Spectrophotometric analysis of crown discoloration induced by MTA- and ZnOE-based sealers

Crown discoloration can be induced by root canal sealer remnants following root canal treatment. Objective: The aim of this study was to evaluate chromatic alterations in human tooth crowns induced by a Mineral Trioxide Aggregate-based sealer (MTA Fillapex®) and a commonly used ZnOE-based sealer (Roth-811). The tested null hypothesis was that the application of the materials did not induce clinically perceptible crown discoloration (Ho: CIE color difference Δ

Spectrophotometric analysis of crown discoloration induced by MTA- and ZnOE-based sealers

Crown discoloration can be induced by root canal sealer remnants following root canal treatment. OBJECTIVE: The aim of this study was to evaluate chromatic alterations in human tooth crowns induced by a Mineral Trioxide Aggregate-based sealer (MTA Fillapex(®) and a commonly used ZnOE-based sealer (Roth-811). The tested null hypothesis was that the application of the materials did not induce clinically perceptible crown discoloration (Ho: CIE color difference ΔE<3.7). MATERIAL AND METHODS: Forty five fully developed, intact, mandibular third molars were sectioned 1 mm below the cemento-enamel junction. The pulp chambers were chemomechanically debrided via the cervical access. The specimens were randomly assigned into three groups Group 1: MTA Fillapex, Group 2: Roth 811, Group 3: Negative control (unfilled) and immersed in individually marked vials containing distilled water up to the cervix (37±1º C). The spectral reflectance lines were recorded by utilizing a UV-VIS spectrophotometer equipped with integration sphere in the visual spectrum at baseline, 1 week, 1 and 3 months after material placement. Data were transformed into values of the CIE L*a*b* color system and the corresponding ΔE values were calculated. Statistical analysis was performed using two-way mixed ANOVA models, at p=0.05 level of significance. RESULTS: A statistically significant increase in a* and b* chromatic parameters of the MTA Fillapex Group was measured. However, ΔE values did not exceed the human eye perceptibility threshold (set at ΔE<3.7) during the experimental period (ΔEt3=2.88). In Roth-811 Group, a statistically significant decrease in L* and a statistically significant increase in a* and b* chromatic parameters was measured, during all observation periods. Resultant ΔE values exceeded the human eye perceptibility threshold after 1 week (ΔEt1=5.65). CONCLUSIONS: Application of MTA Fillapex in tooth crowns resulted in minimal color alterations, while Roth 811 induced severe discoloration, in vitro. It could be suggested that, in terms of aesthetics, the use of MTA Fillapex appears to be favorable

