Journal of Dental School
Year:2003 | Volume:20 | Issue:4|Papers Count:17

Background: Mineral Trioxide Aggregate (MTA) plays a great role in periradicular surgery and treatment of complicated endodontic cases. Including perforations the only problemwith MTA is its cost and storage limits. Aim: This research was conducted to evaluate the biocompalialinota material portland cement with a comparison to the original. Materials and Method: Both MTA and P.C were placed in polyethylenetubes prior to an implantation process of them under the skin of 45 rats, (shoulder and Gluteal areas). The rats were devided into three groups of fifteen. Each of which weresacrified in either 3 days, one week or one month intervals. Histopatologic assessments were made for the degree of inflammation, type of inflammation, foreign body reaction and formation of fibrous capsula. Result: Differences of the degree of inflammation was significantbetweenMTA or P.C. and control group this difference was, howere, only seen in one week period. (P<0.5). There were no significant difference in 3 days and a week period in foreignbody reaction and giant cell formation. The difference was however become significant betweenMTA or P.C and control group in one month. Conclusion: Portland cement could be considered as an alternative to the MTA. Future studies and clinical researches are also strangly recomended.

Aim: This investigation was designed to determine tongue location and movements on palate in pronunciation of Persian alphabets and selected words in control and TT groups.Subjects: Ten persons with TT habit and 10 persons without this habit, 9- 13 years old, which were matched due to age, sex, race, type and severity of malocclusion, with no history of orthodontic treatment, surgery and systemic diseases.Materials and Method: Phonetic test was done to exclude patients with speech disorders. Maxillary alginate impression were taken to construct upper removable appliance with 12 electrodes. Fine wires connected the electrodes to a electro palate-vision device designed for this study. The removable appliance was inserted on the upper arch and then Persian alphabets and some selected words were pronounced by both groups. A marker was designed for every electrode on the device. Tongue movements on palate were shown by these markers. Tongue movements on palate were shown by these markers. After recording the tongue movements, the location of tongue and the quantity of the tongue contacts were compared by T. student and chi-square tests.Results: Tongue position on palate in pronunciation of Persian alphabets will be discussed completely in the two groups. In the TT group, tongue had more contact with the palate in 6 points (P<0.0005) . In pronunciation of alphabets, tongue was more forward in TT group. The quantity of tongue contacts with palate was similar in both groups.Conclusion: Combination of alphabets to words and sentences in speech reduces the difference in speech between TT and control group. Although there is difference in tongue movements to pronounce the alphabets between the two groups but they are similar in speech.

Background & Aim: Most of the endodontic ally treated teeth require extensive restorations, including dowel and core. Post space preparation involves differen stages. Someclinicians make it immediatelyafter the conletion of RCT while some prefer if done several days after the root treatment is comleted. To compare the performance immediate and delayed post space several important factors such as apical microleakage and type of sealer affect the results of final treatment. This research was carried out to compare Apical Microleakage in preparation immediateand delayed post space preparation using two different sealers (AH26 and Apexit). Material and Methods: The method of intotal, 96 single rooted human teeth were selected and divided randomly into four groups in this study was experimental. Two positive and negative control groups were also designatol for this study. Results: Result revealed no significant difference of microleakage level between two groups (delayed and immediate) using two differen types sealer (AH26- Apexit). Conclusion: It seems that the usae of the sealer has no effect on micro leakage level of the root fillings white different operatory systems of immediate and delayed had a significant effect on the result of microleakage measuremen

Background and Aim: ZOE has been used in different fields of dentistry for many years. A locally produced component (Zoliran) has been recently introduced to the marketwith similar characteristic to the original Zonalin. Because of a lower cost involved to use Zoliran cement and its availability, confirm reliability of its physical properties. This investigation was designed to assess the Compressive strength of Zoliran cement in comparison to Zonalin cement as the standard material. Materials and Methods: Five samples with dimension of 4mmx6mm of each cement were provided and stored in distilled water in 370C±10C for a period of 24 hours. The lowest load of force was registered as the reference to which the sample could be broken by(according to the criteria No: 30 of ANSIIADA). The value of compressive strength was then calculated using the following formula (K =4F/πD2 ). Results: The mean compressive strength of five samples was measuredas: 14.33 Mpa for Zoliran cement and 31.83 Mpa for Zonalin cement. The mean compressive strength of Zonalincement was significantly higher than the mean suggested in ANSl/ADA Specification No.30. The mean compressivestrength of Zoliran cement was also lower than the mean value registered in ANSI/ADA SpecificationNo.30. Conclusion: Compressive strength of Zoliran cement was significantlylower than that of Zonalin cement. Further tests are required to compare the other physical properties of this material before it can be clinically recommended.

