Journal of Mashhad Dental School
Year:2005 | Volume:28 | Issue:3-4|Papers Count:19

Introduction: Instruments and equipments used in dentistry field produce sounds with wide spectrum, so dentists and other personnel are exposed to these sounds continuously. The purpose of this study was measuring the received noise level of personnel working in clinics of Mashhad dental school and frequency analysis of sounds at 20-20000 Hz frequency range.Materials and Methods: In this study, the noise level in operational dentistry, endodontics, prosthodontics, oral surgery, periodontics, pediatric dentistry and orthodontics of Mashhad dental school were assessed in 2004. Sound level measuring device and their establishment and set up were selected in which according to acquired data, the received noise level of dentist and average received noise level of personnel could be calculated.Results: Equivalent noise level (LAeq) measured surrounding central unit of each clinic, was less than 73.2 dB and noise level inside each clinic was less than 69.9dB. The dentists received noise level during work and presence at the studied clinics was measured to be 67.2-83.7 dB.The equivalent maximum noise level in all clinics was related to frequency band of 630 Hz and sounds of operational dentistry, endodontics and periodontics clinics had strong components in high frequency.Conclusion: According to permitted exposure noise level, the received noise level of dentists and personnel in studied clinics were not hazardous, but because of high frequency sounds, it is suggested to repeat the study with systems which can assess analysis of higher frequencies.

Introduction: This was a descriptive cross- sectional study of which purpose was evaluation of the knowledge of patients in clinics of Mashhad dental school about AIDS.Materials and Methods: In this study 300 patients (40% male and 60% female) were randomly selected. To gather the information, a standard questionnaire including two parts was prepared. The first part was about personal information and the second part consisted of 24 questions on the nature, diagnostic methods, HIV transmission and Attitudes toward AIDS. Chi-square test and t-test were used for data analysis.Results: The mean age of cases was 32.04 years and most of them had high school diploma or associate degree. 93.7% of the cases inhabited in the urban areas. The mean knowledge score in this study was 14.57±4.6 of the total 24 (24 questions). The lowest level of knowledge as well as the attitudes belonged to the inhabitants of rural areas.There was no significant relationship between the level of general knowledge and sex, while we found a significant relationship between the level of general knowledge and marital status, age, education, occupation and the residence place. 75.3% of the cases in this study asked for diagnostic trials for AIDS before any dental treatment on all the patients.Conclusion: According to this study a more serious education on AIDS especially in rural groups must be considered, necessitating our efforts to modify the negative attitude toward AIDS.

Introduction: Recognizing the main contributing factors of crowding has always been a matter of interest in orthodontics. The purpose of this investigation was to examine the extent of which tooth size or jaw dimension contribute to dental crowding.Materials and Methods: In this cross-sectional descriptive study, two groups of dental casts were selected on the basis of having or not having dental crowding. The first group consisted of 30 pairs of dental casts (15 male and 15 female) which exhibited normal occlusion (without crowding). The second group consisted of 30 pairs of dental casts (15 male and15 female) with gross dental crowding and class I skeletal pattern. Mean values and standard deviations of the following parameters were used to compare the two groups: individual and collective mesiodistal tooth diameters, dental arch perimeters, dental arch lengths and buccal and lingual dental arch widths in canine and molar region. To compare the two groups, two tailed student-t test, with 95% confidence interval was used.Results: On the basis of our research crowded and non crowded group had statistically significant differences in both mesiodistal tooth diameters and transverse arch dimensions.The crowded group was found to have smaller transverse maxillary dental arch dimensions but larger tooth diameters than in the normal occlusion group.Conclusion: The results of this study suggest that consideration should be given to those treatment techniques which increase dental arch transverse width and also decrease tooth material by means of extraction or stripping.

