Showing 359 results for Ion
A. Pahlavan , S. Banava ,
Volume 16, Issue 4 (1-2004)
Abstract
Statement of Problem: Composite reins have recently become popular for posterior teeth restorations. Gap formation and subsequent microleakage are of the complications resulting from such restorations. One of the techniques to overcome polymerization shrinkage of composite resins is sandwich technique (application of glass ionomer as a base beneath the composite resin). Since polymerization patterns in two types of composite resins (light cure and self cure) differ from each other, various effects on the bond strength between glass ionomer and dentin are expected.
Purpose: The aim of this in vitro study was to evaluate the effects of self- cure and light- cure composite resins in sandwich technique on the bond strength of light cure glass ionomer and dentin.
Materials and Methods: 40 extracted human premolars were selected and divided into four groups:Group 1: Light cure glass ionomer of 1mm thickness was placed on dentin.Group 2: 1mm thickness of light cure glass ionomer plus a mass of self cure composite resin of 2mm thickness were placed.Group 3: 1mm thickness of light cure glass ionomer plus light cure composite resin as two separate 1mm layer were placed.Group 4: 1mm thickness of light cure glass ionomer with 37% phosphoric acid etching followed by two separate layers of light cure composite resin of 1 mm thickness were placed.SEM was used to determine gap size ai Gl- dentin and Gi- composite interlaces. The findings were analyzed by ANOVA and t-student tests.
Results: Groups 1 and 2 showed no gap at Gl-dentm interface and also cracks were not observed in all these specimens. In group 3, there was gap between light cure GI and light cure composite resin and cracks were seen in GI, too. Group 4 showed gap at both interfaces and more cracks were seen in GI. Groups I and 2 showed the least gap formation and group 4 showed the most. Statistically significant difference was found between groups 3, 4 and group 1 (control), 2.
Conclusion: Base on this study, the application of self-cure composite resin on light cure GI showed no gap and crack formation on Gl-dentin and Gl-composite interfaces and GI itself. However, light cure composite resins and glass ionomer etching aggregated crack and gap formation.
M. Ramezanian , A. Alizade ,
Volume 17, Issue 1 (4-2004)
Abstract
Statement of Problem: Tooth extraction is always considered as the final treatment option in dentistry.Considering the numerous advances in dentistry, nowadays the preservation of the permanent teeth until old age is common. However, in most economically poor countries or those without security service insurance,the high rate of extraction, particularly among restorable teeth, is regrettable.
Purpose: The aim of the present study was to determine the reasons for tooth extraction among patients referred to the faculty of Dentistry, Tehran University of Medical Sciences in 2002.
Materials and Methods: This descriptive and cross-sectional study was conducted on 320 patients. The information about patient's general knowledge, oral health status, tooth location and causes of extraction were collected and recorded in a questionnaire. The data were submitted to statistical Chi-Square test.
Results: No statistically significant difference was found between two genders in their mentioned causes for extraction. The most prevalent reasons were as follows: Caries (50%), Periodontal diseases (16.6%). Absence of an acceptable occlusion, prosthetic problems, patient's request, etc... make up the remaining 33.4% of the reasons.
Conclusion: According to this study, it is suggested to investigate extraction etiology at the society level and if similar results are obtained, necessary steps should be taken to prevent caries and periodontal problems as the major mentioned causes for tooth extraction.
A. monzavi , Sh. Lavvaf ,
Volume 17, Issue 1 (4-2004)
Abstract
Statement of Problem: Nowadays economical issues on high gold alloys have changed the practice of metal-ceramic restorations toward base-metal alloys. Minalux is one of the base-metal alloys produced in Iran. Marginal fitness is of high importance to be evaluated in dental alloys.
Purpose: The aim of the present study was to compare the marginal adaptation of two base-metal alloys, Minalux (Mavadkaran Co. Iran) and VeraBond2 (Aibadent Co. USA ) during firing cycles of porcelain.
Materials and Methods: In an experimental study 24 standard brass dies, with 135° chamfer finishing line were fabricated by Computer Numeric Controlled (CNC) milling machine. The samples were randomly divided in two groups, A and B, 12 in each. Following wax-up, the samples were equally cast with two mentioned alloys. In each group, there were 4 controlled samples, which proceeded to firing cycle without veneering porcelain. Scanning electron microscope (SEM) measurements of marginal gap from buccal and lingual aspects were performed after 4 stages of casting, degassing, porcelain application and glazing. The data were analyzed using Four-way ANOVA and multiple comparative test based on Tukey criteria.
