JOURNAL OF ISLAMIC DENTAL ASSOCIATION OF IRAN (MAJALLAH-I-DANDANPIZISHKI)
Year:2009 | Volume:21 | Issue:3 (72)|Papers Count:15

Background and Aim: The fluoride ions are commonly found in water resources. These ions should be in optimum levels for prevention of dental caries. However, the excess value can cause such health problems as fluorosis. The aim of the present study was to investigate the removal of excess fluoride ions by using poly aluminum chloride as a new coagulant that is used in water treatment plants.Materials and Methods: All experiments were conducted in batch system. Several combinations of parameters such as initial fluoride concentration (1.4, 2 and 2.4 mg/L), pH of solution (3, 7, 9), poly aluminum concentration (10, 20, 30, 40 mg/L), and exposure time (30, 60, 90 minute) were investigated. Various concentrations of poly aluminum chloride solution at different pH levels were added into 200 ml of fluoride solution, and samples were taken in predetermined time intervals and the final concentration of fluoride was determined by spectrophotometer at 570 nm.Results: The results showed that, the highest removal was obtained at pH=7. In addition, it was observed that fluoride removal efficiency was higher in pH=5 than in pH=9. Also the results showed that, removal efficacy can be increased by increasing the poly aluminum chloride and the exposure-time.Conclusion: This study denoted that removal of high levels of fluoride ions can effectively be done by using poly aluminum chloride as a new coagulant. Its use is possible in water treatment facilities without any need for modification in water treatment plans.

Background and Aim: Cyclooxygenase enzyme inhibitors have been recently investigated regarding their inhibitory effect on cancer. The aim of the present study was to investigate the cytotoxic effects of cyclooxygenase enzyme inhibitor drugs on KB cell line (squamous cell carcinoma) in vitro.Materials and Methods: This experimental study used the powder of Ibuprophen, Indomethacin, Acetaminophen, Naproxen, Celecoxib, Mefenamic acid, Diclofenac Na, Aspirin and Piroxicam. These drugs were dissolved in proper solvents according to specified company instructions (SIGMA Company). The KB cell lines were proliferated through MTT Assay method. The concentration of drugs that causes 50% decrease in cell growth was computed (IC50). Post-hoc test was used to compare the effect of various concentrations of drugs on vitality of cells and variance test was applied to compare the mean of IC50 between various drugs by using SPSS version 13.5 statistical software.Results: This study showed that Celecoxibt, Mefenamic Acid and Diclofenac Na drugs have cytotoxicity effects on KB cell line with the IC50 values of 1.5, 4.5 and 15.4 mg/ml, respectively. Also, it was found that the Naproxen, Indomethacin and Aspirin drugs with the IC50 mean of 50µg/ml can inhibit cell growth.Conclusion: Celecoxib and Diclofenac Na drugs have cytotoxicity effects. Therefore, at the experimental stage, these medicines have the potential to be used as oral anticancer drugs.

Background and Aim: In contemporary orthognatic surgery, osteotomy and rigid internal fixation procedures are commonly used to restore stability and function of the jaws, and to obtain comfort for patients. Although there are many good reasons for utilization of this type of fixation, in some patients the need to remove plates and screws after surgery may arise due to related complications. The present study investigated plate removal after sagital split osteotomy and its reasons.Materials and Method: In this prospective study, 67 patients in need of sagital spilt osteotomy or bimaxillary osteotomy were selected from two university departments during the period of 2005 to 2007. All patients were followed up for 14 month after surgery and number of plates removed was recorded. In addition, information regarding age, sex, duration of operation, medical condition, splitting during surgery, smoking habits, and need to extract wisdom teeth at the time of surgery were gathered. The data were analyzed using a linear logistic regression model with the SPSS software version 12.Results: Infection was the sole reason for plate removal in this study. From 134 plates used in 67 patients 14 plates (10.5%) were removed in 10 patients. Age was the only statistically significant factor to affect plate removal and the effect of other factors were not statistically significant.Conclusions: According to the findings of this study only a few patients needed plate removal. Routine removal of plate does not appear to be clinically indicated.

