Case report: laser-assisted rebonding of a central incisor tooth due to a severe trauma--4 years of follow-up.
Abstract: BACKGROUND: The success of reattaching fractured tooth crowns fragments, as a result of trauma, has improved as a result of the introduction of lasers in dental care. This case report documents a 4 year follow-up of a re-bonded tooth fragment on a maxillary first permanent incisor. CASE REPORT: An 8-year-old girl presented with a fractured maxillary might first permanent incisor (II) as a result of a severe trauma. The child's parents had preserved the tooth fragment in a glass of milk immediately after the injury. TREATMENT: An Er,Cr:YSGG Laser with a wavelength of 2,780nm was used with 20Hz, 5W (250 mJ), 90 % air, 80% water for etching of the enamel and 20 Hz, 3W (150 mJ), 65% air, 55% water for dentine etching with a G6 (600 micron, sapphire, 6mm long) tip. For conditioning the enamel and dentine no additional acid etching was used. Only a 2 step self-etched adhesive system Clearfil Protect[R] (Kuraray Medical, Japan) was applied. Then a flowable composite resin, Grandi Flow[R] (Voco, Cuxhaven, Germany) was applied in order to bind the broken fragment onto the tooth. FOLLOW-UP: The re-bonded tooth fragment has been retained in place and symptom free, as assessed by clinical examination, intraoral photographs and radiographs for a period of 4 years. CONCLUSION: Laser-assisted re-bonding of a tooth fragment was found to be successful.

Key words: Laser, Er., Cr:YSGG, rebonding, tooth fragment, fractures.
Article Type: Report
Subject: Crowns (Dentistry) (Usage)
Crowns (Dentistry) (Health aspects)
Lasers in medicine (Health aspects)
Tooth diseases (Care and treatment)
Pedodontics
Authors: Berk, N.
Berk, G.
Ulucam, S.
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: 277106750
Full Text: Introduction

Crown and crown-root fractures of anterior primary or permanent teeth of children are the most common dental accidents during childhood. Bonding of the permanent tooth fragment is a logical restorative treatment option when the trauma results in no or minimal damage to the biological tissues surrounding the tooth. Reattachment of crown tooth fragments can provide favourable and long-lasting aesthetics because the tooth's original anatomic form, colour, and surface texture are maintained [Macedo and Ritter, 2009].

If the crown fragments of a fractured tooth remain within the dentinal region, several different treatments can be used after the necessary radiological and clinical evaluations. If a fragment is small, it can be restored with suitable composite resin (CR) restorations. But the stability of the CR restoration is limited. Due to nutritional habits and oral hygiene of an individual, CR restorations can change colour and have to be renewed over time. If the tooth fragment is large, consisting of half or more of the tooth crown, the best treatment is to consider restoring the fractured tooth using the original displaced fragment. This approach gives a good aesthetic result and colour match [Andreasen et al., 1995. Burden, 1995; Kania et al., 1996; Cortes et al., 2001]. If a patient is more than 17 years old, however, porcelain laminate veneers can also be used.

The use of lasers is becoming more common in paediatric dentistry [Martens, 2011; Olivi and Genovese, 2011]. The major advantages of hard tissue lasers such as Er:YAG and Er,Cr:YSGG are essentially that the use of providing a smear-free surface, good adhesion, lack of vibration and lack of need for local analgesia in most cases. Both Er:YAG and Er;Cr:YSGG lasers have FDA approval (Government of USA) for hard tissue applications and both laser wavelengths have the highest absorption in water of any dental wavelength and have a high affinity for hydroxyapatite. The laser energy couples into the hydroxyl radical in the apatite crystal and into the water that binds to the crystalline structures of the tooth. The vapourisation of the water within the mineral substrate causes the surrounding material to literally explode away [Eversole et al., 1997].

One of the basic advantages of the laser cavity preparation compared with conventional techniques is the temperature change of the pulp. It had been reported that the use of a bur preparation, with an insufficient cooling, may lead to a temperature rise of over 15[degrees]C when the critical temperature rise lies at about or above 5.5[degrees]C, at which a high percentage of the pulp cells are killed. But for Er:YAG or Er;Cr:YSGG laser prepared cavities, with the suggested cooling settings, a decrease in the temperature of the pulp has been recorded [Moritz, 2005].

The bactericidal effects of the Er,Cr:YSGG laser irradiation have been reported by many different studies. It has been found that with a certain amount of energy, Er,Cr:YSGG laser has a bactericidal effect on even the deeper layers of dentine for the most common bacteria, such as Escherichia coli and Enterococcus faecalis [Schoop et al., 2004; Gordon et al., 2007; Franzen et al., 2009].

Laser prepared enamel has a chalk-like appearance that is similar to the acid etched characteristic of enamel and enamel rods [Trajtenberg et al., 2004]. Laser etching is painless and does not involve vibration or heat, making it very useful for routine use. Furthermore, laser etching of enamel or dentine has been reported to yield a fractured and uneven surface and open dentine tubules, both apparently ideal for adhesion [Secilmis et al., 2009]. The Er,Cr:YSGG laser can also etch enamel for orthodontic purposes. It was stated that the mean shear bond strength and enamel surface etching obtained with an Er,Cr:YSGG laser (operated at 1W or 2W for 15 seconds) is comparable to that obtained with acid etching [Basaran et al., 2007].

