《口腔医学-牙合学》课件ppt第1章 牙合（英文）

Occlusion nOcclusion 牙合 is defined as the static relationship of teeth nArticulation 咬合 is defined as the dynamic relationship of teeth nTooth alignment and occlusion is important in masticatory function nTooth positioning is not a random process nA number of controlling factors are involved Esthetic smile BMC 59.1 Concepts of Occlusion Concepts of Occlusion Balanced Occlusion nBilateral and balancing contacts through all excursive movements nProtrusive 前伸 nLaterotrusive 侧方 nDeveloped for complete dentures nRationale was thought to provide stability to dentures through all excursive movements Esthetic smile BMC 59.1 Concepts of Occlusion Optimal Occlusion Dynamic Individual Occlusion nConcept is based on function and health rather than any ideal occlusal arrangement nIn the absence of pathology, no treatment to change a patients occlusion would be necessary nDeveloped in the late 1970s Esthetic smile BMC 59.1 Morphological classification malocclusion normal occlusion individual normal occlusion; ideal normal occlusion Functional classification physiological occlusion pathological occlusion Clinical classification adaptable occlusion unadaptable occlusion Classification of Occlusion Tooth Alignment and Occlusion nFactors determining tooth position nNormal intra-arch relationships nNormal interarch relationships Sagittal view of human skull BMC 62.6 Tooth Alignment and Occlusion Factors determining tooth position nForces from many directions act to position the tooth in a position of equilibrium nLips nCheeks nTongue nForces are light and constant nHave the ability to move teeth over time nTooth stability is achieved in the neutral position Anterior (top) and posterior (bottom) teeth in neutral position Okeson Fig. 3-1 Tooth Alignment and Occlusion Factors determining tooth position nWhen a tooth erupts out of alignment, forces from the tongue and lip can move the tooth to the neutral position nMust be adequate space for the tooth nIf there is crowding, the muscular forces are insufficient to produce the necessary movement nOrthodontic treatment would then be required Anterior (top) and posterior (bottom) teeth in neutral position Okeson Fig. 3-1 Tooth Alignment and Occlusion Factors determining tooth position nErupted teeth will be moved until an equilibrium is established nLarge tongue nTongue thrust nOral habits nThumb sucking nFinger sucking nPencil sucking nChewing on a pipe nMusical instruments Anterior open bite due to a large tongue (tongue at rest) Okeson Fig. 3-2a Tooth Alignment and Occlusion Factors determining tooth position nErupted teeth will be moved until an equilibrium is established nTongue thrust nAn anterior open bite has resulted from excessive labially directed forces from the tongue Very active tongue producing an open bite Okeson Fig. 3-2c Tooth Alignment and Occlusion Factors determining tooth position Forces on proximal tooth surfaces Contacts with adjacent teeth maintain normal alignment There is a normal mesial migration of teeth towards the midline Normal function produces proximal surface wear Mesial migration tends to maintain contacts Consequences of loss of a single molar Okeson Fig. 3-2d Tooth Alignment and Occlusion Normal Intra-arch Relationships nPlane of occlusion (PO) nA line through the mandibular incisal ridges and the DB cusps of the second molars nActually a planar mean of the curvature of the surfaces nNot flat nGenerated by a line drawn through all buccal cusp tips and incisal ridges connecting the lingual cusps and producing a plane nCurved plane to allow multiple areas of contact during mandibular movement nA result of inclination of teeth within the arches Orientation lines and planes AE angle of eminentia FH Frankfort horizontal CS Curve of Spee PO Plane of occlusion IG Incisal guidance Ash Fig. 2-16 Tooth Alignment and Occlusion Normal Intra-arch Relationships nPlane of occlusion (PO) nA line through the mandibular incisal ridges and the DB cusps of the second molars nActually a planar mean of the curvature of the surfaces nNot flat nGenerated by a line drawn through all buccal cusp tips and incisal ridges connecting the lingual cusps and producing a plane nCurved plane to allow multiple areas of contact during mandibular movement nA result of inclination of teeth within the arches Sagittal view of the angulation of mandibular teeth Okeson Fig. 3-5 Tooth Alignment and Occlusion Normal Intra-arch Relationships nPlane of