Prosthodontics and Occulsion

The Prosthodontics is a part of the dental science that improve the esthetic and functional aspects of the oral and maxillofacial region through artificial restoration of the lost teeth and adjacent soft tissues 

Complete denture ProsthodonticsThe part that restore all the natural teeth and related tissue artificially

Removable partial denture ProsthodonticsThe part that restore one or more absent teeth and soft tissue through removable prosthesis

Fixed ProsthodonticsThe part that restore one or more absent teeth through fixed prosthesis

Dentulous – Full complement of teeth.Edentulous – Lost all the teethPartially edentulous – Lost a few teeth

Upper arch – Maxillary arch

Lower arch – Mandibular arch

Surfaces of teeth – MesialDistal

BuccalLingual

Occlusal

Mandibular movements

Vertical movement

• Opening

• Closing

Horizontal movement

• Protrusive or forward

• Retrusive or Backward

• Right lateral

• Left lateral

All these movements together will anable mastication

Occlusion -What is occlusion? Occlude means ‘to close’

Any contact between the incising or masticatory surfaces of the maxillary and mandibular teeth’

is termed as occlusion

Occlusal Plane -Average plane established by incisal and occlusal surfaces of the teeth

Curve of spee – seen in Natural dentition.Anatomic curvature of occlusal surfaces of

teeth beginning at the tip of the lower canine and following the buccal cusps of the premolars and the molars, continuing to the anterior border of the Ramus,

Curve of Wilson:It is the mediolateral curve that contacts the

buccal and lingual cusp tips on each side of the arch. It results from the inward incination of the posterior teeth ( mandibular molars ), making the lingual cusps lower than the buccal cusps.

Centric Occlusion – the occlusion the patient makes when they fit their teeth together in maximum intercuspation

- A cusp to fossa relation.

The masticatory (or stomatognathic) system

is generally considered to be made up of

three parts:

the Teeth, the Periodontal Tissues,

and the Articulatory System.

Key of occlusion First key, Molar inter-arch relationship, the upper first

molar's mesio-buccal cusp should essentially occlude into the buccal groove, of the lower first molar.

The first upper molar's mesio-palatal cusp must occlude into the central fossa of lower first molar

Second key

The mesial slope of the maxillary canine is in line with the distal slope of the mandibular canine.

When the maxillary and mandibular teeth contact simultaneously the condylar

proceses are fully seated in the mandibular fossae

MAXILLARY AND MANDIBULAR TEETH SHOULD CONTACT EVENLY

TO ALLOW OPTIMUM FUNCTION,TO MINIMIZE TRAUMA TO THE

SUPPORTING STRUCTURES, AND TO ALLOW AN EVEN LOAD DISTRIBUTION

THROUGHOUT THE DENTITION.

OCCLUSAL INTERFERENCES

Interferences are undesirable occlusal contacts that may produce mandibular deviation during closure to maximum intercuspation.

When there is occlusal

interferences there is trauma which cause tissue changes in

periodontal ligament space

CENTRIC RELATIONCENTRIC RELATION IS DEFINED AS THE

MAXILLOMANDIBULAR RELATIONSHIP IN WHICH THE

CONDYLES ARTICULATE WITH THE THINNEST

AVASCULAR PORTION OF THEIR RESPECTIVE DISKS

WITH THE CONDYLES IN THE ANTEROSUPERIOR

POSITION AGAINST THE SHAPES OF THE ARTICULAR

EMINENCES.

THIS POSITION IS INDEPENDENT OF TOOTH CONTACT.

The masticatory movements takesplace with in the following

movements

During mastication

Mandibular movements seen are• Opening• Closing • Protrusive or forward• Retrusive or Backward• Right lateral• Left lateral

All these movements together will anable mastication

Types of condylar MovementsDuring opening or closing of

the mandible

Rotational movement

Translational movement

Rotational Movement Around the horizontal axis (hinge axis)

Opening of the jaw

Translational movement

Wide opening

Translational movement

RetrusiveProtrusive

Movement around the vertical axis

Border movements of the Mandible in

Sagittal plane

Left lateral border

Right lateral border

Functional movements

Border Movement of the Mandible

Horizontal Plane and Frontal plane

Movement in the frontal plane

Movement in the saggital plane

Movement in the horizontal plane

It is with in this boundary that all the movements

of the mandible and the movements of Mastication takes place.

This Masticatory system is disturbed in patients with occlusal interference.

Occlusal schemes in Natural dentition.

Canine guided occlusion – During lateral excursive movement the canine contacts each other only and no other posterior teeth contact is seen,

Group function - During lateral excursive movement the canine contacts each other as well as other posterior teeth contact is seen.

Christensen's Phenomenon

During protrusive movements, there will be no contact of the posterior teeth

It is important to be familiar with

Definitions Components of the masticatory systemOcclusal interferenceKey of occlusionMandibular MovementsOcclusal scheme in Natural dentition.

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