Journal of Mashhad Dental School
Year:2017 | Volume:40 | Issue:4|Papers Count:13

Introduction: Several factors affect the success rate of dental implants, including the quality of bone. Schwartz for the first time described the use of computed tomography (CT) to classify bone density. Cone-beam CT (CBCT) has replaced CT in various fields due to lower dose and cost. This study aimed to evaluate the effect of exposure factors on reliability of CBCT in determining density.Materials & Methods: In this study, CT dose index phantoms including nine different concentrations of 76% meglumine with active ingredient of iodine were subjected to CBCT imaging with Planmecca 3D Mid under different exposure conditions. To obtain Hounsfield unit from CT, CT imaging from the phantoms was performed under standard conditions. Hounsfield unit and voxel values from CBCT and CT were recorded under all conditions, then, the difference and correlation between them was evaluated using paired-samples t-test and linear regression.Results: The results of this study showed excellent correlation between voxel values from CBCT and Hounsfield unit from CT (R=0.847). With changing the kVp conditions and mA this correlation remained high (R>0.8). There was no significant difference between the voxel values from CBCT and Hounsfield unit from CT under standard exposure conditions (P=0.6). However, variation in the amount of radiation exposure factors caused a significant change in CT and CBCT values, which could affect reliability of voxel values from CBCT (P=0.049).Conclusions: Our findings exhibited no significant difference between voxel values from CBCT and Hounsfield unit from CT. Furthermore, changes in exposure factors can affect the reliability of voxel values.

Introduction: Periodontitis is an inflammatory disease of the periodontal ligament caused by microorganisms, which leads to progressive and irreversible damages to the periodontal ligament and the alveolar bone. The main causative agent of this disease is bacterial plaque; however, other factors such as environmental factors, genetics, and immune disease might be at play. Lipid peroxidation is a major consequence of oxidative stress, which in turn, elevates malondialdehyde (MDA) level. Herein, we aimed to compare the salivary MDA levels of patients with chronic periodontitis and normal subjects.Materials & Methods: Thirty chronic periodontitis patients, referred to the Department of Periodontology, School of Dentistry, Mashhad University of Medical Sciences, Iran, and 30 periodontally healthy controls were included in the study. Unstimulated whole saliva samples were collected by spitting method from both groups. Salivary MDA level was measured using a spectrophotometric assay by colorimetric method. The data were analyzed performing independent t-test, Mann-Whitney U test, and Chi-square.Results: Salivary MDA levels were significantly higher in the patients with chronic periodontitis compared to the healthy controls (P<0.001).Conclusion: The results indicated that salivary MDA level can be used as a suitable biomarker for predicting and diagnosing periodontal disease and may play an important role in periodontitis pathology.

Introduction: Ideal restorative esthetic dental materials should have similar properties of light reflection, scattering, and fluorescence as those of natural teeth. Natural teeth emit a strong blue fluorescence when exposed to ultraviolet (UV) light, which makes natural teeth seem whiter and brighter in daylight. The unique structure of natural teeth is the most important constraint for simulation of restorative materials. The purpose of this study was to simulate dentinal tubule and evaluate the effect of different percentages of porosity on the luminescence properties of dental porcelain.Materials & Methods: In this in vitro study, we prepared a control sample (without silicon carbide) and three dental porcelain samples with different percentages of porosity by adding 0, 1, 2 and 3% silicon carbide (SiC). Their luminescence intensities were measured by spectrophotometer and compared with that of natural tooth.Results: With the increase of porosity, the luminescence property improved. The maximum luminescence intensity was observed in the samples with 3% SiC, while the lowest intensity was found in the 1% sample.Conclusion: Porosity within dental porcelains reduces refraction and reflection, and therefore, such samples under exposure to UV light show higher luminescence intensity.

Introduction: Previous studies have revealed the effectiveness of laser therapy in the improvement of dentin bonding. In other words, laser radiation can result in the higher bond strength of adhesives. Accordingly, the aim of this study was to propose an appropriate protocol for the use of Er: YAG and Nd: YAG lasers with the purpose of improving the bond strength of a sixth-generation two-step adhesive.Materials & Methods: In this experimental study, a total of 70 healthy extracted teeth were selected and classified into seven groups. The control group was prepared according to the manufacturer's instructions. The remaining six groups were treated with Er: YAG and Nd: YAG lasers before primer application (Er-BP and Nd-BP groups), after primer application (Er-AP and Nd-AP groups), and after bonding (Er-AB and Nd-AB groups). The specimens were covered with Filtek Z-250 resin composite (shade A2 and height of 4 mm), using an incremental technique and were then treated. Following that, the micro tensile test was performed on the samples. The gathered data were analyzed, using one-way analysis of variance (ANOVA), followed by post-hoc Dunnett T3 test. P-value less than 0.05 were considered statistically significant.Results: The mean and standard deviation of bond strength in the groups were as follows: Control=30.09±4.21, Er-BP=18.83±4.21, Er-AP=14.43±3.12, Er-AB=19.67±4.96, Nd-BP=20.35±5.55, Nd-AP=39.85±4.13, and Nd-AB=18.16±3.36. The values obtained in the Nd-AP group were significantly higher than the control group (P<0.05). However, the values reported in other groups were significantly lower in comparison with the control group (P<0.05).Conclusion: In the present study, use of Nd: YAG laser system after primer application (Nd-Ap) significantly improved the bond strength in comparison with the control group.

