The European Journal of Orthodontics Advance Access published online on February 8, 2008
The European Journal of Orthodontics, doi:10.1093/ejo/cjm103
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Comparison of sandblasting, laser irradiation, and conventional acid etching for orthodontic bonding of molar tubes
aran**
* Private Practice, Dentaform Health Center, Ankara
** Department of Orthodontics, Faculty of Dentistry, Dicle University, Diyarbak
r, Turkey
Address for correspondence Dr Güvenç Baaran, Department of Orthodontics, School of Dentistry, Dicle University, Diyarbakr 21280, Turkey, E-mail: basaran{at}dicle.edu.tr
 |
Summary |
|---|
 Top Summary IntroductionMaterials and methodsResultsDiscussionConclusionsReferences |
|---|
The purpose of the study was to determine if sandblasted and laser-irradiated enamel may be viable alternatives to acid etching for molar tube bonding. Seventy-seven molar teeth extracted for periodontal reasons were used. Seventy teeth underwent shear bond strength (SBS) testing and the remaining seven were examined under scanning electron microscopy (SEM). Adhesive remnant index (ARI) scores were also considered. An erbium, chromium-doped:yttrium-scandium-gallium-garnet (Er, Cr: YSGG) laser was used for enamel etching. Sandblasted and laser-irradiated enamel surfaces with different power outputs (0.5, 0.75, 1, 1.5, and 2 W) were compared with conventional phosphoric acid etching. Descriptive statistics, including mean, standard deviation, and minimum and maximum values, were calculated for each group. Multiple comparisons of the SBS of different etching types were performed by analysis of variance testing. The chi-square test was used to evaluate differences in ARI scores between groups.
Acid-etched, 1-, 1.5-, and 2-W laser irradiation groups demonstrated a clinically acceptable mean SBS (7.65 ± 1.38, 6.69 ± 1.27, 7.13 ± 1.67, 7.17 ± 1.69 MPa, respectively). Irradiation with an output of 0.5 and 0.75 W and sandblasting of the enamel showed a lower SBS than the other groups (2.94 ± 1.98, 4.16 ± 2.87, 2.01 ± 0.64 MPa, respectively). SEM evaluation of 1, 1.5, and 2 W laser irradiation revealed similar etching patterns to acid etching. Sandblasting and 0.5, and 0.75 W laser etching were not able to etch enamel in preferential patterns. Laser irradiation at 1.5 and 2 W was able to etch enamel. More adhesive was left on the enamel surface with low-power laser irradiation.
Sandblasting and low-power laser irradiation (0.5, 0.75, and 1 W) are not capable of etching enamel suitable for orthodontic molar tube bonding, but 1.5- and 2-W laser irradiation may be an alternative to conventional acid etching.
|
Introduction |
|---|
|
TopSummaryIntroductionMaterials and methodsResultsDiscussionConclusionsReferences |
|---|
Bonding of molar tubes has many advantages over banding in daily orthodontic practice (Zachrisson, 1977
). More plaque accumulation and gingival inflammation, although not statistically significant, have been associated with banding (Boyd and Baumrind, 1992).
The primary effect of enamel etching is to increase the surface area and thereby change the surface from a low-energy hydrophobic surface to high-energy hydrophilic surface (Reynolds, 1975). Various surface properties may be accomplished but the most important point is to modify the surface characteristic of the enamel for adhesive attachment (Silverstone et al., 1975). Various preparation methods including orthophosphoric acid, sandblasting, and laser irradiation have been shown to etch enamel for orthodontic bonding (Büyükylmaz et al., 1995; Wigdor et al., 1995; Zachrisson et al., 1995; Miller and Zernik, 1996; Millett et al., 1995; Chung and Hwang, 1997; Takeda et al., 1998, 1999; Aoki et al., 2000; Chung et al., 2001; Üümez et al., 2002).
Acid etching decalcifies the inorganic component of the enamel and the enamel becomes more susceptible to carious attack, which is induced by plaque accumulation around the bonded orthodontic attachments.
