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Occlusion

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Occlusion Occlusion Presentation Transcript

  • INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
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  • • INTRODUCTION • DEFINITIONS • REVIEW OF LITERATURE • EVOLUTION OF OCCLUSION • NATURAL OCCLUSION&ARTIFICIAL OCCLUSION • REQUIREMENTS OF ‘C D ’OCCLUSION • AXIMS FOR ARTIFICIAL OCCLUSION • POSTERIOR TOOTH FORMS • CONCEPTS OF OCCLUSION • CONCLUSION www.indiandentalacademy.com
  •  Occlusion is any contact between the incising or masticatory surfaces of upper and lower teeth.  Most important subject in all branches of dentistry.  Articulation www.indiandentalacademy.com
  • • Importance of occlusion 1 . Vertical & lateral components of occlusal stresses 2 . In case of F P D’s harmonious occlusion 3 . Inharmonious occlusion 4 . Repeated fracture of facings www.indiandentalacademy.com
  • caries malocclusion www.indiandentalacademy.com
  •  OCCLUSION ( G P T 8 ) “ The static relationship between incising or masticating surfaces of the maxillary or mandibular teeth or tooth analogues . ” www.indiandentalacademy.com
  •  CENTRIC OCCLUSION “ The occlusion of opposing teeth when the mandible is in centric relation . This may or may not coincide with the maximal inter cuspation ”  ECCENTRIC OCCLUSION “ An occlusion other than centric occlusion ” www.indiandentalacademy.com
  •  Articulation “ the static and dynamic contact relationship between the occlusal surfaces of teeth during function . ” www.indiandentalacademy.com
  •  Balanced occlusion “ The bilateral , simultaneous , anterior , and posterior occlusal contact of teeth in centric and eccentric positions ” www.indiandentalacademy.com
  •  Maximum intercuspation “ the complete intercuspation of opposing teeth independent of condylar position , sometimes referred to as best fit of teeth regardless of the condylar position ” www.indiandentalacademy.com
  •  Lingualised articulation ( S. Howard payne in 1941 ) “ this form of denture occlusion articulates the maxillary lingual cusps with the mandibular occlusal surfaces , in centric working and non working mandibular positions . ” www.indiandentalacademy.com
  •  Monoplane occlusion “ an occlusal arrangement where in the posterior teeth have masticatory surfaces that lack any cuspal height ” www.indiandentalacademy.com
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  • • BALANCED ARTICULATION by ALFRED GYSI 1.33° cusp form 2.30° cusp form by PILKINGTON AND TURNER www.indiandentalacademy.com
  •  In this concept ,a non anatomic occlusal scheme is used with a few modifications.  First one is articulator used  Second one is arrangement of maxillary and mandibular teeth without any vertical overlap  After introduction of 0°teeth posterior teeth are positioned on a flat plane.  Anterior teeth are positioned with a horizontal and vertical overlap www.indiandentalacademy.com
  • • He used 30° cusp teeth that were selectively reshaped to fulfill the concept of lingualised occlusion • L O allows adaptation to different types of ridges , greater masticatory efficiency , elimination of lateral interferences • L O based on the maxillary lingual cusp functioning as the main supporting cusp in harmony with the occlusal surfaces of the lower teeth. www.indiandentalacademy.com
  • • According to this concept the stability of mandibular prosthesis can be improved by using the linear occlusion and steeper occlusal plane. • Linear ( non interceptive ) occlusion consists of following requirements 1 . Zero degree teeth are opposed by bladed teeth 2 . Mandibular teeth are set to a flat occlusal plane 3 . There is no anterior tooth interference to protrusive or lateral movement. www.indiandentalacademy.com
  •  Study on a clinical trial comparing anatomic, lingualised , and zero degree posterior occlusal forms for complete dentures.  concluded that , lingualised posterior occlusal forms were superior in reducing sore spots , ability to eat , meal interruptions compared to 0° posterior occlusion. www.indiandentalacademy.com
  • BONWILL’S “ Equilateral triangular concept ” He believed that articulation of teeth guides the mandible during function. He postulated that the distance from incisal edges of lower incisors to each condyle is 4 inches ( 10 cm ) and the distance between each condyle is also 4 inches. www.indiandentalacademy.com
