Journal of Dental School
Year:2008 | Volume:26 | Issue:1 (75)|Papers Count:17

Background and Aim: A large number of instruments and techniques have been introduced for preparation of canals, specially in curved canals. It's claimed that FlexoFile Golden Mediums can provide more proper canal preparations.This study aimed to evaluate the efficiency of FlexoFile Golden Mediums in decreasing apical transportation during preparation of simulated curved blocks.Methods & Materials: In this experimental study, fifty simulated resin blocks with 40° curvature were divided in two groups. 25 canals were prepared using K-FlexoFiles and the others were prepared using K-FlexoFiles and FlexoFile Golden Mediums. Ant curvature Passive Stepback technique with pull and push motion were applied for both of the groups. The amount of resjn removal from inner and outer walls of the canals was measured by using superimposed computerized pre and postoperative photographs. Results were evaluated by Mann - Whitney statistical analysis. Results: The amount of resin removal from the inner and outer walls of the canals was assessed milimetric in 11 mm length from the apex. In the three areas of 7, 8 and 9 mm from apex, the amount of resin removal from the outer wall in the experimental group was more than the control group (P<0.05). There was no significant difference in the other areas both in inner and outer walls between two groups.Conclusion: FlexoFile Golden Mediums in spite of using more instruments, had less apical transportation,  and are recommended for preparation of curved canals.

Background and Aim: The prevalence of Cl II malocclusion with tongue thrust and open bite is high. The pressure of the tongue during swallowing and its physiological activity could be transferred to the maxillary complex by the tongue crib and might advance the maxilla to an unfavorable position. This study aimed to evaluate the dentoskeletal change in the Cl II division 1 patients with anterior tongue thrust and mandibular deficiency treated by mandibular tongue guard, from a private office and orthodontic department of Azad University in Tehran.Methods & Materials: The sample consisted of 23 patients, (14 females aged 8 years and 9 months and 9 males aged 10 years and 6 months), with Cl II div 1 malocclusion in late mixed dentition with anterior tongue thrust. The patients were treated by mandibular tongue guard. Lateral Cephalograms were obtained and traced before and after treatment and certain angular and linear variables were measured. The pretreatment and post treatment measurements were compared using Paired t test to evaluate the significance of the results.Results: The findings indicated that SNB, facial angle, the distance between B and Pogonion to the reference line and Interincisal angle were significantly increased (P<0.05). The changes were mainly caused by mandibular growth, were observed after treatment by mandibular tongue guard. Decrease of IMPA, l-SN, ANB, Wits were significant (P<0.05). The changes of Jarabak index, SN-MP, SNA, Y-axis were not significant. Conclusion: In Cl II div 1 patients with mandibular deficiency combined with tongue thrust, mandibular tongue guard caused slight increase in mandibular growth.

Background and Aim: Using fluoride mouthrinses is one of the most effective ways for prevention of dental caries. For obtaining this benefit, the ministry of health has started using sodium fluoride mouthrinse in primary school children. The aim of this study was evaluation and comparison of salivary fluoride after using Kimia and Share Daroo mouthrinse.Materials & Methods: In this experimental study, 42 physically and dentally healthy children, used 10 ml of 0.2% sodium fluoride mouthrinse for 1 minute and then expectorated it. Unstimulated whole saliva (in five minute intervals) was taken in baseline, and after 5, 15, 25 and 45 minutes. 7 days after taking the first test, the second test was taken by using the second mouthrinse. After the collection of all of samples, the content of fluoride and volume of samples was determined and the results were statistically analyzed by using the 2-way repeated measure ANOVA.Results: Fluoride concentration of saliva after using Kimia mouthrinse was 0.95±0.17 and 0.198±0.18 after using Shahre Darou mouthrinse. Fluoride concentrations of saliva after using mouthrinse, was not statistically significant between the gender and the two ages.Conclusion: Results of this study showed that no statistically significant differences of fluoride retention in children's saliva exist between the two Iranian 0.2% sodium fluoride mouthrinses.

