Presented by:Sushant Kumar Swatantra

TRY-IN

For Complete Denture Patients

Definition

Try-in Verification / Aesthetic try-in :

“A preliminary insertion of a removable denture wax- up or a partial denture casting or a finished restoration to determine the fit, aesthetics, maxillomandibular relation.”

– GPT

Trial denture :

“A preliminary arrangement of denture teeth that has been prepared for placement into the patients mouth to evaluate aesthetics & maxillomandibular relationships”

- GPT

Importance:

It is the last opportunity to evaluate many of the previous steps already accomplished.

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Objectives

1) To check and verify the established maxillomandibular relationship:

Verify that centric occlusion and centric relation coincide.

Test for the acceptance of the established vertical dimension of occlusion.

2) To determine if the positions of the teeth and the contours of the denture bases are compatible with the surrounding oral environment.

1) To verify tooth selection and arrangement for proper esthetics and phonetics.

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Various aspects of try in:

Extraoral examination of the trial dentures.

Intraoral examination of the trial dentures.

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Extraoral Examination Of The Trial Dentures

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The master cast

As the finished denture is processed on the master cast. So the master cast should be:

In good shape.

Free from air bubbles or scratches.

Free from wax debris which lead to improper adaptation of the trial denture bases leading to false relationships.

If there are any undercuts present in the cast, these undercuts should be relieved to avoid scratching of the cast by the trial denture bases.

The trial denture bases

Check the following:

The trial denture bases must be stable.

The borders of the trial denture base should be smooth, round, and have no sharp edges.

Also the border should be shaped to conform to the depth and width of the sulci.

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On the articulators

The mounted cast is checked for:

a) Maintaining of the vertical dimension of occlusion

Top of the incisal pin is flush with the upper member of the articulator.

The incisal pin is in contact with the incisal table.

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b) The mounting rings are firmly screwed in their position

c) Moving of the articulator smoothly from centric to eccentric positions without cuspal interlocking.

d) The trial denture bases lie properly on their casts and the teeth meet evenly in centric relation.

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The teeth

It is the dentist responsibility to select the proper shade, and mould of the teeth and to determine that the teeth are set correctly.

Elimination of the excess wax is done to avoid the camouflages of the teeth relationships to overlook the occlusion.

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Intraoral Examination Of The Trial Dentures

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To reduce the risk of cross- contamination, the trial denture should be sprayed with suitable antiseptic solution and washed in running water, before inserted in patient mouth.

1) Checking the trial dentures separately:

Trying- in the upper denture.

Trying- in the lower denture.

2) Checking the upper and lower dentures together.

Maxillary trial denture

Denture base extension:

The labial and buccal extension:

marked overextension of the flanges, will stretch the sulcus tissues and when denture is inserted, leads to elastic recoil resulting in dislodgment of the denture, immediate denture displacement after its seating.

Examination of the extension:

Insertion of the upper trial denture in its place with light pressure on the occlusal surface, move the cheek in functional movement. With the release of the pressure, the denture will fall down.

Need adjustment till little or no movement occurs.

Also under extension of the upper trial denture leads to poor physical retention.

Correction will usually entail making a new final impression.

Provision of the frena {labial and buccal} should be done to ensure that they have adequate clearance.

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Posterior extension

The posterior border of the upper trial denture base should extended from the one hamular notch to the other along the vibrating line of the soft palate, and correctly placed on the master cast.

If the p.p.s is not done before, it should be done at this stage.

Arbitary scraping of the cast and redapting the record base

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Establishment of Posterior Palatal seal

Advantages to placing the seal in Trial dentures :

1)Trial base will be more retentive, this can produce more accurate maxillomandibular records

2) Patients will be able to experience retentive qualities of the trial base, giving them psychologic security about retention

3)Denture wearer will be able to realize the posterior extent of denture.

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Retention

It is noted that the retention of the trial denture is less than that of completed denture, due to:

Absence of a posterior palatal seal.

Poor adaptation of the trial denture base to the tissues.

The trial denture should stay in position when the mouth is opened.

Looseness of the upper trial denture makes it impossible to carry out an accurate assessment of the occlusion {may use denture fixative} especially, in patients with unfavorable anatomical factors.

How to test the retention of upper denture?

Seat the upper trial denture with a firm upward and backward pressure.

Allow the tissues to settle around the denture

Grip the labial and lingual surfaces of the upper denture teeth between the thumb and forefinger

Apply a firm downward vertical pull to dislodge the denture away from the tissues

If the retention is good, dislodgment of the trial denture may be difficult

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Stability

It is tested by applying pressure in a tissueward direction with the ball of the index finger in the premolar and molar regions on each side alternately.

This pressure must be directed at right angles to the occlusal surface where displacement does occur.

Causes of instability

Warpage of the denture base.

