Journal of Mashhad Dental School
Year:2007 | Volume:30 | Issue:3-4|Papers Count:25

Introduction: Recently, the Nickel-Titanium rotary instruments have been noticed because of their desired properties such as high flexibility, less transportation and perforation and less time consumption. Therefore, the aim of this study was to compare the cleaning efficiency of these instruments with hand stainless steel (SS) and Nickel–Titanium (NiTi) files.Materials & Methods: In this invitro experimental study 46 freshly extracted human molars with the curvature of 15-25 degree in mesial root were used. The teeth were randomly divided into 4 experimental groups, each containing 11 teeth and two control teeth. Then mesial canals were instrumented as follows: group 1: step back instrumentation with stainless steel hand files.group 2: passive step back instrumentation with stainless steel hand filesgroup 3: step back instrumentation with Nickel- Titanium hand filesgroup 4: crown down instrumentation with rotary Profile systemNo instrumentation was done on two control teeth. After crown amputation of teeth, the mesial roots were split in half and one half was randomly selected for SEM investigation. After SEM preparation, the photomicrographs were prepared from apical, middle and cervical part of canal with magnification of 2000 under SEM. These graphs were scored by an endodontist in a blind manner, according to the amount of residual debris and smear layer on canal surface. Then, the data was analyzed by Kruskal-Wallis and Mann-Whitney tests.Results: The difference between 4 groups was not statistically significant according to the amount of residual debris (P>0.05). But, rotary Profile system had produced more smear layer than other three groups (P<0.01). This study showed that the amount of residual debris and smear layer after canal preparation in apical third is more than middle third and in middle third is more than cervical third (P<0.01).Conclusion: After using the rotary instrumentation, it is better that canals were finally irrigated with combination of 17% EDTA and 5.25% NaOCl to remove the smear layer.

Introduction: The human tooth has a lot of anatomical variation and adequate information of root canal anatomy is an important factor in successfull root canal therapy. The purpose of this study was evaluation incidence of second canal in distal root of inandibular first and second molars.Materials & Methods: In this descriptive invitro study, 100 extracted human extrated first and second mandibular molar used then; distal roots resected from CEJ. After removal the pulp tissue, teeth stored in 30% hydrogen peroxide for 48 hours. Root canal system was studied with dye penetration and serial horizontal sectioning methods.Results: There were 16% and 18% two canals in distal root of mandibular first and second mandibular molars. Different type of canals in distal root of first mandibular molars was observed as follow: 10% type IV and 6% type II. Different type of canals in distal root of second mandibular molars was as follow: 2% type IV, 2% type III, and 14% type II.Conclusion: With attention to the results of this study about incidence of second canal in distal root of mandibular molars careful exploration is necessary for finding of extra canals.

Introduction: Since maintaining good oral hygiene in fixed orthodontic patients is more difficult compared to normal individuals more serious methods for plaque control is needed. One way to improve oral hygiene and gingival health is chemical plaque elimination by means of mouthrinses. The aim of this study was to compare the effects chlorhexidine and Persica mouthrinses on periodontal status of patients undergoing fixed orthodontic treatment.Materials & Methods: 38 cases with the mean age of 14.2 years were selected among the patients who were refered to Mashhad Dental School for orthodontic treatment. 14 patients were eliminated for different reasons. In all patients before and three months after bonding orthodontic attachments gingival index, gingival bleeding index and mean pocket depth were measured. Then the patients were divided into three groups: for the first group chlorhexidine and for the second group Persica was prescribed. The third group did not receive any mouthrinse and was mentioned as control group. 30 days after using mouthrinses all of the indices were measured for the third time. SPSS software was used for data analysis and after confirming normal distribution of these data, paired t-test and ANOVA with 95% confidence interval were used.Results: Gingival index, plaque index and mean pocket depth showed significant increase after beginning orthodontic treatment. Gingival index had a significant reduction in all groups after prescribing mouthrinses but this reduction was not significant between three groups. Mean pocket depth in chlorhexidine group and gingival bleeding index in Persica group had significant reduction. Plaque index did not show significant reduction in any of three groups.Conclusion: Most of the indices show significant increase after bonding of fixed orthodontic appliances. This emphasizes the need for more serious methods of oral hygiene control during orthodontic treatment. Since plaque index and gingival index did not show significant decrease in patients using chlorhexidine or Persica mouthrinses in comparison to control group it is concluded that correct tooth brushing and flossing are the main factors in plaque elimination and gingival health and mouthrinses could be used as an adjuctive.

