Laser restorative dentistry in children and adolescents.
Abstract: BACKGROUND: The idea of substituting a drill with a laser light, has led to its introduction in dentistry. Besides being more accepted to patients, in paediatric dentistry the laser has demonstrated safety compared with rotating instruments. REVIEW: A review of the past 20 years of the dental literature concerning laser use in dentistry, including paediatric dentistry was completed. The findings of that review are presented. TECHNIQUES: The various types of lasers and their uses for caries detection, tooth sealing and caries removal are described. RESULTS: Laser caries detection demonstrated a good reproducibility, reliability and predictability to monitor the caries process over time. Erbium lasers have been found to be efficient for caries removal, tooth cleaning and decontamination. CONCLUSION: The laser erbium technology represents a safe device to effectively and selectively remove carious tissues from decayed teeth. For children, all the recognized advantages of this technique play a decisive role in the successful day-to-day treatment of dental caries.

Key words: Laser, erbium, laser fluorescence, sealant, cavity preparation.
Article Type: Report
Subject: Dental caries (Care and treatment)
Lasers in dentistry (Analysis)
Children (Health aspects)
Authors: Olivi, G.
Genovese, M.D.
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
Geographic: Geographic Scope: Italy Geographic Code: 4EUIT Italy
Accession Number: 277106745
Full Text: Background

The idea of substituting a drill with a laser light which has less adverse effects on patients, without vibration, noise and pain, has led to its introduction in dentistry. Lasers are extremely safe compared with rotating instruments, especially in paediatric dentistry, when used in the treatment of very young children, due to the lower risk of accidental damage to soft tissues and pulp tissue. Lasers bring new possibilities for safe and minimal removal of carious tissue with better acceptance compared with traditional techniques [Wigdor, 1997; Keller et al., 1998; Parkins, 2000; Matsumoto et al., 2002; Takamori et al., 2003; Boj et al., 2005; Liu et al., 2006; Genovese and Olivi, 2008]. It is important to observe the rules of safety, such as the use of specific protective glasses according to the wavelength used, as well as choosing the appropriate size glasses for the face of the child.

Nowadays, as reported by Martens [2003, 2011] and emphasised by Gutknecht et al. [2005], 'children are the first in line to receive dental laser treatment' and based on micro-dentistry's comment 'filling without

drilling'. Thus, the philosophy of laser-supported dental diagnosis and treatment is becoming a gold-standard to treat children successfully, according to the latest extensive publications in paediatric dentistry [Olivi et al., 2010; Martens 2011].

Laser usage. Lasers are commonly used on hard tissues in paediatric dentistry in the following fields:

* Diagnosis,

* Preventive dentistry,

* Restorative dentistry,

* Endodontics.

For the purpose of this paper, the authors consider only the procedures limited to restorative dentistry, and also include some mention of caries diagnosis by laser and laser-assisted techniques in caries prevention.

Lasers in dentistry

Basic physics in the use of lasers. Laser-tissue interaction depends on the effects of different wavelengths on the different hard tissue treated. The interaction is primarily determined by the wavelength's affinity for specific chromophores of different tissues [Parker et al., 2007]. The main chromophores of dental tissues are the hydroxyapatite and the water content within the hydroxyapatite crystals of enamel and dentine that highly absorb medium infrared wavelengths (2,780nm and 2,940nm), (Fig. 1).

[FIGURE 1 OMITTED]

For the purpose of restorative paediatric dentistry, the application of laser energy on dental tissues takes into account only the water content of healthy, demineralised and carious dental tissues (enamel and dentine), as the interaction with hydroxyapatite has only a minor and negligible role. Consequently it is important to consider the different water content of healthy enamel and dentine, the different composition of primary and permanent teeth, both in youths and adults, when choosing the parameters of laser use. Moreover carious tissues are demineralised and richer in water in comparison with healthy and/or non-vital teeth. This concept is important to understand because more energy will be needed for enamel and less energy for carious tissue, depending on different absorption of different water content in the tooth (different ablation thresholds of dental tissues) (Fig. 2).

[FIGURE 2 OMITTED]

It is also important to emphasise the ablation of the organic component of dentine (collagen) that affects the adhesion of bonding filling materials. The physical properties involved in the ablation of hard tissues by the erbium family of lasers is based on the transfer of laser energy to the tissues that causes different phenomena that rapidly occur, which are thermal and thermo-mechanical phenomena. The first mechanism of action of the erbium family lasers on hard tissues is a thermal effect on the water molecules within the tissues. Once the energy is absorbed by the water, it is converted into heat, causing superheating, and vapourisation. The increased steam pressure produces micro-explosive expansion within the hard tissue itself, causing the tissue to blast away [Hadley et al., 2000; Hirota and Furumoto, 2003] (Fig. 3).

[FIGURE 3 OMITTED]

In addition, the use of an external water spray has a decisive role effectively and efficiently influencing the ablation rate, as well as for the cleaning and debriding and cooling effects on the dental tissues. Even if an unambiguous precise mechanism has not yet been demonstrated. Additional research is necessary to clearly explain the mechanism of the laser hard tissue interaction.

The two different wavelengths work in a similar way, even if with slightly lower absorption (38%) and consequently higher penetration depth into hard dental tissues (up to >15-21 Mm for dentine and enamel) results for Er,Cr:YSGG laser (2780nm) compared with Erbium:YAG (up to > 5-7 Mm for dentine and enamel) [Prhavec and Diaci, 2008] (Fig. 4).

