مجله دانشکده دندانپزشکی مشهد
سال چهل و سوم شماره 3 (پیاپی 110، پاییز 1398)

Soft tissue calcifications seen in the head and neck region are common findings sometimes detectable using panoramic radiographs. Regarding this, this study was carried out to determine the prevalence of these calcifications and their relationship with age and sex in Bushehr since these calcifications could be indicative of underlying systemic disorders, In this cross-sectional study which was conducted in Bushehr in2018, a total number of 1040 panoramic radiographs were evaluated. The radiographs were obtained using a SAMSUNG digital panorex x-ray machine (RAY SCANα-SC model) and printed using an Agfa health printer (Drystar model). After the evaluation of radiopacities, such details as type, position, number, unilateral or bilateral status, and the site of involvement were recorded. A total of 130 calcifications were recorded of 1040 subjects. The prevalence of calcification was 12/5% with 95% confidence interval (9/61%-14/42%). The most prevalent calcification observed was calcified stylohyoid ligament, and the least prevalent was sialolith. In addition, a higher number of calcification was observed in males with the age of > 40 years old. The prevalence of calcification in various age groups (P<0.001) and sex (P=0.023) was significantly different. Sylohyoid ligament calcification was the most prevalent soft tissue calcifications of head and neck region, with a prevalence of 7/5%. Moreover, prevalence of calcifications of soft tissues of head and neck was revealed to be associated with age and sex. In addition, higher frequency of these calcifications was observed in males > 40 years old.

Regarding the use of nickel-chromium (Ni-Cr) alloy in porcelain-fused to metal-restorations and the need for high temperature for porcelain firing, there are probable alterations in the microstructure of the alloy, the corrosion resistance, and the rate of ion release. The aim of the present study was to evaluate the effect of multiple firings on the corrosion resistance and surface characteristics of two Ni-Cr alloys. In total, 24 discs were made from each Ni-Cr alloys without beryllium (Dam Cast) and with beryllium (Super Cast). They were then assigned into four subgroups based on the number of firings: (1) without firing, (2) four times firing, (3) four times firing and a correctional firing, and (4) four times firing and two correctional firings. The corrosion resistance was evaluated using an electrochemical potentiostat device. The ions release was measured after immersing samples in Fusayama artificial saliva (pH of 5, at 37 ◦c) for 30 days by ICP-AES technique. The surface of the alloys was evaluated with a metallurgical light microscope and scanning electron microscope. Data were analyzed in SPSS software .P-value less than 0.05 was considered statistically significant. According to the results, the impedance of both alloys decreased significantly with increasing the frequency of firings. A significant decrease was observed in the impedance and corrosion resistance of Super Cast alloy using correctional firings (the third and fourth firings), compared to Porcelain firing samples. However, no significant decrease was observed in Dam Cast. In addition, the number of released ions was significantly increased with an increase in the number of firings in both alloys. Nevertheless, there was no difference between the alloys regarding the released ions. The concentration of released ions was higher in Super Cast alloy, compared to that in DAM Cast.  Increased levels of corrosion were observed on the surface of Super Cast alloys using a microscopic evaluation. Multiple firings had lower effects on the corrosion resistance of Dam Cast alloy without beryllium, compared to Super Cast alloy with beryllium.

Shape-memory alloys (SMAs) hold a prominent place in medical and dental applications due to their high compatibility with the body, corrosion resistance and, unique mechanical properties. The aim of this study was to assess the influence of SMA dental implants on the stress distribution of the implants and bone. A dental implant was subjected to axial and transverse forces and the results were extracted using finite element methods. To this end, a sample of an existing dental implant with a section of the bone was simulated using Abaqus software and analyzed statistically. Finally, the magnitude of stress in the SMA implant was compared with that of the implant made of common materials. The magnitude of stress in the SMA implant was lower, compared to that of nickel-titanium implant. Moreover, the nitinol implant at the points which were under higher force and stress showed lower levels of the transformed values of stress to the jaw bone, compared to the nickel-titanium implant.

Antimicrobial products in form of mouthwash have an impressive effect on reducing plaque formation and gingivitis. These agents may aid in mechanical prevention and control of periodontal diseases. Chlorhexidine as the gold standard among these solutions has well-known side effects leading to introduction of some alternatives. With this background in mind, this study aimed to evaluate the efficacy of nanocurcumin mouthwash, a herbal mouthwash based on turmeric, on the treatment of chronic gingivitis. Moreover, the impact of this solution was compared with chlorhexidine. Thirty patients with generalized chronic gingivitis were included in the study. The participants were randomly divided into three groups of ten each. All the patients underwent scaling and root planning. In group one, two, and three, the patients were treated with chlorhexidine mouthwash, nanocurcumin mouthwash, and placebo, respectively. Gingival indices (GI), plaque indices (PI), bleeding on probing (BOP), and probing depth (PD) were all recorded pre-treatment, in addition to one, two, three, and four weeks post-treatment. The changes in GI, PI, BOP, and PD were analyzed. According to our findings, the clinical parameters showed improvement in all the three groups, compared to the baselines. When compared to the placebo group, both chlorhexidine and nanocurcumin groups were found to have significantly better outcomes (P<0.001). However, when comparing the chlorhexidine and curcumin groups, the differences regarding GI and BOP were not revealed to be statistically significant. The PI and PD were shown to have significantly better results in the post-treatment evaluations of the nanocurcumin group (P<0.001). The present study indicates that nanocurcumin is comparable to chlorhexidine as an anti-inflammatory mouthwash and results in higher improvements concerning some aspects. Therefore, nanocurcumin can be considered as an effective adjunct to mechanical periodontal therapy.

