Desensitizing Efficacy of Nano-Carbonate Apatite Dentifrice and Er,Cr:YSGG Laser: A Randomized Clinical Trial

Abstract

Objective: The aim of this study was to evaluate the desensitizing effects of a dentifrice containing nano-carbonate apatite (n-CAP) and Er,Cr:YSGG laser in the treatment of dentin hypersensitivity. Background data: Most studies of hypersensitivity treatment have been conducted with different methods of professional treatment and self-care in each study. Moreover, clinical studies that compare self-care and professional treatment have not yet been published. Methods: Eighty-two patients with dentin hypersensitivity were divided randomly into three groups: (1) a control group with strontium chloride dentifrice (SC), (2) n-CAP dentifrice (n-CAP), and (3) an Er,Cr:YSGG laser (laser) group. The study was conducted for 4 weeks: a treatment period of 2 weeks and a maintenance period of 2 subsequent weeks. The SC and n-CAP groups were instructed to brush their teeth twice a day for 1 min. The laser group visited twice at 1 week intervals for irradiation of the sensitive teeth. The desensitizing effect was evaluated by assessing the tactile sensitivity using the visual analogue scale (VAS), and evaporative air sensitivity was determined using an air blast score (ABS). Results: The n-CAP group and the laser group showed significantly different desensitizing effects in VAS after 4 weeks (69% and 63%, respectively) and a 33% (p<0.05) and 3% (p>0.05) desensitizing effect, respectively, in VAS during the maintenance period. Conclusions: The n-CAP and the laser were effective in reducing dentin hypersensitivity. The laser had a superior desensitizing effect at the initial stage, whereas the n-CAP maintained its effect for a relatively longer time in clinical situations.

Introduction

Dentin hypersensitivity is one of the most common dental diseases, occurring in 4–73% of adults.^1,2 Treatments to relieve dentin hypersensitivity are based on two major methods: the occlusion of exposed tubules to block the hydrodynamic mechanism of pain stimulation or the interruption of the neural responses to a stimulus.³ Two approaches have also been taken for the treatment of dentin hypersensitivity. The first approach is home treatment of the symptoms using desensitizing dentifrices.⁴ The second approach is professional treatment in a dental office using fluoride varnish, restorative resins, and laser therapy.^5,6 However, most patients with hypersensitivity first try self-care using desensitizing dentifrices, which can be used easily at home, prior to visiting a dental clinic. The home method is also recommended as a first line of treatment because it is noninvasive and economical.⁷

Desensitizing dentifrices typically contain desensitizers such as strontium chloride (SC),^8,9 calcium carbonate,¹⁰ sodium fluoride,¹¹ or potassium salts.¹² These desensitizers have different mechanisms. All of these desensitizers, SC is the most widely used for desensitizing treatments, and it works through the closure of the exposed dentinal tubules.^8,13 However, SC has no desensitizing effect over the long term, and its effects have only been proven in short-term studies.¹⁴ Another desensitizer is carbonate apatite, which reacts with the dentinal tubules more strongly. Recently, dentifrices containing nano-sized carbonate apatite have been developed. The nano-sized carbonate apatite has a greater solubility, combining with the dental tissues.^15
–17 Dentifrice containing n-CAP has also been developed, and showed a superior occluding effect in vitro. A previous study on self-care for dentin hypersensitivity reported that 20% n-CAP dentifrice had an occluding rate for dentinal tubules of 79.5% compared with the baseline (p<0.05).¹⁶

Laser therapy is another treatment of choice among dental professionals for the closure of dentinal tubules, which works by melting and recrystallizing the dentin surface.¹⁸ The lasers are classified as either low-power or high-power lasers. Low-power laser therapy is used to heal wounds in order to enhance biomodulatory effects as well as decrease nerve transmission; these include the helium-neon (He-Ne) and gallium/aluminum/arsenide (GaAlAs) (diode) lasers.¹⁹ High power lasers, such as Nd:YAG, Er:YAG, and Er,Cr:YSGG laser, are used to increase the dentin surface temperature to close the dentinal tubules. Among the high-power lasers, the Er:YAG laser is expected to be particularly effective in dental applications because of the high absorption of its wavelengths by water.²⁰ The use of an Er:YAG laser as a desensitizing treatment is expected to decrease fluid movements by evaporating the superficial layers of the dentinal fluid.