A common consensus about the values of absorption coefficient and energy penetration depth has not been yet reached. The ablation threshold is currently known to be about 12-20 J/[cm.sup.2] for enamel and 8-14 J/[cm.sup.2] for dentine for Er:YAG and Er,Cr:YSGG respectively [Harris et al., 2002]. Other authors found slightly different values, respectively of 9-11 J/[cm.sup.2] for Er:YAG and of 10-14 J/[cm.sup.2] for Er,Cr:YSGG [Apel et al., 2002].

[FIGURE 4 OMITTED]

Lasers for caries detection and diagnosis. Laser fluorescence has been proposed for the diagnosis of caries in both primary and permanent teeth (655nm). This is the application investigated most frequently and most in depth of all the laser applications in paediatric dentistry. Of the papers indexed under the subject heading 'Laser Paediatric Dentistry' in Pub-Med, more than 40 studied the use of this device for carious detection. This non-ablative laser (LF) emits a laser fluorescence light, visible in the red spectrum at 655nm, which has proved to be useful to complete conventional methods for occlusal caries detection (Fig. 5).

Several studies compared different caries detection methods: visual inspection alone, visual inspection with magnification, bitewing radiographs and laser fluorescence. Lussi et al. [2003] affirmed that LF could be used as an additional tool in the detection of occlusal caries in primary teeth and its good reproducibility should enable the laser device to monitor the caries process over time. Other authors [Burin et al., 2005; Mendes et al., 2006; Barberia et al., 2008] considered the fluorescence device better than bitewing radiographs for occlusal caries detection.

[FIGURE 5 OMITTED]

Some studies investigated the impact of the operator on the results and concluded that the reliability, predictability and the reproducibility of the results did not depend on the operator [Bengtson et al., 2005]. Other studies reported that LF methods for occlusal caries are more efficient in primary than in permanent teeth, but concluded that laser fluorescence was not able either to detect in vitro remineralisation of natural incipient caries lesions of primary teeth nor to monitor the quantification of mineral loss in caries lesions development in primary teeth [Mendes et al., 2003]. A recent study [Braga et al., 2008] reported that a LF device performs better at the dentine than at the enamel threshold. They therefore concluded that this method does not perform well in detecting initial enamel caries lesions, confirming the previous studies of the same group that demonstrated a good performance of LF in predicting the extension of the caries lesions. LF presents a better correlation with the lesion depth than with mineral loss in smooth surface caries lesions and the quantification of mineral loss was undesirable.

Chu et al. [2010] studied the validity of three different methods for fissure caries detection in 144 second molars with intact occlusal surfaces in 41 young adults, including visual examination, bitewing radiographs, and the use of a DIAGNOdent. The combined approach of this device and visual examination was found to be superior. Huth et al. [2008] concluded that the DIAGNOdent's discrimination performance for various carious depths in permanent molars was moderate to very good and it may be recommended as an adjunct instrument in the diagnosis of occlusal caries.

Khalife et al. [2009] performed an in vivo study that assessed the correlation between the depth and volume of caries as it was removed by handpieces with DIAGNOdent readings and they also concluded that this device should be used as an adjunct in the diagnosis and treatment planning process.

Iwami et al. [2004] studied the relationship between bacterial infection of the dentine and the evaluation of a laser fluorescence device, DIAGNOdent. This in vitro study investigated the polymerase chain reaction (PCR) to a fluorescence device in the carious dentine. The values of the DIAGNOdent increased as the rates of detection of the bacteria increased reinforcing the conclusion of the relationship between the DIAGNOdent fluorescence values of dentine caries and the rates of bacterial detection. Virajsilp et al. [2005] confirmed the reliability and the diagnostic validity (sum of sensitivity and specificity) of LF as very high and also reported it as higher than that of bitewing radiography for proximal caries detection in primary teeth. Also the caries detection of approximal tooth surfaces might be influenced by the condition of the adjacent tooth surface.

Novaes, et al. [2009] in a recent study, compared the performance of various methods of interproximal caries detection in primary molars. The examiners evaluated 621 approximal surfaces of 50 children aged 5-12 years. They used visual inspection, radiographic examination, and the LF pen device. Both the LF pen and radiographic examination exhibited similar performance in the detection of the presence of cavitation on interproximal surfaces of primary molars. In a similar study by Costa et al. [2008] it was concluded that the laser device had an acceptable performance and that this device should be used as an adjunct method to visual inspection in order to avoid false positive results.

Several studies investigated particular situations that could condition the results of the readings: the presence of brown or dark spots on fissures tended to overscore discoloured surfaces [Francescut and Lussi, 2003] while the presence of plaque worsened the performance of the laser fluorescence method [Mendes et al, 2004]. Also, the presence of toothpaste residual after teeth cleansing can modify the detection, registering false readings [Lussi and Reich, 2005]. Caries detection under dental sealants was unreliable and not recommended due to a high likelihood of inaccurate readings caused by intrinsic fluorescence of sealant material [Manton and Messer, 2007].

Lasers in preventive dentistry. Laser irradiation has been thought in preventive dentistry to provide enamel surface resistance to caries: several laser wavelengths, including 2940nm, 2780nm, 9300nm, 9600nm and 10600nm, have been proposed for superficial ultra-structural modifications and acid-resistance increase, tested by cross-sectional micro-hardness and enamel solubility analysis since 1980s [Featherstone et al., 1997; Apel et al., 2004]. Today, several studies on these applications have been done which present more or less uniform results while on the other hand clinical studies and evidences are extremely limited. Sub-ablative C[O.sub.2] and erbium family laser irradiation's ability to increase the acid resistance of permanent young healthy teeth could be an effective method of caries prevention [Featherestone et al., 1998; Apel et al., 2004]. Long-term clinical studies are necessary to validate this application before an extensive use of this procedure.

