The effect of low level laser therapy on pain during dental tooth-cavity preparation in children.
Abstract: AIM: To evaluate the effect of low level laser therapy on pain during cavity preparation with laser in paediatric dental patients. STUDY DESIGN AND METHODS: The study was carried out on 10 children aged 6 to 9 years old for a total of 20 primary molar teeth. For laser preparation an Er: YAG laser was used. Half of the preparations were treated by low level laser therapy (LLLT) before laser preparation and the remaining half without LLLT (non-LLLT) before laser preparation. All cavities were prepared by ER:YAG laser, restored with light-cured composite resin following the application of acid etching and bonding agent. Children were instructed to rate their pain on the visual analogue scale (VAS) from 0 to 5 points. Statistical analyses were performed using Mann Whitney U test. RESULTS: VAS Median (min-max) scores were 1(0-2) for LLLT and 3(1-4) for the non-LLT treated children. Between LLLT and non-LLLT groups results were statistically significant (p<0.01). CONCLUSIONS: The use of LLLT before cavity preparation with laser decreased pain in paediatric dental patients.

Key words: Low level laser therapy, pain, children.
Article Type: Clinical report
Subject: Lasers in surgery (Health aspects)
Lasers in medicine (Usage)
Lasers in medicine (Health aspects)
Tooth diseases (Care and treatment)
Children (Diseases)
Children (Care and treatment)
Authors: Tanboga, I.
Eren, F.
Altinok, B.
Peker, S.
Ertugral, F.
Pub Date: 04/01/2011
Publication: Name: European Archives of Paediatric Dentistry Publisher: European Academy of Paediatric Dentistry Audience: Academic Format: Magazine/Journal Subject: Health Copyright: COPYRIGHT 2011 European Academy of Paediatric Dentistry ISSN: 1818-6300
Issue: Date: April, 2011 Source Volume: 12 Source Issue: 2
Product: Product Code: 3832848 Lasers for Medicine NAICS Code: 334510 Electromedical and Electrotherapeutic Apparatus Manufacturing SIC Code: 3845 Electromedical equipment
Geographic: Geographic Scope: Turkey Geographic Code: 7TURK Turkey
Accession Number: 277106749
Full Text: Introduction

Standard treatment for caries removal and cavity preparation for restorations using mechanical means is often accompanied by pain and fear for children, although the pain may be reduced by local anaesthesia. Fear of the needle, noise and vibration of mechanical preparation remains a cause of discomfort [Keller et al., 1998]. Any new technology that decreases dental pain and fear is of great interest to both dentists and patients [Genovese and Olivi, 2008]. The use of lasers in dentistry is increasing and their use in paediatric dentistry have been recently reviewed [Martens, 2011; Olivi and Genovese, 2011].

Lasers are potential alternatives for caries removal and cavity preparation [Matsumoto et al., 2007] and have also been used in children [Kato et al., 2003]. Several types of laser have been investigated to find an alternative to conventional high-speed handpiece preparation. Erbium lasers (Er:YAG and Er,Cr:YSGG) have shown potential in the removal of caries and tooth structures with minimal thermal effects on the adjacent hard and soft tissues [Keller and Hibst, 1989 and 1997]. The Er:YAG laser has a wavelength of 2.94 [micro]m, which makes it more or less completely absorbed by water molecules in enamel and dentine. It has been also reported that the Er:YAG laser produces minimal vibration and noise during cavity preparation, and the need for local analgesia is none or minimal [Keller et al., 1998].

Laser therapy in paediatric dentistry is a good choice for its known advantages especially for the safety of its use and its gentle approach with patients [Olivi and Genovese, 2011].

Low level laser therapy (LLLT) is also known as 'soft laser therapy' and bio-stimulation. The use of LLLT in health care has been documented in the literature for more than three decades. The typical power output for a low level laser device used for his therapy is of the order of 10-50 mW. The wavelengths used for LLLT have poor absorption in water and thus penetrate soft and hard tissues from 3-15mm [Moritz et al., 2006].

