Avicenna Journal of Clinical Medicine
Year:2003 | Volume:10 | Issue:SUPPLEMENT 3|Papers Count:12

Evaluation of dental arch changes after rapid palatal expansion by bonded palatal ‎expander. 10 patients (5 boys & 5 girls) with uni or bilateral crossbite in ‎mixed dentition period were selected and records including, both arches casts, ‎maxillary occlusal radiography, intra & extra- oral photographies obtained rapid ‎palatal expansion applied by acrylic bonded palatal appliance during 14 days (about 7 ‎mm expansion was done). After a period of three months retention, appliance replaced ‎by removable one and the same above records obtained. The average chages of arch ‎width in the first permanent molar & deciduous first molar and coanine area of both ‎arches were measured. Paired t-test was used for analysis. The minimum changes in ‎both arches were in deciduous canine area (3.7 mm expansion in maxilla & 0.5 mm in ‎mandible). The maximum changes in maxilla was 6.77 mm in deciduous first molar ‎area, in mandible was 0.86 mm in permanent molar area. In spite of spondtaneous ‎expansion in lower dental arch following maxillary expansion (correlation coefficient ‎‎0.82) we must expand lower arch independently in clinical use. Because the amount ‎of spontaneous expansion isn't significant clinically‏.‏

In this study wound healing process in soft and hard tissues of the gingival area and ‎the Mandibular bone of rats whose ovary glands were removed bilaterally (as samples ‎which are similar to menopause period in human) was assessed histologically and ‎hisomorphoemtrically and results write compared with those of control group. For ‎performing this study, 20 rats were chosen and divided into two groups with ten rats ‎in each group. In one group of rats bilateral ovariectomy was applied and in another ‎group, simi operation was done except for ovariectomy (Sham operation). 5 months ‎after ovariectomy, a defect was created (Sham operation), 5 months after ‎ovariectomy, a defect was created in gingival area and mandibular bone of lower right ‎central incisor in 5 mm lower than gingival margin which was 5 mm deep with a ‎‎1.3mm diameter. In 1, 4, 7, 21 and 42 days after creation of the defect, biopsies were ‎taken from the defect area and histologic and histomorphometic studies were done. ‎Histological assessment sections consisted of clotting formation, degree and kind of ‎inflammation and granulation tissue and degree and nature of bone formation.Results ‎demonstrated that during the first days, the inflammation was more severe in the ‎control group rather than the study group, but gradually the inflammation process ‎became similar in both groups. The produced fibrous tissue in control group was also ‎more than the study group on the 7th day samples, producing of new bone was ‎obvious in the bone defect margins in both groups. On the 21st day, formation of ‎woven bone was observed in both groups. On the 42nd day, the produced bone in ‎both groups was lamellar, but histomorphometic studies showed that bone formation ‎in the control group was greater than the study group. Few studies through histologic ‎evaluation of wound healing process in soft and hard (bone) tissues after ovariectomy ‎operation have been done. In this study wound healing process in soft tissue in ‎ovariectomized rats has been decelerated and the amount of new bone formation is ‎decreased‏.‏

All root canal treatment completed by first and, second clinical year undergraduates over a 12-month period were included in the study. The availability and readability of pretreatment, diagnostic length, try-in point and postoperative radiographs were noted for each case. All readable postoperative radiographs of primary treatments were examined for quality of the root filling, categorized as complete and incomplete. Thoes incomplete root fillings were furthermore classified by (mishaps occurring for them. The distance from the radiographic apex of the root to the apical extent of each root filling was measured to 0.1 mm precision. Undergraduates performed primary treatment on 679 teeth (1366 canals). A postoperative radiograph was available in 99% of cases. 243 teeth (36%) were obturated completely. 41% of root fillings ended more than 2mm from the radiographic apex and almost 19% of cases had root fillings though the radiographic apex.Overall, the technical quality of root canal treatment completed by undergraduate students was moderate. Undergraduates should be more careful in treating root canals. Plans should be made to revise both preclinical and clinical teaching of endodontology and to reaudit treatment in the future. A method of assessment is that to pay attention to quality rather than quantity.

