It is defined as “Any relation of themandible to the maxilla” Types: 1. Orientation jaw relation2. Vertical jaw relation3. Horizontal jaw relation
Competition• The competitivelandscape– Provide an overviewof productcompetitors, theirstrengths andweaknesses– Position eachcompetitor’s productagainst new productA BCDPerformancePriceClassification of the jawrelation :Orientationjaw relationArbitraryActualVerticaljaw relationAtrestAtocclusalHorizontaljaw relationCentricEccentric
Competition• The competitivelandscape– Provide an overviewof productcompetitors, theirstrengths andweaknesses– Position eachcompetitor’s productagainst new productA BCDPerformancePriceTo orient tolocate.The position of the maxilla ormandible in the skull is recordedusing an instrument called theface bow.Face bow is mainly used mainlywhen the vertical dimension ofocclusion is expected to bealtered.Use of facebow minimizesORIENTATION JAW RELATION :
U shaped Caliper like instrument used to recordthe relationship of the maxillary arch to someanatomic reference point or points and thentransfer this relationship to an articulator.
They simulate teeth and help inestablishing vertical dimension andcentric relation Record bases should be retentive› For making phonetics test and for accuratejaw relation record If slightly loose, denture adhesive can beused If pronounced looseness… finalimpression has to be remade
Poor adapatation of resin to cast Over or under extension of borders Excessive blockout for undercuts whilefabricating record base
Maxillary occlusal rim anterior height 22mm Mandibular occlusal rim anterior height18mm Maxillary rim slightly facial to ridge tocompensate for residual ridge resorptionn to support upper lip Posteriorly the mandibular occlusal rim iskept upto 2/3rd of retromolar pad.
Properly contoured maxillaryocclusal rim is inserted in thepatient’s mouth and following areassessed› Lip support: Upper lip should justsupported enough.› Visibility of the rim: at rest 0.5 – 1.0 mmof the rim should be visible Touches wet line of lower lip whenpt says F or V sounds› Ask patient to from Count 50 -60 Lips relaxed Naso labial angle should be at 90degree Philtrum should be depressedslightly, There should be noobliteration or streching of philtrum
Anteriorly the maxillaryocclusal plane isadjusted to be parallelto interpupillary line. Done using fox plane
Posteriorly the occlusal plane is adjusted to beparallel to alae-tragus line(camper’s plane)Camper’s plane: Imaginary line joining the alaeof the nose to the tip of the tragus
For mandibular occlusal rim› Anteriorly the occlusal plane should be atthe corner of the mouth› Posteriorly the occlusal rim should be at thejunction of anterior 2/3rd and posterior 1/3rdof the retromolar pad.
The Vertical Jaw Relations are expressedas the amount of separation of themaxilla & mandible under specifiedconditions. The Vertical Jaw Relations can berecorded in 2 positions:-1) The vertical dimension at rest position2) The vertical dimension at occlusion.
Correct recording, transferring & incorporatingthe vertical relations in the prosthesis, determinesthe success of the prosthesis. Failure to do somay compromise the success of the prosthesis. Effects of excessively increasing the verticaldimension:-1) Discomfort – teeth come into contact soonerthan expected.2) Trauma – caused by constant pressure on themucous membrane.3) Loss of freeway space
4) Clicking of teeth – teeth are raised & theopposing cusps frequently meet eachotherduring speech & mastication.5) Appearance – over opening may causeelongation of the face & at rest the lipsare parted.
Effect of excessively decreasing the vertical dimension:-1) Inefficiency – the force exerted with the teeth incontact decreases considerably withover closure.2) Cheek biting – the flabby cheek tend to becometrapped between the teeth & bittenduring mastication.3) Appearance – Closer approximation of nose tochin, soft tissue sag & fall in, & thelines on the face are deepened.4) Soreness at the corner of the mouth (Angular cheilitis) –falling in of the corner of the mouth beyond the vermilionborder & the deep fold thus formed become bathed insaliva. This area becomes infected & sore.5) Pain in TMJ – caused due to strain of the joint &associated ligaments.
The distance between two selected pointsmeasured when the mandible is in thephysiologic rest position. The vertical dimension of rest is a measurabledistance, a repeatable reference within anacceptable range & a useful reference whenestablishing the vertical dimension ofocclusion.(VDO)
Factors to be considered for rest position as a reference are:-1) The position of the mandible is influenced by gravity, so,mandibular positions are postural.2) Rest position is a relaxed position of the mandible.3) Rest position is a position in space, which cannot be maintainedfor definite periods of time.4) Space between the teeth is essential when the mandible is atrest.
Mark two points … One at tip of nose and one at tip ofchin. Make patient sit upright comfortableposition in dental chair with headunsupported. Patient is to asked swallow and relaxand drop his shoulders. Once dentist is sure that patientrelaxed, the distance between twopoints are measured. Thismeasurement is for vertical at rest. Usually 2 or 3 readings are taken… theaverage is taken as reading. Thisprevents error during takingmeasurements.
now.. The mandibular occlusal rim isinserted and patient is asked to bite onthe rims. With patient in this occluding position,readings at same two points markedearlier is made. This measurement is vertical at occlusion. Usually the VDO should be 2-4 mm lessthan VDR.
