Effect of different storage media on elemental analysis and microhardness of cervical cavity margins restored with a bioactive material.

Objectives: This study aimed to investigate the elemental analysis and microhardness of a bioactive material (Activa) and marginal tooth structure after storage in different media. Materials and Methods: Fifteen teeth received cervical restorations with occlusal enamel and gingival dentin margins using the tested material bonded with a universal adhesive, 5 of them on the 4 axial surfaces and the other 10 on only the 2 proximal surfaces. The first 5 teeth were sectioned into 4 restorations each, then stored in 4 different media; deionized water, Dulbecco's phosphate buffered saline (DPBS), Tris buffer, and saliva. The storage period for deionized water was 24 hours while it was 3 months for the other media. Each part was analyzed by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) analysis for different substrates/distances and the wt% of calcium, phosphorus, silica, and fluoride were calculated. The other 10 teeth were sectioned across the restoration, stored in either Tris buffer or saliva for 24 hours or 3 months, and were evaluated for microhardness of different substrates/areas. Data were analyzed using analysis of variance and Tukey's post hoc test. Results: Enamel and dentin interfaces in the DPBS group exhibited a significant increase in calcium and phosphorus wt%. Both silica and fluoride significantly increased in tooth structure up to a distance of 75 µm in the 3-month-media groups than the immediate group. Storage media did not affect the microhardness values. Conclusions: SEM-EDS analysis suggests an ion movement between Activa and tooth structure through a universal adhesive while stored in DPBS.

Clinical performance of different bulk-fill composite resin systems in class II cavities: A 2-year randomized clinical trial.

OBJECTIVES: This study evaluated the clinical performance of bulk-fill resin composite systems with different viscosities in class II cavities. MATERIALS AND METHODS: A total of 80 class II restorations were performed with a single operator in 50 patients using four different bulk-fill resin composite materials: Filtek™ Bulk Fill, Heated Filtek™ Bulk Fill, G-ænial™ BULK Injectable, and SonicFill3. A double-blinded randomized clinical trial was designed to evaluate the two-year clinical performance of the four bulk-fill composite resins using modified FDI criteria. Data were analyzed descriptively. Level of significance was set at 0.05. Differences between groups were tested using Wilcoxon-signed-rank and Mann-Whitney-U test as nonparametric tests. RESULTS: Data were analyzed using Kruskal-Wallis, Mann-Whitney U, and Wilcoxon signed rank tests (p < 0.05). Eighty restorations were available for evaluation, with a survival function of 100%. No statistically significant differences were observed between the four groups regarding assessing esthetic, functional, and biological properties during different follow-up periods. CONCLUSIONS: After 2 years of clinical follow-up, the bulk-fill composite systems with different viscosities seem to be esthetically, functionally, and biologically acceptable, with a promising clinical performance in class II cavities.

3-year randomized clinical trial to evaluate the performance of posterior composite restorations lined with ion-releasing materials.

To evaluate the impact of using ion-releasing liners on the 3-year clinical performance of posterior resin composite restorations after selective caries excavation with polymer burs. 20 patients were enrolled in this trial. Each patient had two deep carious lesions, one on each side of the mouth. After selective caries removal using polymer bur (PolyBur P1, Komet, Brasseler GmbH Co. KG, Lemgo, Germany), cavities were lined with bioactive ionic resin composite (Activa Bioactive Base/Liner, Pulpdent, Watertown, MA, USA) or resin-modified glass ionomer liner (Riva Light Cure, SDI, Bayswater, Victoria, Australia). All cavities were then restored with nanofilled resin composite (Filtek Z350XT, 3M Oral Care, St. Paul, MN, USA). All the tested materials were placed according to the manufacturers' instructions. Clinical evaluation was accomplished using World Dental Federation (FDI) criteria at baseline and after 6 months, 1, 2, and 3 years. Data were analyzed using Mann-whitney U and Friedman tests (p < 0.05). The success rates were 100% for all resin composite restorations either lined with ion-releasing resin composite or resin-modified glass ionomer liner. Mann-whitney U test revealed that there were no statistically significant differences between both ion-releasing lining material groups for all criteria during the follow-up periods (p > 0.05). Resin composite restorations showed acceptable clinical performance over 3 years either lined with bioactive ionic or resin-modified glass ionomer liners after selective caries excavation preserving pulp vitality. After the 3-year follow-up period, Activa Bioactive and Riva Light Cure liners were clinically effective and they exhibited with the overlying composite restorations successful clinical performance.Trial registration number: NCT05470959. Date of registration: 22/7/2022. Retrospectively registered.