The Er,Cr:YSGG laser is a new device that has been recently applied for the treatment of dentin hypersensitivity in dental clinics. The Er,Cr:YSGG laser belongs to the Er:YAG laser system class because of the similarity of its wavelengths (2.78 and 2.94 μm, respectively).²¹ The Er,Cr:YSGG laser can give rise to chemical surface alteration and can change the mineral content of enamel and dentin.²²

The Er,Cr:YSGG laser also provides more effective adhesion to worn dentin when compared with the Er:YAG laser.²³ A previous study reported that the high absorption of the Er,Cr:YSGG laser emission wavelength (2.78 μm) by water might result in the evaporation of the tubule fluid and the smear layer.²⁴ Studies using this laser have, therefore, focused on finding the treatment mechanism or comparing it with several types of lasers in terms of efficacy as an in vitro desensitizing treatment.^25,26 Clinical studies using Er,Cr:YSGG laser for treating hypersensitivity have also been reported.^23,24,27

Most of the current studies on hypersensitivity treatment have been conducted using either professional (desensitizing agents, fluoride gel, varnish, and lasers) or self-care (various desensitizing dentifrices) treatments. Only three in vitro studies have compared at-home and in-office methods for desensitizing treatment.^15,17,28 Self-care is economical and easily adapted to daily life activities, but self-care methods have some limitations in that the effect on the tooth surface is not maintained over a long period of time because of rinsing or drinking acidic beverages. In contrast, professional treatments appear to be immediately effective and the effect is longer lasting than those of dentifrices. However, professional treatment presents an economic burden and the inconvenience of dental clinic visits.

The present study focused on the clinical effects of professional treatment and self-care, to provide more valid information for hypersensitivity patients when trying to choose an appropriate treatment. The aim of this study was to compare the clinical efficacy of an n-CAP dentifrice and the Er,Cr:YSGG laser for patients with dentin hypersensitivity.

Materials and Methods

Participants

This study was designed as a randomized, single-blinded clinical trial (RCT). The research protocol was initially submitted for approval by the Ethics Committee of the Yonsei Dental Hospital, Seoul, Republic of Korea (IRB No. 2-2008-0001). Data collection was completed in the Department of Advanced General Dentistry at Yonsei University Dental Hospital. There were two assessors, S.Y.L. and H.I.J., who had been trained for calibration. Neither of the assessors participated in treatment procedure. to maintain blindness. Laser irradiation was applied by only one investigator, B.Y.J. Participants were fully informed about the purpose and procedures of this study, and voluntarily provided written informed consent. Inclusion criteria from the study were: (1) having at least two hypersensitive teeth that were scored >4 according to the visual analogue scale (VAS) and scored >1 according to the air blast, and (2) having exposed root surfaces from which a painful response was elicited by a dental probe and air blast.¹² Participants were excluded if they had one of the following conditions: (1) chronic disease; (2) carious lesions on the selected or neighboring teeth; (3) any desensitizing therapy on the selected teeth during the last 2 months; (4) cervical filling, nonvital teeth, and cracks on the selected teeth; or (5) pregnancy or side effects from a laser.²⁹

In total, 102 of 161 volunteers were selected who satisfied both the exclusion and inclusion criteria. The participants were between 20 and 65 years of age (mean age: 37.2 years). The final number of participants was 82 (29 males, 53 female) with 181 teeth, because 20 participants dropped out of the study (Fig. 1). These 20 were excluded from this experiment because they did not attend follow-up appointments.

FIG. 1.

Flow of participants through each stage of the trial. SC, strontium chloride; n-CAP, nano-carbonate apatite; Laser, Er,Cr:YSGG laser.

Evaluation of dentin hypersensitivity

Assessment of tactile sensitivity threshold

The sensitivity of teeth to tactile stimulation was measured using a pressure indicating probe (PDT sensor probe-type C, Zila Pharmaceuticals, Inc., USA). This probe was used to stroke the exposed surface regularly for 1∼2 sec at a preset force of <25g. Patients were asked to record a mark on a 10 cm visual analogue scale (VAS) line to indicate the intensity of their current level of sensitivity. The bottom of the line indicated no pain (0) and the top, unbearable pain (10).

