Journal of Mashhad Dental School
Year:2008 | Volume:31 | Issue:4 (63)|Papers Count:17

Introduction: One of the problems affecting the prognosis of the treatment is perforation which requires immediate and proper intervention. Dark MTA is applied as material of choice to repair perforations. The purpose of this study was to evaluate the repair of mechanical furcal perforations radiographically and clinically using white MTA and Portland cement and comparing them with dark MTA.Materials & Methods: In this experimental study, second to fourth mandibular and maxillary premolar teeth of five dogs received endodontic treatment following radiographic and clinical examinations. Then, the furcation area of the teeth was perforated and repaired with dark MTA in group 1, white MTA in group 2, Portland cement in group 3 and cotton pellet in group 4 (control). Animals were controlled for 4 months and sacrificed using an overdose of Sodium thiopental intravenous injection after radiographic and clinical examinations. Chi-square test was used to compare groups for gingival attachment and presence of radiolucency. To compare these items between each two groups, Fisher's exact test was used.Results: There was no statistically significant difference between dark MT A, white MT A and Portland cement groups in presence of radiolucency and gingival attachment. However, all the three groups were significantly different in radiolucency and gingival attachment from control group.Conclusion: Both white MT A and Portland cement revealed favourable results in repair of perforations and can be used as an alternative to dark MTA to repair perforations in the areas where esthetics is important and not important, respectively.

Introduction: Anthropology is the science of body sizes evaluation in living people. The science could be useful in diagnosis of diseases especially syndromes. Thus the aim of this study was to determine the mean value of 20 craniofacial anthropometric parameters among 20-35 year old individuals of both sexes in the city of Mashhad.Materials & Methods: This cross sectional analytical study was carried out among 160 skeletal class I adults with normal face height, including 80 men & 80 women between 20 and 35 years of age. Twenty anthropometric parameters of the craniofacial complex (16 facial and 4 cranial) were measured on each subject by use of digital sliding caliper and soft measuring tape. Finally, the mean values of these parameters were determined according to sex. Furthermore, the mean anthropometric measurement of Iranians was compared with Canadians. Student-t test was used for comparing the measured values.Results: In this study, all measurements in men were significantly greater than women (P<0.05).On the other hand, anthropometric measurements in Iranians and Canadians were significantly different, except for n'-gn' and zy'-zy' in men and t-gn'-t and ft'-ft' in women.Conclusion: This study showed that all of the anthropometric measurements in women are smaller than men in the city of Mashhad. Furthermore it was revealed that in Mashhad young adults, soft tissue glabella and subnasal in relation to tragion were more retruded than Canadians, also the width and height of face in females in Mashhad were significantly greater than Canadian young women.

Introduction: Elastomeric ligatures are used to secure archwires into orthodontic brackets. Unless the ligatures show adequate tensile properties, they may tear while inserting in the brackets or between patient's appointments. The latter may cause unwanted tooth movement and prolong orthodontic treatment. In this study the comparison of tensile properties (tensile strength, extension to tensile strength, and toughness) of seven commercially available molded clear elastomeric ligatures was performed.Materials & Methods: In this experimental laboratory-based study, elastomeric ligatures were obtained from American Orthodontics, Ortho Technology, GAC, Techno Tak, All Star, Dentaurum and ITO companies and their tensile properties were measured using Zwick testing machine with 5mm/min cross head speed in the as-received condition and after 28 days immersion in a simulated oral environment. The data was analysed by SPSS software.Results: All of the ligatures tested showed a significant decrease in tensile strength, extension to tensile strength and toughness excluding ITO's toughness after 28 days (P<0.001). Different brands of elastomeric ligatures showed significant differences in tensile properties both in the as-received condition and after 28 days immersion in the simulated oral environment (P<0.001). Under the study conditions, ligatures from American Orthodontics and Techno Tak companies showed superior tensile properties and ligatures from Ortho Technology Company exhibited weaker tensile features compared to other groups.Conclusions: There were significant differences in tensile properties of different brands of elastomeric ligatures in both the as-received condition and after 28 days immersion in the simulated oral environment. There was a significant reduction in strength properties of all types of elastomeric ligatures after 28 days immersion in a simulated oral environment. Thus, it is recommended that all ligatures should be replaced at each visit to reduce risk of tearing.