Clinical performance comparison between lithium disilicate and hybrid resin nano-ceramic CAD/CAM onlay restorations: a two-year randomized clinical split-mouth study.

A total of 20 lithium disilicate glass-ceramics (IPS e.max CAD, Ivoclar Vivadent) and 20 resin nano-ceramic (Voco Grandio Blocks) onlay restorations were performed in 20 patients using a split-mouth design to compare the two-year clinical performance of lithium disilicate and resin nano-ceramic onlay restorations. Both restorations were evaluated at baseline, one-year, and two-year clinical follow-ups based on the modified United States Public Health Service (USPHS) criteria. Chi-square and Fisher's exact tests showed no statistically significant difference between Voco Grandio and IPS e.max ceramic restorations for all evaluated parameters during the different follow-up periods (p > 0.05). Cochrane's and MC-Nemar's tests indicated statistically significant differences regarding color match within the Voco Grandio group. They also indicated statistically significant differences in marginal discoloration, marginal adaptation, surface texture, and postoperative hypersensitivity within both ceramic material groups (p < 0.05). Kaplan-Meier curve indicated that the survival rate of both ceramic materials was 90%. After two years of clinical service, IPS e.max CAD and Voco Grandio onlay restorations exhibited similar clinical performance.

Impact of corticosteroid administration on the response of exposed dental pulp to capping with bioactive cements-experimental study on mongrel dogs.

BACKGROUND: Corticosteroids are commonly used as a treatment for a variety of pathological conditions, however, systemic corticosteroid administration has adverse effects including impaired immune response and wound healing. Such complications may affect pulp healing after direct pulp capping. The current study evaluated the influence of corticosteroids on the healing ability of exposed dogs' dental pulps after direct pulp capping (DPC) with bioactive materials. METHODS: Ten healthy male dogs were assigned randomly into two groups, 5 dogs each: group I represent the control group which did not receive any medication, and group II was given corticosteroid for 45 days before DPC and till the dogs were euthanized (n = 75 teeth for each group). Following mechanical exposure, the pulps were randomly capped with either Ca(OH)2, MTA, or Biodentine. The pulpal tissues' reaction to the capping materials was evaluated 65 days postoperatively according to the following parameters: calcific bridge formation, pulpal inflammation, pulp necrosis, and bacterial infiltration. RESULTS: The corticosteroid-treated group revealed no significant difference compared to the control group concerning the pulp healing response (P > 0.05). Both Biodentine and MTA-treated specimens revealed significant differences with Ca(OH)2-treated specimens (P < 0.05) which displayed a superior positive effect of both MTA and Biodentine to Ca(OH)2 regarding all the parameters. CONCLUSIONS: Direct pulp capping technique whenever indicated in subjects treated with corticosteroid immunosuppressive drugs like prednisone performed well in aseptic conditions especially when capped with bioactive materials.

Effect of shelf-storage temperature on degree of conversion and microhardness of composite restorative materials.