Introduction: The purpose of this study was to evaluate chephalometric changes of soft tissue profile after four first premolar extraction of upper and lower arch in class I bimaxillary dent alveolar protrusion (B.D.P.) cases.Materials and Methods: This investigation consisted of 20 female patients with B.D.P. The mean age of this group was 16±6 years with a range of 12 to 38 years. All of them treated by extraction of four first premolars with standard edgewise technique. Pre and post lateral cephalograms were traced and the cephalometric criteria were measured.Results: This study showed that upper and lower lip protrusion were decreased 2.7±2.9 (p<0.001), 2.8±2.8 (p<0.001) mm respectively. The angle between upper incisor to SN and lower incisor to mandibular plane decreased 10.3±5.8 and 8.3±5.2 respectably. The angle between upper and lower incisor increased about 17.6±9.5. By using stepwise regression analysis the ratio of upper lip retraction to maxillary incisor retraction was 0.63:1 and the ratio of lower lip retraction to mandibular incisor retraction was 0.62:1.Conclusion: This study concluded that a strong correlation exists between retraction of anterior teeth and the position of lips.

Introduction: In the orthogenetic surgery of the mandible and especially bilateral sagital spilt osteotomy (B.S.S.O), the most complication is some change in mandibular border movement, and as a result limitation of mandibular movement. The aim of this study was to evaluate the changes in maximum interincisal opening, left and right lateral excursion, and protrusive movements in all patients before and after operation in the period of three to six months and the effects of modern physiotherapical plans (CPM) on increasing these movements after surgery.Materials and Methods: This is a prospective clinical trial study. In this study 30 patient's (18 females & 12 males) who were 13-30 years old (average age 20.5), BSSO surgery was performed according to Epker procedure with surgical handpice and bur, rigid fixation were performed with 3 positional screw of 2mm diameter for all patients. MIO, LLE, RLE, PM were measured before and after operation in the period of three to six months. At the end the patients who still had mandibular movement limitations were divided into two groups of experiment and sample, then the effects of 20 physiotherapical sessions were studied after the 9th month.Results: After 3 months post-op, considerable reduction in all mandibular movements has occurred, but after 6 months post-op, 12 patients (40%) had significant limitation of mandibular movements, especially in MIO & PM. At the end of nine months post-op all patients in sample group, had limitation in mandibular mobility but in the experiment group all patients had normal mandibular border movement.Discussion: There are different reports about the effect of orthogenetic surgery on mandibular border movements. In this study BSSO for mandibular setback has led to considerable reduction in mandibular movement especially maximum interincisal opening & protrusive movements and the physiotherapical treatment have been considered as the solution of the mentioned problems but the major difference between our study and others are, using of Rigid fixation, not using MMF and two week usage of elastic Training.

Introduction: Cancer is the second – leading cause of death in the United States. The ultimate aim of treatment of cancerous patients is definitive cure and improvement of quality of life. Side effects of cancer therapy are acute and chronic, so study of different factors which influence mucositis as an acute side-effect of head and neck chemotherapy and radiotherapy would be beneficial. Mucositis in severe cases could lead to treatment stoppage.Materials and Methods: 90 patients under chemotherapy and 10 patients under head & neck radiotherapy were included in this descriptive analytic study at Omid hospital (cancer treatment center) from Oct. 2002 to Apr. 2003. A questionnaire including patient and treatment related risk factors were filled for each patient. Patient related risk factors consisted of sex, age, oral hygiene, history of systemic disease, and smoking habits while treatment related risk factors consisted of schedule, chemotherapeutic agent, total dose and field of radiotherapy. The patients in radiotherapy group were examined clinically every two weeks and patients in chemotherapy group were examined only if they complained of mucositis.Results: No one in the chemotherapy group referred to the hospital with mucositis. 80% of the patients in the radiotherapy group suffered from mucositis (from grade I to IV). There was no significant relationship between the radiotherapy and patient risk factors and either the time of mucositis onset or the highest grade of mucositis. This can be due to the insufficient number of samples.Conclusion: Considering the insufficient number of samples in radiotherapy group and lack of patient referring in chemotherapy group due to mucositis, other studies with sufficient samples and longer periods are recommended. Conducting studies including hematologic malignancies as well as other malignancies are also recommended.

