Journal of Dentistry, Shiraz University of Medical Sciences
Volume:14 Issue: 4, Dec 2013

Statement of Problem: Most failures of root canal treatments are caused by bacteria. Studies showed that the most common cause of endodontic failures were the incomplete obturation of the root canal and the lack of adequate apical seal. Some in-vitro methods are used to estimate sealing quality, generally by measuring microleakage that allows the tracer agent to penetrate the filled canal. Conventional methods of evaluating the seal of endodontically treated teeth are complicated and have some drawbacks. We used copper ion diffusion method to assess the leakage and the results were compared to dye penetration method. The crowns of 21 extracted teeth were cut off at the CEJ level. After preparing the canals, the teeth were placed in tubes containing saline. They were divided randomly into 15 experimental cases; 3 positive and 3 negative controls. Positive controls were filled by single cone without sealer while the experimental and the negative control groups were filled by lateral technique. The coronal portion of gutta was removed and 9mm was left. The external surface of each tooth was coated with nail polish. Two millimeters of apical portion was immersed into 9ml of distilled water and 0.3ml of CuSO4 solution was injected into the coronal portion. After 2 days, copper sulfate was measured by an atomic absorption spectrophotometer. The teeth were then immersed in 2% methylene blue for 24 hours, sectioned and the extent of dye penetration was measured by a stereomicroscope. The maximum and minimum recorded copper ion concentrations for the experimental group were 18.37 and 2.87ppm respectively. The maximum and minimum recorded dye penetrations for the experimental group were 8.5 and 3.5mm respectively. The statistical analysis, adopting paired samples test, showed poor correlation between average recorded results of two methods. Based on our results, there was no significant correlation between the dye penetration and the copper ion diffusion methods.

Statement of Problem: Dilaceration is defined as a sudden change in the axial inclination of root or between the crown and the root of a tooth. There is no previous study evaluating its prevalence in south of Iran. This study evaluates the prevalence of root dilaceration on the basis of its location in dental arch in a sample of dental patients referring to Shiraz dental school, Iran. This retrospective study was performed using full mouth periapical radiographs of 250 patients who were referred to Shiraz dental school. Buccal and lingual dilaceration was determined by its known” bull’s eye” appearance in the radiographs or if the deviation was in the mesial or distal directions; the angle of 90 degree or greater between the deviation and the axis of root was the inclusion criteria. Root dilaceration was detected in 0.3% of teeth and 7.2% of patients. It was distributed equally between the maxilla and mandible. Mandibular second molar was the most frequent dilacerated tooth (1.6%) followed by maxillary first molar (1.3%) and mandibular first molar (0.6%). The alveolar nerve was the most common anatomic structure near dilacerated teeth. According to this study, root dilaceration is an uncommon developmental anomaly which occurs mostly in the posterior teeth.

Statement of Problems: Dental age can be estimated on the basis of the tooth mineralization level during the developmental process of the teeth. Among various radiological methods reported for the dental age determination in children, Demirjian method is widely used. To evaluate the applicability of Demirjian method in age estimation of the children aged 7-15 years in Babol, a northern city of Iran. A cross sectional study was performed on the panoramic radiographs of 168 individuals with 7-15 years old. Maturation of the seven permanent teeth on the left side of the mandible was determined according to the crown and root development stages; described by Demirjian method. The mean of the dental age (DA) according to the Demirjian was compared to the mean of chronological age (CA). Data were collected and analyzed using SPSS, V18. P-values<0.05 were considered significance. The mean and the SD of CA was 11.06±2.29 (boys: 11.08±2.31, girls: 11.03±2.28). The mean and the SD of DA was 11.44±2.85 (boys: 11.81±2.93, girls: 11.08±2.73) and the mean and the SD of DA minus CA for all of the children were 0.38±1.24 (boys: 0.72±1.2, girls: 0.05±1.21). Also, t-Test analysis showed the differences of the mean value of the estimated - chronological age difference was statistically significant between the boys and the girls group (p< 0.001). Considering the determined differences between estimated dental age and chronological age in this study; Demirjian method can be applicable for estimation of dental age in girls and boys before their puberty in northern of Iran.

Statement of Problem: Basal cell carcinoma (BCC), the most common skin cancer, is a locally invasive malignant epidermal tumor with ulceration and destruction of underlying structures. The purpose of this study was clinicopathological evaluation of BCC in the state and the private pathology centers in Hamadan province during 1990-2010. In this retrospective study all histopathologically proven cases of BCC were reviewed and the related information including age, gender, place of residency and number of tumors for the patients alongside with the site of occurrence, size, histopathological and clinical type of the lesions were collected and then statistically analyzed, using SPSS software. A total of 804 incidents ofBCC were diagnosed in 746 patients (296 females and 450 males) with the most affected site being in the head-face (84.8%), neck (2.6%), trunk (1.6%) and limbs (0.9 %) and 10.1% cases with unknown site. The mean age for the patients was 61.77±13.75 years (63.07± 13.44 for males, 59.81 ± 14.01 for females) and the highest frequency (27.2%) occurred among 60–69 years age group. Nodular type was the most common clinical and histopathological BCC lesions studied whereas the mean size of the lesions was 15.67 ± 11.06 mm with more frequency rate in urban than rural regions. This study focuses on the survey of BCC in Hamadan province but regarding to insufficiency of the data collected by state and provincial pathology centers about the BCC cases reported; it is highly recommended to apply comprehensive questionnaire, which are designated by skillful professionals who are familiar with the lesion nationally.