occlusion (PO) nA line through the mandibular incisal ridges and the DB cusps of the second molars nActually a planar mean of the curvature of the surfaces nNot flat nGenerated by a line drawn through all buccal cusp tips and incisal ridges connecting the lingual cusps and producing a plane nCurved plane to allow multiple areas of contact during mandibular movement nA result of inclination of teeth within the arches Sagittal view of the angulation of maxillary teeth Okeson Fig. 3-6 Tooth Alignment and Occlusion Normal Intra-arch Relationships nPlane of occlusion (PO) nA line through the mandibular incisal ridges and the DB cusps of the second molars nActually a planar mean of the curvature of the surfaces nNot flat nGenerated by a line drawn through all buccal cusp tips and incisal ridges connecting the lingual cusps and producing a plane nCurved plane to allow multiple areas of contact during mandibular movement nA result of inclination of teeth within the arches Frontal view of the angulation of maxillary teeth Okeson Fig. 3-7 Tooth Alignment and Occlusion Normal Intra-arch Relationships nPlane of occlusion (PO) nA line through the mandibular incisal ridges and the DB cusps of the second molars nActually a planar mean of the curvature of the surfaces nNot flat nGenerated by a line drawn through all buccal cusp tips and incisal ridges connecting the lingual cusps and producing a plane nCurved plane to allow multiple areas of contact during mandibular movement nA result of inclination of teeth within the arches Frontal view of the angulation of mandibular teeth Okeson Fig. 3-8 Tooth Alignment and Occlusion Normal Intra-arch Relationships nCurve of Spee nAnteroposterior curvature of the arch nFormed by a line joining the mandibular incisal ridges to the buccal cusps of the mandibular posterior teeth Curve of Spee- the anteroposterior curvature of the arch Mohl Fig. 4-4 Tooth Alignment and Occlusion Normal Intra-arch Relationships nCurve of Wilson nMediolateral curvature of the arch nFormed by drawing a line through the buccal and lingual cusps of the molars nUsually concave in an unworn dentition nCan be convex when the dentition is worn (resulting in shorter buccal cusps of the mandibular molars; called a reverse Curve of Wilson. Curve of Wilson- the mediolateral curvature of the arch (posterior view Mohl Fig. 4 -5a Tooth Alignment and Occlusion Normal Intra-arch Relationships nCurve of Wilson nMediolateral curvature of the arch nFormed by drawing a line through the buccal and lingual cusps of the molars nUsually concave in an unworn dentition nCan be convex when the dentition is worn (resulting in shorter buccal cusps of the mandibular molars Curve of Wilson- the mediolateral curvature of the arch (posterior view Mohl Fig. 4 -5b Tooth Alignment and Occlusion Normal Intra-arch Relationships nStandardized formulae were sought to describe intra-arch relationships nBonwill, WGA 1889 nDescribed a 4 inch equilateral triangle from condylar centres to mesial of the mandibular incisors nMonson, GS 1932 nDescribed a sphere (“Sphere of Monson”) with a radius of 4 inches that was equidistant from the condylar centres and the occlusal surfaces of the posterior teeth nBoth are oversimplifications and generalizations that apply to some people but not all nRepresent a geometrical ideal Bonwills triangle and Monsons sphere Mohl Fig. 12-3 Tooth Alignment and Occlusion Normal Intra-arch Relationships nOcclusal surfaces of the teeth nCusps nCusp ridges nGrooves nSulci nFunction in breaking up food into smaller pieces nOcclusal table n50-60% of the total buccolingual dimension of the tooth nMasticatory forces are applied to this area nPositioned within the confines of the root Occlusal table (top) Okeson Fig. 3-9 Outer and inner inclines of the crown (bottom) Okeson Fig. 3- 10 Tooth Alignment and Occlusion Normal Intra-arch Relationships nOcclusal surfaces of the teeth nCusps nCusp ridges nGrooves nSulci nFunction in breaking up food into smaller pieces nOcclusal table n50-60% of the total buccolingual dimension of the tooth nMasticatory forces are applied to this area nPositioned within the confines of the root Mesial and distal inclines of teeth Okeson Fig. 3-11 Tooth Alignment and Occlusion Normal Interarch Relationships Normal buccolingual relationship of the molars Okeson Fig. 3-12 An interarch relationship relates the teeth in one arch to the teeth in the other arch As the mandible closes, the occlusal relationship