Light Cure Units
With advancements in the dentistry, resin based composite materials have also been evolved. The improvements in structure, photo-initiator material, aesthetic aspect, polymerization techniques in resin-based composites make it more significant to choose a best Light Cure Unit for a successful dental restoration. The most significant element for a successful restoration is strong adherence to the tooth structure and sufficient polymerization of the resin content.
A Led Light Curing Unit is a dental device that uses the light energy (UV) to initiate polymerization process of resin based composite materials during dental restoration procedure.
The Polymerization Process:
The restorative material is composed of a urethane methacrylate base and a photo-initiator that absorbs the light energy radiated. This gets activated when exposed to electromagnetic radiation i.e. Ultraviolet light of a specific wavelength and create free radicals. These free radicals disperse through the resin medium bonding with monomer to initiate the polymerization process. The viscosity of the resin system increases with increasing monomer integration into the growing polymer network and thus the resin-based composite is polymerized.
Factors Associated with Light Cure Units in Dentistry:
The efficacy of a curing light to effectively cure a composite resin depends on many factors, such as wavelength of the emitted light, type of photo-initiator, exposure time, distance and angulation of the light probe etc.
- Size of the Curing Light Probe: The intensity of the light from the curing unit probe spreads from center to the edges thereby energy is more concentrated in a probe of small diameter (3mm) whereas more diffused in case of standard diameter (11mm). Small diameter in curing light tip increases the light energy but also boost the temperature while curing the restoration, so precautions needs to be taken while using the unit.
- Light Intensity: A sufficient energy density is needed for proper curing of resin-based composites. To maintain the effectiveness of the curing light, cotton swabs dipped in alcohol or methyl ethylketone solvents are essential for routine cleaning of the mirror surface. This helps to maintain the potency of the bulb’s reflection.
- The beam spreading: The light beam usually disperses from the curing unit tip from its source, resulting in an inhomogeneous distribution of light intensity. In order to properly cure the entire surface, it is therefore important to step the light over a broad restoration.
- Angulation of the Tip: When help perpendicular to the restoration surface, a light beam of the LED Curing Unit produces a circular spot of light. To obtain optimum light intensity on the surface, the wand tip of the dental curing unit should always be parallel to the restoration surface.
Types of Photo-Initiators:
- Camphor quinone: Camphor quinone is yellowish in color. Polymerization process is initiated very slowly and it absorbs at the wavelength of 468nm.
- TPO (2,4,6 – Trimethylbenzoyldiphenyl Phosphine Oxide): It has a yellow resistant property and suitable for light colored or bleached resins. Its absorption peak is 350nm to 405nm. The photo curing speed is fast.
Types of Light Cure Units in Dentistry:
- Quartz Tungsten halogen Curing light: It is equipped with a Quartz bulb along with tungsten filament. When electric current pass through the tungsten filament, electromagnetic radiations are generated in form of visible light that is used for curing. It generates blue light of 400 -500 nm.
- Plasma Arc Curing Light: 2 Tungsten rods held at a distance in a gaseous medium of Xenon gas. When high voltage is generated in tungsten rods, it ionizes xenon creating blue UV light of wavelength 400 -500 nm. But it also generated heat that may cause tissue injury.
- Argon Laser Lamp: Laser photons generates high intensity light energy of wavelength 490 nm in a gaseous medium of Argon. It has a risk of other tissues getting irradiated.
- Light Emitting Diodes: LED lights have also been used as light cure unit for the polymerization process of composites. It kept on advancing from generations to generations with advancements in the resin materials.
Techniques of Dental Light Cure Unit:
- Uniform Continuous Cure: Constant intensity light applied to the resin-based composite for polymerization. It is the most familiar method.
- Step Cure: To reduce the degree of polymerization shrinkage first low energy and then high energy light is applied to the restoration surface for polymerization.
- Ramp Cure: Again, for reduction in chances of polymerization shrinkage, low intensity light is first applied then gradually the intensity is increased.
- High Energy Pulse Cure: High energy light than normal power is applied to the surface. It is mostly used for orthodontic brackets and sealants.
The Dental Curing Unit with high durability and excellent performance with upgraded wavelength are available in Best Dental Deals at very reasonable price for the Indian dentists to buy online without any difficulties.