Studies have demonstrated that LLLT is effective for some specific applications in dentistry [Moritz et al., 2006]. LLLT is well-established clinically in dentistry because of its anti-inflammatory and regenerative effects as well as its conditioning effect on tooth enamel [Turhani et al., 2006]. Positive reports of the benefit of LLLT used in the dental surgery to treat disorders including TMJ pain, trigeminal neuralgia and muscular pain have been presented [Pinheiro et al., 1998]. LLLT also reduces cervical dentinal hypersensitivity and periodontal pain during orthodontic tooth movement [Walsh, 1997].

An additional area of interest in this field is the use of LLLT to achieve an analgesic effect in the dental pulp prior to restorative procedures. First noted with the Nd:YAG laser in the early 1990's, the clinical use of 'pre-emptive laser analgesia' is becoming more widespread now as a clinical technique with the Er:YAG and Er,Cr:YSGG laser [Moritz et al., 2006].

When operated at pulse rates between 15 and 20 Hz, the erbium laser energy penetrates into the tooth, and is directed along hydroxyapatite crystals (which function has waveguides) towards the dental pulp. Here, the pulses of energy coincide with the natural bio-resonance frequency of Type C and other nevre fibres in the dental pulp. The action of this type of LLLT is to cause a disruption in the action of the Na-K pump in the cell membrane, resulting in a loss of impulse conduction, and thus an analgesic effect [Moritz et al., 2006]. The duration of this effect is ~15 min. Direct examination of teeth lased to achieve this analgesic effect has not shown any evidence of adverse pulpal change at the histological level over the short or long term [Moritz et al., 2006].

The aim of this study was to evaluate the analgesic effect of low level laser therapy on pain during primary molar cavity preparation with Er:YAG laser in paediatric dental patients.

Materials and methods

All guidelines for treatment and the responsibilities of the participants were set out in the protocol. Patients were selected at random and the children were informed of the details of laser treatment including precautions and possible side-effects such as popping sounds and the smell associated with ablation. Each patient/parent was requested to give an informed consent to participate in the study. Both the consent form and the study protocol were approved by the School of Dentistry Ethics Committee of Marmara University.

The study population involved 20 primary molar teeth of 10 children with ages ranging from 6 to 9 years. Clinical parameters such as depth and location of the cavities were carefully balanced before treatment. For cavity preparation and LLLT application an Er:YAG laser (KaVo KEY Laser, KaVo Co. Germany ) with a wavelength of 2940 nm, a pulse duration of 250 ms and additional water spray was used. Laser parameters for cavity preparation used in the study were predetermined by the manufacturer's instructions which were 250 mJ energy and frequency of 4 Hz. Protective eye glasses were used during treatment and a Carl-Zeiss microscope with X10 plus zoom was used.

Right side of the mouth cavities were treated with laser whilst left sided cavities had LLLT applied to the teeth before being treated with laser. To achieve laser analgaesia, the laser was positioned at a distance of 2mm from the tooth surface on the gingival margin and slowly moved for 2min duration using 60 mJ energy and 20 Hz frequency power (low energy, high frequency). After laser preparation, all cavities were filled with compomer according to the manufacturer's instructions without acid etching. Immediately after treatment, children were instructed to rate their pain on the visual analogue scale (VAS) from 0 to 5 points and the scores were noted (Fig. 1). For statistical analysis NCSS 2007 & PASS 2008 Statistical Software (Utah, USA) programme was used and Mann Whitney U tests performed. A p value below 0.05 was considered significant.

[FIGURE 1 OMITTED]

Results

The results of the Mann Whitney U tests revealed a statistically significant difference between LLLT and non-LLLT groups (p<0.01) (Table 1).

Both LLLT and non-LLLT applied VAS scores were higher in males than females (Fig. 2).

