- Review of Literature for Er,Cr:YSGG lasers in Endodontics
Total elimination of bacteriafrom infected root-canal systems remains the most important
objective of endodontic therapy. However, in spite of a plethora of new products and
techniques, achieving this objective continues to elude our profession. Historically,
endodontic treatment focused on root canal disinfection with “entombment” of
remainingbacteria within dentinal tubules and inaccessible areas of the root-canal system.
Although many factors have been implicated in the etiology of endodontic failures, it has
become evident that these “entombed” bacteria play a pivotal role in the persistence of
endodontic disease (Siqueira et al, 2008). With the introduction of Cone Beam CT, it has
been reported that from 30% to 75% of radiographically successful endodontic-treated
teeth show signs of Apical Periodontitis when viewed with CBCT (Wu et al, 2009;
Estrela et al, 2008)In teeth where reduced size of the existing radiolucency was
diagnosed by radiographs and considered to represent periapical healing,
enlargement of the lesion was frequently confirmed with CBCT (Wu et al, 2009).
Although impressive results have been obtained in vitro, laser energy alone has not been
able to achieve total bacterial kill in extracted teeth. From a clinical perspective, it is
apparent that a combination of different treatment modalities will be required in order to
eventually be able to sterilize root canal systems. In addition, many clinical obstacles
exist that further complicate the clinician’s ability to achieve this goal. These include, but
are not limited to: restricted endodontic access, complex root-canal anatomy, limitations
of irrigation and instrumentation techniques, inability to entomb bacteria, and the
inability to reach and eliminate bacteria deep within the tooth structure.
The erbium, chromium-doped yttrium, scandium, gallium and garnet (Er,Cr:YSGG)
laser, operating at a wavelength of 2,780 nm, has been suggested as a valuable toolin
endodontics. Since this wavelength is very similar to the absorption maximum of water in
hydroxyapatite, photo-ablation occurs where water evaporates instantaneously, thereby
ablating the surrounding tissue. Gordon et al (2007)postulated that it was possible to
achieve expansion and collapse of intratubular water as deep as 1000μm or more into
dentin.This micropulse-induced absorption was capable of producing acoustic waves
sufficiently strong to remove smear layer, disrupt biofilm and kill intratubular
bacteria.These findings are significant, as bacteria have been identified in dentin at depths
of 1100μm, with E. faecalis at depths of 800μm (Kouchi et al, 1980; Haapasalo and
Orstavik, 1987). Irrigants such as sodium hypochlorite have a limited effect on these
bacteria with penetration depths of only 100μm into dentinal tubules (Berutti et al, 1997).
Smear Layer Removal:
Smear layer (SL) removal is considered to be an important requisite of successful
endodontic treatment. By increasing dentin permeability,SL removal enhances the
penetration of intracanal medicaments and laser energy into dentin. In addition, SL
removal facilitates penetration of sealers into the dentinal tubules. Yamada et al (1983)
have extolled the virtue of smear layer removal and how it promotes a better apical seal
due to sealer penetration into dentinal tubules.
Studies have shown incomplete removal of SL from the root canal walls, particularly in
the apical third, when chemo-mechanical preparation was used (Takeda et al, 1999;
Aktener and Bilkay, 1993). Extensive research has been performed into the use of the
Er,Cr:YSGG laser for smear layer removal in root canal systems. As early as 2004,
Ishizaki et al reported that laser irradiation at 5W using a 400μmfiber was efficient for
removing smear layer and debris without melting or carbonization, while preserving the
apical stop. In order to obtain a better understanding of the working mechanism of the
Er,Cr:YSGG laser in endodontics, Blanken and Verdaasdonk (2007), using specialized
imaging techniques, suggested that the working mechanism can be attributed to cavitation
effects inducing high speed fluid motions into and out of the canal. Franzen et al (2009)
using a 200μm fiber at 0.25W at 20Hz showed absence of SL and open tubules, with
intertubular dentin more ablated than peritubular dentin.
