lect 3 - artificial set up, modelling, investing with/without shaft, completion of partial denture, immediate partial dentures, kennedy dentures and dentures with pelots

prognosis

medical prediction regarding likely course, duuration and outcome of a disease/injury

also includes chance of recovery or recurrence

deciding whether a tooth is worth including in prosthetic treatment

understanding that with appropriate maintenance the tooth provides a reasonable 5 year prognosis for survival

• do they require restoration with surveyed crowns?

• how much do they provide to the prosthesis, support/retention?

• any splinting needed?

• is it symmetrical as this will affect distribution

• is there a strong patient desire to maintain teeth?

• comparative functional expectations between a mucosal-borne denture and RPD that uses teeth for some support, stability and retention

restoration with surveyed crowns

specialised full-coverage restorations designed to support RPDs by creating optimal contours, guide planes and rest seats

wax rim and types

prismatic bodies made of pink wax cross section 1cm2

compensate the atrophy of alveolar ridges

• prefabricated

• laboratory made

• elliptical (for maxilla)

• parabolic (for mandible)

guides

1. guidelines :

• midline

• high lip line

• canine line

2. proper placement of occlusal plane

3. proper lip support

4. correct jaw relationship (vertical dimension of occlusion and centric relation)

alveolar ridge resorption

in anterior maxilla its

anterior mandible is down and lingual

anterior maxillary teeth setting

central incisor :

• incisal edge contacts the horizontal plane

• long axis parallel to sagittal plane

• frontal inclination 5-8^o

• overlap with lover incisors should be 1

lateral incisor :

• 0.7mm-1mm above the horizontal plane

• sagittal inclination 10-20^o

• frontal inclination 8^o

canine :

• cusp in contact with plane

• sagittal inclination 7-10^o

• axial rotation of the crown so that when viewed from the front only the mesial part is visible

neutral zone

potential space between the lips/cheeks and tongue where the forces between the tongue and cheeks are equal

area of equilibrium is the neutral zone

position of posterior teeth in relation to alveolar bone

on the ridge crest

important for lower denture stability

balanced occlusion

bilateral simultaneous, anterior and posterior occlusal contact of teeth in centric and eccentric position

eccentric position includes lateral and protrusive positions in both working and balancing sides

central occlusion and eccentric

central is the maximum intercuspation (tighteest fit) of upper and lower teeth - bite

eccentric is any tooth contact during mandibular movement away from that central position

CO stationary

EO movement

compensating curve

curving in anteroposterior median plane and mediolateral frontal plane

alignment of occluding surfaces and incisal edges used to develop balanced occlusion

its the arc introduced to construct complete RPD to compensate for the opening influenced produced by the condylar and incisal guidance during lateral and protrusive mandibular excursive movements

anteroposterior curve (curve of Spee)

anatomic curve made of occlusal alignment of teeth with the cusp tip of mandibular canine following the buccal cusps of the premolar and molars till it reaches the anterior border of the mandibular ramus ending at the mandibular condyle

curve of monson

ideal curve of occlusion where each incisal edge conforms to a segment of a sphere 8 inches in diameter at the crista galli

curve of Wilson

mediolateral curve

occlusion should be spherical, lower bridge is concave adn upper bridge is convex, the curvature in the lower arch is affected by equal lingual inclination of right and left molars so the tip points can be placed on the circumference of a circle

curve of Villain

in abrasion

max post teeth contact

posterior buccal surfaces make contact with a straight line drawn from the labial surface of the canine and the premolar and vestibular surfac eof the molars 155o

poster

upper premolars and molars

1st premolar - contacts horizontal plane buccal cusp ONLY

2nd premolar - contacts horizontal plane BOTH cusps

1st molar - horizontal plane mesiolingual cusp, mesiovestibular cusp 0.5mm, distolingual cusp 1mm, distovestibular cusp 1.5mm over plane

2nd molar - mesiobuccal cusp 1mm above planne, distobuccal cusp 1.5mm above plane, palatal cusp closer to or lightly contacting plane

lower premolars and molars

1st premolar - vestibular cusp in contact with central groove of antagonist

2nd premolar - vestibular cusp in contact with central groove of antagonist

1st molar - key of occlusion, MV of upper 1st contacts groove between MV and DV cusps on vestibular surface of lower 1st molar

2nd molar - vestibular cusps in contact with central groove of antagonist

snowshoe principle

best support with least load per unit area

secondary retention

1. adhesion is the attraction of saliva to the denture and tissues

2. cohesion attraction of molecules to saliva to eachother

3. atmospheric pressure dependent on a border seal and results in a partial vacuum beneath the denture base when a dislodging force is applied

4. physiologic molding of tissues around the polished surface of the denture

5. effects of gravity on mandibular denture only

maxillary distal extension

bases are extended buccally within physiologic tolerance of borders structures

it covers both the maxillary tuberosities and extend into the pterygomaxillary notches and provide adaptation along the posterior border

makes sure it doesn’t extend into the soft palatal flexure

mandibular bilateral distal extension

bases are extended buccally within physiologic tolerance of borders structures

cover retromolar pads and extend into retromylohyoid fossae

basic principles of denture base

• width of denture base is inversely proportional to number of abutment teeth (less abutment larger base)

• denture base material (acrylic resin or dental alloy)

• artificial teeth must respect the form and position of natural teeth

flasking key times

after putting both moulds together with the model being isolated put in boiling water for 3 minutes

any longer will melt the shellac making it harder to remove

open and rinse wax and remove shellac

isolate when flask is still hot

put acrylic in press and leave in for 20 minutes

run under cold water for 5-8

long - put flask in at room temp heat for 30 mins while temp rises to 60c leave at 60 for 1hr heat for another 30min till 100c and slow cool for 2.5 hrs

instruments

• steel burs

• tungstene carbide burs

• diamond

• cutters which are metal or carbide

• abrasive stones (corundum or carborundum)

• abrassive separators (corundum, steel, diamond)

• sandpaper

• abrasive rubber

• brushes

• polishing pastes

Kemeney denture indications to use

RPD with plastic dento-alveolar clasps

1. abutment teeth mobility I-II degree

2. caries resistant teeth

3. retentive alveolar ridge

4. esthetics - priority

Kemeney denture indications not to use

1. teeth with no vestibular infrabuldge

2. caries unresistant teeth

3. nonretentive alveolar ridge

indication for RPD with pelots

1. mobile teeth

2. retentive alveolar ridge

3. in upper frontal area

immediate RPD ad/dis

any removable dental prosthesis fabricated for placement immediately after removal of natural teeth

indications : pathological teeth mobility III in the visible zone

ad :

1. high psych-prophylactic effect

2. preserving the height of occlusion

3. short period for adaptation

4. conductive influence of denture towards the healing process of extraction wound

dis :

1. need of relining after 2-3 months

*The mobile teeth should be ligatured before taking the impression from the mouth, ​if there is a high risk of ​
preliminary extraction