Aim: Hydroxyapatite is a biocompatible material that is uses to reconstructing bone defects in oral and maxillofacial surgery as well as other bone defect. It"s commercialtype (Allotropat-50)is not very popular in Iran concerning it"s price and utilization. The purpose of this study was comparision of biocompatibility of a new Iranian product to the commercial type in rabbits mandible. Material and Methods: A double blind clinical trial was couductedon and oryctolocus cuniculs rabbits.An incision was made at the body and border of mandibleand 16cavity prepaired, 6 filled with hydroxyapatite,5 with Allotrropat-50 and 5 remained empty. After three months the rabbits were sacrificed and the mandible resected and fixed. Serial sectiens with 5µ thickness were prepairedand colored by H&E. Theses sections were divided into three groups by means offibrofic, osseous or granaIonseen in the samples blindly. The difference between groups was tested using X2. Results: In all groups the bone induction was there mode rate or high and no statically difference was revealed. Conclusion: The biocompatibility of the new reduct was the sameas AlIotropat-50and control.

Background and Aim: The present study aims to evaluate the effects of prostaglandin E2, vitamin D and calcium on orthodontic tooth movement(OTM) and consequent root resorption in rats. Material and Methods: Forty eight week old male wistar rats weighing 230-300 grams were randomly divided into five groups. On day zero, the orthodontic appliance, consisting a 10mm long closed coil spring (stainless steel, 0.008 x 0.022 inch), connected posteriorly to the right first molar and anteriorly to the upper right incisor using a ligature wire (0.010 inch). The force employed was 60g . The first group received vit D(1.5 IU/ml) injection into the thigh muscle.The second group was administered Vit D and Ca (200 mg/kg) injections intraperitoneally. The third group was injected Ca alone and the fourth group received both vit D and 0.1 ml PGE2 (I mg/ml). The last group had a combined injected of Ca, Vit D and PGE2. Results: Results indicated significant differences (P<0.05) in the rate ofOTM, only between these who reieved and these didn"t. A significant (P<0.05) difference was found between the amount of root resorption of the first and the second groups, the second and the fourth groups, the second and the fifth groups and the third and the fifth groups. Conclusion: Judicious local and systemic use of chemical agents might prove helpful in particular cases, although further research is certainly warranted.

Aim: The purpose of this study was to evaluate the diagnostic value of SNA and SNB in sagittaljaw assessment. SNA and SNB are the most popular measurements utilized for sagittal jaw assessment. Validity of these measurements are affected by different factorssuch as anteroposterior position of Sella and Nasion as well as age, sex, and geometric factors so that validity reported for these measurement are between 46-80%. Materials -ond Method: Pretreatment lateral cephalogram and photographs and dental casts of 117 orthodontic patients selected randomly ITom the archieve of Shahid Beheshti University. Diagnosis of 5 orthodontist with interobserver reliabillty of 79% using all informationexcept SNA and SNB used as gold standard and compared to SNA and SNB by reporting sensitivity, specificity, positive predictive value, negative predictive value and accuracy as well as ROC analysis. Results: Sensitivity and specificity of SNA in diagnosis of maxillary prognathsm and retrognathsm was 11.1% and 91.90% and 50%, 66.7% respectively. For SNB it was better (28.6% and 96.9%) and (spe. 70.4 and 69.8%) respectively. The area, under ROC curve also confermed the same information. Conclusion: SNB showed much better than SNA specially in mandibular prognatism. Using the best cut-off point also ,improve validity of measurement. Corrected SNA and SNB using 6° SN validity also improve validity specially for SBN.

Aim: Recurrent upthous stomatitis is a lesion with high prevalence and inspite of numerou studies, there are little knowledge about its different aspects. Success in RAS treatment depends on correct diagnosis, and control of etiologicand systemic factors contributing to its development."Adcortyle" is a chemical drug widely used for symptomatic relief of RAS lesions but it has some disadvantages such as undesirable side effects and high price. "Myrtle" is a herbal drug, that has been used for RAS treatment since a few years ago. This study carried out to compare the effects of these two drugs on RAS leasion. Material and Methods: The study was a clinical trial with sequential sampling. Samples were divided into 3 group (A,B,C) taking "Myrtle", "Adcortyle" and placebo respectively.Three groups were matched according to education, history of trauma at the site ofIesions, location and number ofIesions, the use of antibiotics during 2 days ago, history of burning sensation and history of systemic diseases contributing to the development of lesions. The results were analysed using t-test and chi-square. Results: The tome of burning sensation relie of were 2.71±0.95 (A), 2.64±0.76 (B) and 6.8±1.23 (C) days.According to T-Test, there was significant difference between Band C and also A and C (P<0.01),but there was no significant difference between A and B drug. A and B reduced the time of objective improvement significantly compared to C group (P<0.01),but there was no significantdifference between A and B (P<0.001). The numberof cases treated with Adcortyle were less than that of treated with Myrtle (P<0.001). Conclusion: With regard to the above results "Myrtle" can be used as a substitute for "Adcortyle" in our country because of its less side effects and better availability.

