Journal of Dental School
Year:2003 | Volume:21 | Issue:1|Papers Count:19

Background: 'Several diagnostic methods are being employed to detect bening and malignant lesions. One of which is silver nitrate staining for nuclcolar organizer regions (NORs). Researches have shown such regions as being useful in comparison of the tumors for detemination of changes.Aim: This study was designed to evaluate NROs as determinant for malignancy in salivany gland lumors.Material and Methods: A silver colloid technique was applied on paraffin sections of 12 cases of pleomorphic adenoma, 12 cases of Mucoepidermoid carcinoma and 12 Adenoid cystic carcinoma. A group of 12 specimens were selected with normal salivary gland tissue.Results: AgNORs were seen in 1.69±0.19 percent of the cases in normal tissue, 1.71±0.15 in pleomorphic adenoma, 2.18±0.94 in mucoepidermoid carcinoma and 2.61±0.45 in adenoid cystic carcinoma. Statistically significant differences were seen in AgNORs numbers between mucoepidermoid carcinoma and adenoid cystic carcinoma with pleomorphic adenoma and normal tissue (P<1.0001) similar results were seen between the different histologic pattern in adenoid cystic carcinoma and pleomorphic adenoma (P<0.05).Conclusion: The silver nitrate staining for nuclealar organizer (NORs) is a useful method for detection of malignant salivary gland tumors.

Aim: The bonding potential of porcelain laminate veneers to enamel is usually provided. This study was designed to assess the bond strength of these veneers using Asid etch, saline or sandblasting technique.Materials and Method: In this study, 30 disks of porcelain (2.4mm thickness and 9.5mm diameterer) were provided to measure the bond strength between laminate and resin. An initial preparation of one of the porcelain disk surfaces was carriedout using one of the following techniques: group 1 acid etch- silane, group 2 acids etch and group 3 sandblasting. A composite disk was then shaped and cured to each porcelain disk. Then maximum force needed was measured to break the bond between composite and porcelain.Results: Results showed that maximum bond was between composite and porcelain in acid etch-silane techniques while the least was in sandblasting technique. Analysis of variance showed no significant difference between group 1and 2, with a significant difference between groups 1 and 3, 2 and 3.Conclusions: There seems to be an advantage of combined use of asid etch-saline use prior to the application of bond in procelain veneer restoration strength.

Background and Aim: Vertical dimension of occlusion refers to the face height when the teeth are in occlusion.Several methods are used to determine the VDO. This study was designed to measure the closest speaking space associated with, free way space and facial measurements.Materials and Methods: A group of32 girls and 40 boys were selected in a systematic sampling manner.Results: Evaluations were made using statistical analysis showed no significant difference between closest speaking space and free way space.Regression analysis revealed that correlation between facial measurements and V.D.O. is also not statistically significant. But there was a linear relationship between overbite and V.D.O.

Background: Hyper keratinization in gingival epithelium is a very common finding in smokers. Deep pocket with no bleeding is usually sean in such patients.Aim: The aim of this study was to evaluate keratinization in sulcular epithelium. Thiscase- control study was performed to assess the influence of smoking on sulcular epithelium keratosis.Material & Methods: Specimens were obtained from 10 smokers through gingiual biopsy in addition to 10 nonsmokers during a periodontal surgical procedure.Results: Histological examination showed no significant association between smoking and sulcular epithelial keratosis and even the thickness of free gingiva and sulcular epithellium. Howerer smoking did increase the chanceal keratosisim oral epithelium at free gingiva.Conclusion: There was a clear indication of keratosed epithelium in smokers.

Background: As gag reflex is considered as a complication during most of the dental procedures, developing new techniques have always been a task for clinicians to overcome the problem.Aim: The aim of this study was to evaluate the effect of salt (Nacl) to temporarily eliminate the gag reflex during intraoral radiography.Material and Methods: A group of 256 patients (128 male, 128 female) were selected who had history of gag reflex from those reffered to Dental Radilogy Department a Kerman university. Patients were devided in to two groups. During the course of this study of case who used salt, and control group who used starch (as Plasebo).Salt was poured on anterior 2/3 the oftonque, five seconds before taking the dental radiograph. The same proucedure was accomplished with starch for the second group. Incase of an elemination of gag reflex afterpouringsaltor starch, the subject will be recorded as positive responder, other wise as negative.Results: Among 128 patients who were examined with salt, 113 individuals showed a positive respond (88.3%).While, among 128 patients who were examined with starch only 3 individuals showed a positive respond(2.3%).Conclisions: A possitive effect of NaCl could be councluded to relief the gag reflex based on the results of this study.