  •  Ferdinand Graf Von Spee ( 1890 )  There is a relationship between the curved arrangements of the occlusal planes of natural teeth and the corresponding curves of the condylar paths.  He described the forward movement of mandible in sagittal plane.  Concentric arcs shows nature of protrusive movement of mandible.  Total contacts of molar masticatory surfaces lies on same arc of a circle.  Posteriorly arc touches most anterior point of condyle www.indiandentalacademy.com
  • F.G.VON SPEE www.indiandentalacademy.com
  •  Axis of these arcs lies at the level of horizontal mid orbital plane.  Steeper the path of condyle , more pronounced the tooth curve would be because both have same radius. www.indiandentalacademy.com
  •  “ Carl christensen ”observed the opening of posterior teeth in mandibular protrusion .  First to describe an intra oral method of recording a static protrusive record to determine condylar inclination.  Ulf Posselt. www.indiandentalacademy.com
  •  George S Monson in 1916  It was based on the concept that the mandibular teeth move over the occlusal surfaces of maxillary teeth as over the external surface of a segment of an 8 inch sphere and the radius of a sphere is located in the region of crista galli www.indiandentalacademy.com
  • MONSON’S SPHERICAL THEORY www.indiandentalacademy.com
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  •  According to this concept if 2 equilateral triangles ( Bonwill) were placed back to back they would share a common base that represented the condylar axis.  Vertex of anterior triangle incisor point  posterior triangle external occipital protruberance www.indiandentalacademy.com
  •  Reverse curve will stabilize the lower denture  Based on observation that occlusion of dentures and natural dentition were in a reverse curve fashion i.e. maxillary lingual and mandibular buccal cusps .  Main draw back www.indiandentalacademy.com
  •  Max pleasure in 1937 introduced “ pleasure curve ” which advocates “ anti -monson curve ” exept for second molars.  In pleasure curve reverse curve is used in bicuspid area for lever balance, flat occlusion is set in first molar area and a spherical scheme in second molar area. www.indiandentalacademy.com
  • PLEASURE CURVE www.indiandentalacademy.com
  •  Technique involve restoring mandibular posterior occlusion to a 4 inch sphere.  Maxillary posterior occlusion was fabricated to mandibular occlusal form by using maxillary anterior teeth as guide.  According to Schuyler 1.balancing side contacts were eliminated 2.importance of incisal guidance was elevated 3.concept of long centric was proposed in which centric occlusion is thought as an area of contact rather than a point contact. www.indiandentalacademy.com
  •  Condyles were the determinants of occlusal schemes, and the side shift of condyles would greatly affect cuspal position.  Hinge axis was located by rotational centers of condyles  3-dimensional envelope of motion of condyles are recorded by pantographic tracings  Maximum inter cuspation of teeth when the condyles are in their hinge position www.indiandentalacademy.com
  • NATURAL vs ARTIFICIAL OCCLUSION www.indiandentalacademy.com
  •  Natural 1.Teeth retained by periodontal tissues 2. Teeth receive individual pressures of occlusion. 3.malocclusion- uneventfull for years. 4. Non vertical forces effect only the teeth involved and tolerated. 5.Incising  Artificial 1.Allteeth are on bases seated on slippery tissues. 2.Teeth move as a unit 3.Malocclusion causes immediate response. 4.Involves all teeth on base and traumatic. 5. Incising affects all teeth on base. www.indiandentalacademy.com
  •  Natural 6.Second molar – masticating area 7.Bilateral balance is rarely found 8.Force necessory to masticate food 5-175 pounds.  Artificial 6. Cuases tilting of bases ( inclined plane effect ) 7.Bilateral balance is necessary for stability 8.11.7 pounds www.indiandentalacademy.com
  •  Stability of occlusion  Balanced occlusal contacts  Unlocking of cusps mesio distally  Horizontal force controlled by bucco lingual cusp height reduction  Functional lever balance  Cutting, penetrating, shearing  Anterior incisal clearance  Minimum occlusal contact area  Sharp ridges or cusps www.indiandentalacademy.com
