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Biomedical subjects

R Osorio

Publications and source records attributed to R Osorio.

13 recordsLinked to original sources
PubMed1999

Bracket bonding with 15- or 60-second etching and adhesive remaining on enamel after debonding.

The purposes of this study were to (1) evaluate the shear bond strength of brackets fixed to enamel that has been etched for 15 or 60 seconds, (2) correlate etch time with amount of resin remaining on the enamel after debonding; and (3) evaluate enamel morphology after acid etching. Sixty recently extracted human premolars were randomly divided into two groups. Group 1 was etched for 15 seconds, and group 2 for 60 seconds. A 37% phosphoric acid solution was used for etching. The brackets were Mini-Taurus, and the bonding system was Mono-Lok2. After bonding, the teeth were held at 37 degrees C and 100% humidity for at least 48 hours. To debond, a blade was placed at the ligature groove of the bracket. The force in Newtons required to dislodge the bracket was measured, employing a crosshead speed of 1 mm/min. Bond strength was calculated on the basis of bracket area. Immediately after removal of the bracket, the teeth were rinsed and dried using an air-water syringe, and the adhesive remnant index (ARI) was assessed. Enamel surfaces were analyzed using a scanning electron microscope (SEM). The results showed that shear bond strength was greater (p=0.016) when the enamel was etched for 60 seconds, and the amount of adhesive remaining on the teeth was also greater (p=0.001). There was no significant correlation between shear bond strength and the ARI calculated in the total sample (n=60, r=0.017; p>0.05). SEM evaluation revealed that the shorter etching time created a less retentive enamel surface. Absolute enamel loss also decreased.

Acid Etching, Dental↗
PubMed1996

Influence of enamel prophylaxis on wettability of three commercially available orthophosphoric acids.

An in vitro study was performed to assess the wettability of orthophosphoric acid after different procedures for cleaning the enamel surface. Ninety noncarious third molars were randomly distributed into three groups with different enamel surface treatments: an air-powder polisher unit, prophylaxis pastes, and no enamel surface cleaning. Three commercially available orthophosphoric acids were used, and there were 10 teeth in each group. Acid viscosity values and contact-angle measurements were obtained. Each enamel surface was also examined with the scanning electron microscope. Results suggested that the surface treatment with which the best spreading of the acid solution was attained was the air-powder polisher. The least spreading of the acid was obtained with prophylaxis pastes, in which contact angles were even higher than those obtained on the untreated enamel surface. The 3M acid solution was the one that showed the best spreading onto the enamel surface.

Acid Etching, Dental↗
PubMed1996

An in vitro comparison of micro leakage in three glass ionomer cements used as retrograde filling materials.

The aim of this study was to evaluate the sealing ability of conventional self-cured glass ionomer cement, silver glass ionomer cement and light-cured glass ionomer cement as retrofilling materials. Micro-leakage was assessed by introducing the samples into a 1 per cent solution of methylene blue for eight days at a constant temperature of 37 degrees C. Dye penetration was greater when silver glass ionomer cement was used in comparison to the other two materials tested; the difference was statistically significant. Conversely, the sealing ability of light-cured glass ionomer cement was significantly higher than that of conventional glass ionomer cement. The condition of the dentine-filling material interface and the marginal adaptation of the glass ionomer cements under study were assessed using scanning electron microscopy.

Cermet Cements↗
PubMed1995

Posttransplantation lymphoproliferative disorder in patients under primary tacrolimus (FK 506) immunosuppression.

Posttransplantation lymphoproliferative disorder (PTLD) is a well-described complication of the systemic immunosuppression required for successful organ transplantation. Lesions of PTLD often occur in the region of the head and neck and require otolaryngologic evaluations. Although the majority of reported cases of PTLD are associated with cyclosporine immunosuppression, recently, PTLD has been described in patients treated solely with the newer systemic immunosuppressive agent tacrolimus (FK 506). As an introduction to tacrolimus and to PTLD as one of its complications, a case of PTLD presenting as airway obstruction in a child treated solely with tacrolimus immunosuppression is described. In addition, a review of tacrolimus and PTLD in patients under tacrolimus immunosuppression is presented to familiarize the otolaryngologist with this important new immunosuppressive agent and a potential complication of its use.

Female↗
PubMed1995

Short-term changes in lymphocytes after placement of silver amalgam restorations in healthy subjects.

