Biomechanical aspects of marginal bone resorption around osseointegrated implants: considerations based on a three-dimensional finite element analysis.
OBJECTIVE
Although bone loss around implants is reported as a complication when it progresses uncontrolled, resorption does not always lead to implant loss, but may be the result of biomechanical adaptation to stress. To verify this hypothesis, a three-dimensional finite element analysis was performed and the influence of marginal bone resorption amount and shape on stress in the bone and implant was investigated.


METHODS
A total of nine bone models with an implant were created: a non-resorption (Base) model and eight variations, in which three different resorption depths were combined with pure vertical or conical (vertical-horizontal) resorption. Axial and buccolingual forces were applied independently to the occlusal node at the center of the superstructure.


RESULTS
Regardless of load direction, bone stresses were higher in the pure vertical resorption (A) models than in the Base model, and increased with resorption depth. However, cortical bone stress was much lower in the conical resorption models than in both the Base and A models of the same resorption depth. An opposite tendency was observed in the cancellous bone under buccolingual load. Under buccolingual load, highest stress in the implant increased linearly with the resorption depth for all the models and its location approached the void existing below the abutment screw.


CONCLUSIONS
The results of this analysis suggest that a certain amount of conical resorption may be the result of biomechanical adaptation of bone to stress. However, as bone resorption progresses, the increasing stresses in the cancellous bone and implant under lateral load may result in implant failure.
Kitamura
Eriko
E
Division of Oral Health in Aging and Fixed Prosthodontics, Department of Oral Health Science, Course for Oral Life Science, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan. eri@dent.niigata-u.ac.jp
Stegaroiu
Roxana
R
Nomura
Shuichi
S
Miyakawa
Osamu
O
D000222:Adaptation, Physiological; D016301:Alveolar Bone Loss / Q000209:etiology* / Q000503:physiopathology; D019245:Compressive Strength; D003198:Computer Simulation; D015921:Dental Implants / Q000009:adverse effects*; D003799:Dental Stress Analysis / Q000379:methods; D020342:Finite Element Analysis; D006801:Humans; D016348:Osseointegration; D013314:Stress, Mechanical; D013718:Tensile Strength
D015921:Dental Implants