BACKGROUND: The pre-cure temperature is considered an important parameter that affects the polymerization kinetics and the properties of composite restoration. As dissension exists about the effect of storing composite restorative materials in refrigerator, this study aimed to assess the effect of shelf-storage temperature on degree of conversion (DC) and microhardness of three composite restorative materials with different matrix systems. METHODS: Three commercially-available composite restorative materials were used in this study; an Ormocer-based composite (Admira Fusion, Voco GmbH), a nanoceramic composite, (Ceram.X SphereTEC One, Dentsply Sirona GmbH), and a nanohybrid composite (Tetric N-Ceram, Ivoclar Vivadent AG). Regarding DC and microhardness tests, 60 disc-shaped composite specimens for each test were randomly divided into 3 groups (n = 20) according to the restorative material used. Each group was divided into 2 subgroups (n = 10) according to the composite storage temperature; stored at room temperature or stored in the refrigerator at 4°-5 °C. DC was evaluated using a Fourier-transform infrared spectrometer coupled to an attenuated total reflectance accessory. Microhardness was evaluated using micro-Vickers hardness tester under a load of 50 g with a dwell time of 10 s. The results were analyzed by ANOVA, post-hoc LSD, and independent t-tests at a significance level of p < 0.05. RESULTS: Regarding DC test all groups showed statistically significant differences at both storage temperature. The Ormocer-based composite had the highest mean values. There was a statistically significant difference between all room-stored groups and their corresponding groups stored at refrigerator (p < 0.05). For microhardness test, all groups exhibited also statistically significant differences at both storage temperatures with the Ormocer-based composite having the highest mean values. A statistically significant difference between both room-stored and refrigerator-stored groups has been observed also (p < 0.05). CONCLUSIONS: Refrigeration of resin-composite might have a deleterious effect on DC and microhardness of the tested composite restorative materials with different matrix systems. Moreover, the differences in the formulations of composite matrix have a potential impact on DC and microhardness.

Five-year randomized clinical trial to evaluate the clinical performance of high-viscosity glass ionomer restorative systems in small class II restorations.

OBJECTIVE: Evaluate and compare the 5-year clinical performance of three high-viscosity glass ionomer restorative materials in small class II restorations. MATERIALS AND METHODS: Forty patients, each with four class II restorations, were enrolled in this trial. A total of 160 restorations were placed, 25% for each material, as follows: three high-viscosity conventional glass ionomer restorative systems (Ketac Universal Aplicap, EQUIA Forte and Riva Self Cure HV) and a microhybrid resin composite system (Filtek Z250). Clinical evaluation was performed at baseline and after 1, 3, and 5 years by two independent examiners using FDI criteria. Epoxy resin replicas were observed under scanning electron microscope (SEM) to examine surface characteristics. Data were analyzed with Kruskal-Wallis, Mann-Whitney U, Friedman, and Wilcoxon signed-rank tests (p < 0.05). RESULTS: The success rates were 100% for resin composite, 97.4% for Ketac Universal, and 94.9% for both EQUIA Forte and Riva HV restorations. Statistically significant differences were observed between all groups in terms of surface luster and color match criteria (p < 0.05). Statistically significant changes were found over time for all criteria except for fracture of material, postoperative hypersensitivity, recurrence of caries, tooth integrity, periodontal response, adjacent mucosa, and oral health criteria (p > 0.05). SEM evaluations were in accordance with the clinical findings. CONCLUSIONS: Although drawbacks in surface luster and color match appeared over the 5-year evaluation period, the three high-viscosity glass ionomer restorative materials provided successful clinical performance in small to medium sized class II cavities compared to microhybrid resin composite. CLINICAL SIGNIFICANCE: Glass ionomer restorations exhibited clinical performance similar to that of microhybrid resin composite restorations in small class II cavities subsequent to 5-year evaluation.

Microshear Bond Strength of Bioactive Materials to Dentin and Resin Composite.

OBJECTIVES: The aim of this study was to comparatively evaluate microshear bond strength (µSBS) of bioactive ionic resin composite and resin-modified glass ionomer liner (RMGI) to dentin and resin composite. MATERIALS AND METHODS: The enamel of 11 posterior molar teeth was removed to expose dentin and then placed in acrylic blocks. Each specimen received three microcylindrical Tygon tubes filled with bioactive ionic resin composite (Activa Bioactive base/liner (PULPDENT: , MA, USA)), RMGI (Riva light cure SDI LTD, Bayswater, Australia), and resin composite (Filtek Z350xt, MN, USA). Composite discs (n = 11) were fabricated from nanofilled resin composite (Filtek Z350xt) and then fixed in acrylic blocks. Each specimen received two microcylindrical Tygon tubes filled with Activa Bioactive base/liner and Riva RMGI. All specimens were mounted individually to universal testing machine for µSBS test. Failure modes were analyzed using stereomicroscope and scanning electron microscope. RESULTS: Filtek Z350xt nanofilled resin composite showed the highest µSBS values. No statistical significant difference was found between Activa Bioactive and Riva RMGI (p > 0.05). CONCLUSION: Bioactive ionic resin composite liner exhibited similar bond strength as RMGI to dentin and resin composite.

