title: The prognosis of splinted restoration of the most-distal implants in the posterior region.
abstract: OBJECTIVE
  The aim of this study was to compare the efficacies of two-implant splinting (2-IS) and single-implant restoration (1-IR) in the first and second molar regions over a mean functional loading period (FLP) of 40 months, and to propose the appropriate clinical considerations for the splinting technique.
  
  
  METHODS
  The following clinical factors were examined in the 1-IR and 2-IS groups based on the total hospital records of the patients: sex, mean age, implant location, FLP, bone grafting, clinical crown-implant ratio, crown height space, and horizontal distance. The mechanical complications [i.e., screw loosening (SL), screw fracture, crown fracture, and repeated SL] and biological complications [i.e., peri-implant mucositis (PM) and peri-implantitis (PI)] were also evaluated for each patient. In analysis of two groups, the chi-square test and Student's t-test were used to identify the relationship between clinical factors and complication rates. The optimal cutoff value for the FLP based on complications was evaluated using receiver operating characteristics analysis.
  
  
  RESULTS
  In total, 234 patients with 408 implants that had been placed during 2005 - 2014 were investigated. The incident rates of SL (P<.001), PM (P=.002), and PI (P=.046) differed significantly between the 1-IR and 2-IS groups. The FLP was the only meaningful clinical factor for mechanical and biological complication rates in 2-IS.
  
  
  CONCLUSIONS
  The mechanical complication rates were lower for 2-IS than for 1-IR, while the biological complication rates were higher for 2-IS. FLP of 39.80 and 46.57 months were the reference follow-up periods for preventing biological and mechanical complications, respectively.
authors.affiliation: Department of Periodontology, Ewha Womans University Mokdong Hospital, Seoul, Republic of Korea.
authors.forename: Jong-Bin
authors.identifier: 0000-0002-6800-4337
authors.initials: JB
authors.lastname: Lee
authors.affiliation: Department of Prosthodontics, Ilsan Hospital, National Health Insurance Service, Goyang, Republic of Korea.
authors.forename: Man-Yong
authors.identifier: 0000-0002-8959-935X
authors.initials: MY
authors.lastname: Kim
authors.affiliation: Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, Seoul, Republic of Korea.
authors.forename: Chang-Sung
authors.identifier: 0000-0003-3902-1071
authors.initials: CS
authors.lastname: Kim
authors.affiliation: Department of Periodontology, Ilsan Hospital, National Health Insurance Service, Goyang, Republic of Korea.
authors.forename: Young-Taek
authors.identifier: 0000-0002-5132-5783
authors.initials: YT
authors.lastname: Kim
keywords: Complication rates; Functional loading period; Implant restoration; Posterior region; Splinted restoration