Shear bond strength of amalgam adhesives to dentin

Recent studies have suggested that failure of pentamidine prophylaxis against Pneumocystis carinii pneumonia (PCP) may be due to reduced deposition of pentamidine in the upper lobes. In this study, we performed bronchoalveolar lavage from the apical segment of the upper lobe and the middle lobe in 51 HIV-positive patients, all of whom were receiving prophylaxis with aerosolized pentamidine, who had presented with acute respiratory symptoms. Lavage fluid from each lobe was assayed for pentamidine using high-performance liquid chromatography (HPLC). The number of clusters of P carinii were counted after staining with a Wright-Giemsa stain. The patients were subclassified as PCP-positive (32 patients) and PCP-negative (19 patients) on the basis of the presence/absence of P carinii clusters in their BAL fluid. The concentration of pentamidine in the upper lobe compared with the middle lobe was no different (using paired Student's t tests) for either PCP-positive patients or PCP-negative patients. In comparing the positive with the negative subjects, using unpaired Student's t test, there was no difference in the concentration of pentamidine in the upper lobe or the middle lobe. For PCP-positive patients, the numbers of P carinii clusters were on average higher in the upper lobes (mean +/- SD: upper = 14.9 +/- 16.6, middle 7.5 +/- 10.8, p = 0.013, paired Student's t test), but there was no correlation between lobar P carinii cluster counts and pentamidine levels. We conclude that the absence of a relationship between cluster count and pentamidine level, the similarity in regional pentamidine levels between upper and middle lobes, as well as the similarity in pentamidine levels between the PCP-positive and PCP-negative groups indicate that the regional dose of pentamidine is not the determining factor as to whether aerosolized pentamidine prophylaxis will succeed or fail.     

Dentastic bond strength to dentin

PURPOSE: To evaluate the shear bond strength to the dentin of permanent teeth and failure site of Dentastic hydrophilic dentin bonding agent. MATERIALS AND METHODS: Forty permanent noncarious molar teeth stored in distilled water were obtained. The teeth were cleaned with pumice and a rubber cup. The mesio-buccal surface of the teeth was ground flat with hand pressure with a series of SiC paper ending with the 600 grit to provide a uniform surface on dentin to which the resin composite could be applied. After preparing the tooth surface, the teeth were stored in distilled water for 48 hours. They were then divided at random into four groups of 10 specimens each: Group 1: Dentastic, five coats of primer; Group 2: Dentastic, three coats of primer; Group 3: Dentastic, five coats of primer, light-cured adhesive before resin bonding; Group 4: Dentastic, three coats of primer, light-cured adhesive before resin bonding. All specimens were thermocycled (500x) and sheared in a testing machine. After shear testing, the debonded sites of all samples were examined with a stereomicroscope and a scanning electron microscope. RESULTS: The results in MPa were: Group 1: 22.63 +/- 6.24; Group 2: 23.35 +/- 5.14; Group 3: 23.58 +/- 5.66; Group 4: 27.26 +/- 8.22. ANOVA and Student-Newman-Keuls showed no statistically significant difference between the groups. In all groups, all specimens failed at the dentin (dentin cohesive failure = dentin fracture) or at the resin (resin cohesive failure = resin fracture). This means that the bond strength of the product is stronger than the cohesive strengths of the dentin and the resin.     

Effect of disinfectants on the bond strength of composite to dentin

The article describes ultrasonographic (US), computed tomographic (CT), 99mTc-MIBI and angiographic findings of 16 cases of multiple endocrine neoplasia (MEN) confirmed by operations and pathological examinations. Hyperparathyroidism either was the first manifestation of MEN I or was diagnosed simultaneously with other tumors. Medullary thyroid carcinoma usually developed first or coincided with pheochromocytoma in MEN I. Regular US and CT screening can lead to the detection of new endocrine neoplasia. The authors consider that US and CT are the best imaging methods for MEN.     