Introduction: The purpose of this study was to determine the frequency of psychiatric disorders in patients with oral lichen planus.Materials & Methods: In this descriptive cross sectional study, all the patients with oral lichen planus referred to Oral Medicine Department of Mashhad dental school (from September to October 2003) were examined by a psychiatrist and according to the criteria set by DSM-IV-IR, the presence and type of psychiatric disorders were evaluated. The data were analysed by chi-square and t-tests.Results: Among 56 patients examined, 54 (96.43%) subjects were diagnosed with at least one psychiatric disorder.96.41% of subjects were categorized as anxiety disorders.Conclusion: In this study, majority of the patients, with oral lichen planus had psychiatric disorders. So psychiatric disorders could have a role in developing oral lichen planus.

Introduction: One of the popular treatment options for correction of discoloration and poorly shaped anterior teeth is veneer. Two main preparation designs for full veneers have-been developed: 1. Window preparation 2. Incisal lap preparation. The aim of this study was to compare the effect of two new design preparations on the fracture strength and retention of laminate with conventional preparation.Materials & Methods: In this in vitro experimental study, 54 human extracted central and lateral maxillary and mandibular teeth were selected. Samples were divided into three main groups (n=18) with two subgroups in each (n=9).Group 1: Incisal lap preparation of labial surface of teeth without box preparation. Group 2: Preparation of labial surface with labial box in mesial and distal surfaces. Group 3: Preparation of labial surface with proximal box in mesial and distal surfaces. In the first subgroup of all groups, indirect composite laminate and in the second subgroup, ceramic laminate was fabricated. After cementation of laminates with dual cured resin cement (Rely X ARC), we determined the fracture strength by zwick machine and type of failure by the stereomicroscope. The data were analyzed by One-Way and Two- Way ANOVA, Tukey and student-t tests.Results: 1) There was a significant difference between fracture strength of laminates made of two different types of materials in three types of preparations (P=0.016). 2) In composite laminates, there was a significant difference between fracture strength of group 1 and 2 and the greatest fracture strength was observed in group 1 (P=0.019). 3) In ceramic laminates, there was no significant difference between fracture strength of the three types of preparations, although the greatest fracture strength was observed in group 2 (P=0.055). 4) There was no significant relationship between mode of failure and type of preparation in two different laminate materials.Conclusion: The findings of this study demonstrated that in incisal lap preparation of labial surface of tooth without box preparation, fracture strength of composite laminates was proved to be greater than ceramic laminates, while with preparation of labial surface with labial box, fracture strength of ceramic laminates was proved to be greater than composite laminates.

Introduction: For sealing a cavity prepared in endodontic surgery, there is a need for a material to obtain an apical seal and prevent bacterial and tissue exudates. The purpose of this study was to compare the sealing ability of Biocalex and white MTA as root-end fillings.Materials &Methods: In this invitro experimental study, 36 single-rooted extracted human adult teeth with minimum root curvature were cleaned, shaped and obturated with lateral condensation technique, 3 mm of the root apices were resected and a 3 mm deep retrograde cavity was prepared. Teeth were assigned randomly into two groups of 15 teeth each and retrofilled with Biocalex and White MTA. Three teeth served as positive and three teeth served as negative controls. All root surfaces, except the ending part, were covered with two layers of nail polish. Then the roots were stored in 2% methylene blue for 72 hours and then embedded in polyester resin. Next, they were sectioned buccolingually by diamond bur and maximum extent of dye penetration was evaluated through stereomicroscope.Statistical analysis was carried out by student t-test. The level of significance was set at 95%.Results: It was shown that retrofills with Biocalex had significantly less microleakage compared with white MTA.Conclusion: The findings of this study showed that retrograde filling with Biocalex can achieve proper sealing ability and can be used as an alternative for MTA (P<0.001).