Assessment of evaporative air sensitivity

The sensitivity response to a 2 sec application of air blast was evaluated using the air syringe of a standard dental unit, and the temperature of the air blast was 17° to ∼21°C. The air blast was directed perpendicularly to the exposed dentin at a distance of 2∼3 mm after isolating the test tooth to exclude false positive results. The sensitivity to the air blast was recorded using the air sensitivity scale by Schiff et al.³⁰ This air scale was scored as follows:

0=Tooth/subject does not respond to air stimulus

1=Tooth/subject responds to air stimulus but subject does not request discontinuation of stimulus

2=Tooth/subject responds to air stimulus and subject requests discontinuation or moves from stimulus

3=Tooth/subject responds to air stimulus, subject considers stimulus to be painful, and requests discontinuation of the stimulus

Treatment

The participants were randomly divided into the following three groups: (1) positive control group, SC dentifrice; (2) experimental group 1, 20% n-CAP dentifrice; and (3) experimental group 2, Er,Cr:YSGG laser. The positive control group was treated with a representative desensitizing dentifrice containing 10% SC and 10% CaCO₃ (Sensodyne Original^®, Glaxo Smith Kline, USA), the experimental group 1 used a dentifrice containing 20% n-CAP and 8% silica (Dentiguard Sensitive^®, Daewoong Co., Ltd., Korea). The type of laser used in experimental group 2 was an Er,Cr:YSGG laser (Waterlase^®MD, Biolase. Inc., USA), a type of Er:YAG laser. The laser irradiation was divided into three phases according to the manufacturer's recommended settings. The first and second phases were supplied with water [0.25 W, 20 pulses per sec (pps), 16% water, 16% air], whereas the third phase was conducted without water and the laser treatment was implemented for 30 sec in each phase.

All participants received supra- and subgingival scaling prior to entry into the study. All participants received the dentifrice tested in each group and used the same toothbrush with flat and soft bristles (Skydent NO.32 SOFT^®, SKYDENT, Korea), and they were instructed to brush their teeth twice a day for 1 min every time with the same tooth-brushing method that they usually used.

This study had an experimental period of 4 weeks. During the first 2-week treatment period, the SC, the n-CAP, and the laser treatments were applied to each group. For the subsequent 2-week maintenance period, all participants performed only tooth brushing with the same fluoride dentifrice (Perio Cavity Care,^® LG Household & Health Care, Korea) without any desensitizing ingredients. All participants underwent the tactile test and air blast test twice at intervals of 1 week.

Statistical analysis

The results of this study were analyzed using the SPSS 12.0 statistical package program (SPSS Inc., USA). Repeated measures ANOVA and the Bonferroni post-hoc test were performed to analyze the differences in desensitizing effects over time on the 1st, 2nd, and 4th weeks. Also, one way ANOVA was performed to determine significant differences among the groups.

Results

The data of this study are patient based. Patients who had two or more hypersensitive teeth were evaluated by the mean value of the scores. Baseline VAS scores for the tactile test ranged between 6.04 and 6.26 in all three groups (Table 1). The VAS score decreased significantly during the treatment periods in all groups (p<0.05), but no significant difference was noted among the groups. The reduction patterns showed a similar tendency and a significant desensitizing effect in all groups, but the laser group showed the strongest desensitizing effect after 1 week (SC, 35%; n-CAP, 39%; laser, 54% vs. baseline, p<0.05 for all).

Table 1.

VAS Score on Tactile Test of All Subjects for 4 Weeks (Mean±SD)

		Experimental periods
		Treatment period		Maintenance period
Groups	n	Baseline	1 week	2 weeks	4 weeks	p Value
SC	30	6.26±1.59^a	4.05±2.25^b	3.20±1.78^c	2.74±2.09^c	<0.05
n-CAP	30	6.04±1.34^a	3.67±1.83^b	2.84±1.96^c	1.88±1.82^d	<0.05
Laser	22	6.22±1.42^a	2.85±2.17^b	2.39±2.29^b	2.32±2.55^b	<0.05

a,b,c

The same characters indicate no significant differences at Bonferroni's multiple comparison by repeated measure ANOVA at different treatment and maintenance periods (α=0.05).

