Must not interfere with the lip Dentate - the underside = same height as the anterior incisal edge Edentulous = allow room for the lip (expected height of new teeth) Should be parallel with the central axis of the mouth The handle should be parallel to the long axis of the teeth that are to be replaced The handle should be 3-4 mm thick, 8mm long, and 8mm high

lab Flashcards by Haeley collins

what is setting teeth based on

6 things
Occlusal plane
Labial contour
Crest of ridge
Axis of teeth
Curve of Spee/Wilson
Balanced occlusion

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Occlusion Class

Class 1 = 1st molar mesial cusp sits in the lower 1st molar mesial groove
Upper canine slightly distal to lower canine
Class 2 = 1st molar meisial (over bite)
Class 3 = 1st molar distal (underbite)

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Tooth selection considerations

Shape = arch shape, face, existing dentures
Size = intercanine distance, smile line, existing dentures
Colour = skin tones, existing, shade of teeth

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Why are All adjustments made on lower

Lower is mobile upper is fixed
All should be set on the upper for lower teeth to be in correct position.

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What is obtained from the upper (fixed)

Accurate occlusal plane
Vertical dimension
Contouring
Size and shape of teeth
Curve of Spee/Wilson

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What type of special trays are there

Perforated-Alginate
Non-perforated = red compound, fast set material

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What is a custom tray

Custom made device for patient to carry, confine and control impression material
* uniform space
* accuracy
* better for anatomy of patient
* comfort

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Characteristics
Custom Tray

Well adapted
Dimensionally stable
Extensions = 2.3mm from peripheries
Smooth and round edges
Rigid
Retention holes - if needed
Stops
Have a handle
Eased frenems
Steam cleaned
Disinfected

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Custom trays
What should they NOT be

Don’t let bind to model
Don’t react to impression material
Shouldn’t rock on model
Be overextended
Have voids or projections

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What can custom trays be made from

Shellac = heat and time sensitive
Light cure = stable, uniform / brittle, rough surface
Tray compound =done chairside /heat and time sensitive, can distort
Thermoplastic = clear acurate / expensive
Acrylic resin = cheap/rigid

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Why do we need to know LAndmarks

Where to extend trays
Sensitive areas avoid/impinge
Anatomical areas that need capturing
Design of prosthetic device
Identify abnormal conditions

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Tori

Benign bone growth in mouth
90% bilateral
Not pathology
Bruxism, vitamin deficiencies, calcium rich supplements, genetics = cause

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Mylohyoid ridge in prosthodontics

Posteriorly lies close to the residual ridge = needs to be relieved
* Covered by thin mucosa easily damaged by denture base
* Extension on lingual flange is to be beyond the palpable position of MR
* do not undercut

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How to gum carve

6 things
• Buccally do not expose neck’s
• Lingually to marginal ridge height
• Do not expose cingulum’s
• Ensure there is no wax on the teeth
• Use wax carver to shape eminences
• Use wax carver to shape interproximal area’s
• Hollow out tongue space for the lower

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Finishing setting teeth

Round cervical margins with stipple brush
Stipple buccal surface
Brush flame only
cervical margins
Buccal roll
Palate upper
Lingual lower
Check post dam
Wash with cold soapy water
Check occlusion

10 things

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Model and wax build up

• • •
Cut post dam for maxillary
Seal wax up to model
Build up gum eminences

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custom tray handle

Must not interfere with the lip
Dentate - the underside = same height as the anterior incisal edge
Edentulous = allow room for the lip (expected height of new teeth)
Should be parallel with the central axis of the mouth
The handle should be parallel to the long axis of the teeth that are to be replaced
The handle should be 3-4 mm thick, 8mm long, and 8mm high

Function of spacer in custom tray

Allows tray to properly position in mouth during border molding
Allow the impression to have an eventhickness of impression material
Prevent distortion of the material at final stage

Spacer should be

Constructed using wax
Extended fully (but not overextended) as marked on model
Be smooth
Correct thickness
Have stops placed in it
Where required
Subject to availability

Spacer thickness
wax sheets

Zince eugenol –> 0.5 = none
Elastomeric –> .5-1.5 = 1 sheet
Alginate –> 2-3 = 2 sheets
silicones –> 1.5-3 = 2 sheets
Plaster –> 4-5 = 3 sheets