Many researchers have investigated the effects of sandblasting (Zachrisson and Büyükylmaz, 1993; Büyükylmaz et al., 1995; Zachrisson et al., 1995; Miller and Zernik, 1996; Millett et al., 1996; Chung and Hwang, 1997; Chung et al., 2001). Some (Zachrisson and Büyükylmaz, 1993; Büyükylmaz et al., 1995; Zachrisson et al., 1995; Miller and Zernik, 1996; Millett et al., 1996; Chung and Hwang, 1997) preferred the use of sandblasting to increase surface roughness of non-enamel surfaces (metal, gold, amalgam, or porcelain), while Chung et al. (2001) suggested that direct sandblasting may be a feasible method for preparing teeth for orthodontic bonding.
Laser irradiation removes the smear layer. After laser etching, some physical changes occur, such as melting and recrystallization. Numerous pores and bubble-like inclusions appear (Takeda et al., 1998, 1999). Thus, irregular surfaces are created which permit penetration of fluid adhesive components. In dentistry, the first-generation lasers were used only for soft tissues. The main disadvantage was the immediate increase in temperature, resulting in an inflammatory pulpal response (Wigdor et al., 1995; Aoki et al., 2000). The development of the erbium, chromium-doped:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser has overcome this problem and it is convenient for both soft and hard tissue treatments in the oral environment because these lasers can ablate enamel and dentine effectively due to their highly efficient absorption of both water and hydroxyapatite (Wigdor et al., 1995). The main advantage of the laser-etched surface is acid resistance. It yields more resistant enamel for caries attack (Vissuri et al., 1996; Klein et al., 2005). In a previous study, Üümez et al. (2002) demonstrated that ablation of tooth surfaces using an Er,Cr:YSGG laser with different power outputs showed differing etching patterns of enamel, resulting in different shear–peel bond strengths.
Chung et al. (2001) suggested that sandblasting provided clinically acceptable bond strengths, while Millett et al. (1995) showed low bond strengths with sandblasting for orthodontic bonding.
The purpose of the present study was to investigate the shear–peel bond strength and adhesive failure location of laser- and sandblasted-etched enamel compared with conventional acid-etching techniques, and to determine the suitability of these modalities in molar tube bonding.
|
Materials and methods |
|---|
|
TopSummaryIntroductionMaterials and methodsResultsDiscussionConclusionsReferences |
|---|
Experimental design
Seventy-seven molar teeth, extracted for periodontal reasons, were used in the present investigation. The teeth were stored in distilled water for a maximum of 1 month. To prevent bacterial growth, the water was changed weekly (von Fraunhofer et al., 1993). The teeth were free of caries, macroscopic cracks, abrasions, and staining as assessed by visual examination. Seventy teeth were used for the bond strength experiments and the remaining seven (one specimen for each group) for scanning electron microscopy (SEM) to determine the topography and morphology of the treated enamel surface. This technique lacks a quantitative scale and the information that is provided is subjective. However, SEM was used to visualize enamel with different etching protocols. The order of testing each specimen was randomized.
Before the experiment, the teeth were embedded horizontally in self-cure acrylic resin blocks with the facial surface of the teeth at least 2 mm above the surface of the acrylic resin. Before bonding the molar tubes, the enamel surfaces were prepared with different enamel preparation techniques. Seventy teeth, 10 for each group, were randomly assigned as follows:
- Group 1: Enamel irradiated with Er,Cr:YSGG laser with 0.5 W power output.
- Group 2: Enamel irradiated with Er,Cr:YSGG laser with 0.75 W power output.
- Group 3: Enamel irradiated with Er,Cr:YSGG laser with 1 W power output.
- Group 4: Enamel irradiated with Er,Cr:YSGG laser with 1.5 W power output.
- Group 5: Enamel irradiated with Er,Cr:YSGG laser with 2 W power output.
- Group 6: Enamel etched with 38 per cent orthophosphoric acid.
- Group 7: Enamel sandblasted with 50 µm aluminium oxide.