Color stability and surface roughness of ormocer- versus methacrylate-based single shade composite in anterior restoration.

BACKGROUND: The blending ability of universal shade composites and their stability in the oral environment are of great concern in restoring anterior teeth. This study aims to evaluate and compare the color stability and surface roughness of two single-shade composite restorations, ormocer-based composite (OBC) and methacrylate resin-based composite (RBC), after storing them in different staining media. MATERIALS AND METHODS: In this study, two universal shade composite restorative materials were tested: a nanohybrid OBC (Admira fusion X-tra, Voco) and a supra-nanofilled RBC (Omnichroma, Toukyama). In total, 60 cylindrical centralized cavities (diameter: 5 mm, depth: 2 mm) were prepared in sound extracted-human central incisors and divided into two equal groups according to the restorative material used (n = 30). According to the storage media, the teeth of each group were divided into three subgroups (n = 10): artificial saliva, black tea, and cola. The restoration color was evaluated for all teeth at baseline and after four weeks of storage. The color stability (∆E) was measured using a reflective spectrophotometer (X-Rite, model RM200QC, Neu-Isenburg, Germany). The surface roughness (Ra) was evaluated using three-dimensional optical profilometry (Wyko, Model NT 1100, Veeco, Tucson, USA). Additionally, the extracted data were analyzed using two-way analysis of variance (ANOVA), one-way ANOVA and Student's t-test. RESULTS: In the baseline evaluation, there were no statistically significant differences with respect to color matching or surface roughness results between the two studied restorative materials. However, the differences were statistically significant after storing them in different media. CONCLUSION: Universal composites showed satisfactory color matching with different teeth colors and accepted surface smoothness, whereas the aging procedure exerted a negative effect on their color stability and surface characteristics.

Long-term evaluation of early-enamel lesions treated with novel experimental tricalcium silicate paste: A 2-year randomized clinical trial.

OBJECTIVE: The aim of the current study is to evaluate the remineralization potential of experimental tricalcium silicate (TCS) paste in comparison with more popular remineralizing agents like silver diamine fluoride potassium iodide (SDF-KI) and casein phosphopeptide amorphous calcium phosphate (CPP-ACP) on early enamel lesions. MATERIALS AND METHODS: Forty-five patients in the age range of 15-50 years had early enamel lesions on the buccal surface of molar teeth. The patients were randomly divided into three treatment groups (SDF-KI, CPP-ACP, and TCS group) with 15 patients per group. Lesions were evaluated clinically by DIAGNOdent pen immediately and after 3,6,12, and 24 months of treatment. RESULTS: The study was completed with 45 patients and 92 teeth. Twice-daily application of CPP-ACP and TCS paste showed a significant remineralization effect on early enamel lesions after 24 months (p < 0.001). Also, annual application of SDF-KI showed a significant remineralization effect after 24 months (p < 0.001). There was a significant difference between (SDF-KI and CPP-ACP) and (SDF-KI and TCS) at the different follow-up periods 3,6,12, and 24 months (p < 0.001). Meanwhile, there was no significant difference between CPP-ACP and TCS at the mentioned follow-up periods (p > 0.05). CONCLUSION: TCS showed potential remineralization for early enamel lesions. CLINICAL RELEVANCE: Experimental TCS is a promising remineralizing agent for management of early enamel lesions.

Remineralization of early enamel lesions with a novel prepared tricalcium silicate paste.

