Podcast
Questions and Answers
What effect does a higher temperature have on surface tension?
What effect does a higher temperature have on surface tension?
What is the term for the process that reduces surface energy through secondary bonding?
What is the term for the process that reduces surface energy through secondary bonding?
Which condition indicates a hydrophilic interaction between a liquid and a solid?
Which condition indicates a hydrophilic interaction between a liquid and a solid?
How does the viscosity of an adhesive affect bonding?
How does the viscosity of an adhesive affect bonding?
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What happens to bonding if the temperature is increased?
What happens to bonding if the temperature is increased?
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What effect do surface impurities have on bonding?
What effect do surface impurities have on bonding?
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What characteristic of an adhesive reduces bonding due to its thickness?
What characteristic of an adhesive reduces bonding due to its thickness?
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What is the clinical significance of applying a wetting agent on wax patterns?
What is the clinical significance of applying a wetting agent on wax patterns?
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What is cohesion defined as in the context of bonding?
What is cohesion defined as in the context of bonding?
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Which type of bonding utilizes mechanical interlocking as its mechanism?
Which type of bonding utilizes mechanical interlocking as its mechanism?
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What characterizes adhesion at the molecular level?
What characterizes adhesion at the molecular level?
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Which layer is involved in the adhesion process?
Which layer is involved in the adhesion process?
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What is the role of an adhesive in bonding?
What is the role of an adhesive in bonding?
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In the field of dentistry, which interfaces are deemed important for adhesion?
In the field of dentistry, which interfaces are deemed important for adhesion?
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What distinguishes physisorption from chemisorption in adhesion?
What distinguishes physisorption from chemisorption in adhesion?
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What is a major clinical significance of understanding bonding and adhesion?
What is a major clinical significance of understanding bonding and adhesion?
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What is the purpose of using 37% phosphoric acid in the acid etching technique?
What is the purpose of using 37% phosphoric acid in the acid etching technique?
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What does macro-interlocking achieve in dental bonding?
What does macro-interlocking achieve in dental bonding?
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How does capillary rise occur in dentistry?
How does capillary rise occur in dentistry?
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What visual evidence is provided by scanning electron micrographs of etched enamel?
What visual evidence is provided by scanning electron micrographs of etched enamel?
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What is primarily achieved by using a surfactant in the lost wax technique?
What is primarily achieved by using a surfactant in the lost wax technique?
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What is the primary challenge in achieving true chemical bonding between tooth structure and dental materials?
What is the primary challenge in achieving true chemical bonding between tooth structure and dental materials?
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Which of the following dental materials is capable of establishing chemical interaction with hydroxyapatite?
Which of the following dental materials is capable of establishing chemical interaction with hydroxyapatite?
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What is the method by which adhesion is primarily accomplished in dentistry?
What is the method by which adhesion is primarily accomplished in dentistry?
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Which factor influences the adhesion capacity of the adherend?
Which factor influences the adhesion capacity of the adherend?
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What effect does surface tension have on adhesive capacity?
What effect does surface tension have on adhesive capacity?
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In a wet environment, what type of bonding is generally present between two materials?
In a wet environment, what type of bonding is generally present between two materials?
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Which of the following statements is true regarding surface energy?
Which of the following statements is true regarding surface energy?
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What role does contamination play in bonding within dentistry?
What role does contamination play in bonding within dentistry?
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Study Notes
Surface Chemistry (Bonding and Adhesion)
- The presentation focuses on surface chemistry, particularly bonding and adhesion, in dentistry.
- Learning objectives include defining bonding types, understanding bonding and adhesion mechanisms, recognizing factors affecting adhesion, understanding clinical significance, and familiarity with acid etching.
- Surface properties are crucial in dentistry because of the importance of interfaces, such as implant-cells, enamel-dentin-bonding resin, and orthodontic bracket-enamel.
Introduction
- Scientific understanding of materials-tissue and materials-materials interfaces is increasing in dentistry.
- Interfaces in dentistry include implant-cells, enamel-dentin bonding resin, and orthodontic bracket-enamel.
Implant-tissue Interface
- Depicts a diagram of an implant and natural tooth, highlighting the implant-tissue relationship.
- The implant is a porcelain crown with a metal implant embedded in the jawbone.
Bonding of Orthodontic Brackets
- Shows images of orthodontic brackets on teeth.
Cementation of Artificial Crowns
- Illustrates the process of cementing artificial crowns onto teeth.
Bonding Composite Resin Filling
- A visual example of composite resin fillings on teeth.
