Effect of commercially available and experimental potassium oxalate-based dentin desensitizing agents in dentin permeability: influence of time and filtration system

Abstract

This study evaluated the influence of time after application of oxalate solutions in reducing dentin hydraulic conductance. Fifty dentin discs were obtained from extracted human third molars and assigned to 5 groups (n=10), according to the desensitizing agent used: Group I: OxaGel; Group II: experimental agent DD-1: Group III: experimental agent DD-2. In Groups IV and V, a placebo gel and deionized water were used as control, respectively. The agents were applied for 3 min, washed out and the hydraulic conductance was measured immediately and at 5-, 15-and 30-min intervals, and after acid etching. Data were analyzed statistically by two-way ANOVA and Duncan's test at 5% significance level. Groups I, II and III did not differ significantly from each other in any of the time intervals (p>0.05). Likewise, Groups IV and V were statistically similar to each other (p>0.05). The active agents reduced significantly dentin permeability in comparison to control groups (p<0.05). Dentin permeability measured in vitro decreased significantly with time regardless of the agent applied (either active or control agents). The results of Group V, in which no dentin desensitizing agent was employed, indicates that the assessment of dentin permeability by this method must be interpreted with caution.

Dentin hypersensitivity after treatment with desensitizing agents: a randomized, double-blind, split-mouth clinical trial

“…Greenhill and Pashley (17) reported that 30% potassium oxalate reduced dentin permeability by 98% in vitro. Another study (12) found that various potassium oxalate formulations decreased dentin permeability by approximately 75%, indicating the effectiveness of these products. Laboratory tests of desensitizing agents are conducted to evaluate their effectiveness or to predict their clinical performance.…”

“…This mechanism explains why desensitizing agents usually act in short-and longterm bases (11,12). Calcium chloride and potassium phosphate solutions have been tested in vitro (13,14) and in vivo (15), and may work similarly.…”

Análise quantitativa e qualitativa da condutividade hidráulica da dentina após tratamento com diferentes agentes dessensibilizantes. Estudo in vitro

“…Para os estudos de condutividade hidráulica, dois métodos de preparação de espécimes são possíveis. Um deles preconiza o uso de discos de dentina (KOLKER et al, 2002;PEREIRA;SEGALA;GILLAM, 2005;PEREIRA;MARTINELI, 2006;KOMABAYASHI et al, 2010) e o outro utiliza segmentos de coroas (DE ANDRADE E SILVA et al, 2007;DE ANDRADE E SILVA et al, 2009;RUSIN et al, 2010). Pashley (1986) afirma que os discos de dentina são mais utilizados nesses estudos devido à facilidade de manuseio e um bom acabamento dos espécimes, uniformidade de espessura, além de possibilitarem a delimitação da área de superfície a ser testada através do uso de uma câmara de filtração.…”

“…Como o dispositivo apresenta seus componentes interligados, o deslocamento linear realizado pela microbolha é convertido em deslocamento de volume através do disco de dentina, em função do tempo (KOLKER et al, 2002;PEREIRA;SEGALA;GILLAM, 2005;PEREIRA;MARTINELI, 2006).…”

“…Diante de todas essas dificuldades, vários estudos in vitro ainda continuam sendo realizados com pressões semelhantes à empregada no presente trabalho (KOLKER et al, 2002;PEREIRA;SEGALA;GILLAM, 2005;PEREIRA;MARTINELI, 2006;SUGE et al, 2008;KOMABAYASHI et al, 2010). Por outro lado, um aspecto bastante positivo desse tipo de ensaio, independentemente da pressão empregada, da consistência da smear layer e do grau de desmineralização para a medição da PMax, é que cada espécime é controle de si mesmo, posto que os testes de condutividade hidráulica pré e pós-tratamento são feitos no mesmo disco.…”