Posterior teeth selection/ orthodontic continuing education

POSTERIOR TEETH
SELECTION
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

Contents:
Introduction
Posterior teeth selection
size
shade
form
anatomic teeth
modified anatomic teeth
nonanatomic teeth
Factors that control the form and selection of teeth.
Factors infuencing the function of anatomic and nonanatomic teeth.
Conclusion
References.

Introduction:
• Selection and placement of posterior teeth is
based on of the nature of the mucosa and
submucosa, the form and relationship of the
residual ridges, the general systemic condition
of the patient, the tone of mandibular
musculature, esthetic factors and post patient
experiences which help in selecting the size,
form and number of artificial posterior teeth that
may be used on the denture bases. The dentist
is solely responsible for the selection of the
posterior teeth as he alone possesses the
necessary information required in this regard.

• Selection:
• Shade
• Size
• Number
• form

• Shade:

• Size:
• Buccolingual
• Mesiodistal
• Occluso gingival length.

• Buccolingual :

• Mesio distal length:

Vertical height:

• Material :
• Acrylic resin
• Porcelain
• Acrylic teeth with metal inserts

Acrylic teeth:
Indications:
Opposing natural dentition
Opposing gold restorations
Reduced interarch distance

• Advantages:
• Inexpensive
• Easy to grind
• Absorbs occlusal
stresses
• Does not wear
opposing natural
teeth and gold crowns
• Bonds chemically
• Easy to polish
• Softer impact sound
• Disadvantages:
• Wears easily
• Vertical dimenson
altered due to wear.
• Stains and discolors
with time.

Porcelain teeth:
• Indications:
• When sufficient
interridge distance is
available.
• Well formed ridges
• Contraindications:
• Poor mandibular
ridges
• Opposing natural
dentition or gold
restorations.
Porcelain tooth with retentive pins

• Advantages:
• Does not wear easily
so maintains vertical
dimension.
• Maintains masticating
efficiency.
• Ca be re used
through rebasing
• Disadvantages:
• Clicking sound on
impact
• Difficult to grind and
adjust.chips of easily.
• Requires adequate
interarch distance.
• Abrades opposing
teeth.
• does not form
chemical bond with
denture basewww.indiandentalacademy.com

Acrylic resin teeth with metal
inserts:
• Cast gold restorations.
• Amalgam inserts.
• Schultz 1951-gold
occlusals.
Hardy 1951-metal
cutting blades embeded in
Non anatomic teeth.

• Porcelain acrylic combination:

Anatomic teeth or 33 degree teeth:
• Definition:teeth that
have prominient
cusps on the
masticating surfaces
that are designed to
articulate with the
teeth of the opposing
natural or prosthetic
dentition.(G.P.T8)

1913-Gysi
Normal bite teeth
Trubyte teeth.
• 1932-Pilkington and
• Turner.

Modified anatomic teeth between
30 and 0 degree.
• 1927-Gysi –cross bite posterior teeth.

• 1927-Victor Sears-channel tooth

• 1930-Avery –scissor
bite technique

• 1936-Mc Grane-curved cusp posterior
teeth.

• 1935-French

• 1937-Max Pleasure

• 1942-John Vincent-
metal inserts in resin
posteriors.

• 1941-Payne-Lingualized occlusion.

• Levin –Cross blades.

Non anatomic or 0 degree cuspless
teeth.
• Definition:artificial
teeth with occlusal
surfaces that are not
anatomically formed.
(GPT8)

• 1929-Hall-
inverted cusp teeth.

• 1929-Meyerson -True -kusp teeth.

• 1934-Nelson “Chopping Block”

• 1939-Swenson “non lock teeth”

• 1946-Hardy “Vitallium occlusal”’

• 1951-Meyerson “shear cusp tooth”
• Porcelain and acrylic occlusal scheme.

• 1952- Cook “Coe masticators”

• 1957-cutter bar

• Problems with anatomic tooth forms:
• 1.use of adjustable articulator.
• 2.adjustment vary from dentist to dentist.
• 3.mesio distal interlocking will not permit
settling of base without horizontal forces.

