Open Access
Add to BibSonomy
Abstract
We report on using a CO2 (10.6 µm) laser to debond the lithium disilicate veneers. Sixty-four sound human premolar teeth and 64 veneer specimens were used in the study. The zigzag movement via CO2 laser handpiece along with an air-cooled jet to prevent temperature elevation above the necrosis temperature limit (5.5 C°) was applied. The optimal deboning irradiation time was super-fast, at about 5 seconds at 3 Watt CO2 laser power. It is 20 times less than any previously published work for veneers debonding. The enamel beneath the debonded veneers has been assessed by atomic force microscopy (AFM) and shear stress technique as criteria for the easiness of debonding. The fast deboning process with nonsignificant changes in enamel integrity and tooth vitality reflects the high potential of CO2 laser in veneers debonding.
© 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement
1. Introduction
Veneers, crowns, other adhesive restorations, removable and fixed prostheses, tooth whitening, and dental Implants are common practices in esthetic dentistry [1]. Currently, Emax veneers can help with various cosmetic issues, including teeth discoloration, hypocalcified teeth, peg-shaped lateral teeth, dental fluorosis, teeth fracture, and diastema closure [2]. On the other side, sometimes, veneer removal is compulsory for many reasons, such as microleakage of luting resin cement, discoloration, and fracture of restoration margins, which limits the longevity of veneers [3]. Normally the veneers are secured firmly to the enamel surface by light or dual-cured resin cement [4]; this makes the traditional removal method involving grinding with high-speed turbines difficult, annoying to the patient, time-consuming, and may cause damage to the tooth because it is hard to discriminate between veneer, cement, and tooth structure [5,6]. Unlike electrical heating devices which rely on bracket adhesive softening, lasers seem to have more potential in metal-free restorations, where it is considered one of the methods to deliver a controlled quantity of heat energy [7,8]. Most frequently Erbium lasers family (Er,Cr:YSGG, and Er:YAG lasers) have been used to debond Emax veneers [9–11]. Many studies have used various types of lasers (CO2, Nd: YAG, diode Er:YAG, yttrium fiber, and Tm: Yap lasers) for debonding ceramic brackets by lowering the shear bond strength of the ceramic brackets [5,12–14]. All the aforementioned laser types require a long time to debond the veneer and may affect the underlying enamel surface. The far-infrared CO2 laser found a wide range of applications in dentistry, both in hard and soft tissue. Intraoral procedures with CO2 laser have been started since the first demonstration of this laser in 1960 [15]. Subsequently, the major use of the CO2 laser was directed to soft tissue, where this 10.6 µm laser seems a promising surgical scalpel. Moreover, its appropriate long wavelength to be absorbed in soft tissue and its rapid wound coagulation feature attracts many applications in laser soft tissue surgery. The many advantages of this laser, such as safety, a bloodless field during surgery, less time, no suturing, and almost reduced postoperation requirements make it a potential tool for managing these conditions [16]. The employment of CO2 lasers for cutting, incision, and holes can be regarded as practical, efficient, and simple to perform [17]. The CO2 laser was used for excision in oral and implant surgery, soft tissue incision, removal of precancerous lesions, and surgical pre-prosthetic procedures [18,19]. The availability of commercially high output power CO2 laser, in addition to its good wavelength absorption with the soft tissue, found important applications in frenectomies for orthodontic reasons [20], removal of hyperplastic tissues that surround orthodontic brackets [21], in gingivoplasty and gingivectomy [22], de-epithelialization purpose in periodontal tissue regeneration [23], in gingival recontouring and soft tissue crown lengthening [24], for removal of soft tissue mucocele [25], excision of premalignant lesions for biopsy or ablation [26], uncovering implant of submerged implants and in case of peri-implantitis for removal of hyperplastic soft tissue around the implant [27]. Moreover, the CW CO2 laser was applied to inhibit bacteria related to dental implant infection with about complete reduction of the bacteria count [28]. On the other hand, CO2 laser applications in dental hard tissue are still limited. Nevertheless, its application found great benefits, such as in debonding ceramic orthodontic brackets via decreasing the adhesion force between the enamel and ceramic bracket [29]. CO2 laser debonding of a ceramic bracket may not cause iatrogenic enamel damage [30]. A super pulse CO2 laser can potentially replace the conventional debonding ceramic brackets by lowering the debonding force [31]. Occlusion of dentinal tubules to reduce dentin permeability as a new treatment method via the combined CO2 laser and hydroxyapatite paste (nanoparticle) [32]. Silver diamine fluoride enhanced by CO2 laser irradiation was tested as a caries preventive approach [33]. Shear bond strength test reveals a significant improvement to the surface of acrylic dentures irradiated by CO2 laser [34]. Fractional CO2 laser was used in dental materials to promote the shear bond strength of the zirconia-porcelain interface [35]. Also, the super pulsed CO2 laser with 9.6 µm wavelengths has recently gained much interest in dental cavity preparation [36]. Though CO2 laser has many potential advantages in dental hard tissue, veneer debonding has not gained much attention. Among the very few published work related to the veneer debonding by CO2 laser was an in vitro study to evaluate the lithium disilicate veneers debonding from dentine surface [37]. Still, a more detailed investigation concerning the debonding time, laser power, irradiated tooth structure and morphology, and temperature elevation during the debonding process is considered necessary. In the present work, a continuous wave (CW) 10.6 µm CO2 laser has been used to debond lithium disilicate veneers for the first time to the best of the authors’ knowledge. The time required to perform debonding process has been determined for different power settings. The optimized debond time for the lithium disilicate veneer (Emax) from the enamel surface was unpreceded by about 5 seconds at 3 Watt power level, which is more than twenty times faster than with Erbium lasers. No significant changes in the underneath enamel's surface were observed. Also, temperature elevation has been monitored continuously before, during, and after the CO2 laser irradiation process. The experiments were accompanied by the use of cold air stream coupled with a CO2 laser handpiece and directed to the irradiated tooth to avoid temperature rise above the necrosis limit of 5.5 C° [38].