Orthognathic surgery is one of the safe methods for treating dentofacial abnormalities that is effective in a patient’s quality of life and psychological aspects. The aim of this study was to compare the effect of orthognathic surgery on the quality of life of patients with class III deformity treated by orthognathic surgery with patients without dentofacial deformity and nontreated class III patients. Materials & In this descriptive-analytic study, 75 individuals aged 18 to 35 years from both genders who referred to Dental Faculty of Islamic Azad University, Isfahan branch, Isfahan, Iran, were chosen. Thirty subjects had undergone the surgery for class III malocclusion, and at least 6 months passed from their surgery. Thirty individuals with no dentofacial deformity and fifteen untreated patients with class III malocclusion were selected. Then the orthognathic quality of life questionnaires were provided for the patients, and the results were compared. The questionnaire included four aspects of social, dentofacial esthetics, oral function, and awareness of dentofacial aesthetics. The data were analyzed using the Chi-square test, one-way analysis of variance, least significant difference follow-up test, and Pearson correlation coefficient. The mean scores of total quality of life (P=0.02), dentofacial esthetics (P=0.003), oral function (P=0.04), and social domain were significantly different among the three groups; but there was no significant difference between the mean scores of quality of life in awareness of dentofacial aesthetics among the three groups (P=0.81). The mean score of quality of life in the awareness of dentofacial aesthetics domain was the same in the group of treated class III individuals and the group with no dentofacial deformity. Moreover, it was lower in nontreated class III cases.   The quality of life of the patients with class III malocclusion after orthognathic surgery improved, compared to the level of the control group (with no dentofacial deformities), and it was greater than that of the untreated class III group. This difference was greater in oral function and social domains and lower in the awareness of dentofacial aesthetics domain.

Dental sensitivity is one of the most common complications of bleaching treatments. Several sensitization agents have been used to relieve symptoms. Recently, the use of nanobiomaterials has been considered for dentinal tubular occlusion to treat sensitivities. The purpose of this study was to investigate the effect of 40% hydrogen peroxide with and without nano-hydroxyapatite and nano-bioactive glass on the dentinal tubular occlusion. By removing the cervical enamel of 60 healthy premolar teeth, a flat surface of the dentin was created. The samples were prepared with the same dimensions and randomly divided into three equal groups, including group 1) 40% hydrogen peroxide bleaching material, group 2) combination of bleaching material and nano-hydroxyapatite 2% by weight, and group 3) combination of bleaching material and nano-bioactive glass, 7.5% by weight. Bleaching was performed in three periods of 15 min in two sessions with a one-week interval. Dentinal tubular occlusion was investigated using scanning electron microscope images, and scoring was based on the Hulsmann index. The data were analyzed by the Kruskal-Wallis test and Dunn's multiple comparison test. The significance level was considered 0.05. But group 1 was significantly different from both groups 2 and 3 (P<0.001). In contrast to group 1, the occlusion of dentinal tubules occurred in groups 2 and 3. However, there was no significant difference in the closure of dentinal tubules between groups 2 and 3 (P=0.01). There was a significant difference between the group 1 and group 2 and 3 (P<0.001). Adding nano-hydroxyapatite and nano-bioactive glass to hydrogen peroxide causes the occlusion of dentinal tubules after bleaching, and it can be a successful treatment to reduce post-bleaching sensitivities with hydrogen peroxide.

Mandibular premolars are considered the most difficult of all teeth for endodontic treatment due to variation in the shape and the number of canals. For this reason, endodontic treatments showed the most failure rates. In this study, the number and morphology of canals of the mandibular premolar are investigated in northern cities in Iran. This cross-sectional study investigated the archived cone beam computed tomography images of patients who referred for diagnostic purposes to private centers of maxillofacial radiology. In total, 280 mandibular first premolars from 111 males and 169 females and 248 mandibular second premolars from 95 males and 154 females were investigated in this study. Data were analyzed in SPSS software (Version 2016) through descriptive statistics using frequency distribution and Chi-square test. Level of significant considered 0.05. Mandibular first premolars in males and females had one or two roots. One root premolars were the most prevalent of mandibular premolars (95.7%). Similarly, mandibular second premolars had one or two or three roots and one root premolars were the more prevalent of mandibular second premolars (97.6%). In terms of the number of canals, the majority of premolars had a single canal and were of type I. Among mandibular first premolars, types III, IV, and VII were not seen and Vertucci type VIII was the rarest.  Out of mandibular second premolars types IV, VI, and VII were not observed, and Vertucci types II and IIIV were the rarest. According to the results, mandibular first and second premolars in females and males are more single rooted and have a single canal. Regarding the Vertucci classification, the most prevalent type was type I.

