Eugenia Koliniotou-Koumpia

Dentinogenic responses after direct pulp capping of miniature swine teeth with Biodentine.

INTRODUCTION The aim of this study was to evaluate pulpal responses after experimental direct pulp capping of mechanically exposed teeth with a new calcium silicate-based dentin replacement material. METHODS Thirty-four anterior and posterior teeth of 3 miniature swine were used. Class V or I cavities were prepared on the buccal or occlusal surfaces, respectively. Pulpal exposures were further performed using a round carbide bur 0.8 mm in diameter. Exposures were treated with white MTA Angelus (Angelus, Londrina, PR, Brazil) or Biodentine (Septodont, Saint Maur des Fosses, France), and the cavities were further restored with Biodentine. The pulpal tissue responses were histologically assessed at postoperative periods of 3 and 8 weeks. Data were statistically analyzed using the Kruskal Wallis and the Mann-Whitney U tests. RESULTS Inflammatory infiltration or pulp tissue necrosis was not found in any of the specimens. All teeth showed mineralized matrix formation in the form of a complete hard tissue bridge composed of osteodentin or osteodentin followed by a discontinuous or continuous reparative dentin zone. A significantly higher thickness of the hard tissue bridge was found in the group of teeth treated with Biodentine at both 3 and 8 weeks. A number of teeth, which were under root development at the onset of the experimental procedures, exhibited ectopic pulp calcification. CONCLUSIONS The application of both calcium silicate-based materials in direct contact with the mechanically exposed pulp of healthy miniature swine teeth led to pulp repair with complete hard tissue bridge formation. The thickness of hard tissue bridges was significantly higher after pulp capping with Biodentine.

Effect of extraction media and storage time on the elution of monomers from four contemporary resin composite materials.

Introduction: The purpose of this study was to examine the effect of different extraction media, including culture media, as well as storage times on the elution of monomers from modern dental composites. Materials and Methods: Four contemporary composite materials were tested: (a) Clearfil Majesty Esthetic (Kuraray), (b) Esthet X (DENTSPLY), (c) Filtek Silorane (3M ESPE), and (d) Admira (Voco). Forty-eight specimens were made. The specimens were stored in 1 ml of (a) artificial saliva, (b) Dulbecco`s Modified Eagle Medium (DMEM), (c) DMEM plus 10% fetal bovine serum (FBS), and (d) ethanol 75%. The specimens were analyzed after 24 hours and after 1 week of storage. HPLC Liquid Chromatography was performed to analyze the extracted solutions. The statistical package SPSS 18 was used for the statistical analysis of the results. Results: All the materials tested released monomers that were consistent with the base composition of their resin matrix. Bisphenol-A (BPA) was detected in Clearfil Esthetic and EsthetX when ethanol 75% was used for storage. TEGDMA was released at a faster rate compared to the other monomers with most of the monomer eluted in the first 24 hours. The effect of storage solution and storage time on the elution of the same monomers varied between materials. Conclusions: There was a significant effect of time, storage solution, and material on the elution of the detectable unbound monomers. Unbound monomers were detected in culture media, which may lead to false-negative results in cytotoxicity tests of resin composite materials. BPA was detected in two of the tested materials.

The reparability of contemporary composite resins.

Objective: The objective was to investigate the way that various surface treatments could influence the bond strength of the repair of methacrylate (MC) and silorane (SIL) composites. Materials and Methods: A total of 160 MC and SIL cylindrical specimens were polymerized and aged in artificial saliva solution for 7 days. Depending on the following surface treatment (diamond bur or air abrasion), and the conditioning procedure (orthophosphoric acid or sodium hypochlorite), 16 groups were formed and repaired either with MC, either with SIL composite. Repaired specimens were subjected to an additional aging procedure in artificial saliva for 7 days, followed by thermo-cycling and then stressed in shear at a rate of 0.5 mm/min until failure. Failure patterns were analyzed using stereomicroscope and scanning electron microscopy . Results: MC composite showed statistically significant higher bond strength both as a base or repair material than SIL (P < 0.001). Statistically significant differences were not observed, when grinding and conditioning procedures was compared. Pretest failures were observed when aged MC-based composite was repaired with SIL-based. Conclusions: Type of composite seems to be the main factor influencing the bond strength of the repair. MC-based composite showed better repairability than SIL composite. Optimum repair conditions should include knowledge of the composite′s composition.

