The International Journal of Oral & Maxillofacial Implants, 3/2010
PubMed-ID: 20556244Seiten: 461-472, Sprache: Englisch
Purpose: The inter-relationships between various implant and bone parameters were evaluated for their influence on the von Mises stress distribution within the mandible using the finite element procedure. The maximum compressive stresses in cancellous and cortical bone were compared to the published stress-strain data to determine bone fracturing status when the maximum (traumatic) loading is applied.
Materials and Methods: Parameters considered herein include the implant diameter and length. Also considered are Young's modulus of cancellous bone and that of cortical bone, along with its thickness. The implant-bone system was modeled using two-dimensional plane strain elements, 50% osseointegration between implant and cancellous bone was assumed, and linear relationships were assumed between the stress value and Young's modulus of both cancellous and cortical bone at any specific point within the mandible.
Results: Implant length was more influential than implant diameter within cancellous bone, whereas implant diameter was more influential in cortical bone. A ranking of all the parameters indicated that the applied masticatory force had a more significant influence on the stress difference, in both cancellous and cortical bone, than all other parameters. Young's modulus of cortical bone and implant length were least influential in cancellous and cortical bone, respectively. Under traumatic loading, cancellous bone fractured for all parameter combinations. When all parameters were set to their average values, the cortical bone did not fracture under traumatic loading. However, it fractured if all the parameters were all set to the minimum values.
Conclusion: Quantitative evaluation and ranking of the major implant and bone parameters will help provide practical guidelines that are useful for the design and testing of dental implants. The study may also be of interest to dental professionals in evaluating possible implant placement options under various clinical scenarios.
Schlagwörter: bone density, finite element analysis, implant diameter, implant length, masticatory force, stress characteristics, traumatic loading
The International Journal of Oral & Maxillofacial Implants, 5/2009
PubMed-ID: 19865627Seiten: 866-876, Sprache: Englisch
Purpose: The complicated relationships between mandibular bone components and dental implants have attracted the attention of structural mechanics researchers as well as dental practitioners. Using the finite element method, the present study evaluated various bone and implant parameters for their influence on the distribution of von Mises stresses within the mandible.
Materials and Methods: Various parameters were considered, including Young's modulus of cancellous bone, which varies from 1 to 4 GPa, and that of cortical bone, which is between 7 and 20 GPa. Implant length (7, 9, 11, 13, and 15 mm), implant diameter (3.5, 4.0, 4.5, and 5.5 mm), and cortical bone thickness (0.3 to 2.1 mm) were also considered as parameters. Assumptions made in the analysis were: modeling of the complex material and geometric properties of the bone and implant using two-dimensional triangular and quadrilateral plane strain elements, 50% osseointegration between bone and implant, and linear relationships between the stress value and Young's modulus of both cancellous and cortical bone at any specific point.
Results: An increase in Young's modulus and a decrease in the cortical bone thickness resulted in elevated stresses within both cancellous and cortical bone. Increases in the implant length led to greater surface contact between the bone and implant, thereby reducing the magnitude of stress.
Conclusions: The applied masticatory force was demonstrated to be the most influential, in terms of differences between minimum and maximum stress values, versus all other parameters. Therefore loading should be considered of vital importance when planning implant placement.
Schlagwörter: cancellous bone, cortical bone, dental implants, finite element technique, stress distribution characteristics
The International Journal of Oral & Maxillofacial Implants, 5/2007
PubMed-ID: 17974106Seiten: 729-735, Sprache: Englisch
Purpose: Bone collectors are used to harvest bone debris for grafting procedures during implant surgery. The particulate bone debris gathered through filtration has been frequently used in minor regenerative surgical procedures. Nevertheless, the biological potency of such grafts is still unclear. The objective of this study was to systematically review the use of bone collectors in implant dentistry, focusing on the quantity, quality, and bacterial contamination of the bone collected.
Materials and Methods: Following the production of a detailed protocol, screening and quality assessment of the literature were conducted in duplicate and independently. The outcome measures that were assessed were: (1) quantity of collected debris, (2) quality of the collected bone debris, and (3) bacterial contamination. Results: There is a limited amount of information on the nature of bone obtained through collectors. Eleven studies satisfied the inclusion criteria. Bone collectors are able to retain a small amount of bone for minor surgical procedures. The presence of vital bone cells has not been demonstrated routinely, while consistent bacterial contamination has been observed.
Discussion: Bone collected through bone filters appears to be sufficient for small regenerative procedures. Clinicians should bear in mind that presence of bacterial pathogens is always shown with the use of bone collectors. Presurgical chlorhexidine oral rinsing and a strict aspiration protocol must be used to minimize the bacterial contamination of the debris collected.
Conclusions: Although bone collectors are capable of amassing small amounts of bone, the vitality of this bone could not be consistently demonstrated and the collected debris was always contaminated by bacteria. Therefore, the bone debris amassed in bone collectors is not an ideal grafting material and should be utilized with caution.
Schlagwörter: bone collectors, bone traps, dental implants, oral surgery, systematic review