مجله دانشکده دندان پزشکی اصفهان
پیاپی 1 (بهار 1384)

Two important disadvantages of amalgam restorations are lack of adhesion to tooth structure and marginal leakage. In recent studies, the use of dentin adhesive on cavity walls before the insertion of amalgam proved to be the best method to reduce micro leakage and increase chemical adhesion. Forty premolar and molar teeth were collected and divided into two groups. The class V cavities were made at the buccal surfaces of the teeth (Depth 1. 5 mm, Length 3 mm and Width 2 mm). All the angles of cavo-surfaces were Butt joint. The teeth were then washed, cleaned, dried and randomly divided into 2 groups; the first group was coated with 2 layers of varnish. The second group was coated with adhesive resin system and then restored with amalgam. The teeth were kept in distilled water for 24 hours. The prepared surfaces were then polished and thermocycling was performed. All prepared surfaces were coated with nail varnish up to 0.5 mm around the restorative material. Furthermore each group was randomly divided in to 2 subgroups; one group was kept in distilled water for 24 hours and the other group for 5 months. All groups were afterwards kept in 0.5% basic fuchsin solution for 24 hours. The teeth were then mounted in Acrylic resin, were cut into two halves from the centre of preparation with a diamond saw and checked by a stereomicroscope for determining the microleakage rate. Comparison between two groups showed degree of dye penetration into margins of restorations with Rely X ARC was lower than that of varnish. However no significant differences were observed among the groups except for occlusal margins after 24 hours and 5 months.

One of the most common complications of trauma to maxillofacial region is nerve injuries of sensory and motor branches of the nerve V and VII in the face. The aim of this article was to study the relative prevalence of injures of sensory part of nerve V and motor part of nerve VII. The research was descriptive Analytic and information was collected by clinical observation. Samples consisted of 384 individuals refereeing to Alzahra and Kashani hospitals, collected information were described by Descriptive statistics methods and chi statistical test. Motor and sensory nerve involvement in maxillofacial Trauma were evaluated in 384 trauma patients. The most frequent nerve damage was sensory part of the nerve V (51.3%) and the next frequent nerve damage was motor part of the nerve VII. Five patients (1.3%) had both of these two types of injuries. Maxillofacial nerve injuries specially nerves V and VII were the frequent complications of maxillofacial region. Infra-orbital branch of the nerve V and buccal branch of the nerve VII were most affected. Vigilant clinical examination and early diagnosis of the nerve injuries will guide patients towards proper treatment and prevention of complications.

Dental amalgam has been one of the most widely used restorative dental material for over 150 years. Mercury is one of the main elements in dental amalgam composition. Absorption of mercury in human body can cause serious problems such as insomnia, loss of memory, mental depression and inability to concentrate. Widespread use of Dental amalgam in dental schools make a lot of mercury vapour, so, evaluation of blood mercury in dental students during their practical courses may be useful. In this study, two groups of dental students were selected. The first group included 25 clinical dental students and the second 25 preclinical dental students. All selected students were non-smokers, non-alcoholics, and neither group hadnt had new amalgam restoration nor had seafood for at least a week. Blood samples were prepared from each group. In each sample 4 ml of blood was drawn and mixed with 0.5 ml, 1% EDTA as anticoagulant. The concentration of mercury was determined by cold vapor atomic absorption spectrometry with amalgamation. The results showed significant differences between total mercury and nonorganic mercury in two mentioned groups but organic mercury had no significant difference. However means were less than 4ng/ml. According to the result of this study working with amalgam in dental school and operative department can increases blood mercury however no toxicity and serious problem for dental students could be observed. Therefore, it seems making a good air conditioned environment for exiting mercury vapor is necessary, especially in operative department. In addition special attention to control of blood mercury is necessary for assistants, staff and professors of dental school because of their permanent presence in environment containing mercury vapour.