Introduction: NHP is a position that depends on morphology and figure of every body. The purpose of this study was measuring cephalometric norm in NHP to compare four anteroposterior analyses of Cooke, Wits, Reidel and Sassouni in NHP and determining their consistence with clinical status.Materials and Methods: This study was a cross sectional study and the data collecting method was direct observation and lateral cephalomteric radiography using informational forms. In this study 40 high school student girls with normal occlusion and the age between 16-18 years old with an average of 17.3 years old were selected from different districts of Mashhad through random cluster sampling. From each student one lateral cephalometry (with permission from the parents and students) was taken in NHP position.The data were analyzed using SPSS statistical software (Fisher's exact test in two way cross tabulation).Results:1.Cooke, Wits, Reidel and Sassouni showed 85%, 75%, 70% and 32.5% concordance with the clinical status respectively. 2. In comparison between Wits and Reidel analyses, the difference was not significant. P-v>0.05 3. In comparison between Cooke and Wits analyses, the difference was not significant. P-v>0.05 4. In comparison between Wits and Sassouni, the difference was highly significant. P-v<0.01 5. In comparison between Reidel and Sassouni, the difference was highly significant. P-v<0.01 6. In comparison between Cooke and Sassouni, the difference was highly significant. P-v<0.01Conclusion: In this study statistical evaluation justifies more concordance of the anteroposterior analysis of Cooke, Wits and Reidel with clinical status but Sassouni analysis can not be considered as a reliable method. In comparing the upper methods from view point of reliability, Cooke seems to be the most reliable analysis followed by wits and Reidel analyses.

Introduction: It is thought that the most important factor for pulpal stimulation and necrosis is the microleakage of intracoronal and extracoronal restoration. A luting cement with a favorable seal and the least bacterial leakage should be selected.The purpose of this study was to compare the microleakage of four luting cements: Zinc phoshate, zinc polycarboxylate, glass ionomer and panavia F and also three finishing margins: deep chamfer, shoulder, and shoulder bevel, when been applied with porcelain fused to base metal crowns.Materials & Methods: In this parallel interventional study, 96 intact human premolars were selected and divided into three groups of 32 based on the type of finishing line. Each group was randomly divided into four subgroups of 8, based on the type of luting cement. After cementation, the specimens were thermocycled. Dye penetration was done by 0.5% fushin.The data were statistically analyzed using Kruskal Wallis and Mann-Whitney test (α =0.05).Results: 1. There was a significant difference among cements in respect to mean rank of microleakage (P<0.05)2. There was a significant difference in mean rank of cements after two by two comparisons. (P<0.05)3. The least microleakage was observed in Panavi F followed by glass ionomer and zinc polycarboxylate.4. The greatest microleakage was observed in zinc phosphate cement.Conclusion: Panavia F as a luting cement could create suitable seal for base metal crown due to its ability in producing the least microleakage and adhesion to dental tissue.

Introduction: The biologic width is invaded by different factors, among them; the periodontal surgery could be mentioned, especially when accompanied by bone contouring.The aim of this study was to determine the changes of alveolar crest which participate in the reconstruction of biologic width after applying two methods of periodontal surgery.Materials and Methods: 20 patients were selected from the special clinic of Mashhad Dental School and after initial therapy, the surgical treatment were performed by a single operator. Since the study technique was cross over with split mouth design, at one side apically positioned flap (APF) with bone exposure and at the opposite side the APF without bone exposure were perfumed.The distance between CEJ to bone crest was determined. After two months the patients were examined for the same parameters by sounding technique. For analysis of data, paired t-student test was used.Results: The results showed that at sites of apically positioned flap with bone exposure, the crestal resorption was 0.77±0.63mm and on the opposite side it was 1.05±0.19mm. The difference before and after surgery in each area was significant but the difference between two sides was not significant.Conclusion: It was concluded that crestal resorption observed following two periodontal surgery methods plays an important role in reconstruction of biologic width.

