JOURNAL OF ISLAMIC DENTAL ASSOCIATION OF IRAN (MAJALLAH-I-DANDANPIZISHKI)
Year:2005 | Volume:17 | Issue:1 (53)|Papers Count:17

Background and Aim: Compound is one of the oldest impression materials that is nowadays widely used. The flow of compound is one of the most important physical properties for impression. The aim of this study was to evaluate the flow of an Iranian made compound (Pishro) according to ADA standards and to compare with Kerr, Kemdent and Harvard compounds.Materials and Methods: According to ADA, two samples of each compound with the diameter of 10mm and the height of 6mm were prepared. The specimens were put in 37°C and 45°C at 2kg pressure in hot water bath. Changes were measured by a micrometer. Based on the percentage of changes to the original length, the compound flow in a special temperature was taken and compared with standard criteria. The data were analyzed using one-way and two way ANOVA.Results: The flow Kerr compound in 37°C was according to BS 3880 standard but didn't meet ADA standard. The three others were in the standard range (P<0.05). In 45°C, the flow of the Kerr compound was according to ADA standard and the three others had less flow than standard requirements. It should be noted that Pishro compound was the weakest.(P<0.05)Conclusion: In 37°C the silane percentage of Kerr stance does not correspond with ADA standards, however; in 45°C the silane percentages of Kerr, Kemdent, Harvard approximate to that of standard sequentially but Pishro stance is the weakest one and its percentage is far from that of standard.

Background and Aim: Signs and symptoms of cervical degenerative changes are very common among dentists resulting in repeated medical care. The incorrect position of the cervical spine during dental work, avoidance doing exercises and left , hand dominance can increase the risk of this problem. The aim of this study was to evaluate the prevalence of the signs and symptoms of degenerative changes among dentists, doctors and common people.Materials and Methods: In this cross-sectional study, totally 465 samples including 251dentists (General and Specialist) from three provinces of Shahrekord, Esfahan and Tehran, 17dentists from ULB University of Belgium, 101 physicians (General & specialist) and 96 persons from other jobs were studied. All the information were analyzed using SPSS program and χ2  tests.Results: Among Iranian dentists, 155 were male and 96 were female. Cervical pains that cause the patient to stay at home, take medication or use cervical collar were 66.9%. In other groups the results were as follows: foreigner dentists): 52.9%, physicians: 23.8%, other jobs: 24%. 1.6% of the dentists were candidate for cervical region operation and 0.08% of them were operated because of cervical discopathy. The signs and symptoms were 72% for left handed dentists. In the first 1-4 years of professional life the signs and symptoms were 32% and in the next ten years it was 72%.Conclusions: Routine sports, facilities for left-hand dentists and correct position during dental work can decrease the risk of degenerative changes of cervical spine.

Background and Aim: One of the most important factors in the treatment of C1 II Div I malocclusions by functional appliances is the clinical examination of patient profile after forward positioning of mandible. So determining morphological changes of chin, after functional therapy, plays an important role in the prediction of facial profile. The aim of this study was to evaluate the morphological changes of mandibular symphysis after treatment by Farmand (Fa2) functional appliance in C1 II Div I malocclusions.Materials and Methods: In this before-after clinical trial, based on a similar study, 18 female patients, aged 10-12 years, with C1 II Div I malocclusion were investigated. These samples were under treatment for 12 months. Some angular & linear variables and Ricketts analysis were used to evaluate changes in geometric position of chin. Nanda and Aki analysis were utilized to determine morphological changes of symphysis. Paired - t test was used to compare the amount of differences of mean value pre and post treatment.Results: The findings observed following therapy were as follows;1. Depth of symphysis was increased (P= 0.01).2. Lower anterior facial height increased significantly (p< 0.005).3. Facial angle increased during treatment (P= 0.04).4. Increase in the mandibular symphysis contour was significant that could be due to forward movement of pogonion point (P= 0.002).5. Forward and downward movement of symphysis was frequently observed among patients.Conclusion: Following treatment by (Fa2) functional appliance, correction of profile is not only because of forward growth of mandible but also the remodeling of anterior chin contour. This type of treatment leads to better results in patients with normal and or low facial height due to an increase in lower anterior facial height.