Hepatitis B Virus is the most important factor of liver disease in the entire world. And due to unknown infected people carrying hepatitis B virus, Physicians and dentists face the danger of becoming infected. Therefore they should be aware of signs and symptoms of the disease and at the lime of examination or treatment procedure essential precautions must be taken. The best way of immunity is vaccination at the interval of (0-1-6) months. Even after vaccination in some of the individuals HBs-Ab doesnt form. The aim of this study was to evaluate the presence of HBs-Ab in the blood of the dental students admitted in 1997, after receiving 3 doses of vaccination and reasons for declining concentration or not forming HBS-Ab at all after three doses of vaccination. Five cc of blood per students was taken and sent to the laboratory and after serum separation and keeping it at temperature -80ºC: ELIZA test, with the help of special kits (Biokit) was used to calculate Ab titer and other information such as: Age, sex, weight, time of vaccination and type of vaccination history of any systemic disease and hepatitis at the time of blood taking was also collected. Results of this study showed the average antibody titre is 279. 25±205. 62 and the maximum amount are 565. 50 mIu/ml and minimum is 19.70 mIu/m/. And also the amount of antibody titer is inversely proportional to age and weight but had no relationship with sex and time of vaccination. And due to the same type of vaccination and not having any systemic disease or hepatitis these factors had not any effect in our study. Considering that 10 mIu/ml of antibody or more can induce the complete immunization against the disease and the students had high antibody titer, we conclude vaccination would be very effective.

It is Important to make occlusal plane in complete dentures as closely as possible to occlusal plane in natural dentition. In this study it was tried to show the relationship between the occlusal plane in natural dentition to point's Porion-Nasion PN ANS+Frankfort plane and compare occlusal plane in denture teeth to the same points (Porion/Nasion/PN.ANS+Frakfort plane). Methods and Materials: 35 edentulous patients with class I occlusion: 21 male and 14 female, were randomly selected from Isfahan Dental School, department of prosthetic. Complete upper & lower denture was constructed for these patients following standard procedure. After completion of upper & lower prosthesis occlusal plane was marked and lateral cephalometric radiographs was made for them. At the same time 35 adult patients with normal class I occlusion with no history of orthodontic treatment were selected and leteral cephalometric radiographs were done for them. The angle between occlusal plane, frankfort plane and PN. ANS was measured for all seventy patients on radiographs. The results were compared to each other. In this study it was determined that there is an inverse linear relationship between the angle PN.ANS & occlusal plane, Frankfort plane. In patients with natural dentition coefficient of Correlation was 0.989. This relation did not exist in edentulous patients. Coefficient Correlation between two angles was 0.45. Since the only variable between edentulous and edentulous state is occlusal plane, we can conclude that the routine procedure for determining occlusal plane, for all the patients, does not restore the natural state.

Geographic tongue lesion or benign migratory glossitis is a lesion with prervalence of 1-3% that involves all age and sex groups. Etiology of this lesion is unknown, but some references have pointed out to relationship of stress and this lesion. The aim of this study is to introduce stress as one of the factors in geographic tongue incidence. This research was of a case-control type and our sample in case group included 30 patients afflicted with geographic tongue lesion which visited Isfahan Dental School department of oral medicine. These patients were randomly selected from men and women. Patients were explained about importance of this disease and diagnosis of it. Standard stress meter questionnaire of Klementz and Roberts was completed by Patients and witness group and information was analyzed statistically by T-test. Witness groups were selected from fellows or family members of patients because of similarities in circumstances between two groups. Information gathered from questionnaire showed that average stress number in case group was 386 and in witness group 3032. T-test showed significant difference between stressnumber of two groups. Average age in case group was 32 years and witness group 42 years, and this difference was significant, but geographic tongue didnt have significant correlation with sex, educational degree, income, number of children, time spent on studying and place of residence. Nowadays, psychosomatic diseases are very important. Based on the results of this research, it seems that stress is a significant factor in causing geographic tongue. Although, stress is not the only etiologic factor in causing geographic tongue, but its role as psychologic factor cannot be denied.

