Normal occlusionYenny Yustisia

Dept. Oral Biology

Dentistry UNEJ

Literally, the word "occlusion" means closing up (oc=up, and clusion = closing)

Is the changing interrelationship of the opposing surface of the maxillary and mandibular teeth, which occurs during movements of the mandible and the terminal full contact of the maxillary and mandibular dental arches (Gregory)

The normal relation of the occlusal inclined planes of the teeth when the jaws are closed (Angle)

Kriteria oklusi normal

Semua gigi terletak dalam lengkung secara baik

Hubungan yang harmonis antara lengkung gigirahang atas dan rahang bawah

Hubungan antara tonjol baik, di rahang atas dan rahangbawah

Factors for achieving normal occlusion

The position, size and relationship of the bone in which the tooth develops

The position and relationship of the tooth with in the bone

The path which the tooth follows to reach the mucous membrane before eruption

The forces which guide its course after eruption

The forces which start to operate when the tooth contacts with its apparent

Masticatory muscles have a balanced and normal function

Normal temporomandibular joint

Ideal occlusion hypothetical formula

(Maxwell) presupposes and requires:

Normally developed coronal contour of properly coordinated mesiodistal and buccolingual dimensions

Normally developed tooth and osseous, muscular, other anatomic and emerging structures

A definite geometric and anatomic, individual and collective relationship of denture units

A de finite geometric and anatomic relationship of the two dentures, cranium and mandible

Static occlusion

Hubungan gigi-geligi rahang atas dan bawahdalam keadaan tertutup atau hubungan daerahkunyah gigi-geligi tidak berfungsi (statik)

Basic concepts

Balanced occlusion

Morphological occlusion

Functional/individual/dynamic occlusion

Balanced occlusion

Oklusi dikatakan baik/benar, apabilahubungan kontak antara geligi padarahang bawah dan rahang atasmemberikan tekanan yang seimbang pada kedua sisi rahang, baik dalam keadaan sentrik maupuneksentrik

Morphologic occlusion

Oklusi dikatakan baik/benar dinilai

melalui hubungan antara geligi

pada rahang bawah dan rahang

atas pada saat gigi tersebut

berkontak. Konsep ini

menitikberatkan pada segi

morfologiknya saja

Oklusi normal menurut Angle adalah apabila tonjolmesiobukal gigi molar pertama permanen rahangatas kontak dengan lekuk bukal (bukal groove) gigimolar pertama permanen rahang bawah

Dynamic/Individual/Functional Occlusion

Efektifitas fungsional tak dapat ditentukan

oleh hubungan hirroglyphics (cusp,ridge

dan groove) saja, tetapi harus ada

keserasian antara komponen-komponen

yang berperan dalam proses terjadinya

kontak antar geligi tersebut.

Komponen tersebut: Gigi dan jaringan

pendukungnya, otot-otot mastikasi dan

sistem neuromuskulernya serta sendi

temporomandibular

Larry Andrew‘s Six keys to normal occlusion

Molar relationship

crown angulation

Crown inclination

Rotations

tight contacts,

and occlusal plane

Key 1. Molar Relationship

The maxillary first permanent molardisplayed a solid three- point contact with opposing teeth

The distal surface of the distal marginal ridge of the maxillary permanent first molar made contact and occluded with the mesial surface of the mesial marginal ridge of the mandibular permanent second molar

The mesiobuccal cusp of the maxillary permanent fist molar fell within the buccalgroove located between the mesial and middle cusps of the mandibular permanent first molar-as indicated by Angle

The mesiolingual cusp of the maxillary permanent first molar was seated in the central fossa of the mandibular permanent first molar. (The molars and premolars enjoyed a cusp-embrasure relationship buccally, and a cusp-fossa relationship lingually.

The tips of the maxillary canines were slightly mesial to the mandibular canine-premolar embrasure- which is consistent with the canine-rise concept)

Key II. Crown Angulation(Mesiodistal Tip)

By definition, the crown angulation is the mesiodistal tip of the long axis of the crown. It is the angle formed between the long axis of the crown (as viewed from a facial perspective) and a perpendicular line erected from the occlusal plane

It is positive when the gingival portion of the long axis of the crown is distal to the incisal portion , and vice versa. In normal occlusion, the crownangulation was positive for all the teeth

Key III. Crown Inclination(Faciolingual Torque)

By definition, the crown inclination is the faciolingual torque of the long axis of the crown.

It is the angle formed between the facial long axis of the crown (as viewed from a proximalperspective) and a perpendicular line erected from the occlusal plane

It is positive when the gingival portion of the long axis of the crown is lingual to the incisalportion, and vice versa

In normal occlusion, the crown inclination was negative for all the teeth except the maxillary central and lateral incisors

the lingual crown inclination was similar for the maxillary canines through the maxillary second premolars, and was slightly morepronounced in the maxillary molars

the lingual crown inclination progressively increased from the mandibular canines through the mandibular second molars

Key IV. Rotations

In normal occlusion, the dentition should be free from undesirable rotation .

If a molar is rotated, it would occupy more space than normal within the dental arch . The reverse is true for the anterior teeth

Key V. Tight contacts, no spacing

If there are no anomalies in the shape of teeth, or intermaxillary discrepancies in the mesiodistal tooth size, the contact points should abut in normal occlusion

Key VI. Occlusal Plane

occlusal plane is the imaginary plane on which the teeth meet in occlusion. (It is indeed acurved compound surface which is commonly approximated by a planestraight lines on lateral views-based on specific reference points within the dental arches)

normal occlusion, the occlusal plane should be flat or nearly flat (according to Andrews, the mandibular curve of spee should not be deeper than 1.5mm)

Relasi gigi anterior

Overjet (Jarak Gigit)

Jarak horisontal incisal incisive

rahang atas terhadap bidang labial

incisive rahang bawah.

Overbite (Tumpang Gigit)

Jarak vertikal incisal incisive

rahang atas terhadap incisal

incisive rahang bawah.

Relasi gigi posterior

Relasi gigi posterior cusp to marginal ridge :

Cusp fungsional gigi rahang atas danbawah saling bersandar pada marginal ridge gigi posterior lawannya.

Relasi gigi posterior cusp to fossa:

Cusp fungsional gigi rahang atas danbawah saling bersandar pada fossa gigiposterior lawannya.

Maxilla and mandibula relations

Physiological rest position

Posisi istirahat dari mandibula, saat seseorang dalam keadaanrileks dalam posisi tegak lurus dan otot-otot dalam keadaanistirahat atau posisi rahang bawah saat kepala dalam keadaantegak lurus, dimana otot-otot kelompok elevator dan depresortonus kontraksinya dalam keadaan seimbang dan kondili dalamkeadaan netral atau tidak tegang.

Posisi ini dianggap konstan untuk tiap individu

Centric relation

mandibula terletak paling posterior dari maksilaatau kondili terletak paling distal dari fossa glenoid, dimana masih dimungkinkan adanya pergerakaandalam arah lateral

mandibula terletak 1-2 mm lebih ke belakang darioklusi sentris

Centric occlusion

Posisi kontak maksimal dari gigi-geligi pada waktumandibula dalam keadaan sentrik, yaitu keduakondili berada dalam posisi bilateral simetris didalam fossanya

ditentukan oleh panduan yang diberikan olehkontak antara gigi pada saat pertama berkontak

Thank you...