ORIGINAL ARTICLE

https://doi.org/10.5005/jp-journals-10063-0151
CODS Journal of Dentistry
Volume 15 | Issue 1 | Year 2023

Effect of Using 5% Apple Vinegar Irrigation Solution Adjunct to Diode Laser on Smear Layer Removal and Calcium/Phosphorus Ion Ratio during Root Canal Treatment

Tarek AA Salam¹ https://orcid.org/0000-0002-4587-4110, Haythem SA Kader² https://orcid.org/0000-0002-1892-6683, Elsayed E Abdallah³ https://orcid.org/0000-0002-6958-0555

¹Department of Oral Radiology and Laser, Faculty of Dentistry, Aswan University, New Minia, Egypt

^2,3Department of Medical Applications of Laser, National Institute of Laser Enhanced Sciences, Cairo University, Giza, Egypt

Corresponding Author: Tarek AA Salam, Department of Oral Radiology and Laser, Faculty of Dentistry, Aswan University, New Minia, Egypt, Phone: +2001006187539, e-mail: tarek_dentist2008@yahoo.com

Received: 15 September 2023; Accepted: 14 March 2024; Published on: 25 April 2024

ABSTRACT

This study was adjusted to assess the cleaning efficacy of using 5% apple vinegar irrigation in adjunct with diode laser 980 nm in removing the smear layer and its effect on the atomic concentration of the calcium/phosphorus (Ca/P) ions by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy, respectively. A total of 60 maxillary incisor teeth were selected to be endodontically treated, prepared biomechanically, and divided equally into three main groups according to irrigation used—the control group—irrigation with 5% sodium hypochlorite (NaOCl) only, group I: irrigation with 5% NaOCl + 17% ethylenediaminetetraacetic acid (EDTA), group II: irrigation with 5% NaOCl + 5% apple vinegar. Diode laser 980 nm, 2 W/CW applied for 10 seconds. Three times in half the number of samples. All samples were divided longitudinally for SEM and SEM-EDX analysis at the coronal, middle, and apical root sections. Results showed group II had a statistically significant lower median smear layer score at the apical third (p < 0.05) when compared to group I and the control group. This study concluded that during root canal treatment, irrigation of 5% apple vinegar irrigation with 5% NaOCl in adjunct to diode laser 980 nm is better than17% EDTA and 5% NaOCl or 5% NaOCl alone in cleaning the intraradicular dentinal walls from the smear layer and also did not alter the atomic concentration of Ca/P ions ratio.

How to cite this article: Salam TA, Kader HS, Abdallah EE. Effect of Using 5% Apple Vinegar Irrigation Solution Adjunct to Diode Laser on Smear Layer Removal and Calcium/Phosphorus Ion Ratio during Root Canal Treatment. CODS J Dent 2023;15(1):3–8.

Source of support: Nil

Conflict of interest: None

Keywords: Apple vinegar, Diode laser, Endo, Smear layer, Scanning electron microscopy, Scanning electron microscopy–energy dispersive X-ray

INTRODUCTION

Cardinal determiners of successful root canal treatment are through shaping and cleaning procedures.

Mechanical instrumentation not only assists in the removal of necrotic tissues from the root canal system but also results in attributes of inorganic/organic material as a smear layer.

In order to widen dentinal tubules and better function as antimicrobial agents, it is imperative to have a competent irrigation solution that can remove the smear layer.¹^-³

It is a firmly established fact from the literature that ethylenediaminetetraacetic acid (EDTA) and sodium hypochlorite (NaOCl), when used singly or together, work as convincing irrigation scheme for purging organic and inorganic detritus material from the smear layer.

It is noteworthy here that while applying this irrigation scheme, the dental hard tissues having calcium (Ca) and phosphorus (P) are negatively impacted. The total Ca/P proportion in the radicular dentin is markedly reduced; other indices like microhardness, solubility, and permeability are also adversely affected. Due to these factorials, the sealing capacity of root canal sealing and resin cements was adversely affected.⁴^-⁶

The conventional way to deliver irrigation solutions to the root canal space with different sizes of conventional syringes and tip designs of needles is inadequate for the proper draining of complex root canal architecture that includes fins, isthmus, and lateral accessory canals. As demonstrated in the literature, the root canal architecture is unaffected up to 35% and above due to chemical-based and mechanical instrumentations.¹^-⁴

Nowadays, the diode laser is being used most in purging the smear layer as it has ease of working, is less expensive, is space-saving, and has an adjustable nature when compared with other lasers. Also, it is noted that a reconstituted smear layer appears in samples drained with water employing a laser 980 nm diode for irradiating the root canal.⁵^-⁷

Previous studies proved that the use of diode lasers induces cavitation in water-based fluids and can enhance smear layer removal.²^-⁴ Hence, the current study aimed to evaluate the cleaning efficiency of using apple vinegar irrigation solution contrary to 17% EDTA and 5% NaOCl solutions in adjunct with diode laser 980 nm in the extrusion of the smear layer against the dentinal walls of intraradicular area by employing scanning electron microscope (SEM) image functional analysis to be correlated with the Ca/P ions ratio concentration using the energy released by X-ray spectroscopy [energy dispersive X-ray (EDX)].

