orientation jaw relation

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Selecting Setting Denture Teeth
Rola M. Shadid, BDS, MSc, m(AAID)
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• The task of selecting teeth is the responsibility
  of the dentist and should not be left to others
• All the teeth from a particular mode will have
  the same size shape

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Selection criteria for anterior teeth

• Selection of tooth size
• Selection of tooth shape
• Selection of tooth shade
• Selection of tooth material

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Selection of tooth size

• Height (occluogingival)
• Width (mesiodistal)
• Thickness (faciolingual)

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Selection of tooth size

• Preextraction guides
• Diagnostic guides are the most reliable guides in
  the selection of size form
• Extracted teeth
• Previous dentures especially if they are
  immediate dentures
• Postextraction methods

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Determining Tooth Width

• Preextraction guide
• Bizygomatic width
• Cranial circumference
• Corners of the mouth
• Ala of nose

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Determining Tooth Width

• Bizygomatic width the greatest bizygomatic width
  measured by facebow divided by 16 width of the
  central incisor divided by 3.3 approximate
  width of the six upper anterior teeth
• Cranial circumference the ratio of the cranial
  circumference to the combined upper anterior
  teeth width is 10 to 1.

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Determining Tooth Width

• Corners of mouth at rest
• coincide with distal of canines
• Or ala of nose coincides
• with canine cusp tip

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Guide to vertical height of the tooth

• High lip
• (smile) line
• Interarch space

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Guide to vertical height of the tooth (High lip
line)

• Highest point of upper lip
• when smiling
• Cervical necks lie at
• or above this line
• If shorter teeth are selected,
• esthetics compromised

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Selection of tooth form

• facial form
• proximal form
• incisal form

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Selection of tooth form

• Matching the tooth form to the face form (Leon
  Williams theory)
• The dentogenic concept in selecting teeth forms
  (proposed by Frush Fisher)
• Teeth are selected according to sex then to
  personality finally the age

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Selection of the color (shade)

• An appropriate color of artificial tooth is
  selected from a shade guide.
• When making the choice, it is advisable to
  moisten the teeth with water and hold them just
  inside the patients open mouth.

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Selection of the color (shade)

• Care should be taken to avoid letting the patient
  view the teeth against a light background such as
  the dentists white coat as this can be
  positively misleading. Under such conditions the
  shade will appear darker than it will when the
  denture is eventually in the mouth. As a result,
  the patient is likely to choose a shade that is
  too light.

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Selection of the color

• Natural teeth tend to become darker with
  increasing age. It is, therefore, appropriate to
  choose a shade of denture tooth which is in
  keeping with the patients age.
• Correlation with skin and hair color is suspect

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Selection of the color

• Dont show a patient all shades in the shade
  guide outside of the mouth patients will almost
  always pick the whitest shade
• Instead show patient 2 or 3 shades under lip and
  ask their opinion
• Anterior and posterior tooth shades are the same
  (e.g. anterior shade P3.5 corresponds with
  posterior shade P3.5)

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Selection of the color
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Patient Chooses Shade with Input from Dentist

• Patient
• owns the dentures
• will look at them every day
• Offer your opinion, dont persuade

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Selection of posterior teeth

• Requirements of posterior teeth
• Chew food efficiently
• Contribute to denture stability
• Comfortable to underlying soft tissues
• Should not cause any bone resorption
• Should contribute to esthetics not create any
  sound on impact

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Selection criteria for posterior teeth

• Color
• Mesiodistal width
• Buccolingual width
• Occlusogingival length
• Cuspal inclination
• Material

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• Selecting Posterior Tooth Form

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Cuspal Inclination

• Defined as the angle between the palatal incline
  of the mesiobuccal cusp the horizontal
• Classified
• Nonanatomic
• Anatomic

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Anatomic Teeth (10, 20, 33)

• Advantages
• Easier to balance the occlusion
• Better chewing efficiency
• Better esthetics

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Anatomic Teeth (10, 20, 33)

• Use for patients with
• Esthetic concerns
• Coordinated jaw movements
• Denture opposing natural teeth
• Well formed ridges
• When possible to record transfer accurate jaw
  relationship
• When balanced occlusion is planned

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Non-Anatomic Teeth(0, Rational, Monoline, etc.)

