[Show abstract][Hide abstract] ABSTRACT: In dental health care, the application of ultrashort laser pulses enables dental tissue ablation free from thermal side effects, such as melting and cracking. However, these laser types create undesired micro- and nanoparticles, which might cause a health risk for the patient or surgeon. The aim of this study was to investigate the driving mechanisms of micro- and nanoparticle formation during ultrashort pulse laser ablation of dental tissue. Time-resolved microscopy was chosen to observe the ablation dynamics of mammoth ivory after irradiation with 660 fs laser pulses. The results suggest that nanoparticles might arise in the excited region. The thermal expansion of the excited material induces high pressure in the surrounding bulk tissue, generating a pressure wave. The rarefaction wave behind this pressure wave causes spallation, leading to ejection of microparticles.
[Show abstract][Hide abstract] ABSTRACT: The aim of the study was to investigate the efficiency of caries removal employing an ultrashort pulsed laser (USPL) and to compare the results regarding to the ablation rate of sound enamel and dentin including surface texture. The study was performed with 59 freshly extracted carious human teeth. Two cavities with an edge length of 1 × 1 mm per tooth were created: one in the dental decay and one in sound hard tissue. For this purpose a 9-W Nd:YVO4 laser with a center wavelength of 1,064 nm and a pulse duration of 8 ps at a repetition rate of 500 kHz was used. A scanner system moved the laser beam across the surface with a scan speed of 2,000 mm/s. Ablated volume and roughness R z of the cavity ground were measured using an optical profilometer. Subsequently, the specimens were cut to undecalcified sections for histological investigations. The removal of dental decay (dentin, 14.9 mm(3)/min; enamel, 12.8 mm(3)/min) was significantly higher (p < 0.05) compared to the removal of sound tissues (dentin, 4.2 mm(3)/min; enamel, 3.8 mm(3)/min). The arithmetic means of the surface roughness R z were 8.5 μm in carious enamel, 15.43 μm in carious dentin, 4.83 μm in sound enamel and 5.52 μm in sound dentin. Light microscopic investigations did not indicate any side effects in the surrounding tissues. Regarding the ablation rate of dental decay using the USPL system, caries removal seems to be much more efficient for cavity preparation.
No preview · Article · May 2014 · Lasers in Medical Science
[Show abstract][Hide abstract] ABSTRACT: Clinical surveys show a continuous increase of antimicrobial resistance related to the frequency of the administrated medication. The antimicrobial photodynamic therapy (aPDT) is an effective adjuvant to reduce the need of antibiotics in dentistry, especially in periodontics. The antimicrobial effect of lightactivated photosensitizers in periodontics is demonstrated in clinical studies and case reports. Indocyanine green (ICG) as a new adjuvant shows the high potential of antiphlogistic and antimicrobial effects in combination with laser-light activation. In trying to answer the question of just how far the influence of temperature is acting on bacteria, this study was carried out. The influences of ICG at different concentrations (0.01 up to 1 mg/ml) in combination with a culture medium (brain-heart-infusion) and a bacteria culture (Streptococcus salivarius) at different optical densities (OD600 0.5 and 0.1) were investigated under laser-light activation. Laser activation was carried out with diode laser at 810 nm and two different power settings (100 mW/300 mW). The pulse repetition rate was 2 kHz. Taking account of the fiber diameter, distance and spot size on the sample surface, the applicated intensities were 6.2 and 18.7 W/cm2. Total irradiation time was 20 s for all meaurements. Transmitted laser power and temperature increase in the culture medium as well as in the bacteria culture were determined. Additionally the influence of ICG regarding bacterial growth and bactericidal effect was investigated in the bacteria culture without laser irradiation. Without laser, no bactericidal effect of ICG was observed. Only a bacteriostatic effect could be proved. In dependence of the ICG concentration and the applied intensities a temperature increase of ΔT up to 80°C was measured.
