Oral analysis device

An optical analysis method,

• wherein the method comprises control of a multi-frequency optical measurement apparatus comprising a light generator and a light detector, the light generator for irradiating a tooth surface with light during use, and the light detector for detecting a reflection of the light from the tooth surface during use,
• wherein the light generator is operable to selectively generate a light output within each of a plurality of different wavelength bands, and/or the light detector is operable to differentially detect light at each of a plurality of wavelength bands;
• the method comprising:
• controlling the optical measurement apparatus to acquire a non-fluorescent diffuse reflection intensity measurements diffuse reflection spectroscopic measurement set comprising at least two diffuse reflection intensity measurements at two different and non-overlapping wavelength sub-bands, each sub-band within the range 550 and 650 nm;
• computing a characteristic value from the at least two diffuse reflection intensity measurements, wherein the characteristic value is proportional to either a difference between the at least two diffuse reflection intensity measurements, or a ratio of the at least two diffuse reflection intensity measurements, whereby the characteristic value provides a direct or indirect indicator of a sign of a slope of a reflection spectrum of the sampled surface between the respective wavelengths of the at least two measurements;
• determining a classification of healthy enamel vs unhealthy enamel based on the characteristic value;
• and
• generating an output indicative of the classification.