# Laser Applications in Metal Orthodontic Bracket Debonding: A Systematic Review
## 4 Discussion  
This systematic review evaluated the safety and efficacy of various lasers utilized for the removal of metallic orthodontic brackets compared to conventional techniques. The lasers examined in these studies included Nd:YAG [41], Er,Cr:YSGG [44; 45], diode lasers [46; 47], and Er:YAG [5; 42; 43]. Laser-assisted debonding generally resulted in less adhesive residue on the tooth surface compared to conventional methods [44; 45], and there were no significant differences in the shear bond strength (SBS) between the two approaches in most studies [41; 46]. Temperature increases during laser use varied depending on the laser wavelength, power settings, and water cooling [42; 43; 47]. Only two studies provided detailed adhesive remnant index (ARI) data, showing fewer adhesive remnants on enamel with laser-assisted debonding compared to conventional techniques [44; 45]. Safety to tooth pulp is a critical concern when considering the use of lasers, as they can elevate the temperature of the irradiated surface [48]. The Nd:YAG laser was investigated for debonding metal brackets [41], with findings indicating that improper laser settings, such as excessive power or prolonged exposure, could significantly increase the pulp temperature. A normal intrapulpal temperature ranges between 34 and 35 \({}^{\circ}\)C, while an increase beyond 42-42.5 \({}^{\circ}\)C can result in irreversible pulp tissue damage including necrosis [49; 50; 51]. [PERSON] et al. [41] reported that a 2 W Nd:YAG laser caused a pulp temperature rise of up to 7 \({}^{\circ}\)C and alterations in the enamel structure, making this setting unsuitable for safe bracket removal. These findings highlight the critical importance of precise control over laser parameters including power, exposure duration, and cooling mechanisms to avoid adverse effects. The Er:YAG and Er:Cr:YSGG lasers were also assessed, with studies by [PERSON] et al. [43], [PERSON] et al. [45], and [PERSON] et al. [5] showing that these lasers were safe when combined with water cooling, which effectively limits the temperature increases and reduces the risk of pulp damage. Nevertheless, the potential \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Criteria/Authors** & **[PERSON],** **et al.**[41] & **[PERSON] [PERSON],** **et al.**[44] & **[PERSON] **et al.**[46] & **[PERSON]**et al.**[42] & **[PERSON]**et al.**[45] & **[PERSON]**et al.**[5] & **[PERSON],**et al.**[43] & **[PERSON] et al.**[47] \\ \hline Group size of at least & 10 subjects & 1 & 1 & 1 & 1 & 1 & 1 \\ \hline Sample size calculation & 0 & 1 & 1 & 0 & 0 & 0 & 0 & 1 \\ \hline Control group & 1 & 1 & 1 & 1 & 1 & 1 & 0 & 1 \\ \hline Randomization & 1 & 0 & 1 & 0 & 1 & 0 & 0 & 1 \\ \hline Detailed description & & & & & & & & \\ of debonding & 1 & 1 & 1 & 1 & 1 & 1 & 1 \\ procedure & & & & & & & \\ \hline Detailed description & & & & & & & \\ of a laser parameters & 1 & 1 & 1 & 1 & 1 & 1 & 1 \\ \hline The type of adhesive & & & & & & & \\ composite used to & & & & & & & \\ attach the bracket to & & & & & & & \\ the tooth & & & & & & & \\ \hline Total points & 5 & 6 & 7 & 5 & 6 & 5 & 4 & 7 \\ \hline Risk of bias & Moderate & Low & Low & Moderate & Low & Moderate & Low \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Quality assessment. impact on the enamel structure requires careful attention. Similarly, [PERSON] et al. [47] found that a 980-nm diode laser at 2.5 W was safe; however, at 5 W, the temperature rise posed a considerable risk of irreversible pulp damage, underscoring the necessity of optimizing power settings for safe laser use. Another systematic review by [PERSON] et al. regarding the laser debonding of ceramic brackets reported that it was a safe method for the pulp when the power of the lasers used did not exceed 3 W, the time of irradiation was properly matched, and water cooling was used [21]. Reducing the shear bond strength (SBS) between the tooth surface (enamel) and the orthodontic bracket is crucial for debonding without risking damage to the enamel prisms.