The development of the radial-firing laser tip (Biolase Technology, Inc.), with a tip shape
that emits the laser energy as a broad cone, allowed better coverage of the root-canal
walls than end-firing tips. George et al (2008) studied side-firing, conical-ended optical
fibers when Er:YAG and Er,Cr:YSGG lasers were used in root canals in which thick
smear layers were created to provide a challenge for the laser system. Lasing improved
the action of EDTAC in removing SL. Conical fibers performed better than plain fibers
but there was no difference in performance between the 2 laser systems when matched
for all other parameters. These results provided a “proof of concept” for lateral emitting
fibers for endodontic procedures. In a later paper, George and Walsh (2010) determined
that laterally emitting, conical fiber tips could be used safely under defined conditions for
intracanal irradiation without harmful thermal effects on the periodontal apparatus. This
was in agreement with the thermal findings of Schoop et al in 2007. Schoop et al (2009),
using a 200μm radial-firing tip (RFT2) at 3W, found most dentinal tubules exposed with
no signs of cracking or melting. They concluded that the beam expansion by the conical
tip geometry favored homogeneous energy distribution along the root canal walls.
When comparing laser-activated irrigation (LAI) to passive ultrasonic irrigation (PUI)
and conventional irrigation (CI), De Moor et al (2009) found that LAI was statistically
significantly more effective in removing artificially placed dentin debris in a root canal
than PUI and CI.In a follow-up study in 2010 the same authors evaluated the efficacy of
ultrasonic versus laser-activated irrigation to remove artificially placed dentin debris
plugs. They found that LAI techniques using erbium lasers (Er:YAG or
Er,Cr:YSGG) for 20 seconds (4 X 5 seconds) at 75mJ and 20Hz to be statistically
better than PUI for 20 seconds and as efficient as PUI with the intermittent flush
technique for 60 seconds (3 X 20 seconds).Peeters et al (2011) found duration of laser
irradiation to be more important than the size of apical enlargement. Placing the 600μm
tip above the pulp chamber and activating at 1W and 35Hz, completely clean canals were
found after irradiation for 60 seconds. Irradiation for 30 seconds had similar results to
PUI.Juric et al (2014) compared the antimicrobial efficacy of Er,Cr:YSGG laser-activated
irrigation with PUI and RinsEndo against intracanal E. faecalis. They found no
difference among the three active irrigation techniques, which were all significantly more
effective than the conventional syringe irrigation. LAI did, however, generate more
negative bacterial samples.
Peeters and De Moor (2015) measured pressure changes during laser-activated irrigation
by the Er,Cr:YSGG laser, during continuous irrigation in the pre-enlarged canal.The laser
power used and the distance between the tip and the apex affected the magnitude of the
apical fluid pressure. The shape of the emitting tip did not affect the pressure produced at
the apex. The overall mean magnitude of the pressure changes developed using LAI at
0.75 and 1.75 W was comparable with the lymphatic capillary pressure when the tip was
placed at the cervical margin. When looking at obturation of root canal systems in fifty
two canals, Varella and Pileggi (2007) evaluated the number of canals and isthmuses
obturated after Er,Cr:YSGG laser treatment for 40 seconds at 1.5W and 20Hz. They
found that the laser-treated canalshad a statistically significant greater number of
lateral canals/isthmuses obturated than canals flooded with 17% EDTA for 3
minutes.
Ozer and Basaran (2013) evaluated microleakage of root canal fillings irradiated with
different output powers of Er,Cr:YSGG laser. They found the 1W and 2W settings were
most effective for debris and SL removal, exposing dentinal tubules in middle and apical
canal thirds and preventing microleakage statistically better than 2.5W irradiation or 17%
EDTA. Mohammadi et al (2013) studied the effect of Er,Cr:YSGG pretreatment on bond
strength of fiber posts to root canal dentin using a self-adhesive resin cement and found
that laser pretreatment significantly increased post retention.
In a recent, ground-breaking paper published by Al-Karadaghi et al (2015), the authors
compared the effectiveness of a dual wavelength (2780 nm Er,Cr:YSGG, 940 nm diode)
laser in the elimination of SL, comparing it with Er,Cr:YSGG alone, in terms of radicular
dentin permeability and ultrastructural changes of root canal walls. Dye permeation in
the dual wavelength laser group was significantly higher over the whole root length:
cervical, middle, andapical compared to the Er,Cr:YSGG laser group and non-irradiated
samples (p < 0.001). This translates to a significant increase in dentin permeability
with the dual laser group.Scanning electron micrographs of dual wavelength irradiated
samples showed a total removal of smear layer with preservation of the annular structure
of dentinal tubules. There was no sign of melting and carbonization.Er,Cr:YSGG laser
root canal irradiation produced uneven removal of smear layer and inefficient cleanliness,
especially in the apical third. These findings were consistent with those of Silva et al
(2010) in which Er,Cr:YSGG laser with 0.75 W average power produced uneven removal
of smear layer. Some area of insufficient cleanliness and absence of melting and
carbonization was observed due to irregular irradiation. Dentin permeability for all root
thirds was statistically similar to control group (non-irradiated samples).
