization was completed using a 2 mm + 2 mm (40 sec) incremental technique (n = 10). The Vickers microhardness (VHN) values ​​of the samples were calculated. The data were analyzed with Kruskal–Wallis and Mann–Whitney U tests (p &lt; 0.05).&#x0D; Results: Higher VHN values ​​were found in the U composite resin compared to those in the bulk-fill composite resins (p &lt; 0.05). In the bulk technique, a lower VHN value ​​was observed in the N bulk-fill composite resin than in the control group (p &lt; 0.05), while there was no difference between the N and E composite resin groups (p &gt; 0.05). A lower N bulk-fill composite resin was observed in the groups in which the incremental technique was applied than in the control group (p &lt; 0.05). When the techniques applied to the bulk-fill composite resins were evaluated within themselves, higher VHN values ​​were observed in the E composite resin in the group in which the incremental technique was applied but not in the group in which the bulk was applied.&#x0D; Conclusion: It was observed that the content differences of composite resins were effective at different VHN values. The U composite resin (control) group showed higher VHN values than all the bulk-fill composite groups.&#x0D; &#x0D; How to cite this article: Fidan M, Gönder HY. Investigation of the effect of different application techniques on microhardness in bulk-fill composite resins. Int Dent Res 2021;11(Suppl.1):32-7. https://doi.org/10.5577/intdentres.2021.vol11.suppl1.6&#x0D; &#x0D; Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

A Two-Year Comparative Evaluation of Clinical Performance of a Nanohybrid Composite Resin to a Flowable Composite Resin.

Objective: This prospective in vivo study aimed to compare the clinical behavior of a flowable composite resin (Genial Universal Flo, GC) and a nanohybrid universal composite resin (Tetric Evo Ceram, Ivoclar Vivadent) used in Class I and II direct esthetic restorations in posterior teeth. Methods: A total of 108 Class I and II direct restorations were performed in patients aged between 20 and 60 years. The originality of this study lies in the fact that both materials were placed in pairs, in the same clinical environment (i.e., the same patient and the same type of tooth). The evaluations were performed now of restoration and after 2-weeks, 6-, 12-, and 24-months intervals using clinical examination, clinical photographs, and radiological examination, according to modified USPHS criteria. Statistical analysis was performed using the Fisher exact test and chi-square analysis. Results: At baseline, the universal composite resin showed better esthetic properties such as surface luster, surface staining marginal staining. Both materials regressed significantly over time with no significant difference between groups. Conclusions: Both flowable and nanohybrid composite resins exhibit acceptable clinical performance. The present 24 months of evaluation of different composites showed that the G-ænial Universal Flo could be an effective esthetic material for posterior restoration. No significant difference between both materials over time concerning surface luster, surface staining, and marginal staining.

Handling properties and surface characteristics of universal resin composites

This study investigated the handling and surface characteristics of universal resin composites and determined the interrelations among the composites' handling, mechanical, and physical properties. Five recently introduced universal resin composites were tested. Twelve specimens per material were used to measure the stiffness and stickiness (handling properties) of the resin composite pastes. Additionally, surface properties (Knoop hardness number [KHN], surface roughness [Sa], surface gloss [SG], water contact angle [CA], and surface free energy [SFE]) of cured resin composites were determined in 12 specimens per material immediately after preparation (baseline) and after subjection to thermal cycles (TCs). Handling and surface properties of the resin composites were material dependent. All the resin composites showed significantly lower KHN in the post-TC subgroups than that in the baseline subgroups. However, the influence of TC on the other surface properties was dependent on the material used. Some resin composites did not indicate any significant differences in Sa, SG, or CA between the baseline and post-TC groups. Although the resin composites in the baseline groups presented with different handling and surface properties, the surface properties of most of the composites were significantly affected by TC. Extremely strong positive or negative correlations were observed between stiffness and stickiness, KHN and Sa, KHN and SG, Sa and SG, and CA and SFE. Most correlations between the handling and surface properties were weak. Therefore, the selection of resin composites in clinical situations should be based on comprehensive consideration of their properties.

Effect of different composite materials used as core build-ups on the trueness of intraoral scanning.