Fabrication
what needs relieveing
Maxilla

incisal papilla
canine eminance
palatal fovea
sharp spiny ridge
any tori, bony prominance
ridge = tissue undercuts

Fabrication
What needs relieving
Mandible

Crest/ridge
mental foramen
genial tubercles
sharp spiny ridge
tori / bony prominance
ridge = tissue undercuts

Fabrication of
Spacer

thickness dependant on material used
uniform thickness
full extensions of sulcus
DO NOT extend past palatal fovea
DO NOT extend past retro molar pad
Min 3 stops
max 4 stops

Fabrication
light cure material

Fill stops with light cure material
Adapt evenly = uniform thickness
trim excess –> do not tear
go to full extensions
ease frenums
place retention holes (not at periperhery)

Light cure fabrication

5-10 mins boil out remaining wax

Trimming custom tray

Mark deepest point on sulcus --> trim 2-3mm above mark retromolar area use acrylic bur to * trim to marked lines * round peripheries * ease frenems * trim post dam in front of fovea * redrill holes (45)0 * roughen up tissue fitting surface * Chamfer post dam to tissue (endentulous)

making model

Pour primary model mix gypsum appropriatly pour model trim model = make land * remeove imperfections * mark sulcus depths * mark frenems * note landmarks * mark central line

Duplication Process (Hydrocolloid)

* Soak model 30 minutes * Pat dry model with paper towel * Place in flask * Pour Hydrocolloid and place in cold water, minimum * of 3cm, for 1 hour

Calcium Sulphate Dihydrate Plaster of Paris

Different plasters

* Impression plaster, ADA type I * Model Plaster, ADA type II * Model Stone, ADA type III * Model Die Stone, ADA type IV chemically identical. The difference between plaster / stone / die stone is the size and shape of the their particles. has a great effect on the strength of the material

Purpose of balanced occlusion

* Teeth make contact eccentric and centric non functional or parafunctional activity * Prevents breakage of artificial teeth * establish bilateral and simultaneous occlusal contacts

working Movement

Occlusal contact between the maxillary bucccal cusps and the mandibular posterior teeth during lateral movement

Balanced movement

During right = max lingual cusps contact lingual incline of mandibular Buccal cusp

Protrusion movement

Balanced occlusion is achieved by: * contact between maxillary Buccal cusps and lower posterior teeth * contact between upper and lower incisal egde

Model prep for registration rims

* mark crest of ridge posteriorly * mark anterior crest of ridge - mark on land so it can seen once wax is placed * wet model

Registration rims dimensions

Maxillary * anterior vertical = 22mm Anterior width = 5mm Height tuberosity = 8mm posterior width = 6mm Mandible * Anterior vertical = 18mm Anterior width = 4mm Height retro molar = 0 mm Posterior width = 6mm

Registration rim requirements

Constructed on 2nd model Stable Adaptation Correct dimensions Height and width = natural dentition Palate no more than 2mm thick No covering of land area Incorporate Buccal roll Tapered on upper to avoid retromolar pad Relieved Frenums No extensions past post dam Smooth, no voids Centred over crest Curvature follow curvature of arch

CUrve of spee

* anteroposterior compensating curve * The curvature is related to the angle of the condylar guidance * The curve isintroduced to provide balanced occlusion in protrusion

Fabrication = Curve of spee

* anteroposterior compensating curve * starts with the second premolar * buccal set on the occlusal plane, and progresses distally * buccal cusps of the molars set progressively higher than theocclusal plane * 6 and 7 tilt mesially to create an arc

Curve of Wilson

Mediolateral compensating curve introduced to provide balanced occlusion in **lateral excursions**

Fabrication Curve of Wilson

* The long axis of the second premolar is set perpendicular to the occlusal plane * molars are set with a slight tilt. * The buccal cusps are set higher than the occlusal plane. * Distal view –the necks of the 6 and 7 teeth are angled into the upper ridge creating an arc * 6 and 7 lingual cusps are lower than the buccal cusps

what does a face bow record

Vertical dimension Free-way space Centric relation Occlusal plane Labial contour Mid line Intercanine distance Smile line Aids in tooth selection