Pulp response to dentine adhesives: A study on mature human pulps

Objective: To clinically investigate the antibacterial effects of a commercially available self-etch 12-methacryloyloxy- dodecylpyridinium bromide (MDPB)-containing adhesive system in comparison with its respective non-MDPB-containing adhesive and to evaluate the pulp responses when in use on human teeth. Materials and Methods: Sixty-two viable human teeth scheduled for extraction were used. Class V cavities were prepared on the buccal surfaces of the teeth and filled with the tested materials (Protect Bond/Clearfil AP-X, SE Bond/Clearfil AP-X and Dycal/Ketac Fill Plus) as a control group, according to manufacturers recommendations. Randomly divided to two groups teeth remained intra-orally for 4 and 8 weeks. After extraction, teeth were decalcified, sectioned and stained using the Mayers hematoxylin and eosin, and modified Brown-Brenns technique. Pulp responses were evaluated microscopically under a microscope and remaining dentine thickness measured under a stereomicroscope. Results: No statistically significant differences regarding pulp inflammation or bacterial infiltration were found either for the materials tested or for periods of post-operative evaluation. Conclusions: The results suggested that for a short period of evaluation there are no quantitative differences, regardless to restoring material used.

In Vitro Inhibition of Enamel Demineralisation by Fluoride-releasing Restorative Materials and Dental Adhesives.

PURPOSE To determine the ability of 5 contemporary fluoride-releasing restoratives and 3 fluoride-releasing adhesives to inhibit enamel demineralisation surrounding restorations, and the associations between inhibition and the levels of fluoride released from these materials. MATERIALS AND METHODS Five fluoride-releasing restoratives (Fuji IX GP, Ketac N100, Dyract Extra, Beautifil II and Wave) and 3 fluoride-releasing adhesives (Stae, Prime & Bond NT and Fluoro Bond II) were investigated. Eight disks of each material were prepared. Fluoride release was measured daily using a fluoride-ion-selective electrode for 15 days. Twenty-four cavities for each group were restored with a restorative and an adhesive. Specimens were subjected to thermal stress and stored for 30 days in saline solution. After a 15-day pH-cycling regimen, two 150-μm-thick sections were derived from each specimen. Enamel lesion depth was measured at 0, 100, and 200 μm from each restorations margin via polarised light microscopy. RESULTS Of the restoratives investigated, Fuji IX GP released the most fluoride. The fluoride-releasing restoratives tested exhibited shallower enamel lesions than did the control group at all distances tested (p < 0.05). Fuji IX GP yielded significantly lower enamel lesion depth than did the other experimental materials. The depths of enamel lesions did not differ significantly when comparing restoratives applied with a fluoride-releasing adhesive with those applied with a non-fluoride-releasing adhesive. CONCLUSION The fluoride-releasing materials tested reduced enamel demineralisation but to different extents, depending on their levels of fluoride release. Fluoride-releasing adhesives did not influence enamel lesion formation.

The influence of a novel in-office tooth whitening procedure using an Er,Cr:YSGG laser on enamel surface morphology.

The purpose of this in vitro study was to evaluate the influence of a novel in‐office tooth whitening procedure using Er,Cr:YSGG laser radiation on bovine enamel.

Dentinogenic Activity of Biodentine in Deep Cavities of Miniature Swine Teeth

INTRODUCTION The aim of the present study was to evaluate comparatively the bioactivity potential of a calcium silicate-based material (Biodentine; Septodont, Saint-Maur-des-fosses Cedex, France) after the restoration of deep dentinal cavities of miniature swine teeth with or without the application of a calcium hydroxide-containing pulp protective base (Dycal; Caulk Lab, Milford, DE). METHODS Thirty-three permanent teeth (premolars, canines, and incisors) of 3 miniature swine were used. Class V cavities were prepared on the buccal surface of teeth. The cavities were restored with Biodentine in the presence (control group) or absence (experimental group) of a Dycal protective base. The pulpal tissue responses were histologically and histomorphometrically assessed at postoperative periods of 3 and 8 weeks. Three specimens were further evaluated with scanning electron microscopy. The maximum thickness of the postoperatively formed mineralized matrix beneath the cavity floor was measured. Data were statistically analyzed by the Kruskal-Wallis and the Mann-Whitney U tests. RESULTS A bacterial staining reaction along the cavity walls or intense inflammatory infiltration in the pulp was not detected in any of the specimens. A continuous zone of the postoperatively formed mineralized matrix mostly of atubular structure with scattered defects and cellular inclusions and occasionally followed by a thin zone with tubular morphology was detected in all specimens of the control group and 13 of 18 experimental group teeth. In the remaining teeth of the experimental group, a separate zone composed of the osteotypic mineralized matrix and soft tissues was noted between the circumpulpal and the newly formed matrix. Scanning electron microscopy confirmed the fibrous structural morphology of the tertiary dentin. A significantly higher rate of the postoperatively formed mineralized matrix had been formed in the teeth of the experimental group in both periods of 3 and 8 weeks (P < .01). CONCLUSIONS The present investigation indicates that under the present experimental conditions tertiary dentin with occasional intermediate formation of osteodentin is observed after the application of Biodentine in the presence or absence of a Dycal protective base. The thickness of the tertiary dentine zone was significantly higher in the absence of Dycal.

