JOURNAL OF ISLAMIC DENTAL ASSOCIATION OF IRAN (MAJALLAH-I-DANDANPIZISHKI)
Year:2010 | Volume:21 | Issue:4 (73)|Papers Count:12

Background and Aim: Recently, the number of patients with temporomandibular disorders (TMD) has been increased. The aim of this study was to conduct epidemiologic evaluation of TMJ health status among adolescents aged 11-14 years old in Mashhad. Materials and Methods: This cross sectional study included 1066 students who were selected through cluster sampling method. A questionnaire was used to collect data for each student. The questionnaire composed of two parts. In history section, data on TMD related signs and symptoms were collected. In part 2, the results of TMJ clinical examination was collected at rest and movement. Other conditions such as muscular tenderness, mandibular deviation, limitation in mandibular movement and finally occlusion and prematurity at lateral mandibular movement were recorded as well. Data was analyzed by using chi-squre and logistic regression at a=0.05. Results: The overall prevalence of TMD was 23.5%. The most frequent TMD sign was muscle tenderness. TMJ tenderness in Lateral Movement, clicking , headache, Mandibular deflection, TMJ tenderness in resting position, mandibular deviation, limitation in lateral movement, limitation in opening the mouth were less prevalent respectively. The most important etiologic factor of TMD was prematurity at balancing side of lateral movement and next was parafunctional habits, trauma, hand under the chin, or one side of the face as a body posture, deep bite malocclusion and unilateral chewing. Conclusion: The most frequent TMD sign was muscle tenderness and the most important etiologic factor of TMD was prematurity at balancing side of lateral movement.

Background and Aim: Bonding type and curing time may affect shear bond strength of composite to dentin. This study was conducted to evaluate the effect of these factors on composite to dentin bond strength. Materials and Methods: The buccal dentin of seventy-two intact extracted premolar and molar teeth were etched with phosphoric acid 37% for 5 seconds (S) and washed with water, for 15S and dried for 2-3S. The teeth were randomly assigned to six groups. Group1: Dentin Bonding (DB) was applied once and not cured; Group 2: DB was applied once and cured for 10S; Group3: DB was applied once and cured for 20S; Group 4: DB was applied twice and not cured; Group 5: DB was applied twice and each layer cured for 10S; Group 6: DB was applied twice and each layer was cured for 20S. Then composite blocks were placed on bonded surfaces and cured for 40S. The specimens were thermo-cycled and the shear bond strength was measured using Instron testing machine. The data were analyzed with two-way ANOVA and Tukey HSD tests. Results: Mean shear bond strengths of the groups in MPa were as follows: Group1: 15.57; Group 2: 16.22; Group 3: 16.68; Group 4: 17.39; Group 5: 18.18 and Group 6: 20.02. (P<0.001) Additionally the mean bond strength of groups cured 20S was significantly higher than other groups (P<0.05). Conclusion: Adequate polymerization time and increased adhesive layer thickness could improve bond strength of composite to dentin.

Background and Aim: Odontogenic keratocysts are usually in need of extensive treatment and are concerned mostly by researches in order to find their biological behavior. M inichromosome maintenance3 (MCM3) over-expression has been reported in several human beings affected by odontogenic. To our knowledge there is no article about MCM3 expression in odontogenic keratocyst. The aim of this study was to evaluate MCM3 in odontogenic keratocysts and compare it to Ki-67 and p27. Materials and Method: Total of 23 OKC specimens were selected from Razi laboratory, they were reconfirmed by two indipendent pathologists. Clinicohistopathological data were recorded and standard streptavidin-biotin peroxidase method of immuohistochemical (IHC) staining was conducted for Ki-67 antigen, p27 Kip1 and MCM3. The immunostained cells were counted on 10 HPF (Labeling Index) and then classified to negative, low, moderate and high levels. Statistical analysis was done by SPSS 13 using Freidman & Spearman's Rho test s and PLUM-Ordinal Regression. P-value less than 0.05 were considered significant. Results: Ki-67 was stained mostly in the basal and suprabasal cells but p27 was found in the upper layers. No sample was stained by MCM3. There were significant differences among these proteins (MCM3 compared with Ki-67 & p27) not between p27 and Ki-67. No correlation was found among age, location and lesion size with these markers. Conclusions: Most of the odontogenic keratocysts expressed low levels of both Ki-67 and p27. We also found MCM3 is not implicated in the pathogenesis of OKC.

