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The reaction to the use of finite element analysis (FEA) in the study of the human body has been particularly enthusiastic. Of equal and challenging complexity is the investigation of load/stress distribution and morphological distortion of the human mandible under functional loads. Furthermore, the mandible also impacts directly on body function and esthetics, playing a vital role, such as mastication and speech. The application of FEA to the biomechanical investigation of the oral systems, such as human teeth and mandibular bone remodeling, began in the early 1970s. The clinical significance of jaw deformation is unknown. The primary concern is that deformation might result in an ill-fitting superstructure or the creation of harmful strains in the patient-implant complex. Although mandibular implant treatment has a high success rate, the possibility of failure caused by these dimensional changes and the related micromotion cannot be ignored., (© 2014 Wiley Publishing Asia Pty Ltd.)

Objective. This investigation aims to evaluate the changes in stress magnitudes and distributions on Partially Stabilized Zirconia (PS-ZrO2) dental implants and bridges and on the mandible caused by fibrous encapsulations during clenching. Materials and methods. Four 3.26 mm diameter PS-ZrO2 dental implants with lengths of 12 mm were modelled and placed in the second premolar and first molar region on both sides of the mandible model. A rigid zirconia bridge with a thickness of 0.5 mm connects the PS-ZrO2 dental implants placed in the second premolar and first molar. Four periodontal ligament (PDL) case studies were examined: PDL in the second premolars; PDL in the first molars; PDL in both the second premolars and first molars; and no PDL present. Results. The results reveal the magnitudes and distributions of stresses on the dental implants and connecting bridges were governed by the PDLs. A significant drop in stress levels were recorded when the PDL encapsulates the roots of the dental implants. Of the four PDL case studies, it was found that when the PDLs are present in both the second premolars and first molars the lowest stress magnitudes are generated. The analysis also revealed that, during the healing process after implant insertion and the result of fibrous encapsulation, the dental implant system will experience a varying amount of stress levels. Conclusion. This study was intended to produce more insight into the influence of the PDL on the changes in stress distribution on the dental implant system during clenching. [ABSTRACT FROM AUTHOR]

Objective. The purpose of this paper is to compare the differences in stress between Ti-6Al-4V and PS-ZrO2 dental implant during clenching and whether these changes are clinically significant to limit the use of zirconia in oral implantology. Materials and methods. The model geometry was derived from position measurements taken from 28 diamond blade cut cross-sections of an average size human adult edentulous mandible and generated using a special sequencing method. Data on anatomical, structural, functional aspects and material properties were obtained from measurements and published data. Ti-6Al-4V and PS-ZrO2 dental implants were modelled as cylindrical structure with a diameter of 3.26 mm and length of 12.00 mm was placed in the first molar region on the right hemimandible. Results. The analysis revealed an increase of 2-3% in the averaged tensile and compressive stress and an increase of 8% in the averaged Von Mises stress were recorded in the bone-implant interface when PS-ZrO2 dental implant was used instead of Ti-6Al-4V dental implant. The results also revealed only relatively low levels of stresses were transferred from the implant to the surrounding cortical and cancellous bone, with the majority of the stresses transferred to the cortical bone. Conclusion. Even though high magnitudes of tensile, compressive and Von Mises stresses were recorded on the Ti-6Al-4V and PS-ZrO2 dental implants and in the surrounding osseous structures, the stresses may not be clinically critical since the mechanical properties of the implant material and the cortical and cancellous bone could withstand stress magnitudes far greater than those recorded in this analysis. [ABSTRACT FROM AUTHOR]