Effect of temperature, curing time, and filler composition on surface microhardness of composite resins

Aim: The aim of this study was to evaluate the microhardness of two composite resins when subjected to three different temperatures and three different light-curing times. Materials and Methods: Two composites were used; Filtek Z250 and Grandio. Three different temperatures (23, 37, and 55oC) were used, utilizing a composite warmer. The heated samples were immediately injected into cylindrical molds (6 mm × 2 mm) and the top surface of the specimens was polymerized for 10, 20, and 40 sec, using a Quartz-Tungsten-Halogen light-curing unit (QTH LCU). Vickers microhardness measurements were performed from both the top and bottom surface of the specimens, following dry storage for 24 hours in the dark. Statistical analysis were performed using one-way analysis of variance (ANOVA) and Tukey post-hoc test at a level of significance of a = 0.05. Results: The results indicated that there was an increase in microhardness as the temperature of the composite was increased for either the top or the bottom surface (P < 0.05). Furthermore, there was a general increase in microhardness for both composites as curing time increased (P < 0.05). The type of composites did not influence the surface microhardness (P > 0.05). Conclusions: Temperature of composites affects their surface microhardness. Also, light-curing time influence microhardness values of the composites tested.

Effect of preheating and shade on surface microhardness of silorane-based composites.

AIM The aim of the present study was to evaluate the effect of preheating and shade on the surface microhardness of silorane-based composites. METHODS Three shades of two different types of composites were evaluated: a silorane-based composite and a methacrylate-based composite. The composites were tested at 23°C, and after preheating at 55°C. Five specimens were prepared for each experimental group. The top surface of the specimens was irradiated for 20 s using an LED unit. Vickers microhardness test was used to evaluate both top and bottom surfaces of the specimens, followed by 24-h storage in the dark. Statistical analysis was performed using one-way anova and Tukeys post-hoc test at a level of significance of α = 0.05. RESULTS There was a significant rise in microhardness as the temperature increased from 23 to 55°C for both the top and bottom surfaces of the tested composites (P < 0.05). The C2 shade of both composites exhibited the lowest microhardness (P < 0.05), while the A2 and A3 shades did not show significant differences compared to each other (P > 0.05) Filtek Silorane presented significantly lower microhardness than Filtek Z250 (P < 0.05), regardless of the temperature, shade, or depth of measurement. CONCLUSIONS Preheating, shade, and composition of the tested composite resins affected their surface microhardness.

Effect of Acidulated Phosphate Fluoride Gel on the Surface of Dental Nanocomposite Restorative Materials

The aim of this in vitro study was to investigate the changes in surface roughness of different nanocomposite restoratives and enamel after application of 1.23% acidulated phosphate fluoride (APF) gel. Twelve specimens were prepared for each composite material and human enamel. The APF gel was applied to the surface of the six specimens of each experimental group for 60 sec every 24 h for 4 days. The other six specimens did not receive APF treatment (control). The surface roughness was measured using a VSI microscope. One-way ANOVA and Tukey’s test were used to compare surface roughness between materials for each experimental group at a level of significance of a=0.05. There were no statistically significant differences in Ra values among the composites which did not receive APF treatment (p>0.05). After APF treatment the lowest surface roughness exhibited enamel (0.18±0.04 Ra) and the highest Dyract Extra (0.62±0.07 Ra) followed by Tetric EvoCeram (0.59±0.06 Ra) and Beautifil II (0.51±0.06 Ra). Filtek Z350 XT presented the lowest Ra values (0.23±0.03). All the experimental groups exhibited higher Ra values after APF treatment (p<0.05), except for Filtek Z350 XT (p>0.05). Application of APF gel on the specimen surfaces influenced the surface roughness of enamel and the tested dental composite restoratives depending on their composition.