title: Soft tissue biological response to zirconia and metal implant abutments compared with natural tooth: microcirculation monitoring as a novel bioindicator.
abstract: BACKGROUND
  Zirconia is often used for implant abutments for esthetics. The aim of this clinical study was to compare the effects of zirconia and metal abutments on periimplant soft tissue.
  
  
  METHODS
  Ten maxillary anterior implant patients, 5 with metal abutments and 5 with zirconia abutments, were enrolled in this trial. The soft tissue around the implant abutments was evaluated by 2-dimensional laser speckle imaging and thermography. The blood flow in soft tissue around natural teeth was also measured to correct for differences among the subjects.
  
  
  RESULTS
  Significantly greater blood flow was detected in the zirconia abutment group (95.64 ± 5.17%) relative to the metal abutment group (82.25 ± 8.92%) in free gingiva (P = 0.0317). Reduced blood flow (by almost 18%) was detected in the tissue surrounding metal abutments compared with the tissue surrounding natural teeth. The surface temperature showed no significant difference for all measurements.
  
  
  CONCLUSIONS
  These results suggest that blood flow in tissue surrounding zirconia abutments is similar to that in soft tissue around natural teeth. Moreover, zirconia abutments could be advantageous for the maintenance of immune function by improving blood circulation.
authors.affiliation: *Graduate Student, Department of Oral Reconstruction and Rehabilitation, Graduate School, Kyushu Dental University, Fukuoka, Japan. †Assistant Professor, Department of Oral Reconstruction and Rehabilitation, Kyushu Dental University, Fukuoka, Japan. ‡Assistant Professor, Department of Oral Reconstruction and Rehabilitation, Kyushu Dental University, Fukuoka, Japan. §Assistant Professor, Department of Oral Reconstruction and Rehabilitation, Kyushu Dental University, Fukuoka, Japan. ‖Associate Professor, Department of Oral Reconstruction and Rehabilitation, Kyushu Dental University, Fukuoka, Japan. ¶Professor, Department of Oral Reconstruction and Rehabilitation, Kyushu Dental University, Fukuoka, Japan.
authors.forename: Norihiro
authors.initials: N
authors.lastname: Kajiwara
authors.forename: Chihiro
authors.initials: C
authors.lastname: Masaki
authors.forename: Taro
authors.initials: T
authors.lastname: Mukaibo
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kondo
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Nakamoto
authors.forename: Ryuji
authors.initials: R
authors.lastname: Hosokawa
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers; D000044:Dental Abutments / Q000009:adverse effects; D003757:Dental Implantation / Q000009:adverse effects / Q000379:methods; D003764:Dental Materials / Q000009:adverse effects*; D005260:Female; D005881:Gingiva / Q000098:blood supply*; D006801:Humans; D007834:Lasers; D008297:Male; D008833:Microcirculation / Q000502:physiology; D008875:Middle Aged; D013817:Thermography; D055815:Young Adult; D015040:Zirconium / Q000009:adverse effects*
chemical_list: D015415:Biomarkers; D003764:Dental Materials; D015040:Zirconium; C028541:zirconium oxide