Influence of loading and grafting on hard- and soft-tissue healing at immediately placed implants: An experimental study in minipigs.

Abstract

To histologically evaluate the influence of (1) loading and (2) grafting on osseointegration and peri-implant soft-tissue healing at immediately placed, self-cutting progressive tissue-level implants (TLX) in a minipig model. TLX implants (n=56) were immediately placed following the extraction of the mandibular first and second premolars, bilaterally, in a total of n=14 minipigs. In each animal, the implant sites were allocated to the following four groups: (1) unloaded with simultaneous grafting using a bovine bone mineral; (2) unloaded without grafting; (3) loaded with simultaneous grafting; and (4) loaded without grafting. Histomorphometric assessments at 4 and 12 weeks (n=7 animals each) included primary (i.e., bone-to-implant contact [BIC]) and secondary outcome measures (e.g., first BIC [fBIC], junctional epithelium length [JE], connective tissue contact length [CTC], biological width [BW=JE + CTC]). At 4 weeks, mean BIC values ranged from 74.5± 11.6% in Group 2 to 83.8± 13.3% in Group 1, and, at 12 weeks, from 75.5%± 7.9% in Group 2 to 79.9± 8.6% in Group 1. Multivariate linear mixed regression did not reveal any associations between BIC and implant loading or grafting at 4 and 12 weeks. At 12 weeks, significantly higher fBIC values were noted in Group 2 when compared with Group 1. All groups showed comparable JE, CTC, and BW values. Implant loading and grafting had no major effects on osseointegration and peri-implant soft tissue healing at TLX implants.