Biomedical subjects

S González-López

Publications and source records attributed to S González-López.

5 recordsLinked to original sources

PubMed2006

Effect of CHX on the decalcifying effect of 10% citric acid, 20% citric acid, or 17% EDTA.

The objective of this study was to measure the demineralization capacity of 10% and 20% citric acid and 17% EDTA after three time periods and to determine whether it was modified by the addition of 1% of commercial chlorhexidine (CHX). Three slices of 2-mm thickness were cut from the cervical third of the root of ten bovine incisors and sectioned into two equal parts, obtaining six specimens per tooth. Specimens were assigned to one of six groups (n = 10) for immersion in 25 ml of the above mentioned solutions or 25 ml of these same solutions plus 1% CHX (Hibimax). At 3, 10, and 15 min of immersion, the concentration of Ca2+ was measured by atomic absorption spectrophometry. The demineralization effect of all solutions was time-dependent (F = 158,448; p < 0.001), without significant differences among them (p = 0.783). Addition of 1% CHX did not modify the demineralizing capacity of these solutions. In the first three minutes, significantly more [Ca2+] was obtained when 17% EDTA was used in comparison with the other solutions.

Animals↗

PubMed2004

Decalcification of root canal dentine by citric acid, EDTA and sodium citrate.

AIM: To measure the demineralization capability of 1 and 10% citric acid, 10% sodium citrate and 17% EDTA during immersions of 5, 10 and 15 min on root canal dentine. METHODOLOGY: Crowns were sectioned from eight maxillary canines. The cementum was removed from the cervical third of the roots to expose the dentine. Canals were prepared using a handpiece-mounted Largo Peeso reamer. A 3-mm thick cross-sectional slice was obtained from the cervical third of each root. Each slice was sectioned into four equal parts. These specimens were assigned to one of four groups (n = 8) for the application of 1% citric acid, 10% citric acid, 10% sodium citrate or 17% EDTA. Each specimen underwent three successive 5-min immersions in each solution at room temperature. The solutions were not renewed between immersions. Two millimetres of solution were collected from the extracts and lanthanum oxide was added for the calcium reading by spectrophotometry. To compare the amounts of calcium removed by each solution, the Friedman test was used for the global comparison and the Wilcoxon test for paired comparisons. Differences between groups were evaluated using the Kruskal-Wallis test for the global comparison and Mann-Whitney test for paired comparisons. RESULTS: Overall, 1 and 10% citric acid were more effective than EDTA or sodium citrate at the three immersion times (P < 0.001); 10% citric acid was more effective than 1% citric acid (P < 0.001). EDTA and 1 and 10% citric acid showed decreasing effectiveness with time, and the decrease was significant for citric acid at both concentrations (P < 0.001). Although sodium citrate removed little calcium during the three time periods, the small increase recorded was significant (P < 0.01). CONCLUSIONS: Citric acid at 10% was the most effective decalcifying agent, followed by 1% citric acid, 17% EDTA and 10% sodium citrate.

Calcium↗

PubMed2001

The effect of various surface treatments and bonding agents on the repaired strength of heat-treated composites.

STATEMENT OF PROBLEM: Some clinical situations may require the repair of a secondary polymerized or aged composite. The higher indirect resin conversion rate may prove to be a disadvantage if a repair procedure based on covalent bonding from unreacted methacrylate groups is attempted. PURPOSE: This study evaluated the effectiveness of different combinations of surface treatments and 2 bonding agents used to enhance heat-polymerized and aged composite repairs. MATERIAL AND METHODS: Ninety Herculite XRV and 90 Heliomolar Radiopaque specimens were prepared and then postpolymerized and stored for 4 weeks. All composites were subjected to 1 of 9 treatment regimens that involved adding fresh composite onto a corresponding postpolymerized composite (Herculite/Herculite or Heliomolar/Heliomolar). The surfaces were treated with different combinations of air abrasion, phosphoric acid, hydrofluoric acid, acetone, Special Bond II, Heliobond, and Prime & Bond 2.0. RESULTS: Surface treatment with air abrasion resulted in the strongest repairs; surface treatment with phosphoric acid resulted in the weakest repairs. CONCLUSION: The use of air abrasion and Prime & Bond 2.0 adhesive consistently improved the shear bond strength for both composites tested.

Acetone↗

PubMedDate not supplied

Individualized wedge.

The preparation of an individualized wedge in the gingival embrasure before cavity preparation using photo-cured resin permits rehabilitation of the interproximal space and the original contact point position. Because the individualized wedge completely fills the embrasure, the adaptation to the gingival and proximal walls of the molar to be restored is perfect, avoiding any overextension of obturation material during insertion. Furthermore, the original position of the contact point is preserved.

Composite Resins↗

PubMedDate not supplied

Influence of different composite restoration techniques on cuspal deflection: an in vitro study.

Cuspal deflection produced by polymerization shrinkage was measured after using different composite restoration techniques. This study included 30 healthy premolars embedded in acrylic resin connected to a system that simulated intrapulpal pressure. A small ball was attached to each cuspal vertex as a reference point for intercuspal distance measurements. A large mesio-occlusal cavity was cut in each premolar. All premolars were treated with the same adhesive (ScotchBond) and composite (Tetric Ceram). The teeth were randomly distributed among three study groups: Group 1, filled with two horizontal increments; Group 2, filled with two horizontal increments, the first up to half the cavity height and light cured using a transparent plastic cone (Cerana), and the second filling the remainder of the cavity and Group 3, filled in the same way as Group 2, except that the first increment only filled one-third of the cavity height. The intercuspal distance was measured before beginning the restoration and immediately after polymerization of the first and second increments. Under the experimental conditions used, none of the filling techniques utilized avoided the cuspal deflection phenomenon. Polymerization of the final increment, which binds occlusal enamel in the buccal-lingual plane, was the main cause of cuspal deflection and produced a statistically significant reduction in intercuspal distance vs the baseline measurement in the three study groups. The global deflection ranged from 4 microm to 6 microm, depending on the filling technique used, although the differences among techniques did not reach statistical significance (p<0.05).

Composite Resins↗