Workshop 2 Odor measurements using instruments and other laboratory tests (GC, GCMS, Halimeter, Sensors, HPLC, OK2KISS, BANA etc)

ADA guidelines stipulate that organoleptic/hedonic odour judges are the ‘Gold Standard’ whereas instrumental (e.g. gas chromatography) and microbiological analyses of oral malodour are considered secondary tests. 1. Why is instrumental measurement considered 2 nd best to odour judges? Comments of the participants included:•  Human judges are more commonly used. Gas chromatography (GC) is used to measure volatile sulphur compounds (VSCs), which are only part of the total breath mix. •  To what extent do VSCs contribute to breath odour? They correlate with odour scores but are not the only odour in breath. •  First, define other odorants in breath to produce simulated mixtures then compare these mixes to the real thing. •  There are probably different types of bad breath from different locations within the oral cavity. •  Methyl mercaptan is important, in determining the source of oral malodour. •  Butyric acid is odorous and present at high levels in saliva but does not play as important a role in breath odour. •  It is generally accepted that instrumental measures are not advanced or sophisticated enough to measure oral malodour. •  However, judges are subjective and there is a real need for ‘equipment’ that can be taken into the field. •  An inventory of the chemical constituents of bad breath must be completed because VSCs are not the only important component they are just the ‘easy’ route to measuring bad breath. Indole, skatole, butyric acid: Are they important? •  Use GC‐MS and profile the breath of 1000 patients. This is not necessarily straightforward because it is possible to introduce false positive results by concentrating breath samples. •  Often, breath odour treatments can reduce the concentration of VSCs measured in a patients breath but the patient still has oral odour suggesting that other components are important. •  VSC levels in breath can be elevated by cysteine challenges, what components in breath are elevated after challenging with other amino acids? •  Microbiological techniques show increased numbers of Streptococcus salivarius in patients without oral odour, could this be the emergence of the ‘good guy’? •  There have been no long term microbiological studies looking at ecology shifts in patients with and without oral malodour. •  Would long term microbiological studies provide useful information given that many species in the oral cavity are non‐culturable and many are unknown? •  J. Tonzetich examined different components of oral malodour before he focused on the GC measurement of VSCs. •  The Halimeter ® has been demonstrated to have a correlation of about 0.5 with odour scores. •  BANA (benzoyl‐ dl ‐arginine‐napthyamide) and other enzymatic test have been shown to correlate with odour scores. •  Correlations between odour judges and other techniques for assessing oral malodour do vary and this depends on the number of odour judges used. •  Quest International has designed a screening system to find flavour components that specifically eliminate VSCs. Reducing VSCs results in reduced odour in most subjects but there will always be exceptions. •  There are still studies that show the opposite effects for VSC and odour scores. •  Concentrated whole breath should be assessed – although alkanes have been shown to be present in oral odour, the odour index of alkanes is low. •  Do researchers actually look for other molecules in oral odour, other than VSCs? •  Colgate measure VSCs but are moving into the measurement of volatile fatty acids, indoles and amines using SPME. •  GC is a good predictor for the activity of potential odour reducing products. The hierarchical testing procedure for new products is usually as follows: in vitro to Halimeter to GC to organoleptic/hedonic odour assessments. •  What is the cost of using odour judges? Studies using odour judges are expensive, certainly more costly that using instrumental measures, and this could cause problems for smaller companies who do not have sufficient funding. 2. Will there be a day when an analytical measure is the ‘gold standard’ for assessing oral odour? •  Can we produce bad breath in a bottle? •  There is a difference between chronic and morning breath. The industry is geared towards treatment of morning breath. Do such treatments work for sufferers of chronic bad breath? •  There is no information correlating morning breath with mid‐afternoon breath. •  How important will bacterial tests become? Have bacterial tests such as BANA been used in the professional field? •  Industry is driving the use of the Halimeter ® . Maybe the BANA test should be marketed similarly to the Halimeter ® . •  The BANA test needs money and marketing, as does the OK to KISS test. •  Is it possible to test odour treatments on bacteria, where the measurable end product is gaseous headspace? Caution must be exercised since bacterial metabolism will be effected by culturing conditions. •  Some microorganisms have been associated with oral odour, such as Porphyromonas gingivalis , Prevotella intermedius , however the problem is that a large percentage of the oral flora is non‐culturable. •  What is the importance of postnasal drip in oral odour? •  How does tongue cleaning effect oral odour? •  Can amino acid mapping in the oral cavity be correlated with oral odour? (e.g. measuring the concentrations of methionine, cysteine, tryptophan at different locations in the mouth). 3. Will there ever be a ‘gizmo’ to measure oral odour with a 0.9 correlation with odour judges? •  Is this the promise of the electronic nose? Current problems with the electronic nose include moisture and must choose the right sensors. A researcher from University of Manchester Institute of Technology (UMIST) working with the electronic nose forecast that the technology would be ready by 2008!General concensus •  Odour judges ‘measure’ whole breath odour, which is why they are considered the gold standard measure of oral odour. However research has shown that the human nose exhibits a Log response to stimuli but the scales used to rate oral odour are linear and that there is no pan‐industry standard for this measurement, in terms of calibration of judges. •  VSCs are important components of oral odour and GC is the most accurate method of measuring VSCs in breath. Therefore the GC is the ‘gold standard’ for measuring VSCs. •  Portable VSC measures include the Halimeter and portable GC (requires validation). Other measures include enzymatic tests and microbiological measures. Performing all these measures in combination should give better correlations with odour judge scores. •  Research should be performed in the following areas: Detecting the component gases in oral odour. Defining ‘bad breath in a bottle’ and olfactory thresholds. Measuring oral odour substrates/substrate availability.Suggestion for next ISBOR meeting  Gather odour judges from research and industry and have them assess a cross‐section of oral odour patients, in parallel with the instrumental measurement of odour.