Relationship between salivary alkaline phosphatase enzyme activity and the concentrations of salivary calcium and phosphateions

Although salivary alkaline phosphatase [ALP] can balance de- and remineralization processes of enamel, there is no evidence regarding its effects on the concentrations of calcium and phosphate in saliva. The present study aims to determine the relationship between salivary ALP activity and the concentrations of calcium and phosphate in saliva. In this cross-sectional study, we evaluated salivary markers in 120 males, ages 19 to 44 years. All participants provided 5 mL of unstimulated whole saliva and the level of enzyme activity as well as calcium and phosphate concentrations were measured using a colorimetric method. Data were gathered and analyzed by statistical package for social sciences [SPSS] 13.00 using Pearson correlation test. A p value of <0.05 was considered statistically significant. The mean age of participants in the present study was 32.95 +/- 8.09 years. The mean pH of saliva was 6.65 +/- 0.62. Salivary parameters included average ALP activity [5.04 +/- 1.866 U/dL], calcium [4.77 +/- 0.877 mg/dL] and phosphate [10.38 +/- 2.301 mg/dL]. Pearson correlation test showed no significant relationship between ALP activity and calcium and phosphate concentrations in saliva [p>0.05]. According to the results of the present study, there was no significant relation between salivary ALP activity and calcium and phosphate concentrations in saliva. However, further research is highly recommended

effect of epigallocatechin gallate on the dentin bond durability of two self-etch adhesives

Statement of the Problem: Self-etch adhesives can activate matrix metalloproteinase [MMP] which hydrolyzes organic matrix of demineralized dentin. Epigallocatechin gallate [EGCG], especially found in green tea, could inhibit the activation of MMP.

Purpose: The aim of this study was to evaluate the effect of adding Epigallocatechin gallate [EGCG] into two types of adhesives on dentin bond strength.

Materials and Method: In this experimental study, 64 extracted third molars were randomly divided into 16 groups. Clearfil SE Bond and Filtek Silorane System with 0 micro M, 25micro M, 50micro M, and 100micro M concentration of 95% EGCG were used for bonding. Following the bonding and fabrication of beams [1 +/- 0.1 mm[2]] and storage in distilled water, the specimens were subjected to thermal cycles. Microtensile bond strengths of 8 groups were examined after 24 hours and others were tested after 6 months. The fracture modes of specimens were evaluated by stereomicroscope and SEM. Data were analyzed by three-way ANOVA and t-test [alpha = 0.05]

Results: The results of the three- way ANOVA test showed that types of bonding, storage time and interactive effect of EGCG concentration and bonding influenced the bond strength of specimens significantly [p<0.05]. The results of the t-test indicated that storage time only had significant effect on bond strength of Clearfil SE Bond with no EGCG [p= 0.017]. The most common failure modes in Filtek Silorane System groups and Clearfil SE Bond groups were adhesive and mixed/cohesive, respectively. The results of SEM at different magnifications showed that most fractures have occurred in the hybrid layer

Conclusion: Although adding 100 micro M volume of EGCG to Clearfil SE Bond can preserve the dentin bond, incorporation of EGCG in the silorane system, especially in high concentrations, decreases the bond strength after 6 months

Effect of surface treatment with carbon dioxide [CO[2]] laser on bond strength between cement resin and zirconia

Since it is not possible to form an adequate micromechanical bond between resin cement and zirconia ceramics using common surface treatment techniques, laser pretreatment has been suggested for zirconia ceramic surfaces. The aim of this study was to evaluate the effect of Carbon Dioxide [CO[2]] Laser treatment on shear bond strength [SBS] of resin cement to zirconia ceramic. In this in vitro study thirty discs of zirconia with a diameter of 6 mm and a thickness of 2 mm were randomly divided into two groups of 15. In the test group the zirconia disc surfaces were irradiated by CO[2] laser with an output power of 3 W and energy density of 265.39 j/cm[2]. Composite resin discs were fabricated by plastic molds, measuring 3 mm in diameter and 2 mm in thickness and were cemented on zirconia disk surfaces with Panavia F2.0 resin cement [Kuraray Co. Ltd, Osaka, Japan]. Shear bond strength was measured by a universal testing machine at a crosshead speed of 0.5 mm/min. The fracture type was assessed under a stereomicroscope at ×40. Surface morphologies of two specimens of the test group were evaluated under SEM before and after laser pretreatment. Data was analyzed by paired t-test [p value < 0.05]. The mean SBS values of the laser and control groups were 12.12 +/- 3.02 and 5.97 +/- 1.14 Mpa, respectively. Surface treatment with CO[2] laser significantly increased SBS between resin cement and zirconia ceramic [p value = 0.001]. Under the limitations of this study, surface treatment with CO[2] laser increased the SBS between resin cement and the zirconia ceramic

Dental caries prevalence in human immunodeficiency virus infected patients receiving highly active anti-retroviral therapy in Kermanshah, Iran

