Journal of Dental School
Year:2010 | Volume:27 | Issue:4 (82)|Papers Count:12

Background and Aim: Metal ceramic restorations are widely used in crowns. The marginal fitness of these artificial crowns is prone to alteration during the firing cycle of porcelain. Gold electroformed metal-ceramic restorations have been introduced as alternatives to conventional metal-ceramic restorations. However little is known about the relationship between procelain firing procedures and marginal adaptation of this type of crown. The aim of the present study was to evaluate the influence of firing procedures on the marginal adaptation of electroformed metal-ceramic crown restoration.Materials & Methods: One steel die was prepared for maxillary molar crowns with deep chamfer finishing line design. Ten standardized gold electroformed copings were fabricated. Marginal discrepancy was measured at four sites along the circumferential margin of each coping (Midbuccal - Midpalatal - Midmesial - Middistal) using SEM (Mag: X400) prior to and after porcelain firing procedure. Data among the 2 different groups (before porcelain firing) were statistically analyzed using the paired t-test (a=0.05) analysis.Results: The marginal discrepancy of the postfiring procedures (21.45±2.27 mm) were significantly greater than those of the prefiring procedures (18.23±1.96 mm) (p<0.002).Conclusion: The porcelain-firing procedures influenced the marginal distortion of electroformed metal-ceramic crown restorations, but the marginal discrepancies for all copings and examined design are clinically acceptable (less than 100 mm).

Background and Aim: Anthropometric measurements can be correlated to cephalometric values and have a complementary role to facilitate diagnosis. This Study aimed to determine the correlation between lateral cephalometric and anthropometric indices in the Iranian population.Materials & Methods: A cross-sectional study using Anthropometric-Cephalometric indices was carried out on 26 subjects with normal occlusion and harmonious facial ratios. Fiberglass meter, wooden ruler and millimetric Anthropometer (Aesculap Inc.) was used as well as hand-made instruments to measure the palm length and angles of the hand. General measurements including height and weight were also taken. For cephalometric measurements, radiographs were taken by an oral and maxillofacial radiologist. Data were subjected to SPSS 9 software. To determine the normal distribution Kolmogorov-Smirnov test was used and P<0.05 was considered significant. Also Spearman and Pearson coefficient correlation was calculated and t-test was performed. Results: In 12 of the 26 cases the correlation coefficient regarding the bizygomatic width (FW) with lower face height (LFH), SE, S-Gn; facial height (FH) with Pog to NB, Nasion-Menton; upper lip vermilion with SE, weight with ANB, Ar-Go; LFH with Ar-Go, forearm length with angle of facial convexity, height with Na-ANS were significant at p<0.01. There was correlation between LFH and FW and Facial Depth that infers three-dimensional proportional facial growth.Conclusion: The forearm length and the facial convexity angle (non-craniofacial anthropometric indices) have a negative co-efficient of correlation. This means that the longer the forearm the straighter the profile. Though there are numerous statistically significant relations between anthropometric and cephalometric indices, in this study these relations were not so clinically momentous in most of the cases.

Background and Aim: Microbial contamination of dental unit surfaces and materials are of considerable importance since patients and dental staff is regularly exposed to aerosols generated from the dental unit and contaminated surfaces. The aim of this study was to investigate the effect of BIB forte in disinfection of dental instruments. In this study we assessed the composition of aerobe and facultative anaerobe bacterial micro flora before and after administration of BIB forte.Materials & Methods: In this experimental study, 30 microbial samples were obtained from dental instruments before administration of BIB forte and were subjected to microbiological evaluations. The samples were cultured on the specific media and number of the bacterial colonies was counted after keeping at 37 degree centigrade for 24 hours. The effect of BIB forte was also investigated on standard lab species and the number of formed colonies was counted. Data were analyzed by SPSS; Chi-square and Fisher’s exact tests were used.Results: 93% of all species samples were positive regarding presence of bacteria. Microorganisms isolated were mainly composed of: staphylococcus aureus, streptococcus, corynebacterium, Neisseria and Bacillus species. BIB forte significantly reduced the microbial contamination after applied on dental surfaces and prevented the growth of standard microorganisms’ in-vitro. Conclusion: BIB forte is effective in reducing the bacterial load to an acceptable level and its usage is recommended as an ideal disinfectant in routine dental practice.

Background and Aim: Given the current need for studies evaluating oral health related quality of life among the Iranian children, this study was designed to test the validity and reliability of a Persian version of Child-OIDP index and also evaluate the prevalence and impact of oral disorders on the quality of life of 11-14-year-old Iranian children.Materials & Methods: In this cross-sectional study, after translation of Child-OIDP instrument into Persian language, the psychometric properties of this index were evaluated in terms of face, content and construct validity. In addition, the internal and test-retest reliability were evaluated. A sample of 384 Iranian children aged 11-14-years old completed the instrument via a face-to-face interview. Each interview was followed by a clinical examination as well as completion of a self-administered questionnaire providing the information on demographic and oral health behaviors.Results: The Persian version of Child-OIDP demonstrated excellent validity and reliability. The index showed significant associations between perceived oral treatment needs and perceived satisfaction regarding their oral cavity (P<0.001). ICC was 0.784, and Cronbach’s alpha was 0.59. About 54% of children reported dental disorders over the past 3 months that impacted on daily performances, according to Child-OIDP index. The most prevalent affected activities were eating and oral hygiene performance. The most prevalent oral disorder leading to impact were sensitivity tooth and gingival bleeding.Conclusion: Based on the results of this study, it can be concluded that the Persian version of Child-OIDP index is a valid and reliable instrument for evaluation of oral health-related quality of life as applied to Iranian children. The prevalence of oral impacts was moderate. The pattern of impacts differed according to the type of self-perceived oral problem.

