title: The effect of ferrule height on stress distribution within a tooth restored with fibre posts and ceramic crown: a finite element analysis.
abstract: OBJECTIVE
  To evaluate via finite element analysis the effect of different ferrule heights on stress distribution within each part of a maxillary first premolar (MFP) restored with adhesively luted glass fiber-reinforced resin (GFRR) posts and a ceramic crown.
  
  
  METHODS
  The solid models consisted of MFP, periodontal ligament and the corresponding alveolar bone process. Four models were created representing different degrees of coronal tissue loss (0mm, 1mm, 2mm and 3mm of ferrule height). First set of computing runs was performed for in vivo FE-model validation purposes. In the second part, a 200-N force was applied on the buccal cusp directed at 45° to the longitudinal axis of the tooth. Principal stresses values and distribution were recorded within root, abutment, posts, crown and related adhesive interfaces.
  
  
  RESULTS
  All FE-models showed similar stress distribution within roots, with highest stress present in the chamfer area. In composite abutments higher stress was observed when no ferrule was present compared to ferruled FE-models. Stress distribution within crown and GFRR posts did not differ among the models. Stress values at the adhesive interfaces decreased with increasing ferrule height.
  
  
  CONCLUSIONS
  The stress state at abutment-crown and post-root interfaces was very close to their strength, when ferrule was not present. Similarly, higher ferrule produced more favorable stress distribution at post-abutment and abutment-root interfaces. Endodontically treated teeth with higher ferrule exhibit lower stress at adhesive interfaces that may be expected to lower the probability of clinical failure.
authors.affiliation: Department of Medical Biotechnologies, University of Siena, Policlinico Le Scotte, Viale Bracci, 53100 Siena, Italy; Clinic for Pediatric and Preventive Dentistry, School of Dentistry, University of Belgrade, Doktora Subotica 11, 11000 Belgrade, Serbia. Electronic address: jelenajuloski@gmail.com.
authors.forename: Jelena
authors.initials: J
authors.lastname: Juloski
authors.affiliation: Department of Medical Biotechnologies, University of Siena, Policlinico Le Scotte, Viale Bracci, 53100 Siena, Italy; Department of Oral and Maxillofacial Sciences, University "Federico II", Policlinico Via Pansini, 5, 80131 Naples, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Apicella
authors.affiliation: Department of Medical Biotechnologies, University of Siena, Policlinico Le Scotte, Viale Bracci, 53100 Siena, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Ferrari
mesh_terms: D000539:Alveolar Process / Q000502:physiology; D001641:Bicuspid / Q000502:physiology*; D001696:Biomechanical Phenomena; D002516:Ceramics / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry*; D003442:Crowns; D000044:Dental Abutments; D003764:Dental Materials / Q000737:chemistry*; D017267:Dental Prosthesis Design; D020342:Finite Element Analysis; D005898:Glass / Q000737:chemistry*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008422:Materials Testing; D008437:Maxilla / Q000502:physiology; D010513:Periodontal Ligament / Q000502:physiology; D011176:Post and Core Technique / Q000295:instrumentation*; D013314:Stress, Mechanical; D013499:Surface Properties; D019231:Tooth Preparation, Prosthodontic / Q000295:instrumentation*; D014092:Tooth Root / Q000502:physiology; D019553:Tooth, Nonvital / Q000503:physiopathology
chemical_list: D003188:Composite Resins; D003764:Dental Materials; C009753:fiberglass
keywords: Adhesion; Endodontically treated teeth; FEA; Ferrule effect; Fiber post; Stress distribution