[FIGURE 2 OMITTED]

Discussion

It has been reported in some studies that Er:YAG laser can provide clinical procedures with minimal patient discomfort and without any side-effects. Cavity preparation with the Er:YAG laser would seem to be an option for fearful children, as it produces less pain and has acceptable efficiency compared to the conventional mechanical preparation [Liu et al., 2006]. High speed drilling causes greater tooth vibration and has a frequency spectrum close to the peak of hearing sensitivity [Takamori et al., 2003]. By contrast, the Er:YAG laser has been reported to produce a minimum level of vibration and noise during cavity preparation [Keller et al., 1989]. The explanation for the lack of pain in laser treatment could be due to the lower increase in intra-pulpal temperature during laser preparation in comparison to the conventional bur method [Glockner et al., 1998].

In this study, the analgesic effect of LLLT on pain during primary molar cavity preparation with Er:YAG laser in children was investigated. Studies have shown pain relief by LLLT after surgical endodontics [Kreisler, 2004] and in patients with temporomandibular joint pain, trigeminal neuralgia, myalgia, aphthaes and hypersensitivity [Kulekcioglu et al., 2003, Pinheiro et al., 1997, Woodruff et al., 2004]. However, there are no studies about the analgesic effect of LLLT during cavity preparation in children.

Pain assessment by the patient using the Visual Analogue Scale (VAS) from 0 to 5 points showed that the LLLT group median score was 1 and for the non-LLLT group the median score was 3, and this difference was statistically significant (p<0.01). The lack of pain indicates that LLLT application prior to cavity preparation with Er:YAG laser is a preferable treatment option for caries treatment in children.

All common commercially available LLLT systems use semiconductor diode lasers. These are generally variants of either Gallium:Aluminium:Arsenide (GaAlAs) which emit in the near infrared spectrum (wavelength 700-940 nm), or Indium:Gall ium:Arsenide:Phosphorus (InGaAsP) devices which emit in the red portion of the visible spectrum range (wavelength 600-680 nm) [Walsh, 1997; Martens, 2011]. The use of LLLT to achieve an analgesic effect in the dental pulp prior to restorative procedures was first noted with the Nd:YAG laser in the early 1990's and the clinical use of 'pre-emptive laser analgesia' is becoming more widespread now as a clinical technique with the Er:YAG and Er,Cr:YSGG laser [Moritz et al., 2006]. In this study Er:YAG laser was used to achieve an analgesic effect.

To achieve laser analgaesia, the laser was positioned at a distance of 2mm from the tooth surface on the gingival margin and slowly moved for 2 min duration using 60 mJ energy and 20 Hz frequency power (low energy, high frequency). The LLLT effect of laser 'analgesia' does not result in complete 'anesthesia' of the lased tooth [Moritz et al., 2006].

In this study both general VAS scores and LLLT applied VAS scores were higher in males than females. This may be explained by the finding that females appear to recover subjective pain perception more quickly than males [Turhani et al. 2006].

Conclusion

LLLT application prior to cavity preparation with laser, makes cavity preparation more comfortable and effective and has special advantages in the treatment of children. Further clinical studies should be conducted to evaluate the analgesic effect of LLLT in randomised controlled trials with larger numbers of children.

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I. Tanboga, F. Eren, B. Altinok, S. Peker, F. Ertugral

Marmara University Dentistry School, Department of Pediatric Dentistry, Istanbul, Turkey

Postal address: Or L Tanboga, Marmara Universitesi Dis Hekimligi Fak. Pedod onti AD, Buyukciftliksok. No:6 Kat:4, Nicantaci, Sisli/istanbul 34365, Turkey.

Email: itanboga@marmara.edu.tr
Table 1. Pain assessment of LLLT and non-LLLT groups.

Group                     Median (Min-Max)

LLLT                      1 (0-2)

Non-LLLT                  3 (1-4)

p                         Z:-2,878; p:0,004 **

Z: Mann Whitney U Test

** p<0.01
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