JOURNAL OF RESEARCH IN DENTAL SCIENCES
Year:2010 | Volume:7 | Issue:1 (23)|Papers Count:10

Background and Aim: For successful endodontic treatment Sealer is needed , and gutta-percha alone, cannot prepare hermetic seal . One of important clinical and physical characterization of sealer is setting time. This study was conducted to evaluate setting time of AH 26 , 2_Seal, Dorifill, ADSeal Meta and SDS. Materials and Methods: In this in vitro Randomized blind experimental study, sealers were AH 26, 2 Seal , Dorifill , ADSeal Meta and SDS (Iranian ZOE sealer ). Methods and material was according to ISO_6876:2001 2nd ed, "Dental Root canal Sealing Materials". 25 Samples were investigated, 5 for each group. OneWay ANOVA analysis was used by statistical specialist to show the results ( P<0.05).Results: Setting time in minutes were: AH26 = 814.2, Dorifill=93.8, 2Seal=738.4, ADSeal Meta =49.8, SDS =270.6.Conclusion:  Although, all of sealers investigated here have a proper unique specification, but in conclusion and with all investigations until now, sealers with epoxy resin base, with their variety of setting time, are better  sealers and can be used for different techniques, different peoples and different treatment, that needs sealers with short or long setting time.

Background and Aim: The widespread use of antibiotic for prophylaxis and treatment of bacterial infections has lead to emergence of resistant human pathogens the aim of present study is to determine the proportion of bacterial resistance to amoxicillin and tetracycline in subguingival plaque samples of A a ,P g ,F n and EC from patient with chronic periodontitis.Material and Methods: Two subgingival plaque samples were taken from 20 subjects with chronic periodontitis and transferred in Thyoglycolat broth chocolate agar in Co2 (5% atm) and Aa, Pg, Fn, Ec had been identified. Antimicrobial susceptibility test were performed by Etest on Muller blood agar. Results: from 40 samples 19 samples had Aa , 8 samples had Pg , 10 samples had Fn and 3 samples had Ec . All of these bacteria were susceptible to both of amoxicillin and tetracyline. Conclusion: This study showed that amoxicillin and tetracycline were effective on periodontal pathogens and studied bacteria were 100% susceptible to these antibiotics so it seems they can use in treatment of periodontitis.

Background and Aim: Bond failure between bracket and tooth is one of the problems in orthodontic treatments. Placement of bracket increases the accumulation of plaque and periodontal problems, different ways such as mouth rinses are used to control these problems. The purpose of this study was to evaluate the effects of Ortho kin and Oral B mouth rinses on the shear bond strength of orthodontic brackets, taken in the faculty of dentistry.Materials and Methods: In this experimental study, the brackets were bonded with a self cure composite to 45 human premolar teeth. Then the teeth were divided into three equal groups. The samples of all three groups were stored in artificial saliva for two weeks. The samples of experimental groups were placed in Ortho kin and Oral B mouth rinses for 60 seconds twice a day. The shear bond strength (SBS) values and adhesive remnant index (ARI) scores of the groups were evaluated and the data were analysed statistically by one-way analysis of variance (ANOVA), LSD and Chi-square tests.   Results: Control group was found to have the highest SBS for 15.27±0.58 Mpa, followed by Oral B group for 10.11±0.94 Mpa. Ortho kin group had the lowest SBS for 7.59±0.59. The differences were statistically significant (P<0.001). Ortho kin group showed a higher frequency of ARI score of 2, but in Control and Oral B groups ARI score was 3. The differences were statistically significant (P<0.001).  Conclusion: The application of Ortho kin and Oral B after bracket bonding decreased SBS but the values were well within the clinically acceptable range of SBS. It is suggested to use Oral B instead of Ortho kin due to the higher SBS.

Background and Aim: For each and every graduate student the process of composing a thesis is the center part of training and education in research methodology. The content of such material becomes important when the research study turns into a manuscript which is submitted for publication in a journal of medical sciences. Deficiencies and drawbacks in terms of research methodology in student theses still remains a controversial issue. Due to lack of sufficient information concerning the accuracy of research methodology in student theses, the purpose of this study was to evaluate the accuracy of research methodology in several aspects of student theses including: research variables, study population, sample size, sampling method and associated factors. The research was conducted on student theses in Islamic Azad University, school of Dentistry in 2007-2008.Materials and Methods: All presented theses from 09/23/2007 to 09/21/2008 in Islamic Azad University, Dental Branch were evaluated in this descriptive study. Based on 13 variables, aspects such as research variables, study population, sample size and sampling method were assessed for accuracy and classified into 3 categories (correct, relatively correct and incorrect). Information regarding associated factors including student specifications, related department and head researcher… were collected and entered into a data sheet. Each thesis was assessed for accuracy as follows: "correct: if more than 75% of variables were correct"; "relatively correct: if 50-75% of variables were correct"; "incorrect: if less than 50% of variables were correct". The role of associated factors was determined using chi-square statistical test.Results: 137 student theses were evaluated. The rate of inaccuracy in research methodology of research variables, study population, sample size and sampling method was found to be 40.2%. Failure to justify the sample size was seen in 71% of the cases, incorrect organization of data sheet was reported in 53%, and not stating all the variables including new and compound variables was seen in 37% of theses.Conclusion: This study indicated that there are significant drawbacks in student theses which mandate proper steps to be taken to reduce the level of inaccuracies in research methodology. This will not only improve the validity of the research itself but will also provide reliable results to be applied to general population.

