Pulp necrosis is one of the main complication of dental trauma. When it happens on an immature tooth, pulp necrosis implies a lack of root maturation and apical closure. A therapy called apexification is required to induce the formation of a calcified apical barrier allowing a permanent and hermetic root filling.The aim of this study is to compare the efficacy of a new apexification method using Mineral Trioxide Aggregate (MTA®) with the reference treatment based on calcium hydroxide repeated stimulations.

36 patients aged 6 to 18 and presenting a non vital immature tooth will be included in the study (inclusion period: 12 months). These patients will be randomly divided into two groups: one treated with MTA®, and the other one with calcium hydroxide. For each patient, the total duration of the study will be 12 months. Recalls will be performed at 15 and 21 days and then at 3, 6 and 12 months to assess by clinical and X-ray exams the main success criterion: presence of a calcified apical barrier or not. Additional criterions such as presence of clinical symptoms or not, apical morphology and depth of this apical barrier will be observed. This randomised prospective therapeutic study will allow to assess the ability of MTA® inducing apexification of a non vital immature tooth. Furthermore, it will be possible to compare for both materials the kinetics of clinical symptoms disappearance and the morphology and depth of apices.

Inclusion Criteria:

• Indication of apexification treatment of an anterior immature tooth
• Patients aged 6 to 18
• Enlightened agreement of the patient and his/her legal representatives
• Prerequisite medical examination

Exclusion Criteria:

General disease

• diabetes
• immunosuppression of whatever origin (AIDS, drugs, …)
• severe asthma
• chronical disease requiring treatment
• eating disorders (anorexia, bulimia, malnutrition, …) Oral disease
• periodontal disease
• Administration of corticoids in a period of 3 months preceding the inclusion
• Patient with no social security cover