Journal of Dental School
Year:2005 | Volume:22 | Issue:4|Papers Count:24

Purpose: To evaluate the prevalence of tooth- size discrepancies among orthodontic patients with sagittal malocclusions by performing Bolton analysis.Methods & Materials: Two hundred pairs of study models of skeletal Cl I, II, III and crowding were selected. All permanent teeth were present except second and third molars, without any attrition, caries or restorations on their interproximal surfaces. The greatest mesiodistal diameter was measured to the nearest 0.01 mm by means of digimatic calipers. The Bolton's anterior and overall ratios were perfomed on these models to find tooth-size discrepancies. The mean, SD, range, CV and SE were assessed. The four groups were compared by variance analysis. The amount of obtained ratios were compared with Bolton's ratios by T -test, and the difference over 2SD was considered significant.Results: The tooth size discrepancy was more prevalent in crowding group (%14) regarding the overall ratio, and more in cl III group (%28) regarding anterior ratio. The means of Anterior and Overall ratios in the present study (78.21±2.69, 92.01±92.01±2.45) were larger than Bolton's measurements (77.2±1.65, 91.3±1.91) (P<0.0001). Even though the means of the tooth size ratios of the current study were significantly different from Bolton's results, the amount of differences were not more than 1.5mm, hence we can apply the Bolton's ratios for Iranian people. When the Bolton's results were applied to our study, for the Anterior ratio 23% and for the Overall ratio 9% of patients fell outside of 2SD and tooth-size discrepancies.Conclusion: Regarding tooth- size discrepancies specially in crowding and crossbite cases, which are not detectable by inspection alone, it is suggested that Bolton's tooth size analysis be performed before starting the orthodontic treatment. 

Purpose: Adhesion to dentin is the major problem in using tooth color composite resins. The way proposed is the use of hydrophile resins, of which, HEMA is the most important one. Because of the importance of the subject, this study was conducted to evaluate the effect of HEMA on shear bond strength of enamel bonding agent to dentinafter I year water storage.Methods & Materials: This invitro study carried out experimentally on 36 extracted premolar teeth. The teeth randomly assigned to 4 groups, each group containing 6 samples. In group 1, the solution of %35 HEMA and Acetone and in group 2, the solution of %35 HEMA and Water was used. Multipurpose Scotchbond primer was used in group 4. In group 1 and 2, enamel bonding and in group 4 the adhesive was used. In group 3, teeth were dried and enamel bonded after etching. Composite cylinders were bonded on the areas with the same dimensions.The prepared samples were thermocycled 1000 times at 55°C and 5°C after keeping in distilled water for 1 year. Shear bond strength of the samples were tested by Instron machine.Results: Results showed that the "HEMA and Acetone" group had the highest strength (25.12±3.52), and then, "Scotchbond" group (23.55±1.6)."HEMA and Water" group (14.3±5.6) and "enamel bonding" group (4.25±2.61) had the next ranks respectively. Analysis of variance test showed that the overall difference between them was statistically significant (P<0.0001). Difference in strength of HEMA and Scotchbond was not significant but was significantly different from other groups.Conclusion: Shearbond strength of "HEMA and Acetone" and "HEMA and Scotchbond" became acceptable after thermocycling and storage in distilled water for one year but not in enamel bonding group.

Purpose: Dental abscess is considered as one of the most common complications of untreated caries in children. Microorganisms are known as major causes for the pulp and periradicular pathosis. Black - pigmented, gram-negative anaerobes, belonging to species of porphyromonas and prevotella (bacteroides) play an importantrolein causing clinical signs and symptoms related to pulp and periradicular disease. The aim of this investigation was to assess the presence of two main pathogenic microorganisms named porphyromonas gingival is and prevotella melaninogenica in abscessed primary teeth.Methods & Materials: Forty children aged 4-10 years were selected with no systemic disease and no antibiotic consumption during the last two weeks of sampling. Selected teeth were presenting swelling and pain at observation stage as signs of acute abscess. The diagnostic technique of porphyromonas gingivalis and prevotella melaningenica was the use of DNA formulation reading by means of PCR technique.Results: Results showed that of the 40 samples, 35(%87.5) were positive for porphyromonas gingivalis, 34(%85) were positive for prevotella melaninogenica. However, it seems that more work is required for more precise antibiotic therapy of dental abscess in children.Conclusion: The presence of two well known species of microorganisms in periapical abscess of primary teeth was confirmed.

