Types Of Dental Fillings

Dental fillings are  divided into various types. These are Direct Restoration and Indirect Restorations.

DIRECT RESTORATIONS- They include the type of filling materials that are placed in the prepared cavity in a single visit. The materials included in this are resin composites, silver amalgam, glass ionomer cements, temporary filling materials etc.

INDIRECT RESTORATIONSThey include the filling materials that require more than 1 visit to be placed in the cavity. On the first day of appointment, the dentist prepares the tooth and makes an impression to record the details of the tooth to be restored. It is then sent to the dental lab. In the next visit, the material is placed in the prepared tooth. These include veneers, inlays, onlays, crowns and bridges fabricated with gold, base metal alloys, composites.  

DIRECT RESTORATION
 
SILVER AMALGAM 
 
Silver amalgam is undoubtedly the most commonly and widely used filling material. A properly handled silver amalgam produces a restoration that lasts for many years. It is used mostly in posterior teeth.
 
ADVANTAGES
  •  Material is easily handled and manipulated
  • Widely used in many different types or sizes of cavities
  • Used as retrograde fillings
  •  Least technique sensitive
  •   Minimal expansion or contraction at the time of setting
  • Optimal compressive strength
  •  Economical
  •  Hardness is comparable to that of dentin and enamel
  • Biologically stable
  •  Durable
  • Single appointment placement
  • Easily repaired
 
DISADVANTAGES
  • Poor aesthetics, so is not recommended for anterior teeth
  • Extensive cavity cutting is required
  • Mercury toxicity
  • Low tensile strength
  • Base is required under the filling as silver is a good thermal conductor
  •  Poor edge strength
  • Qalvanic current can be produced if any other metallic filling is done in the teeth that come in contact
  • Amalgam blue, blackish appearance of few restored teeth
  • Some patients complain of hot and cold senstivity after the filling
  • Shows marginal breakdown 
CAN BE USED IN
  • In patients of all ages
  • Stress bearing areas
  • In small to moderate size cavities
  •  In patients with poor oral hygiene
  • When moisture control is a problem
  • In low economic status patients
  •  As a foundation to metal ceramic, cast metal restorations    
CONTRAINDICATIONS
  •  Anterior teeth
  •  Patients who have history of allergy to mercury or any other component 
  • Silver amalgam contains silver alloy powder and liquid mercury. The silver alloy powder has constituents like silver, tin, copper and zinc. Amalgam is of 2 types Admixed alloyand Single compositionalloy. It has also been divide into High copperalloy and Low copper alloy, depending upon the amount of copper present in it

RESIN COMPOSITES 

Composite resin is presently the most popular tooth colored filling material. Composite material is a compound of two or more different materials with properties superior or intermediate to those of the individual component. The various components of a composite resin are resin matrix, fillers, coupling agents, coloring agents.
 
The resin matrix initially used was Bis GMA(Bisphenol Glycidyl methacrylate). Now, UDMA( Urethane dimethacrylate) and TEGDMA(Triethylene glycol dimethacrylate) are also being used.
 
 Fillers used are quartz, silica, tricalcium phosphate, zirconium dioxide. They provide strength, hardness, rigidity to the material.
 
Coupling agent binds the resin matrix to the filler particles. Organic silanes are commonly used coupling agents.
 
Coloring agents used are aluminium oxide, titanium dioxide.
 
Composites are divided into 3 types depending upon the size, amount and composition of the inorganic filler. These types are Conventional, Microfilled and Hybrid. Placement of a composite filling requires an etchent (like phosphoric acid) and a bonding agent.
 
Various advances have been made in composites, these are Flowable composites, Packable composites, Antibacterial composites, Laser curing composites.
 