[Show abstract][Hide abstract] ABSTRACT: Ultrashort pulsed lasers (USPLs) represent a new generation of laser systems in the field of biophotonical applications. In terms of a pilot project, the study was carried out to evaluate the ablation parameters of bone tissue regarding the medical use of such a laser technology in dentistry. Specimens from ribs of freshly slaughtered pigs were assembled and irradiated with an USP Nd:YVO4 laser (pulse duration 8 ps at 1,064 nm with repetition rates between 50 and 500 kHz) using eligible average output powers in the range of 3.5-9 W and fluences between 1 and 2.5 J/cm(2). Square-shaped cavities of 1-mm edge length in the bone compacta were created employing a scanner system. Cavities were analyzed with an optical profilometer to determine the ablated volume. Ablation rate was calculated by the ablated volume and the recorded irradiation time by the scanner software. Additionally, samples were examined histologically to investigate side effects of the surrounding tissue. Formed cavities showed a precise and sharp-edged appearance in bone compacta. Optimized ablation rate of 5.2 mm(3)/min without any accompanying side effects was obtained with an average output power of 9 W, a pulse repetition rate of 500 kHz, and an applied fluence of 2.5 J/cm(2). Provided that the used laser system will be advanced and adjusted for clinical applications, the outcome of this study shows auspicious possibilities for the use of USPL systems in the preparation of bone tissue.
No preview · Article · Jan 2014 · Lasers in Medical Science
[Show abstract][Hide abstract] ABSTRACT: Modern ultrashort pulse lasers with scanning systems provide a huge set of parameters affecting the suitability for dental applications. The present study investigates thresholds and ablation rates of oral hard tissues and restorative materials with a view towards a clinical application system. The functional system consists of a 10 W Nd:YVO4 laser emitting pulses with a duration of 8 ps at 1,064 nm. Measurements were performed on dentin, enamel, ceramic, composite, and mammoth ivory at a repetition rate of 500 kHz. By employing a scanning system, square-shaped cavities with an edge length of 1 mm were created. Ablation threshold and rate measurements were assessed by variation of the applied fluence. Examinations were carried out employing a scanning electron microscope and optical profilometer. Irradiation time was recorded by the scanner software in order to calculate the overall ablated volume per time. First high power ablation rate measurements were performed employing a laser source with up to 50 W. Threshold values in the range of 0.45 J/cm(2) (composite) to 1.54 J/cm(2) (enamel) were observed. Differences between any two materials are statistically significant (p < 0.05). Preparation speeds up to 37.53 mm(3)/min (composite) were achieved with the 10 W laser source and differed statistically significant for any two materials (p < 0.05) with the exception of dentin and mammoth ivory (p > 0.05). By employing the 50 W laser source, increased rates up to ∼50 mm(3)/min for dentin were obtained. The results indicate that modern USPL systems provide sufficient ablation rates to be seen as a promising technology for dental applications.
No preview · Article · Apr 2013 · Lasers in Medical Science
[Show abstract][Hide abstract] ABSTRACT: Ultra-short pulsed laser (USPL) systems for dental application have
overcome many of their initial disadvantages. However, a problem that
has not yet been addressed and solved is the beam delivery into the oral
cavity. The functional system that is introduced in this study includes
an articulated mirror arm, a scanning system as well as a handpiece,
allowing for freehand preparations with ultra-short laser pulses. As
laser source an Nd:YVO4 laser is employed, emitting pulses
with a duration of tp < 10 ps at a repetition rate of up
to 500 kHz. The centre wavelength is at 1064 nm and the average output
power can be tuned up to 9 W. The delivery system consists of an
articulated mirror arm, to which a scanning system and a custom made
handpiece are connected, including a 75 mm focussing lens. The whole
functional system is compact in size and moveable. General
characteristics like optical losses and ablation rate are determined and
compared to results employing a fixed setup on an optical table.
Furthermore classical treatment procedures like cavity preparation are
being demonstrated on mammoth ivory. This study indicates that freehand
preparation employing an USPL system is possible but challenging, and
accompanied by a variety of side-effects. The ablation rate with fixed
handpiece is about 10 mm3/min. Factors like defocussing and
blinding affect treatment efficiency. Laser sources with higher average
output powers might be needed in order to reach sufficient preparation
No preview · Article · Mar 2013 · Proceedings of SPIE - The International Society for Optical Engineering
[Show abstract][Hide abstract] ABSTRACT: Due to the high intensities of USP laser radiation, the interaction with
matter is always attended with a plasma formation. Therefore the
surrounding tissue can be influenced by heat generation and additional
light emission from the UV up to the near and mid infrared. In dentistry
it is of importance that the treatment of bone and soft tissues, i.e.
