Table 1. Characteristics of 39 studies were involved for the final analysis .

ID	Study, Year, Country	Sample Size	Treatment Groups and Specifications	TX. Interval	Pain Stimulation	DH Measurement	Follow-up Period	Results
1	Moosavi et al (2016), Iran	66 patients	Placebo LLRL Diode laser (660 nm InGaAlP, 200 mW, 15 s) LLIL Diode laser (810 nm GaAIAs, 200 mW, 15 s)	1	_	VAS	48 hours	810-nm LLIL was significantly more effective than that of the 660-nm laser in DH reduction at 24 h after bleaching, although both laser groups experienced significantly lower pain level than the placebo after 48-h.
2	Soares et al (2016), UK	23 patients (89 teeth)	Placebo 2% neutral fluoride gel for 60 s. Nd:YAG laser (1, 10 Hz, 60 s) GaAlAs laser (40 mW; 4 J/cm2, 60 s)	1	_	VAS	1 week	All treatments provided adequate pain reduction immediately, but laser treatments resulted in significantly greater reductions in pain intensity.
3	Lee et al (2015), Korea	102 patients	Positive control: strontium chloride dentifrice (SC) 20% nano-carbonate apatite (n-CAP) Er,Cr:YSGG laser		Tactile evaporative	VAS ABS	2 weeks	In spite of DH reduction in both treatment groups, laser had a superior desensitizing effect at the initial stage, whereas the n-CAP maintained its effect for a relatively longer time.
4	Bal et al (2015), Turkey	21 patients (156 teeth)	Placebo Low-level laser (LLL) (685 nm diode laser, 25 mW, 100 s) Desensitizing paste (DP) 8% arginine-calcium carbonate Laser followed by DP (LLL+ DP) DP followed by laser (DP+ LLL)	1	Evaporative	VAS	90 days	The application of either LLL or DP was effective in decreasing DH. However, their combined use did not improve the efficacy.
5	Suri et al (2016), India	30 patients (20 teeth)	5% NaF Diode laser (980 nm GaAlAs) Group I + group II Placebo	1	Tactile evaporative	VAS	2 months	In spite of DH reduction in all groups, 5% NaF varnish with DL showed the best results (P<0.001). G3>G2>G1
6	Dantas et al (2016), Brazil	86 teeth	Fluoride varnish Diode laser (GaAlAs laser at a 4 J/cm2 dose)	4	Tactile thermal	VAS	72 hours	In spite of DH reduction in both groups at last, the short term tx with Fluoride was more effective (P<0.001).
7	Yaghini et al (2015), Iran	40 patients	Laser toothbrush Non-laser toothbrush	4	Thermal	VAS	2 months	In spite of DH reduction in both groups, laser toothbrush was more effective (P <0.05).
8	Moosavi et al (2015), Iran	31 patients (62 teeth)	Low-power red laser (630 nm, 28 mW, continuous wave, 60 s, 1.68 J) before resin composite restoration Placebo + resin composite restoration	1	Thermal	VAS	30 days	Significantly greater DH reduction (P <0.05) in the laser than the placebo group was observed suggesting LLLT a suitable approach in class V restoration.
9	Lopes et al (2015), Brazil	27 patients (55 teeth)	Gluma Infrared Low-power laser (30 mW, 10 J/cm(2), 4 points, 9 s per point, 810 nm) Infrared Low-power laser (100 mW, 90 J/cm(2), 2 points, 11 s per point, 810 nm) Group I+ group II Group I + group III	1 3 3 3 3	Evaporative tactile	VAS	2 months	All groups showed a reduction in DH (P<0.001). Gluma presented immediate effects. The combination of protocols is an interesting alternative in the treatment of cervical dentin hypersensitivity.
10	Yilmaz & Bayindir. (2014), Turkey	20 patients (60 teeth)	Er,Cr:YSGG laser at 0·25 W Er,Cr:YSGG laser at 0.5 W Placebo	1	Evaporative	VAS	Immediate	Both laser groups were effective for the tx of FH (P<0.001) according to VAS scores and tubuli occlusion in SEM; however, 0.5 W laser irradiation showed best results.