- Group 2: Enamel irradiated with Er,Cr:YSGG laser with 0.75 W power output.
Etching procedure
The Er,Cr:YSGG laser (Waterlase, Biolase Europe GmBH, Floss, the Germany) is a hydrokinetic system (Figure 1). This device allows precise hard tissue treatments by virtue of laser energy interaction with water above and at the tissue interface. It operates at a wavelength of 2.78 µm and a pulse duration of 150 µs at a rate of 20 Hz. The average output can be varied from 0 to 6 W. The laser energy is delivered through a fibre optic system to a sapphire tip and is bathed in an adjustable air/water spray. The air and water level was 90 and 80 per cent, respectively. The laser beam was directed perpendicular to the enamel surface at a distance of 1 mm. To avoid unnecessary irradiation, acrylic resin with a 4 x 6 mm hole was placed on the tooth surface. The first five groups were irradiated with varying power outputs (0.5, 0.75, 1, 1.5, and 2 W). All laser irradiations were performed for 15 seconds.
|
Group 6, etching for 15 seconds (Surmont et al., 1992
) with 38 per cent orthophosphoric acid (Pulpdent, Watertow, Massachusetts, USA), was performed followed by 15 seconds of rinsing with an air/water spray. For group 7, the buccal surfaces of the teeth were sandblasted at 65–70 psi for 10 seconds with aluminum oxide (GAC International, Inc., Bohemia, New York, USA) with a particle size of 50 µm. The sandblasting apparatus (Microetcher II, Danville Engineering, San Ramon, California, USA) was directed perpendicular to the enamel surface at a distance of 1 mm. To avoid unnecessary sandblasting, acrylic resin with a 4 x 6 mm hole was placed on the tooth surface. The sandblasted specimens were rinsed for 15 seconds using an air/water spray to remove all particles from the surface.
SEM examination
One representative specimen from each group was left unbonded and not subjected to SBS testing. The treated surface of each tooth was marked for SEM.
Bonding procedure
The surface etched by acid, laser, or sandblasting was covered with a small amount of adhesive using a microbrush. After applying the adhesive paste (Transbond XT, 3M Unitek, Monrovia, California, USA), the molar tube was placed on the tooth surface and adjusted for final positioning. Excess adhesive was hand removed and light curing was performed for 40 seconds.
After storing the specimens in water at 37°C for 24 hours, thermocycling for a total of 500 cycles at 5–55°C with a dwell time of 30 seconds was performed. SBS was accomplished using a chisel edge, mounted on the crosshead of the testing machine (Instron testometric M500-25, Testometric Company Ltd, Rochdale, Lancashire, UK). The edge was aimed at the molar tube and the enamel interface at a crosshead speed of 0.5 mm/seconds. The force decay was recorded for each specimen in Newtons and then converted into megapascals. SBS was calculated by dividing the force decay by the molar tube base area. The base area of the molar tubes was 19.88 mm2 (GAC International, Inc.).
After debonding, the tubes were examined under x10 magnification to evaluate the amount of resin remaining on the tooth. The adhesive remnant index (ARI; Årtun and Bergland, 1984) was used to describe the amount of resin remaining on the tooth surfaces. The ARI scores ranged from 0 to 3 as follows: 0, no adhesive remained on the tooth; 1, less than half of the enamel bonding site covered with adhesive; 2, more than half of the enamel bonding site covered with adhesive; and 3, the enamel bonding site covered entirely with adhesive.
