Comparison of tooth size discrepancy in Cl two malocclusion patients with normal occlusions

Statement of Problem: There must be a proper mesiodistal tooth size ratio [Bolton analysis] between maxillary and mandibular teeth for good occlusal interdigitation. Therefore the Bolton analysis should be considered during diagnosis, treatment planning and predication of ultimate results

Purpose: The purpose of this study was to appraise tooth size ratios in Cl II malocclusion group and compare them with normal individuals

Materials and Method: This study was carried out on 60 pre-treatment orthodontic casts of class II malocclusion patients and 60 diagnostic casts of normal occlusion individuals which were selected through cluster sampling in accordance with the selective criteria. Each group consisted of 30 men and 30 women. The greatest mesiodistal diameters of all the teeth on each cast were measured by a digital caliper with 0.01mm accuracy except the second and third molars. Then tooth size ratios were analyzed as Bolton described. The statistical analysis were performed by chisquare and t-tests using SPSS

Results: The prevalence of anterior and overall tooth size discrepancy was relatively high [28.3%, 20%], showing no significant difference between men and women [p> 0.05]. The mean of anterior and overall tooth- size ratios in Cl II malocclusion group were 79.18 and 92.39 respectively, which were statistically different from the Bolton study [ideal occlusion] ratios [p< 0.05].There were no statistical difference between the means of anterior and overall ratios of men and women, neither in Cl II malocclusion group nor in the normal individual group [p> 0.05]

Conclusion: Considering the high frequency of tooth size discrepancy among CLII patients and the significant difference in Bolton ratios between this malocclusion and ideal occlusions; it seems that tooth size discrepancy can be considered as a possible etiologic factor and Bolton analysis should be performed as a pre-treatment diagnostic tool for this type of malocclusion

An investigation on As, Cd, Mo and Cu contents of soils surrounding the Meyduk tailings dam

The contents of As, Cd, Cu and Mo were determined in soil surrounding Meyduk tailings dam based on 21 surface soil samples. Assessment of toxic element pollution in studied soil samples needs knowledge of pre-anthropogenic metal concentration to act as a reference against which measured values could be compared. Estimating the background values was executed by sampling rocks adjacent to soil sampling stations. Various indices including enrichment factor [EF], pollution load index [PLI], modified contamination degree [mCd] and geoaccumulation index [I geo] were used for determining the contamination level of soil in the vicinity of tailings impoundment under the effect of the tailings dust. Anthropogenic pollution was diagnosed from natural one by sequential extraction done by Tessier et al method and calculating pollution intensity index [l poli]. The results indicate a significant upward enrichment in northeastern and southwestern surface soil around the tailings dam for Cd and Cu. The dominant wind direction demonstrated that only the contamination of southwestern soil around the tailings dam would be attributed to tailings dust while the dispersive dusts scattered after the mine explosions generally affected the northeastern part

Correlation between dental and chronological age in 6-15 years old orthodontic patients in Qazvin

The use of different stages of tooth eruption is preferred to estimate the children chronological age as it is less affected by hormonal changes or nutritional status. The most accurate method developed for determination of dental age is the Demirjian technique as indicated by different studies. The objective of this study was to assess the correlation between dental age and chronological age in 6-15 years old orthodontic patients in Qazvin in 2010. In this descriptive analytic study, 468 individuals [255 females and 213 males] were selected based on simple sampling and the dental age for each person was determined by Demirjian technique based on 7 mandibular left teeth. The chronological age was calculated by subtracting the birth date from the panoramic date. The correlation between the dental age and chronological age was assessed by Pearson coefficient and the difference between two genders evaluated. Significant and direct correlation was found between the chronological age and dental age [r=0.912 for females and r=0.905 for males]. With the exception of age 12 in males, the dental age of each individual was higher than the chronological age. The highest and the lowest differences between the two dental age and chronological age in each gender was noted in chronological ages of 6 and 14 in males and 6 and 8 in females, respectively. Based on results found in the presents study, it seems that the Demirjian technique to be valid for dental age estimation among Iranian people. However, the development of exclusive tables for Iranian population is necessary due to the overestimation of the individual's dental age compared to the chronological age

use of orthodontic need index [IOTN] in a referred Iranian population

IOTN index has been used in different countries for assessment of orthodontic treatment needs in recent years. This index has two components, an aesthetic component [AC] and a dental health component [DHC]. The aim of this study was assessment of orthodontic needs on the basis of IOTN index in those people who had come for orthodontic treatment. We used IOTN index in order to assess the orthodontic treatment needs of 343 applicants [262 females and 81 males] with a mean age of 18.1 [standard deviation 3.8 years]. Who had come for treatment during a certain period of time [8 months] For determining the AC we used a set of 10 pictures graded on the basis of aesthetical features of teeth. The DHC Component of Index that has five degrees was determined bases on study casts with standard preparation. If necessary and for more accuracy panoramic radiographies of patients were also used. The analysis of the obtained data was performed using Kappa, Chi-square and Spearman's tests. The results with determination of subjective needs on the basis of AC by patient's perceived need indicate a lock of significant relation between gender and the patients' perceived need for AC [p<0.05]. Most of these patients had determined their AC to be between grades 1-4, the results of AC determination through normative need assessment were the same as the results of perceived need Assessment. Which in case of DHC determination it was revealed that most subjects had a grade between 4 and 5, and there was a significant relation between DHC and type of malocclusion [p>0.05]. Subjective data of IOTN index alone can not be considered an appropriate indicator of orthodontic treatment needs determination

[ study on efficacy of NSAIDS in controlling pain caused by orthodontic treatment]

