Aim To in vitro evaluate the bleaching effect on the color match of Omnichroma composite resin restorations to the teeth color. Materials and methods Thirty freshly extracted intact human premolars were collected and mounted in acrylic resin blocks (only roots were embedded). The shade of the selected teeth was measured by (VITA Easyshade V). Class V cavities (4 mm width, 2 mm length, and 2 mm depth) were prepared 2 mm coronal to cement-enamel junction on the cervical third of the facial surface of each tooth. Specimens were randomly divided into two equal groups ( n = 15): group I: was restored with nano hybrid Tetric N- ceram while group II: was restored with Omnichroma supra-nano filled composite resin using their respective adhesives. All the specimens were thermocycled for 500 cycles from 5 to 55°C with 15 s dwell time, and 20 s transfer time. The initial data of color measurements for tooth and restoration surfaces were recorded after thermocycling using VITA Easy Shade V. Specimens were then bleached using 40% HP by White smile power whitening YF according to the manufacturer instructions and kept in artificial saliva for 1 week before color re-measuring. All data were collected, tabulated, and statistically analyzed at 95% significance level using a software statistical package for social sciences (SPSS version 26). Results Before bleaching, higher mean ΔΕ values were recorded for the teeth (3.38 and 2.74) compared to (2.24 and 1.82) of the restorations in group I (Tetric N) and group II (Omnichroma) respectively with no statistically significant difference ( P = 0.26 and 0.43) in either of the groups denoting the color match between the restorations and the teeth in both groups. After bleaching there was a highly statistically significant difference ( P = 0.039) between the mean ΔΕ values of teeth (5.56) and restorations (3.23) in group I, denoting the color mismatch. While in group II there was no significant difference ( P = 0.249) between the values of teeth (5.25) and restorations (4.49) denoting the persistence of the color match after bleaching. No significant difference was found between the ΔΕ values of teeth used in both groups neither before ( P = 0.62) nor after bleaching ( P = 0.802). While there was a significant difference between the recorded values of the restorations after bleaching ( P = 0.026) although the difference was not significant before bleaching ( P = 0.619). Bleaching significantly affected the teeth color ( P = 0.013 and 0.038), and the restoration color ( P = 0.049 and 0.012) in groups I and II, respectively. Conclusions Omnichroma class V composite restorations matched the shades of teeth before and after bleaching where it was changed to a lighter shade with the teeth enamel that was within the acceptable clinical range. The color matching of the Tetric N restorations after bleaching was lost where the teeth were lighter in a clinically detectable manner, which necessitates restoration replacement.

Abstract Purpose To investigate the effect of different stains on Omnichroma nano filled composite resin restorations compared to a conventional nano hybrid composite resin restorations. Patients and methods A total of 60 intact human upper premolars with shade A2 were embedded in self-curing acrylic resin (roots only) 2 mm below the cement-enamel junction. A trapezoidal Class V cavity was prepared on the buccal surface of each tooth, a width of 4 mm occlusally and 3 mm gingivally, and 3 mm occluso cervically. The cervical margins were located 2 mm coronal to cementoenamel junction. All cavities were 2 mm in depth. Teeth were randomly divided into two equal groups ( n = 30), group I (Omnichroma composite resin) and group II (Tetric Evoceram composite resin). All specimens were incubated at 37°C, 100% humidity in artificial saliva for 24 h, then subjected to 500 thermo cycles between 5°C and 55°C, 30 s dwell time, and a transfer time of 15 s. The color of specimens and restorations (base line) was recorded by Vita Easy shade V. Each group was randomly subdivided into three sub-groups ( n = 10 specimens) and immersed in artificial saliva, coffee, and tea for 48 h. Color measurements were done again after immersion time. All data was collected, tabulated, and statistical analysis was performed using Statistical Package for Social Science (SPSS version 26). Results In base line evaluation, there was no statistical significant differences for mean values of (ΔE) between both groups and within each group teeth surfaces versus composite restorations, still, there was no significant difference after immersion 48 h in saliva, however, a significant difference was recorded after immersion 48 h in both coffee and tea between both groups regarding composite values, and a statistical significant difference recorded within group II between teeth and restorations. All collected data for tested specimens were analysed to conclude the difference in ΔE of teeth surfaces and composite restorations of both groups between baseline and after 48 h immersion in different solutions, recording a statistical significant difference for teeth surfaces and composites of group I and group II. The difference in (ΔE) between both tested groups regardless the immersion solution was analysed. A significant difference was recorded. Conclusion Omnichroma composite resin matches the shade of tooth for class V restorations. Coffee recorded the highest staining mean values, followed by tea, and lowest mean values recorded by saliva. The claim of manufacturer that Omnichroma has a chameleon effect to obtain the same color of the surrounding tooth surfaces was accepted.