Statistical analysis
Descriptive statistics, including mean, standard deviation, and minimum and maximum values, were calculated for each group. Multiple comparisons of the SBS of different etching types were performed by analysis of variance. The chi-square test was used to evaluate differences in ARI scores between groups. All statistical evaluations were calculated using the Statistical Package for Social Sciences Windows, release 10.0.0 (SPSS Inc., Chicago, Illinois, USA).
|
Results |
|---|
|
TopSummaryIntroductionMaterials and methodsResultsDiscussionConclusionsReferences |
|---|
Descriptive statistics of the laser-irradiated, sandblasted-, and acid-etched enamels are shown in Table 1. The mean shear–peel bond strengths observed in groups 1 and 2 were below clinically acceptable levels. Although the mean strengths were acceptable, some shear–peel bond strengths produced by 1-W laser irradiation were lower than clinically acceptable limits. Laser irradiation with an output of 1.5 and 2 W and acid etching produced higher mean shear–peel bond strengths. Multiple comparisons of the groups revealed statistically significant differences from each other (Table 2). When all groups were compared, 0.5- and 0.75 W laser irradiation and sandblasting produced similar shear–peel bond strengths, which were lower than the other groups. The 1, 1.5 and 2 W laser irradiation groups demonstrated similar shear–peel bond strengths compared with the acid-etched group.
|
|
No significant enamel surface etching was obtained when using 0.5-W laser irradiation. Small cavitations only were seen on the enamel (Figure 2a). Laser irradiation with 0.75 W revealed deeper cavitations (Figure 2b) than in the 0.5 W laser irradiation group, but still did not resemble the etching patterns described by Silverstone et al. (1975)
. The 1 W laser produced a more preferential Type I etching pattern (Figure 2c). A honeycomb-like appearance was observed in the 1 W laser-etched group with microcracks on the laser-ablated surfaces, which aid the penetration of resin.
|
Laser irradiation at 1.5 W resulted in a Type I etching pattern with more microcracks (Figure 2d). Laser irradiation of 2 W produced a Type III acid-etching pattern with microcracks, and the surface destruction was more prominent (Figure 2e). The characteristic Type III acid-etching pattern with regular rough surface and spaces (Silverstone et al., 1975
) can be seen with the acid-etching procedure (Figure 2f). Dissolution of hydroxyapatite by phosphoric acid produced tags and rough surfaces that afforded the mechanical lock for resin.
Although sandblasting of the enamel surface did not result in the typical etching pattern described by Silverstone et al. (1975), some cavitations occurred (Figure 2g).
The ARI scores are listed in Table 3. Sandblasting and 0.5 and 0.75 W laser irradiation produced adhesive failures, whereas cohesive failures were seen with acid etching and 1, 1.5 and 2 W laser irradiation.
|
|
Discussion |
|---|
|
TopSummaryIntroductionMaterials and methodsResultsDiscussionConclusionsReferences |
|---|
Acid etching results in chemical changes that may produce modification of the organic matter and decalcification of the inorganic component of enamel (Bertolotti, 1992
; Pashley, 1992). Acid etching is a form of microetching, whereas sandblasting can be regarded as a form of macroetching. Chung et al. (2001) used sandblasting to remove unfavourable oxides and contaminants and increase surface roughness promoting a convenient surface for bonding. In the present study, sandblasting was applied to the enamel surface to test whether it was capable of producing etching patterns suitable for bonding (Zachrisson and Büyükylmaz, 1993; Millett et al., 1995). Laser-irradiated enamels result in fractured and uneven dentinal tubules, which are ideal for bonding. The laser-etched enamel surface is acid resistant; thus, it is more resistant to carious attack (Vissuri et al., 1996). Therefore, laser etching might have an advantage for orthodontic bonding.
The laser used in this study was a hydrokinetic system. The main disadvantage of the previous lasers was the immediate increase in temperature, resulting in an inflammatory pulpal response (Wigdor et al., 1995; Aoki et al., 2000) With this system, not only could the temperature be suppressed but also cutting efficiency could be increased (Eversole and Rizoiu, 1995). Laser energy is delivered through a fibre optic system to a sapphire tip terminal. The average output can be varied from 0 to 6 W. For cutting enamel, high irradiation outputs varying from 2.5 to 6 W can be used (Hossain et al., 2003). In this study, in order to etch enamel, lower outputs (0.5, 0.75, 1, 1.5, and 2 W) were used.
