Determination of central occlusion with partial and complete absence of teeth: methods for measuring the ratio of jaws

Determination of the central occlusions - a necessary process that has to be addressed when planning and constructing any type of denture structure. None of the measures to optimize the condition of the teeth can be complete without this procedure.

It is she who determines how correctly it will function crown or removable denture, whether they will cause inconvenience when using their owner.

Determination of central occlusion with partial absence of teeth occurs according to the principles that depend on the group of defects of the individual dentition.

The classical method for determining central occlusion with wax templates

The method for determining central occlusion is dictated by the urgent need to manufacture a prosthesis (partial or removable), to alleviate the condition of a particular patient.

The methods used are aimed at the most accurate determination of the moment of the position in which the following occurs:

• simultaneous closure of all preserved surfaces;
• even distribution of tension in the muscles of the jaws;
• full contact of the dentition and their elements.

Correct determination of such a position in the future will allow avoiding emerging problems with the facial joints (especially with temporomandibular). This is the only way to achieve the required functionality, completely eliminate the likelihood of deviations, which is great if measurements and definitions are made incorrectly.

The classic method for determining central occlusion is the use of roll-on wax templates.

The practicality of their use has long been proven and appreciated by dentists. But experienced professionals with extensive practical experience recognize that the method has certain drawbacks (as well as every method developed by a person to achieve practical goals).

There are always risks of inaccuracies or mistakes when applying wax templates. They can be caused by atrophy. alveolar bone, lack of proper stability, displacement of the wax device (with insufficient experience of the doctor), or its deformation under the influence of the natural temperature effect of the patient's mouth.

Determination of central occlusion according to Betelmann contains not only guidelines for carrying out manipulations, but also four options of complexity, taking into account the presence or absence of pairs antagonist teeth.

Determination of the prosthetic plane

It starts with determining the height of the anterior segment, for which the height of the upper bite ridge is measured. The main reference point is the length of the upper lip, it is measured and calculated, and a conditional line is applied to the applied template with a special spatula, for this there are certain criteria, focused on individual peculiarities.

Determination of bite on toothless jaws takes into account the length of the upper lip, and adjustments in the height of the OB are made to achieve the required parameters.

The prosthetic plane is a conditional line, the accuracy of its modeling depends on the doctor's skillful manipulations with the bite rollers and correct calculations.

Determination of the height of the central occlusion

A process that is not particularly difficult if some of the teeth are lost and you can focus on the antagonist teeth.

However, complete loss presupposes the impossibility of using such a method. The more difficult the situation with the presence of dental units, the greater the proportion of work falls on accurate calculations and the search for a favorable location in the sagittal, frontal and horizontal planes.

The risk of overestimating or underestimating the bite height (CO) is too great. And the admission of such errors inevitably leads to disturbances in the process of eating, diction, rapid fatigue from use.

For the manufacture of prostheses for a person without teeth, reference lines applied to the measuring rollers and central ratios determined by measuring facial features are taken into account.

Determination of bite on toothless jaws, video:

Determination of the central position of the jaws

It is performed at the moment when the head of the joint is in a physiological position and is correctly located in the glenoid fossa. This landmark is always present in humans, and in the absence of teeth, one can reliably focus only on the central ratio.

His doctor determines by pressing on the roller in the area of ​​the lower jaw and pushing the corners of the mouth. Then he allows the patient to do this manipulation on his own, until he is convinced that the required parameter is determined correctly.

Orthopedics of the patient's teeth is not only the restoration of the anatomical structure. Prosthetics should restore all functional features and norms of diction, smile, patient's face, possibilities used for healthy food consumption.

This requires taking into account many individual factors, ignoring which can lead to errors.

Hence, it becomes necessary to carry out the most accurate calculations and measurements for the most functional and aesthetic restoration of the patient's teeth.