Journal of Islamic Dental Association of IRAN
Volume:20 Issue: 1, 2008

The functional appliances can influence dentofacial growth of anterior-posterior posture of jaws. However, there would be some changes on other dimensions of face in pre-adolescent age group patients. The aim of this study was to demonstrate the influence of Fa II appliance on vertical and rotational growth of jaws in adolescent female cases. This clinical trial investigation was conducted with nineteen female CL II div.l participants who underwent functional therapy with Fa II appliance for 12-18 months. Lateral cephalograms were taken before and after treatment in order to compare them with untreated control subjects as well as the template group. Student t-test was used for statistical data analysis. The analysis of data showed that vertical dimensions were increased specially in lower part of the face (P<0.01). No rotational changes occurred on the upper and lower jaws (mandible P=0.86 and maxilla P=0.58). Direct relationship was observed between increasing vertical dimension on the posterior part of the face and forward rotation of mandible (P=0.004) and dentoalveolar drift of mandible with backward rotation (P=0.034). Based on the results of this clinical trial,the Fa II functional appliance can increase the vertical dimension of face (posterior-anterior) and help with rotation of both jaws in positive directions; which is preferable therapy for normal and short CL II cases.

Due to perfect adaptability, the flow able composite has been recommended to be used as the first layer of restoration in the gingival floor of the proximal cavities restored with composite filling materials. The objective of this in-vitro study was to evaluate the effect of using different shades of flow able composite as gingival increment on the micro leakage of posterior composite restorations. Total of thirty-six freshly extracted human sound premolar teeth were used in this laboratory investigation. Standard class II box-shaped cavities were prepared with proportional size and shape (3mm width, 2mm depth) with 1mm apical extension to CEJ. The teeth were randomly divided into 6 groups. Five shades of flow able composite resin A1,A2,A3.5,C2,D3, (Aeliteflow, Bisco, USA) were used as the first layer in the gingival portion of groups 2-6 respectively. All the rest of cavities were restored with hybrid composite A3 (Aelite, Bisco, USA), incrementally, and light cured through the proximal surface. After 24 hours of immersion in distilled water, the specimens were thermocycled (500 cycles, at 5-55 º C, with 30 seconds dwell time), sealed with nail varnish and immersed in 2% basic fushin solution for 24 hours. he restorations were sectioned longitudinally parallel to mesiodistal tooth dimension. Micro leakage status was evaluated using a 0-3 scoring scale. Data analysis was conducted using Kruskal-Wallis test at 0.05 significance level. No statistically significant differences were observed between the study groups (p>0.05) under investigation. The least and the most micro leakage values were related to group 1 and 6 respectively. All specimens restored with A1 demonstrated zero score for dye penetration. The use of flow able composite with A1 shade as gingival increment may decrease the gingival micro leakage compared with control group. It may be advisable to use flow able composite with lower chroma in posterior composite restorations.

Leukoplakia is one of the most common premalignant or potentially malignant lesions of the oral mucosa. It’s potential for malignant transformation is unpredictable.The aim of present study was to evaluate the expression of p53 and proliferation status of ki67 antigen in normal, homogeneous and non-homogeneous leukoplakia. The standard immunohistochemistry staining method (Biotin Streptavidin peroxidase) was used to study the expression of p53 and ki67 on formalin fixed, paraffin embedded blocks of 7 cases of homogeneous leukoplakia, 10 cases of non-homogeneous leukoplakia and 9 cases of normal oral epithelium. Data were analyzed using ANOVA, MC Nemar and Fisher’s exact tests. No relationship was detected between p53 protein and Ki67 expression and clinical features of leukoplakia. The distribution patterns of p53 and ki67 were mainly localized in the basal layer of normal oral mucosa, while the expression of p53 and Ki67 were extended into suprabasal cell layer in leukoplakia lesions. Ki67 expression in dysplastic lesions was higher than non-dysplastic lesions. This study showed significant relationship between Ki67 and p53 protein. These findings showed that the expression of p53 and Ki67 in suprabasal cell layers in leukoplakia may be correlated with poor clinical outcome and alterations of p53 lead to increased cell proliferation.

