oklusi rim

7/28/2019 oklusi rim

1/6

CLINICAL ADJUSTMENT OF OCCLUSION RIMS

& THE TENTATIVE REGISTRATION OF

MAXILLO-MANDIBULAR RELATIONS

A. DEFINITION:Interocclusal (bite) registration - A tentative registration of the positional

relationship of the mandibular arch to the maxillary arch in centric relation at agiven vertical dimension.

B. PURPOSE:

1. To establish the posterior extent of the maxillary denture.

2. To establish esthetic labial and buccal contours.

3. To establish the occlusal plane.

4. To mark the mid-line, high lip line, and cuspid-to-cuspid distance.

5. To mount the maxillary cast on the articulator in a manner that relates it tocertain cranial landmarks.

6. To measure rest relations.

7. To register the vertical dimension of occlusion and centric relation.

C. INSTRUMENTS AND MATERIALS:

1. Mouth mirror

2. Green handle knife

3. Compound (red handle) knife

4. #7 wax spatula

5. Alcohol torch

6. Baseplate wax

7. Hot water bath

8. Dental floss

9. Flexible ruler

10. Boley gauge

11. Two tongue blades OR a Fox occlusal plane analyzer

12. Face bow assembly

13. Wide flat spatula (trowel)

14. Wax knife

15. Indelible transfer stick

16. Baseplate (triad or acrylic)


2/6

17. Sticky wax

18. Acrylic bur

19. Egg-shaped ball burnisher

D. PROCEDURE:

1. Establishing the Posterior Border of the Maxillary Denture -

The position of the posterior border of the maxillary denture is usually

located in a zone overlaying the tensor veli palatini muscle. The actuallocation is determined by observing the fovea palatini and the line of

deflection between the movable and non-movable tissues. This junction

may be demonstrated by having the patient say "ahh" or by having thepatient hold his nose and blow. The air forces the muscles of the soft

palate to drop sharply. Depending upon the throat form, the length of the

denture will vary from the vibrating line to several millimeters posterior toit as one progresses from Class III to Class I.

In the House Class I palatal throat form it may be possible to extend thedenture as much as six millimeters beyond the fovea palatine. In the Class

II throat form, the posterior border will vary from 2 to 4 millimeters beyond

the fovea palatine. In the Class III throat form, the posterior border of the

maxillary denture must be located at or close to the vibrating line.

The post-dam should vary in width and amount of pressure exerted

according to the resiliency of the underlying tissues. The further posterior

the denture will be extended, the greater will be the need for increasing thedepth of the post-dam. The greatest amount of resilient tissue lies between

the pterygo-maxillary notch and the median line on each side. The

underlying tissue at this point is ordinarily the belly of the tensor veli

palatini muscle. The least resilient tissue is located in the median line areaand is composed mainly of tendinous tissue.

Locate the vibrating line and mark it with an indelible transfer stick.Insert the maxillary baseplate and direct the patient to say "ahh" several

times or blow as above. The mark should transfer to the tissue surface of

the baseplate. Shorten the posterior border of the baseplate to this linewith an acrylic bur until it conforms to this length.

With the aid of an egg-shaped ball burnisher, determine the degree to

which the tissues displace in the patient's mouth just anterior to thepreviously determined posterior border of the maxillary denture. Test

various points along this border from one pterygomaxillary (hamular)notch to the other. Record the extent of displacement of the tissue as to

width as well as depth at the various points. Divide the recordedmeasurements of tissue displacement along the posterior border by two

and mark these points in the palate with the indelible transfer stick then

connect these points.

Remove the baseplate from the mouth. Wet the indelible transfer stick

and enhance the line marking the anterior termination of the proposed


3/6

palatal seal. Reduce the length of the baseplate to the area marked by the

indelible transfer (the posterior mark). Place the adjusted baseplate on the

stone cast and mark with a sharp red pencil the posterior border of thebaseplate on the master cast to designate the posterior extension of the

denture. Remove the baseplate from the cast and check the tissue surface

of the cast. The anterior termination of the post-dam should be lightlyvisible on the cast. Check the location of this mark to ensure that it

corresponds to those measurements of the displacement of the tissues in

the mouth, which were recorded and adjusted by one-half, based uponthese observations. After ensuring the accuracy of this mark, highlight it

with the red lead pencil. A typical post-dam figure on a cast when viewed

from the back of the baseplate would resemble two mountain peaks with a

valley between.