Laser-assisted pits and fissures conditioning prior to sealant application (LAS). The use of laser pre-treatment of pits and fissures, before application of fissure sealant (FS) on the occlusal surface of young teeth was investigated by several in vitro studies, performed to evaluate the bond strength and the microleakage of pit and FS, comparing invasive and non-invasive techniques to laser technique, with or without acid etching. Most of these studies reported no significant difference between the two types of enamel preparation when etching was performed [Matson et al., 2002; Borsatto et al., 2004; Moshonov et al., 2005; Francescut et al., 2006; Youssef et al., 2006; Borsatto et al., 2007; Lupi-Pegurier et al., 2007; Lepri et al., 2008 Sungurtekin et al., 2009]. These studies concluded that laser irradiation did not eliminate the need for acid etching enamel prior to the placement of a pit and FS, which remains a critical step in the bonding procedures. Nevertheless laser technology may be considered to be an additional tool in the FS application procedure (LAS) and also in preventive resin restoration (LPRR), for the conditioning (macro-roughening), cleansing and disinfecting action on the fissure and pits enamel surface. This is especially so when the laser is used in the treatment of initial lesions in combination with laser diagnosis (LF) of pits and fissures, allowing a truly minimally invasive preparation of decayed tissues (LPRR) [Olivi et al., 2011]. Used in this way, the erbium lazer can perform a fissurotomy (invasive technique at 150-200mJ, with 400-600micron tip) only in the areas showing a positive result with laser diagnosis (LF score value from 11-20mJ to 21-30mJ), or a macro-roughening (non-invasive technique at 65-75mJ) when the LF resulted in healthy enamel surface (LF score value of 0-10), with the advantage of leaving the surfaces decontaminated and clean. Care must be taken with the energy applied (65-75mJ, with 400-600micron tip) to the healthy enamel fissures, so as not to over prepare the pit and fissure enamel surfaces. By selecting a different energy for different healthy or carious areas, we are able to work selectively, ablating the carious tissue or conditioning the healthy tissue, performing a truly minimally invasive technique. (Fig. 6a-f and Table 1).

[FIGURE 6a OMITTED]

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[FIGURE 6f OMITTED]

Lasers in restorative dentistry. The erbium family lasers can be used in restorative dentistry for:

* minimally invasive preparation of pits and fissures, according to laser detection values (LPRR) (Fig. 7a-d),

* minimally invasive preparation of hypoplastic lesions (Fig. 8),

* gingivectomy (when needed for the restoration) (Fig. 9),

* cavity preparation: from class I to class V,

* treatment of deep dentinal caries (indirect pulp capping),

* laser-assisted pulp capping (LAPC).

[FIGURE 7a OMITTED]

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Laser preparation of carious cavities compared with traditional techniques presents various advantages and some disadvantages. The advantages can be operative or clinical and include (see Table 2), these are:

* Better patient acceptance (no contact--no vibration--no noise--no or less use of anesthesia); (Fig. 10a,b),

* Better acceptance by parents, who see the high technology and the professional using it as a better therapeutic option for their children,

* Minimally invasive cavity preparation due to the selective absorption of laser light by carious tissue,

* Preparation of cavities with macro-roughened surface that increases the surface for the adhesion of composite material,

* Very clean cavities and free of smear layer,

* Cavity preparation that is highly decontaminated,

* Minimal thermal increase in the pulp chamber, less than with traditional techniques, with the possibility of less post-treatment sensitivity,

* Possibility of sealing the dentine tubules (when needed),

* Possibility of treating soft and hard tissue at the same time and with the same instrument: for example, gingivectomy to access the margins of subgingival cavities or a pulpotomy and the coagulation of the exposed pulp (Fig. 11).

[FIGURE 10 OMITTED]

[FIGURE 11 OMITTED]

Some of the disadvantages of laser therapy compared with traditional techniques are:

* Longer learning curve,

* Equipment costs, time and cost of training,

* Cavity margins that are less finished compared to traditional mechanical techniques,

* Bond strength results lower or equal to traditional techniques,

* Microleakage results lower or equal to traditional techniques.

A careful evaluation of the advantages/disadvantages as outlined point by point above has brought about some modifications in laser preparation techniques, since its introduction in the '90s, improving laser cavity preparation and Minimising the disadvantages.

Laser advantages in paediatric dentistry

Lasers and analgesia. A correct psychological approach to the patient also contributes considerably to the success of laser therapy, which is often seen by patients and their families as something magical. The actual absence of contact and vibration and therefore its lower impact, is suggested by some authors as the potential factor in provoking pain and discomfort during tooth preparation [Takamori et al., 2003; Tanboga et al., 2011].The laser, if used correctly, generates an analgesic effect in the irradiated area caused by a temporary loss of conductance of the nervous impulse due to the disruption of the [Na.sup.+]/[K.sup.+] pump of the cell membrane of the nervous fibre. This results in a loss of impulse conduction, and therefore an analgesic effect occurs [Moritz, 2006]. There is evidence that laser irradiation causes a membrane hyperpolarisation and in order to initiate a potential action, a stimulus of greater intensity is necessary [Benedicenti, 1979, 2005] also raising the threshold of pain of the patient [Genovese and Olivi, 2008]. In addition laser irradiation may selectively target fibres conducting at slow velocities, especially afferent axons from nocioceptors. It has been estimated that the duration of the analgesic effect of the pulp is approximately 15 minutes and no adverse pulpal changes have been seen histologically over short or long periods [Moritz, 2006]. All the wavelengths at a sub-ablation power, especially those of the near infrared laser (803-980nm), can produce analgesia at the irradiated site in a defocused mode with a grating (scanner) technique and raising energy.