Shear bond strength of amalgam and gallium alloys to dentine

The purpose of this in vitro investigation was to determine the shear bond strength of admixed (Dispersalloy), irregular (Oralloy) and spherical (Lojic) amalgams, as well as an admixed gallium alloy (Galloy) to superficial, buccal, human dentine surfaces, using the Scotchbond Multi-Purpose Plus system. The bonds were stressed to failure in an Instron testing machine after 48 hours, and the following values (MPa) were obtained: Admixed = 7.74 +/- 0.7; Irregular = 9.47 +/- 1.4; Spherical = 9.82 +/- 2.4; Galloy = 11.03 +/- 2.5. Data were statistically analysed and fracture sites examined in a scanning electron microscope. Galloy demonstrated a statistical significant higher shear bond strength than to the other types of amalgams (p < 0.01).     

The effect of dentin primer on the tensile bond strength to human enamel

Four third-generation dentin bonding products (Scotchbond Multi-Purpose, Optibond, All-Bond 2, and Prisma Universal Bond 3) were tested to evaluate their tensile bond strength to enamel. Test enamel specimens were etched, primed, and polymerized according to each manufacturer's directions. Control specimens were treated identically except the primer application was eliminated. The results demonstrated that the dentin primer significantly increased the tensile bond strength of All-Bond 2, significantly decreased the tensile bond strength of Scotchbond Multi-Purpose and Optibond, and had no significant effect for Prisma Universal Bond 3. A one-way analysis of variance was run between the eight groups tested, and three significant subsets were found (P < .05). The subset with the highest mean tensile bond strengths consisted of Prisma Universal Bond 3 primed and nonprimed, All-Bond 2 primed, and Optibond nonprimed.     

Compomers and glass ionomers: bond strength to dentin and mechanical properties

Twenty-six patients with newly diagnosed ALL (age range 15-49 years, median 32 years) received treatment comprising: cycles 1 and 2: adriamycin 30 mg/m2 days 1-3, vincristine: 2 mg days 1, 8, and 15, with prednisolone 40 mg daily, given until complete remission (CR). L-asparaginase 10000 units/m2, days 1-14, was given only with the first cycle. Cycle 3 consisted of 100 mg/m2 etoposide orally, days 1-5, and 1 gm/m2 bd cytosine arabinoside (ara-C) days 1-5. Cycles 1-3 were then repeated. Intrathecal methotrexate (MTX) 12.5 mg was given on day 1 of each treatment cycle. The first 12 consecutive patients received this chemotherapy alone, the subsequent 14 received, in addition, 3 micrograms/kg GM-CSF subcutaneously, from day 4 of cycles 1,2,4 and 5 (and from day 6 of cycles 3 and 6) until the absolute neutrophil count had reached 0.5 x 10(9)/1. All patients in whom CR was achieved then received prophylactic cranial irradiation. With the exception of those with T-ALL, this was followed by oral maintenance therapy consisting of 6-mercaptopurine, MTX, and cyclophosphamide for 3 years. Patients receiving GM-CSF did not have shorter intercycle times or a lower incidence of documented infections than those who did not receive it. The CR rate was 89% overall-uninfluenced by GM-CSF, but higher than that achieved previously at St Bartholomew's Hospital in an equivalent age-group.     

Dyes for caries detection influence sound dentin bond strength

This study evaluated the influence of caries-detection dyes on the in vitro tensile bond strength of adhesive materials to sound dentin. Caries-free human molars were ground to expose superficial dentin. Two dyes (a commercial 0.5% basic fuchsin in propylene glycol and Cari-D-Tect) were applied to sound dentin and rinsed. Subsequently, the dentin was etched with phosphoric acid (35%) and rinsed, leaving a moist dentin surface. The adhesive (Prime & Bond 2.0) was applied in two layers and light cured. A composite (TPH Spectrum), a compomer (Dyract), and a hybrid ionomer (Advance) were used to prepare the bond-strength specimens with a 3-mm-in-diameter bonding area. Control groups were made without use of dyes. Six specimens were prepared for each group. After 24 hours in distilled water, tensile bond strength (MPa) was measured using a testing machine. Analysis of variance was used to evaluate the data. Without dyes, bond strengths of TPH Spectrum and Dyract with Prime and Bond 2.0 were similar and both values were significantly (P < 0.05) higher than that of Advance with Prime & Bond 2.0. Dyes for caries detection reduced the bond strength of TPH Spectrum and Dyract but not Advance when used with Prime and Bond 2.0.     