Introduction: Palatal fractures are frequently associated with maxillary fractures in midfacial trauma. These fractures may cause diagnostic and therapeutic challenges. If treated improperly, results would be malunion, malocclusion, and oronasal fistula formation. Herein, we aimed to evaluate the effectiveness of the conventional miniplates used over mucosaly in the management of maxillary palatal fracture.Materials & Methods: Under general anesthesia, arch bar was fixed to the existing teeth. After fixation of palatal fractures, appropriate occlusion was obtained by trans palatal wiring. Fixation of palatal fractures was performed with a conventional four-hole, straight-bar miniplate with 2 mm thickness and four 8-mm-long screws on both fracture sides. The patients remained with interpapillary fixation for seven days and elastic therapy for two weeks. Miniplate and screws were removed about 8-12 weeks after their application. Follow-up was performed every three months for one year.Results: This technique was applied for 10 trauma patients with maxillary palatal fracture. Palatal over mucosal plate and screws remained rigid in their position until their removal. None of the patients suffered from oronasal fistula, bone exposure, or mucosal necrosis. Interference with speech and swallowing, as well as tongue irritation and difficulty in oral hygiene maintenance were not reported by any of the patients. Palatoalveolar segments remained in proper position, and pretraumatic occlusal patterns and facial width were restored except in one case.Conclusion: Fixation of the palatal fractures with the conventional miniplates without elevation of mucoperiosteal flap helps with stability and preventing palatal width problems. In so doing, complications including fistula formation and interference with oral cavity functions are avoided.

Introduction: Personal hygiene enhancement is one of the basic strategies for the management of oral diseases.Considering the great role of attitude in forming health behaviors, this study was designed to develop and validate a new questionnaire on the attitudes towards oral self-care among Iranian adolescents in Isfahan, Iran.Materials & Methods: After item pooling, the initial version of the questionnaire was presented to an expert panel in order to determine its content validity. Face validity of the questionnaire was evaluated in a pilot study, and the final version of the questionnaire was completed by 200 adolescents randomly. Reliability coefficients and attitude scores were calculated. Construct validity of the questionnaire was also evaluated, using exploratory and confirmatory factor analyses.Results: The final version of the questionnaire, consisting of 40 items, was developed with a Cronbach’s alpha of 0.72. The mean age of the participants was 15.9 years, and the mean attitude score was calculated to be 104±15. The correlation between attitude score and social status was statistically significant (P=0.03), whereas no significant relationship was found between gender and attitude score. Based on the exploratory factor analysis (Kaiser-Meyer-Olkin measure above 0.6) and significant Bartlett's test results, five factors accounted for nearly 38% of the variance in responses. The suggested model consisted of various sub-domains, including values (appearance and performance), emotions (positive and negative), parental influence, importance of social status, and knowledge about dental caries. The components were confirmed via confirmatory factor analysis and were found to have a moderate goodness of fit.Conclusion: In this study, the Attitude towards Oral Self-care Questionnaire was found to be reliable. In addition, content and construct validity of this questionnaire was confirmed among Iranian adolescents.

Introduction: Oral lichen planus (OLP) is a common inflammatory disease with an unknown etiology; nevertheless, involvement of viral agents has been suggested in the literature. Human herpesvirus-7 (HHV-7) is a distinctive virus with a 90% global prevalence. It is a member of the Herpesviridae family and Betaherpesvirinae subfamily. Previous studies have confirmed the role of HHV-7 in cutaneous lichen planus lesions. Accordingly, the aim of this study was to evaluate the frequency of HHV-7 DNA genome in OLP lesions, using real-time polymerase chain reaction (PCR) method.Materials & Methods: A total of 30 paraffin blocks from OLP lesions, as well as 30 samples from the normal mucosa, were collected from patients, referring to dental care clinics of Isfahan, Iran. The samples were evaluated for HHV-7 DNA genome, using the conventional PCR method. Data were analyzed via McNamara’s test, and the significance level was set at P=0.05.Results: A total of 10 out of 30 samples from OLP lesions showed positive HHV-7 DNA genome, while none of the control samples showed viral presence.Conclusions: There was a significant relationship between HHV-7 infection and OLP occurrence (P=0.002).

