Nankali Masticatory Force Systematisation
Many problems in an oral environment are as a result of over loaded pressure and its incorrect distribution. This issue creates difficulties in dental treatment, particularly, in restorative dentistry and prosthetics such as teeth abrasion, periodontal disease, loose teeth, and defect teeth arch. Having considered these issue, it is essential to realize how important is to know the size of masticatory force on different locations.
Evidently, a complex plan of treatment, considering all possible aspects, will guarantee the effectiveness of patient treatment. By increasing the number of analyzed impact factors for treatment, the probability of needing further treatment will be decreased significantly. In order to have a suitable prostheses design, in particular, removable partial dentures, many factors are required to be considered. Characteristic of masticatory force is one of the main issues, which needs to be examined.
The size of a masticatory force depends on the amount of diametrical section of involved muscles, such as; Temporalis, Buccalis, Masseter. These muscles are the main factors for creating a mastication force. The total amount of a diametrical section of this group of muscles (closers) in one side is estimated approximately 19.5cm. In addition, it has been determined that a 1cm2 diametrical section of skeletal muscle can produce a force to maximum 100N. Accordingly, the logical mastication force of half side of tooth arc can be roughly 1950N. This means that the total force in oral environment can be increased by up to approximately 3900N.
All of the above-mentioned muscles (closers and openers) are connected to the mandible, where the pressure on molars and premolars is greater than on frontal teeth.
More importantly, mastication forces as a result of affecting all muscles play an important role in balancing mandible positions during different moment of biomechanical actions.
The mandible biomechanical movement was carefully studied by Dr. Ali Nankali in 2000.
Analyzing all effective elements together and using the balance equation of hard materials in all moments (ΣM) concerning horizontal axis was made for further calculation.
The result of testing was registered and is demonstrated in chart 1. These tests were fulfilled on patient models in the Orthopedic Stomatology laboratory of National Medical University (NMU) in Kiev.
The study of tolerant forces determined that the maximum pressure (caused by contraction of masticatory muscles) on teeth is approximately equal to their allowed physiological pressure in non defect condition, and it has also a relationship with the amount of horizontal surface of roots slide.
This study resulted a systematisation in which the force of Masticatory is divided in two main groups, with physiological or pathological condition. The physiological Masticatory Force with is divided into three different subgroups according to their localizations, anterior, general (covering the entire arch) and posterior part of arch, which is also divided into two different groups; unilateral and bilateral.