Slide 1:Good morning


BALANCED OCCLUSION :BALANCED OCCLUSION


Slide 3:INTRODUCTION DIFF B/W NATURAL&ARTIFICIAL DENTITION TERMINOLOGY CHARACTERISTIC REQUIREMENTS OF BALANCED OCCLUSION GENERAL CONSIDERATIONS FOR BALANCED OCCLUSION ADVANTAGES OF BILATERALBALANCED OCCLUSION TYPES OF BALANCED OCCLUSION CONCEPTS PROPOSED TO ATTAIN BALANCED OCLUSION FACTORS INFLUENCING BALANCED OCCLUSION


Slide 4:FACTORS OF LATERAL BALANCED OCCLUSION FACTORS OF PROTRUSIVE BALANCED OCCLUSION TEETH USED TO ATTAIN BALANCED OCCLUSION SETTING TEETH TO ATTAIN BALANCING OCCLUSION BALANCING AND WORKING SIDE INTERFERECES/CONTACTS SELECTIVE GRINDING PROCEDURES


INTRODUCTION :INTRODUCTION All dentures move in function& prime aims in construction of complete dentures to ensure that this movement is reduced to the minimum Everytime opposing teeth contact there is a resultant force. Although this force may vary in magnitude and direction, it must always be always be resisted by supporting tissues.


Slide 6:When forces act on a body in such a way that no motion results there is BALANCE or equilibrium. Stable denture is ultimate goal


Natural vs Artificial dentition :Natural vs Artificial dentition


TERMINOLOGY :TERMINOLOGY OCCLUSION: static relationship b/w incising or masticating surfaces of maxillary or mandibular teeth or tooth analogues ARTICULATION: contact relationship b/w occlusal surfaces of teeth during function CENTRIC OCLUSION: occlusion of opposing teeth when mandible is in centric relation -May r may not coincide with maximum intercuspation


Slide 10:MAXIMUM INTERCUSPATION: complete intercuspation of opposing teeth independent of condylar position EXCURSIVE MOVEMENT: movement occuring when mandible moves away from maximum intercuspation ECCENTRIC: any position of mandible other than that which is its normal position ECCENTRIC OCCLUSION: any occlusion other than centric occlusion


Slide 11:BALANCING SIDE/NON-WORKING SIDE: That side of mandible which moves towards median line in lateral excursion BALANCING INTERFERENCES: undesirable contacts of opposing occlusal surfaces on non working side BALANCED OCCLUSION: Bilateral, simultaneous, anterior & posterior occlusal contacts of teeth in centric, eccentric positions


REQUIREMENTS OF COMPLETE DENTURE OCCLUSION :REQUIREMENTS OF COMPLETE DENTURE OCCLUSION Stability of denture &its occlusion when mandible is in both centric, eccentric relations Bilateral occlusal contacts for eccentric contacts Unlocking cusps mesio-distally to accommodate for gradual settling of denture base Control of horizontal forces by b/l cusp height reduction according to residual ridge resistance form, Interarch distance


Slide 13:Functional lever balance by favourable tooth to ridge crest position Cutting and shearing efficiency of occlusal surface Anterior incisal clearance during posterior masticatory function Minimal area of contact to reduce pressure while crushing food Sharp ridges. cusps, sluice ways to increase masticating efficiency


CHARACTERISTIC REQUIREMENTS OF BALANCED OCCLUSION :CHARACTERISTIC REQUIREMENTS OF BALANCED OCCLUSION All the teeth of working side should glide evenly against opposing teeth No single tooth should produce any interference or disocclusion of other teeth There should be contacts in balancing side bu they shouldn’t interfere with smooth gliding movements of working side There should be simultaneous contact during protrusion


GENERAL CONSIDERATIONS FOR BALANCED OCCLUSION :GENERAL CONSIDERATIONS FOR BALANCED OCCLUSION Ideal balanced occlusion achieved with wider& larger ridges, teeth arranged close to ridge Wider ridge & narrower teeth bucco lingually greater is balance More lingual - teeth are positioned i.r.t crest –greater the balance More centered force of occlusion anteroposteriorly –greater stability of base


ADVANTAGES OF BALANCED OCCLUSION :ADVANTAGES OF BALANCED OCCLUSION SWALLOWING- Bilateral balance allows contacts occuring during swallowing to be made evenly wihout displacing base against oral mucosa CHEWING- helps to seat denture in stable position during terminal arc of closure


