Journal of Dental School
Year:2002 | Volume:20 | Issue:3|Papers Count:21

Aim: The Purpose of this project was to develop a computerized system to design removable partial dentures.Materials and Methods: In this design, a personal computer (PC) was used with windows 98 / visual basic 6.0 with 60 dialog box, 65 pictures and 1000 icons: Removable partial dentures were designed using this Program. Results: Result ant design and treatment plans of 65,536 removable partial denture cases were analyzed using 65 graphs and pictures achieved from each case.Conclusions: The software package designed in this project could process all parameters required for designing denture for partially edentulous patients.

Back ground & Aim: Preservation of tooth vitality is one of the most important tasks for clinicians dealing with exposed teeth. Several different materials have been used for pulp capping in recent years with calcium hydroxide being of the most Due to pathologic complication in the pulp following the are of Ca(OH)2, this investigation was designed to evaluate the effect of MTA on pulp reaction following pulp capping procedure. Method & Material: Calcium Hydroxide (Dycal) was used for direct pulp cap ping of II human maxillary third molar teeth with intentional exposure as control group. The same number of teeth was capped using MTA using the same condition. Results: Results showed that the dentinal bridge was thicker in cases treated with MTA with a clearly milder inflammation in pulp of the teeth treated by MTA. Conclusion: MTA could be used as an acceptable material for pulp capping of exposed permanent teeth.

Background and Aim: Treatment and follow up of traumatized teeth has ever been the obsession of many dentists throughout the world. The matter sounds more concerning, when the traumatized tooth is a permanent anterior incisor (with esthetic and phonetic functions) and also when the injury has involved the patient at the early years of childhood and adolescence. Materials and Methods: The study has been done in a descriptive, retrospective, analytical and cross-sectional way. Our major media for gathering the data were questionnaires among the community of patients seeking dental service at the endodontic and endodontic departments of the Dental School at Shahid Beheshti University of Medical Sciences, Tehran during the period of March 1998 to. February 1999.  The community was constituted of 65 patients with average age of 20.5 years, having 116 traumatized teeth altogether. Almost all the clinical and radiographic complications of traumatic injuries were assessed. Besides the incidence and prevalence of each type of trauma were discussed. Also the relation between incisal over jet and traumatic injuries was later discussed.Results: The most important results obtained through the study are as follows: Mean number of traumatized teeth per patient: 1.8 teeth. The tooth showing the highest prevalence of traumatic injuries among 12 anterior teeth: Maxillary central incisor (69.8%) The ratio male to female patients: 2.1 to 1.The prevalence of trauma patients with excess over jet: 27.7%. The most frequent etiologic factors of dental traumatic injuries: falls: 46.1%, bicycle accidents: 7.8%, traffic accidents: 9.2%, assaults: 7.8%, sports: 9.2%, foreign body striking teeth: 13.8%, child physical abuse: 1.5%, unknown: 3.1%.  Conclusion: Considering the cinportance of anterior teeth, recognizing the prevalence of traumatic injuries and the method of treatment used by the practitioner have an important role in maintaining these teeth.

Background & Aim: Argyrophilic Nucleolar Organizer Regions (Ag NORs) have been used with varying degrees of success in different areas of pathology, including breast, prostate and salivary glands, in an attempt to differentiate being tumors from malignant cases. Material & Method: Silver nitrate staining was carried out for nucleoli organizer regions in 21 paraffin embedded squamous cell carcinoma. One hundred nuclei were counted for AgNoRs dots. Control group samples were selected from normal margins of the same tumors. Results: The number of dots was 2.33±0.46 in normal epithelial cells, 4.63±0.78 in premalignant lesions and 7.5±1.89 in squamous cell carcinoma. The statistical analysis showed significant differences between different groups (P<0.05).  Conclusion: Ag NOR count is a useful method for distinction of squamous cell carcinoma, precancerous and normal epithelium.

