teeth setting - Weebly · So You know now about the selection of teeth. And we are ready to move to...

15
. Done by: Rida alkhatib, Daniel atieh prosthodontics sheet#8 ____________________________________ 1 | Page The first part of this sheet is written by Rida al Khatib and the second part is written by Daniel attieh, according to section 2 record. So You know now about the selection of teeth. And we are ready to move to the next step: teeth setting *upper anteriors: 1) Setting of upper central incisor: A) Tooth from the front: the long axis of the tooth diverges slightly from the midline distally and the incisal edge contacts the occlusal table or the horizontal plane B) Tooth from the side: the neck of the central incisor is depressed by 2mm and that create an angle with vertical plane, and the incisal edge is in line with wax rim. 2) Setting of upper lateral incisor: A) Tooth from the front: the incisal edge is shorter than the occlusal table by 1 mm, the long axis is inclined more distally than the central incisor. B) Tooth from the side: the neck of the lateral incisor is more depressed than the central incisor creating an angle more than that for the central incisor with vertical plane. So this tooth is more labially inclined.

Transcript of teeth setting - Weebly · So You know now about the selection of teeth. And we are ready to move to...

Page 1: teeth setting - Weebly · So You know now about the selection of teeth. And we are ready to move to the next step: teeth setting *upper anteriors: ... ** the relationship between

. Done by: Rida alkhatib, Daniel atieh prosthodontics sheet#8____________________________________

1 | P a g e

The first part of this sheet is written by Rida al Khatib and the second part is written by

Daniel attieh, according to section 2 record.

So You know now about the selection of teeth. And we are ready to move to the next

step:

teeth setting

*upper anteriors:

1) Setting of upper central incisor:

A) Tooth from the front: the long axis of the tooth diverges slightly from the midline distally and

the incisal edge contacts the occlusal table or the horizontal plane

B) Tooth from the side: the neck of the central incisor is depressed by 2mm and that create an

angle with vertical plane, and the incisal edge is in line with wax rim.

2) Setting of upper lateral incisor:

A) Tooth from the front: the incisal edge is shorter than the occlusal table by 1 mm, the long axis

is inclined more distally than the central incisor.

B) Tooth from the side: the neck of the lateral incisor is more depressed than the central incisor

creating an angle more than that for the central incisor with vertical plane. So this tooth is more

labially inclined.

Page 2: teeth setting - Weebly · So You know now about the selection of teeth. And we are ready to move to the next step: teeth setting *upper anteriors: ... ** the relationship between

. Done by: Rida alkhatib, Daniel atieh prosthodontics sheet#8____________________________________

2 | P a g e

3) Setting of upper canine

(Placed at the angle of the mouth)

a) Tooth from the front: the long axis is almost upright, diverges slightly distally.

b) Tooth from the side: the long axis of the tooth is perpendicular on the horizontal

table. And the cusp of the canine touching the occlusal table. The cervical third is more

prominent than the cusp tip.

*you can see here the different inclinations of anterior teeth:

A B C

*harmony in the general arrangement of anterior teeth with:

-harmony of the incisal show and the patient age: younger patient shows more

incisor than the older patient.

-harmony of teeth with smiling line of the lower lip: if we extend a line between

upper canine to the other canine, this line should follow the curvature of the

lower lip during smiling regardless of the shape of the upper lip, also the vertical

positioning of upper canine is responsible for the shape of the smile line because

this line extend from the canine cusp tip of one side to canine cusp tip to other

side; and it should also touche the incisal edges of central incirsors.

A) Central incisor

B) Lateral incisor

C) canine

Tooth from the

side:

A) Central incisor

B) Lateral incisor

C) canine

Tooth from the

side:

Page 3: teeth setting - Weebly · So You know now about the selection of teeth. And we are ready to move to the next step: teeth setting *upper anteriors: ... ** the relationship between

. Done by: Rida alkhatib, Daniel atieh prosthodontics sheet#8____________________________________

3 | P a g e

-harmony of the dental arch form and the form of the residual ridge, the

arrangement of the teeth must follow the shape of the arch:

arch is square in shape: the central incisors and canine are set on a line; to fit

the shape of dental arch

Arch is tapering in shape: the incisors are a greater distance forward from the

canines; and teeth have rotations and lapping.

Arch is ovoid in shape: the relationship between the incisor and canine is more

flat, and no rotation of teeth because the arch is wider; so more of the labial

surfaces of teeth are seen.

-harmony of the long axis of the teeth (central incisors) with the long axis of the

patient’s face; to give esthetic’s appearance to the patient.

