Question

\(2.50\) 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

a. A placebo group isn't necessary in this experiment as the outcome, being physiological, wouldn't be affected by the perceptual concept of having received treatment. b. Including a resin group would provide comprehensive evidence about the effects of different fillings on kidney function, contributing to informed medical advice. c. Sheep were used for ethical reasons, as exposing humans to potential health risks in the early experimental stage wouldn't be ethically sound, and animal trials are typically conducted first for safety purposes.

Step-by-step solution

Understanding a Control Group

In a scientific experiment, a control group is used for comparison purposes. It is a group that does not receive the experimental treatment but instead stays in the same condition as at the start, to evaluate the effects of the experimental treatment. In the given case, the control group of sheep did not receive any fillings, allowing comparison of the effects of the amalgam fillings on kidney function.

Discussing the need for a Placebo Group

A placebo group is a kind of control group where subjects receive a faux treatment, often to control for the psychological effects of receiving treatment. In this experiment, a placebo group is not necessary because the end outcome, which is the impact on kidney function, wouldn't be affected by the psychological aspect of believing that treatment has been received.

Benefits of Including a Resin Filling Treatment Group

Including a resin filling treatment group in this experiment would allow comparison of the effects of both types of fillings on kidney function in sheep. This could provide more comprehensive evidence about the potential health risks of different filling materials, helping to inform medical advice and patient choices.

Discussing experimental Subjects Selection

The experimenters likely used sheep rather than human subjects due to ethical considerations. Exposing humans to a potential health risk knowing that it may impair kidney function would not be ethically sound. Additionally, studies that potentially involve toxic effects are usually first conducted on animals before any human trials, following a principle that prioritizes safety and minimizes risk to human health.

Key concepts

Control Group

In the realm of scientific investigations, a control group is vital for establishing a baseline to measure the effects of an intervention. In the case of the sheep experiment analyzing the influence of amalgam fillings on kidney function, the control group consisted of sheep that did not receive any dental fillings. This was crucial to discern whether any observed changes in kidney function could be attributed directly to the treatment with amalgam fillings.

The control group serves as a comparative point that remains unaffected by the experimental treatment. By observing this group, researchers can detect natural variations and separate them from the effects caused by the treatment under study. For instance, if kidney issues were observed in both the control and experimental groups, one could infer that the amalgam fillings might not be the sole cause of the impairment.

Placebo Group

The concept of a placebo group arises when the outcome of an experiment might be influenced by the subjects' expectations, known as the placebo effect. However, in this experiment investigating the effects of dental fillings on kidney function in sheep, a placebo group is not requisite. Kidney function, unlike symptoms affected by psychological factors, is not likely to change based on whether the sheep believe they have received a treatment.

A placebo typically mimics the treatment without containing active substances and helps to ascertain whether the treatment itself or the act of being treated is producing the observed effects. Since the sheep would have no awareness of receiving a 'sham' filling, and kidney function assessments are objective, incorporating a placebo group would not add value to the core objective of this particular study.

Resin Filling Treatment

The inclusion of a resin filling treatment group would be a significant enhancement to the design of the dental filling experiment. By introducing sheep treated with resin fillings, researchers can directly contrast the effects of resin versus amalgam fillings on kidney function. This comparison could reveal if resin fillings, a modern alternative to amalgam, pose a lesser, greater, or equivalent risk to kidney health.

Including this additional group would broaden the scope of the research, ultimately aiding in a more well-rounded conclusion about which dental filling material may be more suitable for use, especially concerning those with immune or kidney conditions. This comparative analysis is vital, as it provides more context and information for dentists and patients when choosing between amalgam and resin for dental restorations.

Ethical Considerations in Research

Ethical considerations in research are paramount, particularly when the wellbeing of subjects is involved. In the experiment with sheep, ethical standards necessitate the consideration of potential risks and the imperative to prevent harm. The use of sheep instead of humans suggests an adherence to the ethical principle of 'do no harm.'

Before human trials are ever considered, it is standard practice to perform preliminary studies on animals to ascertain the safety and potential effects of treatments. After thorough animal testing, researchers may progress to human trials with a more extensive understanding of possible risks and benefits, thereby protecting human participants. This stepped approach embodies ethical responsibility, ensuring that human subjects are not exposed to unnecessary danger and that the welfare of animal subjects is carefully managed within the context of the research's aims.