Evaluation of the permeability of five desensitizing agents using computerized fluid filtration.

OBJECTIVE: The aim of this study was to evaluate the permeability of five desensitizing agents using computerized fluid filtration (CFF) test method. MATERIALS AND METHODS: Sixty dentin discs of 500 ± 200-mm-thick were prepared from middle dentin of bovine incisors without exposed the pulp and then randomly divided into five groups (n = 12). The permeability of the discs was measured using the CFF test method before and after application of the following desensitizers: Admira Protect (Voco, Cuxhaven, Germany), Seal and Protect (Dentsply, Konstanz, Germany), Sensi Kill (DFL, Brazil), Systemp Desensitizer (Ivoclar Vivadent, Liechtenstein), BisBlock (Bisco, USA). Fluid movement measurements were made at 2-min intervals for 8 min, and a mean of the values obtained was calculated for each specimen. The results were analyzed using Kruskal-Wallis test and Wilcoxon signed ranks tests with a significance threshold of P < 0.05. RESULTS: There were no significant differences in permeability among desensitizing agents (P > 0.05); however dentin permeability was reduced in all groups (P < 0.05). CONCLUSION: The in vitro fluid conductance of dentin discs were reduced by treating with these five desensitizing agents.

Cytotoxic effects of dental desensitizers on human gingival fibroblasts.

The purpose of this study was to evaluate the effects of three different desensitizers on the cell viability and morphology of human gingival fibroblasts (HGF). Human gingival tissues were obtained from individuals who have clinically, healthy periodontium. HGF were grown at 37 degrees C in humidified atmosphere of 5% CO2 in Dulbecco's modified eagle's medium, supplemented with glutamine, penicillin, streptomycin, and 10% fetal bovine serum. The cells were treated with different concentrations (0.1, 0.3, and 0.5 microL/mL) of desensitizers (Gluma Desensitizer, Seal&Protect, and MicroPrime). After 24- and 48-h exposure to the desensitizer solutions, the viable cells were examined using a hemocytometer. To monitor HGF viability, 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl tetrazolium bromide (MTT) colorimetric assay was used and cell morphology was also observed at 48 h. Following exposure to concentrations of 0.1 microL/mL of test materials for 24 h, cell survival rates for Gluma Desensitizer (106%) and Micro Prime (62%) were not significantly different from the control, while it was significant for Seal&Protect (50%). Growing cells were significantly inhibited by all tested materials for 48 h (p < 0.05) in survival rates of 51, 47, and 31%, respectively. On the basis of the MTT assay, the cytotoxic effect of MicroPrime was more prominent, especially at high concentrations, than does Gluma Desensitizer and Seal&Protect. After exposure to Seal&Protect and MicroPrime, HGF became retracted, rounded in appearance and had loss of normal organization, leading to enlargement of intercellular space when compared with Gluma Desensitizer. As a conclusion, taking the limitations of an in vitro experiment into consideration, the cytotoxic effects were varied, depending on the chemical composition and exposure periods of the tested desensitizers.

Ganglion cell complex thickness in nonexudative age-related macular degeneration.

PURPOSE: TO evaluate ganglion cell complex (GCC) thickness with spectral domain optical coherence tomography (SD-OCT) in eyes with nonexudative age-related macular degeneration (NEAMD). METHODS: Forty-seven eyes of 28 patients with nonexudative age-related macular degeneration (NEAMD) and 54 eyes of 28 age-matched healthy subjects were enrolled. Each subject underwent a complete ophthalmic examination before SD-OCT were obtained. Macular scans were taken with software version 6.0 of the ganglion cell analysis (GCA) algorithm. GCC thickness was evaluated automatically as the average, minimum, temporal superior, superior, nasal superior, nasal inferior, inferior, and temporal-inferior segments by SD-OCT and parameters were compared between groups. RESULTS: The mean age was 68.7±8.73 years in patient group, and 61.51±5.66 years in control group. There were no significant differences in mean age, gender distribution, intraocular pressure, and sferic equivalent at imaging between the groups (P>0.05). The mean (±SD) GCC thicknesses were as follows; average 71.53±16.53 µm, minumum 62.36±21.51 µm, temporal superior 72.23±14.60 µm, superior 72.76±20.40 µm, nasal superior 72.31±20.13 µm, nasal inferior 69.74±20.51 µm, inferior 69.38±19.03 µm, and temporal-inferior 73.12±15.44 µm in patient group. Corresponding values in control group were 81.46±4.90 µm, 78.66±6.00 µm, 81.51±4.66 µm, 82.94±5.14 µm, 81.79±5.86 µm, 80.94±6.18 µm, 80.14±6.30 µm, and 81.75±5.26 µm, respectively. There were significant differences between two groups in each segments (Mann-Whitney U-test, P<0.05). CONCLUSION: The average GCC thickness values (in all segments) of NEAMD patients were lower than control group. NEAMD, which is considered as a disease of outer layers of retina, may be accompanied with a decrease of ganglion cell thickness, so inner layers of retina may be affected.