Materials and Methods

Preparation of Samples

After seeking an ethical approval certificate from the National Institute of Laser Enhanced Sciences Research Ethics Committee ”NILES-REC,” Cairo University, Giza, Egypt, under registration number (Cu-NILES/12/22). Having operative dental abnormalities, 60 (n = 60) human maxillary incisor teeth samples were randomized and chosen for the study.

The teeth were assessed radiographically to check for a single canal, apex maturation, and truncation of the absorption process. The teeth having fissures and splinters were not incorporated in the study. Every tooth was cleaned of debris, and with the use of a soft brush, the removal of soft tissues was carried out, and teeth were drained in a 10% concentration formalin liquid solution. Using a contra-angle high-speed air handpiece access cavity using a barbed broach, the pulpal tissue was extirpated, and the functioning length was calculated by infusing a number #10 K file (MANI Inc, Japan) into every root canal as when it starts to be seen forming the apical foramen and thoroughly shaped and clarified in a crown-down manner scheme size #F3 with nickel–titanium ProTaper equipment (Dentsply Maillefer, Ballaigues, Switzerland) rotary file system with torque and speed as stated by manufacturer’s guidelines for each file used.

Irrigation Protocol

Irrigation is made by employing a 27-gauge side vented needle (Appli-Vac, Vista Dental Products, United States of America). The induction of the needle in every canal is made in limits of 1–2 mm functional length. Irrigation was further followed using 2 mL of 5% NaOCl (Alex. Detergents and Chemical Co, Egypt) for 1 minute, and then washed out with distilled water to receive 2 mL of either 17% EDTA (JK Dental Vision, India) or 5% apple vinegar (Yamama, Vinaigre de Pomme 5%) for a minute and between each change of instrument or irrigation with 5% NaOCl solution alone to be considered for the control group. This was accomplished within 10 seconds and repeated three times in 5 seconds. Interval resulted in a total irradiation time of 30 seconds. Only half the number of all teeth from all groups was irradiated by the laser beam.

Samples Grouping

The samples (n = 60) were distributed into three groups established on the type of irrigation solution being utilized for the smear layer purging and Ca/P ions ratio precipitation altogether and subdivided into (A = sample not irradiated with the laser) and (B = sample irradiated with the laser) as follows:

Placebo control group A: Sample size (n = 10) irrigation with 5% NaOCl only.
Control group B: Sample size (n = 10) irrigated using 5% NaOCl and subsequent laser irradiation.
Group IA: (n = 10) 5% NaOCl, then 17% EDTA solution.
Group IB: (n = 10) 5% NaOCl, then 17% EDTA solution followed by laser irradiation.
Group IIA: (n = 10) 5% NaOCl, then 5% apple vinegar solution.
Group IIB: (n = 10) 5% NaOCl, then 5% apple vinegar solution followed by laser irradiation (Fig. 1).

Fig. 1A to R: Scanning electron microscope micrographs of different groups of samples

Smear Layer Evaluation

Scanning electron microscope (SEM) micrographs were carried out to examine the irrigant efficiency used in the eviction of the smear layer coming out of dentinal walls. Employing a low-speed straight handpiece longitudinal grooves on the buccal and lingual surfaces of all the roots, placed with a safe-sided diamond disc (NTI diamond disc, Axis Dental, United States of America) subsumed with continuous water spray without penetration of the canal that was done by a chisel to divide them into two halves. The samples were analyzed by SEM (Thermo, Ultradry FEI Quanta 250-FEG, Czech Republic) and were observed under 6000× magnifications for verification of the patency of the dentinal tubules. Micrographs were recorded from the top, bottom, and coronal portions of root canals (individually 3 mm from root apex). Further recordings were made applying a scoring system suggested by Rome et al.,⁸ as follows:

First score: Dentinal tubules are well open and cleared, there is a total absence of a smear layer, and the root canal walls are cleansed.
Second score: Negligible amounts of smear layer; having above 50% of the dentinal tubules wide open.
Third score: Medium levels of smear layer as fewer as 50% of dentinal tubules open wide.
Fourth score: Considerable amounts of smear layer having through the obliteration of dentinal tubules.

Finally, the surface elemental composition was examined by EDX microanalysis equipment (Octane Plus Silicon Detector, Team Enhanced, v.4.3.) to calculate values of atomic percentages Ca and Pin their elemental forms as were correlated using scanning electron microscopy with energy dispersive X-ray (SEM-EDX) devices in the current study.

