ABSTRACT
We propose a novel, to the best of our knowledge, super-resolution technique, namely saturable absorption assisted nonlinear structured illumination microscopy (SAN-SIM), by exploring the saturable absorption property of a material. In the proposed technique, the incident sinusoidal excitation is converted into a nonlinear illumination by propagating through a saturable absorbing material. The effective nonlinear illumination possesses higher harmonics which multiply fold high frequency components within the passband and hence offers more than two-fold resolution improvement over the diffraction limit. The theoretical background of the technique is presented, supported by the numerical results. The simulation is performed for both symmetric as well as random samples where the raw moiré frames are processed through a blind reconstruction approach developed for the nonlinear SIM. The results demonstrate the super-resolution capability of the proposed technique.
ABSTRACT
OBJECTIVE: The objective of this study is to evaluate and compare surgical stripping and neodymium-doped: yttrium, aluminum garnet (Nd:YAG) laser techniques for gingival depigmentation and to evaluate their effect on repigmentation. BACKGROUND DATA: Gingival depigmentation is often associated with repigmentation. Recurrence of pigmentation differs according to different treatment modalities. MATERIALS AND METHODS: In this study, 40 maxillary sites from 20 patients presenting bilateral melanin gingival hyperpigmentation were selected. Contralateral quadrants in the maxilla were randomly assigned to receive Nd:YAG laser at 3 W, 30 mJ per pulse, with contact mode, and with a handpiece with a 300 µm diameter optic fiber and surgical stripping. Plaque index, Dummett Oral Pigmentation Index (DOPI), Hedin melanin index, size of pigmented area, time interval and extent of repigmentation, time taken for each of the procedures, assessment of pain, intraoperative bleeding index, and patient preference were compared from baseline to 6 months. RESULTS: Comparison between Nd:YAG laser and surgical stripping group for plaque index, DOPI, Hedin index, size of pigmented area, time interval, and extent of repigmentation, at 6 months was statistically nonsignificant. Intergroup comparison for time taken, pain, and patient preference was statistically significant. Intragroup comparison for Nd:YAG laser and surgical stripping at 6 months for DOPI, Hedin index, and size of pigmented area was statistically significant. CONCLUSIONS: From the present study it can be concluded that Nd:YAG laser can be used as an alternative technique for gingival depigmentation. However, surgical stripping continues to remain as a cost-effective procedure.