An investigation on the shear bond strength of one dentin adhesive at two different dentin depths

The aim of this investigation was to study the effect of dentin depth and patient's age on the shear bond strength of one dentin adhesive (ART Bond), using an Instron Universal testing machine at a cross-head speed of 0.5 mm/min. Forty human molar teeth were used and were divided into two main groups, twenty each representing two age groups of patients, i.e., between 20 to 30 years and between 30-40 years of age. Every group was further subdivided into two subgroups of different dentin depths, i.e., superficial and deep. Results were recorded in Kg/Cm2 and converted into MPa units, then tabulated and statistically analyzed. A Duncan's range statistic test at P < or = 0.05 showed statistically significant differences between the bond strength values for both age groups at different dentin depths, with the superficial dentin showing higher bond values, and there were also statistically significant differences between the bond strength values of the two age groups at the same dentin depth, with the older age group showing higher bond values.     

The effect of air abrasion on shear bond strength to dentin with dental adhesives

This study compared the effects of different dentin surface treatments on the shear bond strengths of three adhesive systems. The adhesive systems included a resin-modified glass ionomer, Fuji II LC, and two dentin bonding systems, One Step and Scotchbond Multi-Purpose Plus. The surface treatments compared for each adhesive system were as follows: 1) the controls, which were conditioned, 2) air abrasion at 120 psi without conditioning, 3) air abrasion at 160 psi without conditioning, 4) air abrasion at 120 psi with conditioning, and 5) air abrasion at 160 psi with conditioning. The KCP 1000 Whisperjet was used for all air-abrasive specimens. Controls for each adhesive material (Fuji II LC, One Step, Scotchbond Multi-Purpose Plus) were bonded using manufacturers' recommendations. Results showed that air abrasion significantly lowered bond strength of the resin-modified glass ionomer, conditioned or nonconditioned (P < 0.01). Air abrasion alone significantly lowered bond strengths of the dentin bonding agent systems (P < 0.01). However, air abrasion plus conditioning of the dentin surface resulted in bond strengths that were similar to the conditioned-only specimens (P < 0.01).     

Dual application of dentin bonding agents: effect on bond strength

The objective of this paper is to provide an ethical analysis of the concept of the fetus as a patient and to identify the clinical implications of this concept for maternal-fetal medicine. The principles of beneficence and respect for autonomy are applied to the viable and previable fetus. We argue that the viable fetus is a fetal patient. The previable fetus is a fetal patient only when the pregnant woman confers such status on it. When the fetus is a patient, directive counseling for fetal benefit is ethically justified. When the fetus is not a patient, counseling should be non-directive.     

The effect of dentin disinfectants on shear bond strength of resin-modified glass-ionomer materials

The purpose of this study was to investigate the effect of dentinal disinfection with a 2% chlorhexidine or a 0.11% I2-KI/CuSO4 solution on the shear bond strength of three resin-modified glass-ionomer cements: Fuji II LC, Photac-Fil, and Vitremer. The occlusal surfaces of extracted human teeth were flattened to dentin. Specimens were randomly assigned to one of nine treatment groups (n = 12). For each glass-ionomer material, there was a control group and two treatment groups in which the dentin was treated with either a 2% chlorhexidine or a 0.11% I2-KI/CuSO4 solution before the dentin was treated with the recommended dentin conditioner prior to glass-ionomer bonding. Specimens were stored for 1 day in water, thermocycled, and tested in shear until failure. The chlorhexidine solution did not significantly affect the shear bond strengths of any of the cements, but the I2-KI/CuSO4 solution significantly lowered the bond strengths of Vitremer and Fuji II LC compared to the controls.     