Results: The findings of this study revealed that there was no significant difference in the marginal gap of Minalux (31.10±7.8u.m) and VeraBond2 (30.27±6.96u.m) with confidence level at 0.95 (P=0.43). For both alloys the greatest gap was observed after degassing stage (P<0.05). Porcelain and porcelain veneering proximity caused significant changes in the marginal gap of Minalux castings (P<0.05), however, such changes did not occur in VeraBond2 (PO.05).
Conclusion: Based on the findings of this study, the marginal gaps of two base metal alloys, Minalux and VeraBond2, were proved to be identical and that of the Minalux alloy existed in the range of acceptable clinical application. It was also concluded that Minalux dental alloys could provide proper marginal adaptation.
Ar. Talaeipour , M. Panjnoush , N. Anbiaei ,
Volume 17, Issue 1 (4-2004)
Abstract
Statement of Problem: Subtraction is a newly presented radiography technique to detect minor density changes that are not visible by conventional radiography.
Purpose: The aim of this In-vitro study was to evaluate the efficacy of photoshop subtraction software for detecting minor density changes between two dental images.
Materials and Methods: In this research, five dried human mandibles were held in fixed position while thin aluminium sheets were superimposed on each mandible on the 1th and 2nd molar teeth regions.A reference image, without aluminium sheet placement, was obtained from each mandible subsequently series consist of 20 images with aluminium sheets, ranging from 50p. to "5Q0"x were recorded by radiovisiography (RVG) system. Initial images were subtracted from subsequent ones by Photoshop subtraction software. The difference in density between the two images at the 1st and 2nd molar sites was related to the aluminium sheets. The optical density of aluminium sheets was determined by densitometer.
Results: In the present study, 6.6% of the optical density changes of the minimum aluminium thickness as 300u. could be detected by photoshop software software.
Conclusion: The findings of this study showed that the accuracy of photoshop subtraction software was equal to that of the conventional subtraction softwares. Additionally, the accuracy of this software was proved to be suitable for clinical investigations of small localized changes in alveolar bone.
M. Shahrabi , B. Seraj , Mh. Nekoofar , Sh. Moshrefian , Mj. Kharazi Fard ,
Volume 17, Issue 1 (4-2004)
Abstract
Statement of Problem: Radiography is the most common technique in working length determination, however, because of its limitations is not considered as an ideal technique. Its application, particularly for children due to radiation hazards, technical problems in young and unco-operative children and the superimposition of permanent teeth bud on primary teeth root, lead to numerous problems.
Purpose: The goal of this study was to evaluate the accuracy of an electronic apex locator (EAL) in working length determination of primary teeth.
Materials and Methods: In this in-vitro study 96 canals of the extracted primary teeth, with at least 2/3 of the root length remained, were investigated. There were no obstructed canal, previous root canal therapy and perforation of pulp chamber floor. All working lengths were also measured by radiography. The results of Raypex 4 and radiography were compared with actual root canal lengths determined by direct observation. The applied EAL, in this study was called Raypex 4, a new device belonged to the fourth generation (Ratio Type). The results were analyzed by Chi-Square and Pearson correlation statistical tests.
Results: The accuracy of Raypex and radiography were 61.5% and 63.5%, respectively. The differences between Reypex 4 root canal length measurements and those of direct observation were not significant (P=0.08), but such difference between radiography and direct observation was statistically significant (P=0.01). The diameter of the apical foramen (the site of canal opening) did not affect on Raypex 4 accuray (P>0.05).
Conclusion: Considering the acceptable safetyness, Painlessness, simple and rapid application and an accuracy comparable to that of radiography, the use of Raypex4 EAL for the measurement of primary teeth length is suggested.
A. Khorsand , Y. Soleimani Shayesteh , Ar. Talaci Pour, Ah. Negaresh ,
Volume 17, Issue 1 (4-2004)
Abstract
Statement of Problem: One of the problems associated with the treatment of periodontal diseases is caused through the extension of disease toward furcation area. Several techniques in Conservative, Resective and Regenerative categories have been suggested for the treatment of furcation involvement.