Background and Aim: Since today using dental implants which be substituted destroyed teeth is completly effective and current. The researchers make effort in design and making new generation of implants for having mere resistance against applied forces. This research has evaluated the pattern of horizontal and vertical forces distributed in implants with or without microthread using finite elements method.Materials and Methods: We have used the developed software Ansys 11 for modeling, applying forces and stress distribution evaluation. Cortical and Spongy bone in the limitation of implant with natural dimensions were modelled. In this research Superline and Implantium implant systems with the diameter of 4.3 mm & length of 12 mm, T.B.R (Connect) and Branemark MKIII implant system were modeled with the diameter of 4 mm & length of 13 mm, Each model were simulated in the bone. Vertical force of 200 N and horizontal force of 100 N and resultant of the force exerted to lingual abutment. The amount of vertical & horizontal stress and shear stresses and maximum shear stresses and equivalent stresses were measured.Results: Under horizontal and inclined (lateral) loading the microthread systems showed less stress in comparison with microthread less systems in buccal and lingual cases. More over Branemark system showed less stress in lingual level and highest stress in buccal level. Under loading of vertical forces the microthread and microthread less systems showed different behaviors. T.B.R system showed less stress and Superline showed highest stress and Branemark placed in the third level after implantium.Conclusion: The findings in this research showed considerably the effect of microthreads in the stress distribution in the bone under different loading. It means that the dentist can control the quality & quantity of stress distribution in bone through selecting special implant design.

Background and Aim: In last 2 decades, a lot of research has focused on composition, surface roughness and their effects on success of implants. In general, surface treatments of dental implants include; surface roughness, Osseo inductive and therapeutic biologic coatings. The aim of this literature was a comprehensive review to present the studies related to surface treatments of dental implants and its effects on success of dental implants.Materials and Methods: Relevant published papers in English up to end of Feb 2009 were reviewed. The articles were located through Medline and COHG (Cochrane Oral Health Group database). Publications reviewed included experimental animal studies, prospective and retrospective human clinical studies, a few case reports and relevant review papers Agreement between the reviewers was determined performing k²-statistic. Disagreements were resolved by evaluation of the full texts and discussion. Due to heterogeneity of the factors in different studies, no meta-analysis performed. The results of different studies presented in a systematic manner.Results: In general, surface treatment is mostly focused on increasing surface roughness. Two ways for increasing surface roughness are additive and subtractive methods. According to particle size, surface roughness may be classified as minimally rough (Sa - 0.5mm), moderately rough Sa > 2.0 mm) or rough (Sa > 2.0 mm). Plasma spray, acid-etching, sand blasting and anodic oxidation are important methods for creating surface roughness. Increasing surface roughness enhances Osseo integration especially in early stages of healing. Surface roughness also improves bone to implant contact. This will reduce the healing time and enables the implants to be early or immediately loaded. In addition surface roughness increases the success of implants in poor bone quality. On the other hand high surface roughness could increase the possibility of peri-implantitis. Therefore, most brands of newly marketed implants are moderately roughed. This is a comprehensive review of about 120 papers which explain different methods of implant surface treatment and its ultimate effects on treatment of dental implants.

Background and Aim: To evaluate the bond strengths of FRC posts (Glassix "Nordin dental/Swiss" and Matchpost "RTD/ France") to root dentin after silanization. The null hypothesis tested was that silanization would produce greater bond strength.Materials and Methods: Roots of 40 human freshly extracted maxillary central incisors were endodontically treated and were divided into 4 group of each 10 (n=10.) They received the following treatments. Group 1: Glassix post + silane primer; Group 2: Glassix posts without silane primer; Group 3: Matchpost + silane primer;  Group 4: Matchpost without silane primer. The posts were cemented with panavia F2.0 dual cure resin cement. Each root was cut into 3 slices (2mm height) representing 1/3 coronal, middle, and apical portions respectively. After push-out  bond strength testing (at the cross head speed of  0.5 mm/min), the type of failure at the interface was determined. Results: Silanization of fiber posts had no effect on shear bond strengh (p>0.05). Without consideration of silanization, type of post had also no effect. (p>0.05). The apical third of the specimen had the greatest bond strength (p=0.001).Conclusion: Neither silanization of fiber post surfaces, nor the type of fiber post seem to have any statistically significant difference on shear bond strength of FRC posts to root canal dentin. Most of tested specimen had an adhesive failure mode at the interface of cement-dentin.

