engleski

The criteria that should be fulfilled for post restoration following endodontic treatment

Various methods of restoring pulpless teeth have been reported for more than 200 years. After the root canal treatment, sometimes it is necessary to retain the post inside the root canal. It should be pointed out that this procedure will weaken the remaining structure of the dental root. Since clinical and laboratory data indicate that teeth are not strengthened by posts, their purpose is for retentionof a core that will provide appropriate support for definite crown. Furthermore, post and coreshad an average absolute rate of failure of 9%, and also an apical periodontitis was significantly more common in teeth with posts than in endodontically treated teeth without posts. Some studies indicate that post loosening is the most common cause of post and core failure. Root fracture was the second most common cause followed by post fracture. Factors that may affect the retention of a post are: the post type (custom or prefabricated), the post design (parallel, tapered, smooth, serrated, threaded), cementing medium, the length of the preparation, post adaptation inside the canal etc. Variation of any may affect retention of the post. Sometimes etching, conditioning or chelating agents are used to treat the dentine of the post space. Due to this , it is very important to choose the right post technique prior the clinical procedure. A frequently used and clinically appropriate guideline for post diameter is do not exceed one-third the root diameter. According to the laboratory date, threaded posts provide the greatest retention, followed by cemented parallel-sided posts. Tapered cemented posts are the least retentive. Threaded posts produce the greatest potential for root fracture and most of the clinical data support the laboratory findings. A wide range of recommendations have been made regarding post length. Reasonable clinical guidelines for length is that post should be approximately three-quarters the length of the root when treating long-rooted tooth or, the post length is dictated by retaining 5 mm of apical guttapercha. The post should be extended to the gutta-percha. Recently, post made from carbon fibre, ceramic materials and fibre reinforced polymers have been introduced. Carbon posts are made of carbon fibres embedded in an epoxy matrix and an aesthetic version of this post has a quartz exterior that makes the post collared. They possess adequate rigidity and not prone to produce tooth fracture. Ceramic posts are from zirconium dioxide and have very high flexural strengths and are very hard. Fibre-reinforced posts are made of woven polyethylene fibre ribbon that is coated with a dentine bonding agent and comparing to the metal posts, reduces the incidence of vertical root fracture. In a most clinical situation, the author prefers to use prefabricated non-metal post designed for cementation whenever possible as well as resin bonding procedure for cementation.

endodontic treatment; post; core

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