مجله دانشکده دندانپزشکی مشهد
سال سی و هفتم شماره 1 (پیاپی 84، بهار 1392)

Lack of knowledge about root canal anatomy can cause mistakes in diagnosis، treatment planning and failure of treatment. Mandibular canine is usually single-rooted it may have two roots or more root canals. The purpose of this study was evaluating the number of root and root-canals of mandibular canine using digital radiography with different angles and comparing it with clearing method. This study was a diagnostic test. Two hundred human mandibular canine teeth were studied. Digital radiography of the teeth from mesiodistal، bacculingual and 200 mesial views were prepared. Radiographic evaluation was down by two observers (An oral radiologist and an endodontist) separately. Then dental clearing was performed. Data analysis was done using SPSS. Ver. 17 software and statistical tests of MC Nemar. P<0. 05 was considered significant. Out of 200 cases of mandibular canine teeth، six teeth had two roots. In clearing method 183 teeth (91. 5%) had single-canal and 17 cases (8. 5 %) had two canals، and 3 teeth were type II and 8 teeth were type III. Digital x-ray results in bacculingual view showed that 198 teeth (99%) were single-canal and 2 cases (1%) were two-canal، which showed a significant difference compared to the results of clearing method (P>0. 001). Findings of digital radiography in mesiodistal view showed that 180 teeth (90%) were single-canal and 20 teeth (10%) had two canals، which were not different from those of clearing method (P=0. 25). In 200 mesial view، 192 teeth (96%) were single-canal and 8 teeth (4%) had two canals، which were different from those of clearing method (P=0. 012). Despite the low prevalence of anatomical variations in mandibular canine in this in vitro study، due to the lack of significant difference of radiographic mesiodistal views compared to that of clearing technique، CBCT modality is recommended for obtaining fast and complete diagnosis of unusual root canal.

The posterior palatal area is the most important area for retention of maxillary dentures and must be considered carefully during and after the reline. The purpose of this in vitro study was to compare the posterior palatal seal in relined complete dentures with two different methods.

An average size of edentulous maxillary acrylic arch without undercuts was selected in this in vitro study. The alginate impression was made of this model ten times and was poured with a type IV gypsum product، and the casts of control groups were prepared. Then 10 definitive bases were created for each cast. For the experimental groups، one relief wax layer with a thickness of 2mm was put in post-dam area for relining processes. Then، 20 alginate impressions were made of this model. On definitive base، clear heat-cured acrylic bases were fabricated. In experimental groups، bases were divided into 2 groups of 10: first group was relined with heat-cured acrylic resin and another one was relined with cold cured acrylic resin. All of the bases were put in distilled water for two weeks and then each of them was placed on the definitive base. One code was considered for each model. The gap in posterior area between acrylic bases and arch was measured in five points (a-b-c-d-e: mid line، two points in hamular notch، and two points between midline and hamular notch) by two practicers in two different times (during two weeks) with light B×60 microscope. The data were analyzed by Tukey and Kruskal Wallis tests.

The results of this study indicated that there was a statistically significant difference in the amount of gap at point A between control (bases without reline) and experimental groups (P=0. 047). At point D there was no significant difference between experimental groups، but a significant difference was detected between control group and bases relined with cold cure acryl (P<0. 05).

The results of this laboratory study indicated that there was no significant difference between relining methods with heat-cured and cold cured acryl reline method). So cold cured acryl could be recommended because it is more economic، easier and more time savory compared to heat-cured acryl.