Purpose: Carbon fiber posts are widely used in dentistry. The most problem is their low bond strength with composite resin utilized as core. The aim of this study was to evaluate the effect of different surface treatments on the tensile bond strength of composite resin core to carbon fiber posts.Methods & Materials: Thirty six posts free of defects, were selected and randomly divided into 4 groups and treated as follows:Group 1:No treatment (control).Group 2: Surface treatment with Single BondGroup 3: Surface treatment with Sandblast + Single BondGroup 4: Surface treatment with Sandblast + Silane+ Single Bond.A cylindrical composite resin core (5x5x5 mm) was built around each post using Z100. Post-core assemblies were tested for tensile failure by Instron testing machine at a cross-head speed of 10 mm/min. The bond strength was assessed by Newton (N).Results: The tensile bond strength were respectively, Group 1 262.33±23.37N, Group 2: 522.77±37.33N, Group 3: 613.50±39.93 N, Group 4: 641.00±43.35N. ANOVA and Scheffe test showed that group I was the least retentive group of all (p<0.05), and group 3 and group 4 were significantly more retentive than group 2 (p<0.05).There was no significant difference between group 3 and group 4.Conclusion: The surface treatment of carbon fiber posts significantly improved their retention to composite resin.

Purpose: To assess the gonial angle changes using BSSRO technique for mandibular set back. Methods & Materials: Lateral cephalograms of 30 patients, 11 male & 19 female ranging from 18 to 38 years old who under went BSSRO to treat mandibular prognathism were traced. They were compared before operation, during intermaxillary fixation (IMF) and three months after operation by T - test. The fixation technique was wire osteosynthesis (superior border) - in 24 cases and position screw rigid fixation (2 screws) in 6 cases. Results: Mandibular gonial angle decreased in all patients with a mean of 7° (SD=4.2). This reduction was 10.3° (SD=5.3) in rigid fixation group and 5.2° (SD=3.5) in nonrigid group. In severe set backs (more than 10 mm) the mean of reduction of gonial angle was 5.4° (SD=3.8). Conclusion: In set back osteotomies using BSSRO technique there is a decrease in gonial angle but no significant relation exists between the amount of set back and gonial angle changes.

Purpose: This report presents an extremely rare tumor and provides information to deal with such tumors; intraosseous mucoepidermoid carcinoma. It's pathogenesis is still unknown and is rare in children. The conservative surgical procedures result to metastasis.Case Report: An 11 year old girl was referred for a nonpainful swelling in maxillary region. Central mucoepidermoid carcinoma was diagnosed by clinical and paraclinical examinations.The lining of maxillary sinus was considered to be the source of the tumor. Hemimaxillectomy and adjuvant. radiotherapy was performed as treatment option and patient was reported to be in good health.Conclusion: Early diagnosis and radical resection with adjuvant radiotherapy offered the best chance for eradication of this tumor and that essential to prevent local recurrence and late distant methastasis.

