Journal of Dental Lasers

ORIGINAL ARTICLE
Year
: 2016  |  Volume : 10  |  Issue : 2  |  Page : 43--46

Evaluation of root-end cavity preparation using erbium, chromium:yttrium, scandium, gallium, and garnet laser, ultrasonic retrotips, and conventional burs


Sarika Chaudhry, Sudha Yadav, Gunpreet Oberoi, Sangeeta Talwar, Mahesh Verma 
 Department of Conservative Dentistry and Endodontics, Maulana Azad Institute of Dental Sciences, New Delhi, India

Correspondence Address:
Sarika Chaudhry
Department of Conservative Dentistry and Endodontics, Maulana Azad Institute of Dental Sciences, MAMC Complex, BSZ Marg, New Delhi - 110 002
India

Abstract

Aim: To compare root-end cavities prepared with ultrasonics (Group A), with those created by burs in a conventional handpiece (Group B) and erbium, chromium:yttrium, scandium, gallium, and garnet (Er, Cr:YSGG) laser (Group C). Materials and Methods: After root canal instrumentation and filling, apices of 60 single-rooted teeth were resected. Retrograde Class I cavities 3 mm deep were prepared using ultrasonic retro-prep tips (Group A), round burs (Group B), and Er:YSGG laser (Group C). An ultrasonic unit was used with computed tomography-5 retrotip at the frequency of 32 KHz. Laser beam parameters were a pulse of very short duration (100 s), energy of 280 mJ, and repetition rate of 10 Hz. The apical root portion and root-end cavities were replicated and prepared for stereomicroscopic analysis. Results: The degree of chipping associated with the margin of the root-end cavities and the incidence of root face cracks were noted. Marginal chipping of root-end cavities prepared using ultrasonic instrumentation was significantly higher than that produced by bur (P < 0.001) or laser, with laser group showing the least amount of chipping. Conclusion: There was a significant difference between the number of cracks produced by the three methods, with the laser group having the least number of cracks and marginal chipping.



How to cite this article:
Chaudhry S, Yadav S, Oberoi G, Talwar S, Verma M. Evaluation of root-end cavity preparation using erbium, chromium:yttrium, scandium, gallium, and garnet laser, ultrasonic retrotips, and conventional burs.J Dent Lasers 2016;10:43-46


How to cite this URL:
Chaudhry S, Yadav S, Oberoi G, Talwar S, Verma M. Evaluation of root-end cavity preparation using erbium, chromium:yttrium, scandium, gallium, and garnet laser, ultrasonic retrotips, and conventional burs. J Dent Lasers [serial online] 2016 [cited 2017 Mar 28 ];10:43-46
Available from: http://www.jdentlasers.org/text.asp?2016/10/2/43/196989


Full Text

 Introduction



It is difficult to achieve an ideal root-end cavity preparation and a good retrograde filling with the classical method in the surgical endodontic procedure because of a number of difficulties: limited access, root anatomy, and tooth angulation. Ultrasonic devices were developed to overcome these difficulties, but several authors have found ultrasonic root-end cavity preparation produces cracks and/or chipping. [1],[2],[3],[4] Therefore, research into new methods of retrograde cavity preparation is still necessary.

Erbium, chromium:yttrium, scandium, gallium, and garnet (Er, Cr:YSGG) pulsed laser has been found to be useful in endodontic surgery for root-end resection, root-end cavity preparation, hemostasis, and sterilization of the root apex and surrounding tissue. For restorative procedures, laser use has increased patient acceptance related to pain, vibrations, microfractures, and heat production. This laser cuts hard tissue with highly energized water particles and soft tissue directly with laser energy. [5] Preliminary studies looking at the safety and efficacy of using the Er, Cr:YSGG laser found it to be a proficient instrument in cutting bone. [6]

Hence, the purpose of this study is to assess the efficacy of Er, Cr:YSGG laser usage for root-end cavity preparation, i.e., marginal integrity of apical cavities and root-surface cracking over that produced by ultrasonic retro-prep tips and conventional preparation using a handpiece and bur.

 Materials and Methods



Ninety single-rooted teeth with straight roots and fully developed apices were selected for this experiment. These had been extracted for periodontal and orthodontic reasons and stored in 0.9% sodium chloride and 1% sodium hypochlorite solution to preserve and inhibit microbial growth.

Specimen preparation

The crowns were cut with a diamond bur at the cementoenamel junction. Working length was established at 1 mm short of the anatomical apex by visually identifying a #15 K-reamer (Dentsply, Maillefer, Ballaigues, Switzerland) at the apical foramina and subtracting 1 mm. Root canals were cleaned and shaped using conventional "step-back" technique to a master file #40 at the apical portion and #80 at the coronal part of the root canal. After instrumentation, the canals were dried with sterile paper points and obturated with gutta-percha (Kerr, Romulus, MI) and AH Plus (Dentsply, DeTrey, Konstanz, Germany) sealer using a cold lateral condensation technique. Samples were kept for 48 h after obturation. Then, 3 mm of root end was resected perpendicular to the long axis of the roots with a fissure bur (D and Z, Diamant, Germany) at high speed under a continuous water spray. The resected roots were then randomly assigned to three groups of thirty each.

