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Year : 2014  |  Volume : 8  |  Issue : 2  |  Page : 40-43

A comparative evaluation of shear bond strength of the fifth-generation bonding agent treated with neodymium-doped yttrium aluminum garnet laser before and after polymerization: An in vitro study

Department of Conservative Dentistry and Endodontics, DY Patil Dental College and Hospital, Pune, Maharashtra, India

Date of Web Publication21-Nov-2014

Correspondence Address:
Abhinav Misuriya
Dr. D Y Patil Dental College and Hospital, Pimpri, Pune
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0976-2868.145134

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Objectives: Achieving higher bond strength is one of the most researched issues in adhesive bonding to dentin. Hard tissue modification by means of laser irradiation is becoming popular in dentistry. This study evaluates the shear bond strength of a commercially available adhesive system to dentin irradiated with Nd:YAG laser after adhesive application prior to and after polymerization of the bonding agent. Material and Methods: A group of 15 freshly extracted teeth were selected. Each one of these were disked proximally to expose the dentin. The teeth were randomly allocated into 3 groups. In Group 1, dentin was irradiated with Nd:YAG laser after the application of bonding agent but prior to ploymerization. In Group 2 dentin was irradiated with Nd:YAG laser after the application of bonding agent and subsequent polymerization. Group 3 served as control without irradiation with Nd:YAG.
Shear bond strength was evaluated and the results were analyzed statistically. Results: There was statistical difference between group 1 when compared with group 2 and group 3. However there was no statistical difference between group 2 and group 3. Conclusion: Application of laser on bonding agent before curing can have significant increase in the bond strength

Keywords: Degree of conversion, dentin bonding agents, neodymium-doped yttrium aluminum garnet laser, shear bond strength

How to cite this article:
Misuriya A, Gupta M. A comparative evaluation of shear bond strength of the fifth-generation bonding agent treated with neodymium-doped yttrium aluminum garnet laser before and after polymerization: An in vitro study. J Dent Lasers 2014;8:40-3

How to cite this URL:
Misuriya A, Gupta M. A comparative evaluation of shear bond strength of the fifth-generation bonding agent treated with neodymium-doped yttrium aluminum garnet laser before and after polymerization: An in vitro study. J Dent Lasers [serial online] 2014 [cited 2024 Feb 27];8:40-3. Available from:

  Introduction Top

Dentin is a dynamic and vital tissue and able to develop a defense mechanism the diameter of dentinal tubules decreases from 2.5 μm on a pulpal side to 0.8 μm toward the dentinoenamel junction, similarly the number of dentinal tubules decreases in a number from pulp (45,000/mm2) to the surface (20,000/mm2). [1] Dentinal tubules are the major channels for fluid flow across the dentin. Hence, dentin is an intrinsically wet tissue and fluid in the tubules is under constant outward pressure from pulp. Intra pulpal fluid pressure is estimated to be 25-30 mmHg or 34-40 cm water. [1] Bond strength of the deeper dentin is lesser than superficial dentin, and remaining dentin thickness affects adhesion. Therefore, bonding to dentin has been more problematic than bonding to enamel.

Adhesive dentistry has come a long way, wading through generations. It is clinically very important to enhance the adhesion between dentin and adhesive resin. Improved adhesive strength, not only leads to better retention but also prevents marginal leakage, thus reducing the chance of developing secondary caries [2] and also post-operative dentinal hypersensitivity.

The other revolution in dentistry has been brought by the advent of "lasers."

Shortly after the development of the lasers in 1960, researchers began to study the feasibility of using different lasers for different treatment modalities. Application of lasers in hard tissue treatment procedures is still being considered second after conventional approach in restorative dentistry.

The use of neodymium-doped yttrium aluminum garnet (Nd: YAG) lasers for the treatment of hypersensitivity [3] led to the hypothesis to explore its use in adhesive dentistry to improve bond strength.

After much of the literature search, minimal references were found on this "FUSION" concept using a bonding agent and Nd: YAG lasers.

Laser has been proposed as an aid to conventional restorative treatment. It can remove the smear layer, and seal exposed dentinal tubules. [4],[5] If laser irradiation could fuse or glaze by melting the surface of dentin, and thereby cause re-crystallization, the permeability of dentin could be altered. [6],[7],[8],[9],[10],[11],[12]

On the other hand, laser irradiation has been observed to increase dentin permeability by alteration of physical structures. [10]

Different types of lasers, operating modes, and energy outputs have been used, however, the most popular type recently used in preventive dentistry are CO 2 laser and Nd: YAG laser. Studies have suggested that Nd: YAG laser may function as an alternative or adjunctive therapy in preventive and restorative treatment. [13]

The purpose of this study was to evaluate change in bond strength, the hypothesis of a 5 th generation bonding agent treated with Nd: YAG laser before and after polymerization.

