Sistemas Adesivos e Adesão - Adesão em Dentina

New Section

In this section, the discussion focuses on the adhesion to dentin tissue and the characteristics of dentin compared to enamel.

Adhesion to Dentin Tissue

• Dentin is a mineralized tissue composed mainly of organic content, with approximately 70% organic material primarily consisting of collagen fibrils.

• Dentin differs from enamel due to its heterogeneous morphological structure, including dentinal tubules and intertubular dentin, making it more technically complex for adhesion compared to enamel.

• Dentin is formed by dentinal tubules arranged radially from the pulp region to the junction between enamel and dentin, with variations in tubule concentration based on proximity to different regions.

• Tubules near the pulp region have larger diameters compared to those near the junction with enamel, leading to differences in moisture content that affect adhesive strength.

Dentin Preparation and Adhesive Techniques

• During cavity preparation on dentin tissue, a layer called "smear layer" forms comprising debris from cutting instruments like diamond burs or handpieces.

• The smear layer deposited on dentin during cavity preparation is known as "dentin mud" or "smear plug," which can obstruct tubules and impact adhesion.

• Conventional adhesive systems involve acid conditioning using phosphoric acid separately applied before bonding procedures for effective adhesion.

Advanced Adhesive Techniques

This section delves into advanced techniques for enhancing adhesive bonding on dentin tissue through meticulous application processes.

Acid Conditioning and Water Management

• Acid conditioning involves applying phosphoric acid on dentin surfaces followed by rinsing after 15 seconds to remove the smear layer and expose collagen fibrils for bonding.

• Adequate water presence post-acid removal facilitates resin infiltration into collagen fibrils, ensuring proper adhesion without fiber collapse due to hydrogen bond formation.

Moisture Control Strategies

• Maintaining optimal moisture levels during adhesive procedures is crucial; excessive water dilutes adhesives while insufficient water leads to compromised resin penetration.

Dentin Adhesion Techniques

In this section, the speaker discusses the importance of dentin moisture control and the challenges faced in infiltrating demineralized dentin with adhesive materials.

Dentin Moisture Control and Adhesive Penetration

• Dentin moisture control is crucial for ensuring successful adhesion.

• Conventional systems lack assurance of complete infiltration of demineralized dentin by phosphoric acid and adhesive.

• Different conditioning times are required for enamel (15 seconds) and dentin (30 seconds) to optimize adhesion.

• After acid application, thorough washing is essential to remove residual acid effectively.

• Use of absorbent paper helps maintain desired dentin moisture levels for optimal adhesion.

Enzyme Inhibition in Dentin Adhesion

This part focuses on inhibiting enzyme activity that can degrade the hybrid layer formed during dentin adhesion.

Enzyme Inhibition with Chlorhexidine

• Enzymes like metalloproteinases can degrade the hybrid layer; chlorhexidine solution application inhibits their action.

• Chlorhexidine application post-acid conditioning aids in enzyme inhibition.

Adhesive Application Techniques

The discussion shifts towards proper techniques for applying primers and adhesives in different types of dental preparations.

Primer and Adhesive Application

• Proper moisture control is crucial before applying primer and adhesive materials.

• Techniques differ between three-step and two-step systems regarding primer and adhesive application.

• Evaporation of solvent post-application aids in water removal, enhancing adhesive penetration.

• Timing is critical post-primer application before proceeding with adhesive to ensure optimal bonding.

Final Steps in Dentin Adhesion

The final steps involved in completing the dentin adhesion process are outlined here.

Finalization of Adhesive Process

• Follow manufacturer's instructions for photoactivation after completing adhesive application.