Biomedical subjects

Orlando Chevitarese

Publications and source records attributed to Orlando Chevitarese.

10 recordsLinked to original sources

PubMed2007

Effect of enamel etching on tensile bond strength of brackets bonded in vivo with a resin-reinforced glass ionomer cement.

OBJECTIVE: To evaluate the influence of enamel etching on tensile bond strength of orthodontic brackets bonded with resin-reinforced glass ionomer cement. MATERIALS AND METHODS: The sample group consisted of 15 patients who had indications for extraction of four premolars for orthodontic reasons, equally divided into two different groups according to bracket and enamel preparation. Brackets were bonded in vivo, by the same operator, using a split mouth random technique: Group 1 (control), phosphoric acid + Fuji Ortho LC; Group 2, Fuji Ortho LC without acid conditioning. The teeth were extracted after 4 weeks using elevators. An Instron Universal Testing Machine was used to apply a tensile force directly to the enamel-bracket interface at a speed of 0.5 mm/min. The groups were compared using a Mann-Whitney U-test and Weibull analysis. RESULTS: Mean results and standard deviations (in MPa) for the groups were: Group 1, 6.26 (3.21), Group 2, 6.52 (2.73). No significant difference was observed in the bond strengths of the two groups evaluated (P = .599). CONCLUSIONS: Fuji Ortho LC showed adequate shear bond strength and may be suitable for clinical use.

Acid Etching, Dental↗

PubMed2004

Diffusion of Ca(OH)2 associated with different vehicles: chromatographic study (high-performance liquid chromatography).

Using high-performance liquid chromatography (HPLC), small amounts of liquid samples in which 25 premolar human teeth were immersed were evaluated. Each tooth was immersed separately in 800-ml flasks with distilled ultra-pure deionized water and remained there for 1678 h after the filling of their canals with Ca(OH)2 associated with different vehicles: group 1: polyethylene glycol and colophon (Calen); group 2: glycerin and camphorated paramonochlorophenol; group 3: camphorated paramonochlorophenol; group 4: glycerin and tricresol formol; and group 5: anesthetic solution (Citanest). Five polyethylene tubes were filled with each of these pastes and placed unsealed in similar flasks. At the end of this period, HPLC analyses of the aqueous medium related to each group were performed to detect other substances that had diffused from the pastes used in the canals of the teeth other than calcium and hydroxyl ions. Although the groups presented different maximum peaks when there was no barrier, they all showed higher values than when the tooth was present. At least 15 substances other than Ca2+ and OH- were detected in the aqueous medium of group 4. Analyzing the HPLC graphs, we concluded that not only Ca2+ and OH-, but also a considerable quantity of other components of the pastes diffused through the dentine and reached the external root surface.

Anesthetics, Local↗

PubMed2004

Titanium penetration in human enamel after TiF4 application.

The TiF4 application produces a titanium coating on enamel surface, reducing solubility in presence of cariogenic challenge. However, it is not established if this titanium also penetrates inside the enamel. The aim of this study was to evaluate in vitro the presence of this superficial coat and titanium penetration into human sound and decayed enamel after TiF4 application. Twenty-four unerupted third molars were mesiodistally cut and divided into two groups (GA--sound and GB--artificial decayed). After a 4% TiF4 application, each sample was fractured longitudinally (occlusal-cervical). Through microprobe analysis with energy dispersive spectrometer (EDS), titanium penetration could be observed inside the enamel. The McNemar test (p=0.267) showed that there was no difference between the groups analyzed regarding to titanium penetration, although in group A the titanium penetrated more deeply (Wilcoxon test, p=0.047). It could be concluded that there was no difference between the groups regarding the titanium penetration, but titanium penetrated more deeply into sound enamel compared to artificially decayed enamel.

Cariostatic Agents↗

PubMed2003

Influence on pH of vehicle containing glycerin used with calcium hydroxide.