The accuracy and validity of CT scan images have been established by various investigators. However, there are controversies about the accuracy and validity of tomography techniques. The purpose of this study was to compare the accuracy and validity of diagnostic measurements made out of spiral tomography and spiral CT of human maxilla. Eight partially or fully edentulous dry human maxillae were used in this invitro investigation. A total of 50 edentulous areas were identified as potential implant sites. These locations were composed of 8 sites in midline, 14 in canine, 15 in premolar and 13 sites in molar areas. The spiral tomographies as well as spiral CTs were taken for the selected sites. The following bone parameters were measured in each maxilla: I) Vertical distance between the surface of alveolar bone and floor of nasal cavity or maxillary sinuses (Height). II) Buccopalatal alveolar ridge distance at the mid-height section(Width). Tomography measurements were compared with that of CT images in order to determine the measurements precision. To investigate the validity, the method of Inter-device Inter-observer and test of Intra-class Correlation Coefficient of One-Way Random Effects model was applied. Only 6 out of 100 measurements of tomography showed more than 1mm difference with CT images. The accuracy of tomograms in measuring height and width of alveolar bone was 96% and 92% respectively. This accuracy was 100% in midline, 93.3% in canine, 86.7% in premolar and 100% in molar area. The mean difference was 0.66mm Between measurements of these two techniques. The reliability of tomograms was %96. This investigation demonstrated that spiral tomography is highly accurate in cross sectional imaging of the jaw bones. The validity and reliability of spiral tomography technique is good and acceptable. Therefore, we can use tomography for jaw bones imaging in potential implant cases with high level of confidence.

The adhesives type and placement application technique may be important in long term stability and function of composite veneers. This study was conducted to evaluate the influence of dentin adhesive application techniques (pre-curing vs. non-curing) on micro leakage and marginal adaptation of indirect composite veneer restorations. A total etch bonding system, Excite/Variolink II (EXV), and a self-etching primer system, Panavia F 2.0 (PF2) were used in this in-vitro investigation. Forty-eight human central incisors were prepared for composite veneer restoration. These teeth were then divided into two groups (n=24). Pre-cure adhesive (PC) with light cure technique as well as no pre-cure (NPC) prior to resin cement insertion in half of specimens in each group. By using these methods, we worked with four experimental subgroups (PC+EXV, NPC+EXV, PC+PF2, NPC+PF2). Composite veneers (Tetric Ceram resin) were cemented using a dual-cured resin luting agents. All specimens were then stored in distilled water at 37oC for 24 hours before checking for marginal leakage. By random sampling, two specimens were selected from each group for SEM observations and evaluation of marginal adaptation at 1050 time magnifications. Data was analyzed by ordinal regression and link function of probit type at α ≤0.05. The highest and lowest micro leakage values were observed in dentinal margins of NPC+EXV and PC+EXV subgroups respectively. A significant difference was observed between dentinal and enamel margins on micro leakage values of PC and NPC groups (P<0.05), meaning that, pre-cure adhesive was more effective than resin cements alone. No adhesive layer was observed in non pre-cured adhesive specimens. The effect of pre-curing adhesive was not material specific. The pre-cured adhesives showed the best resistance to dye penetration, although the film thickness of luting agent was slightly increased.

Considering the high prevalence of dental caries, dentists and researchers are searching for restorative materials that are similar to tooth structure and are acceptable from biological point of view. The purpose of this study was to investigate the thermal behavior of a filled tooth with different restorative materials. Modeling was designed using solid ambient work software using the actual measurements of a typical human maxillary second premolar tooth dimensions. A class II (MOD) cavity was prepared and restored with amalgam and composite, with and without using Glass Ionomer as base material. Finally, the restored and non-restored tooth behavior was analyzed under thermal exposure when exposed to hot liquid. A three-dimensional finite-element analysis was conducted using ANSYS soft ware. Analysis of data revealed that placing base material under the amalgam fillings can decrease the maximum pulp temperature by about 43% compared to restorations without base. While, the temperature reduction was only about 17% in composite restorations. It was also found that the base material used under the amalgam fillings can protect the pulp from sudden temperature changes because of considerable time lapse between the application of thermal load and a change in pulp temperature. This time delay is greater in the composite restorations compared with amalgam by about 10% and the maximum time delay was found in sound tooth. The closest temperature profile to sound tooth is found in restorations with composite resin filled over a base material. This study demonstrated that the base material can protect the pulp from sudden temperature changes; likewise, it can decrease the maximum temperature in the pulp chamber/canal.