Background &Aim: Adjunctive use of both mechanicaland chemical methods is advised for plaque reductionand decrease of gingival inflammation. Chlorhexidine is consideredas the most effective mouthrinse, in this regard. This study was there fore, designod to compare the effects of an Iranian made prodnt with the orginl chlorhexidine (BP) on gingivitis. Material and Methods: A group of 42 dental studentsat Shahid Beheshti University were celected who meet the including criteria. The following periodontal indices in childrens PI,GI,PBI,ETSI,CSI were measured as the baseline. Teeth were then divided into 2 groups.Each case was aked to use one of the mouth rinses ineach group again. All measnrements were repeated at the end of the month except the csi as Results: Results showed that the effect of Iranian chlorhexidinecould be considered at anacceptable leveland close to the original, chlorhexidine solution made. Conclusion: Due to results of this study the Iranian mouthwashhas comparable characteristics as the foreign one.

Aim: The aim of this study wasto investigatethe effectofHEMA as a primingagentonshearbondstrengthof composite resin to dentin before the application of an enamelbonding agent. Occlusal dentin of thirty six intact extracted premolars were exposed, etched and blot dried. Teeth were divided in four groups each consisted at a specimens. In group one, a mixture of 35% HEMA and acetonewas used to prime the dentine before enamel bond. In group two, a mixture of35% HEMA and water was used as priming agent. In group threy only enamel bonding agent was applied on dentin. In group four, scothbond multipurposesystem was employed as bonding agent. Shear bond strength test was carried out one week after preparation using an instron testing machine at a ckossheasspeed of 15 mm/min. Results: The results indicated that group four exhibited significantlyless shear bond strength than the orthers ans orther differences were not statisficaly significant. Conclusion: It was concluded that utilizing HEMA as a primingagent preceding the appliceation of enamel bond significantly increased the shear bond streugth of compositeresin to dentin.

Background and Aim: SCC is one of the prevalant cancers of oral cavity and humanpapiloma virus (HPV) has been introduced as an etiologic factor of it since the last two decades. HPVis a epitheliofroph DNA virus and it can be find in more than %90 of the genital cancers. Due to the similarity of genfital mucosa to oral mucosa it may be respensible for oral cancers. Material and Methods: In this study the relation between HPV precancerous and cancerous lesions (SCC,Leukoplakia, Lichenplanus) has been detected by PCR method and comparedto control samples. 44 parafined blocks (I9 SCC, 18 leukoplakia and 7 lichenplanus) were compared to 44 control samples matched by age and sex. Results: 22 samples of eperintal groups and 12 samples of the control group were HPVpositive (P<0.05). The positive samples were tested by PCR for HPV6,8.ll,16.18,31,33 type. Only in the leukoplakia group HPVhas a significant difference between cases and control (P<0.05). The most prevalant locationof HPV was in tongue and at 20-25 years (%75) and 60-69 years (%67) group. (5 cases form 6) Sex had no significant effect. From the 34 . HPV samples, 5 were HPV, 5 HPV11,5 HPVI6, I HPV33 and 19not detected. HPV8. HPV18.HPV31 had zero prevalence. In one sample bolh HPV6 and HPV16 were defected. Conclusion: Tt seens that HPV cmay be one of the etioJogic factor ofleuokoplakia and may induce maliognant changes.