For the optimal analgesic effect in restorative dentistry, it has been to initially hold the laser tip 6-10 mm from the tooth and running slowly around the neck of the tooth for 40-60 sec at 25-50mJ, 10-15Hz, with a low air/water ratio of the integrated spray. Gradually increasing the energy level to 75-80mJ after the first 60 seconds, always in a defocused mode helps. Then, increasing the pulse repetition rate up to 20-25pps, the energy and the air/water up to the minimum effective threshold, the laser beam is focused and the ablation began [Olivi et al., 2011]. It is better to spend more time in inducing analgesia before starting the ablation, avoiding the stimulation of pain, than to interrupt the therapy if an incorrect initial procedure has been performed Fig. 12a-d.

[FIGURES 12a-b OMITTED]

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[FIGURE 12d OMITTED]

Laser cavity design: micro-macro morphological aspects. The laser-prepared cavity does not follow the rules of cavity design by Black, but follows instead the rules of minimally invasive dentistry, as the selectivity of action on the carious tissue, using the erbium laser with the appropriate energy, allows the removal of all the carious tissue and minimally the healthy tissue. The more careful we are with the selective ablation, the more the resulting cavity design will correspond to the extent of the carious process. Therefore should we have no more pre-ordained cavity designs, but different designs for different clinical situations [Olivi et al., 2007, 2008]. The laser-prepared cavities are very clean and decontaminated, with no smear layer, and also present a macro-roughened surface that increases the surface effectively exposed for the adhesion procedure [Olivi et al., 2008].

Pulp temperature. Numerous studies agree that less thermal increase occurs in the pulp chamber during cavity preparation, demonstrating that laser treatment does not cause an inflammatory reaction of the pulp [Dostalova et al., 1997; Eversole et al., 1997]. This important data is especially so in dental trauma [Olivi et al., 2010; Caprioglio et al., 2010] and in the treatment of cavities with deep caries [Olivi et al., 2006, 2007]. This has been subsequently confirmed by other authors [Glockner et al., 1998], who also emphasised how no variation in the environmental temperature of 37[degrees]C occurred in the first 3-4 secs while subsequently there was even a decrease in the temperature that remained at about 25-30[degrees]C.

A recent study [Krmek et al., 2009] summarises all these concepts with very promising results about the efficacy and the safety of the use of the erbium laser in conservative cavity preparation. The highest rise in temperature in the pulp was achieved with the highest energy used on the enamel (400 mJ and 15 Hz) and the lowest with the lowest energy (320 mJ and 10 Hz). The temperature rise ranged from a maximum of 1.99 +/- 0.28[degrees]C to a minimum of 0.70 +/- 0.18[degrees]C. In dentine the highest temperature increase was achieved with 340 mJ and 10 Hz (1.37 +/- 0.42[degrees]C), and the lowest was with 200 mJ and 5 Hz (0.43 +/- 0.18[degrees]C). Two-way analysis showed that the influence of energy on temperature increase was stronger than that of frequency. Table 3 shows the parameters for the use of the laser erbium, chromium:YSGG and erbium:YAG in restorative procedures and also shows the suggested parameters for cavity preparation, dentine decontamination and pulp coagulation.

Erbium laser soft tissue use. The use of the erbium laser on soft tissue is extremely effective especially in conservative therapy, to expose the subgingival cervical margins of the carious cavity (Figs. 9 and 12d). The quantity of tissue to be removed is generally limited and the procedure is absolutely asymptomatic. Actual crown lengthening that invades the biological width of the gingival tissue is rare in paediatric restorative dentistry, usually only performed in the case of coronal fractures. This procedure is traditionally performed with analgesia due to the need to remove both bone and gingival tissue to maintain the biological width. It can be performed effectively with erbium lasers, for their capacity to work on both bone tissue and gingival tissue.

Erbium laser conservative therapy of the pulp. Erbium lasers have also been found to be very effective in the performance of partial pulpotomy and coagulation of the exposed pulp, in pulp capping procedures [Olivi and Genovese, 2006; Olivi et al., 2007]. This is due to the decontaminating and superficial coagulating action, with minimum transfer of energy to the underlying pulp in reversible hyperaemia. Obviously the success of the procedure also depends on the correct diagnosis of reversible pulpitis or accidental exposure of the pulp.

Few studies are indexed in PubMed that investigate laser use in maintaining pulp tissue vitality. The common delineator has been the low laser energy applied according to the different wavelength used (from 0.5 to 1.0W), delivered in defocused mode. Preferably this should be in pulsed or super-pulsed mode with low frequency for better control of the irradiation, defocused, without water, and must not exceed 10 secs to obtain coagulation. The procedure can be repeated after 30 secs, the time needed for the pulp tissue to cool.

