Alignment and Occlusion of the Dentition, Part I Department of Endodontics, Prosthodontics, and Operative Dentistry University of Maryland, Baltimore Pauline Hayes Garrett, D.D.S. Patricia W. Kiln, D.D.S.

This material is taken from: Okeson, J.P. (2003). Management of Temporomandibular Disorders and Occlusion 5th Ed., St. Louis, MO: Mosby, Chapter 3 Wheeler’s Dental Anatomy, Physiology and Occlusion, Ash, Eighth Edition, Saunders, 2003, Chapter 16, pgs Video Clips Ash, Nelson.(2003) Wheeler’s Dental Anatomy, Physiology, and Occlusion 8 th ED. St. Louis,MO: Saunders CD

Objectives! Identify, compare, contrast and describe the clinical significance of axial alignment. Identify, compare, contrast and describe the clinical significance of basic static occlusal relationships.

Factors and Forces that Determine Tooth Position Lips and cheeks Tongue Tooth size Proximal contact Occlusal contact Arch width Illustration modified and Reprinted from: Okeson, J.P. (2003). Management of Temporomandibula r Disorders and Occlusion, 6th Ed., St. Louis, MO: Mosby, Chapter 3.with permission from Elsevier. Pg. 68.

Occlusal Plane (Plane of Occlusion) An imaginary surface, related anatomically to the cranium, which theoretically touches the incisal edges of the incisors and the tips of the cusps of the posterior teeth Not a flat surface Curved due to the varying degrees of inclinations of the teeth

Bonwill’s Triangle 4 inches between the center of the condyles = base of the triangle 4 inches from each condyle to the mesial contact area between the mandibular central incisors-sides of the triangle

The Spherical Theory of the 1930’s: Monson’s Sphere A sphere exists with a radius of 4 inches The center of the sphere is equi-distant from the occlusal surfaces of the posterior teeth and from the centers of the condyle -- Center of Monson’s Sphere ( located in the gabella area of the brain above the condyles)

Harmony Theoretically, a relationship is believed to exist between Bonwell’s Triangle* and Monson’s Sphere*. *Note: These simplistic theories do not apply to all cases. They are oversimplifications and they sparked controversy which led dentistry to the current theories on occlusion used today.

1.From Sagittal plane it is known as the Curve of Spee 2.From Frontal plane it is called the Curve of Wilson 1.From Sagittal plane it is known as the Curve of Spee 2.From Frontal plane it is called the Curve of Wilson Spherical Theory of the 1930’s

Curve of Spee –Alignment of the cusp tips of posterior teeth produces a relatively linear curve in an anteroposterior direction –This curve exists only in the saggital plane, whether it be from a slightly superior view or at the same level of the plane. Remember the curve is “a view of the 3-D sphere” –Curve of the mandibular arch is concave from the level of occlusion. –Curve of the maxillary arch is convex. –Note: if looking down from a slightly superior view, the Curve of Spee relative to the maxillary teeth appears concave. ie. The maxillary teeth fit into the cuped shape of the Curve of Spee

Curve of Wilson The curve formed by an imaginary line touching the buccal and lingual cusp tips of similar teeth on each side of the mandibular arch Typically, viewed in the frontal plane (However, to improve visibility, this image is viewed from the posterior)

Harmony Form follows function: The arches fit a three dimensional plane Not a flat surface “ The curvature of the occlusal plane is primarily a result of the fact that the teeth are positioned in the arches at varying degrees of inclination.” Okeson, J.P. (2003). Management of Temporomandibular Disorders and Occlusion, 5th Ed., St. Louis, MO: Mosby, Chapter 3.with permission from Elsevier. Pg. 71. Illustration modified and Reprinted from: Okeson, J.P. (2003). Management of Temporomandibula r Disorders and Occlusion, 5th Ed., St. Louis, MO: Mosby, Chapter 3.with permission from Elsevier. Pg. 72.

Angulation, Harmony continued

Angulation: (Harmony continued) Maxillary posterior teeth are inclined facially Mandibular posterior teeth are inclined lingually Note how the angulations teeth relate to the Curve of Wilson Illustration modified and Reprinted from: Okeson, J.P. (2003). Management of Temporomandibular Disorders and Occlusion, 5th Ed., St. Louis, MO: Mosby, Chapter 3.with permission from Elsevier. Pg. 73.

Intraarch Alignment

Anatomy of Posterior Surfaces Lingual cusps of maxillary teeth Buccal cusps of mandibular teeth **Note: The loss of a centric supporting cusp could lead to the super eruption of the opposing tooth. Supporting Cusps (centric cusps) Illustration modified and Reprinted from: Okeson, J.P. (2003). Management of Temporomandibular Disorders and Occlusion, 5th Ed., St. Louis, MO: Mosby, Chapter 3.with permission from Elsevier. Pg. 123.