To evaluate the remineralization potential of prepared tricalcium silicate (TCS) paste compared to silver diamine fluoride-potassium iodide (SDF-KI) and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on artificial enamel lesions. Thirty permanent sound molars were collected for the study. After cleaning, root cutting, and applying acid-resistant nail varnish, leaving a 4 × 4 mm buccal window, the teeth were subjected to demineralization process. The teeth were divided into three treatment groups (n = 10). In each group, the teeth were sectioned buccolingually to obtain two halves (30 self-control and 30 experimental halves). The self-control halves were subjected to cross-sectional microhardness (CSMH), energy-dispersive X-ray spectroscopy at 50, 100, and 150 µm from the external enamel surface, and micromorphological analysis at the superficial enamel surface. The experimental halves were subjected to the same tests after 30 days of remineralization. Three-way analysis of variance (ANOVA) outcomes showed no significant difference in CSMH after treatment among the three different groups at the different levels (p > 0.05). Meanwhile, three-way ANOVA outcomes showed a significant difference in calcium/ phosphate ratio after treatment among the three different groups at the different levels. (p < 0.05). The tricalcium silicate paste used in this study showed potential remineralization in subsurface enamel lesions.

Influence of selective immunosuppressive drug regimens on the healing of exposed dogs' dental pulp capped with a recent calcium silicate-based cement.

OBJECTIVES: In the clinical medicine, immunosuppressive drugs are used for an assortment of disorders, while their effect on the pulp healing is a controversial issue. This study evaluated the effect of different immunosuppressive drugs on the healing capacity of mechanically exposed dogs' dental pulps after direct pulp capping (DPC) with calcium silicate-based cement. MATERIALS AND METHODS: Twelve healthy male dogs were randomly allocated into four equal groups, 3 dogs each: group I allocated as a control group where no drugs were received; group П given prednisone (Pred); group III given a combination of Pred and cyclosporine A (CsA); and group IV given triple dose including Pred, CsA, and mycophenolate mofetil (MMF) for 45 days before the operative procedures and until the dogs were euthanized. In each dog, 16 class V cavities were prepared on the labial surfaces of anterior teeth. Following mechanical exposure, the pulps were capped with Biodentine, calcium silicate-based cement. The pulpal tissues response to Biodentine was assessed 65 days postoperatively. RESULTS: The pulp healing response was inferior in the Pred-CsA- and Pred-CsA-MMF-treated groups compared with the control and Pred-treated groups (P < 0.05). Non-significant difference was found between control and Pred-treated groups (P > 0.05). CONCLUSIONS: Within the limitation of this study, DPC with calcium silicate-based cement performed under strict aseptic condition for traumatically exposed dental pulp can be considered as a successful treatment option for those who receiving Pred immunosuppressive therapy. Meanwhile, DPC with those receiving a combination of Pred, CsA, and/or MMF immunosuppressive drug regimens demonstrated unfavorable results. CLINICAL RELEVANCE: Direct capping of mechanically exposed pulps with calcium silicate-based cement performed with special care for preventing infection considered a suitable strategic measure for preserving pulp vitality in patients receiving corticosteroid immunosuppressive drug.

Fracture resistance of prepared premolars restored with bonded new lab composite and all-ceramic inlay/onlay restorations: Laboratory study.

OBJECTIVES: To assess the influence of new light curing lab composite, lithium-disilicate glass-ceramic and yttrium-stabilized zirconia-based ceramic on the fracture resistance of maxillary premolars with class II inlay and onlay preparations. METHODS: Seventy sound maxillary premolars were divided randomly into seven main groups. The first group was left intact (control group). The remaining six groups were prepared with inlay and onlay cavities and restored with lab composite (SR Nexco), lithium-disilicate glass-ceramic (IPS e.max Press) and yttrium-stabilized zirconia-based ceramic (ICE Zirkon). The restorations were cemented with luting resin composite (Variolink N). All specimens were thermocycled 5000 cycles between 5°C ± 2°C and 55°C ± 2°C and were then cyclic loaded for 500 000 cycles. The specimens were subjected to a compressive load in a universal testing machine using a metal sphere until fracture occurred. The results were analyzed by 2-way ANOVA and Tukey HSD post hoc tests. The level of significance was set at P < .05. RESULTS: There were no statistically significant differences among the means of control group and the groups restored with zirconia ceramic inlays and onlays (P > .05). However, statistically significant differences were found among the means of control group and the groups restored with lab composite inlays, lab composite onlays, pressable glass ceramic inlays and pressable glass ceramic onlays (P < .05). CONCLUSIONS: The fracture resistance of prepared teeth for inlay and onlay restorations is inferior to the intact teeth when lab composite is used. Conversely, when a ceramic material being used, the prepared teeth for inlay and onlay restorations showed a comparable strength to the intact teeth especially zirconia ceramic. CLINICAL SIGNIFICANCE: Premolar teeth restored with zirconia ceramic inlays and onlays exhibited fracture resistance comparable to intact teeth.