Purpose: Career choice is one of the most important decision making in whole life. Lots of money, time should be spent in order to gain necessary competency to do the job. Choosing dental job should be accomplished with more precise considerations, because prior studies pointed that there is a little chance of changing job for dentists. This study was carried out to assess first year dental students motivation to enter dental profession. In addition, motivation factors of male and female student were compared.Methods & Materials: The study population comprised 92 first - year dental students of Tehran and Shahid Beheshti University. A questionnaire which included information on students demography and motive rankings was administered. Seven dimensions were covered in the questionnaire including income, social status, independency, service to people, manual working with hands, parents advice and relation with people. The results were analysed using Mann - Whitney U test.Results: The data showed that over 60 percent of first - year dental students were females. Most important motives for choosing dentistry were social status and service to people whereas manual working was a less important motive. Statistically significant differences were revealed in two areas of career choice motivation between male and female dental students. Male students were more likely to be motivated by income. By contrast female students were more likely to be influenced by their parents' advice.Conclusion: Having a good status in the society, students are choosing dentistry to gain social status, service to people is yet a strong motive. Female dental students are in the majority. Male students rate income more highly than the females. Male students could be encourages by this point to enter dental profession.

Purpose: Because of over exposure or over development, occasionally radiographs will be darkened. For lightening and better diagnostic quality of radiographs, bleaching agents are used. One of the super proportional reducers is used in this research. The objective of this investigation was to determine the effect of reducing agent on diagnostic quality of extra oral darked radiograph.Methods & Materials: In this experiment, a human skull was used for radiographic examination. Two extraoral films were put in one casselle as double film. After exposure the two films were processed. One of the radiographs was used as control and the other film lmdergone bleaching procedure get light. The bleaching time was recorded, then films were washed in water. They were put in diluted developing solution (1/20 diluted). The suitable color was selected by examiner. The time was recorded. Radiographs were washed in water, then they were put in diluted fixing solution (1/20 diluted). They were washed and dried, and ready to interpret. 43 double film were used in this experiment. Radiologists and surgeon to evaluate diagnostic quality of definitive landmarks in sample and control films. They should give a grade from 1 to 5 for each chosen landmark on sample and control Radiographs.Grade 1 for the worst diagnostic quality.Grade 5 for the best diagnostic quality.The data were statistically studied to determine if there is a significant difference between the diagnostic quality of the control and sample film.Results: According to wilcoxon test, there is meaningful different between the diagnostic quality of the controls and sample films.Conclusion: To improve diagnostic quality of extraoral darked radiographs we can use a super proportional reducing agent such as copper surface solution. This solution not only causes the reduction of density of darked radiographs but also it cause improvement of its diagnostic quality. The concentration of solution used for extraoral Radiograph is different from one that we use for intra oral radiograph.

Purpose: Maintaining the health of oral tissues is the most important purpose of treating edentulous patients. Patient knowledge regarding to oral hygiene and the quality of oral and denture hygiene are the important factors which affect the health of remaining tissues, prevention of lesions caused by prosthesis irritation and treatment success.Previous studies in Iran showed poor oral and prosthesis hygiene of the patients. The aim of this study is to evaluate the oral and prosthesis hygiene among edentulous patients, attending Kerman dental school.Methods & Materials: Ninety three edentulous patients (between 16-84 years old) were evaluated in descriptive study according to criteria of oral and prosthesis hygiene.Results: This study showed that the oral and prosthesis hygiene among these patients were low. Observation of the dental plaque on different surfaces of their prosthesis revealed this point.Conclusion: The patients did not abrasive their mouth and prosthesis hygiene which caused plaque, calculus and stain accumulation on different surfaces of their prosthesis and the methods they used for plaque removal were not efficient.

Purpose: The purpose of this invitro study was to investigate the effect of disinfectants on dimensional changes of Speedex impression material.Methods & Materials: Thirty impressions were taken by Speedex impression material from laboratory stainless steel model. 20 impressions were disinfected, 10 using %5.25 sodium hypochlorite and using 2% Acid glutaraldehyde for 10 minutes. And 10 impressions served as non-disinfected as control group. Impressions were then rinsed under the cold water and stored in room temperature for 20 minutes in disinfected group and 30 minutes in no disinfected group. Casts were made using type IV gypsum. The height and diameters of dies and the distance between the dies were measured in the three groups. Statistical analysis of the data was done using ANOVA and t- test.Results: The height of the die in the sodium hypochlorite group increased and in the glutaraldehyde group decreased vs control group. The diameter of the die in both sodium chlorite and glutaradehyde group had some increase vs control group. The distance between the dies decreased in both groups vs control group. The differences were not significant.Conclusion: There was no significant difference in dimensional changes between disinfected and non-desinfected.