The introduction of magnetic resonance (MR) technology as a clinical imaging method has substantially increased the patient exposure to static, gradient and radio frequency of electromagnetic fields. The aim of this study was to assess the release of mercury from human dental amalgam restorations after exposure to electromagnetic fields produced by conventional MR imaging. The pre- and post-interventional study design was used for this investigation. The study participants were composed of individuals who were scheduled for brain MRI and those who had at least 4 teeth with amalgam restorations. These restorations had to be at least one week or older. Thirty individuals, who met the inclusion criteria, were referred to magnetic resonance imaging (MRI) department. A questionnaire was used for each patient to collect basic information on past exposures to electromagnetic fields, occupation and life style. Biological specimens (5cc stimulated saliva) were collected just before and after MRI procedures. The magnetic flux density was 0.23 T, and the patient’s duration of exposure to magnetic field was 30 minutes. The collected saliva samples were analyzed by laboratory for mercury level by using cold-vapor atomic absorption technique. The SPSS software and paired t-test were used for statistical analysis of mercury levels. The mean concentrations of mercury in saliva before and after MRI were 0.86 ± 0.3 mg /dl and 1.13 ± 0.5, mg /dl respectively. Data analysis using paired t-test showed a statistically significant difference between the mean concentrations of saliva mercury before and after MRI procedures. This study showed significant relationship between increased mercury levels in saliva of patients exposed to magnetic resonance imaging.

Pulpotomy is one of the most common treatments in decayed primary teeth with pulp involvement. So far various medicaments have been used for this procedure. The aim of this study was to compare the success and/or failure level of these materials by using clinical and radiographic measures. A total of 70 deciduous molar teeth of children aged 3-7 years-old who met our selection criteria were included in this randomized clinical trial. After pulpotomy the Iranian made and the original brand MTA was used. Amalgam was used for restoration of all teeth under investigation. The clinical and radiographic follow up was conducted blindly at 6 and12 months. Fisher’s exact test was used for data analysis. Based on the information collected over of one year follow up period, none of the teeth in Iranian MTA group demonstrated clinical and radiographic failure. In the original MTA group 1 tooth developed abscess and another showed furcation radiolucency. Based on these results the Iranian brand mineral trioxide aggregate can be used in primary molar teeth for pulpotomy treatment.

Basic science courses have long been the subject of debate for its usefulness among many clinicians. This investigation was conducted over the period of 2003 to 2005 in order to evaluate the views of graduating dental students on the quality, quantity and clinical applications of basic science courses on their daily clinical practice. A group of 175 final year dental students (both Male & Female) were asked to participate in this cross sectional investigation. A questionnaire was used to collect both qualitative and quantitative information about different basic science materials that were thought to them. Participants were dental students of Tehran, Shahed and Shaheed Beheshti Universities, the three major dental schools located in Tehran, the capital city. Mann-Whitney as well as Kruskal Wallis tests were used for data analysis. Based on the collected information, most of the students had a common belief that courses like "Human Anatomy", "General Pathology" and "Human Physiology" had the greatest influence in their daily practice while "Biochemistry", "Biophysics" and "Genetics had contributed the least. They also thought that the two courses of "Biochemistry" and "Microbiology" have been the focus of too much attention, while more emphasis needed for "Biostatistics", "Human Anatomy", "Genetics" and "Psychology" courses by the school curriculum committee and the teaching staff. Analysis of data revealed significant group differences between Shaheed Beheshti dental students and others in relation to importance of “Anatomy” “Psychology” and “Biochemistry” courses (P=0.005). The overall satisfaction was observed among all students of the three dental schools for "Microbiology", “Pathology”, "Public Health", “Physiology”, and "Biophysics" courses to some extent. There seem to be a slight difference in the amount of value and emphasis put forward by different schools on the basic science courses offered to dental students.

