title: Soft tissues stability of cad-cam and stock abutments in anterior regions: 2-year prospective multicentric cohort study.
abstract: OBJECTIVE
  Aim of this study was to verify if the type of implant abutment manufacturing, stock or cad-cam, could influence the maintenance of stable gingival margins around single restorations in anterior areas.
  
  
  METHODS
  After 16 weeks of healing, implants (Osseospeed, Astra Tech Dental Implant) were positioned. Depending on the different fixture inclination and the thickness of buccal peri-implant soft tissue, abutment selection resulted in four groups: Group 1 (patients with zirconia ZirDesign(®) stock abutments), Group 2 (titanium stock TiDesign(®) abutments), Group 3 (zirconia cad-cam abutments), and Group 4 (titanium cad-cam abutments). The following parameters were assessed: buccal gingival margin modification (BGM). The modification of the implant gingival margin was followed at 1 and 2 years of follow-up. A computerized analysis was performed for measurements. Differences between soft tissue margin at baseline and after 2 years measured the gingival margin recession. A general linear model was used to evaluate each group in relation to gingival recession after two years. Tukey's post hoc test was used to compare the mean REC indexes of each group of abutments.
  
  
  RESULTS
  Seventy-two healthy patients (39 males and 33 females; mean age of 46 years) scheduled for single gap rehabilitation in anterior areas were enrolled. A 100% of implant survival rate was observed after 24 months of function. One failure occurred due to fracture of a Zirconia cad-cam abutment. Moreover, two abutment screw unscrewing were observed. Both for zirconia and titanium stock abutments (Group 1 and 2), the mean recession of implant buccal soft tissue was of 0.3 mm (SD of 0.3 and 0.4 mm, respectively). Soft tissue mean recession of zirconia and titanium cad-cam abutments (Group 3 and 4) was of 0.1 and -0.3 mm, respectively (SD of 0.3 and 0.4 mm, respectively). REC values of cad-cam titanium abutments (Group 4) were significantly lower than that of Group 1 (-0.57 mm), Group 2 (-0.61 mm), and Group 3 (-0.40 mm), respectively (Table 4).
  
  
  CONCLUSIONS
  In the anterior area, the use of cad-cam abutments is related to a better soft tissue stability. Such a relationship is significant if cad-cam titanium abutments are compared to both titanium and zirconia stock abutments.
authors.affiliation: Department of Prosthodontics, Dental Clinic, School of Dentistry, University of Milan, Milan, Italy.
authors.forename: Diego
authors.initials: D
authors.lastname: Lops
authors.affiliation: Department of Periodontology, School of Dentistry, University of Padova, Padova, Italy.
authors.forename: Eriberto
authors.initials: E
authors.lastname: Bressan
authors.affiliation: Department of Prosthetic Dentistry, School of Dentistry, University of Padova, Padova, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Parpaiola
authors.affiliation: Department of Periodontology, School of Dentistry, University of Padova, Padova, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Sbricoli
authors.affiliation: FRANCI Insitute, Padova, Italy.
authors.forename: Denis
authors.initials: D
authors.lastname: Cecchinato
authors.affiliation: Department of Prosthodontics, Dental Clinic, School of Dentistry, University of Milan, Milan, Italy.
authors.forename: Eugenio
authors.initials: E
authors.lastname: Romeo
mesh_terms: D017076:Computer-Aided Design; D059605:Dental Implant-Abutment Design; D003758:Dental Implantation, Endosseous / Q000379:methods*; D019250:Dental Implants, Single-Tooth; D005260:Female; D005889:Gingival Recession / Q000175:diagnosis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014025:Titanium; D016896:Treatment Outcome; D015040:Zirconium
chemical_list: D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide
keywords: anterior regions; cad-cam abutments; soft tissues stability; stock abutments