ABSTRACT
Although Wit's appraisal is a valuable measurement for antero-posterior jaw relationship evaluation in orthodontic patients, occlusal plane detection is difficult in a lot of cases or is challenging due to its various inclinations. In this study a new method for assessment of sagittal skeletal relationship is introduced and the purpose of this investigation is evaluation of correlation between wit's appraisal and this new method. Lateral cephalograms of 71 orthodontic patients [male and female] from all types of skeletal malocclusions [class I, II, III] were collected and analyzed. Two lines were traced from point A and point B while they were perpendicular to Frankfort Horizontal plane [FH] and also to functional occlusal plane [Wit's] and the both distances were measured. Pearson Correlation analysis was performed for assessment the relationship between AO'-BO' distance on FH [q] and wit's appraisal. Correlation of these variables was evaluated with SNA, SNB, ANB and overjet, separately. The results showed a high correlation of variables using Frankfort Horizontal plane and wit's appraisal [r= 0.82]. Both methods revealed significant statistical relation with SNA, SNB, ANB and overjet [p< 0.05]. The highest scores of correlation with ANB were obtained in using both methods. The use of measurement is as much valuable as the usual wit's measurement and it can be a good alternative in patients when tracing the accurate occlusal plane is impossible or difficult
ABSTRACT
The aim of this study was to evaluate the effect of application of two types of primers over bracket bases on the shear bond strength [SBS] and mode of bond failure. In this study, 75 human premolar teeth were divided into three equal groups. In group 1 [control], after surface preparation of enamel by conventional method [acid etching+primer] brackets were bonded with Transbond XT composite. In group 2 [TX], brackets were bonded to enamel same as the first group but Transbond XT primer were used on bracket bases before placement of composite. In group 3 [PL], Transbond plus primer was applied on bracket bases before placement of composite. After 24 h, the SBS test was performed by universal testing machine at crosshead speed of 0.5 mm/min. Then, adhesive remnant index [ARI] scores and percentage of cohesive fracture were determined using stereomicroscopy. SBS data were analyzed by one-way ANOVA and Duncan tests. Kruskal-Wallis and Mann-Whitney tests were used to analyze ARI and cohesive fracture results. There was significant difference in SBS values among the groups [P<0.001]. The highest SBS was shown in TX group and the lowest was seen in PL group. There was no significant difference between control and TX groups in ARI scores [P=0.199]. No significant difference was found in cohesive fracture values between the groups [P=0.093]. Both the control and TX groups showed significant difference in ARI scores and cohesive fracture compared with the PL group in all of the comparisons [P<0.001]. Application of Transbond XT primer over bracket base affects the bond strength and failure mode. Transbond XT primer increased the bond strength but Transbond plus primer decreased it
ABSTRACT
Efforts to find correlation between ossification events in the hand and wrist, developmental conditions of the teeth, and chronological age can lead to assessment of developmental status of an individual as a simple and useful method. The aim of this study was to investigate the relationship between chronological, dental and skeletal ages among 7 to 13 year old children referring to Orthodontic Department, Shiraz Dental School. This cross-sectional study was conducted on 40 female and 22 male subjects. Sixty two panoramic and hand wrist radiographs were obtained. Dental ages were assessed according to Demirjian based on the lower left canines, first and second premolars and second and third molars. Greulich and Pyle standard atlas was used to determine the skeletal age. The results were analyzed using Pearson coefficient correlation. A statistically significant relationship [p<0.01] was found between dental and chronological ages. The relation between dental and skeletal ages was significant too [p<0.05]. At the same skeletal maturity stage, dental maturation patterns of the male subjects were ahead and the G stage of the canine for both sexes [60%] coincided with the MP3cap stage. It is suggested that tooth calcification stages in panoramic radiographs might be a valuable indicator to assign timing of growth spurt
Subject(s)
Humans , Male , Female , Age Determination by Teeth , Child , Age Factors , Cross-Sectional StudiesABSTRACT
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
Subject(s)
Orthodontic Brackets , Resin Cements , Dentin-Bonding AgentsABSTRACT
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
Subject(s)
Shear Strength , Bicuspid , Dental Bonding , Surface PropertiesABSTRACT
Evaluation of skeletal growth which is necessary in growth modification and orthognathic surgery is usually done by using skeletal maturity indicators of hand and wrist radiographs. The use of growth stages of cervical vertebrae seen in lateral cephalometrics films currently has been suggested to avoid over exposure. The purpose of the present study was to investigate the degree of agreement between hand and wrist bones developmental stages and cervical vertebral maturation stages. The subjects of this cross-sectional study consisted 58 females and 61 males ranging from 8 to 17 years old divided into 10 groups. A total of 119 hand, wrist and lateral cephalometry radiographs were obtained and analyzed. The hand and wrist radiographs were evaluated according to the Fishman system, which uses four stages of bone maturation found at six sites located on thumb, third finger, fifth finger and radius. Cervical vertebral maturation was determined from lateral cephalometry radiographs based on a system developed by Hassel and Farman. In all age groups, the skeletal maturity stage in the hand and wrist bones and cervical vertebrae of female subjects were ahead of male subjects. The Kappa test revealed a high degree of agreement between skeletal maturation indicator in hand and wrist bones and cervical vertebrae in all of the samples [d. of a.=0.846, p<0.001], females [d. of a.=0.791, p<0.001] and male [d. of a.=0.892, p<0.0001]. The chronological conformity between 2 methods showed a high degree of agreement in all age groups except in 8 and 17 years old ages. The highest chronological agreement was seen in 15 years old age group, although the degree of agreement in 8 years old age group was low and in 17 years old age group was moderate. According to the results of this study, hand and wrist radiographs can be easily replaced by cervical vertebral maturation analysis for evaluation of skeletal developmental stage
ABSTRACT
Statement of Problem: Despite numerous cephalometric studies and criteria proposed with respect to standards for hard tissue, studying and analysis of soft tissue has received much less attention in Iran
Purpose: This study aimed to evaluate adults facial soft tissue with normal occlusion and skeletal relationships in Fars province
Materials and Methods: In this study 1500 university students in the age range of 18-24 years were examined clinically. From whom, those with normal occlusion and balanced faces were selected for cephalometric evaluation. After analysis, 44 subjects including 23 females and 21 males with normal cephalometric measurements were selected to conduct Steiner, Rickett's, Merrifield and Holdaway analysis on their facial soft tissue. The obtained values were then compared with standard ones using the above Cephalometric soft tissue analysis and the T and Leven's statistical tests
Results: According to the results of Merrifield analysis, values for the Z angle were almost identical and did not display a significant variation within each of the female and male groups. Using the Rickett's analysis, the mean distance for upper and lower lips from the Eline were not radically different, and similar values were obtained for both groups. The male subjects had more distinctive projected lips compared to their female counterpart. According to the results obtained from Steiner analysis, the mean distance value for the male group was higher than that of the female group. However the results from Holdaway analysis showed that only three variables out of a total of 11, chin thickness, upper lip thickness and the extent of upper lip strain had a statistically significant difference between the two subject groups. The remaining measured variables did not display any significant differences
Conclusion: We can conclude that men suffered from a higher upper lip strain compared with women. Furthermore, with the exception of Steiner and Holdaway [only for three of the measurements], statistically no significant differences were observed between the values of the sampled subjects and those sampled outside Iran