Comparison of smartphone‐camera and conventional flatbed scanner images for analytical evaluation of chewing function

Abstract

Background: The two-colour mixing test is a quick method to assess chewing function (CF). The use of smartphone cameras for acquiring images may help in further simplifying the process. Objective: This study evaluated the reliability of smartphone-camera images of chewing gums to assess CF. Methods: Five test samples of a bicoloured chewing gum were produced by a single fully dentate adult volunteer. The specimens were flattened to 1-mm thick wafers. The two sides of the wafers were digitised with a conventional flatbed scanner (control) and were photographed 20 times using 8 different smartphones. The images were assessed optoelectronically to obtain the variance of hue (VoH) and subjectively by visual assessment (SA) using a categorical scale (SA1-SA5). Spearman's correlation and regression models were used for statistical analyses. Results: The intra-group variability for SA1-SA3 was <1% for all smartphones, but significantly higher than controls for SA4 and SA5 (smartphone: SA4 = 5.57%; SA5 = 8.76%; control: SA4 = 2.5%; SA5 = 0.79%). VoH was progressively lower from SA1 to SA5 for all imaging devices (r > −.97; P < .001). VoH comparisons between control and smartphone images revealed significant differences for the individual SA categories, and however, the magnitude of differences was small and non-significant when the full range of SA levels were considered. The linear mixed model regression showed significant effects for all the smartphones (P < .001) and SA levels (P < .001) in relation to the flatbed scanner values. Conclusions: Smartphone cameras may be used to evaluate colour mixture for a bolus-kneading test, however, the precision is lower with higher degrees of colour mixing.

Assessing masticatory performance with a colour‐mixing ability test using smartphone camera images

“…Individually, higher mixed chewed gums were evaluated with higher SA scores, whereas in comparison less mixed chewed gums were evaluated more similar. Therefore, the results of this study are similar to the findings of the study from Fankhauser et al (2020) 29 . Pictures from mobile phones were scored not very reliably, and clinicians should be aware that deviations are possible.…”

“…It is possible that the non‐standardised recording by the phones changed the image quality for example due to blurring, camera moving or missed focus. With the scanner, images could always be taken with same lightning and quality and similar findings were also made in a previous study 29 . However, digitising wafers using a flatbed scanner is time‐consuming, and therefore, hardly conceivable in nursing home routines.…”

“…Previous studies showed good agreement between a standard flatbed scanner and mobile phone 19,29 . However, these studies used standardised positions of capturing the wafers.…”

The Effect of a Masticatory Muscle Training Program on Chewing Efficiency and Bite Force in People with Dementia

“…Alternatively, it is possible to evaluate the color mixture using a smartphone camera. However, higher degrees of color mixing result in a lower precision [ 115 ].…”

Consensus on the terminologies and methodologies for masticatory assessment

“…The various opto‐electronic assessment tools are often applied in research; however, the methods mostly need only a flatbed scanner and a computer for evaluation. First attempts for evaluation of the colour mixture with a smartphone application have been successful and will surely allow for further technical simplification in the near future 63,73 …”