Showing 384 results for Ion
Mostafa Ghandi, Babak Namvar, Sotodeh Davaie,
Volume 28, Issue 4 (1-2016)
Abstract
Background and Aims: As in fissure sealant therapy the tooth surface is mostly enamel, the use of an enamel bonding agent (hydrophobic bonding agent) may be more cost effective than that of newer generations of bonding (hydrophilic bonding agents). The aim of this study was to compare the retention and durability of fissure sealant therapy when applying an enamel bonding agent, a dentin bonding agent and no bonding agent during 4 years.
Materials and Methods: This study was done on the first permanent molars of the upper and lower jaws of 24 students of the first grade of a primary school (6-7 years old). On 36 teeth, a dentin bonding agent (Excite) was applied under the fissure sealant and on 36 teeth an enamel bonding agent (Margin bond) was applied under the fissure sealant. Then, 24 teeth were selected from these two groups and were compared with a group (including 24 teeth) with no bonding agent under the fissure sealant (as control group). All the fissures of the teeth were evaluated annually for 4 years to find out the presence or absence of fissure sealant substance. Data were analyzed using Wilcoxon test.
Results: From the statistical analysis, there was no significant difference in retention and durability of the fissure sealant substance comparing the group with dentin bonding agent (Excite) and the group with enamel bonding agent (Margin bond). Also, using a bonding agent made no significant difference (P>0.05).
Conclusion: According to the results of this study, using a bonding agent made no improvement in the retention and durability of fissure sealant substance.
Seyedeh Tahereh Mohtavipour, Somayeh Nemati, Alieh Sadat Javadzadeh Haghighat, Seyedeh Saeedeh Mohtavipour, Mina Sadadt Mirkhani,
Volume 28, Issue 4 (1-2016)
Abstract
Background and Aims: Elongation of styloid process may result in development of Eagle syndrome with associated symptoms. This study aimed to assess the frequency of elongated styloid process (ESP) and to evaluate its prevalence according to sex and age.
Materials and Methods: This study was conducted on digital panoramic radiographs of patients refered to the Oral Radiology Department of dental school, Guilan University of Medical Sciences. Styloid process length was measured and classified as elongated, pseudoarticulated, or segmented. Calcification patterns were determined as A, B, C, and D. ESP was defined as length > 30 mm. Data were analyzed by SPSS using T-test, Chi square, Pearson, and Spearman (P<0.05).
Results: A total of 505 digital panoramic radiographs taken from 227 males (45%) and 278 females (55%) aged 10 to 72 (40.1±12.9) years were evaluated. Elongated styloids were present in radiographs of 230 (45.5%) individuals. There was no significant difference in the ESP frequency between males (46.09%) and females (53.91%) (P=0.63). Type I and calcification B pattern showed more frequency than that of other categories.
Conclusion: According to these findings, elongated styloid process was a common condition among the studied population and had a significant correlation to the age.
Farnaz Farahat, Abdolrahim Davari, Motahare Amiri, Ebrahim Mokarizadeh,
Volume 28, Issue 4 (1-2016)
Abstract
Background and Aims: Dental erosion refers to the loss of tooth structure by being scratched chemically without bacterial involvement which needs to care about due to its prevalence and treatment problems. This study was designed with the aim of evaluation of the frequency of dental erosion and its causing factors in patients referring to yazd dental school in 2012-2013.
Materials and Methods: In this cross-sectional study, 400 patients referring to yazd dental school were randomly selected. All of their teeth were evaluated in three surfaces (buccal, lingual and occlusal). The BEWE score was used for classification the extent of damages. Also, patients were given a questionnaire that included patient demographic information and questions to investigate the causes of dental erosion. Data were analyzed using SPSS version 17 and Mann-Whiney, Fisher exact, and Chi-square tests.
Results: In this study, 138 men and 261 women were participated with the mean age of 33.26±10.83. 84 persons (21.1%) had erosion. There was a direct and significant relationship between the dental erosion and patient's age (P >0.001). Also, there was a direct relationship between the dental erosion and reflux and consumption of lemon and pickle, beverages, soft beer and juice (P>0.001).