 
FAILURES OF COMPOSITE RESINS
  •  discoloration of the fillings, specially around the margins
  •   recurrent caries
  •  marginal fractures
  • gross fracture of the restoration
  • failure in maintaining proximal contact
  • post operative senstivity
HOW TO AVOID THESE FAILURES
  • complete removal of dental caries
  •  complete etching
  • proper isolation while placement of the restoration
  • uniform and single coat of bonding agent
  •  avoid bulk placement of composite material
  • avoid contact with fingers or gloved hands
  • proper curing of composite
  •  keep cavity as small as possible
  •  avoid sharp internal line angles
  • use small increments
  •  composite at bevelled areas should be polished properly  
 GLASS IONOMER CEMENT (GIC)
 
The glass ionomer cements have evolved as a hybrid of Silicate cements and Polycarboxylate cement. It is available in powder and liquid form. The powder contains silica, alumina, aluminium fluoride, calcium fluoride, sodium fluoride, Aluminium phosphate. The liquid contains polacrylic acid, itaconic acid, maleic acid, tricarballylic acid, tartaric acid, water. The powder and liquid are mixed on a paper pad in the ratio 3:1 and then placed in the cavity formed.
 
Types of GIC
There are 4 types of GIC- Conventional, Hybrid, Tri-cure and Metal reinforced.
 
ADVANTAGES:
 aesthetic
good adhesion to the tooth
releases fluoride, so anti carcinogenic
 high retention
 biocompatible
good marginal seal
requires minimal cavity preparation
 
DISADVANAGES:
soluble
 water affects the setting reaction
abrasive
 not as aesthetic as composite resins
 
USES OF GIC:
used both in deciduous and permanent teeth
class V and class III cavities
abraded or eroded areas
root caries
 rampant caries, nursing bottle caries
 luting or cementing in veneers, metallic and nonmetallic inlays and onlays
 protective liner under amalgam, composite
core build up
retrograde fillings
 splinting of periodontically weak teeth
a traumatic restorative treatment
 repair of perforations in tooth
 
Various modified forms of GIC are available now like Metal modified GIC( miracle mix, glass cermets), Resin modified GIC, Compomer(polyacid modified composite resins).
 
 
INDIRECT RESTORATIONS
INLAYS AND ONLAYS
An Inlay is an intracoronal cast restoration designed mainly to restore occlusal and proximal surfaces of the posterior teeth without involving the cusps of the teeth. They are custom made to fit the prepared cavity and then are cemented in that place. Its placement usually takes two appointments. During the first visit, an impression is made of the tooth and a temporary inlay is placed. The impression is then sent to a dental lab, which will make the inlay according to a particular tooth. On the second appointment, the temporary inlay is removed and permanent placed on the tooth.
An Onlay is a combination of intracoronal and extracoronal cast restorations when one or more cusps are covered. It is a more extensive reconstruction and indicated in areas where lots of tooth structure needs to be restored. It is made in the same way as an inlay and then the permanent onlay is securely bonded using high strength dental resin.
INDICATIONS
extensive tooth loss
 teeth having periodontal problems also
 endodontically treated teeth
 for correction of occlusion
 retainers for fixed prosthesis
 teeth having fracture lines in enamel
 patients with good oral hygiene
CONTRAINDICATIONS
developing or deciduous teeth
 high caries index
 dissimilar metals
 high plaque index
Porcelain inlays and onlays are highly recommended for anterior teeth since they are aesthetic and natural looking as compared to metal fillings. They are long lasting once bonded to the tooth surface and cover large decayed areas.
Gold inlays and onlays are used in posterior teeth. 
 
DIRECT FILLING GOLD
Gold foil is one of the earliest available dental filling materials.
Its available in various forms like gold foil sheets, pellets, ropes, laminated foil, platinized foil, mat gold, mat foil, powdered gold.
 
INDICATIONS
incipient carious lesions
eroded areas
vent holes in crowns
cavities on cusp tips
 
CONTRAINDICATIONS
  teeth with large pulp chambers
 periodontically weak teeth
large carious lesions
aesthetic areas
 low economic status patient
 not possible to maintain complete isolation