Dental Arch Introduction And Definitions PDF

INTRODUCTION AND DEFINITIONS  OCCLUSION The static relationship between the incising or masticating surfaces of the maxillary or mandibular teeth or tooth analogues.  NORMAL OCCLUSION A situation commonly found in the absence of disease. The normal oc...

INTRODUCTION AND DEFINITIONS  OCCLUSION The static relationship between the incising or masticating surfaces of the maxillary or mandibular teeth or tooth analogues.  NORMAL OCCLUSION A situation commonly found in the absence of disease. The normal occlusion provides 138 occlusal contacts in closure of 32 teeth It is very seldom, if ever reached.  DENTAL ARCH FORM The geometric shape of the dental arch when viewed in the horizontal plane (square, tapering, ovoid)  NORMAL ARC SIZE The arch form of the maxilla tends to be larger than that of the mandible. This results in the maxillary teeth "overhanging" the mandibular teeth when the teeth are in occlusion. During mastication, the cheeks, lips and tongue are less likely to be caught. CLASS I (NORMAL ARCH SIZE) ARCH LENGTH DISCREPANCY The abnormal relationship between the size of the mandible and/or maxilla and their component teeth, especially as viewed and analyzed in the occlusal plane.  ABNORMAL ARCH SIZE Small mandible (class II) Large mandible (class III)  TEETH POSITION IN DENTAL ARCH Certain teeth, because of their size are positioned to the lingual or labial aspect of the ideal curve. The labial surface of maxillary lateral incisors is more lingually placed. The buccal surface of cuspids are more buccally placed. The buccal surface of the maxillary first molar is positioned to the buccal.  STABILITY OF THE OCCLUSION VERTICALLY Maintenance of tooth position vertically are dependent on occlusal and eruptive forces. As long as all of these forces are balanced, the teeth and the occlusion will remain stable. Upon tooth extraction, the occlusal force is reduced and the teeth will shift, disrupting a previously stable occlusion.  STABILITY OF THE OCCLUSION HORIZONTALLY The lip and cheek pressure from outside and the tongue pressure from inside stabilize the teeth horizontally. The neutral zone: The potential space between the lips and cheeks on one side and the tongue on the other; that area or position where the forces between the tongue and cheeks or lips are equal. CURVATURES OF THE DENTAL ARCHES  CURVE OF OCCLUSION The average curve established by the incisal edges and occlusal surfaces of the anterior and posterior teeth in either arch  CURVE OF SPEE The cusps and incisal ridges of the teeth tend to display a curved alignment when the arches are observed from a point opposite the first molars.  MONSON’S CURVE Each cusp and incisal edge touches or conforms to a segment of the surface of a sphere 8 inches in diameter with its center in the region of the glabella Glabella: The smooth area between the eyebrows just above the nose.  CURVE OF WILSON The cusp tips in both sides of molars in a section through the frontal plane forms a mediolateral curve (Wilson). CURVE OF PLEASURE (ANTI-MONSON) A helicoids curve of occlusion that, when viewed in the frontal plane, conforms to a curve that is convex from the superior view, a-Curve of Wilson except for the last b- Flat occlusal surface molars which c-Curve of Pleasure reverse that pattern. (Anti-Monson)  COMPENSATING CURVE The curvature of the occlusal plane of complete dentures, created to permit balanced occlusion.  REFERENCES Academy of Prosthodontics (2013): The glossary of prosthodontic terms, J. Prosthet. Dent. 1- Howat A.P, Capp N.J, Parrett N.V.J: A color atlas of occlusion and mal occlusion. Wolf publishing LTD, London, 1991 2- Dawson P. E: Functional occlusion from TMJ to smile design. Mosby Inc., St. Louis, 2007. 4. Ramfjord SP, Ash MM: Occlusion, ed 4, Philadelphia, 1983, WB Saunders. 5- Thomson H.: Occlusion in clinical practice, Bristol, London and Boston, Whright P.S.G. 1981. 6- Simpson G.W.: On Johnson's Modem Practice in Fixed prosthodontics, 4th. Ed, Philadelphia, Toronto, W.B. Saunders Co., 1986.