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Chapter 2: Problem 50

The article "A Debate in the Dentist's Chair" (San Luis Obispo Tribune, January 28,2000 ) described an ongoing debate over whether newer resin fillings are a better alternative to the more traditional silver amalgam fillings. Because amalgam fillings contain mercury, there is concern that they could be mildly toxic and prove to be a health risk to those with some types of immune and kidney disorders. One experiment described in the article used sheep as subjects and reported that sheep treated with amalgam fillings had impaired kidney function. a. In the experiment, a control group of sheep that received no fillings was used but there was no placebo group. Explain why it is not necessary to have a placebo group in this experiment. b. The experiment compared only an amalgam filling treatment group to a control group. What would be the benefit of also including a resin filling treatment group in the experiment? c. Why do you think the experimenters used sheep rather than human subjects?

Short Answer

Expert verified
a. It's not necessary to have a placebo group in this experiment because the effect of believing in having fillings on kidney function is likely irrelevant. b. A resin fillings group would provide a comparison to understand the impact of different types of fillings on kidney function. c. Sheep might have been used instead of humans due to ethical considerations (avoiding potential harm to humans) and possibly due to similarities in their dental and kidney structure/function to humans.

Step by step solution

01

Understanding Control and Placebo Groups

A control group is a group in an experiment that does not receive the treatment or intervention and is used as a benchmark to measure how the other tested subjects do. A placebo group, on the other hand, is a subset of a control group that receives a sham 'placebo' treatment which is designed to mimic all aspects of the actual treatment without including the therapeutic element. The purpose of a placebo group is to account for the placebo effect, in which participants experience changes simply because they believe they are receiving treatment. In this case, it's not necessary to have a placebo group because the impact of the 'belief' of having fillings on the kidney function is likely non-existent.
02

The Benefit of Including a Resin Filling Treatment Group

Adding a resin filling group to the experiment would provide a comparison to understand the effects of different types of fillings (amalgam fillings versus resin fillings) on kidney function. If the sheep with resin fillings showed less kidney impairment than those with amalgam fillings, it could suggest that the mercury in the amalgam fillings is contributing to the kidney impairment.
03

Reason for Using Sheep Instead of Human

There could be several reasons why they chose sheep instead human subjects. Firstly, it's an ethical issue: exposing human beings to potential harm (mercury in this case) is not ethical. Animal testing allows researchers to explore the effects of the fillings without causing potential harm to humans. Then, sheep might have a similar dental and kidney structure/function to humans, making them a suitable model organism for this study.

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Most popular questions from this chapter

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