2. Material and methods
2.1 Samples grouping
In this in-vitro study, 64 specimens were used and divided into two main groups. First, the temperature change group (TC) comprises 36 samples and is subdivided into three subgroups (each one with n = 12 teeth): TC1, TC2, and TC3 correspond to 1,2,3 W CO2 laser power and 24,9,5 seconds debonding times, respectively.
The shear bond strength test has been carried out for the irradiated and non-irradiated samples. The shear bond strength group (S) consists of 28 samples subdivided into four groups (n = 7): S1, S2, and S3 correspond to 1,2,3, W laser power, and 24,9,5 second, respectively. SC represents the control group without laser irradiation
2.2 Samples preparation
Sixty-four sound human premolar teeth extracted for orthodontic purposes have been used in this experiment. Deposits, attached bone, and soft tissue, were removed using an ultrasonic scaler and polished with fluoride-free polishing paste, then stored in normal saline until used.
An access cavity to the pulp chamber is prepared from the occlusal aspect of the teeth for the placement of the thermocouple sensor.
For easy handling, the teeth roots were embedded in self-cure acrylic resin blocks by using a custom-made silicon mold; this process is achieved by using a dental surveyor to ensure the correct position and alignment of the tooth inside the mold during the acrylic setting.
Labial surfaces of the teeth were prepared for receiving flat lithium disilicate veneer specimens by preparing depth-orientation grooves with a depth preparation bur. Then, mark these grooves with a pencil and prepare the surface by parallel-sided diamond fissure bur with a high-speed handpiece without exceeding the depth-orientation grooves to provide a flat surface within the enamel. Finally, the labial surfaces were finished and polished with fluoride-free polishing paste and a rubber cup.
Sixty-four ceramic blocks of dimensions (4*6 mm and 0.7 mm thickness) ± 0.05 mm fabricated from lithium disilicate (IPS E.max Press, Ivoclar Vivadent, Schaan, Liechtenstein) in the dental laboratory according to manufacturer’s instruction, the outer surfaces of specimens were glazed. The dimensions were measured by a digital vernier caliper.
According to standardized protocols for cementation, the veneers, and teeth were prepared for the bonding procedure.
The enamel surfaces were etched with 37% phosphoric acid etching gel (Ivoclar Vivadent, Schaan, Liechtenstein) for 30 s, washed thoroughly with a water jet, and dried with air. Then bonding agent (Tetric N-Bond, Ivoclar Vivadent) was applied with a bonding brush and cured for 20 seconds.
The veneers were etched with 4.5% IPS Ceramic hydrofluoric acid (Ivoclar Vivadent, Schaan, Liechtenstein) that was applied by bonding brush for 20 seconds, then, washed thoroughly with water spray for 30 seconds and dried with an air jet then the veneers silanized with Monobond N (Ivoclar Vivadent, Schaan, Liechtenstein) for 120 seconds then disperse the remaining excess with air spray. Variolink Esthetic LC light curing cement (Ivoclar Vivadent, Schaan, Liechtenstein) was applied on the veneer which was then placed on the enamel surface with light finger pressure by one operator for all specimens, remove excess cement by light curing of the excess with polymerization light for 2 seconds (light intensity ≥500 mW/cm2) (curing pen, Eighteeth) then removed by dental explorer, after that the veneers light cured for 20 seconds. the samples were stored in distilled water in an incubator (Memmert) at 37 C° for 48 hours before debonding process.
