[Comparison of shear bond strength of orthodontic brackets bonded with Core Max II and Transbond XT in fluorosed teeth and evaluation of enamel damage after debonding]

Orthodontic bracket bonding may encounter difficulties in fluorosed teeth. The aims of this study were to compare the shear bond strength [SBS] of brackets bonded to fluorosed teeth with Core Max II and Transbond XT and to assess the enamel damage after debonding. In this in-vitro study, 60 fluorosed [TFI=4 and 5] and non-fluorosed teeth were divided into two subgroups. The standard edgewise metallic brackets were bonded to the teeth with Transbond XT in the first and third groups, and with Core Max II in the remaining groups. After bonding, the SBS of the brackets was tested with a universal testing machine. The obtained data were analyzed by two-way ANOVA, post-hoc [LSD], Kruskal-Wallis, Wilcoxon, and paired samples tests. Fluorosis significantly reduced SBS [P =0.041]. Core Max II significantly increased SBS [P =0.040]. Teeth in group 4 [fluorosis and Transbond XT] had the lowest SBS [13.44 +/- 1.69 MPa]; group 2 [fluorosis and Core Max II] showed the highest enamel damage. Core Max II is a good adhesive for orthodontic bracket bonding in fluorosed teeth but conservative debonding methods should be necessarily applied to decrease enamel damage

effect of fluoride-releasing elastomeric chains on streptococcus mutans levels in saliva and dental plaque in orthodontic patients

During fixed orthodontic treatments the absolute number and percentage of salivary Streptococcus mutans increase. This will cause increase of enamel demineralization and dental caries. The purpose of present study is to evaluate the effect of fluoride-releasing elastomeric chains in the streptococcus mutans levels in saliva and bacterial plaque. In this randomized clinical trial sixty patients, who were under fixed-orthodontic appliance treatments were selected and randomly divided into two groups of 30 each. Conventional elastomeric chains were used in group 1. As for the second group fluoride-releasing elastomeric chains were utilized. Four samples of saliva collected on days 0, 7, 14 and 28, and two plaque samples were collected on the beginning and finishing days in both groups. The fluoride-releasing and conventional elastomeric chains were removed on day 28. All samples were then used for microbial culture to count the Streptococcus mutans colonies. The results were analyzed statistically with the repeated measures Analysis of Variance [ANOVA] and Student t-tests. The result of Streptococcus mutans [CFU] in saliva at each time point in the study showed no statistically significant difference between the two groups [p >/= 0.301]. Comparison of the effect of elastomeric chains on the Streptococcus mutans colonization in dental plaque and elastomeric chains surface, also did not show any statistically significant difference between the two groups [p= 0.3 Hand 0.803 respectively]. There was no clinical evidence that fluoride-releasing elastomeric chains were effective in reducing the formation and colonization of Streptococcus mutans in saliva and dental plaque

[Comparison of mircoleakage beneath orthodontic brackets using two different methods of enamel preparation]

Decalcification of the enamel in orthodontic patients mainly follows plaque accumulation, but it is promoted by appliance components and the materials used for bonding. This study was designed to compare the microleakage beneath metallic orthodontics brackets, using two different methods of enamel preparation. Sixty bovine deciduous lower incisors were collected, and divided into two equal groups. For bonding the stainless steel brackets using Transbond XT as light cured composite, the surface enamel preparation of each group was as follows: Group I: Acid etch+Transbond XT primer and Group II: self-etching primer. After immersion in fuchsin basic 0.5% for 24 hours, each group was randomly divided into two subgroups of 15 samples and placed in acrylic block, in order to have mesiodistal and buccolingual sectioning. The sectioned teeth were evaluated under stereomicroscope and both enamel-adhesive and adhesive-bracket interfaces were scored for the micropleakage. Kruskal-Wallis and Mann-Whitney U tests were used for statistical analysis for compare the groups. The level of significance was set at p<0.05. No significant differences in the microleakage scores on the gingival and incisal sides were observed in the interfaces between the groups [p>0.05]. Mesiodistal margins of the self-etching groups showed significantly lower scores for microleakage in the enamel-adhesive interface in comparison with acid etch group [p<.o5]. With the limitation of this study using the self-etch primers in enamel preparation for bonding of the orthodontic brackets seems acceptable if all the margins of the brackets are cured directly