Effect of application technique and dentin bonding agent interaction on shear bond strength

This study evaluated the interaction of five clinical application techniques and the shear bond strength of four DBAs (OptiBond FL, Clearfil SE Bond, PQ1 and Prime & Bond NT). A hybrid resin composite (Herculite XRV restorative resin) was attached to human dentin surfaces using five application techniques: Group A--adhesive spread with a 3M brush for 30 seconds, followed by compressed air 0.5 cm from the surface for one second to remove the excess adhesive. Group B--adhesive spread with a 3M brush for 30 seconds, followed by compressed air 0.5 cm from the surface for three seconds to remove the excess adhesive. Group C--adhesive spread with 3M brush for 30 seconds, excess adhesive removed with a clean brush, two strokes side by side, no compressed air. Group D--adhesive spread with a Micro-applicator brush for 30 seconds followed by compressed air 0.5 cm from the surface for one second to remove the excess adhesive. Group E--adhesive spread with a Micro-applicator brush for 30 seconds, the excess adhesive removed with a clean brush, two strokes side by side and no compressed air. The specimens were stored in distilled water at 37 degrees C for 24 hours, followed by thermocycling between 5 degrees C and 55 degrees C for 1,000 cycles. The shear bond strengths were determined on a universal testing machine operating with a crosshead speed of 5 mm/minute. The fracture sites were examined by 20x stereo microscope to determine the type of failure that occurred during the debonding procedure. Bond strength data were compared with analysis of variance at a significance level of p<0.05. Post hoc comparisons of means were performed with t-tests with p-values adjusted for multiple comparisons. This in vitro study concluded that there was an interaction between the application technique and bonding agent tested. All DBAs utilized the one-second compressed air technique, which yielded the highest bond strengths.     

Shear bond strength of orthodontic brackets cemented with a zinc oxide-polyvinyl cement

The purpose of this study was to compare the shear bond strengths and enamel surface structure after debonding a conventional metal bracket and a polycrystalline ceramic bracket bonded with a bipolar zinc oxide-polyvinyl cement (F-21) or a light-cured resin cement (Transbond). Forty extracted human premolars were used. The buccal enamel surfaces were used, and the teeth randomly divided into four groups of 10 teeth each: group 1: conventional metal bracket (Unitek) bonded with Transbond; group 2: metal bracket bonded with F-21; group 3: ceramic bracket (Transcend 2000) bonded with Transbond; and group 4: ceramic bracket bonded with F-21. The brackets were bonded to the etched enamel surfaces according to manufacturer's instructions. All specimens were stored in distilled water for 24 hours and then thermocycled for 300 cycles between 5 degrees C and 55 degrees C. The specimens were mounted in dental stone and placed in the Instron at a crosshead speed of 0.5 mm/min with a knife-edged blade. Immediately after debonding, the enamel surface and bracket-enamel interface were evaluated visually and with a stereomicroscope. Representative samples were then examined with the scanning electron microscope. The analysis of variance and Student-Newman-Keuls tests were performed. The results in megapascals were Group 1: 19,6 (+/- 9,6); group 2: 14,3 (+/- 4,6); group 3: 28,8 (+/- 12,6); and group 4: 18,5 (+/- 7,5). Group 3 was statistically significantly different (P < 0.008) from all other groups. Groups 1, 2, and 4 were not significantly different.(ABSTRACT TRUNCATED AT 250 WORDS)     

