JOURNAL OF ISLAMIC DENTAL ASSOCIATION OF IRAN (MAJALLAH-I-DANDANPIZISHKI)
Year:2006 | Volume:17 | Issue:4 (57)|Papers Count:16

Background and Aim: Controversy about root canal obturation dates back to many years ago and different theories have always been suggested to justify various methods. The aim of this study was to evaluate the effects of canal obturation on the repair of periapical lesions in dogs and also the possibility of healing without obturation. Materials and Methods: In this interventional study, the pulps of 56 canals in 28 teeth of 7 mixed German shepherd dogs were infected through 6 weeks exposure to oral environment. All canals were prepared based on conventional root canal therapy. Canals of control group were filled with gutta percha and AH26 sealer. The test group canals were left unfilled. Then the coronal portion of all teeth was filled with amalgam and a fourth generation dentin bonding agent (Scotch bond multi purpose 3M Company). Six months later the dogs were sacrificed by vital perfusion method. Then the experimental roots and surrounding apical tissues were prepared and radiographs were taken. The histological sections were also prepared and examined. Data were subjected to Wilcoxon and McNemar statistical tests. Results: Cementum and dentin resorption variables showed significant differences between test and control groups (P.V<0.05). Other variables did not reveal significant differences in both groups. (P.V>0.05) Conclusion: It seems that the presence or absence of healing of the periapical lesions in dogs after 6 months is not related to canal obturation.

Background and Aim: One of the epidemic side - effects of wearing denture is chronic atrophic candidosis. The aim of this study was to determine the relative frequency of chronic atrophic candidosis in denture wearing patients referred to dentists in Yasouj (2003).Materials and Methods: In this descriptive cross - sectional study, 85 patients with denture referred to Yasouj dentists were examined and information about age, sex, duration of denture wearing at nights, on days and in years, smoking and denture hygiene were recorded. Then each patient's culture and smear was collected. Data were analyzed statistically using Chi - square test and SPSS software.Results: Out of total examined patients, 57.6% had positively cultural results. - In all age groups most of samples had positive results and there was not significant relationship between age and candidosis prevalence (P>0.05).- 59.6% of males and 54.5% of females had positive results. The difference was not statistically significant (P>0.05).- More than half of the samples wearing dentures over 10 years, showed positive results revealing no significant relationship between denture wearing and prevalence of candidosis (P>0.05).- 71.2% of subjects wearing dentures for 24 - hour had statistically significant positive results (P<0.05).- 77.7% of smoking subjects and 42.8% of non – smoking ones showed positive results. The difference was statistically significant (P<0.05).- 89.6% of patients with poor denture hygiene displayed significantly positive cultural results (P<0.05).Conclusion: The prevalence of candidosis among denture wearing patients was 57.6%. There was not statistically significant relationship between age, sex and years of wearing denture with the prevalence of candidosis, however; significant relationship was found between duration of denture wearing during day and night, denture hygiene and smoking with the prevalence of candidosis.

Background and Aim: Advantages in the use of saliva (easy access and non – invasive collection) have caused it to be a unique fluid as a diagnostic medium during recent years. The aim of this study was to determine and compare the stimulated and unstimulated whole saliva biochemical compositions in healthy female dental students of Tehran University of Medical Sciences living in dormitories.Materials and Methods: In a case series study 5ml of stimulated and unstimulated whole saliva samples were obtained from expectations of female students with a mean age of 22 (19-24) years in May and June 2005. Sodium concentration was measured by Flame - photometry method and other saliva compositions were measured by spectrophotometer and related kits as follows: total protein by the Biuret method, Ca++ by Arsenazo reaction and magnesium by the Xylidyle blue complex method. Data were analyzed for mean, standard deviation (SD) and standard error of measurement (SEM) using SPSS program. Student's unpaired t - test was used to compare stimulated and unstimulated saliva compositions.Results: In the unstimulated whole saliva (n=20), the concentrations (mean±SD) of total protein (mg/ml), magnesium (mmol/l), calcium (mmol/l) and sodium (mmol/l) were 6.19±2.80, 1.19±0.44, 1.90±0.70, 13.95±2.01, respectively. In the stimulated whole saliva (n=20), these values were 3.73±1.97, 1.75±0.60, 2.03±0.76 and 18.15±4.31 respectively.Conclusion: No statistically significant difference was found in calcium values between the stimulated and unstimulated whole saliva where as in stimulated saliva sodium and magnesium levels were significantly higher and total protein level were lower than unstimulated saliva.

