Biocompatibility of various root canal filling materials ex vivo

Aim  To evaluate the biocompatibility of a resin-based endodontic filler (RealSeal) using the indirect cytotoxicity test.
Methodology  Human gingival fibroblasts were cultured ex vivo . Pellets of the materials to be tested were incubated for 24, 48, and 72 h at 37 °C under sterile conditions to obtain their eluates. The fibroblasts were exposed to either diluted (50%) or undiluted eluates for 24 h. A culture medium with foetal calf serum was added to the control wells. Cell viability was estimated by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide method. The data concerning cell viability were statistically analyzed using one-way anova test and Bonferroni multiple comparisons test.
Results  Eluates obtained after 24 h of incubation with the resin filler did not reduce cellular viability. An increase in cellular viability, as compared with control cells, was observed in the gutta-percha group. The undiluted eluate from the polyether material was cytotoxic, causing an 82 ± 4% decrease in cellular viability. Eluates obtained after 48 h of incubation with the resin filler increased cellular viability, whereas the polyether significantly reduced viability. Gutta-percha did not cause any detectable change. After 72 h of incubation the eluate of the resin filler caused an increase in cellular viability, as did gutta-percha, whereas polyether caused a significant decrease.
Conclusions  RealSeal resin filler was nontoxic in this laboratory model. Further investigations are necessary to verify its usefulness in clinical applications.     

A radiologic method for determining the thickness of the hard crown tissues

This study describes a radiologic method that provides a reliable evaluation of the thickness of the hard crown tissues of the tooth scheduled for prosthetic and conservative preparation. The first stage consisted of calculating the discrepancy between the actual dimensions of the specimen under examination and the dimensions of the same specimen as measured and radiographed. Some coefficients of distortion were calculated for the distance(s) more usually involved clinically. Radiographs were made by using the "paralleling" technique. In the second stage, radiographs were made of 83 extracted teeth (22 incisors, 12 canines, and 51 premolars). On the resulting radiographs some prefixed distances were measured. Finally, to gain an anatomic comparison of the values obtained radiologically, 24 of the previously radiographed teeth were sectioned along the sagittal plane at the diameter, and measurements were made and compared with the radiologic data to which the correction coefficients had been applied.     

Statistical study of the angle formed by the lateral part of the mandibular condyle and the horizontal plane

The angle between the LCA and frontal plane and the inclination of the lateral part of the mandibular condyle and the horizontal plane were measured in a sample of the skulls used in the study. Correlation between the two angles was found to be almost insignificant. Fifty-eight percent of the TMJs had an inclination of the lateral part of the condyle less than 15 degrees. The maximum value for this angle was found to be 45 degrees, and the minimum was -6 degrees.     

Bond strength of a resin cement to high-alumina and zirconia-reinforced ceramics: the effect of surface conditioning

PURPOSE: The aim of this study was to evaluate the effect of two surface conditioning methods on the microtensile bond strength of a resin cement to three high-strength core ceramics: high alumina-based (In-Ceram Alumina, Procera AllCeram) and zirconia-reinforced alumina-based (In-Ceram Zirconia) ceramics. MATERIALS AND METHODS: Ten blocks (5 x 6 x 8 mm) of In-Ceram Alumina (AL), In-Ceram Zirconia (ZR), and Procera (PR) ceramics were fabricated according to each manufacturer's instructions and duplicated in composite. The specimens were assigned to one of the two following treatment conditions: (1) airborne particle abrasion with 110-microm Al2O3 particles + silanization, (2) silica coating with 30 microm SiOx particles (CoJet, 3M ESPE) + silanization. Each ceramic block was duplicated in composite resin (W3D-Master, Wilcos, Petrópolis, RJ, Brazil) using a mold made out of silicon impression material. Composite resin layers were incrementally condensed into the mold to fill up the mold and each layer was light polymerized for 40 s. The composite blocks were bonded to the surface-conditioned ceramic blocks using a resin cement system (Panavia F, Kuraray, Okayama, Japan). One composite resin block was fabricated for each ceramic block. The ceramic-composite was stored at 37 degrees C in distilled water for 7 days prior to bond tests. The blocks were cut under water cooling to produce bar specimens (n = 30) with a bonding area of approximately 0.6 mm2. The bond strength tests were performed in a universal testing machine (crosshead speed: 1 mm/min). Bond strength values were statistically analyzed using two-way ANOVA and Tukey's test (< or = 0.05). RESULTS: Silica coating with silanization increased the bond strength significantly for all three high-strength ceramics (18.5 to 31.2 MPa) compared to that of airborne particle abrasion with 110-microm Al2O3 (12.7-17.3 MPa) (ANOVA, p < 0.05). PR exhibited the lowest bond strengths after both Al2O3 and silica coating (12.7 and 18.5 MPa, respectively). CONCLUSION: Conditioning the high-strength ceramic surfaces with silica coating and silanization provided higher bond strengths of the resin cement than with airborne particle abrasion with 110-microm Al2O3 and silanization.     