Purpose This in vitro study evaluated the internal and marginal adaptability of different composite resins in class V cavities. Materials and methods Thirty human maxillary premolars were selected. Trapezoidal class V were prepared on buccal surface. Flowable, self-adhering flowable and nanohybrid composites were applied following their manufacture instructions, in groups I, II and III respectively. Specimens were subjected to 500 thermal cycles and then examined under a stereomicroscope to determine the marginal gap width. All specimens were then sectioned buccolingually into two sections to detect and measure the internal gap width. Results The highest mean value of occlusal gap was recorded for Group II followed by Group I while the lowest value was recorded in Group III. Similar results were found regarding the cervical margins, with no statistically significant difference between the groups. Comparing occlusal versus cervical marginal gap a highly significance difference was recorded in each group. The highest internal mean gap width was recorded in Group III, followed by Group II while the lowest in Group I, with no significant difference between them. Conclusion All tested materials showed satisfactory marginal adaptation with no significant benefits of the self-adhesive composite. The nano hybrid composite showed the best marginal adaptation while the flowable composite showed the best internal adaptation.

Aim To evaluate and compare initial enamel caries treated by ozone gel with or without nanohydroxyapatite paste or fluoride gel. Materials and methods 30 intact, noncarious freshly extracted human premolars, were collected, cleaned from all soft debris and/or calculus and polished using prophy polishing paste. Each tooth was sectioned first at cement enamel junction (CEJ) to separate crown after removal of root. Each crown was mesiodistally sectioned to a thickness of 1–2 mm then stored in artificial saliva which was periodically changed. All the specimens were exposed to demineralizing solution at occlusal surface only (the surface of the study) for creation of enamel lesions. All the specimens were examined with, EDX and tested under PLM to evaluate enamel surface. After demineralization the specimens were divided randomly into three equal groups I, II and III consist of 10 specimens of each group. For group I Ozonized olive oil gel was used alone on occlusal surface for 1 min once daily, group II was treated as group I followed by application of 5% nanohydroxyapatite paste, while all specimens in group III were treated as group I followed by fluoride gel application. All the procedures at the three groups were repeated daily for 21 days. Result It was found that nonsignificant difference among the mean wt % values of mineral contents (Ca, P, and Ca/P ratio) between the three treatment groups at baseline and after demineralization (P ≥ 0.5), by using ANOVA test at remineralization stage it was found that (group II) recorded the highest mineral content with a mean value of 69.58 ± 1.54 followed by (group III) with a mean value of 69.36 ± 1.04 while the lowest mineral content mean value was 67.43 ± 0.92 which related to (group I). Also, highly statistically significant difference between the three groups was recorded (P = 0.001). Findings using PLM supported the previous results revealing decrease in optical reflectivity and the positive birefringent area which was about to appear broad positively birefringent body after demineralization and disappear after remineralization indicating a great mineral content recovery at all the three groups.

Purpose To in vitro evaluate the marginal and internal adaptation of Thermo-Viscous versus SonicFill Bulk Fill composite in Class I cavities. Materials and methods Twenty non-carious human maxillary premolar teeth were selected. Class I cavities were prepared with dimensions of 4 mm mesio-distal, 2.5 mm bucco-lingual width and 2 mm depth. Specimens were randomly divided into two equal groups I and II. Cavities were restored with VisCalor and SonicFill Bulk Fill, respectively. Materials were applied using the recommended adhesive and special dispenser. Specimens were then subjected to 500 thermal cycles, labelled and the restoration margins were inspected under stereomicroscope at X70 to detect and measure the marginal gap width. Specimen were then sectioned buccolingually using a microtome to detect and measure the internal gap width. Results Lower mean values of marginal gap width were recorded in VisCalor group compared to SonicFill group, however there was no statistically significant difference ( P = 0.187) between both groups. While a significant difference ( P = 0.002) was found regarding internal mean gap width values recorded in VisCalor group compared to SonicFill group. Conclusion Both tested materials/techniques used to reduce the viscosity of the bulk fill composites presented nearly comparable marginal integrity results, while VisCalor application technique enhanced the internal adaptation compared to SonicFill method.

