Journal of Isfahan Dental School
Year:2008 | Volume:4 | Issue:1|Papers Count:10

Introduction: There are controversies about the clinical efficiency of bonded amalgam restprations. The aim of this clinical study was comparison of fracture resistance, marginal adaptation and recurrent caries in endodontically-treated premolar teeth.Methods and Materials: Thirty five patients with endodontically treated upper first or second premolars were selected and divided into three groups. Copalite varnish in group A, Amalgam bond plus in group B and Scotchbond Multi Purpose in group C were applied as a sealer. The teeth in all three groups were restored with intracanal pin and amalgam in combination with lingual cusp coverage. After 1 year, fracture resistance, marginal adaptation and secondary caries were evaluated. Fischer's exact test was used for statistical analysis (& = 0.05).Results: There was no significant difference among groups with respect to fracture resistance (p value = 0.3). Significant differences in marginal adaptation existed between the three groups (p value = 0.01). No recurrent caries were found in clinical and radiographic evaluation of restored teeth.Conclusion: In one-year clinical period, using Amalgam bond Plus or Scotchbond Multi Purpose as dentine bondings to bond complex amalgam restorations in endodontically treated premolar teeth, there was no increase in fracture resistance of restorations and teeth and this treatment had no effect on prevention of recurrent caries, but resulted in significant improvement in marginal adaptation.

Introduction: Although distraction osteogenesis is a surprising modality in treatment of many of deformities in craniofacial region, but often tolerance of distractor devices is hard and problematic for many of patients. If low level lasers can increase rate of ossification, cause shortening of treatment duration, and cause lessening of problems of patients. Therefore, purpose of this study was determination of effectiveness of low level laser in acceleration of new bone formation and consequently shortening of treatment period and decrease of problems of distractor device.Materials and Method: In this study, after corticotomy, distractor devices were placed in mandibular body of 18 white zelanian rabbits and after 5 days, were activated at a rate of 1mm/day for 10 days. 9 rabbits were exposed to 7 doses of GaAs laser with power of 200 μw every other day and other 9 rabbits received no laser. Then, the rabbits were periodically sacrificed in the 10th, 20th and 40th days of consolidation period and obtained samples were studied by scanning electron microscopy and light microscopy and then analyzed by Mann-Whitney method (0.05).Results: In SEM and histological examinations, the amount and orientation of fibroblasts and fibrous tissue in the 10th day was greater in laser group than in control group. In the 20th day, in addition to fibrous tissue, the amount of woven bone was greater in laser group than that in control group but the degree of their difference wasn't significant and really was smaller as compared with the 10th day. In the 40th days in each of two groups of laser and control, woven and lamellar bone were seen but no significant difference of new bone formation was found in the laser group as compared with control group. It appears that laser radiation in initial stages of distraction is more effective than end stages.Conclusion: Probably PH changes in cell oxidation and reduction (Redox regulation) is an etiologic factor in incidence of this process; as though in initial stages that PH of tissue is in reduction limit because of trauma, radiation is more effective than late stages that PH of tissue is more stable. For the best result, it is necessary extensive researches about distraction protocol and laser radiation.

Introduction: The personnel of dental laboratories are at risk of infectious diseases transmitted from dental prostheses and impressions that have not been properly disinfected. These materials often carry microorganisms that may cause cross infection from patients to dental laboratory personal. The aim of this study was to investigate the situation of infection control among dental laboratories in Kerman.Methods and Materials: The present research was a cross sectional and descriptive-analytical investigation. Data were collected from 38 dental laboratories by an author developed questionnaire. The questionnaire asked respondents for demographic data (age, gender and education) and to answer some questions about their knowledge and practice of infection control and measures including use of gloves, protective eyeglasses, mask and hepatitis B virus vaccination. The gathered data analyzed with X2, fisher, and t-test using SPSS13.5 statistical software (a=0.05).Results: Among all of 103 respondents, 85 were male (82.5 percent) and 18 were female (17.5 percent). The most popular chemical materials used for disinfection were household bleach, glutaraldehyde, and alcohol. The results showed that 14 percent of technicians in laboratories wore gloves, and 7.7 percent regularly wore eyeglasses. Besides, 54 technicians (52.4 percent) had received HBV vaccination. Conclusion: The results of this study showed a lack of appropriate communication between dentists, and dental laboratory personnel in regards to disinfection of impressions and prostheses. Also, infection control in Kerman laboratories was found unsuitable.