Posterior teeth set buccal to the underlying alveolar ridge

Hard unrelieved area in the midline

e.g. torus palatinus.

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Orientation of the occlusal plane

Properly oriented occlusal plane is important to:

Patient esthetics.

Patient comfort

Chewing function

Balance of occlusion

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Orientation of the anterior end of the occlusal plane is determined by esthetics.

The amount of the upper anterior teeth that will be seen during speech and facial expression depends on length and movement of the upper lip.

If the upper lip is relatively long, the natural teeth may not be visible when the lip is relaxed or even during speech.

The movement of the lips during function varies considerably among patient thus , the amount of the upper teeth that will be visible varies for each patient.

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Lower denture trial

Denture base extension:

The lower trial denture extension should be tested with the patient mouth is opened no more than half opened position to allow the surrounding musculature is in an acceptable state of relaxation.

Labial and buccal extensions are checked as for the upper trial denture.

How to evaluate lower denture retention?

Usually the lower denture retention is poor when compared to the upper denture due to:

1. Small denture bearing area

2. The difficulty in obtaining an efficient border seal.

Testing of the lower trial denture retention:

a) Ask the patient to open his mouth slightly and let his tongue touch the cingula of the lower anterior teeth, support the chin of the patient with the left hand and pull the teeth straight upwards to check the retention of the anterior labial and lingual flanges.

b) Tilt the lower trial denture outward from the canine region to test the retention of the opposite retro molar pad.

Lower occlusal plane

In most patients, the incisal edges of the natural lower canines and the cusp tips of the lower first premolars are located at the level of the lower lip at the corner of the mouth when the mouth is slightly open.

The posterior end of the occlusal plane should be at the level of the anterior two thirds of the retro molar pad.

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Tongue space

Natural teeth occupy a position in the mouth where the inward pressure of the lips and the cheeks is neutralized by an equal and opposite outward pressure of the tongue, and it is in this zone of neutral pressure that the artificial teeth must be set (neutral zone).

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To check for the neutral zone in the patient’s mouth, let the patient open his mouth half-way and touch the lower anterior teeth with the tip of his tongue, while his tongue is relaxed. Feel the amount of pressure exerted by the tongue and cheek on the lower teeth, using a plastic filling instrument. Pressure should be roughly equal on the lingual and buccal sides of the teeth.

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Lack of tongue space (cramped tongue)

If the tongue is more mobile than the cheeks will cause greater instability of the lower denture.

Cramped tongue may be due to:

1. Posterior teeth set lingually to the neutral zone.

2. Posterior teeth tilted lingually

3. Posterior teeth too broad bucco-lingual.

Testing of the tongue space:

Ask the patient to raise the tongue. If the tongue is cramped, the denture will begin to rise immediately. As the tongue moves it tries to expand laterally and whenever the tongue moves the denture will move.

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Checking the upper and lower dentures together

It is usually advisable to insert the lower trial denture first and then the upper because there is less chance of having the upper denture drop down.

The patient should be seated in an upright position.

The patient head is not supported by the headrest (the headrest may effect the physiologic rest position of the mandible so, it effect the amount of interocclusaldistance).

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Perfection & Verification of Jaw-relation records

Verifying the Vertical dimension

Checking of labial frenum

Evaluation of Vertical dimension at rest & at occlusion

pre extraction records

amount of inter occlusal distance to which pt. was accustomed

phonetics & esthetics

facial dimension & facial expressions

lip length in relation to teeth

inter arch distance & parallelism of the ridges

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Verifying Centric Relation

Intra Oral Observation of Intercuspation

Pt. is guided into CR by a thumb placed on the anteroinferior portion of the chin & index finger bilaterally on the buccal flanges of the lower denture.

Any Error in CR will be apparent when teeth slide over each other.

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If Error is due to mounting :

anterior teeth if not placed to support lip, are corrected.

vertical overlap of anterior teeth are carefully noted .

posterior teeth are removed from lower occlusal rim

Impression plaster is mixed & placed on the rim.

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Pt. is instructed to close the mouth slowly until the anterior teeth have same vertical overlap as they had before the posterior teeth were removed.

After the plaster is set, rims are removed & this corrected new record is mounted on a articulator.

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Extra oral articulator method

Process :

- Impression material (eg. Aluwax) is placed over mandibular posterior teeth

- wax sealed – denture placed in mouth – just wax portion is immersed in water bath of 130oF for 30 secs – denture placed back in pts mouth - mandible guided into CR so that upper teeth makes contact with the wax – denture removed & chilled in ice water & returned back to patients mouth for re-checking

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– CR is confirmed – Trial dentures are then locked in articulator – opposing teeth should fit in the indentation in every way (anteriorly, posteriorly, laterally & vertically ) if the original CR was correct.