Conclusion: Consumption of lemon and pickle, beverages, soft beer and juice increases the risk of erosion. Considering the prevalence of dental erosion in about 21% of patients, it is necessary to pay more attention to the knowledge of the causes of erosion and reduction strategies of it.
Hadi Ghasemi, Arezoo Ebnahmadi, Maryam Moezzyzadeh, Masoud Geramipour,
Volume 28, Issue 4 (1-2016)
Abstract
Background and Aims: Dental students’ evaluation of teachers’ educational activity is crucial for the improvement of dental school’s performance. The process of the evaluation needs a valid and reliable tool. This study aimed to produce and validate a questionnaire for the evaluation of dental school teachers by students.
Materials and Methods: A group of 15 teachers in the Shahid Beheshti dental school gave their opinions regarding the characteristics of an ideal teacher using nominal group technique. These characteristics together with characteristics gathered from similar studies made the base of a questionnaire which later underwent a validity and reliability assessment by means of the calculation of Content Validity Index (CVI), Content Validity Ratio (CVR), and Cronbach’s alpha coefficient.
Results: The preliminary questionnaire included 94 items in four categories naming: ethics, educational capability, practical capability, and managemet. After calculating CVR and CVI for each item, 23 items with CVR<0.33 and 20 items with CVI<0.79 have been excluded from the questionnaire leaving a questionnaire with 54 items. The overall reliability of this questionnaire using Chronbach’s alpha coefficient was 0.96.
Conclusion: Consulting an expert group that are familiar with different aspects of educational performance of faculty teachers, it was concluded that applying various methods for validity and reliability, and considering local culture values are useful for the preparation of the questionnaire for similar studies in Iran.
Abbas Majdabadi, Mona Ahadi, Reza Fekrazad,
Volume 29, Issue 1 (7-2016)
Abstract
Background and Aims: Nowadays lasers are used as alternatives to the tooth preparation because of reducing pain and bloodshed. The aim of this study was to observe the effect of ArF laser on the dental hard tissues.
Materials and Methods: For this research human molar teeth with no caries or dental restoration and enamel cracks were used. Irradiation laser energies were taken 95, 70 and 50 mJ for enamel and 80, 70 and 50 mJ for dentine. Then, for each of energy values pulse numbers (repetition rate) were adjusted at 200, 400, 600, 800, 1000 and 1500. Ablation was carried out without water spray on both enamel and dentine. Finally, the dimensions of ablated areas were measured by using a camera connected to the computer and results were applied in graphs.
Results: For each energy value, the ablation dimension increased by increasing pulse numbers. Ablation depth in dentine was more than that of for enamel. Trends of graphs for dentine and enamel were the same. SEM images of ablations by 95 mJ energy on enamel and 80 mJ energy on dentine showed sharp edges.
Conclusion: Ablation depths increased by increasing pulse numbers, for each energy level. However, this increase was not that as expected, because the lack of water spray while irradiating.
Nina Rahshenas, Mohammad Hasan Salari, Maryam Koukabi Salehi, Mahshad Mohebbi,
Volume 29, Issue 1 (7-2016)
Abstract
Background and Aims: Debonding at the cement-dentine interface is the main reason of failure in restoration of endodentically treated teeth with fiber posts. The aim of this study was to compare the effect of Starfill 2B danville and Panavia F2 kuraray cements on the retention of fiber posts to root canal dentin.
Materials and Methods: Twenty extracted mandibular premolar teeth which had single root canal were endodentically treated and decoronated. Teeth were randomly divided into 2 groups, (n=40). Fiber posts were cemented using 2 dual cure resin cements. Group A was cemented with Starfill 2B Danville and group B was cemented with Panavia F2 Kuraray. Each root was mounted in acrylic resin and then sliced in 2 parts. The retention strength of each specimen was determined using push-out test using a universal testing machine. Data was analyzed using T-test.
