مجله دندانپزشکی دانشگاه علوم پزشکی تهران
سال بیست و یکم شماره 2 (پیاپی 55، تابستان 1387)

Among different treatments of patients with Class III malocclusion, orthopedic protraction of maxilla has been known as an effective method in mixed dentition period. The aim of this study was to evaluate the cephalometric changes of Cl III patients in mixed dentition period following face mask therapy and slow maxillary expansion. This was a before-after study which was conducted on 10 children in mixed dentition period, who had class III malocclusion and maxillary deficiency according to the Stiener and Mc Namara's analysis. The patients were all treated by protraction face mask and slow maxillary expansion. The cephalometric changes of maxilla, mandible and dental relations during the treatment were analyzed by Paired sample T Test. P<0.05 was considered as the level of significant. The overjet increasement was 1.7mm. Co. ANS distance improvement was 5.6mm, Ptm.ANS distance increasing was 3mm, and ultimately improvement of Gf.s distance was 1.5mm which were all statistically significant (p<0.05). Based on the results of this study, face mask therapy with slow maxillary expansion is able to improve the horizotal position of maxilla, in patients with Cl III malocclusion, in mixed dentition period.

Three Dimensional obturation of root canal is one of the main goals of root canal therapy to preserve health or reach the regeneration or healing of periapical tissues. Root end filling materials are used in numerous situations to reach the mentioned goals. One of the common root end- filling materials is mineral trioxide aggregate (MTA) which the foreign and Iranian ones are different in their prices. The aim of this study was to compare the rat connective tissue reaction to Iranian and foreign MTA. This was an animal study in which 40 rats were divided into 5 groups of each 8. The polyethylene tubes filled with foreign (Pro Root MTA) and Iranian (Root MTA) white MTA and were implanted in subcutaneous connective tissue. Similarly, the empty tubes were inserted in subcutaneous connective tissue as control group. The samples were examined histologically after 7, 14, 30, 60 and 90 days and were scored as followings: 0, was characterized to samples without inflammatory cells; without inflammatory reaction 1, for samples with less than 25 inflammatory cells; mild inflammatory reaction. 2, for samples with 25 to 125 inflammatory cells; moderate inflammatory reaction and 3, for ones with more than 125 inflammatory cells; severe inflammatory reaction. The data were analyzed using Kruskal-Wallis test and p<0.05 was considered as the level of significance. In general, inflammatory reactions were reduced in all groups. Experimental groups had moderate to severe inflammation in the 7th day which had significant difference with the control group having mild to moderate inflammation (p=0.04). There was not any significant differences between experimental and control group in 14th, 30th, 60th and 90th days (p>0.05). Based on the findings of this investigation, inflammatory subcutaneous connective tissue reaction to Iranian (Root MTA) and foreign (Pro Root MTA) MTA was the same.

Nonmetallic tooth- colored posts adhere to canal walls by dentin bonding agents and resin cements. Better retention and proper distribution of stress result from enough and proper bonding. The purpose of this study was to evaluate bond strength of D.T. Light - post with two different resin cements (self-cure & dual-cure) and to investigate the effect of irrigating solutions applied in root canal on bond strength of the resin cements and D.T.Light- post to root canal wall. In this experimental study 40 single root teeth (maxillary canine & central) were selected and stored in 0.1% thymol solution for one week and transferred to distilled water. The teeth were decoronated 2mm above CEJ. The canal space was mechanically enlarged using k-files (up to # 70). The teeth were randomly divided into two groups. The first group was irrigated with 2.6% NaOCl, and the second was irrigated with normal saline. After drying, the teeth were filled with gutta percha cones using lateral condensing method. After two weeks the post space was prepared and D.T.Light- post was inserted in each subgroup using self or dual-cure cements according to manufacturer's instructions. After thermocycling, the apical part was cut 1cm below CEJ. The remained length was divided into 9 equal sequential sections. Each section was submitted to shear push-out test in universal testing machine. Statistical analysis of the bond strength data was performed using ANOVA and post hoc tests with p<0.05 as the level of significance. All failed specimens were examined under stereomicroscope. Degrees of conversion of the cements were determined by FTIR. Significant difference in bond strength values were found among sites (P=0.001) and cements (P=0.03). With increasing in depth, bond strength decreased. The mean bond strength value in dual-cure resin cement was higher than self-cure cement. The irrigating solutions caused no significant difference in bond strength (P=0.46). DC% had significant difference in various depths. According to the results of this investigation, bond strength of dual-cure cement is higher than self-cure one in D.T Light- post because of post's translucency. 2.6% sodium hypochlorite does not affect the bond strength.

