Finishing and Polishing

Remove oxygen-inhibited layer .Use stones or carbide burs for gross reduction.Use highly fluted carbide burs or special diamonds for fine reduction.Use aluminum oxide strips or disks for finishing. Use fine aluminum oxide finishing pastes. Microfills develop smoothest finish because of small size of filler particles
 

Denture Liners

Use - patients with soft tissue irritation

Types

Long-term liners (soft liners)-used over a period of months for patients with severe undercuts or continually sore residual ridges

Short-term liners (tissue conditioners)-used to facilitate tissue healing over several days

Structure

Soft liners-plasticized acrylic copolymers or silicone rubber

Tissue conditioners-PEMA plasticized with ethanol and aromatic esters

Properties

Liners flow under low pressure, allowing adaptation to soft tissues, but are elastic during chewing forces. 
Low initial hardness, but liner becomes  harder as plasticizers are leached out during intraoral use 
Some silicone rubber liners support growth of yeasts
 

Components 

a. Fillers added to most to control shrinkage
b. Matrix

Bonding Agents

Applications-composites, resin-modified gIass ionomers, ceramic bonded to enamel restorations, veneers, orthodontic brackets, and desensitizing dentin by covering exposed tubules (Maryland bridges, composite and ceramic repair systems, amalgams and amalgam repair, and pinned amalgams)

Definitions;-

Smear layer - Layer of compacted debris on enamel and/or dentin from the cavity preparation process  that is weakly held to the surface (6 to 7 MPa) , and that limits bonding agent strength if not removed

Etching (or, conditioning)- smear layer removal and production of microspaces for micromechanical bonding by dissolving –minor amounts of surface hydroxyapatite crystals

Priming..- micromechanical (and chemical) bonding to the microspaces created by conditioning step.

Conditioning/priming agent-agent that accomplishes both actions

Bonding- formation of resin layer that connect  the primed surface to the overlying restoration (e.g., composite) .. –

Enamel bonding System-for bonding to enamel (although dentin bonding may be a Second step)

Dentin bonding system  for bonding  to dentin (although  enamel bonding  may have been a first step)

•        First-generation dentin bonding system for bonding to smear layer

•        New-generation dentin bonding system- for removing smear layer and etching intertubular dentin to allow  primer and/or bonding agent to diffuse into spaces between collagen and form hybrid zone

Enamel and dentin bonding system-for bonding to enamel and dentin surfaces with the same procedures

Amalgam bonding  system for bonding to enamel, dentin, and amalgam, dentin and amalgam during an amalgam placement procedure or for amalgam repair

Universal bonding system-for bonding to enamel, dentin, amalgam, porcelain , or any other substrate intraorally that may be necessary for a restorative procedure  using the  same set of procedures and materials

Types

Enamel bonding systems

Dentin bonding systems

Amalgam bonding systems

Universal bonding systems

Structure

o        Components of bonding systems

o        Conditioning agent-mineral or organic acid

Enamel only   37% phosphoric acid

Dentin only or enamel and .dentin---37% phosphoric acid, citric acid, maleic acid, or nitric acid

o        Priming agent

Hydrophobic-solvent-soluble, light cured monomer system

Hydrophilic-water-soluble, light-cured monomer system

Bonding agent

BIS-GMA-type monomer system

UDMA-type monomer system

Reaction

Bonding occurs primarily by intimate micromechanical retention with the relief created by the conditioning step

Chemical bonding is possible but is not recognized as contributing significantly to the overall bond strength

Manipulation-follow manufacturer's directions

Properties

Physical-thermal expansion and contraction may create fatigue stresses that debond the interface and permit micro leakage

Chemical-water absorption into the bonding agent may chemically alter the bonding

Mechanical-mechanical stresses may produce fatigue that debonds the interface and permits microleakage

Enamel bonding-adhesion occurs by macrotags (between enamel prisms) and microtags (into enamel prisms) to produce micromechanical retention

Dentin bonding-adhesion occurs by penetration of smear layer and formation of microtags into intertubular dentin to produce a hybrid zone (interpenetration zone or diffusion zone) that microscopically intertwines collagen bundles and bonding agent polymer

Biologic

Conditioning agents may be locally irritating if they come into contact with soft tissue

Priming agents (uncured), particularly those based on HEMA, may be skin sensitizers after several contacts with dental personnel

Protect skin on hands and face from inadvertent contact with unset materials and/ or their vapors

HEMA and other priming monomers may penetrate through rubber gloves in relatively short times (60 to 90 seconds)

Cement Bases

Applications

•    Thermal insulation below a restoration
•    Mechanical protection where there is inadequate dentin to support amalgam condensation pressures

Types

•    Zinc phosphate cement bases
•    Polycarboxylate cement bases
•    Glass ionomer cement bases (self-curing and light-curing)

Components

o    Reactive powder (chemically basic)
o    Reactive liquid (chemically acidic)

Reaction

o    Acid-base reaction that forms salts or cross linked matrix
o    Reaction may be exothermic

Manipulation-consistency for basing includes more powders, which improves all of the cement properties

Properties

Physical-excellent thermal and electrical insulation

Chemical-much more resistant to dissolution than cement liners

    Polycarboxylate and glass ionomer cements are mechanically and chemically adhesive to tooth structure

    Solubility of all cement bases is lower than cement liners if they are mixed at higher powder- to-liquid ratios

Mechanical- much higher compressive strengths (12,000 to 30,000 psi)
    Light-cured hybrid glass ionomer cements are the strongest
    Zinc oxide-eugenol cements are the weakest

Biologic (see section on luting cements for details)

    Zinc oxide-eugenol cements are obtundent to the pulp
    Polycarboxylate and glass ionomer cements are kind to the pulp
 

Root canal sealers

Applications

Cementation of silver cone gutta-percha point
Paste filling material

Types

Zinc oxide-eugenol cement types
Noneugenol cement types
Therapeutic cement types

properties

Physical-radiopacity
Chemical-insolubility
Mechanical-flow; tensile strength
Biologic-inertness

Gingival tissue packs

Application-provide temporary displacement of gingival tissues
Composition-slow setting zinc oxide-eugenol cement mixed with cotton twills for texture and strength

Surgical dressings
1.Application-gingival covering after periodontal surgery
2. Composition-modified zinc oxide-eugenol cement (containing tannic, acid. rosin, and various oils)

Orthodontic cements

Application-cementation of orthodontic bands
Composition-zinc phosphate cement 

Manipulation

Zinc phosphate types are routinely mixed with cold or frozen mixing slab to extend the working time
Enamel bonding agent types use acid etching for improved bonding
Band, bracket, or cement removal requires special care