Tissue conditioner impression materials are applied to impression side of removable prosthesis to heal abused tissue under them. Albeit it has been observed that most of these materials furnish a proper media for candida albicans growth, but most manufactures acclaim that the reverse effect would be taken place. Thisin vivostudy compares the effect of two kinds of tissue conditioner material on the oral candida growth in patients with maxillary complete denture. Soft-liner (GC Corporation, Japan) and Tc Acrosoft (Marlic Medical Industries Co. Iran) were investigated regards to yeast growth. These materials were applied in the maxillary complete dentures of 20 patients with consideration to predisposing factors. Samples were taken from palatal tissues before any treatment and after 15 days of tissue conditioner materials application. Colonies were counted. Samples from these colonies were cultured and smears were stained. A- mycological evaluation determined the species of candida. Fungi were grown on the palate of 10 patients regardless to the kind of tissue conditioner materials. In 7 patients the number of colonies diminished and left stable in 3 cases. The number of clonies intensified in 5 patients under Acrosoft, while this material diminished yeast growth in 4 patients. The number of colonies remained stable in 1 case. In other group yeas1 growth were decreased in 3 patients and remained stable in 2 persons and increased in 5 cases samples. 65%yeast colonies were candida albicans. 35%samples were diagnosed as other candida species. There was no difference between these two materials in respect to their effects on yeast growth from thy statistical point of view (P.value=0.07). Due to yeast growth in 10 patients (50%) case it is suggested to prescribe antimycotinic drugs during application of tissue conditioner materials in patients.

The goal of this study was to evaluate and compare the effects of using corticosteroids and rubber drain on postoperative complications of impacted third molar surgery.This clinical trial study was carried out on 22 patients with bilateral symmetrical impacted mandibular third molar. For surgical removal of impacted teeth in one side of these patients rubber drain (11 cases) or perioperative steroids (11cases) was used (study group). Impacted teeth in other side was removedroutinly without drug or drain usage (control group). In no drug group the mean of the mouth opening on the second and seventh postoperative day was 26.7 and 37.72mm and the mean of facial swe1ling (Tr-Com+Ca-Go) was 225 and 217 mm and the mean of pain severity was 2.36 and 0 respectively .In drug group the mean of the mouth opening on the second and seventh postoperative day was 31.3 and 40.6 mm and the mean of facial swelling (Tr-Com+Ca-Go) was 220 and 215.7 mm and the mean of pain severity was 1.5 and 0 respectively. In no drain group the mean of the mouth opening on the second and seventh postoperative day was 23.4 and 30 mm and the mean of facial swelling (Tr- Com+Ca-Go) was 220 and 213 mm and the mean of pain severity was 2.4 and 0 respectively. In drain group the mean of the mouth opening on the second and seventh postoperative day was 24.9 and 33.4 mm and the mean of facial swelling (Tr-Com+Ca-Go) was 217 and 212 mm and the mean of pain severity was 2 and 0 respectively. The results of this study showed that Perioperative corticosteroids is more effective than rubber drain in reducing postoperative pain &edema but their effects on trismus is similar.

This study was accomplished in order to evaluate the of composite basing technique (CB.T) on fracture resistance of the teeth restored with porcelain inlays (invitro). Forty sound human maxillary first premolars were divided into 4 groups. Each group included 10 teeth. samples prepared in the following manner: group 1 :prepared and restored without CB.T group 2:prepared but unrestored without C B.T group 3 :prepared and restored with CB.T group 4:prepared but unrestored with CB.T for all groups Instron universal machine were used under compressive load. 1- no significant difference were observed in fracture resistance and fracture mode between teeth that restored (group 1 &3). 2- no significant difference were seen in fracture resistance and fracture mode between unrestored teeth ( group 2&4 ). 3- significant difference were seen in fracture resistance between restored teeth (group 1&3)and prepared but untestored teeth (group 2&4).

