maxillary class-iii designs

8/22/2019 Maxillary Class-III Designs

1/28

Presented by,Jagadish.Konchada

Div of Prosthodontia


2/28

Anterior edentulous segment only

Single anterior space which does not cross midline

Left central and lateral incisor teeth are missing

Both third molars are missing which we dont take into consideration


3/28

Embrasure clasps may be moved one tooth

forward or backward depending upon

location of undercuts and occlusal contacts.

Cingulum rests should always be included on the

central incisor and canine


4/28

Anterior guide plates must be located on the

linguo proximal surfaces so that they will not be

visible from the labial aspect or interfere with

positioning of the replacement teeth.


5/28

An anterior-posterior palatal strap major connector is

preferred if the palatal opening would be large

enough to be of significant benefit ie.,15 mm in

anterior-posterior dimension

For a maxillary R.P.D there should be at least 6 mm of

space between gingival margin and the border of the

major connector

A U-shaped major connector may also be considered.


6/28

Minor connectors that connect rests to

major connectors should be positioned in

embrasures and form a right angle at the

junction with the major connector.

Whenever possible, at least 4 mm of

space should be present between

adjacent vertical minor connector

4 mm


7/28

Cast clasps are almost always used for class-III RPDs

With a small anterior edentulous space, anterior retentive

arms are seldom used.

Clasp can be placed on the canine if added retention is

desired.

Bar clasp can be given if the approach arm will be hiddenby the upper lip.

Circumferential clasp on the canine is usually

contraindicated.


8/28

Circumferential (embrasure )clasps are almost always used to provide

retention posteriorly.

If the height of contour is very near the occlusal aspect on the buccal surface,

minor recontouring may be required where retentive arms emerge from the

embrasure.

Access into and out of the rest seats ( shaded areas)

must be created by removal of tooth structure from the

proximal inclines of adjacent cusps,inorder to attain

adequate strength of metal.


9/28

Retentive network , denture teeth and denture base would tend to be selected if

the space is not appropriate for the missing teeth or if the residual ridge exhibits

extensive resorption or incomplete healing.

Facings ,tube teeth , or heat cure or light activated resin replacements would be

more appropriate if the residual ridge exhibits little resorption and large

undercuts and if the spacing is correct.


10/28

Posterior edentulous segment with no modification space

Left first and second molar are missing

Right third molar is missing which is not considered.


11/28

Occlusal rest on the left second premolar may be

moved to the mesial fossa or mesial or distal aspect of

first premolar if occlusal problem exists.

On the right side embrasure clasp may also be used on

second premolar and first molar.

In embrasure clasp some stability may be sacrificed

because the rests will be closer together.


12/28

Guide surface-guide plate contacts should be parallel

to path of insertion/dislodgement.

Occluso-gingival dimension of the contact should be

one half to two thirds the crown length.

Since class-III RPDs do not exhibit functional motion,

guide plates may be longer and may extend further

lingually and above the survey line without creating

adverse torquing forces on the abutments.


13/28

With only two teeth in edentulous segment, a palatal

strap major connector would always be used.

Palatal strap should be minimum of 8 mm in

anterio-posterior direction.

If the occlusion dictated that the rests be more

widely separated, an anterio-posterior palatal strap

could be considered with minimum of 15 mm or more

opening between the straps.

8 mm


14/28

Minor connectors that connect rests to

major connectors should be positioned in

embrasures and form a right angle at thejunction with the major connector.


15/28

On the left side, cast circumferential clasps are the

retainers of choice if the undercuts are on the sides

of the abutments away from the edentulous space

.

Bar clasps would be preferred if the undercuts are

adjacent to the edentulous space.

-If the undercut is located at the middle of the facial

surface, an I-bar is preferred.

-If the undercut is adjacent to the edentulous

space, a modified T-bar is preferred.


16/28

Retentive network , denture teeth and denture base would tend to be selected

with two or more teeth in the edentulous space.

A metal base with heat cured or light activated resin replacement is indicated if :

- vertical space is limited

- metal base is not visible when patient smiles.

- residual ridge is well healed.


17/28

Posterior edentulous segment with modification space on same side of arch.

Left first premolar and second molar are missing.

Right third molar is missing which is not considered.

It is class-III Mod 1.


18/28

One or both rests on the left molar may be omitted

if occlusal interference exists.

Rests on the right side may be moved forward or

backward depending on the occlusal interference.

Stability tends to improve as the rests and clasps

are more widely separated.


19/28

Guide surface-guide plate contacts should be parallel

to path of insertion/dislodgement.




20/28

Anterior-posterior palatal strap is usually

preferred.

However if the posterior border can be placed

farther forward, a palatal strap may be selected.


21/28

If the esthetics is a problem, the anterior clasp

on the left side may be placed on the first molar

rather than the first premolar.


22/28

Tube teeth or heat cured or light activated resin replacements would usually be

used for the two single tooth posterior replacement.

All metal tooth could be used to replace the second molar if vertical space is

limited.


23/28

Posterior edentulous segment with modification space on opposite side of arch.

Left first and second molars and right second molar are missing.

It is class-III Mod 1.


24/28

Rests on the distal of the right first molar could be

moved forward to the mesial fossa or to the distal fossa

of the second premolar if the occlusal interferencespreclude normal placement.


25/28

Guide surface-guide plate contacts should be parallel to

path of insertion/dislodgement.




26/28

A palatal strap would almost always be used.


27/28

Modified T-bars are the retainers of choice on the right

first and third molar if the only usable undercuts are

adjacent to the edentulous space.


28/28

Tube teeth or heat cured or light activated resin replacements would usually

be used for the single tooth in the modification space.

All metal tooth could be used if vertical space is limited or if the width of the

space is narrowed by drifting.

maxillary class-iii designs

Documents