To evaluate the trueness of digital impressions of different composite resin materials that can be used for core build-ups in clinical practice. A maxillary central incisor was prepared and scanned with an intraoral scanner (Primescan, Dentsply Sirona). Ten composite resin specimens (in three groups: universal composite; flowable composite; and bulk fill resin composite) were milled in the same dimensions of the prepared tooth and scanned. The data of the prepared tooth were used as reference, and the data obtained from the composite resin specimens were aligned with the evaluation software (Geomagic Studio 12) to determine deviation values. Kruskal-Wallis with Dunn post hoc test was performed (α = .05). There were significant differences in the trueness of digital impressions between some composite resin groups (P < .05). The mean trueness deviation values were in the range of 12.75 μ m (G-aenial Posterior) to 17.06 μ m (Filtek Bulk Fill Posterior). The trueness of G-aenial Posterior (12.75 μ m) was higher than that of Core-X Flow (14.62 μ m), Clearfil Majesty Flow (16.93 μ m), and Filtek Bulk Fill Posterior (17.06 μ m). Filtek Bulk Fill Posterior exhibited lower trueness than Clearfil Majesty Esthetic (12.93 μ m), Clearfil Majesty Posterior (13.50 μ m), and Charisma Classic (13.81 μ m). Different composite resins used for core build-up can impact the trueness of digital impressions, with universal composite resin scans being the truest compared to flowable and bulk fill composite resin scans. All scanned substrate groups can be regarded as within a clinically acceptable range.

Evaluation of wear property of Giomer and universal composite in vivo

Objective To observe the wear performance of Giomer and universal composite for posterior restorations by 3D laser scan method, in order to guide the material selection in clinic. Methods In this study, 48 patients (108 teeth) were selected according to the inclusion and exclusion criteria. All the patients in need of a minimum of 2 Class Ⅰ and/or Class Ⅱ restorations were invited to join the study. The teeth were restored with Giomer (Beautifil Ⅱ, BF) and universal composite (Filtek Z350, Z350) randomly. The restorations were evaluated at baseline and after 6-, 18-, 48-month using the modified United States Public Health Service (USPHS) criteria for clinical performance. The in vivo images and gypsum replicas were taken at each recall. A 3D-laser scanner and Geomagic Studio 12 were used to analyze the wear depth quantitatively. Statistical analysis was performed with SPSS 20.0. Results After 4 years, 89.6% patients were recalled. The survival rate of both materials was 95.8% (Kaplan-Meier survival analysis). Seven restorations of the two materials failed due to loss of restoration, bulk fracture, secondary caries and pulp necrosis. The wear patterns of restorations were divided into 2 classes. Pattern Ⅰ: occlusal contact areas showed the deepest and fastest wear depth; pattern Ⅱ: the wear depth was slow and uniform. Both materials showed a rapid wear in the first 6 months. Then the wear rate was decreased. The occlusal wear depth after 4 years were (58±22) μm and (54±16) μm for BF group and Z350 group respectively, which were in accordance with the American Dental Association (ADA) guidelines (wear depth for 3 years 0.05) were observed between the two groups. Regarding the restorations with wear pattern Ⅰ, the wear depth of BF group was higher than Z350 group at 6- and 48-month (P 0.05). Conclusion Within the limitation of the study, after 4 years, the survival rate and wear resistance of Giomer met ADA guidelines for tooth-colored restorative materials for posterior teeth. When the two materials were applied in occlusal contact areas, wear resistance of Giomer was slightly lower than universal composite resin. No significant difference was found when they were applied in none of the occlusal contact areas.

Adhesive dentistry: Current concepts and clinical considerations.

To address contemporary concepts in adhesive dental materials with emphasis on the evidence behind their clinical use. Adhesive dentistry has undergone major transformations within the last 20 years. New dental adhesives and composite resins have been launched with special focus on their user-friendliness by reducing the number of components and/or clinical steps. The latest examples are universal adhesives and universal composite resins. While clinicians prefer multipurpose materials with shorter application times, the simplification of clinical procedures does not always result in the best clinical outcomes. This review summarizes the current evidence on adhesive restorative materials with focus on universal adhesives and universal composite resins. (a) Although the clinical behavior of universal adhesives has exceeded expectations, dentists still need to etch enamel to achieve durable restorations; (b) there is no clinical evidence to back some of the popular adjunct techniques used with dental adhesives, including glutaraldehyde-based desensitizers and matrix metalloproteinase inhibitors; and (c) the color adaptation potential of new universal composite resins has simplified their clinical application by combining multiple shades without using different translucencies of the same shade. New adhesive restorative materials are easier to use than their predecessors, while providing excellent clinical outcomes without compromising the esthetic quality of the restorations.

