Introduction: The outcome of root canal treatment is based on the efficient disinfection of the root canal system and the prevention of reinfection. Pulpectomy is defined as a root canal procedure for pulp tissue that is irreversibly infected or necrotic due to caries or trauma in primary teeth. The root canals are debrided and shaped with hand or rotary files. However, since instrumentation and irrigation with an inert solution alone cannot adequately reduce the microbial population in a root canal system, disinfection with irrigants such as sodium hypochlorite and/or chlorhexidine is an important step in assuring optimal bacterial decontamination of the canals. But these have disadvantages. For example, as it is a potent tissue irritant, sodium hypochlorite must not be extruded beyond the apex. We can use a laser to disinfect the canals. Also, in primary teeth, due to complex pulpal anatomy and curved canals, it is difficult to completely remove the pulp and hence the bacterial load.
Justification for Using Laser
1) The effect of the laser beam is based on thermal changes, i.e., it generates heat which is bactericidal and thus kills the microorganisms in the root canal. The antibacterial effect of diode lasers has been observed to be more than 1000 microns deep into dentine.
2) Irrigants have limited penetration into dentinal tubules in the apical 1/3rd when compared to the middle and coronal 1/3rd, but lasers can eliminate microorganisms in deeper layers of dentin.
3) Require minimal enlargement of the root canals during cleaning and shaping to allow for maximum canal disinfection.
This antibacterial effect of lasers has a broad application spectrum.
1) Straight line access: The 200 micron laser tip should not be bent, or it will break, if used in a primary tooth.
So it is important to have straight-line access.
2) Wet canals: Saline can be used to wet the canals. Dry canals are a complete contraction while using a laser.
3) Working length-The working length is different for straight and curved canals. s
a) Straight canals—it is measured at 2 mm short of the apex. For example, the specimen has a working length of 12 mm. So 12-2 = 10 mm. This 10mm will be the length up to which the laser tip will go inside the canal.
b) Curved canals: The curvature is measured from the first pass.is not flexible, hence it should not be forced beyond the maximum curvature. For example, if the first pass curvature is at 12 mm, then 12 x 2 = 10 mm will be our working length for the curved canal.
Settings/parameters for laser root canal disinfection: The laser we have used is the S1 Pioon Laser at a 980nm wavelength.
1) A 200 micron non-initiated tip is used in continuous mode at 1 W.
2) Withdrawal of the tip from the canal is done at the rate of 2 mm/second.
3) Disinfection begins at the apex and progresses to the canal orifice.
4) Circumferentially move the tip without touching the canal's walls.
5) No more than three passes should be made per canal, and the total time for the entire tooth should not exceed 30 seconds.
Steps for Root Canal Disinfection: Under rubber dam isolation, all the steps till biomechanical preparation (BMP) remain the same.
Step 1: Irrigation: we wet the canals first with saline.
Step 2): First pass-200 micron tip at 1W continuous mode with a working length of 2mm short of the apex is used in a circumferential manner at a rate of 2mm/sec without touching the walls of the canal from apex to canal orifice. Withdraw the laser tip.
3) IRRIGATION-To be repeated
4) Second pass-Repeat the action as in the first pass. Withdraw the suggestion
5) Saline irrigation to wet the canals
6) Third pass – Proceed in the same manner as the first.Withdraw the suggestion
7) In primary molars, the furcation area has many accessory canals, and disinfection of these canals is a very important step in primary molar root canal disinfection. The laser tip is kept 2 mm away from the pulpal floor at the same settings as before to lase the furcation area.
Multiple-visit root canal protocol –
1) The root canal disinfection procedure must be performed at each visit.
2) In the case of multiple visits, it should be repeated prior to obturation.
LASER is a superior tool for root canal disinfection. A favourable outcome can be achieved with the laser as an adjuvant along with the traditional root canal disinfection.
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