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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?

Step by step solution

01

Answer to part a

In this experiment, a control group, receiving no treatment, is already serving the role of a placebo. A placebo group might be used as a control in a blind experiment where subjects do not know whether they are receiving an active treatment or not, to account for possible psychological impacts of receiving treatment. But in this case, the subjects are sheep and the expected psychological effects are non-existent. Therefore, the control group is enough for comparison with the treatment group to examine any effects from the amalgam fillings.

02

Answer to part b

Adding a resin filling treatment group would provide comparative data between three groups - no treatment, amalgam filling, and resin filling. The results thus obtained can offer a clearer understanding of the level of kidney impairment (if any) caused by each material and aid in validating the safe use of resin fillings. This could be particularly important in driving the ongoing debate of resin fillings being a superior alternative to amalgam fillings.

03

Answer to part c

The use of sheep instead of human subjects could be due to ethical considerations. It would be unethical to knowingly expose human subjects to a possible toxic material, potentially damaging their health. Additionally, the use of sheep allows for a controlled environment, where variables like diet, activity, etc., can be monitored and kept constant, reducing unforeseen effects. Sheep kidneys are similar in function to human kidneys making them good models for such a study.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Control Group

The concept of a control group is pivotal in any scientific experiment, as it establishes a baseline for comparison. In the sheep study regarding dental fillings, the control group consisted of sheep that did not receive any fillings. This group helps researchers understand what changes occur due to the treatment and what changes are independent of the treatment. Since the control group undergoes no specific treatment procedures, any deviation in their biological functioning is considered a natural variation. This control group plays a similar role to a placebo group but does not require deception, as sheep are unlikely to experience placebo effects.

• Establishes a baseline without treatment
• Helps identify treatment effects by comparison
• Prevents external influences from affecting study outcomes

Treatment Group

The treatment group in an experiment receives the specific condition or treatment being tested. In the discussed study, the treatment group consisted of sheep with amalgam fillings. By doing so, researchers can specifically observe any health impacts, such as kidney function impairment, attributable to the amalgam fillings. Comparing the treatment group to the control group reveals critical information about the effects of the treatment. But the study's design can improve with a resin filling treatment group for additional comparative data across different treatment methods.

• Involves subjects receiving the variable being tested
• Allows thorough examination of the treatment impact
• Key to identifying the specific effects of experimental material

Placebo Effect

A placebo effect occurs when participants experience a change merely because they believe they are receiving treatment. However, in experiments involving animals like sheep, this effect is irrelevant. Animals cannot perceive or have expectations about their treatment, making a placebo group unnecessary in this context. This absence minimizes complications related to psychological biases, focusing solely on the physiological outcomes due to treatment. The control group already fulfills the role of comparison effectively in such animal studies.

• Commonly seen in human subjects
• Not needed in animal experiments
• Ensures focus on physiological effects

Animal Testing

Animal testing offers valuable insights, particularly in scenarios where direct human experimentation is unethical. In this case, sheep served as an excellent choice due to ethical concerns of human exposure to potentially toxic materials like mercury in amalgam fillings. Sheep kidneys are comparable to human kidneys, allowing scientists to extrapolate outcomes more accurately to human scenarios. Moreover, using animals permits a controlled study environment, monitoring factors like diet and activity to ensure reliable results while maintaining ethical standards.

• Reduces ethical concerns compared to human testing
• Provides reliable data in a controlled setting
• Sheep physiology closely resembles human physiology for targeted studies

Comparative Study

A comparative study involves evaluating multiple groups to understand differences and effectiveness across treatments. In the dental fillings experiment, involving both amalgam and a potential resin treatment group alongside a control group would provide deep insights into which material is safer or more effective. This approach allows researchers to draw more definitive conclusions, showcasing the relative advantages or disadvantages of each filling type. The broader the comparison, the more potent the argument in favor of one treatment over another.

• Helps in detailed analysis and comparison of treatments
• Enhances understanding of each treatment's effects
• Assists in making informed recommendations in ongoing debates