Square form

Taper form

Ovoid form

Page 4: teeth setting - Weebly · So You know now about the selection of teeth. And we are ready to move to the next step: teeth setting *upper anteriors: ... ** the relationship between

. Done by: Rida alkhatib, Daniel atieh prosthodontics sheet#8____________________________________

4 | P a g e

harmony of the opposing labial and buccal long axes of teeth: Balanced opposing lines.

Such as dissimilarities in the inclination, rotation, and position of the teeth on each side

of the midline provide what is called asymmetrical symmetry: when we look at the left

side and the right side, they are asymmetrical (they don’t show symmetry), but they

are symmetrical in another way; for example: if we look at the long axis of right lateral

incisor, it slopes distally, and when we look at the long ax of the left lateral is it slopes

distally as well (mirror image to each other).harmony of the long axes between upper

and lower teeth; when we look at the long axes of the lower teeth, it slopes distally as

well as upper teeth so the long axes appear as a continuous line between upper and

lower tooth.

*Lower anterior:

Lower Central incisors:

A) Tooth from the front: the long axis is almost vertical and slight mesial inclination to the

midline (according to incisal edge), less distal inclination than the lateral and canine

(according to root).

B) Tooth from the side: its positioned labially; which makes an angle with the

perpendicular plane.

Lower lateral incisor:

A) Tooth from the front: the long axis is slightly inclined mesially (according to incisal

edge), little distal inclination (according to root).

B) Tooth from the side: the long axis is vertical to the hohizontal plane.

Lower canine:

A) Tooth from the front: the long axis is more distally inclined (according to root).

B) Tooth from the side: the cusp of canine is lingually inclined and the cervical third is

prominent.

*the cervical third of the canine is prominent because the tooth has lingual inclination;

the tip of the tooth is more depressed lingually.

Page 5: teeth setting - Weebly · So You know now about the selection of teeth. And we are ready to move to the next step: teeth setting *upper anteriors: ... ** the relationship between

. Done by: Rida alkhatib, Daniel atieh prosthodontics sheet#8____________________________________

5 | P a g e

**Two relationship between upper and lower teeth which are:

1) Static: A) vertical overlap (overbite),B) horizontal overlap (overjet) between upper

central incisor and lower central incisor.

2) dynamic: during function which is mainly (protrusive movement) lower central

incisors slide against the palatal surface of upper central incisors. This path is called the

Incisal guidance (is the path on the lingual surface of the maxillary anterior teeth along

which the mandibular anterior teeth glide).

Incisal guidance angle: angle between the incisal guidance and the horizontal plane.so

in the complete denture we need this angle to be as shallow as possible and not greater

than 15 degrees (to achieve balanced occlusion). If it’s greater than 15 degree posterior

teeth will have separation during protrusion

-the incisal guidance angel depend on vertical overlap (overbite) or the

horizontal overlap (overjet) between the upper and lower incisors, so if these

change, the angle will be different. (The dimension of the triangle will change

so the angle also will change.

** the relationship between upper and lower anterior teeth at centric

occlusion; how should the upper and lower anterior teeth be arranged:

Anterior teeth are set with a minimal vertical overlap(over bite) for about .5-1 mm, and the

horizontal overlap(overjet) around 1-2 mm to make an incisal angle as shallow as possible.

No contact between upper and lower anterior teeth; there is a separation between them, no

contact at centric occlusion; equidistance overjet: when we measure the horizontal overlap from

the lower canine to the lower canine on the other side, this horizontal distance is equal (Even

horizontal distance from the left side to the right side).

Shallow incisal guidance will enhance denture stability when we talk about balanced

occlusion.

Page 6: teeth setting - Weebly · So You know now about the selection of teeth. And we are ready to move to the next step: teeth setting *upper anteriors: ... ** the relationship between

. Done by: Rida alkhatib, Daniel atieh prosthodontics sheet#8____________________________________

6 | P a g e

Here we are talking about the overbite and overjet which interact with each other

to give us the incisal angle:

-the triangle at the central: forming an angle of 15 degree

-the triangle at the upper right: overjet increase and the overlap is fixed; the angel is

reduced.

-the triangle at the upper left: overjet is fixed and the overbite is reduced; the angle is

reduced.

-the triangle at the lower left: overjet is fixed and the overbite increased; the angle is

greater.

-the triangle at the lower right: overjet is reduced and the overbite decreased; the angle is

greater.

Therefore, in order to obtain a shallow incisal angle; either we increase overjet or decrease

overbite.

