[Comparison of color change of silorane and methacrylate-based composites due to bleaching]

Bleaching treatments may alter the color stability of composite restorations. Silorane-based composites have shown similar or superior physical and mechanical properties compared to other types of composites. Furthermore, studies have shown variable and sometimes contradictory results regarding the effect of bleaching agents on the color stability of composite restorations. This study aimed to assess the effect of two Iranian bleaching agents on color stability of a Silorane-based [P90] composite compared with two methacrylate-based composites [nanofiller[Z350] and microhybrid. [Z250]. In this in vitro study, a total of 18 disc-shaped specimens [10 x 2 mm] of Z250, Z350 and P90 composites [A3 shade] were fabricated and randomly divided into 3 groups [n=6] and subjected to bleaching treatment with 16 % carbamide peroxide, 35% carbamide peroxide and distilled water as the control group. Color parameters were measured using CIE-L*a*b* system and a spectrophotometer before and after bleaching. The factors were statistically analyzed by means of two-sided ANOVA [repeated measures ANOVA] and Tukey's multiple comparisons tests.The mean +/- standard deviation of total color change [delta E] in control, 16% carbamide peroxide and 35% carbamide peroxide groups was 3.48 +/- 1.43,4.55 +/- 1.7 and 4.17 +/- 1.9, for Z250, 4.33 +/- 2.41, 4.94 +/- 2.23 and 4.25 +/- 1.65, for Z350 and 4.97 +/- 2.47, 5.28 +/- 1.67 and 3.4U2.26 for P90, respectively. delta E was clinically perceptible after bleaching treatments of all composite materials [delta E>3.3]

[Efficacy of four disinfectants against hepatitis B virus]

Hepatitis B is an important infection in dentistry necessitating the use of disinfectants to prevent its transmission. This study compared the efficacy of 2/100 sodium hypochlorite disinfectants manufactured by four different manufacturers namely Ashimashi, Paknaz, Vitex and Active against hepatitis B virus [HBV]. In this experimental laboratory trial, serum of 10 hepatitis B patients was poured into microtubes and Ashimashi, Paknaz, Vitex and Active disinfectants were added to them. Polymerase chain reaction [PCR] was performed with viral diagnostic kits to diagnose the virus genome. Real time PCR was performed before and after incubation with the disinfectants. The reductions occurred in the viral load of HBV were statistically analyzed by Kruskal-Wallis and Mann-Whitney U tests.No significant antiviral efficacy was noted following the application of Ashimashi 2/100 sodium hypochlorite disinfectant. Paknaz showed the highest efficacy against HBV. Vitex and Active ranked next with significant differences [P<0.0001].Under the study limitations, Paknaz 2/100 sodium hypochlorite solution was the most effective while Ashimashi 2/100 sodium hypochlorite disinfectant did not show adequate efficacy against HBV

[Color stability of three composite resins following accelerated artificial aging: an in-vitro study]

Discoloration is among the most common problems of composite restorations. Color change over time compromises the main advantage of composite resins namely their high esthetics. In such cases, the restoration needs to be replaced. .The aim of this in-vitro study was to evaluate the effect of accelerated artificial aging [AAA] on the color stability of three composite resins [Filtek Z250, Filtek Z250XT, and Filtek Supreme]. In this experimental study, 7 composite specimens with equal dimensions were fabricated of each composite resin. The initial color of specimens was measured using a spectroradiometer according to the CIE L*a*b* system. The specimens were then submitted to AAA for 384h and underwent color assessment again. Before and after aging, the surface roughness of one specimen from each group was determined by Atomic Force Microscopy [AFM]. The obtained color parameters were analyzed by one-way ANOVA and Tukey's test. The color change of Filtek Z250 was significantly lower than that of Filtek Z250XT and Filtek Supreme [P 0.05]. All composite resins showed color change above the clinically acceptable threshold [delta >/= 3.3]. Z250 microhybrid composite was more color stable than nano-composites [Z250XT and Supreme]. AAA increased the surface roughness in all groups but it was within the clinically acceptable range

[Radiographic assessment of upper airway size in skeletal sagittal and vertical jaw discrepancies]