Aim: The purpose of the present study was to compare caries prevalence between secretors and non-secretors of blood group substances (A.B.O). Method & Material: A group of 180 cases who were referred to Iranian blood transfusion central office wereselected and divided in to two groups of secretor and non-secretor according to the presence or absence of bloodgroup antigens in their saliva. Caries rate was recorded on the bases of DMFT index criteria.Results: Results indicated that 136 cases (75.6%) were secretors while 44 cases (24.4%) were non-secretors. There was no significant difference between secretor status and DMFT.Conclusion: There was no significant difference between prevalence of dental caries, secretor status or blood group (ABO) in the population of the study.

Aim: The quantity of root resorption was measured after injections ofPGE2 alone and with calcium gluconate during orthodontic tooth movement.Materials & Method: A group of 24, male Wistar rats, 8 week - old were randomly placed into 3 groups.Orthodontic appliance consisted of a Closed Coil Spring ligated to the first upper right molar and incisor of the same side, applying a 60-gr force. The control group had localized injections of distilled water on the buccal gingiva of the upper right first molar. In the second experimental group, 0.1 ml of Imgr/ml PGE2 was injected at the same place, while the third group received IP injection of 200mg/kg calcium gluconate (10%) beside the PGE2. All injections were performed on day 1 and 7. Animals were sacrificed on the day 21. Palatal halves of both sides in the Control group (right side as control and left side as normal) were removed for histological process with the right palatal halves of the other groups. Root resorption was calculated on the mesial root surface of the right molar by sum of the resorptive surfaces, multiplying the deepest depth and the Largest Length of the resorptive surfaces. The data were analysed by Kruskal- Wallis and Multiple Range tests.Results: There were no statistically significant differences between the 4 groups, except for the normal group and the PGE2 group. PGE2 as a mediator of orthodontic movement, enhanced the root resorption following the remodeling process in respect to the teeth that were not moved orthodontically. Conclusion: The judicious use of local and systemic biochemical agents which alter remodeling of periodontal tissues, in conjunction with orthodontic treatment appears to have less side effects during the treatment. Transient systemic hypoparathy roidism following the calcium content injections seemed to decrease the trend towards root resorption in comparison to PGE2 group.

Aim: This survey was designed to compare the efficiency of preventive methods on gingival bleeding index (GBI) of 12 year old Tehranian pupils. Method and Material: 16 secondary Schools were selected randomly and then divided into four groups:Group I: the control group with no preventive program. Group II: the first trial group (Education G) who were introduced to oral hygiene through audio-visual training. Group III: the 2nd trial group (promotion G) who were persuaded practically. Group IV: the 3rd trail group (Education and promotion G) who were both trained and persuaded practically. GBI index was measured both before and after intervention is completed (one year research period. Results: Results showed that GBI had been increased in 6 sextants from 2.6% to 23.3% of group I. This data was decreased in six sextants from 22.9% to 13.6%of the group II. In group III, GBI was increased in six sextant from 19.4%to 43.9% while a decreased was occurred in six sextant of group IV from 34.2% to 14%. Conclusion: Education and training has an obvious effect on increase of the level of oral hygiene.

Aim: The propose of this study was to calculate the amount of force that the spring deliver after variable degree of activation. Material & Method: A specific designed program in Pascal language was employed to calculate the forcedelivered by each spring considering relevant variables such as cross section wave length and spring design.Results: The amount of force per each degree activation of 3 different springs currently used in removable orthodontic appliances was calculated. Stainless steel, Z spring with round cross section, 0.5 mm diameter and 1.5 turn helix delivered 45,52,59 gr force when activated at 14, 15, 16 degrees respectively.Conclusion: Useful ranges of force delivery can be achieved with 0.4 mm cross section for finger spring and 0.5 and 0.6 mm for Z-spring.