Prevalence of malocclusions in school-age children attending the orthodontics department of Shiraz University of Medical Sciences

To provide quantitative data about the prevalence of malocclusions in the Shiraz orthodontic population, we studied the records of 700 patients [391 girls and 309 boys] aged 6-14 years attending the undergraduate Department of Orthodontics at Shiraz University of Medical Sciences. The prevalence of Angle class I, II and III malocclusion of first molars was 52.0%, 32.6% and 12.3% respectively. Skeletal class I, II and III malocclusion was found in 18.0%, 70.0% and 12.0% respectively. There were no significant differences between the sexes in the prevalence of different types of skeletal malocclusion. Children with class III were significantly younger [mean age 8.9 years] than those with class I [9.6 years] or class II [9.7 years] malocclusions. Orthodontics students need more education and training in the management of class II malocclusion to improve the overall quality of care for patients

[Correlation between index of orthodontic treatment need [IOTN] and self-evaluation in 18-22 year old patients]

Index of orthodontic treatment need [IOTN] has several applications and advantages for determination of orthodontic treatment need. Due to the effects of different factors such as gender, age and socioeconomic status on treatment need based on self evaluation, it is important to evaluate correlation between orthodontic treatment need assessed by self- evaluation and real treatment need assessed by IOTN. The purpose of this study was to evaluate the correlation between orthodontic treatment need as assessed by IOTN and self- evaluation in 18-22 year old patients. Of 18-22 year old patients referred to Shiraz dental clinics, 240 were selected by random cluster sampling method. IOTN and self- evaluation questionnaires were filled in. In self-evaluation questionnaire, the mean scales for all the questions were determined as the scale of patient. The correlation between treatment need as assessed by IOTN and self-evaluation was evaluated by Pearson correlation and Partial correlation statistical analysis. There was a significant moderately positive correlation between Dental Health Component [DHC] and self-evaluation [r=0.51]. Also, the correlation between Aesthetic Component [AC] assessed by the examiner and patient and self evaluation was significantly positive. [r=0.39, r=0.31]. The significantly positive correlation between IOTN and self-evaluation indicates that in assessment of orthodontic treatment need, not only standard indices but also self-evaluation of the patient should be taken into account

Effect of changing cross head speed on shear bond strength of orthodontic brackets and mode adhesive failure

In most shear bond strength [SBS] studies, different cross head speeds have been used. The effect of different speeds on the shear bond strength has been studied in very limited researches. The aim of this study was to evaluate the influence of changing cross head speed of testing machine on the shear bond strength and failure mode of orthodontic adhesive [Transbond XT] in bracket bonding. For this experimental study, 175 human premolars with intact enamels were divided into seven equal groups of 25. After surface preparation, brackets were bonded to teeth using transbond XT adhesive. For deboning process various cross head speeds of 0.5, 1, 2.5, 5, 7.5, 10, 25 mm/min were applied. Shear bond strength and Adhesive Remnant Index [ARI] were recorded for different groups. One way ANOVA and Tukey tests were used for bond strength comparison. Data on shear bond strength evaluations and modes of bond failure were analyzed using Kruskal- wallis and spearman tests. The means of shear bond strength for the applied 0.5, 1, 2.5,5, 7.5, 10 and 25 mm/min cross- head speeds were 16.39, 14.37, 13.30, 14.12, 13.32, 16.58, and 13.83 respectively. Shear bond strengths in groups receiving 0.5, 10 mm/min cross head speeds, were significantly greater than other groups. No significant differences were obtained between these two speeds, as well as, between 1, 2.5, 5, 7.5, 25 mm/min speeds, but there were significant differences in the shear bond strengths between the two groups with the cross head speeds of 0.5, 10, and 1, 2.5, 5, 7.5, 25 mm/min. Considering the ARI, no differences were found between the groups. Also, there was no relation between ARI and bond strength in groups with different cross head speeds, except in 5 mm/min. Cross head speed of Instron is an effective factor on the SBS of the adhesives, but it does not have significant effect on the failure mode of bonding materials

[ effect of different tooth surface preparation methods on microshear bond strength]

