Journal of Dental Medicine
Year:2008 | Volume:21 | Issue:3 (56)|Papers Count:11

Background and Aim: Soft tissue condition around dental implant is an essential part for long term healthy and esthetic outcome. The aim of this study was to compare soft tissue dimensions between implant supported single tooth replacement and the contra-lateral natural tooth.Materials and Methods: This retrospective study was performed on dentate patients treated with anterior single tooth implant at least 1 year ago. Of twenty eight, fourteen patients had been treated with one stasge method and others with two stage method. Biologic width (BW), papilla index (PI), and mucosal thickness (MT) were evaluated around implants and contra-lateral teeth clinically and compared with each other. The Wilcoxon test, Mann-Whitney test, and Student pair t-test were used to assess the differences between one stasge and two stage implants, and implant and tooth groups.Results: The mean BW around one stasge implants, two stage implants, and contra-lateral teeth were 1.42±0.48 mm, 1.67±0.48 mm, and 1.47±0.60 mm, respectively. The mean PI adjacent to one stasge implants, two stage implants, and contra-lateral teeth were 2.50±0.52, 2.53±0.55, and 2.72±0.47, correspondingly. The mean MT around one stasge implants, two stage implants, and contra-lateral teeth were 3.10±0.48, 3.09±0.75, and 2.57±0.88, respectively. There was no statistically significant difference among one stasge implants, two stage implants, and contra-lateral teeth with regard to measured variables.Conclusion: Based on the results of this investigation, in standard condition, it seems that there is no noticeable difference in indicators of; biologic width, papilla index, and mucosal thickness around onestasge implants, two stage implants, and contra-lateral teeth.

Background and Aim: By definition, pontic is an artificial replacement of missing tooth (teeth) which is essentially used to establish function and esthetics. In order to this fact that, pontic(s) is not completely the same as tooth (teeth) to be replaced, it may not be concern as a simple type of restoration to achieve the best result, it must be design from the esthetically and hygienically point of view as well as comfort, demand and tissue health of patient. The main purpose of this study is to investigate the pontic designs and their relationship to edentulous partial aras.Materials and Methods: 73 pontics in 57 patients have been included in this cross-sectional study. These patients were under treatment in the department of prosthodontics. A primary cast was achieved from each patient and then the cross-sectional contour of edentulous ridge was depicted. For each patient the type of pontic design was derived from textbook standards and then compared with the design of actual verified Prosthesis at delivery. The shape of tissue surface of each denture was determined by a low viscous impression material. The result of each comparison was recorded in a chart data set.Results: The most common pontic design was Modified ridge lap with frequency of 93.2%. The type of ridge was %45.2 normal, %19.2 class I, %8.2 class II and %27.4 class III, respectively. %72.6 of pontics tested have inappropriate design in tissue surface.Conclusion: It seems that in a high percentage of cases the tissue surface contour of prescribed pontics in department of prosthodontics was incorrect and more attention must be paid to the education of students and technicians

Background and Aim: Elimination of microorganisms and their byproducts from root canal system is one of important aims of root canal therapy. This object is gained by using of many chemomechanical techniques but with noncertain success. A new method is used of nonpathogenic bacteria for growth inhibition of pathogenic bacteria, Antibiosis, in root canal therapy. The aim of this study was in vitro evaluation of antimicrobial effect of probiotics, such as Lactic Acid Bacteria (LAB) on the infected root canal bacteria.Materials and Methods: Isolated bacteria from infected root canal were grown and then scattered onto themuller Hinton agar plates which contain wells, LAB, extracted from dairy products, were added into these wells, Inhibition effected of LAB was determined. Furthermore the sample taken from the inhibition zone and possible resistant monoclonal bacteria also were identified, then 6 sensitive and 14 resistant samples were selected and E. faecalis species were added to them; Then antimicrobial effects of LAB on these samples was reevaluated.Results: The results showed that 66.7% of the samples were sensitive at least to one type of LAB, and 33% were resistant to all kind of LAB. Meanwhile the outgrowing anaerobic bacteria inside the inhibition zone were from the low frequency oral bacterial flora. Furthermore, adding E. faecalis to the samples caused more sensitivity of them to LAB. Mc-Neamar test recognized the difference significant.Conclusion: This study showed that the LAB inhibit growth of the pathogenic root canal bacteriae. Furthermore, presence of E. faecalis reinforces the antimicrobial effect of LAB. It seemed that LAB maybe have potential to use in endodontic practice for elimination of root canal infections.