Bond strength to crown and root dentin

PURPOSE: To investigate (1) the tensile bond strengths of four commercial dentin bonding systems to bovine crown and root dentin and (2) the structure of the hybrid layers for each system bonded to the two dentin substrates. MATERIALS AND METHODS: Superficial surfaces were exposed in bovine crown and root dentin. The teeth were embedded in plaster and a 3 mm diameter bonding area was demarcated. The four bonding systems used were All-Bond 2, Super-Bond D-Liner Plus, Clearfil Liner Bond II, and ProBond. Bonding procedures followed the manufacturers' instructions with the exception of Super-Bond D-Liner Plus where the primer was left in situ for 60 seconds. Tensile bond strengths were tested after 24-hour storage in 37 degrees C deionized water. Specimens were also prepared for SEM observation of the hybrid layer, after treatment with 10% phosphoric acid, and 10% phosphoric acid and 5% sodium hypochlorite. RESULTS: Statistically lower bond strengths to crown dentin when compared with root dentin were observed for All-Bond 2, whereas Liner Bond II showed the opposite (P < 0.01). Both ProBond and Super-Bond D-Liner Plus showed no statistical differences between crown and root dentin (P > 0.05). Hybrid layers could be observed for All-Bond 2, Liner Bond II and Super-Bond D-Liner Plus, with no apparent differences between the hybrid layers of crown and root dentin. In the case of ProBond, where the smear layer was not removed during the priming stage, it appeared that the primer had infiltrated and caused hybridization of the smear layer. The differences in bond strength were thought to be related to the different bonding mechanisms of each material, as well as possible variations in the crown and root dentin substrates.     

Methods used in dentin bonding tests: an analysis of 50 investigations on bond strength

Researchers have carried out a variety of investigations to determine the properties of available dentin bonding systems. The test methods and variables used in 50 published investigations of bond strength were analyzed. Among the studies analyzed, shear tests predominated, being used in 80% of the studies; dentin from human molar teeth was used most often (in 88% of investigations); and the most prevalent time of testing was 24 hours postcuring. However, a number of potential variables were not recorded in a high proportion of articles, among these the film thickness, the type of dentin tested, and the surface condition (moist or dry). The mode of failure was recorded in only 42% of the investigations assessed. It was found that there is little standardization of test methods in studies of dentin bond strength and that a number of variables are often either not recorded or reported.     

Initial tensile bond strength of resin-modified glass ionomers and polyacid-modified resins on perfused primary dentin

The objective of this study was to evaluate the initial tensile bond strength of a resin-modified glass ionomer (Photac-Fil) and two polyacid-modified composite resins (Compoglass, Dyract) to primary dentin. A hybrid composite resin (Tetric) and two chemical cured glass ionomers (BaseLine, Hi-Dense) served as controls. Ninety caries-free dentinal discs were ground flat and perfused with Ringer's solution. Dentinal surfaces were conditioned (except for Base Line). From each material, fifteen standardized specimens were attached to the dentin. Light-curing of the respective materials followed (1 min), and adhesion was tested with a universal testing machine 15 min after application. The highest initial bond strength was observed with Tetric (5.17 MPa). Closed test procedure (Kruskal-Wallis) showed significant differences between all materials (P < 0.05), except for Compoglass (1.82 MPa) vs. Dyract (2.35 MPa), and BaseLine (0.37 MPa) vs. Photac-Fil (0.42 MPa). The condensable glass ionomer Hi-Dense revealed a mean tensile bond strength of 0.79 MPa. Adhesion of (polyacid-modified) composite resins is superior to the other tested glass ionomer materials, when applied to perfused primary dentin.     

The influence of the depth of substrate dentin surface and thickness of the current restorative samples on bond strength

The effect of sample thickness and dentin depth on bond strength of composite, compomer and resin modified glass ionomer have been investigated. The occlusal surfaces of 84 non carious human third molars were used for bonding. 4 subgroups were tested, superficial dentin with sample thickness 1 and 2 mm and deep dentin with sample thickness 1 and 2 mm respectively SBMP + /Z 100 composite showed 26 +/- 3.2, 22.3 +/- 4.5, 17 +/- 3.2 and 21.8 +/- 4.2 MPa shear bond strength to S. dentin 1 mm, deep dentin 1 and 2 mm and S. dentin 2 mm respectively. Compoglass reported 10.4 +/- 1.57, 9.1 +/- 2.3, 5.0 +/- 0.6 and 9.24 +/- 3.1 MPa while, Vitremer achieved 4.7 +/- 0.49, 3.2 +/- 0.39, 3.0 +/- 0.81 and 3.2 +/- 0.53 MPa. It is concluded that the highest bond strength can be achieved to superficial dentin in thickness or increments not more than 1 mm. And that both dentin depth and sample thickness might influence the quality of the bond to dentin with an effect that varies from one material to another depending upon the mechanism of bond of each material and its chemical composition.     