Color Matching of a Single Shade Structurally Colored Universal Resin Composite with the Surrounding Hard Dental Tissues

Color matching between the resin composite and the teeth is the most aimed target by the patient to evaluate the quality of the treatment. The aim was to investigate the ability of the uni-shade restorative material to match the tooth shade and the blending effect of the single shade structurally colored universal resin composite. Materials and methods disc shaped specimen (6×2 mm) were prepared from Omnichroma® single shade resin composite. Color shade was recorded for 10 freshly extracted premolars by Easyshade® according to CIE Lab system. Standardized class V cavities (4×2×1.5 mm) were prepared on the buccal surface of each tooth away 0.5mm from the CEJ. Cavities were then restored with resin composite, cured for 40s, and their color was recorded after 24 hours storage in distal water. Two tests have been done, the first was to determine the differences of the color parameters between disc and resin composite in teeth (T1). The second was to record the change in color between the sound teeth and the resin composite in teeth (T2). The color change data statistically analyzed using paired t-test. It was considered statistically significant at(a=0.05). Results All color parameters in the two tests showed significant changes except (ΔL) in T2 which showed nonsignificant differences. The specimens showed decrease in lightness and showed shifting toward the green and yellow direction, while in T2 they became lighter than the teeth and directed toward the green and blue scale. Conclusion OMNICHROMA single shade resin composite matches the shade of enamel.

Discoloration of flowable and universal resin composites immersed in black tea for 30 days

Discoloration of flowable and universal resin composites immersed in black tea for 30 days

Influence of water aging on surface hardness of low-shrinkage light-cured composite resins

This study evaluated the microhardness of four types of low-shrinkage composite resins and two types of universal composite resins with either 12 or 16 J/cm2 light power energy. Three disks were made for each group (n = 3) for a total of 36 specimens. The specimens were prepared by condensing the composite resin into a circular copper mold (diameter: 6 mm; height: 2 mm) and polymerizing with 700 mW/cm2 light power density. The microhardness values of the resin specimens were measured using a Vickers hardness tester after different storage durations. Z250 and Clearfil Majesty Posterior composites showed softer subsurfaces when comparing the 24 h samples for all six types. Conversely, Kalore GC and Admira (AD) composites showed harder subsurfaces during the 24 h samples. All the composite resins showed significant differences (P < 0.05) in microhardness values at one of the aging times when they were polymerized with either 12 or 16 J/cm2 light power energy. Composite resin AD had a higher microhardness value after polymerization with 12 J/cm2 than with 16 J/cm2. The results indicated that low-shrinkage composite resins have better subsurface characteristics, and the light power energy of 16 J/cm2 is better for the polymerization of most composites.

An 18-month clinical evaluation of three different universal adhesives used with a universal flowable composite resin in the restoration of non-carious cervical lesions.

The aim of this randomized, controlled prospective clinical trial was to evaluate and compare the performances of three different universal adhesives using a flowable universal composite resin in the restoration of non-carious cervical lesions (NCCLs) over an 18-month period. Eighteen participants recieved 99 restorations from a single operator. NCCLs were divided into three groups according to adhesive systems used: Clearfil Universal Bond (CU), iBOND Universal (IU), and G-Premio Bond (GP). No enamel bevel was placed and no mechanical retention was created for the NCCLs. Prior to adhesive procedures, selective etching was performed with 37% phosphoric acid. Adhesive systems were applied following manufacturers' instructions and the lesions were restored with a flowable composite resin (G-ænial Universal Flo). Restorations were finished and polished immediately after placement and scored with regard to retention, marginal discoloration, marginal adaptation, sensitivity, surface texture, and color match using modified USPHS criteria after a week (baseline) and 6, 12, and 18months. Descriptive statistics were performed using chi-square tests. The 18-month recall rate was 88.8% and retention rates for CU, IU, and GP were 100%, 96.8%, and 100%, respectively. No restorations exhibited post-operative sensitivity and secondary caries. After 18months, CU, IU, and GP groups showed similar alpha rates for marginal adaptation (CU 93.1%, IU 90%, GP 81.8%) and marginal discoloration (CU 100%, IU 90%, GP 87.9%). A total of ten (CU 2, IU 3, GP 5) restorations exhibited bravo scores for surface texture and three (CU 2, GP 1) restorations showed bravo score for color match. No statistical differences were found among the tested adhesives for any criteria evaluated (p > 0.05). The three adhesive systems demonstrated similar performances during the 18-month follow-up in the restoration of NCCLs. Universal adhesives could be used successfully in the restoration of NCCLs.

