From all teaching methodologies focused on student learning (active methods), one of the most established in Health Sciences is Problem Based Learning (PBL), incorporated in our discipline (Pediatric Dentistry, Degree of Dentistry) under the impulse of projects of educational innovation of our university (UCM). Its methodology focuses in the student´s ability to solve the common problems of their clinical practice by applying knowledge and skills, so they learn to develop as a professional. The working process is structured in four phases and ends with a summary of the information gathered, a report with new knowledge and presentation of the problem and its resolution to the whole group. The major part of the work is done in non-school hours, which produces a discontinuous tutoring.

Some drawbacks emerged from the teachers and students perspective: work overload, superficial development of the problem, lack of tutorial control and excessive autonomy, parasitism among students, collective cover-up, late tasks delivery and last minute difficulties in assessing individual work, etc.

After analyzing these problems, we consider the Wiki could facilitate this collaborative work. Its use could be a strategy that motivates the students to realize individual and group tasks, and could allow the visibility of the whole process.

- Encouraging a more active participation of students in the tasks assigned to problem-based learning;
- Strengthen the relationship between students and tutorial work;
- Allow better control of process development, contributing to the planned temporary compliance;
- Facilitate the assessment of individual contributions and group contributions throughout the process.

The project has been developed in two chronological stages:
1st) Distribution of students in groups of 4 and assignment of a tutor, who poses the problem and guides its development through seven successive steps.
2nd) Creation of ten Wiki page, each one in relation to a PBL. In each one appears title, problem, objectives and distribution of the students in the group. According to a time schedule, the Wiki integrates individual work, the intragroup collaborative work and the intergroup collaborative work. At the beginning of the course, teachers show to the students the working protocol and the criteria for evaluation their participation.

In the present course, students have done the work related to the PBL by the wiki, so they have been able to make the documents collaboratively. We believe that the best way to foment this new teaching practice would be by evaluation. In order to apply uniform evaluation criteria, a known protocol was developed including: number of entries, extension and quality of them; entries within the group and entries to other groups; chronology and compliance with established deadlines and quality of the final report.
In this pilot study, we found some problems related to poor management of the platform and a lack of planning in the practical use of the tool. Its main advantages are related to the control and evaluation throughout the process.

This new educational tool allows collaborative training activities in a virtual environment. Wikis can facilitate the realization of collaborative projects between students but it is necessary to design a proper planning to incorporate them.