Background and Aim: Among various treatments available for patients with Class III malocclusion, orthopedic protraction of maxilla during the mixed dentition period has been reported to be beneficial in cases with maxillary deficiency. In such patients, however, the maxillary expansion is not sometimes needed. The aim of the present study was to evaluate the therapeutic effects of face mask with and without maxillary expansion screw in Class III malocclusion patients who had maxillary deficiency.Materials and Methods: Twenty children with class III malocclusion were selected and randomly divided into two equal groups (A & B). The children in group A were treated with a protraction face mask, and patients in group B were treated with a face mask and removable slow maxillary expansion device. The cephalometric changes in maxilla and mandible, and alterations in dental relations were compared within and between groups before and after treatment. Before-after comparisons in each group were performed with paired sample t-test. Covariance analysis served for between groups comparisons.Results: In group A, the overjet was improved and molar relation was changed into normal occlusion (Class I). The cephalometric analysis in group B revealed that Class III malocclusion was modified through a forward movement of the maxilla and a backward rotation of the mandible.Conclusions: Face mask is a favorable treatment in improving the antero-posterior position of maxilla and mandible in Class III patients even if they don’t need palatal expansion.

Background and Aim: 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.Materials and Methods: 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 (group3) 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. Afterwards samples were embedded in epoxy resin, sectioned mesiodistally and observed under 20 x magnifications. 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.Results: 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).Conclusion: Panavia cement had less microleakage compared to Core Max II. Key words: Dental Leakage - Post and Core Technique - Composite Resins.Corresponding Author: Dr. Moosavi H., Assistant Professor, Department of Operative Dentistry, School of Dentistry, Mashhad University of Medical Sciences. Mashhad, Iran.

Background and Aim: The orthognathic surgery not only can alter facial appearance and occlusion, but also can affect the morphology, physiology, and biomechanics of craniofacial skeleton and the muscles of mastication. The purpose of this study was to investigate the changes in maximum bite force and electromyographic activity of masticatory muscles after sagital split ramus Lefort I osteotomy in patients with mandibular prognathism.Materials and Methods: A clinical trial was conducted on 14 patients with mandibular prognathism. Maximum bite force in 7 predefined points of dentition as well as electromyographic activity of masseter and temporalis muscles preoperatively, and at 3- and 6-month follow ups were measured in the patients. The analysis of variance for repeated measures and paired T-test served for analysis of longitudinal changes in maximum bite force and electromyographic activity of muscles.Results: Three months after surgery, both bite force and electrical activities of mandibular muscles of patients were significantly less than those of before surgery (P<0.05). Although all parameters were improved 6 months after surgery, maximum bite force in molar region did not reach the preoperative value. All other parameters at 6-month follow up increased by 10 to 15 percent compared to preoperative measurements.Conclusion: The findings of this study suggest that the maximum bite force and electrical activity of masticatory muscles in patients with mandibular prognathism may adapt to the new situation resulted from orthognathic surgery in six months after surgery; yet their return to the preoperative measurements is possible.

Background and Aim: Dental impressions are routinely contaminated with varying amounts of blood and saliva. This study investigated transferability and sustainability of oral flora on irreversible hydrocolloid and elastomeric impression materials.Materials and Methods: In this experimental study a sterilized maxillary typodont was contaminated through immersing in a solution containing approximately 108 bacteria/ml of Staphylococcuse, Streptococcuse and Candida albicans. Impressions were taken of contaminated typodont with irreversible hydrocolloid (Bayer-iralgin), and condensational silicone (Speedex). The impressions were rinsed with water and were placed in specific culture. The colony growth was investigated and the remainder of viable organisms was estimated. In the next stage of the study, samples were taken from impressions after 30 and 60 minutes, and 3 and 5 hours in order to evaluate the persistence of microorganisms. In the third stage, after preparing microbial suspension, the effectiveness of two different concentration of sodium hypochlorite was investigated in four different times. Kolmogrove-Smirnov, three-way ANOVA, and Tukey-HSD served for statistical analysis.Results: Type of impression material, time, and type of microorganisms significantly influenced the number of transmitted colonies (P=0.0001). Also, all interaction effects were statistically significant (P=0.0001). All tested microorganisms had grown in disinfected alginate and Speedex after immersion in 0.5% NaClO for one minute, but no bacterial growth was observed in both alginate and Speedex after 3, 5, and 10 minutes immersion. Regarding 0.6% NaClO, microorganisms were detected only in alginate material Bayer-Iralgin and only after one minute immersion.Conclusion: The results showed hydrocolloidal materials are more capable of carrying microorganisms compared to elastomeric materials specially Iralgin.

