Pulp Capping With Two Different Agents

The purpose of this study was to test two dental products used as direct pulp capping agent for the permanent teeth. The two products were mineral trioxide aggregate and calcium hydroxide.

A direct pulp capping consists of covering an exposed tooth pulp (the inside portion of the tooth where the blood vessels and nerve supply the tooth) with a medication to maintain tooth vitality. Different events can cause the pulp to be exposed, for example a deep cavity, or an accident where the outer portion of the tooth fractures. When this occurs, it is sometimes possible to place a medicine over the top of the exposure (a "cap") in an effort to allow the pulp to heal on its own. Our study intended to compare two of those medicines, calcium hydroxide and mineral trioxide aggregate, both Federal Drug Administration (FDA) approved products, to determine if one performed better than the other.

The study was conducted with patients recruited by Northwest PRECEDENT practitioners. The practitioners interested in participating in the study were randomized (assigned by chance) to one of the two intervention groups: a treatment group (mineral trioxide aggregate) and a control group (calcium hydroxide).

Direct pulp capping was completed on permanent (adult) teeth with pulps exposed due to decay, trauma (injury) or mechanical exposure. Treated teeth were followed over two years to determine how well they responded to the treatment.

All patients who had a pulp exposure of a permanent tooth were eligible for the study. These patients were further asked to participate in the study if they satisfied the inclusion criteria for the study and did not present any of the exclusion criteria stated in the study protocol.

A tooth that received a pulp cap was treated in the following manner: After a tooth pulp had been exposed and the tooth was found to be suitable for a pulp cap, the exposure and surrounding area was cleaned by gentle rinsing with water. A cotton pellet moistened with 5.25% sodium hypochlorite was placed over the exposure and allowed to sit for 1-2 minutes. This procedure was used to control pulp bleeding and remove the germs from that area. After the initial period, the cotton pellet was removed and the area inspected. If bleeding continued, a new cotton pellet moistened in the sodium hypochlorite solution was reapplied to the area for an additional several minutes. This was repeated until bleeding was controlled or the practitioner decided that pulp capping was not appropriate for the situation. Once the bleeding was controlled from the exposure, one of the two pulp capping agents was applied to the pulp exposure site.

Practices were assigned by chance into one of two treatment groups, those that completed direct pulp capping with mineral trioxide aggregate and those that completed direct pulp capping with calcium hydroxide, both FDA approved agents for this purpose. The handling characteristics of the two materials were so different, that it was not practical to blind the practitioners as to which material they were using. Likewise, training in the use of each material was required. It was believed that it was more important that the practitioner become familiar and competent in the use of one of the materials to ensure it was used appropriately, than it was to have practitioners use both materials and confuse procedures between them. Since time was a critical element in the success or failure of direct pulp capping, the patients were consented to participate in the study after the procedure was done. A resin-modified glass ionomer liner (e.g. Vitrebond, Fuji Lining Cement, Fuji II LC, Vitremer) was placed over the pulp capping agent. This liner sealed the pulp capping agent and protected the pulp from being infiltrated with bacteria. After the resin-modified glass ionomer lining material was set, the final filling was placed.

Two types of instruments were used in this study:

Study participant data collection form This form collected two types of data: demographic and clinical data. The demographic part gathered information regarding patient age, gender, and race. The clinical form collected data regarding the clinical and x-ray evaluation of the tooth treated with a direct pulp cap: condition of the tooth, the type of pulp exposure (by decay, by injury or during tooth preparation), patients' complaints regarding the tooth, and results of diagnostic tests (x-ray, pain to biting or temperature, etc) were recorded.

Practitioner feedback survey A survey was administered to all practitioners who participated in the study. This survey included a series of questions designed to evaluate the communication between the member practitioners and the network, practitioner/staff training, patient recruitment, obtaining informed consent, data collection and data transmission, including the electronic data capture system. The survey also tried to determine how well the offices were able to combine the research in a regular daily office schedule in order to determine if a research project would affect the normal day-to-day routine.

The intent of this study was to find out which of the two products yielded better results as a pulp capping agent. In order to detect this, the failure rates in the two treatment groups were compared using statistical tests. Distributions of covariates in the two treatment groups were compared and clinical judgment was used to identify covariates with serious group imbalances that would cause an unusual result for the primary analysis. Logistic regression was used to compare failure rates while adjusting for any covariates that were imbalanced between groups.