Journal of Isfahan Dental School
Year:2009 | Volume:4 | Issue:4|Papers Count:10

Introduction: Cementing plays an important role in increasing the retention, stress distribution and seal of micro gap and porosity between post and tooth. The purpose of this study was determination and comparison of the mean retentive strength of cast posts with zinc phosphate, poly carboxylate, glass ionomer and resin cements.Methods and materials: Forty recently extracted human teeth were endodontically treated. Fore groups of 10 specimens formed. Post pattern made with acrylic resin and casting was fabricated using base metal alloy. Each group was cemented with 1 of 4 cements: Zinc phosphate, ploy carboxylate, glass ionomer and resin cement. Then, specimens mounted in acryl and tensile bond strength of them measured with a universal testing machine. The data analyzed by one-way ANOVA and Turkey test.Results: A significant difference between mean retentive strength of the cemented cast posts with these cements was shown (p value =0.06); after final assessment of Turkey test, it was appeared that the retention of posts cemented with poly carboxylate was significantly better than posts cemented with Zinc phosphate (p value =0.010). In addition, retention of posts cemented with poly carboxylate was significantly better than posts cemented resin cement (p value =0.012).Discussion: Despite the limitations of this study, the use of poly carboxylate cement provided greater retentive strength than the Zinc phosphate for cast metal posts. Between poly carboxylate, resin, and glass ionomer; however, there was no significant difference in terms of retention.

Introduction: This laboratory study deals with the effect of various environments in which the fractured part is kept before being bond to the remaining tooth on the required force to fracture the restored teeth by a re-attachment method.Materials & Methods: Seventy two mandibular incisor teeth divided into six groups of 12. The samples in 5 groups were fractured on middle one third, and the apical part of the remainders of teeth was dipped in normal saline. The environments where the fractured parts was kept in first to fifth group were, normal saline, water, milk, saliva and dry environment respectively. Sixth group was regarded as positive control group. After 24 hours all parts were bonded to the apical parts of the related groups by a bonding agent (Single Bond) and a flowable composite resin. The required force for the fracture was measured by a universal testing machine, and was analyzed by using Anova and Tukey statistical tests.Results: The required force to fracture the teeth in first to sixth group were 239.4, 231.2, 347.2, 328.6, 205.4, 693.3 Newton respectively. Statistical analyses indicated significant difference among the various groups (p value<0.001). The required forces for the fracture in third and forth group were significantly higher than first, second and fifth groups.Conclusion: The required force to fracture the restored teeth is affected by placing the fractured parts in various environments before bonding.

Introduction: Esthetic in dentistry requires the consideration of some indices. The frequency of these indices varies in different populations. This study was designed to determine the frequency of smile indices in students of Isfahan dental school.Method and materials: In this descriptive study 110 dental students were selected. A film was recorded from full smile of subjects. Computer photographs were prepared and the esthetic indices were measured on these photographs. Independent sample t-test was applied to determine whether a significant difference exist between the various means. The significance level was set at a=0.05.Results: Lip line was in middle position in 75.5% of cases, second premolars displayed in the corner of the mouth in 41.8%, position of the upper lip corners to the lower center of the upper lip was upward in 52.7%, maxillary incisal curve was parallel to the lower lip in 59.1%, incisal edge of the anterior teeth did not touch the lower lip in 58.2%, smile was symmetric in 81.8%, mandibular teeth were not displayed in 60.9%, negative space was present in 67.3% and midline was on, in 83.6% of subjects.Conclusion: In regard to variety in smile characteristic of different races, it is recommended to repeat this study in different Iranian population to determine more precisely the smile indices in Iranian with different age and personalities.

Introduction: 20-30% of adult population has experiences of temporomandibular joint (TMJ) disorders. Primary step for reduction of pain and joint dysfunction is nonsurgical treatments like Intra-articular injection of glucocorticosteroid. The aim of this investigation was to determine optimal dose of triamcinolone injection in treatment of arthritis in order to control its side effects.Methods and Materials: In this experimental animal study, after the sedation of 25 rats, experimental chronic inflammation induced by injection of Complete Freund's Adjuvant (CFA) in left TMJ of all 5 groups. After 7 days, injection of Triamcinolone acetonide performed differently in five groups: Group A. 0.1 mg/kg; Group B. 0.2 mg/kg; Group C. 0.5 mg/kg; Group D. 1 mg/kg; and group E. only equivalent volume of normal saline. After 10 days, rats were sacrificed and according to modified Gynther system, three factors of inflammatory cells infiltration, vascularity and number of synovial cell layers were evaluated and got scored.Results: All the groups with injection of Triamcinolone acetonide showed lower scores but only differences in vascularity and number of synovial cells in group B were statistically significant and in addition group B showed more predictable results than other groups in every three factors.Conclusion: We suggest that the best dose of intra-articular injection of Triamcinolone acetonide in rat TMJ is 0.2 mg/kg which caused the most reasonable therapeutic results. So evaluating the optimal dose for human joint leads to achieve the best results with the least side effects is recommended.