OBJECTIVES: The purpose of this study was to evaluate the changes in lymphocyte subpopulations that have led to immune system alterations after amalgam restorations were placed. METHODS: A controlled, quasi-experimental pretest-posttest design was used to investigate the immune effects of silver amalgam restorations in a sample of 60 individuals (30 experimental and 30 control subjects) aged 18 to 21 y. Two blood samples were obtained 15 d apart from each participant. In each experimental subject, two amalgam restorations were placed in posterior teeth immediately after the first blood sample was collected. The changes in lymphocyte subpopulations in the two groups were compared by multivariate analysis. RESULTS: There was a greater change in T8 lymphocytes in experimental than in control subjects; increases in B, DR, NK, and CD45R lymphocytes were smaller in experimental than in control subjects; the changes in T3 and T4 lymphocytes did not differ significantly between the two groups. SIGNIFICANCE: Despite the statistical significance of some differences between the two groups, the differences are not considered to be clinically relevant for the 2 wk time period after placement.

B-Lymphocytes↗
PubMed1995

Environmental microbial contamination. Pilot study in a dental surgery.

Environmental contamination by bacterial aerosols occurs every day in the dental surgery. The aim of this study was to determine bacterial levels in five different areas of a dental surgery during ultrasonic scaling procedures using bacterial cultures. Two areas with markedly different amounts of infective aerosols were identified. The role of the air conditioning system was also assessed. There was evidence that the air conditioning system could act as a vehicle for the transmission of microorganisms.

Aerosols↗
PubMed1993

Modulation of LH secretion by progesterone and estradiol after naloxone injection in the median eminence.

To evaluate whether the median eminence (ME) is a site of action of opioids on gonadotropin secretion, and to determinate the role of estradiol (E) and progesterone (P) in modifying these secretion in response to naloxone, we injected naloxone (1, 2.5 and 5 micrograms) into the ME in ovariectomized rats treated with estradiol benzoate (OVX+E) or ovariectomized rats treated with estradiol benzoate plus progesterone (OVX+E+P), and measured LH and FSH serum levels 10 and 30 min postinjection. Naloxone injection at doses of 2.5 and 5 micrograms significantly increased serum LH levels in OVX+E animals 10 and 30 min postinjection, whereas naloxone injection at all doses in OVX+E+P rats did not have any significant effect on LH secretion 10 and 30 min postinjection, when compared with values obtained in controls injected with saline. The injection of naloxone into the ME did not modify FSH secretion. We conclude that naloxone, acting within the ME, can elicit LH release in OVX+E rats, while it abolishes this effect in OVX+E+P rats.

Animals↗
PubMed1990

[Visual activity in dental treatment].

We've done an analitical study in 60 dental clinics about their illuminating systems in clinical and no clinical areas. We propose ideal values for light intensity in oral and ambiental illumination in clinical areas. Following these instructions you'll get: An increasing in productivity and rentability due to a bigger comfort in your working areas. To decrease the visual fatigue for you and your dental assistants.

Dental Offices↗
PubMedDate not supplied

Enamel surface morphology after bracket debonding.

The purpose of this study was to evaluate the shear bond strength of brackets and the enamel morphology after using six methods for removal of adhesive after bracket debonding. A total of thirty-five recently extracted noncarious human premolars were used. The twin bracket Mini-Taurus was used with the Mono-Lok2 TM bonding system. Shear bond strength (MPa) was calculated. Immediately after the brackets were removed, the teeth were rinsed and dried, using an air-water syringe. The adhesive remnant index was calculated and the debonded teeth with residual adhesive material attached to the enamel surface were equally sorted in seven groups of five, as follows: Group 1. The residual adhesive was removed with a 12-blade tungsten carbide finishing bur in a high-speed handpiece, using water as the coolant. Group 2. The residual adhesive was removed with a 12-blade tungsten carbide finishing bur in a low-speed handpiece, using water as the coolant. Group 3. The residual adhesive was removed with an Arkansas stone: Dura-white stones for finishing composite in a high-speed handpiece using water as the coolant. Group 4. The residual adhesive was removed with an Arkansas stone: Dura-white stones for finishing composite in a low-speed handpiece, using water as the coolant. Group 5. The residual adhesive was removed with Sof-Lex aluminum oxide discs according to manufacturer's instructions in a low-speed handpiece, using water as the coolant. Group 6. The residual adhesive was removed with Enhance Composite Finishing Discs in a low-speed handpiece, using water as the coolant. In this group, the paste was not applied after the polishing discs. Group 7. The residual adhesive was removed with Enhance Composite Finishing Discs and Polishing Cups in a low-speed handpiece, using water as the coolant. Prisma-gloss polishing paste and ultrafine polishing paste were applied according to manufacturer's instructions. After removal of the adhesive, all teeth were evaluated with the scanning electron microscope. The results revealed a mean shear bond strength of 12.75 MPa. The higher the bond strength, the higher the percentage of ARI. The smoothest enamel surface was obtained when the Enhance system with the gloss polishing paste was used; the second smoothest enamel surface was obtained when using Sof-Lex discs. If the paste was not used with the Enhance system, the obtained surface was rougher than when using Sof-Lex discs.

Adhesives↗