Olivi and Genovese [2006] first reported the advantages of in vivo use of the Er,Cr:YSGG laser, as a single minimally invasive instrument for carious removal and pulp coagulation. Laser irradiation avoided over-preparation and overheating of the residual dental tissue, with tooth survival of 80% after 4 years. In another study [Olivi et al., 2007] conducted at the Paediatric Department of the University of Tor Vergata (Rome) a comparison was presented of the efficacy of Er,Cr:YSGG and Er:YAG lasers, with conventional calcium hydroxide procedure. An 80% success rate was reported in the Er,Cr:YSGG group, 75% in the Er:YAG group, while the control group presented 63% success after 2 years.

Other wavelengths have been suggested for this procedure, mainly by Moritz et al. [1998a, b], with the C[O.sub.2] laser, who reported 89% and 93% success rates after 1 and 2 years compared with 68% and 66% for the calcium hydroxide control group. This was due to the purely thermal effect on the tissue due to C[O.sub.2] that is absorbed by a fine tissue layer (100[micro]) and transformed into heat.

Critical evaluation of disadvantages

Education, cost and investment return. Even if laser technology is intuitive, it also requires specific knowledge and a refined performance technique because it is a non-contact procedure. Instruction at a university or other academic site together with a period of training is necessary before approaching a patient, especially a child, The costs of equipment, the time it takes to train and the relative costs are however generously repaid by the clinical results and the range of procedures that can be performed in a simple, safe and efficacious way in diverse branches.

Lasers and adhesive dentistry. The studies in the literature on this topic have taken into consideration tests both of microleakage and of bond strength, performed by laser alone, with or without acid etching and compared with traditional techniques. The reported results are very disparate and contrasting, both with permanent and primary teeth. Based on these references, it is difficult to arrive at any conclusions, because the studies cannot be compared for various reasons, as the variables occur in multiple areas: different power density and fluence used are only one aspect of the energy delivered to the target tissue. Air/water flow and pressure of the integrated spray, the pulse length, the beam profile, are other parameters that affect the results of the laser tissue interaction, together with operator factors such as laser angulation, focus mode, hand speed movement: if incorrect, all these factors can cause sub-structural damage, overall to the dentine.

A selection of indexed papers in Pubmed studies is presented here; the effectiveness of laser irradiation to influence the bond strength and microleakage on the enamel and dentine of primary teeth was investigated. Some reported favourable results using only the laser without etching with orthophosphosphoric acid [Yamada et al., 2002; Kohara et al., 2002; Wanderley et al., 2005; Sung et al., 2006], while others found that even in primary teeth, acid etching of the enamel and dentine was necessary to obtain results equal to those obtained with traditional techniques [Monghini et al., 2004; Borsatto et al., 2006; Lessa et al., 2007]. Even the diverse materials and adhesives used have not been evaluated critically [Quo et al., 2002].

Combining the traditional technique of cavity margin refinishing, acid etching of the enamel and the dentine with the laser preparation technique, the advantages of both techniques can be employed. Minimising the disadvantages that are correlated with the thermal effect of the laser at the dentinal level, where the organic matrix is vapourised with the ablative energy used, and of the enamel, make a final conditioning advisable at low wattage both on dentine and enamel.

The principle disadvantage of the laser technique in terms of microleakage and thus of adhesion at the enamel margins can be avoided with a mechanical finishing of the cavity margins, with manual, rotative or ultrasonic instruments followed by etching with 35-37% orthophosphoric acid. Currently, the procedure using 35-37% orthophosphoric acid for 20-30 secs, remains the only common denominator that makes the diverse results obtained with different instruments uniform, eliminating the thin layer of dentine substructural damage, exposing the collagen fibres and creating a substrate for the formation of the hybrid layer. Acid etching also modifies the Silverstone classification of type 2 and 3 enamel lesions, allowing a better composite resin adaptation to the enamel margins of the cavity [Olivi et al., 2009].

Conclusion

The laser erbium technology, introduced in restorative dentistry in 1997 by Keller and Hibst, after 20 years of research, improvement and increasingly widespread clinical use, represents today a safe device, to effectively and selectively remove carious tissues from decayed teeth. Beside the laser itself, the human factor, with each operator's differing level of skill and knowledge, represents both the limit and the widespread acceptance of this therapy. For children, all the recognized advantages of this technique play a decisive role in the successful day-to-day treatment of carious pathologies and beyond.

References

Apel C, Meister J, Ioana RS, et al. The ablation threshold of Er:YAG and Er:YSGG laser radiation in dental enamel. Lasers Med Sci 2002;17:246-252.

Apel C, Meister J, Schmitt N, et al. Calcium solubility of dental enamel following sub-ablative Er:YAG and Er:YSGG laser irradiation in vitro. Lasers Surg Med 2002;30: 337-341.

Apel C. Birker L, Meister J, et al. The caries-preventive potential of subablative Er:YAG and Er:YSGG laser radiation in an intraoral model: A pilot study. Photomed Laser Surg 2004;22:312-317.

Barberia E, Maroto M, Arenas M, Silva CC. A clinical study of caries diagnosis with a laser fluorescence system. J Am Dent Assoc 2008;139:572-579.

Benedicenti A. Laser therapy ability in the trigeminal neuralgia treatment. (article in italian) (Le possibilita della laser terapia nella cura della nevralgia del trigemino). Parodontologia e Stomatologia Nuova 1979;3:21.

Benedicenti A. Laser Atlas (Atlante di Laser), ed. Villa Carcina, Italy: Teamwork, 2005.

Bengtson AL, Gomes AC, Mendes FM, et al. Influence of examiner's clinical experience in detecting occlusal caries lesions in primary teeth. Pediatr Dent 2005;27:238-243.