The varying power outputs produced different etching patterns. While 0.5 W laser irradiation demonstrated a significantly lower SBS and more even surfaces, higher power outputs showed different characteristics. Laser irradiation at 0.75 W showed no significant difference in SBS, but the mean SBS was below clinically acceptable limits (Reynolds, 1975). Although 1 W laser etching produced a clinically acceptable mean SBS (Reynolds, 1975), some results were below acceptable limits and, in agreement with a previous study (Üümez et al., 2002), indicating that it is not suitable for enamel etching. Laser etching of 1.5 and 2 W demonstrated comparable mean, maximum, and minimum levels of SBS to that of acid etching.
Reynolds (1975) reported that 6–8 MPa were clinically acceptable bond strengths, whereas Maijer and Smith (1986) found 8 MPa to be adequate. In this study, the acid-etched specimen was the control group which showed a mean bond strength of 7.65 ± 1.36 MPa. Laser irradiation showed varying bond strengths between 2.94 ± 1.98 and 7.17 ± 1.69 MPa. In a previous study (Üümez et al., 2002), a similar bond strength was reported with acid etching (8.23 ± 2.3 MPa) and laser irradiation (5.64 ± 3.19 and 7.11 ± 4.56 MPa) indicating that the mean bond strengths in this study were reliable.
During orthodontic treatment, attachments are subjected to shear, tensile, and torsion forces. In the present investigation, shear–peel forces were generated. The relatively low bond strengths may be related to the forces generated. The technique sensitivity of the experiments is also an important factor. The storage of the specimens and the different configuration of enamel prisms on molars may also have contributed to the low bond strength values.
Sandblasting of the enamel in this study produced a lower shear–peel bond than clinically acceptable limits. It has been shown to be helpful to increase bond strengths on porcelain or amalgam surfaces (Zachrisson and Büyükylmaz, 1993; Zachrisson et al., 1995; Miller and Zernik, 1996).
There are some contradictory findings concerning the use of lasers for enamel etching. Some researchers (von Fraunhofer et al., 1993; Üümez et al., 2002) stated that laser irradiation is not capable of etching enamel. However, the present findings are in agreement with Vissuri et al. (1996), Hossain et al. (2003), and Lee et al. (2003) who reported that laser irradiation may be used to etch enamel. These contradictory findings are due to the different outputs and experimental designs of the studies. The importance of using suitable settings is clearly highlighted by the findings of the present research. SEM demonstrated that 0.5 and 0.75 W laser irradiations were not able to etch enamel, but 1, 1.5 and 2 W irradiation produced preferable etching patterns. Fewer microcracks were produced with 1 W irradiation than 1.5 and 2 W. A Type I etching pattern was produced with 1 and 1.5 W, whereas a Type III pattern was produced with 2 W laser irradiation. The cavitations were not uniform with 2 W laser irradiation. Obtuse angularities and sharp irregularities were both seen on 2 W laser-irradiated surfaces, leading to the conclusion that outputs of 1 and 1.5 W are suitable to etch enamel.
The SBS obtained in the present study demonstrated wide variations. The 0.5 and 0.75 W laser-irradiated groups and the sandblasted group showed lower bond strengths than clinically acceptable limits (Reynolds, 1975). The mean SBS obtained with 1, 1.5 and 2 W laser irradiation and phosphoric acid was within acceptable limits. Some results for 1 W laser irradiation were below acceptable limits, so the use of 1 W laser irradiation must be questioned. Laser irradiation with an output of 1.5 and 2 W was more successful in producing acceptable etchings.
Sandblasting the enamel surface was not a good alternative for acid etching because the etched enamel was similar to the 0.5 W laser irradiation group. Although Chung et al. (2001) indicated, contrary to present results, that bonding attachments could be used on sandblasted enamel. This finding may be due to the different forces applied to debond. The sandblasted surfaces displayed obtuse angularities instead of the sharp irregularities of etched enamel surfaces which could lead to weak bond strengths. Improved SBS has been reported with sandblasting of the brackets or substances other than natural tooth (amalgam, porcelain) in combination with acid etching (Zachrisson and Büyükylmaz, 1993; Büyükylmaz et al., 1995; Millett et al., 1995; Zachrisson et al., 1995; Miller and Zernik, 1996). They also reported unacceptable bond strengths with sandblasted tooth structures, as observed in the present investigation.