11	Ko et al (2014), South Korea	96 patients	635 nm per 6 mW laser-emitting toothbrush Placebo: 635 nm per 12·9 µW light-emitting diode (LED) toothbrush	84 (3 times a day for 4 weeks)	Evaporative	VAS	4 weeks	In spite of DH reduction in both groups (P<0.05), this decrease was significantly greater in the test group with no noticeable side effects.
12	Hashim et al (2014), Sudan	5 patients (14 teeth)	Diode laser (810 nm) with exposure duration of 30 s Diode laser (810 nm) with exposure duration of 1 min	2	Tactile	VAS	7 days	Diode laser was effective for the reduction of dentine hypersensitivity (P<0.001).
13	De Almeida Farhat et al (2014), Brazil	16 patients	LED LED-laser (300 mW/cm2)	2	_	VRS	6 months	LED-laser treatment was not able to prevent or reduce the sensitivity of teeth (P>0.05) and did not improve the efficacy of bleaching.
14	Raichur et al (2013), India	45 patients	Diode laser 0.4% stannous fluoride gel 5% potassium nitrate gel		Evaporative		6 months	All groups showed a reduction in DH (P= 0.0020). DL was not only the most effective, but also brought about improved immediate relief.
15	Lund et al (2013), Brazil	13 patients (117 teeth)	Placebo: carbomer 940 gel 2% sodium fluoride gel Low-level infrared diode laser	4 4 3	Evaporative	VAS	90 days	All groups were able to reduce DH (P<0.001), including placebo group, with no difference among them.
16	Lopes & Aranha (2013), Brazil	24 patients (33 teeth)	Gluma Nd:YAG Laser 1.5 W, 10 Hz, and 100 mJ, approximately 85 J/cm(2), 60 s Group I + group II	1	Tactile Evaporative Thermal	VAS	6 months	All protocols were effective in reducing DH after 6 months (P<0.001); however, the association of Nd:YAG and Gluma Desensitizer is an effective treatment strategy that has immediate and long-lasting effects.
17	Flecha et al (2013), Brazil	62 patients (434 teeth)	(GaAlAs) infrared diode laser (795 nm,120 mW, 2.88 J/cm2, 8 s) Cyanoacrylate	3	Tactile	NRS	180 days	Cyanoacrylate is as effective as low-intensity laser in reducing DH. In addition, it is a more accessible and low-cost procedure and can be safely used in the treatment of DH.
18	Femiano et al (2013), Italy	24 patients (262 teeth)	NaF Diode laser (808 nm-35 W) Group II + Group III Gluma desensitizer	3	Thermal	VAS	6 months	In spite of DH improvement in all groups, diode laser in association with NaF effectively reduced DH with a more immediate relief and longer lasting (P<0.001).
19	Mogharehabed et al (2012), Iran	9 patients (60 teeth)	Placebo 5% sodium fluoride varnish Nd: YAG laser (1 W, 20 Hz, 120 s) Group II + group III	1	Evaporative Thermal	VAS	2 weeks	The use of 5% sodium fluoride varnish and laser for treatment of DH is accompanied by a placebo effect. The association of NaF and laser showed the best improvements.
20	Ehlers et al (2012), Germany	22 patients	Glutaraldehyde-based desensitizing system Er:YAG laser		Evaporative	VAS	6 months	Both laser and glutaraldehyde groups showed an effective and equal reduction of cervical dentin hypersensitivity (P<0.001).
21	de Almeida et al(2012), Brazil	40 patients	Home bleaching with 10% carbamide peroxide, 4 h/d 35% hydrogen peroxide, 10 minutes Quartz−tungsten−halogen light irradiation, 10 min LED/laser light irradiation, 10 min	3 weeks 3 sessions 3 sessions 3 sessions	_	Analog scale (0-10)	180 days	Although all groups led to tooth sensitivity, light irradiated techniques showed more sensitivity in terms of both duration and intensity.
