The impact of dis-/reconnection of laser microgrooved and machined implant abutments on soft- and hard-tissue healing

Objectives To (i) investigate the influence of different extensions of a laser microgrooved abutment zone on connective tissue attachment and (ii) assess the impact of a repeated abutment dis-/reconnection on soft- and hard-tissue healing. Materials and Methods Titanium implants were inserted epicrestally in the lower jaws of six dogs. Healing abutments with either partially (LP) or completely (LC) laser microgrooved margins or machined surface margins (M) were randomly allocated either to a single (1x)/repeated (2x) dis-/reconnection at 4 and 6weeks (test), respectively, or left undisturbed (control). At 6 and 8weeks, histomorphometrical (e.g. most coronal level of bone in contact with the implant [CBI], subepithelial connective tissue attachment [STC]) and immunohistochemical (Collagen Type-I [CI]) parameters were assessed. Results At control sites, LP/LC groups revealed lower mean CBL (8weeks, 0.95 +/- 0.51 vs. 0.54 +/- 0.63 vs. 1.66 +/- 1.26mm), higher mean STC (8weeks, 82.58 +/- 24.32% vs. 96.37 +/- 5.12% vs. 54.17 +/- 8.09%), but comparable CI antigen reactivity. A repeated abutment manipulation was associated with increased mean CBL (8weeks, 1.53 +/- 1.09 vs. 0.94 +/- 0.17 vs. 1.06 +/- 0.34mm), decreased STC (8weeks, 57.34 +/- 43.06% vs. 13.26 +/- 19.04% vs. 37.76 +/- 37.08%) and CI values. Conclusions It was concluded that (i) LC>LP abutments enhanced subepithelial connective tissue attachment and preserved crestal bone levels, (ii) repeated abutment dis-/reconnection during the initial healing phase (46weeks) may be associated with increased soft- and hard-tissue changes and (iii) LP and LC should be considered using a one abutment, one time approach.