Scrape the post-dam into the cast by means of the cleoid or other sharp

suitable instrument (green-handled knife, Woodson #1, #7 wax spatula,small denture scraper, etc.). Follow these outlines, reducing the amount of

scraping gradually toward the anterior border, so that at the anteriortermination of the post-dam, the stone is cut to a minimum and blends

with the non-scraped palatal area of the cast. The depth should beapproximately 1/2 mm at the midline (midpalatal suture line), 1 mm deep

in the notch area and 1 1/2 mm deep in the displaceable tissue area

between the hamular notch and the midline. This palatal seal willcompensate for the palatal lift of the methyl methacrylate denture due to

acrylic shrinkage resulting from processing.

2. Establishing Esthetic Labial and Buccal Contours:

The final labial contour of the maxillary denture is established by altering

that surface of the contour rim. With the maxillary contour rim in thepatient's mouth, observe the facial contours from both the front and sideviews. If necessary, re-contour the facial surface of the rim until the

desired contour is achieved. Observe the relationship of the rim to the

relaxed upper lip.

3. The Occlusal Plane is established next using the following guidelines:

a) The level of the anterior portion of the occlusal plane usually extends 1mm below the lower border of the relaxed upper lip.

b) The antero-posterior component of the plane is parallel to (but not at the

same level as) a line drawn from the ala of the nose to the tragus of the ear

(ala-tragus line).c) The lateral component of the plane is parallel to a line drawn between

the pupils of the eyes (the interpupillary line).

Trim or add wax to the contour rim to achieve this relationship. With the

contour rim in the mouth, insert the Fox gauge or tongue blade against itsocclusal surface. Study the relationship of the plane indicated by the Fox

gauge to the interpupillary and ala-tragus lines. Placing a tongue blade

between the points indicating where the ala-tragus and interpupillary lines


4/6

is very helpful to visualize the locations of these lines. The rim should be

trimmed or adjusted until it is parallel to both of these guide-planes. Final

adjustment to the guide-planes is achieved by use of the hot flat plane(plasterer's trowel).

4. Establishing the Midline, High Lip and Cuspid Line:

With the maxillary contour rim in the patient's mouth, study the face from

a front view. Divide the philtrum of the lip and mark this point on the

labial surface of the contour rim with a #7 spatula. This is the midline ofthe anterior segment.

The distal surface of the natural maxillary canine is usually located near

the corner of the mouth and a vertical line dropped from the ala of thenose to the occlusal plane will often pass through the middle of the natural

maxillary canine. These landmarks will provide an estimation of the

position for the artificial canines and the width of six artificial teeth on acurve.

Direct the patient to smile and make a horizontal mark at the lower borderof the upper lip. This is the high lip line. This mark is used to estimate thelength of a maxillary central incisor.

5. Relating the Maxillary Arch to Cranial Landmarks:

The maxillary arch occupies a specific position in the cranium and the

mandible is related to the cranium in a specific manner by way of the

mandibular fossa of the temporal bone. The face-bow may be used as a

means of mounting the maxillary cast on the articulator in a manner thatrelates it to certain cranial landmarks.

You will be using the Denar Slidematic face bow. Separate the bite fork

from the face-bow, wrap a cake of softened red compound around the forkand attach the fork to the notched and lightly lubricated wax rim so that

the handle projects from the midline of the rim. The small gold colored

knob on the fork should face up and should match the midline. Insert thecontour rim into the mouth.

Place the bow into position by sliding it onto the fork handle and gently

placing the earpieces into the ears. Position the ala indicator at the ala ofthe nose and secure it. Now tighten the 2 screws on the front of the face-

bow in sequence. Repeat the sequence to make the screws extra tight as

they are prone to loosening up. Loosen the ala indicator and move it aside,then remove the entire face-bow from the mouth.

Attach the cast supporter and face bow supporter to the lower member of

the articulator. Separate the vertical rod with attached face-bow fork fromthe "U" of the bow and attach it to the articulator. Seat the notched and

lightly lubricated maxillary cast into the baseplate and mount the

maxillary cast.

Please note: Before securing the maxillary cast to the articulator, check

the height of the cast, with the baseplate and occlusion rim in place, in a


5/6

denture flask. With a waxed denture attached, there should be at least 1/2-

inch clearance from the top of the flask.