Background and Aim: Mercury is a natural-occurring metallic substance. There are quantities of mercury found in air, water, soil, and all living matters. It is considered as one of the harmful metals to human being. Study of normal mercury content in human internal organs, blood, urine and saliva can be useful in assessing the level of environmental exposure. Such information may be useful and contributes to medico-legal expert opinions. The present study was conducted to determine the un-stimulated whole saliva mercury content in high school students in Tehran. Materials and Methods: This cross sectional study recruited 130 volunteer high school students (65 male, 65 female). They were selected randomly from 5 different geographical sites in Tehran. All examinations conducted in this study were undertaken during the day from 9AM to 12PM, at least 2 hours after last intake of food and drink. By using spilling method, about 5CC of saliva was collected in a specially prepared test tube. Mercury was measured by Cold Vapor Atomic Absorption Spectrometry (CVAAS). SPSS software and Man-Whitney U test were used for data analysis. Results: The average student age was 16.5 and the average saliva mercury concentration was 0.17mg/dl, with 0.20mg/dl in males and 0.16mg/dl in females. No significant difference was detected between males and females saliva mercury levels. Conclusions: This study showed that a trace of mercury is detectable in saliva of people who have no amalgam fillings. Such information may be useful for relevant studies conducted in future.

Background and Aim: Composite restoration microleakage has been reported following bleaching treatment. The purpose of this study was to assess the in-vitro effect of sodium ascorbate gel on microleakage of class V restorations on bleached teeth. Materials and Methods: Forty-eight premolar teeth were randomly divided into 4 equal groups. Class V cavities were prepared on the buccal surfaces of group 1 teeth (negative control) and they were restored. In groups 2-4, bleaching was applied by using 9.5% hydrogen peroxide gel. In group 2 (positive control) and group 3, (delayed bonding) teeth were restored immediately and one week later, respectively. In group 4, 10% sodium ascorbate gel was applied, rinsed and restored. After thermocycling, samples were immersed in fushin and then, sectioned. Leakage was assessed and penetration of dye was scored. Data were analyzed using Kruskal–Wallis and Dunn’s tests. Results: There were significant differences in terms of microleakage between group 2 and other groups (P<0.05). Groups 1, 3 and 4 exhibited similar leakage patterns, and all groups demonstrated less leakage values than group 2. Regarding marginal microleakage, there were significant differences between enamel and dentinal margins. Conclusion: Applying sodium ascorbate gel or 7-day delay following bleaching technique may improve the marginal integrity of composite class V restorations.

Background and Aim: Space maintainers are appliances used to preserve the space and prevent ectopic movement of adjacent and opposing teeth when premature loss of deciduous teeth occurs. This study aimed at evaluation of general dental practitioners’ knowledge and attitudes regarding the space maintainers in Tabriz. Materials and Methods: This descriptive cross-sectional study involved 151 subjects, selected randomly from 450 general dentist practicing in Tabriz city/province, located in the North-West of Iran. A self-administered questionnaire was provided to subjects and included questions to evaluate the knowledge and attitudes as well as their case selection policy. Data were analyzed using Chi-square and ANOVA tests. Results: 103(70%) of dentists were male. The mean age of subjects was 33.32 years. The mean score on knowledge was 5.32 out of 10 and the mean score on attitude was 25.3 out of 40. About 76.5% (n=115) of participating dentists admitted child patients, younger than 12 years old. These dentists had higher scores in both sections than others. This difference wasn't significant. Increasing scores in the years after graduation was followed by decreasing scores which was statistically significant (P<0.05). Conclusion: The general dental practitioners under investigation in this study had a good attitude towards the use of space maintainers. Their knowledge in this regard, however, could be improved by means of attending continuing dental education programs, workshops, brochures and pamphlets.

Background and Aim: Using intra cranial reference lines is inherently unreliable for assessment of anterior-posterior jaw relationships. However, they are being widely used for cephalometric evaluation and diagnosis and treatment planning of orthodontic patient. The aim of this study was to evaluate the correlation of the TH/AB and TH-Wits to the common horizontal and vertical analyses. Materials and Methods: This cross sectional descriptive study was conducted with 40 adults (20 male, 20 female) who were between 18-24 years-old and had no history of craniofacial disorders. Lateral cephalometries were taken for all patients, using Natural Head Position (NHP). All the cephalograms were taken by the same radiologist and were traced by same person. Two orthodontists approved the results and the kappa statistics was calculated to determin intra-examiner agreement level. Pearson correlation coefficient value was determined between TH-Wits, TH/AB and horizontal parameters (Wits, Harvold, Wylie, APP-BPP, and ANB angle) and vertical parameters (Sn-GoGn, S-Go/N-Gn, TH-GoGn and sum of posterior angles). The correlation analysis was used in order to determine the relationship between these parameters. Results: The results revealed that the highest correlation in horizontal direction was observed between TH-Wits, TH/AB; and ANB (0.73) and APP-BPP (0.68 & 0.61). In vertical direction, the highest correlation was demonstrated between TH-Wits, TH/AB; and sum of posterior angles (0.75 & 0.35). Conclusion: In using TH-Wits and TH/AB, the effect of changes in vertical dimension and the lack of significant correlation between these parameters and linear horizontal analysis should be considered.