Background and Aim: Wear is one of the main problems of acrylic teeth that creates a lot of problems for both patient and dentist. The aim of this research was to compare the amount of wear between two types of Iranian artificial teeth with Ivoclar teeth.Materials and Methods: In this study, the amount of wear between super brelian teeth was compared with Ivcolar teeth. Five denture teeth of each sample were selected. All tests were performed using porcelain abrader. The weight reduction of each sample was measured after 5000 and 10000 cycles with help of a digital balance. Then, average of weight decrease compared using ANOVA test.Result: The mean wear for super brelian did not show any significant difference with Ivcolar for 5000 cycles (P=0.9) and 10000 cycles (P=0.6). No significant difference was also found between the mean wear of Ivoclar and brelian (P=0.7). On the other hand, the mean wear of brelian showed significant difference to Ivoclar for 10000 cycles (P=0.03) it should be noted that there was not any significant difference between the average wear of two Iranian teeth (P=0.8)Conclusion: The result of this study indicated that the amount of teeth wear in super brelian type was to an acceptable extent near Ivoclar teeth.

Background and Aim: Having knowledge about the exact time and sequence of primary teeth eruption for dentists and especially pedodontists, to design an appropriate treatment plan is essential. The aim of this study was to determine the rime and sequence of primary teeth eruption among children residing in Tehran from birth (2000 - 2002).Materials and Methods: To achieve true statistics of time and sequence of primary teeth eruption, 542 newborn children, whose parents had lived for at least three years in Tehran, were selected randomly from five areas in Tehran. During more than two and half years follow-up,785 of them continued their co-operation. In this descriptive longitudinal cohort study, statistical analysis was performed using t-test at P<0.05 level of significance.Results: The time of tooth eruption, in right and left sides of both jaws, were similar. Mandibular central incisors and second molars, in both sexes, erupted faster than the same teeth in maxilla. The average duration of eruption, in both sexes, did not have any significant difference. Time and sequence of eruption of primary teeth in month were as follows:1- Mandibullar central incisors (7.88) with S.D (2.4)2- Maxillary central incisors (9.53) with S.D (2.26)3- Maxillary central incisors (11.52) with S.D (3.25)4- Maxillary central incisors (12.70) with S.D (3.42)5- Maxillary first molars (15.72) with S.D (2.94)6- Maxillary first molars (16.12) with S.D (2.85)7- Maxillary canines (18.25) with S.D (3.12)8- Maxillary canines (18.80) with S.D (3.42)9- Maxillary second molars (24.74) with S.D (3.59)10- Maxillary second molars(24.82) with S.D (3.47)The average time of maxillary central incisors and mandibular right incisor eruption was significantly earlier in boys than girls(P< 0.05).Conclusion: There is not any difference in the eruption of teeth quadrant, mandibular central incisors and second molars erupt faster than those in maxilla. No difference was found in the mean duration of eruption.

Background and Aim: Centric interference is a premature contact that happens during mandible closing, while condyles are in good position, causing mandible deviation to back, forward and lateral. Centric interference results in destructive effects on periodontal and pulpal tissues, temporomandibular joint, occlusion, jaws and masticatory system. The aim of this study was to evaluate the prevalence of occlusal disturbances in CR in posterior crowns.Materials and Methods: In a descriptive and cross-sectional study on 42 patients referring to Faculty of Dentistry, Tehran Islamic Azad University, 105 posterior crowns were evaluated for existing occlusion interference condition in CR.Results: Out of 105 crowns, 68 of them (64.7%) had contact in CR and 37 of them (35.2%) had no contact in Cr. Out of 68 posterior crowns with contact in CR, 19 of them (18.1%) had interference. There was no significant difference between posterior crowns regarding occlusal interferences (P<0.05).Conclusion: Considering the fact that occlusal interferences in crowns and metallic restorations are more destructive that those exist in natural dentition, it is recommended to pay more attention in the establishment of a correct occlusion in crowns and metallic restorations. 

Background and Aim: Children born with lip and palate clefts encounter their parents with severe concerns. Such patients are generally affected with dental and occlusal anomalies. The aim of this study was to investigate dental anomalies in children with oral clefts.Materials and Methods: In this case series study, 40 patients, age ranging from 1.5-21 years, with lip and palate clefts were examined. Statistical data were collected during six months in Mashhad and analyzed by SPSS software at 95% level of confidence.Results: Lateral incisor missing (24.7%) and maxillary incisor rotation (24.7%) were the most common findings. Supernumerary lateral incisor was the rarest finding (1%) at the cleft side.Conclusion: Considering that clefts are one of the highly prevalent structural birth defects and require complicated treatments, parental education, regular dental and medical visits can facilitate treatment plan.

