Effect of Different Surface Treatments on Porcelain-Resin Bond Strength.

PURPOSE: The aim of this study was to evaluate the effects of various surface treatments on the surface structure and shear bond strength (SBS) of different ceramics. MATERIALS AND METHODS: A total of 192 disk-shaped cores were prepared using two all-ceramic systems, of which 168 were submitted to SBS tests, and 24 were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The ceramics used were IPS Empress e.max (EX) lithium glass-ceramic and Vita In-Ceram Zirconia glass-infiltrated zirconia (ICZ). The specimens were randomly divided into seven groups (n = 12) on the basis of the surface treatment used: control; SB-sandblasting with 50 µm Al2 O3 particles; CJ-chairside silica coating with 30 µm SiO2 particles and silanization (Clearfil Porcelain Bond Activator); HF-etching in 5% hydrofluoric acid and silanization; ER-etching with an Er:YAG laser (10 W); ND-Nd:YAG laser etching (0.8 W); and FS-etching with a femtosecond laser (860 mW). A luting cement (Clearfil Esthetic) was photopolymerized on each treated ceramic disk. After subjecting the specimens to thermocycling (1000 cycles, 5°C to 55°C), SBS tests were performed using a universal testing machine. The data were analyzed with two-way ANOVA and Tukey's tests using a significance limit of 5%. RESULTS: Among the EX ceramics, the CJ (29.10 MPa) and HF (26.07 MPa) specimens had statistically higher SBS values. For the ICZ ceramics, the highest value (28.08 MPa) was obtained for the CJ specimens. CONCLUSIONS: Silanization after coating with silica improves the bond strengths of both EX and ICZ specimens, while HF etching is favorable only for the EX specimens.

The effect of silane applied to glass ceramics on surface structure and bonding strength at different temperatures.

PURPOSE: To evaluate the effect of various surface treatments on the surface structure and shear bond strength (SBS) of different ceramics. MATERIALS AND METHODS: 288 specimens (lithium-disilicate, leucite-reinforced, and glass infiltrated zirconia) were first divided into two groups according to the resin cement used, and were later divided into four groups according to the given surface treatments: G1 (hydrofluoric acid (HF)+silane), G2 (silane alone-no heat-treatment), G3 (silane alone-then dried with 60℃ heat-treatment), and G4 (silane alone-then dried with 100℃ heat-treatment). Two different adhesive luting systems were applied onto the ceramic discs in all groups. SBS (in MPa) was calculated from the failure load per bonded area (in N/mm(2)). Subsequently, one specimen from each group was prepared for SEM evaluation of the separated-resin-ceramic interface. RESULTS: SBS values of G1 were significantly higher than those of the other groups in the lithium disilicate ceramic and leucite reinforced ceramic, and the SBS values of G4 and G1 were significantly higher than those of G2 and G3 in glass infiltrated zirconia. The three-way ANOVA revealed that the SBS values were significantly affected by the type of resin cement (P<.001). FIN ceramics had the highest rate of cohesive failure on the ceramic surfaces than other ceramic groups. AFM images showed that the surface treatment groups exhibited similar topographies, except the group treated with HF. CONCLUSION: The heat treatment was not sufficient to achieve high SBS values as compared with HF acid etching. The surface topography of ceramics was affected by surface treatments.

Effect of femtosecond laser beam angle on bond strength of zirconia-resin cement.

Yttrium-stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramic is widely used as an all-ceramic core material because of its enhanced mechanical and aesthetic properties. The bond strength of Y-TZP restorations affects long-term success; hence, surface treatment is required on ceramic boundaries. This study evaluated the effect of different laser beam angles on Y-TZP-resin cement shear bond strength (SBS). Forty plates of Y-TZP ceramics were randomly assigned to four groups (n = 10). A femtosecond amplifier laser pulse was applied on Y-TZP surface with different incidence angles (90°, 75°, 60°, 45°). The resin cement was adhered onto the zirconia surfaces. The SBS of each sample was measured using universal testing machine at crosshead speed of 1 mm/min. The SBS was analyzed through one-way analysis of variance (ANOVA)/Tukey tests. The results showed that the degree of laser beam angle affects the SBS of resin cement to Y-TZP. The laser beam was applied to a surface with a 45° angle which resulted in significantly higher SBS (18.2 ± 1.43 MPa) than other groups (at 90° angulation (10.79 ± 1.8 MPa), at 75° (13.48 ± 1.2 MPa) and at 60° (15.85 ± 0.81 MPa); p < 0.001). This study shows that decreasing of the angle between the ceramic surface and the laser beam increased the SBS between the resin cement and the ceramic material, as well as the orifice.