Root Canal Disinfection
While the erbium laser has been shown to be extremely effective in smear layer removal
in root canals, its ability to disinfect root canals has been questioned. Jha and colleagues
(2006)conducted a study examining the antimicrobial effects of the Er,Cr:YSGG laser.
They concluded that the “Er,Cr:YSGG laser instrumentation was [not] able to eliminate
an E. faecalis infection in root canals” and that “the laser was completely ineffective in
disinfecting root canals when sterilesaline was used as an irrigation solution.”In the Jha
and colleaguesstudy, the researchers recovered residual viable bacteria after laser
treatment of infected root dentin by collecting dentin shavings from the root canal wall.
They then transferred dentin shavings to broth tubes and incubated them. The
development of turbidity was taken as evidence of bacteria survival of the lasing
treatment. However, this model is not quantitative in the sense that a single surviving
bacterial cell from the infected dentinwould give precisely the same result as would a
million surviving organisms: in both cases, the tube receiving the infected dentin
shavings turned turbid following incubation. Therefore, according to this model, it
would be impossible to determine whether any reduction (disinfection) of the
bacterial population had occurred.
When comparing the bactericidal effect of different lasers, Gutknecht et al,in a series of
studies (1997 – 2002), reporteda bacterial kill rate (at a depth of 1000μm into dentin)of
only 38.6% for the Er,Cr:YSGG laser compared with 84.8% for the Nd:YAG, 63.9% for
the diode (810nm) and 13.9% for the Er:YAG.
Studies with the 200μm radial firing tip (RFT2 tip) showed more promising bacterial kill
rates. Gordon et al (2007) reported a disinfection reduction of 99.71% for E. faecalis at a
dentin thickness of approximately 200μm. They found that bacterial recovery decreased
when laser duration or power increased and when operating in the dry mode. Schoop et
al (2009)reported very high bacterial kill rates for E. coli and E. faecalisbut the sample
size was small and the teeth were only incubated for 4 hours prior to laser irradiation
resulting in a lack of penetration of the test bacteria into the dentinal tubules. Franzen et
al (2009) studied the decontamination of deep dentin by means of Er,Cr:YSGG laser
irradiation. Despite low pulse energy of 3.13mJ, the laser irradiation resulted in
significant bacterial reduction up to a dentin thickness of 500μm (p < 0.05). Arnabat et al
(2010) compared the antimicrobial effect of Er,Cr:YSGG laser with that of sodium
hypochlorite at various concentrations in root canals experimentally colonized with E.
faecalis.The use of NaOCl 5% was the most effective procedure, with NaOCl 0.5% being
the least effective; however, laser treatment was as effective as NaOCl 5% when
applied at 2 W for 60 s.
For root canal irrigation to be effective, the irrigant solution needs to reach the end of the
root canal, create a current and continuously replenish itself and carry away un-dissolved
debris (Chow, 1983). In many cases however, air is trapped at the end of the root canal,
creating an apical vapor lock. This in turn, prevents the irrigant from reaching the critical
apical third of the root canal.Ultrasonics, hand files, rotary instrumentation or paper
points will not dislodge this vapor lock. Apical negative pressure irrigation as well as
laser-activated irrigation will eliminate this vapor lock. Peeters and De Moor (2014)
studied the mechanism by which laser-activated irrigation removed the vapor lock.
Laser-activated irrigation overcame the airlock effect by releasing air trapped in the air
column. The mechanism underlying the removal of trapped air from the apical region
using an Er,Cr:YSGG laser in a dry root canal is via the disruption of the surface tension
at the solution-air interface. This disruption, caused by bubble implosion(cavitation),
displaced air in the form of bubbles from the apical region toward the solution, which
allowed the solution to travel apically.
When comparing bacterial reduction in straight and curved canals using Er,Cr:YSGG
laser treatment versus a traditional irrigation technique with sodium hypochlorite,
Dewsnup et al (2010) reported that the laser reached higher sterilization levels in straight
canals (all samples) than in curved canals but no statistical significance was found
between all groups. On a cellular level, Lopez-Jimenez et al (2014) used atomic force
microscopy visualization of injuries in E. faecalis cells caused by Er,Cr:YSGG and diode
lasers. They concluded that the Er,Cr:YSGG laser at 2W of power was the most effective
in the extent of injuries and damage to bacterial cell surfaces.
