Jaw relation determination
The jaw relation determination (outdated bite registration ) is used in dentistry and dental technology to assign upper and lower jaw models. Model holder fixators , occluders , mean value articulators , partially adjustable articulators and fully adjustable articulators are available for this. The determination of the jaw relation is an important step in the production of indirectly (outside the mouth) produced restorations such as inlays , partial crowns , crowns , bridges , implant-supported dentures as well as partial and full dentures . In addition, bite splints are articulated after the jaw relation has been determined. After an impression , models of the upper and lower jaw are made. They are mounted in an articulator in a relation that reflects the patient's situation as precisely as possible, the bite height .
Classification
A distinction is made between the determination of the jaw relation in the toothless patient and that in the partially and fully edentulous patient. With the classification according to Eichner (1955) a functional division of the gap bites into three groups is carried out according to the existing support zones . A complete set of teeth has four support zones, whereby the front teeth are not taken into account. A support zone consists of two opposing pairs of teeth, i.e. four teeth:
- 1. Support zone: premolars on the left side
- 2. Support zone: premolars on the right side
- 3. Support zone: molars on the left side
- 4. Support zone: molars on the right side
This results in three groups of bite that are decisive for the type of jaw relation determination:
- Group A: Antagonistic contact in all support zones
- Group B: Antagonistic contact not in all support zones
- Group C: No antagonistic contact
Procedure
Hand-guided jaw relation determinations
The hand-held jaw relation determination is opposed to the relation determination by means of central support pin registration . The hand-guided jaw relation determination and the coding on the arrowhead tip result in different lower jaw positions. The hand-guided jaw relation determination is carried out with the Lauritzen handle (chin guide handle, English : Lauritzen's handle, technique for guiding the lower jaw , named after the American dentist Arne Lauritzen ) in the centric condyle position of the caput mandibulae . To do this, the dentist moves the patient's chin into this position with the thumb bent. The same can be done with the Dawson handle (lower jaw guide handle, English: Dawson's handle, after the American dentist Peter Dawson). With this method, the lower jaw is grasped with both hands at the angle of the jaw and guided towards the skull with the thumbs.
Arrow angle recording
With the support pin registration (arrow angle recording) the support pin is worked into the upper jaw wax plate, the registration plate into the lower jaw wax wall. After closing, maximum protrusion, maximum retrusion and, subsequently, lateral movements to the right and left are carried out. The support pin is brought into contact with the established adduction point and the templates are connected to one another. The models are articulated in this position.
Dissolution of the support zones
If the support zones have to be broken up during a dental prosthesis treatment, for example by grinding the teeth for crowns, the original bite height is recorded using so-called plastic keys before the complete grinding. At least one three-point contact must be fixed that comes as close as possible to an equilateral triangle . With its help, a stable position of the upper and lower jaw can be restored. The three fixation points must be on the left and right in the posterior region and one in the anterior region. With the help of these "keys", the models can then be articulated at the original distance, in the original jaw relation, without having to redefine it.
Determination of the jaw relation in fully edentulous patients
In patients in group A, i.e. fully edentulous patients or patients with largely preserved support zones, the jaw relation is determined with maximum intercuspation . Carrier plates made of plastic , tin or wax are used for this. Wax carrier plates in combination with aluminum wax or zinc oxide-eugenol preparations as encryption material is slightly better than the plastic plates or tin foils . The plaster models are positioned in relation to each other in the impressions in the carrier plates that were created by the clenching and plastered into the articulator. Erasing (grinding in) the articulated models until the same localized contacts appear as in the mouth appears to be expedient.
Determination of the jaw relation in partially edentulous patients
The jaw relation determination in partially edentulous patients is also carried out - as far as possible - in maximum intercuspation. The fewer support zones there are, the greater the risk of an imprecise determination of the jaw relation. When actively biting, the body of the lower jaw is twisted depending on the biting force exerted. The aim is therefore a closing movement guided by the dentist with the chewing muscles as relaxed as possible. Carrier plates made of plastic, tin or wax are used to fix the corresponding position. Wax carrier plates in combination with aluminum wax or zinc oxide eugenol preparations as encryption material are slightly better in comparison to plastic plates or tin foils. The erasing of the articulated models until the same localized contacts appear as in the mouth appears to be expedient here too. In addition, regardless of the method used, the patient's ability to adapt, i.e. their ability to adapt, is decisive for the success of the treatment.
Manufacture of a partial denture in the articulator
Assembly of an upper jaw model in an individual articulator
Assembly of the lower jaw model using registration templates
Creation of a transfer sheet
Determination of the jaw relation in the edentulous patient
Determining the jaw relationship in toothless patients is particularly difficult because the loss of all teeth or all teeth in one jaw or residual teeth in both jaws, which are not in contact, mean that the three-dimensional relationship between the upper and lower jaw, which is secured by the occlusion, is no longer possible exists. These are patients of group C. The aim of the production of total dentures is to achieve a new three-dimensional assignment of the lower jaw to the upper jaw that comes close to the original dentition and appearance, does not damage the stomatognathic system and is tolerated by the patient and his environment. A distinction is made between the vertical and horizontal restoration of the jaw relation.