Group A: Ultrasonic group

The root-end cavities were prepared using computed tomography-5 retrotip on an ultrasonic unit Piezon Master 400 (EMS, Nyon, Switzerland) at a frequency of 32 KHz. The operator employed intermittent pressure with in-and-out motion to start preparation, then increased the depth to 3 mm from the resected surface, and finally moved the tip circumferentially to complete the preparation.

Group B: Bur prepared group

A size 010 round bur in a slow-speed handpiece with water cooling was used to prepare a cavity 3 mm down the long axis of the canal. Cavity refinement and undercut were created with a size 010 inverted cone bur.

Group C: Laser group

The root-end cavities were made using the Er, Cr:YSGG laser device (WaterLase, C100 Model at 2,780 nm wavelength), energy was set at 280 mJ/pulse, and repetition rate was 10 Hz. Pulse width was 100 μs (very short pulse). The laser radiation was applied manually through a fiber tip 1.5 cm long with a 600 μm laser tip and a setting of four watts, 55% water, and 65% air as suggested by the manufacturer. Class I root-end preparation was made in the twenty resected root ends to a depth of 3 mm and approximately 1 mm in diameter confirmed with a periodontal probe. All root ends were prepared by one operator.

Then, the teeth were immersed in 0.004% methylene blue solution for 48 h, and again they were observed under a stereomicroscope at ×40 magnification to examine the existence of cracks and chippings. Statistical analyses were carried out using the Statistical Package for Social Sciences software version 17, SPSS Inc, Chicago IL. Fisher's exact test was used. P < 0.05 was considered statistically significant.

 Results



seven cracks were seen in the ultrasonic group [Figure 1], three in the bur prepared group [Figure 2], whereas there was only one crack in the l aser group [Figure 3]. chipping was found in ten samples of the ultrasonic group [Figure 1], whereas four bur prepared samples showed chipping and there was only one sample with chipping in the laser group, and the difference was statistically significant (P).{Figure 1}{Figure 2}{Figure 3}

 Discussion



Grung et al., [7] 1990, estimated the success rate of periradicular surgery using traditional techniques to be 70%. This implies that three out of ten cases fail. A number of factors predispose to failure, with root-end cavity preparation being the most important steps in achieving an apical seal at the resected root end.

Traditional preparation with a bur and conventional handpiece is not ideal since it is often difficult to achieve the correct alignment with the long axis of the canal. Furthermore, a bur cannot debride the apical canal and is likely to produce a smear layer. [8] Furthermore, in the previous studies, more chippings were observed after preparation with the ultrasonic device. [9],[10] It has been found that the roots remained very cool to the touch during preparation as has been noted for osseous tissue [11] by use of pulsed Er, Cr:YSGG laser (WaterLase art). Therefore, the present study was designed to investigate the integrity of root end following root-end cavity preparation with an ultrasonic device, conventional burs, and laser.

In this study, burs were used for root resection to simulate the clinical situation; however, for the purpose of homogeneity, teeth showing cracks following root resection were excluded from the study. Although Beling et al. [5] found no significant difference with regard to the number or type of cracks after root-end resection or root-end preparation between gutta-percha filled and uninstrumented roots, it was considered to obturate the canals in this study. To examine the existing cracks at the root end, methylene blue dye technique and a stereomicroscope were used which, according to Wright et al., [12] is a precise method for studying cracks. As it has been found that placing a dehydrated tooth in the low-vacuum conditions of a scanning electron microscope (SEM), will cause crack propagation. [13] These artifacts cannot be discerned from real evidence of fracture. Hence, we used stereomicroscope in this study. In this study, no scoring for the extension of cracks was done, the presence or absence of root face cracking was the only factor recorded, with no attempt made to quantify the extent of the cracking.

Cavities produced with burs were generally of good quality with little evidence of chipping. This reflects the control possible with a bur, a factor emphasized by the ideal access possible ex vivo. Preparations in vivo are likely to be of poorer quality [14] as alignment along the canal system is compromised by the less than ideal access.

Apel et al. [15] showed that pulses of shorter duration reduced the limit at which ablation of dental enamel started by approximately 3 J/cm 2 . In this study Er, Cr:YSGG pulsed laser was used at very short pulse (100 s) that enabled a high efficacy in hard tissue removal, so we could expect no cracks in dentinal walls and minimal or even no thermal damages, in accordance with the study of Kimura et al. [16] Moreover, energized water molecules cut the dentin in a way that the temperature of root surface during cavity preparation remains low, which is critical for the surrounding bone.

Chipping was also investigated the following cavity preparation, and the difference of the methods applied was significant (seven cases with ultrasonic vs. none with laser). In the previous studies, more chippings were observed after preparation with the ultrasonic device. [17],[18],[19] Although the importance of chipping in root-end cavity preparation has not been determined, it may affect marginal seal and long-term prognosis of treatment. [7] In the present investigation, chipping was considered as damage to the tooth structure involving intracanal and/or the resected surface. No chipping during root-end cavity preparation may be an advantage of the laser over ultrasonic preparation.

Based on this laboratory study, the WaterLase laser does not produce a clinically relevant rate of cracking when used to make endodontic root-end preparations; future studies are needed to determine the effect of chipping on marginal seal with different laser parameters; SEM studies are also required to find out the reason for crack formation or chipping. Hence, there is minimal chipping and cracking with us.

 Conclusion



The results of this study show that Er,Cr:YSGG laser produces least number of cracks and marginal chipping. Thus lasers can provide good apical seal during root end cavity preparation and increase the success rate of periradicular surgery.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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