  •  Shorp incising units  They should not contact during mastication  Flat incisal guidance  Horizontal over lap  Contact only during protrusive incising www.indiandentalacademy.com
  •  Efficient in cutting and grinding  Decreased bucco-lingual width  Function as a group with simultaneous harmoneus contacts  Over the crest of ridge for lever balance  Have a surface to receive and transmit force of occlusion vertically  Plane of occlusion should be as parallel as possible www.indiandentalacademy.com
  •  Contact on 2nd molars when incising units contacts  Contact at the end of chewing cycle when working units contacts  Smooth gliding contacts for lateral and protrusive movements www.indiandentalacademy.com
  •  Smaller occlusal area– smaller crushing force  Vertical force on inclined occlusal surfaces  Vertical force on denture base with resilient tissues  Vertical force lateral to ridge crest  Vertical force on inclined supporting tissues www.indiandentalacademy.com
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  •  Hundreds of years ago teeth were carved from stone, wood, ivory and metal.  Human teeth  3 types a) anatomic teeth of 33˚ or more b)modified anatomic teeth between 3o˚and 0° c)non anatomic or zero degree www.indiandentalacademy.com
  • ANATOMIC MODIFIED ANATOMIC NON ANATOMIC www.indiandentalacademy.com
  •  In 1913 Dr. Alfred Gysi of Switzerland carved the first anatomic porcelain tooth.  Marketed by Dentist supply company and were called Trubyte.  They had transverse ridges for tight inter digitation  Pilkington and turner’s 30˚  Allow for small degree of freedom in protrusive but tight interlocking in lateral excursions www.indiandentalacademy.com
  •  In 1927 Gysi also introduced the cross-bite teeth.  Maxillary buccal cusp was almost eliminated resulting one prominent lingual cusp that occlude into lower anatomic tooth www.indiandentalacademy.com
  •  In 1928 Victor Sears introduced channel teeth.  Maxillary occlusal surfaces consists of deep channel that run mesio distally.  Lower posteriors are half of width in bucco lingually. www.indiandentalacademy.com
  •  Avery bros in 1930 introduced the Scissor bite teeth.  Posterior occlusal surfaces locked antero posteriorly and free in lateral excursion www.indiandentalacademy.com
  •  In 1936 Mc Grane marketed a tooth which he called the curved cusp posterior tooth.  This design lock antero posteriorly but free in laterally in an arc corresponding to an orbitary radius from vertical rotational axis of condyles www.indiandentalacademy.com
  •  In 1937 Max Pleasure proposed to modify the lower posterior teeth occlusal surfaces to a reverse curve by tilting the tooth buccally.  Reverse curve in pre molars , flat occlusal surface on 1st molars and a monson curve on 2nd molar for balance. www.indiandentalacademy.com
  •  John Vincent in 1942 introduced a change in materials by using metal inserts in resin posteriors.  Originally gold solder wire and later stain less steel. www.indiandentalacademy.com
  •  Sosin in 1961 replaced maxillary second bicuspid and first & second molars with cleat shaped vitallium forms called cross-blades.  Levin modified this scheme by reducing the size of the cross- blade to the maxillary lingual cusp. www.indiandentalacademy.com
  •  HALL’S inverted cusp teeth  In 1929 Hall was the first to design cuspless teeth he called inverted cusp tooth.  Tooth was flat with concentric cone shaped depressions on occlusal surfaces www.indiandentalacademy.com
  •  Had a series of transverse bucco- lingual ridges www.indiandentalacademy.com
  •  In 1934 Nelson described teeth he called chopping blocks, which were flat occlusal surfaces with numerous ridges.  Ridges on mandibular teeth ran transversely and on maxillary they ran mesio distally. www.indiandentalacademy.com
  •  In 1946 Hardy designed a metal insert upper and lower posterior which he called Vitallium occlusal. Marketed by Austenal Company and are still in use  Produced in resin blocks of 3 posterior teeth  A narrow vitallium ribbon www.indiandentalacademy.com
  •  In 1951 Myerson Tooth Corporation introduced the first cross-linked acrylic teeth in a flat occlusal scheme called the Shear cusp tooth.  Sears and myerson proposed a combination of porcelain and acrylic occlusal scheme. www.indiandentalacademy.com
