مجله دانشکده دندانپزشکی مشهد
سال چهل و یکم شماره 3 (پیاپی 102، پاییز 1396)

Panoramic radiography is a diagnostic tool, which has a widespread application in the assessment of tempromandibular joint (TMJ) by the dentists as well as ear, nose, and throat specialists. Regarding this, the present study aimed to compare the accuracy of this method in the evaluation of the condylar position and osseous changes with that of the cone beam computed tomography (CBCT) as the gold standard method.
This study was conducted on 28 patients with both TMJ panoramic imaging and bilateral CBCT imaging of TMJs. The condylar position was determined in closed-mouth and maximum intercuspation positions based on the measurement of superior, posterior, and anterior joint spaces and osseous changes of condyle, including erosions, osteophytes, resorbtion, Ely’s cyst, flattening, and sclerosis. The images were evaluated by two expert maxillofacial radiologists. Finally, the accuracy of TMJ panoramic radiography was compared with that of CBCT in terms of the sensitivity, specificity, as well as positive and negative predictive values.
According to the results, there was a significant difference between the two techniques regarding the diagnosis of anterior and posterior condylar positions in horizontal dimension (P=0.012, P=0.007). The sensitivity rates in the anterior and posterior positions were 50% and 51%, and the specificity rates were 55% and 55%, respectively. Regarding the identification of condylar position in vertical dimension, the two methods showed a significant difference only in the narrowing of superior joint space (P=0.004). The sensitivity and specificity in the narrowing of superior joint space in the vertical dimension were 100% and 79%, respectively. Regarding the osseous changes, the TMJ panoramic method had a poorer performance in the diagnosis of erosion (sensitivity: 29%, specificity: 95%), compared to the CBCT. Nevertheless, no significant difference was observed between the two methods regarding the diagnosis of osteophytes and flattening.
TMJ panoramic radiography had a lot of limitations in the detection of the condylar position both in horizontal and vertical dimensions, compared to the CBCT. However, panoramic radiography can be relatively helpful in the initial screening of osseous changes for determining the healthy cases.

Surfaces mostly touched during dental treatments can be areservoir for infections and lead to cross-infection. The aim of the presentstudy was to evaluate the incidence of microbial infection of clinical surfaces in Mashhad Faculty of Dentistry.
Surface samples were randomly collected from unit headrest, light handle, and tabure of 10% of active dental units in Mashhad Dental Faculty. Samples were collected at two time points including beginning of the day and midday after surface disinfection. Samples were collected and transferred to the microbiology laboratory to determine the number of various microorganisms including staphylococcus, streptococcus, micrococcus, bacillus, tetragen, corena, and yeast. Data was analyzed by using Kruskal-Wallis test. P-value less than 0.05 were considered significant.
The highest rate of contamination of headrest was observed at Prosthodontics Department, and the highest rate of contamination of light handle respectively in Endodontics, Pediatrics, and Prosthodontics departments. Furthermore, Prosthodontics Department showed the highest rate of tabure contamination. Kruskal-Wallis test revealed no significant difference in total microorganisms at different departments in various surfaces. A significant difference was found between departments regarding micrococcus infection (P Microbial contamination was found at all surfaces at one or both of the sampling times, to prevent cross-infection more is required.

The aim of this in vitro study was to evaluate the effect of calcium hydroxide mixed with different vehicles on the push-out bond strength of mineral trioxide aggregate.
The study was conducted on 80 extracted single-rooted human maxillary incisor teeth who secrowns had been removed. The root canals were instrumented and divided into 4 groups according to the vehicle of the calcium hydroxide paste: Group I – distilled water; Group II – propylene glycol; Group III – 0.2% chlorhexidine; Group IV – control. After placement ofthe root canal dressings, the teeth were washed with EDTA and sodium hypochlorite and sealed with MTA. After 7 days, the push-out test was carried out using a universal testing machine. Data were analyzed with one-way ANOVA and gomes-howell tests.
The maximum and minimum bond strength values were recorded in the propylene glycol and distilled water groups, respectively. There was significant differences in push out bond strength between chlorhexidine and propylene glycol groups (P=0.015). There were significant differences in resistance to dislodgement between group control - propylene glycol (P=0.032) and group control-chlorhexidine (P=0.012).
Placement of propylene glycol before placement of MTA in root canal improves the push-out bond strength of this material.

