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DEFINITION ~Occlusion is each static contact between one or more lower teeth iwht one or more upper teeth ~Functional occlusion refers to the occlusal contacts of the maxillary and mandibular teeth during function, i.e. during speech, mastication and swallowing www.indiandentalacademy.com
~Intercuspal position is the occlusal with the teeth in maximum intercuspation ~Retruded axis position is the position the condyle adopts during the terminal hinge movement of openeing or closing ~Retruded contact position is the occlusal position when the first tooth contact occurs on the mandibular path of closure with the condyles in the retruded axis position
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~Working side is the side that the mandible moves towards in a lateral excursion ~Non-working side is the side that the mandible moves away from during a lateral excursion
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OCCLUSAL CONCEPTS ~Angle ~Raymond Begg ~Andrews ~Other modifications
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RONALD H. ROTH ~Stability of the treated case ~Benefit to the patient ~Functioning occlusion after bicuspid ext.
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ROLE OF EQUILIBRATION ~Tooth positioning close to centric ~Criteria starts from diagnosis, Rx planning Rx and retention ~Difficulty in occlusal adjustment ~Equilibration after growth is complete
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PHILISOPHY & RATIONALE ~Treatment objectives - Pleasing facial esthetics evaluated cephalometrically & by soft tissue -Molar relationship & tooth alignment-Angle -Functional occlusion-gnathologic articulator -Comfort, efficiency and longevity of dentition, supporting structures and TMJ www.indiandentalacademy.com
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~Lower jaw up in the socket-ideal physiological position ~Closure, no forward or backward movt. But only teeth should mesh ~Teeth should not interfere ~Harmony of occlusion
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The mandible should be able to close into maximum intercuspation without deflecting the condyles from their most ideal relationship in the fossae.
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HARMONY OF OCCLUSION ~Defining Ideal relationship of condyle in fossae ~Degree of accuracy in recording the full extent of jaw movement ~Type of centric contacts & type of Excursive occlusal scheme ~Instrumentation www.indiandentalacademy.com
~Centric relation of mandible & centric occlusion of teeth-identical ~Alleviation of pain ~Orthodontist & Restorative dentist Arranging the teeth in harmony with condylar guidance and adjust occlusal plane in relation to angle of eminence
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NEUROPHYSIOLOGY OF PAIN
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CENTRIC RELATION ~An idealized treatment goal ~CR of the mandible is a superior limit position of the condyles in the fossae with the mandible centered and its most closed position
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~The fact that someone’s occlusion is not centrically related is not by itself an indication for treatment ~There are some patients who are not comfortable in centric , such patients will not be comfortable anywhere
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~CR contrary to popular opinion is not a strained position. It is only a strained position if attempts are made to forcibly retrude the mandible and make the teeth contact where they do not intercusp When the teeth fit together with the mandible seated properly in centric relation there is no strain
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~Williamson-Superior-anterior fossa position ~Stuart-Rearmost, midmost & uppermost position of condyles in their respective fossae with the mandible in the closed position
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~Agrees with Dyer & Dawson-when one is dealing with a patient who has damage to the TM ligaments and has excess mobility of the condyles, it is virtually impossible to push the mandible distally without causing further inferior positioning or subluxation of condyles, unless care is taken to support the gonial angles and even than it is doubtful that subluxation could be avoided without prior use of repositioning splint to obtain a stable centric relation www.indiandentalacademy.com
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RECOGNIZING OCCLUSAL DISHARMONY ~Occlusal wear ~Excessive tooth mobility ~TMJ sounds ~Limitation of opening or movement ~Myofacial pain ~Contracture of mandibular musculature making manipulation difficult ~Some types of tongue thrust swallow
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~Patients do not adapt to occlusal interferences, they tolerate them, but the tolerance becomes less as they grow older ~Tolerance level > Symptomatic ~Occlusal disharmonies should be treated prior to orthodontic treatment