  •  In 1952 Coe Masticators designed by Cook  2nd premolars and 1st molars were flat stainless steel castings with holes on the occlusal surfaces diagonally  These teeth occlude with flat upper porcelain teeth www.indiandentalacademy.com
  •  In 1957 Bader introduced cutter bar scheme by opposing upper porcelain cusp less teeth with a metal cutting bar replacing 2nd premolar, 1st & 2nd molar.  Similar to sears channel tooth exept the maxillary molars were flat www.indiandentalacademy.com
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  •  Adjustable articulators  Eccentric records  Harmonious occlusion is lost when bases are not stable  Bases need frequent refitting  Presence of cusps generates more horizontal forces www.indiandentalacademy.com
  •  occlude only in 2-dimension  Less shearing efficiency  Bilateral and protrusive balance is not possible  Esthetically poor. www.indiandentalacademy.com
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  • “ The bilateral , simultaneous , anterior and posterior occlusal contact of teeth in centric and eccentric positions ” Cusp form posterior teeth. Purpose of B O . Balance in natural teeth. www.indiandentalacademy.com
  •  Wider , larger the ridge and closer the teeth to the ridge.  Wider the ridge and narrower the teeth bucco lingually  More lingual the teeth in relation to ridge crest  More centered the force of occlusion antero posteriorly. www.indiandentalacademy.com
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  •  Tooth size and position in relation to ridge size and shape.  Denture base coverage  Occlusal balance at retruded contact position  Right and left eccentric occlusal balance www.indiandentalacademy.com
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  •  Inclination of condylar guidance  The prominence of the compensating curve  The inclination of the plane of occlusion–orientation of occlusal plane  The inclination of incisal guidance  The heights of the cusps – inclination of cusps. www.indiandentalacademy.com
  • CONDYLOR INCLINATION (GUIDANCE )  Determined on the patient by a protrusive record and set on the instrument.  Under the influence of anterior slope of glenoid fossa. www.indiandentalacademy.com
  • SAGITTAL CONDYLOR GUIDANCE ANGLE  Average path taken by the condyle during a farward movement from centric relation position when viewed in a sagittal plane.www.indiandentalacademy.com
  •  : Is the influence of the contacting surfaces of the mandibular and maxillary anterior teeth on mandibular movement.  It can be set by dentist in accordance with esthetics and phonetics.  If the incisal guidance is steep it calls for steep cusps, steep occlusal plane or a steep compensating curve to effect an occlusal balance  Incisal guidance should be as flat as possible. www.indiandentalacademy.com
  • SIGA  Sagittal incisal guidance angle is formed by vertical overlap between teeth. It is only dependent on amount of horizontal overlap. www.indiandentalacademy.com
  • ORIENTATION OF OCCLUSAL PLANE  Is established in the anterior by height of the lower cuspid and in the posterior by the height of the retromolar pad.  Occlusal plane should be similar to the natural teeth. www.indiandentalacademy.com
  • COMPENSATING CURVE  compensating curve is one of the most important factors in establishing a balanced occlusion. The compensating curves eliminate Christensen’s phenomenon to achieve balance.  It is determined by the inclination of the posterior teeth and their vertical relationship to the occlusal plane. A steep condylar path requires a steep compensating curve for occlusal balance. www.indiandentalacademy.com
  • INCLINATION OF THE CUSPS OF THE TEETH  Refers to the angle between the total occlusal surface of tooth and the inclination of the cusp in relation to that surface.  33° tooth inclination.  The basic inclination of cusps can be made steeper www.indiandentalacademy.com
  • FACTORS OF BALANCED OCCLUSION RELATED TO A BALANCE BEAM  If the incisal guidance is made steeper the beam is out of balance. www.indiandentalacademy.com
  • Equation for determining degree of inclination  Cuspal inclination=incisal inclination+1/2(condylar inclination- incisal inclination)  For e.g. c.g is 40°and i.g is 30° Cuspal inclination=30˚+1/2(40˚-30˚) =35° www.indiandentalacademy.com