SC, strontium chloride; n-CAP, nano-carbonate apatite; laser, Er,Cr:YSGG laser.

The VAS scores of the n-CAP group were continuously decreased during the maintenance period without further use of the n-CAP dentifrice from 2 to 4 weeks, and the desensitizing effect during the maintenance period was 33%, which was statistically significant when compared with the treatment period (p<0.05). After 4 weeks, the n-CAP group showed a total desensitizing effect of 69%. For the laser group, the VAS score showed a total desensitizing effect of 63% after 4 weeks, and the desensitizing effect during the maintenance period was 3%, for which differences were not statistically significant (Table 1).

The air blast test scores (ABS) showed statistically significant differences by treatment period (p<0.05). After treatment for 1 week, a significant difference was noted among the groups (p<0.05). The laser group showed the highest reduction in sensitivity, and the ABS of the laser group greatly decreased to 51% in 2 weeks (p<0.05) and stayed at 46% up to 4 weeks. The ABS of the SC and n-CAP groups decreased to 37% and 40%, respectively, in 2 weeks (p<0.05) and the n-CAP group stayed at 37% up to 4 weeks (p<0.05). This effect continued even during the maintenance period from 2 to 4 weeks, but no statistically significant difference was observed (Table 2).

Table 2.

Air Score on Air Blast Test of All Subjects for 4 Weeks (Mean±SD)

		Experimental periods
Groups	n	Baseline	1 week	2 weeks	4 weeks	p Value
SC	30	1.92±0.70^a	1.55±0.66^A,B	1.21±0.63^c	1.26±0.74^c	<0.05
n-CAP	30	1.85±0.66^a	1.34±0.63^A,B,b	1.11±0.70^c	1.16±0.69^b,c	<0.05
Laser	22	2.11±0.40^a	1.03±0.48^B,b	1.05±0.55^b	1.13±0.64^b	<0.05
p Value		-	<0.05	-	-

a,b,c

The same characters are not significant at Bonferroni's multiple comparison by repeated measure ANOVA at different experimental periods (α=0.05).

A,B

The same characters are not significant at Scheffe's multiple comparison by one way ANOVA among groups (α=0.05).

SC, strontium chloride; n-CAP, nano-carbonate apatite; laser, Er,Cr:YSGG laser.

Discussion

This study evaluated the clinical effects of the professional treatment and the self-care treatment to provide realistic information about appropriate treatments for dentin hypersensitivity patients. The present study investigated the effect of hypersensitivity treatment with 82 patients for 4 weeks. Unlike the treatment period of the present study, many past studies on hypersensitivity desensitization have shown effective results with observation periods between 4 and 24 weeks.^31,32 However, the long-term clinical trials of SC that lasted >12 weeks were unable to confirm a clinical effect.³³ Previous studies have also examined the effects of short-term use, and desensitizing effects showed that short-term use of 20% n-CAP dentifrices for pain relief was more effective than long-term use.³⁴ Therefore, this study focused on the short-term desensitizing effects that considered a treatment period and a maintenance period of 4 weeks.

The assessment of hypersensitivity symptoms commonly uses tactile and thermal stimuli. Other than the common methods, this study also applied air blast stimulation in a temperature test. Some authors recommend the application of more than one stimulation.³⁵ The air blast was considered to be the most appropriate method as a single in vivo stimulation.^29,36

The VAS scores were used as an assessment method for the tactile test. This method is widely used for pain assessment and is easily understood by patients, making it an adequate tool for the evaluation of pain on dentin hypersensitivity. According to the results of the present study, both tactile and air blast tests showed statistically significant differences by treatment period in all groups (p<0.05). The SC and the n-CAP groups showed statistically significant decreases in both tactile and air blast tests for 2 weeks while using the test dentifrice (p<0.05). The VAS scores of the n-CAP group were greatly reduced (69%) until the maintenance period without the n-CAP dentifrice (p<0.05). These results are in accordance with Orsini's study, who showed that new dentifrices containing nanostructured carbonate/hydroxyapatite may significantly reduce sensitivity symptoms compared with a control group at 4 weeks.³⁷ In addition, the VAS scores of the n-CAP group during the maintenance period showed a 33% desensitizing effect (p<0.05). These results would be attributable to the relatively longer- lasting effect because of the excellent adhesion of n-CAP, which creates a thick protective layer on the smear layer by forming a thick mixture with abrasive particles, tooth debris, and other materials on the dentin surface during tooth brushing. The n-CAP has excellent adhesion with a wide surface area, and is highly reactive. As tooth brushing is continued, a stable protective layer will be maintained by the renewal of some of the particles and the continuous supply of new n-CAP. As a result, particles can occlude the dentinal tubules with smear layers created by tooth brushing.³⁸ The occlusion effect of the dentifrice containing n-CAP has already been proven in previous in vitro studies.^15,17,38 An in vitro study also showed a tubule occlusion rate of 89% with a 20% n-CAP dentifrice compared with a control group.¹⁵

