Journal of Dental School
Volume:24 Issue: 2, 2006

Free radicals are cytotoxic and can act as inflammatory mediators it seemed useful to investigate whether ploymethyl methacrylate used in complete dentures induces the release of free radicals. The aim of the present study was to compare the free radical concentration in saliva before and after use of acrylic denture. Methods & Subjects: In this experimental study 50 healthy human subjects who were wearing recently made heat polmerized ploymethyl methacrylate dentures were selected and saliva samples were taken before and after use of dentures. Free radicals concentration was measured by spectrophotometry method. Data were analyzed by student t-test. Results showed that the mean concentration of free radical in the after time of delivery of prosthesis (1.150.18 ngr/l) significantly increased when compared with start time (0.60.13 ngr/l). Mean concentration of free radical in the after time of delivery of prosthesis was increased (1 day, 1 week, 1 month after delivery of prosthesis). The increase was significant (P<0.05). Free radicals were produced in saliva after use of acrylic dentures.

Missing teeth lead to functional, esthetical and occlusal problems. The aim of the present study was to evaluate the incidence of missing teeth (except third molar) clinically in female students of Rasht high schools in year 1999 - 2000. Methods & Subjects: In this epidemiological cross – sectional study 600 female students were examined to find missing, impacted or extracted teeth. The data was collected by means of clinical examination without radiography. The history of syndromes, cleft lip or palate, trauma, extraction, midline deviation, space excess or space deficiency, tooth size or tooth form problems and enamel hypoplasia were evaluated. Additional evaluations on type of jaw, kind of missing (unilateral or bilateral), side of missing and number of missings were performed in this study. SPSS software was used for data analysis, using Phi-cramer’s test for qualitative variables. Six hundred students of 10 high schools in Rasht were examined. The incidence of missing was 16.8% 8.8% was because of extraction and 8% due to impaction or missing. The most incidence of missing was found in the age of 16 and the least was in the age of 18. The most common missing teeth were second premolars and the least were second molars. Early diagnosis of missing teeth can lead to better prognosis and treatment. Another investigation is recommend on men students to compare the findings by gender.Keywords:

The aim of this study was to determine the length of time needed for two microorganisms to penetrate through two commonly used temporary restorative materials and through the entire root canal system obturated with the lateral condensation technique after preparation of post space. Methods & Materials: Sixty two extracted single rooted premolars and canines were used in the experimental group, divided into four groups. In group 1 and 2 the length of access cavities of 30 teeth were 1mm. Fifteen teeth in group 1 were temporarily restored with Cavisol and in group 2 were filled with Coltosol. In groups 3 and 4 the length of access cavities of 30 teeth were 3mm. Fifteen teeth in group 3 were temporarily restored with Cavisol and in group 4 were filled with Coltosol. All 60 teeth were mounted individually, where the crowns were placed in contact with BHI broth containing Enterococcus Faecalis and Candida Albicans, in the upper chamber. The lower chambers were filled with sterile BHI broth. Two teeth, one of them with amalgam restoration and the other one without any temporary restorative materials and any microorganisms used in the negative control groups. The data were analyzed by Chi – square test. Broth in the lower chamber of negative control group remained clear throughout the entire experiment period. In the experimental groups the average time for broth contamination was during the third week. There was no significantly difference between 4 experimental groups. The results obtained in this study demonstrate that: Coltosol and Cavisol could not prevent leakage of microorganisms from obturated canals after preparation of post space, 32 cases in experimental groups were leaked with Enterococcus Faecalis and 28 cases were leaked with Candida Albicans, in groups with 1mm thickness of dressing first leakage occurred after 5 days and in groups with 3mm thickness it occurred after 12 days. If it is possible, it is better to use 3mm thickness of dressing. Temporary restoration must be replaced with a permanent restoration before the end of second week. Keywords:

Very often apparently similar nickel-titanium wires behave differently and this makes the selection of clinically proper wire very difficult. The aim of this study was to compare load-defection characteristics of some super elastic nickel-titanium wires available in Iran's commercial field. We hoped the results would be helpful for clinicians in selecting the proper wire to be used in different situations. Methods & Materials: This study was a descriptive and cross-sectional one. 10 types of super elastic nickel-titanium wires (5 of each) with 0/016 inch diameter were tested by three-bracket bending test at 27ºc temperature. Hounsfield (H10KS) machine was used to deflect the wires. The cross-head speed was 0/5mm/min and force level was recorded in 0/25 mm intervals from passive to 3 mm deflection and then in unloading condition from 3 mm to the point that no force was detected (permanent set). Analysis of variance was used. Tukey analysis was done for comparison of each wire with other 9 wires. Although recorded curves were generally similar to typical curves of super elastic wires but their slopes were different. The recorded force levels in 1-1.5-2-2.5 mm deflection in the unloading curve showed statistically significant difference in force levels (P-value<0.001). Analysis of variance showed significant difference in force decay from 2/5 to 1mm deflection as well (P-value < 0.001). According to the findings the wires were divided into three groups of force level: light (Rematitan, Elastinol, Nitinol Sel, Global), medium (Chinese NiTi, Flex Medics, Force II, Nitanium) and heavy (Force I, Reflex TP). Moreover, it was found out that even the wires made by one factory were not the same. Among the tested wires the TP wires had minimum and the Global ones had maximum similarity to each other. This study showed that only the word “superelastic” on the packages of nickel-titanium wires is not enough for using them for treating all kinds of crowdings. Attention should be paid to the results of the independent researches as well.

The goal of many researchers conducted nowadays is to achieve adhesive materials that exhibit good bonding capability, simplified application and easy handling. In this regard, self – etching primer systems were introduced to the market. The aim of this study was to evaluate the micro – shear bond strength of two new self – etching materials compared to an already established bonding materials. Methods & Materials: Sections of human third molars (1.5 mm) were used in this study. The tooth surfaces were polished with 600 grit SiC paper nder running water and randomly divided into three groups. In group I Clearfil Protect Bond (Kuraray Japan), in group II, Clearfil SE Bond (Kurary Japan) as control group, and in group III, Clearfil Tri – S Bond (KUrary Japan) were used due to manufacturer's instruction. Hollow tygon tubes (0.7×0.5mm) were placed on the enamel and dentin surfaces and Clearfil AP-X composite was inserted into the tubes. After 40 seconds light curing, the tygon tubes were removed and samples were stored in distilled water for 24 hours. Micro – shear bond strength was measured (EZ-test, Shimadzu Co., Kyoto, Japan) and the data was statistically analysis by one – way ANOVA and multiple comparison with LSD. Mean bond strength in enamel was 35.76±6.89 mpa in group I 33.62±5.59 mpa in group II, and 34.65±5.65 mpa in group III. Their difference was not statically significant. Mean bond strength in dentin was 34.47±6.0 mpa in group I, 45.20±10.3 mpa in group II, and 35.99±6.13 mpa in group III. The bond strength in group II was higher than group I and II (P<0.05), and the difference between group I and II was not statistically significant. After 24 hours, the shear bond strength of two new adhesive systems to enamel was similar to SE Bond, however, SE Bond exhibited a higher bond strength to dentine.

Surgery for mandibular prognathism produces changes in the skeletal and soft tissue components of the orofacial complex. In particular, studies have shown changes in positions of the tongue and the hyoid bone and consequent narrowing of the pharyngeal airway space. This study evaluated the change in the pharyngeal airway space associated with surgical mandibular set back. Methods & Materials: Lateral cephalograms of 25 adult patients taken preoperatively and 3 months after mandibular setback surgery were traced, and the width of pharyngeal airway space and pharyngeal airway space area were calculated and compared by Paired T – test. The mean amount of mandibular Set back was 6.8±2 mm. There was not significant change in width of nasopharyngeal airway. Mean reduction in distance from uvula to the posterior pharyngeal wall was 1.4±0.7 mm, mean reduction in distance from vallecula to the posterior pharyngeal wall was 2± 0.7 mm, mean reduction in the distance from the tongue base to the posterior pharyngeal wall was 2.5± 0.8 mm and the mean reduction in pharyngeal airway space area was 1.5±0.5 cm2. The hyoid bone moved in an superoposterior direction. Mandibular set back surgery caused decrease in pharyngeal airway dimension. In the patients, who have other risk factors, for example, over weight, short necks, or large tongues, a mandibular set back procedure could possibly predispose the development of sleep apnea syndrome.