Various studies have shown that reliable bond at the root - post - core interfaces are critical for the clinical success of post - retained restorations. Severe stress concentration at post - cement interface increases post debonding from the root. To form a bonded unit that reduces the risk of fracture, it is important to optimize the adhesion. Therefore, some post surface treatments have been proposed. The purpose of this study was to investigate the influence of various surface treatments of tooth - colored posts on the bonding of resin cement. In this interventional study, 144 tooth colored posts were used in 18 groups (8 samples in each group). The posts included quartz fiber (Matchpost), glass fiber (Glassix), and zirconia ceramic (Cosmopost) and the resin cement was Panavia F 2.0. The posts received the following surface treatments: 1- No surface treatment (control group), 2- Etching with HF and silane, 3- Sandblasting with Cojet sand, 4- Sandblasting with Cojet sand and application of silane, 5- Sandblasting with alumina particles, 6- Sandblasting with alumina particles and application of silane. Then, posts were cemented into acrylic molds with Panavia F 2.0 resin cement. The specimens were placed in water for 2 days and debonded in pull - out test. Statistical analysis was performed using ANOVA followed by Tamhane and Tukey HSD. Failure modes were observed under a stereomicroscope (10). P<0.05 was considered as the significant level. Surface treatments (sandblasting with Cojet and alumina particles, with or without silane) resulted in improved bond strength of resin cement to glass fiber post (Glassix) and zirconia ceramic (Cosmopost) [p<0/05], but not to the quartz fiber post (Matchpost). In general, higher bond strengths resulted in a to higher percentage of cohesive failures within the cement. Based on the results of this study, sandblasting with cojet and alumina particles increases bond strength of resin cement to glass fiber post (Glassix) and zirconia ceramic (Cosmopost).Generally, the bond strength of resin cement to the posts is affected by the post's composition and surface treatment.

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. 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. 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). 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.

Microleakage has been always a major concern in restorative dentistry. The curing contraction of composites still presents a problem with controlling microleakage and postoperative sensitivity. The aim of this study was to investigate the effect of flowable and dual-cure resin composite liners on gingival microleakage of packable resin composite restorations. Sixty Class II cavities with cervical margins 1 mm below the CEJ were prepared in 30 extracted human molars. The teeth were randomly divided into five groups of 12 each. In control group, each tooth was restored incrementally with Tetric Ceram composite without applying any liner. In the second and forth groups, flowable materials- Tetric Flow and dual-cure composite resin cement Relay X ARC were placed respectively as a 1-mm thick gingival increment and cured before the resin composite restoration, whereas, in the third and fifth groups liners were cured with the first increment of packable composite.The restored teeth were stored for one week in distilled water at 370C, and thermocycled between 50C and 550C, sealed with nail varnish except the tooth - composite interface in cervical restoration margins and immersed in 2% basic fuchsin for 24 hours. Dye penetration was evaluated using a stereomicroscope with 28x magnification. The data were analyzed by Kruskal-Wallis and Mann-Whitney U-tests with p<0.05 as the level of significance. The results of this study indicated that there were significant statistical differences between control - cured flowable liner, control-flowable liner without separately curing, control-cured dual cure composite resin cement groups.However there were no significant differences between dual-cure composite resin cement without separately curing-control,cured flowable liner-cured dual cure composite resin cement, flowable liner without separately curing-dual cure composite resin cement without separately curing groups. The results of this study indicated that none of techniques could thoroughly eliminate microleakage in gingival floor, however the effect of flowable or a dual-cure liner on reducing the gingival microleakage was found to be statistically significant in tested restorative material.