2.3 Design setup and laser debonding
The laser used in performing the study was CW CO2 laser; it has an output wavelength of 10600 nm with an output power of up to 40 W in a continuous wave regime (Ultra Dream Pulse Surgical CO2 system, DS-40U, Daeshin Enterprise Co., Ltd., Korea), spot size (0.2 mm).
The tooth was fixed during the irradiation procedure by a metal fixation machine. The tip of the laser handpiece was positioned at about 1 mm distance from the ceramic veneers perpendicular to the surface, and the zigzag configuration with horizontal movements was performed. The setup of the experiment is shown in Fig. (1). The thermocouple sensor was placed inside the pulp chamber of the fixed tooth. This chamber was filled with thermally conductive paste to enhance thermocouple performance. Light cure composite filling material was used to isolate the sensor tip. The electrical cooling device (chiller) outlet tube was fixed by a holder 2 cm away from the veneer at 45 degrees to cool the tooth. The temperature was recorded at three points (room temperature to about 30 C°, cooling temperature to 20 C°, and temperature after the irradiation process).
The shear bond strength was conducted to evaluate the quality of the debonding process. In addition to the control subgroup(SC), the subgroups S1, S2, and S3, (at the same applied laser parameters and exposure time) were examined by the shear bond strength test using a universal testing machine (Electronic Universal Testing Machine, Beijing Jinshengxin Testing Machine Co., Ltd, China), with 0.5 mm/min speed of crosshead.
The debonded samples by the shear test were examined under an optical stereomicroscope (Euromex Microscopic Reflection/Transmission, Holand) at a 10X magnification. Adhesive remnant index (ARI) described by Artun et, al. [39] was used to evaluate the mode of failure for the debonded samples according to the following scale:
0: No resin cement remains on the tooth surface.
1: Less than half of the resin cement remains on the tooth surface.
2: More than half of the resin cement remains on the tooth surface.
3: All the resin cement remains on the tooth surface.
2.4 Surface morphology of the enamel and chemical composition
To characterize the teeth’ thickness, roughness, structure, and morphology, the prepared samples were analyzed with atomic force microscopy (AFM) and field emission scanning electron microscope (FESEM). Figure (2) depicts the AFM (Nanoscope IIIa contact-mode microscopy, Angstrom Advanced Inc., USA). The captured image of a sound tooth sample indicates uniformity, and homogeneity, with a root-mean-square height roughness of about 24.73 nm.
The fast Fourier transform analysis has been used to analyze the 2d power spectrum of images. The peaks initiated due to noise were removed by the notch filter. The histogram distribution for height was plotted as shown in Fig. 2(c). All specimens were stored in distilled water to simulate the moist condition of the oral environment. In the present in vitro study, an air-cooled jet was applied to the tooth during the CO2 irradiation to control the temperature increase. The enamel tooth surface treated with CO2 laser (Fig. (3(a), and (b)), shows regular and no deep scratch marks typical of wear and tear.
Fig. 3. AFM image of enamel tooth surface treated with CO2 laser sample: (a) 3D, (b) 2D, (c) extracted profile, and (d) histogram.
The important features on each histogram reflect the surface regularity. The enamel surface treated with CO2 laser showed a histogram of Gaussian distribution as shown in Fig. 3(d). The tail lengths are different from the left side to the right side of the histogram, inducing scratches that appear in the micrograph Fig 3(c). A Root-mean-square height roughness(RMS) of 0.3110 µm was recorded for the enamel tooth surface treated with a CO2 laser.
Figure (4) represents the tooth after debonding of veneer and cement removed by sandblast. The AFM image indicates uniformity, and homogeneity, with a Root-mean-square height roughness of about 146 nm. This shows that the roughness is symmetrical around the peak value. Hence, CO2 laser treatment produced the smoothest regular enamel surface.
Fig. 4. AFM image of enamel tooth surface after debonding of veneer and cement removed by sandblast: (a) 3D, (b) 2D, (c) Extracted profile, and (d) histogram.
2.5 Chemical composition
First, the Fourier transform infrared (FTIR) test using (FTIR-8400, SHIMADZU, 25000.00 nm- 2500.00 nm). was carried out for the veneer and the cement. The FTIR spectra that have been shown in Figs. (5(c), and (d) reveal that CO2 laser (10.6 µm) wavelength has only 35% transmission through the veneer, while Er,Cr:YSGG (2.79 µm) has 78% transmission. In other words, the veneer and resin cement will absorb most of the laser power. Eventually, only a tiny fraction of the applied CO2 laser power reaches the enamel; this gives much superiority of CO2 laser in comparison to Er,Cr:YSGG laser in keeping the tooth vital.
Fig. 5. FTIR (a) tooth enamel after debonding of veneer by CO2 laser (b) sound tooth (c) Lithium disilicate veneer (d) resin cement.
3. Statistical analysis
Data description, analysis, and presentation were performed using Statistical Package for Social Science (SPSS version -22, Chicago, Illionis, USA).