Dental plaque is the main cause of periodontal disease. Prevention and treatment of periodontal disease is provided by inhibition of plaque formation or its removal. Uses of mouthwashes are one of the methods for plaque control. The purpose of this study was to determine the most efficient mouthwash in prevention of plaque formation. This experimental study consisted of 48 microbial cultures. Antibacterial effect of three well known mouthwashes: povidine iodine 1 %, chlorhexidine 0.2% and cetyl pyridinium chloride 2.5% were studied on two bacterial species: streptococcus mutans and bacterial melaninogenicus, which were obtained from dental plaque of three different patients. This mentioned bacteria were added to culture mediums until the turbidity equivalent of number 0.5 mcfarland tube was achieved. Then mouthwashes were added to the cultures which were then placed in 37ºC incubator in two different conditions, aerobic and anaerobic. The turbidity's of the aerobic and anaerobic cultures were compared with standard mcfarland tubes after 24 and 72 hours respectively. Data analysis was done with ANOVA, kroscal valis and T-test. The mean number of streptococcus mutans in one millilitre of the culture medium, with mouthwashes including povidine iodine 1%, chlorhexidine 0.2% and cetyl pyridinium chloride 0.5% added was determined: 19.5 × 108, 0.19×108 and 0. 75 × 108 respectively and for bacteroides melaninogenicus: 12.75 ×108, 0, 0.56×108 was achieved respectively. Total average of bacterial number in one millilitre of culture, when mouthwashes were added was determined: 16.1×108, 0,0.9×108 and 0. 65×108 respectively. Result of this study showed that for each type of species and also in general, antibacte¬rial effect of three applied mouthwashes in descending order was: chlorhexidine 0.2%, cetyl pyrid¬inium chloride 2.5% and povidine iodine 1 %. In other word chlorhexidine can be suggested as elective mouthwash. Finally longitudinal study, in vivo-in vitro, with application of more mouthwashes and bacterial species is suggested.

Wearing of acrylic denture teeth creates many problems for patients as well as dentists. Nowadays, artificial teeth are produced by different Iranian companies which compare to their foreign counterparts are more suitable economically. The aim of this study was to compare the amount of wear between Iranian resin teeth and Ivoclar teeth. In this study wear of three types of Iranian resin teeth (Berelian. Marjan, Super newclar) were compared with Ivoclar teeth. Four denture teeth samples were used for each denture teeth. All tests were done in presence of saliva and by using porcelain abrader. The thickness reduction of each sample was measured after 5000 and 10000 cycles with the help of a micrometer. The mean values were compared with ANOVA and T-student test. After 5000 and 10000 cycles there was no significant difference between the mean wear of Berelian teeth and Ivoclar teeth, but after 10000 cycles the mean wear of Ivoclar teeth was decreased and the mean wear of Berelian teeth was increased although this wear was not statistically significant. Comparison of three Iranian resin denture teeth indicated that Berelian teeth showed the least and Super newclar teeth show the maximum amount of wear. The amount of wear in Berelian was almost close to Ivoclar teeth. Therefore we can be hopeful that Iranian companies with improving their production techniques such as mixing the materials, temperature and duration of curing and packing of materials in vacuum can make high wear resistance acrylic teeth.

When an amalgam restoration fails, the repair of existing amalgam restoration with fresh amalgam can be a practical alternative to the replacement of entire restoration. In most studies the bond strength of fresh amalgam to old amalgam is reported lower than the old amalgam itself. Therefore, the purpose of this study was to compare the effect of using adhesive system with surface irregularities and roughness on shear bond strength between fresh and set (old) amalgam. Methods and Materials: Fifty acrylic cylinders were made and a cavity preparation (6mm diameter by 2 mm high) was made in each cylinder. Forty cavities were filled with amalgam, level with cylinders surface and ten cylinders (control group=Groupl) were filled 5mm higher than the surface of cylinder using split die. After aging of all samples in water at 37º c for 14 days, the first 40 samples were divided into 4 groups and were repaired with fresh amalgam in the following manner. Group 2: with surface irregularities and roughness, group 3: using Panavia F, without surface irregularities and roughness, Group4: using cement and surface irregularities and roughness, group 5: without cement and without surface irregularities and roughness. After storage in water at 37ºc for 7 days, the shear bond strengths of groups were tested. Mean shear bond strengths and standard deviations (MPa) for groups were: in Group 1 (control): 36±4.8, Group 2: 31.26±2.70, Group 3: 8.07±1.34, Group 4: 13.05±183 and in Group 5 no bond was seen. ANOVA revealed statistically significant difference among groups Duncan test indicated that there was a significant difference between each group with the other one. Results of this study didnt reveal any advantages for using Panavia F to increase the bond strength. According to the results obtained from making surface roughness and irregularities compared to the control group, this procedure can be suggested for repairing broken amalgam as an acceptable procedure.

