Polymerization efficiency of different bulk-fill resin composites cured by monowave and polywave light-curing units: a comparative study.

OBJECTIVES: The objective was to evaluate the polymerization efficiency of different bulk-fill resin-based composites cured by monowave and polywave light-curing units, by assessment of the degree of conversion and Vickers microhardness at different depths. METHOD AND MATERIALS: Two commercially available bulk-fill resin-based composites were used: Filtek One Bulk Fill Restorative (3M ESPE) and Tetric N-Ceram Bulk Fill (Ivoclar Vivadent). The light-curing units utilized were two LED light-curing units: a monowave LED light-curing unit (BlueLEX LD-105, Monitex) and a polywave LED light-curing unit (Twin Wave GT-2000, Monitex). For each test, 20 cylindrical specimens (4 mm diameter, 4 mm thickness) were prepared from each bulk-fill resin-based composite using a split Teflon mold. Ten specimens were light-cured by the monowave light-curing unit and the other ten were light-cured by the polywave light-curing unit according to the manufacturer's recommendations. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) was used to assess the degree of conversion, and a Vickers microhardness tester was used to assess Vickers microhardness. Statistical analysis was performed using three-way ANOVA and Tukey post-hoc tests (P < .05). RESULTS: The degree of conversion and Vickers microhardness in bulk-fill resin-based composites containing only camphorquinone as photoinitiator were similar when cured with either monowave or polywave light-curing units. However, bulk-fill resin-based composites containing a combination of photoinitiators exhibited significantly higher degree of conversion and Vickers microhardness when cured with a polywave light-curing unit. Although all groups showed statistically significant differences between the top and bottom surfaces regarding degree of conversion and Vickers microhardness, all of them showed bottom/top ratios > 80% regarding degree of conversion and Vickers microhardness. CONCLUSION: The polywave light-curing unit enhanced the polymerization efficiency of bulk-fill resin-based composites especially when the latter contained a combination of photoinitiators, but does not prevent the use of a monowave light-curing unit.

Evaluation of surface microhardness and gingival marginal adaptation of three different bulk-fill flowable resin composites: A comparative study.

OBJECTIVES: To evaluate surface microhardness and gingival marginal adaptation of three different bulk-fill flowable resin composites (FB-RBCs) in Class V cavities with enamel or dentin margins before and after thermocycling (TMC). MATERIALS AND METHODS: Three available FB-RBCs were used; Palfique Bulk Flow (PaBF) (Tokuyama Dental), SDR Flow+ Bulk Fill Flowable (Dentsply Sirona), and I-Flow Bulk Fill (I-Dental). Thirty discs were prepared from each type of FB-RBCs. The discs were subjected to Vickers microhardness tester machine. Class V cavities were prepared on 180 molars. Gingival margins of half the specimens were prepared above CEJ and the other half below CEJ. Cavities were restored with FB-RBCs for gingival marginal adaptation test. Two-way ANOVA was used in microhardness, while three-way ANOVA was used for marginal adaptation. RESULTS: The used materials showed statistically significant differences in microhardness and marginal adaptation. CONCLUSIONS: Regarding microhardness, PaBF showed the highest value before TMC and SDR was the highest after TMC. Regarding marginal adaptation, SDR revealed the best marginal adaptation than PaBF and I-flow, either subjected to TMC or not. CLINICAL SIGNIFICANCE: The longevity of cervical restorations depend on both the location of the cavity margin and the material used. The microfractures in resin composite surface due to low surface microhardness as well as marginal gaps seen in laboratory studies could be considered as an indicative parameter for clinical problem associated with marginal differences.

Matrix Metalloproteinases in Dental and Periodontal Tissues and Their Current Inhibitors: Developmental, Degradational and Pathological Aspects.

OBJECTIVES: This review article aims to describe some of the roles of Matrix metalloproteinases (MMPs) in enamel, dentine, dental caries, hybrid layer degradation, pulp and periodontal tissues, throwing light on their current inhibitors. The article addresses the potential of MMPs to serve as biomarkers with diagnostic and therapeutic value. DESIGN: The sections of this review discuss MMPs' involvement in developmental, remodeling, degradational and turnover aspects of dental and periodontal tissues as well as their signals in the pathogenesis, progress of different lesions and wound healing of these tissues. The literature was searched for original research articles, review articles and theses. The literature search was conducted in PubMed and MEDLINE for articles published in the last 20 years. RESULTS: 119 published papers, two textbooks and two doctoral theses were selected for preparing the current review. CONCLUSIONS: MMPs are significant proteases, of evident contribution in dental and periapical tissue development, health and disease processes, with promising potential for use as diagnostic and prognostic disease biomarkers. Continuing understanding of their role in pathogenesis and progress of different dental, periapical and periodontal lesions, as well as in dentine-pulp wound healing could be a keystone to future diagnostic and therapeutic regimens.

The Impact of Nano-Hydroxyapatite Resin Infiltrant on Enamel Remineralization: An In Vitro Study.

