JOURNAL OF DENTISTRY (SHIRAZ UNIVERSITY OF MEDICAL SCIENCES)
Year:2010 | Volume:11 | Issue:1 (26)|Papers Count:19

Statement of Problem: Root canal cleaning is the main purpose of canal instrumentation. Hand instruments leave more debris and smear layer on the root canal walls .The use of automated instruments is helpful in root canal cleaning.Purpose: The aim of this study was comparison of hand NiTi instruments, rotary flexMaster and FKG race instruments in root canal cleaning.Materials and Method: In this interventional and in vitro study, 75 single canal teeth with minimum curve were selected and divided into three groups of 25 teeth in each. The canals were prepared with hand NiTi file, FlexMaster and race instruments using crown down preparation technique, up to size 40 .During preparation, the root canals were irrigated with 5m1 of 0 0.50% Naocl solution and at the end of instrumentation with 5 ml of normal saline. After splitting the roots longitudinally, the amount of the debris and smear layers was quantified on the basis of Hulsmann method, using a scanning electron microscope. The data were analyzed by Kruskal wallis test using SPSS statistical software.Results: In general, flexMaster instruments left less debris than FKG race and NiTi hand instruments significantly) p < 0.05. (This difference was significant in all three thirds of the canal. FlexMaster instruments left debris with the smallest size in the middle and coronal thirds of the canal but not the apical third. FlexMaster instruments left less smear layers Just in the apical third of the canal significantly.Conclusion :No completely cleaned root canals were found with any of the three instruments .In general, FlexMaster instruments proved to have better canal cleaning in all three third of the root canal significantly.

Statement of Problem: Conscious sedation is frequently employed for the management of precooperative or extremely anxious dental patients. Many medications have been used to sedate children in the dental office separately and in combination in an attempt to find an ideal sedation regimen. However, it seems that there is a need for finding a drug with more effectiveness and lower complications.Purpose: This study was undertaken to compare the effectiveness of oral combinations of midazolam/ketamine and midazolam /hydroxyzine in sedating pediatric dental patients.Materials and Method: In this prospective, double-blinded, crossover clinical study, 25 uncooperative children, ages 37 to 56 months (mean age of 48.1 months), in need of at least 2 restorative visits were selected. The subjects were assigned randomly to receive either a combination of midazolam 0.5 mg/kg and ketamine 5mg/kg or midazolam 0.5 mg/kg or hydroxyzine 2 mg/kg prior to dental treatment at the first appointment. The alternative drug regimen was administered at the second appointment. All the subjects also received 50 %nitrous oxide/oxygen during treatment. The child's behavior, in all 4 behavioral criteria including sleeping, crying, body movement and overall behaviors, during injection and procedure, was evaluated by an independent clinician who was unaware of the drug given to the child. The data were analyzed using Wilcoxon and McNemar tests. Results: Midazolam/ketamine was found to be significantly more effective than midazolam/hydroxyzine during injection and procedure for sleeping (p =0.00, p =0.001, respectively), crying (p= 0.00, p.= 001) and body movement (p =0.001, p= 0.001) and was more successful, according to the overall behavior evaluation criteria (p =0.008.)Conclusion: Midazolam /ketamine resulted in safe and effective sedation for the dental treatment of young children and in comparison to midazolam /hydroxyzine, it resulted in less sleeping, crying, movement and better overall behavior during the dental treatment.

Statement of Problem: Complete root canal seal is one of the most important aims of root canal treatment .Elimination of smear layer plays an important role in this regard.Purpose: The purpose of this study was to compare the apical microleakage of Tubliseal sealer when 17 %EDTA, 7 % citric acid, or 20 %citric acid was used to remove the smear layer.Materials and Method: In this experimental study, 80 single rooted teeth were selected. The crowns were removed from cemento enamel junction (CEJ). Instrumentation of the canal was performed by the step back method .The teeth were randomly divided into 3 experimental groups of 20 and 2 control groups of 10 (positive and negative groups).Final irrigation was implemented as follows: group1; EDTA17+%NaOCl, group2; 7 %citric acid+NaOCl and group3; 20% citric acid+NaOCl. Then, the groups were obturated with gutta percha and Tubliseal sealer. Lateral condensation technique was carried out in all groups .The teeth were stored in 100 %humidity and 37°C for 48 hours. The root surfaces other than the apical 2mm were covered with 2 layers of nail polish. After that, the teeth were placed in metylene blue dye for 72 hours. Then, the teeth were sectioned longitudinally with a diamond disk and the degree of dye penetration was measured. The results were statistically analyzed by one-way Variance and Post Hoc Tukey tests. Results: A statistically significant difference was found between the groups (p < 0.05). The least amount of dye penetration (2.59mm) was belonged to 17 %EDTA group and the highest mean dye penetration occurred in the group in which 20 %citric acid was used (3.59mm).Conclusion: The results of this in vitro study indicate that when a ZOE-based sealer is used for obscuration of the root canal system, EDTA is recommended to remove the smear layer. Furthermore, it can be concluded that the main purpose of removing the smear layer is not only to clean the dentinal tubules from organic and inorganic debris, but also to create a dentinal surface structure that best fits the characteristics of the sealer used for root canal obturation.