Canine impaction is a common occurrence. In this study, we sought to investigate the root anatomy and length of impacted canines and lateral incisor adjacent to impacted maxillary canine.
In this retrospective study, three-dimensional tomographic imaging was performed on 26 patients with unilateral maxillary canine impaction. In this study, we evaluated root length and anatomy of impacted canines, in terms of resorption intensity and curvature, with Planmeca Romexis Viewer 4.0. Furthermore, crown shape as well as root length and anatomy of the lateral incisors adjacent to impacted canines were investigated and compared with the other side on the dental arch, where canine eruption was normal.
Root length of impacted canines was significantly lower than that of normal canines (P=0.011). There were no significant differences between root length of lateral incisors adjacent to impacted canines and root length of lateral incisors adjacent to normal canines (P=0.221). Moreover, the resorption intensity of the adjacent lateral incisors was higher than that of the impacted canines. No significant differences were noted in root resorption intensity between the lateral incisors adjacent to the imacted canines and the lateral incisors adjacent to normal canines (P=0.36). In addition, resorption intensity was significantly higher in impacted canines than in normal canines (P=0.024). Root anatomy of impacted canines was not significantly different from that of normal canines (P=0.055). The crown shape of the lateral incisors adjacent to impacted canines was not significantly different from that of the lateral incisors adjacent to normal canines (P=0.052).
Impaction can probably affect root length and canine resorption severity. However, root and crown shape of lateral incisors cannot always be associated with canine impaction.

Nowadays, appraisal of patient's perception of health has largely replaced the clinical evaluations. This study aimed to compare oral health-related quality of life in patients referring to public and private clinics in Mashhad, Iran.
In this cross-sectional study, we enrolled 383 patients referred to five private and two public dental clinics in Mashhad, Iran. The study variables including age, gender, level of education, functional dentition status, decayed, missing, and filled teeth, and the reason for referral were recorded. Oral Impact on Daily Performance (OIDP) score was calculated for each patient. To analyze the data, independent samples t-test, Man-Whitney U test, and Chi-squared test were run.
The reason for visiting the public and private clinics was significantly different (P The mean OIDP score was significantly higher in public clinics, that is, oral health-related quality of life was lower in patients referring to public clinics.

In post-core crown restorations, the use of prefabricated composite posts concentrate stress at the cervical region and the use of metal posts (prefabricated and customized posts) concentrates stress at the interfaces. Fiber reinforced composite posts (FRCs) with oval cross-section (oval posts) were proposed for post-core crown restorations to reduce the stress levels at the cervical region. The aim of the present study was to investigate the impact of oval cross-section composite posts on stress distribution of premolar with oval-shaped canal by using three-dimensional (3D) finite element analysis.
An extracted premolar tooth was mounted, sectioned, and photographed to create a 3D model. The surrounding tissues of the tooth, periodontal ligament, as well as cortical and trabecular bones were modeled. Seven taper posts with two different cross-section geometries (circular and oval shapes) were modeled, as well. Then, the effect of post geometry, post material (carbon fiber and fiberglass), and cement material were investigated by 3D finite element analysis and the stress distribution results were compared.
In all the models, the highest stress levels of the dentin were accumulated at the coronal third of the root, and the highest stress levels at the bonding layers were accumulated at the cervical margin. Narrow circular posts induced the highest stress levels, whereas the stress levels were reduced by using thick oval posts. Application of elastic cement reduces the stress at the bonding layers but increases stress at the dentin.
Finite element analysis showed that prefabricated oval posts are superior to traditional circular ones. The use of cement with low elastic modulus reduces the risk of debonding but raises the risk of root fracture.