Background and Aim: Full veneer crowns are frequently used for damaged teeth restorations.The function and durability of full veneer crowns are affected by retention. Retention depends on several factors such as convergence angle of the prepared teeth, type of cement, casting frame and so on. The aim of this study was to evaluate the effects of axial walls convergence on the retention of full veneer crowns.Materials and Methods: In this experimental study, 69 brass models with 6°, 12° and 20° convergence angles were made. The length of all models was 7mm with diameter of 6mm. Full metal crowns were made and cemented on these models. Then the crowns were detached from dies using an instron testing machine. The applied forced were recorded and data were subjected to ANOVA and Duncan tests for statistical analysis.Results: There were significant differences in the retention of the three different angles of convergence (P<0.0005). The retention decreased to almost one fourth from 6° to 20°. There was also a reverse correlation between the convergence angle and retention.Conclusion: The development of optimal convergence for maximum retention of full veneer crowns in the mouth is difficult, on the other hand convergence is a necessity for work facilitation. Therefore, the development of convergence should be conducted according to its effects on retention and other influencing factors

Background and Aim: Temporomandibular disorder is a broad term referring to jaws dysfunction. Investigators have presented several factors for the etiology of TMD (temporomandibular disorder), one of them is malocclusion. Balancing premature contacts are also recognized as a type of malocclusion. Therefore, the aim of this research was to determine the relation between balancing premature contacts and TMD. Secondary objectives as parafunctional habits and type of occlusion were also investigated.Materials and Methods: Sixty patients, 55 females and 5 males, referred to TMD ward, Faculty of Dentistry, Tehran University of Medical Sciences were selected. All samples had TMD signs and symptoms (TMJ) pain, joint malfunction, pain and malfunction of masticatory muscles.On the other hand, 60 patients, referred to oral diseases diagnosis department, without any problems were selected as controls. All patients were at the age range of 20-40 years old. Following complete examination and filling a questionnaire by all patients, data were analyzed by χ2.Results: There was no significant relationship between TMD and balancing interferences. Parafunctional habits in TMD patients was more prevalent comparing to the controls. No significant relation was found between TMD and type of occlusion. Crossbite and overjet more than 4mm were more prevalent among TMD patients.Conclusion: The most common factors influencing TMD are increased overjet and crossbite

Background and Aim: It is believed that a period of healing, approximately 3-4 months for mandible and 4-6 months for maxilla, are required to ensure osseointegration. Recently, a new method called Immediate loading of implants have been proposed. This method provides improved stability of the implant by the immediate support of an iterim prosthesis. The aim of this study was to evaluate the success rate of the Immediate loading single OPILS dental implants.Materials and Methods: Thirty-nine patients, including 26 females and 13 males, at the minimum age of 18 and maximum age of 54 years old, received 48 OPILS dental implants. In this prospective study, all samples were non-smoking, without any systemic disease or psychological problem. In all cases, and acrylic prefabricated crown was placed immediately after implant surgery. The definitive metal-ceramic crown was placed 2.5 months later in mandible and 5.5 months later in maxillae. Lack of pain, pus, implant immobility and less than 1mm bone loss were criteria of success.Results: The oral hygiene of females were better than males, 26 women had plaque index (0) and 11 of them had plaque index (1) where as out of 13 male subjects, 4 had plaque index (0), 6 had plaque index (2) and (3) had plaque index (3). The mean vertical bone loss, on mesial and distal parts, were less than 1mm, with the min. of 0 and max. of 0.4mm and the average of 0.2mm. All implants pass the defined criteria of success.Conclusion: On the basis of this short-term study, in single tooth cases, OPILS implants of Neo-Dent system can be loaded immediately.

Background and Aim: Various surgical techniques have been already proposed for the coverage of denuded root surfaces. The aim of this study was to compare coronally repositioned flap procedure with and without the use of EDTA gel in the treatment of recession defects.Materials and Methods: This study was a clinical test of 3 months duration conducted as a split-mouth and randomized design. Twenty-five patients, aged 17-60 years, with one paired buccal recession defects of at least 2mm depth participated. Surgical recession coverage was performed as coronally- advanced flap technique at both sites in the same session. One site was additionally treated with EDTA gel (24%, PH=7) (test group n=25). Clinical measurements including assessments of oral hygiene, recession depth (RD), recession width (RW), height of keratinized tissue (HKT), probing depth (PD), probing attachment level (PAL) and photographs were taken before and 1, 2 and 3 months after surgical treatment. Data were analyzed using t-student test, paired t-test and ANOVA.Results: Three months after therapy, both treatment modalities showed significant root coverage and probing attachment gain. Gingival recession decreased from 2.73mm to 0.53mm for the EDTA treated sites and from 2.39mm to 0.79mm for the control sites, corresponding to mean root coverage of 79% and 68%, respectively. This difference was not statistically significant (P=0.13) with the exception of probing attachment level which was significantly higher (P=0.004) in the EDTA group, all other clinical variables were not different between compared groups. Conclusion: It is suggested that the additional use of EDTA combined with coronally advanced flap technique for recession coverage results in the difference in the overall clinical outcome.

