Journal of Dental Medicine

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There are two types of high-copper dental amalgams produced in Iran Cinalloy (lathe-cut particles) and Cinalux (spherical particles). Tarnish is one of the disadvantages of dental amalgam, which precedes corrosion, and in fact it means real destruction of restorative materials. The purpose of this study was to compare the extent of tarnish in Cinalux and Cinalloy amalgams. 32 patients, with at least two carious or poorly restored teeth were selected. Then, each tooth was restored with one of these two types of dental amalgams. The restorations were polished after 24 hours and patients were followed up after 9 months. The restorations were categorized in four groups of no change, one plus (1-30%), two plus (30-60%) and three plus (more than 60%) according to the level of discoloration. The results showed that the level of tarnish in Cinalux group was significantly less than Cinalloy group. The mean of tarnish for Cinalloy and Cinalux was 2.09±0.59 and 1.72±0.68 respectively. In addition, statistical analysis showed that there was no significant relationship between tarnish and Oral hygiene, smoking, operator or type and place of restoration.

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Dental amalgam is one of the oldest restorative materials, used in dentistry, which has undergone a lot of quality changes since its advent. Copper is one of the major elements in dental amalgam. Dental amalgam is classified as low and high cooper group based on the percentage of this element. Cinaluy is an Iranian product, a product of Shahid Faghihi's factory and its particles are spherical with high copper and it does not contain any zinc and gama II phase. The goal of this study was to identify the type and percentage of its ingredients and to analyze this dental amalgam by muclear reactor. The products of the factory, at two different times, were compared with each other and also with the percentages presented by the factory, regarding their ingredients. They were also compared with two standardized amalgams called: Sybralloy and Tytin. Three typical Cinalux amalgam capsules, produced on different dates, were selected. The contents of capsules were enveloped in plastic bags and then sealed and placed in a miniature reactor to undergo nuclear radiation for 10 days. After this period, the elements in amalgam became activated and converted into radioisotopes of the same elements, and began to radiate. Then gama spectrometer system accumulated these radiations and transferred them to Span software. This software, aided by reference standards, shows the intensity and the wave length of the received radiation, and consequently identifies the type and percentage of the elements in amalgam. The results demonstrated that the Cinalux amalgam samples, regarding the type and percentage of their elements, were identical and also met the factory standards. The differences were not significant. There was also no significant difference between Cinalux amalgam and the standardized amalgam Sybralloy, regarding the percentage of their elements, but comparing this amalgam with the standardized amalgam Tytin, a significant difference was not observed.

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Statement of Problem: Microleakage presents the major cause for restorations failure in the oral cavity resulting in postoperative sensitivity, pulp irritation and secondary caries formation.

Aim: The aim of this study was to compare two dentinal adhesive systems of fifth generation and copalite varnish in reducing microleakage of amalgam restorations in primary teeth.
Materials and Methods: In this in-vitro study, 100 class V amalgam restorations were prepared on the buccal or lingual surfaces of primary molar and canine teeth. Samples were randomly divided into four groups (25 samples each). No liner was used for the first group and the second group restorations were lined with copalite varnish. Two dentin adhesives, called Syntac C and Single Bond, were used for the third and fourth groups, respectively. At the next stage, the samples were immersed in 5% fuschin solution for 24 hours, then sectioned buccolingually, and examined under a stereomicroscope for microleakage evaluation.
Results: There was a significant difference between four groups statistically (PO.000I), Comparing four groups, the first and fourth ones, demonstrated the most and the least microleakage, respectively.

Conclusion: The present study showed that new dentinal adhesive systems caused microleakage reduction in amalgam restorations of primary teeth.

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Background and Aim: Achieving appropriate seal in canal obturation is the main goal of endodontic therapy. However, in some cases, it can not be obtained by non-surgical procedures alone. Retrograde surgery is one of the most common procedures in endodontics. Apical seal improvement can be obtained by root end filling and decreasing the root end resection angle (bevel angle). The aim of this study was to investigate the role of bevel angle on apical microleakage following the use of amalgam and MTA as root end filling materials.