Effect of femtosecond laser treatment on the shear bond strength of a metal bracket to prepared porcelain surface.

OBJECTIVE: The aim of this study was to investigate the effects of femtosecond laser treatment (Group FS) on the shear bond strength (SBS) of a metal bracket to prepared porcelain surface, and to compare it with other surface treatment techniques [50 µm Al2O3 sandblasting (Group SB), 9.6% hydrofluoric acid gel (Group HF), and neodymium-doped yttrium aluminium garnet (Nd:YAG laser) (Group NY)]. BACKGROUND DATA: Because of the increasing number of adult patients in current orthodontic practice, achieving sufficient bond strength of composite resin to porcelain restorations without bond failure during the treatment is a challenge for orthodontists. METHODS: In total, 80 glazed feldspathic porcelain samples were prepared and randomly assigned to four groups of 20. Treated surfaces were treated with a silane agent. Brackets were bonded to porcelain samples. The specimens were stored in distilled water for 24 h and then thermocycled for 500 cycles between 5° and 55°C. The SBS of the brackets was tested with a universal testing machine at a crosshead speed of 1 mm/min, until bonding failure occurred. The data were analyzed statistically using analysis of variance (ANOVA) and Tamhane multiple comparisons tests. The results of ANOVA indicated that the SBS values varied according to the surface treatment method (p<0.001). RESULTS: Results of the Tamhane post-hoc tests indicated that the bond strength in Group NY (5.11±1.53) was significantly lower than the other groups (p<0.05). There were no statistically significant differences among Groups SB (9.07±3.76), HF (9.09±3.51), and FS (11.58±4.16) (p=0.28). CONCLUSIONS: The results of this study showed that FS treatment produced high SBS of the processes assessed; therefore, it appears to be an effective method for bonding orthodontic metal brackets to prepared porcelain surfaces.

Effects of Different Demineralization-Inhibiting Methods on the Shear Bond Strength of Glass-Ceramics.

PURPOSE: This in vitro study was undertaken to evaluate the effects of different demineralization-inhibiting methods on the shear bond strength (SBS) of glass-ceramics. MATERIALS AND METHODS: Ninety extracted intact human mandibular lateral insicors were randomly divided into six equal groups. Group C was left untreated, while enamel subsurface demineralization was induced in the other groups. In group D, porcelain discs (3 mm in diameter) were cemented to demineralized enamel by using total-etch photopolymerizing luting composite resin without pretreatment. Demineralized specimens in groups F, CA, M, and I were pretreated with fluoride gel, CPP-ACP paste, microabrasion, and resin infiltration, respectively, and then porcelain discs were cemented. SBS (MPa) was calculated from the failure load (N) per bonded area (mm(2)). Fracture types were examined by optical microscopy (40× magnification). Data were analyzed with ANOVA, Tukey's test, and G-test. RESULTS: ANOVA revealed significant intergroup differences (p < 0.01). No significant differences in SBS (MPa) were found between groups C (19.48 ± 2.0) and I (20.02 ± 1.6). Lower SBS values were recorded in groups D (7.93 ± 0.8), F (12.51 ± 1.5), CA (17.08 ± 1.3), and M (14.84 ± 1.4). Mixed and cohesive failures were the most prevalent in groups M and I, respectively. CONCLUSION: Resin infiltration enhanced the SBS of porcelain discs bonded to demineralized enamel when compared with the other demineralization-inhibiting methods. CLINICAL RELEVANCE: Resin infiltration could be useful to enhance adhesion of glass-ceramics to teeth with white spot lesions.

