In vivo forces on implants influenced by occlusal scheme and food consistency

The aim of this study was to investigate whether systematic modifications of occlusal features or food consistency are suitable to reduce the loading of implants.

Ten healthy subjects, each of whom had a gap in the chewing center (second premolar or first molar) of one lateral dental arch, were provided with fixed partial dentures (FPD) on two ITI implants. Strain gauges attached to the abutments recorded forces in three dimensions. In each person, the original FPD was successively replaced by three FPDs with different occlusal schemes: The first had steep cusps, the second had flat cusps, and the third had the same cuspal inclination as the first but a narrow occlusal surface. Subjects chewed gummy bears and bread as a tough and a soft bolus, respectively.

In chewing of gummy bears, the mean vertical forces of the three FPDs ranged between 264 and 284 N and were not significantly different. The mean bending moments amounted to 27 Ncm and 24 Ncm with steep and flat occlusal slopes, respectively. With the narrow occlusal surface, the bending moments were reduced by 48%, to a mean of 11 Ncm. Chewing of bread yielded similar relations with lower mean vertical forces and bending moments.

Narrowing the orovestibular width of the occlusal surface by 30% caused a significant reduction of lateral force components. A reduced orovestibular width of the occlusal surface is recommended in unfavorable loading conditions. In addition, the chewing of soft food is suggested during the healing period in cases of immediate loading.