The application of die- spacer to crown preparation dies prior to the fabrication of cast crowns is an acceptable procedure that improves the fit of the restorations. Previous studies have shown that the retention of the restoration will be improved, unchanged or reduced when an appropriate thickness of die- spacer is used. But in our country shellac is used instead of die¬-spacer. No study has compared the effect of using standard die-spacer & shellac on the retention of fixed prosthesis. This study compares the effect of using these two materials on the retention of fixed prosthesis. Ninety eight cast copings were fabricated on dies coated with die-spacer and shellac, cemented on the dies and removed using an Instron Universal Testing Machine. T-test showed that there is statistically significant difference between the mean force required to remove crowns relieved with die- spacer and relieved with shellac. With regard to some practical difficulties in application of shellac and the results of this study; it appears that application of die-spacer is better than shellac.

The goal of operative dentistry is to prevent pathological lesions, restoration of anatomy and to enhance proper functional ability of occlusion and aesthetic. Restoration of teeth may lead to fracture microleakage and overhangs. One of the most restorative defects is amalgam overhang that causes food impaction, caries, gingival recession, bone loss, unpleasant feeling of foreign body and tendency to use toothpick. The purpose of this study was to determine the incidence of overhang in class II amalgam restorations performed in the Department of Operative Dentistry, Isfahan University of Medical Sciences and comparing the results of this study with the results of similar studies. The results of this study may help decrease the incidence of amalgam overhangs. In this study, incidence of class II amalgam overhang restorations that were done in Isfahan University, school of dentistry, during second semester of 79-80 and first semester of 80-81 was investigated. This investigation consisted of clinical and radiographic examination. 396 patients were selected consecutively among patients visiting to operative department. Clinical examination was done with an explorer, mirror and dental floss. Radiographic examination consisted of bitewings. Total incidence of amalgam overhangs was 11.6% of which 69.56% related to upper jaw and 30.43% related to lower jaw. Incidence of amalgam overhang was 30% and 70%. Relative frequency of amalgam overhangs in upper jaw was almost twice as much as lower jaw. Also, amalgam overhangs increased from anterior to posterior part in both jaws. In this study the incidence of amalgam overhangs were less than similar studies done before, this might be due to more skilful dentists that had done class II amalgam restorations for patient in this study. Therefore it is suggested to do clinical as well as radiographic examination for diagnosis of amalgam overhangs.

The purpose of this study was to compare the size of periapical lesions by using radiovisiography and conventional radiography (parallel technique). Methods and Materials: Twenty cavities were prepared in periapical zone of two mandible. The diameter of lesions were between 1.5 mm to 3.5 mm. Radiographic and digital images were provided for each lesion by two techniques of digital and conventional radiography (paralleling technique). Results were analyzed by paired T-test. There was a statistically significant difference between radiovisiography and conventional technique in diagnosis of size of periapical lesions. Analysis of data showed significant differences between two methods. Radiovisiogeraphy was better than conventional radiography for measuring periapical lesion.

Since hygiene instructors can play important role in promoting and following oral hygiene instructions in schools, it was decided to investigate hygiene instructors’ knowledge and their attitudes about oral hygiene. This was qualitative-descriptive cross sectional study. Information was gathered by questionnaire containing 25 questions about knowledge and 8 questions about attitudes. 188 hygiene instructors were selected randomly among 278 hygiene instructors present in primary schools in Isfahan. After questionnaires were approved by specialists, they were completed by hygiene instructors. The data were analyzed by SPSS software program and statistical analysis was carried out with analysis of Variance, T-test, ANOVA and Spearman correlation. The average of personals’' knowledge was 18.53± 2. 78 and domain was 11 to 24 (Total mark: 25). The average of their attitude was 25. 7± 2. 7 (Total mark: 32). The T-test didnt show any relationship between altitude, knowledge and educational degree (i. c. Diploma VS bachelor degree). There was no relationship between work experience and educational degree work experience and attitude, knowledge and attitudes. The average of personals’' knowledge showed satisfactory results and positive attitude. Periodic instructions and supervising hygiene instructions in school can improve student's oral hygiene in school and this in turn can create healthier students overall.