Aim The aim to this study is to evaluate the biocompatibility and antibiofilm actions of two nano-hydroxy apatite (NHA). Methodology Nano-hydroxy apatites are biomaterials use in direct contact with living tissues. Therefore, they should be tested for their safety beside assessment of their minimum inhibitory (MIC) and minimum bactericidal concentration (MBC) using broth microdilution method. One hundred and twenty extracted bovine incisors were collected and cleaned to ensure the absence of any defects. Enamel blocks with different size (2 × 2 × 3 mm) and (5 × 5 × 2 mm) were prepared from their labial surfaces using an isomet saw. Enamel blocks are used for detecting the suitable concentration will be used in the following experiments using energy dispersive X-ray analysis (EDX). The remaining enamel blocks divided into 5 equal groups to detect inhibitory effect against bacterial adhesion to the initial enamel caries like lesions using viable count technique beside the antibiofilm activity against mature biofilm of Streptococcus mutans (S. mutans) using confocal laser microscopy. The remaining enamel blocks were used as a representing data for detecting surface topography for each group by using the scanning electron microscopy (SEM). Result The data showed safety of NHA suspensions. Additionally, only NHA suspension of large nanoparticle size (NHA-LPS) had MIC of 1.25 mg/ml against S. mutans. Also, have the higher percentages of Ca and P in the enamel blocks. Furthermore, the lowest level of bacterial adhesion was recorded in (group III) treated by NHA-LPS which was non-significantly different with the positive control group V. Biofilm thickness in group IV treated with NHA-small particle size (SPS) recorded high biofilm thickness followed by group III. Interestingly, group III showed greater killing effect against mature biofilm which is slightly higher than the positive control group V. In group III, surface topography revealed very smooth enamel surface with closed pores. Accordingly, NHA-LPS suspension had antiadhesive, antibacterial, and antibiofilm effect against cariogenic S. mutans representing a promising possibility to be recommended for safe effective remineralization.

Objective: to evaluate the efficacy of non-invasive procedures through biomimetic mineralization of a fluoride, bioactive glass with and without fluoride and self-organizing peptides in the treatment of dentinal hypersensitivity due to early non-carious cervical lesions. Materials and methods:Twenty-eight patients with self-reported history of dentin hypersensitivity were evaluated sequentially for evidence of erosion, abrasion or gingival recession at facial cervical region.Patients were randomly distributed into four treatment groups of seven patients each according to the type of the treatment (group I: Elmex Gele'e, group II: BioMin™ F, group III: BioMin™ C group IV: Curodont TM D'senz).The teeth were subjected to five follow up periods (baseline, after 3,6,9 and 12 weeks) and assessed in response to evaporative air-blast stimulus utilizing Schiff Sensitivity Scale and Visual Analogue Scale.Electrical test was performed utilizing electrical pulp tester.The extent of tubule occlusion was examined under scanning electron microscope using negative replica of randomly selected patients.Results: All the tested groups showed different degrees of relieving dentinal hypersensitivity symptoms with significant difference throughout the different assessment periods.The difference between the studied groups was statistically significant.Under SEM, group II, III and IV showed complete tubule occlusion.However, group I showed partial tubule occlusion.Conclusions: Elmex® gelée, BioMin™ F, BioMin™ C and Curodont™ D'senz were effective to manage dentin hypersensitivity related to early non-carious cervical lesions based on the biomimetic mineralization concept that has focused on permanent management of dentin hypersensitivity.