An important factor in the process of diagnosis and orthodontic treatment planning is patient's respiratory function that has a direct correlation with the upper airway size. The aim of this study was to measure and compare nasopharyngeal, oropharyngeal and hypopharyngeal airway volumes in Iranian subjects with sagittal [Class I, II and III] and vertical [normodivergent, hyperdivergent and hypodivergent] jaw discrepancies using standard cephalometric radiographs. In this descriptive cross-sectional study, 100 pre-treatment lateral cephalograms of orthodontic patients were evaluated to assess the size of upper airway space including the nasopharynx, oropharynx and hypopharynx. In order to assess airway dimensions in patients with sagittal and vertical discrepancies, subjects were divided into two large groups of normal sagittal and normal vertical patterns. Airway size was measured in sagittal plane in 50 subjects with normal vertical patterns and in vertical plane in 50 subjects with normal sagittal patterns. Linear variables i.e. the size of nasopharyngeal space [PNS-UPW], oropharyngeal space [U-MPW] and hypopharyngeal space [V-LPW] were measured by cephalometric tracing. Data were analyzed using SPSS version 15 software and chi-square, ANOVA and Tukey's HSD tests. Understudy subjects had normal age and gender distribution pattern. In patients with normal sagittal pattern, by an increase in vertical dimension, size of nasopharynx [PNS-UPW], oropharynx [U-MPW] and hypopharynx [V-LPW] decreased and the mentioned volumes were significantly smaller in subjects with hyperdivergent facial patterns compared to hypodivergents. In subjects with normal vertical pattern, by an increase in ANB angle, size of oropharynx [U-MPW] and hypopharynx [V-LPW] decreased and the mentioned volumes in CL II patients were significantly smaller than in CL III subjects; whereas, the largest nasopharynx [PNS-UPW] was observed in CL I subjects. Sagittal and vertical discrepancies affect upper and lower airway dimensions and by an increase in facial height, the mentioned volumes decrease. Smaller ANB angle results in larger airway dimensions

[Application of information technology by Iranian dentists: assessment of knowledge and performance]

Advances in medical sciences have increased the volume of medical records and documents. In order to solve this problem, the information technology [IT] is now being applied to improve health care. This study aimed to assess the knowledge of dentists about IT and its application by them. In this analytical cross-sectional study, a validated questionnaire was distributed among 220 dentists participating in the 52[nd] International Congress of Iranian Dental Association and 120 dentists working in Tehran and included 7 questions about knowledge, 8 questions about background, 10 questions about general use of IT and 3 questions about the professional use of IT. The data were entered into SPSS version 18 software and the statistical analyses were performed by regression modeling. Of a total of 340 general practitioners, 30.4% were males and 11 dentists [3.6%] stated that they had no access to a personal computer. Some of the most popular sites visited by dentists were Google [94.3%] and Facebook social networking site [69.8%]. Among the participants, 64.5% were not familiar with any website related to their special field of work. The mean knowledge score was 5.3 [SD= 2.5]. The application of professional IT was more common among men and among those with higher general use of IT. Most dentists participated in this study had insufficient knowledge about professional IT. The general and professional use of IT was poor by dentists and further instruction and training seem necessary in this respect

In vitro evaluation of the effect of different times of sandblasting on the bond strength of feldspathic porcelain to composite resin

Intraoral repair of fractured porcelain is an acceptable method to avoid replacement and therefore saving time and cost. The purpose of this study was to determine the in-vitro shear bond strengths of composite resin to feldspathic porcelain after different durations of sandblasting and to compare the effect of sandblasting with that of hydrofluoric acid [HF]. In this in-vitro study, 40 porcelain disks were fabricated and randomly divided into 4 groups [n=10]. Porcelain surface in group 1 was etched with 9.5% HF for 2 minutes. Groups 2, 3 and 4 were sandblasted with 50am alumina particles for 5, 10 and 15 seconds, respectively. All specimens received the same silane agent, bonding agent and composite resin. The samples were subjected to 5000 thermal cycles and then underwent shear bond strength testing. The mean bond strength was analyzed with one-way ANOVA. The mode of failure was determined using stereomicroscope and scanning electron microscope. An additional porcelain sample was fabricated and prepared according to the aforementioned protocols in each group and its surface topography was observed by SEM. The mean bond strength was 15/28 [ +/- 3/64], 13/82[ +/- 4/03], 15/77[ +/- 3/94] and 16/54[ +/- 3/73] MPa in the 4 groups, respectively. There were no statistically significant differences among groups. The most common mode of failure was cohesive in porcelain. No statistically significant difference was found in SEM results of different durations of sandblasting. The shear bond strength was not significantly different after various durations of sandblasting treatment. The bond strength after sandblasting was similar to that of HF. SEM showed that HF acid etching and sandblasting patterns were different

