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S. Stübinger et al. (eds.)Lasers in Oral and Maxillofacial Surgerydoi.org/10.1007/978-3-030-29604-9_7
7. Use of Er:YAG Laser in Conservative Dentistry and Adhesion Process
This chapter deals with the use of Er:YAG laser in conservative laser dentistry as well as its part in the interaction with the adhesion process. Er:YAG laser is helpful in conservative dentistry. Its property to be absorbed by water and apatite can help clinicians in selective and microinvasive decay removal from tooth structure. The importance of using repeatable clinical protocol, to obtain a very strong adhesion effect with materials, brings medium- and long-term results of efficacy in conservative rehabilitations. The precision of the laser beam and its selectivity give the possibility to create new shapes for conservative cavity preparation.
Er:YAG laserConservative dentistryMicro leakageAdhesionThreshold ablation
7.1 Er:YAG Laser Interaction with Enamel and Dentine
Prevention and the safeguarding of the integrity of the tooth: the techniques and procedures carried out on the patient with a view to reducing the amount of cariogenic bacteria in the mouth in order to reduce the incidence of disturbances to the enamel and dentine tissue.
Curative treatment and restoration: microinvasive techniques for the removal of infected tissue and the use of selective long-wave laser for tissues with a greater water density may be useful in minimizing the sacrifice of healthy tissue during the process of ablation in order to preserve the architectonic structure of the tooth.
Restoration of lost tissue: the adhesive techniques that have now become part of the normal routine in our work allow and, indeed, oblige us to exploit any portion of healthy tissue remaining in order to ensure the preservation and restoration of the tooth. The use of laser and ER:YAG in order to improve the process of adhesion and micro-infiltration at a marginal level both on the enamel and the dentine.
Maintenance of dental health: checking up on the maintenance of the suitable margins of the reconstructions, the physiological wear and tear that result from chewing, and the duration of the adhesive interface in subsequent years is a fundamental step in the mechanical maintenance of conservative restoration .
Interactive selection with the tissue,
Compatibility with state-of-the art adhesive systems.
In order to make a cautious choice, we need to know the different wavelengths of the lasers so as to decide which is the most suitable for the abovementioned parameters.
In order to satisfy these requirements, we need to use a laser in which the predominant feature is the absorption of the rays on the tissue. In this respect, the wavelengths that best fit this requirement are ultraviolet wavelengths of between 190 and 300 nm, such as the excimer lasers used in ophthalmology because of their high rate of energy or infrared lasers such as CO2, Ho:YAG, Er:YAG, and Er-Cr:YSGG of between 2000 and 11,000 nm.
The penetration depth of these lasers is very slight, between 1 and 100 μm; the diffusion element is basically irrelevant, and there is no retro-diffusion.
In light of these considerations in the course of our work, we have chosen the Er:YAG 2940 nm laser for work on the hard tissue of the tooth.
Considering the various anatomical components that make up the tooth, the action of the laser will differ according to the work to be done on enamel or dentine tissue.
A mineral phase composed of around 50% apatite.
An organic phase of around 30% represented for 90% by type 1 collagen and 10% by non-collagen proteins as well as lipids.
A watery phase of 20%, 75% of which is present within the dentine tubes and 25% mineralized matrix that varies according to the anatomical area .
The dentine tubules, hollow structures that run through the dentine tissue in a centripetal direction toward the pulp chamber, represented by a number between 20 and 45,000/mm2, with a diameter comprising from 1 to 3 μm, contain the processes of odontoblasts, lamina sslimitans, collagen, fibers, dentine fluids, proteins, etc. There are also present numerous ramifications and anastomosis with a smaller diameter of between 50 nm and 1 μm.
The dentine is subdivided into three parts:
Intratubular dentine: characterized by presence of type 1 collagen fiber, crystalline structure, non-collagen proteins, lipids, and water.