Vitreoretinal surgery of retinal detachment and macular hole associated with optic nerve pit: an optical coherence tomography study.

PURPOSE: To describe the course of a case of macular elevation and a full-thickness macular hole associated with optic nerve pit. METHODS: Case report. A 28-year-old woman who had laser-assisted in situ keratomileusis surgery 2.5 years ago presented with decreased vision, full-thickness macular hole, and macular detachment in association with optic nerve pit. Complete ophthalmic examination was done and optical coherence tomography (OCT) was performed before and after vitreoretinal surgery. RESULTS: OCT showed that the macular elevation consisted of both separation of the inner and outer retinal layers with neurosensory retinal detachment. There was a full-thickness macular hole. After vitreous surgery and intraocular gas tamponade, the macular elevation completely resolved, and OCT showed the flattening of the outer and inner retinal layers but the macular hole was not closed. CONCLUSIONS: OCT is a reliable technique to study macular elevation with a hole associated with optic nerve pit before and after vitrectomy and gas tamponade.

Amalgam repair: evaluation of bond strength and microleakage.

This study evaluated the tensile bond strength of "repaired" amalgams and compared the degree of microleakage. Amalgam (Cavex avalloy) was condensed into plastic tubes (3 mm in diameter, 10 mm in height) to the half-length. After storage in water at 37 degrees C for two days, the remaining parts of tubes were filled with amalgam (A), cavity varnish (CV)+A, Liner Bond 2V (LB2V)+A, 3M Opal Luting Cement (3MOLC)+A, Panavia F(PF)+A, Metabond(MB)+A, Fuji BondLC(FB)+A, HytacOSB(HOSB)+Hytac Aplitip (H), Liner Bond2V+Clearfil AP-X(CAP). The bond strengths for 15 samples of each restoration group were determined. For the microleakage study, MOD cavities of 90 extracted human premolars were used. The distal half of cavities were filled with amalgam. After storage in water at 37 degrees C for two days, the mesial half of the cavities were filled to simulate a clinical repair. The "repair" was placed using the procedures applied in the bond strength study. The teeth were stained with basic fuchsine (0.5%), sectioned and evaluated for dye penetration. In both parts of study, the data were analyzed by ANOVA and Duncan's multiple range tests. Bond strength values (MPa) were: A+PF+A 3.84+/-1.08, A+LB2V+A 3.15+/-0.97, A+LB2V+CAP 3.05+/-0.53, A+MB+A 2.86+/-0.88, A+HOSB+H 2.58+/-0.51, A+3MOLC+A 2.11+/-0.75, A+FB+A 0.68+/-0.59. The repaired A+A and A+CV+A groups were separated before testing. The A+PF+A group showed the highest bond strength (p<0.05). Microleakage in the cervical margins of repaired restorations was lower in the amalgam groups than microleakage in the resin composite and compomer groups. PF, MB, 3MOLC and FB performed better at the amalgam "repair" interface. The A+LB2V+A group showed no microleakage at both the occlusal and gingival test regions.

Evaluation of internal adaptation in ceramic and composite resin inlays by silicon replica technique.

This study was aimed at investigating the internal adaptation of a ceramic (Ceramco II) and two composite resin inlay materials (SureFil and 3M Filtek Z 250) using silicon replica technique as an indicator. Forty-five standard mesial-occlusal-distal (MOD) cavities were prepared into brass moulds by using computer numerically controlled system. Inlays were prepared according to manufacturers' instructions with indirect methods. Replicas of the prepared cavities and inlays were produced with a polyvinyl siloxane material (Elite H-D). The spaces between inlays and cavities were filled by different coloured light-body polyvinyl siloxane material. Two parallel slices (mesio-distally) were obtained from the replicas with a sharp blade. Different coloured polyvinyl siloxane material thickness between cavity and inlay was measured at seven points (mesial, occlusal and distal). The data were evaluated with anova and Tukey's honestly significantly different (HSD) statistical tests. In the SureFil and Ceramco II groups, the sizes of the contraction gaps at mesial and distal gingival floors were greater than that of the occlusal marginal walls. In comparison of gap formation at occlusal regions, while the 3M composite group showed highest gap values (204.33 +/- 75.45 microm), the Ceramco II group revealed the lowest (141.17 +/- 23.66 microm) (P < 0.05). At the gingival floors, gap formation of Ceramco II group was the highest (227.08 +/- 51.95 microm). Neither the 3M Filtek Z250 nor SureFil group showed any statistical difference between gap values of their self-occlusal and gingival floors (P > 0.05). In conclusion, our results showed that ceramic inlays did not confer any big advantage for internal adaptation over the composite inlays.