Background: There is not enough research evidence to support specific treatment plan for leukemia patients before and after chemotherapy. One of the complications in leukemic patients is the increased incidence of infection due to reduction of defense mechanism and consumption of immunosuppressive drugs. In addition, the normal flora of these patients changes during chemotherapy. Aim: This research was designed to study the changes of oral flora before and after chemotherapy in leukemic patients. Method & Material: This study was performed on 22 Leukemic patients, of whom 2 died later, leaving 14male and 6 female with the mean age of 8 (5-12 Years). Out of these 20 patients, 12 were suffering from acute lymphocytic leukemia and 8 from acute myelocytic leukemia. The first sample was taken before hospitalization while the second one was one month after the beginning of chemotherapy. Microbial culture was provided followed by colony count for each sample. Results: Results showed a reduction in the number of colonies of streptococcus, Neisseria, Diphtheroids and also an increase in that of staphylococcus, Pseudomonas, Escherichia coli, Klebsiella, Enterobacter and Candida. Conclusion: Variability of micro organisms including gram negatives, introduces the need for provisional dental treatment plans for leukemia patients.

Aim: The aim of this study was to determine the prevalence of leukoplakia in patients over 30 years of age in Tehran during the year 1996. Method and Material: Altogether there were 1508 females (51%) and 1437males (49%) in the samples (2947 individuals). Assessments were carried out on the basis of observation and interviewing individuals techniques. Results: The prevalence of leukoplakia was 0.9% of the total population, 1.5% in males and 0.4% in females. The greatest rate was 1.4% in the age groups 50 to 59 and 70-79 year old cases.The prevalence of leukoplakia was 4.4% and 0.1% in smokers and non-smokers, respectively. Conclusion: The rate of leukolakia was found to be higher in males and smokers compare to females and non smokers.

Background: Numerous clinical and radiographic studies have shown a degree of alveolar bone loss in children and adolescents. Children with incipient periodontal disease could suffer from advanced periodontal disease in adulthood. Aim: The purpose of this study was to investigate normal mean of the alveolar bone height of primary and first permanent molars, in a sample of healthy seven to nine- year old children, in Isfahan. Method & Material: Bitewing radiographs were taken from 93 healthy children aged seven to nine- years. The normal mean value for CEJ- ALC was measured using radiographs. Results: Results showed that the mean CEJ- ALC to be atl.06mm in primary molars andO.26rnmin the permanent first molar area. The mean distance (CEJ- ALC) for the maxillary molars was greater than their mandible counter parts for each primary molar tooth. However, this difference was not statistically significant. The mean distance was significantly greater for teeth with inter proximal caries (P< 0.001). The mean distance (CEJ- ALC) was greater in male than female patients (P<0.001).Conclusion: There was a clear difference between these distances in male compare to female cases with male being greater. This value was higher in carrion teeth too.

Xylitol is a 5-Carbon sugar alcohol, which looks and tastes very much like ordinary sugar. Its oral intake has proved to be safe in long-term human studies. The most important thing from a dental point of view is the fact that in a large number of clinical studies xylitol has been totally non-cryogenic and in some cases it has even enhanced the demineralization of dental caries. In order to get at least 40-50% reduction in caries increment, it seems that the chewing frequency should be at least 3 times a day. Xylitol consumers have less mutants bacteria in dental plaque. Although many tooth pastes also contain xylitol, health recommendations focus on the fluoride content only. Indeed some studies with xylitol dentifrices indicate that they might be caries-preventive.

Background & Aim: Dental plaque is known as the main etiologic factor for periodontal diseases. Plaque control is considered as the most important part of prevention and therefore, before treatment of the diseases. Several mechanical or chemical methods have been used including brushing techniques and mouth rinsing including. Persica mouth rinse which contains extracts of Salvadora Persica, Mint and Yorrow. It is a plant product being in the Iran’s market for the last decade. The aim of this study was to evaluate and compare the effect of two mouth rinses namely: Persica (PI) and chlorhexidine (CHL) on the development of plaque and gingivitis. Method & Material: A group of 26 individuals were entered into a randomized double blind study. Subjects received supra gingival scaling and prophylaxis as the preparatory procedure followed by refraining from all oral hygiene procedures for a week. At the end of the week, Plaque index (PI) was recorded associated with Modified gingival index (MGI). Rinsing was performed two times per day only with the assigned preparation given to each case and data was registered for another week. The same clinical parameters were registered at the end of the treatment course. Results: Statistical analysis showed significant differences in PI and MGI (Pv<0.05) in each group compare to the baseline. Wilcoxon Signed Ranks test didn’t show any significant differences in changes of MFI between the two groups but changes in PI was significantly greater in CHL group (Pv <0.05). Conclusion: Persica was effective in reducing plaque and gingivitis when used as a 2 times daily mouthiest.

