bonding to tooth structure dental material

1. BONDING TO TOOTH
STRUCTURE

2.  Macro-mechanical attachment
 Chemical bonding
 Micro-mechanical attachment
 Interpenetration (Hybrid layer)
Bonding Approaches to Tooth Structure

3. ADHESIVE
BONDING

4. Clinical Applications
 Bonded resin composite restorations.
 Bonded amalgam restoration.
 Cementing indirect ceramic restorations.
 Root canal posts and direct resin core build-ups.
 Glass ionomer restoration and cementation.
 Bonding of orthodontic brackets.
 Application of pits and fissures sealant.

5. Difficulties
 Heterogeneous composition of tooth structure
 Wet tissues
 Presence of saliva
 Tubular nature of the dentin
 Irregularities of cut enamel and dentin surfaces
 Presence of debris layer (smear layer)
1. Northwest Dentistry - Journal of the Minnesota Dental Association
2. www.answers.com/topic/smear-layer
3. www.forp.usp.br/bdj/bdj12(3)/trab13123/t13123.html

6. ADHESIVE BONDING
TO TOOTH ENAMEL

7.  Chemical Bonding
Both PAA or phosphates-containing bonding agents can achieve
chemical bond to HA
 Micro-mechanical retention (Acid etching)
Adhesive Bonding to Tooth Enamel
Benefits of acid etching
1. Creating surface micro-irregularities
2. Increases the bonding surface area
3. Removes surface debris and stains
4. Increase the surface free energy
Types of acids to be used
 30-50% phosphoric acid (liquid or gel)
 10% Maleic acid
 2.5% Nitric acid
 18% Hydrochloric acid

8. www.nordiskadental.se/ana_etchi...composite

9. Steps of acid etching
 Application of the nominated acid for 15-60s
 Rinsing with water-air spray for 15s
 Air Drying for 15s
 Enamel surface should have a white frosted appearance
 This procedure is then followed with application of liquid adhesive
 The restorative material (composite) should only applied after hardening
(curing) of the adhesive takes place
priory.com/den/resin.htm

10. Enamel Bonding Agents
 Diluted Bis-GMA or TEG-DMA resins.
 Hydrophobic….. Bond only to dry enamel surfaces
 New formulations have hydrophilic resins (HEMA) to be used for
both enamel and dentin bonding

11. ADHESIVE BONDING
TO TOOTH DENTIN
Yoshiyama et al., J. Appl. Oral Sci. 2004

12.  Chemical Bonding
Bonding to the HA (Ca++)
o NPG-GMA (N-phenyl glycine glycidyl methacrylate)
o Polymerizing phosphates (glycerophosphoric acid dimethacrylate)
o Poly alkenoic acid (polycarboxylic acid)
Bonding to collagen
o Glutaraldehyde reacts with collagen forming a charged compounds that
reacts with HEMA molecule.
o 4-META (4- methyloxy ethyl trimellitic anhydride) can be used as a
potential coupling agent to collage
 Micro-mechanical attachment
Retention of resin adhesive could be achieved to irregular dentin surfaces
(inter-tubular dentin) and to the walls of opened dentinal tubules (intra-
tubular dentin).

13.  Interpenetration attachment
Hydrophilic resin adhesive is required to penetrate the wet
collagen. e.g. HEMA , PAA and NPG-GMA (N-phenyl glycerol
glucidyl methacrylate)
Dentin Bonding Agents (DBA) should Have both hydrophilic and
hydrophobic resin components.
oThe hydrophilic part is to displace the dentinal fluids and wet the surface.
oThe hydrophobic part is responsible for bonding to composite filling materials.

14. G Characteristics Bond
strength
Commercial
examples
1st
- 1 component
- Very weak adhesion to dentin
2 MPa - Cervident
- Cosmic Bond
2nd
- 2 components
- Weak adhesion to dentin
- Prone to water-degradation
2-8 MPa - Bond Lite
- Scotchbond
- Dentin Adhesit
3rd
- 2 component (primer +adhesive)
- Bonding to metal
- Reduced sensitivity
8-15
MPa
- Prisma UB
- Scotchbond II
- Tenure
- Gluma
- X-R Bond
Development of Dentin Bonding Systems

15. 4th
Generation
(3 Steps)
1. Etchant
2. Primer (could be B&C)
3. Adhesive (could be B&C)
1. www.solutions.3m.com.
2. www.promedica.de/products/compblcm.htm
 Total etch (E&D)
 Formation of hybrid layer
 Acceptable bond strength (17-25 MPa)
• Compobond LCM
• Scotchbond MP
• Syntac

16. 5th
Generation
(2 Steps)
1. Etchant
2. single component
(Primer + Adhesive)
 Total etch (E&D)
 Wet bonding
 Formation of hybrid layer
 Acceptable bond strength (20-24 MPa)
• Exite
• Single-Bond
• one-step

17. 6th
Generation
(2-3 steps)
1. Self-etch primer
(etchant + primer)
2. Adhesive
• Prompt L-Pop
• SE Bond
• Liner bond
 Total etch (E&D)
 Formation of hybrid layer
 Acceptable bond strength (18-23 MPa)

18. 7th
Generation
(1 step)
1. Self-etch Adhesive
• I- Bond
• G-Bond
• VivaPen
 Total etch (E&D)
 Formation of Nano-hybrid layer
 Acceptable bond strength (18-25 MPa)