Results: The retentive strength for groups A and B were 48.16±12.11 and 61.44±9.16 MPa, respectively. There was significant difference in the retentive strength between group A and B (P<0.05).
Conclusion: It seems that type of cement had effect on the retention of fiber posts. Panavia F2 Kuraray resin cement significantly provided higher retention than that of Starfill 2B Danville cement.
Mohammad Javad Etesami, Seyyed Lotfollah Derakhshan, Kiomars Nazari Moghadam, Mohammad Ebrahimi Saravi,
Volume 29, Issue 1 (7-2016)
Abstract
Background and Aims: Cleaning and shaping is one of the most important stages in endodontic treatment. Single-file systems save time and reduce the risk of transmission of pathogens. This in vitro study was aimed to compare the rate of canal transportation after the preparation of the stimulated resin root canal with two single-file systems, namely Waveone and Reciproc.
Materials and Methods: Thirty stimulated resin root canal blocks with size 8/0. 02 K file were randomly divided into two study groups. The preparation in Group A and Group B was performed using Reciproc and Waveone files, respectively. Pre and post- preparation photographs were taken and the images were superimposed to evaluate the inner and outer wall’s curvature tendency at three points (apical, middle and coronal) using AutoCad pragram. Data were analyzed using T-test.
Results: Based on the results, the degree of transportation in the inner and outer walls of the canal was less at the level of 3 millimeters (P<0.001) and there was no significant difference between the two groups regarding the deviation at the levels of 1 and 5 millimeters (P>0.05).
Conclusion: Waveone showed better performance in the middle third of canal and this system maybe recommended.
Arash Zar Bakhsh, Ezzatollah Jalalian, Nilufar Rahimi, Shahrzad Sadr Haghighi,
Volume 29, Issue 1 (7-2016)
Abstract
Background and Aims: The zirconia coated FRC posts (Ice light) is the next generation of aesthetic posts , ice light features 70% fill of zirconia enriched, parallel glass fiber for exceptional strength. Its flexibility is close to dentine so stress is distributed. The aim of this study was to evaluate the effect of post type (FRC post and the zirconia coated FRC post) on the retention to the root canal wall.
Materials and Methods: 20 extracted human premolar teeth with 14 mm length were selected. After post space preparation, the teeth were randomly divided into two groups: Group1: the zirconia coated FRC post (Danville, USA) Group2: FRC post (RTD DT light post, France). All posts were cemented with a dual-cure resin cement (Panavia, Kuraray, Japan). All specimens were mount in acrylic cylinders, and the push-out test was done using a universal testing machine (Instron 5500 R, USA) at 1 mm/min speed. Data were analyzed using T-test.
Results: The retentive strengths were in coronal (75.27+14.81 MPa), in middle (64.38+15.29 MPa) and in apical (51.46+13.29 MPa) for the zirconia coated FRC post, and also were in Coronal (59.16+1.91 MPa), in middle (66.83+12.32 MPa) and in apical (67.88+17.47 MPa) for the FRC post. There was no significant difference in mean retentive strength between two groups in each region (P=0.07).
Conclusion: The FRC post and zirconia coated FRC post had similar retention to the root canal walls.
Sara Koosha, Masoomeh Kandi Bidgoli, Azadeh Raouf, Reza Ezatian,
Volume 29, Issue 2 (11-2016)
Abstract
Background and Aims: Constant dynamic and static activities are considered as the main cause of musculoskeletal problems among dentists. The aim of this study was to evaluate the musculoskeletal problems and related factors among dentists in specialized clinics and dental schools in Tehran in 2014 using the REBA method.
Materials and Methods: In this cross-sectional study, the dentists from clinics of dental schools in Tehran were selected as individual targets. Nordic anddemopghrphic questionnaire were completed through interview from dentists. In order to assess the musculoskeletal disorders, REBA method (Rapid Entire Body Assessment) was used. In this method, positions and postures of the dentists during their work was observed and recorded. Data was analyzed using Regression Logestic test.
