Dental Occlusion and Arch Size Quiz

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Questions and Answers

What does Wilson’s curve describe?

The curvature of the occlusal surface of complete dentures

A helicoid curve that is superficially flat

A curve formed exclusively by anterior teeth cusps

A mediolateral curve formed by cusp tips in a section through the frontal plane (correct)

What is described by the curve of occlusion?

The average alignment of the posterior teeth only

A flat occlusal surface at the maxillary arch

The average curve established by the incisal edges and occlusal surfaces of both anterior and posterior teeth (correct)

The alignment of molar cusps when viewed from the frontal plane

Which curve ensures balanced occlusion in complete dentures?

Monson’s curve

Compensating curve (correct)

Curve of Pleasures

Curve of Spee

What is distinctive about Monson’s curve?

It relates to a sphere that is 8 inches in diameter Signup and view all the answers

The curve of Spee is primarily observed from which point?

Opposite the first molars Signup and view all the answers

The term 'glabella' refers to which anatomical location?

The smooth area between the eyebrows above the nose Signup and view all the answers

Which curve of occlusion is also known as the anti-Monson?

Curve of Pleasure Signup and view all the answers

What does normal occlusion primarily refer to?

The relationship of the teeth during closure. Signup and view all the answers

How many occlusal contacts are typically found in normal occlusion?

138 contacts Signup and view all the answers

What is meant by the term 'arch length discrepancy'?

The abnormal relationship between arch size and component teeth. Signup and view all the answers

Which of the following describes the stability of occlusion vertically?

Dependent on occlusal and eruptive forces. Signup and view all the answers

What is classified as Class II in arch size?

Small mandible Signup and view all the answers

Which teeth are positioned more buccally in the dental arch?

Maxillary first molars Signup and view all the answers

What is the neutral zone in dentistry?

The area where lip and cheek pressures balance with tongue pressure. Signup and view all the answers

What happens to occlusal stability after tooth extraction?

It becomes unstable due to decreased occlusal force. Signup and view all the answers

Which of the following teeth generally have only one antagonist?

Mandibular central incisors Signup and view all the answers

What is true about the vertical overlap (overbite) in centric occlusion?

Maxillary anterior teeth extend labially over the mandibular anterior teeth. Signup and view all the answers

Which cusps are categorized as the supporting cusps in the occlusion principles?

Lingual cusps of the maxillary posterior teeth Signup and view all the answers

What describes the primary function of closure stoppers during mandibular closure?

They help maintain occlusal relationships on closure. Signup and view all the answers

In the context of occlusal contacts, which statement is correct regarding A, B, and C contacts?

B contacts are crucial for maintaining occlusal stability. Signup and view all the answers

Which description correctly identifies non-centric cusps in occlusion?

They facilitate horizontal and vertical overlaps over supporting cusps. Signup and view all the answers

Which principle best describes the concept of cusp-fossa occlusion patterns in centric occlusion?

Cusp-fossa relationships are meant for stabilizing occlusion. Signup and view all the answers

What is the primary feature of cusp-marginal ridge occlusion?

One stamp cusp fits into a fossa while another fits into an embrasure area. Signup and view all the answers

In cusp-fossa occlusion, what arrangement is described?

Stamp cusps of one tooth interdigitate with those of a single opposing tooth. Signup and view all the answers

What is a critical benefit of using cusp-fossa occlusion?

Improved stability and prevention of food impaction. Signup and view all the answers

During centric occlusion, what should occur between the Equalizers and Stoppers?

They should make simultaneous contact. Signup and view all the answers

What type of occlusion is characterized by a tripod contact?

Cusp-fossa occlusion. Signup and view all the answers

Which cusp of the maxillary first molar fits into the central fossa of the lower first molar?

Mesio-palatal cusp. Signup and view all the answers

Which of the following describes tooth-to-two-teeth occlusion?

One cusp fits into the fossa and another into an embrasure area. Signup and view all the answers

What forces are improved by cusp-fossa occlusion during mastication?

Centric relation closure forces applied closer to the long axes of the teeth. Signup and view all the answers

In centric occlusion, which teeth typically have only one antagonist?

Mandibular central incisors Signup and view all the answers

Horizontal overlap (overjet) occurs when the incisal ridges of which teeth extend labially or buccally to those of the opposing arch?

Maxillary anterior teeth Signup and view all the answers

What are the supporting cusps also known as in the context of centric occlusion?

Stamp cusps Signup and view all the answers

Which statement best describes the role of closure stoppers during mandibular closure?

Establish vertical stability between arches Signup and view all the answers

What is the relationship between the buccal cusps of the posterior teeth termed?

A contact Signup and view all the answers

Which occlusal relationship is essential for maintaining occlusal stability according to the contacts defined?

B contacts must be obtained and maintained Signup and view all the answers

Which of the following describes the characteristics of guiding cusps?

