Experimental studies of the application of the Er:YAG laser on dental hard substances: II. Light microscopic and SEM investigations

Abstract

Many studies have been undertaken trying to use various laser systems as optical drills on dental enamel and dentin, but the high radiant exposure needed and subsequent high temperature rises lead to fractures of the hard substances and possible damages to the pulp. Compared to the other laser systems, the use of the Er:Yag laser has given encouraging results. Optical and scanning electron microscopy showed only minimal if any damage of the surrounding tissue.

Temperature rise in cavities prepared by high and low torque handpieces and Er:YAG laser

“…In the current study, the irradiation of the Er:YAG laser at energy density of 80.19J/ cm 2 created a mean increase in temperature of 0.74 o C. The reduced increase of temperature is in agree ment with the findings of 10 who verified that the majority of the incident energy is consumed in the ablative process and only a small frac tion of the energy results in heating the remaining tissue, causing no damage. The reduction of temperature change is also obtained from the use of constant water cooling, in accordance with Attrill et al (2004), 16 who observed that the application of an Er:YAG laser without water cooling would exceed the temper ature increase threshold of 5.6ºC.…”

“…Some Er:YAG laser beams could penetrate to deeper areas than the ablated area and damage the nerve fi bres and terminals, which might be a mecha nism of pain reduction in cavity ablation with the Er:YAG laser. 1 A number of authors 10,13,16,[18][19][20][21][22][23] stud ied the behaviour of different lasers to determine the amount of temperature increase during cavity preparation on dental structure. Keller et al (2003) 19 verified a mean temperature rise of 1.68ºC in the pulpal chamber using CO 2 and morphologically unaltered dentine surfaces, demonstrat ing the safe and tissue preserving char acter of the laser.…”

“…Class I and class V cavity preparations with Er:YAG laser in enamel, cemen tum and carious tissue was carried out by Oelgiesser et al (2003), 18 at different irradiation energies (600-1000 mJ) and pulse frequencies (7)(8)(9)(10)(11)(12), with an air-water spray as a cooling system. The authors stated that the elevation meas ured in the pulp chamber during lasing with various energies and pulse rates was low and did not exceed the critical value of 5.5ºC.…”

“…8 The high-speed handpieces generated an increase in pulpal tem perature and pressure that decreased with an increase in the thickness of the remaining dentine. 9 Because the wavelength of the Er:YAG (Erbium:Yttrium-Aluminum-Garnet) laser can absolve water and hydroxyapa tite, 10 it can be indicated for the removal of caries and cavity preparations. 11,12 Some Er:YAG laser beams can penetrate to deeper areas than the ablated area; damage of the nerve fibres and terminals might be a mechanism of pain reduction in cavity ablation with Er:YAG laser.…”

An In Vitro Comparison of the Bond Strength of Composite to Superficial and Deep Dentin, Treated With Er:YAG Laser Irradiation or Acid-Etching

“…[18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] Previous reports have claimed that there are certain advantages in bonding to lased dentin because of an apparently enlarged surface area for adhesion based on the scaly and flaky surface appearance following Er:YAG irradiation. [33][34][35] In a study, the shear bond strength in deep lased dentin was better than in superficial lased dentin. 36 In addition, acid etching the previously laser-conditioned dentin surfaces has proved to be an effective technique.…”