4. Results
The optimized values for the laser exposure time with different CW CO2 laser power to achieve successful debonding/ removal of veneers are as follows: 1 W, 2W, and 3W laser power corresponding to 24, 9, and 5 seconds, respectively. This ultrashort time for the debonding process is unpreceded in all previous investigations. Still, for more confidence, a preliminary experiment on veneer debonding by an Er,Cr:YSGG was conducted. The recorded debonded time was 106 sec. 34 E.max veneers of a total of 36 samples were removed successfully manually by dental explorer after laser irradiation directly. After debonding, no changes in the underlying enamel were observed, as indicated by the FTIR test for both the sound tooth and the one after debonding of veneer by CO2 laser as shown in Fig. (5(a) and (b).
As well as the roughness of the tooth, according to the AFM test did not affect by the residual CO2 laser power, where the majority of power was consumed to heat the veneer and melt the resin cement. In all cases, the cement was easily scratched off from the enamel surface as well as from the inner aspect of the veneer with a dull instrument. The powerful cooling system was adapted to the experiment to cool down the irradiated tooth before and during irradiation. The tooth temperature was set to 20 C° in all deboned veneers.
A shear bond strength test has been carried out for the irradiated and non-irradiated (control group) teeth with veneers. Data distribution for temperature changes and shear bond strength were evaluated using the Shapiro–Wilk test; results show that the data are normally distributed among groups at p > 0.05.
The mean values of temperature change (°C) and shear bond strength, and the respective standard deviation and standard error values are shown in Tables 1,2, and Figs. (6 and 7).
Table 1. Descriptive and statistical test of temperature among groupsa
Table 2. Descriptive and statistical test of SBS among groupsa
All CO2 laser powers causing an excessive increase in temperature (above 3 W) were excluded from the laser debonding process. At 3 W laser power, the recorded temperature was the lowest, furthermore, multiple pairwise comparisons using Tukey's HSD showed a significant difference between 1 W and 3 W only while differences between other groups as 1 W × 2 W and between 2 W × 3 W are not significant. The temperature changes as a function of exposure times are shown in Fig. (8. Though temperature elevation is a crucial factor in all dental procedures and many sophisticated sensors have been employed [40] to measure the temperature, still needs to be manipulated. Any temperature increase during the laser irradiation period was compensated by the cooled air jet keeping the temperature below the necrosis limit of 5.5 C°. The Shear Bond Strength (SBS) was the highest in the control group; then it decreased sharply with the irradiated samples. Plus, multiple pairwise comparisons for Shear bond strength using Dunnett's T3 post hoc show that there is a significant difference of laser groups between each other and with the control group except between 1 W × control group; this result is statistically not significant. The mean measured values for the SBS test were (15.985 MPa in the control group, 0.984 MPa at 3 W, 2.762 MPa at 2W, 5.743 MPa at 1W). the shear bond strength changed dramatically after the laser and with power change as shown in Fig. (9.
To assess the adhesive failure, the adhesive remnant index (ARI) test was performed using an optical microscope; scores distribution between the four groups were shown in Fig. 10.
The ARI scores for the laser groups (SP1, SP2, SP3) were higher than the control group (SC). In SP1, SP2, and SP3, most of the samples were of score 2. While in SC, the majority were of score 1.
5. Discussion
The most common method for removing all-ceramic restorations is to use a high-speed handpiece [41]. With this technique, removing veneers without harming the underlying tooth structure is a challenge and time-consuming. Many dentists currently face a difficult task when they need to replace existing all-porcelain restorations. They would welcome alternative means that could safely, reliably, and fast debond porcelain restorations without possibly causing further damage to the underlying tooth structure. Laser debonding of ceramic brackets is documented in the literature [7,30,42–48], As a potential part of the laser’s spectrum, CO2 laser with its long wavelength of 9-11 µm may be one of the candidates to assist the debonding process. Generally, the laser interaction with matter involves heating, melting, and vaporization depending on how much the laser energy/power is. In CW lase mode, the focusing condition is the main parameter that should be adapted well for the intended application. The laser intensity increases as far as the laser beam spot size decreases. This long wavelength CO2 laser with a peak wavelength of 10.6 µm may decrease the adhesion of ceramic brackets to enamel, facilitating bracket debonding [29]. Unfortunately, the published research relating to the debonding of PLVs by lasers is still few and poorly covered. On the other hand, the well-adapted laser for most hard dental tissue was used in most investigations on debonding ceramic laminates [49–52]. There are only a few studies in which other types of lasers, such as CO2 and diode lasers used to debond ceramic laminates. In the current investigation, the main goal was to evaluate the potential of CW CO2 (10.6 µm) laser applied at three different powers (1, 2, and 3 W) as a conservative debonding technique for laminate veneers. The power parameters