Aim: The aim of this study was to evaluate the repair bond strength of modified composite resin (Compoglass F) with similar and dissimilar materials (Compoglass F and Fuji II LC). Method & Material: Surface treatments were performed by the application of polyacrylic acid 25% in one group and hydrofloric acid (25%) in the other group. Each group was divided into two subgroups for their adhesive potential test. Thermal cycling was performed using 600 cycles before restoration procedure. First, the surface was roughened using a diamond bur. After a surface treatment course using HF or PA, restoration was carried out using Compoglass F and/or Fuji II LC with and without EBA. Samples were subjected to a blade (cross head with the speed of 0.5 mm/min) after a second 600 thermal cycling. Collected data was analysed using 3 way ANOVA test in addition to a Duncan test. Results: Results revealed that the type of acid and enamel bonding agent significantly increased the repair bond strength. Mean repair bond strength with HF was more than with PA. Bond strength was more when EBA was need compare to its absence. Conclusion: It is concluded that application of acid hydrofluoric followed by the use of adentive bonding agent could improve the bond strength of repaired restorations.

Most often analysis of the data depends on the study design in different kinds of studies. In control studies what we are to express be rates of incidence and prevalence in the exposed and unexposed groups. We can also calculate relative risk and risk difference. In case-control studies however, the cross products ratio gives the odds ratio, while in surveys the prevalence is measured and prevalence ratios with the differences are calculated.

Background and Aim: Candidiasis is one of the most common infections of the oral carith in denture wearers. Studies of Relation between various diseases and ABO blood groups have shown elevated relative risks. This study was designed to determine the interrelation between ABO blood types and candidiasis. Method and Material: A group of 150 denture wearers (756 with candidiasis, 75 without candidiasis) studied using simplified culture method and direct microscopic slide examination to detect candidiasis, blood group types. Agglutination method was also employed using monoclonal antibodies detection on saliva. This was determine the secretors and non secretors of blood types. Results:  Results suggest that denture wearers in blood group O are more susceptible to canidiasis compared to the other types. This condition is reverse in denture wearers with type B blood group. The percentage of the blood group secretors with canidiasis was much higher than non secretors. Conclusion: ABO blood group could be one of the etiologic factors for candidiasis in denture wearers with blood group O being more susceptible.

Back ground &Aim: Physical anthropometric evaluations have revealed variations in craniofacial dimensions both in different sex and among human races. This study was conducted to establish cephalometric norms of9 to 11 year old Iranian children and cross sectional effect of age and sex on them. Material and Methods: A group of 3500 pupils aged 9-11 years were examined in the city of Qazvin from whom only 90 cases were selected with normal occlusion 30 students of each age. A conventional lateral cephalogram was taken from each of the students with written concent A combination cephalometric analysis was conducted including 22 angular measurements, 10 linear measurements and one ratio. Mean and SD were calculated in addition to variation coefficient and the range of each measurements. Results: Cephalometric analysis norms were calculated for 90 children 45 girls and 45 boys. The mean was 80.54±3.8 for SNA, 76.81±2.61 for SNB and 3.74±1.84 for ANB in the whole sample. In evaluation of sex effect, significant variations were seen in most of the linear measurements, with the most significant one being in the length of maxilla (P=0). In all dimensions the boys faces were longer than that of girls. Conclusion: Significant variations were seen in anteroposterior linear measurements of 9 to 11 year olds.