To date no product is available that have all the desirable properties of an ideal resilient material. Therefore, it is necessary to determine certain physical and mechanical properties of new soft liner materials that are introduced in the market. The aim of this study was to investigate several properties of Acropars compared to Molloplast B. Two groups of permanent resilient liner materials, a heat cured acrylic copolymer (Acropars; Marlik Medical Inc., Iran) and silicone based rubber (Molloplast B; Detax Ettlingern, Germany), were tested for hardness, elongation percentage, tensile and tear strengths.Ten dumbbell-shaped specimens were fabricated for each test group according to ASTM-D412 (Die-c) and ASTM-D638 (type 4) standards. The universal testing machine was used to test all specimens for tensile strength, elongation percentage. Ten cylinder shaped specimens of 31 × 10 mm (in diameter and height) were prepared for hardness test. This test was conducted, using a shore-A hardness instrument, according to ASTM-D2240 standards. Also the standard test method of ASTM-D624 for tear resistance of rubber material was performed. Ten bar shaped specimens of 60×10×2 mm, with a 45 degrees notch 6 mm in width on lower side were prepared. All specimens were forced to failure using a universal testing machine. All specimens were stored at room temperature for 40 hours before testing process started. The mean group differences and student-t test at α= 0.05 were used for statistical data analysis. Acropars showed statistically significant greater mean tensile strength (P<0.0001), tear strength (P<0.0001) and hardness (P<0. 0001) compared to Molloplast B. In addition Molloplast B showed a significant higher elongation percentage. (Pv<0.001) Within the limits of the present study, it was demonstrated that Acropars had higher tensile and tear strength, but harder than Moloblast B.

The absolute advantages of immediate loading of dental implants, such as time saving, immediate function and patient satisfaction, increases the demand for this protocol. In this article we report the results of literature review on conditions under which necessary for successful immediate loading and discuss the predictable conditions as well. Search of relevant published articles was conducted for the period between 1970 to 2007 in Medline, PubMed, Embase, Blackwell Synergy, Sciencedirect, Scholar google, Google and Yahoo databases along with manual search to identify pertinent English text-books. The key words used for this search were dental implants, immediate loading, early loading, delayed loading, occlusal loading and primary stability. Factors that may influence the success of immediate implant loading, including patient selection, type of bone quality, required implant length, micro- and macrostructure of the implant, surgical skills, the need for achieving primary stability/control of occlusal forces, and prosthesis guidelines, were thoroughly reviewed and discussed. Immediate loading is predictable in the anterior section of the mandible, irrespective of implant type and surface topography (success rate 90% - 100%). Limited evidence is available for edentulous maxilla and partially edentulous patients. Unfortunately most of the reviewed articles provided limited information due to study design and methodological shortcomings. Anatomical locations implant designs, and restricted prosthetic guidelines are a key to ensure successful outcomes. Future studies, preferably should be more of randomized control trials and prospective longitudinal studies are certainly needed before this approach can be widely used.

Human saliva can be easily obtained by non-invasive techniques. It contains many analytes of interest for screening, diagnosis and monitoring of normal and abnormal conditions. The protein c-erbB-2, also known as Her2/neu, is a prognostic breast cancer marker in women diagnosed with malignant tumors. The aim of this study was to assess the relationship between serum and saliva levels of c-erbB-2 in healthy women and untreated and treated patients with breast cancer. A case-control study design was used for this investigation. A total of forty two women were included in the study. Participants were matched for age and were divided into three equal groups. The collected specimens were evaluated for the expression of c-erbB-2 levels in serum and unstimulated whole saliva by ELISA technique. The ANOVA and Pearson Correlation were used for data analyses. Significant lower unstimulated salivary flow rate was observed in untreated cases in comparison with healthy women. However, no significant difference was detected in whole saliva output, as well as serum and saliva concentration of c-erbB-2 between the three groups. The correlation of c-erbB-2 between serum and saliva concentrations (r=0.02) and between serum concentration and saliva output (r=0.18) were not statistically significant. It seems that salivary and serum c-erbB-2 concentrations have no correlation in early stages of breast cancer and non-metastatic conditions.