Development of a Novel Denture Adhesive Performance Test Model

Objectives: To develop an in vitro adhesive strength test model on a Texture Analyser imitating human mastication to determine the meaningful force required to separate two denture-like (PMMA) disc surfaces in the presence of a denture adhesive formulation, and give an indication of the clinical bite force.
Methods: The Instron Texture Analyser was equipped with an automated spray system to achieve controlled hydration of adhesives between the PMMA discs through intermittent spraying upon controlled dislodgement. The adhesives underwent 24 cycles of imitated chewing and relaxation between two PMMA discs with each cycle lasting approximately 2.5 minutes, and automated spraying of deionised water to imitate saliva flow.
The maximum force, time, compressive extension, cycle count, and loop count dislodgment values were obtained through the method created in the Bluehill software. This raw data was further analysed to determine Work of Adhesion and Adhesive Layer Thickness values to give an indication of the swelling/disintegration capabilities through changes in the adhesive layer thickness as well as the adhesive performance of a denture adhesive over time.
Seven denture adhesives previously tested in clinical studies were tested in the developed in vitro system(n=3);
The mean work of adhesion integral and the mean bite force data (collated from clinical reports) integral of the selected adhesives were calculated to plot a predictive model.
Results: A positive relationship was seen with the resultant graph, with a correlation coefficient, r = 0.97 (see Figure 1).
Conclusions: A robust in vitro model was developed which allows early indication of adhesive performance in bite force clinical studies.