Introduction: Today, performance evaluation has become a ubiquitous and essential process in all organizations. Such evaluations are of paramount importance at higher education institutes, which mainly focus on the improvement of the education process. Each year, the School of Dentistry of Mashhad University of Medical Sciences (MUMS) facilitates teacher performance evaluations by the students, instructors, managers, and personnel, and the obtained results are presented to the instructors. The aim of this study was to assess the instructors’ opinions at MUMS School of Dentistry regarding factors affecting teaching quality assessment.Materials & Methods: This descriptive study was conducted during 2009-2010 academic years at MUMS School of Dentistry. A valid and reliable questionnaire consisting of three parts was designed in accordance with the research objectives. Part I contained the demographic information of the instructors, and part II included questions about the instructors’ feedback to the evaluation scores and the importance of the scores to different individuals and sources. Part III consisted of questions regarding factors affecting the evaluation scores from the instructors’ perspective. The collected data were analyzed and compared by Friedman test (a=0.05).Results: More than half of the instructors believed that there was a moderate relationship between the assessment scores and the reality of teaching methods. Regarding the importance of scores announced by various sources, 46.2% (n=30) of the instructors gave value to the residents’ opinions. Among factors affecting the evaluation scores from the instructors’ perspective, “mastery over the course content” and “renewal of teaching methods” was the first and last priorities, respectively (P<0.001). Also, the most important factor in decreasing the evaluation scores was the officials’ poor performance, while the least important factor was repeated holidays throughout the semester (P<0.001).Conclusion: To reach better and more realistic results in performance evaluations, improvement of evaluation tools and implementation processes is recommended. Since comprehensive understanding of the course content is the most important factor in increasing the evaluation scores from the instructors’ viewpoint, it is important that their knowledge be improved through participating in training workshops, seminars, and discussion meetings, as well as studying the available literature.

Introduction: The aim of this study was to investigate the fraction rate of Pro Taper Universal and Neoniti rotary files during the preparation of simulated severely-curved root canals.Materials & Methods: A total of 70 resin blocks with simulated severely-curved canals were randomly divided into two groups and prepared with Pro Taper Universal and Neoniti files. Each set of files was used for cleaning and shaping five canals; the files were sterilized after each application. Afterwards, the number of deformed and fractured files was recorded.Results: Deformation was reported in 11.4% and 19% of Pro Taper and Neoniti files, respectively (P>0.05). Also, fraction was found in 11.4% of Pro Taper files, while no fracture was reported in the Neoniti group; overall, no statistically significant difference was found between the groups (P>0.05).Conclusion: Based on the present findings, there was no significant difference between Pro Taper Universal and Neoniti files with respect to the incidence of deformation or fracture during the preparation of severely-curved canals.

Introduction: Brown tumors of the jaws represent severe osteodystrophy in patients with end-stage renal failure. These tumors occur most often in long bones, although any bone can be involved. From a clinical perspective, brown tumors are rarely reported in the jaws.Case report: Herein, we report the case of a hemodialysis patient with an unusual growth of masses in jaws following partial parathyroidectomy. The masses were diagnosed as brown tumor, based on clinical, radiographic, and pathological findings. The present case report is noteworthy, considering the patient’s medical history, site and size of lesions, unusual course of the disease, and occurrence of serious complications (dyspnea, dysarthria, and chewing dysfunctions).Conclusion: Early detection of oral manifestations following hyperparathyroidism in patients with chronic renal disease and diagnosis by a dentist is important for preventing further complications.

Introduction: Odontodysplasia is a localized, non-hereditary, developmental abnormality, affecting tooth enamel, dentin, and dental pulp. Different factors are involved in the development of this abnormality, including vascular lesions. Odontodysplasia is most frequently observed in the anterior maxilla among females and usually involves less than two maxillary quadrants.Case report: Herein, we present the case of a 15-year-old female patient, seeking treatment due to lack of tooth eruption in the jaws at the Department of Oral Medicine, Zahedan School of Dentistry in 2015. Dental examination of the upper jaw showed partial eruption in the right and left central incisors, whereas the second deciduous molars were still unerupted; also, other teeth in the upper jaw showed no eruption. The panoramic radiography showed ghost teeth with a large pulp chamber and an open apex. Moreover, pulp stones were observed in some mandibular teeth; many impacted teeth were reported in the radiography, as well.Conclusion: Similar to other previous studies, the current report presented a case of generalized odontodysplasia in a female patient; however, in contrast to previous reports, both jaws were involved in our patient. Unfortunately, there is no consensus regarding the best treatment option for these patients.