Evaluation of the Trial Dentures

8/4/2019 Evaluation of the Trial Dentures

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We must be sure that:1. Mounting rings are firmly secured in position2. Incisal pin touches the incisal table

3. The trial denture bases lie properly on their castsand the teeth are in good intercuspation4. The sagittal and lateral condylar path inclinations

coincide with the reading obtained from the

eccentric relation records (with adjustablearticulator)5. The articulator moves smoothly from centric to

eccentric position without interlocking of the teeth



Checking casts

The casts should be in good shape, free fromair bubbles and scratches, undercuts should berelieved.



Checking the trial denture bases on the cast

1. The borders must be smooth and rounded2. Trial bases must be stable



Checking the teeth

The anterior teeth plays an important part in threeobject esthetics, incision and phonetics



The occlusion of the teeth on the articulator should meet thefollowing specifications in an normal class I jaw relationship

1. The upper anterior teeth should overlap the lower anteriorteeth by about 1-2 mm, in both horizontal and verticalplanes without contact.

2. The mandibular incisors do not protrude beyond the labialvestibule.3. The labial surfaces of the six anterior teeth should present a

curve when viewed from the occlusal surface4. The buccal cusps of the upper premolars and molars should

overlap those of the lower5. The buccal cusps or the central grooves of mandibular

premolars and molars should be positioned on the crest ofthe ridge for better stability of lower denture.

6. The lower posterior teeth should be set vertically on theridges.



7. The posterior teeth should be in maximumintercuspation8. Each tooth is opposed by two teeth, except for the

lower central incisor and the upper last molar.9. The height of the occlusal plane with the line joining

the incisal tip of the mandibular canine to theretromolar pad10. The posterior end of the occlusal plane with the

junction between the middle and the distal thirds of theretromolar pad

11. No teeth should be placed on the upward inclines ofthe lower ridge12. There are uniformly balanced occlusal contacts

between the maxillary and mandibular posterior teeth.The teeth should move from centric to eccentric

positions without interlocking of cusps.



Concave surfaces between the marginalgingival areas and denture borders are mostfavorable for maximum retentive effects of thecheeks, lips and tongue.



Concave surfaces between the marginal gingivalareas and denture borders are most favorablefor maximum retentive effects of the cheeks,

lips and tongue.



1. Trying in the lower denture

a. Extensioni. The buccal and labial extension – Hold

the denture in place with lightpressure on the occlusal surface of the

teeth, and move the cheek on one sidegently, but firmly, upwards andinwards.



ii. The lingual extension – Hold thedenture in placed with pressure andask the patient to protrude his tongue

sufficiently to moisten his lips. Next,ask the patient to put the tip of histongue as far back on his palate aspossible.



iii. Posterior extension – Ensure that the heels ofthe lower denture are extended as high upthe ascending ramus of the mandible as is

practicable. The purpose of this is to buttressthe denture against the backward pressure ofthe lower lip.



iv. Under extension – Shown by the presence ofa gap between it and the functional positionof the surrounding mucous membrane.



b. Stability-- This test is used to determine if occlusal

stresses will be transmitted outside the ridge.

Apply pressure with the ball of the finger inthe premolar and molar regions of each sidealternatively. This pressure must be directedat right angles to the occlusal surface.



c. Retention-- Asking the patient to open his mouth with the

tongue touching his mouth with the tongue

touching the cingulae of the lower anterior.The denture is then pulled upward (whilesupporting the chin.



d. Tongue space-- Natural teeth occupy a position in the mouth

where the inward pressure of the cheeks and

lips is equaled by the outward pressure of thetongue, and it is into this zone of neutralpressure that the artificial teeth must beplaced.



The causes of tongue cramping

1. Posterior teeth set inside the ridge2. Molar teeth which are too broad buccolingually3. Molar teeth leaning inwards.Difference between over extension and cramped

tongue --------for the former it needs moremovement

Height of occlusal plane



Trying in the upper denturea. Extension

1. The buccal and labial periphery is checked asfor the lower denture

2. Position of posterior border



b. Stability

c. Retention – to test retention the trial denture is

inserted in the patient mouth with firmupward and backward pressure, the tissues ofthe lips and cheeks are allowed to settle aroundit. The labial and lingual surfaces of the upper

trial denture are griped between the thumb andfore finger.

d. Labial contour



Both dentures togethera. Position of the occlusion

1. Anteroposterior relation – if the biteregistration was accurate, the teeth should interdigitate in the mouth in exactly the samemanner as they do on the articulators, but if theregistration was wrong, the teeth will notinterdigitate correctly and may even occludedcusp to cusp on one or both sides.



Correcting the anteroposterior position

Vertical height

Correcting the vertical height



Evenness of occlusal pressure1. Pressure on the blocks being heavier on one

side than the other when the records were

taken2. A slight error in sealing the models in the

blocks when articulating them.

3. Warpage of the base-plates



Balance occlusion – the first check is for centricocclusion. Check for evenness of occlusalpressure in the centric position with celluloid

strips and then test for balance with gentlelateral and protrusive movements. With theteeth in a lateral position of occlusion, insertthe point of a wax knife between the teeth on

the balancing side, and attempt to separatethem.



If they do separate, it shows that the occlusionof the teeth on that side is apparent only and isresulting from the displacement of the denturebases from the ridges. The cause of this errormay be due either to an incorrect face-bowreading, or to an incorrect condylar pathregistration. These registration must be takenagain, the casts remounted on the articulatorand the teeth reset; but if the error is onlyslight, it may be corrected by grinding theocclusal surfaces of the teeth when thedentures are finished



Appearance1. Center line2. Anterior plane3. Shape of the teeth4. Size and shaped of the teeth – individual judgment

must be relied on them together with the patientsopinion observed the patients profile and note ifthe lips are either excessive distended or undulysunken

5. Amount of tooth visible – ask the patient to say‘YES’ and smile and note how much tooth shows

6. Regularity of the teeth



Approval of appearance by the patient



Phonetic test-- speech defect in complete denture may be due

to

a. poor fitb. improper arrangement of teethc. high vertical dimension

d. reduced tongue space



The F, V and Ph sounds are aids in determining theproper position. When pronouncing the letter S thelateral margins of the tongue contact the lingualsurface of the posterior teeth and the tip of the

tongue is brought near palate in the rugae area, soit confines the stream of air forms the letter S, thesize and shape of this space affect the quality of Ssound. If the maxillary anterior teeth are place too

far forward (labially) the patient may whistlebecause the tongue is forced between the teeth andthe S becomes Ch. Also the relationships of theupper and lower anterior teeth affects the

Evaluation of the Trial Dentures

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