Vol 3, No 1 (2006)
Proceeding Abstracts
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Statement of problem: The bond strength of root canal sealers to gutta-percha seems to be an important property for maintaining the integrity of the apical seal which can result in reducing apical microleakage. Purpose: The purpose of the present study was to compare the tensile bond strengths of four types of root canal sealers to gutta–percha. This study measured the maximum forces needed to disengage the bond between gutta–percha and these sealers. Materials and Methods: in order to prepare the specimens, 40 blocks of unprepared gutta-percha (20 10 3mm) was used. Aluminum cylinders, 6 mm in diameter, were stabilized on the gutta–percha with small amounts of wax and were filled with one of the sealers. After setting each sealer, the drops of wax were removed and the tensile bond strengths of all the samples were measured using universal testing machine. Collected data were analyzed by ANOVA and Tukey tests. Results: The highest bond strength was observed in the Diaket. It was followed by AH26 and Apexit. Dorifill had the least bond strength between the four groups. The tensile bond strength of Diaket and AH26 to gutta-percha were significantly higher than Dorifill and Apexit. Conclusion: Th According to the findings of the present study it can be concluded that the use of Diaket and AH26 for root canal therapy may produce better results in endodontic treatments.
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Statement of Problem: Pulpotomy is the most common pulp treatment of primary molars. Formocresol pulpotomy has enjoyed long-term clinical use and success, but concerns over its toxicity and mutagenicity have prompted research into other pulpotomy techniques. Purpose: The aim of the present study was to compare the relative success of formocresol, ferric sulfate and MTA pulpotomy methods in primary molars, using clinical and radiographic examinations. Materials and Methods: 135 second primary molars requiring pulpotomy treatment were selected from children between 3 and 6 years of age. They were randomly assigned to three groups according to the pulpal therapy technique: pulpotomy with formocresol, ferric sulfate, and MTA. All pulpotomized teeth were restored with amalgam. The subjects selected for clinical and radiographic evaluations were monitored periodically for 3 and 12 months. Results: The clinical success rate of the MTA group was 82.1% after one year which was significantly less than the 100% observed in the other groups (P= 0.005). The highest and lowest radiographic success rates after one year, were encountered in the formocresol (92.5%) and MTA (69.2%) groups respectively, which showed a significant difference (P=0.01). The success rate of the ferric sulfate group was 80.50%. Conclusion: MTA is not recommended as a pulpotomy medicament in primary teeth, but ferric sulfate may be acceptable as an alternative to formocresol.
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Statement of problem: Condylar hyperplasia of the mandible is a self limiting abnormality which can cause facial asymmetry, temporomandibular joint (TMJ) dysfunction and esthetic problems. Treatment planning is based on the results of isotope scanning, clinical findings and patient age. Single photon emission tomography (SPECT) is considered to be a sensitive method in the calculation of condylar uptake differences. Purpose: The aim of this study was to determine the growth activity occurring in the mandibular condyles, and to devise an index of side-to-side differences in condylar activity in different individuals. Material and Methods: 38 patients, with an age range of 13 to 34 years, undergoing skeletal scintigraphy for a variety of conditions, were chosen for this study. 25 mci TC-99 was injected to all subjects in order to assess the difference between right (Rt) and left (Lt) condylar uptake percentage and to calculate the Lt to Rt condylar uptake ratio. The normal index was determined. Results: The maximum amount of difference between the uptake of Rt and Lt condyles was 6.2 percent (Lt side and Rt side were 53.1 % and 46.9 %, respectively) in the male patients and 5.7 percent in the female patients (Lt side and Rt side were 52.85 % and 47.15 %, respectively). The condylar activity difference and ratio of Lt to Rt condylar uptakes did not show a significant difference between the male and female groups. Conclusion: The difference between the growth activity of RT and LT normal TMJs was less than 6.2 percent.
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Statement of problem: The gonial angle plays an important role in ensuring a harmonious facial profile. Changes in this angle especially after surgery may be an aesthetic concern for both the patient and the surgeon. Purpose: The aim of the present study was to evaluate gonial angle changes after mandiblular setback with the BSSRO technique and to measure postsurgical relapse two years after surgery. Material and Methods: Nineteen patients with mandibular prognathism referred to Taleghani Hospital were selected from 1999 to 2001. All subjects underwent surgery for mandibular setback with the BSSRO technique and IMF for 8 weeks. Lateral cephalograms were taken before surgery, immediately postoperatively and 2–4 years after surgery. The setback rate (relapse) and gonial angle changes were evaluated during these periods. Pearson correlation and student t tests were used for statistical analysis. Results: The mean gonial angle decreased in all subjects, it was 135.05° (6.41) before and 128.73° (5.43) after surgery. The mean reduction of the gonial angle was 6.32° (4.08) immediately after surgery while it showed 4.89° (3.44) decrease after 2 years follow-up at the final examination. The mean of setback was 6.27 (2.28) mm which decreased to 5.82 (1.82) mm after follow-up. A significant correlation was observed between the amount of setback and reduction of the gonial angle (P=0.0001) but no correlation was found between sex and gonial angle changes or mandibular setback relapse. Conclusion: Surgical correction of mandibular prognatism using BSSRO and IMF can cause a decrease in the gonial angle. This increase in the setback, may reduce the gonial angle and have correlation to the amount of relapse.