The factors such as adhesive compositions and light curing cement could be affected on shear bond strength between enamel and brackets and could increase orthodontic techniques, so that, the aim of this study was to evaluate the shear bond strength of orthodontic brackets using different light curing cements. Methods & Materials: Thirty human extracted intact permanent premolars were used in this study. After cleaning with ultrasnic scaler, teeth were disinfected with 1% hypoclorite for ten minutes and stored in tab water at room temperature and were divided into three groups, and the roots were mounted in acrylic resin. Brackets was bonded on buccal surface of teeth with composite resin according to their manufacturer's instructions. The specimens were thermocycled (5Cº to 55Cº for 500 cycles), shear bond strength was determined using universal testing machine at a cross head speed of 1mm/min. The data was analysed by SPSS software, ANOVA and LSD tests. The mean value of shear bond strength for Ideal makoo, 3M and Heliomolar was 19.52±4.36 Mpa, 19.84±5.19 Mpa and 17.04±3.53 Mpa respectively. There was not a statistically significant difference in shear bond strength between the three light curing cements, therefore Ideal Makoo cement is recommended for orthodontic bonding groups.

Tuberculosis is the first disease introduced as an “emergency” by WHO, 1993. Dental-care workers encounter the diseases potentially every time in their works and a proper awareness may lead to cease transmission of the disease and improve dental management. The aim of this study was to evaluate the knowledge of general dental practitioners (GDP) who in private offices in the Great Tehran 2006 about tuberculosis. Methods & Materials: 420 GPDS (193 male, 227 female) were selected by a random cluster sampling method and evaluated using a questionnaire. This questionnaire consisted of 18 questions with 3 choices and another choice as “I don’t know”. Three groups of questions, each one with 6 questions, were used: general aspect of tuberculosis (diagnosis, pathology, transmission, oral manifestation, and screening) medical therapy and finally drug interaction and dental management. Content validity was confirmed by several specialists in oral medicine and one general practitioner. The mean correct answers were 2.0±1.0, 1.6±1.1 and 2.1±1.2 with respect to general aspects, medical therapy and drug interactions, and dental management. Total score was 5.7±2.5 (95% CI: 5.4 to 5.9, ranged from 0 to 11) of maximum 18. Individuals who had graduated from Azad Universities and governmental dental schools in Tehran, respectively, had more knowledge. Knowledge of our study population about tuberculosis is clearly low. It seems that non - traditional educational methods may be helpful.

Since dental plaque is known as an essential cause of periodontitis, adjunctive use of both mechanical and chemical methods is advised for plaque control. Several invitro investigations have shown that tetracycline hydrocloride is highly effective against the major suspected periodontal pathogens of periodontitis. This study was therefore, carried out to compare clinical effects of scaling and root planning alone and with application of local oxytetracycline irrigation on Early periodontitis. Methods & Materials: Fourteen patients from the staff dental school of Shaheed Beheshti Medical Sciences University, age 23-41 years, volunteered for a split–mouth randomized clinical trial. After oral hygiene instructions, tooth with early periodontitis in each quadrant was selected. Clinical changes were monitored for selected teeth at baseline including PI, GI, PBI, PD. Full mouth scaling and root planning were performed and two selected were served as control (SC/RP) and the others as experimental group which were irrigated with 5 mg/ml oxytetracycline solution. Irrigation was performed every 48 hours during the first two weeks of the study. The side of the irrigation was changed alternatively (right or left). After 2 and 4 weeks all indices were measured too. The paired t and wilcoxon signed ranks tests were used to test the differences. The differences between indices PI and PD at the baseline and after 4 weeks were: (GI), 1.59-0.84, (PD), 3.24-2.83. The two groups showed statistical differences comparing with the base line in all indices, but there isn’t any significant difference between them. Considering the consequent results, antibiotics dont have noticeable effects in the process of treatment.

