Vol 3, No 4 (2006)
Proceeding Abstracts
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Statement of Problem: The replacement of missing teeth with implant-associated restorations has become a widely used treatment modality in recent years. The length of dental implants may be a critical factor in achieving and maintaining osseointegration. Purpose: The aim of this study was to evaluate the survival rate and bone loss of dental implants with different lengths Materials and Methods: A retrospective cohort study was performed on 60 ITI-system implants, evenly distributed into three groups including 8, 10 and 12 mm high implants in the posterior segments of both jaws. Demographic information, oral hygiene, cigarette smoking, implant length, duration of implant placement (at least 24 months), bleeding on probing index and pocket probing depth were recorded for all participants. Bone loss was calculated using pre- and post-operative panoramic radiographs. Results: The mean rate of bone loss was different among the three groups and were found to be 0.21 (0.45), 0.3 (0.41) and 0.43 (0.55) mm in the 8, 10, and 12 mm high implants, respectively. Neither mean bone loss nor bleeding on probing index showed significant differences with implant length. A significant correlation was found between implant length and pocket probing depth (P<0.0001). Conclusion: The results of this study suggest that both short (8 mm high) and long (10 or 12 mm high) implants may be used with nearly equal success rates in the posterior segments of the jaws.
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Statement of Problem: Various surgical procedures have been used to achieve root coverage and subepithelial connective tissue graft (SCTG) is identified as one of the most successful techniques. Recently, acellular dermal matrix allograft (ADMA) has been developed as a substitute for SCTG to avoid removing the palatal connective tissue. Purpose: The present study compared the clinical efficiency of ADMA and SCTG in the treatment of recession defects. Materials and Methods: This randomized controlled clinical study, consisted of nine patients with 32 Miller’s class I or II recession defects of ≥ 2 mm on the facial aspects of premolar teeth. Bleeding on Probing Index (BPI), Plaque Index (PI), Probing Depth (PD), Recession Depth (RD), Recession Width and Clinical Attachment Level (CAL) were measured at baseline and 6, 12 and 24 weeks post-surgery. Before operation, the samples were randomly allocated to ADMA (test) or SCTG (control) groups. Results: A statistically significant improvement was observed in RD, RW and CAL, but not in BPI, PI and PD. The mean values of changes in all clinical parameters from baseline to 24 weeks postsurgery were not significantly different between the two groups. There was no significant difference in the amount of mean root coverage between the ADMA (85.42%) and SCTG (69.05%) groups (P= 0.058). Conclusion: ADMA may be a useful substitute for SCTG in the treatment of shallow to moderate gingival recessions, if the financial aspect is not an issue for the patient.
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Statement of problem: Fracture strength of a denture base resin is of great concern, and many approaches have been used to strengthen acrylic resin dentures. Purpose: The aim of this study was to measure the transverse strength of a heat polymerized acrylic resin, after reinforcement with metal wire and two types of glass fibers. Materials and Methods: Forty rectangular specimens (65.0×10.0×3.3 mm) of a heat- cured acrylic resin were made according to ISO/FDI 1567. Group I (control group) consisted of 10 specimens with no reinforcement. Specimens in group II reinforced with sandblasted metal wires. Group III and IV strengthened with woven (Stick Net) and continuous unidirectional (Stick) fibers respectively. The specimens were polymerized according to manufacturer’s recommendation. The transverse strengths were assessed with a 3- point bending test at cross head speed of 5mm/min. One-way ANOVA was carried out to compare and detect any differences among groups (=0.05). Results: Mean transverse strength (SD) of unreinforced specimens was 85.44 (8.6) MPa. The transverse strength increased significantly to 97.97 (5.5) MPa, 109.69 (5.8) MPa, and 127.13 (6.4) MPa in Metal wires, Stick Net, and stick fibers groups, respectively. Conclusion: The transverse strength of heat-polymerized denture base resin was enhanced considerably by using metal wire and glass fibers reinforcements. However, the addition of unidirectional glass fibers was significantly more effective method to improve flexural strength of denture base acrylic resin.
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Statement of problem: Fixed orthodontic appliances can interfere with removing bacterial plaques from dental surfaces which can ultimately lead to white spot formation. Purpose: The aim of this study was to evaluate the quantity of white spots and areas of decalcification following fixed orthodontic treatment. Materials and Methods: A total of 100 patients undergoing or scheduled for fixed orthodontic treatment were divided into two groups. Group A consisted of fifty volunteers before the initiation of therapy and group B included fifty patients at the end of their treatment. In group A, the buccal surfaces of the first molars in each quadrant were examined for the presence of enamel decalcifications. After removing the orthodontic bands in group B, the buccal surfaces of the first molars in each quadrant were examined for white spots. Gender, oral hygiene level, plaque index, type of cement and duration of treatment were recorded for all patients. Binomial logistic regression, chi-square and Mann-Whitney U-tests were used for statistical analysis. Results: The number of white spots in group A was 28 (14%) which was significantly lower than group B with 83 (41.5%) decalcified lesions (P<0.01). Oral hygiene and duration of treatment had a significant effect on the occurrence of white spots (P<0.05). Conclusion: The results showed that patients with orthodontic bands are at higher risk for white spot formation and good oral hygiene demonstrates a protective effect on their reduction. Both professional and daily oral hygiene measures can decrease the cariogenicity of bacterial plaques in these patients.