Results: The obtained results showed that among 100 dentist, 6% were in the very high risk (15-11) for musculoskeletal problems and 17% and 25% were in high-risk (10-8) and average risk (7-4), respectively. Based on the findings from Nordic questionnaire, the most skeletal- muscle travail were related to the neck (60%), lumbar (58%) and rear (46%) consequently. It seemed that factors such as gender, body mass index (BMI), height, specialty, body posture during the work (standing or sitting), smoking and using the direct or indirect vision, had an impact on the musculoskeletal disorders.
Conclusion: Findings from the final scoring of REBA showed that a high percentage of dentists were struggling with skeletal- muscle problems and they were in moderate to high range of risk for these type of disorders.
Arghavan Kamali, Amene Taghdisi Kashani, Masume Hydarpoor,
Volume 29, Issue 2 (11-2016)
Abstract
Background and Aims: Trauma to the teeth is a common problem that occurs in children. Avulsion is the one of the most complex dental damages that if be untreated can cause multiple problems. Since many of dental traumas happen in school and school health teachers have main role in children treatments, the aim of this study was to evaluate the primary school health teachers’ knowledge regarding the emergency treatment of avulsed permanent teeth.
Materials and Methods: In this cross-sectional study, after consultation training of education, all of the health teachers of elementary schools in Hamadan were selected through census sampling method and were given the regulation questionnaire. After completing the questionnaire, information was collected using software SPSS19. The data was analyzed using Fisher Exact, Kolmogrov Smirnov test, Chi-square, One way, Levenes test and
T-test.
Results: 81 Health teachers were studied and the ratio of knowledge score of all of health teachers to a maximum knowledge score was obtained to be 43/1%. There was no significant relationship between the school health teacher knowledge and their work experiences and age (P=0.23-0.6), respectively. Average of knowledge score of who were educated was more than who were not educated previously (P<0.001).
Conclusion: Primary school health teachers' knowledge of dealing with Avulsion was not at a high level. Therefore, training on the dental trauma cases is quite essential for them.
Arash Mansourian, Shiva Shirazian, Mohammad Jalili, Mehdi Vatanpour, Leila Pour Momen Arabi,
Volume 29, Issue 3 (10-2016)
Abstract
Background and Aims: The objective of this study was the development of a checklist for assessment of students’ clinical skills in the clinical oral medicine. The second aim was the assessment of stake holders’ satisfaction of this checklist in comparison to the routine global rating method.
Materials and Methods: The checklist was developed in an expert panel sessions and the validity and reliability of checklist were assessed by CVI and test-retest method, respectively. All students (n=66) were assessed in 2 groups, one with developed checklist and another with global rating. At the end of the session, the satisfaction’s level of staff and students were analysized using Wilcoxon and Mann-Whitney test and the mean scores of students were analysized using Paired T test.
Results: Content validity index (CV I) of checklist was 0.88. Reliability of checklist confirmed with high correlation coefficient (0.9). Staffs’ satisfaction had no significant difference between the two methods
(Wilcoxon P=0.06). The mean score of students who assessed by checklist was higher than global rating with no significant differences (P=0.06).
Conclusion: Regarding the higher students’ satisfaction from checklist and more attention to component of assessment and more objectivity of this method and also higher score in checklist, it seems that the use of a checklist is more proper method for assessing the students’ clinical skills.
Samaneh Razeghi, Sara Ghadimi, Simin Zahra Mohebbi, Fatemeh Eghbalimoghaddam,
Volume 29, Issue 3 (10-2016)
Abstract
Background and Aims: One of the most effective methods in reducing the prevalence of caries is oral health education. The aim of this study was to evaluate of two educational interventions regarding prevention of early childhood caries on self-reported practice of parents of 2-5-year-old children receiving dental treatment under general anesthesia.
