Journal of Dental Medicine
Year:2012 | Volume:25 | Issue:2 (71)|Papers Count:11

Background and Aims: Accurate recording of implant location is required to achieve passive fit and have the implants without stress concentration. The aim of this in-vitro study was to evaluate the dimensional and angular accuracy of open-tray and closed-tray impression techniques using polyether impression material and also to assess the surface detail reproduction of the tooth while impression making.Materials and Methods: One reference metal model with 2 implants (Implantium) on the position of the maxillary second premolar and first molar and one molar tooth for evaluation of surface details was prepared.27 polyether impressions of these models were made (9 using open-tray, 9 using closed-tray techniques and 9 were made just of the surface of the teeth without any implants). Impressions were poured with ADA type IV stone.Coordinate Measuring Machine was used for measuring the dimensional accuracy and video measuring machine for surface detail reproduction. All of these measurements were compared with the measurements on the reference model. Data were analyzed by and compared by T-test and One-way ANOVA.Results: There was a significant statistical difference between open-tray and closed-tray techniques (P<0.001).There was no significant difference in the surface detail reproduction of open-tray and Closed-tray techniques and impression making with or without the implants (P>0.05).Conclusion: The accuracy of open-tray impression technique was more than closed-tray technique. The surface detail reproduction of the tooth was not affected by impression technique.

Background and Aims: The aim of this study was to measure the degree of conversion (DC) of three types of composite resins (micro-hybrid, nano-hybrid and Ormocer) with different light curing units (LED LCU and QTH LCU) in two depths.Materials and Methods: Three commercially available dental resin composites were used in this study: (Tetric Ceram, Ivoclar Vivadent, Liechtenstein-A2 shade), (Tetric Evoceram, Ivoclar Vivadent, Liechtenstein-A2 shade), (Ceram X, Dentsply, Germany-M2 shade). Specimens were divided into two groups, 5 specimens were photoactivated by QTH unit (Coltolux 75-Colten) and the other five specimens were cured by LED (Demi-Kerr). Then each specimen was sectioned at the top surface and at 2-mm depth. The DC was measured by FT-IR (Bruker-tensor 27). The data were analyzed by 3-way ANOVA test.Results: There was significant difference between tested composite resins (P<0.001). The results of top surfaces were significantly different from those observed at 2-mm depth (P<0.001). The type of curing unit affected the polymerization of Ceram X resin composite.Conclusion: This study showed a significant difference in the degree of conversion in different thicknesses within three groups of resin composites.

Background and Aims: Adequate retention of the post is a prerequisite for the clinical success which might be affected by the type of root canal filling material. The aim of this in vitro study was to compare the effects of gutta-percha and Resilon on retention of quartz fiber posts.Materials and Methods: In this experimental study, 44 maxillary central incisors were sectioned at the CEJ level and prepared endodontically using ProTaper rotary files. The specimens were then randomly assigned into two experimental groups (n=22): group R, the root canals obturated with Resilon; and group G, the root canals obturated with gutta-percha. After preparing the post space and insertion of quartz fiber posts, the coronal 10 mm of the root was sectioned perpendicular to the long axis to produce disks of 2.3 mm thickness. Then the specimens were submitted to the push-out test (1mm/min) using a universal testing machine? The data were analyzed using Mann-Whitney U test.Results: There was a significant difference between the retention of posts in groups R (7.08±5.1) and G (4.8±3.3) (P=0.04).Conclusion: Quartz fiber posts showed significantly higher retention in teeth obturated with Resilon compared to those obturated with gutta-percha.

