Current status of whitening agents and enzymes in Dentistry

Abstract This study reviews the knowledge on the use of conventional dental whitening and the use of enzymes as a new approach in bleaching. A review of the literature was based on academic articles and on patents related to the use of enzymes in dental bleaching. Tooth whitening techniques used nowadays are well reported in the literature, and its mechanism of action consists of an oxidoreduction reaction with the release of free radicals. The great instability of radicals, when in contact with the tissues, promotes oxidation and reduction in the size of the pigment chains incorporated into them. These pigments are eventually broken down into smaller and smaller molecular chains and end up being diffused from the dental structure. In turn, the use of enzymes aimed at tooth whitening can be a less harmful alternative to the tooth because their specificity regarding the substrate makes them of great interest to perform specific reactions, reducing collateral effects. The use of proteolytic enzymes and oxidoreductases paired with the application of peroxides, can be a promising alternative for obtaining even better results in the dental bleaching process.

Isolation and screening of d-limonene-resistant microorganisms

This study reports the isolation of microorganisms that are resistant to environment containing limonene, the most important residue in the citrus industry. For the isolation, samples collected from strategic places of a citrus processing plant (yellow water, entrance and exit of the bagasse tank, effluent and deteriorated fruits found in bins, machine straps, fruit washers and plant floor), some citrus fruit and mint from local market were used. The samples were incubated in rotary shaker at 30°C/150rpm for 48h or 7 days in YM medium containing 0.1 percent limonene. Great part of the 112 strains recovered after 48h and the 126 strains recovered after 7 days were identified as Gram positive bacilli, followed by Gram negative bacilli, yeasts and Gram positive cocci, besides five fungi. About half of the Gram positive and Gram negative bacilli and yeasts and some Gram positive Cocci were resistant to limonene concentrations up to 2 percent in the medium broth. Amongst them seventy were able to grow in mineral medium containing limonene as sole carbon source. The research described in this paper is the initial step for the exploration of flavor compounds production via biotransformation of limonene, a non-expensive by-product of citrus industry.

Este estudo relata o isolamento de microrganismos resistentes a ambientes contendo limoneno, o mais importante resíduo da indústria citrícola. Para o isolamento, foram utilizadas amostras colhidas de pontos estratégicos de uma indústria processadora de laranja (água amarela, entrada e saída do tanque de bagaço, efluente e frutas deterioradas encontradas nos bins, nas correias dos equipamentos, nos lavadores e espalhadas pelo chão), além de frutas cítricas e hortelã adquiridas em mercado local. Cada amostra permaneceu incubada a 30°C/150 rpm por 48h ou 7 dias em meio YM contendo 0,1 por cento de limoneno. Dentre as 112 linhagens obtidas com 48h e as 126 com 7 dias, a grande maioria dos microorganismos isolados foram bacilos Gram positivos, seguidos por uma menor quantidade de bacilos Gram negativos, leveduras e cocos Gram positivos, além de cinco fungos. Cerca de metade das linhagens de bacilos Gram positivos e Gram negativos e de, leveduras e alguns de cocos Gram positivos resistiram à presença de até 2 por cento de limoneno, dentre as quais 70 foram capazes de sobreviver em ambientes contendo limoneno como única fonte de carbono. O trabalho descrito nesse artigo representa o primeiro passo no desenvolvimento de processos de produção de compostos de aroma pela biotransformação do limoneno.