  Specimens Preparation Top

Extracted human teeth were used for this study, teeth with caries, restorations, and cracks were discarded. Any remaining soft tissue was removed from the tooth surface by a dental scaler [Figure 1]. All the teeth were stored in distilled water. The crowns were cut perpendicular to the long axis of the teeth with a diamond wafering blade mounted on a straight handpiece with water spray [Figure 2]. The enamel of each tooth was removed, and dentin block was made, which was then mounted on an acrylic jig which would act as a holder before subjecting it to shear bond strength (SBS) [Figure 3] and [Figure 4].
Figure 1: Sample of 15 teeth

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Figure 2: Slicing of tooth proximally to expose dentin

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Figure 3: Sample being subjected to SBS

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Figure 4: Plastic ring placed on the treated surface

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All specimens were randomly divided into three groups (A, B and C). Group A, was a control and received no laser treatment, each sample was etched and bonded as per manufacturer's instruction for the fifth generation dentin bonding agents (DBA) [Table 1]. Group B samples were the parameters of laser irradiation were: Pulse energy (100 mJ), rate (10 pps), and total irradiation time (4 s) they were etched, DBA was applied and surface was lased according to the mentioned parameters and then polymerized. Group C all samples were subjected to same bonding instructions except the surface was lased after polymerization. For all experimental conditions, the nano filler resin composite FiltekZ 350 (3M/ESPE, St. Paul, MN, USA; shade A2) was used, and light polymerized at 600 mW/cm 2 for 20 s (energy density = 12 J/cm 2 ) or 40 s (24 J/cm 2 ) with quartz-tungsten-halogen light polymerization unit (Optilux). All the samples were subjected to SBS test and the data were statistically analyzed by multiple comparison test that is, Tukey's test [[Table 2] and [Figure 5].
Figure 5: Graphical representation

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Table 1: Composition

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Table 2: One-way analysis of variance

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  Result Top

There is statistically highly significant mean difference in bond strength among the groups, but, from this analysis of variance, we didn't get the picture of in which two groups there is significant difference, for that purpose, we apply the multiple comparison test that is, Tukey's test [Table 3].
Table 3: Multiple comparison test (Tukey's test)

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In this study, the results showed significantly higher SBS of group B that is, lasing before polymerizing the bonding agent when compared to the control (group A without lasing) or group C (lasing after polymerization of bonding agent) [Figure 5].

The difference may be because of:

  • Better flow of bonding agent due to heat, No effect on the bonding agent as it is transparent
  • There was no statistical significant difference between the control group and group C as heat (due to laser) may not cause further penetration of bonding agent after polymerization [Table 3]
  • Significance. Irradiation with Nd: YAG laser before the placement of bonding agent is not recommended, given the fact this results in partial or total occlusion of dentinal tubules making adhesive infiltration and micromechanical retention more difficult.

  References Top

Nanci A, Ten Cate AR. Ten Cates Oral histology: Development, Structure and Function. 8 th ed. St. Louis, Mo: Elsevier, Cop.; 2013.  Back to cited text no. 1
Nakabayashi N, Kojima K, Masuhara E. The promotion of adhesion by the infiltration of monomers into tooth substrates. J Biomed Mater Res 1982;16:265-73.  Back to cited text no. 2
Lan WH, Liu HC. Treatment of dentin hypersensitivity by Nd: YAG laser. J Clin Laser Med Surg 1996;14:89-92.  Back to cited text no. 3
Pashley DH, Livingston MJ, Reeder OW, Horner J. Effects of the degree of tubule occlusion on the permeability of human dentine in vitro. Arch Oral Biol 1978;23:1127-33.  Back to cited text no. 4
Anic I, Tachibana H, Masumoto K, Qi P. Permeability, morphologic and temperature changes of canal dentine walls induced by Nd: YAG, CO2 and argon lasers. Int Endod J 1996;29:13-22.  Back to cited text no. 5
Sánchez F, España Tost AJ, Morenza JL. ArF excimer laser irradiation of human dentin. Lasers Surg Med 1997;21:474-9.  Back to cited text no. 6
Moritz A, Gutknecht N, Goharkhay K, Schoop U, Wernisch J, Sperr W. In vitro irradiation of infected root canals with a diode laser: Results of microbiologic, infrared spectrometric, and stain penetration examinations. Quintessence Int 1997;28:205-9.  Back to cited text no. 7
Dederich DN, Zakariasen KL, Tulip J. Scanning electron microscopic analysis of canal wall dentin following neodymium-yttrium-aluminum-garnet laser irradiation. J Endod 1984;10:428-31.  Back to cited text no. 8
Miserendino LJ, Levy GC, Rizoiu IM. Effects of Nd: YAG laser on the permeability of root canal wall dentin. J Endod 1995;21:83-7.  Back to cited text no. 9
Pashley EL, Horner JA, Liu M, Kim S, Pashley DH. Effects of CO2 laser energy on dentin permeability. J Endod 1992;18:257-62.  Back to cited text no. 10
Schaller HG, Weihing T, Strub JR. Permeability of dentine after Nd: YAG laser treatment: An in vitro study. J Oral Rehabil 1997;24:274-81.  Back to cited text no. 11
Lan WH, Liu HC. Sealing of human dentinal tubules by Nd: YAG laser. J Clin Laser Med Surg 1995;13:329-33.  Back to cited text no. 12
Lee BS, Lin CP, Lin FH, Lan WH. Ultrastructural changes of human dentin after irradiation by Nd: YAG laser. Lasers Surg Med 2002;30:246-52.  Back to cited text no. 13


  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]

  [Table 1], [Table 2], [Table 3]


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