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~Occlusal interferences-classify 1.Those with symptomatology 2.Pschycologically or physically predisposed to developing a problem 3.Those that are neither symptomatic nor predisposed to developing symptoms
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OCCLUSAL INTEREFERENCES TEND TO MAKE TEETH AND JAWS A FOCUS FOR VENTING PSYCHOLOGICAL STRESS
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EXAMINATION ~THIS IS A SKILL THAT MUST BE LEARNED
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~If the mandible is easy to manipulate, then what can be seen clinically is usually a fair representation of actual discrepancy ~Large disc.-Whip Mix articulator ~If the mandible is difficult to manipulate and there is no centric prematurity and resistance encountered , this requires splint therapy to free the musculature
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~TMJ should be palpated for popping or grating sounds, tenderness. ~Splint therapy & TMJ tomograms are indicated prior to ortho. Rx ~Occlusion checked for wear facets and look for contact areas ~Ricketts VTO
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~Right & Left lateral excursions & protrusive movements (interferences cannot be diagnosed intra-orally but can be done in articulator) ~The maximum opening should be notedindicator of state of contracture of the mandibular musculature – 45-50 mm
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MPI
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NEUROMUSCULAR CONTROL
TMJ
TEETH www.indiandentalacademy.com
DIAGNOSIS & TREATMENT PLANNING ~Symptomatology
splint therapy
~Intra-oral examination & Articulator simulation ~Neuromuscular adaptations
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~Records should be as close as possible to centric relation ~Standard ortho. Models & cephalometric headfilms have been traditionally taken in habitual centric occlusion ~If significant discrepancy exists, records should be taken in centric relation to evaluate the extent of discrepancy www.indiandentalacademy.com
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~In diagnosis & Rx Planning, it is necessary to diagnose the case from a mandibular position of centric relation, if you wish to treat to centric relation occlusion ~The jaw relationship is corrected in all three planes of space ~Buccolingual co-ordination of basal arches and A-P adjustment so that there is no horizontal overjet and there must be sufficient closure of mandible to provide a vertical overbite www.indiandentalacademy.com
TRIPODISATION
OCCLUSAL CONTACT B-L STABILITY www.indiandentalacademy.com
~A true centric can never be captured on the first clinical attempt ~True centric can be stabilized if there is no degenerative joint changes in a non-growing patient ~The cephalometric tomogram of the TMJ is a good indicator of the state of the bony elements of the joints
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~Relief of symptoms alone is not the major purpose of the splint ~To seat the condyle in the most superior position and maintain a closed vertical dimension ~An anterior ramp is created to disclude the posterior teeth ~The cuspids should be the main guiding inclines in lateral movements www.indiandentalacademy.com
~The mandibular postural changes during splint therapy is of three types changes due to relaxation of musculature that postures the mandible incorrectly due to muscle contracture or spasms changes due to elimination of intracapsular inflammatory fluid changes due to remodeling or recontouring of the bony parts of the joints
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~Splint therapy is continued until there has been no change in mandibular positioning in centric relation for atleast three months ~If symptoms are not releived / stability not attained, Rx is stopped ~It is wise to institute splint therapy prior to orthodontic Rx and stabilize the mandibular Position for three months on any symptomatic case
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REPOSITIONING SPLINT www.indiandentalacademy.com
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.0005” SHIMSTOCK CLEARANCE
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GNATHOLOGY
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~The term gnathology denotes the science that deals with the biology of the masticatory system ~It referred to the science dedicated to the study of oral cavity as a functional unity in direct relationship to its morphology, histology, physiology and therapy, including its vital relations with the rest of the body ~Occlusion, Jose dos Santos www.indiandentalacademy.com
FINISHING TO GNATHOLOGICAL PRINCIPLES ~Visualisation of Mandibular body excursions Tooth relationships during excursions The effect of characteristic of the border movement pattern on the ooclusal morphology Mandibular movement Articulator movement www.indiandentalacademy.com
~We should not simply believe what we see in mouth ~Pt. will bite where their teeth fit ~Pt. will move their mandible to avoid noxious contact of teeth ~Muscles will contract to avoid inflicting self injury to joints, teeth, supporting structures.