Materials and Methods: In this interventional study, the effects of two different educational interventions
(pamphlet and pamphlet along with reminder) on self-reported practice of parents of 2-5-years-old children receiving dental treatment under general anesthesia was assessed. Thirty seven couples of children and mothers in two groups were randomly selected. Before and three months after interventions, a standard questionnaire regarding self-reported practice of mothers on prevention of early childhood caries was completed by respondents. Moreover, oral examination including Simplified oral hygiene index (S-OHI), dmft, and white spot lesions were rerecorded at the beginning and three months after interventions. At this time in one of the groups reminder phone calls were made every month. Finally, the answers were scored and data were statistically analyzed to be compared in pre- and post-test.
Results: Comparing each of the groups before and after interventions showed that in both groups there were significant differences in mothers’ perception of perceived ability to make child brush his teeth twice a day (P=0.001), and child’s tooth brushing frequency more than once a day (P=0.03). S-OHI had no significant difference after the intervention between two groups. But each group had a significant decrease three months after intervention (P=0.003). Also the mean number of white spots showed a significant decrease before and after intervention in each groups. Regarding mothers’ self-reported practice no significant difference was observed between two groups (P>0.05).
Conclusion: Using pamphlets along with or without reminder as educational measures had similar enhancing effects on the mothers’ self-reported practice on oral health of children within three months.
Habibeh Farazdaghi, Mohammad Bagher Tavakoli, Shahab Etemadi, Arash Ghodousi,
Volume 29, Issue 3 (10-2016)
Abstract
Background and Aims: Gender determination is an important step in identification. For gender determination, anthropometric evaluation is one of the main forensic evaluations. The aim of this study was the assessment of sphenoid sinus volume in order to determine sexual identity, using multi-slice CT images.
Materials and Methods: For volumetric analysis, axial paranasal sinus CT scan with 3-mm slice thickness was used. For this study, 80 images (40 women and 40 men older than 18 years) were selected. For the assessment of sphenoid sinus volume, Digimizer software was used. The volume of sphenoid sinus was calculated using the following equation: v=∑ (area of each slice × thickness of each slice). Statistical analysis was performed by independent T-test.
Results: The mean volume of sphenoid sinus was significantly greater in male gender (P=0.01).The assessed Cut off point was 9/35 cm3, showing that 63.4% of volume assessments greater than cut off point was supposed to be male and 64.1% of volumetry lesser than cut off point were female.
Conclusion: According to the area under Roc curve (1.65%), sphenoid sinus volume is not an appropriate factor for differentiation of male and female from each other, which means the predictability of cut off point (9/35 cm3 ) is 65/1% close to reality.
Behrad Tanbakuchi, Sepideh Arab,
Volume 29, Issue 3 (10-2016)
Abstract
Background and Aims: The first permanent molar is susceptible to caries, endodontic complications and developmental anomalies. Compromised teeth with poor prognosis could cause the clinician to face dilemmas. The aim of this review article was to assess recent guidelines on the treatment planning of compromised first permanent molars in mixed dentition period.
Materials and Methods: The design of the study was based on review of literature by searching the MEDLINE, Web of science and Google scholar. Key words (permanent first molar, extraction, treatment plan) were used. This search was limited to the English articles published after the year 2000.
Conclusion: A number of factors influenced decision-making process regarding compromised first permanent molars including the restorative status of the tooth, dental age of the patient, degree of crowding and occlusal relationships were assessed. The ideal time for removal of these teeth was 8-9 years of age. However, the current evidence for managing compromised first permanent molars demands clinical trials.
Sayed Mohsen Hosseini, Fateme Bagheri, Faranak Farahmand, Asiye Heydari, Elahe Khorasani,
Volume 29, Issue 4 (1-2017)
Abstract
Background and Aims: Nowadays, oral cancer is considered one of the most important diseases related to oral health. The objective of the present study was to determine the dental students’ knowledge in Isfahan about oral cancer and the comparison of the level of students' knowledge in different years of education.
Materials and Methods: The present study was a cross-sectional-analytical one conducted in 2013. The population of study included the dental students of private and state University of Isfahan which 255 students were randomly selected. The data were collected using questionnaire and were then analyzed using SPSS software program and Kruskal-Wallis and Mann-Whitney.