22	Aranha & Eduardo Cde. (2012), Brazil	28 patients	Placebo Er:YAG laser (2 Hz/32.4 mJ/5.9 J/cm(2)) Er,Cr:YSGG laser treatment (0.25 W/4.4 J/cm(2)) Er,Cr:YSGG laser treatment (0.50 W/ 8.9 J/cm(2))	1	Evaporative Tactile	VAS	1 month	With the evaporative stimulus, group II was associated with the lowest level of pain. With the mechanical stimulus, group IV showed the most pronounced decrease in pain immediately after treatment; however, after 4 weeks, pain levels had increased.
23	Yilmaz et al (2011), Turkey	51 patient (174 teeth)	Diode laser (GaAlAs laser at 8.5 J/cm2, 60 s) Er,Cr:YSGG laser (0.25 W, 20 Hz, 0% water and 10% air, 30 s) No treatment	1	Evaporative	VAS	3 months	Compared to the control group, both Er,Cr:YSGG and GaAlAs lasers were effective in DH reduction immediately after the treatment (P <0.05) with no significant difference (P < 0.05).
24	Yilmaz et al (2011), Turkey	48 patients (244 teeth)	GaAlAs laser (810 nm, 500 mW, 60 s, 8.5 J/cm(2)) Placebo laser NaF varnish Placebo NaF varnish	1	Evaporative	VAS	6 months	GaAlAs laser and NaF varnish treatments resulted in a significant reduction in the VAS scores immediately after treatments that were maintained throughout the study when compared to the baseline and placebo treatments.
25	Yilmaz et al (2011), Turkey	42 patients (146 teeth)	Er,Cr:YSGG laser (0.25W, 20 kHz, 30 s) Placebo	1	Evaporative	VAS + plaque index	3 months	Er,Cr:YSGG laser had a significantly higher desensitizing effect compared with the placebo immediately after treatment (P <0.05).
26	Orhan et al (2011), Turkey	16 patients 64 teeth	Glutaraldehyde containing dentin desensitizer Low-level Diode laser (25-mW, 655 nm, 4 J/cm(2), 160 s) Distilled water Placebo laser	1 6 1 6	Thermal evaporative	VAS	7 days	Pain scores of placebo groups were significantly higher than those of the desensitizer's and diode lasers (P < 0.05). Significant DH reduction was observed in 7 days with the use of the desensitizer and low-level laser therapy with no statistically significant difference (P > 0.05).
27	Kossatz et al (2011), Brazil	30 patients	Light-activated (LA) (LEDs with wavelength of 470 nm and three infrared Laser diodes with 830 nm and light intensity of 200 mW/cm, 1 min for 3 times) Non-activated	2	_	0-4 scale	48 hours	The intensity of sensitivity was similar for both groups immediately after bleaching but significantly higher for the LA group 24 hours after each bleaching session (P=0.001).
28	Pesevska et al (2010), Macedonia	(30 teeth)	Low-level diode laser (630–670 nm; 100 mW/cm2, 20 s) Topical Fluoride Varnish (Fluor Protector)	3	_	VRS	5 days	DH reduction by Laser was superior to Fluoride Varnish. Complete resolution of pain was achieved in 26.67% of group I, compared to 0 % in group II after the second visit, and 86.67% in group I compared to 26.67% in group II after the third visit.
29	Gurgan et al (2010), Turkey	40 patients	Bleaching twice without light activation Bleaching with a diode laser (810 nm, 10 W) activation for 3 times Bleaching treatment with a plasma arc lamp (400-490 nm, 2800 mV/cm(2)) for 3 times Bleaching twice with a light emitting diode (LED) lamp (400–500 nm)	1	_	VAS	Immediate	Group II showed significantly lower tooth and gingival sensitivity scores than did the other groups (P<0.001).
30	Genovesi et al (2010), Italy	15 patients	Er:YAG (2940 nm) & CO2 lasers (10600 nm) + fluoride gel Placebo Er:YAG & CO2 lasers Fluoride gel + Placebo	1	Evaporative	VAS	Immediate	There were statistically significant differences between groups I and II. There were no statistically significant differences between groups III and IV. Er:Yag and CO2 lasers together with fluoride gel are useful in the treatment of dentine hypersensitivity.
