The Dynamic Recording of Occlusal Forces Related to Mandibular Movement and Masseter Muscle Activity in Implant Stabilised Overdenture Wearers
Abstract
The initial phase of this study was to develop a force
transducer to investigate occlusal forces during the process of
mastication. The strain gauge transducer was designed to
attach to an Astra implant. A commercial pressure transducer
was also used under one distal saddle of the denture. The
calibration method was designed to record unilateral
masticatory forces regardless of the site of loading. Five
edentulous subjects with implant stabilised mandibular
overdentures and maxillary complete dentures were selected
for the study. Mandibular movements and unilateral Masseter
muscle EMG were recorded. Experiments were designed to
establish within subject differences related to cycle type, food
type, EMG-force relationship, chewing side and cycle phase.
Maximum biting force on a bite gauge and in the intercuspal
position were also recorded. Details of force production during
the closing and occlusal phases improved the description of the
movement cycle and it's relationship to food breakdown. A
classification of chewing cycles is proposed based on the force
exerted in the closing and occlusal phases. This provides
objective criteria for separating crushing, reduction and mush
cycles. Peak forces varied between subjects, but are
characteristic for the type of food within subjects. The different
strategies used by subjects appeared to be partly related to the
force capacity of the individual. The duration of force in the
closing phase was related to the stage in the chewing sequence
and indicated the degree of bolus resistance. A longer force
duration in the closing phase was usually accompanied by a
shorter occlusal duration and consequently an early occurrence
of force peak relative to occlusion. The progressive change of
jaw gap at the beginning of force was consistent with the
expected reduction of particles through the masticatory
sequence. The jaw gape at maximum velocity correlated with
maximum jaw gape but both did not decrease progressively
2
Abstract
through chewing sequences. Conversely, the jaw gape at which
force exceeded 5N showed patterns of progressive decrease
especially with frangible foods. Integrated force and Emg
showed high correlations during mastication, better than peak
values. These correlations were, however, weaker than those
found in static unilateral biting. The slope difference found
between the two conditions contraindicate the use of Emg
activity in static unilateral biting as an index for measuring
masticatory forces.
This study has, thus, validated a method for investigating
masticatory forces and shown their value for analysis of
dynamic aspects of the loads that occurs during mastication.
Authors
Akeel, Riyadh FadulCollections
- Theses [3706]