Aim: The aim of this study was to evaluate the frequency of TMJ disorders in a group of patients reffered to Shahed dental school.Material and Methods: A total of 52 patients with TMJ disorders were studied. Patients were evaluated for age, sex, medical history, dental history, socioeconomic status, occlusion, pain, sounds of joint, muscles tenderness, maximum opening, premature contacts, clenching and bruxism.Results: The results showed 35 patients were female and 16 were male. Mid age o.fpatients was 18-49, and most of them were 20-29.The prevalence of TMJ disorders was pain (%78.85) clicking (%73.08). Muscles tenderness (%76.92) limitation of maximum opening (%40.38).Conclusion: Prevalence of TMJ disorders was found to be high in women. Joint clicking and pain were the most common complaints. Correct treatment planning will reduce signes and symtoms.

Background &Aim: The presence of immunocompetent cells and various classes of immunoglobulins in inflamed pulps indicates that host immune responses could participate in the pathogenesis of pulpitis.The purpose of this study was to determine the changes of immunoglobulins in the supematant fluids of the explants cultures of various states of dental pulps.Material and Methods: For this purpose pulp of impacted teeth: were culyure with also healthy erupted teeth, teeth with irreversible symptomatic pulpitis; and irreversible asymptomatic pulpitis were cultured. The amounts of various classes of immunoglobulins were measured by SRID method.Results: The presences of IgG in the above states were 62.5%; 26.7%; 60%; and 100% with average concentration of 833.5±944.5; 81.1±2062; 23.6±30.6; and 786.5±799.5 mg/100ml, espectively. The differences between between these groups regard to concentration of IgG were significant (p< 0.002).The presences of IgA were observed in 50%; 6.7%; 10%; and 100%with average concentration of 213.1±257.6; 31.1±121.6; 4.25±13.3; and 282.7±212.2 mg/100ml, respectively. There was an also significant difference between the above groups for their IgA concentration (p< 0.001).IgM was present in 6.2%; 26.7%; 30%; and 0% with average concentration of 0; 54.7±132.2; 20±32.7; and 0 mg/100ml, respectively and the differences between these four groups were significant (p< 0.05).Conclusion: In conclusion, there are significant differences between the pulps of impacted and healthy erupted teeth, regard to presence and amounts of immunoglobulins.

Aim: The aim of this study was to compare tensile strength of pre-solder and post-solder joints for three dental alloys. 45 rods, 32mm in length and 25mm in diameter were made from degubond 4 (Au-Pd-Ag), porson 4 (Pd-Ag) and verabond (ni-Cr-Be).Material and Methods: 15rods for each alloy randomly divided in to three groups of control, presolder and postsolder.10 rods of each alloy were cut in half with a custom made cutting Jig and then positioned and stabilized at 13mm gap distance in an indexing Jig. Rods of deubond 4 and porson 4 were given a heat treatment to simulate porcelain firing. Specimens were soldered with manufacturers recommended solder with gas-oxygen torch (pre-soldering). Verabond specimens were soldered with gold and base-metal solder. Tensile testing was done on an instron machine. Model AB 725-AM.SM.At cross head speed of 2mm1min and result were recorded in kilogram.Results: 1- For Degubond 4, techniques of soldering has no sigificant effect on tensile strength of solderjoints.2- For Porson 4, tensile strength of presolder joints is significantly stronger than post-solder joints.3- The tensile strength of presolder joints for degubond 4 and porson 4 are significantly stronger than verabond.Conclusion: Tensile strength of solder joints depends on different factors such as type of alloy and soldering technique however this is not dearly predictable.

Aim: The purpose of this investigation was to assess the prevalence of edentulous patiants in Iran dunring 1998- 1999. Edentulouness is a good indicaton of evaluating oro- dental health status inapulation. The aim of this cross-sectional study was to evaluate the prevalence of edentulous cases in people above 35 years in three cities of Iran. (Torbat-e-heidarieh in the west Yazd in the center and Hamadan in the east) Material & Methods: The study was carried out by means of a question aire as well as clinical examination with random sampling out ot 1191 participants. The percentages of edentuluseness were 52.4% in Hamadan, 32.8% in Torbateheidarieh, and 40.7% in Yazd, while 5.78% in Hamadan, 3.4% in Torbate heidarieh and 6% in Yazd had all their 28-32 teech.Results: Results of this study showed that edeutulusness had significant relation with the following Factors: Age, education, oral health status. There was no significant relationship betweek gendar and and edentulousness.