Introduction: A paramount objective of modern orthodontic therapy is the improvement of facial esthetics. Orthodontic treatment can cause an attractive smile through change in position of the anterior teeth. Thus the purpose of this study was to determine the standards of the beautiful smiles and also the effects of non extraction orthodontic treatment on smile esthetics.Materials & Methods: Sixty three women, 30 with non extraction orthodontically treated occlusions and 33 with normal occlusion were selected. Five standardized black and white close- up image of their posed smiles were taken and then the most natural photograph of each case were selected. At next selected photographs were evaluated by a panel of five men and five women of varied vocations. They were told to rate each photograph as to the attractiveness of the individual smile with visual analogue scale.Results: This study showed 27.3% of normal occlusion females with out history of orthodontic treatment had very good, 57.6% had good and 15.1% had fair smiles. But in none extraction orthodontically treated group 10% had very good, 76.7% had good and 13.3% had fair smiles. As the result of the panel members evaluations, orthodontically treated subjects and subjects with normal occlusion had similar smile scores. Furthermore smile line ratio, buccal corridor ratio and symmetry ratio were not significantly different between two groups. On the other hand, there was no significant difference in smile morphometric indices between fair, good and very good smiles.Conclusion: This study demonstrates that the smile line, buccal corridor and symmetry of smile do not influence smile esthetics and also orthodontically treated subjects and subjects with normal occlusion had similar smile esthetics.

Introduction: Alveolar bone level is changed due to the balance between bone formation and resorption. Precise examination of alveolar bone is done by clinical and radiographic methods. Radiographic examination has an important role in diagnosis and treatment of periodontal patients, so this study was performed to determine the accuracy of bitewing radiography in alveolar bone resorption. Materials & Methods: This analytical and cross-sectional study was performed in 37 interdental osseous wall of patients who referred to the periodontology department of Babol dental faculty for periodontal surgery in 2004. Vertical bitewing radiography was done in premolar and molar region by use of Snap-A-Ray film holder. A caliper with accuracy of 0.05 mm was used for measuring the level of interdental bone resorption on cliche. During periodontal surgery the amount of bone resorption was measured by Williams probe. Then datas were analyzed by paired-t-test and Pearson correlation coefficient and linear regression. Results: The mean value of alveolar bone resorption with Williams probe and bitewing radiography was 2.66±1.2 and 2.81±1.06 in maxillary molars, 2.31±0.75 and 2.5±1.6 in mandibular molars, 1.73±1.03 and 1.93±0.97 in maxillary premolar and 1.91±1.11 and 2.25±1.59 in mandibular premolars respectively. Conclusion: According to the results, bite wing radiography had high accuracy in measuring the amount of alveolar bone resorption. So, this method can help to diagnose and determine treatment plan of periodontal disease.  

Introduction: Today use of chelater materials such as RC Prep for easy root canal preparation with rotary instruments has been increased. According to the importance of apical seal and probably influence of instruments and materials on apical constriction size, the aim of this study was to evaluate the effect of RC Prep on apical leakage.Materials & Methods: In this experimental invitro study the crown of 66 single-root extracted human adult teeth with minimum root curve and same diameter were resected and divided to 3 experimental groups and two control groups (test groups: 20 teeth, control groups: 3 teeth). The working length determined 1mm from the apex. The canals were prepared as follow: Group A: The canals were prepared by step back technique (MAF#40) and RC Prep, irrigated by 5cc Naocl 2.6% and obturated by AH26 and gutta percha via lateral condensation.Group B: The canals were prepared and obturated similar to group A without use of RC Prep.Group C: The canals were prepared like group A, but the irrigator was saline.Root canals of control groups were prepared like group A, but the canals of group D (positive control) were not obturated. Crowns of experimental groups and negative group were sealed by glass Ionomer. Then the surface of all roots except 2mm of apical end was covered by nail polish. Teeth were incubated in 37oc and 100% humidity for 24 hours, then centrifuged in India ink for 15 minute by 3000 rpm and soaked in it for 72 hours. They were mounted in polyster and sectioned buccolingually. The dye penetration was measured by stereomicroscope with 0.1mm accuracy. The data analyzed by ANOVA and DUNCAN test.Results: The results showed that there was a statistical difference between exprimental groups (P=0.011). This difference was between groups B & C (P=0.008) and leakage was lower in group C. Groups A & B, A & C did not have significant differences, statistically.Conclusion: RC-Prep as a lubricant and chelator doesn't have any effect on apical leakage and is useful for canal preparation by instruments.