Background and Aim: Due to the disadvantages of self cure composites, application of light cure composites is suggested in orthodontics but light transmission through metal brackets is in doubt. The aim of this study was to compare shear bond strength (SBS) of Ideal Maccoo and Brilliant composites in bonding steel and ceramic brackets.Methods & Materials: Eight intact first upper premolars were collected for this experimental invitro study and randomly divided into 4 equal groups. The buccal surfaces were etched and cured by visible light after applying margin bond resin. In the first group Ideal Maccoo composite was applied on the steel bracket base (SI group), bracket positioning in the correct location was done and then curing was performed by visible light for 40 seconds (20 seconds from occlusal and 20 seconds from gingival). In the second group fascination ceramic brackets with Ideal Maccoo composite (CI group), in the third group ceramic brackets with Brilliant composite (CB group) and in the fourth group steel brackets with Bralliant composite (SB group) were bonded to teeth with the same method. SBS was measured by Zwick testing Machine. To compare the groups, Kolomgrov-Smironov, two way analysis of variance, one way analysis of variance and Tukey tests were used. Results: Mean SBS was 9.7±3.37, 7.36±4.40, 5.58±2.21 and 12.36±5.77 in SI, CI, CB and SB groups respectively.  Tukey test showed significant difference between SB and CB groups (P<0.001), no significant differences was detected between CI and SI, SI and SB and between CI and CB.Conclusion: Ideal Maccoo and Brilliant light cure composites had good capabilities in steel bracket bonding whereas ceramic brackets had lower shear bond strength. In bonding ceramic brackets only Ideal Maccoo composite showed acceptable results.

Background and Aim: Microleakage is an important problem for amalgam restorations and causes teeth discoloration, pulp irritation, sensitivity and caries. The aim of this study was to determine and compare the in vitro micro leakage of 3 different dental amalgams with commercial names (Cinalux, Dentam, SS White) using a dentin bonding agent (Excite) and a cavity varnish (Compalite), in class V amalgam restorations.Methods & Materials: Class V preparation measuring 3x2x2 mm were cut on the facial surfaces of 78 freshly extracted human premolar teeth. The teeth were divided into 3 groups of 20 teeth and 2 groups of 9 teeth as positive and negative control. They were restored using the material of choice following manufacture's instructions, and thermo cycled between 4±2C° and 54±4C° for 700 cycles in 105 seconds. The teeth were subsequently immersed in methylene blue dye and sectioned to allow assessment of microleakage with stereomicroscope. The obtained data were analyzed by Kruskal-wallis and Mann-Whitney U tests. Results: Non-parametric statistical analysis showed significant differences between 3 different amalgams when the cavities lined by Excite (P<0.05). There was no significant differences between 3 different amalgams when the cavities lined by varnish.Conclusion: These results suggested dentin bonding agents reduced microleakage in comparison to varnish, and the type of amalgam is effective on microleakage.

Background and Aim: Intraoral repairs often involve bonding composite to fractured PFM crowns. Newer adhesive systems currently referred to as multipurpose systems are capable of bonding to enamel, dentin, metal and porcelain.The Adper Scotchbond Multipurpose Plus system (ASMP) is as one of the systems using in repair procedures. Most studies observed significant differences between early and late bond-strength results. This study evaluated the effect of thermal stresses on shear bond strength of composite resin to Supercast alloy by using different surface treatments including etching, sandblasting and combination.Methods & Materials: In this invitro experimental study composite cylinders were bonded with ASMP to the 60 surfaces of alloy that were treated with etching (groups 184), sandblasting (groups 285) or combination of both (groups 386) following the manufacturer instructions. In each group, groups 4, 5 and 6 were thermo cycled intermittently in 5 & 55 C°. Groups 1,2 & 3 were stored in 37C° distilled water. Shear bond strengths were measured and compared by loading each specimen in shear to failure in an Instron testing machine. Data were analyzed using two-way, ANOVA and Duncan tests.Results: The mean shear bond strengths in groups 1 to 6 were respectively: 1.84±0.49, 4. 77±0.77, 17.97±3.59, 1.08±0.62, 1.98±0.81, 12.77±2.38 (MPa). There were significant differences between the study groups (p<0.001).Conclusion: Thermo cycling significantly reduced the bond strength of composite resin and Super cast alloy. The bond strength of composite resin increased when the combination of sandblasting and etching used for surface treatment.