chosen for this investigation were optimized after conducting multiple preliminary tests. CO2 laser radiation was applied perpendicularly onto the veneers. The mechanisms behind debonding the veneers include heating and melting. Different mechanisms were proposed to explain the interaction of laser radiation with veneer, resin cement, and tooth. The suggested mechanisms are thermal softening which is a purely heat-dependent mechanism, thermal ablation includes rapid heating and vaporization of the resin, and the third mechanism is photoablation which normally occurs via the chemical interaction between the laser light and the atoms of the resin. So, the fast veneer’s debonding time with CO2 laser might be attributed to the photothermal softening of the resin cement, giving both the dentist and the patient more comfort and distress as well as keeping the integrity of the treated tooth. The interaction occurs and causes shrinkage to the adhesive cement. Simple calculations rely on the FTIR spectrum (Fig. 5(c)) which reveals that the absorption percentage of CO2 wavelength in lithium disilicate veneer is about 65% and 22% for Er,Cr:YSGG wavelength (2.8µ). Consequently, the rest transmitted laser light will get absorbed by the resin cement. Only a very few percentages will reach the underlying enamel. This of course will give more protection for the tooth. After a superfast time of about 5 seconds, the veneers were debonded at a moderate power of 3 W. To avoid any possible necrosis, a thermocouple sensor was positioned inside the pulp chamber to monitor the temperature change instantaneously to maintain a safe tooth temperature below the necrosis limit of less than 5.5 C°. An experiment has been conducted to compare the potential of CO2 laser to Er,Cr:YSGG laser. The debonding of veneers was performed using Er,Cr:YSGG laser at laser parameters of 2.5 Watt, 25 Hz, MZ6. The veneers were debonded successfully but with a long time of about 106 sec, comparable to the previously published work [53]. On the other side, the pulpal temperature rise was measured in vitro without considering the effect of pulpal blood flow, ignoring the role of circulating blood in lowering the temperature [54,55]. Thermal diffusion in the tooth depends on the temperature gradient, and the accumulated heat due to laser irradiation may be successfully dissipated out of the tooth by efficient air or water cooling [56,57]
An auxiliary cold air jet coupled with the CO2 laser handpiece has been used to lower temperature before and during the CO2 laser irradiation process. The ambient cooling temperature of 20 C° was fixed for all samples to avoid temperature elevation of the irradiated teeth. The first trial was started without cooling, and the temperature was significant. While with the aid of cold air jet under different CO2 laser irradiation powers, the temperature changes were insignificant.
FTIR spectroscopy for the sound tooth and the one after debonding of veneer (Fig. 5(a), and (b)) proved that there was no change to the underlying tooth structure.
The mean debonding shear test values recorded in the three experimental groups were 5.743, 2.762, and 0.984 MPa, respectively. A manual veneer removal without laser irradiation (SC) required much more force about 15.985 MPa.
The ARI is crucial in giving a clue idea about the condition of the treated tooth. It is an index for measuring the amount of residual adhesive left on the enamel surface after debonding. The enamel-adhesive approaches to debonding location increased enamel damage risk [58]. Most of the samples of laser groups (S1, S2, S3) within scores 2 and 3 means that most of the cement remained on the tooth enamel surface; this indicates that less enamel damage was likely because most of the resin cement stayed on the tooth enamel surface. At the same time, most of the control group (SC) samples were within scores 1 and 2. In addition, the enamel surface of 2 teeth was subjected to sand blast (20 Psi, 50 microns) applying dental sandblaster (Vario basic, Renfert) after debonding of veneer and viewed under a stereomicroscope to check the possibility of any microcrack formation. It was found that the enamel surface remains sound without cracks. The sound enamel after debonding of veneer by CO2 laser and removal of resin cement by ultrasonic scaler on one sample and another by sandblast were subjected to the AFM test (Fig. 3 and 4), which also revealed no changes to the underlying tooth structure.
6. Conclusion
The results have shown a very fast debonding process (5 sec) without any remarkable increase in temperature or damage to the enamel surface; this indicates a safe procedure for veneer debonding can be applied using the CO2 laser, especially with laser power 3 W with complete control of temperature rise during the process in parallel with the cold air jet.
Acknowledgments
This work was supported by the Ministry of Higher Education and Scientific Research (MOHESR), University of Baghdad (UoB).
Disclosures
The authors declare no conflicts of interest.
Data availability
Data underlying the results presented in this paper is not publicly available at this time but may be obtained from the authors upon reasonable request.
References
1. M. Blatz, G. Chiche, O. Bahat, R. Roblee, C. Coachman, and H. Heymann, “Evolution of aesthetic dentistry,” J. Dent. Res. 98(12), 1294–1304 (2019). [CrossRef]
2. P. Magne, J. Hanna, and M. Magne, “The case for moderate “guided prep” indirect porcelain veneers in the anterior dentition. The pendulum of porcelain veneer preparations: from almost no-prep to over-prep to no-prep,” Eur J Esthet Dent 8(3), 376–388 (2013).