Statement of Problem: Bonded restorations have a number of advantages over traditional, non-adhesive methods. Adhesion reduces the microleakage at the restoration -tooth interface. Prevention of microleakage, or the ingress of oral fluids and bacteria along the cavity wall, reduces the clinical problems such as postoperative sensitivity, marginal staining, and recurrent caries, all of which may jeopardize the clinical longevity of restorative efforts. Purpose: The aim of this study was to evaluate the microleakage in class V composite restoration with total-etch and self-etch adhesive systems.Materials and Method: In this in -vitro study, 48 standard class V cavities were prepared in the buccal surface of human extracted premolars so that the occlusal margins of the cavities were in the enamel and the gingival margins in the dentin (cementum). The teeth were divided into two groups of 24. In the first group, the cavities were restored with total -etch system (Excite) and composite. The teeth in the second group were restored with self-etch system (Prompt L –Pop) and the same composite. The teeth were thermocycled 500 times between 5 -55°c and then were covered with nail -polish and adhesive wax except for 1 mm around cavities, and all teeth were immersed into the 2 %methylene blue for 10 hours. The samples were mounted in polyester blocks, sectioned longitudinally at the middle of the cavities, and evaluated for microleakage under a stereomicroscope at 40x magnification. Dye penetration was scored between 0-3. Data were analyzed with Mann Whitney and Wilcoxon tests.Results: In the enamel and dentin margins, microleakage for the total-etch group was found to be less than the self-etch group (p<0.05). A significant difference in the microleakage mean rank of the enamel and dentin margins was observed (p < 0.05). Microleakage in the enamel margins was less than that in the dentin margins. Conclusion: Total-etch adhesive system showed a significant difference on the microleakage of class V composite restorations especially in the enamel margin.

Statement of the Problem: The use of calcium hydroxide as an intra-canal medication can lead to leakage of permanent obturation of the canal and failure of the treatment.Purpose: The purpose of this study was to evaluate the rate of the remained calcium hydroxide in radiographic views and their effect on apical leakage.Materials and Method: For this study, 75 human extracted premolar teeth were divided into 5 groups randomly. All the teeth were prepared by step back technique and apical foramen enlarged to # 30 file. Aria dent calcium hydroxide was introduced into the canal in group 1 .In group 2, Barium sulfate was added to calcium hydroxide powder in 1 to 9 proportions and the method was gone on the same as in group 1. Dentsply calcium hydroxide was mixed with glycerinbased aqueous and introduced into the canal in group 3. Calcium Hydroxide paste (Pulpdent) was introduced into the canal with its special needle. In groups 4 and 5, there was no calcium hydroxide as a control group. The canals were prepared with one size larger than master apical file, MAF (35 file size) to remove calcium hydroxide. The remaining of calcium hydroxide was accessed radiographically and compared using Kruskal Wallis test. Dye leakage in the 5 groups was compared, using ANOVA and Tukey tests.Results: There was no significant difference between the five groups when dye leakage was compared, but calcium hydroxide paste (Pulpdent) shows more remained material when evaluated radiographically. Conclusion: The use of calcium hydroxide paste with methyl cellulose base for intra-canal medicament is not recommended.