Background and Aims: Using the conservative adhesive resin restoration (CAR) in uncooperative children lead to numerous problems because of being time consuming. The purpose of this study was to compare the microleakage of conservative adhesive resin restoration under separate curing and co-curing.Materials and Methods: In this experimental study, 120 intact premolar teeth were collected and 120 vertical grooves were prepared on them. Then the teeth were divided into four groups: group 1, separated curing of bonding agent, flowable composite and sealant; group 2, co-curing of all materials for 60 seconds; group 3, co-curing of all materials for 40 seconds and group 4, co-curing of all materials for 20 seconds. Then the specimens were thermocycled and immersed in basic fuchsin solution. The teeth were sectioned horizontally and dye penetration was evaluated with stereomicroscope. Dates were analyzed using one-way ANOVA and Scheffe test.Results: Mean value of dye penetration in groups 1, 2, 3, and 4 was 1.53±0.6, 2.06±0.6, 2.5±0.7 and 3.53±0.6, respectively. There was a statistically significant difference between group 1 and the other groups (P=0.0001).Conclusion: Considering the problems caused by microleakage in conservative resin adhesive restorations, cocuring method should not be used. In the case of using co-curing method, 60 second curing time is suggested for sufficient polymerization.

Background and Aims: Apical root resorption is an adverse side effect of fixed orthodontic treatment which cannot be repaired. The aim of this study was to use panoramic radiographs to compare the root resorption before and after the orthodontic treatment with standard edgewise.018 appliance.Materials and Methods: The before and after treatment panoramic views of sixty-three patients needed fixed orthodontic treatment included 1520 teeth were categorized into 3 Grades (G0: without resorption, G1: mild resorption with blunt roots or≤1/4 of root length, G2: moderate to severe resorption or>1/4 to 1/2 of root length.Relationship between root resorption and sex and treatment duration was analyzed with Mann-whitney and Spearman’s correlation coefficient, respectively.Results: The findings showed that 345 teeth were categorized as Grade 1. Grade 2 of root resorption was not found in this study. The highest amount of root resorption was recorded for the mandibular lateral incisor. In both gender, the root resorption of the mandible was more than that of the maxilla. The males showed significantly higher rate of resorption than the females (P<0.05). Root resorption was not significantly related to the treatment duration and the side of the jaws (P>0.05).Conclusion: The mandible and male patients showed higher amount of root resorption. In addition, root resorption was not related to the treatment duration and the side of the jaws.

Background and Aims: The purpose of this study was to design a new device assisting dental students to measure the tapering of the prepared teeth for fixed crown prosthesis in which the desired tapering for better clinical prognosis could be obtained.Materials and Methods: The designed device in this study had two arms that were placed on two opposite walls of the prepared teeth. To evaluate the validity and reliability of this device, 3 dies with different degrees (13, 29 and 45o) were used and 20 teeth were prepared by dental students with undefined tapering degrees. The measurements of tapering were performed by six last year-dental students in two different time periods.Comparison of errors in measurements on standard dies between observers and between time intervals were analyzed by (Wilcoxon) Paired t-test with a significance level of a=0.05.Results: For the three dies used in this study, we compared the differences for each measurement taken by observers with the standard taper of the dies. Maximum difference of measurements with true standard die tapering was 1 degree. A number of 6 measurements were under the true standard tapers and 2 measurements were above it. Interclass Correlation Coefficients (ICC) of the first and second measurements on prepared teeth were 97.4 and 97.5, respectively. There were no significant differences between different observers or two measurements of the same observer in different time intervals (P>0.05).Conclusion: The results indicated that this device can be valid and reliable for measuring the angle of convergence of the prepared teeth and can be used as an educational device in dental schools as a replacement for previous tapering measurement methods.

Background and Aims: Various methods are used for treatment of open bite. The objective of this study was to investigate the effects of Lower Anterior High Pull Headgear (LAHPH) appliance in Class I subjects with moderate open bite and high lower lip line.Materials and Methods: The study group was composed of 10 subjects with a mean age of 15.8±2.5 years and 3.05±0.07 mm moderate open bite. All the patients rejected or thognathic surgery. The treatment included extraction of upper and lower second premolars followed by leveling, banding, bonding, posterior space closure, and anterior retraction. After these procedures, the open bite was reduced to 2.04±1.17 mm. afterwards; LAHPH was applied for 18 hours per day for 8±2 months. LAHPH appliance was composed of High Pull Headgear and two hooks mounted on its inner bow. Two elastics (1.8, light, Dentaurum) connected the upper hooks on the inner bow to the lower hooks on the mandibular canines vertically. The forces produced by the prescribed elastics were 10 and 60 g during mouth closing and opening, respectively. Paired T-test was used to evaluate pre-and post-treatment outcomes.Results: The pre-and post-treatment cephalometric evaluations showed that the LAHPH reduced effectively the open bite of the patients to 0.15±1.7 mm (P<0.001).Conclusion: This appliance can be used as an acceptable method for closing the open bite in Class I subjects.