3. P. Kursoglu and H. Gursoy, “Removal of fractured laminate veneers with Er: YAG laser: report of two cases,” Photomed. Laser Surg. 31(1), 41–43 (2013). [CrossRef]
4. P. Runnacles, G. M. Correr, F. Baratto Filho, C. C. Gonzaga, and A. Y. Furuse, “Degree of conversion of a resin cement light-cured through ceramic veneers of different thicknesses and types,” Braz. Dent. J. 25(1), 38–42 (2014). [CrossRef]
5. D. Nalbantgil, M. O. Oztoprak, M. Tozlu, and T. Arun, “Effects of different application durations of ER:YAG laser on intrapulpal temperature change during debonding,” Lasers Med. Sci. 26(6), 735–740 (2011). [CrossRef]
6. I. I. Al-Rawi, “Fracture strength of laminate veneers using different restorative materials and techniques (A comparative in vitro study),” (2014).
7. T. Ma, R. D. Marangoni, and W. Flint, “In vitro comparison of debonding force and intrapulpal temperature changes during ceramic orthodontic bracket removal using a carbon dioxide laser,” American Journal of Orthodontics and Dentofacial Orthopedics 111(2), 203–210 (1997). [CrossRef]
8. A. Obata, “Effectiveness of CO∼ 2 laser irradiation on ceramic bracket debonding,” J. Japan Orthodontic Society 54, 285–295 (1995).
9. C. K. Morford, N. C. Buu, B. M. Rechmann, F. C. Finzen, A. B. Sharma, and P. Rechmann, “Er:YAG laser debonding of porcelain veneers,” Lasers Surg. Med. 43(10), 965–974 (2011). [CrossRef]
10. N. A. Zanini, T. F. Rabelo, C. B. Zamataro, A. Caramel-Juvino, P. A. Ana, and D. M. Zezell, “Morphological, optical, and elemental analysis of dental enamel after debonding laminate veneer with Er, Cr:YSGG laser: A pilot study,” Microsc. Res. Tech. 84(3), 489–498 (2021). [CrossRef]
11. H. G. Cifuentes, J. C. Gómez, A. N. L. Guerrero, and J. Muñoz, “Effect of an Er, Cr: YSGG laser on the debonding of lithium disilicate veneers with four different thicknesses,” Journal of Lasers in Medical Sciences 11(4), 464–468 (2020). [CrossRef]
12. A. R. Mundethu, N. Gutknecht, and R. Franzen, “Rapid debonding of polycrystalline ceramic orthodontic brackets with an Er: YAG laser: an in vitro study,” Lasers Med. Sci. 29(5), 1551–1556 (2014). [CrossRef]
13. M. O. Oztoprak, D. Nalbantgil, A. S. Erdem, M. Tozlu, and T. Arun, “Debonding of ceramic brackets by a new scanning laser method,” American Journal of Orthodontics and Dentofacial Orthopedics 138(2), 195–200 (2010). [CrossRef]
14. D. Nalbantgil, M. Tozlu, and M. O. Oztoprak, “Pulpal thermal changes following Er-YAG laser debonding of ceramic brackets,” The scientific world journal 2014, 1–4 (2014). [CrossRef]
15. N. Garg, S. Verma, M. Chadha, and P. Rastogi, “Use of carbon dioxide laser in oral soft tissue procedures,” National journal of maxillofacial surgery 6(1), 84 (2015). [CrossRef]
16. S. A. Ismaeel, S. S. Abdulrazaq, and A. A. Alani, “Carbon dioxide laser in the treatment of oral and craniofacial soft tissue lesions, pros and cons,” Indian J. Forensic Medicine & Toxicology 14(4), 3433 (2020).
17. B. A. A. Jaleel and A. S. Mahmood, “Evaluation the effects of CO2 laser on soft and hard tissues (in vitro study),” Iraqi Journal of Laser vol. 13, no. B, pp.13–22 (2014).
18. L. Gáspár, M. Kásler, G. Szabó, and F. Bánhidy, “Separate and combined use of Nd:YAG and carbon dioxide lasers in oral surgery,” J. Clinical Laser Medicine & Surgery 9(5), 381–383 (1991). [CrossRef]
19. L. Gaspar and G. Szabó, “Manifestation of the advantages and disadvantages of using the CO2 laser in oral surgery,” J. Clinical Laser Medicine & Surgery 8(1), 39–43 (1990).