Statement of Problem: Nowadays, MTA has numerous clinical applications because of desirable properties. Many teeth which are treated by MTA need final composite restorations .In this situation, the bonding between composite and MTA has the main role in retention, durability and seal of the restoration.Purpose: Evaluation of the bond strength between MTA and composite resin and its comparison with Resin Modified Glass Ionomer (RMGI).Materials and Method: Sixty specimens were prepared for three experimental groups of white MTA, gray MTA, and glass ionomer Fuji II LC .Ten specimens in each group were etched with 37 %phosphoric acid for evaluation of the etching effect while ten specimens were not etched .All specimens were then bonded to the composite and shear bond strength test was performed, using Instron testing machine .In addition, the fractured surfaces of the samples were checked with steriomicroscope (x10). Data were analyzed by ANOVA and Tukey HSD test.Results :The highest shear bond strength value was seen in unetched glass ionomer subgroup and there were significant differences in shear bond strength of the composite to unetched glass ionomer in comparison with the other groups (p<0.001). There were no significant differences in shear bond strength of the composite to etch and unetched white MTA, etched and unetched gray MTA, and etched glass ionomer (p > 0.05).Conclusion: Shear bond strength between MTA and the composite is comparable with etched glass ionomer. The etching of the RMGI surface causes a significant decrease of bond strength to the composite but it has no effect on the bond strength of MTA to Composite.

Statement of Problem: Acute pain and swelling following root canal therapy is considered as flare up. Pushing the infectious debris to the periapical region. Inadequate chemical and mechanical cleaning are the reasons for inflammation of this area. Microorganisms are the major causative agents of acute peri-radicular inflammation. Adequate and appropriate irrigation of the canal removes the intra-canal microorganisms, debris and infected agents from the canal space and may decrease pain and swelling. On the other hand, caustic effect of intra-canal irrigants may cause acute inflammation in the peri-radicular tissue. Purpose: The aim of this study was to compare the effect of three intra-canal irrigants on the incidence of flare-up following root canal therapy of the teeth with necrotic pulp.Materials and Method: In this clinical trial study, 225 patients with molar necrotic pulp and peri-radicular lesion were selected and randomly divided into three groups, 75 in each. Protaper Rotary files were used for preparing the canals and 2.5 %sodium hypochlorite, 0.2% Chlorhexidine gluconate or saline were used for irrigation of the canals in each group respectively. Then, they were filled by lateral condensation technique. Questionnaires were given to the patients, asking for the level of their pain and swelling. The patients were followed for 48 hours. The data were statistically analyzed, using Chi-square, Mann-Whitney and Kruskal –Wallis tests.Results: The results of this study showed no significant difference between irrigant solutions in the incidence of flare - up after endodontic treatment.Conclusion: Our clinical research indicated that the type of irrigating solution used makes little difference in the incidence of postoperative flare-up .It is difficult to attribute flare-up incidence specifically to the use of any particular irrigant.

Statement of Problem: Proper bond of the soft liner to acrylic denture base is one of the most important factors in the longevity of soft liner. Since the antifungal efficacy of clotrimazole in soft liners has been approved, it is necessary to determine its effect on the physical properties of soft liners.Purpose: Determination of the tensile bond strength of the silicone soft liner (GC-Extrasoft) containing clotrimazole to the acrylic denture base, when the specimens are stored in distilled water and washed daily with wet cotton, was the goal of this in vitro study.Materials and Method: Forty two pairs of acrylic base (3cm length and surface area of 10 mm2) were prepared. The specimens were divided into 2 equal groups of control and case, each consisting of 21 specimens. Silicone soft liner was added between them with a thickness of 3 mm after treating the acrylic surface with isopropyl alcohol and application of adhesive layer. Clotrimazole 1 %by weight was incorporated into soft liner in the case group. The control group consisted of S1, S30, S60 and the case group of Sc1, Sc30, Sc60 that were stored in distilled water and washed with wet cotton for 1, 30 and 60 days, respectively. Tensile bond strength was measured by universal testing machine at a cross head speed of 10 mm/min. seven specimens of the groups were evaluated each time. Finally, the results were analyzed, using Two-Way ANOVA. Results: The means and standard deviations of tensile bond strengths in the control group after 1, 30 and 60 days were 0.52±0.19, 0.58±0.28, 0.60±0.25 and were 0.60±0.32, 0.50±0.18 and 0.55±0.42 in case group, respectively .There was no statistically significant difference in tensile bond strength between control and case groups (p >0.05).Conclusion: No significant effect on tensile bond strength of the soft liner into the acrylic denture base was seen by adding clotrimazole to the silicone soft liner (Gc-Extra soft) after 1, 30 and 60 days of storage in distilled water and cleaning with wet cotton.