On the other hand, the use of the Er,Cr:YSGG laser as the professional treatment in this study had an advantage in that it applied minimal stimulation to the tooth hard tissue, as the water absorption of the hydroxyapatite structure increased the hydroxyl radical desensitizing effect. In this study, the sensitivity following Er,Cr:YSGG laser treatment was greatly reduced by 61% and 51% in the tactile and air blast tests in 2 weeks, respectively. In contrast, the n-CAP group showed desensitizing effects of 53% (VAS) and 40% (ABS) in 2 weeks. Additionally, a significant difference occurred among the groups (p<0.05), that can be explained by the melted surface formed by laser irradiation being less sensitive to the air blast.

The VAS scores obtained from the laser group were distinctively reduced during the treatment period, and then remained consistent during the maintenance period without any decrease in the scores. The results of this study are in accordance with a previous study, in which the mean pain level in the 0.25 W Er,Cr:YSGG laser group was decreased compared with the Er:YAG laser group 1 month after treatment, in a short-term clinical trial.²³ The Er,Cr:YSGG laser would also be a caries prevention treatment and would have a solubility-reducing effect on enamel and dentin because of a greatly enhanced acid resistance in the enamel structure as a result of the duration of the chemical changes. However, clinicians need to be aware of the safety guidelines and correct usage, because improper use of the Er,Cr:YSGG laser can be dangerous to oral tissues.

In summary, the SC dentifrice, the n-CAP dentifrice, and the Er,Cr:YSGG laser were all effective for the treatment of dentin hypersensitivity. The n-CAP dentifrice had the same desensitizing effects as the SC dentifrice, which is a representative desensitizing dentifrice. Moreover, the desensitizing effect of the n-CAP dentifrice on tactile stimulation was somewhat longer lasting than that of the SC dentifrice. During the maintenance period after the treatment, the Er,Cr:YSGG laser was no more effective than the n-CAP dentifrice against sensitivity to the air blast. However, the n-CAP dentifrice is expected to be more effective in terms of endurance than an occluding treatment, because the n-CAP dentifrice showed superior desensitizing effects during the maintenance period. When convenience, time, and cost effectiveness are taken into account, the n-CAP dentifrice can be recommended as an appropriate treatment for dentin hypersensitivity.

However, the use of Er,Cr:YSGG laser as the professional treatment shows a superior initial desensitizing effect immediately after treatment relative to that of n-CAP. Therefore, it can be considered that the desensitizing effect can be maintained for a long time when the professional laser treatment is performed on the hypersensitivity patient following self-care with the n-CAP. Meanwhile, this study did not evaluate any synergistic effect of combined treatments with both the dentifrice and the laser. The small sample size was also another limitation. Therefore, further study is needed to evaluate the combined effects of the n-CAP dentifrice and the Er,Cr:YSGG laser with sufficient samples based on a sample size estimation.

Conclusions

This clinical study demonstrated that the use of both the desensitizing dentifrices containing 20% n-CAP as self-care and the Er,Cr:YSGG laser as professional treatment were effective in reducing dentin hypersensitivity. The Er,Cr:YSGG laser in particular had a superior desensitizing effect initially, whereas the n-CAP dentifrice maintained this effect for a relatively longer time. Further study and serious consideration should be given to the therapeutic effect of combined therapy.

Footnotes

Acknowledgments

This work was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Education, Science and Technology (R13-2003-013-05002-0).