Slide 17:PARAFUNCTIONAL MOVEMENTS: Balanced occlusion prevents destructive lateral forces generated against basal seat during parafunctional activity CHRISTENSEN PHENOMENON: if dentures are not balanced in protrusive excursion, resulting posterior disocclusion & pressure in premolar area causes dislodgement


TYPES OF BALANCED OCCLUSION :TYPES OF BALANCED OCCLUSION UNILATERAL OCCLUSAL BALANCE : type of occlusion seen when occlusal surfaces of teeth on one side articulate simultaneously, as a group, with smooth, uninterrupted glide -More pertained to fixed dental prosthesis BILATERAL OCCLUSAL BALANCE: Equilibrium on both sides of denture due to simultaneous contact of teeth in centric, eccentric postions


Slide 19:Requires minimum of 3 contatcs for establishing plane of equilibrium It could be protrusive r lateral balance PROTRUSIVE OCCLUSAL BALANCE: This type is present when mandible moves forward& Occlusal contacts are smooth, simultaneous in posterior, anterior regions(right,left sides) -requires minimum of 3 contacts- 1 on each side,1 anteriorly. -absent in natural dentition


CONCEPTS PROPOSED TO ATTAIN BALANCED OCCLUSION :CONCEPTS PROPOSED TO ATTAIN BALANCED OCCLUSION GYSI CONCEPT- 1914- pioneered concept of balanced occlusion -introduced 33°anatomic teeth FRENCH CONCEPT-1954- proposed lowering the lower occlusal plane to increase stability of dentures along with balanced occlusion -used modified french teeth to obtain balanced occlusion


Slide 21:SEARS CONCEPT proposed balanced occlusion for non anatomical teeth using posterior balancing ramps PLEASURE CONCEPT- introduced pleasure curve or posterior reverse curve to align and arrange posterior teeth to increase stability of dentures FRUSH CONCEPT-advised arranging teeth in one dimensional contact relationship, should be reshaped during try in to obtain balanced occlusion


HANAU’S LAWS OF ARTICULATION :HANAU’S LAWS OF ARTICULATION -RUDOLPH.L.HANAU- ENGINEER -Proposed nine factors that govern the articulation of artificial teeth-laws of balanced articulation 1.Horizontal condylar inclination 2.Compensating curve 3.Protrusive incisal guidance


Slide 23:4.Plane of orientation 5.Buccolingual inclination of tooth axis 6.Sagittal condylar pathway 7.Sagittal incisal guidance 8.Tooth alignment 9.Relative cusp height


HANAU’S QUINT :HANAU’S QUINT Condylar guidance Incisal guidance Compensating curves Relative cusp height Plane of orientation


TRAPOZZANO CONCEPT :TRAPOZZANO CONCEPT According him –only 3factors necessary for determining plane of occlusion -Triad of occlusion 1.Condylar guidance 2.Incisal guidance 3.Cuspal angle -HE STATED OCCLUSAL PLANE COULD BE LOCATED AT VARIOUS HEIGHTS TO FAVOUR WEAKER RIDGE -HE ALSO STATED THAT BY ARRANGING CUSPED TEETH-THESE CURVES ARE PRODUCED AUTOMATICALLY


BOUCHER’S CONCEPT :BOUCHER’S CONCEPT -Recommended occlusal plane “be oriented exactly as it was when natural teeth are present” -Need for compensating curve as stated “the value of compensating curve is that it permits an alteration in cusp height without changing morphology of teeth”


Slide 29:Boucher’s concept is that 1. There are 3 fixed factors -orientation of occlusal plane -incisal guidance -condylar guidance 2. Angulation of cusp is more important than height of cusp 3.Compensating curve enables one to increase effective height of cusps without changing form of teeth


LOTT CONCEPT :LOTT CONCEPT Explained HANAU work by relating laws of occlusion to posterior separation


LEVIN CONCEPT :LEVIN CONCEPT Similar to lott’s concept He stated need for compensating curve & occlusal plane should be included only in its correct anatomic position Plane of orientation is fixed factor& it can be altered by 1-2 mm to improve stability for poor ridge Guiding factors produce posterior separation which must prevented by controlling factors Named four factors-QUAD


FACTORS AFFECTING BALANCED OCCLUSION :FACTORS AFFECTING BALANCED OCCLUSION According to HANAU Inclination of condylar guidance Prominence of compensating curve Inclination of Plane of orientation Inclination of incisal guidance Height of cusps