ObjectiveThe purpose of this in-vitro study was to quantitatively evaluate the remineralization potential of chicken egg shell powder (CESP) solution on early demineralized enamel lesions and the resistance of the treated enamel surfaces to further acidic challenges.Patients and methodsA 3 × 3 mm enamel windows were done on the buccal surface of 36 sound, freshly extracted human first premolars for orthodontic purposes. Specimens were randomly divided according to the period of treatment with CESP solution into two equal groups (18 each). Ten specimens from each group were examined throughout the steps of the study with energy dispersive radiograph analysis for their calcium (Ca) and phosphorus (P) content. Enamel surface topography of the remaining eight specimens was examined under scanning electron microscope (two specimens for each step). Initial enamel lesions were created by immersion of the specimens separately in 10 ml of a demineralizing solution at 37°C for 96 h. For treatment specimens of group I were individually immersed in CESP solution once daily for 12 min and kept in artificial saliva at 37°C for the rest of the day, for 7 consecutive days. Specimens of group II were treated twice daily with a 12 h interval between both immersions following the cycle mentioned before. The treated specimens were then subjected to a 5 days' pH cycling regimen consisting of demineralization for 3 h, and remineralization for 21 h. The collected data were tabulated and statistically analyzed.ResultsGroup II recorded a statistically significant higher Ca value and Ca/P ratio after treatment and pH cycling compared to group I (P = 0.000) as detected by independent t test. Regarding the P content value recorded after treatment it was significantly lower for group II versus group I (P = 0.000). While no significant difference was found between both groups after pH cycling (P = 0.755). Scanning electron microscope findings were found supporting the previous results.Clinical significanceCESP solution provided a significant remineralization potential of the human initially demineralized enamel lesions.

ObjectiveThe purpose of this study was to evaluate effect of frequent bleaching regimens on the color stability of enamel.Materials and methodsThirty sound bovine incisor teeth were used representing three main groups. Group 1 (control group) was not subjected to any bleaching procedure. Group 2 was bleached with 15% carbamide peroxide (CP) gel; Opalescence PF. Group 3 was bleached with chemical-activated hydrogen peroxide bleaching gel (Opalescence Boost PF 40%). All groups were subdivided into two subgroups A and B according to the storage solution either artificial saliva or staining cycle containing three staining solutions. This was performed for 30 days, with an immersion time 6 h/day resembling a period of 24-month clinical use. All the procedures were performed twice with 2 months interval where the teeth were stored in daily renewable artificial saliva at room temperature (23 ± 1°C). Spectrophotometer was used to measure the color change of the specimens. One-way analysis of variance test and pairwise test were used, at a 95% level of significance.ResultsA statistical significant rebound was recorded after first bleaching regimen (P = 0.009 and 0.032) and after second bleaching regimen (P = 0.016 and 0.013) for groups 2 and 3, respectively. A statistical significant difference was recorded between the (ΔE) after staining for first vs second time in the tested groups (1, 2, and 3) (P = 0.000, 0.047, and 0.002), respectively. Regarding specimen preserved in saliva, no statistical significant difference between the tested groups (P = 0.074, 0.793, and 0.756), respectively.ConclusionThe hypothesis of this study was rejected as the color was proved to be unstable after frequent bleaching regimens. There was an increase in color change due to exposure to staining cycles and/or artificial saliva.

ObjectiveThis study was carried out to investigate the nanoleakage of different composite restoration systems (composite materials and its recommended adhesives).Patients and methodsThirty intact, noncarious human premolars were selected. Root apices of all teeth were sealed with wax. For each tooth, the roots were inserted into self-curing resin mold, with the long axis perpendicular to the acrylic resin base. Standardized class V cavities were prepared above the cemento-enamel junction by 1 mm, on the buccal surfaces of the teeth. The prepared teeth were divided randomly into three equal groups (10 each) according to restorative systems used: group 1: nanohybrid composite system, group 2: bulk-fill composite system, and group 3: flowable composite system. Each group was equally divided into two subgroups (five each) according to the thermal and load cycling treatments (A and B). All specimens were examined at the occlusal margins and cervical margins (divisions 1 and 2). All specimens were coated with two layers of nail varnish except for 1 mm, around the restoration margins and immersed in a 50% (w/v), sectioned in bucco-lingual direction and processed for scanning electron microscopy and energy dispersive analysis radiograph.ResultsThe bulk-fill composite system (group 2) recorded the higher silver weight percentage mean value followed by nanohybrid composite system (group 1) while the flowable composite system (group 3) recorded the lowest silver weight percentage mean value in both cases whether the restorations were thermal and load cycled or not. However, a statistically significant difference was recorded in the three tested groups when subgroup A was compared to subgroup B in each group. Moreover, the results indicated that the mean value of nanoleakage at the cervical margins (division 2) in all groups (1, 2, and 3) and subgroups (A and B) recorded a higher significant nanoleakage than the occlusal margins (division 1) except group 2B which recorded no significant difference with a P value of 0.147.ConclusionThe flowable composite system recorded the lowest silver weight percentage mean values. Thermal and mechanical stresses increase nanoleakage significantly.