Background: A laboratory model is needed for investigating the techniques and accuracy of impression materials.There are three techniques of making a laboratory model:1. Replica method2. Simulation method3. Abstract methodAim: This laboratory model was prepared on the basis of simulation method, to test ifs reliability.Material and Methods: This model consisted of two individual dies (one with an undercut under its margin and the other one without us chundercut). Special tray and guide rods were used to unify special trays path of insertion and exertion on the dies.

Background: This cleanliners of water supply is of considerable importance as both' patients and the dental personal are regularly exposed to water and it's aerosols generated from the dental unit. Many microorganisms have been isolated from dental unit water lines using a wide variety of recovery techniques. Although the risk of infection to most of patients from the water-borne microorganisms appears to be small, immunocompromised individualsbeing at the greatest risk.Aim: The purpose of this study was to evaluate the microbial levels in water system of the dental units in Shahid Beheshti University Dental School.Material and Methods: Water samples were collected from II dental units and 11 sidetaps. Samples were spread 11 on nutrient agar and the colonies were counted after 72 hours incubationin 37oC.Results: Microbial contamination levels in the dental unit water supply and their related tap water samples were 177318±2057 (cfu/ml) and 3578±33 (cfu/ml) respectively. Water contamination was significantly higher I, dental unit than that of the tap water.Conclusion: The dental profession must continue its awareness of the high levels of microorganisms found in the dental unit water. Indicates a clear need for prevention form microbial contamination.

Aim: This study was designed to evaluate the ability anthropometry as a new method of determining the VDO.Material & Methods: A group of 229 complete dentate dental students were selected with class I occlusion.Subnasal to submental was measured in maximum intercuspation. Subnasal to the incisal edge of the maxillary incisors was also measured in addition to submental to the incisal edge of the mandibular incisors. The last measurement was performed at submental to mentom groove and right and left bipapillary areas. Measurements were made with a modified measuring gauge. The mean values and regression for the measurements were calculated and used for statistical analysis.Results: The mean value of alove the mentioned measurements were calculated which helped to determine the occlusal planes and V.D.O. Regression analysis between variables were from 0.27 to 0.66 (P<0.05).Conclusion: It is concluded that some guidelines could be used in determination the V.D.O using anthropometry.

Aim: The aim of this study was to evaluate the effect of local factors on gingival recession.Material and Methods: A total of 1044 teeth in 55 patients aged between 20-60 years were selected for this retrospective study. All local factors which were mentioned in literature were evaluated. Results: Different predisposing and precipitating local factors were found to have obvious effects on gingival recession with various Odds ratio. The effect of each of these variables depended on the age of the patients too.Conclusions: A local factor has an important effect on gingival recession.

Aim: This study was designed to assess the level of gram negative bacterial contamination in water supply of dental units used at Shahid Beheshti University at the year 1999.Material and Methods: Water samples were obtained from water syringe lines and high - speed turbine lines of 30 dental units which were initially selected on random manner. All samples were stored in sterile tubes containing 5cc nutrient broth followed by an incubation stage on EMB and MacCankey plates for 48 hours at 37oC. Bacterial colonies were then counted and compared with suggested limit by ADA.Results: Sections of first floor had shown. Psedomonas and staphylococcus contamination were seen in 37.5% of the samples collected form dental units of surgical wards at first floor while 61.5% of the samples of dental units of restorative wards (2nd floor) had staphylococcus contam E.coli and Entrococcus contamination were found in samples of or the/paedo clinic water supply samples in 75% of the cases.Conclusion: there appeared to be a relationship between the increase in the number of microorganisms and water stagnation on the upper floors of the building.