Purpose: To assess the association of halitosis and gram-negative anaerobic bacteria in oral cavity.Method & Materials: The study was analytical and case control in which thirty-four patients with halitosis and 27 normal controls, referred to Department of Oral Medicine in Shahid Beheshti Dental School, have been visited by two dentists and studied microbiologically. Samples for microbiological studies were taken from the base of the tongue by a wooden instrument and immediately transported to liquid thioglycollate medium. The samples were cultured in nutrient culture medium, blood agar, MacConkey agar and chocolate agar after incubation at 37°C for 24 hours in anaerobic jar. Appropriate laboratory tests, such as catalase, coagulase, manitol, gellatinase, oxidase and DNase, were used to make differential diagnosis of cultured bacteria. The results were analyzed, using chi square test, Fisher's exact test, T test and Mann-Whitney U test. All tests were 2-tailed with alpha set at 0.05. Results: Obligate anaerobic bacteria were cultured in 24 of the cases (%70.1) and 11 of the controls (%40.7).This difference was significant (p=0.036, OR=3.5). Thirty-one cases (%91.2) and 24 controls (%88.9) were cultured positive for either facultative or obligate anaerobic bacteria (p=ns, OR=I.3). There was no statistically significant difference between the two groups according to cultured-positive individuals for fusobacterium, fusiform bacillus, prevotella, veillonella, haemophilus, spirillum and kingella, but tendency to difference for bactericides (p=0.083, OR=3.3) and Niesseria (p=0.084, OR=OA).Conclusion: There is an association between halitosis with obligate anaerobic bacteria.

Purpose: Treatment resistance cases in both endodontal and periodontal diseases are sometimes encountered in spite of a good treatment. These cases may be caused by microbial agents and/or inefficient host responses. The microbial factors need further investigation and host response in discussed in this section.Methods & Materials: Thirty two articles and two text were reviewed for this discussion. Conclusion: The main cause of innate and specific immune system involvement in refractory periapical periodontitis are microbial factors, where as in refractory periodontitis the bacterial factor is less prominent and cigarette smoking is considered the main factor with emotional stressors micronutrient deficiency and herpes viruses being contributing factors.

Purpose: Application of heavy forces to maxillary dentition during treatment with headgear, induces high concentration of stresses in periodontal tissue. Quantification of this stress is of great concern in orthodontics. This study was designed to investigate the quantity and quality of stress response in the PDL of maxillary first molar which was subjected to high pull headgear traction using Finite Element method.Methods and Material: In an experimental study, a three-dimensional finite element model of maxillary dentition, consisting of 17096 elements and 23013 nodes, was developed based on a young human skull. The forces were applied to the maxillary first molar in the stabilized Arch by means of a rectangular full size arch wire in (022) slot bracket. Mechanical properties of this model were based on previous studies. A 350 gram force was used for high pull headgear to affect the dentition (+30 degree) and stress distribution was investigated in buccal, palatal, mesial and distal side and in cervical, middle, apical sections of the PDL. The quantity of stresses were expressed as principal stresses (1,2,3), while the negative and positive signs indicated compressive and tensile stresses.Results: The buccal surface of PDL of mesiobuccal root and the buccal, palatal and distal surface in cervical region of PDL of distobuccal root and the distal surface of the PDL of palatal root had received a great deal of stresses, in addition, the over all stress distribution in roots of molar had intrusive nature.Conclusion: The extension of high stress concentration areas observed after using high pull headgear is limited to some root surfaces specially the distobuccal root.