Purpose: The aim of this study was to compare the results of the treatment of grade II furcation involvement in mandibular molars using an allograft material named 'Dynagraft' (a type of demineralized bone matrix) and the coronally positioned flap.
Materials and Methods: In this randomized controlled clinical trial study, twelve patients (9 females and 3 males), aged 25 to 40, suffering from bilaterally grade II furcation involvement of mandibular molars who referred to dental faculty Tehran University of medical Sciences, were investigated. The molars of one side were treated by Dynagraft whereas those of the opposite side underwent the CPF method. Measurements of the probing pocket depth (PPD), clinical attachment level (CAL), keratinized gingiva (KG) and horizontal probing depth (HPD) were recorded at baseline, 3 and 6 months after surgery. In order to investigate the bone radiographic changes, radiovisiography at the mentioned periods in addition to clinical investigation, were performed. For statistical analysis, Paired West was used.
Results: The mean PPD reduction three months and six months after the operation were 1.75 mm and 2.25mm, respectively in the Dynagraft (test) group whereas 1.26mm and 1.27mm in the CPF (control) group (P<0.005). The mean attachment gain three months and six months after the operation were 1.1 mm and 1.5mm respectively in the test group, and 0.2mm and 0.3mm in the control group (P<0.005). The mean KG reduction three months and six months after the operation were 0.5mm and 0.6mm respectively in the test group and those of the control group were 1.1mm and 1.1mm. The mean HPD reduction three months and six months after the operation were 1.55mm and 2mm respectively in the test group (P<0.005) and 0.55mm and 0.55mm in the control group (PO.01). Radiovisiography of the mentioned areas three months and six months after the operation confirmed the changes obtained from clinical measurements, showing appreciable reconstructive results (Bone filling) in the test group as compared with the control group. Moreover, root resorption was not observed.
Conclusion: Based on the results of this study, Dynagraft can be used as an appropriate material in the treatment of grade II furcation involvement in mandibular molars. However, for a through evaluation of such regenerative techniques in furcation involvement, further studies with larger population and long term follow up in addition to histologic studies are suggested.
H. Bashizadeh Fakhar , Sa Fatemi Tabar ,
Volume 17, Issue 1 (4-2004)
Abstract
Statement of Problem: One of the major goals, in most dental researches, is to measure bone destruction or deposition due to the progression or regression of disease. Failure of human eyes to detect minor radiographic density changes resulted in more accurate methods such as optical densitometry and direct or indirect digital densitometry.
Purpose: The aim of this study was to determine the accuracy of a newly proposed method of indirect digital densitometry using modified Photoshop software.
Materials and Methods: Radiographs from 37 samples of urografin solution with three concentrations (12.5%, 25% and 37.5%) were taken on dental radiographic films no.2 and digitized by a scanner. A region with 800*800 pixels was cropped from each image and compressed with the Joint Photographic Experts Group (JPEG) compression algorithm and saved. These new images were then put into registration with new algorithm using MATLAB software version 6.1. This algorithm assigned each image and average pixel value (between 0 and 255). The association between concentration and calculated values for each image was tested with regression analysis and the meaning fullness of differences between calculated values was also analysis by ANOVA test. Tukey HSD and Alpha Krunbach were used whenever needs.
Results: Regression analysis revealed significant correlation between concentration and calculated average pixel value (r=0.883). The differences between average of pixels value for different concentration was significant (P=0.0001). Pixel values showed a good intra- sample and intra-group repeatability (Alpha Krunbach: a=99.96%, a=99.68%).
Conclusion: This method due to its high accuracy, easy usage and densitometer independency can be considered as a suitable alternative for conventional densitometry methods.
Sm. Sahebi, Sh. Rocni ,
Volume 17, Issue 2 (6-2004)
Abstract
Statement of Problem: Different temperature and moisture around Iran and wide usage of stone type IV in dental laboratories in our country were the reasons for us for doing this study.
Purpose: In this survey the effect of temperature, moisture and time on dimensional change of dental stone type IV (Velmix) were investigated.
Materials and Methods: In this experimental study cube shape Metal models (10×10×10mm) was made for Taking impression. We used special tray, which has ten holes (15×20×25mm) and made impression with condensational silicone in two-step procedure, and poured it with stone type IV. stone cubes were divided to different groups. 3 groups holed in fix moisture and variable tempraure and 5 groups in fix temperature and variable moisture. After 2 hours, 24 hours and one-week dimension of stone cubes were measured. Then analysis was done with ANOVA and dauncan.