Slide 34:Restated as Inclination of condylar guidance end controlling Inclination of incisal guidance factors Orientation of occlusal plane Inclination of cusps Prominence of compensating curves


CONDYLAR GUIDANCE :CONDYLAR GUIDANCE Mandibular guidance generated by condyle and articular disc traversing contour of glenoid fossa Mechanical form located in upper posterior region of an articulator that controls movement of its mobile member {GPT-8}


Slide 36:Condylar guidance is due to path followed by condyle in temperomandibular joint


Slide 37:HANAU states that inclination of condylar guidance is definite anatomical conception Some dentists believe that path is precise& constant and that it guides mandible so precisely that it is primary dictator of occlusion one investigation showed tracings made on hinge axis as a common starting point to have same condylar path


Slide 38:KURTH claims that condylar path is not same for varying incisal guidances WEINBERG showed that condylar path vary owing to variable pressures of function PAYNE showed that mandible can move to follow steep cusps,modified cusps&teeth with no cusps when there is posterior occlusal harmony&no anterior interference


Slide 39:The degree of condylar inclination registered results from shape and bony contour of TMJ


Slide 40:Limitation of movements effected by attached ligaments Muscles attached to mandible The method used to record this factor


Slide 41:Only factor given by patient which cannnot be modified by operator Obtained by protrusive registration record


Slide 42:Increase in condylar guidance will increase jaw separation during protrusion As this factor cannot be modified, all other 4 factors should be modified to compensate effects of this factor In pts with steep condylar guidance, incisal guidance should be decreased to reduce amount of jaw separation produced during protrusion


INCLINATION OF INCISAL GUIDANCE :INCLINATION OF INCISAL GUIDANCE Influence of contacting surfaces of mandibular & maxillary anterior teeth on mandibular movements Influence of contacting surfaces of guide pin and guide table on articulator movements {GPT-8}


Slide 44:INCISAL GUIDE ANGLE: angle formed by intersection of plane of occlusion and line with in sagittal plane determined by incisal edges of maxillary& mandibular central incisors when teeth are in maximum intercuspation On articulator-Angle formed in sagittal plane, b/w plane of reference& slope of anterior guide table


Slide 45:Angle of incisal guidance is largely under influence of dentist But there are certain limitations like Ridge relation Arch shape Ridge fullness Inter ridge space Phonetics &esthetics requirement of patient With in range of these limitations incisal guide angle can be altered considerably


Slide 46:This factor is influenced by amount of horizontal, vertical overlap Greater horizontaloverlap=lesser angle of inclination Lesser the verticaloverlap=lesser angle of inclination


ORIENTATION OF OCCLUSAL PLANE :ORIENTATION OF OCCLUSAL PLANE Plane of orientation-factor already been determined orient – “find proper relation or bearings of” It is factor to be determined –so more valid way of expressing idea –orientation of plane According to BOUCHER,LEVIN- it is a fixed factor By HANAU-it is vertical location of anteroposterior alignment of occlusal plane in space b/w upper,lower ridges


Slide 48:METHODS TO ESTABLISH OCCLUSAL PLANE using ala-tragus line using cephalometric method Using cephalometric method-cephalometrically a relationship is shown to exist b/w angle of occlusal plane relative to frankfort horizontal plane on one hand,and angle formed b/w cephalometric points, porion,nasion,ANS angle(PoNANS angle) Once cephalogram is obtained,tracings are made, points identified,occlusal plane computed by formula Y=83.4307-(0.9907-X) (X=PoNANS angle )


Slide 49:HANAU states plane of orientation is purely geometrical factor-plane assumed to pass thru 3 dental landmarks, namely, central incisal point& summits of mesiobuccal cusps of molars. Hanau uses this plane for signifying general direction of masticatory surfaces in denture space available and for characterization of compensating curve.


Slide 50:Once plane is selected –this plane makes mandibular measurements facile and gives them a definite comparitive value,as soon as we mount central incisal contact point of each case at same distance from articulator base. UnFortunately,in not all cases can mounting be carried out at level indicated by HANAU


Slide 51:frequently face bow transfer results in maxillary cast mounting extremely high or low A change of height in mounting of cast when a face bow transfer is used will not alter relation of cast to condylar inclination Actually, inclination of plane of orientation, may be established at various levels with in available interridge space, without any influence on incisal guide angle /condylar inclination but corresponding influence on cuspal angulation


Slide 52:According to sharry, plane of orientation established intially can be altered subsequently to serve purposes Its existence is temporary as it is lost in establishing compensating curves