Anatomy of Posterior Surfaces The inner aspect of a posterior tooth is the area between the cusp tips Also called the occlusal table Inner Aspect Illustration modified and Reprinted from: Okeson, J.P. (2003). Management of Temporomandibular Disorders and Occlusion, 5th Ed., St. Louis, MO: Mosby, Chapter 3.with permission from Elsevier. Pg. 74. ** Note: Excessive decay or the loss of an Occlusal restoration could lead to super eruption.

Anatomy of Posterior Surfaces Buccal cusps of maxillary teeth Lingual cusps of mandibular teeth Generally sharper (tip) than supporting cusp, they are not generally in function Inner aspects has potential for functional contact “Guiding cusp”=because in group function the inner aspect has a functional contact Non-Supporting Cusps (Non-centric cusps): Illustration modified and Reprinted from: Okeson, J.P. (2003). Management of Temporomandibular Disorders and Occlusion, 5th Ed., St. Louis, MO: Mosby, Chapter 3.with permission from Elsevier. Pg. 123.

Anatomy of Posterior Surfaces The occlusal area outside the cusp tips Functional Outer Aspect –Small area of the centric cusp (about 1 mm) is the only area in which an outer aspect has any functional significance. This small area functions against the inner incline of the non-centric cusp or non-supporting cusp. This area assist in shearing of food during mastication. Outer Aspect Illustration modified and Reprinted from: Okeson, J.P. (2003). Management of Temporomandibular Disorders and Occlusion, 5th Ed., St. Louis, MO: Mosby, Chapter 3.with permission from Elsevier. Pg. 72.& 73.

Note: Where function occurs, wear occurs. As teeth wear they remain in contact due to the mesial drift and super eruption of adjacent teeth.

Maximum Intercuspation The relationship between the maxillary and mandibular teeth which produces the maximal contact between their respective occlusal surfaces

Angle’s Classification of Occlusion Based on the position of the mandibular first molar Angle’s Class I Angle’s Class II Angle’s Class III

Angle’s Class I The mesiobuccal cusp of the mandibular first molar occludes in the embrasure area between the maxillary second premolar and first molar The mesiobuccal cusp of the maxillary first molar is aligned directly over the buccal groove of the mandibular first molar Illustration modified and Reprinted from: Okeson, J.P. (2003). Management of Temporomandibular Disorders and Occlusion, 5th Ed., St. Louis, MO: Mosby, Chapter 3.with permission from Elsevier. Pg. 81

Angle’s Class I The mesiolingual cusp of the maxillary first molar is situated in the central fossa area of the mandibular first molar In Angle’s Class I each mandibular tooth occludes with it’s counterpart and the adjacent tooth mesial to it. Illustration modified and Reprinted from: Okeson, J.P. (2003). Management of Temporomandibular Disorders and Occlusion, 5th Ed., St. Louis, MO: Mosby, Chapter 3.with permission from Elsevier. Pg. 81

Class I Occlusal Contacts The contacts on premolars occur between cusp tips and opposing marginal ridges The contacts on molars occur on both cusp tip and fossae and cusp tip and marginal ridges Illustration modified and Reprinted from: Okeson, J.P. (2003). Management of Temporomandibular Disorders and Occlusion, 5th Ed., St. Louis, MO: Mosby, Chapter 3.with permission from Elsevier. Pg. 81

Occlusal Contacts, Angles Class I Centric cusps contact in central fossa areas and marginal ridge areas. Illustration modified and Reprinted from: Okeson, J.P. (2003). Management of Temporomandibular Disorders and Occlusion, 5th Ed., St. Louis, MO: Mosby, Chapter 3.with permission from Elsevier. Pg. 81

Angles Class I Illustration above modified and Reprinted from: Okeson, J.P. (2003). Management of Temporomandibular Disorders and Occlusion, 5th Ed., St. Louis, MO: Mosby, Chapter 3.with permission from Elsevier. Pg. 81

Note Cusp Tips: Mandibular cones in maximum intercuspation Positive Wax Addition Technique: (Technique originally developed by Dr. Everett Payne and then modified by Dr. Peter K. Thomas

Waxing Completed (Lingual view) Mandibular teeth are waxed to completion utilizing a positive waxing technique to allow the various area of the occlusal table to be viewed.

Occlusal Contacts Contacts shown with Zinc Stearate When properly waxed, the occlusion is supported harmoniously by including contacts in three main areas. –Central Fossa, Marginal Ridge and Centric Supporting Cusps

Occlusal Contacts, Class I Each tooth contacts two teeth in the opposing arch except the mandibular central incisors and the maxillary third molars Each tooth occludes with its namesake in the opposing arch and an adjacent tooth Illustration modified and Reprinted from: Okeson, J.P. (2003). Management of Temporomandibular Disorders and Occlusion, 5th Ed., St. Louis, MO: Mosby, Chapter 3.with permission from Elsevier. Pg. 80.