Results: The following conclusions were achieved: 1-Time has no effect on dimensional changes. 2-Tempreture and moisture has some effect on dimensional changes in stone IV. Increasing of temperature result in stone contraction and increasing in moisture result in stone expansion.
Conclusion: The best temperature for least dimensional change is 20C and the best moisture for a least dimensional change is 30 %.
D. Goodarzipoor, Sh. Shahrabi Farahani , H. Vahedi Gashniani ,
Volume 17, Issue 2 (6-2004)
Abstract
Statement of Problem: One of the dental lesions which is mainly diagnosed by periapical radiography is apical root resorption Diagnosis of the presence and extension of this lesion can put some effects on its treatment plan and prognosis.
Purpose: The aim of the present study was to evaluate the efficacy of periapical radiography on apical root resorption diagnosis. Materials and Methods: In this experimental study, sixty extracted teeth were examined radiographic and histological regarding the presence and extension of apical root resorption. It should be noted that periapical radiographs were taken before extraction of all mentioned teeth. The results were analyzed by Fisher’s exact test.
Results: The results of this study showed significant differences between radiological and histological examinations (P=0.0003). Significant correlation between these two observations was seen only in 53.33% of cases comprising 23% of teeth with root resouption. Non-correlation was found in 46% of samples. Moreover, there was no significant difference in the prevalence of apical root resorption between maxillary and mandibular teeth (P=0.233). Sensitivity of periapical radiographs in apical root resorption diagnosis was determined 57.3%. Conclusion: According to the findings of the present study, it seems that periapical radiography technique does not possess desirable efficacy in diagnosis of apical root resorption and its limitation should be considered by clinicians.
As. Madani, B. Ajami ,
Volume 17, Issue 2 (6-2004)
Abstract
Statement of Problem: In recent years, the prevalence of temporomandibular disorders among children and adolescents has increased, however, no study on the correlation between occlusal relations and temporomandibular disorders, in Mashhad adolescents, has been conducted yet.
Purpose: The aim of this study was to survey the relationship between occlusal indices and temporomandibular disorders (TMD) among Mashhad adolescents, with the age range of 11-14 years old.
Methods and Material: In this descriptive cross-sectional study, 1066 students (533 males and 533 females), age ranging from 11-14 years old (12.620.96 years), from seven Mashhad educational regions, were selected. Temporomandibular joints were thoroughly examined for all subjects. All occlusal indices including dentition system, angles classification, types of malooclusion such as cross-bite, deep-bite as well as types of lateral occlusion, premature contacts in lateral and protrusive movements were investigated. Data were analyzed statistically using, Chi-Square and logestic regression tests.
Results: The prevalence of TMD was 23.5%. There was no significant relation between TMD and type of dentition, angles classification and type of occlusion in lateral movements, however, statistically significant relation was found between TMD and deep over bite (P<0.05). Premature contacts in lateral movements at balancing side were proved to be significant etiologic factors of TMD (P=0.003).
Conclusion: In the present study, premature contacts at balancing side and secondary deepbite malocclusion were considered to be the most important etiologic factors of TMD.
M. Ghavam Nasiri , R. Goharian , A. Madani , T. Salari,
Volume 17, Issue 2 (6-2004)
Abstract
Statement of Problem: Parafunctional habits are the most important factor in the creation of non-carious cervical lesions and correcting of these habits may affect cervical lesions.
Purpose: The goal of this study was to survey the effects of one-year occlusal adjustment on clinical success of non- carious cervical restorations.
Materials and Methods: In this clinical study, sixty tooth-colored cervical restorations on canines and premolars in patients with parafunctional habits (bruxism and clenching) were studied. The teeth, according to the type of restorative material, were randomly divided into two groups: One group with a composite resin (Tetric Flow Group A: n=30) and the other group with a compomer (Compoglass Flow Group B: n=30). After restoration, each group was divided into two subgroups: (A1, B1) with occlusal adjustment (case group), (A2, B2) without occlusal adjustment (control group). The evaluation was perfumed single blind at 6 and 12 months after restorative operations according to Us Public Health Service (USPHS) classification. Assessment criteria included: marginal integrity, marginal discoloration, recurrent caries, postoperative sensitivity and loss of filling. Statistical analysis was completed using Fisher’s exact test.