oral mucosa, with a USP laser should not cause any kind of morphological
changes on the cell level leading to a delayed wound healing or cell
mutation. HaCaT keratinocyte cells were used for epidermal (soft tissue)
and MG-63 osteoblast-like cells for hard tissue (bone) modelling. Cell
growing was realized on glas cover slips. Irradiation was carried out
with a USP Nd:YVO4 laser having a center wavelength at 1064 nm. Based on
the pulse duration of 8 ps and a pulse repetition rate of 500 kHz the
laser emits an average power of 9 W. For efficiency testing of cell
removal on glas cover slips, 1, 5, 25, 50 and 75 repetitions of the
scanning pattern (scan loops) were used. Heat distribution during laser
irradiation was measured with an infrared camera system. Subsequently
haematoxylin staining and SEM investigations were used to analyse the
morphological changes. Differences of cell removal efficiency were
observed with repetitions <=25. Irradiated areas with repetitions
>=50 were cell-free. Additionally, repetitions >=25 showed side
effects for both cell lines. Cell destruction in both cell lines could
be verified using the haematoxylin staining and the SEM pictures.
No preview · Article · Jan 2013 · Proceedings of SPIE - The International Society for Optical Engineering
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to screen CO(2) laser (10.6 μm) parameters to increase enamel resistance to a continuous-flow erosive challenge.
A new clinical CO(2) laser providing pulses of hundreds of microseconds, a range known to increase tooth acid-resistance, has been introduced in the market. Methods: Different laser parameters were tested in 12 groups (n=20) with varying fluences from 0.1 to 0.9 J/cm(2), pulse durations from 80 to 400 μs and repetition rates from 180 to 700 Hz. Non-lased samples (n=30) served as controls. All samples were eroded by exposure to hydrochloric acid (pH 2.6) under continuous acid flow (60 μL/min). Calcium and phosphate release into acid was monitored colorimetrically at 30 sec intervals up to 5 min and at 1 min intervals up to a total erosion time of 15 min. Scanning electron microscopic (SEM) analysis was performed in lased samples (n=3). Data were statistically analysed by one-way ANOVA (p<0.05) and Dunnett's post-hoc tests.
Calcium and phosphate release were significantly reduced by a maximum of 20% over time in samples irradiated with 0.4 J/cm(2) (200μs) at 450 Hz. Short-time reduction of calcium loss (≤1.5 min) could be also achieved by irradiation with 0.7 J/cm(2) (300μs) at 200 and 300 Hz. Both parameters revealed surface modification.
A set of CO(2) laser parameters was found that could significantly reduce enamel mineral loss (20%) under in vitro erosive conditions. However, as all parameters also caused surface cracking, they are not recommended for clinical use.
Full-text · Article · Mar 2012 · Photomedicine and laser surgery
[Show abstract][Hide abstract] ABSTRACT: During ablation of oral hard tissue with an USPL system a small amount
of the incident laser power does not contribute to the ablation process
and is being transmitted. Partial transmission of ultra-short laser
pulses could potentially affect the dental pulp. The aim of this study
was to assess the transmission during ablation and to deduce possible
risks for the patient. The study was performed with an Nd:YVO4 laser,
emitting pulses with a duration of 8 ps at a wavelength of 1064 nm. A
repetition rate of 500 kHz and an average power of 9 W were chosen to
achieve high ablation efficiency. A scanner system created square
cavities with an edge length of 1 mm. Transmission during ablation of
mammoth ivory and dentin slices with a thickness of 2 mm and 5 mm was
measured with a power meter, placed directly beyond the samples. Effects
on subjacent blood were observed by ablating specimens placed in contact
to pork blood. In a separate measurement the temperature increase during
ablation was monitored using an infrared camera. The influence of
transmission was assessed by tuning down the laser to the corresponding
power and then directly irradiating the blood. Transmission during
ablation of 2 mm specimens was about 7.7% (ivory) and 9.6% (dentin) of
the incident laser power. Ablation of specimens directly in contact to
blood caused coagulation at longer irradiation times (t~18s). Direct
irradiation of blood with the transmitted power provoked bubbling and
smoke formation. Temperature measurements identified heat generation as
the main reason for the observed coagulation.
