The Effect of Fluence Variations of Nd:YAG Laser Ablation and Sample Condition on Human Tooth

Abstract

Nd:YAG laser has shown some potential to be used in dental practice replacing the conventional method. In particular, it can be used to modify the tooth surface by the ablation process. The laser provides an ability to accurately deliver a significant amount of energy into a confined region. Thus, alteration of the sample surface and composition may occur during the process. Additionally, the use of a laser in ablation procedure is also associated with heat generation and potential thermal injury that may be experienced by a patient. The wet condition of the samples is expected to reduce the thermal effect. In this paper, the changes of enamel surface and elemental composition following laser irradiation of Nd:YAG laser are discussed. The teeth samples were irradiated at 1.5 Hz of pulse rate, 100 ms of pulse width, and range of fluences of 80-120 J/cm 2. Field Emission Scanning Microscopy (FESEM) and Energy Dispersive X-ray (EDX) were used to analyze the morphology and composition of the teeth samples. Samples were compared before and after laser irradiation. The percentages of carbon increased after laser irradiation, while oxygen decreased for most of the samples. The morphologies of the samples were varied with a more pronounced effect on the sample surface at higher fluence. In addition, the effect of wet sample condition is also investigated and discussed. It is demonstrated that the ablation in wet condition produced less damage to the enamel surface compared to dry sample. However, no remarkable difference between the elemental composition of wet and dry samples.

Comparative Evaluation of Influence of Nd:YAG Laser (1064 nm) and 980 nm Diode Laser on Enamel around Orthodontic Brackets: An In Vitro Study

“…The statistical evaluation showed statistically significant differences in all four element contents before and after Nd:YAG laser irradiation. The results obtained for Section C (Nd:YAG) were in accordance with the results of other articles in the literature, which have obtained an increase in the hardness of the enamel after laser irradiation due to modification of the chemical elements in its structure [ 18 , 32 , 43 , 45 ].…”

“…This is made possible by altering the enamel crystalline structure. Also, low-level lasers (used alone or with topical fluoride) can lead to an increase in enamel resistance under an acid environment, as has been reported in the previous literature [ 23 , 32 , 34 , 37 , 38 , 39 ]. In other studies, nanoparticles were used in order to prevent bacterial adhesion and reduce enamel demineralization.…”

“…In the context of the shortcomings of fixed orthodontic treatments, in terms of the effects on enamel as well as the methods to prevent early demineralization (assisted or not by laser therapy), the aim of this study was to evaluate and compare the effects of two wavelengths on the enamel surface morphology and chemical composition of enamel adjacent to orthodontic brackets. For this study, we selected the 980 nm and 1064 nm wavelengths from considering reports from the literature with positive results in terms of increasing enamel resistance [ 18 , 32 , 33 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 ]. The assessment of enamel surface morphology before and after the experimental procedure and chemical composition analysis of the tested areas near the brackets were carried out through scanning electron microscopy and elemental analysis X-ray energy dispersive spectroscopy (EDX) using an FEI Quanta FEG 250 instrument (SEM-EDX, Type Quanta 250 FEG, Model No 1027641, FEI company, Brno, 62700, Czech Republic).…”

“…By observing this aspect, we can conclude that the concentration of calcium varies in a very insignificant manner on the enamel buccal surface. The reason for this could be due to the enamel’s thickness, the age of the patient at which the extraction was performed, their eating habits, and their level of oral hygiene [ 32 , 50 ]. Furthermore, the concentration of P wt% was almost the same for the control and the other two evaluated areas before laser irradiation, as can be seen in Table 1 and Table 2 .…”

“…Due to the storage conditions, sodium (Na) and chlorine (Cl) elements were detected during the elementary EDX analysis, which were not considered significant for the enamel structure during the evaluation data phase, and thus were not taken into consideration as they have no influence on the enamel microhardness. The weight percentages of Ca and P are considered to be very important in influencing the microhardness of the enamel, as many studies have shown previously [ 32 , 33 , 34 ].…”