Results: In 12 month period between two groups of compoglass Flow restorations, group B1 showed superior results than group B2, however, no significant difference was found between both groups of tetric flow restorations (A1 and A2). There was also no difference in clinical conditions between A2 and B2 groups.
Conclusion: Considering the results of this study, it can be concluded that occlusal adjustment puts a considerable effect on clinical success of compoglass non- carious cervical restorations. However, it should be mentioned that such and effect was not found among Tetric flow restoration.
A. Vahid ,
Volume 17, Issue 2 (6-2004)
Abstract
Cervical third root defects, like perforations (due to resoption or iatrogeic), fractures or invasive decays make great difficulties for appropriate restoration making. In these circumstances crown lengthening is needed, especially for anterior teeth. Forced eruption also could be a beneficial treatment. By this therapy, cervical third root defects will be available to receive a good restoration. without gum and biologic width problems. In this article tried to introduce this method of therapy by reviewing litraure and with regard to personal research.
F. Heravi , Sh. Sahafian ,
Volume 17, Issue 3 (8-2004)
Abstract
Statement of Problem: Tooth extraction is a common technique in orthodontics and most of the specialists believe that this technique is able to change the facial appearance.
Purpose: The aim of this study was to investigate facial vertical changes in orthodontic patients following tooth extraction.
Materials and Methods: Thirty patients, after their growth spurt, with CLI malocclusion all treated by a specific orthodontist through Edgewise technique along with the extraction of four first premolars were chosen. Lateral cephalograms of patients, before and after treatment were compared and facial vertical changes and teeth were studied.
Results: Anterior and posterior facial heights were increased during treatment. Despite the limited use of intermaxillary elastics, teeth were extruded. The most increase in facial heights was observed in the lower third of face. Patients with longer faces before treatment showed more extrusion of mandibular molars as well as more increase of mandibular slope.
Conclusion: Tooth extraction in orthodontic treatments can not guarantee the decrease or even non-increase of facial height. Among patients with long faces, it is particularly suggested to refrain from the application of extrusive orthodontic forces.
S. Nokar , R. Baghaee-Naeeni ,
Volume 17, Issue 3 (8-2004)
Abstract
Statement of Problem: In the treatment of edentulous patients with implant supported fixed partial dentures several factors such as implant numbers, implant position, superstructure pattern and cantilever length must be considered. Mandibular flexture in function exerts forces in peri-implant bone, however this phenomenon has received little attention.
Purpose: The goal of this finite element analysis (FEA) study was to evaluate the effect of mandibular dimensional changes on peri-implant bone stress in different prosthesis and implant treatment plans.
Materials and Methods: In this experimental study, three dimensional finite element computer model of mandible was simulated according to data from CT-Scan in 0.5 mm sections. The model of 4.110 mm ITI implant, measured by profile projector, was simulated in solid works 2003 software. Implant models were inserted, in two different patterns, on mandible and three different superstructures were placed on implants. Two clenching tasks were modeled (incisal clench and right molar clench).
Results: Analysis of Von Misses stress for peri-implant bone revealed the lowest stress values in three-piece superstructure.
Conclusion: According to this study, additional placement of implants in order to fabricate independent prostheses and to achieve the freedom of mandibular flexture are recommended.
F. Shafiee , Z. Borhan Haghighi ,
Volume 17, Issue 3 (8-2004)
Abstract
Statement of Problem: Because dental amalgam does not adhere to tooth structure, using adhesive cements in amalgam-bonded restorations have been increased.
Purpose: The goal of this in-vitro study was to compare the effects of three types of glass ionomer as adhesive liners as well as varnish liner in increasing fracture resistance of teeth restored with amalgam.
Materials and Methods: Seventy extracted human maxillary premolars were selected and MOD cavities were prepared on them excluding ten intact teeth as positive control group and ten cavity prepared teeth without restoration as negative control group. All the prepared teeth were then restored with spherical amalgam (gs.80) with one of the following liners silver alloy glass ionomer liner, conventional glass ionomer liner, varnish liner, resin-modified glass ionomer and resin-modified glass ionomer with delayed light curing. The teeth were stored in 37C distilled water for 7 days and were then loaded under compressive strength using an Instron testing machine. The force required to fracture teeth were recorded and the data were analyzed statistically using ANOVA and Tukey HSD tests.
