Shear bond strength of resin bonded to bleached enamel using different modified 35% hydrogen peroxides

Statement of Problem: Bleaching systems with different concentrations and applications are widely used to improve the visual appearance of the teeth, but one of the complications of these materials is reduction of bond strength for immediately bonding to the bleached enamel

Objective: The aim of this study was to evaluate the influence of using different modified hydrogen peroxide bleaching agents on the shear bond strength of composite resin bonded to the bleached enamel

Materials and Methods: Forty-eight sound extracted premolar teeth were collected, sectioned 1 mm below the CEJ to detach the root. The proximal surfaces of the teeth were flattened using diamond disks and silicon carbide papers to achieve flat homogeneous enamel surfaces without exposure to the dentin. The teeth were randomly divided into four groups as follows [n = 12]: group 1: bleaching with 35% hydrogen peroxide gel; group 2: bleaching with 35% hydrogen peroxide gel contained [casein phosphopeptide-amorphous calcium phosphate [CPP-ACP]; group 3: bleaching with 35% hydrogen peroxide gel combined with fluoride; and group 4: bleaching with 35% hydrogen peroxide applying one week before resin restoration placement. Composite resin, Clearfil AP-X [Kuraray, Tokyo, Japan], was bonded on each tooth in the mould [4 mm diameter × 3 mm height] using Clearfil SE Bond [Kuraray, Tokyo, Japan]. After 24 hours of storage and 1000 cycles of thermocycling, the shear bond strength of the specimens at a cross-head speed of 0.5 mm/min was measured in MPa. Data were analyzed using ANOVA and Tukey's post-hoc test

Results: The minimum and maximum mean shear bond strength values were observed in groups 2 [15.82 +/- 4.41] and 4 [21.00 +/- 3.90], respectively. Multiple comparisons of groups revealed no significant differences among the groups except between group 4 and all the other groups. The most common type of failure was adhesive

Conclusion: Using modified bleaching agents decreased the bond strength of the composite resin to the enamel when it was used immediately after bleaching

[ effect of eight weeks selected aerobic exercise on liver parenchyma and liver enzymes [AST, ALT] of fat liver patients]

Fatty liver disease is a kind of fat accumulation in the liver cells which uncontrolled subjects have a trend to parenchymal fibrosis and cell death. This study aimed to investigate the effect of eight weeks elected aerobic exercise on the levels of AST, ALT enzymes and liver parenchyma of male patients with fatty liver, aged 20 to 45 years in Shooshtar, Iran. In this study, 24 patients referred to sonography clinics of Shooshtar, Iran with the diagnosis of fatty liver disease were selected randomly and divided to control and experimental groups. The serum ALT and AST were measured and liver sonography was done before intervention in both groups. After eight weeks aerobic exercise with intensity of 50 to 70 VO2 Max in case group, the tests were performed for both groups. Descriptive analysis and t-test were performed using SPSS. The results showed that ecogenesity of liver parenchyma was decreased in the post-test in comparison to pre-test [83.2%] and the serum AST and ALT of experimental group were decreased in comparison to control group [P<0.05]. It can be concluded that eight weeks aerobic exercise has significant effects on the fatty liver disease

[Psychosis secondary to traumatic brain injury with manifestation of prominent grandiosity delusion: a case study with a 4-month follow-up]

Traumatic brain injury [TBI] has been known as one of rare etiological factors of psychotic disorder. In this case study we investigated the trend of evaluation, diagnosis and treatment of a patient with psychosis secondary to TBI who developed prominent grandiosity delusion. The patient was a young 35-year-old man who was hospitalized due to a motorcycle accident and developed decreased level of consciousness, restlessness and nausea. CT findings indicated contusion of the left temporal lobe. Moreover, loss of consciousness [LOC], cognitive impairment, post-traumatic amnesia [PTA], disorientation, lack of attention and concentration, memory disturbances, aggression and grandiosity delusions were observed during psychological evaluations. 27 days after TBI, he was diagnosed as a case of psychosis secondary to TBI based on DSM-IV-TR in psychiatric examinations. Then, the patient gradually recovered after medical treatment and the symptoms of injury disappeared during a follow-up period of 4 months. Presentation and treatment of this patient cannot clarify the vague relationship between TBI and psychosis secondary to TBI; however, the results of this study emphasize the importance of psychological evaluations, investigation of serious symptoms of mental disorders, monitoring and protection of these patients for proper treatment. Identifying the risk factors of secondary psychosis complicating TBI can be helpful to rule out differential diagnoses, detect those with higher risk of psychosis and facilitate timely implementation of management strategies for this disorder before the onset of its advanced symptoms