of the teeth is determined Arch length Distance from the distal surface of one third molar to the other in the same arch 128mm Max arch 126mm Mand arch Arch width Distance across the arch Mandibular width is slightly less than maxillary width Tooth Alignment and Occlusion Normal Interarch Relationships Normal buccolingual relationship of the molars Modified after Okeson Fig. 3- 12 Normal buccolingual relationship allows for efficient use of musculature in chewing Minimizing trauma from cheek or tongue- biting Supporting cusps buccal cusps of Mandibular posterior teeth lingual cusps of Maxillary posterior teeth Centric cusps Centric holding cusps Stamp cusps Maintain vertical dimension or distance between the maxilla and mandible Tooth Alignment and Occlusion Normal Interarch Relationships Centric holding cusp position (mandibular first molar) BLUE centric cusps YELLOW non-centric cusps Okeson Fig. 3-14 Centric holding cusps are important in mastication Contact occurs on outer and inner inclines of the cusp Centric holding cusp position is approximately 1/3 into the total buccolingual dimension What is the significance of the position of the centric cusps in this buccolingual direction? Forces are directed over the long axis of the tooth and are dissipated through the root. Tooth Alignment and Occlusion Normal Interarch Relationships Normal buccolingual relationship of the molars Modified after Okeson Fig. 3- 12 Guiding cusps lingual cusps of Mandibular posterior teeth buccal cusps of Maxillary posterior teeth Non-centric cusps Non-centric holding cusps Shear cusps Non-centric holding cusp position is approximately 1/6 into the total buccolingual dimension Cusps tend to be sharper with defined cusp ridges and tips Tooth Alignment and Occlusion Normal Interarch Relationships FUNCTIONAL OUTER ASPECT Outer aspect of centric cusp contacts about 1mm Functional Outer Aspect Modified after Okeson Fig. 3- 15 Tooth Alignment and Occlusion Normal Interarch Relationships Crossbite relationship of the molars Okeson Fig. 3-13 Identify the centric holding cusps when there is a posterior crossbite relationship. LINGUAL CUSPS of Mandibular posterior teeth BUCCAL CUSPS of Maxillary posterior teeth Tooth Alignment and Occlusion Normal Interarch Relationships Mandibular bucco-occlusal line Okeson Fig. 3-16 Contact Relationships- Buccolingual A line drawn through the buccal cusps of mandibular teeth illustrates the Bucco-occlusal line Line follows arch form and is smooth and continuous Line divides the outer and inner aspects of the mandibular centric cusps Tooth Alignment and Occlusion Normal Interarch Relationships Maxillary bucco-occlusal line Okeson Fig. 3-17 Contact Relationships- Buccolingual A line drawn through the lingual cusps of maxillary teeth illustrates the Linguo-occlusal line Line follows arch form and is smooth and continuous Line divides the outer and inner aspects of the mandibular centric cusps Tooth Alignment and Occlusion Normal Interarch Relationships Central fossa line Okeson Fig. 3-18 Contact Relationships- Buccolingual A continuous line drawn through the central developmental grooves of maxillary and mandibular posterior teeth illustrates the Central fossa (CF) line Line follows arch form and is smooth and continuous Tooth Alignment and Occlusion Normal Interarch Relationships Central fossa line, contacts and embrasures Modified after Okeson Fig. 3-18 The contacts are usually slightly buccal to the central fossa line. Tooth Alignment and Occlusion Normal Interarch Relationships Central fossa line, contacts and embrasures Modified after Okeson Fig. 3-18 The buccal embrasure is smaller and shaped like a wide V. The lingual embrasure area is larger and is shaped like a long narrow V. Tooth Alignment and Occlusion Normal Interarch Relationships Central fossa line, contacts and embrasures Modified after Okeson Fig. 3-18 What is the clinical significance of the contact position and embrasure shape? The lingual embrasure acts as a spillway. Food is directed towards the tongue during mastication. The tongue then directs the food back towards the occlusal table. This is more efficient than having the perioral and buccinator muscles direct food towards the occlusal table in the other direction. Tooth Alignment and Occlusion Normal Interarch Relationships Central fossa line and bucco- occlusal line Okeson Fig. 3- 20 In a normal occlusion, the MANDIBULAR BUCCAL CUSPS (CHC) will occlude in the central