[Effect of staining solutions and repolishing on composite resin color change]

Success of composite restorations mainly depends on their color stability when in service. The present study aimed at assessing the effect of staining solutions and repolishing on composite resin color change. In this experimental study, 200 specimens were fabricated with A2 and B2 shades of Spectrum [TPH, Dentsply] and Point 4 [Kerr, USA] composite resins [100 specimens each]. Specimens were divided into 5 groups of 10 samples each and immersed in coffee, tea, coke, orange juice and distilled water for 30 days. Specimens were photographed with a digital camera [Fine Pix S9600]. Color analysis was done with CS Photoshop software [CIE lab color space] at baseline, after color change and after repolishing. Obtained results were analyzed using Three-way ANOVA and LSD test. Level of significance was set at P<0.05. All specimens showed a significant color change in all solutions except for water [delta E>3.3]. The greatest color change occurred in B2 Spectrum composite resin in coffee while the smallest color change was observed in A2 Point 4 specimens in water. Except for water and coke, the difference in color change between the two composite resins in all solutions was statistically significant. Color changes of B2 shade were significantly higher than those of A2. Significant improvements were observed in color of specimens after their repolishing. However, color change of specimens in coffee and tea did not improve to the clinically acceptable level by repolishing. Color change of composite restorations depends on the type and shade of composite resin as well as patient's nutritional habits

[Evaluation of the effect of three different Iranian industrial fruit juices on plaque PH]

Evaluation of cariogenic city of fruit juices as healthy snacks has special importance. The aim of this study was to evaluate the effect of 3 different Iranian industrial fruit juices on plaque pH. In this randomized clinical trial, 10 healthy dental students were selected based on the inclusion criteria namely the amount of streptococcus mutans and lactobacillus in the saliva, salivary secretion rate, buffering capacity of saliva, absence of active dental caries, absence of systemic disease and etc. Dental plaque pH in certain areas of the 4 mouth quadrants was measured by omega Metrohm microelectrode and digital pH meter before and 2 to 60 minutes after the consumption of Children orange juice, orange nectar with pulp, pineapple nectar and 10% sucrose solution. The pH curve at different time points was then drawn for each product. Data were analyzed statistically by repeated measures ANOVA [P<0.05]. The maximum drop in plaque pH occurred 2 minutes after consumption. The time spent below the critical pH was the longest for orange nectar with pulp [10.75 +/- 2.24] and shortest for pineapple nectar [3.46 +/- 1.14] .At final minutes of study, plaque pH returned to its baseline value after consumption of all fruit juices except for orange nectar with pulp]. After consumption of orange nectar with pulp, the mean plaque pH was significantly lower in comparison to other juices and the time spent under the critical plaque pH was the longest

Evaluation of DIAGNO dent values before and after the application of opaque fissure sealant to permanent teeth

The ability of DIAGNOdent [DD] for detection of occlusal caries under sealant and its reproducibility is a matter of question for dentists. The aim of this study was to evaluate DD values before and after the application of opaque fissure sealant [FS] and to determine the reproducibility of DD for detection of occlusal caries under sealant. This study was carried out on 42 extracted sound human premolar and third molar teeth. Two examinersassessed the deepest occlusal pit of teeth with DD Pen [Kavo, Germany]. This evaluation was repeated one week later to assess DD reproducibility. Assessment with DD was also performed after acid etching and FS application. The results were recorded and analyzed using linear regression test and SPSS software. The intra-examiner reproducibility of DD was 75.49% and 77.56% for the first and second observers, respectively. The mean DD value after etching and FS therapy increased by 28 and 6 units, respectively. DD has high reproducibility making it suitable for the monitoring of occlusal caries. However, DD value is influenced by the opaque sealant and thus, it should not be used as the sole device for detection of caries under sealants

[ vitro comparison of solubility of resin modified glass ionomer and a base containing hydroxyapatite in water, acid and artificial saliva]