Bond strength and interfacial morphology of adhesives to primary teeth dentin

PURPOSES: To evaluate (1) the shear bond strength to the dentin of primary teeth and failure site of hydrophilic dentin bonding agents, (2) the interfacial micromorphology of these adhesives on primary teeth. MATERIALS AND METHODS: Seventy-six primary noncarious molars stored in distilled water were obtained. The teeth were cleaned with pumice and a rubber cup. The mesio-buccal surface of the teeth was ground flat with hand pressure with a series of SiC paper ending with the 600 grit to provide a uniform surface on superficial dentin to which the adhesives and resin composite could be applied. After preparing the dentin surface, the teeth were stored in distilled water for 48 hours. They were then rinsed and dried with compressed air and divided at random into four groups of 16 specimens each: Group 1: Dentastic; Group 2: One-Step; Group 3: Prime & Bond 2.0; Group 4: Compoglass SCA. Z100 resin was used in all groups. All specimens were thermocycled (500x) and sheared in an Instron machine. After shear testing, the debonding sites of all samples were examined with a stereomicroscope and selected samples were also examined with the scanning electron microscope. Three additional samples per group were used to evaluate the resin adaptation to dentin. RESULTS: The results in MPa were: Dentastic 19.62 (4.67); One-Step 11.24 (3.67), Prime & Bond 22.38 (6.47), Compoglass SCA 18.88 (4.04). ANOVA (P < 0.0001) revealed that there was a significant difference between the groups. The Student-Newman-Keuls test (P < 0.05) showed no statistically significant difference between Dentastic, Prime & Bond and Compoglass SCA. However, these three groups were statistically significantly higher than One Step. In the Dentastic group, 14 of 16 samples revealed resin cohesive failure (resin fracture) while two of 16 displayed dentin cohesive failure (dentin fracture). In the One Step group, 15 samples failed at the resin and one sample showed dentin cohesive failure. In the Prime & Bond group, 12 specimens revealed resin cohesive failure while four displayed dentin cohesive failure. In the Compoglass SCA group, 13 samples had resin cohesive failures while three had dentin cohesive failures. All samples revealed an intimate adaptation to the dentin displaying resin tag formation.     

Effects of argon laser curing on dentin shear bond strengths

Previous studies have demonstrated the ability of the argon laser to polymerize light-activated materials and improve enamel shear bond strengths. This study was conducted to evaluate the effects of the argon laser on dentin shear bond strengths of current dentin bonding systems. Argon laser (HGM Model 8) at 231 and 280 mW, 5 sec bonding agent, 10 sec composite, and a conventional curing light (Translux EC/Kulzer) at 10 sec bonding agent, 20 sec composite were used to polymerize samples of dentin bonding systems [Scotchbond Multi-Purpose Plus (3M) and Prime Bond (Dentsply/Caulk), both with TPH (Dentsply/Caulk) composite]. A flat dentin bonding site (600 grit) was prepared on the buccal surface of extracted human teeth. Twelve samples were made for each set of parameters for both laser and conventional light totaling 48 samples. Samples were stored in distilled water in light-proof containers for 24 h at 37 degrees C. Shear bond strengths (MPa) were determined for each sample on the Instron testing machine. Mean values were calculated for each set of data and ANOVA with Fisher PLSD were used for statistical analysis. The argon laser provided bond strengths that were 21-24% greater than those of the conventional curing light system.