[Evaluation of the effect of pre- and post-topical fluoride treatment on marginal microleakage of resin composite and glass ionomer restorations]

Fluoride has popularly been used as a caries prevention agent. This study evaluates the effect of fluoride gel [APF] on microleakage before and after restoration placement of tooth colored restorations. Eighty-four standard class V cavities were prepared and the specimens were randomly divided into three groups [n=14]: Group 1-APF employed before cavity preparation; Group2-APF employed after completed restoration: Group3- without APF application [control]. Buccal cavities were restored with OptiBond Solo adhesive system and Herculite XRV composite resin and lingual cavities were restored with Fuji II LC Glass ionomer. After finishing and polishing, thermal cycling followed by immersion in 0.5% basic fuchsin dye was performed. Then, the specimens were sectioned and microleakage was ranked under magnification [x40]. Two teeth of each group were treated for SEM observation. Data were subjected to statistical analysis using Kruskal Wallis and Wilcoxon tests. There were significant differences in enamel marginal microleakage of composite [14.68] and glass ionomer [16.00] restorations [p=0.02], but they similarly proceeded in dentinal margins [0.921]. The dentinal margins [2.50] of the glass ionomer in control group showed more leakage than the enamel margins [0.00] [p=0.04]. All experimental groups; either before or after fluoride therapy, showed similar microleakage in the enamel and dentinal margins. APF employed was ineffective on microleakage before and after composite resin restoration placement. Microleakage could increase in enamel margins of resin modified glass ionomer restoration with fluoride therapy protocol

[Microleakage in core build up composite resins]

Composite resin cores with pre-fabricated posts are commonly used to restore endodontically treated teeth. This study compared the sealing ability of Core Max II and Clearfil photocore by Panavia F 2.0 cement, with and without adhesive. Crowns of sixty recently extracted human second premolar teeth were cut 3 mm above the CEJ. After preparing proximal boxes and finishing root canal therapy, the teeth were randomly divided into four groups of fifteen teeth each. The Dentatus #2 Long pins with approximately 8 mm length were cemented in canals. In the first two groups, Core Max II with adhesive [group 1] and without adhesive [group 2] was applied for cementation. Pins in the other two groups were cemented with Clearfil photocore composite and Panavia F 2.0 cement with adhesive [group 3] and without adhesive [group 4]. After 24 hours, specimens were thermally cycled for 500 cycles. Then the teeth were sealed with nail varnish beyond 1 mm of restoration margins and immersed in a 0.5% fuschin solution. Aftewards samples were embedded in epoxy resin, sectioned mesiodistally and observed under 20 x magnification. The microleakage was recorded as the amount of dye penetration in the route connecting the proximal boxes to the end of the pin. ANOVA and Tukey tests served for statistical analysis. The first [61.57 +/- 14.24] and fourth [12.37 +/- 13.85] groups had the highest and the lowest value of microleakage, respectively. Using adhesive for both cements reduced microleakage [P<0.05]. Panavia cement had less microleakage compared to Core Max II

[Comparison of different reinforcement methods of weakened buccal walls in premolar teeth]

In order to improve the aesthetics and functional quality of restorations, the combined amalgam-composite restorations have been introduced. The aim of this study was to compare different reinforcement methods, in weakened buccal walls of premolar teeth. In this in vitro study, 70 similar and intact premolar teeth were used. The specimens were divided into seven groups of ten. In six groups, the three reinforcing materials composite [A], Compoglass F [B] and glass ionomer [C] with two methods: I: buccal and distal wall reinforcement. II: buccal, distal and pulpal floor reinforcement was used. In the seventh group [D], the Scotchbond M.P.P adhesive as a control group was applied. Then specimens were restored conventionally with amalgam and submitted to 500 thermal cycles [5°C-55°C]. The specimens were loaded through Instron testing machine at a crosshead speed of 1 mm/min with angle of 45 degree. Statistical analyzes of ANOVA, Duncan and chi- square tests were used to analyse fracture strength, location and type of fracture. The highest strength was detected in group with composite reinforcement on buccal and distal walls and pulpal floor. The highest failure mode was adhesion type and observed in composite reinforcement and control group. The highest cohesive and mixed failure mode was respectively observed in Compoglass and glass ionomer groups. This study showed that composite resin was the best material for reinforcement of weakened walls with favourable aesthetic property

[Effect of NaOCl as canal irrigant on microleakage of resin composite restorations]

