# SEM Studies Assessing the Efficacy of Laser Treatment for Primary Teetis: A Systematic Review
## 3 Results
### General Study Outcomes
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Reference Number** & **Laser Type** & **Investigation** & **Surface Characterization** \\ \hline  & & & (dentin) \\  & & & Same energy level, different frequency: \\  & & 5–15 Hz protrusion of peritubular dentin, \\  & & ichthyosis appearance, lamellar, irregular \\  & & surface, open denitinal tubules \\  & & 15 Hz single cracks \\  & & 20 Hz ichthyosis appearance, lamellar \\  & & surface, open channels, deeper cracks \\  & & 25 Hz larger cracks, blurred border \\  & & between channels, collapsed structure \\  & & 30 Hz disorganization of collagen \\  & & & fibers, carbonization \\ Wang [17] & & & \\  & & effect on dentin morphology, & Fixed frequency, different energy: \\  & & shear bond strength of composite & 50 mJ open dental tubules, irregular \\  & & resin to dentin & surface, no smear layer, protrusion of \\  & & & peritubular dentin \\  & & 100–200 ml open dental tubules, \\  & & irregular surface, no smear layer \\  & & 150 mJ single cracks \\  & & 200 mJ clear, deep cracks \\  & & 250 mJ smooth surface, blurred \\  & & boundaries between channels, larger \\  & & cracks, collapsed structure \\  & & 300 mJ collapsed structure, \\  & & disorganization of collagen fibers, signs \\  & & of carbonization \\ \hline  & & Er,Cr:YSG & 89 human teeth & (enamel) \\ [PERSON] [28] & 0.5 W, 20 Hz, 25 mJ, 8.84 J/ cm\({}^{2}\), 60 μs, & Rough irregular surface, cracks and \\  & 600 μm & enamel remineralization & craters, melted enamel \\ \hline  & & Er,Cr:YSCG & 60 human teeth & (enamel) \\ [PERSON] [29] & I: 0.25 W, 20 Hz, II: 0.50 W, & & Irregular surface, numerous conical \\  & 20 Hz, III: 0.75 W, 20 Hz. & Thermal effects on the pulp & The depth and number of craters increase \\  & & & as the laser power increases \\ \hline  & & & (enamel) \\ [PERSON] [33] & 200 μm, 15 μs, 100 mJ, 125 J/ cm\({}^{2}\), & & In the laser only group, melting of the enamel, irregular, wavy surface with no continuity, numerous cracks and pits No \\  & 10 Hz, 1 W & enamel remineralization & visible enamel prisms \\  & & & In the fluorine laser group, the surface is smoother and there are fewer cracks \\ \hline  & & Er:YAG & \\  & Group I: 0.40 W, 2 Hz, and 200 mJ & & \\  & Group II: 0.60 W, 3 Hz, and 200 mJ & & \\  & Group III: 2 W, 10 Hz, and 200 mJ & & \\ [PERSON] [18] & Group IV: 0.50 W, 2 Hz, and 250 mJ & 45 human teeth & (enamel) \\ [PERSON] [18] & Group V: 0.75 W, 3 Hz, and 250 mJ & & Appearance of a lava stream, more \\  & Group V: 0.75 W, 3 Hz, and 250 mJ & & irregular surface at 250 mJ than 200 mJ \\  & Group VI: 2.5 W, 10 Hz, and 250 mJ & & Cracks, no signs of enamel degradation \\  & Group VII: 0.60 W, 2 Hz, and 300 mJ & & \\  & Group VIII: 0.90 W, 3 Hz, and 300 mJ & & \\  & Group IX: 3 W, 10 Hz, and 300 mJ & & \\ \hline  & & & 54 human teeth & (enamel) \\ [PERSON] [19] & Er:YAG & effect on bacterial adhesion, effect & Rough, scaly surface with clearly defined \\  & 100, 7 Hz, 400 μs & on enamel morphology and & areas of smooth molten enamel No visible \\  & & bacterial adhesion & enamel prisms \\ \hline  & & & 36 human teeth & (dentin) \\ [PERSON] [20] & Er:YAG & effect on surface roughness, effect & Rough, crystalline surface \\  & & on dentin morphology & \\ \hline  & & & \\ [PERSON] [30] & Er:Cr:YSGG & 20 human teeth & (dentin) \\  & 3.5 W, 20 Hz & hybrid layer thickness & Wavy surface, few cracks, exposed \\  & & hybrid layer thickness & dental tubules, no smear layer \\ \hline \hline \end{tabular}
\end{table} 
Table 3: _Cont._