Background and Aim: Saliva contamination is the main reason for the failure of sealant therapy. The aim of this study was to evaluate the effect of three types of adhesives (Single Bond, Adhes and I Bond) on sealant microleakage in saliva-contaminated enamel.Materials & Methods: In this experimental study, 54 intact premolars were chosen and divided into 5 groups. Group 1: teeth were etched and sealed with sealant. In groups 2, 3 and 4: teeth were etched and exposed to saliva for 10 seconds and air-dried. Subsequently, a bonding agent (Single Bond, Adhes and I Bond) was applied prior to the sealant application and curing. In group 5: after being etched and contaminated, the teeth were sealed without any bonding agent. After thermocycling, the teeth were immersed in fuchsin 0.5% as a leakage tracer for 24h.Then the teeth were sectioned in a longitudinal direction. Samples were then evaluated using stereomicroscope. The findings were statistically analyzed using Kruskal - Wallis and Dunn tests.Results: The extent of microleakage in saliva contaminated sealant without bonding agent group had significant difference compared to the Single Bond, Adhes and I Bond groups (p<0.05). Although the amount of microleakage in study groups was less than the non-contaminated fissure sealant group, the difference was not significant. Besides, there was no significant difference between Single Bond, Adhes and I Bond groups.Conclusion: Exposing enamel to saliva after etching would increase the microleakage. Using Single Bond, Adhes and I Bond the dentin adhesives, after salivary contamination would decrease the microleakage to the extent of uncontaminated sealant group.

Background and Aim: Squamous cell carcinoma is the eighth common cancer and forms 94% of oral malignancies. Nowadays, many molecular and genetic changes have been known to affect tumoral behavior which might be good for drug production and gene therapy. It has been known that mutated P53, overexpression of P63 as an oncogene and HPV infection are correlated with clinicopathological behavior of oral squamous cell carcinoma (OSCC) and it’s prognosis and overall survival rate. The aim of this study is to determine the correlation between the expression of P53, P63 and HPV infection with oral squamous cell carcinoma and it’s clinical staging and microscopical grading.Materials & Methods: Forty paraffin blocks with diagnosis of OSCC were collected from the pathology department, Shahid Beheshti School of Dentistry and the Department of general pathology, Taleghani hospital. Immunohistochemical staining was performed with antibodies against P53 and P63 and for detection of high risk types of HPV (HPV16, 18) polymerized chain reaction (PCR) was used. Spearman correlation test was used for data analyzing.Results: In this analytical cross-sectional study, we found significant correlation between P53 total score and staging (P=0.0001) and P53 total score and grading (P=0.013). There was also significant correlation between P63 proportional score and grading (P=0.049). HPV16 also had significant correlation with P53 total score (P=0.003). The mean nuclear staining of P53 was 33.04±25.66% (CI=24.94-41.14) and P 63 was 39.25±19.35 (CI 33.13-45.37). HPV frequency was 40% (HPV 16=20% and HPV18=7.5%). There was no significant correlation between P63 and HPV infection (P>0.05).Conclusion: We concluded that P63 could be a diagnostic marker for grading of OSCC and P53 and P63 expression might have some role in progression of OSCC and its clinicopathological behavior. Presence of HPV especially HPV 16 may be regarded as a risk factor in OSCC.

Background and Aim: Penetrating Knife injuries to the maxillofacial region are quiet rare and infrequently reported. In these few reports knife involves various fossae: Orbit, Maxillary & etmoidal sinus, blood vessel or throat. It can cause hemorrhages, neurological lesions, visual acuity loss and fracture.Case Report: The reported case is a 28 y/o man in whom a knife has penetrated from below the zygomatic arch crossing the intercondylar notch and coronoid, petrigoid plate and reach throat fossa without affecting vital structures such as skull, sinuses or main vascular branches. The approach to treatment and surgery plan should be multidisciplinary.Conclusion: Surgical removal of complicated foreign body penetrations involving vital structures in maxillofacial region is a very tender and sensitive approach. Knife specially endangers some important organs such as facial nerves and main vascular trunks. The knife was removed from the entrance wound in throat and no complications were observed either during or after surgery with any untoward sequelae.

Background and Aim: Determining the true hinge axis point in order to transfer the orientation relation to articulator is of great importance in reducing occlusal errors. Because of the high cost and time consuming nature of kinematic method in determining hinge axis point, different arbitrary methods have been introduced which rendered controversial results throughout literature. The aim of this study was to evaluate some arbitrary methods for determining hinge axis point and to introduce a precise arbitrary method which has the least distance from kinematic point.Materials & Methods: This cross-sectional study was performed sequentially on 40 subjects without any TM- disorders with an age range of 21-37. At first true hinge axis point was determined by DENAR hinge axis locator and marked bilateraly on the skin. Then 3 arbitrary points (Beyron, Gysi, Tetruck & Laundeen) was also determined by a flexible ruler and marked on the skin. The distance between the arbitrary points and kinematic point was measured and the data were charted and subjected to Repeated ANOVA and Paired sample test.Results: According to the results of the study, Beyron method was significantly more accurate than the other two methods. 88.88% of Beyron points were within 3 mm distance from kinematic point, but the other points didn't show any significant difference with each other.Conclusion: It is concluded that Beyron method has a high accuracy as an arbitrary method and because of its proximity to the true point, application of this method is recommended.