Introduction of new approaches for the treatment of human immunodeficiency virus [HIV] infection such as anti-retroviral medicines has resulted in an increase in the life expectancy of HIV patient. Evaluating the dental health status as a part of their general health care is needed in order to improve the quality of life in these patients. The aim of this study was to compare the root and crown caries rate in HIV patients receiving highly active antiretroviral therapy [HAART] with that rate in HIV patients without treatment option. This cross sectional study consisting of 100 individuals of both genders with human immunodeficiency virus were divided into two groups: i. group 1 [treatment group] including 50 patients with acquired immunodeficiency syndrome [AIDS] receiving HAART and ii. group 2 [control group] including 50 HIV infected patients not receiving HAART. Dental examinations were done by a dentist under suitable light using periodontal probe. For each participant, numbers of decay [D], missed [M], filled [F], Decayed missed and filled teeth [DMFT], decay surface [Ds], missed surface [Ms], filled surface [Fs], Decayed missed and filled surfaces [DMFS], and tooth and root caries were recorded. Data were analyzed using Chi-square test and independent t test using SPSS 13.0, while p-value of <0.05 was considered statistically significant in all analysis. The mean and standard deviation [SD] of decayed, missed and filled teeth of those who were on highly active antiretroviral therapy was 6.86 +/- 3.57, 6.39 +/- 6.06 and 1.89 +/- 1.93, respectively. There was no significant difference between these values regarding to the treatment of patients. The mean and standard deviation of DMFT, DMFS and the number of decayed root surfaces were 15.14 +/- 6.09, 56.79 +/- 28.56, and 4.96 +/- 2.89 in patients treated by anti-retroviral medicine which were not significantly different compared to those without this treatment. According to the results of the present study, highly active antiretroviral therapy could not be considered as a single factor for dental caries prevalence in HIV-infected patients. However, more research is recommended to evaluate the cariogenic potential of these medicines

Antibacterial properties of composite resins incorporating silver and zinc oxide nanoparticles on Streptococcus mutans and Lactobacillus

OBJECTIVES: Recurrent caries was partly ascribed to lack of antibacterial properties in composite resin. Silver and zinc nanoparticles are considered to be broad-spectrum antibacterial agents. The aim of the present study was to evaluate the antibacterial properties of composite resins containing 1% silver and zinc-oxide nanoparticles on Streptococcus mutans and Lactobacillus. MATERIALS AND METHODS: Ninety discoid tablets containing 0%, 1% nano-silver and 1% nano zinc-oxide particles were prepared from flowable composite resin (n = 30). The antibacterial properties of composite resin discs were evaluated by direct contact test. Diluted solutions of Streptococcus mutans (PTCC 1683) and Lactobacillus (PTCC 1643) were prepared. 0.01 mL of each bacterial species was separately placed on the discs. The discs were transferred to liquid culture media and were incubated at 37degrees C for 8 hr. 0.01 mL of each solution was cultured on blood agar and the colonies were counted. Data was analyzed with Kruskall-Wallis and Mann-Whitney U tests. RESULTS: Composites containing nano zinc-oxide particles or silver nanoparticles exhibited higher antibacterial activity against Streptococcus mutans and Lactobacillus compared to the control group (p < 0.05). The effect of zinc-oxide on Streptococcus mutans was significantly higher than that of silver (p < 0.05). There were no significant differences in the antibacterial activity against Lactobacillus between composites containing silver nanoparticles and those containing zinc-oxide nanoparticles. CONCLUSIONS: Composite resins containing silver or zinc-oxide nanoparticles exhibited antibacterial activity against Streptococcus mutans and Lactobacillus.

Bond strength of resin cement to CO2 and Er:YAG laser-treated zirconia ceramic

OBJECTIVES: It is difficult to achieve adhesion between resin cement and zirconia ceramics using routine surface preparation methods. The aim of this study was to evaluate the effects of CO2 and Er:YAG laser treatment on the bond strength of resin cement to zirconia ceramics. MATERIALS AND METHODS: In this in-vitro study 45 zirconia disks (6 mm in diameter and 2 mm in thickness) were assigned to 3 groups (n = 15). In control group (CNT) no laser treatment was used. In groups COL and EYL, CO2 and Er:YAG lasers were used for pretreatment of zirconia surface, respectively. Composite resin disks were cemented on zirconia disk using dual-curing resin cement. Shear bond strength tests were performed at a crosshead speed of 0.5 mm/min after 24 hr distilled water storage. Data were analyzed by one-way ANOVA and post hoc Tukey's HSD tests. RESULTS: The means and standard deviations of shear bond strength values in the EYL, COL and CNT groups were 8.65 +/- 1.75, 12.12 +/- 3.02, and 5.97 +/- 1.14 MPa, respectively. Data showed that application of CO2 and Er:YAG lasers resulted in a significant higher shear bond strength of resin cement to zirconia ceramics (p < 0.0001). The highest bond strength was recorded in the COL group (p < 0.0001). In the CNT group all the failures were adhesive. However, in the laser groups, 80% of the failures were of the adhesive type. CONCLUSIONS: Pretreatment of zirconia ceramic via CO2 and Er:YAG laser improves the bond strength of resin cement to zirconia ceramic, with higher bond strength values in the CO2 laser treated samples.