ObjectivesEvaluate the color regression, postoperative sensitivity, and patient's satisfaction after bleaching with different regimens over a period of 1 year clinical service.Participants and methodsTwenty highly educated adolescents (age range: 18–25 years) seeking for better esthetics were enrolled into the study. Their teeth shade was A3 or darker. Participants were enrolled in a split mouth study design divided into four groups according to bleaching materials and/or desensitizer used. Groupgroup I: right mandibular anterior teeth will receive over-the-counter (OTC) bleaching material followed by desensitizer application. Group II: left mandibular anterior teeth will receive OTC bleaching material. Group III: right maxillary anterior teeth will receive in-office bleaching material followed by desensitizer usage. Group IV: left maxillary anterior teeth will receive in-office bleaching material. The color change, teeth sensitivity and patient's satisfaction were recorded along the evaluation periods at baseline, before any treatment, directly after bleaching, and in 3 months intervals for a year postoperatively.ResultsOne-way repeated measure analysis of variance test was performed to investigate the effect of time on the color change for each tested group. A highly significant difference was recorded regarding the color change for all tested groups with P value equals 0.000. Considerable postoperative sensitivity was recorded in 13.3, 36.7, 1.7, and 30% for group I, II, III, IV, respectively. Treatments were generally well-tolerated, a percentage of zero (n = 0) patient terminated the treatment prematurely. There was no postoperative hypersensitivity at any tooth after 3, 6, 9, and 12 months evaluation periods. Additionally, after 1 year evaluation periods, five (25%) patients recorded moderately satisfaction, nine (45%) patients were satisfied, and six (30%) patients were extremely satisfied with their teeth color.Conclusion and recommendationsThe degree of whitening is superior in the power bleaching compared with the OTC bleaching technique. The higher incidence of tooth sensitivity was found in teeth bleached using OTC technique. It is recommended that over-the-counter products should be used under strict manufacturer's directions.

Aim and objective: The aim of this study was to evaluate the effectiveness of three different techniques on treating induced incipient enamel demineralized lesions using digital subtraction radiography (DSR).Materials and methods: Fifteen human sound premolars were used in this study. White spot lesions (WSLs) were established on the buccal, palatal, or lingual surfaces of the samples. Samples were then randomly divided into three equal groups (n = 10). Samples in group A were treated with ACT anticavity fluoride mouthrinse, those of group B were treated with MI paste Plus cream, while those of group C were treated with ICON resin infiltrant. All groups were exposed to a pH cycling, for 30 days excluding weekends where samples were stored in distilled water, during which the treatment regimen was applied. All groups were then exposed to a secondary demineralization attack. Standardized periapical radiographs were taken at four times interval; before any treatment which is considered as the baseline, after WSL creation, after material application, and lastly, after the second demineralization attack. DSR was used for the assessment of WSLs progression.Results: Statistical analysis was conducted using one-way analysis of variance, Tukey's and paired t-tests (P < 0.05). Comparing the three methods of treatment; DSR evaluation showed that there was a statistically significant difference between the three groups, where group B had the best effect on decreasing the WSLs. Also, a significant difference was found among the three groups after the secondary demineralization attack, where group A was found to be the most resistant group.Results: ACT mouthrinse, MI paste Plus, and ICON resin infiltrant are effective materials in treating the incipient lesions and in resisting caries recurrence.

