Occlusion Chapter 20 Definition Occlusion is defined as

Occlusion Chapter 20

Definition • Occlusion is defined as the relationship of the maxillary and mandibular teeth when closed together or during excursion of movement when teeth are touching.

Importance of Assessing Occlusion • Personalized instruction – Thumbsucking – Orthodontics – Fixed or partial appliances • Adaptation of oral hygiene technique • Diagnosis of dental disease • Recording occlusion for legal records and forensics

Importance of Good Occlusion • • Good masitication Facial symmetry Promote normal speech Stability of jaw relationships

Stages of Development • Deciduous dentition • Mixed dentition • Permanent dentition

Deciduous Teeth • Primate spaces • Leeway space • Diastemas www. coveringkids. org. Access, August 2002, p. 9.

Primate Spaces • Spaces that occur in the primary dentition that are isolated to: – Maxillary anterior to canines – Mandibular posterior to canines Brand Isselhard. Anatomy of Orofacial Structures, 7 th Ed. Mosby, St. Louis. 2003, p. 67.

Leeway Space • Extra space that is gained upon the exfoliation of the deciduous canines and molars. • These deciduous teeth occupy this space, which is a wider distance than the permanent replacements. Brand Isselhard. Anatomy of Orofacial Structures, 7 th Ed. Mosby, St. Louis. 2003, p. 56.

Diastema • Spaces between primary teeth that allow room for the permanent teeth to erupt • Diastemas may be isolated between the incisors with growth and development.

Static Occlusion • The relationship of the teeth when the jaws are closed in centric occlusion. • Maximum cuspation

Centric Occlusion • The relationship of opposing occlusal surfaces which provides the maximum contact and /or intercuspation. • Habitual occlusion Facial view Ash. Wheeler’s Dental Anatomy, Physiology and Occlusion. , Seventh Edition. W. B. Saunders Company, Philadelphia. 1993. p. 439.

Centric Relation • The most unstrained, retruded anatomic and functional position of the heads of the condyles of the mandible in the glenoid fossae of the TMJ

Functional Occlusion • Teeth contact while the mandible is working. • Examples: chewing, swallowing

Keys to Understanding • The maxilla is stationary. • The mandible is movable (static).

Keys to Understanding • The maxilla slightly overlaps the mandibular arch in normal occlusion. • The mesiobuccal (buccal) groove of the mandibular first molar and the mesiobuccal cusp tip of the maxillary 1 st molar are occluding in normal occlusion.

Single Tooth Deviations • • • Labioversion/Buccoversion Linguoversion Torsoversion (Mesioversion and Distoversion) Supraversion Infraversion

Linguoversion • Maxillary central is linguoverted. Proffit. Contemporary Orthodontics, Second Edition. Mosby, St. Louis. 1993, p. 8.

Labioversion/Buccoversion • Lavioversion: anterior tooth toward the lip • Buccoversion: posterior tooth toward the buccal mucosa Labioversion Buccoversion

Torsoversion • Mesioversion: mesial toward the buccal mucosa or lip • Distoversion: distal toward the buccal mucosa or lip Mesioversion Distoversion

Mesial Drift • Tooth moves forward (not mesioversion)

Supraversion (Supraeruption) • Hypereruption due to no opposing tooth • Brand Isselhard. Anatomy of Orofacial Structures, 7 th Ed. Mosby, St. Louis. 2003, p. 67.

Infraversion Wright. A Textbook of Orthodontics. Second Edition. 1995. Great Britain, Redwood Books, p. 219.

Groups of Teeth • Crossbite – Anterior – Posterior • • • Edge to edge End to end Openbite Overjet Underjet

Anterior Crossbite • Crossbite of 10 year old Proffit. Contemporary Orthodontics, Second Edition. Mosby, St. Louis. 1993, p. 152.

Posterior Crossbite Proffit. Contemporary Orthodontics, Second Edition. Mosby, St. Louis. 1993, p. 8.

End to End • Posterior teeth do not overlap vertically 5 29 Proffit. Contemporary Orthodontics, Second Edition. Mosby, St. Louis. 1993, p. 8.

Openbite • No vertical overlap. • The separation is measured. Proffit. Contemporary Orthodontics, Second Edition. Mosby, St. Louis. 1993, p. 8.

Anterior Openbite

Posterior Openbite • Left posterior (lateral) openbite Wright. A Textbook of Orthodontics. Second Edition. 1995, Great Britain, Redwood Books, p. 218.

Openbite Due to a Tongue Thrust

Overjet Horizontal overlap Of the incisors Measure distance with a probe. Proffit. Contemporary Orthodontics, Second Edition. Mosby, St. Louis. 1993, p. 8.

Overjet: Thumbsucking • Casts of 11 year old twins. The cast to the left continued to suck thumb several hours a day. The cast on the right quit at age 6.

Overbite • Overbite : Vertical overlap Proffit. Contemporary Orthodontics, Second Edition. Mosby, St. Louis. 1993, p. 8.

Overbite Vertical of the incisors A. Normal B. Moderate C. Severe Brand Isselhard. Anatomy of Orofacial Structures, 7 th Ed. Mosby, St. Louis. 2003, p. 61.

Skeletal Profiles • Mesiognathic: Class I • Retrognathic: Class II • Prognathic: Class III

Skeletal Profiles • Mesiognathic: Class I Proffit. Contemporary Orthodontics, Second Edition. Mosby, St. Louis. 1993, p. 147.

Skeletal Profiles • Retrognathic: Class II Proffit. Contemporary Orthodontics, Second Edition. Mosby, St. Louis. 1993, p. 147.

Skeletal Profiles • Prognathic: Class III Proffit. Contemporary Orthodontics, Second Edition. Mosby, St. Louis. 1993, p. 147.

Angle’s Classification • Normal Occlusion • Malocclusions – Class II • Division 1 • Division 2 – Class III

Normal or Class I Mesiobuccal groove of the mandibular 1 st molar and the mesiobuccal cusp tip of the maxillary 1 st molar are aligned. mesiobuccal cusp tip mesiobuccal groove

Normal • Perfect occlusion!!!!

Class I Malocclusion • One or more teeth deviate from normal occlusion. – In the picture, some anterior teeth are torsoverted. Molar relationship is in normal alignment. (Class I, #22, #23 and #26 mesioverted)

Class II Malocclusion • The mesiobuccal groove of the mandibular 1 st molar is distal to the mesiobuccal cusp tip of the maxillary 1 st molar. mesiobuccal cusp tip groove

Class II: Division 1 and 2 Division 1: Anterior teeth flare out Division 2: Anterior teeth retrude

Class II Malocclusion 11 22

Class III Malocclusion Mesiobuccal groove of the mandibular 1 st molar is mesial to the mesiobuccal cusp tip of the maxillary 1 st molar. mesiobuccal cusp tip mesiobuccal groove

Class III 14 11 22 19

Class III Malocclusion Courtesy of Baker College of Port Huron’s Dental Hygiene Clinic

Class III Malocclusion 11 22

Curve of Wilson • Right to left in a posterior view: transverse occlusal curve • Brand Isselhard. Anatomy of Orofacial Structures, 7 th Ed. Mosby, St. Louis. 2003, p. 57.

Sphere of Monson • Curve of Wilson and Spee viewed simultaneously demonstrate sphere of Monson • Brand Isselhard. Anatomy of Orofacial Structures, 7 th Ed. Mosby, St. Louis. 2003, p. 57.