Background and Aims: Normative need assessments should be substituted or integrated by patient-based outcome measures regarding their shortages in health-oriented approach. This study aimed to assess and compare the ability of an index of oral health-related quality of life measured by Child Oral Health Impact Profile (COHIP) questionnaire and the Aesthetic Component of Index of Orthodontic Treatment Need (AC-IOTN) to identify the normative need to orthodontic treatment using Dental Health Component-IOTN in a sample of the Iranian adolescents.Materials and Methods: Target population of this cross-sectional analytic study was 597 of the 13 to 18 year-old schoolchildren enrolled in middle and high schools of the city of Isfahan, Iran. They completed the COHIP questionnaire and then were examined by two calibrated trained dentists (agreement coefficient: 0.9) to record the DHC grading. The students scored their AC in according to the images of the scale. The association between subjective indicators and clinically defined need were evaluated by the correlation analysis and the statistics for the diagnostic validity of tests.Results: Of 568 examined students, 16.7% and 2.1% had definite need according to DHC and AC criteria, respectively.10% of orthodontic patients had perceived distinct impact on their quality of life. The significant association (P=0.001) between the severity of malocclusion and quality of life was at moderate level by AC (R=0.37), but it was not convincing enough by DHC (R=0.16). The specificity of AC to detect the healthy ones showed to be excellent but its low sensitivity disabled the recognition of patients, precisely.Conclusion: The considered patient-based indices did not meet the competencies to define the orthodontic need in the adolescents, but it could be employed to identify the persons with impaired quality of life and it would probably benefit the process of prioritization.

Background and Aims: The oral impact on daily performance (OIDP) is one of the oral health-related quality of life indices to measure physical, social and mental consequences of the oral health status. This study aimed to evaluate the OIDP index in patients referring to Tehran dental school.Materials and Methods: Four hundred and ninety nine patients referring to patients’ clinic in Dental School of Tehran University of Medical Sciences in spring 2011 participated in this study. They were interviewed for demographic factors including age, gender and level of education, and OIDP index questionnaire before receiving any treatment. Statistical analysis was carried out by means of linear regression modeling.Results: 85.6% of patients confirmed that they had at least one oral impact on daily performance during the last 6 months. The most prevalent performances affected were eating (50.1%) and smiling and showing teeth without shame (12.8%). The mean OIDP score for the population was 5.6 ranging from 0 to 36. Linear regression modeling controlling for age, gender and years of education revealed that older patients and those with lower education had significantly higher OIDP scores.Conclusion: The effect of oral health on daily performance was clear. The association among age, education and oral impact on daily performance indicates the need for more comprehensive preventive oral health care for adults with lower educational level.

Background and Aims: Improper feeding is one of the most important etiologic factors in early childhood caries (ECC). In some clinical trials, breast feeding (BF) is mentioned as a causing factor in ECC. Results in this topic are different or even controversial. It is vital that all general advices given out are consistent with general health education messages. The aim of this study was to conduct a systematic review on the relationship between breast feeding and early childhood caries.Materials and Methods: Articles, guidelines, related books, and specific databases such as SID, PubMed, Scirus, Elsevier, American Association of Pediatric Dentistry (AAPD), American Association of Pediatrics (AAP) and American Dental Association (ADA) were searched for related topics cited since 1990. Early childhood caries definition, breast feeding and other variables such as sample size, study location and study design were analyzed.Results: According to data analysis, there was a lack of methodological consistency and inconsistent definitions of ECC and BF in the literature making it difficult to draw conclusions. Results about relationship between prolonged BF and ECC were inconclusive. There was a positive relationship between nocturnal BF and ECC. A history of BF did not have any effect on the caries incidence.Conclusion: Because of the role of breast feeding in children’s health, it is important to inform the parents about the possibility of dental caries due to nocturnal breast feeding.