Bonding Mechanisms
- Bonding can be achieved chemically (cohesion and adhesion) or mechanically (interlocking).
Cohesion
- The attraction between atoms or molecules of the same kind within a material.
- Primarily involves chemical primary bonds.
Adhesion
- The attraction between atoms or molecules of different kinds in contact.
- Surfaces can be divided into substrate and adsorbed layers.
- Adsorption can involve chemical reactions (chemisorption) or weaker interactions (physisorption).
Definitions
- Adhesive: The material applied to create adhesion.
- Adherend (substrate): The material the adhesive is applied to.
Adhesion between Two Solid Surfaces
- Illustrates a diagram of two surfaces with an adhesive in between them.
Dental Bonding Challenges
- True chemical bonding between tooth structure and restorative/luting materials is difficult in dentistry due to the complex composition of substrates (such as dentin), the presence of contaminants, and water.
Exceptions to Chemical Bonding
- Zinc polycarboxylate, glass ionomer, and resin-modified glass ionomer are dental materials capable of chemical interaction with hydroxyapatite.
Primary Adhesion Mechanism
- Micro and macro mechanical interlocking are the primary mechanisms of adhesion used in dental practice.
Physical Bonding
- Physical bonding (van der Waals forces) exists between any two contacting materials, but it is especially weak in wet environments.
Factors Affecting Adhesion (Bonding)
- 1. Surface Energy of the Solid: Surface energy is higher than the interior of solids; higher surface energy of the solid increases adhesion.
- 2. Surface Tension of the Liquid: Surface tension of liquids, like an adhesive, influences adhesion and can be altered based on the nature of liquid molecules, temperature, or the presence of impurities. Lower surface tension increases adhesion.
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3. Wettability: A liquid's tendency to spread over a solid surface. Increased wettability leads to higher adhesion. Wettability is demonstrated by contact angles.
- Contact angle, the angle created between a liquid and a solid surface, determines wettability. Smaller angles lead to greater wettability.
- Hydrophilic materials have contact angles < 90°
- Hydrophobic materials have contact angles > 90°
- Contact angle, the angle created between a liquid and a solid surface, determines wettability. Smaller angles lead to greater wettability.
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4. Other Factors: Affecting adhesion include:
- Viscosity: Low viscosity of adhesive increases bonding.
- Impurities: The less impurities on surfaces, the greater the adhesion.
- Surface roughness/area of contact: Wider contact areas between two materials and more roughness improves adhesion.
- Dimensional stability, temperature, film thickness.
Mechanical Bonding (Interlocking)
- Macro-interlocking: Occurs due to the shaping of the tooth structure and the surface roughness of the tooth and crown.
- Micro-interlocking: Achieved by acid etching.
Acid Etching
- Acid etching involves applying an acid (e.g., 37% phosphoric acid) to tooth structures for a short period to remove inorganic content, creating micropores.
- These micropores are subsequently filled with bonding agents and restorative materials.
Acid Etching and Composite Filling Procedure
- Showed step-by-step instructions on acid etching and composite filling procedures.
Etched Enamel/Resin Tags
- Scanning electron micrographs showing etched enamel surfaces with resin tags.
Etching of Dentin
- Scanning electron micrographs showing dentinal surfaces before/after etching, highlighting changes to tubules.
Bonding Composite Resin with Dentin
- Illustration of the composite resin bonding process with dentin.
- Involved steps of acid-etching, rinsing, applying bonding agent, applying composite, and curing.
Capillary Rise
- Penetration of liquids into narrow spaces, relevant to caries progression and the way restorative materials fill cavities.
- Occurs only when the contact angle between the solid and liquid is less than 90 degrees
- Capillary rise is affected by the gap width.
Clinical Significance of Surface Energy and Wettability
- Waxes are hydrophobic and need wetting agents on their surface for adhesion.
- Fluoride reduces plaque accumulation on teeth by decreasing enamel surface energy.
- Surfactants are added to hydrophobic impression materials to enhance wettability.
Lost Wax Technique and Porcelain Making
- Describes the steps involved in creating dental prostheses using the lost wax technique.
Spraying Wax Pattern with Surfactant and Investing
- Explains the steps in preparing a wax pattern for casting.
Casting Ring Before and After Filling with Investment
- Illustrates the steps in preparing a casting ring for use.
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Description
This quiz explores the principles of surface chemistry as they relate to bonding and adhesion in dentistry. Key topics include bonding mechanisms, factors that influence adhesion, and the clinical significance of these concepts in dental practice. Enhance your understanding of how interfaces between materials affect dental procedures.