Introduction: The first permanent molars erupt very slowly in distal surface of primary second molar, without any side effects, therefore in most cases children and parents are not aware of their eruption. However these teeth are predisposed to caries and need close sanitary care and parental notice. Parent's awareness about existence of first molar as a permanent tooth in children's mouth could lead the health preservation of this tooth. The main objective of this study was to consider the rate of awareness of parents about the presence of first pemanent molars and its effect on health of the tooth.Materials & Methods: This cross sectional research has been done on 844 elementary school students and their paents. Sampling was done randomaly. Then questionnaires were filled out by the parents and then tooth condition was registered in a visit form for each student separately. Next, the related children's DMFT was determinated and recorded. For statistical analysis we used Student t-test, Chi-square and Fisher exact tests (P-value<0.05).Results: 1- In these research only 201 parents (34.7%) knew about the first permanent molar eruption in their child's mouth.2- The average of restoration of first molar in students whom their parents were aware of presence of these teeth was 0.11 and in other students was 0.03.3- Among 844 7-8- years- old students, only 474 cases (55.6%) had a history of visiting the dentist.Conclusion: According to the results of this study only 13.4% of parents knew about existence of first pemanent molar in the mouth of their children. The average of molars restoration in students, whom their parents knew about it, was three times more than others.

Introduction: Today, use of composites in tooth color cosmetic restorations has been increased and many developments have been showed up in physical characteristics. Unfortunately, problems such as polymerization contraction and the resulting gap formation in different parts of the cavity, has led to restoration failure. The purpose of this study was to evaluate the effect of four different methods of restoring teeth on pulpal gap of class I composite restorations.Materials & Methods: 60 extracted human premolars were selected. In all samples, a deep class I cavity preparation was made. The samples were divided into four groups. In each group containing 15 samples, a different liner was applied.Group 1: Dentin bondingGroup 2: Dycal and dentin bondingGroup 3: Dentin bonding agent and flowable compositeGroup 4: Glass-ionomer and dentin bondingAll cavities were restored using light-cured Z-100 composite resin (3 M), using oblique incremental technique. Finally, for evaluation of the pulpal gap, the samples were observed under scanning electron microscope. The analysis was done with One Way ANOVA and DUNCAN test.Results:1- There was a significant difference in the amount of pulpal gap between the four froups (α = 0.05).2- The greatest amount of gap was related to group 1 (dentin bonding group) and the least amount of gap was related to group 3 (flowable composite group), followed by group 2 (Dycal group).3- Group 1 and group 4 were not different in the amount of pulpal gap significantly.Groups 2, 3, 4 were not different in the amount of pulpal gap, either. The only significant difference observed was between group 1 and group 2, as well as group 1 and group3.Conclusion: 1- In deep composite cavities, use of flowable composites under the composite restorations as a liner is suggested.2- Use of dycal in deep cavities as a base is also recommended due to its partially agreeable outcomes in our study.

Introduction: HTLVI virus is one of human's retroviruses which is the cause of T Lymphocytes Leukemia and spastic parpareseis or HTLVI associated myelopathy and some other inflammatory diseases, in some patients. Regarding that HTLVI is an endemic virus in Khorasan and the lack of studies and researches about its intraoral clinical signs, we decided to study periodontal status in patients with HTLVI associated Spastic Paraparesis.Materials & Methods: This was a case- control study with easy sampling that performed on about 30 patients (10 men and 20 women) with the mean age of 42 years in Mashhad dental school in 2004. Patients, whose HTLV1 involvement had been proved, took part in this study. Patients were chosen among people refered to neurology Department of Mashhad Ghaem hospital. Periodontal state, gingival disease, pocket depth, presence of leukoplakia, gingival linear erythematic, candida infection, ANUG, NUP, … were studied and three indices including Debris, Calculus Index (Green and Vermelion) and Gingival Index (Loe & silness) were recorded.Results: In the view of Debris, Calculus and gingival indices, there were significant differences between control and case groups but there were no significant differences between two groups in pocket depth, leukoplakia, candida infection, ANUG and NUP.Conclusion: The patients with HAM/TSP have higher plaque, calculus and inflammation, compered to the healthy individuals. To eliminate Plaque and prevent of gingival disease, good oral hygiene is recommended.

