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...
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