Introduction: Prediction of a child behavior and interaction with the practitioner, particularly a dentist, is an important factor in successful diagnosis and treatment especially at the first and generally at subsequent appointments. In this study, the major contributing factors which are important for the prediction of a Childs' behavior and way of preparation of the practitioner were studied.Materials & Methods: In this descriptive-cross sectional study which was done during the second semester of 2001-2002 at Mashhad dental school, one hundred 3-6 year old children (50 girls and 50 boys) with normal physical, psychological and intelligence stata were selected randomly and classified according to a history through interviewing with parents and state behavior, comparing with franckles behavioral rating scale during three different dental visits.Results: The result revealed that 10.4% of children had difficult behavioral characteristics, 40.1% had easy behavioral characteristics and the remaining was placed in difficult-easy interval. These results were consistent with other studies according to franckles behavioral rating scale, but there were no relationships between easy-difficult behaviors and any of the factors age, occupation of parents or birth order of children.Conclusion: According to signs and factors achieved through observation, examination and interview with parents and children, it is possible to predict the Childs' behavior during examination and treatment (specially dental treatments which are stressful for most of patients) and take appropriate actions according to Childs' behavior without reaching the irritation threshold of child as well as the practitioner.

Introduction: Maintenance of primary teeth has a special importance for development of occlusion and arc stability. Primary teeth which have lost a lot of tooth structure are restored routinely with stainless steel crowns. Bonded restorations reinforce the remnant structure of tooth and increase the fracture strength. The purpose of this study was to determine the fracture strength of pulpotomized primary molars after restoring with Coremax II and Compoglass.Materials & Methods: In this parallel in vitro interventional study, 60 extracted second primary molars were selected. After the teeth were mounted in self-curing acrylic resin, the standard pulpotomy was performed. The teeth were divided into 3 groups of 20. Group A was restored with Coremax II, group B with Compoglass and group C (control) with amalgam. All groups were subdivided into 2 subgroups for load cycling Subgroups A1, B1 and C1 were regarded as baseline without load cycling. Subgroups A2, B2 and C2 were loaded for a period of 5 days load cycling. After that, the specimens were placed in Incubator for 24 hours. Finally all groups were fractured in the Instron Machine. Compressive test was performed with the round Cross head speed of 5-mm/min. All specimens were examined for type of fracture (adhesive, cohesive) with use of a steriomicroscope (x16). Quantitative data analysis was done using ANOVA and Duncan's test with a 95% significance level. Chi-square test was performed for evaluation of kind of fracture.Results: There was an interaction between two factors of time and material (P<0.05). The time interval had a significant effect on mean fracture strengths of Coremax II and amalgam (P<0.05). The most fracture strength was observed at base line. Kind of material had a significant effect on fracture strength. At baseline, Compoglass had the least mean fracture strength (97.19 kg) and Coremax II had the greatest one (131.39). After 5 years there was no significant difference in fracture strength between amalgam and Compoglass, but the fracture strength of Coremax was significantly higher than the others (P<0.05).There was a correlation between kind of fracture and material. In amalgam, 100% of fracture was of adhesive and in Compoglass, 60% of cohesive type while in Coremax II, 85% of the fracture was of adhesive type.Conclusion: According to this study and because of high fracture strength of teeth restored with Core max II, this material is an acceptable restoration material just for restoration of pulpotomized primary molars.

Introduction: The purpose of this research was to determine the status of oral and gingival hygiene of dialytic patients (case group) in comparison with healthy children (control group).Materials and Methods: The two groups which consisted 19 hemodialytic patients aged between 5-16 years old from the Dr. Sheikh hospital as case group and 19 patients of the dental school as control group were examined.These two groups were matched according to age, sex and status of tooth-brushing. In both groups, there were 10 girls and 9 boys, 7 aged between 5-10 years and 12 aged between 11-16 years. In both groups the Gingival Index, Debries Index, simplified Calculus Index and oral Hygiene Index were examined. Mann-whitney and kruskal-walis test were used for statistical analysis.Results: Evaluation of the indices mentioned above showed that the DI-S and GI were significantly higher in Case group than Control group, but there was not any significant difference between the 2 group in OHI-S and CI-S. Assessment of the indices according to the age in the case group, displayed that CI-S was higher in patients aged 11- 16 years old.Conclusion: Among the hemodialytic patients, plaque formation and the resultant amount of gingivitis was increased.