Background and Aim: Digital subtraction Radiography (DSR) is a method of accurate assessing condylar head changes. several studies have been carried out in applying DSR in dentistry, however there is a few number of studies in efficacy of DSR method in assessment of condylar head changes, The aim of this study was to compare panoramic radiography and DSR detecting simulated lesions of the mandibular condyl.Materials and Methods: this was a process research study, in which two dry human skulls with no obvious temporomandibular joint pathology were used. Osteophytic lesions were simulated using three sizes of bone chips that were placed on the medial portion of anterior and superolateral aspects of the condyle. Osteolytic lesions were simulated making 1 and 2 mm holes using round burr in the central portion of anterior aspect and Lateral pole of the condyle. Panoramic radiographs were prepared with and without the lesions in place. These paired radiographs were digitized and digital- subtraction images of the original panoramic images were obtained. Eight observers evaluated 155 images of each modality for the presence or absence and the type of simulated lesions of the mandibular condyle. Sensitivity, specificity, reliability and measure of agreement were analyzed using kappa test and crossed tables and qualitative variables were assess by chi-square and fisher’s Exact test.Results: Specificity of panoramic and DSR methods were 15.4% and 66.7% respectively. Sensitivity of panoramic and DSR methods were 61.1% and 80.6% for osteophytic lesions and 37.5% and 83.3% for Osteolytic lesions. The percentage of correct decisions made in DSR method was significantly more than conventional panoramic method (82.6%vs 41.9%) (p<0.0001).Conclusion: Based on the results of this study digital subtraction technique was significantly more accurate than the panoramic radiographs in detection of simulated lesions of the mandibular condyle.

Background and Aim: Polymerization shrinkage of resin cements during setting leads to stress on teeth receiving indirect esthetic restorations. Some methods like blocking out undercuts during cavity preparation with glass Ionomer can reduce the mass of resin cement and therefore the amount of stress. The aim of this study was to evaluate the fracture resistance of molar teeth, receiving class I ceramic inlays with two different methods of blocking out undercut.Materials and Methods: In this experimental study, thirty intact molar teeth were randomly divided into three groups of 10 each. One group was maintained intact as the control group. Similar class I cavities with identical undercuts were prepared on the other groups. In group 2 the undercut was filled with light cured glass Ionomer (vitremer 3M) before making impression, and in group 3 they were blocked out in the lab before preparation of the inlay. All the teeth in test groups were restored with indirect ceramic inlays. (vitadur – Alpha/ single bond / Rely X ARC). After thermocycling load causing fracture was assessed by universal testing machine. All the specimens were examined under a stereomicroscope (X40) to determine type of fracture. The results were analyzed by one way ANOVA and Tukey HSD tests. P<0.05 was considered as the level of significance.Results: The restored groups showed significantly less fracture resistance than the control group. The difference between two test groups was not significant. The fracture in group2 had less destruction.Conclusion: According to the findings of this study, blocking out the undercut with two different methods (using glass ionomer/ or blocking it out on the die) made no difference in fracture resistance.

Background and Aim: Image distortion is one of the major problems in panoramic radiography. Horizontal and vertical correction factors could be determined for more efficient clinical applications. The purpose of this study was to determine horizontal and vertical correction factors in panoramic radiography.Materials and Methods: In this test evaluation study in which an asymetric mandibular phantom was constructed by plexiglass and aluminium as soft and hard tissue equivalents. The right half was slightly shorter than the left half. Steel makers were installed to make vertical and horizontal measurments possible.The length of the markers as well as the intermarker distances were measured by Mitutoyo digital micrometer which was accurate within ±0.05mm. The phantom was then positioned in PM 2002 cc proline (Planmeca, Finland) panoramic machine and panoramic images were obtained. 8 times for each half of the phan. The same length and inter marker distances were measured on digitized panoramic images by Cygnus software, which was accurate within ±0.01 mm. Magnification and correction factors were determined for the vertical and horizontal dimensions in each region of pantomograms.Results: The mean vertical correction factor was 0.77±0.02 (range: 0.75-0.80) in the right and 0.77±0.05 (range: 0.75-0.85) in the left half jaw. The mean horizontal correction factor was calculated as 0.98±0.15 (range: 0.76-1.18) in the right and 1.02±0.14 (range: 0.90-1.25) in the left half jaw.Conclusion: Dissimilarity of vertical and horizontal correction factors among left and right half jaws and also in different regions of a half jaw is relatively considerable. However, a constant correction factor, specialy in horizontal aspect, could not be applicable. Comparing with horizontal correction factors the vertical correction factors showed less variations between different regions as well as different samples.