Background and Aim: One of the most challenging procedures in restorative dentistry is fitting the color of the restoration to the tooth. The main purpose of this study was to determine the ability rate of color matching among the students of Yazd faculty of dentistry in December 2004.Methods and Materials: In this descriptive study, 127 dental clinical students of Yazd faculty were participated. Age, gender, wearing eyeglasses or lens and the year of starting the dental faculty were assessed as variable. Heliomolar composite with 16 colors was used to make the shade guide and 6 colors of the same composite were used as test group. The students were matched the shade guide with the test group in similar conditions. The data was analyzed by t, ANOVA and LSD test.Results: Mean truth definition of all colors in 20-29 years old students were 3.86 and in 30-40 years old group were 3.38 and there was no significant differences between them. Mean truth definition in male group was 3.57 and was 3.91 in females. There were no significant differences between them. Mean truth definition in all of the colors by students without eyeglasses or contact lens were 3.98 and the other group was 3.55 which was significantly differences (P=0.023). The difference between the entrance year for mean truth definition of all colors was significant (P=0.016).Conclusion: In this study, the students whom specially wear photochoromic eyeglasses or contact lenses were lower truth color definition, but age and gender had no effect on truth color definition.

Background and Aim: In order to improve the aesthetics and functional quality of restorations, the combined amalgam-composite restorations have been introduced. The aim of this study was to compare different reinforcement methods, in weakened buccal walls of premolar teeth.Materials & Methods: In this in vitro study, 70 similar and intact premolar teeth were used. The specimens were divided into seven groups of ten. In six groups, the three reinforcing materials composite (A), Compo glass F (B) and glass ionomer (C) with two methods: I: buccal and distal wall reinforcement. II: buccal, distal and pulpal floor reinforcement was used. In the seventh group (D), the Scotchbond M.P.P adhesive as a control group was applied.Then specimens were restored conventionally with amalgam and submitted to 500 thermal cycles (5°C-55°C). The specimens were loaded through Instron testing machine at a crosshead speed of I mm/min with angle of 45 degree. Statistical analyzes of ANOVA, Duncan and chi- square tests were used to analyse fracture strength, location and type of fracture.Results: The highest strength was detected in group with composite reinforcement on buccal and distal walls and pulpal floor. The highest failure mode was adhesion type and observed in composite reinforcement and control group.The highest cohesive and mixed failure mode was respectively observed in Compoglass and glass ionomer groups. Conclusion: This study showed that composite resin was the best material for reinforcement of weakened walls with favourable aesthetic property.

Background and Aim: The incidence of maxillary canine impaction is between 1% and 3% populations. Determining whether impaction will occur and timing the treatment modalities that are affected by impacted canine(s) are paramount for a successful outcome, panoramic radiograph to identity canine impaction; not only is economical but treatment result will be more desirable. The aim of this investigation was to develop a reliable method for predictors of maxillary canine impaction on a panoramic radiograph.Methods & Materials: Sixty- four panoramic radiographs of mixed dentition patients were inspected to belong to two groups of patient with impacted and not impacted canines. 88 were found with no impaction and 40 with impacted canines. For predicting canine impaction panoramic radiographs were inspected for two indices:1- The erupted lateral tooth were divided to fourfold zone from 4 to 1 sectors in mesiodistal dimension; therefore identified the unerupted permanent canines cusp tip location related to the erupted permanent lateral.2-The internal angle between the long axis of the unerupted canine and a horizontal line between superior points of condoles was measured. The data were analyzed by descriptive statistics and logistic regression. Results: All of not impacted teeth were found in sector I and II. (69.3% in sector I and 30.7% were placed in sector II). 17.5% of impacted teeth were in sector I, 42.5% in sector II, 27.5% in sector III and 12.5% were placed in sector IV. Furthermore the mean angle for non impacted teeth was 74.72' and for impacted teeth were 67.12.Conclusion: The location of canine cusp tip in panoramic radiograph is the most important factor in predicting probable impaction, but often, the angle of canine is not worth.