Introduction: The purpose of this study was to investigate the amount of denuded root coverage using subepithelial connective tissue graft.Materials and Methods: 12 patients (8 female and 4 male) between 22 and 43 years old with at least one tooth with gingival recession were selected. The following parameters were measured for each tooth: 1.Gingival level to CEJ height. 2. Gingival level to the reference point height 3.Recession width in CEJ. 4. Pocket depth 5.The amount of keratinized gingiva. Gingival graft surgery was done with the Langer & Langer technique. The parameters were measured at baseline and one, two and three months after surgery. Statistical analysis was performed using ANOVA and correlation coefficient.Results: The results revealed that our procedure was successful in 75% of cases in root coverage of greater than.1.7 mm and in about 92% of cases in increasing the width of keratinized gingiva more than 2 mm. Conclusion: Subepthelial connective tissue graft procedure could be used successfully in treating denuded roots.

Introduction: One reason for endodontic failure is calcified canals. Canals may be calcified radiographically or clinically but are not often completely obliterated.The purpose of this study was to determine the microscopic size of open spaces in clinically and radiographically calcified canals.Materials and Methods: In this in-vitro descriptive study 18 human extracted teeth including 21 calcified canals were selected and transverse sections were prepared in 0.8-0.9mm thickness and studied using a stereomicroscope. After taking digital photographs of these sections, open spaces dimensions were measured in each section using Auto Cad 14 program.Results: Computerized evaluation of samples revealed varying dimensions of open spaces. Open spaces were observed in most of the canals, especially those with closed orifices.Conclusion: According to varying dimensions of open spaces in calcified canals, practitioners are recommended to be more persistent when negotiating canals with calcified appearances.

Introduction: Resistance to sliding and tipping of a restoration must be considered at the time of treatment planning. Some factors have influence in resistance such as type of occlusion, size of occlusal table in comparison with cervix, and place and amount of occlusal forces. When the occlusal table of a restoration is wide and the cervical part is narrow, it is very probable that the line of action of an applied force on marginal ridges passes outside the margins of the restoration and produce destructive torque and causes dislodgment of the restoration. Leverage is probably the predominant factor in the dislodgment of cemented superstructure of implant supported prosthesis that results in disruption of the cement film. The purpose of this study was to evaluate the effect of finishing line form on cement microleakage in implant supported prosthesis following occlusal forces in cusp to marginal ridge occlusion.Materials and Methods: In this experimental study, 90 metal models were made similar to implant abutment with three types of finishing lines (Shoulder, Sloping shoulder, and Knife edge). Ninety crowns were made from base metal alloy with the occlusal table similar to mandibular first molar and cemented on the models. All specimens were subjected to 1000 thermocycles between 5oc and 55oc, with a dwell time of 15 seconds. Each group was divided into 2 subgroups. The subgroups were subjected to 50000 masticatory cycles (equal to 3 months of mastication) with 60 and 100 N occlusal forces on the marginal ridge. All samples were then immersed in 5% basic foshin solution for 24 hours and mounted in polyester to be sectioned vertically. Microleakage was measured under a microscope with magnification of 40 times. The results were analyzed using One-Way & Two-Way ANOVA and t-test.Results: There was no difference in microleakage rate between 3 forms of finishing lines. The interaction between finishing lines and occlusal force of 60 N showed significant difference (P= 0.0182<0.05).Conclusion: The results of this study showed that the least microleakage was observed in shoulder finishing line.