Background and Aim: Fractured anterior teeth can be restored by adhesive bonding of the separated fragment to the remaining tooth structure. This invitro study evaluated the force required for fracture of rebounded fragments which were dried and rewetted for various time intervals prior to bonding.Materials and Methods: One hundred and eight human mandibular incisors were selected and were divided into 9 groups and then were fractured. The fragments were stored in air at room temperature and ambient humidity. They were air dried for 30 minutes in group 1, 2 and 3, 6 h in group 4 and 5, 24 h in group 6 and 7, and 3 days in groups 8 and 9. The apical parts of the fractured teeth were stored in water. After storage in air, each fragment in group 1 was bonded to the remaining apical tooth structure with a bonding agent and flowable composite. In groups 2, 4, 6 and 8 after air drying the fragments were stored in water for 30min. The time of storage in water in groups 3, 5, 7, 9 were 24 hours. Then each fragment was bonded to the apical part structure. The mean force required for fracture was measured by a mechanical testing machine. One way ANOVA and Tuckey tests were used for analysis.Results: There were statistically significant differences between different groups (p<0.001).The highest and lowest force required for fracture belonged to groups 3 and 8 respectively. The force required for fracture in group 1 was lower than group 2, 3, 5 and 7 and 9 and more than groups 4, 6 and 8 with significant differences. While there were no significant differences among groups 3, 5, 7, 9 and 4, 6, 8 the force required for fracture in groups 2, 3, 5, 7 and 9 was more than 4, 6, 8 with significant differences.Conclusion: This research revealed that the force required for fracture was affected by air storage of fragments prior to bonding. Also showed that with an increase in duration of drying the force required for fracture decreased and after a period of time it becomes steady. This study showed that in order to increase the fracture strength after air drying the fragment should be immersed in water for at least 24 hours prior to bonding.

Background and Aim: The roles of applying rotary instruments in reducing preparation time and proper root canal preparation have been approved in permanent teeth. The aim of this study was to compare the rotary instruments (Hero642) and K-files in root canal preparation of primary molars. Time and canal transportation were compared.Materials and Methods: In this experimental, invitro study, 30 human extracted primary molars with 8 mm length were selected and divided into two equal groups. After preparing access cavity, group 1was prepared by Kfiles and group 2 by Hero642 systems. Before canal preparation, with # 15 K-file and after canal preparation, with master apical file, canal curvature was evaluated by Weine technique using Radiovisiography. Apical transportation was calculated. Time taken for preparation was recorded by chronometer. The results were analyzed with T-test and Mann-Whitney. P<0.05 was considered as the level of significance.Results: The average canal transportation angle was 3.42 for Hero642 group and 7.33 for K-file group (p<0.04). The mean instrumentation time was 4.28 for Hero642 group and 8.76 minutes for K-file group (p<0.001). There was a significant difference between two groups.Conclusion: Based on the findings of this study, it is suggested to apply Hero642 rotary instrument for primary molar canal preparation due to less preparation time and less canal transposition.

Amelogenesis imperfecta is an inherited disease that disturbs the formation of the enamel. It occurs as two main categories, hypomineralized and hypoplastic. Both deciduous and permanent teeth are affected, and the disorder may create unaesthetic appearance, dental sensitivity, and severe attrition. In this article through performing a structured literature review, numerous treatment modalities which so far advocated in rehabilitation of amelogenesis imperfecta in adults and children is discussed. The progressive changes on open bite, the problem of bonding during restorative phase of treatment , the rehabilitation difficulties of deciduous as well as permanent teeth is also discussed in detail and finally the interdisciplinary approach for treatment of this disability is demonstrated and some points for decision making in treatment protocols are suggested.

Background and Aim: Infective endocarditis is a rare disease resulted in mortality and morbidity in 10-80% of patients. The purpose of present study was to investigate the knowledge of guidelines on antibiotic prophylaxis for bacterial endocarditis in a group of Iranian dentists.Materials and Methods: This was a descriptive study in which the population under study was 205 who were participated in the 47th international congress of dentistry (Tehran-Spring 2007) and they were chosen by census sampling methods. Nameless questionnaires were designed and were given to the dentists to complete. The t-test, X2 and spearman with the SPSS 13.5 program were used in the data analysis. P<0.05 was considered as the level of significance.Results: Regarding to the prescribing of prophylactic antibiotic for patients with prosthetic cardiac valves, 94.6% of all answers were correct. Also, the most common procedures in which the prophylaxis antibiotic was distinguished to be necessary were periodontal surgery, scaling, dental extraction and using subgingival cord, respectively. More than half of the dentists (65.8%) had chosen amoxicillin as a prophylactic antibiotic. Mean knowledge score was 38.77±12.4.Conclusion: Results of the present study showed that the knowledge of dentists about prescribing antibiotics for prevention of bacterial endocarditis is relatively low. It was also found that the level of knowledge decreases by passing time from graduation