No preview · Article · Feb 2012 · Proceedings of SPIE - The International Society for Optical Engineering
[Show abstract][Hide abstract] ABSTRACT: The exposition of nanoparticles caused by laser application in dental
health care is an open discussion. Based on the fact that nanoparticles
can penetrate through the mucosa, the knowledge about particle
characteristics after irradiation with an USPL is of high importance.
Therefore, the aim of this study was to investigate the particle
characteristics, especially the size of the ablated debris after USPL
irradiation. The irradiation was carried out with an USP Nd:YVO4 laser
with a center wavelength of 1064 nm. Based on the pulse duration of 8 ps
and a pulse repetition rate of 500 kHz the laser emits an average power
of 9 W. The materials investigated were dental tissues and dental
restorative materials (composite and amalgam), ceramic and different
metals (gold and aluminium). The samples were irradiated with a power
density in the order of 300 GW/cm2 at distances of 5, 10, 15,
and 20 mm. The debris was collected on an object plate. SEM pictures
were used for analysis of the ablation debris. Depending on the
irradiated material, we observed different kinds of structures:
vitreous, flocculent, and pellet-like. The mean particle sizes were 10 x
10 up to 30 x 30 μm2. In addition, a cluster of ablated
matter (nanometer range) distributed over the whole irradiated area was
found. With increasing distances the cluster structure reduced from
multi-layer to mono-layer clusters. Particle sizes in the micrometer and
nanometer range were found after irradiation with an USPL. The
nanoparticles create a cluster structure which is influenced by
No preview · Article · Feb 2012 · Proceedings of SPIE - The International Society for Optical Engineering
[Show abstract][Hide abstract] ABSTRACT: In this paper we describe a novel, erbium laser-assisted whitening method, TouchWhiteTM, which pertains to chemical strategies for removing tooth stains by means of laser-activated aqueous gels or pastes. The TouchWhiteTM method makes use of the fact that the Er:YAG laser wavelength has a water absorption peak in the vicinity of 3 μm. Since water is the major component of the aqueous bleaching gels, this eliminates the need for any additional absorbing particles in the bleaching gels. More importantly, taking into account thermal burden considerations, the TouchWhiteTM procedure represents the most effective and least invasive laser-assisted tooth whitening method possible. Due to its high absorption in bleaching gels, the Er:YAG laser beam is fully absorbed in the gel and does not penetrate to the hard tissue or the pulp. All of the laser energy is thus effectively used for the heating of the gel. There is no direct heating of the dental tissue and the pulp, as is the case with other laser-assisted whitening methods. As a consequence, the procedure can be performed with a minimal undesirable thermal burden on the tooth, and the tooth whitening speed can be safely increased by 5 - 10 times.
[Show abstract][Hide abstract] ABSTRACT: The success of endodontic treatment depends on the effective elimination of microorganisms from the root canal, and lasers provide more effective disinfection than conventional treatment using rinsing solutions. The objective of this in vitro study was to determine the bactericidal effect of laser irradiation in dentine of various depths at a wavelength of 1,064 nm and pulse durations of 15 and 25 ms. A total of 90 dentine slices were cut from bovine incisors and divided into two groups (45 slices each) of thickness 500 and 1,000 μm. All were inoculated with a suspension of Enterococcus faecalis (5.07 × 10(9) bacteria/ml). Based on the clinically accepted dose (approximately 300 J/cm(2)), the following laser settings were chosen for this study: 1.75 W, 0.7 Hz for 4 s, three repetitions. The two groups were divided into two subgroups of 15 slices each to be irradiated with pulse durations of 15 and 25 ms. The remaining 15 slices per group were not irradiated to serve as a control. After irradiation, the colony-forming units (CFU) were counted and evaluated. To determine the bactericidal effect of irradiation with different pulse durations, the results in the different groups were compared statistically. For all irradiated subgroups a bactericidal effect was observed at pulse durations of 15 and 25 ms (p=0.0085 and p<0.0001). The corresponding average log kills were 0.29 (15 ms) and 0.52 (25 ms) for 500 μm and 0.15 and 0.3 for 1,000 μm, respectively. The results of this in vitro study showed that Nd:YAG laser irradiation with a pulse duration of 15 ms eliminated an average of 49% and 29% of E. faecalis at dentine depths of 500 μm and 1,000 μm, respectively, and irradiation with a pulse duration of 25 ms eliminated 70% (500 μm) and 50% (1,000 μm). However, these values are lower than those achieved with the established protocol using microsecond pulses.