ALL THESE DENOTE THE NEUROMUSCULAR ADAPTATION www.indiandentalacademy.com
GNATHOLOGICAL OBJECTIVES I~CR and maximum intercuspation in that position (No contact of anterior teeth) II~Harmonious glide path of anterior teeth working against each other to separate or disclude the posterior teeth immediately
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~The cuspids should be the main gliding inclines on lateral excursion and the six anterior teeth should articulate with the six mandibular anterior teeth and the mandibular bicuspids ~Mutually protective occlusal scheme
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Good occlusions, if to be preserved, must also have disocclusions (disclusions), otherwise excessive contacts of the tooth surfaces would result in abrasions and wear of their parts. Disclusion, as defined by Dr. Harvey Stallard, "is a separation of the teeth from occlusion; the opposite of occlusion".
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CUSP-FOSSA
STAMP,SHEAR CUSPS www.indiandentalacademy.com
CUSP-EMBRASURE www.indiandentalacademy.com
DYNAMIC SPIRAL
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HORIZONTAL DISCREPANCY
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VERTICAL DICREPANCY FROM CENTRIC
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~1979, JCO -Mchorris
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EXCURSIVE OCCLUSAL SCHEME
~The gentle lateral and protrusive lift is necessary for both mandibular movement and post-treatment stability of tooth positions
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CLASS I vs CUSP-FOSSA OCCLUSION ~There are enough number of cusp-fossa relationship to hold centric in Class I ~The lower buccal cusp tips rest only on one opposing marginal ridge
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THE IDEAL AND THE POSSIBLE ~Ideally centric relation and habitual centric occlusion should be coincidental, maximum intercuspation of teeth should occur in centric relation which is less than 1% ~Treat the orthodontic case where there is no discernible discrepancy between CR and CO
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IDEAL TOOTH POSITIONING ~A centrically related occlusion and a mutually protecttive occlusal scheme are dependent upon 1.Proper individual tooth positioning 2.Knowing when the mandible is in centric and when it is not 3.Co-ordination of arch form and width www.indiandentalacademy.com
4.Control of vertical dimension 5.A-P correction between mandible and maxilla 6.Clinical awareness of excursive interferences
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1.+1 to A-Po 2.Upper incisors tip- 2-2.5 mm below the lip embrasure 3.No more than 1mm gingival show 4.2.5 mm overjet 5.Level occlusal plane that will return to 1-1.5 mm curve www.indiandentalacademy.com
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6.Curve of Wilson allowing seating of centric cusps 7.As much as divergence from occlusal plane from angle of eminence for excursive clearance 8.Lower incisors point-point contact with roots in same plane, Ma incl.-2 degrees 9.Lower cuspids – 5 degrees mesial angulation with incisal tip 1mm higher than laterals, exa. Mesial rotation in extraction www.indiandentalacademy.com cases
10.Lower bicuspids uprighted 1 degree from their normal mesial inclination and slight distal rotation 11.Lower molars-uprighted 1 degree from normal 2-degree mesial inclination and slight distal rotation 12.Lower buccal segment-progressive torque close to Andrews
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13.Upper molar-Andrews 14.Upper bicuspids to 0 degrees from 2 with some distal rotation in extraction case 15.Upper cuspid-11-13 deg mesial tip, contact point adjacent to lateral incisors and bicuspids for proper cuspid guidance 16.Central & lateral – 0.5mm differential, 9 & 5 deg. Mesio-axial inclination www.indiandentalacademy.com
There should be sufficient torque such that six upper anterior teeth can contact six lower anterior teeth and the upper cuspids can lift off the lower bicuspids in a protrusive excursioin 17.No rotations or spaces, buccal segements non-progressive 14 deg. Buccal root torque 18.Arch form-5 separate radii. Widest point upper arch-MB cusp Max Molars lower arch-MB cusp lower molar & first bicuspids www.indiandentalacademy.com
Settling into centric relation and ideal intercuspation is essential because 1.Tooth movement after appliance removal 2.Curve of Spee 3.Distal tip rather than mesial tip 4.Buccal segments tip & rotate mesially 5.As band space closes =loss of torque in anteriors www.indiandentalacademy.com