Boj J, Galofre N, Espana A, Espasa E. Pain perception in paediatric patients undergoing laser treatments. J Oral Laser Applications, 2005;2:85-89

Borsatto MC, Corona SA, Ramos RP, et al. Microleakage at sealant/enamel interface of primary teeth: Effect of Er:YAG laser ablation of pits and fissures. J Dent Child 2004;71:143-147.

Borsatto MC, Corona SA, Chinelatti MA, et al. Comparison of marginal micro leakage of flowable composite restorations in primary molars prepared by high-speed carbide bur, Er:YAG laser, and air abrasion. J Dent Child. 2006 May-Aug;73(2):122-6.

Borsatto MC, Corona SA, de Araujo FP, et al. Effect of Er:YAG laser on tensile bond strength of sealants in primary teeth. J Dent Child (Chic) 2007;74:104-108.

Braga M, Nicolau J, Rodriguez CR, et al. Laser fluorescence devise does not perform well in detection of early caries lesions in primary teeth: An in vitro study. Oral Health Prev Dent 2008;6:165-169.

Burin C, Burin C, Loguerciao AD, et al. Occlusal caries detection: A comparison of a laser fluorescence system and conventional methods. Pediatr Dent 2005;27:307-312.

Caprioglio C, Olivi G, Genovese MD. I laser in Traumatologia Dentale. Ed.Martina, 2010, Bologna, Italia.

Chu CH, Lo EC, You DS. Clinical diagnosis of fissure caries with conventional and laser-induced fluorescence techniques. Lasers Med Sci 2010 May;25:355-362.

Costa AM, Paula LM, Bezerra AC. Use of diagnodent for diagnosis of non cavitated occlusal dentine caries. J Appl Oral Sci 2008; 16:18-23.

Dostalova T, Jelinkova H, Krejsa O, et al. Dentine and pulp response to Erbium:YAG laser ablation: a preliminary evaluation of human teeth. J Clin Laser Med Surg. 1997;15(3):117-21.

Eversole LR, Rizoiu I, Kimmel AI. Pulpal response to cavity preparation by an erbium, chromium:YSGG laser-powered hydrokinetic system. J Am Dent Assoc. 1997 Aug;128(8):1099-106.

Francescut P, Lussi A. Correlation between fissure discolouration, Diagnodent measurements, and caries depth: An in vitro study. Pediatr Dent 2003;25:559-564.

Featherstone JDB, Fried D, Bitten ER. Mechanism of laser-induced solubility reduction of dental enamel. In: Wigdor HA, Featherstone JDB, Rechmann P (eds). Lasers in Dentistry III. Proceedings Volume 2973. Bellingham, WA:SPIE, 1997:112-116.

Featherstone JDB, Barrett-Vespone NA, Fried D, Kantorowitz Z, Seka W. C[O.sub.2] laser inhibition of artificial caries-like lesion progression in dental enamel. J Dent Res 1998;77:1397-1403.

Francescut P, Lussi A. Performance of a conventional sealant and a flowable composite on minimally invasive prepared fissures. Oper Dent 2006;31:543-550.

Genovese MD, Olivi G. Laser in paediatric dentistry: patient acceptance of hard and soft tissue therapy. Eur J Paediatr Dent. 2008;9(1):13-7.

Glockner K, Rumpler J, Ebeleseder K, Stadtler P. Intrapulpal temperature during preparation with the Er:YAG laser compared to the conventional burr: an in vitro study. J Clin Laser Med Surg. 1998;16(3):153-7.

Gutknecht N, Franzen R, Vanweersch L, Lampert F. Lasers in Pediatric Dentistry--A Review. J Oral Laser Applications 5 (2005), No. 4, Page 207-218.

Hadley J, Young DA, Eversole LR, Gornbein JA. A laser-powered hydrokinetic system for caries removal and cavity preparation. J Am Dent Assoc 2000;131:777-785.

Hirota F, Furumoto K. Temperature rise caused by laser (C[O.sub.2], Nd:YAG, Er:YAG) irradiation of teeth. Int Congress Ser 2003;1248:301-304. 48.

Huth KC, Neuhaus KW, Gygax M, et al. Clinical performance of a new laser fluorescence device for detection of occlusal caries lesions in permanent molars. J Dent 2008;36:1033-1040.

Keller U, Hibst R. Effects of Er:YAG laser in caries treatment: a clinical pilot study. Lasers Surg Med. 1997;20(1):32-8.

Keller U, Hibst R, Geurtsen W, et al. Erbium:YAG laser application in caries therapy. Evaluation of patient perception and acceptance. J Dent. 1998 Nov;26(8):649-56.

Khalife MA, Boynton JR, Dennison JB, et al. In vivo evaluation of DIAGNOdent for the quantification of occlusal dental caries. Oper Dent 2009;34:136-141.

Kohara EK, Hossain M, Kimura Y, et al. Morphological and microleakage studies of the cavities prepared by Er:YAG laser irradiation in primary teeth. J Clin Laser Med Surg. 2002 Jun;20(3):141-7.

Krmek SJ, Miletic I, Simeon P, et al. The temperature changes in the pulp chamber during cavity preparation with the Er:YAG laser using a very short pulse. Photomed Laser Surg. 2009 Apr;27(2):351-5.

Iwami Y, Shimizu A, Narimatsu M, et al. Relationship between bacterial infection and evaluation using a laser fluorescence device, DIAGNOdent. Eur J Oral Sci 2004;112:419-423.