- The pH values of the external aqueous medium, relative to the roots of 41 human premolar teeth filled with Ca(OH)2 in to several vehicles, were evaluated in the present study. After root canal biomechanical preparation and smear-layer removal, the teeth were stored individually, immersed in flasks containing 800 ml of ultra-pure deionized water for a period of 118 days. A pH meter was used to analyse the pH values as a function of time. The measurements were divided into phase 1: dissolution, in which all canals remained empty and open in the absence of medicament for 48 days, and phase 2: diffusion, in which the specimens were divided into 10 groups which consisted of three control groups: group 1, water control; group 2, sealing control; and group 3, opened canal dissolution control, and seven experimental groups, with five teeth each, whose canals were filled with Ca(OH)2 paste associated with the following vehicles: group 4, saline solution; group 5, polyethylene glycol (Calen); group 6, glycerin and parachlorophenol (PMCC); group 7, PMCC; group 8, glycerin; group 9, glycerin and formo cresol (FC); and group 10, anesthetic solution. This phase lasted for 70 days. A total of 1058 measurements of the pH values were made. Regression analysis was used for statistical evaluation. The results show that all groups containing polyol in the composition of the paste had a trend to acidification in the interval between filling and 14 days later (therapeutic period) and, at the end of the experiment (1687 h to 70 days after canal filling), the pH was slightly alkaline. We conclude that polyhydroxy alcohol (glycerin and polyethylene glycol, Calen) diffusion enhances acidification of the aqueous medium.

Calcium Hydroxide↗

PubMed2003

Ca2+ diffusion through dentin of Ca(OH)2 associated with seven different vehicles.

This investigation measured the diffusion of Ca2+ through dentin by using Ca(OH)2 associated with various vehicles. After mechanical preparation and removal of smear layer, 41 human premolar teeth were stored individually in flasks containing 800 ml of ultra-pure deionized water for 2855 h. The Ca2+ concentration was measured by atomic absorption spectrophotometry as a function of time. These measurements were divided into two phases: dissolution, to check the loss of Ca2+ from the tooth structure itself, for which all canals were kept empty and open in the absence of medication for 1168 h, and diffusion, in which the specimens were divided into 10 groups (3 control groups: group 1 = water control, group 2 = sealing control, and group 3 = open canal dissolution control; 7 experimental groups in which the whose canals were filled with Ca(OH)2 paste associated with the following vehicles: group 4 = saline; group 5 = polyethylene glycol (Calen); group 6 = glycerin and camphorated parachlorophenol group 7 = camphorated paramonochlorophenol; group 8 = glycerin; group 9 = glycerin and tricresol formaldehyde (TCF); and group 10 = anesthetic solution. This phase lasted 1687 h. A total of 1058 measurements of Ca2+ were made. Regression analysis was used for statistical evaluation. We concluded that diffusion occurred differently for each group: the medications used in the root canals interacted with the dentinal structure or among themselves; the medication coated the dentinal tubule, facilitating the diffusion of Ca2+ into the external part of the root.

Anesthetics, Local↗

PubMed2003

A comparative study of dentin thickness of primary human molars.

The aim of the present survey was to evaluate the dentin thickness of buccal, lingual, mesial and distal surfaces of first and second primary molars. These evaluations were done at the middle third of the crowns of twenty extracted non-carious primary teeth separated in two groups (first molars and second molars). Comparisons were performed within-groups and between-groups. The mean values of dentin thickness observed for first molars were 2430 mm (buccal), 1.869 mm (lingual), 1.655 mm (mesial) and 1.664 mm (distal). For second molars the dentin thickness presented 3.006 mm (buccal), 2730 mm (lingual), 2130 mm (mesial) and 2192 mm (distal). The dentin thickness was higher in the buccal surface in both groups (P<0.05; Wilcoxon Test), except for the lingual surface of second molars (P>0.05). No differences were observed between mesial and distal surfaces in both groups (P>0.05). Comparisons between-groups showed that the dentin thickness was higher in all surfaces of second molars (P<0.01; Mann-Whitney Test). It was concluded that there are differences in the dentin thickness between first and second primary human molars and within the different surfaces of such teeth.