Purpose: Exfoliation of deciduous teeth and eruption of permanent teeth are an important stage for child's parent and dentist. The purposes of this study are: 1) to determine the mean and range of the times and sequence of eruption of permanent teeth in Turkman children, 2) to determine the relationship between eruption of permanent teeth with age and gender.Method & Materials: In this analytical and cross-sectional study, 1365 (681 boys and 684 girls) 4-14 years old Turkman children from schools of Gonbad Kavoos City were selected randomly and examined. If a tooth was observed in oral cavity, it meant eruption. The time and sequence of eruption was recorded in a questionnaire. The data were analyzed by SPSS software and t test analysis.Results: The first erupted-teeth were lower central incisors and first molars in girls and last erupted-teeth were upper second molars in boys. The sequence of eruption in girls was 6124357/6123457 and  124537/6124357 in boys.Most of the lower permanent teeth erupted earlier than upper teeth; only for the first premolars in boys, earlier eruption in upper jaw (than lower jaw) was statistically significant. Only for upper canines in girls, difference between mean eruption times in two sides of jaws was statistically significant. Most of the permanent teeth erupted earlier in girls than boys; only for upper central incisors, earlier eruption in boys (than girls) was statistically significant. Conclusion: Permanent teeth in Turkman children erupt later than Lysell's and Hurme's standard tables. In Turkman children the median of eruption time in some teeth is more and in some teeth is less than Tehranian children and in one teeth is equal.

Purpose: The increasing use of foreign toothbrushes along with their higher prices in comparison with Iranian toothbrushes has made us to perform this study in order to evaluate macroscopic characteristics of ten types of toothbrushes Laleh, Mina, Jarda, Jourdan, AlFalij, Dr.Best, Oral-B, Butler and Crest before and after 1,2 and 3 months using.Methods & Material: This experimental study was carried out on 240 students (12 years old girls), of Shahid Beheshti school with observation and questionnaire as its technique. The students were divided to 10 groups according to 10 kinds of toothbrushes. They used the toothbrushes for 1,2 and 3 months. Finally, the toothbrushes were gathered and their bristles were evaluated.Results: Tests (Analysis of variance, Tukey and chi square) showed showed that all the toothbrushes except of Laleh, Mina and Oral-B were in the range of standard. Laleh and Mina toothbrushes just in the bristle-less edge and Oral-B in the size of toothbrush head were out of standard range. There was a significant difference between the end roundness of different toothbrushes and between the changes of bristles after 1, 2, 3 month application (P<0.001).Conclusion: Satisfaction of using and end roundness among foreign toothbrushes was more than Iranian toothbrushes.

Purpose: The lower part of the face, especially mandible is more susceptible to fracture. This study was done to estimate the prevalence and the causes of mandibular fractures in the patients referred to Taleghani Hospital 1999- 2003.Method and Materials: The patients with mandibular fracture referred to Taleghani Hospital were studied. The site of fracture, the kind of surgery done, the causes of fracture were recorded and inserted into SPSS software. Results: Four hundred and twenty seven patients (364 male, 63 female), between 3 to 83 years old were referred for mandibular fracture. The peak of incidence occurred in the ages of 20-30. The condylar fracture was the most frequent in mandible. Of the fractures, more than %45 of the fractures were due to car and motor vehicle accidents.Most patients (%71.1) were treated by close reduction surgery.Conclusion: To prevent the mandibular fractures it is recommended to obey the traffic rules and make the drivers to use safety devices during driving.

