Composite filling

Dental composites referred as resin based composites. Synthetic resins evolved as dental restorative materials since they were insoluble, tooth like appearance, insensitive to dehydration, easy to manipulate and reasonably inexpensive. Composite resins are composed of Bis-GMA and other dimethacrylate monomers (TEGMA,UDMA,HDDMA), an inorganic glass filler material silico dioxide (silica) where as ceramic fillers include zirconia-silica and zirconiumoxide, a photoinitiater (camphoroquinone, phenylpropanedione or lucirin).The photoinitiator intiates the polymerization reaction of the resins when a blue light is applied. Dimethylglyoxime is also commonly added to increase the flow properties. The filler ie. Silica gives the composite greater strength, wear resistance, reduced polymerization shrinkage,improved translucency, reduced exothermic reaction on polymerization, improves optical and mechanical properties of the material. A coupling agent silane is added to increase the bond between these two components. Fillers can be classified based on the particle size and shape such as Macrofilled (5–10 micro.mts), Microfillers (0.4 micro.mts), Hybrid fillers (contains particles of different size), Nanofillers (20–70 nano.mts), Bulk filler (4–5 milli.mts).

Handling and Application:

The placement of composite requires meticulous attention to procedure or it may fail prematurely. The tooth must be kept perfectly dry during placement or the resin will likely fail to adhere to the tooth. Composites are placed while in a soft dough like state, and when exposed to a blue light of certain wavelength, they polymerize into a hard solid filling. The Dentist should place the composite in to the deep filling in numerous increments curing each 2–3mm section fully before adding the next. The most desirable finish of the composite restoration can be provided by Aluminium oxide disk. The enamel margin of a composite resin preparation should be beveled in order to improve the appearance and expose the enamel rods for acid attack. Etching of enamel surface prior to the placement of composite resin restoration is done using 30–50% phosphoric acid, washing thoroughly with water and drying it with air only. Contraindications for composite include usage of varnish and zinc-oxide eugenol.

Advantages :

1.Tooth colored restorative material ( aesthetics)

2. Strong bonding to the tooth structure

3. Conservative preparations unlike amalgam fillings

4. More cost effective alternative to dental crowns

5. Versatility: used for repair of chipped, broken or worn teeth

6. Longer working time : for the dentist

7. Reduced exposure to mercury for both the patient and the dentist

8. Lack of corrosion unlike amalgam fillings

Disadvantages :

May undergo polymerization shrinkage leading to secondary caries, Not as durable as amalgam fillings under the pressure of chewing, chipping off the tooth, sometimes time taking procedure.

Composites based on flow characteristics :

1. Universal : traditional composite resins commonly used in the practice where aesthetics is not the paramount.

2. Flowable composites: indicated for small cavities, preventive resin restorations, pit and fissure sealants, cavity liners etc . contraindicated in stress bearing areas.

3. Packable composites: indicated for posterior teeth fillings which are major stress bearing areas. They are more viscous compared to flowable composites because of the higher filler content.

About the author:

Author: Dr. Abhilash Dandy

Qualification: B.D.S

I graduated as a Dentist from Sibar Institute of Dental Sciences, Guntur. I have done my externship program at Rutgers school of dental medicine, New Jersey, USA. I have clinical experience of 3 years and currently working as Administrative head — Dental wing in MediCub India, Hyderabad.