Child↗

PubMed2002

Bonding brackets to porcelain--in vitro study.

The aim of this research was to verify, in vitro, the effect of various porcelain surface treatment on the shear strength of orthodontic brackets bonded to porcelain and the mode of fracture after debonding. Eighty-eight samples of metallic supported feldspathic porcelain were randomly divided into four groups according to their surface preparation as follows: the porcelain was maintained intact (GI), roughened with a diamond bur (GII), etched with 10% hydrofluoric acid (GIII), or sandblasted with aluminum oxide (GIV). The specimens were treated with silane (Scotchprime) and brackets were bonded with Concise. Each sample was subjected to a shear load at a crosshead speed of 1 mm/min and a recording was made at the point of failure. Bond strengths, adequate to withstand the application of orthodontic forces, were achieved in all groups. The Kruskal-Wallis statistical test showed no significant differences in bond strength between the groups (p > 0.05). However, many more porcelain fractures occurred on deglazed porcelain. This study indicates that with the appropriate material selection, the silane/composite procedure alone may be adequate for bonding.

Acid Etching, Dental↗

PubMed2002

Density and diameter of dentinal tubules of first and second primary human molars--comparative scanning electron microscopy study.

The aim of the present survey was to evaluate tubule density and diameter of dentin of first and second primary human molars and compare the two dental categories. These evaluations were done solely at the middle third of the crowns of twenty extracted noncarious teeth separated in two groups (first molars and second molars). The tubule diameters observed were 0. 794 microm and 1.0 microm for first and second molars, respectively (measurements done at 35-65% from the pulp-chamber walls). Regarding tubular density, the measurements indicated 17,997.594 tubules/mm2 and 25,211.317 tubules/mm2 for first and second molars, respectively. Comparisons between-groups indicated that tubule diameter and density of dentin were higher in second molars, being the difference highly significant (P<0.01).

Child↗

PubMed2002

Influence of prophylaxis on the microleakage of sealants: in vitro study.

The aim of this study was to evaluate the influence of prophylaxis on the sealants microleakage in 30 premolars divided into: Group A, Group B and Group C. The teeth were analyzed using the optical microscope (OM) and at scanning electron microscope (SEM). There was a statistical significant difference among the groups regarding the presence of microleakage, but not with the presence of tags.

Acid Etching, Dental↗

PubMedDate not supplied

Effects of a glass-ionomer cement on the remineralization of occlusal caries--an in situ study.

This work evaluated the remineralization of demineralized enamel of pits and fissures of human third molars sealed with a glass ionomer cement (Fuji IX, GC Corporation--Japan) or with a Bis-GMA sealant (Delton--Dentsply). Ten volunteers participated in this in situ study that consisted of two thirty-day periods using intra-oral devices, with a weeks interval in between. Four experimental treatment procedures and one control were randomly assigned to the volunteers specimens: Group I, no treatment, control; Group II, artificial caries process; Group III, same treatment as Group II, but sealed with Delton (Dentsply); Group IV, same treatment as Group II, but sealed with Fuji IX (GC Corporation--Japan); Group V, same treatment as Group II and no sealing. Groups I and II were not submitted to the oral environment and served as controls. After a period of 30 days in the oral environment, the specimens were removed from the devices, embedded in acrylic resin, ground flat and polished. Then, Knoop hardness tests were performed, with a 25 g static load applied for 15 seconds. The measurements were made from the base of the fissure up to an opening of 600 microm, pre-established between the inclines of the cusps. Three indentations were then made, located at 25, 75, and 125 microm in depth from the outer enamel margin and 100 microm apart from each other (Micromet 2003). The Brieger F and Bonferronis tests were applied to the measurements. It was concluded that sealing with the glass ionomer cement Fuji IX was capable of making the enamel of pits and fissures more resistant by increasing the value of Knoop hardness.

Bisphenol A-Glycidyl Methacrylate↗