This picture shows incisal relationship in different incisal classifications:

Page 7: teeth setting - Weebly · So You know now about the selection of teeth. And we are ready to move to the next step: teeth setting *upper anteriors: ... ** the relationship between

. Done by: Rida alkhatib, Daniel atieh prosthodontics sheet#8____________________________________

7 | P a g e

Class 1: the lower incisal edge occludes with or lie immediately below the middle part of the

palatal surface of the upper central incisors.

Class 2: division 1: the upper central incisors are proclined or of average inclination and there is

an increase in overjet.

Class 2: division 2: the upper central incisors are retroclined: the overjet is minimal but may be

increased.

*setting upper posteriors:

First premolar:

A) Tooth from the front: the long axis is perpendicular to the horizontal plane or occlusal

table.

B) Tooth from the side: we can notice that the buccal cusp touching the horizontal plane or

occlusal table while the palatal cusp is shorter than the buccal cusp so it doesn’t touch

the horizontal plane or occlusal table (refer to arrow).

Second premolar:

A) Tooth from the front: the long axis is perpendicular to the horizontal plane or occlusal

table.

B) Tooth from the side: we can notice that the buccal cusp and the palatal cusp are in

contact with the occlusal table or the horizontal plane. (Refer to arrow).

Page 8: teeth setting - Weebly · So You know now about the selection of teeth. And we are ready to move to the next step: teeth setting *upper anteriors: ... ** the relationship between

. Done by: Rida alkhatib, Daniel atieh prosthodontics sheet#8____________________________________

8 | P a g e

First molar:

A) Tooth from the front: the long axis slopes mesially (according to root).

B) Tooth from the side: all the cusps are not contact with the horizontal plane

except mesiopalatal cusp; so the mesiobuccal cusp is about 0.5mm higher than

the occlusal table while the distobuccal cusp is much higher than the MBC;

around 1mm.

First premolar and second premolar and the first molar from the occlusal view:

A line: a line extending from the distal surface of the canine touching the buccal surface of the

first premolar and second premolar and the MB surface of first molar, and this line will

continuous with the distal surface of the canine.(refer to arrow)

That mean there is a continuation of arrangement to produce an arch shape between

the anterior teeth and the posterior teeth.

Page 9: teeth setting - Weebly · So You know now about the selection of teeth. And we are ready to move to the next step: teeth setting *upper anteriors: ... ** the relationship between

. Done by: Rida alkhatib, Daniel atieh prosthodontics sheet#8____________________________________

9 | P a g e

Second Molar

- Long axis slopes more mesially (because we can see the occlusal surface) a bit more than first

molar (buccal view). The occlusal surface faces distally and buccaly.

- All four cusps do not touch the lower occlusal rim but the mesiolingual cusp is the nearest.

B- LINE

This second line contacts the buccal surface of the buccal

cusps of first molar and second molar.

The two lines (A & B) will achieve the curve of the arch

that is required.

Page 10: teeth setting - Weebly · So You know now about the selection of teeth. And we are ready to move to the next step: teeth setting *upper anteriors: ... ** the relationship between

. Done by: Rida alkhatib, Daniel atieh prosthodontics sheet#8____________________________________

10 | P a g e

SETTING MANDIBULAR TEETH - GENERAL STEPS TO ACHIEVE

Long axis of all lower teeth must be perpendicular to the horizontal plane which

means no inclination in all lower posteriors

these teeth are set in centric occlusion (maximum intercuspation/contact

between upper and lower teeth). No spaces should be seen specially in posterior

teeth, but buccal over-jet should be present to prevent cheek biting.

in order to produce this max intercuspation, you either reduce the size of

marginal ridges of upper and lower teeth, or slight spacing in upper teeth.

should allow sufficient, equidistant buccal over-jet in order to prevent cheek

biting.

we always start with the lower first molar in setting

lower first molar is placed over the crest of the lower ridge and its central fossa

occludes with the mesio-palatal cusp of the upper first molar

You need to look at the relationship between upper and lower teeth in centric

occlusion (table in the slides). For example: (1) palatal cusp of upper first

premolar occludes with the distal triangular fossa of lower first premolar (note

that we talk about maxillary lingual cusps because they are the functional cusps

of upper teeth).

(2) For second premolar, palatal cusp of upper tooth contacts distal triangular

fossa of lower second premolar (3) For the first molar, the mesiopalatal cusp of

the upper contacts central fossa of lower first molar and the distolingual cusp of

the upper contacts distal marginal ridges of lower first molar and mesial

marginal ridge of second molar.