Increasing use of dental radiography makes necessitates of increasing awareness and appropriate performance about ionizing radiation protection. The present study was done with the aim of evaluation of awareness، attitude and performance levels of dental practitioners in the city of Isfahan about ionizing radiation and protection against them. In this descriptive-analytic study a questionnaire including questions for evaluating of awareness، attitude and performance levels and demographic information was distributed among 184 dentists in the city of Isfahan. The data were analyzed by means of student t test and Pearson correlation coefficient in SPSS software (α=0. 05). In the present study 73. 2% of dentists had weak awareness level 25. 6% and 1. 2% of dentists had moderate and good awareness levels respectively. Twentyfour and 76 percent had good and apathetic attitudes. Ten and 4. 5 percent of dentists have been using lead apron and thyroidal necklace for their patients respectively. Experience and awareness had significant inverse correlation with eachother (P=0. 004، r =-0. 218). According to the results of the presents study، the awareness of dentists was weak and academic education as well as post-graduate education is necessary.

The use of fast films is one of the major factors contributing to dose reduction. However، the diagnostic ability of fast film must be determined before current use of the films. The purpose of this study was to compare the efficiency of D and F speed films in the diagnosis of proximal caries. Eighty proximal surfaces in 40 extracted unrestored premolars were undergone radiography in standardized conditions using D- and F-speed flowdental intraoral films. True caries diagnosis was based on histological assessment of the surfaces after sectioning the teeth. Two observers read the radiographs using a four-point scale to record their diagnosis. Observer responses were evaluated using ROC analysis and areas under the ROC Curves (Az) was microscopical assessed by pairwise comparison of ROC Curve. D and F speed films had a mean Az of 0. 934 and 0. 920 respectively. The difference was not statistically significant (P=0. 548) Difference between observers was also not statistically significant. The efficiency of the new F-Speed films was not statistically different from that D Speed films in caries detection. This film shows the ability of reducing patient’s dose while maintaining diagnostic quality.

Biological matrix has received special attention in recent medical and biological researches. Cells of tissue are supported by extracellular matrix (ECM). Extracellular matrix is used as a scaffold for morphogenesis، proliferation، migration، and differentiation in tissue engineering. Extracellular matrix of natural tissues can be used as a scaffold for reconstructing biological tissues in tissue engineering. Human maxillary sinus membrane consists of cells and ECM which contain collagen، elastin، and proteoglycans. Collagen can be used as a natural scaffold via high level of biocompatibility. In this study، Human maxillary sinus membrane were decellularized by two techniques، physical method (liquid nitrogen) and chemical procedures via increment concentration of sodium dodecyl sulfate (SDS) in three groups. The samples were fixed with Bouin''s fixator، and then were stained with Hematoxylin & Eosin. decellularised Human maxillary sinus membrane was evaluated with scanning electrone microscope. Histological evaluation of decellularized scaffolds revealed that cells of the schneiderian membrane tissues were completely removed via concentration of 1% of SDS. Scanning Electrone Microscope (SEM) (Leo-VP1450، Germany) of the scaffolds indicated that collagen fibers of connective tissue remained intact. In 0. 5 and 0. 1% concentrations of SDS، few cells were observed at peripheral of ECM، so decellularization process was not complete. According to the results، scaffolds prepared from Human Maxillary Sinus Membrane could be used as a suitable scaffold for In vitro investigation and reconstruction and tissue engineering.

Bacterial plaque has been identified as the primary factor for the onset of periodontal disease. Although pathogens are very important in the pathogenesis of periodontal diseases، the hosts’ systemic and predisposing factors should also be considered. Sex hormones are important factors contributing to periodontal diseases. The purpose of this study was to investigate the effects of menstruation cycle on periodontal indices. In this study، 20 premenopausal women (17-45 years old) were selected. Before the examination، scaling and oral health instruction for all subjects was done. Clinical examinations were done during the menstrual cycle specifically during ovulation (OV) time، during pre-menstruation (PM) and during menstruation (M) with four month in tervals. Indices evaluated included: 1) Plaque index (PI) 2) Gingival index (GI) 3) Probing depth (PD) around the (Ramfjord teeth). Friedman test was used for comparison among the three durations and for two by two comparisons، Wilcoxon test was used. Results showed a significant difference among the phases of the menstrual cycle for gingival index (P<0. 05)، and during the menstruation، the inflammation was significantly less than the other stages but PI and PD did not show significant differences during menstrual cycle (P>0. 05). During menstrual cycle due to the hormonal changes، gingival index and inflammation is significantly increased indicating that in order to prevent periodontal diseases، oral health should be maintained.