Dual Wavelength Laser
While the erbium lasers have a high affinity for water and are therefor extremely efficient
in removing smear layer, they are rapidly absorbed and have little penetration into dentin.
Diode lasers, however, are selectively absorbed by pigment (melanin and hemoglobin)
and are relatively unaffected by water. This affords the diode laser greater penetration
through dentin with little interaction with it, making it possible to act on microorganisms
deeper in the dentinal tubules.
Recent research has been conducted on the effectiveness of a dual wavelength laser (2780
nm Er,Cr:YSGG, 940 nm diode) in endodontic treatment. In 2013, Gutknecht and
Franzen reported a 99.9% bactericidal effect at a depth of 1000μm in dentin using dual
laser therapy. Al-Karadaghi et al used thermocouples to record temperature elevation
during root canal treatment with a dual wavelength laser and found the temperature
elevation on the external root surface along the apical, middle and coronal thirds to be
below the periodontium critical limit (7°C). Franzen et al (2015)evaluated the
intrapulpal thermal changes that occurred during the treatment of the root surfaces with a
laser system emitting Er,Cr:YSGG 2780- and 940-nm diode laser irradiation in an
alternating sequence.They found that the combined laser emission of 2780 and 940 nm
was a promising way for root surface debridement without inducing intrapulpal thermal
damage when using an appropriate water/air spray. All measured temperatures were
considerably below the critical value of 5.6°C.Al-Karadaghi et al (2015) compared the
effectiveness of a dual wavelength (2780 nm Er,Cr:YSGG, 940 nm diode) laser in the
elimination of smear layer, comparing it with Er,Cr:YSGG alone, in terms of radicular
dentin permeability and ultrastructural changes of root canal walls. They reported a
significant increase in dentin permeability with the dual laser group,with no sign of
melting and carbonization. These results reflect a major paradigm shift in laser-assisted
endodontic therapy and further studies will be needed to determine if dual lasers will
improve clinical outcomes.
Clinical Outcome Studies
To date, very few endodontic laser outcome studies have been reported in the literature.
Martins et al (2014) published a blind, randomized and controlled clinical study that
compared a laser-assisted endodontic treatment using an erbium,chromium:yttrium- scandium-gallium-garnet (Er,Cr:YSGG) laser and radial firing tips (RFT) versus the
conventional use of 3% sodium hypochlorite and interim calcium hydroxide paste, in
teeth with chronic apical periodontitis. Their findings suggest that for single-rooted and
premolar teeth, this laser-assistedprotocol can achieve predictable endodontic outcomes,
comparable to conventional strategies, in 1 year of follow-up.
Conclusion
The introduction of CBCT has highlighted the fact that recurrent/persistent endodontic
disease is more prevalent than previously reported. In addition, it has illustrated that
many lesions of endodontic origin are larger than they appear on standard dental
radiographs and that their healing takes significantly longer when evaluated in 3-D.
While many different factors can influence healing, it is now evident that bacteria left
behind in root canal systems play a pivotal role in the recurrence of endodontic
disease as well as the incomplete healing of endodontic lesions. A large body of
evidence supports the positive role of the Er,Cr:YSGG laser in smear layer removal,
increased dentin permeability as well as root canal and dentin disinfection. The ongoing
research into dual wavelength, laser-assisted endodontic therapy is extremely promising
and may change significantly the way endodontic treatment is performed in the near
future.
References
1. Siqueira JF Jr, Rôças IN.Clinical implications and microbiology of bacterial
persistence after treatment procedures.J Endod. 2008 Nov;34(11):1291-
1301.
2. Wu MK. Shemesh H. Wesselink PR. Limitations of previously published
systematic reviews evaluating the outcome of endodontic treatment. Int
Endod J,2009;42;656-666.
3. Estrela C, Bueno MR, Leles CR, Azevedo B, Azevedo JR. Accuracy of cone beam
computed tomography and panoramic and periapical radiography for
detection of apical periodontitis.J Endod. 2008;34:273–279.
4. Gordon W, Atabakhsh VA, Meza F, Doms A, Nissan R, Rizoiu I, Stevens RH.The
antimicrobial efficacy of the erbium, chromium:yttrium-scandium-gallium- garnet laser with radial emitting tips on root canal dentin walls infected with
Enterococcus faecalis. J Am Dent Assoc. 2007 Jul;138(7):992-1002.
