DENTAL MATERIAL

Types of Polymerization of Resin Composite Dental Material

Types of Polymerization of Resin Composite Dental Material

Types of polymerization

Chemical cure materials

The term self cure or dual cure (when combined with photo chemical initiation) describes chemical cure materials. Chemical composites mix a base paste and a catalyst paste for self cure. Bonding agents mix two liquids. Mixing two pastes incorporates air into the composite. Oxygen inhibits curing resulting in a weaker restoration.

The additional use of a chemically curing catalyst may compensate for these problems, it is also reported that the incorporation of the necessary catalyst has the potential for discoloration of the luting resin and disadvantage which causes lower bond strength in interference with some self-etching adhesives(Anusavice, 1996: 205-208).

For e.g. A highly filled, non-sticky, self curing, hybrid, anterior/posterior composite filling material. It is a convenient universal shade, paste/paste system. The restorative has high strength (2 i 3 MPA compressive) with low water sorption and solubility(Hoffman, 2002: 471-9.).

The material can be condensed into the cavity preparation up to the enamel-dentinal joint as a base layer or may be filled to the cavo-surface margin for a complete self cure composite restoration. Quick setting eliminates time spent with incremental placement of light cure materials.

Visible light cure material

Composite resins activated by ultraviolet light and visible light have become an essential part of the armamentarium of the dentist undertaking restorative, preventive and orthodontic dentistry. Visible light in the blue region of the spectrum has gained popularity as a source over ultraviolet light because of its ability to produce a greater depth of polymerization (Emami, 2003: 536-42). These are the units that cause dental materials, such as composites, sealants, and cements, to set or polymerize in the mouth. These units produce a visible blue light that these materials absorb, causing them to set. The first point is that the unit produces visible light, not ultraviolet light. Every dental curing light today is a visible blue light and does not produce ultraviolet light, which would not generally be safe for you, or the patient. So these lights are not UV lights. The confusion arises from the fact that dental curing lights once were UV lights (Mills, 2002: 2955-63). The inventor of this system was not familiar with visible light curing chemistry at the time, and therefore selected UV chemistry, which was quickly replaced by blue, visible light curing chemistry.

Dual cure material

The use of dual-curing resin cements intends to combine chemical and light-polymerization and at the same time allowing polymerization to take place in deeper areas of the tooth cavity applying shorter light irradiation time.Dual-cured resin cements have been developed in an attempt to combine the most desirable properties of the chemical-curing and light-curing materials, thereby providing adequate polymerization in deeper areas, reduced inhibition zone, and shorter setting time. Dual-cure cements includes Calibra, Choice and RelyX ARC.

Polymerization of a dual-cured resin cement is significantly affected by ceramic thickness but not affected by activation modes. Increased irradiation times could potentially lead to higher hardness values in applications where light is ...