Background and Aim: There is an increasing global tendency to use traditional medicines and drug-extracts from natural plant materials. This in-vitro study was conducted in order to evaluate the cariostatic effect of hydroalcoholic extract of Salvia officinalis and Achillea millefolium.Materials and Methods: In this experimental study, hydroalcoholic extracts were prepared from Salvia officinalis and Achillea millefolium using maceration method. The antibacterial activity of these two extracts against Streptococcus mutans, Lactobacillus rhamnosus, and Actinomyces viscosus were evaluated through broth macrodilution method. Data was analyzed with Mann-Whitney test.Results: The Minimum Inhibitory Concentration (MIC) of Salvia officinalis and Achillea millefolium for streptococcus mutans were 6.25 and 50 micro gram per milli liter, respectively. The corresponding figures for Lactobacillus rhamnosus were 1.56 and 12.5 micro gram per milli liter; and for Actinomyces viscosus the value were 12.5 and 50 micro gram per milli liter, respectively. The differences between the two extracts were statistically significant.Conclusion: Both extracts had growth inhibitory effect on all three bacteria. Salvia officinalis showed greater inhibitory effect on growth of all three bacteria. Both extracts had bactericidal effect in the considered concentration range.

Background and Aim: In 1993, Mineral Trioxide Aggregates (MTA), a grey-colored material was introduced to dentistry. A similar product in white-color was also produced later. The aim of this study was to review the literature in order to compare the chemical composition of these two different types of MTA.Materials and Methods: Over 600 articles have been published about the properties of MTA, 33 of which were about chemical and 28 were on its physical properties. In addition, about 80 articles have been published on similarities and differences between MTA and Portland Cements (PC). This article reviews the history of MTA’s manufacturing, its introduction to market, its patent, its commercial brands, and its similarities with PC. We also reviewed size of powder particle, setting form, and also hydration reaction of MTA.Results: Mainly consisting of CaO and SiO2, MTAs and PC have similar compositions. MTA also contains Bi2O3 as an opacifier. The main difference in chemical composition of white MTA and PC with grey MTA is that the latter contains less amount of some minor elements specifically FeO. White MTA has finer particles and crystals compared to the grey one. No phosphate does exist in MTA composition, but during the hydration, this material is able to release calcium and hydroxyl ions which, in reaction to exogenous phosphate, results in hydroxyapatite formation.Conclusion: Both MTA and PC are hydrophilic cements. Regarding the biocompatibility of these materials, MTA is considered suitable for clinical applications; while no permission exists for clinical use of PC.

Background and Aim: The purpose of this study was to assess the fracture resistance of two different designs of tooth preparation and fiber placement in fiber-reinforced composite restorations replacing a missing mandibular lateral incisor.Materials and Methods: Forty newly extracted human mandibular intact teeth (20 centrals and 20 canines) were selected for fabrication of twenty FRC inlay bridges. A box preparation design with straight fibers and a slot design preparation with curved fibers were implemented. After preparation, the teeth were mounted in self-cured acrylic resin with 6.5 mm distance from each other. PDL was simulated with polyether material. After taking impressions with polyether material, the impressions were poured with dental stone. The two groups of bridges were fabricated and bounded to teeth with panavia F2. The cyclic load of 1.2×106×20N×1.66HZ was applied with 130O angle. The samples were stored in 37oC water for seven days and then thermo cycled (2000 cyles, 5-55oC). The fracture strength was tested by a universal testing machine (Instron 1195) at a speed of 1 mm/min. The mode of fracture was observed under stereomicroscope. The data was analyzed by using independent sample T-test.Results: The mean fracture resistance for the box design and direct fiber group was 1411.07 N and in the slot and curved fibers group was 377.33 N. The group difference was statistically significant (P=0.012).Conclusion: It could be concluded that in fiber-reinforced composite restorations, box design with straight fiber has more fracture resistance than slot design with curved fiber.