Considering the pain as one of the most significant reasons for patients avoiding orthodontic treatments, the topic of pain control appears to be of prime importance for both clinicians and patients. This study was aimed at determining the efficacy of commonly used non-steroidal anti- inflammatory drugs [NSAIDs] in controlling pain following orthodontic procedures. This was a double-blind clinical trial performed on a total of 75 patients, randomly divided into 5 groups following the placement of their initial arch wires. The members of each group received one of the 5 different treatments [Ibuprofen 400 mg, Naproxen 250 mg, Mefenamic acid 250 mg, Aspirin 325mg, and starch as placebo]. After receiving 2 doses of drugs [one hour before and six hours after bonding] the patients indicated the severity of their pain on a 100mm horizontal line [VAS] during mastication, biting, fitting on anterior and posterior teeth in different specified times. Statistical analyses were carried out based on ANOVA and t-test. The pain increased soon after the placement of the arch wire and reached its peak in 24 hours. In all cases, the least pain was reported following the administration of Ibuprofen and the most after taking placebo. Although all NSAIDs were more or less effective in controlling pain, ibuprofen was found to be relatively of higher efficacy in decreasing the pain

effect of chemical recycling on shear bond strength of orthodontic metal brackets

Recycling of brackets can significantly reduce the price of fixed orthodontic appliances but if the bond is more prone to failure during treatment, this potential benefit will disappear. The aim of this study was to investigate the effect of chemical recycling on bond strength of metal orthodontic brackets and failure pattern of recycled brackets. In this experimental study Instron machine was used to measure shear bond strength [SBS] of brackets in two stages on 60 human maxillary first premolars using No-Mix composite. Shear bond strength and pattern of failure were compared between recycled and new brackets in two stages. Data were analyzed by ANOVA and Duncan tests. Adhesive Remnant Index was evaluated in different groups by Pearson Chi-square test. P<0.05 was considered as the limit of significance. Statistical analysis showed that the mean values of SBS for new bracket group was 12.00 MPa and for recycled group and double recycled group, 9.94 Mpa and 10.00 MPa respectively. A significant reduction [about 18%] in bond strengths of brackets was observed at the first time of recycling. Recycling at the second time had no significant influence on the bond strength. Pattern of bond failure of these brackets showed that a great amount of residual adhesive material was remained on the teeth surfaces after debonding of recycled brackets which indicates that cleaning the teeth surfaces after debonding of recycled brackets is more time consuming. Based on the results of this study, before using recycled brackets, several advantages and disadvantages must be considered

comparative study between bond strength of rebonded and recycled orthodontic brackets

A large number of orthodontists prefer to rebond the failed bonded brackets or use recycled brackets in some instances. The aim of this study was to compare the shear bond strength of rebonding with using recycled brackets on enamel surface. Bonding of brackets on the surface of extracted first bicuspids was tested in five different groups to compare their shear bond strength [SBS]: Group N, new bracket on enamel surface of newly extracted teeth as a control group; Group R, recycled bracket on newly extracted teeth; Group NR, new bracket on the cleaned enamel surface of previously bonded teeth with Tungsten Carbide bur; Group RE, reused bracket on cleaned surface of previous teeth; and RR group, with brackets undergone two times of recycling on the newly extracted bicuspids. Adhesive Remnant Index was specified for each group. Twenty teeth were studied in each group. The highest SBS was related to control group [group N] which rated as 12.00 Mpa, and the next scores were related to groups NR, RE, RR, and R with 11.85, 10.80, 10.00 and 9.94 Mpa, respectively. The differences between groups N and NR with groups R and RR were significant [P<0.05]. Rebonding had no significant effect on reduction of SBS. Tungsten Carbide burs are suitable for removing of remaining composite from brackets and enamel surface and finally, chemically recycled brackets had a clinically acceptable SBS

[Peripheral blood monocytes responsiveness in aggressive periodontitis patients by comparison of Interleukin-6 production before and after stimulation by E. Coli lipopolysacharide]

Results of other studies suggests that hyper-responsiveness of monocytes to the products of dental plaque especially the endotoxin of Gram negative bacteria and secretion of high levels of pro-inflammatory cytokines may have a role in the pathogenesis of AP. To investigate this possibility, we evaluated the IL-6 production by cultured peripheral blood monocytes before and after stimulation by E.coli lipopolysacharide [LPS] in AP patients and healthy controls. Fifteen patients with AP were compared to 15 periodontal healthy controls in a case control study. Mononuclear layer was obtained from peripheral blood samples and monocytes were isolated and cultured. The reaction of monocytes was studied by IL-6 production before and 6 hours after stimulation by 0.1 micro g/ml E.coli. LPS. The IL-6 concentration in the culture supernatant was measured with ELISA [Enzyme linked Immunosorbent Assay]. Wilcoxon and Mann-Whitney U-tests were used to compare the groups. There was no significant difference in IL-6 production levels before LPS stimulation between patients and controls [P = 0.5]. The IL-6 production after LPS stimulation in the patients was higher than controls, and the difference approached the significance threshold [P = 0.07]. However, the increase in the IL-6 production as a result of LPS stimulation was significantly higher in patients compared to controls [P = 0.029]. Our results suggest that increase in monocyte responsiveness may play a potential role in the pathogenesis of AP. Elevation in cytokines elicited at the site of infection in response to a minimal bacterial challenge can exert significant effects locally and systemically. An over aggressive immune response can provide the basis of explanation for the observed severe tissue damage. and bone loss in periodontium, familial nature of aggressive periodontitis and other immunological findings associated with the pathogenesis of this disease. Future investigations through longitudinal monitoring of monocyte responsiveness over time and following successful treatment are required to elucidate the role of this phenomenon in the pathogenesis of periodontitis