Introduction: In patients requesting to bleach their teeth, bleaching treatment might affect microleakage of present restorations. Technique and concentrations of applied bleaching and bonding agents are some effective factors on microleakage of composite restorations. The aim of this study was to evaluate the effect of bleaching method on microleakage of resin composite restorations.Methods and Materials: 48 extracted carries free human premolars were selected and randomely divided into 4 groups. Class V cavities were prepared on buccal and lingual surfaces, with gingival margins located 1mm below CEJ. In group one Cleatfil, SE- bond and Single bond applied on buccal and lingual surfaces respectively, and cavities restored by Z 250 resin composite. In group two, the cavities were restored as in group one and then were kept in distilled water for a period of one month. In group three, all the stages resembled group two and home bleaching regimen was used. In group four, all the stages resembled group two, but samples subjected to in office bleaching regimen. All the samples were thermocycled and examined for microleakage. Data analyzed using Wilcoxon, Kkruskal-wallis and Man-Whitney U tests (a = 0.05).Results: Single bond compared to SE- bond provided the best post bleaching results regarding microleakage. The amount of microleakage was higher in office bleach technique in both margins.Discussion: Single bond showed the best results regarding post bleaching microleakage. Bleaching had a negative effect on microleakage that was higher in office technique.

Introduction: This study evaluated the effects of eugenol -free temporary cement remnants on the retentive strength of casting crowns luted via zinc phosphate and resin cement (Maxcem) to the tooth structure.Material and methods: 40 extracted human molars ware randomly divided into 2 groups. Each group was then divided into 2 subgroups and the teeth were paired so that the size of each tooth in each subgroup was the same as a tooth in the other subgroups. 40 standardized Ni-cr complete crowns were made on teeth prepared with a milling machine using conventional laboratory techniques. For each adhesive system, in one subgroups a provisional restoration was cemented using an eugenol -free temporary cement. Temporary crown was remained on the tooth structure for an hour and then extracted and cement remnant was removed by an excavator. Then the casing crowns were adhesively luted via zinc phosphate, adhesive resin (Maxcem) to prepared teeth. After 24h storage in distilled water, Retention was evaluated by measuring the tensile force required to dislodge the crowns from tooth preparations with a universal testing machine after thermo cycling (1500 cycles between 5c and 55c with 1- minute dwell times). The data were analyzed by means of paired T-test and wilcoxon test in SPSS software version 11.5.Results: The analysis showed the mean retentive strength for 2 subgroups with and without prior use of temporary cement in the maxcem group was 176 ± 55 and 274 ± 169 N, there was not a significant difference between the 2 subgroups. (p value = 0.174). And the mean retentive strength for 2 subgroups with and without prior use of temporary cement in the zincphosphate group was 257 ± 125 and 238 ± 135 N, there was not significant difference between the 2 subgroups (p value = 0.782).Discussion: The use of an eugenol -free temporary cement does not alter the retentive strength of casting restorations lutted to prepared teeth using the tested adhesive system, when temporary cements are removed properly