Background and Aim: The knowledge about the anatomic variation pulp cavity, specially in multi-rooted teeth, is an important factor for diagnosis and successful endodontic treatment. Root canal treatment of 4-rooted maxillary second molars has been described in only a limited number of case reports. The purpose of this case report was to illustrate and describe the endodontic treatment of a 4-rooted maxillary second molar.Case Report: A 20-year-old female with no history of systemic disease was referred for treatment of her upper left second molar tooth. The diagnostic radiographies revealed root anomalies. After access cavity preparation, presence of four orifices in the pulp chamber was confirmed; each of them related to a distinct root. Root canal therapy was performed completely in all four roots.Conclusion: This case report indicates that the clinicians must be aware of anatomic variations during the diagnostic and treatment phases of maxillary molars, and proper root canal treatment should be performed respecting the presence of challenges in pulp space anatomy.

Background and Aim: Using implant to replace missing teeth is dependent on bone quality and quantity. One of the ways to achieve better bone quality and quantity is using grafts such as autogenos bone, Bioss and demineralized dentin. The aim of this research was to study the histomorphometric effect of dematerialized dentin on increasing bone quantity and ossteointegration in tibia bone of rabbit.Methods & Materials: In this experimental study five white New Zeeland female rabbit were obtained and a 3.5 mm hole was created to insert implants. One implant was inserted in each tibia so each rabbit hade two implants. A 6 mm defect was made at the distal of that hole. These defects contained two cortical layers. One of these defects was filled with autogenous demineralized dentin (ADDM) and the other one was left empty. Each defect was covered with collagen membrane. Rabbits were sacrificed in 3, 5, 7, 9, 11 weeks and two samples were obtained from each rabbit.The samples were decalcified, their implants were removed and send to laboratory for histologic and histomorphometric assessment.Results: Histomorphometric evaluation showed equal bone to implant contact (BIC) in cortical layer in both groups. The mean BIC in bone marrow of experimental group was more than the control group in different weeks (Addm= %19, control=%0). The mean surface of new bone within threads (NBT) in different weeks in ADDM group was greater than controls (ADDM=%35 control %23.6).Conclusion: In this study histomorphomeric ADDM caused new bone formation in bone marrow around implant and osteointegration was increased.

Background and Aim: The loss of tooth substance has been the concern of specialists for many years, but the role and impact of erosion in the form of loss of tooth substance is related to consumption of acidic food - staff, by youngsters, which in currently the point of concern amongst other problems. This research was aimed at evaluating the epidemiology of dental erosion amongst high school girls, aged between 14-17, who were living in the city of Ghazvin, Iran.Methods & Materials: The present study has been carried out on the basis of descriptive criteria, using cross sectional method. For this purpose, a sample of 368 female students from 6 high - schools, located in three different residential zones of Ghazvin have been randomly selected. The conducting of the survey was mainly followed the method based on observations and interviews. The questions asked on the questionnaire were aimed at nutritional diet, drugs, swimming, para-functional habits and socio-economic status of these students. A full examination of upper and lower anterior teeth after drying them under proper light was carried out. Used index was Eccles & Jenkins. Data were analyzed with SPSS analysis program and Pearson correlation test.Results: The prevalence of erosion amongst the population under study was 14.4 percent. The most common affected teeth were maxillary central incisors (labial surfaces). No significant relationship was found between risk factors and prevalence of erosion.Conclusion: With regards to the high prevalence of erosion and their treatment problems, exact follow up concern is recommended.

