title: Influence of preparation depths on the fracture load of customized zirconia abutments with titanium insert.
abstract: OBJECTIVE
  This study evaluated the fracture load of customized zirconia abutments with titanium insert according to preparation depths, with or without 5-year artificial aging.
  
  
  METHODS
  Thirty-six identical lithium disilicate crowns (IPS e.max press) were fabricated to replace a maxillary right central incisor and cemented to the customized zirconia abutment with titanium insert on a 4.5×10 mm titanium fixture. Abutments were fabricated with 3 preparation depths (0.5 mm, 0.7 mm, and 0.9 mm). Half of the samples were then processed using thermocycling (temperature: 5-55℃, dwelling time: 120s) and chewing simulation (1,200,000 cycles, 49 N load). All specimens were classified into 6 groups depending on the preparation depth and artificial aging (non-artificial aging groups: N5, N7, N9; artificial aging groups: A5, A7, A9). Static load was applied at 135 degrees to the implant axis in a universal testing machine. Statistical analyses of the results were performed using 1-way ANOVA, 2-way ANOVA, independent t-test and multiple linear regression.
  
  
  RESULTS
  The fracture loads were 539.28 ± 63.11 N (N5), 406.56 ± 28.94 N (N7), 366.66 ± 30.19 N (N9), 392.61 ± 50.57 N (A5), 317.94 ± 30.05 N (A7), and 292.74 ± 37.15 N (A9). The fracture load of group N5 was significantly higher than those of group N7 and N9 (P<.017). Consequently, the fracture load of group A5 was also significantly higher than those of group A7 and A9 (P<.05). After artificial aging, the fracture load was significantly decreased in all groups with various preparation depths (P<.05).
  
  
  CONCLUSIONS
  The fracture load of a single anterior implant restored with lithium disilicate crown on zirconia abutment with titanium insert differed depending on the preparation depths. After 5-year artificial aging, the fracture loads of all preparation groups decreased significantly.
authors.affiliation: Department of Prosthodontics, School of Dentistry, Chonnam National University, Gwangju, Korea.
authors.forename: Han-Sung
authors.initials: HS
authors.lastname: Joo
authors.affiliation: Department of Prosthodontics, School of Dentistry, Chonnam National University, Gwangju, Korea.
authors.forename: Hong-So
authors.initials: HS
authors.lastname: Yang
authors.affiliation: Department of Prosthodontics, School of Dentistry, Chonnam National University, Gwangju, Korea.
authors.forename: Sang-Won
authors.initials: SW
authors.lastname: Park
authors.affiliation: RIS Foundation for Advanced Biomaterials, School of Dentistry, Chonnam National University, Gwangju, Korea.
authors.forename: Hyun-Seung
authors.initials: HS
authors.lastname: Kim
authors.affiliation: Department of Prosthodontics, School of Dentistry, Chonnam National University, Gwangju, Korea.
authors.forename: Kwi-Dug
authors.initials: KD
authors.lastname: Yun
authors.affiliation: Department of Prosthodontics, School of Dentistry, Chonnam National University, Gwangju, Korea.
authors.forename: Min-Kyung
authors.initials: MK
authors.lastname: Ji
authors.affiliation: Department of Prosthodontics, School of Dentistry, Chonnam National University, Gwangju, Korea.
authors.forename: Hyun-Pil
authors.initials: HP
authors.lastname: Lim
keywords: Artificial aging; Dental implant; Fracture load; Preparation depth; Titanium insert; Zirconia abutment