Materials and Methods: In this experimental study, 128 extracted human teeth were instrumented and obturated by lateral condensation technique. The teeth were divided into two groups and the apical root resection was performed by high speed fissure bur (one group perpendicular to the long axis of the teeth and the other 45 to the long axis. The 3 mm root end cavity was prepared by ultrasonic device. Each group was divided into two subgroups: One filled with amalgam and the other with MTA. Teeth were incubated for 72 h, covered by two layers of nail polish (except for apical 3mm) and submerged in methylene blue for 48 h. Teeth were washed under tap water and mesiodistally dissected by low speed disc. Dye penetration was evaluated by stereomicroscope. Data were analysed by two way ANOVA and Tukey tests with p<0.05 as the limit of significance.

Results: The results showed that retrofill material type had a significant effect on microleakage and MTA was superior to amalgam in this respect. Bevel angle failed to show any significant effect on apical microleakage.

Conclusion: Based on the results of this study, it seems that the use of MTA instead of amalgam in clinical practice can improve the success rate of endodontic surgery whereas the bevel angle can be determined based on the status of each individual case However, increasing the bevel angle seems to increase microleakage due to exposure of more dentinal tubules.

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Background and Aim: Dentists are exposed to mercury from dental amalgam in their routine occupational practice. Excess exposure to mercury is harmful and the measurement of mercury content of urine is a reliable and valid assessment of the level of mercury exposure from dental amalgam. The aim of this study was the measurement of urine mercury in dentists of Tehran and assessment of some possible related factors.

Materials and Methods: This cross-sectional study was performed randomly on 211 dentists in all regions in Tehran city (center, north, south, west, and east) between 1381 and 1383. Dentists were asked to give a sample of urine in the day of visit and to complete a questionnaire consisting of variables such as age, working history, handling of amalgam, environmental parameters and general health situation. Urine samples were analyzed by cold vapour atomic absorption spectrophotometry. Data were analyzed by Kruskall Walis, Kendall and Mann Whitney tests, with p<0.05 as the limit of significance.

Results: The mean of urine mercury content in Tehran dentists was 3.1 (± 3.95) which was lower than the international TLV (Threshold Limit Value). There was a significant relation between urine mercury level and working hours per day (P=0.006). This relation was observed with working hours per week too (P=0.006). In general dentists, there was a positive relation between urine mercury and age (0.008) as well as the practicing years (P=0.034). A significant relation was found between urine mercury and the number of amalgam repairs and replacements in restorative specialists (p=0.039). There was a significant relation between the number of amalgam fillings in the mouth and urine mercury in general practitioners (p=0.027). The type of amalgam (predosed capsules or bulk powder) had a significant effect on the urine mercury content (P=0.001). There was no significant relation between urine mercury and other variables of the study such as the squeezing of triturated amalgam, storage method of residual amalgam, method of storing mercury and office ventilation.

Conclusion: Based on the results of this study, the mean urine mercury content of dentists of Tehran was below the international TLV. The use of precapsulated amalgams had significant effect on the urine mercury. Most of the dentists were working in public or semiprivate clinics, so it is concluded that the level of general hygiene and specially mercury hygiene in these centers seems to be acceptable.

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Background and Aim: Dental Amalgam is a common restorative material for posterior teeth. Because of Hg content in the composition of amalgam, during the handling of material, mercury may release as vapor in the environment. Excess amount of mercury vapor can cause serious health problems in dental personnel. The aim of this investigation was to determine mercury vapor concentration in working environment of dentists in Tehran.

Materials and Methods: 211 dental clinics were participated in this cross-sectional study. The clinics were randomly selected from different regions of Tehran (north, center, south, east and west). The dentists were asked to complete a questionnaire including items on demographic characteristics such as age, sex and work history, method of handling of amalgam, environmental characteristics and general health conditions. Environmental measurements of mercury vapor in dentists’ offices were done by mercury absorption tubes (Hydrar) and personal pumps (SKC, 222-3, England) as suggested in NIOSH method. Analysis of air samples was done by atomic absorption spectrophotometery (cold vapor). The data were analyzed by non-parametric tests (Kruskall Wallis, Mann-Whitney and Kendall).P<0.05 as the level of significance.

