JOURNAL OF RESEARCH IN DENTAL SCIENCES
Year:2019 | Volume:15 | Issue:4 (58) |Papers Count:9

Background & Aim: One of the most important problems after post space preparation is its bacterialcontamination especially before post placement and its effect on overall treatment success and incidenceof dental infections. So the purpose of this study was to compare the effect of calcium hydroxide andchlorhexidine 2% gel on bacterial contamination of post space. Material and Methods: This study was a clinical trial (IRCT2017041232777N1) and was performed assingle blinded randomized clinical trial. 45 maxillary incisors from 23 Patients which were correspondedwith inclusion criteria were selected and included. After access preparation and WL determination, canals were prepared with Mtwo rotary files till 35/0. 06. Sodium hypochlorite was used as irrigant. Finally EDTA was applied to remove smear layer. Canals were obturated by lateral obturation techniquewith AH26. After post space preparation first sampling was taken and CFU was determined. Thensampled were randomly divided into first experimental group was calcium hydroxide and the second waschlorhexidine 2% gel. The control group had not delivered any medicament. Then teeth were temporizedwith Cavisol and after two weeks by discharging and neutralizing the medicaments the second samplingwas done. then the change of CFU of bacteria was compared using ANOVA test, also TAMHANE testwas used to compare groups two by two. Results: In control group s. mutans after two weeks had increased 21%. In calcium hydroxide groupthese bacteies had decreased with the amount of 34 % and in chlorhexidine group this decrease was 17 %(p<0. 001). So the most effective medicament against S. mutans was calcium hydroxide. For E. faecalis incontrol group after two weeks had increased 400 %. In calcium hydroxide group these bacteies haddecreased with the amount 35% and in chlorhexidine group this decrease was 98 % (p<0. 001). Conclusion: It was seems that calcium hydroxide has better efficacy on S, mutans and Chlorhexidine hasbetter efficacy on E. faecalis bacteria in dental post spaces.

Background & Aim: Designing and fabrication of biodegradable and bioactive membranes are the importantissues in guided bone regeneration while these membranes should maintain their structural integrity duringrepair, have the required mechanical, physical and biological properties and selective permeability. One of theapproaches to achieve this purpose is the fabrication of composite membranes based on biopolymers. Materials and Methods: In this experimental research, the fabrication and characterization of compositemembranes composed of chitosan-silk fibrobin and polyvinyl alcohol have been performed. chitosan solution andfibroin-polyvinyl alcohol solution were mixed in different ratio and membranes were fabricated by solventcasting method. Mechanical properties such as tensile strength and ultimate strain percentage and physicalproperties including water absorption and degradation rate of membranes were investigated. Results: The FTIR spectrum of the extracted fibrobin showed peaks at 1650 cm-1, 1530 cm-1, and 1244 cm-1. The XRD and SEM images showed that the synthesized fibrin has the structure of beta plates. The results ofphysical and mechanical properties of membranes showed that the presence of fibroin in the compositionincreases the mechanical strength. Increasing the amount of chitosan in the composition increased the waterabsorption and degradation rate of membranes. Conclusion: Fibroin is a suitable polymer for increasing mechanical strength, controlling the degradation rate, improving the water absorption ability and is so biocompatible. Solvent casting method with controlling theviscosity of solution and solvent evaporation rate is appropriate method for fabrication the membranes.

Background and Aim: Since some sealants can control cariogenic microorganisms, therefore theevaluation of antibacterial effect of different sealants are the subject of this study. Materials and Methods: in this experimental study, the plates were divided into 5 groups. Group Icontrol: two plates including Blood Agar with Mutans Streptococcus (SM) & the other MRS withLactobacillus Acidophilus (LA). Group II: 6 plates Blood Agar culture with two wells and inoculation ofSM with addition of two fissure sealants; Clinpro 3M with fluoride &flowable composite 3M withoutfluoride. In group III all the steps were the same as group IIexcept that in which fissure sealants usedwere Conseal F with flouride& Eco-s without fluoride. In groups IV & V all the steps were the same asgroups II & III respectively except that MRS culture media with inoculation of LactobacillusAcidophilus was used. The diameter of the growth inhibition halo (zone of inhibition) was measuredusing calipers. The experiment was repeated for three consecutive days with 26 plates and the resultswere recorded every 48 hours. The data were analyzed using Two-way ANOVAResults: The diameter of growth inhibition halo for Clinpro 3M in the medium where Streptococcusmutans was cultured was 27/29+ 3/59mm&where Lactobacillus Acidophilus was cultured was 12/37+1/46mm which differed from other three materials significantly. (p<0. 000)Conclution: It seems, Clinpro 3M had the most inhibitory effect on Streptococcus mutans and, Lactobacillus acidophilus growth.