Slide 53:According toBOUCHER, locating occlusal plane high/low to favour weaker of two ridges can cause both esthetic, mechanical trouble If soft tissues surrounding dentures are to work around them as they did around natural teeth,occlusal plane should be oriented exactly as it was when natural teeth are present


Slide 54:By positioning anterior teeth correctly for esthetic appearance and locating posterior end of occlusal plane appx level with top of retromolar pad-factor of orientation of occlusal plane is fixed Any necessary alterations for balancing occlusion must be made on other factors


INCLINATION OF CUSPS OF TEETH :INCLINATION OF CUSPS OF TEETH CUSP ANGLE: angle made by average slope of cusp with cusp plane measured mesiodistally or bucco lingually


Slide 56:CUSP PLANE: plane determined by two buccal cusp tips and highest lingual cusp of a molar EFFECTIVE CUSP ANGLE: angle formed by average cusp slope and horizontal reference plane


Slide 57:INCLINATION OF CUSPS-refers to angle between Total occlusal surface of tooth and inclination of cusp i.r.t that surface Cuspal inclination can be made steeper when distal end of lower tooth is set higher than mesial end Cuspal inclination can be lowered if distal end is set lower than mesial end Similar adjustments can be made in buccal,lingual cusps


Slide 58:To obtain balanced occlusion, cuspal angles must be set such that they are parallel to path of mandible


Slide 59:Tilting teeth i.e by correcting cuspal angles- effective cuspal angle can produce compensating curve –resulting in balanced occlusion


COMPENSATING CURVES :COMPENSATING CURVES Arc introduced in construction of complete dentures to compensate for opening influences produced by condylar and incisal guidances during lateral and protrusive mandibular excursive movements or Anteroposterior curving(median plane)and mediolateral curving(in frontal plane)with in alignment of occluding surfaces and incisal edges of artificial teeth that is used to develop balanced occlusion (GPT-8)


Slide 61:determined by inclination of posterior teeth and their vertical relationship with occlusal plane Compensating curve should be in harmony with movements of mandible Curves of natural dentition -curve of spee - curve of wilson -curve of monson -Pleasure curve(in excess wear of teeth) Curvatures in artificial dentition -anteroposterior curve -mediolateral curve


Slide 62:Steep condylar path requires steep compensating curve to produce balanced occlusion Valuable factor as it allows dentist to alter cusp height without changing morphology of manufactured teeth Cusps can be made longer or shorter by inclining long axes of teeth to conform to end guidances If teeth themselves donot have any cusps,the compensating curve can be used to produce equivalent of cusps


Slide 63:Inorder to obtain smooth, balanced occlusion, compensating curve should be in harmony with other factors Explained by THIELMANS FORMULA K .I -------------- op .C. ok K-inclination of condylar guidance I-inclination of incisla guidance C-height of cusps op-inclination of plane of orientation ok-prominence of compensating curve


Slide 64:CURVE OF SPEE: -FERDINAND GRAF SPEE-GERMAN ANATOMIST -refers to anteroposterior curvature of occlusal surfaces, beginning at tip of lower canine and following buccal cusp tips of bicuspids and molars and continuing to anterior border of ramus,ending with anterior most portion of mandibular condyle Compensating curve for curve of spee in artificial dentition is anteroposterior curve Posterior teeth set on this curve will continue to remain in contact during protrusion


Slide 66:CURVE OF WILSON: -GEORGE.H.WILSON -eponym for mediolateral curve -contacts buccal and lingual cusp tips of molars on each side of arch In mandibular arch -results from inward inclination of lower posterior teeth-making lingual cusps lower than buccal cusps –curve being concave In maxillary arch-results from outward inclination of posterior teeth-making buccal cusp higher than lingual cusps-curve being convex Teeth set on this curve will have lateral balance of occlusion


Slide 68:CURVE OF MONSON: -GEORGE .S.MONSON - eponym for proposed ideal curve of occlusion in which each cusp and incisal edge touches or conforms to segment of surface of sphere 8 inches in diameter with its center in region of glabella. CURVE OF PLEASURE: -MAX.A.PLEASURE -Helicoidal curve of occlusion when viewed in frontal plane, conforms to a curve that is convex from superior view, except for last molars. -associated with reversal of occlusal plane of premolars, first and second molars, occlusal surfaces of lower teeth slope facially and maxillary teeth incline lingually


Slide 70:Thank you