Prosthetic rehabilitation of a child affected from anhydrotic ectodermal dysplasia: a case report

The aim of this clinical report is to describe the management of a young patient, affected by ectodermal dysplasia, during a nine-year period. Dental treatment can vary depending on the severity of the disease (tooth size, morphology, and amount of available alveolar bone). New technologies, such as adhesive dentistry, and new materials, such as composite resin, represent current options in the management of the dental rehabilitation of patients affected by ectodermal dysplasia. Removable partial dentures were used to replace congenitally missing teeth, and composite resin materials were used to restore conical-shaped maxillary teeth to achieve a favorable esthetic result. This option minimized the sacrifice of healthy dental tissue. Prosthodontic and restorative treatment was provided for the psychological and social comfort of the young patient.     

Effect of post length on the fatigue resistance of bovine teeth restored with bonded fiber posts: a pilot study

This study evaluated the influence of the cementation length of glass fiber-reinforced composite (FRC) on the fatigue resistance of bovine teeth restored with an adhesively cemented FRC. Thirty roots of single-rooted bovine teeth were allocated to 3 groups (n = 10), according to the ratio of crown length/root length (post cementation length): group 1 = 2/3, group 2 = 1/2, and group 3 = 1/1. The roots were prepared, the fiber posts (FRC Postec Plus) were cemented, and the specimens were submitted to 2 million mechanical cycles. After fatigue testing, a score was given based on the number of fatigue cycles until fracture, and data were submitted to statistical analysis. All specimens were resistant to fatigue. Taking into account the methodology and results of this study, the evaluated fiber posts can be cemented based on the ratio of crown/root at 1/1. Further clinical studies must be conducted to verify this ratio.     

Influence of preparation design and spacing parameters on the risk of chipping of crowns made with Cerec Bluecam before cementation

Purpose

To evaluate the influence of the preparation design and spacing parameters on the risk of chipping of crowns made by CEREC Bluecam before cementation.

Intravenous use of tranexamic acid reduces postoperative blood loss in total knee arthroplasty

Introduction

Blood transfusion is often required in total knee replacement (TKR); several methods of blood preservation are commonly used but the ideal solution is to reduce the blood loss during and after surgery. Aim of the study was to evaluate the hemostatic efficacy and safety of intravenous use of tranexamic acid in patients receiving TKR (cemented).

Materials and methods

Forty-five patients after TKR receive treatment with tranexamic acid (TXA, treatment group), and 45 were managed with fibrin tissue adhesive (control group). Hemoglobin values decrease and transfusions in both groups were recorded. Statistical analysis was performed with Student t test and χ ² test. A statistical model was elaborated to evaluate together all variables and to underline what data can increase transfusions need.

Results

A significant reduction was detected in hemoglobin values in the first 3 days after surgery in the treatment group. The difference in all cases was significant. When tranexamic acid was administered, the need for transfusions was lower (difference statistically significant). No major adverse events were recorded in our series. The use of autologous blood preparation before surgery led to a higher transfusion rate.

Conclusion

Tranexamic acid reduced blood loss in TKR and significantly reduced the blood transfusion need also when compared to fibrin tissue adhesive. The use of tranexamic acid is safe and in future may avoid preparation of autologous blood unit before surgery with a decrease of cost and medical figures involved.     

In vitro antimicrobial activity of a new antibiotic, MDL 62,879 (GE2270 A).

MDL 62,879 (GE2270 A) is a new peptide antibiotic that inhibits protein synthesis through an interaction with elongation factor Tu. MDL 62,879 was very active against gram-positive clinical isolates, particularly staphylococci and enterococci, for which MICs for 90% of isolates were < or = 0.13 micrograms/ml. It was equally active against isolates resistant to beta-lactams, erythromycin, gentamicin, and glycopeptides. It also had activity against Mycobacterium tuberculosis. MDL 62,879 had moderate bactericidal activity against staphylococci.