• Advantages
• Freedom of occlusal movement
• Elimination of lateral forces
• Lack of interferences better able to
  accommodate positional changes of the dentures
  relative to the supporting tissues brought about
  by resorption of alveolar bone
• Disadvantages
• Not esthetic looking, lower shearing efficiency
  difficult to balance

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Non-Anatomic Teeth(0, Rational, Monoline, etc.)

• Use for patients with
• Jaw size discrepancies (Class III)
• Severe ridge resorption
• Uncoordinated jaw movements
• For elderly patients because an increased
  variation in occlusal contact positions is
  characteristic of this groupso it is difficult to
  record transfer accurate jaw relationship

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• Selection Of Denture Tooth Material

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Denture Tooth Material

• Acrylic resin
• Porcelain teeth
• Porcelain acrylic combination
• Acrylic teeth with amalgam inserts or with cast
  gold occlusal surfaces

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Denture Tooth Material

• Porcelain teeth less common now
• Acrylic easier to set and adjust
• Last life of denture (5-7 years)

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Acrylic teeth Porcelain teeth
Stain discolor with time/ Improved translucency with layers Very esthetic and more translucent
Wear easily but new acrylics wear better Less wear
Loose masticating efficiency with time Maintain masticating efficiency for years
Softer impact sound Clicking sound
Easy to grind Difficult to grind
Not abrade opposing natural teeth gold crowns Abrade opposing natural teeth gold crowns

Selection of tooth material
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Acrylic teeth Porcelain teeth
Bond chemically to denture base Mechanical bond to denture base by pins or channels within teeth
More resilient - Less breakage Brittle susceptible to fracture
Easier to set/adjust Difficult to set/adjust
Absorb occlusal stresses act as shock absorber Not act as shock absorber
Used when opposing natural teeth or gold restorations with reduced interarch distance in RPDs because teeth in contact with clasps may require grinding Used when sufficient interridge space is available well formed ridges superior esthetics is required. Contraindicated with poor mandibular ridges when opposing natural teeth or gold restorations

Selection of tooth material
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Porcelain-Acrylic Combination

• Resin posteriors oppose porcelain posteriors
• Porcelain anteriors resin posteriors ?

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Selecting Posterior Tooth Size

• Determine distance from distal of canine to
  ascending ramus (29, 30 mm, etc.)

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Selecting Posterior Tooth Size

• Buccolingual size can affect the tongue space
• smaller teeth if tongue space is limited

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Summary

• Selecting denture teeth
• advise patient dont persuade
• an art, minimal science
• use common sense
• use old denture as a starting point
• look at dentate patient esthetics

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Setting of Denture Teeth at Balanced Occlusion
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Arranging Prosthetic Teeth

• The goals of proper teeth selection and arranging
  are to construct complete dentures that
• Function well
• Allow the patient to speak normally
• Are esthetically pleasing
• Will not abuse the tissues over residual ridges
• Offer health comfort to TMJ

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Some guidelines for arranging artificial teeth

• The artificial teeth should be placed as near as
  possible to the position occupied by natural
  teeth, with being compatible with surrounding
  musculature.
• The preliminary position of both anterior
  posterior teeth is determined during jaw relation
  appointment (Refer to the lecture)

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Some guidelines for arranging artificial teeth

• Regarding anteroposterior position of upper
  anterior teeth fullness of the lips, phonetics
  (f v sounds) as a guide, distance from incisive
  papilla, and relation to the residual alvealar
  ridge as to be placed anterior to it according to
  the amount of resorption all guide their
  position.
• Regarding superoinferior position of upper
  anterior teeth preextraction records, former
  dentures, and visibility of the upper incisors
  are used as a guide.

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Some guidelines for arranging artificial teeth

• Inclination of the anterior teeth there is an
  obtuse angle between the labial surface of bone
  the labial surface of anterior teeth
• Mediolateral position midline ala of nose are
  used as aguide
• 0.5 mm vertical overlap of mandibular central and
  canine teeth with the maxillary central and
  canine teeth.
• A 1-2 mm horizontal overlap must exist between
  the lingual surface of the maxillary anterior
  teeth and labial surface of the mandibular
  anterior teeth.

