Effect of interim cement application on bond strength between resin cements and dentin: Immediate and delayed dentin sealing.

STATEMENT OF PROBLEM: Despite the advances in materials and techniques, adhesion to dentin is challenging because of the complex composition of dentin's mineral, organic, and fluid phases. PURPOSE: The purpose of this in vitro study was to evaluate the bond strength of 2 different resin cements (conventional and self-adhesive) with or without previous dentin sealing and the effect of interim cement. MATERIAL AND METHODS: Forty-five molars were embedded into acrylic resin blocks and a flat dentin surface was exposed. Twenty teeth (n=5 per group) were treated with the conventional resin cement associated with etch-and-rinse or self-etch adhesive approaches, applied before (immediate dentin sealing) or after (delayed dentin sealing) the application/removal of interim cement. Another 25 teeth (n=5, per group) were treated with self-adhesive resin cement with (self-etch mode [immediate dentin sealing or delayed dentin sealing]) or without adhesive application. Furthermore, in the self-adhesive resin cement group, the application of polyacrylic acid for dentin etching before cementation was evaluated. Composite resin blocks were cemented onto flat, treated dentin surfaces, and the assemblies were sectioned into bar-shaped specimens for microtensile bond strength testing. The data were subjected to 1-way ANOVA followed by the post-hoc Tukey test (α=.05). The failure patterns were classified as cohesive, adhesive, or mixed. RESULTS: The application of adhesive before interim cement (immediate dental sealing) promoted the highest values of bond strength for both resin cements (P<.001). For self-adhesive resin cement, polyacrylic acid-enhanced bond strength after the application of interim cement. CONCLUSIONS: The application of dental adhesive immediately after tooth preparation (immediate dentin sealing) and before the use of an interim cement promoted the highest values of bond strength to dentin with the resin cements tested.

Influence of re-using reversible hydrocolloids on the linear alteration of coating models.

Reusing reversible hydrocolloids too many times may cause alterations of the coating model and produce unsatisfactory RPPs. The aim of this study was to analyze the linear alterations of coating models reproduced from molds obtained with two commercial brands of reversible hydrocolloid (RH) with 15 reuse cycles of the material. A metal model was used with 4 marks (A, B, C and D) on which the distances AB, BC, CD, DA, BD and AC could be measured lineally. Ten models were divided into two groups according commercial brand of RH: group VIPI-Duplicator VIPI and group K27--Duplicator K27l. The RH was heated in a microwave oven and poured into a flask containing the model. The mold was filled with the ethyl silicate coating, and after crystallization, refractory models were obtained. This was repeated in the 15 re-use cycles of each RH. The refractory models obtained from the 1st, 5th, 10th and 15th times of re-use of RHs were measured under a measuring microscope. The means were submitted to the Analysis of Variance, Tukey and Dunnet tests, to a 5% level of significance. Group VIPI showed linear alterations in relation to the plaster models, for distances AB (1 use = -1.25% and 5th re-use = -1.20%); AD (1st use = 0.76%, 10th re-use = 0.65% and 15th re-use = 0.52%); BD (1st use = 0.58%). Both commercial brands analyzed produced coating models with acceptable linear alterations in up to 15 reuse cycles, no statistical difference being observed between them.

Influence of different materials and techniques to transfer molding in multiple implants.

The aim of this study was to compare different materials and techniques used in transfer molding of multiple implants, by evaluating the space between implants and superstructure. Four external hexagon implants were fixed in a master template and the same on a superstructure. Transfer molding of implants were done using the direct and indirect techniques, with transfers united or not, using the union chemically activated acrylic resin (QA) and other groups polymerized acrylic resin (FT), and sectioned and not split. The casts were made with polyether and models divided into 8 groups (n = 5). The space between the superstructure and the master implants was measured with a microscope and the data was analyzed statistically by Student's t test (p < 0.05). For the material of union there was no significant difference, except when the groups were compared with the resin Duralay QA (G4) and the resin Duolay FT (G8) and groups using resins Duolay QA (G5) and Duolay FT (G7) for the union of the transfers. When comparing the groups who had the union between the transfers and sectioned again united with those in which the union was not severed there was no statistically significant difference. QA resin was superior to the FT with respect to the union of transfers. Techniques with united transfers or not were similar.

Traumatic fractures of the tympanic plate: a literature review and case report.

Fracture of the tympanic plate resulting from posterior dislocation of the mandibular condyle is an uncommon diagnosis. Presented is a clinical case in which computerized tomography was used as a diagnostic resource in a conservative therapeutic and clinical controlled one-year study. A review of the literature revealed 23 cases clinically reported with symptoms, diagnosis, and types of therapy utilized.

Valvoplastia mitral percutânea com a técnica do balão único. Resultados imediatos, complicaçoes e evolução intra-hospitalar / Percutaneous mitral valvuloplasty with the single balloon technique. Short-term results, complications and in-hospital follow-up

PURPOSE: To study the short-term results, complication and in-hospital follow-up of 268 percutaneous mitral balloon valvuloplasty (PMBV) procedures performed with the low-profile monofoil balloon (LPMB) technique from 1990 to 1995. METHODS: A single 30mm balloon diameter was used in 247 (92.9) procedures, a single 25mm balloon diameter in 9 (3.3), a single 25mm balloon followed by a single 30mm balloon diameter in 7 (2.6) and in 5 procedures a balloon was not used. The mean age group was 36 +/- 12 years. Two hundred nineteen (81.7) procedures were performed in women (mean age 36 +/- 12 years) and 49 (18.3) in men (mean age, 35 +/- 14 years) (p = 0.78). Patients were in functional class II (NYHA) in 39 (14.5), class III in 198 (73.9) and class IV in 31 (11.6). Patients were in sinus rhythm in 228 (85.1) procedures and in atrial fibrillation in 40 (14.9). The echocardiographic score ranged from 4 to 14 (mean 7.2 +/- 1.5). RESULTS: There were 256 complete procedures, 249 of which were successful (mitral valve area (MVA) > or = 1.5cm2 after PMBV). Echocardiographic calculated MVA before PMBV was 0.9 +/- 0.2cm2. Hemodynamic calculated MVA before PMBV was 0.9 +/- 0.2cm2 and after was 2.0 +/- 0.4cm2 (p < 0.000001). Mean pulmonary artery pressure decreased from 40 +/- 15mmHg to 28 +/- 10mmHg (p < 0.000001) and mitral mean gradient from 20 +/- 7mmHg to 5 +/- 4mmHg (p < 0.000001). In the 256 complete procedures mitral valve (MV) was competent in 214 and there was 1+ mitral regurgitation (MR) in 42. After PMBV, MV was competent in 166 and there was 1+ MR in 68, 2+ in 16, 3+ in 5 and 4+ MR in 1. There were complications in 14 (5.2) procedures, severe MR in 6 (3 or 4+), stroke in 2 and cardiac tamponade in 6. Two patients died during emergency cardiac surgery after left ventricular perforation and 1 after stroke. CONCLUSION: PMBV with the LPMB was an effective procedure with a high success rate and a low rate of complications as the more usual double-balloon and Inoue balloon techniques.