This study assessed the effect of nano-hydroxyapatite incorporation into resin infiltrant on the mineral content, surface tomography, and resin tag penetration of demineralized enamel. Forty specimens were exposed to a demineralized solution to form subsurface caries lesions. The lesions were treated with negative control, a resin infiltrant (ICON), ICON with 5% nano-hydroxyapatite (NHA, Sigma-Aldrich), or ICON with 10% NHA. Mineral density was assessed using microcomputed tomography scans at various stages of the experiment. Specimens were scanned by scanning electron microscope (SEM) for surface analysis and resin tag penetration. Analysis of variance was used to assess the difference among groups. Specimens treated with ICON and 5% or 10% NHA showed the most favorable mineral density regarding the percent change in mineral content (32.4% and 29.7%, respectively), compared to 8.8% in teeth treated with ICON alone and -1.8% in teeth in the control group. SEM showed that teeth treated with ICON or ICON with 5% or 10% NHA had a smooth surface. The resin penetration in all tested groups showed high-quality resin tags, regardless of the treatment protocol. NHA resin infiltrant (ICON with 5% or 10% NHA) effectively enhanced the artificial enamel caries surfaces in terms of smooth surfaces, mineral density, and resin penetration.

Spectrophotometric Analysis of Different Flowable Restorative Materials.

AIM: To compare the color change of three flowable composites after exposure to staining solutions. MATERIALS AND METHODS: A total of 240 oval samples were constructed of conventional flowable resin composite, self-adhesive flowable resin composite, and nanohybrid flowable ormocer (n = 80). Each set was further subcategorized into three subsets as regards staining solution. The baseline color parameters were recorded using spectrophotometer after the immersion of the specimens in artificial saliva for 24 hours. Then, the measurements were taken again after exposure to staining solutions where the color change was measured as ΔE* = V (ΔL*2 + Δa*2 + Δb*2). RESULTS: Conventional flowable resin composite had the best color stability in all staining solutions. The coffee was concluded to be the most staining solution. Compared to beverages, mouthwashes had a greater discoloration effect on nanohybrid flowable ormocer than on selfadhesive flowable composite. CONCLUSION: Conventional flowable composite had the highest color stability among the tested materials, followed by flowable nanohybrid ormocer, and the least was self-adhering flowable composite. Coffee had the greatest discoloration effect, followed by a sports drink and then the energy drink. However, mouthwashes did not have a significant discoloration effect. CLINICAL SIGNIFICANCE: Selection of flowable composite materials that are resistant to staining by coffee, beverages, or mouthwashes is an important factor that may influence the sustainability of the esthetic quality of the restoration.

Performance of Self-adhering Flowable Composite in Class V Restorations: 18 Months Clinical Study.

AIM: The present randomized clinical study compared the 18 months performance of self-adhering flowable composite with a conventional flowable composite in anterior Class V restorations. MATERIALS AND METHODS: Totally, 20 patients, each with two moderate cervical carious lesions, participated in this single-center study. Forty restorations were allocated on a random basis by one examiner not involved in the restoration or the evaluation procedures, In each patient, one lesion was allocated to be restored using self-adhering flowable composite [Fusio liquid dentin (FL)] and the other to be restored using conventional flowable composite [Tetric Flow (FF)]. The allocation sequence of the restorations was concealed from the operator in sequentially numbered, opaque, sealed, and stapled envelopes. An operator restored all the preparations in accordance to the manufacturer's instructions. Finishing and polishing of the restorations were done immediately after placement. Evaluation of the restorations was done in accordance to the United States Public Health Services (USPHS), modified Ryge criteria. Statistical analysis was completed with Statistical Package for the Social Sciences (SPSS) version 20.0 (IBM Product, Chicago, USA). RESULTS: One case could not be reassessed at 18 months follow-up in both groups. No significant differences were detected between the tested materials from baseline to those of 18 months using the modified USPHS criteria. CONCLUSION: Self-adhering flowable composite exhibited acceptable clinical performance comparable with the conventional flow-able composite in anterior Class V restorations over an 18-month period. Nevertheless, the findings of this study must be validated by a longer clinical study. CLINICAL SIGNIFICANCE: Self-adhering flowable composite exhibited clinical performance comparable with the conventional flowable composite in Class V restoration.

X-ray microtomography assessment of Carisolv and Papacarie effect on dentin mineral density and amount of removed tissue.

OBJECTIVE: The aim of the present study was to directly compare Carisolv and Papacarie regarding the volume of removed tissue (RT) and dentin mineral density (DMD) after excavation. MATERIALS AND METHODS: Twenty permanent molars were randomized into two groups where caries was excavated using Carisolv or Papacarie followed by removal of softened tissue by a blunt instrument. X-ray microtomography was used to scan teeth before and after excavation generating two- and three-dimensional images that were used to calculate the percentage of RT relative to baseline tooth tissue volume and DMD that was categorized into sound dentin (>1.11 g/cm3) and residual caries (≤1.11 g/cm3). The two groups were compared using t-test Fisher exact test. RESULTS: DMD was higher after Papacarie than Carisolv (mean = 1.70 and 1.14, p = .14) with higher percentage of cases with sound dentin (70 and 60%, p = 1.00). The percentage of RT was lower after Papacarie than Carisolv (7.40 and 8.95%, p = .31) with 22.95% less RT in cases that ended with sound dentin after excavation. CONCLUSIONS: There was higher DMD, more sound dentin and less RT when Papacarie was used compared to Carisolv.

