Veterinary Oral Health Council

VOHC Digital Scoring Project

Prepared by VOHC Director Colin Harvey

April 2019 Update:

The Summary of the November 2018 VOHC Update presentation and subsequent discussion in Phoenix is available HERE. The next steps in the QLF scoring development outlined in that file are now underway.

I will be meeting with Elbert Waller (Inspektor Research – the QLF camera and software company) at Inspektor Research in Amsterdam on May 14 and 15 to go over the software changes that Inspektor is working on.

The European Veterinary Dental Forum meeting in Utrecht includes a formal VOHC Update presentation at 15.10 on Friday May 17. This will include a demonstration of the QLF software that will have been updated to include extent of coverage and thickness of coverage in a single plaque score and a single calculus score. This session can also be used for discussion of other items relevant to VOHC. Additional time will be made available for further discussion.

If you will be at the Utrecht Forum meeting, and would like to get together for informal discussion of VOHC issues in addition to or separate from the Friday afternoon VOHC Update session, possibilities are following the Thursday evening welcome reception, for drinks or dessert somewhere, or lunch-time on Friday or Saturday. I will be staying over on Saturday night, so if you are interested and available, dinner on Saturday would be another possibility. Please let me know ahead of time if you would like to meet with me. The website for the Utrecht meeting is

April 2018 Update:

Next Scoring Project Session: Friday, June 2, 12.30 hours, Eurpean Veterinary Dental Forum, Innsbruck, Austria. The four primary items for presentation/discussion at that session are:

1. Incorporation of thickness into the plaque and calculus QLF indices, based on differences in intensity of fluorescence from pixel to pixel, so that an extent of coverage-thickness combined score can be generated for each target tooth. Plaque and calculus would be scored separately, by scoring plaque and then brushing the tooth surface before taking a second QLF image that would be scored as calculus. One critical aspect for VOHC will be coming up with a mechanism for calculating a score for statistical analysis, which will require defining a maximum (for a tooth completely covered by maximum thickness of plaque or calculus).

2. Whether to use a disclosing solution. Disclosed and non-disclosed teeth will produce readable QLF images, with plaque identified on non-disclosed teeth representing more mature plaque. Examples of the difference between QLF scores of plaque on the same tooth, non-disclosed or disclosed, will be presented. They are significant, with implications for the VOHC effectiveness standard. A decision will need to be made as to which to score (disclosed vs non-disclosed images) for VOHC trials. Click here to see data comparing QLF analyses of the same tooth before and after applying a disclosing solution in dogs and cats (data provided courtesy of Waltham/MARSPetcare).

3. Discussion of who owns the ‘intellectual property’ that is incorporated into a final version of ‘VOHC Digital Plaque and Calculus Scores’. I am pursuing completion of this project in the expectation that an agreed-on VOHC Digital QLF Scoring System will be able to be used by any company without limitations to protect intellectual property rights.

4. Confirmation of selection of specific tooth sets to be used for VOHC QLF digital scores. Correlation coefficient analyses comparing QLF data were presented at the Nashville Forum in September 2018. A unilateral set is included to make it practical to use split-mouth trials for some product types.

The 12.30 VOHC Digital Scoring session in Innsbruck is scheduled immediately before the 13.00 hours lunch break, so there will be opportunity to continue informal discussion at the end of the scheduled session. If you or a representative of your company will not be able to attend the Innsbruck Forum, and you would like to have your comments and suggestions included in the presentation/discussion, please send you comments to me by mid-May.

General Description of the Scope of this Project

The plaque and calculus scoring systems currently used in VOHC trials in dogs and cats are subjective and categorical in nature. This has resulted in extensive discussion at recent Veterinary Dental Forum meetings, resulting in recognition of the shortcomings of current scoring methods, particularly given the irregular shapes and wide range in sizes of canine and feline teeth. Reports of these meetings and copies of the Powerpoint files used in the presentations are available via the links below. The available files include background information on scoring in VOHC trials and a brief history of digital scoring techniques.