Statistical Analysis

Statistical analyses were used by employing IBM® SPSS® Statistics Version 20 for Windows. Data normality was calculated using Kolmogorov–Smirnov and Shapiro–Wilk tests. For every group, mean and standard deviation were calculated. For parametric EDX data between two groups in related samples, repeated measure analysis of variance was used. Friedman was used as a nonparametric data (SEM data) to compare more than two groups in related samples. Relationship and interobservers’ reliability between the three readings of different observers for SEM evaluation was measured using different measurements. The significance levels were established at p ≤ 0.05.

RESULTS

With reference to SEM evaluation, it revealed that 5% apple vinegar irrigation solution + 5% NaOCl (group II) had an improved outcome in extruding the smear layer from intraradicular dentine than with either 5% NaOCl alone ”the control group” or 5% NaOCl + 17% EDTA solution ”group I” in all sample’s sections that were exposed to the laser. While without laser subgroups, group II showed the same results except for the apical section, which had the same statistically significant lower median smear layer score as group I, but both still had a lower score than the control group.

The study results revealed that laser irradiation reduced the amount of smear layer in all third samples. Subgroup IIB showed the least amount of smear layer precipitation, followed by subgroup IB, and then the last one was the (control B) subgroup. Laser irradiation decreases smear layer values in the apex third in group II as statistically significant alterations were observed among groups IB and IIB (p = 0.029) (Table 1).

**Table 1:** The mean values of SEM scores for groups
Variables	SEM
	Coronal		Middle		Apical
	Without laser	With laser	Without laser	With laser	Without laser	With laser
Control	3.1	1.4	3.1	1.6	3.5	2.5
Group I	3	1.3	2.5	1.4	2.8	2.6
Group II	1.4	1.1	1.8	1.3	2.8	1.8
p-value	0.001*	0.001*	0.028*	<0.001*	0.002*	<0.001*

*Significant (p < 0.05)

Apical third portions in all groups appeared to have the largest quantity of smear layer formed as related to the coronal and medium third sections. Additionally, all laser subgroups showed a lesser amount of smear layer in the apical third when compared to the without laser subgroups in the same third. The minimum volumes of smear layer were established in the third coronal section of group IIb, while the largest amount was found in the apical thirds of samples not irradiated to laser in the control group (Table 2).

**Table 2:** The mean values of SEM scores for thirds
Variables	SEM
	Control		Group I		Group II
	Without laser	With laser	Without laser	With laser	Without laser	With laser
Coronal	3.1	1.4	3	1.3	1.4	1.1
Middle	3.1	1.6	2.5	1.4	1.8	1.3
Apical	3.5	2.5	2.8	2.6	2.8	1.8
p-value	0.289 (NS)	0.001*	0.423 (NS)	0.001*	0.001*	0.015*

*Significant (p < 0.05); NS, nonsignificant (p > 0.05)

Regarding SEM-EDX results, in group comparison, the ratio of the Ca/P ions showed that the largest amount of ion precipitation was found in the third apical portion of group IB, while the least amount was found in the similar third portion in the irradiated control group. There was a random relation between the laser effect on calcium/phosphate (Ca/P) ions and their concentration, shown as an increase in ratio after laser irradiation in some middle third portion of the control group and altogether third portions in coronal and apical parts of group I, while Ca/P ions concentration decreased in all thirds of group II after laser irradiation (Fig. 2).

Fig. 2: Bar chart representing the effect of laser irradiation on Ca/P ions atomic ratio in group comparison

DISCUSSION

The cardinal delimiting factor of good endodontic treatment is proper expatriation of the smear layer from the dentinal walls.⁷ Therefore, the present study analyzed the repercussions of applying different liquid irrigation solutions to several sections of teeth, such as coronal, middle, and apical.

Studies from the literature suggest that traditionally used irrigation methods would be more capable of cleansing coronal sections of root canals but less practical in the third apical portion of the canals.⁷ Other workers suggest that two discrete compartments of a smear layer exist—the superficial smear layer and clogged debris in the dentinal tubules.⁶ The smear layer functions as a physical impediment against the infusion of therapeutics and irrigation solution inside dentinal tubules.⁹^,¹⁰

Several irrigating solutions have been used in this study in adjunct to diode laser to achieve the purpose categorically through expulsion of organic debris from the root canal architecture, which is a promising technique that claims to have better functioning irrigant’s capacity, although due to intricate branching meshwork of the root canal system, total smear layer eviction from the dentinal tubules has not been successfully attained only with the use of some of these irritants, predominantly at the third apex portion of root canal.⁷^,¹¹^,¹²