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Some guidelines for arranging artificial teeth

• The upper lower posterior teeth are centered
  over the crest of the ridge whenever possible
• Placing maxillary teeth over maxillary
  tuberosity should be avoided
• Placing mandibular teeth over retromolar pad or
  over steep slopes should be avoided.
• Placing posterior teeth too far buccally should
  be avoided

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Some guidelines for arranging artificial teeth

• Placing posterior teeth too far lingually should
  be avoided
• The lingual cusps of mandibular posterior should
  be in alignment with mylohyoid ridge never
  lingual to it
• Regarding occlusal plane
• Interpupillary line ala-tragus line
• Corners of the mouth ( anterior occlusal plane is
  placed at or slightly below corners) level with
  one-half to two-thirds of retromolar pad
• Tongue (lateral borders of tongue should be just
  superior to occlusal plane)

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Some guidelines for arranging artificial teeth

• The lower posterior teeth are placed
  buccolingualy along a line extending from the tip
  of the canine to the middle of the retromolar
  pad. This line should pass through the central
  fossae of the premolars and molars.

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Occlusal contacts between upper lower posterior

• The posterior teeth articulate in a cusp to fossa
  cusp to marginal ridge relationships.
• The figure shows the contacts of upper
  palatal cusps on lower posterior teeth. The
  contacts of upper second molar mesiopalatal
  cusp of upper 1st molar are cusp-fossae
  relationships. The others are cusp-marginal
  ridges contacts.

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Reference marks in maxilla
a 7 Midline of the maxillary rim score a line
demarcating the position of the midline of
philtrum of the lip. This is one of the most
critical references to record. Ensure the mark is
a line, not just a dot, which parallels the
patients overall facial midline. Otherwise the
incisors can be set at an angle, making the set
up look off center. The mandibular midline can be
marked at the same time.
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Reference marks in maxilla
Corners of the mouth - mark the corners of the
patients mouth, when closed, at rest. This
approximates where the distal of the canine teeth
should terminate. Use the flexible Trubyte
Auto-Rule to measure around the circumference of
the rim between contralateral marks - tooth size
of the six anterior teeth can be read off the
ruler in mm or by the Dentsply letter code
(A,B,C,etc.)
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Reference marks in maxilla
High Lip line - mark the highest point the upper
lip reaches when the patient smiles. The
maxillary anterior teeth should be selected so
the cervical necks lie at or above this line. If
shorter teeth are selected, the esthetic result
will be compromised.
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Reference marks in maxilla
Palatal Midline - With a pencil and a straight
edge, draw a line through the middle of the
incisive papilla and the mid-palatal raphe,
extending it onto the land area of the cast.
Check your occlusal rim for symmetry about this
important midline. If it is not symmetrical,
adjust the rim prior to sending it to the lab for
placement of teeth.
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Reference marks in maxilla
Distal aspect of the incisive papilla - In the
edentulous maxilla, a line drawn perpendicular to
the palatal midline, passing trough the distal
aspect of the incisive papilla should normally
intersect with the cusp tips of the canines. On
average, the facial surface of the central
incisors should be approximately 8-10 mm anterior
to this line.
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Reference marks in maxilla
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Reference marks in maxilla
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Reference marks in mandible
1) Half way to two thirds up the retromolar pad -
the posterior aspect of the occlusal plane should
intersect the half to two thirds of the
retromolar pad, to ensure the occlusal plane is
not set too low (can cause tongue biting) or too
high (can cause instability strain as tongue
struggles to place the food bolus back on
occlusal table)
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Reference marks in mandible
2) Center of the posterior mandibular ridge -
Draw this line with a pencil and a straight edge,
on the cast, extending out to the land area. The
lingual cusp of the maxillary posterior teeth
should be centered over this line to ensure
denture stability, by reducing fulcruming forces
during function
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Reference marks in mandible
3) Center of the anterior mandibular ridge - Draw
this line with a pencil and a straight edge, on
the cast, extending out to the land area. If the
anterior teeth are set too far anterior to this
line, heavy fulcruming forces can cause tilting
and dislodging of the mandibular denture,
particularly when the mandibular ridge is
severely resorbed.
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Reference marks in mandible

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Guidelines for setting upper posterior teeth

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References

• Baskers Prosthetic treatment of the edentulous
  patient. Fourth edition Ch. 11.
• G. Zarb, Prosthodontic Treatment for Edentulous
  Patients 2004, Ch. 17

1. Complete Denture Prosthodontics, 1st Edition,
   2006 by John Joy Manappallil, Ch. 13 14