Author Disclosure Statement

No competing financial interests exist

References

Rees

, Addy

. A cross-sectional study of dentine hypersensitivity. J Clin Periodontol, 2002; 29:997–1003.

Irwin

, McCusker

. Prevalence of dentine hypersensitivity in a general dental population. J Ir Dent Assoc, 1997; 43:7–9.

Porto

, Andrade

, Montes

. Diagnosis and treatment of dentinal hypersensitivity. J Oral Sci, 2009; 51:323–332.

Orsini

, Procaccini

, Manzoli

, Giuliodori

, Lorenzini

, Putignano

. A double-blind randomized-controlled trial comparing the desensitizing efficacy of a new dentifrice containing carbonate/hydroxyapatite nanocrystals and a sodium fluoride/potassium nitrate dentifrice. J Clin Periodontol, 2010; 37:510–517.

Palazon

, Scaramucci

, Aranha

, et al. Immediate and short-term effects of in-office desensitizing treatments for dentinal tubule occlusion. Photomed Laser Surg, 2013; 31:274–282.

Yilmaz

, Kurtulmus–Yilmaz

, Cengiz

. Long-term effect of diode laser irradiation compared to sodium fluoride varnish in the treatment of dentine hypersensitivity in periodontal maintenance patients: a randomized controlled clinical study. Photomed Laser Surg, 2011; 29:721–725.

Orchardson

, Gillam

. Managing dentin hypersensitivity. J Am Dent Assoc, 2006; 137:990–998; quiz 1028–1029.

Kobler

, Kub

, Schaller

, Gernhardt

. Clinical effectiveness of a strontium chloride- containing desensitizing agent over 6 months: a randomized, double-blind, placebo-controlled study. Quintessence Int, 2008; 39:321–325.

Liu

, Hu

. Efficacy of a commercial dentifrice containing 2% strontium chloride and 5% potassium nitrate for dentin hypersensitivity: a 3-day clinical study in adults in China. Clin Ther, 2012; 34:614–622.

10.

Paes Leme

, dos Santos

, Giannini

, Wada

. Occlusion of dentin tubules by desensitizing agents. Am J Dent, 2004; 17:368–372.

11.

Plagmann

, Konig

, Bernimoulin

, Rudhart

, Deschner

. A clinical study comparing two high-fluoride dentifrices for the treatment of dentinal hypersensitivity. Quintessence Int, 1997; 28:403–408.

12.

Wara-aswapati

, Krongnawakul

, Jiraviboon

, Adulyanon

, Karimbux

, Pitiphat

. The effect of a new toothpaste containing potassium nitrate and triclosan on gingival health, plaque formation and dentine hypersensitivity. J Clin Periodontol, 2005; 32:53–58.

13.

Pinto

, Silveira

, Pochapski

, Pilatt

, Santos

. Effect of desensitizing toothpastes on dentin. Braz Oral Res, 2012; 26:410–417.

14.

Silverman

, Berman

, Hanna

, et al. Assessing the efficacy of three dentifrices in the treatment of dentinal hypersensitivity. J Am Dent Assoc, 1996; 127:191–201.

15.

Kim

, Han

, Kwon

, Kim

. Synergistic effect of dentinal tubule occlusion by nano-carbonate apatite and CO2 laser in vitro. Photomed Laser Surg, 2013; 31:392–397.

16.

Lee

, Kwon

, Kim

. Effect of dentinal tubule occlusion by dentifrice containing nano-carbonate apatite. J Oral Rehabil, 2008; 35:847–853.

17.

Han

, Jung

, Kwon

, Kim

. Combined effects of Er:YAG laser and nano-carbonate apatite dentifrice on dentinal tubule occlusion: in vitro study. Photomed Laser Surg, 2013; 31:342–348.

18.

Sgolastra

, Petrucci

, Severino

, Gatto

, Monaco

. Lasers for the treatment of dentin hypersensitivity: a meta-analysis. J Dent Res, 2013; 92:492–499.

19.

Corona

, Nascimento

, Catirse

, Lizarelli

, Dinelli

, Palma–Dibb

. Clinical evaluation of low-level laser therapy and fluoride varnish for treating cervical dentinal hypersensitivity. J Oral Rehabil, 2003; 30:1183–1189.

20.