6.Teeth adjacent to extraction site will tend to rotate towards the extraction site 7.Tip towards extraction sites 8.Maxillary lingual cusp hanging
SIX KEYS
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Mandibular hinge axis
Stuart Pantographic recorder www.indiandentalacademy.com
CR-CO MOVEMENTS
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IDEAL FUNCTIONAL OCCLUSION
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Treatment Priorities Completing lower arch Rx before upper arch (finishing lower arch within a year) Detailing of tooth positions (individual considerations)
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~Molar Fulcrum TPA with Headgear Compensating curves in UAW Rectangular wires to control torque Short vertical elastics ~Overcorrection Held upto three months Elastics & Headgear discontinued for 2-3 weeks Braided rectangular wires Pt. seen at weekly basis www.indiandentalacademy.com
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Rt. & Left Excursions, protrusive excursions-smooth gliding movement with cuspids and anteriors in contact The glide should be smooth and slow if the cuspid guidance is correct and there are no excursive interferences
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FINISHING IN CENTRIC RELATION 1. Correct A-P jaw relationship. (Overcorrect, then hold, ther settle back.) 2. Eliminate molar fulcrum. 3. Coordinate arch widths and arch form with mandible in centric relation. 4. Buccolingual axial inclination of posterior teeth. Lingual crown torque of 76^67 5. Watch cuspid heights and midline or lateral deviation. 6. Level curve of Spee through second molars.
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7. Check for centric deflection. A. Prominence of lower bicuspids. B. DB cusp upper 1st molars with MB and D cusp on lower 1st molars. C. ML cusp upper 1st molars with ML cusp lower 1 st molars. 8. Marginal ridge heights. 9. Rotations
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AFTER CENTRIC IS OBTAINED Check tooth detailing (by having patient to go through test excursions — right lateral, left lateral,protrusive) for: 1. Torque of upper incisors. 2. Artistic tip of upper incisors and cuspids. 3. Overbite and overjet. 4. Flatness of curve of Spee. 5. Second molar positions. 6. Look for anterior group function, posterior clearance (minimal), cuspid guidance, and balancing interferences. www.indiandentalacademy.com
BITE REGISTRATION
GNATHO-POSITIONER
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ARTICULATED MODELS
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SAM II
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1. To treat to centric the case must be diagnosed from centric. 2. The case must be constantly monitored in centric throughout treatment. 3. The operator must have sufficient experience to be able to recognize when his patient is not in centric. 4. The operator must know how and when to use a repositioning splint to find centric. 5. Treatment mechanics should be employed that will not tend to create a centric "fulcrum" 6. The operator should have a very clearcut image in his mind of where each and every tooth belongs from a functional standpoint, and why it belongs www.indiandentalacademy.com there.
7. The operator should have an "End of Mechanotherapy Goal" from which teeth will tend to settle most favorably. 8. The orthodontist must be able to apply the excursive border movements clinically, to determine proper mandibular position and individual tooth position. 9. The use of a carefully and properly constructed gnathological positioner will aid in achieving the most ideal functional occlusion on a case that is basically treated close to centric relation occlusion with orthodontic appliances. www.indiandentalacademy.com
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The one undeniable factor that is of primary importance in any occlusal concept and functional analysis is whether or not the mandible can achieve centric relation. The greatest single error we can make in reconstructions of mouths is failure to treat to centric relation.15 Orthodontic treatment, which is a full-mouth rehabilitation utilizing natural teeth, the best that Nature has to offer, may be the hardest dentistry in the world to accomplish, but when done with respect to centric relation, and to the static as well as the moving parts of the gnathic system, is no doubt the finest dentistry in the world. www.indiandentalacademy.com
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