Statement of problem: Sodium hypochlorite is used as an endodontic irrigant for different purposes. Since it is a strong oxidizing agent it might inhibit the resin polymerization

Purpose: The objective of this in vitro study was to compare the effect of NaOCl on sealing ability of total etch and self etch bonding at different time intervals after root canal therapy

Materials and Methods: The roof of the pulp chambers and roots [1-2 mm below furcation] of eighty human first molar teeth were cut and pulp tissues were completely removed. Teeth were divided in two groups [n=40], based on the type of used adhsive; total etch [Scotchbond Multi-Purpose plus] and self etch [Clearfil SE Bond]. Immediately, chamber pulp of ten teeth of each group were restored with resin composite [control groups]. Thirty teeth in each group were treated with 5% NaOCl for 5 minutes in the chamber pulp and restored with resin composite associated with each bonding agent [Z100, Clearfil Photo Core] in three intervals: immediately, one, and two weeks after irrigation with NaOCl. Fluid filtration method was used for evaluation of microleakage. Data were statistically analyzed using ANOVA and T-test [alpha =.05]

Results: Type of dentin adhesive and different time intervals after NaOCl application and restoration, did not show any significant effect on microleakage value [p>0.05]. The variable of using and not using of NaOCl showed significant difference on microleakage value [p<0.05]. NaOCl treated samples demonstrated significantly higher microleakage

Conclusion: Irrigation with NaOCl during root canal therapy has a negative effect on microleakage of resin composite restorations. Delayed time for restoration did not remove the negative effect of NaOCl

[ effects of adhesive type and different curing methods on micro leakage and marginal adaptation of composite veneers]

The adhesives type and placement application technique may be important in long term stability and function of composite veneers. This study was conducted to evaluate the influence of dentin adhesive application techniques [pre-curing vs. non-curing] on micro leakage and marginal adaptation of indirect composite veneer restorations. A total etch bonding system, Excite/Variolink II [EXV], and a self-etching primer system, Panavia F 2.0 [PF2] were used in this in-vitro investigation. Forty-eight human central incisors were prepared for composite veneer restoration. These teeth were then divided into two groups [n=24]. Pre-cure adhesive [PC] with light cure technique as well as no pre-cure [NPC] prior to resin cement insertion in half of specimens in each group. By using these methods, we worked with four experimental subgroups [PC+EXV, NPC+EXV, PC+PF2, NPC+PF2]. Composite veneers [Tetric Ceram resin] were cemented using a dual-cured resin luting agents. All specimens were then stored in distilled water at 37°C for 24 hours before checking for marginal leakage. By random sampling, two specimens were selected from each group for SEM observations and evaluation of marginal adaptation at 1050 time magnifications. Data was analyzed by ordinal regression and link function of probit type at alpha

[In-Vitro evaluation of fracture resistance of weakened roots restored with fiber posts and tooth-colored materials]

Restoration of endodontically-treated anterior teeth with weakened roots requires special attention. The purpose of this investigation was to compare the fracture resistance of experimentally weakened anterior roots reinforced with three different methods using tooth-colored materials. Forty human sound maxillary central incisors were used in this in vitro study. The crowns of 30 teeth were removed 2mm above the CEJ. After root-canal therapy, flared canals were simulated. The teeth were filled with D.T. light-post plus resin composite [Clearfil DC Core Automix] in group 1, D.T. light-post plus two accessory posts [Reforpin+Panavia F 2.0] in group 2 and D.T. light-post plus Panavia F 2.0 in group 3. Access cavities in the fourth [control] group were restored after ideal root-canal therapy. Following cementation of the posts and restoration of the crowns with Clearfil Photo-Core composite, the roots were embedded in acrylic resin blocks, 1 mm below the CEJ. After 24h storage, the samples were loaded in an Instron testing machine with a crosshead speed of 0.5 mm/min at a 45° angle to the long axis of the tooth on the palatal surfaces until failure. The data were analyzed using ANOVA and Tukey test [P=0.05]. The lowest [300.17 N] and highest [585.11 N] mean fracture resistance values were observed in the third and fourth groups, respectively [P<0.05]. These values were not significantly different between the first, second and third groups. The results showed that Reforpin could be used as an alternative to resin composite for internal reinforcement of weakened roots

[ descriptive study on the frequency of pleomorphic adenoma in oral minor salivary glands]