Physicians play a pivotal role in guiding patients with oral and dental diseases. Cooperation between physicians and dentists is necessary for suitable and timely patient referral, as well as diagnosis and treatment of oral diseases. This study was conducted to investigate the knowledge of medical interns in medical schools of Sari and Babol regarding periodontal diseases in 2013-14.
This analytical descriptive study was performed in 80 medical interns in Sari and Babol medical schools during 2013-14. A questionnaire was designed on the nature and risk factors for periodontal diseases and the association between systemic and periodontal diseases; in doing so, the available articles in this regard were employed. Content and face validities of the questionnaire were established by two periodontal specialists. In order to evaluate the reliability of the questionnaire, test-retest was performed; spearman correlation coefficient was 0.8. To analyze the data, Chi-squared test was run using SPSS, version 20. P-value less than 0.05 was considered statistically significant.
This study was performed on 37 interns in School of Medicine of Sari (46.25%; 47% males and 53% females) and 43 interns in School of Medicine in Babol (53.75%; 49% males and 51% females). The mean overall knowledge scores of medical interns about periodontal diseases in Sari and Babol were 6.27±3.27 (medium) and 12.00±5.23 (very good), respectively, showing no significant differences (P>0.0001).
Given the importance of prevention of oral and dental diseases, especially periodontal diseases, further training for medical students and planning for promoting public knowledge seem to be necessary.

There is limited data on the factors affecting the retention of cemented fixed prostheses to implant abutment. The aim of this study was to evaluate the effect of screw access channel filling method and cement type on retention of implant-supported fixed restorations.
In this experimental study, 40 implant analogs were mounted in autopolymerizing acrylic resin blocks, and two-piece titanium abutments were placed in each implant analog. Twenty abutment samples were completely filled with silicone, and 20 other samples were filled partially. In each of the study groups, Temp Bond® eugenol-containing temporary cement was used for 10 samples, while in another 10 samples non-eugenol temporary cements were utilized. Prior to the retention test, samples were placed in the rmocycling machine with 1000 cycles for 24 h. Each sample was stretched using a Universal Pull-out Test Machine with a force of 5000 N. The required load for removing the crown was recorded. The data was analyzed USING two-way ANOVA and least square difference (α=0.05).
Among the four groups, the highest retention rate was observed in the group of partial screw access channel filling with eugenol cement. Also, the rate of retention in the group of complete screw access channel filling with non-eugenol cement was significantly lower than in any other group. A significant difference was observed between all the groups except for the groups of complete screw access channel filling with eugenol cement and partial screw access channel filling with non-eugenol cement (P=0.27).
The mean rate of retention in partial access cavity filling group was greater than that of the complete access cavity filling group; moreover, this rate was higher in the eugenol cement group than the non-eugenol cement group.

There are few studies investigating the oral health condition of the autistic children, rendering conflicting results. Regarding this, the present study aimed to compare the autistic and normal children in terms the caries experience.
This cross-sectional study was conducted on 70 children with autism and 70 healthy children with the age range of 8-12 years. The participants’ age, gender, and parental education level were recorded. The number of the decayed, missing, and filled teeth (DMFT; both permanent and primary) was determined. The data were analyzed using the Mann-Whitney U and Chi-square tests. P-value less than 0.05 was considered statistically significant.
According to the results, the paternal education level of the autistic children was significantly higher than that of the normal children (P=0.002). However, there was no significant difference between the two groups regarding their maternal education level (P=0.051). Additionally, the autistic and normal children showed no significant difference regarding the DMFT index in the primary (P=0.53) and permanent (P=0.85) teeth. Moreover, the autistic children had more unmet dental needs in primary dentition, compared to their normal counterparts (P=0.002).
As the findings of the study indicated, the autistic and normal children had comparable DMFT index. However, the unmet dental needs of the autistic children in the primary dentition were higher than those of the normal children.

Osteosarcoma of jaw bones is the most common primary malignant bone tumor arising from mesenchymal cells capable of producing steoid; this disorder predominantly occurs in the long bones and rarely involves the maxillofacial region. Normally, this disease presents in the third and fourth decades of life, is slightly more common in men than women, and affects the mandible and maxilla in the same proportion.
Case report: An 8-year-old girl was referred to an oral and maxillofacial surgeon due to tumoral lesions in the posterior mandible in Sari, Iran. After the surgery, histopathological examination of the tumoral lesions revealed fibroblastic osteosarcoma. Further, immunohistochemical markers were evaluated, results of which approved final diagnosis of mandible osteosarcoma.
Given that osteosarcoma of jaw bones share the same clinical manifestations with benign lesions, misdiagnosis is highly common and diagnosis is challenging for dentists. Accurate diagnosis and early referral are critical in prognosis and survival of patients.