5. Kouchi Y, Ninomiya J, Yasuda H, Fukui K, Moriyama T, Okamoto H.Location of
Streptococcus mutans in the dentinal tubules of open infected root canals. J
Dent Res. 1980 Dec;59(12):2038-46.
6. Haapasalo M, Orstavik D.In vitro infection and disinfection of dentinal
tubules.J Dent Res. 1987 Aug;66(8):1375-9.
7. Berutti E, Marini R, Angeretti A.Penetration ability of different irrigants into
dentinal tubules.J Endod. 1997 Dec;23(12):725-7.
8. Yamada RS, Armas A, Goldman M, et al. A scanning electron comparison of a
high volume final flush with several irrigating solutions. J Endod 1983;9:137.
9. Takeda FH, Harashima T, Kimura Y, Matsumoto K.A comparative study of the
removal of smear layer by three endodontic irrigants and two types of
laser.Int Endod J. 1999 Jan;32(1):32-9.
10. Aktener BO, Bilkay U.Smear layer removal with different concentrations of
EDTA-ethylenediamine mixtures.J Endod. 1993 May;19(5):228-31.
11. Ishizaki NT, MatsumotoK, Kimura Y, Wang X, Kinoshita J, Okano SM,
Jayawardena JA. Thermographical and morphological studies of Er,Cr:YSGG
laser irradiation on root canal walls. Photomed Laser Surg. 2004
Aug:22(4):291-7.
12. Blanken JW, and Verdaasdonk RM. Cavitation as working mechanism of the
Er,Cr:YSGG laser in endodontics: a visualization study. J Oral Laser Appl.
2007;(7):97-106.
13. Franzen R, Esteves-Oliveira M, Meister J, Wallerang A, Vanweersch L,
Lampert F, Gutknecht N.Decontamination of deep dentin by means of erbium,
chromium:yttrium-scandium-gallium-garnet laser irradiation. Lasers Med
Sci. 2009 Jan;24(1):75-80.
14. George R, Meyers IA, Walsh LJ.Laser activation of endodontic irrigants with
improved conical laser fiber tips for removing smear layer in the apical third
of the root canal. J Endod. 2008 Dec;34(12):1524-7.
15. George R, Walsh LJ. Thermal effects from modified endodontic laser tips used
in the apical third of root canals with erbium-doped yttrium aluminium
garnet and erbium, chromium-doped yttrium scandium gallium garnet lasers.
Photomed Laser Surg. 2010 Apr;28(2):161-5.
16. Schoop U, Goharkhay K, Klimscha J, Georgopoulos A, Sperr W, Moritz A. The
use of the erbium, chromium:yttrium-scandium-gallium-garnet laser in
endodontic treatment: the results of an in vitro study. J Am Dent Assoc. 2007
Jul;138(7):949-55.
17. Schoop U, Barylyak A, Goharkhay K, Beer F, Wernisch J, Georgopoulos A,
Sperr W, Moritz A. The impact of an erbium, chromium:yttrium-scandium- gallium-garnet laser with radial-firing tips on endodontic treatment. Lasers
Med Sci 2009 Jan;24(1):59-65.
18. De Moor RJ, Blanken J, Meire M, Verdaasdonk R. Laser induced explosive
vapor and cavitation resulting in effective irrigation of the root canal. Part 2:
evaluation of the efficacy. Lasers Surg Med. 2009 Sep;41(7):520-3.
19. De Moor RJ, Meire M, Goharkhay K, Moritz A, Vanobbergen J. Efficacy of
ultrasonic versus laser-activated irrigation to remove artificially placed
dentin debris plugs. J Endod. 2010 Sep;36(9):1580-3.
20. Peeters HH, Suardita K.Efficacy of smear layer removal at the root tip by
using ethylenediaminetetraacetic acid and erbium, chromium: yttrium,
scandium, gallium garnet laser. J Endod. 2011 Nov;37(11):1585-9.
21. Bago Jurič I, Plečko V, Anić I.Antimicrobial efficacy of Er,Cr:YSGG laser- activated irrigation compared with passive ultrasonic irrigation and
RinsEndo(®) against intracanal Enterococcus faecalis. Photomed Laser Surg.
2014 Nov;32(11):600-5.
22. Peeters HH, De Moor RJ.Measurement of pressure changes during laser- activated irrigant by an erbium, chromium: yttrium, scandium, gallium,
garnet laser.Lasers Med Sci. 2015 Jul;30(5):1449-55.
23. Varella CH, Pileggi R.Obturation of root canal system treated by Cr, Er: YSGG
laser irradiation.J Endod. 2007 Sep;33(9):1091-3.
