Arrangement of teeth

Prof.Dr. Ahlam El-SharkawyHead of prosthodontic Departement.Pharos University.

Introduction:Artificial teeth should be arranged to be in harmony with the surrounding structures both in physiological and esthetic considerations in centric and excentric movements.

Balanced Occlusion:---The simultaneous contact of upper and lower teeth as they glide over each other when the mandible is moved from centric relation to eccentric relations.---This type of occlusion rarely found in natural dentition . However bilateral balance is generally considered necessary for denture stability.

Occlusal Curvatures:

This is a curved occlusal surface that makes simultaneous contact with the major portion of the incisal and occlusal prominence of the existing teeth.

Antero-posterior curve(Curve of Spee)

Lateral curve (Curve of Monson)

Curve of Spee:--It is the anatomical curvature of the occlusal alignment of the teeth beginning at the tip of the lower cuspid extended through the buccal cusps of the posterior teeth and continuing to the anterior border of the ramus ,ending with the anterior portion of the condyle.--This formed an arc of a circle of 7 cm. radius with a center at crista lacrimalis posterior.

Monson Curve:---It is the Curve of occlusion

touching the cusp tips of posterior teeth in frontal plane.---It forms a segment of the surface of a sphere 20 cm. in diameter with its center at the Glabella.

Compensating Curves:

---Compensating Curves are artificial curves introduced into dentures in order to facilitate the production of balanced occlusion.----They are artificial counter parts of the curve of Spee and curve of Monson found in natural dentition.

Factors of occlusion.1-Condylar Guidance.

2-Incisal Guidance

3-Cusp height

4-Compansating curve

5-orination of occlusal plane

General Consideration for the arrangement of teeth.

Anterior teeth

Esthetics

Phonetics

Posterior teeth.

The Crest of lower ridge

Compensating Curves

Common horizontal

plane

Spacing of

posterior teeth

Reference Marks for Selecting Anterior Teeth

Technician sets the teeth without seeing patient

Wax rim contours aid selection and setting:◦ Occlusal vertical dimension◦ Angulation of facial rims affects lip support◦ Overjet

Midline Position

Critical reference #7 wax spatula Score a line parallel

the facial midline Mark both rims

Guidelines for Setting Anterior Teeth

High Lip Line

Corner of Mouth

Angulation is as important as midline

Mandibular Reference Lines

Mandibular Reference Lines

aa

1/2 way up1/2 way upretr omolarretr omolar

Center of ridgeCenter of ridgePosteriorPosterior

Center of ridgeCenter of ridgeAnteriorAnterior

MandibularCast

Land AreaLand Area

Occlusion rimOcclusion rim

aa

1/2 way up1/2 way upretr omolarretr omolar

Center of ridgeCenter of ridgePosteriorPosterior

Center of ridgeCenter of ridgeAnteriorAnterior

MandibularCast

Land AreaLand Area

Occlusion rimOcclusion rim

1-The relation of the teeth to the alveolar ridge:

Maxillary central grooves should be centered over the crest of lower ridge.

Ensures denture stability

Reduces fulcruming forces during function

1.Maxillary anterior teeth

1.The long axis of the tooth shows slight distal inclination to the perpendicular.

2.The contact point should coincide with the midline of the face.

3.The incisal edge should touch the occlusal plane.

4.The neck of the tooth should be slightly depressed.

a. Maxillary central incisors

1.The long axis of Maxillary lateral incisor shows slightly more distal inclination than the central incisor when view from the front.

2.The long axis inclined labially when view from the side .

3.The incisal edge of the lateral should be 0.5-1mm above and parallel to occlusal plane.

4.The neck is depresed more than central incisor

b. Maxillary lateral incisors

1.The long axis should be parallel or distally inclined when view from the front, and vertical when viewed from the side.

2-The cusp tip is in contact with the occlusal plane3.The canine has two planes on the labial surface.

The mesial plane follow The contour of anterior teeth , the distal plane in line with the posteriors.

4.The neck of canine is prominent.

c. Maxillary canines

2. Mandibular anterior teeth

1.The long axis of the mandibular central incisor should be set perpendicular to the occlusal plane.

2. Set the mandibular central incisors so that the maxillary incisors cover them (1mm horizontally and vertically.

3.The contact point of mandibular incisors should coincide with the midline of the maxillary teeth.

a. Mandibular central incisors

1.The long axis of the mandibular incisor should be slightly inclined distally at the cervical portion of the tooth.

2.The occlusal height should be the same at the central incisors

b. Mandibular lateral incisors

1- The long axis of the mandibular canine is nearly perpendicular to the occlusal plane with a slight distal inclination.

2-The tip of the canine should be at the same occlusal height as the mandibular central and lateral incisors.

c. Mandibular canines

Arrangement of posterior teeth

Arrangement of Maxillary Posterior Teeth

First Premolar

Second Premolar

First Molar

Second MOLAR

The buccal cusp is touching the occlusal plane

Both the buccal and palatal cusps are touching the occlusal plane

The mesiopalatal cusp is touching the occlusal plane

The mesiopalatal cusp is the nearest to the occlusal plane

Occlusal View of Maxillary Posterior Teeth

Final Arrangement of Maxillary and Mandibular Posterior Teeth(Maximum Intercuspation)

Buccal View Proximal View