The difference between the occlusal vertical dimension& the rest vertical dimension is the INTEROCCLUSALDISTANCE referred to as the “FREEWAY SPACE.”VD at occlusion = VD at rest - Freeway Space.VDO is the distancemeasured betweentwo points when theoccluding membersare in contact.
- Interocclusal Distance(free way space):- isthe distance or gap existing between theupper & lower teeth when the mandible is inthe physiological rest position. It is usually 2-4mm when observed in the 1st premolarregion. If the interocclusalspace is greater then4mm, the occlusalvertical dimensionmay be consideredtoo small.If less then 2mm,the dimension isconsidered to be toogreat.
Seat the patient in a comfortable upright positionunsupported by a head rest. Mark a small dot on on thenose and the chin to serve as reference points. Ask thepatient to swallow and relax the jaw several times. Use a tongue depressor blade to record the distancebetween the reference points when the patients jaws are inthe physiologic rest position. This measurement is thevertical relation of rest (VDR) on the tongue blade. It shouldbe relatively constant after several repetitions. Only maxillary record base and occlusion rim inserted toprovide lip support. Mark the tongue depressor blade 2-3 mm short of thevertical relation of rest. This is the vertical relation ofocclusion (VDO) for most patients. The mandibular record base and occlusion rim is adjustedby trimming the wax rim with a heated spatula or knife. Replace the mandibular record base in the mouth andverify using the tongue blade that you have established thevertical dimension of occlusion you desire.
The rest position of the mandible affects the harmony ofthe facial muscles. An experienced clinician can use thisas a further check of the vertical relations. If the mandibleis over closed, the lips and the mandible appearprotruded. If the mandible is held open from the restposition, a strained appearance can be evident when thelips are brought into contact. Observe your patient in theestablished rest position. He or she should appear neitherstrained nor suffer a loss of vertical face height. Ask thepatient to swallow and see if he or she appears to strain tobring the teeth into contact while swallowing.
Speech movements can also be used to verify thevertical relations. The wax occlusal rims must contactevenly prior to evaluating the vertical relation ofocclusion. The vertical relation of occlusion should nowbe verified using phonetics.1. Place both maxillary and mandibular record bases inthe patients mouth. Ask the patient to wet the upperlip with the tip of the tongue.2. Ask the patient to say words with "S" sounds, such as77 ,Sunset Strip, 66, count from 1-10, or from 60-70.
Observe from the profile and frontal view that there is 1-2mm of clearance between the incisal edges of theocclusion rims in the midline when the patient repeats thewords containing "S" sounds. The space that exists whenthese words are said is called the closest speaking space. If there is a space of 1-2 mm between the incisal edges ofthe maxillary and mandibular occlusal rims in the midlinewhen the patient says an "S" sound, there should beadequate interocclusal distance. If the occlusion rims contact when these words are said,then wax on the mandibular occlusion rim should beremoved until this clearance is obtained. When you are satisfied that the vertical relation of occlusalyou have established is correct for your patient and yourocclusion rims occlude evenly anteriorly and posteriorly,you are ready to record centric relation.
1) Pre-extraction Records:-a) Profile Photographs:-- Profile photographs are made & enlarged to a life sizeof the patient.- Measurements of anatomic landmarks on thephotographs are compared with measurements usingthe same anatomic landmarks on the patients face.-These measurements can be compared when therecords are made & again when the artificial teeth aretried in.- The photographs should be made with the teeth inmaximum occlusion, as this position can be maintainedaccurately for photographic purposes.
b) Profile Silhouettes:-- The word silhouette means “outline.”- Any further information like name, address,date, colour & shape of the teeth can beentered on the template & kept for futurereference.
GPT 4,The jaw relation when the condyles are in the most posterior,unstrained position in the glenoid fossa at any given degree ofjaw separation from which the lateral movements can be made. BOUCHERThe most posterior relation of the lower to the upper jaw fromwhich lateral movements can be made at a given verticaldimension .
Centric relation is a reproducible and stableand comfortable position.Therefore it isused as a reference when mountingdentulous and edentulous casts inarticulator.Thus CR serves as a referencerelationship for establishing an occlusion. When CR and CO of artificial teeth do notcoincide the stability of denture bases is injeopardy and patient will have unnecessarypain or discomfort.
There are two aspects :1.Assisting the patient to retrude themandible2.Recording.
Effective manipulation of mandible requires delicacy and firmness.METHODS FOR ASSISTING THE PATIENT TO RETRUDE THE MANDIBLE. Relaxing the jaw and closing Repeatedly protruding and retruding the mandible Swallowing and closing Tapping the rims or back teeth repeatedly Touching the tip of the tongue to the posterior aspect of thepalate or denture border and bite. Palpate the temporal and massater muscles to relax them.
Max & MandOccusion Rims› Two sharp “V”-shaped notches inthe molar/premolararea of each sidedwax› Depth 1-2 mm1-2mm
› Place Alluwax into a 1-2mm slot in maxillary rim› Fill to slight excess› Ensure wax is dead soft› Hot water bath forsoftening
› Rehearse making therecord withoutrecording medium› Place occlusion rimsintraorally› Have patient closeinto record› Ensure smooth arcof closure, nohorizontaldeviations› Use index fingers tostabilize lowerrecord base
The sealed occlusal rimsare removed from thepatient’s mouth. The record should bereverified if there isdoubt in its accuracy. Using this record themaxillary andmandibular casts aremounted on articulator. Next step is arrangementof teeth in thelaboratory.