  • Factors of lateral balance  The inclination of the condylar path on the balancing side.  The inclination of the incisal guidance and cuspid lift.  The inclination of the plane of occlusion on the balancing side and working side.  The compensating curve on the balancing side and working side.  The buccal cusp heights or inclinations on the balancing side.  The lingual cusp heights or inclination on the working side.  The Bennett side shift on the working side. www.indiandentalacademy.com
  • An occlusion for all reasons www.indiandentalacademy.com
  • LINGUALIZED OCCLUSION  First described by S. Howard Payne, DDS, in 1941,  This form of denture occlusion articulates the maxillary lingual cusps with the mandibular occlusal surfaces in centric, working and nonworking mandibular positions. The term is attributed to Earl Pound.  Maxillary Lingual Cusps acts as the centric holding cusps www.indiandentalacademy.com
  • LINGUALIZED OCCLUSION • No contact of the maxillary buccal cusps with mandibular buccal or lingual cusps.  Anatomic teeth are used in maxillary arch.  Semi Anatomic or non anatomic teeth can be selected for mandibular arch. www.indiandentalacademy.com
  • MOLDS FOR LINGUALISED OCCLUSION  Maxillary teeth are anatomic  Mandibular occlusal forms require some minor reshaping www.indiandentalacademy.com
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  • RATIONALE FOR LINGUALISED OCCLUSION  Maximum intercuspation must occur at the centric jaw relation position  An absence of deflective occlusal contacts or tooth interferences must be observed between opposing teeth  The arrangement and articulation of artificial tooth forms must provide enough cusp height to permit selective occlusal reshaping to achieve an absence of interferences  A natural and pleasing appearance must be achievable with the tooth arrangement www.indiandentalacademy.com
  • Factors in the tooth molds for lingualized articulation  The mandibular arch offers the most recognizable anatomic landmarks used for arranging artificial teeth. 1. The number of teeth selected 2. Anterior and posterior reference points. 3. Bucco-lingual positioning of the teeth. 4. Antero-posterior compensating curve. 5. Medio-lateral compensating curve. www.indiandentalacademy.com
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  •  Flat planes in all directions  Balance was unnecessary and undesirable. www.indiandentalacademy.com
  •  Eliminates antero-posterior and medio- lateral inclines of teeth.  Horizontal condylar guidance set at 0.  Lateral condylar guidance set at 0.  Bucco lingual width of teeth is reduced.  No of teeth is reduced. www.indiandentalacademy.com
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  •  In 1966 J. F .FRUSH described occlusion in 3 geometric terms .  One dimensional-linear occlusion  Two dimensional – flat plane  Three dimensional – cuspid.  This scheme increases stabllity. www.indiandentalacademy.com
  • • Linear ( non interceptive ) occlusion consists of following requirements 1 . Zero degree teeth are opposed by bladed teeth 2 . Mandibular teeth are set to a flat occlusal plane 3 . There is no anterior tooth interference to protrusive or lateral movement. www.indiandentalacademy.com
  •  Mandibular prosthesis stability can be analyzed with anatomic teeth , zero degree ,and linear teeth .  ANATOMIC TEETH www.indiandentalacademy.com
  •  ZERO DEGREE TEETH WITH MONOPLANE OCCLUSAL SCHEME. www.indiandentalacademy.com
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  •  Prosthodontic treatment for edentulous patients— Boucher’s 9th edi.  Essentials of complete denture prosthodontics— Sheldon winklers 2nd edi  Text book of complete dentures– Rahn & Heartwell 5th edi  Complete denture occlusion-D C N A .2004 ;641-665  Maximising mandibular prosthesis stability utilising linear occlusion, occlusal plane selection and centric recording ( JPD 2004;13;55-61)  A randamised clinical trial comparing anatomic, lingualised ,and zero-degree posterior occlusal forms for complete dentures.( JPD 2007;97;292-8)  History of articulators;a critical history of articulators based on geometric theories of mandibular movement;part 1(JP,JUNE 2002 ;134-146 ) www.indiandentalacademy.com
  • www.indiandentalacademy.com For more details please visit www.indiandentalacademy.com