Background and Aim: Coronal sealing plays an important role in the prevention of root canal system reinfection and the access of irritants to periradicular tissues. The aim of this experimental (in - vitro) study was to evaluate the effects of dentin bonding agents in the reduction of coronal microleakage and improvement of root canal seal.Materials and Methods: In this experimental study, twenty four extracted straight single rooted human teeth were randomly divided into two groups of ten. In the first group, after DBA application, root canals were filled with gutta percha and AH26 using lateral condensation technique. In the second group, root canals were only filled with gutta - percha and AH26. Two groups were also considered, as positive and negative controls. In positive control group, the root canals were filled with gutta - percha only. Then all teeth surfaces except the cut coronal surface were covered with two layers of nail varnish. In negative control group all surfaces were covered with two layers of nail varnish. The specimens were immersed in methylen blue dye (PH=7) for 48 hours. After rinsing the teeth and removal of nail varnish, the specimens were divided into buccal and lingual halves using diamond disk. The amount of linear penetration of dye was measured with stereomicroscope. Data were subjected to t - student test.Results: The mean of dye penetration was 3.2±1.217mm in the first group (DBA + gutta percha + AH26) and in the second group (gutta percha + AH26) was 6.1 mm. The difference between two groups was statistically significant (P<0.001). In positive control group dye penetrated in the entire length of canal, however; in the negative control group dye penetration was not observed.Conclusion: The use of D.B.A with gutta percha and AH26 using lateral condensation technique is effective in the reduction if coronal leakage.  

Background and Aim: Resin bonded restorations are preferred to the conventional ones due to their potential prevention of the unwanted tooth structure destruction, however; the rate of success depends on different factors such as: resin cements and metal surface treatment. The aim of this study was to compare the amount of microleakage between two methods of metal surface treatments and three kinds of resin cements.Materials and Methods: In this experimental study, 96 disks were cast with Cr-Co alloy and machined to 15mm diameter and 2 mm thickness with a handle in the center by an engineering lathe. Half of the samples were sandblasted with 50  mm Aluminium oxide at 7 bars of air pressure. The other half were firstly sandblasted and degazed. Then one layer of slurry opaque (1 gr of opaque porcelain powder plus 0.5 ml of distilled water) was applied on their surfaces. Disks in opaque and sandblast groups were divided randomly into two equal groups of case and control. Each group was divided into 3 groups of 8 each. In each group, the disks were mounted on a surveyor two by two against each other and cemented by a load of 20 N using one of these 3 resin cements: Panavia 21, All - bond 2 and Enforce. All samples of case group were thermocycled 2000 times (temperature between 5°C - 55°C) and then cyclic loading was applied with a force of 100 N for 112000 times at 1.5 Hz frequency. All samples were then immersed in a 0.5% basic fushin solution for 24 hours. Then were separated and scanned. Colored surface of each image of disks surfaces was calculated by Auto-CAD. Data were subjected to one - way ANOVA and Post Hoc test of Scheffe type. Results: All samples of Panavia 21+opaque (case) were failed during cyclic loading. The group of Panavia 21+opaque (control) showed the highest microleakage (10.27±11.25) and the difference between this group and the other ones was highly significant (P<0.001). Enforce+opaque (case) group showed microleakage (4.390±6.91) and the difference between this group and other groups was significant was found between other groups.Conclusion: The application of Panavia 21 and Enforce with slurry opaque porcelain as a metal surface treatment is not recommended.

Background and Aim: Superelasticity refers to the same amount of force exerted by an ideal archwire independent of the degree of activation. Clinical findings show that in most of situations these materials do not fulfill the expected properties. The aim of this study was to evaluate the bending properties of some of these archwires.Materials and Methods: In this experimental research eight specimens of each of the round wires with 0.14, 0.16 and 0.018 inch sizes of force I, rematitan lite and superelastic G & H types were tested. These wires were subjected to a three point bending test by DARTEC machine. Data were tested by ANOVA and Duncan tests at 0.05 level of significance. Results: All of these materials showed superelastic properties or at least superelastic tendencies. More pronounced superelastic properties were observed in thicker wires. However, their force level of plateau for 0.014 inch rematitan lite wires the end of the plateau was observed when the wire was displaced at least 0.6 mm.Conclusion: In all of these wires, the force level of plateau was higher than the optimal force required for tipping movements.

Background and Aim: Compomers are placed between composite resins and glass ionomers cements regarding their surface and mechanical properties. Compoglass is a trademark of compomers that is bonded to tooth surface using Syntac single component. The aim of this study was to investigate the effects of tooth surface conditioning on fracture resistance of compoglass restorations prior to Syntac agent application.Materials and Methods: In an experimental study, thirty intact maxillary premolar teeth were chosen and divided into three groups of ten each. MOD cavities were prepared and restored with compoglass as follows: Group 1: Restoring the teeth without conditioning the cavity surfaces prior to Syntac application.Group 2: Conditioning the cavity surfaces with phosphoric acid prior to Syntac application.Group 3: Conditioning the cavity surfaces with polyacrylic acid prior to Syntac application. All the samples were tested under compressive loading and the findings were statistically analyzed using ANOVA test.Results: The mean values obtained from groups 1, 2 and 3 were 1585.70, 1465.20 and 1535.60, respectively. No statistically significant differences were found in fracture resistance between tested groups.Conclusion: Conditioning tooth surfaces with phosphoric acid and polyacrylic acid prior to Syntac application had no effect on increasing the fracture resistance of compoglass restored teeth.