Results: The mean mercury vapor concentration in dentists’ offices was 8.39(±9.68) µg/m³.There was no significant relationship between the urine mercury of dentists (3.107±3.95) and the air Hg vapor concentration of their offices. Using precapsulated amalgam showed significantly less Hg vapor than bulk amalgam (P=0.034). Also the surface area of working room and air Hg vapor (P=0.009) had a significant relationship (P=0.009 r=0.81). There was not any significant correlation between mercury vapor and other factors such as working hours per day and working days per week, squeezing of triturated amalgam or not, storage medium of set amalgam (water or fixer solution), mercury storage method and type of ventilation.

Conclusion: The concentration of mercury vapor in dental offices' environment was lower than threshold limit value. Based on this study the type of amalgam (precapsulated or not) and area of the working room had significant effect on the mercury vapor concentration of environment.

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Background and Aim: Patients always complain about metallic color of amalgam restorations. Covering amalgam by composite can solve this problem. Since polymerization shrinkage is a serious shortcoming in composites, application of the combined amalgam and composite restoration is one of the methods to reduce leakage in the cervical margins of posterior restorations. The aim of this invitro study was to evaluate the microleakage of amalgam/composite interface when Rely-X ARC adhesive resin cement was used in the joint.

Materials and Methods: Twenty-four sound extracted premolars were chosen. Mesial and distal class II conventional cavities were prepared and the samples were divided into 4 groups of 12. In all groups, the bases of the cavities were restored with amalgam and then the remaining part was filled by composite resin. Specimens in groups 1 and 2 were restored with composite-resin, immediately after condensing amalgam without or with application of Rely-X ARC (3M, ESPE) respectively. In groups 3 and 4, composite resin were applied 24 hours after condensation of amalgam, without or with application of Rely-X ARC respectively. After polishing and thermocycling, all specimens were prepared for dye penetration and the degree of leakage was scored and analyzed using Kruskall Wallis test with p<0.05 as the level of significance.

Results: The frequency of dye penetration in different groups was obtained. The most and the least scores were observed in groups 3 and 4 respectively. No statistically significant difference was observed in different methods.

Conclusion: None of the methods in this study could seal the amalgam/composite-resin interface.

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Background and Aim: Nowadays, esthetic dentistry has become an important part of modern dentistry. Bleaching is considered as a conservative, safe and effective way for treatment of discolored teeth. Although bleaching is commonly used on anterior teeth, the bleaching gel may come into contact with patient's former amalgam restorations and result in corrosive effects, dissolution of amalgam phases and increasing release of mercury. Mercury released from dental amalgam during mouthguard bleaching can be absorbed and increase the total mercury body burden. The aim of this study was to determine the amount of mercury released from Iranian and foreign brands of amalgams with spherical and admixed particles, polished and unpolished, after 16%carbamide peroxide gel application.

Materials and Methods: This experimental in vitro study was performed on 256 Iranian and foreign amalgam samples with spherical and admixed particles. The provided samples were put in distilled water and classified according to the type of amalgam, shape of particles and quality of surface polishing. The test samples were placed in Nite White 16% carbamid peroxide gel and control samples were put in phosphate buffer (Ph=6.5) for 14 and 28 hours. The amount of released mercury was calculated using AVA-440 Mercury Analysis System (Thermo Jarrell Ash model SH/229) with cold-vapor atomic absorption. Data were analyzed using t-test, four way and three way ANOVA tests with P<0.05 as the level of significance.

Results: 16% Nite White carbamide peroxide gel caused a significant increase in amount of mercury released from amalgams in all groups (P<0.05). Mercury release from Iranian amalgam was higher than that from the foreign brands (P<0.05). There was no significant difference in mercury released from spherical and admixed amalgams (P>0.05). The amount of mercury released from Iranian and foreign amalgams was time dependent (P<0.05). Furthermore, the amount of mercury released from unpolished amalgams was higher than polished ones (P<0.05).

