JOURNAL OF ISFAHAN DENTAL SCHOOL
Year:2010 | Volume:6 | Issue:2|Papers Count:10

Introduction: Malocclusion is caused by genetic, environmental, and acquired factors. Respiratory disorders and decrease of air flow in nasopharynx are known as etiologies for malocclusion. The aim of this study was to examine occlusion characteristics of preschool children in Tabriz who suffer mouth breathing.Materials and Methods: This was a cross sectional, descriptive and analytic study. Sixty four preschool children from five districts in the city of Tabriz were put into the case and the control groups. Impression from the samples were prepared and the casts were studied for arch symmetry, arch form, inter molar and inter canine width, overjet, overbite, molar relationship, posterior cross bite and crowding. Finally the data were analyzed and compared through SPSS (a=0.05). Results: Although there were signs of malocclusion in the case group, occlusion indicators did not show any statistically significant differences between the case and the control group.Conclusion: The results of the current study show that mouth breathing does not have remarkable effects on occlusion characteristic during childhood. However, the intensity of nasal obstruction may have an influence on malocclusion.

Introduction: Tooth brushing is a common oral health habit worldwide. Therefore hygiene of toothbrushes can play an effective role in maintaining oral health. Several factors can affect microbial contamination of toothbrushes. The aim of this study was to investigate the effectiveness of chlorhexidine 0.2% solution on toothbrush decontamination.Materials and Methods: In this experimental study, a total of 84 sterile, similar toothbrushes were given to 42 individuals in two seperate sessions. In the first session, subjects washed their brushes in the usual way after brushing their teeth. In the second session, the brushes were put in a solution of chlorhexidine 0.2% following their application by the subjects. At the end of each session, toothbrush heads were detached under sterile conditions and were put in the phosphated buffer solution (PBS) before being sent to the laboratory for microbial culture. The collected data were analyzed using Wilcoxon test with a confidence rate 0.95.Results: There was a statistically significant difference in bacterial contamination on toothbrush heads between the two sessions (P value=0.009). In the first session (simple rinsing) 21.4% of toothbrushes were contaminated while in the second session (using chlorhexidine 0.2%) only 2.4% of samples were contaminated.Conclusion: The results of this study revealed that chlorhexidine 0.2% reduces bacterial contamination on toothbrushes. This solution is easily available and is also helpful for other oral purposes.

Introduction: Microleakage is one of the most important complications of direct tooth-colored restorations. One of the described methods to reduce microleakage is the use of bonding agents after finishing restorations. The purpose of this study was to evaluate microleakage associated with class V composite restorations while using rebonding on restorative margins.Materials and Methods: A total of 48 extracted caries-free human premolars were selected. Class five cavities were prepared on the buccal surfaces of all samples. Occlusal margins were placed in enamel while gingival margins were placed in dentin.Teeth were randomly divided into four groups of 12. Group 1 was considered as the control group, which was restored without rebonding. In groups 2, 3 and 4, after finishing and polishing, rebonding was performed by Prompt L-Pop, permaseal and Clearfil SE Bond on the restoration margins respectively. Specimens were thermocycled for 500 cycles, sealed with two layers of fingernail polish except for the occlusal and gingival margins, and immersed in fuschine 2% for 24 hours. Specimens were longitudinally sectioned with diamond disk and studied under stereomicroscope. The data were analyzed with Kruskal-Wallis and wilcoxon tests. (a=0.05).Results: Kruskal-wallis test showed no statistically significant differences for microleakage on occlusal (P value=0.075) and gingival margins (P value=0.281) among the groups. Wilcoxon test showed significant differences between occlusal and gingival margins in Prompt L-Pop (P value=0.023) and permaseal (P value=0.026) groups, but between the other groups, this difference was not significant. (P<0.05).Conclusion: The three bonding agents applied in this study do not seem useful in decreasing microleakage into enamel and dentin margins.

Introduction: The length of styloid process usually varies from 20 to 30 mm. This process along with its attached ligaments is prone to mineralization. The aim of this study was to estimate the frequency of elongated styloid process (ESP) and Eagle’s syndrome on panoramic view X-rays.Materials and Methods: This descriptive - cross sectional study was performed on 618 radiographs (387 females and 231 males ranging from 11 to 75 years old) were included. The length of styloid process in each patient was measured with Planmeca ruler. Other necessary information such as age, sex, involved side, type of ossification, history of cervicopharyngeal trauma and the presence of relevant symptoms were also asked and recorded on each patient's file.Lengths equal to or greater than 30mm were consider as ESP. Data analysis was performed via Pearson, Chi-square and T tests. (a=0.05). Results: Mean lengths in males and females were 28.95mm and 26.82 mm respectively. ESP was confirmed in 225 patients (36.4%). The prevalence of ESP was 43% in males and 32.5% in the female patients (P value<0.05). ESP was seen with older ages. Bilateral involvement was more common than the unilateral form. Type (I) was the most frequent ossification type (81.1%). The frequency of symptomatic ESP (Eagle’s syndrome) was 1.2%. Among all the included cases, painful swallow was reported as the most common symptom.Conclusion: This study showed that symptomatic ESP is not so common. It is recommended that clinicians consider the possibility of elongated styloid process in patients with chronic maxillofacial pain.