Background and Aim: According to the large number of surgical removal of impacted third molar and prevalence of pain and side effects and importance of prevention to reduce these side effects, the present study was held to evaluate the influence of modified triangular flap and buccal envelope flap on incidence of dry socket and postoperative healing after surgical removal of impacted third molar on patients who came to oral and maxillofacial surgery Department of Tehran Azad dental school and one private office in 1387.Materials and Methods: The study was a double blinded clinical trial design. It was hold on 19 patients at the age of 17-23 which were candidate for bilaterally impacted third molar extraction with the same difficulty index. Influence of modified triangular flap and buccal envelope flap were evaluated on dry socket and healing at 3 days and one week after surgery. changes in upon characteristics in two groups were analyzed with  Mann u- Whitney and Fischer's exact Tests.Results: Two of patients were excluded for different reasons and study were completed on 17 patients (34 sample) .age of the patients were 19/94±1/5 .70/5 female, 47/1 had academic educations. Pederson difficulty index was 7-10. Incidence of dry socket in control and test groups were 41/17, 11/76 ,(P< 0/05 ) . The average of healing at the 3rdday after surgery in control and test groups were 3/94±1/52, 0/82±0/73,(P< 0/001 ) and at the 7th day were 3/06±1/39,0/35± 0/61,(P< 0/001).Conclusions: The modified triangular flap used in this study caused to decrease the incidence of dry socket and increase the healing at the 7th day after surgery of the mandibular third molars and the statistically significant differences was observed in dry socket and postoperative healing at the 7th day after surgery.  In addition to the positive influence of modified triangular flap in the surgery of mandibular third molars in this study, it is suggested to evaluate the effects of this flap on incidence of dry socket and postoperative healing in the mandibular third molars surgery with a systematic review Research.

Background and Aim: For certain surgical procedures (e.g. placement of implants), an accurate localization of the mandibular canal is of utmost importance to avoid injuries to the neurovascular bundle. The aim of the present study was to evaluate, the accuracy of spiral tomography for the localization of the mandibular canal.Material and Methods: By means of the cranex tome multifunctional unit (orion corporation Sordex, Finland), tomographic slices were taken at 4 different locations in each posterior mandible segments (distal to the mental foramen). The mandibles were then sectioned at these 4 sites with a specialize designed drill. The following 4 measurements were preformed both on the tomograms (A, B, C and D) and the bone sections (A’, B’, C’ and D’) at the 4 sites.Results: We found an average mean difference of 0.02 mm with a standard deviation of 0.33 mm. The reported data showed that %95.2 of cases are in ±0.5 mm and %98.4 of cases are in ±1 mm (overestimate and underestimate).Conclusion: Spiral tomography using the cranex tome multifunctional x-ray unit provides accurate information and sufficient detail for preoperative planning of implant in the posterior mandible.

Background and Aim: Oral lesions are common in renal transplant patients taking immunosuppressive drugs. The presence of oral lesions in these patients as an infective center can effect on their graft prognosis & face the people with severe problems. The aim of this study was to evaluate the frequency rate of oral lesions in renal transplant patients & relative factors in Labbafinejad hospital (2007_08).Materials and Methods: The present study was descriptive. The cases were renal transplant recipient patients who were grafted at least one year ago. In Labbafinejad hospital from June 2007 to November 2008. The variables of the research were type of pathologic lesions, location of incidence, the time passed after graft administration, age, gender, smoking, drug dosage, other drug consumption, type of renal graft, systemic disease, situation of hemoglobin and FBS, blood group type. Statistical analysis was performed by spss & c² test.Results: The result showed that out of 250 patients, 159 cases(63.6%) have oral pathologic lesions. Gingival over growth, hairy tongue, gingival recession, gingivitis and halitosis were the most common lesions respectively. Systemic disease, oral hygiene & folic acid consumption have statistical relation with oral pathologic lesions in this group. There were no statistical relation between oral pathologic lesions & other variables.Conclusion: According to the result of this study, regular oral hygiene assessment in renal transplant recipient patients is recommended.