Fig。 4 – Equivalent strain distribution in the cortical bone of model C under three loading conditions ((A) VM, (B) IM and (C) VI)。 Colours indicate level of strain from dark blue (lowest) to red (highest)。 The arrows show the sites at which peak strain values occur。

Fig。 5 – Equivalent strain distribution in the cortical bone of model D under three loading conditions ((A) VM, (B) IM and (C) VI)。 Colours indicate level of strain from dark blue (lowest) to red (highest)。 The arrows show the sites at which peak strain values occur。

maximum strain values in peri-implant bone under IM were higher than under VM or VI。 However, under VI, the maximum strain value in model B was as high as that in model D, and was located on the lingual side of the peri-implant cortical bone (Fig。 3C)。 When model D was loaded on the incisors, the peak strain values in the cortical bone were found to be concentrated around the distal two implants (Fig。 5C), and were nearly three times higher than those around the central two implants。

3。2。 Stress in abutments

The maximum equivalent stress values in the abutments under three loading conditions in each model are shown in Table 4。 It was notable that under VI, the maximum stress value in model B was about three times as high as in the other models and was located on the labial side of the interface between the abutment and the nylon   replacement。

Loading condition Model A Model B Model C Model D

VM 13。62 20。1 21。14 21。46

IM 17。03 23。59 29。05 28。32

VI 15。41 76。57 26。33 21。13

Loading condition Model A Model B Model C Model D

VM 0。2641 0。3268 0。2753 0。2474

IM 0。2544 0。3462 0。2835 0。2454

VI 0。1984 0。4529 0。2266 0。2095

Loading condition Model A Model B Model C Model D

VM 861。9 1183 1128 1099

IM 1044 1125 1041 992。4

VI 793。4 200。4 303。7 236。3

3。3。 Pressure on the mucosa and the contact area between the denture and the mucosa