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Statement of Problem: Bracket de-bonding during initial orthodontic archwire placement immediately after bracket set up or following re-bonding a single bracket can be a clinical concern. Purpose: The aim of this in vitro study was to assess the effect of time on the shear bond strength of a no-mix orthodontic composite adhesive. Materials and Methods: Seventy freshly extracted human upper first premolars were collected and stored in normal saline solution. The teeth were cleaned, polished, and randomly separated into 7 groups of 10. First premolar mesh-backed standard edgewise brackets were bonded to all specimens using a no-mix orthodontic composite adhesive. In the first 6 groups, the brackets were de-bonded 2, 5, 10, 15, 30 and 60 minutes after the primary setting time and the shear bond strengths were determined with the Universal testing machine. The teeth in group 7 were stored in 100% humidity at 37oC for 24 hours before de-bonding. Data were statistically analyzed with one-way ANOVA and the Duncan multiple range analyses via SPSS software. Results: The minimum shear bond strength of 14.03 MPa was observed in group 1. A statistically significant difference was found between the shear bond strength of group 1 and the other groups (P<0.05). The shear bond strength increased significantly with time up to the first 5 minutes after bonding, but did not change afterwards. Conclusion: The bracket and composite adhesive used in this study demonstrated initial bond strengths of sufficient magnitude to withstand the immediate application of orthodontic forces, even 2 minutes after the primary setting time. Therefore, the operator should not be concerned with bracket de-bonding due to primary arch wire placement during the first minutes after bracket set up or following re-bonding a single bracket.
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Statement of Problem: The aggressive nature and high recurrence rate of Odontogenic Keratocysts (OKCs) may be due to unknown factors inherent in the epithelium or because of enzymatic activity in the fibrous wall. Bcl-2 protein is characterized by its ability to inhibit apoptosis. Purpose: The aim of the present study was to analyze the expression of bcl-2 protein in OKCs and to compare it with the more common radicular and dentigerous cysts. The possible relationship between inflammation and bcl-2 expression was also investigated. Materials and Methods: Formalin fixed paraffin-embedded tissue sections of 20 OKCs, 20 radicular and 20 dentigerous cysts were immunohistochemically analyzed for immunoreactivity of the bcl-2 protein. Results: Bcl-2 expression was observed in 19 OKCs (95%), one radicular cyst (5%) and one dentigerous cyst (5%). There was no statistically significant relationship between inflammation and the number of bcl-2 positive cells. Immunoreactivity was mainly noted in the basal or basal/supra basal layers. Conclusion: Considering the fact that bcl-2 over expression may lead to increased survival of epithelial cells, present study may demonstrate a possible relationship between the aggressive nature of OKC and the intrinsic growth potential of its lining epithelium. Furthermore a basal/supra basal distribution of bcl-2 positive cells was seen in some odontogenic keratocysts which may have a significant impact on the behavior of this cyst.
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Statement of problem: One of the main goals in periodontal therapy is the correction of recession defects; therefore the efficacy and predictability of the various techniques are important considerations for clinicians. Purpose: The purpose of this pilot study was to compare the outcomes of gingival recession therapy using the semilunar coronally repositioned flap (SCRF) alone and in conjunction with a tissue adhesive (EPIGLU). Materials and Methods: Thirty-two anterior and premolar teeth with class I and II Miller gingival recessions were selected and randomly divided into two groups. The test group received SCRF followed by EPIGLU application and the control group was managed with SCRF alone. Clinical parameters measured at baseline and 7, 14, 30 and 90 days after surgery included vertical and horizontal recession depths, width of keratinized tissue, probing depth, clinical attachment level, percentage of root coverage, and sensitivity of root surface to air flow. Results: The recession depths decreased significantly in both groups (P<0.05). Three months after surgery, the mean root coverage in the test and control groups was 1.86mm (77.96%) and 1.57mm (69.1%), respectively. The width of keratinized tissue along with all the other tested parameters except for probing depth, increased significantly in both groups, during the study period (p<0.05). Sensitivity of root surface to air flow was not observed in either group. Conclusion: The SCRF alone or with EPIGLU is an effective procedure for root coverage in anterior and premolar teeth. The addition of EPIGLU improves the amount of root coverage, especially in relatively shallow defects.
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A new fixed-partial denture design using laminates is described for the replacement of a missing anterior tooth. In this article advantages, disadvantages, indications and contraindications of the new design have been discussed. This method is best suited for cases with missing incisors and esthetically compromised abutment teeth.
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Sleep apnea, and particularly obstructive sleep apnea, is a common disorder that is characterized by a repetitive, partial or complete cessation of air flow, associated with oxyhemoglobin desaturation and an increased effort to breath. In recent years, orthodontists have been interested and involved in the management of this disorder since it has been shown that oral appliance therapy can be an effective treatment approach for obstructive sleep apnea (OSA). The purpose of this article is to present a review of OSA by describing this disorder, its diagnosis, currently available treatment modalities and, in particular, the role of oral appliance therapy in its treatment.