ObjectiveThe aim of this study was to evaluate the effect of different desensitizing agents, oxalate desensitizer and I-Bond, on the shear bond strength of composite resin to dentin surface.Materials and methodsOcclusal surfaces of 80 sound human molars extracted were trimmed to expose a flat dentin surface. Each prepared sample was inserted in a metallic mold, which was designed with a Teflon mold having a hole (4 mm diameter ×3 mm height) for filling the restorative material. The samples were divided into four groups (20 each): group I (the control group), in which Adper Single Bond 2 and composite were applied; group II, in which oxalate desensitizer (D/Sense Crystal) was applied followed by Adper Single Bond 2 and composite; group III, in which oxalate desensitizer was applied, followed by re-etching and application of Adper Single Bond 2 and composite; and group IV, in which I-Bond and composite were used. All samples were thermocycled for 500 cycles (5–55°C). The samples in each group were subdivided into two subgroups (10 each) (A and B) according to storage time (24 h or 6 months, respectively). Shear bond strength of eight samples from each subgroup was measured. Debonded surfaces were examined under a stereomicroscope at magnification ×40 to determine the mode of failure. The remaining two samples were prepared to be examined under scanning electron microscope to reveal the resin penetration.ResultsGroup I (the control group) recorded the highest shear bond strength values (11.838 ± 3.141 and 6.842 ± 3.912, respectively) in the two subgroups, followed by group IV (6.695 ± 3.164 and 6.217 ± 3.276, respectively) and group III (7.707 ± 3.845 and 3.681 ± 1.743, respectively), whereas the lowest values were found in group II (6.347 ± 3.208 and 3.240 ± 1.804, respectively). The incidence of adhesive mode of failure was higher in all tested groups, followed by mixed mode. Scanning electron microscope results confirmed the obtained statistical analysis of collected data.Clinical significanceBoth desensitizing agents and storage time had a negative significant effect on the shear bond strength of composite restoration to dentin surface.

Aim: To evaluate the remineralization potential presented by surface metrology, of two remineralizing agents: CPP-ACPF (MI paste plus) and fluoride containing mouthwash (Aquafresh extra care mouthwash) on the induced acid erosion bovine enamel. Materials and Methods: Ten freshly extracted bovine permanent incisors were selected. The incisal one third of their crowns were sectioned by a slow speed diamond disc. The labial surface of each sample was examined under atomic force microscope (AFM) to record its surface roughness (Ra values). All samples were then demineralized by citric acid solution and reexamined under AFM .The demineralized samples were randomly divided into two equal groups I and II (5 samples each), according to the remineralization regimen used; samples in group I were treated with MI Paste plus while those in group II were treated with Aquafresh extra care mouthwash. All samples were reexamined under AFM to evaluate Ra values. Results: Acid erosion showed an increase of surface roughness value (72.85 nm) compared to that recorded for the original surface (38.45 nm). After remineralization, there was a decrease of the mean Ra value in group I (52.78nm) and group II (59.54 nm). ANOVA test revealed a statistical significant difference among base line data (original enamel surface), demineralized and remineralized samples in both groups. Scheffe`s test revealed a statistical significant difference between mean Ra value of demineralized samples versus that of base line data as well as that of remineralized samples in both groups. Conclusion: The tested CPP-ACP based compound offered a significant remineralization potential of initially eroded bovine enamel compared to the tested fluoride containing mouthwash as detected by reduced surface roughness

To evaluate the shear bond strength of a new generation of glass ionomer (Glass Carbomer) to enamel versus a nano-filled resin-modified glass ionomer (ketac Nano) and a conventional type after different storage periods. Crowns of 36 sound and freshly extracted human permanent molars were sectioned mesiodistally into two halves. The convex buccal or lingual surface was gently ground with water cooled 200-, 400-, and 600-grit silicon carbide abrasive papers successively to obtain flat enamel surfaces. The prepared specimens (n = 72) were divided into three main groups (24 each): I (Ionofil Molar), II (Ketac Nano) III (Glass Carbomer). The specimens in each group were subdivided into three subgroups A, B & C according to the storage period in artificial saliva. Shear bond strength between enamel surface and the bonded material was measured using a universal testing machine at a cross head speed of 0.5 mm/min. All the debonded interfaces were examined under both binocular stereo microscope at 40× and SEM at 200× to determine the mode of failure. Ketac Nano recorded the highest shear bond strength values (9.30 ± 0.67, 12.07 ± 0.76, 6.7 ± 0.73) followed by Ionofil Molar, recording (5.25 ± 0.62, 7.82 ± 1.42, 5.91 ± 0.87) while the lowest values were found in Glass Carbomer specimens, recording (2.17 ± 0.63, 6.66 ± 0.68, 5.72 ± 0.79). There was a highly significant difference in shear bond strength values among the three different storage periods in all the tested materials (P < 0.0001). A positive correlation was recorded (R = 9.3) between the adhesive mode of failure and shear bond strength while a negative correlation was recorded (R = 4.5) between the cohesive mode of failure and shear bond strength using Spearman's correlation test. Storage time was a factor which significantly influenced both shear bond strength and mode of failure especially in Glass Carbomer specimens.