A three-year prospective randomized study of silorane- and methacrylate-based composite restorative systems in class II restorations.

PURPOSE: To evaluate and compare the 3-year clinical performance of a silorane-based composite with that of a methacrylate-based composite in Class II restorations. MATERIALS AND METHODS: Seventy-eight patients, each with two class II restorations under occlusion, were enrolled in this study. One hundred fifty-six restorations were placed, 50% for each material: a silorane-based composite, Filtek P90/ P90 System Adhesive and a methacrylate-based resin composite, Quixfil/ Prime &Bond NT. A single operator placed all restorations according to the manufacturers' instructions. Immediately after placement, the restorations were finished/polished. Clinical evaluation was performed at baseline and at yearly intervals after placement by two other independent examiners using slightly modified USPHS criteria. The changes in the USPHS parameters during the three-year period were analyzed with the Friedman test. The baseline scores were compared with those at the recall visits using the Wilcoxon signed rank test. The level of significance was set at p < 0.05. RESULTS: All restorations were evaluated at 3 years. Post-operative sensitivity was observed in 6 patients (2 Filtek P90, 4 Quixfil) between 1 and 3 weeks. Seven failed restorations (4.5%) were observed during the follow up: 4 in the Filtek P90 (5.1%) and 3 in the Quixfil group (3.8%). This resulted in non-significantly different annual failure rates of 1.7% and 1.2%, respectively. Fracture of restoration was the main reason for failure. CONCLUSION: After 3 years, no significant difference was seen in overall clinical effectiveness between the silorane- based and methacrylate-based composite restorative systems.

Effects of phosphoric acid concentration and etching duration on enamel and dentin tissues of uremic patients receiving hemodialysis: an AFM study.

PURPOSE: Using atomic force microscopy (AFM), the purpose was to investigate the effect of phosphoric acid (H3PO4) concentration and etching duration on surface roughness (Ra) and micromorphology of enamel and dentin substrates of uremic patients receiving hemodialysis. MATERIALS AND METHODS: Sixty-three enamel and dentin slabs were prepared from 42 sound natural molars collected from uremic patients under hemodialysis and mechanically polished up to 4000-grit roughness. Nine slabs of each substrate were not etched (control group). The remaining slabs were divided into two experimental groups (n = 27) according to etchant concentration (37% or 42%). In each group, 9 specimens were etched for 15, 30, and 60 s. The surface morphology of the control and test specimens was examined by AFM operated in "contact" mode. The obtained Ra was subjected to statistical analysis. RESULTS: Statistical analysis showed that increasing the duration of acid application (irrespective of acid concentration and type of substrate) significantly increased the amount of Ra. H3PO4 at a concentration of 42% was more effective at producing Ra than was H3PO4 at 37% for all 3 application times. The Ra quantity produced by H3PO4 at 42% was time specific, with 15 s being significantly less effective than 30 or 60 s. However, 60 s was significantly better than 30. CONCLUSION: The findings of this study support the use of 42% H3PO4 for etching uremic hard tooth tissues for 60 s.

Marginal adaptation of ormocer-, silorane-, and methacrylate-based composite restorative systems bonded to dentin cavities after water storage.

