Nanomechanical properties of bone around cement-retained abutment implants. A minipig study

Aim The nanomechanical evaluation can provide additional information about the dental implants osseointegration process. The aim of this study was to quantify elastic modulus and hardness of bone around cemented-retained abutment implants positioned at two different crestal bone levels. Materials and methods The mandibular premolars of 7 minipigs were extracted. After 8 weeks, 8 implants were inserted in each animal: crestally on one side of the mandible and subcrestally on the other (crestal and subcrestal groups). Functional loading were immediately provided with abutments cementation and prostheses installation. Eight weeks later, the animals euthanasia was performed and nanoindentation analyses were made at the most coronal newly formed bone region (coronal group), and below in the threaded region (threaded group) of histologic sections. Results The comparisons between subcrestal and crestal groups did not achieve statistical relevance; however the elastic modulus and hardness levels were statistically different in the two regions of evaluation (coronal and threaded). Conclusions The crestal and subcrestal placement of cement-retained abutment implants did not affect differently the nanomechanical properties of the surrounding bone. However the different regions of newly formed bone (coronal and threaded groups) were extremely different in both elastic modulus and hardness, probably reflecting their differences in bone composition and structure.