Aim: With regard to importance ofbacteriae and their products in initiation and perpetuation ofpulpo-periapical pathosis and it is so that the key objective of root canal therapy has been the elimination or reductionof microorganisms in root canal system and dentinal tubules with irrigationand debridment, this experimentalinvitro study was done to compare the antimicrobial effects of three Iranian intracanal irrigants: 2.6% Sodium hypochlorite (A), 0.2% Chlorhexidine gluconate (B), 1%Bethadine(C), on infected dentinal tubules infectedwith two pathogenic and resistant microorganisms. Materials and Method: The smear layer of 105 prepared specimens was first removed, subsequently all specimens were infected with two known bacterial isolates;candida albicans(Fungi)and Actinomyces israelii (bacterium). The infected specimens were exposed to the 3 aforementioned irrigants for periods of 5 minutes, 30 minutes, 60 minutes. The existence or elimination of tubular infection was determined by incubation of dental specimensin test tubes containing Brain and heart infusion broth (BHI). If turbiditywas observed, the degree of it would be measured by comparison to McFarland"s tubes; then we culturedtarget organisms on the surfaces of Sabourd"s Dextrose agar (SDA), and Brain and heart agar (BHI)to countthe colony forming units (CFU/ml) of candidal yeasts, and candida with Actinomyces microorganisms respectively. Results: The results of this study indicate that 100%of the specimensof positive control group (placed in strerile saline) showed positive response after culturing. All three irrigantswere more effective than saline in eliminating tubular infection with test microorganisms. SolutionA was moreeffectivethan B and B was more effectivethan C. In restriction of tubular infection with Candida-Actinoinfection,but solution B was more effective than A and A was more effective than C in decreasing the CFUs of candida infectionof tubules. To eliminate tubular infection with target microorganisms the irrigants must be used for at least 30 minutes. Conclusion: To eliminate tubular infection with resistant microorganisms like Actinomyces israelli.The best irrigant is sodium hypochlorite and for elimination of candida albicans. The best solution is chlorhexidine guloconate and the minimum time for effective disinfectionis 30 minutes.

Background and Aim: Apical seal is one of the most important factors in successful endodontic surgery. Apicoectomyand Retrofill are a way the canal selecting a suitable Retrofill material has an important role in apical seal. Material and Methods: In this Invitro study 129 single root of human teeth wererandomly chosen and prepared by step back technique. Following root-end resection, retrograde cavity with 2mm of depth was prepared at the end of the roots. The cavity of study group was filled with MTA, Zinc free amalgam, and Ceramic in sterile condition. In this 60 days, study the number of the days required for Staphylococcusepidermidis to penetrate 2 mm of various root-end filling material (MTA, Amalgam and Cold Ceramic)was determined. Results: All samples filled with zinc-free amalgamshowed leakageduring 5 to 39 days. 22 samples among those teeth filled with cold ceramic had leakage during 7 to 53 days. IS cases ofMTA group didn"t show any leakage, while 15 remaining samples had at 8 to 55 days. Conclusion: The study has proved that cold ceramic is a suitable material form the point of sealing ability, but there should be more studies on other feature of this material.

Aim: One of the main problems concerning society health is conductive hearing loss which become more important in school age children. This study conducted for the purpose of the evaluation of rapid maxillary expansionon conductive hearing loss. Material and Methods: A total of 10 patient (6 female and 4 male) with the age of 13.98±2.25 years old and with bilateral posterior skeletal cross bite were selected for the study. The selected patients were tested with Pure tone test 3 times, before RME, after the opening of midpalatal suture and after fixed retention. All RME apparatus were manufactured in a laboratory activating by an orthodontist. Changes in pure tone thresholds for bone condition and air condition and also the air bone gap measurements and Eustachian tube function were noted. The paired t-test was used in order to identify significant differences between different records. Results: The study showed that there was statistically significant difference between the first and second records and first and third records for pure tone threshold (bone condition, air condition and air bone - gap), su-ggesting the notable improvement of both ears. There was no significant difference between second and third records which showed the continuos effect of RME. 8 cases (80 %) were suffering from type AD tympanic disorder before the treatment which changed to type AN. The other 2 cases had this disorder before and after the treatment without any change. Conclusion: The study showed the stable effect ofRME on pure tone threshold (air and bone conditions) and on air bone gap in all cases.

Aim: Several studies, rerealed that in pathogenesis of aggressive periodontitis, neutrophil dysfunction especially chemotaxis defects may have some role. But in other studies, there is no report of neutrophil chemotaxis defect in patients with aggressive periodontitis. In this regard, this study was designed to assess the chemotaxis of peripheral blood neutrophils in patients with aggressive periodontitis. Materials and Method: For this purpose, we studied the neutrophil chemotaxis of 27 patients with aggressive periodontitis which intum included: 12 patients with LJP; 7 patients with GJP; and 8 patients with RAP. Also,we included 10 normal subjects in our study as control group. The chemotaxis test was performed as leading&ont assay by using 3 micrometer filters and LPS-activated serum as chemotactic factor. Results: Statistical analysis by Kruskal WaIlis and Mann-Whitney U tests showed that the random migration of neutrophils in the case group (aggressive periodontitis patients) is significantly lower than control group (P<0.015) but in the case of netrophil chemotaxis, no significant difference was seen. The net chemotaxis of LJP group was significantly higher than control group (P<0.009). Conclusion: These results showed that there is no defect in the chemotaxis of peripheral blood neutrophils of Iranian patients with aggressive periodontitis. So it is likely that the neutrophil dysfunction is not important in the pathogenesis of aggressive periodontitis in Iranian patients. Of course more studies are needed in order to emphasize the above hypothesis.