Evaluation of new adhesives efficacy in bonding orthodontic brackets to enamel has led to different results. The new measuring method, micro-shear bond strength, is preferred as an accurate method due to its ability to reduce confounding factors.The purpose of this study was to evaluate and compare the micro-shear bond strength of three different adhesive systems for enamel surface preparation before bracket bonding.In this experimental study, 90 extracted premolars were randomly divided into three groups of 30. Transbond XT was bonded to enamel after enamel surface preparation with acid etch in the first [control] group, Transbond plus self-etch primer in second group, and Adper prompt L-pop self-etch adhesive in third group. Then each group was randomly divided into two subgroups of 15. Micro-shear bond test was performed after 24 hours [T1] and 3-months [T2]. Bond failure mode was also evaluated according to Adhesive Remnant Index [ARI]. Two way ANOVA and Tukey tests were used for bond strength evaluation in groups, and mode of bond failure was analyzed with Kruskall Wallis and Mann Whitney tests.The highest bond strength was found in acid etch group [29.17 MPa]. Difference of bond strength at two intervals was statistically significant in all groups [p <0.001]. Bond strength difference between T1 and T2 was also significant in three groups [p <0.001]. However changes over time in three groups did not reveal any significant differences [p = 0.091]. Bond failure analysis demonstrated significant differences in ARI between groups.Bond strength of acid etch group was the highest and self etch primer showed higher bond strength than self etch adhesive group. Less adhesive remnant was found in self etch group

[Evaluation of enamel surface damage following use of two different adhesive resins and debonding pliers; a stereomicroscopic study]

At the final stage of fixed orthodontic treatment, the debonding process has high potential in causing enamel damages especially enamel cracks. Thus, the investigation on the effective factors involves in the amount of enamel damages including the type of resin and the method used for debonding is necessary. The aim of this study was to evaluate and compare the number of enamel cracks and changes in cracks length following bonding with two different adhesives, and debonding with two different pliers by stereomicroscope. In this interventionally in-vitro study, 120 extracted first premolars were randomly divided into four equal groups of 30. The metal brackets were bonded on the teeth with two pastes self-cure composite "Concise" in the first and second groups, and No-mix composite "Unite" in the third and fourth groups. The debonding was done by means of Lift off Debonding Instrument "LODI", in the first and third groups, and Dentaurum Bracket Removing Plier, in the second and forth groups, respectively. Before bonding and after debonding, all teeth were evaluated with stereomicroscope for comparing the changes in the number and lengths of enamel cracks. Data were analyzed using Wilcakson and Mann Whitney tests using SPSS statistical package. Statistically significant differences [p<0.001] in the number and length of enamel cracks after debonding were evident in all groups. The most increase in the number of new cracks was observed in the fourth group [p<0.05]. The results indicated statistically significant difference [p<0.05] in increasing the total length of enamel cracks between group 4 and groups 1, 2. The debonding procedure is principally destructive to enamel surfaces. Applying shear-peel force using bracket removing plier with Unite adhesive [group 4], increased the enamel defects compared to other combination of adhesives and debonding pliers

effect of Cyclosporine A on the orthodontic tooth movement in rats

Immunosuppressive drugs have special effects on bone remodeling during orthodontic tooth movement. This study aimed at investigating the effect of oral Cyclosporin A, an immunosuppressive drug, on the orthodontic tooth movement in rats. Eighty male Sprague-Dawley rats, weighting 220-280 gm, were used. The animals were randomly assigned into control and experimental groups, each one containing 40 rats. Each group included four subgroups, each of 10 rats. Four groups of rats were selected for the assessment of the effect of olive oil and stripping stress of the lower incisors for a period of 15 and 30 days. The two experimental sub-groups received 10 mg/kg Cyclosporine A by gastric gavages every 24 hours for 15 and 30 days. The other two experimental sub-groups received 30 mg/kg cyclosporine-A by gastric gavages every 24 hours for 15 and 30 days. A fixed orthodontic appliance consisting of nickel - titanium closed coil spring, was ligated between the maxillary right incisor and the first molar. The initial activating force was 60 gm. One way Analysis of Variance and Tukey were used for comparing tooth movement between the two groups and eight sub-groups. The results showed that oral Cyclosporine A [30 mg/kg/30 day] could accelerate the rate of orthodontic tooth movement in rat [0.635 +/- 0.22 mm] [P<0.05]. Also, its administration period was more effective than the dose itself. Olive oil and stripping stress could not increase the rate of tooth movement. Due to the findings of this study and predominant effect of Cyclosporine A on orthodontic tooth movement in rats, the patients using Cyclosporine A may have the chance of more tooth movement. Further studies are requested for evaluating the effect of Cyclosporine A on increasing tooth movement in accordance with its dose and duration

