# Biophotonics in Dentistry
## 3 Applications in Dentistry
### Lasers
#### 3.4.2 Applications of Lasers  
Laser can be used to remove damaged tissue and treat caries and carious lesions. In 2001, interactions of laser with hard tissues were investigated, and the study found that pulsed carbon dioxide lasers markedly inhibit the progression of caries and that the selective removal of carious tissue is possible with laser [83]. The same result was found by [PERSON] et al. using a pulse 9.6 \(\upmu\)m CO\({}_{2}\) laser in a short-term pilot clinical trial of 24 subjects [124]. Demineralisation was inhibited by 46% in 4 weeks and by 87% in 12 weeks. A 2018 study by [PERSON] et al. found a near-infrared imaging system combined with a 9.3 \(\upmu\)m CO\({}_{2}\) laser aimed to ablate carious lesions in a selective manner. The laser, with the aid of an imaging, system successfully removed stimulated lesions and achieved a loss of only 12 \(\upmu\)m of healthy enamel [125]. This level of precision achieved by a laser combined with a sophisticated imaging system could not have been achieved with a mechanical drill. This study is significant in highlighting how laser technology can continue to be developed in dentistry. Aside from its reduced the precision, the use of a mechanical drill may also cause a build-up of matter on the tooth surface, which then reduces the adhesion of bonding agents. Phosphoric acid has been used to counteract this effect, but it causes further demineralisation of healthy tissue, whereas the use of laser leaves a clean surface [81]. In addition to removal of caries and inhibition of their progression, laser may also be applied as a preventative measure. [PERSON] et al. found that the use of a CO\({}_{2}\) laser enhances the resistance of enamel and dentin to caries formation [126]. This can be achieved if the tissue is exposed to laser to increase its temperature without ablating it. The result is a crystallographic change that causes a denser and more acid-resistant surface [81]. The haemostatic abilities of laser make it a very useful and versatile tool in dentistry. Some lasers may be employed to promote healing after tooth extraction. Lasers are able to produce micro-holes at the site in order to increase blood flow and increase the attachment \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Laser Type** & **Wavelength** & \multicolumn{2}{c}{**Applications**} \\ \hline CO\({}_{2}\) & 10.6 \(\upmu\)m & \(\bullet\) & Soft tissue ablation \\  & \(\bullet\) & Treatment of lesions \\  & & \(\bullet\) & Frenectomy and gingivectomy \\ \hline Nd:YAG & 1.064 \(\upmu\)m & \(\bullet\) & Root canal therapy \\  & & \(\bullet\) & Caries removal \\ \hline Er:YAG & 2.94 \(\upmu\)m & \(\bullet\) & Caries removal \\  & & \(\bullet\) & Root canal preparation \\ \hline Er,Cr:YSGG & 2.78 \(\upmu\)m & \(\bullet\) & Caries removal \\  & & \(\bullet\) & Cavity preparation \\  & & \(\bullet\) & Bone ablation \\  & & \(\bullet\) & Root canal preparation \\ \hline Argon & 572 nm & \(\bullet\) & Polymerization of restorative resin materials \\  & & \(\bullet\) & Treatment of lesions \\  & & \(\bullet\) & Frenectomy and gingivectomy \\ \hline Diode & 810–980 nm & \(\bullet\) & Promotion of healing of lesions or surgical \\  & & & wounds \\  & & \(\bullet\) & Frenectomy and gingivectomy \\ \hline HO:YAG & 2.1 \(\upmu\)m & \(\bullet\) & Treatment of lesions \\  & & \(\bullet\) & Frenectomy and gingivectomy \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Brief summary of commonly used lasers and their applications in dentistry. Adapted with permission from Ref. [82] 2022, IntechOpen. of osteoblasts to the implant, thereby increasing the success rate of dental implants and simultaneously lowering the risk of infection [81]. [PERSON], [PERSON] and [PERSON] investigated the use of a diode laser in the healing of extracted tooth sockets of rabbits. Histological examination showed that the use of laser formed new bone faster, with increased density and volume compared to control sockets [127].