- If it does not fit, mandibular cast should be separated & remounted with last occlusal record.

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Eccentric relation records

It is essential that the movements of articulator should simulate movements of the patient within the range of normal functional contacts of teeth.

For this, condylar elements of articulator must be adjusted so that they approximate condylar guiding factors within TMJ.

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Contact during protrusion

At least three widely separated points or areas of occlusion must exist.

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Contact during lateral movement

Working side Balancing side

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Creating facial & functional harmonywith Anterior teeth

Appearance of entire lower half of face depends on dentures.

After vertical dimension of occlusion & CR has been verified. To obtain a harmonious effect with the patient face, modifications are made in arrangement of teeth

Incorrect positioning of anterior teeth or supporting base material alters normal appearance of vermilion border, the philtrum & mentolabial sulcus

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1. Preliminary selection of artificial teeth

Evaluated for size, form & color

6 anterior teeth should be of sufficient overall width to extend approx. corner of mouth

Color should blend with the face

Any records used in initial selection

should be consulted & changes should

be made if it improves the appearance of patient

2. Horizontal orientation of anterior teeth

Teeth set directly over ridges causes insufficient lip support characterized by:

Drooping of corners of mouth,

Reduction in visible part of vermilion border,

Deepening of nasolabial sulcus,

Wrinkles over vermilion border

Excessive lip support causes stretched lips, tendency of lips to dislodge dentures during function, elimination of normal contours of lips, philtrum & sulci.

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Labial surface of many natural central incisors are about

8 – 10mm from center of incisive papilla

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3. Vertical orientation of anterior teeth

Index finger is placed on incisive papilla with relaxed upper lip & amount of finger covered gives indication of length of upper lip.

Lower lip is better guide for vertical orientation of anterior teeth. Incisal edges of lower canine & cusp tip of lower first premolar are even with corner of mouth when mouth is slightly open.

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If lower teeth are above then,

1. plane of occlusion may be too high

2. vertical overlap of anterior teeth may be too much high

3. vertical space between the jaws may be excessive

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4. Inclination of anterior teeth

Inclination of labial surface of residual ridges seen on edentulous cast gives guide to inclination of anterior teeth

Inclination of anterior teeth parallels the profile line of face

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5. Harmony in general composition of anterior teeth

A. Harmony of dental arch form & form of residual ridge:

I. Square arch form

Central incisors are more nearly in line with canine

4 incisors should have little rotation to give broader effect to teeth

II. Tapering arch form

Central incisors are greater distance forward from canine

rotating or lapping of teeth may be present

III. Ovoid arch form :

teeth seldom rotated

show greater amount of labial surface

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B. Harmony of long axis of central incisors& face

Imaginary perpendicular line from mid point of Inter pupillary line should mark middle of dental arch to be in harmony with face

Mid line also determined by observing position of incisive fossa

Mid line of mandibular central incisor is aligned with that of maxillary incisors

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C. Harmony of the teeth with smiling line of the lower lip

Line formed by upper anterior teeth should follow curved line of lower lip during smiling

Vertical positioning of upper canines are responsible for shape of smile line

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Canines should be arranged in such a way that their incisal edges should be slightly shorter than that of lateral incisors, if not it will create reverse smile line.

Reverse smile line is one of the frequent cause of artificial appearing dentures.

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D. Harmony of opposing lines of Labial & Buccal

surfaces

Asymmetrical symmetry is essential for natural appearing teeth

eg. If maxillary right lateral incisor is set at 5 degrees to perpendicular then opposing lateral should be of same angle but in opposite direction

Labial & buccal lines should be in harmony with lines of face.

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E. Harmony of incisal wear & age

Incisal edges of denture teeth should be grinded to simulate the wear surface that would have developed by the time patient reached his current age.

This wear is placed on teeth where it would have occurred during function & also where it assists in the mechanics of balancing the occlusion

F. Harmony of spaces & individual tooth position

Use of spaces between teeth can be effective in emphasizing individual tooth position & natural appearing arrangement

Spaces designed should be self cleansing

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Conclusion

For the success of a complete denture the teeth should be arranged in harmony with the intraoral and circumoral structures and adjusted so that they occlude and articulate evenly.

After the preliminary arrangement of the artificial teeth on the occlusion rims, it is essential that the accuracy of the jaw relation records made with the occlusion rims be tested, perfected if incorrect, and then verified to be correct.

During Try-in all the procedures carried out in fabrication of denture are verified clinically.

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References

Prosthodontic Treatment for Edentulous patients, 12th edition : Zarb – Bolender

Essentials of complete denture prosthodontics, 2nd edition : Sheldon Winkler

Text book of prosthodontics, Deepak Nallaswamy

http://www.slideshare.net/narendrabasutkar/try-in-complete-dentures

www.gr.dentistbd.com

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