Background & Aim: Dental porcelain is one of the best materials ever used in dentistry. Restoring and replacement of the teeth by porcelain fused to metal restorations is still the most commonly used approach. There fore, Mashad Dental School and Par-e-Tavoos research institute attempt to produce porcelain powder used in P.F.M. system.Method & Material: This is an experimental single blind in vitro study. For this purpose Dentin powder was produced, observing vita Dentin porcelain powder (VMK 68M) (Vita Co. Germany) and ISO 6872 1995 (E) standard qualifications. First "Vita-dentin" powder was chemically analyzed using SEM, XRD, and XRF techniques to find the chemical formula of the powder and to make a similar powder using material from inside the country. After producing different powders, (Dentin-D4) powder was found to be physically and chemically similar to "Vita-Dentin". Different tests have been performed to be compatible with Vita porcelain which is one of the most universal dental porcelain in the world. One of the tests was to measure the shrinkage of porcelain after baking. For this purpose a stainless steel box was made with 25x5x2 mm diameter and filled with porcelain powder paste to make 10 blocks of Dentin-D4 and 10 blocks of Dentin-Vita and baked in Vita furnace. The dimensions of the blocks including length, width, and thickness were measure using a especial gauge and percentage of volume shrinkage was calculated.Results: The Mean volume shrinkage between two powders had a statistically significant difference (P<0.001)."Vita- Dentin" had volume shrinkage of 33.07% while Dentin-D4, had 17.24%.Conclusion: 1- The mean volume shrinkage of all Dent-D4was lowers than Dentin-vitan. 2- The laboratory works are easier with Dentin-D4 than Dentin - vita due to less volume shrinkage of Dentin-D4.

Introduction: Many clinical studies have evaluated different dentin bonding agents in treatment of dentin hypersensitivity (DH). But the use of acid is controversial and the effect of self-etch bonding agents isn't clearly defined. Objective: The aim of this study was to compare two dentin bonding systems, prompt (self-etch bonding system) and excite(with and without acid) in treatment of DH.Materials and Methods: This clinical study had a double-blind, randomized, subject design and was performed on 41 sensitive teeth with DH. We had 3 groups e1 (we used excite without acid), e2 (excite with acid) and p (prompt). Two stimuli (cold water 20‎ْc and compressed air) and two methods for evaluation ((VAS (Visual Analogue Scale) and response time)) in 3 times (before treatment, immediately after treatment and two weeks after it) were used.Results: All treatments showed significant reductions in DH. In the VAS scores, no significant difference was found. But in the response time, the groups e1, P significantly showed better results than group e2.(P<0.05)Conclusion: Treatment effects were improved in all groups with time. Use of acid before the bonding agent had a negative effect but there was no significant difference between prompt and excite (without acid etching). It's worth nothing that the measurement of response time to stimulus compared to the VAS method is more accurate in evaluation studies of pain rate.

The aim of this review study is to increase information about dentin hypersensitivity, its etiology and treatments. For data collection we used PUBMED to find relevant articles. Then using the obtained articles and relevant text books, we attempted to sort this information according to etiology, prevalence and available treatment options.

Many studies have shown that microorganisms are the main cause of pulpal diseases and the main purpose of root canal therapy is their elimination from the root canal system. Antiseptic agents are used to reduce bacteria but their antibacterial activities differ from in vivo to in vitro studies and might be inactivated by dentin and its components in root canal space. This study was designed to investigate the effect of dentin on antibacterial activity of different antimicrobial agents.Materials and Methods: In this experimental study, two antibacterial agents (sodium hypochlorite and chlorhexidine) with different concentrations were used in four experimental groups: Group 1: dentin, Group 2: demineralized dentin with EDTA, Group 3: dentin matrix and Group 4: dentin mineral component. The species used in this study was Entrococcus faecalis. Different concentration of agents was added to mixture of each experimental group and bacteria. At the baseline and after one and 24 hours, samples were collected and cultured. After incubation period, colonies were counted. Data were analyzed by Tukey test with p<0.05 as the limit of significance.Results: 2% and 0.2% chlorhexidine, and 5% sodium hypochlorite solutions at the three studied times eliminated Entrococcus faecalis completely. 1% sodium hypochlorite eliminated all bacteria in 1h and 24 hs. Statistical analysis showed significant differences between experimental and control groups (P<0.05). Sodium 1% hypochlorite at time 0, could reduce bacteria significantly (P<0.05) but didn’t eliminate them completely.Conclusion: Inactivation of intracanal antiseptics was not observed in this study. As elimination of bacteria occurred, application of these antibacterial agents is recommended in endodontic treatment. Further investigations on other antibacterial agents, other concentrations and shorter time intervals are recommended.