Results: From private and public dental schools in Isfahan, 56% and 44% of dental students were involved. Regarding performing routine clinical oral examination, 81% of the participants answered positively, which showed no significant difference among the years of education of the participants (P=0.116). Regarding the examination of patients with oral lesions, 46% of them answered positively, which the difference between the years of education was highly significant (P≤0.001).
Conclusion: The findings of the research indicated that the level of knowledge of dental students of Isfahan city regarding the detection of oral lesions was not sufficient. Although, the students did not perform common examinations for exploring oral cancer, they did not have sufficient knowledge regarding some of the risk factors and oral lesions related to cancer. Therefore, it is necessary that a comprehensive curriculum be developed in this regard for their education.
Masumeh Hasani Tabatabaei, Sakineh Arami, Fatemeh Khajavi, Zohreh Moradi,
Volume 29, Issue 4 (1-2017)
Abstract
Background and Aims: Despite the reduction of incidence of dental caries in recent years, this disease is common and many efforts were conducted to decrease the prevalence of dental caries. On the other hand secondary caries lesions are the main reason for replacement of direct restorations. Therefore, the aim of the current study was to evaluate suitable methods of preparation and restorative materials to reduce caries recurrence.
Materials and Methods: In this experimental study, eighty human teeth were collected and stored in normal saline. The teeth were soft-tissue debrided and cleaned with water/pumice slurry and rubber cups in a low-speed handpiece. Speciments were randomly divided in two main groups. Cavities were prepared with diamond burs or Er:YAG laser (10 Hz, 300 mJ, 3W). Each group was divided into 4 sub-groups, and restored with a glass-ionomer cement (Fuji IX), resin modified glass-ionomer (Fuji II LC), total etch bonding + composite resin or self-etch bonding + composite resin. The specimens were submitted to pH cycling. Speciments were then sectioned, polished and Vickers microhardness measurements were performed on each specimen. Differences among the medians were analyzed using two way ANOVA test at a 95% confidence level and Tukey test.
Results: Statistical analysis showed significant difference in the type of substrate (enamel, dentin) in both main groups (P<0.0001) but no differences in the caries lesion development between the cavities restored with the same material and prepared with diamond burs or Er:YAG laser.
Conclusion: The Er:YAG laser used for cavity preparation and different types of restorative materials used did not show the ability to guarantee significantly more acid-resistance tooth structure against demineralization.
Somayeh Zeighami, Hakimeh Siadat, Marzieh Alikhasi, Zeinab Saeidi,
Volume 30, Issue 1 (6-2017)
Abstract
Background and Aims: Taking impression from angulated implants has always been a great challenge in clinic. In this regard, studies on sectional trays are very few. The aim of this study was to evaluate and compare the dimensional and angular accuracy of impressions using full arch and sectional trays.
Materials and Methods: Four implants (4.3 × 12 mm) (Implantium, Dentium) were placed in the first premolar and molar regions of a Kennedy class I mandibular acrylic model with 30° lingual angulation. Twenty open special trays (Full arch & Sectional) were made on the primary cast. The impressions were taken using vinyl polysiloxane (VPS) and were poured with type IV dental stone. The coordinate measuring machine (CMM) was used to measure the dimensional (Z, Y, X) and angular (θ) coordinates of implants. The data were analyzed using and t-test and SPSS 22. Software.
Results: The type of tray had no significant effect on the dimensional accuracy in X, Y and Z axes (P>0.05) and total linear displacement (r); However, it significantly affected the angular accuracy (∆q) (P<0.05).
Conclusion: Sectional tray yields less rotational displacement in impressions made of angulated implants.
Maryam Khoroushi, Mohammad Rabbani Khorasgani, Azam Aliasghari,
Volume 30, Issue 1 (6-2017)
Abstract
Background and Aims: Tooth decay has high prevalence in the world. The use of plant material for the prevention and treatment of this disease for various reasons is considered, due to the increasing resistance of bacteria to antibiotics, the high cost and adverse effects of some chemicals used in dentistry. This study was aimed to determine the antimicrobial effect of alcoholic extract of Pepper (Capsicum annuum) and eggplant skin and cap on the cariogenic streptococci.
