Evaluation of functional dynamics during osseointegration and regeneration associated with oral implants

Abstract

Objectives: The aim of this paper is to review current investigations on functional assessments of osseointegration and assess correlations to the peri-implant structure.

Material and methods: The literature was electronically searched for studies of promoting dental implant osseointegration, functional assessments of implant stability, and finite element (FE) analyses in the field of implant dentistry, and any references regarding biological events during osseointegration were also cited as background information.

Results: Osseointegration involves a cascade of protein and cell apposition, vascular invasion, de novo bone formation and maturation to achieve the primary and secondary dental implant stability. This process may be accelerated by alteration of the implant surface roughness, developing a biomimetric interface, or local delivery of growth-promoting factors. The current available pre-clinical and clinical biomechanical assessments demonstrated a variety of correlations to the peri-implant structural parameters, and functionally integrated peri-implant structure through FE optimization can offer strong correlation to the interfacial biomechanics.

Conclusions: The progression of osseointegration may be accelerated by alteration of the implant interface as well as growth factor applications, and functional integration of peri-implant structure may be feasible to predict the implant function during osseointegration. More research in this field is still needed.

Figure 1. Biomechanical assessments for oral implant osseointegration

(a) tensional test, (b) push-out test, (c) pull-out test, (d) insertional/removal torque test, (e) Periotest, and (e) resonance frequency analysis (RFA).

Figure 2. The in vivo finite element homogenization procedures for functional apparent moduli

(a) The cylinder implant was pushed out (following the direction of the red arrow) from the jaw bone, and (b) the load-displacement relationship was recorded for calculating the interfacial stiffness (dash line, referred to the slope of the curve before the yielding point). (c) The three-dimensional (3-D) peri-implant structure was identified after removing the implant. (d) The finite element model was developed from projecting the peri-implant structure and interfacial information (microscopic model, upper panel) with the suspension boundary condition (pink marks on the peri-implant tissue border). In the optimizing model (lower panels), the peri-implant layer of interest was homogenized (yellow peri-implant regions), and the effective stiffness was calculated from the numerical approximation (to the microscopic model) under the implant loading condition (light blue arrows). Abbreviations: TI: titanium implant; PI: peri-implant tissue; Gr: granulation tissue in peri-implant area; FBAM: functional bone apparent modulus; FCAM: functional composite tissue apparent modulus