Results: Statistically significant differences were observed in fracture resistance between restored and non-restored samples. Comparisons between groups attributed significant effects to resin-modified glass ionomer in increasing fracture resistance of amalgam restored teeth (P<0.05). In most specimens, one cusp was separated from tooth structure whereas amalgam remained bonded to the intact cusp. Conclusion: According to these findings, resin-modified glass ionomer put a statistically significant effect in fracture resistance of amalgam-restored teeth.
Z. Dalili , A. Miandog ,
Volume 17, Issue 3 (8-2004)
Abstract
Statement of Problem: Considerable response to functional orthopedic appliances treatment in class II skeletal patients occurs during pubertal growth spurt. Therefore, it seems necessary to investigate indices indicating mandibular growth pattern. It has been proved that analyzing cervical vertebral maturation stage is a more valid index than that of hand wrist.
Purpose: The aim of this study was to evaluate the time status of functional orthopedic treatment in class II skeletal patients using CVMS index.
Materials and Methods: In this descriptive-inferential study, lateral cephalometric radiographs of 153 class II skeletal patients with mandibular deficiency, before treatment, were studied by an oral and maxillofacial radiologist using the index of cervical vertebral maturation stage (CVMS) and were categorized in three phases: CVMS I (desirable phase of treatment), CVMS II (ideal phase), and CVMS III (undesirable phase of treatment).
Results: Statistical analysis ranked the prevalence of treatment phases as: 41.8% in desirable phase (CVMS I), 28.1% in ideal phase (CVMA II) and 30% in undesirable phase (CVMS III). No significant differences were found between the three phases using Chi-square analysis. Time status of functional orthopedic treatment was also evaluated based on age and sex. The results showed significant differences between two sexes (P=0.032).
Conclusion: The present study suggests the analysis of CVMS index, along with clinical criteria, in the determination of an ideal time for functional orthopedic treatment to prevent patients’ exhaustion during treatment Period.
M. Memarian , R. Masoomi ,
Volume 17, Issue 4 (1-2005)
Abstract
Statement of Problem: Choosing an appropriate tooth for edentulous patients is a very important step in dentistry.
Purpose: This research has been done for determination of proper procedure for tooth selection in edentulous patients.
Methods and Materials: In this cross- sectional study 100 student and people who have come to a medical
center (range 20-30 years old) were collected randomly and the size of their anterior teeth were determined. A gauge with 0.01 mm accuracy and flexible plastic millimeter was used in order for measurement of anatomic landmark. For achieving the relation between the sizes of teeth statistical analysis was done.
Results: 50% of patients were female and the other 50% were male. We found a relationship between mesiodistal width of six maxillary anterior teeth and mesiodistal width of six mandibuMary teeth that can be shown as follow In men: six mandibular anterior teeth width= 0.S3 * width of six maxillary anterior teeth -2.008 In women: six mandibular anterior teeth width- 0.56 * width of six maxillary anterior teeth + 9.53 Also strong meaningful relationships between width of six anterior maxillary teeth and the width between corners of the lip in curve position have been noticed only in men which can be show' as follow:width of Six mandibular anterior tceth= 39.63 + 0.21+ the width between corners of lip in curve position for men
Conclusion: Although there are different ways for prediction of teeth size, it seems these findings can be
helpful in determining and prediction of it.
Mb. tavakoli , R. Tabarak , A. zargar ,
Volume 17, Issue 4 (1-2005)
Abstract
Statement of Problem: Zinc contained cements are so important among dental material as they have many indications and used in different ways therefore evaluation of their physical properties is so important in dentistry.
Purpose: The purpose of this research was to measure some physical properties of zinc-contained cements used in restorative dentistry. These cements included: Zinc oxide-eugenol, Zinc phosphate and Zinc polycarboxylate. Physical properties measured in this research were compressive strength, and setting time also Solubility & Disintegration were evaluated.