[Comparison of the anti-caries effect of polyphenol extract of green tea with 0.05% fluoride, 0.2% chlorhexidine and fluoride-chlorhexidine, an in vitro study]

Mouth rinses beside the other methods have an important role in reducing dental caries. The aim of this study was in-vitro comparison of the anti-caries effect of polyphenol extract of green tea with 0.05% fluoride, 0.2% cholorhexidine and fluoridecholorhexidine. In this laboratory experimental study, 50 maxillary premolars were placed separately in tubes which contained cariogenic solution [streptococcus mutans, lactobacillus and 3 ml sucrose solution of 20%]. Each tube regarding the rinse solution was placed in 5 experimental groups [n=10] as follows: 1] normal saline, 2] 10% solution of green tea polyphenol extract, 3] 0.05% fluoride, 4] 0.2% cholorhexidine and 5] fluoride_cholorhexidine. Every 24 hours, the teeth were rinsed with 5 mL of the rinse. After 21 hours, the depth of decay was measured by polarized light microscope. Data were analyzed by SPSS V 13.0 software using Colmogrove Smirnove, One way ANOVA and Tukey tests. The mean and standard deviation of the depth of the caries in group 1 to 5 were 194 +/- 16.43, 175 +/- 17.94, 142 +/- 9.34, 155 +/- 13.27, and 144 +/- 8.57, respectively. One way ANOVA showed that there were significant differences between the groups [P<0.001]. Tukey test showed that although there was no significant difference in the depth of the caries between groups 1 and 2 [P=0.205], it was significantly less than groups 3 to 5 [P<0.001]. There were no significant differences between the depth of the caries in group 3, 4 and 5. According to the results of the current study, the anti-caries effect of flouride_cholorhexidine was the greatest between the groups. As the anti cariogenic effect of green tea was similar to that of normal saline and significantly less than fluoride or chlorhexidine, its use as a common mouth rinse needs more research

Effect of Epigallocatechin Gallate on shear bond strength of composite resin to bleached enamel: an in vitro study

OBJECTIVES: The aim of this study was to determine the effect of epigallocatechin gallate (EGCG) on the shear bond strength of composite resin to bleached enamel. MATERIALS AND METHODS: Ninety enamel surfaces of maxillary incisors were randomly divided into 9 groups as follows: G1: control (no bleaching); G2: bleaching; G3: bleaching and storage for seven days; G4 - 6: bleaching and application of 600, 800 and 1,000 micromol of EGCG-containing solution for 10 minutes, respectively; G7 - 9: bleaching and application of 600, 800 and 1,000 micromol of EGCG-containing solution for 20 minutes, respectively. The specimens were bleached with 30% hydrogen peroxide gel and a composite resin cylinder was bonded on each specimen using a bonding agent. Shear bond strength of the samples were measured in MPa. Data was analyzed using the two-way ANOVA and Tukey HSD tests (alpha = 0.05). RESULTS: The maximum and minimum mean shear bond strength values were observed in G1 and G2, respectively. Time and concentration of EGCG showed no significant effects on bond strength of the groups (p > 0.05). Multiple comparison of groups did not reveal any significant differences between the groups except for G2 and all the other groups (p < 0.05). CONCLUSIONS: There is a significant decrease in bond strength of composite resin to enamel immediately after bleaching. A delay of one week before bonding and the use of EGCG increased bond strength of composite resin to bleached enamel.

[Comparison the effects of different root canal irrigants on the retention of quarts fiber posts cemented by resin cement]

Root canal irrigants could change the structure of root dentin and affect the posts retention the purpose of this study was to compare the effects of three different endodontic irrigants on the retention of quarts fiber posts cemented by different resin cements. In this in-vitro study, 10 mm long post spaces were prepared in root canals of 120 premolars after endodontic therapy and cutting the crowns at the cementoenamel junction. The teeth were randomly divided into four equal groups based on the irrigants as follows: distilled water, 2% chlorhexidine, 0.25% iodine and 1% NaOCl. Quarts fiber posts were cemented by Panavia F2. Samples were stored at 370c and humidity of 100% for one week. After thermocycling, the retention of fiber posts were measured by tensile test and modes of failure were reported. Data were analyzed by One-Way ANOVA, Tukey and Fisher's exact tests. The mean and standard deviation of the posts retention were 367.08 +/- 63.07, 377.59 +/- 72.02, 363.11 +/- 68.53 and 342.89 +/- 74.94 for distilled water, chlorhexidine 2%, iodine 0.25% and sodium hypochlorite, respectively. One-way ANOVA showed that there was a significant difference among the groups [P<0.001]. The results of Tukey test showed that posts retention was significantly higher after rinsing by chlorhexidine [P<0.01]. According to the results of this study, chlorhexidine rinse had a favorable effect on retention of posts cemented by resin cement.