6. To Measure Rest Relation:

In order to establish the proper interarch distance and the required

interocclusal distance or Freeway Space of 2-4mm, it is necessary to studyand measure rest relation of the mandible with respect to the maxilla. Rest

relation is the postural relation of the mandible to the maxilla when the

patient is resting comfortably in the upright position and the condyles arein a neutral unstrained position in the mandibular fossae. Cut two small

triangles of masking tape and place one on the tip of the nose and the other

on the chin at the midline so that their apices face one another. Direct the

patient to sit upright, free of any back or head support, and relax. Insert theupper contour rim. Ask the patient to count slowly from 1 to 10. Then

direct the patient to moisten the lips and swallow. Measure the distance

between the apices of the tape with a ruler or a Boley gauge. Repeat themeasurement several times until a consistent result is obtained. Make sure

that the position of the mandibular triangle is not influenced by the

mentalis muscle contraction. Make a note of the rest positionmeasurement. It will be used the registration of the vertical dimension of

occlusion.

7. To Register the Vertical Dimension of Occlusion (VDO) and Centric

Relation (CR):

Insert the mandibular occlusal rim and adjust its occluding surface until

rest position is achieved. There should be uniform contact between themaxillary and the mandibular rims at this level. At this point it is often

necessary to re-evaluate the previous tentative determination of the

occlusal plane in order to permit proper placement of teeth. The occlusalplane may be altered bearing in mind that the lateral orientation of the

plane remains parallel to the interpupillary line.

The VDO is established by an arbitrary reduction of 2-3mm from thevertical dimension at rest relation. The Freeway Space is evaluated at this

time. Look at the "Closest Speaking Space" - when the patient makes "S",

"SH" and "SH" sounds the posterior portions of the wax rims should justmiss. If this is not the case, the rims should be adjusted accordingly,

keeping in mind anterior esthetics and the "fixed" height of the posterior

mandibular rim.

Remove 2mm of wax from the MANDIBULAR rim from the 1st bicuspidback on both sides and THEN make 2 small non-parallel "V" notches. On

the maxillary rim make 2 small non-parallel "V" notches on both sides andlightly coat with Vaseline. Note that Vaseline is not placed on the

mandibular rim so that the registration will stick to it. Soften Aluwax and

place a "mound" on both sides of the mandibular posterior to a level atleast 2mm higher than the occlusal plane. Insert wax rims in the patient's

mouth and guide the patient's closure into Centric Relation. Remove the


6/6

rims separately and chill them in cold water. Reinsert them and check to

see that the patient closes repeatedly into this record*. Remove the rims

and mount the mandibular cast on the articulator. An alternative method ofrecording this relationship is to squirt Take One bite registration material

onto the mandibular indices after the baseplate/occlusion rims are placed

in the mouth.*Please Note: This procedure should be repeated as the patient frequently

resists being guided into position until he understands what is being done.

It is wise to practice with the patient before the final registration is made.When two records are exactly the same, it can reasonably be assumed that

the record is accurate.

E. PROBLEMS AND ERRORS

1. When the posterior border of the maxillary denture is too short, the seal is

reduced, resulting in a less retentive denture.

2. When the posterior border of the maxillary is too long, the soft palate tissues

are irritated and the movement of the soft palate breaks the seal.

3. When the cast is not cut deep enough for the posterior palatal seal, the denture

will not make sufficient contact with the tissues resulting in poor retention.

4. When the cast is cut too deeply for the posterior palatal seal the denture willdisplace the tissue excessively resulting in irritation of the related tissues and/or

poor adaptation to the hard palate.

5. When the labial surfaces of the contour rim are improperly formed, the anteriorteeth will be mal-positioned resulting in a non-esthetic denture.

6. When the occlusal plane is incorrectly oriented, the teeth will be incorrectly

positioned resulting in 1) decreased stability in either or both dentures; 2) pooresthetics; 3) poor articulation.

7. When the face-bow is improperly positioned the maxillary cast will not be

properly oriented on the articulator.

8. When the VDO is excessive, the Freeway Space is reduced or eliminated

resulting in excessive pressure on the alveolar ridges and premature contacts ofthe teeth during non-masticatory functions.

9. When the VDO is insufficient the Freeway Space is increased resulting in

possible TMJ disturbances, neuromuscular disorders and distortions of facialcontours.

10. Incorrect CR will result in an occlusion of the teeth, which is not in harmonywith the proper position of the condyles in the mandibular fossae.

11. If there is contact between the baseplates in the retromolar pad area of the

mandibular denture base and the maxillary tuberosity area of the maxillary

baseplate, the record will be inaccurate. The record should be immediatelyevaluated after removal from the mouth to ensure this situation has not occurred.

oklusi rim

Documents