The purpose of this study, is the evaluation of stress distribution around bone of implant due to influence of the cantilever buccolingually variable widths of superstructure in implant therapies (ITI) using the Finite Element Method. For this research, three different conditions: with cantilever 3.5 , 5 , 7mm associated with one 12mm fixture on the anterior of the maxilla, designed by ANSYS5.4 Software. Then, the differences between principal nonnal and VonMises stresses due to three oblique, axial and lateral forces each 50 and 70Ne"lon were analyzed by two and three dimensional finite element analysis. The results indicated that stress concentration in three conditions due to the three forces, were mainly. at the crest of cortical bone The maximum vonmises stress in bone-implant interface in the first. Second and third condition due to oblique force (50 New 1 on) were. 1 8.1 Mpa. 2] Mpa. 24.6 Mpa respectively. w11 ereas the maximum vonmises stress in first, second and third condition due to oblique force (7() Newton} were 25.3 Mpa ,27.7 Mpa, 34.5 Mpa respectively. The amount of the stress Obtained due to axial forces were much less than the stress related to oblique forces. Whereas toe stress obtained due to lateral forces was more than the stress related to oblique forces. Since the stress more than 29 Mpa in bone-implant intcrtace produce fatigue fracture and destruction of osseointegration ,the thiru condition (7mm cantilevered) dye to oblique force (70 Newton) and also the second and third condition due to lateral force (70 Newton) cause rrohlcms and it will lead to the failure of treatment.

The important base of orthodontic treatment is correct diagnosis. One of diagnostic tools is comparing craniofacial skeleton in laferal cephalogram of patient with the normal ones. There are differences in normal standards between different races .The present study was carried out with the aim of determining and assessing the cephalometric standards of girls with the age of 17to 20 years old in Hamadan.Among 1305 girls of preuniversity centers, 25 persons were selected based on index of IOTN and normal occlusal standards. Lateral cephalograms were obtained in Natural Head Position. 22 cephalometric variables (15 angles, 5 lines, 2 ratios) were determined & measured three times by an orthodontist. T student test was used for analysis. The length of anterior cranial base in our study (72.57±3.75) was significantly less than Michigan standards (76.9 ± 3.9, p≤0.0056) .There is a significant tendency to more straight profile in this evaluation (Npog- TH = 88.33 ± 4.65) in comparing with Cooke's study ( 80.8±3.1 , p≤0.001) .Also there was significantly less protrusion of mandibular incisors in our study ( L1- TH=120.05 ± 7.6) versus Cooke's standards(127.8 ± 6.3). Mandibular plan angle in present study (GoGn - TH =23.18 ± 5.55) had significantly more counter clockwise rotation versus Viazis rapports (27.5± 7, p< 0.001). It is important to consider the ethnic and racial variations in our ideal treatment plan. Majority of standards achieved from European whites therefore it seems there is necessary to design a broader investigation for assessing the cephalometric standards in our country.

Today dental radiography is one of the most important diagnostic tools in dentistry. The aim of this study was to evaluate the performance of radiation protection rules in dental centers and private clinics in Hamadan city in year 2001.Among 102 dental centers and private clinics only 29(28.5%) had x-ray machine. A questionnaire completed for these centers. Collected information analyzed with EPI6software.Result showed that 86.20% used paravan or leaded room, 55.17% using position and distance roll. 37.93% used lead apron, 13.79%used thyroid collar, 10.37% used film holders. All the centers used E speed film. 62.06% used cylindrical short cone, 6.89%used cylindrical long cone, 31.03%used closed-end cone no unit had rectangular collimator. For exposure condition 58.62% used proper time of exposure due to patient age, 62.06% used proper time of exposure for anatomical region and 51.72% used proper time of exposure for film type. In 51.72% of the cases trained operator doing radiography procedure, only 44.82% had film badge, 24.13% had standard condition for processing of the radiographs.Results of this investigation implies that general performance of radiation protection in dental clinics was not satisfactory.