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Statement of problem: Few longitudinal studies have evaluated the reproducibility of natural head position (NHP) with more than six months follow-up. Purpose: The present investigation was conducted to estimate the reproducibility of NHP in adult cases after three years. Materials and Methods: This descriptive study was performed on 27 volunteer dental students, 19-29 years of age. One radiograph and two photographs were taken in a NHP. The time interval between the two photographs was 4 to 10 minutes (short-term period) and a radiograph was taken approximately 2 years, 6 months after the first photograph. These were obtained by one operator and device in standing subjects. In order to evaluate NHP reproducibility, the photographs and radiographs were superimposed on the true vertical line and the angle between the true horizontal (from N') and N'-Pog' was assessed. The mean, standard deviation (SD) and confidence interval of the three angles along with short- and long-term method errors were calculated. Correlation coefficient of the angles was analyzed according to time. The differences of registration in genders were determined by t-test. Results: Short-term reproducibility between the two photographs was 2.44º and the long term reproducibility between the first photograph-radiograph and the second photograph-radiograph was 3.23º and 3.38º, respectively. Method error in registration of NHP by photography and radiography showed no systematic bias. Gender had no significant effect on reproducibility. Conclusion: NHP is a reproducible position in adults after 3 years. This position is more consistent in men. Photographic and radiographic registrations of NHP indicate similar results.
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Statement of problem: Microorganisms are essential for the development of periradicular diseases and are one of the major causative factors associated with endodontic treatment failures. Different instruments and preparation techniques have been developed in Endodontics to eliminate or reduce intracanal bacteria. Purpose: The aim of this study was to compare the amount of remaining E. faecalis in the apical third of root canals following instrumentation with Profile, Race and FKG files. Materials and Methods: Ninety freshly extracted mandibular single canal premolars were selected. A horizontal groove was made circumferentially around the roots at a depth of 0.5 mm and a distance of 5 mm from the anatomic apex. All the equipments were sterilized overnight by ethylene oxide gas. Root canals, inoculated with E. faecalis suspension, were prepared using Profile, Race or FKG instruments in a step-back technique. Master apical file, amount of irrigant for each canal and working length were similar in all specimens groups. Following preparation, the apical portions of the roots were separated from the previously made grooves and were sampled by sterile paper points. Statistical analysis was performed using ANOVA and Duncan’s multiple range tests. Results: Profile was significantly more effective in eliminating E. faecalis as compared to Race. A significant difference was not observed between FKG and the other two studied instrumentation techniques. Conclusions: Neither of the methods could completely eliminate E. faecalis from the root canals.
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Statement of problem: Surface disinfection is an important aspect of infection control in dentistry. A new generation of quaternary ammonium components (QACs) is gaining popularity as high-level disinfectants. Two types of QAC sprays, UniseptaQuick and SolarSept, are being widely used by Iranian dentists. Purpose: The aim of this study was to evaluate the clinical efficiency of Unisepta quick and Deconex Solarsept sprays against a number of selected microorganisms. Materials and Methods: In this experimental single-blind study, Unisepta quick and Solarsept sprays were examined using 15 specimens for standard and resistant pseudomonas aeruginosa, staphylococcus aureous, salmonella typhimurium, bacillus subtilis, mycobacterium bovis and trichophyton mentagrophytes. Test surfaces consisted of high-speed handpieces which were contaminated with suspensions of the microorganisms. Cultivation and incubation were performed and bacterial counts (Colony Forming Unit) were obtained. Data were analyzed using Fisher’s exact, chi-square and Mann–Whitney U-tests. Results: Unisepta quick and deconex solarsept showed bactericidal effects on pseudomonas aeruginosa, staphylococcus aureous, mycobacterium, and salmonella typhimurium and demonstrated fungicidal effects on trichophyton mentagrophytes. However, neither of them had a significant effect on bacillus subtilis and resistant-pseudomonas aeruginosa. Conclusion: Deconex solarsept and unisepta quick are effective against all tested microorganisms, except bacillus subtilis and resistant pseudomonas aeruginosa; therefore they can be classified as intermediate-level disinfectants.
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Statement of problem: Dental caries are considered as one of the most common health problems and have been shown to be more prevalent in children. Purpose: The aim of this cross-sectional study was to determine the distribution of dental caries among 400 twelve-year-old schoolchildren, in the Al-Mukalla area in Yemen. Materials and Methods: Multistage stratified sampling was used to obtain a sample size of 400 children, consisting of 200 males and 200 females with mixed dentitions. All subjects were selected from two private schools and five public schools. Clinical examinations were performed under standardized conditions by a trained examiner. Results: Dental caries was found in 198 (49.5%) of the 400 schoolchildren including 51.5% males and 48.5% females. The prevalence of caries was higher (p<0.05) in permanent teeth (76.6%), in urban areas and in the mandible (54%); compared to deciduous teeth, rural regions and the maxilla, respectively. Private schools (57%) revealed a larger number of affected cases as compared to public schools. Dental caries were more prevalent in children living in areas that received their water supply from Al Ghail, in comparison to those residing in regions supplied from Al Taweela water source (p<0.05). Caries were the primary cause of missing teeth in 8% of the subjects. Conclusion: Considering that dental caries can be associated with children’s school grade, dental services should be directed toward preschool children with a preventive policy through dental health education..