[Effect of premolars extraction on Bolton overall ratio in an Iranian population]

Tooth size discrepancies [Bolton ratio] affect the best possible esthetic and functional results at the end of treatment. The extraction decision is the most critical decision when planning treatment, and the premolars are the most common teeth in this decision. The purpose of this study was to compare the effect of different patterns of premolar extraction on tooth size discrepancy at the end of orthodontic treatments. This cross-sectional study was carried out on 200 study models of the patients [145 females and 55 males] who were selected through available selective sampling method. The greatest mesiodistal width of all teeth were measured except for the second and third molars. The measuring was done by a digital caliper with 0.01mm accuracy. According to calculated Bolton overall ratios, the patients' casts were divided into three groups: NB [Normal Bolton], DB [Decreased Bolton], and IB [Increased Bolton]. This classification was based on the overall Bolton normal values plus or minus one standard deviation. The Bolton overall ratios of each group were measured before and after hypothetical extractions of different four premolars. The data was analyzed using one way ANOVA, and the paired t-test was used for comparing the ratios between males and females. The results showed that there was no significant difference between males and females in Bolton overall ratios. Significant differences were found between overall ratios for different combinations of premolar extraction before and after extractions. The Bolton overall ratios showed to be smaller after premolar extractions in each group. After premolar extractions, some patients in the NB and IB groups were transferred to the DB, and NB group respectively. According to the results of this study four premolars extraction causes a decrease in Bolton overall ratio and in some patients, increased overall ratios could be corrected to normal values after removal of second mandibular premolars

Evaluation of Possibility of Using Core Max II in Bonding Orthodontic Brackets to Teeth

Different adhesives have been used for bonding orthodontic brackets to teeth. The aim of this study was to evaluate the possibility of using Core Max II in bracket bonding by comparing it's shear bond strength with the two commonly used orthodontic adhesives; Transbond XT and Unite. In this interventional study, 105 human premolars were divided into 3 groups of 35 each. After etching with 37% phosphoric acid, Dyna-Lock stainless steel brackets [3M Unitek, Monrovia, CA] with the average base surface area of 12.09 mm2 were bonded with three different adhesives; Core Max II [Sankin, Tokyo, Japan] Transbond XT [3M Unitek] and Unite [3M Unitek]. The shear bond strength of 3 groups were measured by a universal testing machine [Instron 3401, Canton, Mass] with cross- head speed of 0.5 mm/min. Adhesive Remnant Index [ARI] was determined under 10[X] magnification. For data analysis, SPSS statistical package was used. Mean shear bond strength of Core Max II [17.24 +/- 3.2 MPa] was significantly higher than Transbond XT [15.44 +/- 2.2 MPa] [P=0.009] but had not statistically difference with Unite [17.16 +/- 3.7 MPa] [P=0.93]. Evaluation of ARI indicated that 83% of Core Max II samples had score 0 or 1 and 17% had score 2 or 3. These percentages were 66% and 34% for Transbond XT and 77% and 23% for Unite, respectively. In this study, it was concluded that: 1] Core Max II had a shear bond strength higher that Transbond XT and equal to Unite. 2] ARI of Core Max II showed a higher frequency of score 0 and 1, which indicated that after debonding, most of the adhesive remains on the bracket base. 3] Core Max II has the potential of being a good orthodontic adhesive

[Cost- income analysis of oral health units of health care centers in Fars province and evaluation of oral health indices in 2001-2003]