Restoration of the vertical jaw relation
Of many of the methods described in the literature, the determination of the closest speaking distance, the resting position, dominates for determining the vertical jaw relation . When the chewing muscles are relaxed, the lips should touch. The distance is determined, for example, by the Zielinsky compass , with which the distance between two points is measured. For this purpose, the distance is measured extraorally on the skin, for example between the tip of the nose and the tip of the chin. This distance is usually three millimeters larger than the distance at maximum intercuspation. However, this distance does not necessarily have to correspond to the actual intraoral conditions. If the bite has sunk - for example due to abrasion - an orientation to the resting position may be incorrect. In this case, the original bite height should also be restored as best as possible according to functional and aesthetic criteria. Existing full dentures that are to be replaced can also be helpful for the reconstruction. In particular, the patient is already used to this jaw relation.
The procedure consists in applying wax walls, which are supposed to simulate a prosthesis, on the upper and lower jaw and removing the wax step by step until the two wax walls are clenched, the distance between the previously defined reference point on the nose and nose is about three millimeters shorter Chin can be reached. With the help of the registration templates (formerly: bite templates), the dental technician can mount the jaw models in an articulator at the desired distance .
Determination of the vertical dimension in the toothless. Stickers on the tip of the nose and chin
Measurement of the floating position with the Zielinsky compass
Registration templates with wax walls; left for the lower jaw, right for the upper jaw
Restored jaw relation through full dentures
Restoration of the horizontal jaw relation
Since the teeth can no longer be used to adjust the horizontal relationship in the toothless person, the musculature dominates the determination of the position, or the practitioner positions the lower jaw by guiding it into the respective limit position of the temporomandibular joints. The limit position of the lateral movements (sideways movements) of the lower jaw is determined with further bite templates in that the patient bites on the bite walls in the limit positions. In the respective positions, the wax walls are connected to one another in the mouth. In the individually adjustable articulator, the dental technician can also set the limit positions of the lower jaw after mounting the models in the habitual position.
history
The development of the articulator , which, as a chewing simulator, should enable the movements of the lower jaw and thus the reproduction of the chewing pattern, began with an occludator that only allowed the opening and closing of the dentition to be imitated. In 1893 Julius Parreidt described in detail various methods common in the 19th century, initially using a door hinge . After preliminary work by Daniel Evans , William Gibson Arlington Bonwill (1833–1899) from Philadelphia developed the first above-average articulator in 1864. It was Bonwill who coined the term articulation and replaced the older term occlusion . The Gysi Simplex articulator developed by the Swiss dentist Alfred Gysi (1865–1957) around 1910 was to prove to be a milestone. Due to the condylar guide surface in the lower part and the joint drum in the upper part, these types are referred to as so-called non-arcon articulators , as the movements take place in reverse to the anatomical-physiological process in the real joint. The Whip-Mix articulator, which is based on the same principle, or the School Articulator Munich (SAM) became better known. Over 100 different articulators have been developed over the past 150 years. With the introduction of gnathology , Arne G. Lauritzen , Peter K. Thomas , Charles E. Stuart and Harry Lundeen took over the further development with the increasing use of face bows and the use of support pin registrations in toothless patients . In Germany, Axel Bauer and Alexander Gutowski were the first to adopt these concepts.
outlook
There is a lack of prospective, double-blind clinical studies that compare several different methods and include a larger sample. The reconstruction of the occlusal position remains rather imprecise. An adaptation to the new lower jaw position or to the new dentures by the patient is necessary after the integration of a prosthesis.
Individual evidence
- ↑ University of Greifswald, Classification according to Eichner, p. 196 ( Memento of the original from November 17, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF; 193 kB). Retrieved November 11, 2015.
- ↑ Jens Christoph Türp, Hans Jürgen Schindler: Vertical and Horizontal Jaw Relation in Reconstructive Dentistry , Switzerland Monthly Dentistry, Vol 116: 4/2006. Retrieved November 15, 2015.
- ↑ G. Herdecke: jaw relation determination, model assembly, scaffolding fitting ( memento of the original from November 17, 2015 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. , Universitätsklinikum Hamburg-Eppendorf, p. 43 ff. Accessed on November 16, 2015.
- ↑ Determination of the jaw relation , Scientific Communication of the German Society for Prosthetic Dentistry and Biomaterials , September 2010. Accessed on November 11, 2015.
- ↑ András Szentpétery: Three-dimensional mathematical movement simulation of articulators and their application in the development of a "software articulator" , University and State Library of Saxony-Anhalt, Habilitation thesis (2000), pp. 6–37. Retrieved November 11, 2015.
- ↑ H. Stemmann: The future needs an origin - from the bent door hinge to the virtual articulator ( Memento of the original from November 17, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , 44th Annual Meeting of the Dental Technology Working Group, June 2015, pp. 6–13. Retrieved November 11, 2015.
- ↑ Alexander Gutowski, Axel Bauer, Gnathology: Introduction to Theory and Practice . Quintessenz-Verlag, 3rd edition 1984, ISBN 3-87652-158-0 .