OBJECTIVE: To assess the marginal adaptation of ormocer-, silorane-, and methacrylate-based composite restorative systems bonded to dentin cavities after water storage. METHOD AND MATERIALS: Cylindric dentin cavities were prepared on the buccal surfaces of 45 extracted human molars after their enamel was removed. The cavities were assigned to one of three groups (each n = 15). Each group was restored with one of three composite/adhesive systems: an ormocer-based (Admira/Admira Bond), a silorane-based (Filtek P90/P90 System Adhesive), and a methacrylate-based (Tetric Ceram/Excite). Marginal adaptation was evaluated immediately after polymerization and after 1 month and 1 year of water aging and thermocycling. Evaluation was performed under a metallographic microscope by recording frequency of gap-free restorations, width of maximum marginal gap (MG), percentage length of debonded margins relative to cavity periphery (DM), and marginal index (MI = MG x DM/100). The results were statistically analyzed with two-way ANOVA and the Tukey test at α = .05. RESULTS: None of the composite/adhesive systems examined exhibited gap-free restorations at any aging time. Marginal adaptation was significantly affected by the type of restorative/adhesive system, while water aging time had no significant effect. Silorane composite restorations exhibited the lowest MG, DM, and MI values, while methacrylate composite restorations revealed the highest values. Ormocer restorations showed intermediate values. CONCLUSION: Although all examined composite systems failed to achieve gap-free margins with dentin cavities, the silorane-based system revealed the best marginal adaptation at all aging times.

Fracture resistance of maxillary premolars with class II MOD cavities restored with Ormocer, Nanofilled, and Nanoceramic composite restorative systems.

OBJECTIVE: To assess the influence of ormocer, nanofilled, nanoceramic, and microhybrid composite restorative systems on the fracture resistance of maxillary premolars with Class II mesio-occlusodistal (MOD) cavities. METHOD AND MATERIALS: Eighty-four sound maxillary human premolars were divided into six groups of 14 teeth each. Teeth in the first group were left intact and tested as unprepared positive controls. Teeth in the remaining five groups were prepared with MOD cavities. Teeth in one of the five groups were unrestored and tested as negative control. The remaining four groups were restored with an ormocer (Admira), a nanofilled composite (Filtek Supreme), a nanoceramic composite (CeramX mono), and a microhybrid composite (Tetric Ceram). All groups were stored in water at 37°C for 24 hours and thermocycled 500 times between 5°C and 55°C. The specimens were loaded occlusally in a universal testing machine using a metal sphere that contacted only the teeth on the cuspal inclines until fracture occurred. The results were analyzed by Kruskal-Wallis and Mann-Whitney U tests. The level of significance was set at .05. RESULTS: The difference between the mean cuspal fracture resistance of the unprepared positive control teeth and those restored with ormocer, nanofill, and microhybrid composite was found to be statistically significant (P < .05). No statistically significant difference in cuspal fracture resistance was found between the unprepared positive control teeth and those teeth restored with nanoceramic composite (P > .05). CONCLUSION: Under compressive load testing, teeth with microhybrid, ormocer, and nanofilled composite restorations had lower cuspal fracture resistance than those with nanoceramic composite restorations.

Effect of 16% carbamide peroxide bleaching gel on enamel and dentin surface micromorphology and roughness of uremic patients: an atomic force microscopic study.

OBJECTIVES: To investigate the effect of 16% carbamide peroxide bleaching gel on surface micromorphology and roughness of enamel and root dentin of uremic patients receiving hemodialysis using atomic force microscopy (AFM). METHODS: A total of 20 sound molars were collected from healthy individuals (n=10) and uremic patients (n=10). The roots were separated from their crowns at the cemento-enamel junction. Dental slabs (3 mm x 2 mm x 2 mm) were obtained from the buccal surface for enamel slabs and the cervical third of the root surface for dentin slabs. Dental slabs were then flattened and serially polished up to #2500-grit roughness using silicon carbide abrasive papers. Half of the slabs obtained from healthy individuals and uremic patients were stored in artificial saliva and left without bleaching for control and comparison. The remaining half was subjected to a bleaching treatment using 16% carbamide peroxide gel (Polanight, SDI Limited) 8 h/day for 14 days and stored in artificial saliva until AFM analysis was performed. Statistical analysis of the roughness average (Ra) results was performed using one-way ANOVA and Bonferroni post hoc multiple comparisons test. RESULTS: The micromorphological observation of bleached, healthy enamel showed exaggerated prism irregularities more than non-bleached specimens, and this observation was less pronounced in bleached uremic enamel specimens with the lowest Ra. Bleached healthy dentin specimens showed protruded peritubular dentin and eroded intertubular dentin with the highest Ra compared to bleached uremic dentin. CONCLUSIONS: The negative effects of the bleaching gel on uremic tooth substrates are less dramatic and non-destructive compared to healthy substrates because uremia confers different micromorphological surface changes.

