75600838 prostho lab 7 anterior teeth setting

7/27/2019 75600838 Prostho Lab 7 Anterior Teeth Setting

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TEETH SETTINGIn dentures we try our best to reestablish esthetics, phonetics and function, but we still have problems and it's far away from being perfect! As commonly knownin general prosthodontics, the prosthesis (whether a denture or a maxillofacialprosthesis or any other replacement of a part of the body) will never be exactly the same as the lost body part, or as good as Allah's creation.

If someone loses a limb and gets a prosthesis, he doesnt expect that it will be as good as his natural limb, but unfortunately in dentures, our patients tend tohave this false expectation, they feel that the denture should feel as comfortable as their natural teeth! This is impossible! So a large part of our job is todeal with patients psychologically, and give them the correct expectation of what the denture will be like, and this should be discussed with the patient on thefirst visit. Unless you talk the patient through all of this, he will be surprised when he gets the final denture and neither of you will be happy! So keep them informed and give them the true expectation of what the denture will be like!

What do you know about natural occlusion? What's so special about natural teeth?

NATURAL VS. ARTIFICIAL TEETHThe main thing that distinguishes natural teeth from artificial teeth is that each natural tooth is attached to the bone through the PDL, that means each individual natural tooth is a unit by itself, if it moves it moves alone, if it fractures it fractures alone, if it is extracted it's extracted by itself .

However in dentures (partial or complete), all teeth are attached to the denture's base, the denture is considered as one big unit (as if it was one big tooth).

In other words the functioning unit in natural teeth is every tooth on its own,but in dentures the whole upper or lower denture is one big functioning unit.

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Why is this significant?? Because every time a patient with denture bites on something on one side the other side will be affected, or if he bites an apple in the front the back tends to come down a bit.

In dentures we have 28 teeth (we dont set third molars), 14 in the upper jaw and14 in the lower jaw, the company sends us 28 teeth per set.

In jaw relationship records, we have four steps as discussed earlier: 1) Vertical relationship 2) Horizontal relationship 3) Face-bow transfer records 4) Toothselection

In the horizontal relationship, we talked about centric relation (maximum intercuspation for denture teeth equals centric relation, but in natural teeth it's not the same).

In natural teeth, the patient chews on one side which we call the working side,the other side is called the non-working side because the teeth dont touch, and this is normal, if they touch we call it interference and it's bad.

However in dentures when the patient chews on one side (working side), the teethare designed to contact each other on the other side (balancing side).

Why do we design denture that way? Because when the patient chews, we want somekind of support on the other side, otherwise the denture will fall off or move;

it will cause instability and loosening of the denture. There for we design thedenture so that teeth are in contact at all times and in all movements, whethercentric or eccentric.

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In horizontal relation, after we learned about Centric Relation we will learn about what we call Eccentric Relation.

Eccentric relation represents all other movements other that the centric relation and we use these movements daily. In fact, the time spent in centric relationis very minimal (about 15 min daily), so the majority of the time, our teeth isin eccentric relation which includes lateral, protrusive and retrusive movementssuch as chewing.

Centric relation is a static relation (it's the zero point), while eccentric relation is a dynamic relation (right, left and forward movements and everything inbetween).

The patient is going to chew in dynamic relationship, that means we have to design the teeth so that when the patient chews on the right, the teeth will contactevenly on the left, and when he bites forwards the teeth will touch posteriorlyas well, and this is a little bit more complicated than it sounds, and we callthis type of symmetry Balanced Occlusion.

In natural teeth we dont have balanced occlusion.

In the balanced occlusion we have a working and a balancing side and the teeth touch in both, while in natural teeth we have a working and a non-working side and the teeth should only touch on the working side.

Main differences between natural teeth and dentures: 1) In natural teeth each individual tooth is an independent unit, while in dentures the whole upper or lower denture is one big functional unit. 2) In natural teeth when you chew, the teeth on the working side touch but they dont touch on the non-working, while in dentures we have BLANCED OCCLUSION, and teeth touch on both the working and balancing side.

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We are going to learn to set the teeth in centric relation (static relationship)but we are not going to create balanced occlusion, because our denture opens and closes in one position so we are not concerned with other movements.

HOW TO CREATE BALANCED OCCLUSION?Even though we will not be doing this in lab but it is a very important part ofmaking dentures that you need to know in some detail.

We have five factors affecting occlusal balance (HANAU's QUINT): 1) 2) 3) 4) 5)Condylar inclination Incisal guidance Occlusal plane Cusp angle Compensating curves (CC)

Using and varying these five factors we can create balanced occlusion.

1) CONDYLAR INCLINATIONo It's an anatomical position, it is fixed. o It can't be controlled by the dentist. o It's the angle between the condyle and the articular eminence.

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2) INCISAL GUIDANCEo Incisal guidance: Relates the overbite with the over jet. o It is usually expressed in degrees of angulations from the horizontal occlusal plane by a line drawn between the incisal edges of the upper and lower incisor teeth when closed incentric occlusion.

3) OCCLUSAL PLANEWhich we made according to camper's plane and was previously discussed.

4) CUSP ANGLECompanies provide us with teeth with variant cusp angle, which ranges from sharpto almost flat cusps.