Statement of Problem: Pit and fissure sealants and topical fluoride are the most important methods to prevent caries in children and adolescents .It was assumed that application of fluoride materials has a negative effect on the bond of adhesive materials such as fissure sealant to teeth .If this is not proved then fluoride therapy can be done before fissure sealant at the same session. Purpose: The aim of this study was to evaluate the effect of topical fluoride application prior to acid etching on the retention of pit and fissure sealant.Materials and Method: In this experimental in vitro study 28 extracted human permanent premolars were used. Each tooth was embedded in dental stone so that the buccal surface was perpendicular to the long axis of the stone block. The teeth were randomly assigned to two groups (n =14). The facial surfaces of all the teeth were freshened by 600 grit silicon carbide paper. The specimens were cleaned with rubber cups and aqueous slurry of pumice, and then rinsed and dried .In the test group, APF gel was applied on the enamel surface and left for four minutes. Then, it was rinsed for 15 seconds .In both groups, etching was done with 37 %phosphoric acid for 30 seconds, followed by a water spray wash for 30 seconds and drying for 15 seconds .The fissure sealant, Helioseal F, was then applied to the etched enamel, using a cylindrical plastic tube (3mm × 3mm) perpendicular to the buccal surface. The sealant was cured. The plastic matrix was carefully removed and the specimens were placed in distilled water for 72 hours .Shear bond strength was evaluated, using a universal testing machine. A shear force was applied to the tooth at a cross-head speed of 1 mm/min. Data were analyzed with Mann-Whitney test.Results: The mean shear bond strength was 17.7±5.28 for the control and 19.66±4.27 Mpa for the test group .There was no statistically significant difference in the shear bond strengths between the two groups (p >0.05).Conclusion: The results of this study showed that application of fluoride does not affect the shear bond strength of fissure sealant to the enamel.

Statement of Problem: Formocresol is one of the most common pulpotomy madicaments in the primary teeth. Because of its systemic and local side effects, it may be essential to use another material instead of formocresol. Purpose: The purpose of this study was to assess the pulpal response after pulpotomy in the primary teeth using 3 different agents: formocresol, ferric sulfate and Iranian MTA.Materials and Method: In this randomized clinical trial, 30 teeth of 14 children that were to be extracted because of orthodontic treatment were selected. These teeth were divided randomly into three groups of 10. The teeth in each group were pulpotomized with formocresol, ferric sulfate and MTA, respectively, these teeth were extracted after 2 months and the pulpal responses were evaluated according to the degree of inflammation and extent of pulpal involvement. Dentinal bridge formation was also evaluated. Finally, the data were analyzed with Kruskal-wallis and sign test.Results: In the formocresel group, moderate and severe inflammation was seen in 5 cases, necrosis in 4 cases, and abscess in 1 case. In the ferric sulfate group, moderate and severe inflammation was seen in 5 cases, necrosis in 1, abscess in 1, and internal resorption in 1 case. In this group, dentinal bridge was formed in 1 case. In the MTA group, severe inflammation was seen in 1 case and dentinal bridge formation in 7 cases. Kruskal-wallis test revealed that inflammation in the MTA group was less than that of formocresol and sulfate ferric, significantly (p < 0.05). Sign test showed that dentinal bridge formation in the MTA group was more than that in formocresol and ferric sulfate, significantly (p < 0.05).Conclusion: Based on the results of this study, Iranian MTA can be used in primary teeth pulpotomy.

Statement of Problem: Odontogenic cysts and tumors are lesions that are found exclusively in the mandible and maxilla. These lesions are one of the main causes of jaw destruction. But unfortunately only a few studies have been conducted in Iran on relative frequency of these lesions.Purpose: The aim of this study was to determine the relative prevalence of odontogenic cysts and tumors in Kerman province along with age, sex and site of presentation over a 12-year period and to compare it with previous reports from different parts of the world.Materials and Method: This research reviewed 1320 biopsies in a 10 -year period. Data on factors such as age, sex and location of the lesions were extracted from pathology reports and analyzed by SPSS statistical software. Results: Of 1320 specimens, 221 were diagnosed as odontogenic cysts and 24 biopsies were diagnosed as odontogenic tumors. Odontogenic cysts and tumors occurred most frequently in the first to second decades of life and most commonly in the mandible. Cysts were more common in men than women. Radicular cysts were the most common ones (33.9%), followed by dentigerous cysts (21.7%) and odontogenic keratocyst (15.4%). The most prevalent odontogenic tumor was ameloblastoma (41.4%).Conclusion: Our study provides demographic data on odontogenic cysts and tumors in Kerman province. Odontogenic cysts have a predilection for certain ages, sexes and sites. To determine the real relative frequency of odontogenic tumors, further studies should be conducted, especially in Iran, by experienced pathologists in the field of odontogenic tumors.