Materials and Methods: To perform this research two packs of each cement type were provided from an Iranian company products as prototypes and German HARVARD Dental GmbH company products as proof samples. For compressive strength 11 samples provided from any type of cement. For setting time test, 16 samples provided from Zinc oxide-eugenol and 11 samples from two other types. For solubility &
disintegration beet, 11 samples provided only from Zinc oxide-eugenol cement. The results compared with standard.
Results: The results of Iranian product showed that compressive strength of Zinc oxide-eugenol- is I2.58±3 MPa, of Zinc phosphate cement is 37.2I±5.0 MPa and of Zinc polycarboxylate cement is 35.86±2.1 MPa.Setting time of Zinc oxide-eugenol cement is 2 9.04 ±0.7 1 min, of Zinc phosphate cement is 5.41 ±0.55 min and of Zinc polycarboxylate cement is 2.5±0.6 min. Solubility & disintegration of Zinc oxide-eugenol cement is 8.44±i.l%. None of these findings are in standard limit.
Conclusion: By the use of standard charts it is concluded that: Only compressive strength of Zinc oxide-eugenol cement is between standard limits and compressive strengths of two other types of the cements are less than standard limits. Also only setting time -of Zincoxide eugenol cement is in standard limit and setting times of two other types of the cements aren't in standard limit. The German samples results were in standard limit. Solubility & disintegration-of Zinc-oxide eugenol cement isn't in standard limit. Therefore it is concluded that all types of these cements are not standard for use.
D. Goodarzi Pour , S. Ebrahimi Moghaddam ,
Volume 17, Issue 4 (1-2005)
Abstract
Statement of Problem: A few decades have past from using radiographic technology as an accurate paraclinical method and always protective measurements is applicated against ionizing radiation. As dental radiography is a routine procedure in dentistry the importance of protective strategies is clear.
Propose: The aim of this descriptive study is to evaluate the protection principles in centers which have intraoral radiographic devices in Yazd.
Material and Methods: We have considered all three aspects of practitioner, environment and patient protection using questionnaire and visiting those centers.
Results: 33/7% of dental offices ,10 clinics ,3 institution and faculty of dentistry had intraoral radiographic equipments. Stablishment of protection principles for radiographer was favorable. 7.7% of centers had x-ray room with leaded walls, 23.1% had curtain , in 69/2% of centers radiographers stood in correct position and distance while taking radiograph. Regarding to protection of environment, beams leakage control in 23.1% dental offices, 70% of clinics, all institution and faculty of dentistry have done.
Conclusion: Non of the centers used rectangular localizator, thyroid shield, film holder and just some centers used leaded apron in specific circumstances. We have concluded that patient protection constitute less consideration. Generally lack of protective consideration is related to deficient knowledge of operators. Lack of information about protection equipments causes decrease of demanding of these tools and ultimately lack of these equipments in the market.
Mh. Toodeh-Zaeim , H. Ravanmehr ,
Volume 17, Issue 4 (1-2005)
Abstract
Statement of Problem: The significance of adenoid tissue in Orthodontia appeared in 1954. At that time,even as today, orthodontists had an enduring interest in the relationship between excessive amounts of adenoid tissue, the developing occlusion, and facial morphology.
Purpose: The aim of this study was to evaluate effect of mouth breathing with adenoid enlargement on dentofacia! cephalometric measurements.
Material and Methods: A sample of 92 subjects between the ages of 6 and 15 years old were studied in two study and control groups. In study group, 46 mouth breathers (32 girls and 14 boys) with mean of 1 1.26 years old were examined by orthodontist and ENT specialist in order to confirmation of nasopharyngeal obstruction.Control group contained 46 nasal breathers (35 girls and 11 boys) with mean of 11.33 years old. For each patient in centric occlusion, a lateral cephalogram was taken and traced. 12 dentofacial variables were measured and statistical t-test was conducted by calculating the mean, standard deviation and p-value of parameters. Statistical t-test for mean oi~ dentofacial variables for the two groups revealed that some of variables were significantly different.
Results: In study group Z Go.Me-SN, Z Y-A.xis, Z Go, Z SN-PL variables were significantly higher than control group and Z HoFIl, Z SNB were significantly lower. The other dentofacial variables (ZS, IMPA,Z SNA, Z ANB. Z Ar and LH) didn't show any significant difference.
Conclusion: Adenoid enlargement and nasopharyngeal obstruction can affect dentofacial morphology and cause facial vertical growth pattern and upper centrals retrusion.