Background and Aim: Different surgical techniques have been proposed for crown exposure among patients under orthodontic treatment. The aim of this study was to investigate periodontal indices in closed flap operation technique used for impacted teeth crown exposure.Materials and Methods: In this descriptive study (2001-2003) 20 patients (15 females and 5 males), age ranging from 15 to 20 years, were participated. Following the performance of closed flap operation technique, in 12 patients impacted canine and central incisors were exposed and treated orthodontically. Periodontal parameters including sulcular depth, width of keratinized gingiva and attachment loss were recorded. Results: The mean of gingival sulcus depth was 1.50±0.43, the means of keratinized gingival in central incisors and canines were 3.07±0.53 and 2.30±0.42, respectively. In one patient, attachment loss was reported.Conclusion: Considering the optimal sulcular depth and keratinized gingiva, the closed flap operation technique seems suitable.

Background and Aim: When a complete denture is replaced with an overdenture supported by implant, masticatory efficiency will be improved. There are a lot of controversies on the use of the best attachments in overdentures. The aim of this study was to compare the stresses transferred to the implant supported overdentures in mandible with bar, ball and zaag attachments using photoelastic technique.Materials and Methods: In this descriptive in - vitro study, stresses transferred to the implants supported over dentures with bar, ball and zaag attachments were analyzed using photoelastic method. Two implants were installed in the canine area 8 mm from the midline. Vertical and oblique loads of 30Thwere applied to the first molar unilaterally. Resultant stress distribution with ball, bar and zaag attachments were evaluated.Results: The bar attachments exhibited the most stress transferred to the implants on the loaded side and opposite side. When the model was subjected to the posterior vertical load. The oblique load transferred to the implants was more than the vertical load. The ball and zaag attachments transferred the vertical load to both implants and edentulous area. These both attachment systems exhibited more stress on implants in oblique load where as the edentulous ridge was stress tree.Conclusion: Bar attachments transferred more stress to the implant bodies than ball and zaag attachments in both oblique and vertical loads and zaag attachments transferred more stress to the implant as compared with the ball ones.

Background and Aim: Bacterial contamination of dental unit waterlines may be attributed to biofilm formation. According to American Dental Association (ADA), bacterial colony counts of dental unit waterlines less than 200 CFU/ml if favorable. The aim of this study was to assess the effects of Bilpron, as a disinfectant, on bacterial. Colony counts of dental unit waterlines.Materials and Methods: In this controlled trial study on water samples of dental units, Shaheed Beheshti University of Medical Sciences, 6 units with Bilpron injection system as cases and 8 units without any disinfectant as controls of Endodontics department were investigated. Samples were obtained during 6 times, 3 samples of each unit (totally 108 samples in case group and 144 in control one). Sampling was performed on Wednesday and Saturday. Data were subjected to X2 and Fisher exact tests. Results: In samples without any bacterial contamination on Wednesdays, Bilpron was able to prevent staphylococcus growth on Saturdays (3.3%) which was significantly lower than the controls (16.3%) (P<0.01). There was no infection of Pseudomonas, beta hemolytic streptococci and Ecoli in Bilpron group that for all types the differences were statistically significant (P<0.01). However in contaminated waterlines on Wednesday, there was not a statistically significant difference between two groups.Conclusion: Bilpron may prevent bacterial growth in water if it is not contaminated but its usefulness for contaminated water has not been proved.

Background and Aim: In children requiring general anesthesia for dental care, a number of teeth are treated with amalgam in one session. The aim of this study was to compare the post -amalgam filling urinary mercury levels of children treated consciously vs. unconsciously. Materials and Methods: In this clinical trail research a group of 15 children requiring the usual tooth amalgam filling in office (group A) and the other group with 15 uncooperative children requiring general anesthesia for dental treatment (group B) were selected. All research conditions were made equal for both groups. The morning urine of each child was collected and coded at three time: before treatment, 4 days after treatment and 9 - 12 days after treatment. The urinary mercury levels were measured by the cold vapor atomic absorption spectrometric method. Data were subjected to t-pair test, Variance (ANOVA) and Duncan analyses.Results: The urinary mercury levels showed a significant increase in both groups post-treatment and during the sampling times (P<0.05). The amount of increase was more in group A as compare with group B (P<0.05).No significant relationship was found between the urinary mercury levels and sex, age, weight, the number of amalgam units and amalgam filled - tooth surfaces.Conclusion: Mercury absorption following tooth amalgam filling under general anesthesia is significantly less than that of in - office treatment.