Introduction: Iron deficiency anemia is the most common health problem in childhood. One way to meet this important need in the body is to add iron supplement in our diet. This supplement is known as Ferrous sulfate in Iran. Teeth blackness in children especially after taking Iron drops and the parent`s dissatisfaction is one of the most important reasons for visiting a dentist. Generally, parents have an idea that taking iron drops by the children is the cause of tooth decay, therefore they limit this vital supplement in their children's diet. The aim of this study was to compare of primary enamel discoloration caused by the use of three different iron drops.Materials & Methods: Quantitative stage: In this first stage of the study, 60 anterior primary teeth were selected and the necessary preparation was made. The level of iron absorption in etch group and the intact one were determined by Atomic absorbtion in 248.3 nonometers long wave and resolution of 0.062ppm. Qualitative stage: In this stage, 7 teeth were put under scan electron microscope (SEM) after the primary preparation.Results: There was no significant difference in the iron absorption on the healthy teeth, between foreign iron drop and the one produced by Mashhad school of pharmacy. But the level of absorption in Iranian Iron drop was significantly higher (P=0.01). The absorption in etched teeth increased which might have been due to increased surface- (P=0.0001). There was no significant difference between experimental drops in the etched teeth.Conclusion: Iron drops that produced by Mashhad school of pharmacy had less discoloration on the primary enamel teeth. The more increased surface because of etching, the more change in color was observed and this was most prominent in Iranian iron drop. Color discoloration increased with frequency of iron drop intake.

Introduction: The width ratio of teeth is very important for esthetic of maxillary anterior teeth. Some dentists utilize golden proportion (1.618) as a main guidance to establish a harmonious proportion. Although the proportion has been used frequently in dentistry, it has rarely been studied, especially among Iranian population. The aim of this study was to evaluate golden proportion in a group of Iranian dental students, in Hamedan.Materials & Methods: This cross-sectional study was conducted with 165 dental students (79 female and 86 male) in Hamedan Dental School-Iran. The inclusion criteria for case selection were lack of rotation, tilt, spacing, caries, restoration or missing in anterior maxillary teeth. Photographs of the subject’s teeth were taken from frontal view. The apparent width of the teeth were measured by a digital caliper and width ratio’s of central to lateral, lateral to canine and canine to first premolar were calculated. Then data were analysed by student t-test, t-paired t-test and one sample t-test.Results: In this study the mean ratio of central to lateral, lateral to canine and canine to first premolar width on the right side were 1.489±0.153, 1.200±0.153, 1.432±0.271 respectively and 1.525±0.151, 1.235±0.170, 1.477±0.368 for the left side.Conclusion: In comparing the results and golden proportion (1.618), it was concluded that golden proportion was absent in a high percent of the subjects. Comparing the mentioned ratios showed that central to lateral width was the closest ratio to golden proportion and lateral to canine width had the lowest similarity to golden proportion. In addition, it was showed that there was not a significant difference between male and female in apparent width ratios, in maxillary antetior teeth. This study indicated that golden proportion can not be assumed as a constant ratio between the apparent widths of maxillary anterior teeth in all conditions.

Introduction: Although local anesthesia may be applied in different steps of fixed prosthodontics, patient complain about annoying pain after cord packing is sometimes reported. The aim of this study was to asses the effect of warm saline mouthwash on reduction of pain after packing cord insertion.Materials & Methods: 22 patients needing crowns for two symmetrical roots either in mandibular or maxillary molars were selected. All of the procedures for making crown on both teeth were carried out similarlly. Inter dental anesthesia was used for packing cord. After elimination of anesthesia the patients scored their pain according to VAS method (scale).Control group (all 22 patients after impression of their first tooth) used warm water mouth wash as placebo and experimental group (the same patients after impression on their second tooth) used warm saline. After using mouth wash the patients scored their pain again. The data were analyzed using a paired test.Results: The mean pain intensity score in control group was not significantly different before and after mouthwash. In test group this difference was significant (P<0.001) (table 1).Conclusion: Using warm saline (12±2gr/250cc) mouth wash for 5 minutes reduces or eliminates the pain after packing cord insertion.