Aim: The aim of this study was to compare the effects of Ethylen glycol tetra acetic acid (EGTA) and EDTA for their smear layer removal capability using scanning electron microscopy technique.Material and Methods: A group of 28 single rooted teeth were instrumented to size 60 master file. Four teeth were also kept as control while the remaining teeth were divided into two groups. Group A: in which 12teeth were irrigated with 10 ml of 17% EGTA for 2 minutes? Group B: consisted of 12teeth irrigated with 10 ml of 17% EDTA for 2 minutes. Both groups were then irrigated with 10 ml of 5% Naocl. the control group were just irrigated with 10 ml of 5 % Naocl. All teeth in then the control group were only irrigated with 10 ml of 5% Nacl. Specimeus were then sectioned longitudinally. A scanning electrone microscope was wsed to in vetig ate the intenal surfaces of the canal.Results: EGTA chelated dentin surface more conservatively than EDTA without causing erosion.Conclusion: It seems that EGTA can be used safely to remove smear layer from the canal surfaces.

Aim: The aim of this investigation was to detennine the efficiency of several toothbrushes on plaque removal.Material and Methods: This single blind crossover clinical trial was carried out on 10 dental students of Shahid Beheshti University of Medical Sciences. During the year 2000 (1379) cases were selected randomly from a group of volunteers. Each sample was examined under a dental chair light using a flat dental mirror, both before and after brushing. The modified steelman brushing method was employed to remove dental plaque with one of the following toothbrush: Oral-B, GUM, Crest, Jarda, Jordan, Mina, Laleh, Alfalij, Dr.Best, Mojan toothbrushes.Disclosing tablets were used to help identifying the plaque Index according to Turesky modification of Quigley and Hein Index (1962).Results: Analysis of the data using ANOVA test showed a significant difference between the level of cleaning at the buccal surfaces (p<0.02). However this difference was not significant between these groups at the lingual side using any of the brushes.Conclusion: Oral-B toothbrush was found to be significantly more efficient compared to other toothbrushes in its clinical perfonnance.

Background and Aim: An association between periodontal and other bacterial infections and coronary heart disease/ atherosclerosis has recently been observed in both cross-sectional and logitudinal studies. The objective of this study was to examine the association between periodontitis and (CHD) and coronary atherosclerosis.Material and Methods: A case-control study was arranged using 76 individuals (52 men, 24 women), with mean age: 51 years who were referred to general hospital for coronary angiography. Gingival attachment loss and coronary atheromatosis was assessed, together with measurement of the established coronary risk factors.Results: In the logistic regression analysis, odds ratios were 11.7 and 13.14 for attachment loss and CHD and coronary atheromatosis. For patients with attachment loss of greater than 6mm. Compared to those with attachment loss of less than 6mm, odds ratio of CHD and "two and three vessels disease" were 11.7 and 13.4 respectively. Odds ratio of each millimeter increase in attachment loss, for CHD was 2.18 individuals with less than 10 teeth compared to those with more than 10teeth had odds ratio of 3.77 and 4.4 for CHD and "two three vessels disease". No association was observed between age, systolic and diastolic blood pressure, smoking and CHD, which is not quite reliable due to the small number of participants.Conclusion: This observation shows an association between the severity of periodontitis and CHD and atherosclerosis also supports the proposal that periodontal infections play a role in the pathogenesis of coronary atherosclerosis.

Aim: This study was performed to assess common factors involued in esthetic smile detemilation using anterior component of dentition in a group of dental students.Materials and Methods: This descriptive study was corried out using a sequential sampling technique. A group of 157 students (75 females with 82 males) were selected who were considered with normal smile. Attempts were made to avoid including individnals with any visual tension inrelation to the student or study criteria. Factors assessed were: lip line, smile line, upper lip curvature, tooth visibility, negative space and gradation. Repeated and careful visual judgement were perform posed smile's photography feach individual.Results: Results indicated that the majority of lip lines were in the average 33.7% level of the natural criterial in esthetic smiles. Smile lines were convex at 96.8% of the cases white. Upper lip curvatures were upward in 55.4% 1.51 percent of the cases had their second premolar in tooth visibility limit. Gradation in bilaterall form was present in 87.3% of the covers white bilateral negative space was present only in 54.1%.Only two factors of lip line (P<0.002) and tooth visibility (P<0.005) presented statistically significant differences between men and women.Conclusion: Parallelism of smile line with upper curvature of lower lip and gradation are the two more frequent factors in esthetic smile. The field of unity and variety in factors studied in esthetic smiles and gender differences suggest that these factors must be evaluated before designing anterior restorations.