Adhesion as an important physical factor in denture retention varies in different base materials. In this research the rate of adhesion is measured in the commonly used denture base materials. Methods & Materials: Twelve kind of different materials used in denture base were considered and 10 specimens of each of them were made. Then, the forces necessary to separate specimens from distilled water are measured by using special measuring devices for determining surface tensions. The results were compared with one way analysis of variance and paired t – test. Red autopolymerized Meliodent Acrylic resin showed the maximum (987.5±29.3 mg) and silicon Molloplast B showed the minimum rate of adhesion (885.5±44.7 mg). Also, the rate of adhesion of heat cure Meliodent acrylic (965.3±17.6 mg) was more than Acropars acrylic (945±35.4 mg) and variation was statistically significant (P<0.05). Polishing the acrylic caused increase in the rate of adhesion which was statistically significant (P<0.0001). Physical retention due to the adhesion of acrylic resin is expected more than of silicone and to obtain the better retention, it is recommended to polish the impression surface of complete denture.

The purpose of this in vitro study was to compare microleakage of three bonding systems in one week and ten months. Methods & Materials: The study was conducted experimentally through observation technique. Two V shape cavities, with gingival margin in cementum were prepared on the buccal and lingual surfaces of 45 freshly extracted premolar teeth. The teeth were randomly divided into three groups and restored with Tetric Ceram composite, utilizing the following bonding systems: Single bond, Excite, and PQ1. One third of the specimens in each group were stored in distilled water for one week and the remaining was stored for ten months. All specimens were thermocycled (1000 times) and subjected to dye penetration testing. The results were analyzed by Mann – whitney and Kruskal – Wallis tests. Enamel leakage of Single bond did not differed through two periods while its gingival leakage in one week was less than ten months. But, no difference was noticed in enamel and cervical leakage of Excite and PQ1 samples in one week and ten months periods. Enamel leakage was significantly lower than gingival leakage. There was no significant difference between materials and water storage had detrimental effect on sealing ability.:

Plasters have vast applications in dentistry and are one of the most consumed materials in this field. Nowadays plasters are produced by several Iranian Company and the foreign ones are expensive and unavailable. According to the numerous usages of plasters in dentistry and inadequate study about Iranian plasters, the purpose of this study was to evaluate physical properties of the Khodabandeloo plaster. Methods & Materials: In this laboratory experimental study, five properties which have been necessitated by ADA specification n 25 and Iranian standard n 2792 were evaluated. The number of samples was 20 per every test. All measuring tests were performed according to ADA specification n 25 and 2792 Iran Standard. T - Student and chi square tests were applied to the results to determine a significant difference between the various means. Arrival information’s show that the appropriate consistency of this plaster was obtained by 58ml water and 100gr powder. The mean setting time, setting expansion and compressive strength for Khodabandehloo plaster were in the range of 13.8±1.005 min, %0.219±0.05, 5.75±0.63 MPa respectively. In the reproduction of details test, 75 percent of specimens had completely reproduced the groove. The consistency, setting time, setting expansion and reproduction of details for Khodabandeloo plaster are in the standard limits, but the compressive strength of this plaster was not in standard limits and performs must be reform for this defaults.

Using of fluoride and fissure sealant in preventive of caries has specific condition, since the research on in vitro shows that dental material such as fissure sealant would effect physical and chemical against on fluoride gel. The aim of this research was to compare the effect of fluoride APF gels (Sultan) on microhardness of two types of fissure sealants Helioseal (with filler) and Clinpro (fillerless). Methods & Materials: This research was carried out on the basis of both experimental and in vitro has case and control groups. Thirty two cylindrical (dimension 2×6mm) specimens were made using equal number of each fissure sealant (Helioseal & Clinpro) which were randomly divided in to 4 equal groups. After storing the first two groups in distilled water for forty eight hours, they were exposed to APF Gels for 4 minutes and then were stored for half an hour in synthetic saliva. Then the excess gels were removed and the samples stored again in synthetic saliva for thirty minutes prior to immersion into distilled water for another thirty minutes after an intermediate penoid gap. The above procedures once again were repeated. This method is similar to routine fluoride therapy in clinic (twice per year). The other two groups were used as control for Helioseal and Clinpro respectively while they were stored in distilled water. Vickers microhardness test values were obtained. The data were subjected to ANOVA and T test analysis. The data indicated that application of APF gel had only a significant effect on microhardness of Clinpro (P<0.05). But in the case of Helioseal it was not so significant. The results obtained indicate a higher resistance by Helioseal in comparison to Clinpro against APF gel.