Purpose: There is a wide clinical application of Duralay acrylic resin pattern for direct post and core fabrication.As the effect of time elapse, desinfection solution and preservation places is not studied together, this study was designed to evaluate the interaction of these variables on dimensions (length, coronal and apical diameters) of duralay acrylic resin patterns.Methods & Materias: In this in vitro and quasi experimental study 36 duralay patterns fabricated in simulation method were used. Then patterns were categorized in one of the 3 groups of glutaraldehyde, sodium hypochloride and control. Each group of 12 patterns was divided in the two groups of preservation places (wet and dry). Patterns were measured in time intervals of 0, 1, 3, 6, 9, 24 hours. The 3 dimensions of length and apical and coronal diameter were measured with digital micrometer with 10 microten accuracy.Results: Statistical analysis demonstrated that coronal and apical diameters differ significantly by the effect of time elapse and disinfection solutions and preservation places (P<0.005). Coronal diameter demonstrated significant difference as the etfect of time elapse. (P<0.005) Significant differences were not noted between wet ordry preservation places. Glutaraldehyde caused contraction and sodium hypochloride caused expansion of duralay patterns. The mechanism of this different effect was not understood.Conclusion: It was observed that linear dimensional change of duralay acrylic patterns didn't follow a linear correlation formula for prediction of duralay changes and the best time for casting. Different effects of desinfection solution on casting and cementation stages must be evaluated to achieve better evidence and clinical relevance.

Purpose: Tooth brushing is the most common method for removing dental plaque. The design of toothbrush influences the amount of plaque removal. The purpose of this study was to compare the two manual toothbrushes (Oral-B and chic) in their efficacy in removing plaque.Material & Method: This experimental study was done cross over and single blind. Forty children 8 to 10years old were selected and told to stop all oral hygiene procedures for 24 hours. In the first visit dental plaque was evaluated by means of Shick-Ash index before and after brushing with one of the test brushes. The brushing was done 20 times in every quadrant by one of the authors by scrub method. Children were instructed to use their routine method of oral hygiene and return to the clinic one-week later. The same plaque removal procedure and plaque index assessment was applied for the other toothbrush in the second appointment. Data were analysed using Paired -T-test.Results: Statistical analysis showed significant differences in reducing PI for the two toothbrushes (chic, P=0/0005 and oral-B, P=0/0006). The results indicated no significant differences in reducing PI between the two toothbrushes (P=0/075).Conclusion: Both toothbrushes (Oral-B and chic) were equally effective in reducing PI. It seems that correct brushing as equally important as kind of toothbrushes.

Purpose: Together with the increase of orthodontic treatment needs the use of functional apparatus has been increased. Furthermore, different studies has been done on skeletal and dental changes after the use of these functional appliances, but few studies discussed soft tissue changes in the field. So, this study was carried out in order to evaluate soft tissue changes following the use of Twin Block functional appliance.Methods & Materials: This study was quazi experimental done on 13 patients (7 girls and 6 boys) with 7 years and 7 months to 12 years and 6 months of age. All patients were Cl II Div.I malocclusion, Iranian, Muslim, resident of Tehran and with no previous orthodontic treatment and tooth extraction. The period of treatment with the apparatus varied between 7 to 17 months. The studied angular variables were nasolabial, nasofacial, facial convexity,H angle, mentocervical, nasomental and mentolabial. The liner variables were lower and upper lip to E line, upper and lower lip thickness, prominence and length, upper and lower face height. All variables were compared before and after the use of Twin Block and recorded in a questionnaire and were analyzed by T - test. Results: The study showed that nasolabial, nasofacial, Lower lip to E line and Upper lip length decreased slightly with the use of apparatus, while facial convexity, H angle, upper lip prominence, upper lip thickness and upper lip to E line decreased significantly. As well as, mentocervical, upper lip thickness, lower lip prominence and soft tissue lower face height increased slightly and nasomental, mentolabial, soft tissue upper face height and lower lip length increased significantly.Conclusion: Following the treatment with Twin Block, the lower face soft tissue moved anteriorly leading to decrease in profile convexity. The upper and lower face soft tissue height increases and their ratio improved. The upper and lower lip thickness reduced, but upper lip length did not change and lower lip length increased after the treatment. The space between upper and lower lip edge to E - line moved to a normal range and labiomental fold became wider.