Avaliação da customização por desgaste de pinos pré-fabricados de fibra de vidro / Evaluation of fibre posts submitted to customization of the apical portion

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

25/01/2012

RESUMO

The purpose of this study was to evaluate fibre posts (White Post DC/FGM) submitted to customization of the apical portion. Experiment 1: 5 #4 posts were divided into five groups (G) and submitted to different custom adaptation treatments: GA no surface treatment, GB- industrial shaping tool (Dentsply), GC- #3195 fine diamond bur (KG Sorensen), GD- medium-grain paper discs (Sof-Lex/3M/ESPE), GE pliers (Tramontina). The micromorphology of the posts was observed in a scanning electron microscope (ZEISS/DSM 960). Experiment 2: 60 posts of different diameters were divided into six groups: G0 #0.5 posts, G1 #1 posts, G2 #2 posts, G3 - #3 posts; G4 - #4 posts and G5 #4 posts submitted to custom adaptation of the apical portion with paper discs until the diameter was equivalent to #2 posts. The posts were submitted to a 3 point bending test in a universal testing machine (Instron/5500 R), according to ISO 10477. Experiment 3: 20 freshly extracted permanent healthy human canines with similar size were endodontically treated and the crowns were removed, leaving a remaining root length of 15 mm. The teeth were embedded in acrylic resin with simulation of the periodontal ligament, received a 2 mm ferule and were divided into two groups: G1- 10 #4 posts were cemented into post spaces prepared with #4 drill (FGM) at 10 mm, G2 - 10 #4 customized posts were cemented into root spaces prepared with #2 drill (FGM) at 10 mm and #4 drill (FGM) at 5 mm. The posts were cemented with resin cement (Rely X U100/3M/ESPE), and the teeth received direct crowns of composite resin (Enforce Core/Dentsply), standardized with polycarbonate crowns (TDV). The fracture strength was measured on an Instron, at 45 degrees to the long axis of the tooth, until fracture. The 500 N cylindrical load was applied to the buccal/lingual axis 2 mm below the incisal line, at crosshead speed of 0.5 mm/min. The fracture pattern was observed and classified as favorable or unfavorable. The results were submitted to ANOVA (p<0.05). Flexural strength and resistance to fracture data were, respectively: G0 58.40+6.40; G1 83.95+9.43; G2 103.42+19.17; G3 160.78+17.30; G4- 170.47+11.28; G5 106.35+21.96;GI 303.02+62.21 and GII 402.81+131.97. Fracture patterns were statistically similar according to Mann-Whitney test. It was concluded that customization of fibre posts with diamond burs or paper discs produces acceptable micromorphological changes. The cut of the post with pliers should be avoided. Grounding of the apical portion of fibre posts reduces the flexural strength to acceptable values. Teeth restored with grounded fiber posts have grater fracture strength than teeth restored with intact posts. Grounding of the post facilitates adaptation to root walls and preserves tooth structure.

ASSUNTO(S)

técnica para retentor intrarradicular microscopia eletrônica de varredura resistência à flexão resistência à compressão odontologia coroas (odontologia) técnica para retentor intra-radicular pinos dentários restauração (odontologia) post and core technique microscopy electron scanning flexural strength compressive strength

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