Marginal restorations are appropriate places for plaque accumulation and bacteria reproduction causing periodontal diseases or tooth loss sometimes. With the importance of tooth maintenance as teeth restorations are daily dental services, the present study was conducted to compare the periodontal status in patients with correct marginal restorations and their controls referred to department of Oral Medicine and Operative Dentistry of Isfahan Dental School. Methods & Materials: Ninety six patients with one or more marginal restorations as well as their controls were studied in a case – control method. Bleeding, gingival and plaque indices were evaluated in both groups for the purpose. Periodontal probes were used for measuring plaque and bleeding index and gingival index was examined by observation. Mann Whitney U test was used for comparing the results in both groups. 46.9 percent of cases had plaque index of 0 as the rate was 55.2 per cent in control samples. Considering gingival index, the percentage of patients with 0 gingival index was 65.6 and 80.2 in case and control groups respectively. Bleeding index of 0 was reported to be 31.3 and 58.3 per cent in case and control groups. Statistical analysis showed significant difference between the two groups considering three measured variables (P<0.05). According to the results of this study, even the correct marginal restorations may have effect on periodontal status.

Gingivitis is the most common form of periodontal disease. And as we know bacterial plaque is the most important factor in causing gingivitis. So we must try to limit the plaque formation as much as we can. For controlling the plaque, as prevention and treatment there are two ways: mechanical and chemical. Using tooth brush, dental floss, tooth pick,. .. are mechanical ways and using toothpaste, jells, antibiotics and antiseptics. .. are chemical ways. Disregarding preventive measures will lead to periodontal diseases, which needs different treatment modalities to eliminate them. There are limited information regarding the behavior of Iranian people for their oral hygiene, and there are no available datas about their oral hygiene measures in the month of Ramadan. The purpose of this study is to find out frequency, timing and type of devices used by our Moslems to clean their mouths in Ramadan month and other months. Methods & Materials: The type of this study is descriptive – analytic. We prepared 880 questionnaires and distributed them between 22 areas of municipality of Tehran. 8 helpers (4 females and 4 males) interviewed 40 people (20 females, 20 males) in each area and wrote these dates in supplied questionnaires. 40 people in each area were located in mosques, parks, and Friday prayer of Tehran. 6.01% of fasting people use toothbrush at noontime in Ramadan month and 21.61% in routine months. 12.6% of people use toothbrush three times a day (morning, noontime and night) in routine months, but only 4.55% in Ramadan month. 43.4% of people use toothbrush 2 times a day in Ramadan month (this percentage for other months is 35.78%). The percentages of females who use tooth brush two times a day and more than that in Ramadan and other months are 10% more than males. And after statistics accounts it was found that these differences are sensible. Also, after statistics accounts it was found that the percentages of educated people (who have diploma and more degree) that use toothbrush 2 times a day and more in Ramadan and other months are sensibly more than others. According to our previous findings after calling using toothbrush 2 times a day and more as "Hygiene Index" we can conclude that educated people more than others like care about their oral hygienes, and females more than males take care about their oral hygienes, too. The decrease of using toothbrush at noontime in Ramadan month relates to people's belief that their fasting will be cancelled, if they use toothbrush in fasting time. It is suggested that people be informed of importance of noon brushing during fasting time through all the means of mass media.