31	Dilsiz et al (2010), turkey	13 patients (52 teeth)	GaAIAs Diode laser (100mw, 25 s, 808 nm) + desensitizer toothpaste Desensitizer toothpaste	3	Evaporative	VAS	60 days	GaAIAs Diode laser plus desensitizer toothpaste group showed a higher degree of desensitization in teeth than did the control group (P<0.001).
32	Dilsiz et al (2010), turkey	24 patients (96 teeth)	Er:YAG laser (2,940 nm, 60 mJ/pulse, 2 Hz, 20 s) Nd:YAG laser (1,064 nm, 100 mJ/pulse, 15 Hz, 100 s) Diode laser (808 nm, 100 mW, 20 s) Placebo	3	Evaporative	VAS	60 days	Significant reduction of DH occurred at all times for all groups. Nd:YAG laser was proved more effective in treatment of DH than the Er:YAG and diode lasers especially in 3-months results (P<0.001).
33	Sicilia et al (2009), Spain	45 patients	Diode laser (810 nm) + placebo gel Placebo laser + 10% potassium nitrate bio adhesive gel Placebo laser + placebo gel	1	Evaporative	VRS	60 days	The DL and NK10% gel were proven effective in the treatment of DH. DL has shown efficacy in rapid and long-lasting DH reduction compared with placebo laser in periodontal patients.
34	Kara & Orbak. (2009), Turkey	20 patients	Nd:YAG laser (100 mJ, 20 Hz) Fluoride varnish	1	Evaporative	VAS	4 weeks	Laser treatment resulted in significant improvements of discomfort immediately after treatment and after 1 week (P<0.001). However, the VAS scores at the 4-week examination were significantly lower in the fluoride group compared with those in the laser group (P<0.05).
35	Ipci et al (2009), Turkey	50 patients (420 teeth)	2% NaF CO(2) laser (1 W, 10 s) Er:YAG laser (30 Hz, 60 mJ,10 s) Group I + group II Group I + group III	1	Thermal Evaporative	VRS	6 months	VRS scores were significantly lower for the other four treatments than for NaF gel alone (P +/- 0.001). No superiority was found for desensitization among the CO(2), Er:YAG, CO(2) + NaF, and Er:YAG + NaF groups.
36	Aranha et al (2009), Brazil	(101 teeth)	Glumma Desensitizer Seal & Protect (SP) Oxa-gel (OG) Fluoride (F) Low intensity laser- LILT (660 nm/3.8 J/cm2/15 mW)	1 1 1 1 3	Thermal Evaporative	VAS	6 months	OG and LILT showed significantly higher sensitivity immediately compared to Gluma Desensitizer and SP (P=0.0165). However, after 6 months, all therapies showed lower sensitivity compared with baseline presenting no statistically significant differences.
37	Tengrungsun & Sangkla. (2008), Thailand	70 patients (140 teeth)	GaAlAs laser (30 mW, 1 min) Dentin bonding agent	1	Tactile, thermal	(0-4 degree scale) (Uchida criteria)	30 days	A significant DH reduction after both treatments at all times was observed (P< 0.05). DH reduction by dentin bonding agent was significantly superior to GaAlAs laser (P< 0.05).
38	Marson et al (2008), Brazil	40 patients	35% Hydrogen Peroxide (HP) 35% HP + Halogen Curing Light XL 3000 (3M/ESPE) 35% HP + Demetron LED (Kerr) 35% HP + LED/LASER (Bio-art)	2	_	VRS	6 months	The recorded tooth sensitivity was similar in the number of patients and intensity. Tooth sensitivity occurred immediately following bleaching, but a higher degree of sensitivity was recorded after the second bleaching session, independent of the group evaluated.
39	Birang et al (2007), Iran	9 patients (63 teeth)	Nd:YAG laser (1 W, 15 Hz, 60 s, 2 times) Er:YAG laser (100 mJ, 3 Hz, 60 s, 2 times) Placebo	1	Tactile	VAS	6 months	Both lasers, in spite of a placebo effect at short time, were so effective to decrease DH. Nd:YAG laser was more effective than Er:YAG laser in reduction of patients’ pain (P<0.0005).