24. Özer SY, Basaran E.Evaluation of microleakage of root canal fillings irradiated
with different output powers of erbium, chromium:yttrium-scandium- gallium-garnet laser.Aust Endod J. 2013 Apr;39(1):8-14.
25. Mohammadi N, Savadi Oskoee S, Abed Kahnamoui M, Bahari M, Kimyai S,
Rikhtegaran S.Effect of Er,Cr:YSGG pretreatment on bond strength of fiber
posts to root canal dentin using a self-adhesive resin cement.Lasers Med Sci.
2013 Jan;28(1):65-9.
26. Al-Karadaghi TS, Franzen R, Jawad HA, Gutknecht N.Investigations of
radicular dentin permeability and ultrastructural changes after irradiation
with Er,Cr:YSGG laser and dual wavelength (2780 and 940 nm) laser. Lasers
Med Sci. 2015 May 3. [Epub ahead of print]
27. Jha D, Guerrero A, Ngo T, Helfer A, Hasselgren G.Inability of laser and rotary
instrumentation to eliminate root canal infection. J Am Dent Assoc. 2006
Jan;137(1):67-70.
28. Klinke T, Klimm W, Gutknecht N. Antibacterial effects of Nd:YAG laser
irradiation within root canal dentin.J Clin Laser Med Surg. 1997
Feb;15(1):29-31.
29. Moritz A1, Gutknecht N, Goharkhay K, Schoop U, Wernisch J, Sperr W.In vitro
irradiation of infected root canals with a diode laser: results of microbiologic,
infrared spectrometric, and stain penetration examinations.Quintessence Int.
1997 Mar;28(3):205-9.
30. Arnabat J, Escribano C, Fenosa A, Vinuesa T, Gay-Escoda C, Berini L, Viñas
M.Bactericidal activity of erbium, chromium:yttrium-scandium-gallium- garnet laser in root canals. Lasers Med Sci. 2010 Nov;25(6):805-10.
31. Chow TW.Mechanical effectiveness of root canal irrigation. J Endod. 1983
Nov;9(11):475-9.
32. Peeters HH, De Moor RJ, Suharto D.Visualization of removal of trapped air
from the apical region in simulated root canals by laser-activated irrigation
using an Er,Cr:YSGG laser.Lasers Med Sci. 2015 Aug;30(6):1683-8.
33. Dewsnup N, Pileggi R, Haddix J, Nair U, Walker C, Varella CH.Comparison of
bacterial reduction in straight and curved canals using erbium,
chromium:yttrium-scandium-gallium-garnet laser treatment versus a
traditional irrigation technique with sodium hypochlorite. J Endod. 2010
Apr;36(4):725-8.
34. Lopez-Jimenez L, Arnabat J, Vinas M, Vinuesa T. Atomic force microscopy
visualization of injuries in Enterococcus faecalis surface caused by
9
Er,Cr:YSGG and diode lasers. 2014;Med Oral Patol Oral Cir Bucal.
Doi:10.4317/medoral.19991
35. Franzen R, Rashidisangsary B, Ozturan S, Vanweersch L, Gutknecht N.
Intrapulpaltemperature changes during root surface irradiation with dual- wavelength laser (2780 and 940 nm): in vitro study. J Biomed Opt. 2015
Jan;20(1):018002.
36. Al-Karadaghi TS, Franzen R, Jawad HA, Gutknecht N.Investigations of
radicular dentin permeability and ultrastructural changes after irradiation
with Er,Cr:YSGG laser and dual wavelength (2780 and 940 nm) laser. Lasers
Med Sci. 2015 May 3. [Epub ahead of print]
37. Martins MR, Carvalho MF, Pina-Vaz I, Capelas JA, Martins MA, Gutknecht
N.Efficacy of Er,Cr:YSGG laser with endodontical radial firing tips on the
outcome of endodontic treatment: blind randomized controlled clinical trial
with six-month evaluation. Lasers Med Sci. 2013 Jul;28(4):1049-55.
38. Martins MR, Carvalho MF, Pina-Vaz I, Capelas JA, Martins MA, Gutknecht
N.Outcome of Er,Cr:YSGG laser-assisted treatment of teeth with apical
periodontitis: a blind randomized clinical trial. Photomed Laser Surg. 2014
Jan;32(1):3-9.
Endodontic State of Art (Dr Kolnick).pdf
Open with Lumin PDF
Page 2 of 9 Page 1 of 9