In vitro dentine permeability evaluation of HEMA-based (desensitizing) products using split-chamber model following in vivo application in the dog.

The aim of this study was to evaluate in vitro dentine permeability evaluation of 2-Hydroxyethyl methacrylate (HEMA)-based desensitizing products using split-chamber model following in vivo application in the dogs for three experimental time periods of 1 week, 1 month and 3 months. Buccal enamel of upper and lower canines of nine young dogs was removed and flat dentinal surface was obtained using a water-cooled diamond bur. The dentinal surface divided into four quarters, three experimental and a control. Health-Dent and Gluma Desensitizing agent and Single bond were applied to respective quarters of one tooth, according to manufacturers' instructions. The last quarters were left as control without any applications. For the each experimental period, 10 dentine samples from each group including control were used to measure the hydraulic conductance values. The dentine discs were placed pulp-side down in a split-chamber device in which the plastic spacers containing the rubber 0 rings have a surface area of 1 mm(2) and permeability was measured by fluid filtration. The data were expressed as hydraulic conductance (Lp). Differences in dentine permeability obtained for the desensitizing agents against the control were tested for statistical significance using Kruskal-Wallis one-way ANOVA and Bonferroni-adjusted Mann-Whitney U-tests. Differences in permeability in three time periods for each desensitizing agent were analysed using Friedman's anova and Wilcoxon signed rank tests. All desensitizing applications caused decreased Lp values compared with the control Lp value at the end of 1 week. In the 1-month samples, between the Lp values of Single bond and control, no statistical difference was found (P > 0.05). At the end of the 3-month period, the Gluma Desensitizing agent had the lowest the Lp value (P < 0.05). The result of this study is that the topical application of desensitizing agents led to decrease in dentine permeability in the dog model. The Gluma Desensitizing agent provide the more lasting tubule-occluding effect than the other material tested in this model.

The long-term effectiveness of five current desensitizing products on cervical dentine sensitivity.

The aim of this study was to compare the long-term effectiveness of five desensitizing products on 25 male and 27 female patients (total 52) aged 21-67 years (mean 36 +/- 7 years) suffering from cervical dentine sensitivity. All subjects were seen by the same examiner (ID) who was blinded to the applied treatment for 3-month clinical study. Patients were asked to record their overall sensitivity by marking a point on a 10 cm Visual Analogue Scale (VAS). Two hundred and seventy-seven sensitive teeth were treated by one of the five desensitizing products, all of which were placed following manufacturers' instructions by the other investigator (AS). A paired (split mouth) study design was used and selection of quadrants was randomized. At the post-treatment and at 10 days and 3 months periods, sensitivity measurements were recorded by the same investigator (ID). Statistical analysis showed that all of the VAS scores at post-treatment evaluation points were significantly decreased compared with baseline data (P < 0.05). There was a significant reduction in mean sensitivity scores in the Protect Liner F and the Health-Dent Desensitizer groups when compared with Fluoline varnish at the 10-day time point (P < 0.05). At 3 months, the Protect Liner F group continued to show a significantly reduced sensitivity level when compared with Health-Dent Desensitizer, Single Bond, Fluoline and Gluma Desensitizer (P < 0.05). The present study demonstrated that although at the end of 3-month evaluation period all desensitizers showed lower VAS sensitivity values compared with baseline, there were differences in the level of reduction of cervical dentine sensitivity.

The effect of simulated intrapulpal pressure on bond strength to enamel and dentine.

The purpose of this study was to evaluate the effect of simulated intrapulpal pressure on the shear bond strength (SBS) of a self-etching bonding system (Clearfil Liner Bond II) to both enamel and dentine surfaces. Forty-two caries-free human molar teeth were randomly assigned to two equal groups (n=21). One group of 21 teeth was connected to a special pulpal pressure machine, which is developed to simulate in vivo conditions. The buccal and lingual surfaces of the teeth were prepared with a diamond wheel to create flat dentine and enamel surfaces. A self-etching bonding system was then applied under pulpal pressure and 2.5 mm diameter composite cylinders were bonded to the prepared surfaces. The samples were then stored in distilled water at room temperature for 24 h under pulpal pressure before SBS was tested. The second restored group was used as a control and the teeth were not connected to the pulpal pressure apparatus during material application and test procedures. They were stored for 24 h in distilled water at room temperature before the SBS test. Fracture analysis of the enamel and dentinal surfaces was performed using a stereomicroscope. Shear bond strength values to dentine was significantly reduced with pulpal pressure (P < 0.001). However, in the enamel, SBS was increased (P < 0.001). In the control group, the SBS values to dentine and enamel did not show any significant difference (P > 0.05). Based on these results, it can be concluded that further analysis of enamel histology and bonding mechanisms are needed.