Lepri TP, Souza-Gabriel AE, Atoui JA, et al. Shear bond strength of a sealant to contami-nated-enamel surface: Influence of erbium:yttrium-aluminumgarnet laser pretreatment. J Esthet Restor Dent 2008;20:386-392.

Lessa FC, Mantovani CP, Barroso JM, et al. Shear bond strength to primary enamel: influence of Er:YAG laser irradiation distance. J Dent Child (Chic).2007 Jan-Apr;74(1):26-9.

Liu JF, Lai YL, Shu WY, Lee SY. Acceptance and efficiency of Er:YAG laser for cavity preparation in children. Photomed Laser Surg. 2006 Aug;24(4):489-93.

Lupi-Pegurier L, Bertrand MF, Genovese O, et al. Microleakage of resin-based sealants after Er:YAG laser conditioning. Lasers Med Sci 2007;22:183-188.

Lussi A, Francescut P. Performance of conventional and new methods for the detection of occlusal caries in deciduous teeth. Caries Res 2003;37:2-7.

Lussi A, Reich E. The influence of toothpastes and prophylaxis pastes on fluorescence measurements for caries detection in vitro. Eur J Oral Sci 2005;113:141-144.

Manton DJ, Messer LB. The effect of pit and fissure sealants on the detection of occlusal caries in vitro. Eur Arch Paediatr Dent 2007 Mar;8:43-48.

Martens LC. Laser-assisted Paediatric Dentistry: Review and Outlook, J Oral Laser Applications 2003, Vol 3, No 4, pp. 203-209.

Martens LC. Laser physics and a review of laser applications in dentistry for children. Europ Archs Paediatr Dept 2011; 12:61-67

Matson JR, Matson E, Navarro RS, et al. Er:YAG laser effects on enamel occlusal fissures: An in vitro study. J Clin Laser Med Surg 2002;20:27-35.

Matsumoto K, Hossain M, Hossain MM, et al. Clinical assessment of Er,Cr:YSGG laser application for cavity preparation. J Clin Laser Med Surg. 2002 Feb;20(1):17-21.

Mendes FM, Nicolau J, Duarte DA. Evaluation of the effectiveness of laser fluorescence in monitoring in vitro remineralization of incipient caries in primary teeth. Caries Res 2003;37;442-444.

Mendes FM, Hissadomi M, Imparato JC. Effects of drying time and the presence of plaque on the in vitro performance of laser fluorescence in occlusal caries of primary teeth. Caries Res 2004;38:104-108.

Mendes FM, Ganzerla E, Nunes AF, et al. Use of high-powered magnification to detect occlusal caries in primary teeth. Am J Dent 2006;19;19-22.

Monghini EM, Wanderley RL, Pecora JD, et al. Bond strength to dentine of primary teeth irradiated with varying Er:YAG laser energies and SEM examination of the surface morphology. Lasers Surg Med. 2004;34(3):254-9.

Moritz A, Schoop U, Goharkhay K, Sperr W. Advantages of a pulsed C[O.sub.2] laser in direct pulp capping: a long-term in vivo study. Lasers Surg Med. 1998a; 22(5):288-93.

Moritz A, Schoop U, Goharkhay K, Sperr W. The C[O.sub.2] laser as an aid in direct pulp capping. J Endod. 1998b Apr;24(4):248-51.

Moritz A. Oral Laser Application. Berlin: Quintessence, 2006.

Moshonov J, Stabholz A, Zyskind D, et al. Acid-etched and erbium:yttrium aluminium garnet laser-treated enamel for fissure sealants: A comparison of microleakage. Int J Paediatr Dent 2005;15:205-209.

Novaes TF, Matos R, Braga MM, et al. Performance of a pen-type laser fluorescence device and conventional methods in detecting approximal caries lesions in primary teeth--In vivo study. Caries Res 2009;43:36-42.

Olivi G, Genovese MD. Erbium Chromium Laser in Pulp Capping Treatment. Journal of Oral Laser Application Vol 6 No 4:2006; 291-299.

Olivi G, Genovese MD, Maturo P. Docimo R. Pulp capping: advantages of using laser technology. Europ Paediat Dent. 2007 Jun;8(2):89-95.

Olivi G, Costacurta M, Perugia C. Docimo R. Erbium Chromium laser in restorative therapy (article in italian). Il laser Erbium Chromium in terapia conservativa. Dental Cadmos. 2007;7:91-8.

Olivi G, Iaria G, Genovese MD. Laser in Aesthetic Dentistry: scientific basis for the use in Restorative Dentistry (article in italian). Laser in Odontoiatria Estetica: basi scientifiche dell'utilizzo in Conservativa. Cosmetic Dentistry. vol,2,Mag;2008;22-28

Olivi G, Genovese MD, Caprioglio C. Evidence-based dentistry on laser paediatric dentistry: review and outlook. Eur J Paediatr Dent. 2009;10(1):29-40. Review.

Olivi G, Caprioglio C, Genovese MD. Lasers in dental traumatology. Eur J Paediatr Dent. 2010;11(2):71-6.

Olivi G, Margolis FS, Genovese MD. Pediatric Laser Dentistry. A user's guide; pg.73-76. Chicago, IL, USA; 2011. Quintessence Publishing Co.

Parker SPA, Darbar AA, Featherstone JDB, et al. The use of laser energy for therapeutic ablation of intraoral hard tissues. J Laser Dent 2007;15:78-86.