• 4.harmonious balance lost due to settling.
• 5.the bases need prompt and frequent
refitting to keep occlusion stable.
• 6. cusp generate more horizontal force
during function.

• Problems with nonanatomic tooth forms
• 1.non anatomic teeth occlude only in two
dimensions.
• 2.do not function efficiently.
• 3.cannot be corrected much without
impairing their efficiency.
• 4.Appear unnatural.

• 5.bilateral and protrusive balance is not
possible with a purely flat
occlusion.nonanatomic teeth set on
inclines for balance require as much
concern as anatomic teeth for jaw
movement.

• Advantages of anatomic tooth forms
• 1.Efficient.
• 2.balanced occlusion.
• 3.esthetics.
• 4.compatible with surrounding oral environment.
• 5.cusps making contact in fossa at correct
vertical dimension with jaws in centric relation ,is
comfortable and is a definite point of return.

• Advantages of non anatomic tooth forms:
• 1.Offer less resistance in nonmasticatory
movement.
• 2.greater range of movement.
• 3.neuromuscular disorder patients.
• 4.elimination of inclined plane forces.
• 5.lack of interference when dentures
settle.

• Factors that control the selection of the
form of tooth.
• 1.condylar inclination:

• 2.height of residual ridge:

• 3.ridge relatinship:
• 4.incisal guidance:

• 5.type of ridge:

Ridge type Interridge
distance
Ridge
relation
Posterior
type.
prominient ideal normal Anatomic 1
prominient average prognathic Anatomic 1
average average retrognathic Anatomic 2/3
average close retrognathic Anatomic2/3
average large normal Anatomic 2
or
monoplane
Flat firm large normal monoplane
Flat firm excessive prognathic Anatomic 2
or
monoplane
Flat flabby excessive retrognathic monoplane

• Indications of flat teeth to be used:
• 1.flat ridges,rendering dentures more
susceptible to horizontal stress.
• 2.old age.
• 3.vertical dimension great causing tipping
forces to develop.
• 4.maximum vertical force and minimum
horizontal force is desired.

• Factors influencing function of anatomic and non
anatomic teeth:
• 1.efficiency:
• Type of patient.
• Condition of mucosa.
• The type of denture.
• Biting force.
• Character of food and size of bolus
• Arrangement of teeth.

• 2.directional forces:
• Form of teeth:
• Placement of the tooth:

• 3.horizontal forces:
• Incisal guidance.

• 4.stability:
• Tooth form
• Tooth arrangement
• Jaw movements
• Impression technique.

Conclusion
• There are no definite guidelines for
selection of posterior teeth. But it mainly
depends on the type of patient and the
condition of the supporting tissues. And
hence, the selection of teeth is the
responsibility of the dentist which he
acquires through knowledge and
experience.

References:
• Boucher : Prosthodontic treatment for edentulous
patients. 334-343, 9th Edition.
• Charles H. Heartwel, Arthur O. Rahn : Syllabus for
complete dentures. Pg. 322-325.
• Fenn, Liddelow and Geinsons : Clinical dental
prosthetics. Pg. 104-105, Third Edition.
• Essentials of complete denture Prosthodontics: 2nd
edition,Sheldon Winkler.
• Hardy I.R. : The developments in the occlusal patterns
of artificial teeth. J. Prosthet. Dent., 1 : 14-27, 1951.
.Moses C.H. : Biomechanics and artificial posterior teeth.
J. Prosthet. Dent., 4 : 782, 1954.

• Robert.L.Engelmeier:The history and development of
posterior denture teeth-introduction ,part 1.J.Prosthet
.Dent ,vol12,no3,219-226,sept 2003.
• Robert.L.Engelmeier:The history and development of
posterior denture teeth-introduction,part 2, J.Prosthet
.Dent ,vol 12,no.4, 288-301,December 2003.
• .Robert Rapp:the occlusion and occlusal patterns of
artificial posterior teeth:
J.Prosthet Dent ,vol 4,no.4,461-479,july 1954.
• I.R.Hardy: the developments in occlusal patterns of
artificial teeth:
J.Prosthet Dent,vol 85,no.3,220-230,march 2001.

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