Solubility is one of the shortcomings of dental materials that causes decreased physical and mechanical properties and longevity of the restoration. The aim of this in vitro study was to compare the solubility of the resin modified glass ionomer cement and a base containing hydroxyapatite. This experimental study was carried out according to ISO4049:2000[E] and ISO 9917-1:2007[E]. Ten samples of each of the two materials including resin modified glass ionomer and a base containing hydroxyapatite were evaluated for solubility in distilled water and artificial saliva. Evaluation of acid solubility was performed in lactic acid with pH=2.7 +/- 0.02 for 24 hrs. The data were analyzed by two-way ANOVA test. The mean values of solubility in distilled water for RMGIC and base containing hydroxyapatite were 0.6 [ +/- 0.3] and -1.6 [ +/- 1.4], respectively. The means of saliva solubility were 0.007 [ +/- 0.8] and 1.07 [ +/- 1.4], respectively for the mentioned materials. The mean value of acid solubility was 0.000474 [ +/- 0.000784] for RMGIC and 0.000334 [ +/- 0.000221] for Lime-lite. There was no significant difference between values of water sorption and solubility of the two materials [p>0.05]. The solubility of the two tested materials in distilled water, artificial saliva and acid was very little and there was no significant difference between them in this regard

[ effect of head and neck radiation therapy on salivary biochemical indicators]

Saliva plays a crucial role in preserving and maintaining oral health. Hyposalivation due to head and neck radiation therapy may induce changes to the biochemical properties of the saliva. The aim of this study was to analyze and compare saliva properties before and after radiation therapy in patients with head and neck cancers. In this quasi experimental study, 18 patients [13 male, 5 female] with head and neck cancers were evaluated regarding the flow rate of saliva, buffering capacity, amylase, total protein, IgM, IgA, IgG and albumin concentration of saliva prior to and following radiotherapy by schirmer test, pH meter, biuret, turbidometry and spectrophotometry. The oral symptoms due to radiotherapy [xerostomia, loss of taste, difficulty in swallowing, eating and speaking] were evaluated according to the patients' complaints. S tatistical analysis of the results was performed with paired t test. There was statistically significant changes in flow rate [28.27 +/- 7.8 Vs 10.94 +/- 12.2], salivary buffering capacity [6.47 +/- 0.68 Vs 5.06 +/- 0.52], amylase [2536.5 +/- 707.9 Vs 1053.23 +/- 343.5] and IgM concentration [0.87 +/- 1.8 Vs 0.04 +/- 0.07] before and after radiation therapy [p

[Azithromycin as an adjunct approach in non-surgical treatment of chronic periodontilis]

The use of antibiotics in conjunction with scaling and root planning is indicated in several cases of periodontitis. Azitbromycin is effective against gram negative microorganisms and has a long half life. The aim of this study was to evaluate the effectiveness of Azithromycin on clinical parameters in patients with chronic periodontitis. This randomized double-blind placebo-controlled clinical trial was conducted by recruiting 40 patients with chronic periodontitis referring to the Periodontics Department of Tehran University Dental School. The Papilla Bleeding index [PBI], Probing Depth [PD], and Clinical Attachment Level [CAL] were measured. The clinical examination was folloed by scaling and root planning [SRP]. Patients were assigned randomly to test [Azithromycin, 500 mg once daily for 3 days] and control [placebo, once daily for 3 days] groups one month after SRP. All parameters were measured again 2 and 4 months after baseline evaluation. Before administration of antibiotics [one month after baseline] the levels of clinical parameters [PBI, PD, and CAL] were not statistically different between the test and control groups. All clinical parameters [PBI, PD, and CAL] were significantly improved in both test and control groups one month after baseline [P<0.05]. In addition, all parameters were significantly lower in test group when compared with control group at 2 and 4 months [P<0.05]. Within the limits of this study, oral administration of Azithromycin in conjunction with scaling and root planning was useful in the treatment of moderate to severe chronic periodontitis

Evaluation of intelligence quotient in children with early first permanent molar eruption

