**2. Experimental methods**

The deposition of hydroxyapatite thin films has become a topic of interest in medical appli‐ cations. This dental film applied on the surface of the tooth may act as a(n) artificial, highly resistant, and flexible enamel, protecting teeth and removing tooth sensitivity. There is also a possibility for whitening and covering deficient enamel structure. We obtained this flexible film of hydroxyapatite using laser ablation. We also tried to apply the film on an extracted tooth. The plasma plumes were generated by an Nd:YAG nanosecond laser in a vacuum chamber with 10−6 Torr. We used the pulsed laser deposition technique and for the investiga‐ tions we opted for optical emission spectroscopy (OES) and Raman spectroscopy.

In this work, we studied the evolution of plasma plumes resulting from enamel and hydrox‐ yapatite ablation. The plasma plumes were generated by an Nd:YAG nanosecond laser and the depositions were performed in a cylindrical stainless steel vacuum chamber (10 L volume, 30 cm height, 20 cm diameter) (**Figure 1**). The chamber is evacuated to a base pressure of 10−6 Torr by a 550 L/s turbomolecular pump (Agilent Technologies TV-551) placed in a vertical position at the bottom of chamber. The target (HA) is placed on a micrometric precision XYZ stage and can be rotated with a motorized vacuum feedthrough (Caburn MDC). The target is placed on a metallic target holder, which is electrically isolated from the rest of the experiment by an alumina block. The substrate (salt) is placed parallel to the target. The target-substrate distance was 1.4 cm. The ablation laser beam was usually at 45° on the target surface (**Figure 2**).

**Figure 1.** Vacuum chamber.

dental sensitivity. Being very thin, it is invisible once applied on teeth and can be

This chapter describes a unique way to obtain a flexible pure hydroxyapatite film. In the past years, the nanocomposites have been in the center of attention due to their unique physical

Specifically, the biomaterials have been widely studied, motivated by their clinical applica‐ tions. Among these, the hydroxyapatite has been studied due to its remarkable properties, such as biocompatibility, osteoconductivity, and bioactivity. This material is naturally found in the human body, being one of the major constituents of bones and teeth. As a consequence, HA has been widely used in many fields, including biomedical applications. Our experiments led to the creation of a thin HA film that has the role of protecting teeth against cariogenic bacteria and could even have cosmetic effects by teeth whitening. This dental plaster acts as an artificial HA enamel, very resistant and flexible, protecting the tooth and eliminating dental sensitivity. Being very thin, it is invisible once applied on teeth and can be observed only by examination under a strong light. The plaster, produced by pulsed laser deposition (PLD), can be manipulated with tweezers and applied on the tooth. The originality of our approach consists in the fact that the flexible HA film can be obtained in pure state, because it grows without a substrate, using just a base and lateral supports between which it will grow on

The deposition of hydroxyapatite thin films has become a topic of interest in medical appli‐ cations. This dental film applied on the surface of the tooth may act as a(n) artificial, highly resistant, and flexible enamel, protecting teeth and removing tooth sensitivity. There is also a possibility for whitening and covering deficient enamel structure. We obtained this flexible film of hydroxyapatite using laser ablation. We also tried to apply the film on an extracted tooth. The plasma plumes were generated by an Nd:YAG nanosecond laser in a vacuum chamber with 10−6 Torr. We used the pulsed laser deposition technique and for the investiga‐

In this work, we studied the evolution of plasma plumes resulting from enamel and hydrox‐ yapatite ablation. The plasma plumes were generated by an Nd:YAG nanosecond laser and the depositions were performed in a cylindrical stainless steel vacuum chamber (10 L volume, 30 cm height, 20 cm diameter) (**Figure 1**). The chamber is evacuated to a base pressure of 10−6

tions we opted for optical emission spectroscopy (OES) and Raman spectroscopy.

**Keywords:** hydroxyapatite, biocompatibility, films, biomaterials, laser, tooth

observed only by examination under a strong light.

**1. Introduction**

3402 High Energy and Short Pulse Lasers

vertical direction.

**2. Experimental methods**

and chemical properties.

**Figure 2.** Experimental setup of an Nd:YAG nanosecond laser (Continuum Surelite III-10) (gw = 1 μs, gd = 25 ns).

**Figure 3.** (a) Vacuum chamber with target; (b) 1 plasma tooth; (c) 1 tooth after ablation; (d) 1 HA after ablation.