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5) COMPENSATING CURVESInstead of making the arch flat, we create a curve in it, and this is one of themost important ways to maintain balanced occlusion. We design the teeth to havesome degree of curvature. We need this curve to be present antero-posteriorly and laterally.

In natural teeth we have two curves: 1) Curve of spee 2) Curve of Wilson CURVE OF SPEE: o If we draw an anterio-posterior line touching the cusp tips andincisal edges of mandibular teeth we will end up with is a smooth, linear curvewhich is called the curve of Spee. o It is viewed from the lateral aspect.

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CURVE OF WILSON: o The curve of Wilson is a lateral curve that contacts the buccal and lingual cusp tips of posterior teeth on each side of the arch. o It is viewed from the anterior aspect

SPHERE OF MONSON: combines both curves to create a sphere.

Scientifically speaking, these curves are present in natural teeth but in dentures we create curves to compensate for the space that is created when the jaw moves so we call them Compensating Curves.

As a summary to the compensating curves: o DEFINITION: the antero-posterior andlateral curvature in the alignment of the occluding surfaces and incisal edges of artificial teeth which are used to develop balanced occlusion.8


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o TWO TYPES: 1) Antero-posterior CC: They compensate for the curve of spee seenin natural teeth. 2) Lateral CC: They compensate for the curve of Wilson seen innatural teeth.

- Curve of spee and Wilson are only present in natural teeth. - Compensating curves are present in dentures - However we sometimes use Spee and Wilson to talk about dentures and you will find some books that confuse the two terms also.

SEQUENCE OF TEETH SETTING1) 2) 3) 4) Upper anterior Lower anterior Upper posterior Lower posterior

Upon setting teeth, we are going to face a problem which is the loss of our occlusal plane reference which is the wax. Because as I set teeth most of the wax will be melted away! And thats where the plastic sheet comes in. It will be my occlusal plane reference as wax will be lost and disfigured. This sheet is flat so Icreate the curves by raising the teeth above it as much as I want. The metal sheets are the best and the easiest to use but the plastic sheets are fine.

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SETTING OF ANTERIOR TEETHBefore we start setting, we should: 1) Check the articulator : a) Incisal pin position is correct. b) Condyles dont move.

2) Have the midline marked: a) Marked in the clinic for actual patients: Use midline of the face not the mouth or nose. b) Marked on the cast in our lab

To mark the midline on the cast, use the anatomic land marks like the incisive papilla and labial frenum anteriorly, and the fovea palatini posteriorly. But becareful because on our cast the fovea palatini aren't completely centered in themidline (the midline touches the right fovea palatini)

After you mark the midline on the cast, mark it on the occlusal rim and on the base plate so you dont lose it. It's CRITICAL that you mark the midline correctlyas any shift will cause all the teeth to shift to one side which is not acceptable. 3) Draw a template on the plastic sheet as a reference for the occlusal plane to stay oriented.

To set teeth correctly you should know that each tooth has a specific: 1) Mesiodistal inclination 2) Buccolingual inclination 3) Correct relationship with the occlusal plane.

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Following the sheet (Setting of Anterior Teeth) we have: Anterior View of UpperAnterior Teeth

Central incisor: o Incisal edge touches the occlusal plane. o The neck is slightly distally inclined (about 5o). Lateral incisor: o Raised above the occlusal plane by 0.5-1.0 mm (the more its raised the more feminine the teeth look) o The neck is more distally inclined (about 10o) Canine: o Touches the occlusal plane oThe neck is again more distally inclined (about 10o-15o)

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Lateral incisor:o Raised about 0.5 1.0 mm o Mesiodistally: the neck is more distally inclined (10o) o Buccolingually: the tooth axis is more proclined. The neck is more palatal. And our concentration is not so much on the proclination as much as it is on the neck being depressed.

Canine:o Touching the occlusal plane. o Mesiodistally: the neck is again more distallyinclined (15o) o Buccolingually: the tooth axis is upright. (the bulge is more apparent) These criteria are for each tooth alone, but the wax rim is what determines their places in the arch according to the shape of the patient's mouth. Toonarrow wax rim will give V-shaped arch and too wide will give a more flat arch.

If the wax is not symmetrical, use the setting plate to set the anterior teeth.And it can be used only for anterior teeth because the template we have is too wide for the posterior. Lower Anterior Teeth

The upper anterior over lap the lower anterior. The horizontal distance is called: Horizontal Overjet (HO) The vertical distance is called: Vertical overbite (VO)13


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This is a factor in Hanau's Quint that we already discussed. It is the incisal guidance. To understand the incisal guidance follow these three examples:

Normal overjet and overbite

Normal incisal guidance.

Longer overjet or shorter over bite incisal guidance less steep (more horizontal)

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An over view of a set of acrylic teeth:

Patient's Right

Patient's left

Patient's Right

Patient's left

A major problem that students face is confuse the right and left teeth, or lowerand upper, because later on we won't have much teeth left. Be careful because this will affect your mark significantly Write on the corners whether these are left or right so when you have less teeth you dont get confused between right andleft or upper or lower. Or you can mark on the teeth themselves in some way thatmakes you recognize them. Do not lose these teeth! There are no replacements!

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75600838 prostho lab 7 anterior teeth setting

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