Porcelain laminate veneer conditioning for orthodontic bonding: SEM-EDX analysis.

The purpose of this in vitro study was to evaluate and compare the effects of different surface treatments and laser irradiation on the bond strength of brackets bonded to porcelain laminate veneer. Porcelain laminate veneer specimens were embedded in the centers of acrylic resin blocks. Thirty-nine teeth were used for shear bond strength testing and the remaining three (one tooth for each group) were used for evaluation of the debonded bracket interface. Specimens were randomly divided into three groups, each containing 13 specimens. The details of the groups are as follows: Group SB, sandblasting with alumina particles (50 µm); Group HFA, 9.6 % hydrofluoric acid etching; Group ER, erbium-doped yttrium-aluminum-garnet (Er: YAG) irradiation (from 1 mm distance, 2 W, 10 Hz for 10 s). After conditioning, the upper central brackets were bonded to the porcelain surfaces. Porcelain laminate veneers were examined under stereomicroscope for adhesive remnant index and surface damage after debonding. The highest shear bond strength values were obtained with Group HFA (10.8 ± 3.8 MPa) and Group ER (9.3 ± 1.5 MPa), whereas Group SB revealed the lowest values. Scanning electron microscopy energy-dispersive X-ray (SEM-EDX) analysis revealed that the silicon level in the porcelain decreased after debonding in all groups. The sandblasting method did not demonstrate any ideal bond strength values; however, the 9.6 % hydrofluoric acid etching and Er: YAG laser did. There were no significant differences among all groups in terms of laminate surface damages. The Er: YAG laser therefore can be selected for ideal bond strength and minimal damage to porcelain laminates.

Effect of Nd:YAG laser bleaching and antioxidizing agents on the shear bond strength of brackets.

OBJECTIVE: The aims of this study were to evaluate the effect of hydrogen peroxide bleaching agents, both nonactivated and activated by a neodymium:yttrium-aluminum-garnet (Nd:YAG) laser, and of antioxidant treatment on the shear bond strength (SBS) of orthodontic brackets. BACKGROUND DATA: Nd:YAG laser activation is expected to accelerate the bleaching therapy without decrease shear bond strength. MATERIALS AND METHODS: Ninety extracted maxillary central incisors were divided into two experimental groups and a control group. Group I was the control group, Group II was bleached with 35% hydrogen peroxide and had no photoactivation, and Group III was bleached with 35% hydrogen peroxide with activation by a Nd:YAG laser (4.0 W, 60 Hz frequency, 1 mm distance, 20 sec). Each group was divided into two subgroups: Subgroup A was immersed in artificial saliva for 2 weeks, and then bonded using the total etch system, whereas subgroup B was treated with an antioxidant agent (10% sodium ascorbate) and then bonded using the same system. The samples were stored in water for 24 h at 37°C, and thermocycled. The SBS in megapascals (MPa) was determined by a shear test with 1 mm/min crosshead speed, and failure types were classified with modified adhesive remnant index scores. The data were analyzed with two way analyses of variance, Tukey, and χ(2) tests at the α = 0.05 level. RESULTS: In both Groups II and III, the SBSs of brackets bonded after bleaching (Group II 15.16, Group III 17.50 MPa) were significantly lower than those of brackets in the bonded unbleached group (Group I 22.13 MPa); however, sodium ascorbate treatment significantly increased the SBSs of brackets in the bleached groups (Group II 21.52, Group III 22.43 MPa), but had an insignificant effect on the SBS of the control group (Group I 23.66MPa). CONCLUSIONS: Hydrogen peroxide bleaching agents reduce the SBSs both with and without Nd:YAG laser activation; however, treatment of the bleached enamel surface with 10% sodium ascorbate prior to bonding negates the effect.

Effects of different surface treatments on shear bond strength in two different ceramic systems.

