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ScienceDaily — A group of University of Southern California School of Dentistry researchers says it has identified the slimy culprits killing the jawbones of some people taking drugs that treat osteoporosis
dentist | Shear Bond Strength of Self-etch Adhesives to Enamel with Additional Phosphoric Acid Etching
Clinical Relevance
When using self-etch adhesives to bond composite materials to enamel, there is concern about the ability to achieve bond strengths comparable to approved etch-and-rinse systems. An additional phosphoric acid etching can improve the shear bond strength of self-etch adhesives to enamel
SUMMARY:
This study evaluated the shear bond strength of self-etch adhesives to enamel and the effect of additional phosphoric acid etching
Seventy sound human molars were randomly divided into three test groups and one control group. The enamel surfaces of the control group (n=10) were treated with Syntac Classic (SC). Each test group was subdivided into two groups (each n=10). In half of each test group, ground enamel surfaces were coated with the self-etch adhesives AdheSe (ADH), Xeno III (XE) or Futurabond NR (FNR). In the remaining half of each test group, an additional phosphoric acid etching of the enamel surface was performed prior to applying the adhesives. The shear bond strength was measured with a universal testing machine at a crosshead speed of 1 mm/minute after storing the samples in distilled water at 37°C for 24 hours. Fracture modes were determined by SEM examination. For statistical analysis, one-way ANOVA and the two-sided Dunnett Test were used (p>0.05
Additional phosphoric etching significantly increased the shear bond strength of all the examined self-etch adhesives (p<0.001). The highest shear bond strength was found for FNR after phosphoric acid etching. Without phosphoric acid etching, only FNR showed no significant differences compared to the control
SEM evaluations showed mostly adhesive fractures. For all the self-etch adhesives, a slight increase in mixed fractures occurred after conditioning with phosphoric acid
An additional phosphoric acid etching of enamel should be considered when using self-etch adhesives. More clinical studies are needed to evaluate the long-term success of the examined adhesives
dentist | Clinical Relevance
The use of light-activation sources did not affect the outcome of in-office bleaching with 35% hydrogen peroxide
This study clinically evaluated the alteration of color, color stability, dental sensitivity and gingival irritation on patients undergoing dental bleaching using varying bleaching methods and light-activation sources. According to pre-established criteria, 40 patients were selected and randomly divided into four groups (n=10): Group 1-35% Hydrogen Peroxide (HP); Group 2-35% HP plus Halogen Curing Light XL 3000 (3M/ESPE); Group 3-35% HP plus Demetron LED (Kerr) and Group 4-35% HP plus LED/LASER Curing Units (Bio-art). For all groups, there were two sessions of bleaching with 35% HP, with a one week break between sessions. At each bleaching session, three applications of the bleaching gel were used. Two methods of shade evaluation were performed before and after the first week, second week, first month and after six months of the bleaching treatment. These methods were VITA Easyshade Spectrophotometer and Vita Classical Shade Guide. Statistical analysis using ANOVA demonstrated equality between the participating groups when evaluating the group and time variables. The In-Office dental bleaching treatments of vital teeth with 35% HP did not prove to be more effective when light sources were used. There was no difference in color stability between groups until the sixth month of evaluation
dentist | Dentists were yesterday ordered to stop reusing instruments in root canal treatments after fears that they could spread the infection of variant CJD.
The chief dental officer, Barry Cockcroft, issued the edict after evidence that vCJD could hypothetically survive the sterilisation techniques used between surgeries. He emphasised that the move was precautionary, and there had been no reported cases of anyone contracting vCJD from dental procedures
Dr Cockcroft added: The guidance is purely an extra precaution. The public should continue to attend their dentist as normal
dentist | Science Daily — Scientists at University College London (UCL) have conducted the first clinical trial to demonstrate that an intensive treatment for periodontitis (gum disease) directly improves the health of blood vessels. This study, conducted in conjunction with Professor Maurizio Tonetti (University of Connecticut, USA), and reported in the latest edition of the New England Journal of Medicine, may have relevance for the prevention of heart attacks and stroke.
dentist | CHIBA, Japan, Feb. 26 (UPI) -- Japanese scientists say they have become the first to successfully replace natural teeth in mice with teeth that were created in a Petri dish.
Takashi Tsuji and colleagues at the Tokyo University of Science said they started with the two cell types that develop into a tooth -- mesenchymal and epithelial cells. First they grew each cell type separately to obtain larger quantities of cells and then injected them into a drop of collagen -- a substance that "glues" cells together in an organism.
The cells developed into a budding tooth with high efficiency and, when transplanted into the cavity of an extracted tooth in a mouse, developed normally and showed the same composition and structure as natural teeth.
The researchers say that method can be applied to any organ that develops from those cell types.
The experiment is described online in the journal Nature Methods.
Copyright 2007 by United Press International. All Rights Reserved.
dentist | The sugar substitute xylitol affects the bacterial composition of the oral cavity even in low doses. On the other hand, a relatively high intake is needed to counteract the production of acid ...
dentist | In a new study, researchers at the Harvard School of Public Health (HSPH) and Dana-Farber Cancer Institute found that periodontal disease was associated with an increased risk of cancer of the ...
dentist | Science Daily — Imagine having a decayed tooth repaired, painlessly, without drilling or shots of anesthesia to numb the area.
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