Introduction: Sodium fluoride mouthrinses have been effective in preventing caries in numerous clinical trials during the past 50 years. The purpose of this study was to asses the oral retention, or ingested and urinary excretion of fluoride with the use of Naf mouthrinse.Materials & Methods: 45 school children at the ages of 6 to 12 years at a day & night (residential) nursery were selected. The amount of fluoride in their drinking water was about 0.2ppm. At the first part of study, before using mouthrinse children were instructed to brush their teeth at bedtime with non fluoride dentifrice. The salivary specimens were gathered the same night after brushing, but specimens from the urine were gathered the next morning. In the second part, the same specimens were taken after using the 0.2% Naf mouthrinse (1 minute with 5ml). The difference between amount taken orally and the one not recovered in the expectoration is amount of fluoride retained orally and potentially ingested. Fluoride concentration in the urine and saliva was measured by means of potentiometer device. The data were analysed by the statistical package of Graphpad instat and using paired sample t.test, and analysis of variance. The numerical values are shown as mean ±sd.Results: The fluoride retained during mouthrinsing ranged from 1.07 to 2.42mg F, with the average of 1.7±0.32mg F. The amount of F excreted before and after mouthrinsing was 110.56±40.46 mg and 201.27±70.45 mg respectively. The urinary fluoride excretion rate before and after mouthrinsing was 13.87±5.05 and 24.68±9.35 respectively. These results indicated that more than 1/3 of the applicated solution is orally retained or potentially ingested. There was significant difference between the amount of urinary fluoride excretion rate before and after mouthrinse application (P<0.0001).Conclusion: Amount of fluoride existing in fluoride mouthrinse might be swallod and ingested, therefore necessary caution should be consider inorder to recommend this fluoride regimen in school children. The potential ingestion may be considered unimportant, but since there are many other sources of fluoride such as dentifrices, fluoride accumulation may be a cause of increasing the fluorosis risk. So, training and teaching school personel about proper use of mouthrinse is of great priority.

Introduction: Regarding to esthetic needs of the patients and the demand for tooth colored restoration, this study evaluated the compressive fracture resistance of cuspal coverage of the maxillary premoalrs with tow types of indirect composites (Tetric Ceram HB, Targis) and one type of porcelain (IPS Empress).Materials & Methods: 32 extracted maxillary premolars were collected and were allocated in to four groups of eight teeth. The MOD cavities were prepared with following dimensions; Buccolingual width: 2/3 of cuspal tips distance, pulpal depth: 2.5mm, axial depth: 2mm, gingival floor 1mm above CEJ and 2mm reduction of cusp. One group were kept sound as control. The prepared teeth were restored with the above mentioned materials according to the manufacture’s instruction, and then they were stored in normal saline for 7-10 days. All teeth were loaded occlusally using universal-testing machine to the point of fracture. Data were anulysed by ANOVA test. Also the type's fracture of teeth was compared.Results: The fracture resistance values for all of the groups were equivalent to those obtained for the unresorted control teeth, and according to the ANOVA test, no difference were detected between fracture resistances of resorted groups (P=0.7). The mode of fracture of teeth resorted with composite onlays when subjected to compressive loading were less catastrophic than that of teeth resorted with porcelain onlays.Conclusion: Cuspal coverage of extensively weakened teeth with composites or ceramics onlays can improve fracture resistance comparable to intact teeth.

Introduction: Color stability is crucial for the success of any restorative material. Despite composites, color stability of ceromers has not been studied widely. The purpose of this study was evaluation of color stability of one type of ceromers and comparing it with porcelain and composite.Materials & Methods: In this invitro experimental study, one type of ceromers (targis), a light cured direct composite (tetric ceram) and a porcelain (vita) were chosen. The samples were evaluated in CIELAB color order system by a colorimeter in 3 stages: before UV exposure, after 100 hours UV exposure and after 200 hours UV exposures. l*, a* and b* peculiarities and their changes in examination steps were calculated. The results were analyzed by ANOVA and LSD statistical tests.Results: The results revealed the porcelain and targis had the highest and lowest color stability after 100 (P=0.05) and 200 (P=0.014) hours periods, respectively. In comparison among the different colors of ceromers, C3 and D3 had the highest and the lowest color stability respectively (P= 0.001 in 100 and P= 0.008 in 200 hours). In all of studing groups, the final color change was clinically acceptable.Conclusion: All of the groups revealed acceptable color stability and among them porcelain had the best characteristics.