The purpose of this study was to evaluate the influence of different surface treatments (sandblasting, acid etching, and laser irradiation) on the shear bond strength of lithium disilicate-based core (IPS Empress 2) and feldspathic ceramics (VITA VM 9). One hundred ceramic discs were divided into two groups of 50 discs each for two ceramic systems: IPS Empress 2 (group I) and VITA VM 9 (group II). Each of the two groups was further divided into five surface treatment groups (ten each) as follows: group SB, sandblasting with alumina particles (50 µm); group HF, 5 % hydrofluoric acid etching; group L, Er:YAG laser irradiation (distance, 1 mm; 500 mJ; 20 Hz; 10 W; manually, noncontact R14 handpiece); group SB-L, sandblasting + Er:YAG laser; and group HF-L, 5 % hydrofluoric acid + Er:YAG laser. Luting cement (Panavia 2.0) was bonded to the ceramic specimens using Teflon tubes. After 24 h of water storage, a shear bond strength test was performed using a universal testing machine at a crosshead speed of 0.5 mm/min. The data were analyzed with a two-way analysis of variance (ANOVA) and Tukey's honestly significant difference tests (α = 0.05). The two-way ANOVA indicated that the shear bond strength was significantly affected by the surface treatment methods (p < 0.05), but there was no significant interaction between the ceramic systems. Group SB-L had the highest mean values for each ceramic system. Sandblasting, followed by Er:YAG laser irradiation, enhanced the bond strength, indicating its potential use as an alternative method. The atomic force microscopic evaluation revealed that group SB had the most distinct sharp peaks among the groups.

Comparison of the effects of surface treatments on roughness of two ceramic systems.

OBJECTIVE: The aim of this study was to evaluate the effects of different surface treatments on the surface roughness of lithium disilicate-based core (IPS Empress 2, shade 210, Ivoclar Vivadent, Schaan, Liechtenstein) and feldspathic ceramics (Vita VM9, VITA Zahnfabrik H. Rauter GmbH & Co. KG, Bad Säckingen, Germany). BACKGROUND DATA: Er:YAG laser irradiation is expected to be an alternative surface treatment, thus enhances surface roughness of procelains and produces morphological changes. METHODS: Fifty lithium disilicate-based core ceramic discs and 50 feldspathic ceramic discs were prepared (diameter, 10 mm; thickness, 1 mm) according to the manufacturers' instructions. All-ceramic discs were polished to standardize, and surface roughness of the discs was evaluated before treatment and serving as controls. Both of two ceramic groups were divided into five groups (n=10), and the following treatments were applied: (1) sandblasting with aluminum oxide (Al(2)O(3); Group SB); (2) Al(2)O(3)+Er:YAG laser (Group SB-L); (3) Er:YAG laser irradiation (distance, 1 mm; 500 mJ; 20 Hz; 10W; manually, contact handpiece [R 14]) (Group L); (4) 5% hydrofluoric acid etching (Group HF); and (5) Er:YAG laser +5% hydrofluoric acid (Group HF-L). Surface roughness was evaluated by profilometry, and specimens were then examined with atomic force microscopy. RESULTS: Data were analyzed by Wilcoxon signed rank, Mann-Whitney U, and Kruskal-Wallis tests (α=0.05). The Wilcoxon signed rank test results indicated that surface roughness after sandblasting was significantly different from the surface roughness after laser irradiation and acid etching (p<0.001). Mann-Whitney U and Kruskal-Wallis test results indicated that groups SB and SB-L had significantly higher mean roughness values (p<0.05) than those in the other groups. CONCLUSIONS: Groups SB and SB-L had rougher surfaces than the groups subjected to the other surface treatment methods. There was no significant difference in surface roughness between the HF acid etching, Er:YAG laser irradiation, and HF and Er:YAG (p<0 .05).

Phospholipase and proteinase activities in different Candida species isolated from anatomically distinct sites of healthy adults.