Full-text · Article · Jan 2011 · Lasers in Medical Science
[Show abstract][Hide abstract] ABSTRACT: For medical applications, erbium lasers are usually equipped with articulated mirror arms or special glass fibers. However, only with mirror arms is it so far possible to transmit high average powers or pulse energies in the region of 1 J to achieve suitable energy densities for fast tissue preparation. An alternative to the glass fiber systems mentioned above are liquid-core light guides. An extremely flexible liquid-core light guide was used to connect a dental Er:YAG laser system to an especially adapted dental laser applicator. The core liquid was continuously circulated during laser irradiation to transmit pulse energies up to 1.1 J. A modified laser handpiece was used for exemplary clinical treatment. The experimental setup with the highly flexible light guide was completed successfully, and its ease of handling for a dental surgeon was demonstrated in the clinical treatment of leukoplakia of the oral cheek mucosa. Complete ablation of the epithelium with the laser was performed. One year postoperatively, the patient remains disease-free. This article describes the technical realization of a liquid-core light guide system for medical applications. We report about the first successful clinical treatment of oral hyperkeratosis using this new light guide technology.
No preview · Article · Sep 2010 · Lasers in Medical Science
[Show abstract][Hide abstract] ABSTRACT: The use of an erbium:YAG laser in arthroscopic surgery has the advantage of a precise treatment of soft tissue. Due to the high absorption in water, the laser energy is perfectly matched to smoothing the hydrous, fibrillated articular cartilage surface. In minimal invasive surgery, the workspace is filled with aqueous liquids for enlargement. This appears contrary to the absorption characteristics of erbium:YAG laser radiation in water. The purpose of this study was to evaluate the ablated volume per pulse of cartilage lesions and the potential side effects including thermal damage and tissue necrosis.
Twenty-four osteochondral specimens of porcine knee joints were irradiated with an Er:YAG laser completely submerged in water, with distances to the cartilage surface of 1, 3 and 5 mm and pulse durations of 75 and 100 microseconds. To keep a constant peak power of approximately 6 kW, pulse energies of 450 and 580 mJ were used at a pulse repetition rate of 15 Hz. After a histological preparation, ablated volumes, depths, and widths of the cuts were investigated. Additionally, laser protocols were correlated with different markers of cartilage tissue damage and apoptosis.
Ablation could be observed for every measurement. The influence of the distance showed a statistical significance (P < 0.001) for the volume, depth, and width of the cuts. For the pulse duration, statistical significance (P < 0.001) was found only for the volume and the depth. We observed no loss of proteoglycan or collagen type II. The total cell number, cell morphology, and number of apoptotic cells in an area close to the cutting edge and in a corresponding unaffected area of the same specimens revealed no differences regardless of the applied protocol.
The use of an Er:YAG laser demonstrates the successful application in liquid environments for cartilage removal without any damage of the surrounding tissue.
No preview · Article · Nov 2009 · Lasers in Surgery and Medicine
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to determine the amount of intra-canal dentine removed with an erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser using different endodontic tips and different power settings. Ninety intact extracted bovine teeth were selected as samples. After sectioning the roots and preparing the testing cylinders, we divided the samples into three main groups (A, B, C), with further subdivision of each group to be irradiated with three different powers (1500 mW, 1750 mW and 2000 mW). An Er,Cr:YSGG laser system (2.78 microm, 140 micros, 20 Hz and 65% water to 35% air ratio) was used for irradiation, and the loss of intra-canal dentine mass was calculated by the difference between the initial and final sample masses. Data were analysed with Kolmogorov-Smirnov, analysis of variance (ANOVA) and Tukey tests. At a significance level of alpha = 1%, the results showed statistically significant differences (P < 0.0001) between different tip groups, regarding both the ablation rate and the ablation efficiency criteria. With regard to the three irradiation power settings, statistically significant difference were recorded only between groups C and A, for the ablation rate criteria. The intra-canal ablation ability of the Er,Cr:YSGG laser improved with increasing power and/or tip diameter. The latter exhibited a stronger influence on ablation rate and efficiency. Laser intra-canal ablation is an important addition to the field of endodontics; nevertheless, further investigations and system improvements are required.