This study aimed to investigate Moodle mobile educational application, which can be run in Android and ios operating systems for improving knowledge regarding laser applications among the students of dentistry. A total of 59 subjects were selected from the dentistry students of first academic semester in Mashhad University of Medical Sciences, Iran who chose the course of practical oral diseases. The participants were divided into two groups. First, the pretest was conducted and the basic knowledge of the students regarding laser application in dentistry was evaluated. Next, Moodle mobile software was introduced during a half of a semester to the students of the test group and they learned how to work with it in a workshop held at the beginning of the semester. Afterwards, Moodle mobile was installed on their mobile phones. On the other hand, the participants in the control group were trained by booklet. In both groups, the knowledge of the students in terms of the application of laser in dentistry was evaluated pre- and post-intervention. All the data were analyzed by McNemar test, paired t-test, and Mann-Whitney U test using SPSS software version 19 (SPSS Inc., Chicago, IL). The mean scores of the students trained by the booklet changed from 7.3 pretest to 13.9 post-intervention, which was statistically significant (P<0.001). Furthermore, the mean scores of students trained by software increased from 7.8 pre-intervention to 16.6 post-intervention. The latter alteration was found to be statistically significant (P<0.001). The post-intervention mean scores in the software and booklet groups were 16.6 and 13.9, respectively. The difference between these mean scores was statistically significant (P<0.001). According to the results of this study, both software and booklet training methods elevated the knowledge of dentistry students concerning the application of lasers in dentistry. However, the educational software was revealed to be significantly more effective than the booklet.

Motorcyclists are prone to face, neck, and head injuries. The aim of this study was to evaluate the effect of using or not using helmet on the different patterns of facial fractures. This descriptive cross sectional study was performed on the study population consisting of 127 traumatic motorcyclists referring to Shahid Bahonar Hospital, Kerman, Iran during the first six months of 2017. The subjects were selected by convenience sampling method. The demographic variables, including age and gender, in addition to the clinical variables, such as the type of fracture (single or multiple), fracture site in the mandible and midface were recorded in the study checklist. Out of 127 patients, 72.8% were male and 27.2% were female. It was revealed that 81 cases had fractures due to trauma to the maxilla and mandible. Moreover, 25.6% of the patients used helmet. The most frequent age group was 40-49.9 years with the frequency of 24.8%. Among the subjects, 44.4% and 55.6% of the motorcyclists had single and multiple fractures, respectively. The highest frequency in the mandibular fractures belonged to the body of mandible (26.3%), and the lowest frequency was related to coronoid of mandible (1.3%). The most frequent cases of fractures in the midface were Le Fort 1, Le Fort 2, and Le Fort 3 with the frequencies of 31.4%, 23.8%, and 16.3%, respectively. On the other hand, the least frequent fractures were seen in the orbital rim region (2.5%). There was no significant correlation between wearing helmet and the anatomical location of the maxilla fractures. However, wearing helmet was found to have a significant correlation with midface fractures. According to our results, the standard helmet had an optimal protective role in almost all facial fractures.

Antioxidant system is one of the most important protective mechanisms of saliva against free radicals. One of the most important antioxidant agents is vitamin C, which is effective in the treatment and prevention of oxidative stress. With regard to the effect of environmental, genetic, and nutritional factors on the balance between the production and expulsion of free radicals, the present study aimed to determine the effect of vitamin C on salivary total antioxidant capacity (TAC) in non-smokers. This randomized clinical trial was conducted on 60 healthy non-smokers referring to the Dental Clinic of Rafsanjan, Kerman, Iran, in 2017. After random division of the participants into three groups, the first and second groups were given 1000 and 500 milligrams of vitamin C effervescent tablet for 3 weeks, respectively. The third group did not receive any vitamin C supplements. The salivary TAC was measured before and after the intervention using an antioxidant kit and an ELISA reader. Data were analyzed using the paired t-test, one-way ANOVA followed by Duncan's post hoc test. Duncan's multiple comparisons test indicated that the mean changes (increase) in salivary TAC of the receiving groups of 500 and 1000 milligrams of vitamin C were not significantly different (P>0.05). However, the mean changes in salivary TAC in the control group were significantly lower than those receiving 500 and 1000 milligrams of vitamin C (P<0.001). The results of this study showed that the use of vitamin C as an antioxidant agent increases the salivary TAC.