Background and Aim: Cigarette smoking may affect saliva, oral commensal bacteria and fungi, mainly Candida that causes oral candidiasis. This study was designed to evaluate the prevalence of Candida colony count in smokers and non smokers based on clinical and preclinical findings. Materials and Methods: This case control study recruited 72 subjects, 36 smokers and 36 non-smokers who were selected after a primary clinical examination and completion of a questionnaire. The saliva was collected by spitting in sterile test-tubes after tooth brushing. Samples were transferred to a lab for culture and colony count. The colonies were counted after 48 hours and results were analyzed by using T-test and Pearson correlation coefficient. Results: The mean number of colonies in smokers was 140 and in nonsmokers were 67.25. This finding shows that the mean number of colonies in smokers is significantly higher than non-smokers (P=0.01). Also, there was a significant relationship between the number of daily cigarette smoked and the number of colonies (P=0.039, r=0.346). Another finding of this study showed that the number of colonies increased with age among smoker's group (P=0.039, r=0.346). There was no significant relationship between the number of colonies and age in nonsmokers (P=0.822, r=0.039). Conclusion: Based on the results of this study, we can conclude that, there is a direct relationship between cigarette smoking and increased growth of Candida in the mouth of smokers. It was also demonstrated that, the higher the number of cigarette smoked, the higher was the number of Candida in the mouth.

Background and Aim: Restoration of severely damaged primary anterior teeth by early childhood caries is a challenge for clinicians. Due to pernicious nature of this condition, immediate and definitive treatment has been advocated in order to prevent further tooth destruction. It is important to preserve the integrity of natural primary dentition until the expected exfoliation time. The aim of this study was to review all suggested restorative techniques as well as their success rate in treatment of decayed maxillary anterior teeth. Materials and Methods: Aside from initial hand searching, all published studies after 1990 were identified by searching Medline, The Cochrane Library, Embase, Scopus, Iran-medex, Google and scholar databases using “ bottle caries, early childhood caries, treatment of nursing caries, children caries”. Results: For intra-canal retention of severely decayed primary teeth, resin composites, reinforced fiber, fiber glass, treated post, nickel chromium cast post with macroretentive element, can be used. A variety of restorative materials and technique are available for restoring primary anterior teeth such as atraumatic restoration, sandwich technique, stainless steel crown, open-face crown, pre-veneered S.S.C, bicarbonate crown, resin composite crown, biologic crown and strip crown. However, due to lack of supporting clinical data, none of these crowns can be determined as superior to others. Conclusion: Choosing many alternative treatment plans available to repair carious primary anterior teeth, the operator need to consider several factors such as, size and location of lesion, parental esthetic demands, child’s attitude and behavior, moisture and hemorrhage control. These are variables that ultimately affect the treatment outcome.

Background and Aim: Bleaching teeth can lead to decreased calcium, phosphate and fluoride content of enamel which may cause decreased enamel micro-hardness. Reportedly, the topical use of fluoride can help regaining those minerals. The aim of this study was to evaluate the effect of fluoride therapy on enamel micro-hardness when used before or after bleaching. Materials and Methods: Total of 60 premolar teeth were divided into 5 groups. The occlusal surface in all teeth were flattened and covered with nail varnish. Initially, all specimens were inserted in artificial saliva for 7 days. Group 1 used as negative control. Samples in group 2 were bleached 2 times with 30 minutes interval for 5 days, using %45 carbamid peroxide. Group 3 samples were exposed to fluoride varnish for 5 minutes. Group 4 exposed to fluoride varnish for 5 minutes, bleached 2 times for 30 minutes in 5 day intervals. Group 5 samples were treated same as group 4, however, followed by fluoride varnish for 5 minutes. Micro hardness for each group measured in 3 points after cleaning the occlusal section. The LSD and ANOVA tests were used for data analysis. Results: This study showed, reduction in enamel surface hardness can be compensated by fluoride application. Group 2 (bleached only) showed the minimum micro hardness (294.38), and group 3 (exposed to fluoride only) showed the maximum micro hardness (455.36). Conclusion: Fluoride therapy can affect enamel micro-hardness before and after bleaching. The application of fluoride varnish is recommended after exposing teeth to bleaching agents.