Optic Observation about Effectiveness in Dental Plaque Reduction of Dextranase on Real Teeth

I Background

The purpose of this project is to alleviate the dental plaque that can be found on human teeth. Thus, the characterization of the enzyme effectiveness in realistic conditions from direct observation is necessary. We obtain several extracted teeth from a local hospital. All of the teeth are determined to have dental plaque coverage at similar levels. Python programs are used to provide quantitative analysis to the observational results we obtained from the experiment.

II Objective

By doing this experiment, we hope to find how effective the dextranase can alleviate the coverage of dental plaque on human teeth. By comparing the processed pictures specially characterized on the coloration region of the picture with a mathematical conversion, we are able to obtain a quantitative analysis to the effectiveness of the dextranase.

III Design & Procedure

1. Obtain teeth. We obtain teeth from a local hospital that conduct teeth extraction surgery. Every tooth is observed to have some dental plaque in some similar degrees.

2. Obtain dextranase from our engineered E. coli. We obtain dextranase from TOP10 strain E. coli following the standard procedures of cultivation and enzyme extraction methods

1.7ml -50mM-ph8.0-Tris-HCl Solution + Precipitation (17ml E. coli broth after centrifuging triple times).

After using Ultrasonication, dextranase solution and fracted cells are got. Then centrifuge solution for 10 min (25℃, 13000rpm).

(The Ultrasonication we used)

3. Take the teeth out of the hydrogen peroxide solution and divide them into three groups, standing for 0min, 10min and 40min after the introduction to dextranase.

4. As the pre-set time group, use the crude enzyme solution we obtained previously to cover up teeth inside 3 culture dishes

5. Use dental plaque chromogenic agent to color the dental plaque region.

6. Use optical camera to obtain the results

IV Result

Result Picture 1 - The Original Difference on Colored Region

Result Picture 2 - The Processed Gray Value Difference on Colored Region

There is an obvious decrease on the dental plaque, which is denoted by colored region, as the time passed on after the introduction to the dextranase.

During the 0 – 10min interval, the speed of differentiation seems to be the largest. And as the experiment continues, the effectiveness of dextranase on the dental plaque decrease.

Groups (Divide on time)	The Scope of Colored Region (Pixels)	The Darkness Level of Colored Region (Grey Value*3)
(1) 0 min introduced to Dextranase	14527	3637584
(2) 10 min introduced to Dextranase	4568	1179588
(3) 40 min introduced to Dextranase	4123	1042017

Result Picture 3 - Graphical Illustration on the Scope of Colored Region over Time

Result Picture 4 - Graphical Illustration on the Darkness Level of Colored Region over Time

V Conclusion & Implication

Basing on our experiment result, the experimental group shows significant effectiveness on the reduction of dental plaque in realistic conditions, we prove that our dextranase can degrade dextran on the surface of human teeth. Thus, we can conclude that our Dextranase is expressed successfully in the E. coli expression system, and has the ability to degrade the dextran and dental plaque structures on teeth surface. This experiment sets stage for our future experiment to establish production, in which we are not yet able to carry out experiment at present due to time table.