Objectives: The aim of this in-vitro experimental study was to assess the effect of application of a desensitizing varnish on the enamel and dentin marginal seal.Materials and Methods: Seventy-two freshly extracted, intact human premolar teeth were divided into four groups (n=18). Class V cavities (3mm in length, 2mm in width and 2mm in depth) were prepared on the buccal surface of each tooth. The following sealing materials were applied in the four groups: One-step Clearfil S3 Bond (S3) self-etch adhesive, two-step Clearfil SE Bond (SE) self-etch adhesive, S3 Bond+ VivaSens desensitizing varnish (VS+S3) and Clearfil SE Bond + VivaSens (VS+SE). The cavities on the teeth were then incrementally filled with Z350 light-cure composite. The teeth were stored in distilled water for 24 hours at 37°C, and were then thermocycled for 1000 cycles. Then, all the specimens were prepared for dye penetration test and were immersed in 2% basic fuchsin dye and incubated at 37°C for 24 hours. The teeth were then sectioned buccolingually along the center of restorations with a diamond disk. Microleakage at the tooth-restoration interface was assessed in the enamel and dentin margins blindly using dye penetration under a stereomicroscope at ×20 magnification.Results: There was significantly greater leakage at the enamel and dentin margins in group VS+SE than in group SE, also, these values were higher in group VS+S3 than in S3.Conclusion: Combined application of desensitizing varnish and self-etch adhesives seems to increase microleakage in composite restorations. Thus, its application is not suggested.

Introduction: Nowadays, several casein components such as casein phosphopeptide amorphous calcium phosphate (CPP-ACP) are vastly considered as a suitable replacement for fluoride component. The aim of this study was to compare the effect of CPP-ACP paste and fluoride varnish on dentin hypersensitivity reduction.Materials & Methods: In this clinical trial study, thirty adult patients between the ages of 20-50 years, presenting with the chief complaint of dentin hypersensitivity were examined. The loss of dentin was less than 0.5mm. The subjects divided into three groups: In groups I and II, patients were treated using CPP-ACP and fluoride varnish following manufacturer instructions. Group III received placebo gel. A visual analog scale was used to assess subjects' response to compressed air and ice stimuli at baseline, 7 days, 28 days and 60 days after treatment. Data was analyzed by One Way Analysis of Variance (ANOVA), Duncan Post Hoc test using the SPSS software version 21.Results: The results showed significant statistical difference between the groups (P<0.05). In fluoride varnish group and CPP-ACP paste group, the dentin hypersensitivity significantly decreased when baseline scores compared to post treatment scores at 7, 28, 60 days (P<0.05).There was no significant statistical difference in dentin hypersensitivity reduction in fluoride varnish and CPP-ACP paste groups.Conclusion: The results of this study showed that both of fluoride varnish and CPP-ACP paste effectively reduced dentinal hypersensitivity compared with placebo-control group.

Statement of Problem: Dental porcelain is one of the best materials ever used in dentistry. Excellent tissue compatibility, esthetics, very low solubility in oral fluids, high compressive strength, and the lowest bacterial plaque accumulation on the glazed porcelain are some of its advantages. Porcelain brittleness due to its low tensile strength, impact strength and the occlusal attrition of opposing teeth enamel are some of its disadvantages. The most important mechanical properties of dental porcelains are their flexural strength that is the ability of a porcelain to resist fracture when loaded from above. Different ways have been proposed to eliminate porcelain brittleness and develop its flexural strength, among which baking porcelain on a metal framework is more commonly used.Purpose: Considering that restoration and replacement of teeth by porcelain fused to metal restorations is still the most commonly used technique, the aim of the present study was to measure the flexural strength of a porcelain bonded to metal powder, D4 Dentin, and to compare it with Vita Dentin powder.Materials and Methods: In this experimental study, a stainless steel box, 25×5×2mm was made according to ISO 6872: 1995 (E) Standard and filled with D4 Dentin powder and Vita Dentin (VMK 68N) and baked in Vita furnace. Then 10 blocks of D4 Dentin and 10 of Vita Dentin were made. Samples were placed on the three point bending test machine and force was applied the middle of each block. To analyze the data, t- student test and co-variance analysis were used.Results: Mean flexural strength of D4 Dentin was 53.40 1.35 MPa and that of Vita Dentin was 53.86 7.38 MPa. The difference was not statistically significant.Conclusion: According to ISO 6872: 1995 (E) standard, the flexural strength of all D4 Dentin samples were greater than 50 Mpa.

Background and Aim: This study aimed to assess the efficacy of Pistacia lentiscus (P. lentiscus) extract for dentin remineralization. Materials and Methods: This in vitro experimental study evaluated 45 extracted sound human premolars,pH cycling was performed to assess the effect of 10% P. lentiscus extract on dentin remineralization. The samples were randomly assigned to three groups of 1000 ppm sodium fluoride (NaF) solution, 10% P. lentiscus extract, and deionized water. To induce dentinal lesions, the teeth were immersed in a demineralizing solution at 37°, C for 96 hours. The demineralized samples were then subjected to pH cycling for 14 days, and then underwent the Vickers microhardness test and scanning electron microscopic (SEM) assessment. Data were analyzed by repeated-measures ANOVA. Results: The mean microhardness in the NaF group was significantly higher than that in the extract and control groups after 14 days (P<0. 05). SEM assessment after demineralization indicated tubular obstruction in the extract and NaF groups. However, after 14 days, the sealing of dentinal tubules in the extract group was greater than that in the NaF group. Conclusion: P. lentiscus extract can serve as a suitable organic compound for dentinal tubule occlusion as well as non-invasive and conservative treatment of dentin hypersensitivity (DH).