Sharper and placed more outward Signup and view all the answers

What type of occlusion involves the interaction between the mesial inclines of the lower teeth and the distal inclines of the upper teeth?

Closure stoppers Signup and view all the answers

What type of occlusion involves the interdigitation of the cusps and fossae of one tooth with those of only one opposing tooth?

Cusp-fossa occlusion Signup and view all the answers

Which structure best describes the contact mechanism in cusp-marginal ridge occlusion?

One cusp fits into the fossa and another into the embrasure area Signup and view all the answers

Which cusp of the maxillary first molar fits into the central fossa of the lower first molar during occlusion?

Mesio-palatal cusp Signup and view all the answers

What is the primary mechanical advantage provided by tripod contacts in cusp-fossa occlusion?

Stability due to tripod structure Signup and view all the answers

What is a notable feature of the cusp-fossa occlusion pattern found in only 5% of natural teeth?

All stamp cusps fit into fossae Signup and view all the answers

Which of the following is NOT an advantage of using cusp-fossa occlusion?

Broader interarch space Signup and view all the answers

Which cusp of the mandibular first molar fits into the mesial fossa of the maxillary first molar?

Mesio-buccal cusp Signup and view all the answers

Study Notes

Introduction and Definitions

Occlusion describes the static relationship of the maxillary and mandibular teeth when occluding.
Normal occlusion commonly exists in the absence of disease.
Normal occlusion presents with 138 occlusal contacts between 32 teeth.
Dental arch form refers to the geometric shape of the dental arch viewed horizontally.

Normal Arch Size

The maxillary arch tends to be larger than the mandibular arch resulting in maxillary teeth "overhanging" mandibular teeth.

Arch Length Discrepancy

Abnormal relationships between the size of the mandible and/or maxilla and their component teeth are viewed in the occlusal plane.
A class II discrepancy refers to a small mandible.
A class III discrepancy refers to a large mandible.

Teeth Position In Dental Arch

Certain teeth, due to their size, are positioned lingually or labially to the ideal curve.
The labial surface of maxillary lateral incisors is more lingually placed.
The buccal surface of cuspids are more buccally placed.
The buccal surface of maxillary first molars are positioned buccally.

Stability of the Occlusion Vertically

The maintenance of tooth position vertically depends on occlusal and eruptive forces.
Balanced forces will keep the occlusion stable.
Tooth extraction disrupts occlusion due to reduced occlusal force and tooth shifting.

Stability of the Occlusion Horizontally

Lip and cheek pressure from the outside and tongue pressure from the inside maintain the teeth horizontally.
The neutral zone is the potential space where the forces between lips/cheeks and tongue are equal.

Curvatures of the Dental Arches

The curve of occlusion is the average curve of the incisal and occlusal surfaces of the anterior and posterior teeth.

Curve of Spee

The cusps and incisal ridges display a curved alignment in a point opposite the first molars.

Monson’s Curve

Each cusp and incisal edge touches or conforms to a segment of a spherical surface with an 8-inch diameter.

Curve of Wilson

The cusp tips in both sides of molars in a frontal section form a mediolateral curve.

Curve of Pleasure (Anti-Monson)

A helicoid curve of occlusion that when viewed frontally forms a convex curve, except for the last molars which reverse the pattern.

Compensating Curve

The curvature of the occlusal plane of complete dentures, created to permit balanced occlusion.

Cusp-Marginal Ridge Occlusion

This type of occlusion occurs when a cusp fits into a fossa and another cusp of the same tooth fits into the embrasure area of two opposing teeth.
This pattern is present in 95% of natural teeth.
The mesio-palatal cusp of the maxillary first molar fits into the central fossa of the lower first molar.
The disto-palatal cusp of the maxillary first molar fits into the distal marginal ridge of the lower first molar and the mesial marginal ridge of the second molar.
The mesio-buccal cusp of the mandibular first molar fits into the distal marginal ridge of the second premolar and the mesial marginal ridge of the maxillary first molar.
The disto-buccal cusp of the mandibular first molar fits into the maxillary central fossa.

Cusp-Fossa Occlusion

This type of occlusion occurs when most or all of the cusps fit into fossae.
The cusps and fossae of one tooth interdigitate with the cusps and fossae of only one opposing tooth.
This pattern is present in 5% of natural teeth.
The cusp ridges make a tripod of contact with the fossa, leaving the cusp apex out of occlusion.
The mesio-palatal cusp of the maxillary first molar fits into the central fossa of the lower first molar.
The disto-palatal cusp of the maxillary first molar fits into the distal fossa of the lower first molar.
The mesio-buccal cusp of the mandibular first molar fits into the mesial fossa of the maxillary first molar.
The disto-buccal cusp of the mandibular first molar fits into the maxillary central fossa.