Background and Aim: Full blockage of the root canal space along with the formation of and ideal seal in the apical foramen at cemento dentinal junction (cdj) area with a neutral material compatible with the biological conditions of the area and stable in volume are the main goals of endodontic treatments. The aim of the present study was to investigate and compare tissue reactions to different types of gutta percha, mostly used in Iran.Materials and Methods: The studied gutta perchas were produced by Aria Dent, Dia Dent, Roeko and Saylastic (as the negative control group) factories. Each cone of gutta percha was divided into two apical and coronal pieces and sterilized by DV radiation. The apical piece was used for the implant and the coronal piece for sterilization control Saylastic cones were also divided into 5mm pieces for implant. These materials were implanted in the subcutaneous connective tissue, at the back of 40 male rats, using the injection technique. The animals were sacrificed in the periods of 4 to 60 days and approximately 160 sections were obtained for histological study. Data were analyzed through χ2 ,Fisher-exact and Kruskal-Wallis tests.Results: Chronic inflammatory responses were not observed, in long-term period, around the sections. The used gutta perchas were not toxic and tissue-irrigating.Conclusion: The results showed that none of the used gutta perchas were permanently tissue-irrigating and were borne properly by the tissue. No significant differences were found between the Iranian and the foreign types in this regard.

Background and Aim: Proper restoration of root canal treated teeth have been one of the controversial subjects in restorative dentistry. Such teeth, due to caries and extensive restoration, loss of marginal ridges and preparation of access cavity, have lost most of coronal structure so intra coronal extension (post) is necessary for the achievement of an adequate retention.The goal of this study was to evaluate stress distribution in root canal treated teeth, restored with post and crown.Materials and Methods: In this study, three dimensional finite element was used for stress analysis. Mandibular second premolar was used for modeling and restored by post and crown and a gold casting. The sample was loaded by 300N force at two different angles (45°, 90°).Software was used to compare the tensile, compressive and vonmiss stresses and the results were shown graphically.  Results: The most degree of stress was observed in cervical region. The amount of stress in oblique load and vertical load were 110.5Mpa and 38Mpa, respectively. Conclusion: The most amount of stress was observed in cervical region. The stress induced by oblique load, in each model, was greater than vertical load.

Background and Aim: Considering the high prevalence of hepatitis B infection among dentists and since hepatitis B is one of the most dangerous infections for dentists, the aim of this study was to determine HBSAB titer values of dental students, residents and faculty members of Tehran University of Medical Sciences, Dentistry School.Materials and Methods: This descriptive-analytic study was conducted on 107 samples, out of them 57 were female and 50 were male. That were randomly and systemically selected and their anti-body (Ab) titer was measured. None of the studied group had a history of hepatitis B infection or any other systemic disease of dental students 31(57.4%) were female and 23 (46.6%) were male. Of residents 18(69.2%) were female and 8(30.8%) were male. Of board members 19 (70.4) were male and 8(29.6%) were female.Results: The findings of frequency distribution of Ab titre showed that 86.9% had Ab titre more than 100 iu/1.  7.5% had Ab titre between 10 and 100 iu/1 and 5.6% had Ab titre less than l0iu/l. The least amount of Ab was reported 5 units and the greatest amount was 1020 units. The mean and standard deviation for Ab titre was 597.5094±398. χ2 test showed no significant relationship between Ab titre and background variables (P>0.5). Conclusion: It should be stated that 11.1% of faculty members need a second course of vaccination, all belong to the male group. Also 7.7% of residents and 1.8% of students need to be vaccinated again, most of them wee male. Of the whole faculty, 5.5% need to be vaccinated again.

Background and Aim: Academic success of Dentistry students is and important issue in dental education, its ignorance will lead to a decrease of scientific level among future dentists. The aim of this study was to evaluate the effects of dental students' occupation on their academic success.Materials and Methods: This descriptive-analytic study was performed on the students of Faculty of Dentistry, Tehran University of Medical Sciences in the academic year of 2004. All the students who had entered dental school in the September of 1998, 1999 and 2000 were given a questionnaire. Out of 200 investigated students, 83 of them were employed during school years. The gained average score was considered as a criteria for the students' academic success. Data were subjected to t-test, ANOVA and Pearson's regression analysis, at the significance level of P>0.05.Results: Employment, either related or unrelated to dentistry, had significant negative effects on educational success (P=0.0001).According to this study females versus males, singles versus married students and younger students versus older ones had better educational performance. Conclusion: Based on these results, paying attention to economic issues and providing welfare for students seems necessary for their academic success.