There was agreement at the Minneapolis Forum in 2016 that recent work on digital scoring of plaque in dogs and cats conducted at the Waltham Center for Pet Nutrition, UK (hereafter 'Waltham'), provided a model for scoring for VOHC trials that was worth investigating.

The method used at Waltham is based on the Quantitative Light-induced Fluorescence (QLF) equipment and technology developed by Inspektor Research Systems, The Netherlands. The Inspektor website includes a comprehensive set of resources, including a downloadable White Paper on QLF and an extensive list of Literature available as links from the webpage.

Individuals, companies and organizations known to Colin Harvey as being potentially interested in development of an objective veterinary dental scoring system for VOHC purposes were invited to be part of a collaborative project to further investigate the QLF system. The participant list now includes about 90 individuals. If you are not a member of this group and are interested in this topic, you are welcome to join - send an email note to, briefly describing your background and reason for interest in this topic. Individuals are welcome to participate anonymously (group email messages will be sent to you as bcc:). As part of this outreach effort, interested individuals were asked whether they were aware of alternative objective plaque and calculus scoring methodologies in use or in development; none with any likelihood of development into a practical system have been mentioned to date.

VOHC Scoring Project PowerPoint presentations at recent Veterinary Dental Forum meetings:

Phoenix North American Forum PowerPoint file, 2018.

Dublin European Forum PowerPoint file, 2016.

Minneapolis North American Forum PowerPoint file, 2016.

Malaga European Forum PowerPoint file, 2017.

Nashville North American Forum PowerPoint file 2017.

Reports of the following Forum meetings and additional updates are also available:

Phoenix Forum meeting report, November 2018.

January 2017 Email Update.

February 2017 correspondence with Inspektor Research Systems.

April 7, 2017 Email Project Update note

Malaga and Waltham May 2017 meeting reports

Nashville North American Forum meeting report, 2017.

As a result of the research conducted at Waltham, Waltham has applied for a patent on certain aspects of digital scoring of dental plaque in dogs and cats. Click Patent to download a copy of the patent application. Corrin Wallis and colleagues at Waltham have proven to be very willing to collaborate, and have provided much very useful information, which we hope will prevent un-necessary repetitive effort.

In 2016, Dr. Wallis and colleagues at Waltham published their work on scoring plaque in dogs using the QLF technology. Click QLF Plaque Scoring in Dogs to download a copy of the published paper. A similar publication is now available on use of QLF to measure extent of plaque in cats. VOHC has now approved use of the Waltham adaptation of the QLF scoring technique in both dogs and cats for VOHC trials.

Another research group has investigated computer modeling in scoring of dental plaque in canine teeth. Click Plaque Computer Modeling to download the paper in the 2015 IEEE Journal of Biomedical and Health Informatics.

To date, Waltham has concentrated on using QLF to score the extent of plaque coverage, and has conducted some preliminary work on extent of calculus. Discussions are now considering a new phase, desgned to determine whether the QLF technology can be broadened to include measurement of thickness of plaque or calculus.

Inspektor Research Systems has participated in these discussions. Futher discussions with Waltham and Inspektor will be held late in 2017. Once an estimate of cost of required next steps is available, the members of the VOHC Scoring Project group will be contacted to investigate options for raising funds to cover the cost. The AVDC Board has agreed to include funds in the VOHC budget as a start-up resource for any required funding.

Additional Resources:

Using tooth-weighted data to score gingivitis and attachment loss in dogs.

Sub-sets of teeth of dogs in which scores of gingivitis and attachment loss correlate highly with full-mouth tooth scores.

Historical Items:

Here are some historical articles on scoring, to provide perspective for this project.....

Ramfjord Index An early attempt at comprehensive scoring of periodontal disease factors.

Volpe-Manhold Calculus Index The classic calculus index.

Relationship between calculus and plaque An early attempt at comprehensive scoring of periodontal disease factors.

Correlation of weight of calculus with V-M Calculus Index scores The definitive method of scoring calculus.


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