To evaluate the effect of different root canal irrigating regimens on the push-out bond strength of RealSeal root canal obturation system. 16 mm ± 1 of roots of 70 freshly extracted single rooted human teeth were obtained and divided randomly into seven groups (n = 10) according to irrigation regimens throughout root canal preparation and final rinse: 1(DW–DW), 2(NaOCl–NaOCl), 3(NaOCl–MTAD), 4(NaOCl–EDTA), 5(CHX–CHX), 6(CHX–MTAD), 7(CHX–EDTA). All root canals of all groups were prepared using K3 root canal preparation system up to size #40/0.06 taper and filled using RealSeal Root canal obturation system. Two-millimeter thick horizontal sections from the coronal, middle and apical thirds of each root were sliced for the push-out bond strength measurement. In cervical sections the highest push-out bond strength value was recorded for NaOCl–MTAD (4.074 ± 2.524) followed by CHX–MTAD (3.795 ± 1.935), CHX–EDTA (2.659 ± 0.587), NaOCl–EDTA (2.404 ± 1.166), CHX–CHX (1.905 ± 0.573), NaOCl–NaOCl (1.690 ± 0.427) and the least value was recorded for DW–DW (0.791 ± 0.381) with statistical significant difference between groups (P < 0.001). In middle sections the highest value was recorded for CHX–MTAD (3.801 ± 0.186) followed by CHXEDTA (3.222 ± 0.148), NaOCl–MTAD (3.119 ± 0.306), NaOCl–EDTA (2.066 ± 0.805), CHX–CHX (1.624 ± 0.724), NaOCl–NaOCl (1.350 ± 0.539) while the lowest value was recorded for DW–DW (0.684 ± 0.382) with no statistical significant difference among groups (P = 0.067). In apical sections the highest value was recorded for groups NaOCl–MTAD (2.654 ± 0.733), CHX–MTAD (2.020 ± 1.5522), CHX–EDTA (1.878 ± 0.808), NaOCl–EDTA (1.763 ± 0.068), NaOCl–NaOCl (1.260 ± 0.846), CHX–CHX (1.175 ± 0.298) and the lowest value was recorded for DW–DW (0.631 ± 0.152) with statistical significant difference between groups (P = 0.006). Whenever root canal obturation using RealSeal is decided, it is preferred to use NaOCl solution throughout instrumentation in association with MTAD as a final irrigant after instrumentation to obtain a the highest push-out bond strength to root canal dentin specially at the coronal sections that showed higher bond strength than middle and apical sections.

The aim of this study was to investigate the cytotoxic effects of elements released from gold and CAD-CAM fabricated ceramic crowns. According to the determination of elements released from gold alloy1 and CAD-CAM fabricated ceramic2 crowns into saliva of fixed prosthodontic patients by using inductively coupled plasma mass spectroscopy, similar amounts of elements (Au, Pd, Ag, Zn, Cu, Al, Si) were prepared as salt solutions. A well without any tested element was used as a negative control. These salt solutions were tested for cytotoxicity by culturing mouse L-929 fibroblasts for a 7-day period of incubation. Then, the percentage of viable cells for each element was measured using trypan blue exclusion assay. The data (n = 5) were statistically analyzed by ANOVA/Tukey test (p < 0.05). The lowest percentage of viable cells (Mean ± SD) was evident with Zn and Cu released from gold crowns indicating that they are the most toxic elements. Ag was found to be intermediate in cytotoxic effect. Au, Pd, Al, Si were found to be the least cytotoxic elements. Zn and Cu released from gold alloy full crowns showed evidence of prominent cytotoxic effect on fibroblasts cell cultures.