20. R. C. Fiorotti, M. M. Bertolini, J. H. Nicola, and E. Nicola, “Early lingual frenectomy assisted by CO2 laser helps prevention and treatment of functional alterations caused by ankyloglossia,” Int J Orofacial Myology 30(1), 64–71 (2004). [CrossRef]
21. R. Convissar, L. Diamond, and C. Fazekas, “Laser treatment of orthodontically induced gingival hyperplasia,” General dentistry 44(1), 47–51 (1996).
22. R. M. Pick, B. C. Pecaro, and C. J. Silberman, “The laser gingivectomy: the use of the CO2 laser for the removal of phenytoin hyperplasia,” J. Periodontol. 56(8), 492–496 (1985). [CrossRef]
23. M. Israel, C. M. Cobb, J. A. Rossmann, and P. Spencer, “The effects of C02, Nd:YAG and Er:YAG lasers with and without surface coolant on tooth root surfaces: an in vitro study,” J. Clin. Periodontol. 24(9), 595–602 (1997). [CrossRef]
24. T. C. Adams and P. K. Pang, “Lasers in aesthetic dentistry,” Dent. Clin. North Am. 48(4), 833–860 (2004). [CrossRef]
25. W. K. Kopp and H. St-Hilaire, “Mucosal preservation in the treatment of mucocele with CO2 laser,” Journal of oral and maxillofacial surgery 62(12), 1559–1561 (2004). [CrossRef]
26. J. Roodenburg, A. Panders, and A. Vermey, “Carbon dioxide laser surgery of oral leukoplakia,” Oral Surg., Oral Med., Oral Pathol. 71(6), 670–674 (1991). [CrossRef]
27. G. E. Romanos and G. H. Nentwig, “Regenerative therapy of deep peri-implant infrabony defects after CO2 laser implant surface decontamination,” International Journal of Periodontics & Restorative Dentistry 28(3), 245 (2008).
28. F. H. Bayda’a, A. S. Mahmood, E. H. Ali, E. N. Najee, and B. S. Fakhri, “Bactericidal effect of CO2 laser on bacteria associated with dental implant infection: an in vitro study,” Iraqi Journal of Laser 13, 1–6 (2014).
29. D. S. Matos, E. C. Küchler, M. C. Borsatto, M. A. N. Matsumoto, F. V. Marques, and F. L. Romano, “CO2 laser irradiation for debonding ceramic orthodontic brackets,” Braz. Dent. J. 32(2), 45–52 (2021). [CrossRef]
30. M. Iijima, Y. Yasuda, T. Muguruma, and I. Mizoguchi, “Effects of CO2 laser debonding of a ceramic bracket on the mechanical properties of enamel,” The Angle orthodontist 80(6), 1029–1035 (2010). [CrossRef]
31. A. Tehranchi, R. Fekrazad, M. Zafar, B. Eslami, K. A. Kalhori, and N. Gutknecht, “Evaluation of the effects of CO2 laser on debonding of orthodontics porcelain brackets vs. the conventional method,” Lasers Med. Sci. 26(5), 563–567 (2011). [CrossRef]
32. M. A. Al-Maliky, A. S. Mahmood, T. Sardar, et al., “The effects of CO2 laser with or without nanohydroxyapatite paste in the occlusion of dentinal tubules,” The Scientific World Journal (2014).
33. K. Luk, I. S. Zhao, O. Y. Yu, M. L. Mei, N. Gutknecht, and C. H. Chu, “Caries prevention effects of silver diamine fluoride with 10,600 nm carbon dioxide laser irradiation on dentin,” Photobiomodulation, Photomed., Laser Surg. 38(5), 295–300 (2020). [CrossRef]
34. H. K. Aziz, “Effect of the CO2 laser as surface treatment on the bond strength of heat cured soft liner to the high impact acrylic denture base material,” Journal of baghdad college of dentistry 29(1), 20–26 (2017). [CrossRef]
35. A. M. Abdulsatar, B. M. Hussein, and A. M. Mahmood, “Effects of different laser treatments on some properties of the zirconia-porcelain interface,” Journal of Lasers in Medical Sciences 12, e2 (2021). [CrossRef]
36. R. Müllejans, G. Eyrich, W. M. Raab, and M. Frentzen, “Cavity preparation using a superpulsed 9.6-µm CO2 laser—a histological investigation,” Lasers Surg. Med. 30(5), 331–336 (2002). [CrossRef]
37. M. K. Al-maajoun, T. E. Henar, A. E. Tost, and C. A. Terren, “CO2 and Er, Cr: YSGG laser applications in debonding ceramic materials: An in vitro study,” Open J Dent Oral Med 5(3), 25–30 (2017). [CrossRef]
38. L. Zach, “Pulp response to externally applied heat,” Oral Surg., Oral Med., Oral Pathol. 19(4), 515–530 (1965). [CrossRef]
39. J. Årtun and S. Bergland, “Clinical trials with crystal growth conditioning as an alternative to acid-etch enamel pretreatment,” Am. J. Orthod. 85(4), 333–340 (1984). [CrossRef]
40. Z. J. Naeem, A. M. Salman, R. A. Faris, and A. Al-Janabi, “Highly efficient optical fiber sensor for instantaneous measurement of elevated temperature in dental hard tissues irradiated with an Nd: YaG laser,” Appl. Opt. 60(21), 6189–6198 (2021). [CrossRef]