Introduction: The purpose of orthognathic surgery is to correct facial deformity and dental malocclusion and to obtain normal orofacial function. However, there are controversies of whether orthognathic surgery might have any negative influence on temporomandibular joint. The purpose of this study was to evaluate the influence of orthognathic surgery on articular disc position and temporomandibular joint symptoms of skeletal CI II patients by means of Magnetic Resonance Imaging.Materials and Methods: Fifteen patients (10 women and 5 men) with skeletal CI II malocclusion, aged 19-32 years (mean 23 years), from the Isfahan Department of Maxillofacial surgery were studied. All received lefort I & bilateral sagittal split osteotomy (BSSO) and all patients received pre- and post surgical orthodontic treatment, Magnetic Resonance Imaging was performed 1 day preoperatively and 3 month post operatively. Statistical analysis of the positional change of the disk was done by Wilcoxon rank sum test.Results: The change of articular disc position after mandibular advancement surgery by means of sagittal split ramus osteotomy was not statistically significant, but it tended to be positioned anteriorly.Conclusion: It can be suggested that orthognathic surgery dose not significantly change the position of the articular disc.

Introduction: With due attention to great application of irreversible hydrocolloid impression material in treatment dentistry and importance accuracy of impression in final result of treatment was necessary to study the all of effect factors on the accuracy impression. So this study was done for comparison of surface detail reproduction some of the kinds of irreversible hydrocolloid.Materials and Methods: In this laboratorial experimental study, was used the recommended laboratoril model of the standard (Iran) and research organization, with the registration number 2787. The form of this model was a stainless steel slotted block in 20, 50 and 75 sizes. The impression materials that used were Super Iralgin, Iralgin and Bayer irreversible hydrocolloid. For each materials was take 20 impression in the same conditions and was poured with type III gypsum and totally 60 cast models was earned. These models were observed with steriomicroscope randomly and each of the identical lines 20, 50 and 75 were allowed with a specific score. For evaluation of the results was used statistic analysis of Mann-Whitney Test and Kruskal Walli's (a = 0.05).Results: In registration of 20-line, 20 samples of Super Iralgin had sore 3, 19 samples of Regular Iralgin and Alginoplast had score3 and 1 sample score 4. The difference among these 3 groups was not significant (p value = 0.601). In registration of 50-line, 15 samples of Super Iralgin had score 2 and 5 samples had score 3, 7 samples of Alginoplast, had score 2, 13 samples had score 3, 6 samples of in Regular Iralgin had score 2 and 14 samples had score 3.The difference among these 3 groups was significant (p value = 0.008). In registration of 75-line, 15 samples of Super Iralgin had score 1 and 5 samples had score 2, 7 samples of Aliginoplast score 1 and 13 samples had score 2, 6 samples of Regular Iralgin had score 1 and 14 samples had score 2. The difference among these 3 groups was significant (p value = 0.008).Conclusion: In registration each three lines, the super Iralgin was more precises than the other types and was an ideal impression material. In registration of 20-line, Regular Iralgin and Alginoplast were in the same level, but in registration two others lines, Alginoplast was more precise. It is better to advise to the factory necessary recommendations to improve the quality of the Regular Iralgin material.

Introduction: Occlusal plane orientation is an important part of organized occlusion. The ala-tragus plane is considered to be parallel to the occlusal plane while reconstructing occlusion. This study was aimed to determine the condition of parallelism of these two planes in Iranian.Methods and material: In this cross sectional study, 197 patients were examined. The angle between ala-tragus and occlusal plane was assessed by indexed fox plane and the position of Stensen's duct to adjacent molar in maxillary tooth and the position of the dorsal side of the tongue relative to posterior mandibular teeth were also examined by clinical examination. Then two planes were investigated by lateral cephalometry for 23 patients. Deep bite, long face, and with bruxism patients were identified to examine the probable effect of this position in them. The data was analyzed with t-test, Peirson and X2 tests (a=0.05).Results: The ala-tragus line had the tendency to be paralleled with posterior occlusal plane and the mean angle of two planes was 1.77o. In cephalometric measurement, the estimated mean of the angle was 2.96o. In the most of the cases, Dorsum of tongue was above the mandibular occlusal plan. In the half of the cases Stensen's duct was in the occlusal third of adjacent molar.Conclusion: The differences in the mean angles of clinical measurement and cephalometric measurement have been resulted from the differences in two methods. The results allow clinicians to parallel occlusal plan with the ala-tragus line to achieve a natural position for reconstruction of occlusal plan.