A predetermined parameter of laser of wavelength 980 nm was made to work in this study based on other studies, which revealed such indices produced a temperature hike of approximately 10°C, which doesn’t bridge the benchmark maintained by the periapical tissues.⁶^-⁹ In addition, it is proven that the diode lasers can efficiently remove the smear layer and disinfect the lateral and accessory canals, plus their antibacterial property, which is accredited to the increase in temperature taking place inside the root canals on irradiation.²^,⁷^,¹³

Some ultramorphological changes such as limited melting, fusion, and constricted gate entries of dentinal tubules were observed in quite a lot of samples in this study that may be attributed to the melting and evaporating property of the laser on the smear layer due to the photon-mediated chemical and thermal plasmolysis and severances, along with acoustic effects of photons due to diode lasers.⁷^,¹³

Some studies reported that the third apical had diminished smear layer values contrary to the middle and third coronal while using thin, flexible fiber of 200 μm laser tips, which came in contrast to this study’s results that showed more smear layer scores in apical sections when using greater diameter of the laser tip of 320 μm. This can be explained by the thinner diameter of the canal at the apex that prevented the laser tip from reaching the apical section closely, and the thin laser tips offer a superior approach to the apex that finally leads to better capability of smear layer purgation at the apex (Fig. 2).¹⁴^-¹⁷

In contrast, other authors reported that the cleansing of the third middle and cervical was more convincing than in the third apical, as observed in this study. They concluded that the smear layer removal was much easier in these thirds due to the diameter of the canals, which permitted superior irrigating solution circulation plus action. Also, an in-depth account of the needle would allow better cleansing yet would present a holistic hazard of damaging the periapical tissues with proficient expulsion of irrigating solutions.¹⁸^,¹⁹

Scanning electron microscope is used in this study with 6000× magnification as it is commonly used for the identification of smear layer on the complete walls of the root canal after a biomechanical endodontic arrangement to accomplish complete images with advanced imaging focused on the dentinal tubules.¹³

This study used 17% EDTA solution as an irritant because it has been permitted to be a remarkable smear layer removing potential besides having chelating prospects that would alter the root dentin microstructure. This came per a prior study done by Rao et al., which revealed that irrigation using 17% EDTA with a volume of 10 mL irrigation for 1 minute was found to be efficient in purging the smear layer, but a 10-minute application caused enormous peritubular and intertubular dentinal abrasions.⁸^,²⁰

In the current study, SEM images of group IA (irrigation with NaOCl and EDTA without laser exposure) showed the presence of a sensible amount of the smear layer all through the functioning length of the canals, chiefly in the apex fragment of the root canal and siege of dentinal tubules which came following similar earlier studies done by Torabinejad et al., and Goldman et al., that conferred NaOCl and EDTA would be ineffective in expunging the smear layer from third apical.²¹^,²²

In addition, the results of this research showed that the smear layer present throughout the apical section of group IB was approximately similar to what was found in the apical section of group IIB, but both were still lighter than the same section in the control group in without laser subgroups (Fig. 1).

In group IB of this study, the addition of laser after irrigation aided in escalating smear layer withdrawing capacity in all root canal portions, which came similar to a previous study done by Karunakar et al., which reported that the extension of EDTA after ultrasonics manifested in incrementing the smear layer evicting potential of EDTA by boosting its insertion in dentinal tubules of root canals.⁶

The effectiveness of the alliance between NaOCl and EDTA solutions in the elimination of the smear layer has been noted in many previous studies. The authors explained this association by the decalcification of the peritubular and intertubular dentine that occurred after using the EDTA irrigation solution, leaving the collagen exposed. Meanwhile, the NaOCl solution dissolves collagen and subsequently opens and exposes the entrance of the dentinal tubules. From another point of view, previous authors have warranted this association, which results in acute impediments to the surfaces of canal walls. But indeed, such erosion has the potential to raise the dentine permeability and allow for better insertion of root Ⴁlling substances in dentinal tubules as well as lateral canals.¹⁹^,²¹^,²³

The functional mechanism lies in the fact that there would not be any irrigating solution that altogether works on organic and inorganic components of the smear layer. Therefore, it is the need of the hour to look for a more promising chelating agent that has biological compatibility with the EDTA solution and apple vinegar employed in the present study due to its antimicrobial, economic viability, chelating capacity, and biological consonance.²⁴

Therefore, group II with both subdivisions (I and II) conferred reduced median smear layer numbers coupled with the coronal and third middle related to that in group I.

The above findings indicate that apple vinegar has acidic compositions, with malic as the chief acid, which is liable for the considerable alterations in the therapeutic properties of apple vinegar. These grades came in agreement with former studies that stated that apple vinegar is efficient in removing the smear layer. ²⁴^-²⁶

ORCID

Tarek AA Salam https://orcid.org/0000-0002-4587-4110

Haythem SA Kader https://orcid.org/0000-0002-1892-6683

Elsayed E Abdallah https://orcid.org/0000-0002-6958-0555

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