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I 35 trends _ tooth and restoration survival I roots2_2011 _Principle #VII Until more long-term data is available, fibre- reinforcedresinpostsshouldbeusedwithcaution. For many years, the standard method of restoring endodonticallytreatedteethhasbeeneitheracustom castpostandcoreoraprefabricatedmetalpostwitha restorativematerialcore.41, 82, 83 Anationwidesurveyof dentists in 1994 reported that 40% of general practi- tioners used prefabricated posts, and the most popu- lar post was the parallel-sided serrated metal post.28 The usage of prefabricated posts has undoubtedly in- creasedevenmoresubstantiallysincethe1994survey. The high demand for aesthetic restorations and all- ceramiccrownsledtothedevelopmentofavarietyof non-metallic prefabricated post systems as alterna- tives to metal posts.84–87 In addition to the aesthetic advantages of non-metallic posts, laboratory studies have shown that the resin-based alternative posts have favourable physical and mechanical properties and there is less root fracture with fibre-reinforced resin posts than with metal posts.88–92 However, clini- cal studies of fibre-reinforced posts have produced a wide range of reported failure percentages, ranging from 0% after a mean of 2.3 years to 11.4% after 2 years.9, 58–61, 63, 93–96 Post loosening and root fracture have been the most commonly reported complica- tions (Fig. 7).58–62, 93, 97, 98 Because the core depends on the retentive capacity of the post, the prognosis of thefinalrestorationishighlydependentonthereten- tion of the post.99 Given the wide range of reported failure percentages, it appears that additional long- term clinical data is needed to determine the efficacy of fibre-reinforced posts. _Conclusion Based on this review of available research, the following clinical recommendations are made: 1. Crowns are not needed for intact or minimally restored anterior teeth except when substantial colour or form changes cannot be accomplished by more conservative means. 2. Crowns should be placed on most endodontically treated posterior teeth to enhance their long-term survival.Thereissomedatathatindicatesposterior teeththatareintact,exceptfortheaccessopening, can be satisfactorily restored with composite resin rather than a crown. However, the long-term success of this more conservative treatment in the presence of heavy occlusal forces is not known. 3. Posts weaken teeth and they should only be used when the core cannot be adequately retained by some other means. 4. An adequate apical seal is retained by preserving 5mm of gutta-percha. 5. Short posts should be avoided, as they increase the potential for root fracture. For all teeth except molars, optimal post length is determined by retaining5mmofapicalgutta-perchaandextend- ing the post to that depth. For molars, posts should only be placed in the primary roots (palatal roots or maxillary molars and distal roots of mandibular molars)andtheyshouldnotbeextendedmorethan 7mm apical to the orifice of the root canal owing to the possibility of root thinning or perforation. 6.Thediameterofpostsshouldnotexceedone-thirdof therootdiametertominimiserootthinningandthe potential for root fracture. Post preparation instru- mentdiametershouldbematchedtorootdiameters. 7. Whencrownsareplacedonendodonticallytreated teeth,theyshouldencompass2mmoftoothstruc- ture apical to the core whenever possible, since crown ferrules increase the resistance of teeth to fracture. 8. Until more long-term clinical data becomes avail- able, fibre-reinforced resin posts should be used with caution owing to the wide range of reported failure rates in clinical studies._ Editorial note: A complete list of references is available fromthepublisher. Fig. 7_A radiograph of a fractured maxillary lateral incisor with a glass fibre post. Dr Nadim Z.Baba Loma Linda University,School of Dentistry Department of Restorative Dentistry 11092Anderson Street Loma Linda,CA 92350 USA nbaba@llu.edu _contact roots Fig. 7