In a previous study (Üümez et al., 2002), the time used for etching enamel with laser irradiation was also 15 seconds. This was sufficient to scan a 4 x 6 mm area which was used in the present investigation to bond molar tubes. Sandblasting the selected area was performed for 10 seconds, which was followed by 15 seconds of air/water spraying. Acid etching was applied for 15 seconds and then 15 seconds of rinsing with air/water spray. Since etching the enamel by laser irradiation required no rinsing, a gain in chairside time of 15 seconds for each tooth was obtained. Although, the exact time required for etching was not determined, it is clear that laser etching takes less time thus reducing chairside time.
The ARI scores revealed differences between etching procedures. Generally, more adhesive was left on the enamel surface with low-power laser irradiation. This demonstrates that shallow etching patterns are unsuitable for bonding.
While less chair time is needed when less adhesive is left on the enamel, it may cause enamel fracture while debonding. Breakage at the bracket adhesive interface is safer, but the time spent to clean the tooth after debonding results in an increase in chair time. The ARI scores obtained in the present research with suitable etching procedures (1, 1.5, and 2 W and phosphoric acid) were generally 1 and 2, which means that adhesive was left both on the bracket and on the tooth.
Since the handpiece of Er,Cr:YSGG laser is light, its manipulation is easy. Unnecessary etching of the enamel is prevented with Er,Cr:YSGG laser. The handling in the posterior segments of the mouth could be problematic because of the cheek muscles.
|
Conclusions |
|---|
|
TopSummaryIntroductionMaterials and methodsResultsDiscussionConclusionsReferences |
|---|
- Sandblasting and low-power laser irradiation (0.5, 0.75, and 1 W) are not capable of etching enamel suitable for orthodontic molar tube bonding.
- Laser irradiation with outputs of 1.5 and 2 W could be a viable alternative to the conventional acid-etch technique.
|
References |
|---|
|
TopSummaryIntroductionMaterials and methodsResultsDiscussionConclusionsReferences |
|---|
-
Aoki A, Sakaki MK, Watanabe H, Ishikawa I. Lasers in nonsurgical periodontal therapy. Periodontology (2000) 36:59–97.
Årtun J, Bergland S. Clinical trials with crystal growth conditioning as an alternative to acid-etch enamel pretreatment. American Journal of Orthodontics (1984) 85:333–340.[CrossRef][Web of Science][Medline]
Bertolotti RL. Conditioning of the dentin substrate. Operative Dentistry Supplement (1992) 5:131–137.
Boyd RL, Baumrind S. Periodontal considerations in the use of bonds or bands on molars in adolescents and adults. Angle Orthodontist (1992) 62:117–126.[Web of Science][Medline]
Büyükylmaz T, Zachrisson YØ, Zachrisson BU. Improving orthodontic bonding to gold alloy. American Journal of Orthodontics and Dentofacial Orthopedics (1995) 108:510–518.[CrossRef][Web of Science][Medline]
Chung KH, Hwang YC. Bonding strengths of porcelain repair systems with various surface treatments. Journal of Prosthetic Dentistry (1997) 78:267–274.[CrossRef][Web of Science][Medline]
Chung K, Hsu B, Berry T, Hsieh T. Effect of sandblasting on the bond strength of the bondable molar tube bracket. Journal of Oral Rehabilitation (2001) 28:418–424.[CrossRef][Web of Science][Medline]
Eversole LR, Rizoiu IM. Preliminary investigations on the utility of an erbium chromium YSGG laser. Canadian Dental Association Journal (1995) 23:41–49.