Conclusion: The present study indicated that exposure of amalgam to 16% Nite White carbamide peroxide  gel causes a significant increase in mercury release from the amalgam which is significantly influenced by the brand, exposure time, and surface polishing.

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Background and Aim: Application of varnish and dentin bonding agents can effectively reduce microleakage under amalgam restorations. Also rebonding may show some effects on microleakage and its complications. The aim of this study was to evaluate the effect of liner/ adhesives on microleakage of Class V amalgam restoration with or without rebonding.

Materials and Methods: In this in vitro study Class V cavities were prepared on sixty sound human maxillary premolars with the gingival floor 1mm below the CEJ. Cases were divided into six groups of ten teeth each. Specimens in group 1 and 2 were lined with Copalite and Scotchbond Multi-Purpose (SBMP) respectively. In the third group (control) no liner was applied. The teeth were then restored with spherical amalgam. Specimens in group 4 to 6 received the same treatments but after filling, the interfaces of restorations and teeth were etched with 37% phosphoric acid gel, rinsed and dried. Adhesive resin of SBMP was applied over amalgam and tooth margins and polymerized (rebonding). Specimens were thermocycled, exposed to dye and sectioned. Microleakage was graded (0-3) using a stereomicroscope at X40 magnification. Data were analyzed with Kruskal-Wallis, Mann-Whitney and Wilcoxon pair wise statistical tests. P<0.05 was considered as the limit of significance.

Results: The groups lined with SBMP showed the lowest and the groups without liner the highest microleakage (p= 0.001). Significant difference was observed in microleakage mean rank of enamel and dentin margins (p=0.048). Rebonding with resin did not improve the seal (p> 0.05).

Conclusion: Based on the results of this study, total etch adhesive system had significant effect on microleakage of Class V amalgam restorations especially in cervical margin. Rebonding did not show a significant effect on microleakage.

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Background and Aim: Several materials have been introduced for retrograde fillings, pulp capping and sealing root perforations, but their biological effect on vital tissues and cells is not clear. The purpose of this study was to evaluate the reaction of human periodontal ligament fibroblasts to four root canal filling materials: Pro Root MTA, Root MTA, Portland cement and amalgam.

Materials and Methods: In this experimental study, impacted or semi impacted third molar teeth were extracted in aseptic conditions and tissues around the roots were used to obtain fibroblast cell line. After proliferation, cells were cultured in chamber slides and extracts of materials were added to wells. Fibronectin, type I collagen and TGF-  expression were measured by immunocytochemistry method. Data were analyzed by SPSS 11.0 using one way ANOVA and Tukey test. P<0.05 was considered as the limit of significance.

Results: Collagen I expression was higher in Pro Root MTA group after 24 hours (p<0.05) and in Portland cement group and positive controls after 48  hours. Portland cement group showed the highest expression of collagen after 1 week. There was no significant difference in fibronectin expression after 24 hours. After 1 week the highest expression of fibronectin was seen in Portland cement, Root MTA and Pro Root MTA groups. TGF-  expression was higher in amalgam, Root MTA and Pro Root MTA specimens after 24 hours and was the highest in Pro Root MTA group after 48 hours.

Conclusion: Based on the results of this study, Portland cement and Root MTA are comparable with Pro Root MTA and better than amalgam regarding their effects on human periodontal ligament fibroblasts.

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Background and Aim: Amalgam is one of the mostly used restorative materials, but has some disadvantages. Microleakage is one of the short comings of amalgam which may lead to sensitivity and recurrent caries. The aim of this study was to evaluate the effect of three dentin bonding systems on reduction of microleakage in amalgam restorations.

