ABSTRACT
OBJECTIVE: The aim of this study is to compare the adaptation of a straight wire between brackets positioned at the mid-lingual surface and those placed gingivally by using a three-dimensional simulation software. METHODS: This cross-sectional study was performed using OrthoAid, an in-house software. The subjects were 36 adolescents with normal Class I occlusion. For each dental cast, two bracket positioning approaches, namely the middle and gingival, were examined. In the middle group, the reference points were placed on the mid-lingual surface of each tooth, while in the gingival group, the reference points were positioned lingually on the anterior teeth. A 4th degree polynomial was adopted, and the in-plane and off-plane root mean squares (RMSs) of the distances between the reference points and the fitted polynomial curve were calculated using the software. Statistical analysis was performed using the paired-samples t-test (α = 0.05). RESULTS: The mean in-plane RMS of the polynomial curve to the bracket distance in the gingival group was significantly lower than that in the middle group (p < 0.001). The off-plane RMS was higher in the gingivally positioned brackets in the maxilla than in the middle group (p < 0.001). However, the off-plane RMS in mandible was not statistically significantly different between the two groups (p = 0.274). CONCLUSIONS: The results demonstrated that the gingival placement of lingual brackets on the anterior teeth could decrease the distance between a tooth and the straight wire.
Subject(s)
Adolescent , Humans , Cross-Sectional Studies , Mandible , Maxilla , Orthodontic Brackets , Orthodontics , ToothABSTRACT
Objective: For the assessment of primary arch form, different methods have been used including qualitative classifications, inter-canine and inter-molar widths and quantitative and numerical methods using mathematical models. The purpose of this study was to compare the validity and reliability of Cast Analyzer X Iranian software with those of Curve Expert Professional version 1.1 for arch form construction based on mathematical models
Methods: This diagnostic, in vitro study was performed on 18 sets of dental casts with normal Class I occlusion. The clinical buccal points [bracket attachment sites][CBPs] were marked on each tooth and their spatial coordinates were digitized using a three-dimensional [3D] laser scanning system. These coordinates were entered in Cast Analyzer X and Curve Expert software programs. Arch forms were constructed by the software programs using Brown's beta function, Noroozi's beta function and fourth order polynomial equation. The root mean square [RMS] of the distance from a reference point to their corresponding points on the curve was calculated. The RMS values in the two software programs were compared
Results: The RMS values in Brown's beta function, Noroozi's beta function and fourth order polynomial equation were significantly different in the Cast Analyzer X software [p<0.001] and the fourth order polynomial equation had the lowest RMS. The difference in RMS values between the two software programs was not clinically considerable and was 0.45 and 0.68 mm for the fourth order polynomial equation and Brown's beta function, respectively
Conclusion: Considering the RMS values, the fourth order polynomial equation is the most suitable analysis for describing normal dental arch forms best fitted with the CBPs. Although the difference between the two software programs was statistically significant, this difference was not clinically noticeable. The RMS value was lower in Cast Analyzer X and consequently the fitting of curves with the landmarks [CBP] was better in the Iranian software
ABSTRACT
Candida albicans is one of the most common causes of hospital infections. The aim of this study was to develop a rapid, easy and sensitive way to detect candida albicans. Polyclonal antibodies were prepared in rabbits. The antibodies were purified by salt concentration and Ion exchange chromatography. The purified antibody was coated onto the colloidal gold. Color change [red to blue] was observed when the purified antigens [mannoprotein of Candida albicans cell wall] were added to Polyclonal antibodies. The method was sensitive and easy. This study indicated that using colloidal gold particle agglutination method can be used for accurate and rapid candida detection Method.
Subject(s)
Animals , Membrane Glycoproteins , Agglutination Tests , Antigens , Rabbits , Gold ColloidABSTRACT
In assessment orthodontic treatment need, for the same group of people, dentists usually have different ideas with respect to a gold standard. The most common way of determining validity of the assessments is computing coefficients of agreement like Kappa and Weighted Kappa. In this article we first present shortcomings of the coefficients and then propose a more appropriate alternative method for evaluating of agreement. This analytic cross-sectional investigation has been done with the Index of Orthodontic Treatment Need [IOTN]. This index which independently was measured on 51 study models by an expert dentist [as gold standard] and 10 other dentists [as raters], has 5 ordinal levels [no need, little/mild need, moderate/borderline need, severe need, extreme need]. Diagonal parameter model and uniform association model were used for modeling agreement to evaluate validity of the assessments. In 6 cases, diagonal parameter model [with significance level at least 0.34] and in 4 other cases, uniform association model [with significance level at least 0.36] were appropriate to the relevant data. The best assessments belong to the dentists for whom uniform association model was fitted and the worst of them to the dentists for whom diagonal parameter model was fitted. All of the dentists tended to rate casts higher than the gold standard, so that local odds ratio for dentist who had the least[most] tendency to rate casts higher than the gold standard was 6.4[121.5], So all of them needed to be further educated to assess the index
ABSTRACT
One of the new methods for stress distribution evaluation is finite element. In this method, mechanical properties of objects including implants may be evaluated and advantage and disadvantages of each configuration may be revealed. The purpose of this study was comparison of vonmisses stress distribution of three implants, Persia, ITI and Biohorizons in surrounding bone of anterior and posterior part of mandible by finite element modeling. In this study first experimental model of mandible was constructed by means of CMM, according to data's from human skull CT scans. Then the implants were modeled using Project Profile. Mesh was constructed on the model in ANSYS and implants were located were located at first incisor and second molar area. The elastic modulus and cortical layer thickness applied in incisor [D2] and molar [D3] region was different. Three force vectors and two moments were applied, [Vertical = 100N vestibule lingual: 20n [t2] mesiodistal = 20 N [T1] M1 = M2 = 100 N/mm], first individually and then all together. The results were calculated by ANSYS software using contour and graphs. In incisor [D2] coronal region the best vonmisses stress distribution was seen in Biohorizon. In body, the distribution was same in ITI and Biohorizon which was better than Persia. In apical area, the least stress was distributed respectively in Biohorizon, Persia and ITI. In molar [D3] area coronal region, the amount of stress was least in ITI and was distributed differently in the way of penetration to trabecular layer. In body, the distribution was respectively better in Biohorizon, Persia and ITI. In apical region, best stress distribution was seen in Biohorizon however it was not property concentrated in ITI type. Condition of surrounding bone and implant design causes variation in vonmisses stress distribution around implants. In area's which quality of surrounding bone is weak range of variation is higher and stress concentration may cause bone resorption. The best distribution in weak bone condition was revealed around Biohorizon. Persia [made in Iran] have proper stress distribution and may compete with other brands