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Abutments with reduced diameter for both cement and screw retentions: analysis of failure modes and misfit of abutment–crown–connections after cyclic loading
Author(s) -
Moris Izabela Cristina Maurício,
Faria Adriana Cláudia Lapria,
Ribeiro Ricardo Faria,
Rodrigues Renata Cristina Silveira
Publication year - 2017
Publication title -
clinical oral implants research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.407
H-Index - 161
eISSN - 1600-0501
pISSN - 0905-7161
DOI - 10.1111/clr.12816
Subject(s) - abutment , crown (dentistry) , materials science , cyclic stress , dentistry , composite material , orthodontics , structural engineering , medicine , engineering
Abstract Objective The aim of this study was to analyze failure modes and misfit of abutments with reduced diameter for both cement and screw retentions after cyclic loading. Material and Methods Forty morse‐taper abutment/implant sets of titanium were divided into four groups ( N = 10): G4.8S‐4.8 abutment with screw‐retained crown; G4.8C‐4.8 abutment with cemented crown; G3.8S‐3.8 abutment with screw‐retained crown; and G3.8C‐3.8 abutment with cemented crown. Copings were waxed on castable cylinders and cast by oxygen gas flame and injected by centrifugation. After, esthetic veneering ceramic was pressed on these copings for obtaining metalloceramic crowns of upper canine. Cemented crowns were cemented on abutments with provisional cement (Temp Bond NE ), and screw‐retained crowns were tightened to their abutments with torque recommended by manufacturer (10 N cm). The misfit was measured using a stereomicroscope in a 10× magnification before and after cyclic loading (300,000 cycles). Tests were visually monitored, and failures (decementation, screw loosening and fractures) were registered. Misfit was analyzed by mixed linear model while failure modes by chi‐square test (α = 0.05). Results Cyclic loading affected misfit of 3.8C ( P ≤ 0.0001), 3.8S ( P = 0.0055) and 4.8C ( P = 0.0318), but not of 4.8S ( P = 0.1243). No differences were noted between 3.8S with 4.8S before ( P = 0.1550) and after ( P = 0.9861) cyclic loading, but 3.8C was different from 4.8C only after ( P = 0.0015) loading. Comparing different types of retentions at the same diameter abutment, significant difference was noted before and after cyclic loading for 3.8 and 4.8 abutments. Analyzing failure modes, retrievable failures were present at 3.8S and 3.8C groups, while irretrievable were only present at 3.8S. Conclusions The cyclic loading decreased misfit of cemented and screw‐retained crowns on reduced diameter abutments, and misfit of cemented crowns is greater than screw‐retained ones. Abutments of reduced diameter failed more than conventional.