Materials and Methods: Class II amalgam restorations were made in 40 noncarious molar and premolar teeth. Then the specimens were divided into four equal groups. Scotch Bond Multi Purpose, Single bond,
iBond, were used as liner in groups one to three respectively and in group four no liner was used. The teeth were restored with high copper spherical amalgam. After thermocycling for 500 cycles at 5⁰C and 55⁰C, the specimens were immersed in basic fuchsin for 24 hours, bisectioned mesiodistally and evaluated under stereomicroscope at X25 for dye penetration. The data were analyzed by Kruskal-wallis and Scheffe. P<0.05 was considered as the level of significance.

Results: The groups showed significant difference (p=0.003). The group four had significantly less microleakage than the first and second groups (p<0.05). The second and third groups showed significantly different microleakage (p=0.038).

Conclusion: Based on the results of this investigation applying dentin bonding agents has no effect on reducing microleakage in amalgam restorations, however more studies are recommended.

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Background and Aims: The aim of this in vitro study was to assess the shear bond strength of amalgam to dentin using four dentin adhesive systems.
Materials and Methods: One hundred human molars were selected. After enamel removal, a dentin cylinder with 3 mm thickness was prepared. Eighty specimens were resorted with amalgam and four dentin adhesive systems as follows (n=20): group 1, Scotch Bond Multi-Purpose group 2, One Coat Bond group 3, PQ1 and group 4, Panavia-F. In group 5, 20 specimens were resorted with amalgam and varnish as control group. The specimens were incubated at 37°C for 24 h. The shear bond strengths were then measured by using push out method. The data were analyzed by one-way ANOVA and post hoc Duncan's tests.
Results: Mean values for bond strengths of test groups were as follows: group 1=21.03±8.9, group 2=23.47±9, group 3=13.16±8.8, group 4=20.07±8.9 and group 5=14.15±8.7 MPa±SD. One-way ANOVA showed the statistically significant difference between the bond strengths of five groups (P=0.001). Post hoc Duncan's test showed significant difference between groups 1and 3 (P=0.008), groups 1 and 5 (P=0.019), groups 2 and 5 (P=0.0008), groups 4 and 5 (P=0.042), and groups 3 and 4 (P=0.018).
Conclusion: Results of this study showed that the bond strength of amalgam to dentin using One Coat Bond as dentin adhesive system was higher than that observed in other dentin adhesive systems.

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Background and Aims: Endodontically treated teeth are prone to fracture because they loose a big amount of their structure. The treatment plan of those teeth is completed when they are rehabilitated with a strong and functional restoration. The purpose of this study was to evaluate the fracture resistance of endodontically treated teeth restored with amalgam cuspal coverage in comparison with other restorative techniques.

Materials and Methods: 40 human healthy maxillary premolars were divided into 4 groups: group1 (S): sound teeth, group 2(Co): endodontically treated teeth with MOD cavity restored with bonding and composite, group 3(Am-B): endodontically treated teeth with MOD cavity restored with bonding and amalgam and group 4 (Am-CC): endodontically treated teeth with MOD cavity restored with amalgam cuspal coverage. Then the restorations were stored in water and room temperature for 100 days at then thermocycled for 500 cycles between water baths at (5.5 ± 1) and (55 ± 1) ⁰ C. The fracture resistance was evaluated by universal testing machine (Instron, 1195 UK) with the compressive force of about 2000 N in 0.5 mm/min. The fracture modes were evaluated in four groups by a stereomicroscope. Statistical analysis (Scheffe test) was done for all groups (P<0.05 was considered as the level of meaningfulness).

Results: The highest fracture resistance was found in group 4 (Am-CC) (976 ± 23.27 N) that had no significant difference with sound tooth (P>0.05). The lowest fracture resistance was found in group 2 (Co) (384 ± 137.4 N) that had no significant difference with group 3 (Am-B) (P>0.05). The fracture resistance in group 4 was significantly higher than group 2 (Co) and 3 (Am-B). The fracture mode in group 1 was cohesive within tooth and in group 2 (Co) and 3 (Am-B) was mixed cohesive and adhesive, and in group 4 was cohesive within in restorative material.

Conclusion: The highest fracture resistance was found in teeth that received amalgam cuspal coverage.