Materials and Methods: In this study, the antimicrobial activity of ethanol extract of Capsicum annuum and eggplant skin and cap on the cariogenic streptococci, including Streptococcus mutans, Streptococcus sobrinus, and Streptococcus sanguis by microtitre plate method for MIC (Minimum Inhibitor Concentration) was performed. Data were analyzed by one-way analysis of variance using Prism 5 Graph Pad software.
Results: MIC for the Capsicum annuum and eggplant skin for Streptococcus mutans was 250 mg/ml (SD=0.052), and for the Streptococcus sobrinus and Streptococcus sanguis was 125 mg/ml (SD=0.027). The MIC for the cap eggplant for Streptococcus mutans and Streptococcus sobrinus was 500 mg/ml (SD=0) and for S. sanguis was getting 125 mg/ml (SD=0.159).
Conclusion: This study showed that the herbal extracts of Capsicum annuum and eggplant skin and cap had beneficially antimicrobial effects on all three strains of cariogenic streptococci.
Hakimeh Siadat, Amin Jabbari, Mohammad Taghi Baghani, Marzieh Alikhasi,
Volume 30, Issue 1 (6-2017)
Abstract
Background and Aims: The exact placement of impression copings in making accurate prosthesis is very important. In some cases, the implants need to be placed deeply subgingival, which could reduce the direct vision and ultimately reduce the precision of impression copings and subsequently, delivered prosthesis. This would be the cause of multiple complications such as delivery of ill-fitting prosthesis. The aim of this study was to evaluate the effect of the dental implant placement depth on the accuracy of impression coping connection by students.
Materials and Methods: This in-vitro and experimental study was conducted by 50 senior dental students. Four implants at different depths (0, 2, 4 and 6 mm) were placed in a model. After learning how to mount impression coping on implants, the students were asked to mount impression copings on all four implants. The samples were examined by an experienced prosthodontist using a magnifier with 4x magnification. Data were analyzed by statistical Cochran test (P<0.05(.
Results: The proper adapting rate of transfer copings, in subgingival implants with the depth of 0, 2, 4 and 6 mm were 100%, 62%, 58% and 20%, respectively. Statistically significant differences were observed between all groups (P<0.001).
Conclusion: The results showed that there was an inverse relationship between the increasing depth of the implants in the gingiva and the dentist’s ability to connect the impression copings properly.
Abbas Rahimi Foroushani, Nooshin Akbari Sharak, Mohamad Javad Kharazi Fard,
Volume 30, Issue 2 (8-2017)
Abstract
Background and Aims: In recent years, dental implants have received special attention in dentistry. Due to the remarkable success of predictable dental implants, there is growing interests in the scientific community from descriptions of implant success toward identify factors associated with implant failure. The purpose of this study was to identify the risk factors associated with implant failure in an objective and statistically valid manner.
Materials and Methods: To address the research purposes, we used a cohort study in which a total of 2368 implants were placed on 1011 patient in the Clinic of Tehran University of Medical Sciences. The predictor variables included demographic variables, the health status and variables are related to implants. The outcome variable of interest was implant failure. The overall implant survival was estimated using the Kaplan-Meier analysis. First, risk factors were identified using Chi-square test and Fisher's exact test and then the Cox proportional hazard regression models were used for more analysis.
Results: The overall 39 month implant survival using the Kaplan-Meier function was 0.99±0.002. The implant location (jaws) (P=0.049) and type of teeth (P=0.011) were found to have significant relation with failure times in Cox proportional hazard model.
Conclusion: According to result of this study, both implant location and type of teeth had effection the failure times so that, the survival in mandible was higher than maxilla. The failure rate was higher in anterior teeth than that of others (molar, premolar, canine and primary).