Introduction: The minimum acceptable light intensity for light cure systems is 233mW/Cm2. This intensity is acceptable just for curing the surface of composite and is not acceptable for the deeper areas. Light intensity decrease after passing through different thicknesses of tooth structures and dental materials can affect the degree and depth of polymerization of light cure materials. The purpose of this study is evaluation of light intensity decrease after passing through different thicknesses of dental structures, light activated hybrid and microfilled composites, light activated glass ionomer, bioglass, dental porcelain and also air.Materials and Methods: Six groups each containing five samples including hybrid composite, microfilled composite, glass ionomer, dental porcelain, bioglass and dental structures in five thicknesses from 1 up to 5 millimeter were prepared. The intensity of curing light was measured by radiometer after passing through samples and the air.Results: Rate of light intensity reduction reduces dramatically after passing through different thicknesses of dental porcelain¸ tooth structures, microfilled composite, hybrid composite, bioglass, glass ionomer and air respectively .The reduction rates for dental porcelain, tooth structures, microfilled composite, hybrid composite, bioglass, glass ionomer and air with 1.0 mm thickness are 88, 80, 78, 68, 47, 44 and 0.7 percent respectively. As thickness increases, reduction of light intensity increases. Higher light intensity reduction occurs after passing through dental porcelain and the lower occurs within air.Conclusions: 1. Application of light cure material in less than 1.mm thickness could have better results due to polymerization.2. For light cure glass ionomer it is acceptable to cure only for one millimeter thickness.3. For bioglass as a light coducting insert and material, the acceptable curing depth is up to3mm. so higher light curing intensity is suggested for different sizes and thickness of these inserts.4. For other materials and tooth structures even after passing through 1mm thickness, the adequate intensity is not aquired. So units with the ability of producing higher intensity radiation patterns are suggested.5. The reduction rate of light intensity due to different distances is considerably lower than when light is passed through different thicknesses of dental materials and tooth structures.

Introduction: Assessment of edentulous patients, motivation to attend practical denturists office for providing a denture, was important for us.Methods and Materials: 450 patients were selected by "random sampling" method and each case were analyzed by his or her choices in the questionaire. Results were presented by bar diagrams and pie charts.Results: There was a significant relationship between the number of patients attending denturist's office and the patient's level of education. The higher the level of education the less the patients showed up in the partical denturist's office.There was also a relationship between the number of patients attending denturist's office and the patient's economical class, so the higher the economic class of the patients, the less they showed up in the practical denturists office.Conclusion: There were several reasons for referring to the practical denturists but the major reasons were as follow:1. Rapid construction and delivery of denture.2. Encouragement of relatives and friends of patients.3. Practical denturists seemed more experienced to the patients.4. Lower cost of practical denturist's services.

Introduction: Dental radiography has a major role in diagnosis of oral and dental diseases. Different technical methods are used to obtain high quality image in radiography and reduce X-Ray exposure in the patients. In this research modified techniques for periapical intraoral radiography with parallel technique by using XCP and Snap-A-Ray film holders had been used to overcome technical errors.Materials and Methods: With the use of XCP and Snap-A-Ray film holders, 96 parallel periapical intraoral radiographs were taken from 96 patients who were referred to the radiology department of Isfahan dental school with the same condition of operation such as voltage (70 kvp), Amp (8mA). The type of radiography films was E speed.From 96 radiographs, 6 of them were included in the pilot study and 90 radiographs were processed automatically (processor) in the same condition and after observation by the radiologist, the reports were written in the checklist.Results: Evaluation of intraoral radiographs obtained by use of Snap-A-Ray film holder, showed technical errors of cone cutting (26.7%), displacement (15.6%), foreshortening (13.3%), elongation (8.9%) and overlapping (2.2%) whereas none of these technical errors were observed in intraoral radiographs obtained by use of XCP film holders.Discussion & Conclusion: Totally the XCP film holders are easier to use and image quality of radiographs are better than those of Snap-A-Ray film holders. Regarding to the absence of technical errors and better image quality using XCP film holders, these film holders are preferred which prevents repetition of radiography and reduces patient x-ray exposure dosage.

Introduction: One of the major factors in a successful root canal therapy is the knowledge of anatomy and root canal morphology.The presence of 4-rooted maxillary second molars has been described in only a limited number of case reports. The purpose of this report was to show presence of two palatal roots in maxillary second molar in one patient.Results: A 43-year-old female patient was referred for root canal therapy of maxillary right second molar due to invasive caries. The diagnostic radiograph revealed presence of anomaly in roots. After access cavity preparation presence of four orifices in pulp chamber was confirmed and all of the steps of root canal therapy were performed.Conclusion: Knowledge of the most common anatomic characteristics and their possible variations of root canal morphology are fundamental. Report of uncommon cases can motivate the dentist to consider the rarities during root canal therapy.