Advantages of Cusp-Fossa Occlusion

Prevents food impaction.
Centric relation closure forces are nearer the long axes of the tooth.
Improves stability.
Used when the mesiodistal relationship of opposing teeth favors it.
Used in full mouth/full arch reconstruction.

Centric Holding Cusps & Centric Stops

The supporting cusps (PU-BL) are the lingual cusps of the maxillary posterior teeth and the buccal cusps of the posterior mandibular teeth.
Centric stops are areas of contact that a supporting cusp makes with opposing teeth.

Non-Centric (Guiding or Shear) Cusps

Guiding cusps (BU-LL) are sharper and more outward placed than the supporting cusps and provide horizontal and vertical overlap over them.

A, B, and C Contacts

Contact between the buccal cusps of the posterior teeth is an A contact.
The common contact between the stamp cusps is a B contact.
Contact between the lingual cusps of the posterior teeth is a C contact.
The B contacts in centric occlusion must be obtained and maintained for occlusal stability.

Closure Stoppers and Equalizers

The closure of the mandible occurs in a curved upward path.
Upon closure, mesial inclines of lower teeth contact distal inclines of uppers. These contacts are called Closure Stoppers (ML-DU).
The distal inclines of the lowers contact the mesial inclines of the uppers. These contacts are called Equalizers (MU-DL).
Both Closure Stoppers and Equalizers should occur in centric occlusion.
The supporting cusps (PU-BL) act as Closure Stoppers and Equalizers during mandibular closure.
PU-BL means palatal upper, buccal lower.
ML-DU means mesial lower, distal upper.
MU-DL means mesial upper, distal lower.

Functional Form of the Teeth

C; cusp
CR; cusp ridge
MR; marginal ridge
TR; triangular ridge
CF; central fossa
MRF; marginal ridge fissure

Facial and Lingual Relations of Each Tooth to its Antagonist

In centric occlusion, each tooth on one arch occludes with two teeth on the opposing arch except for:
- Mandibular central incisors
- Maxillary third molars (occludes with one tooth)

Horizontal Overlap (Overjet)

The incisal ridges or buccal cusp ridges of maxillary teeth extend labially or buccally to the incisal ridges or buccal cusp ridges of the mandibular teeth in centric occlusion.

Vertical Overlap (Overbite)

The incisal ridges of the maxillary anterior teeth extend below the incisal ridges of the mandibular anterior teeth in centric occlusion.

Centric Holding Cusps (Supporting or Stamp) Cusps & Centric Stops

Lingual cusps of maxillary posterior teeth and buccal cusps of mandibular posterior teeth are supporting cusps.
Centric stops are areas of contact made by supporting cusps with opposing teeth.

Non-Centric (Guiding or Shear) Cusps

Guiding cusps (BU-LL) (Mandibular lingual & maxillary buccal) are sharper and more outward placed than supporting cusps.
They provide horizontal and vertical overlap over supporting cusps.

Centric Holding Cusps in Posterior Cross Bite Relationship

In this relationship, supporting cusps on the crossbite side would need to be flattened or re-contoured.

A, B and C Contacts

A contact: Contact between the buccal cusps of posterior teeth
B contact: Common contact between stamp cusps
C contact: Contact between lingual cusps of posterior teeth
B contacts in centric occlusion must be obtained and maintained for occlusal stability.

Closure Stoppers & Equalizers

Closure of the mandible occurs in a curved upward path.
Closure Stoppers (ML-DU): Mesial inclines of lower teeth contact distal inclines of upper teeth.
Equalizers (MU-DL): Distal inclines of lower teeth contact mesial inclines of upper teeth.
Simultaneous contacts of stoppers and equalizers should occur in centric occlusion.

Cusp – Marginal Ridge Occlusion

One stamp cusp fits in a fossa and the other stamp cusp of the same tooth fits into the embrasure area of two opposing teeth (“tooth-to-two-teeth” occlusion or a “cusp-embrasure” occlusal pattern).
Present in 95% of natural teeth.
Plunger cusp effect

Cusp-Fosse Occlusion

Most or all stamp cusps fit into fossae.
Cusps and fossae of one tooth interdigitate with cusps and fossae of one opposing tooth (“tooth-to-one-tooth” occlusion)
Present in 5% of natural teeth.
Tripod Contact in Cusp Fosse Occlusion: Cusp ridges make a tripod of contact with the fossa, leaving the cusp apex out of occlusion. This provides escapement spaces, necessary for efficient mastication.

Advantages of Cusp Fosse Occlusion

Prevents food impaction
Centric relation closure forces are closer to the long axes of the tooth
Improves stability
Used when:
- Mesiodistal relationship of opposing teeth favors it
- Full mouth/full arch reconstruction

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Description

Test your knowledge on dental occlusion, arch size, and the classifications of dental discrepancies. This quiz covers definitions, normal occlusion, and the positioning of teeth in the dental arch. Ideal for dental students and professionals looking to review essential concepts.