Introduction: In many of orthodontic treatments of patients with jaw discrepancies it is important to understand more about the pattern of growth and eruption of teeth. The aim of this study was to compare the pattern of eruption of upper and lower second molars in class I, II and III malocclusions to select the best time and treatment mechanics.Materials & Methods: 192 panoramic radiographs from 45 class I, 97 class II and 50 class III orthodontic patients in the range of 11-12 years were selected. They were classified dentally by Angle’s classification and skeletally by cephalometric analysis. Eruption stage of second molars was determined by Nolla’s method and compared statistically X2 Pearson and Fisher exact test.Results: There was no significant difference between different malocclusions and sexes in pattern of eruption and percentage root formation of upper and lower second molars. The only significant difference was seen in girls with class II malocclusion, in which maxillary second molars were in the lower stages of eruption comparing with mandibulars (P=0.024). No significant difference was seen between right and left molars. In both sexes upper and lower second molars were in equal distances to the occlusal plane.Conclusions: There was no significant difference between different malocclusion and sexes in eruption stage of upper and lower second molars.• There was significant difference between different malocclusions and sexes in percentage of root formation of upper and lower second molars.• Exceptionally girls in with class II malocclusion, percentage of root formation in lower second molars were higher then upper second molars.• In both sexes and all types of malocclusions the distance of upper second molars to occlusal plane was more than lowers.

Introduction: One of the most widely used materials in prosthetic dentistry is polymethyl methacrylate. Despite it's popularity, the primary problem is it's poor flexural strength and low impact strength. The aim of this study was to compare the flexural strength of unreinfored heat-cured polymer (group 1) with wire-reinforced polymer (group 2) and with glass fiber–reinforced polymer (group 3).Materials & Methods: In this invitro experimental study 24 uniform specimens of 65.0×10.0×3.5 mm were fabricated as the manufacturer’s recommendation and were assigned to 3 groups of eight. In the first and second group the samples were reinforced by glass fibers and wire respectively. The samples speciemens of third group were made of heatcure resin and served as control group. All of them were loaded up to failure, using a three-point bending test, and then the flexural strength was calculated. Data were analysed by one way analysis of variance (ANOVA).Results: The results showed that wire and fiber-reinforced polymers have higher flexural strength than unreinforced polymer. The one-way ANOVA revealed significant difference between group 1 and other groups statistically (P<0.05) however, there was no significant differences between groups 2 and 3.Conclusion: Based on the achieved results, we can use wires or fibers in order to reinforce polymer, regarding that glass fibers can be used as reinforcement of denture acrylic resin in patients who care about esthetic.

Introduction: Multiple endocrine neoplasia syndromes (Type 2B) is a condition associated with systemic malignancies and posses orofacial manifestations. The oral mamifestations help clinician to diagnose disease in early ages. In this article a case is reported with MEN2B syndrome which was diagnosed on the basis of orofacial findings.Case report: An eight years old boy was refered for routine dental cares to Mashhad Dental School. In clinical examinations, multiple papules (which defined as neuroma by histopathologic examination) were found on the lip comissures, tip of the tounge and margin of lower eyelids. He had long, narrow face, high arched palate and eversion of eyelids. On the basis of oral and ocular findings, the diagnosis of MEN2B syndrome was made and the patient was refered to a pediatric endocrinologist. Thyroid scans showed cold nodules in thyroid gland which was confirmed by histopathologic examination as medullary carcinoma after total thyroidectomy. Epinephrine and neurepinephrine metabolites were high in urine analysiy setting him in suspicion to develop pheochromocytoma in future. Now the patient is under specialist control.Conclusion: Early diagnosis of MEN2B syndrome is necessary for successful treatment. The dentist may be the first one who diagnoses this syndrome by its orofacial signs. So Dentists should be aware of oral findings of this disease.