## 4 Discussion  
Overall, the overwhelmingly positive experiences of patients treated with the CO\({}_{2}\) laser in this study are consistent with prior studies for Er:YAG lasers. Patient preferences for laser over conventional treatments are generally high; however, our patient preference of 98% is higher than values typically reported for Er:YAG laser treatment in children and adults. These reported values have ranged from 72 to 92% [12; 16; 17; 24]. The null hypothesis that patients would not prefer the CO\({}_{2}\) laser to traditional handpieces for cavity preparations was rejected. This is bolstered by the fact that our patient discomfort scores were low, even when supplemental handpiece treatments were performed. This is also similar to reports for Er:YAG lasers, in which pediatric patients experienced less pain with a laser than drill [25], patients are more comfortable with laser treatment than conventional therapy [16], the majority (82.5%) of pediatric patients experienced no pain with laser treatment [24], and laser procedures on children were more comfortable than traditional procedures 67% of the time [24]. The null hypothesis that patients would have a high-level of discomfort during laser cavity preparations was also rejected. Our patients' strong preference not only for lasers, but for no anesthetic, also mirrors results by [PERSON] (1994) who found that 51 out of 54 patients required no local anesthesia for laser treatments for many different dental procedures [20]. In total, it appears that patient experiences when using a CO\({}_{2}\) laser for cavity preparations is equal to or greater than those reported for Er:YAG laser use. There were some interesting trends within our sample population, in particular the significant, inverse correlation between discomfort and age, and the higher rates of anesthesia use in younger individuals. The authors suggest that this stems from the relative pulpal proximity to cavity preparations in younger patients and is not related to specific characteristics of the laser. The CEI demonstrated that all clinicians had generally favorable views of laser cavity preparations. This contrasts with prior work in several ways. In another comparative study, [PERSON] et al. (2000) found that clinicians significantly preferred conventional handpieces for cavity preparations due to the slow cutting speed of the Er:YAG laser and difficulty using the laser handpiece to access cavity preparations [12]. Similarly, [PERSON] and [PERSON] (2013) found that cavity preparation with an Er:YAG laser took nearly 4 times longer than with a conventional handpiece [26], and [PERSON] et al. (2018) reported that it took 3 times longer [27]. This contrasts with our study, in which the clinicians reported high (positive experience) scores for both speed (4.18 \(\pm\) 0.86) and ease-of-use (4.13 \(\pm\) 0.92) on the 5-point scale (see Figure 3). This may be due to the absorption characteristics of the 9300 nm CO\({}_{2}\) wavelength versus the Er:YAG wavelength as previously discussed and the physical characteristics of the Solea handpiece and delivery system. The null hypothesis that clinicians would not prefer the CO\({}_{2}\) laser to traditional handpieces for cavity preparations was also rejected. This clinical study demonstrated several limitations. To ensure minimal change to standard treatment plans, the clinicians were given no restriction on use of supplemental high and slow speed handpieces in conjunction with laser therapy. This means that some patients received one or both forms of cavity preparation. While not formally investigated, subsequent discussion with the clinicians indicated several reasons for using handpieces during the treatment, including confidence in completing outline and caries removal without tactile sensation, the speed of refining cavity preparations, and concerns over the length of the laser-induced analgesic-like effect. Larger operative procedures including cuspal coverage were also not included in this study.