Case report

An 8-year-old girl was brought a our paediatric dental clinic after a severe trauma to her face and maxilla. Due to the trauma she had minor soft tissue contusions but also a broken right maxillary first permanent incisor (tooth II). The patients' mother had been advised to immediately keep the piece of broken tooth in a glass of milk while bringing her child for treatment. After the child arrived, intra-oral pictures (Fig. 1a) and digital periapical radiograph (Fig. 1b) of the tooth II were taken. There were no sign of broken bone or other pathological findings and the apexification of II almost complete of II.

[FIGURE 1 OMITTED]

Treatment

An Er;Cr:YSGG laser (Waterlase, Biolase, CA, USA, wavelength of 2,780 nm) was used for etching the fractured tooth crown and the broken fragment before re-bonding without any analgesia. The laser parameters were as follows:

* 20Hz, 5W (250 mJ), 90 % air,

* 80% water for etching of the enamel and 20 Hz, 3W (150 mJ),

* 65% air, 55% water for dentine etching with a G6 (600 micron, sapphire, 6mm long) tip.

After air-drying both tooth and fragment surfaces, a chalk-like appearance of the enamel on both surfaces was observed (Fig. 2). No additional acid etching was used for conditioning the enamel and dentine, but a 2 step-self etched adhesive system (Clearfil Protect[R], Kuraray Medical, Japan) was applied. Then a flowable CR, (Grandi Flow[R], Voco, Cuxhaven, Germany) was used in order to bind the broken fragment to the retained tooth. Polishing discs were used to remove the excess CR and for polishing the surface. Then post-operative pictures of the patient were taken (Fig. 2b). Application of ice was recommended to prevent the swelling of the injured soft tissues.

[FIGURE 2 OMITTED]

Follow-up

The patient was recalled 1 week after initial treatment. She only had to take analgesics for the first 3 days after the trauma, due to her soft tissue contusions. At the time of the first follow-up appointment a digital radiograph was taken and a recall appointment was scheduled for one month, two months then every following 6 months.

On every appointment, digital radiographs and intra-oral pictures (Fig. 3 a and b) were taken and evaluated for any signs of internal or external resorption of the root surfaces. The latest follow-up appointment was performed 4 years post-trauma (Fig. 4 a and b). Periodic pulp vitality tests showed that the tooth was still healthy and remained vital.

[FIGURE 3 OMITTED]

[FIGURE 4 OMITTED]

Discussion

Of all the dental hard tissue traumas 18-22% are coronal fractures of permanent incisors. There are many different techniques described in the literature for re-bonding of tooth fragments [Mader, 1978; Ludlow and LaTurno, 1985; Croll, 1988; Baratieri et al., 1991]. If a tooth fragment fits exactly back into place, then it can be re-bonded provided that the endodontic, periodontal and occlusal evaluations are normal. Some researchers, however, do not support this technique because the re-bonded surface cannot withstand the occlusal forces that occur during protrusive movements [Baty et al., 1994; Chu et al., 2000; Vilela et al., 2003]. Traumatic forces affecting the teeth and periodontium can cause damage in different ways and degrees.

Re-bonding of a tooth fragment with acid-etch and adhesive system technique has been used for many years [Andreasen and Ravn, 1972; Mader, 1978; Baratieri et al., 1990]. Baratieri et al. [1990] introduced the 'Sandwich Technique' for rebonding of tooth fragments whereby the advantages of glass ionomer cements (GIC) and CR were combined. As this treatment technique gives an opportunity to treat cases with patients' own dental tissue, it has many advantages. Treatment with the original tooth fragment has better aesthetic than CR or porcelain restorations. Anterior guidance will be truer due to the similar physical appearance with a neighbouring tooth. Also, as a patient has the opportunity to use his or her own tooth, psychological and sociological status will be better. For many cases this technique is easy and quick to do [Simonsen, 1979; Simonsen 1982; Baratieri et al., 1990].

Due to the development of bonding agents there are some case reports concerning re-bonding of tooth fragments by using only bonding agents without using additional CR [Baratieri et al., 1994; Kanca, 1993]. On the other hand, laser-assisted bonding systems have also given promising results. But there is not sufficient evidence-based research about the shear bond strength of enamel surfaces prepared by lasers compared with surfaces prepared by burs. In none of the previous studies, the laser prepared surfaces was found to be less successful when compared with conventionally prepared enamel surfaces [Moritz, 2005; Basaran et al., 2007; Secilmis et al., 2009]. In most of the previous investigations laser prepared enamel surfaces with specific wavelengths with suitable settings for enamel etching were found to be more successful than with a bur preparation [Moritz, 2005].

Conclusion

Re-bonding of a broken tooth fragment, following trauma, with an Er,Cr:YSGG laser was found to be very successful, maintaining stability and vitality of the affected tooth.

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N. Berk *, G. Berk **, S. Ulucam **

* Orthodontist, Private practice, ** Paediatric Dentists, Private practice, DENTA FORM, Ankara, Turkey.

Postal address: Dr. N. BERK, Denta Form, Mahatma Gandi Cad. No:34 06700 G.O.P.-Ankara, Turkey.

Email: dentaform@yahoo.com
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