Page 11: teeth setting - Weebly · So You know now about the selection of teeth. And we are ready to move to the next step: teeth setting *upper anteriors: ... ** the relationship between

. Done by: Rida alkhatib, Daniel atieh prosthodontics sheet#8____________________________________

11 | P a g e

Compensating curves:

Two curves created in artificial teeth while setting to stimulate

curve of spee and

Monson, as they exist

naturally. Those two

cruves are: A =

Anteroposterior curve

similar to curve of

spee, B= lateral curve

similar to curve on Monson

BALANCED OCCLUSION AND ARTICULATION

The mandible in real life is not static, but is dynamic. Think about

grinding food, which produces dyamic mandible movement

involving protrusion and lateral movements. Those are the

horizontal movements produced (lateral + protrusive movements

i.e. eccentric). Vertical movements also take place.

So let's talk a bit more about the horizontal relations (centric and

eccentric relations). Centric relation have many definitions, but a

simple one describes the position of the maximum retrusion of

the mandible in which lateral movements can be produced. It may

or may not coincide with maximum intercuspation. While

Page 12: teeth setting - Weebly · So You know now about the selection of teeth. And we are ready to move to the next step: teeth setting *upper anteriors: ... ** the relationship between

. Done by: Rida alkhatib, Daniel atieh prosthodontics sheet#8____________________________________

12 | P a g e

producing the complete denture, we do it so that centric relation

= maximum intercuspation.

The eccentric relations describe the lateral and protrusive

movements produced as mentioned.

Now let's go back to our main topic concerned with balanced

occlusion. In order for all those dynamic movements to be

achieved and be successful, we must ensure that the denture

remains stable and does not dislodge by keeping teeth in contact

together to provide support.

Balanced occlusion means that there should be a bilateral,

simultaneous contacts between upper and lower teeth in centric

and eccentric positions of the mandible i.e this is a static

relationship.

Balanced articulation is actually the same idea of bilateral, even

contact between upper and lower teeth, but this is during

movement like sliding for protrusion movement (changing from

centric position to eccentric) i.e a dynamic relationship.

In average value articulator, we can achieve balanced occlusion

but not the balanced articulation because you will need to record

the condylar guidance angle exactly as it is in the patient.

Example - during lateral movement

if mandible moves to the right, then the right side is the working

side and the left side should be the balancing side (in order to

prevent dislodgment - that's only one advantage actually).

Page 13: teeth setting - Weebly · So You know now about the selection of teeth. And we are ready to move to the next step: teeth setting *upper anteriors: ... ** the relationship between

. Done by: Rida alkhatib, Daniel atieh prosthodontics sheet#8____________________________________

13 | P a g e

One more thing to note is that the condyle that moves is not the

one on the working side but on the balancing side. Working side

condyle show minimal movement in position only.

In this figure, A is the balancing

side and B is the working side.

Note that during this lateral

movement of the mandible,

buccal cusps of upper meet

buccal cusps of lower and lingual cusps of upper meet the lingual

cusps of upper on the working side. However, on the balancing

side, the palatal cusp of upper meet the buccal cusp (the lingual

incline part of the buccal cusp) of the lower.

Example - during protrusion movement

in the same way, we should achieve the contacts between

teeth, so that the incisal edges meet anteriorly and at the

same time have posterior contacts of teeth to avoid

dislodgement. The more posterior the contacts, the better,

but if we can achieve at least one on each side then it will

be sufficient.

Page 14: teeth setting - Weebly · So You know now about the selection of teeth. And we are ready to move to the next step: teeth setting *upper anteriors: ... ** the relationship between

. Done by: Rida alkhatib, Daniel atieh prosthodontics sheet#8____________________________________

14 | P a g e

Advantages of Balanced Occlusion:

1) allows the denture to be seated during activities such as eating, speaking etc.

2) If the denture is unseated properly, it will keep moving with different activities,

and this will lead to soreness and inflammation, and will also accelerate the bone

resorption.

3) Enhance retention and stability during activities (actually this is related to

point 1).

Factors that influence Balanced Occlusion:

We have incisal and condylar guidance on one side. And we have

cusp angles, orientation of occlusal plane, and compensating

curves on the other side. The reason we put them in separate

groups is because increase in one side will need to be balanced by

an increase on the other side to maintain the balance and so on.

Page 15: teeth setting - Weebly · So You know now about the selection of teeth. And we are ready to move to the next step: teeth setting *upper anteriors: ... ** the relationship between

. Done by: Rida alkhatib, Daniel atieh prosthodontics sheet#8____________________________________

15 | P a g e