Color research has shown that shade guides do not always represent the color of natural tooth. Moreover, visual evaluation has been found to be unreliable and inconsistent. This study evaluated the effects of 2 shade guides and 2 light sources on the intrarater repeatability of prosthodontists, postgraduate students and laboratory technicians with regard to shade selection. Methods & Materials: Three prosthodontists, three postgraduate students and three laboratory technicians participate in this descriptive – analytic study. Examiners were tested to eliminate color blindness by Eshihara Test. Each clinician used Vita Classic and Vitapan 3 D- master shade guides under two light sources (sun light and corrected Dialite lamp) to determine the shades of the maxillary left canines of 20 patients following a standard protocol. The identification codes of the shade tabs were masked to prevent shade memory. All teeth were polished before each shade selection. Shade selection was randomly repeated 1 month later by the same practitioners on the same group of patients. Data were analyzed with two way analysis of variance (Anova). Significant interactions were found between the effects of shade guide system and specially training on intrarater repeatability (P<0.05). The intrarater repeatability of prosthodontists was significantly higher than that of postgraduate students and laboratory technicians when the Vita Classic shade guide was used (P<0.05). Use of the Vitapan 3 D – master shade guide significantly improved the intrarater repeatability of postgraduate students compared with Vita Classic shade guide (P<0.05). This improvement was not significant, however, among prosthodontists and laboratory technicians (P>0.05). Light sources didnt show any significant effects on intrarater repeatability of examiners. The prosthodontists demonstrated superior intrarater repeatability in shade selection, especially when the Vita Classic shade guide was used. Use of the Vitapan 3 D – master Shade guide notably improved intrarater repeatability among the postgraduate students.

The purpose of this study was to compare two methods of unerupted teeth size determination (Tanaka and Johnstone and Moyers) in patients referred to Shaheed Beheshti University Dental School. Methods & Materials: The study was descriptive and its technique was observation and questionnaire. The study included dental casts of patients referred to orthodontic department of Shahid Beheshti University of Medical Sciences which met the requirements of the study. 117 pairs of models were studied after analyzing existing 1500 pairs. The mesiodistal width of canine, first and second premolar and also four lower incisors were measured by digital caliper with precision of 0.01 mm in both maxilla and mandible. The overall width of teeth was predicted using the formulas and compared with their true size. The statistical analysis included paired t test, student t test and linear regression. The study showed that both methods of Tanaka and Johnstone and Moyers in 50%, 65% and 75% overestimated the true size of canine and premolars in both maxilla and mandible while Moyers method in 25% underestimated their real size in females. At both maxilla and mandible of studied females, significant differences existed between real and predicted sizes. The linear regression showed a formula of "y=0.65x+6.1" and "y=0.62x +7.2" in mandible and maxilla. In males, both methods of Tanaka and Johnstone and Moyers in 65% and 75% overestimated the true size of canine and premolars in both maxilla and mandible while Moyers methods in 25% and 50% underestimated the real sizes. Significant differences existed between real and predicted sizes in all methods with the exception of Moyers in 50%, so that, Moyers method in 50% had been estimated the sizes with high accuracy. The linear regression showed a formula of "y=0.58x+7.98" and "y=0.64x+7.2" in mandible and maxilla respectively. Except for Moyers method at 50% that predicted the size of canine and premolars with higher accuracy in males, the other formulas could not predict the real size of unerupted teeth. As there was no significant differences between true and predicted teeth sizes, the application of the suggested formulas are suggested for Iranian people.

One of the most important aspects in oral and maxillofacial surgery is the healing process after periapical surgery during apicotomy, transplantation or pathological surgeries. Past studies with the vascular supply to surgically mobilized dentoalveolar segments, apicotomized transplanted teeth and root resected teeth in periodontal disease, have mentioned occasional encounters with vital root resection and have noted varying degrees of pulpal response to this insult. The purpose of this investigation was to observe the pulpal and periapical responses of dog dental tissues to intentional apical vital root amputation over six months postoperative period. Methods & Materials: Four adult German – Canadian dogs were used in this experimental study. One root of multirooted teeth in left quadrant of each jaw were surgically transected and mandibular quadrants for 12, 13, 24 and 25 weeks following surgery were obtained after the animals were sacrificed by formalin perfusion of the left and right carotids. The tissue blocks were prepared by routine histological methods. Fisher exact test were used for data analysis. The results demonstrated a disruption of the normal pulpal architecture, with initial pulpal degeneration and subsequent early replacement by the periodontal ligament tissue. An intermediate cemental lining of the root canal occurred in all specimens. There was fat tissue in the apical part of the root in some specimens. Pulpal regeneration were seen in 75% of upper molars and 25% of lower molars. Resorption were took place only in two specimens (12.5%). Severe hyperemia were seen in 62.5% of all specimens. The pulp of multirooted teeth, remain vital after transaction of apical part of the root in dogs.