Angle’s Class II Illustration on the left above modified and Reprinted from: Okeson, J.P. (2003). Management of Temporomandibular Disorders and Occlusion, 5th Ed., St. Louis, MO: Mosby, Chapter 3.with permission from Elsevier. Pg. 85

Class II

Angle’s Class III The distobuccal cusp of the mandibular first molar occludes with the embrasure between the maxillary first molar and the maxillary second premolar The mesiobuccal cusp of the maxillary first molar is situated over the embrasure between the mandibular first and second molar The mesiolingual cusp of the maxillary first molar occludes with the mesial pit of the mandibular second molar Illustrations modified and Reprinted from: Okeson, J.P. (2003). Management of Temporomandibular Disorders and Occlusion, 5th Ed., St. Louis, MO: Mosby, Chapter 3.with permission from Elsevier. Pgs. 82 & 85

Class III Occlusion

Alignment Video Clips Ash, Nelson.(2003) Wheeler’s Dental Anatomy, Physiology, and Occlusion 8th ED. St. Louis,MO: Saunders CD

Buccoocclusal Line (B-O line) An imaginary line extended through all the buccal cusp tips of the mandibular posterior teeth Represents the general arch form Demarcation between the inner and outer aspects of the buccal cusps Illustration modified and Reprinted from: Okeson, J.P. (2003). Management of Temporomandibular Disorders and Occlusion, 5th Ed., St. Louis, MO: Mosby, Chapter 3.with permission from Elsevier. Pg. 77.

Linguoocclusal Line (L-O Line) An imaginary line extended through the lingual cusp tips of maxillary posterior teeth Represents the general arch form Demarcation between outer and inner aspects of lingual cusps Illustration modified and Reprinted from: Okeson, J.P. (2003). Management of Temporomandibular Disorders and Occlusion, 5th Ed., St. Louis, MO: Mosby, Chapter 3.with permission from Elsevier. Pg. 77.

Central Fossa Line (C-F Line) An imaginary line extended through the central developmental grooves of the maxillary and mandibular posterior teeth Represents the general arch form Proximal contact areas are generally located slightly buccal to the C-F line Allows food to be shunted toward the tongue Illustration modified and Reprinted from: Okeson, J.P. (2003). Management of Temporomandibular Disorders and Occlusion, 5th Ed., St. Louis, MO: Mosby, Chapter 3.with permission from Elsevier. Pg. 78.

Landmarks of Occlusion: Class 1 Occlusion

Common Occlusal Relationships of Anterior Teeth The maxillary anterior teeth are normally positioned labial to mandibular anterior teeth The maxillary anterior teeth overlap the mandibular anterior teeth almost ½ the length of the mandibular crowns Both maxillary and mandibular teeth are inclined labially Illustration above left modified and Reprinted from: Okeson, J.P. (2003). Management of Temporoman dibular Disorders and Occlusion, 5th Ed., St. Louis, MO: Mosby, Chapter 3.with permission from Elsevier. Pg. 83.

Common Inter arch Relationships of Anterior Teeth Incisal edges of mandibular incisors contact the lingual surfaces of maxillary incisors in the lingual fossa Normally the maxillary anterior teeth overlap the mandibular anterior teeth almost 1/2 the length of the mandibular crowns Contacts are lighter as anterior teeth are not designed for heavy occlusal function Illustration modified and Reprinted from: Okeson, J.P. (2003). Management of Temporomandib ular Disorders and Occlusion, 5th Ed., St. Louis, MO: Mosby, Chapter 3.with permission from Elsevier. Pg. 84.

Two Types of Overlap Horizontal Overlap= Overjet Vertical Overlap= Overbite Illustration reprinted from: Wheeler’s Dental Anatomy, Physiology and Occlusion, Ash, Eighth Edition, Saunders, 2003.with permission from Elsevier. pg. 453.

Functional Purposes of Anterior Teeth To guide the mandible through eccentric or lateral movements-called anterior guidance To incise food Speech, lip support and esthetics Illustration modified and Reprinted from: Okeson, J.P. (2003). Management of Temporomandibular Disorders and Occlusion, 5th Ed., St. Louis, MO: Mosby, Chapter 3.with permission from Elsevier. Pg. 83.

Anterior Guidance The anterior tooth contacts that provide guidance of the mandible affected by horizontal overlap and vertical overlap or overbite Illustrations above modified and Reprinted from: Okeson, J.P. (2003). Management of Temporomandibular Disorders and Occlusion, 5th Ed., St. Louis, MO: Mosby, Chapter 3.with permission from Elsevier. Pgs. 123 & 90.

Anterior Guidance PosteriordisocclusionPosteriordisocclusion Anterior guiding contacts

To Be Continued!!!!!!