The effects of mouth rinses on the color stability of resin-based restorative materials.

OBJECTIVE: The aim of this study was to assess the color stability of three direct resin-based restorative materials: IPS Empress Direct (Ivoclar Vivadent, Schaan, Liechtenstein), Nano-filled composite (Filtek Z 350 XT, 3 M ESPE, St. Paul, MN, USA), and Nano-hybrid composite (Tetric Evo Ceram, Ivoclar Vivadent, Schaan, Liechtenstein) upon immersion into the following three mouth rinses: Antiseptol (Kahira Pharmaceuticals and Chemical Industries Co. Cairo-Egypt), Flucal (Alexandria Co. Pharmaceuticals Alexandria, Egypt), and Listerine (Johnson & Johnson, UK). MATERIALS AND METHODS: Ninety disc-shaped, 12 mm × 1 mm specimens were divided into three groups according to the type of direct resin-based restorative material used. The specimens were randomly subdivided into three different subgroups (N = 10) in terms of immersion medium. Color change was evaluated prior to and after immersion into the mouth rinses for 24 hours by spectrophotometry (Shimadzu, UV-3101 PC Shimadzu Corporation. Kyoto, Japan). RESULTS: Data were statistically analyzed using two-way analysis of variance (ANOVA) to assess the color stability of the restorative materials. The post hoc Scheffe's test was applied to clarify pair-wise statistical significance. Results with p-values < 0.05 were considered statistically significant. IPS Empress Direct (ΔE = 1.48) exhibited more favorable stability than the other tested composite resins, Filtek Z 350 X (ΔE = 3.05) and Tetric Evo Ceram (ΔE = 10.35). The immersion media elicited a significant effect on the color stability of the tested, resin-based restorative materials, where Flucal elicited the most significant color change, followed by Listerine and Antiseptol, which elicited the least significant color change. CONCLUSIONS: Within the limitation of this laboratory study, the following conclusions could be drawn: (1) The composite structure, namely the resin formulation, which includes the filler size and type of photo-initiator, has a direct impact on its susceptibility to stain by external agents; (2) Mouth rinses can be considered stainable solutions; (3) The chemical formulation of individual mouth rinses can significantly control their ability to stain. CLINICAL SIGNIFICANCE: Patient use of mouth rinses should be subject to dental supervision to control their adverse effects on the aesthetic quality of the restoration. Knowing the composition of the restorative material is important, as is its polymerization cycle and the promotion of adequate surface texture in order to select the appropriate material for each clinical application, and to use it in an effective way to promote its best properties.

Apoptotic effect of different self-etch dental adhesives on odontoblasts in cell cultures.

OBJECTIVES: We aimed to evaluate the potential cytotoxicity (apoptosis-induction) of three types of self-etch dental adhesives: two-component one-step (Xeno III), two-component two-steps (Clearfil Protect Bond) and one-component one-step (Xeno V) on cultured odontoblasts. METHODS: Each adhesive was prepared to simulate its clinical manipulation. Cured sterile individual masses were immersed in DMEM and left at 37 °C for 24 h. Then a volume of 100 µL of the extract medium was added to the cultured odontoblasts and incubated for additional 24 h, 48 h and 72 h, respectively. Acridine orange-propidium iodide (AO-PI) labelling was employed to assess the proportion of dead to total number of cells. In addition, an in situ apoptosis detection kit was used to evaluate the DNA cleavage and chromatin condensation employing the immunohistochemical (IHC) technique. Statistical analysis of the data was performed using one-way ANOVA. RESULTS: Both apoptosis evaluation methods revealed comparable results with the exception that IHC showed 5-7% less number of dead cells when compared to similar groups evaluated by AO-PI. The percentages of dead to total cells after treatment with Clearfil Protect Bond, Xeno III and Xeno V, were significantly different from the percentage of dead cells after treatment with DMEM alone (-ve control), P value <0.05 and Xeno V dental adhesive had the weakest cytotoxic effect on odontoblasts followed by Xeno III especially after 24 h of incubation. Clearfil Protect Bond had the strongest cytotoxic effect on odontoblasts that was almost closer to that of Staurosporine in DMEM (+ve control). CONCLUSION: All tested dental adhesives had remarkable adverse effect on the odontoblasts in vitro; this might be of concern when applied clinically in deep cavities where such cytotoxic chemicals become in close contact to dental pulp. Therefore, further in vivo studies on animal models are recommended to support or refute these in vitro findings.

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.