Introduction: Clinically, vertical root fracture occurs commonly in endodontically treated teeth. Previous studies have shown little changes in root fracture strength following endodontic treatment. The purpose of this study was evaluation of changes in' dental root biomechanical properties following two different methods of instrumention by Rotary (R) or Hand (H) files and two different methods of obturation by lateral (L) or vertical (V) technique.Materials & Methods: In this invitro study, one hundred extracted human mandibular premolars with straight root, closed apices and free of caries were selected. For the teeth to be indentical and simple to study, all teeth were decoronated 3mm above the CEJ. With making artificial PDL, all teeth were mounted in acrylic molds. Teeth were randomly distributed into four experimental groups according to the instrumentation and obturation techniques used each with a sample size of 25. Hand instrumentation was done using stainless steel (S.S) files and Step-Back technique. Rotary instrumentation was done using Ni-Ti files (Race) and crown-down technique. Loading was applied using a crosshead conical tip mounted in a Zwick testing machine. The crosshead tip was initially placed into the canal orifice of each tooth, advanced vertically until it contacted the gutta-percha automatically and at a constant rate (2mm/min). Root fracture was noted with observation of a sudden deflection in the running graph. Load to fracture was recorded in Newton (N). The energy to fracture, slope of elastic area and displacement was calculated using origin V.5.0 software through running graphs. The data were analyzed using ANOVA and Duncan test.Results: Maximum mean load to fracture was observed in RL group (524 N). Minimum mean load to fracture was observed in RV (Rotary & Vertical) group (319 N). A significant difference in mean load to fracture was found between the (Rotary & Vertical) RV & (Hand & Lateral) HL, (Hand & Vertical) HV & (Rotary & Lateral) RL and (Rotary & Lateral) RL & (Rotary & Vertical) RV groups (P<0.05). Both the energy and displacement were significantly correlated with load to fracture.Conclusion: The fracture strength of roots obturated through vertical compaction of gutta-percha was lower than that of lateral compaction regardless of method of instrumentation. Fracture strength of root was not affected by the method of instrumentation (hand or rotary).

Introduction: There has always bee a concern about the easiness, durability and costs of filling in teeth which are extremely decayed. Different restorative methods such as use of Pre Fubricated Post with Amalgam Core, composite and FRC Post have been considered but the most common one is use of melted post core. Retention of the post is influenced by different factors such as length, width, shape of post and the type of cement. Another important retentive factor is the procedure of the post cementing. The aim of this study was to compare cast post retention of three different cementing methods.Materials &Methods: In this invitro experimental study, 40 central incisors were selected. After preparing and making the posts, the teeth were randomly divided into three groups of ten as A, Band C. The cement which was used was glass lonomer (GC Fuji l) mixed according to the manufacturer's instructions and was used in three ways: Group A: cement was placed in the canal with lentulo. Group B: cement was injected into the canal. Group C: first it was injected followed by use of lentulo. In order to keep the cemented teeth out of humidity, vaseline was applied. Finally, after 72 hours, the tensile stress at the speed of 1mm per minute was applied. Tukey test, Kruskal Wallis test and one way ANOVA were used for data analysis.Results: The maximum strength was abserved in group C (in jection+lentulo) in which 90% of the samples had more than 50kg tensile strength. The minimum strongth was abserved in group A (Lentulo placed cement) in which 10% of the samples had more than 50kg tensile strongth (P<0.05).Conclusions: 1) The procedure and method of cementation of the post had greeted role in retention of it. 2) The best way of cementing post was injection followed by lentulo use.

Introduction: Amalgam and adhesive resin core with cemented dowels are commonly used to restore endodontically treated teeth. These restorations have widely been studied for their mechanical properties; however, less is known about their sealing ability. In this study, we compared the microleakage of adhesive resin core buildup (Core Max 11) of amalgam and adhesive in enamel margins and compared it with amalgam.Materials & Methods: In this interventional experimental parallel group study, 30 intact human premolars were randomly selected. Calss V cavities were prepared on the buccal surface of each tooth with occlusal margin in enamel and gingival margin in cementum. Then, the teeth were divided into two groups with 15 teeth. Next, one group was filled with amalgam and another group with Core Max 11according to manufacturer's instructions. After thermocycling and dye penetration, the teeth were sectioned and microleakage was assessed. Data were analyzed by T-student and paired t tests through SPSS VII with 95% confidence interval.Results: 1. The mean microleakage of occlusal margins (enamel) of adhesive resin core, Core Max II (30.84±5.01) was significantly greater than amalgam Oralloy (13.07±3.5) (P=0.001). 2. The mean microleakage of cervical margins (cementum) of Core Max 11(39.81±4.92) was not significantly different from amalgam (34.56±2.03). However, the mean for Core Max 11was greater than amalgam (P=0.337). 3. The mean microleakage of cervical margins of amalgam (34.56±2.03) was significantly greater than occlusal margins (13.07±3.50, P=0.001). 4. Mean microleakage of cervical margins (cementum) of adhesive resin core, Core Max II (39.81±4.92) was not significantly different from occlusal margins [enamel, (30.8±5.01, P=0.197)].Conclusion: Amalgam restorations especially at enamel have less microleakage than adhesive resin cores (Core Max 11) and the mean micro leakage of enamel margins is less than cementum margins.