Introduction: Salivary contamination of etched surfaces is an important cause of resin and composites bond strength reduction. The aim of this study was to evaluate the relationship between the duration of saliva exposure on the etched surface and the shear bond strength of braces and the enamel of the tooth.Materials and Methods: This was an experimental study which included 50 premolar intact teeth. After mounting the specimens, they were randomly divided into 5 groups of 10 teeth. In the first group used as our control, the braces were bonded without any saliva contamination. In the remaining four groups, samples were contaminated with saliva prior to resin application and the etched surfaces were cleaned after 1, 5, 10 and 15 seconds and then the resin was applied. After thermocycling, samples were subjected to shear force and the loads were recorded. The collected data were analyzed through ANOVA and Duncan post hoc tests using SPSS (a=0.05). Results: The groups showed significant differences (P<0.001). Pair wise comparison showed that there was no statistically significant difference only between groups IV and V.Conclusion: Contamination of etched surface with saliva reduces the bonding strength of braces. However, there was no significant difference between the contamination durations of 10 and 15 seconds.

Introduction: In addition to conventional radiography, several other techniques such as stereoradiography have so far been proposed to determine the position of impacted maxillary canines. The purpose of this study was to evaluate the diagnostic value of panoramic radiography and stereoradiography for determining the position of impacted maxillary canines.Materials and Methods: This was a prognostic, cross sectional study. A total of 30 impacted maxillary canines in 23 patients candidated for surgery were included. Four well coordinated observers separately determined the position of impacted maxillary canines using both panoramic radiography and stereoradiography. In the next phase, the exact position of impacted canines were determined through surgical exploration. Mc-Nemar and kappa index were applied for statistical data analysis. (a=0.05).Results: The rate of correct diagnosis in stereoradiography and conventional radiography was 93.35% and 60.82% respectively which demonstrated a statistically significant difference. With each method, there were no significant differences among observers. Sensitivity and specificity with stereoradiography were calculated 91.98% and 94.78% respectively. With conventional radiography however these values dropped to 49.90% and 74.11% respectively.Conclusion: Stereoradiography seems quite reliable for determining the position of impacted maxillary canines. On the contrary, conventional radiography per se does not look precise enogh to determin the position of impacted maxillary canines.

Introduction: The purpose of this study was to evaluate the fracture resistance of premolars with mesio-occluso-distal (MOD) preparations restored with two different resin composites along with three placement methods.Materials and Methods: In this in vitro study, sixty human sound maxillary premolars mounted in acrylic resin were randomly divided into two groups according to the type of composite restoration (Filtek P60, Nulite F). Each group was further subdivided into three subgroups according to the type of placement methods namely Bulk, Centripetal and Fibre Insert (n=10). The same adhesive system, Single Bond, was used for composite bonding following manufacturer's instructions for all teeth. Specimens in groups 1, 2 and 3 were restored with Filtek P60 resin composite while in groups 4, 5 and 6 Nulite F was applied. After 24 hours storage in 37oC, a 4 mm diameter steel sphere in Universal Testing Machine was contacted the buccal and lingual cusps of the tested teeth at a crosshead speed of 5 mm/min until fracture occurred. Data were subjected to analysis of variance and Duncan tests (p value<0.05).Results: Groups 3 and 6 showed a higher fracture resistance than other groups (P=0.001).Among the placement methods, Fibre insert showed a significant result (P=0.0001) but the type of composite was insignificant (P=0.791).Conclusion: It seems that on MOD cavities, contrary to the type of materials used, the insertion method, largely influences fracture resistance of premolar teeth restored with resin composite.

Introduction: Chondrosarcomas are malignant mesenchymal tumors with cartilaginous differentiation. Chondrosarcomas of the maxillofacial region are extremely rare lesions, accounting for approximately 1% of chondrosarcomas of the entire body. In most cases, the tumor presents as a painless mass or swelling with loosening of the associated teeth. The final diagnosis of the lesion is based on histopathological findings.Case Report: A 30-year-old man with a swelling over the lingual side of his mandible was admitted. The patient had no complaints of pain or tenderness in the region.The mass lesion was biopsied. Histopathological examination on the biopsied sample confirmed the diagnosis of chondrosarcoma.The patient was advised to undergo surgery and the tumor was resected completely.So far there has been no evidence of recurrence in the 6 month post operation follow up.Conclusion: Chondrosarcomas vary from a well-differentiated tumor resembling a benign mass of cartilage to a high grade malignancy with aggressive behavior and the potential to form metastasis.Tumor grade and resectability are the most important prognostic factors for head and neck chondrosarcomas. The treatment of choice for such lesions is wide surgical excision.

Using a post is a common method in providing the adequate retention for coronal restoration of endodontically treated teeth. With proper post selection, the success rate of this kind of treatment is considerable. In addition to post selection, some determining criteria including endodontic treatment, the remnant tooth structure, ferrule effect and some other factors should be considered.It is important to select a post with a proper length, diameter, type and material.Furthermore, modern brands of posts and contemporary cements have been introduced which assist dentists to present more variable treatment modalities.The endodontically treated teeth are very susceptible to fracture. Considering this fact that the occlusal forces partly transfer to the root through the post, an inappropriate post selection may enhance the tension on the post and on the root. The tensions can lead to three different situations: Loss of retention, post fracture and root fracture. Among these, the loss of retention is the most prevalent accident. However, root fracture would be probable if an improper post selected. Usually in this circumstance the final resort is tooth extraction.