41. G. A. van As, “Using the erbium laser to remove porcelain veneers in 60 seconds,” J Cosm Dent 28, 20–34 (2013).
42. A. S. K. Sarp and M. Gülsoy, “Ceramic bracket debonding with ytterbium fiber laser,” Lasers Med. Sci. 26(5), 577–584 (2011). [CrossRef]
43. K. Hayakawa, “Nd: YAG laser for debonding ceramic orthodontic brackets,” American Journal of Orthodontics and Dentofacial Orthopedics 128(5), 638–647 (2005). [CrossRef]
44. H. Mimura, T. Deguchi, A. Obata, T. Yamagishi, and M. Ito, “Comparison of different bonding materials for laser debonding,” American Journal of Orthodontics and Dentofacial Orthopedics 108(3), 267–273 (1995). [CrossRef]
45. J. L. Rickabaugh, R. D. Marangoni, and K. K. McCaffrey, “Ceramic bracket debonding with the carbon dioxide laser,” American Journal of Orthodontics and Dentofacial Orthopedics 110(4), 388–393 (1996). [CrossRef]
46. E. Azzeh and P. J. Feldon, “Laser debonding of ceramic brackets: a comprehensive review,” American Journal of Orthodontics and Dentofacial Orthopedics 123(1), 79–83 (2003). [CrossRef]
47. K. H. Chan and D. Fried, “Selective removal of dental composite using a rapidly scanned carbon dioxide laser,” in Lasers in Dentistry XVII20117884: SPIE, pp. 163–167.
48. A. Obata, T. Tsumura, K. Niwa, Y. Ashizawa, T. Deguchi, and M. Ito, “Super pulse CO2 laser for bracket bonding and debonding,” The European Journal of Orthodontics 21(2), 193–198 (1999). [CrossRef]
49. R. Ghazanfari, N. Azimi, H. Nokhbatolfoghahaei, and M. Alikhasi, “Laser aided ceramic restoration removal: A comprehensive review,” J Lasers Med Sci 10(2), 86–91 (2019). [CrossRef]
50. M. ALBalkhi, E. Swed, and O. Hamadah, “Efficiency of Er: YAG laser in debonding of porcelain laminate veneers by contact and non-contact laser application modes (in vitro study),” J Esthet Restor Dent 30(3), 223–228 (2018). [CrossRef]
51. M. Khoroushi and M. Kachuie, “Prevention and treatment of white spot lesions in orthodontic patients,” Contemp Clin Dent 8(1), 11 (2017). [CrossRef]
52. S. V. Kellesarian, V. Ros Malignaggi, K. M. Aldosary, and F. Javed, “Laser-assisted removal of all ceramic fixed dental prostheses: A comprehensive review,” J Esthet Restor Dent 30(3), 216–222 (2018). [CrossRef]
53. M. Alikhasi, A. Monzavi, H. Ebrahimi, M. Pirmoradian, A. Shamshiri, and R. Ghazanfari, “Debonding time and dental pulp temperature with the Er, Cr: YSGG laser for debonding feldespathic and lithium disilicate veneers,” J Lasers Med Sci 10(3), 211–214 (2019). [CrossRef]
54. W. Raab, “Temperature related changes in pulpal microcirculation,” Proc Finn Dent Soc 88(Suppl 1), 469–479 (1992).
55. K. Kodonas, C. Gogos, and D. Tziafas, “Effect of simulated pulpal microcirculation on intrapulpal temperature changes following application of heat on tooth surfaces,” International Endodontic Journal 42(3), 247–252 (2009). [CrossRef]
56. T. Hennig, P. Rechmann, A. Holtermann, and R. Dramburg, “Caries selective ablation: temperature in the pulp chamber,” in Laser Surgery: Advanced Characterization, Therapeutics, and Systems IV, 19942128: SPIE, pp. 397–402.
57. A. Secilmis, M. Bulbul, T. Sari, and A. Usumez, “Effects of different dentin thicknesses and air cooling on pulpal temperature rise during laser welding,” Lasers Med. Sci. 28(1), 167–170 (2013). [CrossRef]
58. M. Tozlu, M. O. Oztoprak, and T. Arun, “Comparison of shear bond strengths of ceramic brackets after different time lags between lasing and debonding,” Lasers Med. Sci. 27(6), 1151–1155 (2012). [CrossRef]