To report one year clinical performance of two types of composite (silorane based versus methacrylate based) in class I preparations. A total of 15 patients (9 female and 6 male aged 20–40 years) participated in this study where 30 class I cavities were restored with either Filtek silorane (P90) or a methacrylate based composite (Tetric EvoCeram) representing two main groups (n = 15). Each patient received at least one pair of restoration. The cavity design was restricted to eliminate primary carious lesions. All restorations were subjected to a clinical follow up schedule representing (baseline, 6 months and 12 months) during which, two investigators rated the restorations according to the modified USPHS criteria evaluating marginal integrity, surface roughness, marginal discoloration, color match, anatomic form (wear), recurrent caries, retention of restoration and postoperative sensitivity. The data were collected, tabulated and statistically analyzed at a level of significance (P ≤ 0.05) using Friedman test, Chi-square and Fisher's exact test. Regarding the clinical performance of the tested materials there was no statistical significant difference among the different recall periods in all the tested criteria in both materials and no statistical significant difference between group I versus group II at all follow up periods (P > 0.05). In addition Kappa test revealed a statistical agreement between marginal discoloration as well as color match and both marginal integrity and surface roughness (P < 0.05). 1-The clinical performance of silorane based composite (Filtek P90) was deemed acceptable after one year; with no obvious advantage compared to methacrylate based composite. 2-The low shrinkage associated with (Filtek P90) may not be a determinant factor for its high clinical performance.

To evaluate the clinical performance of two nano-hybrid giomer restorative composites; Beautifil II and Beautifil Flow Plus F00 with FL-Bond II adhesive system in class I posterior restorations during three-year period. Twenty patients joined this study with age ranging from 20 to 35 years. Each patient has to present two permanent upper or lower molars of the same side requiring new class I restorations of primary carious lesions to be restored by both tested materials. Two clinicians examined the twenty patients with 40 restorations (20 for each restorative material) clinically using Modified USPHS/Cvar & Ryge Criteria for direct restoration for a period of three years with an examination interval 6 months. Data was collected and statistically analyzed using SPSS version 18. Friedman's test showed no significant changes to all modified USPHS criteria for each material during the three-year evaluation period. Fisher's exact test showed no significant changes between materials in postoperative sensitivity, recurrence of caries or retention of restoration. The significant changes recorded were after three years period follow up between the two materials; Beautifil flow plus F00 has significantly better marginal adaptation (P < 0.01), marginal discoloration (P = 0.01), surface roughness (P = 0.01) and surface morphology (P < 0.01) versus Beautifil II. Beautifil Flow Plus F00 (zero flow) restorative material achieved clinically better significant acceptable results than Beautiful II after three years of service in conservative class I cavities.

The aim of the present study was to test the following hypotheses: 1. In-vitro repeated bleaching by low hydrogen peroxide (HP) regimens –at 2-month interval- will affect enamel hardness and composition. 2. The use of MI Paste Plus, GC Co. (MIPP) during bleaching treatments will reduce these possible enamel changes. Two 14-day bleaching regimens; 1 h/day of 10% carbamide peroxide (CP) gel; Opalescence PF (OpPF) and 30 min/day of 9.5% HP strips; Crest Whitestrips Advanced Seal (CWAS) were evaluated. Each bleaching regimen was applied on enamel three times, separated by 2 months of artificial saliva with or without MIPP regimen. Surface treatment groups (n = 10/group) included: (1) Artificial saliva (control) (2) OpPF, (3) CWAS (4) OpPF-MIPP, and (5) CWAS-MIPP. Vicker Hardness (VH) was repeatedly measured for all groups; at baseline and after 2, 12 and 22 weeks (after each bleaching treatment). The final enamel surface of each group was chemically analyzed using Fourier Transform Infrared Spectroscopy (FTIR). The median VHs (Kg/mm2) were: (1) 310, 312, 330, 343; (2) 299, 272, 283, 264; (3) 320, 277, 271, 255; (4) 300, 311, 304, 316, and (5) 305, 315, 309, 320, respectively. Friedman repeated measures ANOVA on ranks (Dunnett method) indicated that enamel VH was significantly reduced after the third OpPF treatment and after the second and third CWAS treatments. Within OpPF-TMP and CWAS-TMP groups, no significant differences were found among VHs measured at different time intervals (p < 0.05). FTIR of the final enamel surfaces revealed decreased phosphate group intensity; enamel mineral content, for all groups except OpPF-MIPP group where its intensity increased. Repeating of low HP bleaching regimens – at short intervals – may reduce enamel hardness and mineral content. Daily over-night use of MIPP may preserve enamel hardness and mineral content only if the OpPF regimen is used.