"Randomized control clinical trial" would probably be the most appropriate study design to evaluate whether a certain material (material A) has any effect whatsoever on the outcome of a particular treatment. In a recently published book "Introduction to randomized control clinical trials" by JNS Matthews, there is a very nice definition:
"A randomized concurrently controlled clinical trial is simply an experiment performed on human subjects to assess the efficacy of a new treatment for some condition. It has two key features:
- The new treatment is given to a group of patients (treated group) and another treatment, often the most widely used, is given to another group of patients at the same time (control group). This is what makes the trial concurrently controlled.
- Patients are allocated to one group or another by randomization. "(1)
"Trials are applied to many different modes of treatment... for example, new surgical procedures, screening programs, diagnostic procedures etc."(1)
How does this apply to our material A? A double-blind trial would be impossible in this case, because a clinician would always know the details of the treatment. On the other hand, a single-blind trial would be possible and recommended since the patient wouldn't know the details of the treatment in order to exclude the possible placebo effect.
Patient inclusion criteria should be taken into consideration at the beginning of the trial. These include, but are not restricted to, patient age, general health, the diagnosis of the current dental condition, the history of this condition etc. It would be wise to "standardise" the cohort so that the number of variables is reduced as much as possible. For example, root canal treatment of a pulpitis may have a different outcome than the treatment of periapical disease, because of the nature of the two dental conditions and variations in patients' immunological response to any of them. Therefore, it would be recommended that one of the inclusion criteria is the uniformity of clinical diagnosis.
Randomization would be easy using the table of random numbers. It excludes any potential bias and is always preferred to other ways of patient selection, as long as the number of cases in both the treated and control group is the same or as similarly-sized as possible. Most statistical tests are most powerful when the groups being compared have equal sizes.
Then, once the treatment is performed, the treated group would receive material A and the control group would receive placebo. The outcome of the treatment would be monitored over at least 3 years, using the standard parameters for monitoring the outcome of this particular treatment. After the monitoring period, (an) appropriate statistical test(s) would be used to assess the difference in treatment outcomes between the two groups of patients.
Only then would it be possible to claim that material A has any effect on the outcome of this particular dental treatment.
(1) Matthews JNS. Introduction to randomized control clinical trials. 2nd edition. Chapman&Hall/CRC; Boca Raton, FL, USA; 2006.