Hossain M, Nakamura Y, Tamaki Y, Yamada Y, Murakami Y, Matsumoto K. An atomic analysis and knoop hardness measurement of the cavity floor prepared by Er,Cr:YSGG laser irradiation in vitro. Journal of Oral Rehabilitation (2003) 30:515–521.[CrossRef][Web of Science][Medline]
Klein ALL, Rodrigues LKA, Eduardo CP, Nobre dos Santos M, Cury JA. Caries inhibition around composite restorations by pulsed carbon dioxide laser application. European Journal of Oral Science (2005) 113:239–244.[CrossRef]
Lee BS, et al. Bond strengths of orthodontic brackets after acid-etched, Er:YAG laser-irradiated and combined treatment on enamel surface. Angle Orthodontist (2003) 73:565–570.[Web of Science][Medline]
Maijer R, Smith DC. Crystal growth on the outer enamel surface: an alternative to acid etching. American Journal of Orthodontics (1986) 89:183–193.[CrossRef][Web of Science][Medline]
Miller S, Zernik JH. Sandblasting of bands to increase bond strength. Journal of Clinical Orthodontics (1996) 30:217–222.[Medline]
Millett DT, McCabe JF, Bennett TG, Carter NE, Gordon PH. The effect of sandblasting on retention of first molars orthodontic bands cemented with glass ionomer cement. British Journal of Orthodontics (1995) 22:161–169.[Abstract]
Pashley DH. The effects of acid etching on the pulpodentin complex. Operative Dentistry (1992) 17:229–234.[Web of Science][Medline]
Reynolds IR. A review of direct orthodontic bonding. British Journal of Orthodontics (1975) 2:171–180.
Silverstone LM, Saxton CA, Dogan IL, Fjerskov D. Variation in the pattern of acid etching on human dental enamel examined by scanning electron microscope. Caries Research (1975) 9:373–387.[Web of Science][Medline]
Surmont P, Dermaut L, Martens L, Mors M. Comparison in shear bond strength of orthodontic brackets between five bonding systems related to different etching times. An in vivo study. American Journal of Orthodontics and Dentofacial Orthopedics (1992) 101:414–419.[CrossRef][Web of Science][Medline]
Takeda FH, Harashima T, Eto JN, Kimura Y, Matsumoto K. Effect of Er:YAG laser treatment on the root canal walls of human teeth: a SEM study. Endodontic Dental Traumatology (1998) 14:270–273.[CrossRef]
Takeda FH, Harashima T, Eto JN, Kimura Y, Matsumoto K. A comparative study of the removal of smear layer by three endodontic irrigants and two types of laser. International Endodontic Journal (1999) 32:32–39.[CrossRef][Web of Science][Medline]
Üümez S, Orhan M, Üümez A. Laser etching of enamel for direct bonding with an Er,Cr:YSGG hydrokinetic laser system. American Journal of Orthodontics and Dentofacial Orthopedics (2002) 122:649–656.[CrossRef][Web of Science][Medline]
Vissuri SR, Gilbert JR, Wright DD, Wigdor HA, Walsh JT. Shear strength of composite bonded to Er:YAG laser-prepared dentin. Journal of Dental Research (1996) 75:599–605.
von Fraunhofer JA, Allen DJ, Orbell GM. Laser etching of enamel for direct bonding. Angle Orthodontist (1993) 63:73–76.[Web of Science][Medline]
Wigdor HA, Walsh JT, Featherstone JDB, Visuri SR, Fried D, Waldvogel JL. Lasers in dentistry. Lasers in Surgery and Medicine (1995) 16:103–108.[CrossRef][Web of Science][Medline]
Zachrisson BU. A posttreatment evaluation of direct bonding in orthodontics. American Journal of Orthodontics (1977) 71:173–189.[CrossRef][Web of Science][Medline]
Zachrisson BU, Büyükylmaz T. Recent advances in bonding to gold, amalgam and porcelain. Journal of Clinical Orthodontics (1993) 27:661–675.
Zachrisson BU, Büyükylmaz T, Zachrisson YØ. Improving orthodontic bonding to silver amalgam. Angle Orthodontist (1995) 65:35–42.[Web of Science][Medline]
CiteULike 
Connotea 
Del.icio.us What's this?
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||