The aim of this descriptive study was to determine the frequency of pleomorphic adenoma of oral minor salivary glands according to sex, and age and different site of tumor, in patients referring to Mashhad Dental School. Among the total number of 8115 biopsies taken during years 1349 to1384 at oromaxillofacialpathology department of Mashhad Dental School, 120 cases of oral minor salivary glands tumors were detected and selected for the study. Two time intervals of A [1349-1375] and B [1375-1384] were considered in which the frequency of pleomorphic adenoma was compared according to age, sex and site of the lesion. The frequency of benign and malignant tumors of oral minor salivary gland tumors was also determined. Pleomorphic adenoma with the frequency percentage of 29.16 was the most benign tumor in oral minor salivary glands. The most frequent age of pleomorphic adenoma involvement was different between the two time intervals. The percentage of benign to malignant tumors was higher in the first interval. Pleomorphic adenoma was the most frequent oral minor salivary glands neoplasm especially in thepalate. The onset age of involvement had decreased but female/ male ratio increased. Malignancy was more frequent in Interval B compared to A

[ effect of three different amalgam surface treatment methods on composite- amalgam fracture strength]

Following increasing people's demand for having aesthetic, functional and simultaneous benefits of composite and amalgam restorations, combined restoration of composite-amalgam has been introduced. The aim of this study was to evaluate the effect of there methods of surface treatment on composite-amalgam fracture strength. In this experimental invitro study, on thirty uniform and sound human maxillary premolar teeth mesiobuccal class II cavities were prepared so that in all specimens the thickness of buccal reminder enamel was one millimeter. They were divided randomly into three groups of ten and filled with amalgam. After 24h in each tooth, thin mesiobuccal enamel was removed and amalgam surface were veneered with Tetric Ceram composite by one of the three following methods. In A and B groups after etching with phosphoric acid, Scotchbond Multi-purpose and One Coat Bond were applied respectively. In group C after sandblasting and acid etching, margin bond unfilled resin was applied for adhesion of composite to amalgam. Finally for fracture strength measurement, the specimens were loaded under Instron testing machine at a crosshead speed of 1mm/min with 45[degree sign] angle. Fracture areas were also considered from stand point of CEJ location and type of debonding [adhesive - cohesive - mixed]. Data were analyzed with One Way ANOVA and Duncan tests. Mean fracture strengths in three methods were significantly different [P=0.02]. Group C had the highest and group B had the lowest fracture strength. In all three groups, the most common type of debonding was adhesive and above to the CEJ. The highest mean value of fracture strength was obtained in group with amalgam sandblasting followed by application of unfilled resin which did not differ significantly with Scotchbond Multi-purpose group. However it differed significantly with One Coat Bond group

Factors contributing to the incompatibility between new adhesive systems and various composite resin restorations

Although light cured composites are easily accessible, self/dual-cure cements and composite resins also have broad clinical applications. The aim of this study was to evaluate the incompatibility between new adhesives and different types of cement and composite resin restorations and their effects on interface bond strength. All articles and theses on adhesives and cement/composite resin restorations up to June 2005, available at Mashhad dental school library, medline and other internet information banks were collected and evaluated. Some two-step-total-etch and one-step-self-etch adhesives were incompatible with self7dual-cured cements and composite resins. This is due to the large concentration of acidic, ionic and hydrophilic resin monomers that result in adverse chemical interactions and increased permeability of these adhesives. In order to prevent the adverse acid-base chemical interactions between simplified adhesives, light cured cements or composites or dual cured adhesives containing catalysts should be used. For neutralizing the permeability effect of simplified adhesives, light cured composites or a single layer of unfilled resin bonding or flowable composites should be applied over the adhesive layer to induce rapid curing

[Comparison of prevalence of helicobacter pylori infection in urban and rural areas of Qazvin [2002]]

Background: Helicobacter pylori infection is the most common worldwide human infection and may be complicated by peptic ulcer and gastric cancer or MALT lymphoma

Objective: To evaluate prevalence of helicobater pylori in urban and rural areas of Qazvin

Methods: Through a cross-sectional, random sampling study, 120 subjects of general population of each area were selected and the data were collected by the use of a questionnaire. Blood [3ml] was obtained from each individual and tested by ELISA for Hp IgG Antibody [sensitivity 96% and specificity 94%]

Findings: Seroprevalence of helicobacter pylori infection in Rural areas 83.3% was higher than urban areas 75.8% but there were no significant statistical difference. Other factors [number of family members, gender, educational level, contact with domestic animals and cigar] except than increasing age were not associated with increased helicobacter pylori infection

Conclusion: Age was the only effective factor predicting the helicobacter pylori infection rate