It has been a decade since the course “Community Oral Health” has been revised. The aim of this study was to evaluate how the course of community oral health is being taught in the undergraduate program of dental schools in Iran after a decade of revisions. In spring 2010، dental schools have been requested to report how the course of community oral health is being taught in terms of content and format، number of credits and the distribution of the credits along the curriculum، and the discipline of the teachers that teach this course. In total، 12 schools responded. The content of the course، in all the schools، was according to what had been formally authorized by the Ministry of health and the format of presentation was a mix of lecture، workshop، and field work. The most prevalent format of presentation even in some parts of practical credit was lecture; field work was rare. In 92% of the schools، this course consisted of one theoretical and five practical credits. More than half of the schools (58%) reported that the teachers of this course did not have a degree related to the community oral health. There are shortcomings in the mode of teaching the course of community oral health in dental schools in Iran. To improve the quality of teaching for this course، the department of community oral health needs to be strengthened and cooperation with this department must be enhanced inside the dental schools and as well between dental schools and university.

Operative dentistry is one of the most useful scopes in practice of dentistry. Recognition of weaknesses of dentists in this scope is very important and general dentists are the main sources to evaluate the operative dentistry curriculum and receiving feedbacks from it. The aim of this study was to evaluate the importance of the topics of theoretical and clinical courses of operative dentistry in general dentistry major curriculum by Mashhad Dental School alumni graduating between 2006-2010. A valid and reliable questionnaire to evaluate the topics of courses in theoretical course of operative dentistry and practical course (including different restorations and number of sessions) was distributed among 200 dentistry alumni. The data were reported descriptively. Response rate was 75%. Most of the responders evaluated that most of theoretical topics are important (more than 50%); Practical topics were mostly sufficient and it was recommended to increase the number of extensive composite restorations. According to alumni point of view of importance of defferent topics in operative dentistry curriculum، revision of the curriculum is in demand with special regard to extensive and cosmetic restorations.

Posterior composite restorations are the one of the most usual dental treatments among patients. The goal of this study was determining dentists’ problems during and after treatment of posterior – composite restorations in the city of Isfahan. In this descriptive-analytical study، we used a questionnaire including questions about the problems of posterior composite treatments during and after operation among dentists in Isfahan in 2009-2010. The data were analysed by chi-Square test. The most frequent problem during composite restoration was achieving good proximal contact (30. 8%) and after it، sensitivity of teeth while chewing which would not be repaired by correct occlusion (34. 8%). Most of the dentists pushed the matrix strip toward the adjacent teeth while polymerization، applied the composite in different layer، did the company instructions for bonding layer and used wet polishing during restoration. Most of the dentists (55. 8%) used two step total etch dentinal bonding and selected the composite because of its ability in making isolation and good restoration (42. 5%). Providing correct education for the dentists and increasing their knowledge about these restorations result in reduction of associated problems during and after the operation.

Multiple supernumerary teeth are a rare phenomenon. It occurs more often in patients with syndromes such as Gardner''s syndrome، cleidocranial dysplasia and so on. This phenomenon in absence of such syndromes is rare. The purpose of this report was to introduce a case of non-syndromic multiple supernumerary impacted teeth. Case Report: A 29-year-old woman with no skeletal، metabolic، systemic and mental disorder was referred to oral and maxillofacial department of Mashhad dental school. In clinical evaluation، seven Permanent teeth were missing. In radiographic evaluation، there were a total of 15 impacted teeth which 7 of them were supernumerary. Missing or Excess of one or more teeth usually leads to occlusal and functional problems. In these cases، a complete clinical and radiographic examination accompanieal by a precise history should be performed to plan a suitable surgical-orthodontic-prosthetic treatment.