Introduction: Mandibular fractures depend on many factors like muscle traction, force direction, etc. Traffic accident and fall from height are the most common reason for maudibular fractures. The aim of this study was to determine type and site of mandibular fracture and its relation to etiology of fractures.Methods and Materials: This cross-sectional study was done in 358 patients with mandibular fractures (maxillofacial clinic, Shariati hospital, 2002- 2007). For each patient a special form was filled. The information's of this form were consisted: gender, age, time of accident, and location of fracture (and additional fracture).Results: From 358 patients with mandibular fractures, 192 were with complex fracture, 124 with simple fractures, and 42 accompanied with other fractures. Two hundred and ninety two (82.96%) were male and 61 (17.04%) were female. The most common type of fracture was body fracture and less common type was coronoid fracture.Conclusion: Car accident is the major reason of fractures and the most fractures happened in summer (especially in September). Controlling of drivers and license examination can improve and decrease the rate of mandibular fractures; also using the cascade helmet by motorcycle drivers is very important.

Introduction: Bone turn over in females is influenced by steroid hormones such as progesterone. The aim of the present study was to evaluate the effects of Progesterone on experimental tooth movement in rabbits.Material and Methods: Twenty four pre-pubertal female albino rabbits were randomly assigned into three equal groups. In the first group (LTG), rabbits received daily injection of 5 mg intramuscular progesterone for 9 weeks. In the second group (STG), rabbits received the same injections for the last 3 weeks of the experiment and in the third or control group (CG), the animals did not receive any progesterone. At the end of the 6th week, in all groups, two brackets were bonded to the incisor teeth in order to apply 50 gr distal force to these teeth via a stainless steel springs. Measurements were conducted at the end of weeks 7, 8, and 9 to calculate the distance between the incisors. The ANOVA and Tukey tests were used to compare the three groups.Results: The results showed no significant difference between the three groups at the end of the 7th and 8th week, but at the end of the 9th week, the rate of tooth movement was significantly lower in the first group (long term progesterone application) compared to the other two groups (p value =0.001 and 0.044, respectively).Conclusion: It was concluded that long- term Progesterone administration reduced the rate of tooth movement in rabbits.

Casein Phosphopeptides (CPP-ACP) is a bioactive agent with the base of milk products, which have formed from two parts CPP and ACP.CPP produced from the milk protein casein and have a remarkable ability to stabilize calcium phosphate in solution and substantially increase the level of calcium phosphate in dental plaque. CPP-ACP buffers the free calcium and phosphate ion activities, thereby helps to maintain a state of super saturation with respect to tooth enamel depressing demineralization and enhancing remineralization. The free ca-p ions move out of the CPP, enter the enamel rods and reform onto apatite crystals.Laboratory, animal and human studies have shown that CPP-ACP exhibit cariogenic activity, treatment of white spot lesions, hypo mineralized enamel, mild fluorosis, tooth sensitivity, erosion, and prevent plaque accumulation around brackets and other orthodontic appliances. This agent facilitates the normal post-eruptive maturation process is derived from cow's milk and is ideal for protecting deciduous teeth at a time when oral care is difficult.This product is fluoride free and is especially useful for under 2's where toxicological issues mean normal or high strength fluoride products are contraindicated; it is safe to swallow. This agent have commercial potential as an additive to foods, soft drinks, chewing gum as well as to toothpastes and mouthwashes for the control of dental caries.This article reviews the mechanism of action and therapeutic effects of CPP-ACP.

Introdution: Cleido cranial Dysplasia (CCD) is a rare autosomal dominant disorder affecting skull and clavicle and may be accompanied by some other skeletal abnormalities. Additionally, delayed tooth development associated with presence of supernumerary teeth has been reported. It is an uncommon disorder with the prevalence being 0.5% per 100'000 live births.Case report: The patient was a 19-year old boy referred to the Department of Oral Medicine of Isfahan Dental College. His chief complaint was an unknown pain in the left side of Maxilla. His intraoral examination revealed presence of deciduous teeth and crowding, missing in permanent teeth. Upon general examination, it was found that he had an abnormal clavicle with hypertelorism and patent anterior fontanel. Panoramic radiography revealed multiple completely impacted supernumerary teeth.Conclusion: Clediocranial dyplasia is a rare skeletal disorder. However, its clinical and radiological manifestations are characteristic. Although this disorder is benign, it must be remembered that abnormal dentition may result in dental caries. For eruption of impacted teeth, especially in young patients, surgical exposure is preferred. Orthodontic occlusal movement must be done for restoring the compatible with normal dental.