Aim and background: Behavior of endothelial cells can have significant role regarding theirproliferation and attachment on acellualr dermal grafts in regeneration procedures. The purpose of thisstudy is to evaluate the effects of two dermal scaffolds on attachment and proliferation of humanumbilical vein endothelial cells. Methods and Materials: This study was conducted on experimental approach. Human umbilical veinendothelial cells were seeded, experimentally. Two commercially available types of ADM were used. 1. Kish tissue regeneration co. 2. Knowledge Based Company of Persian Textile Products. Theproliferation rate in matrix and control groups were evaluated 12, 24, 84 hours and 7 days after cultureusing MTT 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide ) test. The morphologicevaluation was made after 24 hours incubation with Ethanol and Dehydrated Hexamethyldisilazane(HMDS) using Platinium coated drops. The surface and circularity of cells was examined byelectronic microscope. Results: The results for DAPI and MTT index was similar in 3 groups(P<0. 4). After 1 week thecontrol group rate was 2. 66 ± 0. 001, fist group, 2. 09 ± 0. 001 and second group, 1. 64± 0. 17. Theresult was statistically signi􀏐 icant. (P<0. 1)Conclusion: It seems, in experimental status, both matrix was similar in endothelia celladhesion. But, proliferation rate of endothelial cells was more in matrix 1 v. s matrix 2 after 7days.

Background & Aim: During cavity preparation, smear layer is created. This layer should be removedwith irrigators. Leakage may be decrease after irrigation. The aim of this study was to evaluate theleakage after irrigation by chlorhexidine 2%, sodium hypochlorite 2. 5% and water in glass ionomer classV restorations. Materials and Method: In this experimental-in vitro study, the class V restoration preparation wasprepared in the standard cervical portion of buccal accept in 51 human premolar teeth. The samples weredivided to 3 groups due to type of irrigants. Group 1: sodium hypochlorite 2. 5% was applied in cavity for30 seconds. Group2: chlorhexidine 2% was applied in cavity for 30 seconds. Then, all cavities werewashed for 10 seconds in order to remove agents and their extra waters. Group3: only washed withwater. The cavities were filled by Glass ionomer reinforced composite resins. After 1000 thermal cyclesof 5-55 ° c, the microleakage of samples, was evaluated with dye penetration and data was analyzedstatistically with chi-square. Results: The microleakage of enamel were 94. 1% in water irrigant, 41. 2% in chlorhexidine 2%, 17. 6%in sodium hypochlorite 2. 5% (p<0. 001) and for dentin, in water, chlorhexidine 2% and sodiumhypochlorite 2. 5% were 88. 2%, 70. 6% and 17. 6% respectively. (p<0. 001)

Background & Aim: Helicobacter pylori is a major cause of gastric ulcer and peptic ulcer and isconsidered a risk factor for gastric cancer. Gingival grooves in the teeth of people with chronicperiodontitis may act as a reservoir for H. pylori. Therefore, the aim of this study was to investigate thevirulence genes of H. pylori isolated from dental plaques. Material & Methods: The study was cross--sectional and from 120 patients with periodontitis referringto Tehran dental clinics, 111 dental plaque samples were isolated. Sterile physiology serum was used totransfer the sample. Growth in Brucella agar + 1% starch + 10-7% at 37 ° C and 95% humidity and CO2concentration of 0. 5% in CO2 incubator. In order to identify the molecules, DNA extraction wasperformed and then the sequences of JW22 and JW23 regions were used for accurate identification. Results: Of the 111 dental plaque samples taken from 120 participants in this study, 22 strains (19%)were positive for H. pylori which 10 strains carrying different H. pylori virulence genes. The molecularanalysis of the studied genes showed that the frequency of cagA, cagT, cagE, vacA and hrgA genesshowed that the prevalence of these genes was 19% of H. pylori strains of 3 (57. 5%), 1 (0. 19%), %), 2(0. 34%), 1 (19. 1%) and 1 (0. 19%), respectively. Conclusions: It seems that in spite of the presence of Helicobacter pylori virulence genes in the dentalplaque, to control the related diseases in addition to antibiotic treatments periodontal treatments anddental plaque control are also required.