Pit and fissure sealant therapy, is one of the most effective methods, in prevention of occlusal caries. Saliva contamination before curing the resin can increase the risk of failure in this method. The purpose of this study was to evaluate the effect of saliva contamination prior to curing on microleakage of pit and fissure sealants. In this experimental in vitro study 21 sound human pre molars were selected and two standardized V-Shaped fissures were prepared on both buccal and lingual surfaces, then they were randomly divided into two equal groups. In the control group, the sealant was cured without any saliva contamination and in the case group, the sealed teeth were immersed in artificial saliva for ten seconds before curing. After thermocycling the samples were immersed in 2% fouchsin solution for 24 hours and then sectioned longitudinally in bucco - lingual direction. The specimens were then fixed and assessed under stereomicroscope to determine microleakage and dye penetration using paired student t. test. P<0.05 was considered as the level of significance. Analysis of data showed no significant differences in microleakage, between the two groups (p=0.178). According to the results of this study saliva contamination of uncured sealant had no influence on microleakage.

Zygomatic fractures are common among oral and maxillofacial problems and ocular injuries are of great importance, the prevalence of ocular problems following zygomatic fractures in Iran is not clear so we performed this study to evaluate this problem in patients referring to Shariati Hospital. In this descriptive, cross-sectional study, we evaluated the patients who referred to department of oral and maxillofacial surgery of Shariati hospital for ocular complains following zygomatic fractures. The evaluation was performed both clinically and historically. 115 patients were examined (87 males and 28 females) with the mean age of 26 for males and 32 for females. The prevalence of ocular injuries were as follows: subconjunctival ecchymosis: 23.07% for males and 21.05% for females. Displacement of palpebral fissure: 26.5% for males and 27.6% for females. Unequal papillary levels: 18.37% for males and 15.78% for females. Diplopia: 8.9% for males and 10.5% for females. Enophthalmos: 23.1% for males and 25% for females. It is strongly recommended to refer patients with zygomatic fracture for an ophthalmologic consultation.

Contaminated dental handpieces have the potential to transfer infection to patients. New generation of autoclavable turbines have to some extent overcome the problem however, in clinic sometimes it is necessary to use chemical to disinfect handpieces. The aim of this study was to determine the antimicrobial effect of some routinely used disinfectant solutions on dental contaminated handpieces. In this experimental study 35 turbines were sterilized. The turbine's heads were inserted into microbial suspension containing staphylococcus, pseudomonas and candida and then exposed to the disinfectant solutions. Inoculations into culture medium were made at different intervals. All medium was incubated for 24 hours at 37oC followed by spectrophotometer inspection for detection of microbial growth. Serial dilutions of disinfectant agents were used to determine the highest dilution in which there was no microbial growth. Kruskal wallis test was used for statistical analysis and p<0.05 was considered as the level significance. Ethanol had antimicrobial effect on all of the tested microorganisms at dilution of 1:4. Betadine at dilution of 1:64 caused inhibition of all of the microbes except pseudomonas. Micro 10 had antimicrobial effect up to dilution of 1:256 but could not inhibit microbial growth at higher dilution. Sodium hypochlorite inhibited growth of the three microoganisms up to dilution of 1:1024. Based of on the results of this study sodium hypochlorite was found to be the most effective antimicrobial agent among those used in this study, inhibiting microbial growth at the highest dilution

Plaque control has always been important in preventive dentistry. Various methods and materials have been introduced for this purpose. Recently a three-colored tooth paste has been introduced which claims to prevent plaque formation. The aim of this study was to compare three-colored pouneh tooth paste containing triclosan with the conventional one in preventing plaque formation. This was a randomized double blind cross over clinical trial which was carried out on 40 dental students of Tehran azad university in 2005. Before beginning the trial, the index of plaque was evaluated, registered and reduced to null. The subjects were randomly divided into two groups, the case group (three color tooth paste) and the control group (conventional tooth paste). The participants were asked to apply the specified tooth paste with an oral B Advantage Artica toothbrush for two weeks. After two weeks, the amount of plaque was re-registered and again reduced to null. The type of tooth paste was changed among two groups and the plaque was registered for the third time at the end of two weeks. Then the patients and assessors were not aware of the type of tooth paste in the tubes (double blind). McNamar and ManWhitney test were used. From the 40 subjects, 4 cases were omitted due to the different reasons. The amount of initial plaque index was 88.3 12.1 which was reduced to 78.2 16.9 in the control and 74.1 19.3 in the case group. The difference between primary plaque and secondary plaque (after applying tooth paste) was significant in both case and control groups, however there was not any significant difference between two groups. Based on the results of this study, there was not any significant difference between conventional and three-colored tooth paste in reducing the plaque index.