Parkins F. Lasers in pediatric and adolescent dentistry. Dent Clin North Am. 2000;44(4):821-30.

Perhavec T, Diaci J. Comparison of Er:YAG and Er,Cr:YSGG dental lasers. J Oral Laser Appl 2008:8:87-94.

Sung EC, Lin CN, Harada V, et al. Composite bond strength to primary dentine prepared with Er,Cr:YSGG laser IADR 84th General Session, Brisbane, Australia, June 28-July 1, 2006 J Dent Res 85(Spec.Issue B): Abstract 0043.

Sungurtekin E, Ozta N. The effect of erbium, chromium:yttrium- scandiumgallium-garnet laser etching on marginal integrity of a resin-based fissure sealant in primary teeth. Lasers Med Sci 2009 Aug 5. [Epub ahead of print]

Takamori K, Furukawa H, Morikawa Y, et al. Basic study on vibrations during tooth preparations caused by high-speed drilling and Er:YAG laser irradiation. Lasers Surg Med. 2003;32(1):25-31.

Quo BC, Drummond JL, Koerber A, et al. Glass ionomer microleakage from preparations by an Er/YAG laser or a high-speed handpiece. J Dent. 2002 May;30(4):141-6.

Virajsilp V, Thearmontree A, Aryatawong S, Paiboonwarachat D. Comparison of proximal caries detection in primary teeth between laser fluorescence and bitewing radiography. Pediatr Dent. 2005; 27(6):493-9.

Wanderley RL, Monghini EM, Pecora JD, et al. Shear bond strength to enamel of primary teeth irradiated with varying Er:YAG laser energies and SEM examination of the surface morphology: an in vitro study. Photomed Laser Surg. 2005 Jun;23(3):260-7.

Wigdor H. Patients' perception of lasers in dentistry. Lasers Surg Med. 1997;20(1):47-50.

Yamada Y, Hossain M, Nakamura Y, et al. Microleakage of composite resin restoration in cavities prepared by Er:YAG laser irradiation in primary teeth. Eur J Paediatr Dent. 2002 Mar;3(1):39-45.

Youssef MN, Youssef FA, Souza-Zaroni WC, et al. Effect of enamel preparation method on in vitro marginal microleakage of a flowable composite used as pit and fissure sealant. Int J Paediatr Dent 2006;16:342-347.

G. Olivi, Dept. of Endodontics, University of Genoa DI.S.T.BI.M.O; M.D. Genovese, Private practice of Paediatric Dentistry and Orthodontics, Rome, Italy.

Postal address: Prof. G. Olivi. Piazza F. Cucchi, 3--00152 Rome, Italy.

Email: olivi.g@tiscali.it
Table 1. Suggested parameters from the authors for laser-assisted
sealant (LAS) and for laser minimally invasive pit and fissures
preparation.

Parameter                LAS                 PRR

Energy                   65-75mJ           150>200mJ

Pulse repetition rate    10-20Hz           20-25Hz

Power                    0.65-1,5W         3.0>5.0W

Tip                      400-600[micro]    600 [micro]

Pulse duration                   100-300 [micro]secs

Operative mode           Continuous movement--high ratio of air
                                    water spray--focused

Table 2. Operative and clinical advantages of laser treatment in
restorative dental treatment.

Operative Advantages:

Safety                    No rotating or cutting instruments used in
                          the mouth

Comfort                   No contact--no vibration--no noise

Painless                  Reduction of need for local anesthesia or
                          no anesthesia

Approach                  Improved patient compliance

Clinical Advantages       Minimally invasive: selective for carious
                          tissue

Decontaminating           Micro-retentive surface: cleaned and
effect: of deep caries    debrided surface

Less rise in              In pulp and periodontal surface during the
temperature               irradiation

Direct pulp capping       Coagulation/bactericidal
indication

Soft tissue               Exposure of subgingival tooth margins
application               during cavity preparation

Table 3. Suggested parameters for laser cavity preparation,
decontamination and conditioning for anterior permanent teeth and
primary teeth.

Er,Cr:YSGG and Er:YAG Laser settings for Primary teeth
(all the cavities) and Permanent anterior teeth

Clinical Indications                Pulse Frequency   Energy (mJ)
                                         (Hz)          Power (w)

Enamel conditioning before acid        10>20>50          65>75
etching                                               0.65>3.75W

Cavity preparation enamel                20>25          150-200
                                                       3.0>4.5W

Cavity preparation dentine               15>20          120>100
                                                       1.8>2.0W

Carious tissue                           20>25           75>80
                                                       1.5>2.0W

Dentine conditioning before acid         10>20            50
etching                                                0.5>1.0W

Dentine melting                          10>20            25
                                     per 5>10 sec      0.25>0.5W

Clinical Indications                Operative mode continuous
                                    movements

Enamel conditioning before acid     Contact-handpiece, at 1,5mm
etching                             high air: water spray ratio

Cavity preparation enamel           Contact-handpiece at 1,5mm
                                    high air: water spray ratio

Cavity preparation dentine          Contact-handpiece, at 1,5mm
                                    high air: water spray ratio

Carious tissue                      Contact-handpiece, at 1,5mm
                                    high air: water spray ratio

Dentine conditioning before acid    Defocused at 4-5mm high air:
etching                             water spray ratio

Dentine melting                     Defocused at 4-5mm low air:
                                    water spray ratio

short pulse duration 100-300 microseconds tip 400 [micro]m to 600
[micro]m
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