Background & Aim: One of the important points in composite restorations is the bond strength, which, if reduced, can cause treatment failure and decay recurrence. One of the reasons for reducing the bondstrength can be the use of homeostasis in restorations. Therefore, in this study, the effect of aluminumchloride hemostasis on the shear strength of three-step and two-step bonds was investigated. Materials and Methods: This experimental study was performed on forty human premolar teeth in fourgroups as follows: A: Aluminum chloride + Three-step bond + Composite. B: Aluminum chloride + two-step bond +Composite. C: Three-step bond + Composite. D: Two-step bond + composite. Then the shear strength ofthe bond was measured in MPa and compared in four groups with Kruskal Wallis test. Result: In the three-step, non-homeostasis bonding group, the shear bond strength was 53/8± 47/3 MPaand with the homeostasis it was 45/4± 31/1 MPa, but this difference was not significant in these groups. (p < 0. 8) In the two-step, non-homeostasis bonding group, the strength was 83. 8 ± 35 MPa and withhomeostasis was 56/7± 27/9 MPa and the test showed that the hemostasis reduced the strength of bond. (p<0. 1)Conclusion: The hemostasis substance does not seem to have an effect on the shear strength of the three stepbond, but it decreases the shear strength of the two-step bond.

Background and Aims: Considering the importance of the related factors in learning and in the light of the fact that therewas no study of this kind on dentistry students, so this research has been carried out in 2016 to evaluate the relationship betweenmorning & evening patterns with the learning levels of dentistry students of Dentistry Faculty, Tehran Medical sciences, IslamicAzad University. Material & Methods: in this descriptive study, first, the students were undergo morningness-eveningness pattern by Horn-Oostberg method. Then, the relationship between students’ s learning level and the results of both end-of-session and end-termtests was evaluated by a linear regression test. Results: In this study, 69 dentistry students were participated. 22 persons (31. 88%) had an overnight sleep pattern, 28 persons(40. 57%) intermediate, and 19 persons (27. 53%) in the morning. in both tests, there was a significant correlation between themorningness-eveningness pattern and the learning level. End-of-session test with (P <0. 004) and end-term test with (P <0. 002)Besides, There was not any significant correlation between age and sex of participants and their level of learning (P = 0. 45, 0. 10) in both tests. Conclusion: It seems, The morningness-eveningness pattern of the students analyzed in this study was significantly correlatedwith their learning outcomes, that is to say that students who had morningness pattern had higher scores than midway ones andthese ones had better scores compared to the eveningness ones.

Background and Aim: One of the concerns of dentists is maxillofacial pain and sinusitis symptoms thatbe related to presence of Haller's cells. Considering the importance of the issue and the differences inprevious studies, the aim of this study was to determine the frequency and apparent characteristics of thesecells in Iranian population using digital panoramic radiography. Materials and Methods: In this descriptive study, 650 panoramic radiography, which were in terms ofcontrast, clarity and darkness were acceptable, were collected from patients with no history of trauma andsurgery in the maxillofacial area. Then, the presence of Haller's cell and its apparent features wereevaluated and frequency was estimated by statistical analysis with 95% confidence in society and the effectof age, sex and side was judged by Chi-square test. Results: Of the 650 examined samples, 32% had Haller's cell, of which 28. 8% were in men and 71. 2% inwomen, and the sex did not play a role in the number of Haller's cell (P <0. 4), but Haller's cell in terms ofage (Over 39 years old) was found in 81. 2% and was not found in 28. 7% which was significant (P<0. 0001). Most of the Haller's cell were observed to be round (46. 2%) and oval (51. 4%), frequency of theHaller's cellin left side was 23. 5% and in right side was 25. 5%. in 50. 4% observed in both side. Conclusion: considering that Haller's cell can play a role in the development of maxillofacial pains, it isimportant to be aware of its existence, and it seems that as the age rises, this anatomical feature appearsmore.