Statement of Problem: Two potential problems commonly identified with a denture base incorporating a resilient liner are failure of the bond between acrylic resin and soft liner material, and loss of resiliency of the soft liner over time. Since patients may drink different beverages, it is important to evaluate their effects on physical properties of soft lining materials. The objective of this in vitro study was to evaluate the effect of different beverages on the hardness of two temporary acrylic-based soft lining materials and their bond strength to the denture base resin. For the hardness test; a total of 80 rectangular specimens (40mm×10mm×3mm) were fabricated from a heat-polymerized polymethylmethacrylate. Two commercially auto-polymerized acrylic resin-based resilient liners; Coe-Soft and Visco-gel were prepared according to the manufacturers’ instructions and applied on the specimens. For the tensile test, 160 cylindrical specimens (30mm×10mm) were prepared. The liners were added between specimens with a thickness of 3 mm. The specimens of both soft liners were divided into 4 groups (n=10) and immersed in distilled water as the control group, Coca-Cola, 8% and 50% ethanol. All groups were stored in separate containers at 37oC for 12 days. All beverages were changed daily. The hardness was determined using a Shore A durometer and tensile bond strength was determined in a ZwickRoell testing machine at a cross-head speed of 5mm/min. The results were analyzed using two-way ANOVA. There was no significant interaction between the soft liners and the drinks for both hardness (p= 0.748) and bond strength (p= 0.902). There were statistically significant differences between all drinks for both hardness (p< 0.001) and bond strength (p< 0.05). Within the limitations of this study, it seems that drinking Coca-Cola and alcoholic beverages would not be potentially causing any problems for the temporary acrylic soft liners.

Statement of Problem: Clinicians use the NiTi coil springs frequently for its appropriate mechanical properties. The aim of this study was to determine the effect of recycling and autoclave sterilization on the unloading forces of NiTi closed coil springs. Fourteen NiTi closed coil spring with the length of 9mm were selected. Each coil was stretched to a peak extension of 12 mm. A universal testing machine was used to acquire load/deflection curve of the coil springs at 25±2°C. The influence of thermocycling (1000 cycles,5-55°C), autoclaving (134°C, 32PSI, 3min) and mechanical strain (9mm extension) which simulated the oral condition, were considered. Data were statistically analyzed by adopting Repeated Measures MANOVA Paired t-Test. Autoclaving in the 1, 4, 6 steps increased the force levels of coil springs about 2-5gf (p< 0.01). Thermocycling reduced their force levels about 4-6gf. Prolonged strain at 3, 5 steps decreased the magnitude of forces levels about 3-4gf. Concerning all the limitations; according to the results of this study; it is possible to recycle Ni-Ti closed-coil springs without significant reduction in their force levels.

Statement of Problem: The increase in the use of metal-ceramic restorations and a high prevalence of porcelain chipping entails introducing an alloy which is more compatible with porcelain and causes a stronger bond between the two. This study is to compare shear bond strength of three base-metal alloys and one noble alloy with the commonly used VMK Master Porcelain. Three different groups of base-metal alloys (Ni-cr-T3, Super Cast, and VeraBond) and one group of noble alloy (X-33) were selected. Each group consisted of 15 alloy samples. All groups went through the casting process and change from wax pattern into metal disks. The VMK Master Porcelain was then fired on each group. All the specimens were put in the UTM; a shear force was loaded until a fracture occurred and the fracture force was consequently recorded. The data were analyzed by SPSS Version 16 and One-Way ANOVA was run to compare the shear strength between the groups. Furthermore, the groups were compared two-by-two by adopting Tukey test. The findings of this study revealed shear bond strength of Ni-Cr-T3 alloy was higher than the three other alloys (94 MPa or 330 N). Super Cast alloy had the second greatest shear bond strength (80. 87Mpa or 283.87 N). Both VeraBond (69.66 MPa or 245 N) and x-33 alloys (66.53 MPa or 234 N) took the third place. Ni-Cr-T3 with VMK Master Porcelain has the greatest shear bond strength. Therefore, employment of this low-cost alloy is recommended in metal-ceramic restorations.

Regional odontodysplasia is a rare dental anomaly affecting both primary and adult dentitions in the maxilla or mandible or both jaws, whilst involvement of the maxilla is more common [1-2]. In most cases, one quadrant is affected. One of the characteristics of this anomaly is discolored and soft teeth that can be accompanied by swelling or abscess. In this anomaly, enamel and dentin are thin and hypoplastic, therefore, the teeth give the impression of “ghost teeth” [2, 8]. In radiography, the delineation between enamel and dentin is not clear and pulp chamber is wide. Histologically, areas of hypocalcified enamel are observed and the enamel prisms appear to be irregular in direction [2]. There is a disturbance in dentin formation and dentinal tubules are reduced in number. The etiology of regional odontodysplasia is still unknown [8]. Managements of these cases should be based on the esthetics and functional needs as well as the degree of involvement.This report describes a case of regional odontodysplasia in a 3.5 year old Iranian girl whose chief complaint was the abscess formation in the left maxillary primary molar region. This case study aims to report the clinical and radiological findings of the current case.

Oral Lichen Planus is a chronic inflammatory disease of unknown etiology. Erosive/ ulcerative oral lichen planus is often a painful condition that tends to become malignant, urging appropriate therapy. Laser therapy has recently been suggested as a new treatment option without significant side effects. This article presents two cases of erosive/ ulcerative oral lichen planus, who had not received any treatment before, treated with 630 nm low level laser. Lesion type and pain was recorded before and after treatment. Severity of lesions and pain were reduced after treatment. Low Level Laser Therapy was an effective treatment with no side effects and it may be considered as an alternative therapy for erosive/ulcerative oral lichen planus.