Ando

, Aoki

, Watanabe

, Ishikawa

. Bactericidal effect of erbium YAG laser on periodontopathic bacteria. Lasers Surg Med, 1996; 19:190–200.

21.

Hossain

, Nakamura

, Yamada

, Kimura

, Matsumoto

. Effects of Er,Cr:YSGG laser irradiation in human enamel and dentin: ablation and morphological studies. J Clin Laser Med Surg, 1999; 17:155–159.

22.

Harashima

, Kinoshita

, Kimura

, et al. Morphological comparative study on ablation of dental hard tissues at cavity preparation by Er:YAG and Er,Cr:YSGG lasers. Photomed Laser Surg, 2005; 23:52–55.

23.

Aranha

, Eduardo Cde

. Effects of Er:YAG and Er,Cr:YSGG lasers on dentine hypersensitivity. Short-term clinical evaluation. Lasers Med Sci, 2012; 27:813–818.

24.

Yilmaz

, Kurtulmus–Yilmaz

, Cengiz

, Bayindir

, Aykac

. Clinical evaluation of Er,Cr:YSGG and GaAlAs laser therapy for treating dentine hypersensitivity: a randomized controlled clinical trial. J Dent, 2011; 39:249–254.

25.

Adu–Arko

, Sidhu

, McCabe

, Pashley

. Effect of an Er,Cr:YSGG laser on water perfusion in human dentine. Eur J Oral Sci, 2010; 118:483–488.

26.

Gholami

, Fekrazad

, Esmaiel–Nejad

, Kalhori

. An evaluation of the occluding effects of Er;Cr:YSGG, Nd:YAG, CO(2) and diode lasers on dentinal tubules: a scanning electron microscope in vitro study. Photomed Laser Surg, 2011; 29:115–121.

27.

Yilmaz

, Cengiz

, Kurtulmus–Yilmaz

, Leblebicioglu

. Effectiveness of Er,Cr:YSGG laser on dentine hypersensitivity: a controlled clinical trial. J Clin Periodontol, 2011; 38:341–346.

28.

Al-Azzawi

, Dayem

. A comparison between the occluding effects of the Nd:YAG laser and the desensitising agent sensodyne on permeation through exposed dentinal tubules of endodontically treated teeth: an in vitro study. Arch Oral Biol, 2006; 51:535–540.

29.

Schwarz

, Arweiler

, Georg

, Reich

. Desensitizing effects of an Er:YAG laser on hypersensitive dentine. J Clin Periodontol, 2002; 29:211–215.

30.

Schiff

, Dotson

, Cohen

, De Vizio

, McCool

, Volpe

. Efficacy of a dentifrice containing potassium nitrate, soluble pyrophosphate, PVM/MA copolymer, and sodium fluoride on dentinal hypersensitivity: a twelve-week clinical study. J Clin Dent, 1994; 5 Spec No:87–92.

31.

Pillon

, Romani

, Schmidt

. Effect of a 3% potassium oxalate topical application on dentinal hypersensitivity after subgingival scaling and root planing. J Periodontol, 2004; 75:1461–1464.

32.

Ipci

, Cakar

, Kuru

, Yilmaz

. Clinical evaluation of lasers and sodium fluoride gel in the treatment of dentine hypersensitivity. Photomed Laser Surg, 2009; 27:85–91.

33.

Gillam

. Clinical trial designs for testing of products for dentine hypersensitivity––a review. J West Soc Periodontol Periodontal Abstr, 1997; 45:37–46.

34.

Saxer

, Yankell

. Impact of improved toothbrushes on dental diseases. II. Quintessence Int, 1997; 28:573–593.

35.

Duran

, Sengun

. The long-term effectiveness of five current desensitizing products on cervical dentine sensitivity. J Oral Rehabil, 2004; 31:351–356.

36.

Ide

, Wilson

, Ashley

. The reproducibility of methods of assessment for cervical dentine hypersensitivity. J Clin Periodontol, 2001; 28:16–22.

37.

Orsini

, Procaccini

, Manzoli

, Giuliodori

, Lorenzini

, Putignano

38.

Lee

, Kwon

, Kim

. Occlusion effect of dentinal tubules of the dentifrice containing nano-sized carbonate apatite. J Oral Rehabil, 2008; 35:847–853.