Introduction: Loss of tooth structure due to dental caries and cavity preparation can reduce fracture resistance, especially for endodontically treated teeth. The aim of this study was to assess the fracture resistance of pulpotomized primary molar teeth with class 11amalgam restorations.Materials & Methods: In this invitro experimental study, 80 carious human extracted primary molar teeth (40 first molars and 40 second molars) were selected for pulpotomy preparation. The teeth were divided into four groups. Mesioor disto-occlusal (20 teeth) and Mesio-occluso-distal (20 teeth) cavities were prepared in both first and second primary molarteeth. Each group was divided into two subgroups with 10 teeth in each, according to thickness of the remaining walls (1.5 or 2.5mm).After restoring teeth with amalgam, all groups were stored in distilled water at 37oc for 7 days. They were then thermocycled for 1000 times 5oc to 55oc. Finally, the specimens were subjected to a compressive axial load in a universal testing machine (Zwick) at a crosshead speed of 0.5mm/min and fracture resistances of teeth were calculated in Newton. T-test was used for statistical analysis.Results: Mean fracture resistances of first and second molar teeth were 975±368.8 N and 1049±540.1 N respectively.In the first molar teeth, fracture resistance of two-surface cavities was significantly greater than three-surface ones (P<0.001), but the difference was not statistically significant in second molars. In the second molar teeth, the fracture strength of cavities with 2.5mm wall thickness was greater than 1.5mm thickness walls in both two (P=0.001) and three surface cavities (0.015) but in first molars, this difference was significant only in the three surface cavities (P=0.045).Conclusion: The fracture strength in pulpotomized primary molar teeth with amalgam restorations was high (more than maximum bite force in primary teeth) even in extensive 3-surface ones. Therefore, the teeth with large proximal carious lesions in school children can be restored with amalgam instead of Stainless steel (ss) crown.

Introduction: Ceramic inlays are alternative systems for restoring dental cavities with tooth colored materials. These restorations may have some benefits over direct composite restorations such as reduction in the bulk of the cured composite. The aim of this study was to evaluate the microleakage of direct composite restorations and ceramic inlays with two different resin cements.Materials & Methods: In this experimental study, 45 class V cavities (15 teeth in each group) were prepared in buccal surfaces of human extracted molars. For 30 cavities, ceramic inlays were prepared and were cemented either with Variolin k I Excite DSC or Panavia FlED primer. Fifteen samples were restored with Excite! Heliomolar (direct composite). Then the teeth were thermocycled and were covered with sticky wax and were immersed into the 2% Methylene blue for 48 hours. The teeth were sectioned longitudinally and dye penetration was determined. Data were statistically analyzed using nonparametric tests of Kruskal Wallis, and Mann Whitney with significance level 0.05.Results: Enamel margins showed less microleakage than dentin margins in all groups (P<0.05). No significant differences were observed between the materials used in this study (P>0.05).Conclusion: The materials used in this study can not completely prevent microlekage. It seems that ceramic inlays can not reduce microleakage over direct composite significantly.

Introduction: Calcifying odontogenic cyst is an uncommon odontogenic lesion that demonstrates variable clinical behaviour and considerable histopathologic diversity and acounts for only (1%) of jaw cysts reported. This cyst is derived from odontogenic epithelial remants within the gingiva or within the mandible or maxilla and it may be associated with the recognized odontogenic tumors most commonly odontoma but rarely, ameloblastoma, Adenomatoid odontogenic tumor, or odonto Amelobalstoma. This case is presented here for its rarity and difference between ameloblastomatous calcifying odontofenic cyst and ameloblastoma along with calcifying odontogenic cysts. Because the prognosis and treatment procedures are different in Ameloblastomatous COC and COC with Amelobalstoma, their differential diagnosis is necessary.Results: The patient was a 22-year old male referred to dental office for filling of surface caries 6, 71. A painless swelling that had been present for approximately 2 months was observed. Panormaic radiography showed a well defined multilocular radiolucency. Microscopic examination reported calcifying odontogenic cyst (ameloblastomatous type).Treatment was done with simple enucleation. In 11 month follow up, no recurrence was reported.Conclusion: Calcifying odontogenic cyst (Ameloblastomatous) microscopically resembles unicystic Ameloblastoma except fot the ghost cells and dystropic calcifications within the proliferative epithelium. There has always been confusion about its nature as a cyst, neoplasm or hamartoma. This cyst, microscopically, shows ameloblastic proliferation in the connective tissue but no characteristics of Basal cell hyperchromatism, vacuolization and nuclear polarization which is often seen in ameloblastoma, are present here. Ameloblastoma ex COC and ameloblastomatous COC are morphologically entirely different and easily distinguishable.