# SEM Studies Assessing the Efficacy of Laser Treatment for Primary Teetis: A Systematic Review
## 4 Discussion
[21] also observed a smear layer and closed dentinal tubules after usage of the Er:YAG laser set at 200 mJ/10 Hz with water cooling of 7 mL/min from a 17-mm distance, but proved that it can be removed by 5.25% NaOCl. [PERSON] et al. [24] reported a smear layer and partial obstruction of dentinal tubules at settings of 60 mJ/2 Hz and 80 mJ/2 Hz, yet not at settings of 100 mJ/2 Hz, all based with the Er:YAG laser within a distance of 17 mm, with water mist at 5 mL/min. [PERSON] et al. [13] also observed almost no smear layer and mostly patent dental tubules after use of 300 mJ energy density with a repetition rate of 4 Hz with water at 1 mL/min. [PERSON] et al. [35] reported dentinal tubules closed by laser-melted material after use of the Nd:YAG laser (100 mJ, 15 Hz) but no smear layer and suggested using the Nd:YAG laser in endodontic treatments of deciduous teeth because of its ability to decrease dentin permeability, which leads to better isolation of developing permanent teeth from pathogens. Other authors denied the presence of a smear layer after lasing [42, 43, 44, 45, 46, 47]. There is no straightforward correlation between laser settings, amount of water cooling, and presence of a smear layer. This topic requires further research. To accurately assess the effectiveness of the treatment method, it is necessary to conduct a prolonged observation on a representative group of patients. Long-term follow-ups during clinical trials provide a comprehensive overview of the assessed issue. [PERSON] et al. [48] evaluated results of diode laser pulotomy on human primary teeth. Clinical and radiological controls took place after six and twelve months, allowing for a comparison between laser pulotomy and the formocresol method. The study concluded that there were no significant differences between these two methods. Similarly, the study carried out by [PERSON] et al. [49] showed promising results after a 12-month follow-up period. The systematic review conducted by [PERSON] et al. compared the effects of various pulp treatment techniques, yet it did not encompass laser treatment. This technique presents numerous disparities, as observed by other researchers, thus hindering a comparison [50]. For cavity restoration to be successful, it has to be durable and resistant to the influence of surrounding environments [51, 52]. The hybrid layer is a variable on which the longevity of composite fillings strongly depends [53, 54]. It decreases microleakage and prevents occurrence of secondary caries [27, 55]. [PERSON] et al. [27] stated that cavities prepared with the Er:YSGG laser and then acid etched present better results with respect to microleakage than those prepared with a traditional drill. But the hybrid layer thickness was reported to be thinner, probably due to ablation exerted by the laser system that leads to a decrease in the collagen content. [PERSON] et al. [24] found that acid etching of dentin still provides the best results in terms of the hybrid layer compared to the Er:YAG laser regardless of the energy level. However, [PERSON] et al. [16] measured tensile strength and came to the conclusion that bond strength achieved after treatment with the Er:YAG laser is similar to that achieved with a diamond burr. [PERSON] et al. [17] tested shear bond strength and came to the conclusion that bonding strength is enhanced after treatment with the Er:YAG laser. A definite majority of researchers agreed that use of a laser promotes better conditions for stronger resin bonding to dental tissues. However, the issue demands further evaluation due to some differences in experiment results. Laser treatment offers a significant advantage for both children and adults by minimizing pain [56, 57]. When treating children, creating a hospitable environment is crucial for a successful appointment [58, 59]. In pediatric dentistry, it is important to limit sound and vibration during treatment to avoid generating dental fear in young patients [9, 20, 60].