Effect of routine scaling and prophylactic polishing on the surface roughness of nano-filled restorative materials: In vitro study

AimThis study aimed at investigating in vitro the effect of routine scaling (hand/ultrasonic) and polishing on the surface roughness of three nano-filled restorative materials. Materials and methodsNano-filled universal resin composite (Filtek Z350), nano-filled flowable resin campsite (Filtek Supreme Plus Flow) and resin modified glass ionomer (Ketac N100) were tested. Ninety discs (10 mm × 2 mm) were prepared and divided into 3 groups (n = 30/material). Each group was divided into 5 subgroups (n = 6). Subgroup 1: control (surface against matrix), subgroup 2: ultrasonically scaled (US), subgroup 3: hand scaled, subgroups 4 and 5 were US, hand scaled then received prophylactic polishing respectively. The mean surface roughness (Ra μm) of all specimens was measured by a profilometer. Data were statistically analyzed by ANOVA and post-hoc tests (P ≤ 0.05). Representative specimens were examined by the SEM. ResultsUnder all testing conditions, Ketac N showed the highest mean Ra value expect for hand scaled/non-polished specimens, where they were not significantly different than the Filtek Z350 as confirmed by SEM. However, under all testing conditions, Filtek Flow revealed the lowest mean Ra values except for polished specimens after either hand or US scaling; there was insignificant difference between Filtek Z350 and Filtek Flow. ConclusionsScaling method tends to have material dependent effect on the Ra. All polished material's Ra exceeded the critical threshold roughness values. Clinical significanceRoutine periodontal scaling and prophylactic polishing of nano-filled resin restorations should be carried out with caution. Nano-filled flowable resin composite can be recommended in Class V restorations.

Color recovery effect of different bleaching systems on a discolored composite resin

Discoloration of resin-based composites is a commonly encountered problem, and bleaching agents may be used for the therapy of the existing discoloration. The purpose of this study was to investigate in vitro color recovery effect of different bleaching systems on the heavily discolored composite resin. Fifty disk-shaped dental composite specimens were prepared using A2 shade nanohybrid universal composite resin (3M ESPE Filtek Z550, St. Paul, MN, USA). Composite samples were immersed in coffee and turnip juice for 1 week in each. One laser activated bleaching (LB) (Biolase Laserwhite*20) and three conventional bleaching systems (Ultradent Opalescence Boost 40% (OB), Ultradent Opalescence PF 15% home bleaching (HB), Crest 3D White [Whitening Mouthwash]) were tested in this study. Distilled water was used as control group. The color of the samples were measured using a spectrophotometer (VITA Easy shade Compact, VITA Zahnfabrik, Bad Säckingen, Germany). Color changes (ΔE00) were calculated using the CIEDE2000 formula. Statistical analyses were conducted using paired samples test, one-way analysis of variance, and Tukey's multiple comparison tests (α = 0.05). The staining beverages caused perceptible discoloration (ΔE00 > 2.25). The color recovery effect of all bleaching systems was statistically determined to be more effective than the control group (P < 0.05). Although OB group was found as the most effective bleaching system, there was no statistically significant difference among HB, OB, and LB groups (P > 0.05). Within the limitation of this in vitro study, the highest recovery effect was determined in office bleaching system among all bleaching systems. However, home and laser bleaching systems were determined as effective as office bleaching system.

Time Sensitivity Associated with Application of HEMA-free Adhesive

Background: Acetone is one of the solvents incorporated in HEMA-free dental adhesives. Since acetone is very sensitive with high vapor pressure, acetone-based adhesives necessitate great care and attention in handling and application. Objective: The aim of this study was to determine the optimal application time of acetone-based HEMA-free adhesive by conducting micro tensile bond strength test (MTBS) at different time intervals. Materials and Methods: Twelve freshly extracted non-carious human molars were collected. Two-thirds of the roots were removed and the coronal part of the teeth was subjected to horizontal cross-sectioning in order to remove their cusps and expose the superficial coronal dentin. Then, the teeth were randomly divided into 4 groups (3 teeth each) according to the adhesive application time before curing. One- step self-etch HEMA-free adhesive (G bond; GC, Japan) and universal resin composite (Kalore; GC, Japan) were used in this study. In group (A), application of adhesive was carried out for 15 sec as recommended by the manufacturer instructions. In groups (B), (C) and (D), the adhesive was applied for 30 sec, 1 min and 5 min, respectively, before curing. After 24-hour storage in distilled water at 37°C, each tooth was cross-sectioned into micro beams and subjected to MTBS test by using a universal testing machine. Results: The tests showed statistically significant differences among the groups (P = 0.00) with each group is different from the others (P = 0.00). Group A had the highest mean strength value followed by groups B, C and then D with 57.7, 41.6, 29.7 and 17.1 MPa, respectively. Conclusion: The tested adhesive might be sensitive to application time as shown by superior MTBS results when its application time lasts for 15 seconds. This might be explained by evaporation of acetone in one-step acetone-based self-etch adhesives.