The aim of the present study was to determine in vitro phospholipase and protease activities in 122 Candida spp. isolated from several anatomically distinct sites of healthy adults. C. albicans (66.4%) was the most frequently isolated Candida spp. C. glabrata (7.3%), C. tropicalis (6.3%) and C. kefyr (4.9%) were the most frequently isolated non-C. albicans Candida spp. Fifty (40.9%) of the isolates examined were phospholipase positive and 64 (52.4%) were protease positive. Forty-three (53.8%) of the C. albicans isolates tested were phospholipase producers--however, only a few strains of non-C. albicans Candida spp. behaved in the same way. Protease activity was detected in 46 (56.7%) of the C. albicans strains tested and in a few strains of non-C. albicans Candida spp. The levels of phospholipase and protease activities in commensal isolates were found to be lower than the levels of other enzyme activities previously reported in clinical Candida spp. isolates. The phospholipase activity of Candida spp. was found to be higher in oral (59.0%) and fecal (42.8%) isolates. The protease activity of Candida spp. was found to be higher in urogenital (55.1%) and skin (58.8%) isolates. We conclude that further investigations will be needed on the phospholipase and protease activity of Candida spp. in healthy subjects in order to clarify their contribution to fungal virulence.

Effects of melatonin on Candida sepsis in an experimental rat model.

As an immunomodulator, melatonin reportedly exhibits protective effects in severe sepsis/shock induced by bacterial lipopolysaccharides in animal models. The present study was conducted to evaluate the possible protective effects of melatonin against experimental Candida sepsis in rats. A total of 40 adult male Wistar rats were randomly assigned to 4 groups: control, melatonin-treated control, septic, and melatonin-treated septic. Melatonin (200 microg/kg/d, intraperitoneally) injections were begun a week prior to sepsis induction and were continued daily for 3 wk until the end of the study. Cyclophosphamide was administered to animals in all groups as an immunosuppressive agent as a single dose 4 d prior to yeast inoculation. To cause sepsis, the Candida albicans (ATCC 10259) strain was administered intravenously. Amphotericin B was given as an antimycotic therapeutic agent as a single dose to septic rats. Plasma levels of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), vascular cell adhesion molecule-1, and E-selectin were measured on the first and 15th days of sepsis. IL-6, TNF-alpha, vascular cell adhesion molecule-1, and E-selectin levels of septic rats were higher than those of controls. Melatonin reduced IL-6 levels and shortened time to improvement in animals with Candida sepsis. Levels of TNF-alpha and adhesion molecules in melatonin-treated septic rats were decreased compared with those in septic rats, but this difference was not statistically significant. In light of the current results, investigators conclude that melatonin may have therapeutic benefits in Candida sepsis and in classic antimycotic treatment because of its immune regulatory effects.

Anti-Müllerian hormone levels during hormonal contraception in women with polycystic ovary syndrome.

OBJECTIVE: The use of oral contraceptive (OC) pills alters the characteristic features of polycystic ovary syndrome (PCOS) complicating the diagnosis of this disease. Anti-Müllerian hormone (AMH) levels are high in PCOS patients and are stable throughout the menstrual cycle in healthy subjects. This study examined the influence of hormonal suppression with OC therapy on the serum AMH levels in women with PCOS and with normal menstrual cycles. STUDY DESIGN: Thirty women with PCOS and 15 women with normal menstrual cycles were enrolled in this prospective study. Serum was collected from the subjects during the early follicular phase of the menstrual cycle and after the sixth cycle of oral contraceptive therapy, and stored frozen until assayed. The effect of OC therapy on the serum AMH, estradiol (E(2)), luteinizing hormone (LH), follicle-stimulating hormone (FSH), free testosterone, total testosterone, and dehydroepiandrosterone sulfate (DHEA-S) levels was studied. In addition, ovarian volume and follicle count were assessed. RESULTS: The serum AMH levels in PCOS patients were significantly higher than in healthy women at baseline (+/-S.D.; 5.49+/-2.26 and 1.93+/-0.51 ng/ml, respectively; p=0.001). After six cycles of OC therapy, no significant changes in the AMH levels were observed in either the PCOS patients or normally cycling women. Ultrasound showed significant reductions in ovarian volume and follicle number and size at 6 months in both groups. CONCLUSION: Although significant reductions were observed in ovarian volume and follicle number, 6 months of contraceptive therapy did not change the serum AMH concentration in either group. AMH may be considered a new marker in PCOS patients who are already on contraceptive treatment.