Background and Aim: peripheral soft connective tissue lesions are common in oral mucosa and despite their benign nature can make problems for patients. According to our knowledge, a comprehensive study for these lesions was not performed in Iran. General practitioners are commonly encountered affected with these lesions. They have not enough information about their clinical prevalence, may make mistake in diagnosis and treatment plan. The aim of this study was to evaluate peripheral soft connective tissue lesions prevalence in patients referred to Pathology department of Shahid Beheshti Dental School during 1981-2006. Methods & Materials: In this descriptive retrospective study (existing data), cases were patients that referred to Pathology Dept. (1981-2006) with complete files recorded in the Dept. Questionnaires included age, sex, location of lesion and lesion type which were retrieved from patient's files. The incomplete files were excluded. Finally the collected data were analyzed descriptively by SPSS Ver 11.0 software.Results: A total number of 900 cases had peripheral soft connective tissue lesions during 1981-2006 from 4529 files in the department. 29.7% (268 cases) were irritation fibroma, 21.9% (197 cases) were peripheral giant cell granuloma, 19.5% (176 cases) were pyogenic granuloma, 19.3% (174 cases) were epulis fissuratum, 8% (72 cases) were peripheral ossifying fibroma, 0.5% (5 cases) were giant cell fibroma, 0.4% (4 cases) were oral focal mucinosis and 0.4% were inflammatory papillary hyperplasia. The most prevalent age was 50-59 years (18.1%) and 20-29 years (16.3%). The lesions were more prevalent in women (61.9%) and were 38.1% in men. The most prevalent site was gingival (54.3%) and the least prevalent site was floor of the mouth (0.1 %). Conclusion: 19.9% peripheral soft connective tissue lesions were reported, the most frequent lesion was irritation fibroma that was similar to other reports.

Background and Aim: Nowadays cephalometric software have become very popular, but due to racial and ethnical difference in facial soft and hard tissue features the norms should be adapted for each nation. The purpose of this study was to establish soft and hard tissue data base for 9 to II years Iranian children and to compare it with Legan and Ricketts dentofacial planner plus norms for American Caucasians.Methods & Materials: This was a longitudinal descriptive study on 60 cephalograms of normal 9- II years Iranian children in city of Qazvin. They were selected as normal occlusion cases according to Moyer's. The cephalograms were scanned and 13 landmarks for Legan soft tissue and 32 landmarks for Ricketts hard tissue analysis were digitized. Then by means of Dentofacial planner plus II measurements were calculated for each age group (20 in each age 9, 10, 11 years). The mean for each landmark was compared to American Caucasian norms in the databank by Paired t test.Results: Nine years old Iranian girls had more facial convexity, nasolabial angle, upper & lower lip protrusion and height of midface but their lower face height was less. In boys, middle face height was the same as American's and nasolabial angle differed less. In II year old girls the difference between lower face height and lip protrusion became less, boy's nasolabial angle was more than American's.Conclusion: Significant differences were present in soft and hard tissue norms of Iranian's in comparison to American Caucasions. Iranian data base for cephalometric norms should be established.

Background and Aim: Decalcification of the teeth remains a problem during orthodontic treatment with fixed appliances. It has been suggested that fluoride-releasing glass ionomer cements could decrease the risk of enamel decalcification under orthodontic bands. The objective of this study was to compare enamel fluoride uptake from three different glass ionomer cements (AquaCem, Resilience and Bandite) used for band cementation in permanent teeth in vitro.Methods & Materials: In an experimental in vitro randomized trial, 33 sound premolars that were extracted for orthodontic purposes were randomly divided into three groups. In each group one of the glass ionomer cements was tested. A 6 mm diameter adhesive tape was placed over the center of buccal enamel surface of each tooth and then the entire surfaces of them were painted with two layers of an acid protective nail polish. After removing adhesive tapes, brackets were cemented with one of the cements over the window. Then all the specimens were immersed in 5ml deionized water for one month. Brackets were deboned and remnants of cements were removed. The windows were etched with 1ml perchloric acid 0.5M for 60 seconds and then 4 ml of 0.5 M Total Ionic Strength Adjustment Buffer (TISAB) was added to perchloric acid. Fluoride and calcium concentration of the solutions were determined by Potentiometer and Inductively Coupled Plasma, respectively. The depth of etch and fluoride concentration in the enamel were calculated, and the results were analyzed with one way ANOV A and Kruskal-Wallis test.Results: In Resilience the mean fluoride concentrations group were higher and depths of etch were lower than in the other two groups. But there was no statistically significant difference between them.Conclusion: It seemed that an increase in fluoride uptake may be capable of rendering a tooth more resistant to dental decalcification.