Application Note | Consumer Product Tribology
Tribology Study of Dental Dog Treats
How Surface Texture Drives the Cleaning Friction of Dental Chews
Research & Experimental Testing
Duanjie Li
Visual Design & Editorial
Andrew Shore
Introduction
Oral and dental hygiene is an often-overlooked but vital factor in the dog’s overall health. Proper dental cleaning ensures clean teeth, freshened breath and prevention of plaque and tartar. A variety of measures have been applied to clean dog’s teeth, such as routine brushings, food selection, dental treats and oral rinse aids. There are several factors to consider in order to find the right products, including the dog size, temperament, tooth health condition, etc.
Importance of Friction Evaluation for Dog Dental Treats
Flavored dental treats have been demonstrated as an effective, comfortable and easy to use method for dog dental cleaning. The flavorful and chewy dental treats make teeth and gums cleaning an enjoyable procedure. During the chewing mechanical actions, the dental treat creates friction against the surface of the teeth to remove tartar and bacteria films. A reliable friction measurement is needed to quantitatively compare the effectiveness of dog dental treats of different surface texture and roughness, and to provide insight of the correlation of the surface roughness, texture and friction to facilitate the R&D and quality control of the dental treat production.
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Measurement Objective
In this study, we compared the frictional behaviors of dog dental treats with different surface texture and roughness to showcase the capacity of the NANOVEA Tribometer in providing quantitative friction measurement in a controlled and monitored manner.
NANOVEA T2000 High Load
Pneumatic Tribometer
Test Procedure
The coefficient of friction, COF of two dog dental chews samples made by different processes were evaluated by the NANOVEA Tribometer using the Linear Reciprocating Wear Module. A Steel 440 ball (6 mm diameter) was used as the counter material. The surface roughness of the samples was examined using a NANOVEA 3D non-contact profilometer. The test parameters are summarized in Table 1.
Please note that a smooth Steel 440 ball as a counter material was used as an example in this study, any solid material with different shapes and surface finish can be applied using custom fixture to simulate the actual application situation. Such tests can also be performed in the liquid environment to simulate the presence of saliva during the chewing process.
| Test parameter | Value |
|---|---|
| Load | 1 N |
| Duration of test | 20 min |
| Speed rate | 100 cycles/min |
| Length | 5 mm |
| Number of cycles | 2000 |
| Ball diameter | 6 mm |
| Ball material | SS440 |
| Atmosphere | Air |
| Temperature | 24 °C (room) |
| Humidity | 40% |
Table 1: Test parameters of the measurements.
Results and Discussion
The 3D view, false color view and roughness analysis of the two dog dental treat samples are compared in Fig. 2. The 3D View images provide users a straightforward tool to directly observe the morphology of the surface from different angles. The 2D profiles in Fig. 3 extracted from the 3D topography image provide more information of the peak and valley features of the samples.
Sample 1 shows a rougher surface of a Sa value of 11.1 μm, compared to 8.33 μm for Sample 2, according to the surface topography analysis by the NANOVEA 3D non-contact profilometer. The rough surface may increase the surface area in contact with the saliva during the chewing process, accelerate the release of the flavor and improve digestibility of the treats.
| ISO 25178 parameter | Sample 1 | Sample 2 |
|---|---|---|
| Sa (µm) | 11.1 | 8.33 |
| Sq (µm) | 13.7 | 11.1 |
| Sp (µm) | 35.9 | 57.0 |
| Sv (µm) | 53.5 | 47.3 |
| Sz (µm) | 89.5 | 104 |
| Ssk | −0.567 | 0.622 |
| Sku | 3.18 | 4.48 |
Table 2: Surface roughness of the dog dental chew samples (from Fig. 2).
Fig. 4 compares the evolution of the coefficient of friction, COF of the samples during the reciprocating wear measurement. The linear reciprocating wear test setup is used here to simulate the back-and-forth chewing motion at the contact of the teeth against the dental treats. Sample 1 exhibits a higher friction throughout the test, resulting in an average COF of ~0.182, compared to a COF of ~0.081 for Sample 2. Such a difference in the COF of the two samples may lead to their different dental cleaning performance. The higher friction of Sample 1 provides better friction to effectively remove tartar and bacteria films on the teeth and gums during the chewing process.
Conclusion
In this study, we showcased the capacity of the NANOVEA Profiler and Tribometer in evaluating the surface roughness and coefficient of friction of the dog dental chews samples in a well-controlled and quantitative manner. The surface texture plays a critical role in the friction of the chews against the dog teeth, providing sufficient frictional force to remove tartar and bacteria films on the tooth surface. Oral hygiene is an often-overlooked but important factor in the dog’s overall health. A better understanding of the surface texture and friction during the chewing mechanical actions enables R&D of high-quality dental dog treats.
The NANOVEA Tribometer offers precise and repeatable wear and friction testing using ISO and ASTM compliant rotative and linear modes, with optional high temperature wear, lubrication and tribo-corrosion modules available in one pre-integrated system. NANOVEA’s unmatched range is an ideal solution for determining the full range of tribological properties of thin or thick, soft or hard coatings, films and substrates.
Frequently Asked Questions About Dental Treat Friction Testing
Why measure the friction of dental dog treats?
While chewing, the treat rubs against the teeth to remove tartar and bacteria films. A reliable friction measurement compares treats of different texture and roughness quantitatively, supporting R&D and quality control.
How was chewing simulated?
A linear reciprocating test, 5 mm strokes at 100 cycles/min for 2000 cycles under 1 N, reproduces the back-and-forth contact of teeth against the treat; a 6 mm SS440 ball served as the counter surface.
How rough were the two chews?
Sample 1 had an Sa of 11.1 µm and Sample 2 8.33 µm, measured with a NANOVEA 3D non-contact profilometer.
Which chew produced more friction?
Sample 1, with an average COF of about 0.182 throughout the test, against about 0.081 for Sample 2.
Can real teeth or saliva be simulated?
Yes. Any solid counter material with different shapes and surface finish can be mounted with a custom fixture, and tests can run in liquid to simulate saliva during chewing.
Which instruments were used?
The NANOVEA Tribometer with its linear reciprocating wear module, and a NANOVEA 3D non-contact profilometer for roughness.