Nasal carriage of pathogenic bacteria in medical students: effects of clinic exposure on prevalence and antibiotic susceptibility.

Staphylococcus aureus is a major cause of community-acquired and nosocomial infections worldwide. One important source of this pathogen for nosocomial infections is the nasal carriage of S. aureus among hospital personnel. There are only a few studies investigating the carriage of S. aureus in a community of medical students. Oral and nasal flora of 179 medical students with varying clinical exposures were determined. Oral cultures revealed no nosocomial pathogen and nasal cultures showed an increasing rate of S. aureus carriage with increasing clinical exposure. Methicillin resistance also demonstrated a tendency toward increasing with increasing clinical exposure.

Etiologic agents of cervicovaginitis in Turkish women.

OBJECTIVE: To investigate the distribution of microbiologic agents causing cervicovaginitis. METHODS: We conducted the study between October 2002 and December 2004 in Abant Izzet Baysal University, Duzce School of Medicine Hospital, Turkey. The samples were obtained from the posterior vaginal fornix and cervix by swabs in 828 patients. Direct microscopic examination, culture and enzyme immune assay (EIA) methods were performed in all patients for diagnosis of microbiologic agents. RESULTS: Gardnerella vaginalis (G. vaginalis) were diagnosed in 254 (30.7%) patients, Candida albicans (C. albicans) in 152 (18.4%), Candida glabrata (C. glabrata) in 36 (4.3%), Candida species in 52 (6.3%), Staphylococcus aureus (S. aureus) in 62 (7.5%), Streptococcus group B in 28 (3.4%), Escherichia coli (E. coli) in 42 (5.1%), Klebsiella species in 24 (2.9%), and Streptococcus group D in 8 (1%) patients in culture. Less frequent enterobacteria in 30 (3.6%) were: Pseudomonas species, Proteus species Enterobacter species, Hafnia alvei and Nonfermenter species. Neisseria gonorrheae (N. gonorrheae) was detected in one patient (0.1%) in culture. The Chlamydia trachomatis (C. trachomatis) antigen was detected by EIA methods in 130 (15.7%) patients and Trichomonas vaginalis (T. vaginalis) was observed in 8 (1%) patients by direct microscopic examination. CONCLUSION: Performing the etiologic diagnosis of cervicovaginitis is necessary in order to take appropriate therapeutic and preventive measures. Therefore, we recommend G. vaginalis, C. albicans and C. trachomatis should be investigated in patients having a diagnosis of cervicovaginitis in our population, since these were detected in a considerable number of cases. Additionally, C. glabrata and T. vaginalis should be kept in mind as possible pathogens.

Seroprevalence of varicella, measles and hepatitis B among female health care workers of childbearing age.

To evaluate the relation between infectious agents and reproductive health hazards for health care workers (HCWs), a cross-sectional study consisting of 73 HCWs and 65 bureau workers was conducted. The reproductive health problems of both groups were compared using a questionnaire, and serologic examinations for measles, varicella and hepatitis B were performed. There were no differences between the two groups according to the rate of seropositivity of measles and varicella (P > 0.05). The prevalence of anti-HBc seropositivity was significantly higher among HCWs than controls (31.5 versus 16.9%). There were no differences between seropositive and seronegative subgroups of measles, varicella and hepatitis B regarding the rates of normal delivery time, preterm and postterm delivery and stillbirth. Subjects seropositive for anti-HBc showed a higher spontaneous abortion rate than those who were seronegative (38.2 versus 16.3, P = 0.009). Although these data showed that HCWs had a high rate of anti-HBc seropositivity and that the rate of spontaneous abortion was associated with past hepatitis B virus infection, further studies including larger populations are needed. We considered that it should be strongly recommended that all HCWs be vaccinated against this virus, and future studies should be focused on the relationship between infectious diseases and reproductive health problems in HCWs.