Increasing demands for health care services on one hand, and limited resources on the other hand brings about pressure over governments to find out a mechanism for fair and appropriate distribution of resources. Economic analysis is one of the appropriate tools for policy making on this priority. The objective of this study was to assess capital and consumption expenditure of Oral Health Units of Health Care Centers in Fars province and its effectiveness on oral health indices. The data were collected by statistical forms in urban and rural Health Care Centers which were sent to Provincial Health Care Centers every 3 months from 2001 to 2003. Oral Health Unit service expenses had been 6,871,471,160 Rials in 2001, 6,243,026,540 Rials in 2002 and 7,009,570,880 Rials in 2003 respectively. Income/cost ratio was 20% in 2001 and it was 25% and 26% in 2002 and 2003 respectively. In spite of this high expenses, the oral health statues of 6-12 year old children did not improve during the survey period. Regarding the low tariff of dentistry services and also subsidiary payment to target groups, the Oral Health Unit expenses are always more than its income. These costs had no effect on oral health indices [dmft, DMFT] in Fars province

[Use of panoramic radiographs in localization of maxillary impacted canines]

In spite of low prevalence of maxillary canine impaction in population [1%-3%], its occurrence in orthodontic patients is nearly high sometimes reaching 23.5%. The exact determination of impacted canine location is of high importance for better access as well as correct force application. The purpose of this study was to determine the impacted maxillary canines location by orthopantomograph using Chaushu's method in comparison with their real location which were determined by surgical exposure of the teeth. Sixty eight panoramic radiographs of patients with either unilateral or bilateral maxillary canine impaction were evaluated using Chaushu's method. The available selected patients [14 males, 54 females] were treated orthodontically by force eruption of canines after surgical exposure. The mean age of the patients was 17 years. The largest mesiodistal width of 82 impacted canines as well as central incisors of the same side and also the contralateral side erupted canines were measured and evaluated using Chanchu's technique for determining canineincisor and canine-canine indexes [CII, CCI]. Also these ratios were evaluated and compared for different horizontal and vertical positions of impacted canines. The mean of CII for palatally and bucally impacted canines were found to be 1.17 and 1.07 respectively which was statistically significant. Considering their vertical positions, it was revealed that CII was valid only in coronally positioned situation. In case of unilateral impaction, the CCI did not show to be statistically significant for buccal or palatal side. Evaluating the relation of impacted canine crown to the lateral incisor's root, it was found that the palatally impacted canines were located more mesially than bucally impacted ones. Although panoramic radiography could show the buccal or palatal position of the impacted canines in coronally impaction situations, but due to the effect of their vertical position and also maxillary apical form on the radiographic magnification, use of other complementary radiographs for exact determination of impacted canine location seems to be necessary

[ new index [micro angle] for evaluating sagittal jaw relationship in comparison with beta angle; a cephalometric study]

In Orthodontic diagnosis and treatment planning one of the most important issue is an accurate anteroposterior measurement of jaw relationship. The most commonly used angular and linear measurements that have been proposed, such as ANB angle and Wit's appraisal can be inaccurate and misleading due to their dependence on various factors. This study was aimed at establishing a new cephalometric measurement, named the micro angle, to assess the sagittal jaw relationship with accuracy and reproducibility. The micro angle uses 3 skeletal landmarks, point A, point B and a perpendicular line from point A to the mandibular plan. One hundred and fifteen pretreatment cephalometric radiographs of orthodontic patients [mean age 16 +/- 2 years] were selected on the basic of inclusion criteria according to their skeletal and profile patterns. The patients compromised of 30 class I, 45 class II and 40 class III skeletal relationships and profile pattern, the mean and standard deviation for the new angel [micro] and the previous reported angle [beta] were evaluated. One way analysis of variance [ANOVA] and the Newman-Keuls test were used for data analysis as well as, dermination of the new angle's specifity and sensitivity comparing with beta angle. The results obtained showed that a patient with a micro angle between 16.1 degree and 23.9 degree can be considered to have a class I skeletal pattern. A more acute micro angle is an indication of a class II skeletal pattern and a more obtuse micro angle indicates a class III skeletal pattern. The new angle [micro angle] has an acceptable specificity and sensitivity in determining the anteroposterior relation of jaws and thus can be used for assessing the type and severity of jaw discrepancies, besides the other diagnostic parameters