Anna-Maria Le Bell-Rönnlöf

Publications (4)5.52 Total impact

• Article: Load-bearing capacity of human incisor restored with various fiber-reinforced composite posts.

  Anna-Maria Le Bell-Rönnlöf, Lippo V J Lassila, Ilkka Kangasniemi, Pekka K Vallittu
  [show abstract] [hide abstract]
  ABSTRACT: The aim of this study was to evaluate the load-bearing capacity and microstrain of incisors restored with posts of various kinds. Both prefabricated titanium posts and different fiber-reinforced composite posts were tested. The crowns of human incisors were cut and post preparation was carried out. The roots were divided into groups: (1) prefabricated serrated titanium posts, (2) prefabricated carbon fiber-reinforced composite posts, (3) individually formed glass fiber-reinforced composite posts with the canal full of fibers, and (4) individually formed "split" glass fiber-reinforced composite posts. The posts were cemented and composite crowns were made. Intact human incisors were used as reference. All roots were embedded in acrylic resin cylinders and stored at room temperature in water. Static load was applied under a loading angle of 45° using a universal testing machine. On half of the specimens microstrain was measured with strain gages and an acoustic emission analysis was carried out. Failure mode assessment was also made. The group with titanium posts showed highest number of unfavorable failures compared to the groups with fiber-reinforced composite posts. With fiber-reinforced composite posts the failures may more often be favorable compared to titanium posts, which clinically means repairable failures.
  Dental materials: official publication of the Academy of Dental Materials 03/2011; 27(6):e107-15. · 2.88 Impact Factor
• Article: Bond strength of composite resin luting cements to fiber-reinforced composite root canal posts.

  Anna-Maria Le Bell-Rönnlöf, Milla Lahdenperä, Lippo V J Lassila, Pekka K Vallittu
  [show abstract] [hide abstract]
  ABSTRACT: The aim of this study was to compare the attachment of different composite resin luting cements to a fiber-reinforced composite (FRC) post with a semi-interpenetrating polymer network polymer matrix. Six different brands of composite resin luting cement stubs were applied on the surface of FRC post material and light-cured for 40 seconds. Shear bond strengths of luting cement stubs were measured using a universal testing machine. The differences in shear bond strengths between the cements were not statistically significant. All of the tested composite resin luting cements provided acceptable attachment to the tested FRC post. The tested FRC post material is suitable to use with different composite resin luting cements.
  The journal of contemporary dental practice 02/2007; 8(6):17-24.
• Article: Fracture behavior of structurally compromised non-vital maxillary premolars restored using experimental fiber reinforced composite crowns.

  Wietske A Fokkinga, Cees M Kreulen, Anna-Maria Le Bell-Rönnlöf, Lippo V J Lassila, Pekka K Vallittu, Nico H J Creugers
  [show abstract] [hide abstract]
  ABSTRACT: To study the fracture behavior of direct resin composite crowns with or without experimental fiber reinforcement. Clinical crowns of single-rooted maxillary premolars were cut off at the cemento-enamel junction. Canals were prepared with Gates Glidden drills up to size 4. No additional post-space preparations were made. Roots were embedded in acrylic and canal entrances were standardized (depth 2 mm, diameter 1.75 mm). Three groups of 14 samples were treated as follows: (1) custom-made glass FRC post (EverStick Post); fibers 5 mm deep in the canal, (2) similar post-system as (1) with incorporation of a new type of glass fiber fabric, (3) no fiber reinforcement (control). Posts were cemented with resin cement (Panavia F). Resin composite crowns (Filtek Z250) were made using an anatomically formed mold. Static load until fracture was applied using a universal loading device with a cylindrical bar (diameter 2 mm) with a crosshead speed of 5 mm/minute (loading angle: 30 degrees to the tooth long-axis). Failure modes were categorized as favorable and unfavorable failures. There was no significant difference in mean failure loads among the four groups (P > 0.05). Favorable failures occurred significantly more often in Group 2 than in the other groups (P < 0.05). The results suggest that an incorporated glass fiber fabric does not affect the load-bearing capacity of resin composite complete crowns on structurally compromised and non-vital premolars. Incorporation of a glass fiber fabric, however, has a beneficial effect on the failure mode.
  American journal of dentistry 12/2006; 19(6):326-32. · 0.76 Impact Factor
• Article: In vitro fracture behavior of maxillary premolars with metal crowns and several post-and-core systems.

  Wietske A Fokkinga, Cees M Kreulen, Anna-Maria Le Bell-Rönnlöf, Lippo V J Lassila, Pekka K Vallittu, Nico H J Creugers
  [show abstract] [hide abstract]
  ABSTRACT: The in vitro fracture behavior of severely damaged premolars, restored with metal crowns with limited ferrule and several post-and-core systems, was investigated. Crowns of maxillary premolars were removed and canals were prepared with Gates Glidden drills and with Parapost drills. Groups of 11 samples were each treated with cast post-and-cores (Parapost XP, Wironium Plus) (group 1), prefabricated metal posts (Parapost XH) (group 2), prefabricated glass fiber posts (Parapost FiberWhite) (group 3), and custom-made glass fiber posts (EverStick Post) (group 4). Posts and composite cores and metal crowns in groups 2, 3, and 4 were adhesively cemented. Post-and-cores and crowns in group 1 were cemented with phosphate cement. Thermocycling was performed (6,000x, 5-55 degrees C). Two static load tests (30 degrees ) were applied. During the first load test (preloading) no failures occurred. Failure modes from the second load test were categorized into favorable and unfavorable failures. Mean failure loads among the four groups (group 1, 1,845 N; group 2, 1,718 N; group 3, 1,812 N; and group 4, 1,514 N) were not significantly different. Unfavorable failures were root fractures and favorable failures were postcrown displacements. No differences in frequencies of unfavorable/favorable failures were seen among the groups. The results suggest that different post-and-core systems have no influence on the fracture behavior of severely damaged premolars restored with metal crowns with limited ferrule.
  European Journal Of Oral Sciences 07/2006; 114(3):250-6. · 1.88 Impact Factor