Statement of Problem: Utilization of denture cleaning solutions and toothpastes are common methods of cleaning the denture surfaces, which can increase the surface roughness of acrylic dentures.Purpose: The aim of this study was to evaluate the effect of two cleaning agents in the form of solution and paste on the surface roughness value of denture following tooth brush application.Materials and Method: Thirty acrylic discs with 20 mm diameter and 2 mm thickness were made and uniformly polished .These discs were randomly divided into three groups, each comprising ten discs .The roughness value (Ra) was measured, using talysurf.10 .The discs in the first group were brushed using tooth paste and brush. The discs in the second group were first brushed using water and tooth brush, and then immersed in cleaning solution for 92 hours .The discs in the third group (control) were only brushed using water and tooth brush. For all the groups, tooth brushing abrasion test was performed with 200gr weight applied. The surface roughness of each specimen after 10.000 strokes was determined. Data were analyzed with ANOVA and post hoc Tukey test (a =0.05). Results: An increase in the surface roughness was observed for all groups .However, surface roughness in the first group, for which tooth paste had been used was significantly increased as compared to the other groups (p= 0.01). But there was no significant difference between the other two groups (p >0.05).Conclusion: Denture cleaning materials in the form of solution produce less surface roughness as compared to the ones in the form of pastes.

Statement of Problem: Dental Unit Water Systems (DUWS) have been demonstrated to be contaminated with biofilms. This biofilm could be a site for growth and colonization of pathologic microorganisms. Purpose: The aim of this research was to measure the Total Cultivable Flora (TCF) in DUWS of Khorasgan dental school and the effect of stabilized chlorine dioxide on its reduction.Materials and Method: In this research, 60 samples of water from high speed turbines, air-water syringes, cavitrons and wash basins were collected. The samples were cultured in agar nutrition media and incubated for 5 days. After the incubation period, colonial counting was done by HPC method. In the next stage, stabilized chlorine dioxide was added in a container for each unit and the samples were taken from air-water syringes, cavitrons and turbine outlets .As for the first stage, after 5 days of culture and incubation, the samples were observed under microscope for counting the bacterial colonies. Kruskal-Walis and Mann-Whitney tests were used for statistical analysis.Results: A high level of bacterial contamination (more than 200 CFU) was observed in high speed turbines, air-water syringes, cavitrons and wash basins. The highest colonial count was observed from cavitron and the lowest from washbasin outlets but the difference was not statistically significant .After using chlorine dioxide, the amount of bacterial colonies was significantly reduced (p <0.05). Conclusion: The amount of bacterial contamination in DUWS of Khorasgan dental school was higher than the accepted level .These bacteria were mainly opportunistic .The addition of an anti-bacterial agent in the DUWS will significantly reduce the bacterial count to an acceptable level.

An 11 year old boy was referred to Mashhad dental school for his several oral ulcers with recurrences from 4 years ago. After clinical examinations, the diagnosis was recurrent aphthous stomatitis. Laboratory findings showed anemia, a high degree of ESR and positive CRP.Moreover, he sufferred from periodic abdomenal pain after eating and loss of weight. This associated clinical signs and laboratory changes required more comprehensive search about possible systemic diseases which can have similar oral manifestations .So, with this objective, he was referred to a specialist for considering his digestive signs.The findings of the colonoscopy revealed that the entire colon was normal but there was increased thickening as well as edema of the terminal mucosa. In the transit of the small bowel, thinning of the distal ileum and loop of geogenum were seen. Also, an increase of the terminal ileum loop was shown. In the serologic finding (ASCA), Anti- Saccharomyces Cervisia was positive.Due to the pain of ankle’s leg which then occurs in the sacral region, a decrease of bone density was seen in the MRI. All of these finding approve our strong suspicion to Crohn's disease .Now, he is under treatment by a gastroenterologist.