Background and Aim: The caries preventive effect of pit and fissure sealants has been documented and their success, in this regard, is directly related to the retention rate of them. The aim of this study was to compare the retention rate of sealants with and without mechanical preparation of enamel by bur.Materials and Methods: In this randomized clinical trial, 37 children referred to Pedodontics Department, Faculty of Dentistry, Tehran University of Medical Sciences were selected based on inclusion and exclusion criteria. A total number of 128 permanent first molars were randomly divided into two groups: Case group (mechanical preparation by bur) and control group (conventional method without bur preparation). Following fissure sealant application, patients were followed up every 4 months. Data were subjected to McNemar test.Results: After one year, the complete retention rate in case group was 81.3% and in control Correspondence: group was 70.3%. Statistical analysis for matched pairs showed statistically significant difference between two groups (P=0.04)Conclusion: The application of bur resulted in superior sealant retention revealing the effectiveness of bur application prior to sealant therapy in caries prevention.

Background and Aim: Considering the existing concern on increasing caries and the importance of sweetness impact on it. The aim of this study was to determine the relationship between sweetness preference and dental caries among pre-school mother/child pairs in Tehran, 2004.Materials and Methods: The present study was conducted on 120 pairs of pre-school children and their mother (240 samples) using descriptive design and random cluster sampling. The levels of dmft/DMFT were measured on WHO indices and sweetness preference was measured by modified sweet preference inventory. The related factors included sex, type of pre-school, parents' age, occupation and education, and mother's marital status. The correlation between mother-child sweetness preferences was measured by Spearman correlation coefficient, the relationship between sweetness preference and the level of caries was assessed by Kruskal-Wallis method and DMFT/dmft correlation was judged by Pearson's relation.Results: Correlation between sweetness preference of mother and child was 0.14. There was no significant relationship between the levels of dmft/DMFT and children's dmft were 48.5±8.53 and 3.66±3.5, respectively and their correlation was 0.02. Conclusion: No significant relationship was found between sweetness preference and the amount of caries in mother/child pairs. In other words, sweetness preference plays no role in mother/child caries.

Background and Aim: Antero-posterior position of condyle in glenoid fossa puts a direct effect on antero-posterior and vertical position of mandible determining the facial morphology, as a result. The aim of this study was to evaluate the condylar shape in patients with Cl I and Cl m malocclusion radiographically.Materials and Methods: In this study, condylar shape as weel as length and width of its neck, on panoramic and lateral cephalometric radiographs of 80 subjects, with the mean age of 11 years for females and 12 years and 5 months for males were investigated. Condylar shape and length were measured on panoramic radiographs while the width of its neck was measured on lateral cephalometries.Results: Statistically significant relationship was found between facial grosth pattern and condylar shape in patients with Cl m malocclusion (p.value=0.02). In such patients, with normal or horizontal growth pattern, condylar flattening was the prominent shape. In patients with Cl I malocclusion there was no significant correlation between facial growth pattern and condylar shape. The width of condylar neck was less in patients with Cl m malocclusion than those with Cl I malocclusion. The difference was statically significant, however, condylar length was more among Cl m patients.Conclusion: The prominent shape of flattening in patients with Cl m malocclusion could be an indicative of the effects of malocclusion on condylar shape.

Background and Aim: Enamel defect is a developmental disorder which may be occurred with other tissues dysplasia. Following any quantitative and qualitative defects of enamel and dentin, teeth susceptibility to decay is observed. Disorders of any type in enamel developmental process may lead to complications in the appearance and microscopic structure of enamel. The aim of this study was to determine the prevalence of enamel defects in permanent incisors and first molars and its influencing factors among (8-9) - year - old children of Tehran.Materials and Methods: In this nested case control study, 1400 primary school students from 5 educational regions (1-6-8-9-16) were randomly selected. In each region, two girl schools and two boy schools, out of each 140 grade two students were randomly selected as case and control groups. Subjects were examined clinically using a portable light, a mirror and probe. After dental examination, a questionnaire comprising of possible etiologic factors was filled by parents. The obtained data were analyzed through Chi- square and fisher exact tests.Results: The prevalence of enamel defects was 34.2% in girls and 30.1% in boys. Enamel defects were found as follows: 65 children with permanent incisors, 222 children with permanent first molars and 165 children with permanent first molars and incisors defects. A statistically significant correlation (P<0.05) was observed between enamel defects and respiratory diseases.Conclusion: Although the etiology of enamel defects is not thoroughly recognized, it seems that embryonal and infantile disorders, especially respiratory diseases in the first 5 years of life, are important factors.