Experimental designs and graphs

This dissertation presents a research on the construction of experimental designs, which is the first of the three objects of Statistics (according to R.A. Fisher, while the other two are Descriptive Statistics and Statistical Inference). In particular it is a study on the saturated D-optimal, s1 x s2 x s3 factorial plans of resolution III, i.e. designs of xperiments on three factors with any number of levels in each factor, that estimate the main effects of the levels of the factors using the criterion of the minimization of the generalized ariance and the minimal number of experimental units. Some properties of these designs are demonstrated, for any value of the parameters s1, s2,, s3. The upper bound of the value of the determinant of the information matrix for the 3xs2xs3 plan where s3>=s2+1, s2>=3 and the 3xs2 plan, where s>=3, is achieved and then some graph for which the determinant of the adjacency matrix attains the corresponding upper bound is constructed by the method of the ear construction. Finally the level combinations (treatments) of the factors for each one of the above optimal plans are given by the use of some appropriate labeled graph. The entire study where based on Combinatorial and Graph Theory methods (methods from the field of Discrete Mathematics), while it is worthy to mention that the computation of the value of the determinant of any matrix was done merely by additions and subtractions.H παρούσα διατριβή αποτελεί μια μελέτη επάνω στην κατασκευή πειραματικών σχεδιασμών (τον πρώτο από τους τρεις στόχους της επιστήμης της Στατιστικής R.A.Fisher). Συγκεκριμένα μελετώνται οι κορεσμένοι d-βέλτιστοι s1xs2xs3 παραγοντικοί σχεδιασμοί εκτιμητικής τάξης ΙΙΙ, δηλαδή σχέδια πειραμάτων στα οποία υπεισέρχονται τρεις παράγοντες με οποιοδήποτε πλήθος σταθμών και τα οποία έχουν ως στόχο την εκτίμηση των κυρίων επιδράσεων των σταθμών των παραγόντων ελαχιστοποιώντας τη γενικευμένη διασπορά και χρησιμοποιώντας το ελάχιστο πλήθος πειραματικών μονάδων. Παρουσιάζονται και αποδεικνύονται αρκετές ιδιότητες αυτών των σχεδιασμών για κάθε τιμή των παραμέτρων s1, s2,, s3. Αποδεικνύεται η τιμή του άνω φράγματος της ορίζουσας του πίνακα πληροφορίας για τις περιπτώσεις 3xs2xs3, s3>=s2+1, s2>=3 και 3xs2 για κάθε s>=3, ενώ στη συνέχεια κατασκευάζονται με τη μέθοδο της σύνθεσης με περιττά μονοπάτια (αυτιά) τα γραφήματα των οποίων η απόλυτη τιμή της ορίζουσας του πίνακα συνδέσεων πετυχαίνει τα αντίστοιχα προηγούμενα άνω φράγματα. Τέλος χρησιμοποιώντας σημασμένα γραφήματα δίνουμε τους συνδυασμούς των σταθμών των παραγόντων (αγωγές) που πρόκειται να συμπεριληφθούν κατά την εκτέλεση των αντίστοιχων βέλτιστων πειραμάτων για οποιεσδήποτε τιμές των παραμέτρων. Οι αποδεικτικές διαδικασίες που ακολουθούμε βασίζονται κυρίως σε μεθόδους της Θεωρίας των Γραφημάτων και γενικότερα των Διακριτών Μαθηματικών, ενώ χαρακτηριστικό της μελέτης είναι ότι ο υπολογισμός των οριζουσών των πινάκων στηρίζεται εξ’ ολοκλήρου στις πράξεις της πρόσθεσης και της αφαίρεση

The Effect of Wet Conditions and Surface Combat Swimming on Shooting.

INTRODUCTION: Shooting ability is an important aspect of performance in some sports and is vital during a military operation. Load carriage, clothing, and equipment normally associated with fatigue and reduced field of vision or lack of stability at a specific point are important factors that affect the ability to aim when shooting. Additionally, gun support and equipment appear to differentially affect shooting ability with varying shooting positions. All of the studies examining these factors have taken place on dry land and not in water. However, up to date, no study has examined the effect of wet conditions, especially after surface combat swimming (sCS), on shooting ability in different shooting positions. The purpose of this study was to determine the effect of fatigue, produced by prolonged sCS, on a fighter&apos;s shooting ability. In addition, we investigated whether the effect of fatigue and wet conditions differed between the shooting positions. MATERIALS AND METHODS: Forty-five participants performed 10 shots in a shooting simulator while standing (ST) and 10 shots while kneeling (KN). This was performed twice and in three conditions: dry, wet, and after 1,000 m of sCS. RESULTS: Wet conditions did not significantly affect shooting abilities. Surface combat swimming negatively affected shooting ability when both ST and KN. The reduction in the center of gravity (COG) of the shots after sCS was 3.7 ± 2.5\% for ST and 3.5 ± 0.8\% for KN (P {\textless} .01). This was accompanied by the increase in horizontal and vertical movement of the gun after the sCS (P {\textless} .01). Kneeling was more stable, as shown by a higher percentage of COG of the shots by 3.3 ± 0.1\% (P {\textless} .01) and by fewer gun movements in both axes (P {\textless} .01). CONCLUSIONS: In conclusion, combat swimming affects shooting ability, both in ST and in KN positions. The KN position provides better stability and improved shooting ability