Full-text · Article · Jul 2009 · Lasers in Medical Science
[Show abstract][Hide abstract] ABSTRACT: The desire for perfect and white teeth can be accomplished in aesthetical dentistry by modern tooth bleaching methods. Within the scope of a clinical study, laser assisted in-office bleaching was applied to the teeth of 20 individual patients with a neodymium:yttrium-aluminum-garnet (Nd:YAG) laser (lambda = 1.064 microm, average power 4 W, pulse repetition rate 10 Hz, pulse duration 320 micros). The treatment was carried out in a split-mouth design, each patient having two appointments with 1 week in between. Laser activation of the bleaching agent was performed on teeth 14-11 and 34-31 per session, with a total irradiation time of 30 s per tooth. The initial and the final color of the teeth were ascertained by VITA Colorsticks and the dental chromatometer ShadeEye NCC. Whitening was detected in the laser-activated and in the non-activated quadrants. Statistical evaluation showed that the additional activation of the bleaching agent by the Nd:YAG laser had produced no significant influence on the whitening (P > 0.05). The results achieved in this study should be scrutinized critically. They give cause for one to reconsider the treatment conditions or the laser parameters used, or even to query the application of the Nd:YAG laser in general during in-office bleaching.
No preview · Article · May 2009 · Lasers in Medical Science
[Show abstract][Hide abstract] ABSTRACT: Although CO(2) laser irradiation can decrease enamel demineralisation, it has still not been clarified which laser wavelength and which irradiation conditions represent the optimum parameters for application as preventive treatment. The aim of the present explorative study was to find low-fluence CO(2) laser (lambda = 10.6 microm) parameters resulting in a maximum caries-preventive effect with the least thermal damage. Different laser parameters were systematically evaluated in 3 steps. In the first experiment, 5 fluences of 0.1, 0.3, 0.4, 0.5 and 0.6 J/cm(2), combined with high repetition rates and 10 micros pulse duration, were chosen for the experiments. In a second experiment, the influence of different pulse durations (5, 10, 20, 30 and 50 micros) on the demineralisation of dental enamel was assessed. Finally, 3 different irradiation times (2, 5 and 9 s) were tested in a third experiment. In total, 276 bovine enamel blocks were used for the experiments. An 8-day pH-cycling regime was performed after the laser treatment. Demineralisation was assessed by lesion depth measurements with a polarised light microscope, and morphological changes were assessed with a scanning electron microscope. Irradiation with 0.3 J/cm(2), 5 micros, 226 Hz for 9 s (2,036 overlapping pulses) increased caries resistance by up to 81% compared to the control and was even significantly better than fluoride application (25%, p < 0.0001). Scanning electron microscopy examination did not reveal any obvious damage caused by the laser irradiation.
[Show abstract][Hide abstract] ABSTRACT: Seit nunmehr fast 20 Jahren werden Neodymium-Laser sowohl in der dentalen Praxis als auch in der Zahntechnik eingesetzt. In diesem Artikel werden die technisch-physikalischen Aspekte dieser Geräteklasse vorgestellt. Unter anderem werden die chemischen Eigenschaften des Laserkristalles und das allgemeine Funktionsprinzip beschrieben. Des Weiteren werden Lichtübertragungssysteme wie z. B. Fasern oder Spiegelgelenkarme sowie die zugehörigen Handstückausführungen erörtert.
[Show abstract][Hide abstract] ABSTRACT: This preliminary study was to investigate in vitro the Er,Cr:YSGG laser ablation capability, both range (enlargement aspects of laser tips corresponded to conventional endodontic files) and quality (removing of smear layer and opening of dentinal tubules) to clean and shape the root canal for final obturation step. The crowns of 15 extracted multi-rooted posterior human teeth were resected, and then 15 canals were prepared by an Er,Cr:YSGG laser up to 1.5 W (actual power output) using the step-back technique, while the other 15 canals (control) were enlarged conventionally by K-flex file. The results revealed that posterior root-canal preparation could be achieved by laser beam transmitted to the canal using endodontic tips. At a chosen significance level of alpha = 1%, the results showed no significant statistical difference between the two groups (P > 0.01). Considering the results of this current study, laser-based root-canal preparation still shows certain limitations, and further improvements are mandatory for higher achievement and better preparation outcomes.
Full-text · Article · Dec 2007 · Lasers in Medical Science