fossa and on marginal ridges of the maxillary posterior teeth. Tooth Alignment and Occlusion Normal Interarch Relationships Central fossa line and bucco- occlusal line Okeson Fig. 3- 20 In a normal occlusion, the MAXILLARY LINGUAL CUSPS (CHC) will occlude in the central fossa and on marginal ridges of the mandibular posterior teeth. Tooth Alignment and Occlusion Normal Interarch Relationships Normal contacts in a Class I occlusion Okeson Fig. 3-23 Contact Relationships- Mesiodistal Occlusal contacts result from centric cusps contacting the opposing CF line Contacts will occur in or on Central fossae AND Marginal ridges and embrasures Tooth Alignment and Occlusion Normal Interarch Relationships Normal contacts in a Class I occlusion Modified after Okeson Fig. 3-23 Contact Relationships- Mesiodistal Occlusal contacts result from centric cusps contacting the opposing CF line Contacts will occur in Central fossae Comparable to a mortar and pestle（臼杵） Two dissimilar shaped surfaces meet result in a spillway being produced and masticatory efficiency SUMMARY STATEMENTS Mesiolingual cusp of each maxillary molar occludes in the central fossa of the opposing mandibular molar Mesiobuccal cusp of each mandibular molar occludes on the mesial marginal ridge of the opposing maxillary molar Tooth Alignment and Occlusion Normal Interarch Relationships Normal contacts in a Class I occlusion Modified after Okeson Fig. 3-23 Contact Relationships- Mesiodistal Occlusal contacts result from centric cusps contacting the opposing CF line Contacts will occur in Central fossae Comparable to a mortar and pestle Two dissimilar shaped surfaces meet result in a spillway being produced and masticatory efficiency Marginal ridges and embrasures Cusp tip is very convex Marginal ridge is slightly convex (flat by comparison) Actual contact is not cusp tip but 0.5mm area around it Tooth Alignment and Occlusion Normal Interarch Relationships Cusp tip to two marginal ridges (embrasure) contact Okeson Fig. 3-22 Contact Relationships- Mesiodistal Occlusal contacts result from centric cusps contacting the opposing CF line Contacts will occur in Central fossae Comparable to a mortar and pestle Two dissimilar shaped surfaces meet result in a spillway being produced and masticatory efficiency Marginal ridges and embrasures Cusp tip is very convex Marginal ridge is slightly convex (flat by comparison) Actual contact is not cusp tip but 0.5mm area around it Tooth Alignment and Occlusion Normal Interarch Relationships Cusp tip to marginal ridge contact Modified after Okeson Fig. 3-22 Contact Relationships- Mesiodistal Occlusal contacts result from centric cusps contacting the opposing CF line Contacts will occur in Central fossae Comparable to a mortar and pestle Two dissimilar shaped surfaces meet result in a spillway being produced and masticatory efficiency Marginal ridges and embrasures Cusp tip is very convex Marginal ridge is slightly convex (flat by comparison) Actual contact is not cusp tip but 0.5mm area around it Tooth Alignment and Occlusion Normal Interarch Relationships Cusp tip to marginal ridge contact Modified after Okeson Fig. 3-22 Contact Relationships- Mesiodistal Each tooth contact two teeth in a normal Class I occlusion with two exceptions Which teeth only occlude with one opposing tooth? Mandibular central incisors contact only the maxillary central incisor Maxillary third molars contact only the mandibular third molars The one tooth to two teeth contact relationship assists in force distribution Tooth Alignment and Occlusion Normal Interarch Relationships The mandibular first molar is positioned mesial to the maxillary first molar Interarch relationship of opposing teeth Modified after Okeson Fig. 3-21 Contact Relationships- Occlusal contacts of posterior teeth The mesiobuccal cusp of the mandibular first molar occludes in the embrasure between the maxillary second premolar and the first molar The mesiobuccal cusp of the maxillary first molar is opposite the mesiobuccal (buccal) groove of the mandibular first molar The mesiolingual cusp of the maxillary first molar occludes in the central fossa of the mandibular first molar Tooth Alignment and Occlusion Normal Interarch Relationships The mandibular first molar is positioned mesial to the maxillary first molar Class I molar relationship (facial view) BMC 62.11a Contact Relationships- Occlusal contacts of posterior teeth The mesiobuccal cusp of the mandibular first molar