Vol 5, No 4 (2008)
Proceeding Abstracts
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Objective: The aim of the present study was to investigate the level of gingival over-growth (GO) in patients with kidney transplant.
Materials and Methods: The target group of the study was the patients recently received kidney transplant and cyclosporine-A therapy. By a systematic case selection method, a total of 131 cases were included in the study, of whom 80 (61.6%) patients were male. The data was collected through interview with the patients as well as clinical assessment of their dental and periodontal indices. Gingival enlargement was recorded in terms of a 4-point scale from absence of enlargement to sever enlargement. Gilmore and Glickman plaque index was also recorded. Chi-square test served for statistical analysis.
Results: The mean dose of the drug received was 203 mg (SD=75), with 191 mg (SD=71)in females and 209 mg (SD=77) in male individuals. GO was found in one-third of the pa-tients receiving CSA. Incidence of GO was found to be roughly equal in upper and lower jaw with no significant difference (P>0.05). Gingival enlargement was also found to be more prominent at the anterior region. Difference between two age groups was statistically significant (P<0.05). No Statistically significant difference was found between groups tak-ing different doses of the drug.
Conclusion: Gingival overgrowth among the patients receiving kidney transplant and CSA therapy seems to vary according to such factors as age and gender, but not the dose of the drug taken.
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Objective: Osteopontin (OPN) has been proposed to play a role in bone resorption. With regard to bone and cementum/dentin structural and histological similarities, it was hy-pothesized that expression of this gene might be increased in resorptive lacunae during orthodontic tooth movement.
Materials and Methods: Fixed Nickel-Titanium closed coil springs (Dentaurum®) capa-ble of delivering approximately 60 gf were applied for mesial movement of maxillary left first molars in 26 male 8-week-old Wistar rats. The right maxillary molar served as inter-nal control for each subject. After 21 days, the rats were sacrificed. Tissues from 13 rats were examined by histomorphometric analysis and the scratched material from resorptive lacunae on mesial sides of the roots was used for extracting messenger ribonucleic acid (mRNA) in RT-PCR reactions. T-test and Wilcoxon signed-rank test served for statistical analyses.
Results: Histomorphometric analysis of histologic sections revealed an increased resorbed area in test group compared to control animals (P<0.001). The integrity of mRNA con-firmed by RT-PCR for housekeeping gene glyceraldehyde 3-phosphate dehydrogenase (GAPDH). Densitometric analysis of OPN mRNA on electrophoresis gel showed an in-crease in background levels of OPN in resorptive lacunae of test group (P<0.001).
Conclusion: Data indicates that in the controlled environment of this study, an increase in OPN expression is associated with root resorption induced by orthodontic tooth move-ment.
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Objective: Evaluating the effect of dentin conditioning with EDTA on microleakage of composite resin restorations, using two etch and rinse and two self-etch adhesives.
Materials and Methods: One hundred and sixty extracted molars received class V cavity preparations right under the CEJ and were randomly divided into eight groups of 20, usingfour different adhesive systems. These adhesives included Adper Scotchbond Multi-purpose (SBMP), Adper Single Bond (SB), Clearfil SE Bond (CSEB), and Adper Prompt L-Pop (PLP). In the SBMP and SB experimental groups, EDTA was applied instead of phosphoric acid. In the CSEB and PLP experimental groups, EDTA conditioning was added to the bonding process. After thermocycling, the amount of dye penetration was evaluated using stereomicroscope. The data were analyzed using the Kruskal-Wallis and Dunn tests.
Results: Two etch and rinse adhesives (SBMP, SB) showed a significantly lower micro-leakage than the two self-etch adhesives, CSEB and PLP, (P<0.05). No significant differ-ence was observed among the experimental groups. PLP and CSEB showed significantly less microleakage using EDTA conditioning (P<0.05). There was no significant difference for SBMP and SB when applying either phosphoric acid or EDTA.
Conclusion: In the cases of SBMP and SB, EDTA conditioning is as effective as phos-phoric acid in preventing microleakage. In cases of CSEB and PLP, EDTA conditioning can significantly improve the sealing ability.
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Objective: The aim of this study was to evaluate the efficacy of enamel bonding agents on pit and fissure sealant retention in a well-isolated situation.
Materials and Methods: Thirty-two patients (6-9 years old, all males) with four fully erupted permanent first molars were selected. Their occlusal, buccal, and lingual fissures were sealed according to a split-mouth design using concise light curing white sealant (3M) for the control group and Heliobond (Vivadent) plus sealant for the study group. The retention of sealants was carefully inspected after one year and the data were analyzed by chi-square test.
Results: The percentages of complete retention in the study and control groups were 73.2, and 71.4, respectively. Chi-square test revealed no significant difference between these groups (P>0.05)
Conclusion: In a dry and isolated situation, application of enamel bonding agent has no significant effect on fissure sealant retention.
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Objective: The aim of this study was to investigate the effect of phosphoric acid re-etching of an enamel surface treated via a one-bottle adhesive system on shear bond strength between resin composite and the enamelsurface in different stages of adhesive application.
