Comparative Evaluation of Laser Etching and Acid Etching: An in vitro Study

Abstract

Introduction: Recent innovations in bonding propose laser ablation as an alternative method to acid etching. Objectives: The objective of this study is to compare the effect of laser irradiation at medium-short pulse (MSP) mode, quantum-square pulse (QSP) mode, and acid etching on the shear bond strength (SBS) of orthodontic brackets to enamel. Materials and methods: Forty-two premolars were allocated to three groups (14 each): (1) 37% phosphoric acid etching; (2) erbium-doped yttrium aluminum garnet (Er:YAG) laser etching with MSP mode; (3) Er:YAG laser etching with quantum-square pulse mode. Metallic brackets were bonded with Transbond XT. After photo polymerization, the SBS values were recorded with universal testing machine. Surface morphology was evaluated with scanning electron microscopy (SEM). The remaining adhesive was assessed using adhesive remnant index (ARI). Results: Nonparametric test was used to analyze the statistical significance. A mean rank of 18.29 and 10.71 was obtained for QSP mode and acid etching with p = 0.015, 18.14; and 10.86 for MSP mode and acid etching with p = 0.019; and 14 and 15 for QSP mode and MSP mode with p = 0.748. Statistically significant difference was found between laser and acid-etched group. The SEM scan showed MSP mode with regular and uniform surface, like acid-etched sample, whereas QSP samples had irregular and severely rough surface. The ARI indicates that failure sites are mainly at the enamel/adhesive interface in the acid-etched and MSP mode group and at the bracket base/adhesive interface in QSP mode group. Conclusion: Laser etching in MSP mode is a successful alternative to acid etching, and provides a safer debonding of the brackets from the enamel surface without causing fractures.

Heavy Metal Bioaccumulation and Histopathological Studies of Fish Tissues from Ose River, Ondo State, Nigeria

“…Cadmium according to [39] was reported to be an impurity in zinc as it is usually found around zinc ores. In addition, Cd is referred to as a toxic trace metal and may be found in some rocks, fertilizers, galvanized plumbing, industrial waste, coal, and petroleum [40]. Though no past or recent studies have revealed any valuable benefit of Cd, most of the previous studies have revealed negative effects of the metals.…”

Bioaccumulation of Heavy Metals in Pelagic and Benthic Fishes of Ogbese River, Ondo State, South-Western Nigeria

“…This result is similar to the study of Vardi and Chenji (2020) who reported high concentrations of Cd in India. Cadmium is usually grouped as a toxic trace element, found in low concentration in rocks, coal, and petroleum and sometimes combines with Zn (Sobha et al 2016). However, no previous study has shown any beneficial values of Cd.…”