RESUMO
BACKGROUND: The purpose of this in vitrostudy was to evaluate the retention and resistance form of complete coverage restorations supported by two different cast post and core designs. MATERIAL AND METHODS: Forty extracted maxillary central incisors were randomly divided into four groups of 10 specimens each (namely A, B, C and D). All specimens were endodontically treated and a uniform post space of 9mm was created. All prepared teeth had a 360o chamfer ferrule of 2mm in axial height measured 0.5mm coronally from the cementoenamel junction (CEJ) and an axial wall thickness of 1.5 mm. Specimens in groups A and C received cast post and cores with the standardized core design, where the core ended at the coronal part of the ferrule, while specimens in groups B and D received cores that were encircling the ferrule. Cemented complete coverage restorations in groups A and B underwent tensile load stress, while the restorations in groups C and D underwent compressive load stress until failure. RESULTS: Teeth in group A exhibited a mean failure load of 326.14±83.67 N under tension, while teeth in group B exhibited a mean failure load of 332.79±80.38 N (p=0.858). Teeth in group C recorded a mean failure load of 1042.81±205.07 N, and in group D a mean failure load of 875.15±167.64 N (p=0.061) under compression was registered. CONCLUSIONS: The standard cast post and core design with a 2 mm of ferrule height offers superior resistance, although not statistically significant (p=0.061), when compared to the core design encircling the axial wall ferrule. Both cast post and core designs offer equal retention. However, different failure modes of decementation were noted. Key words:Endodontically treated teeth, Post-and-core technique, Endodontic-post, Decementation, Root fracture, Ferrule effect.
RESUMO
PURPOSE: A survey was conducted in the Dental School, Aristotle University, Thessaloniki, Greece, (i) to assess the perceptions and experiences of senior dental students, Classes of 2014 and 2015, toward the old, specialty-specific (OC) and new, holistic-oriented (NC) undergraduate curriculum, respectively, in removable prosthodontics and (ii) to identify areas of improvement in prosthodontic training. MATERIALS AND METHODS: Structural components of both curricula were collected, including the total number of (i) laboratory/lecture/clinical training hours, (ii) written examinations, (iii) mandatory clinical cases, and (iv) European Credit Transfer and Accumulation System (ECTS) credits. A 20-item closed-type questionnaire using a five-point Likert scale was distributed in two consecutive groups of seniors, Classes of 2014 (n = 54) and 2015 (n = 57); 54 OC and 57 NC senior students filled out the questionnaire. RESULTS: A greater percentage of NC students stated that (i) they felt less confident to carry out jaw relation recording and removable partial denture metal framework design and (ii) the time allocated for clinical training was less sufficient. Students of both curricula reported that the laboratory courses and lectures contributed little to their clinical performance. Implant restorations and prosthetic management of patients with craniomandibular disorders were the most popular treatment options that the respondents felt that should be incorporated in the undergraduate curriculum. CONCLUSIONS: As a general trend, students completing the revised curriculum reported more difficulties during their training and felt more insecure about their clinical competences. To enhance students' self-confidence in prosthodontics, more effective preclinical training methods, introduction of additional treatment options, and alternative educational methods should be considered.