Influence of selective immunosuppressive drugs on the healing of exposed dogs' dental pulp capped with mineral trioxide aggregate.

INTRODUCTION: Immunosuppressive drugs are used in clinical medicine for a variety of disorders, but their effects on the reparative capacity of the dental pulp are unknown. This study evaluated the influence of selected immunosuppressive drugs on pulpal tissue healing after direct pulp capping of mechanically exposed dog's teeth with mineral trioxide aggregate (MTA). METHODS: Ten healthy male dogs were assigned into 5 experimental groups: a control group in which no drug was received and 4 experimental groups in which the immunosuppressive drugs prednisone, mycophenolate mofetil, sirolimus, and cyclosporine A were administered 45 days before the operative procedures and until the dogs were killed. Class V cavities were prepared on the buccal surfaces of 12 teeth in each dog. In each cavity, the pulp was exposed and capped with MTA. The pulpal tissue responses to capping material were assessed 65 days postoperatively. RESULTS: Compared with the control group, variable responses was recorded in the groups treated with mycophenolate mofetil, sirolimus, and cyclosporine A, which were characterized by moderate to severe inflammatory reactions, tissue necrosis, and total absence of hard tissue bridging. Pulpal tissue responses in the group treated with prednisone were characterized by inflammatory cell infiltration, limited tissue necrosis, as well as partial to complete hard tissue bridging. CONCLUSIONS: From these findings, it seemed evident that acceptable repair of the dentin-pulp complex, eg, wound healing with hard tissue formation after capping with MTA, is unlikely with mycophenolate mofetil, sirolimus, or cyclosporine A immunosuppressive drug therapy.

Bonding of resin composite to tooth structure of uremic patients receiving hemodialysis: shear bond strength and acid-etch patterns.

PURPOSE: To investigate the influence of uremia on the shear bond strength (SBS) of composite resin to enamel and dentin substrates with assessment of the micromorphological pattern of etched enamel and dentin surfaces using atomic force microscopy (AFM). MATERIALS AND METHODS: A total of 44 natural molars was collected from healthy individuals (n=22 molars) and uremic patients (n=22 molars). Each set of teeth was then divided into 2 equal subsets (n=11 molars) relative to the bonding substrate to be tested. In each subset, the surfaces of 7 molars were flattened and polished up to 2000-grit roughness using wet silicon carbide (SIC) abrasive papers. A three-step adhesive was used to bond Tetric Ceram composite buildups to the prepared tooth surfaces. All specimens were thermocycled before they were stressed in shear using a universal testing machine. Fractured specimens were stereomicroscopically examined to detect the mode of bond failure. In the remaining 4 molars, enamel and dentin specimens were prepared for AFM examination to assess the micromorphological patterns of acid-etched surfaces. RESULTS: The mean bond strength values in MPa to enamel (22.40 +/- 4.30) and dentin (17.97 +/- 4.65) of teeth of healthy individuals were significantly different (p < 0.001) from those to enamel (12.40 +/- 2.81) and dentin (7.83 +/- 2.05) of teeth of uremic patients. Most of the tested enamel specimens showed a mixed type of bond failure, but the adhesive type was predominant with dentin specimens. AFM examinations revealed a shallow etching pattern for uremic enamel and dentin specimens compared to those of healthy individuals. The mean roughness average (Ra) values after etching of healthy enamel (238.0 +/- 4.65) and dentin (267.0 +/- 4.79) were significantly different (p < 0.001) from those to etched uremic enamel (111.0 +/- 5.24) and dentin (143.0 +/- 2.16). CONCLUSION: Uremia adversely affects bonding of composite resin to enamel and dentin and confers an altered micromorphological etching pattern.