Materials and Methods: Extracted intact premolars (n=84) were divided into sevengroups (n=12). In the control group 1, the adhesive i-Bond was used according to the manufacturer's instructions, with nocontamination. In groups 2 to 4, the conditioned and saliva, contaminated enamel was blot dried only, rinsed,and blot dried, rinsed blot dried and re-etched, respectively. In groups 5, 6and 7 cured adhesive was contaminated with saliva and then rinsed and blot-dried, blot dried only and rinsed, blot-dried and re-etched respectively. In groups 3, 4, 6 and 7 the adhesive was reapplied. Afterward, Z100 compos-ite cylinders were bonded to the enamel surfaces. The samples were thermocycled (5°C and 55°C, 30 s, dwelling time: 10 s, 500 cycles). Finally, the samples were sheared using Dartec testing machine and shear bond strength data were subjected to one-way ANOVA analysis and Tukey's HSD test.
Results: There were statistically significant differences among groups 1 and 5-7. The samples in groups 1 and 4 demonstrated higher bond strengths than those in the other groups.
Conclusion: Using phosphoric acid etching may be effective, only where contamination occurs prior to curing of the adhesive. After curing of the adhesive, none of the methods in this study would be preferred.
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Objective: Nowadays light-cured composites are used widely by orthodontists to bond brackets. As these composites require 20-40 seconds time per tooth to be light cured, more chair-time in needed compared to self-cured composites. In recent years, the argon laser and plasma arc lights have been introduced in dentistry to reduce this curing time. The purpose of this study was to compare bond strength of brackets bonded with the argon la-ser and plasma arc light with those bonded with the conventional halogen light.
Materials and Methods: Fifty-one intact human premolars were randomly divided into three groups of 17 teeth each. Stainless steel twin premolar brackets (018- in Dyna lock, 3M Unitek) were bonded to the teeth using one of these curing devices in each group: the halogen unit (Coltolux 75, Switzerland), the argon laser unit (Bo-5, Iran ), and the plasma arc unit (Remecure 15, Belgium). The orthodontic adhesive was the same in the three groups (Transbond XT, 3M Unitek). After thermal cycling, the diametral tensilebond strength of specimens was measured using a debonding plier in a Zwick Universal Testing machine (Z/100, Germany).
Results: The mean bond strengths was 17.344 MPa (SD=4.567) for halogen 19.172 MPa(SD=6.328) for laser and 19.322 MPa (SD=4.036) for plasma arc groups. No statistically significant difference existed in the mean bond strengths among three groups.
Conclusion: Argon laser lights, significantly reducing the curing time of orthodonticbrackets without affecting bond strength, have the potential to be considered as advanta-geous alternatives to conventional halogen light.
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Objective: Optimal dentin bonding is not always obtained in clinical practice due to func-tional forces. These forces may provide stresses throughout the tooth and restorative sys-tem, which in turn may affect the adhesive bond. This experimental study evaluated the effect of load cycling on bond strength of self-etch systems.
Materials and Methods: One third of the coronal portions of 48 intact human extractedupper premolars were removed. The teeth were equally divided into six groups. In groups Unloaded-Clear tri-S Bond (ULCB) and Loaded-Clear tri-S Bond (LCB), prepared dentin surfaces of each tooth were treated with Clearfil tri-S Bond (Kurary medical inc, Oka-yama, Japan), in groups Unloaded-I Bond (ULIB) and Loaded-I Bond (LIB) with I bond Heraeus Kulzer, GmbH,&Co KG, Germany), and in groups Unloaded-Xeno III (ULX) and Loaded-Xeno III (LX) with Xeno III dentin adhesives (Dentsply Detrey GmbH, Kon-stanz, Germany). Then, the teeth were restored with Filtek Supreme resin composite. After thermal cycling of the samples, Groups LCB, LIB and LX were submitted to mechanical loading (100,000 cycles, 60 N). Microtensile bond strength (MTBS) test was performed for all of groups. Two-way ANOVA and Tukey HSD tests served for statistical analysis.
Results: Results showed that groups ULCB and ULIB had significantly more bond strength than group ULX (P<0.05). For all the tree adhesive systems, the MTBS values in teeth subjected to load cycling was significantly lower than unloaded teeth (P<0.001).
Conclusion: Load cycling seems to decrease MTBSs of one-step adhesive systems to den-tin.
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Objective: Interceptive contacts in complete denture cause some side effects. To our knowledge, however, no comprehensive reports exist on the prevalence of interceptive contacts after complete denture placement. The aim of the present study was to investigate the prevalence of interceptive contacts in inserted complete dentures and its associated factors.
Materials and Methods: This cross sectional study was conducted on 52 patients receiv-ing complete denture treatment. Factors such as gender, ridge relationship and its extent, and occlusal scheme were recorded for each patient. Whether the clinical remounting had been done was also recorded. The status of interceptive contacts was determined extra-orally and qualitatively. Chi-square test served for statistical analysis. The results were considered highly significant at P<0.0001 and significant at P<0.05.
Results: Out of 52 patients, 15 (28.8%) showed interceptive contacts. No statistically sig-nificant association was found between interceptive contacts and gender, ridge relation-ship, the extent of residual ridge resorption, or occlusal scheme. Clinical remount had been performed only for one of the dentures with interceptive contacts. Highly significant rela-tionship existed between clinical remounting and absence of interceptive contacts (P<0.0001).
Conclusion: Within the limits of this study, interceptive contacts were noticeable. Clinical remounting seemed to play an important role in preventing interceptive contacts.
