Root canal obturation techniques. Bioceramics and traditional sealers towards the evolution of the techniques

OBJECTIVES The aim of this didactic module is to describe the main root canal obturation techniques, the biomaterials used, their applications, limits and advantages. MATERIALS AND METHODS The main root canal obturation techniques are described, with particular attention to the scientific evidence, the clinical evaluation and some historical aspects. Biomaterials to seal the root canal are examined, describing their chemical physical and biological properties, such as the setting time and expansion, radiopacity, biointeractivity and bioactivity. RESULTS Root canal obturation must avoid the bacteria recolonization of previously instrumented root canal and prevent the contamination of the periapical bone. The filling material should provide a stable tridimensional seal of the end odontic space with no voids or gaps at the root canal-material interface. The materials must also be insoluble, radiopaque, biocompatible and non-toxic. The techniques and the materials should be easy to be used in complex cases and non-operator dependent. Classical root canal techniques, such as cold lateral compaction and warm vertical compaction demonstrated valid results in long term studies, when associated to gutta-percha and traditional sealers. Carrier-based techniques, developed 30 years ago, showed extremely predictable results, which may be attributable to their simple procedure. For this reason, carrier-based is considered one of the gold standard techniques nowadays. All the techniques necessitate of a sealers. The sealers are used to occupy the small porosities and filling defects, aiming to guarantee the long-term sta bility of root canal treatment. Traditional zinc oxide-eugenol cements and epoxy resin based sealers have been used for years with excellent clinical results documented in literature. Bioceramic calcium silicate based cements are a group of materials from MTA initially used for retrograde obturation during root-end surgery. Bioceramics have innovative properties such as excellent biocompatibility, the ability to set in presence of moisture, the ability to expand and to nucleate apatite. Cold filling techniques, such as single-cone and lateral compaction, are recommended for these cements. Their principal clinical applications are elements with perforations or canal aberrations, wide apexes, large periapical bone defects and infected root canals. CONCLUSIONS Several materials are now clinically available. Knowledge and proficiency of both materials and technique is import ant in clinical practice. Coronal obturation and post-endodontic rehabilitation is crucial to prevent reinfection of the root canal over time. CLINICAL SIGNIFICANCE The evolution of cements, with the introduction of calcium-releasing bioceramics, represent a further step towards a more predictable endodontics using osteoinductive and osteoconductive materials. Biomaterials knowledge, and the proficiency of the operator in root canal obturation techniques are important aspects to obtain excellent and long-term clinical results.