Influence of dentinal regions on bond strengths of different adhesive systems.

This in vitro study assessed comparatively the shear bond strengths of three composite resins, 3M Valux Plus (3MVP), Herculite (H), Clearfil AP-X (CAP-X), a polyacid modified composite resin Dyract (D), and a resin modified glass-ionomer materials Vitremer (V), to cervical and buccal dentine regions of extracted human molar teeth. Four different bonding systems, 3M ScotchBond Multipurpose (SB), Clearfil Liner Bond 2 (LB2), Opti Bond (OB), and Prime & Bond 2.1 (PB 2.1) were used with the manufacturer's respective composite and compomer materials. One hundred freshly extracted mandibular molar teeth were selected for this study. Flat buccal dentine surfaces were created on 50 teeth and cylindrical rods of the five materials were bonded to the dentine surfaces. For assessment of cervical bond strengths, the materials were bonded to mesial and distal enamel bordered occlusal dentinal surfaces of the remaining 50 teeth. The five groups of restorative procedures were applied as follows; Group 1: SB + 3MVP, Group 2: LB2 + CAP-X, Group 3: OB + H, Group 4: PB2.1 + D, Group 5: Vitremer primer (VP) VP + V. Each restorative procedure thus had 20 specimens (10 buccal + 10 cervical). After 24 h of water storage (37 degrees C), the specimens were tested on a Universal Testing machine in shear with a cross head speed of 0.5 mm min-1. The bond strength values were calculated in MPa and the results were evaluated statistically using Kruskal-Wallis one-way/anova and Mann-Whitney U-tests. It was found that the bond strengths of SB + 3MVP, LB2 + CAP-X and VP + V to buccal dentine surfaces were significantly stronger (P < 0.05) than those to the occluso-cervical dentine floors. When the bond strengths to the occluso-cervical dentine and buccal dentine surface were compared, there was no significant difference between the materials (P > 0.05). Vitremer was found the least successful adhesive material in terms of shear bond strength on both buccal and occluso-cervical dentine surfaces.

Shear bond strengths of tooth fragments reattached or restored.

This study investigated the shear bond strengths of sectioned human mandibular incisor edge fragments reattached using luting cements, bonding agents or restored with composite resins. Seventy teeth were randomly distributed among six experimental groups and a control group. Leaving half of the anatomic crowns exposed, the teeth were embedded in self-cure acrylic resins with the exposed part then sectioned. The fragments in groups 1-4 were bonded to their respective teeth using Clearfil Liner Bond 2V, Scotch Bond Multi Purpose Plus, Panavia-F and 3M Opal Luting cement. The 5th and 6th groups were restored with composite resins (Silux 3M and Clearfil AP-X) using their bonding agents (Single Bond and Clearfil SE Bond). The results indicated that reattachment of fractured incisal fragments by using new generation bonding agents was effective against shear stresses, comparable with the intact teeth. Instead of restoration with composite resins therefore reattachment of a fractured fragment might be more preferable in cases of dental trauma.

Bond strength of five current adhesives to caries-affected dentin.

Five current dentin adhesives were evaluated for their ability to bond to caries-affected dentin. The materials were: total etch [Solid Bond (SB)], two self-etch [Clearfil SE Bond (CSE), Etch and Prime (EP)], two one bottle [Prime and Bond 2.1 (PB), One Coat Bond (OCB)]. Sixty extracted molar teeth with proximal caries (mesial or distal) extending into mid-dentin were used. By grinding normal and caries-affected proximal surfaces, flat dentin surfaces were obtained. The surfaces were then bonded with each adhesive system and composite resins were added to the surfaces by packing the material into a cylindrical-shaped plastic matrix with an internal diameter of 2.5 mm and height of 3 mm. Shear bond testing was performed following 10 days incubation of specimens in distilled water at 37 degrees C. Results were analysed by Kruskal-Wallis ANOVA, and Mann-Whitney U multiple comparison test and Wilcoxon rank tests. The results obtained with CSE, SB, and EP were similar in caries affected and normal dentin (P > 0.05). But bonds made to normal dentin with OCB and PB were lower (P < 0.05) than bonds to caries-affected dentin. Bonding to caries-affected dentin with CSE (24.49 +/- 5.38), SB (21.49 +/- 9.15), and EP (21.19 +/- 9.17) showed shear bond strengths higher than OCB (17.43 +/- 9.78) and PB (14.10 +/- 7.94) (P < 0.05). Bonding to normal dentin with CSE (29.91 +/- 8.95) was the highest (P < 0.05). SB (21.17 +/- 5.41) and EP (17.45 +/- 6.21) showed shear bond strengths higher than OCB (11.99 +/- 10.15) and PB (10.57 +/- 4.56) (P < 0.05).