There are many unknown systemic and local factors influencing tooth growth and development. Likely, tooth eruption may be under such influence as well. Despite delayed tooth eruption, studies on early tooth eruption are very scarce. Therefore, this study was conducted in order to evaluate the relationship between intelligence quotient [IQ] and early tooth eruption in normal children [with no disease or disorder]. By using study criteria, 44 children were recruited after oral examination of 652 children [337 boys and 315 girls]. Oral examination was conducted by one dentist using plastic disposable mirror, under day light. The Raven's test was taken blindly under standard conditions for all subjects by a psychologist. [Case] subjects were defined as individuals who had partially or fully erupted molars earlier than the expected normal time. [Control] subjects were similar to [cases] but without erupted molars. Statistical analysis was conducted using student T-test. The intelligence test was performed on 44 subjects consisted of 22 boys [IT'case] and 1 T'control]] and 22 girls [11 [case] and 11 [control]]. IQ in two sexes did not have significant difference [P<0.05]. But the mean IQ difference between [case] and [control] groups was about 11 points that was statically significance [P<0.01]. Healthy children with early first permanent molar eruptions, have higher IQ compared to their peers [P<0.01]. This criterion may be used to identify high IQ children for provision of special care and training for faster advancement of individual and society

[Accuracy and validity of spiral conventional tomography in assessment of mandibular implant recipient sites: an in-vitro study]

Conventional tomography is a cross sectional imaging modality that provides information about the width of the alveolar bone and the position of the critical anatomical structures such as mandibular canal in the lower jaw. In comparison with conventional CT, it is less expensive, more accessible and patients are exposed to much less radiation. The purpose of this study was to compare the accuracy and validity of spiral computed tomography and spiral conventional tomography. Ten fully or partially edentulous cadaver mandibles were selected. The specific points in anterior, canine, premolar, and molar regions were selected and imagings were performed with both radiographic systems. The distance between alveolar crest to superior border of mandibular canal, as well as mandibular height and width were measured by one oral and maxillofacial radiologist in two successive sessions. The tomography and CT scan [as gold standard] measurements were compared. This evaluation revealed that the absolute mean differences in measuring the vertical dimension in the anterior, canine, premolar, and molar regions were 1.43, 0.74, 0.87, and 0.81 millimeters respectively. The horizontal dimension measurements were 1.21, 0.92, 0.76, and 0.82 millimeters respectively. The absolute mean differences in measuring the vertical and horizontal dimensions were 0.65 and 0.91 millimeters respectively. All these measurements were with in limits of +/- 1 mm error except in the anterior region. Both measurements of vertical and horizontal dimensions had the tendency to be underestimated in anterior region. In measuring the vertical and horizontal dimensions, the validity of spiral conventional tomography were 90.49% and 73.02% respectively, and both were statistically significant [P < 0.001]. From the results of present study it can be concluded that the spiral conventional tomography is an accurate and reliable technique for measuring the vertical and horizontal dimensions in mandible

[Antimicrobial effects of sanosil solution on dental instruments]

Sanosil is a brand new disinfectant that is composed of H2O2 and traces of Ag with considerable effectiveness. The aim of this study was to evaluate the effectiveness of Sanosil on disinfecting dental devices and instruments. This laboratory-based study was conducted on 60 samples that were collected before [n=30] and after [n=30] administration of Sanosil from the same spots on dental instruments. The samples were cultured on blood agar and chocolate agar and were incubated in 37°C for 24 hours. The effect of Sanosil was investigated by counting the number of microbial colonies after determining the standard laboratory species' type and subtype. The data were analyzed by using SPSS version 14 and Chi-square test for determining the significance level, and alpha error was set at 0.05. The isolated microorganisms were mainly: Staphylococcus aureus, Streptococcus viridans, coagolase negative Staphylococcus, E.coli, Bacillus cereus, Bacillus subtilis and Staphylococcus epidermidis, E.coli Aeromonas hydrophila, corynebacterium, Microccus luteus. From the total samples 90% were free of any bacteria. Microbial load was significantly reduced [P<0.05] after Sanosil application on dental instruments and it also deferred the growth of standard microorganisms in vitro. Sanosil is an effective agent in decreasing bacterial contamination of dental instruments without any adverse effect on the surface of instruments

Prevalence and risk indicators of periodontal disease among high-school students in Tehran

To identify the prevalence and risk indicators of periodontal disease in high-school students in Tehran, Islamic Republic of Iran, the periodontal condition of 867 students aged 15-19 years was assessed using the community periodontal index of treatment needs [CPITN]. The results showed that 88.7% of these students had less than perfect periodontal health. Multiple regression analysis revealed that sex, parents' educational level, frequency of toothbrushing and flossing, preventive dental visits and presence of extracted teeth were significant risk indicators for periodontal disease. School-based oral health promotion and prevention programmes are needed