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Presented by :Aravind.M | IVBDS|2007 batchUnder the guidance of Dept. of prosthodontics
Any spatial relationship of themaxilla to the mandible or any one of theinfinite relationships of the mandible to themaxilla.
• Provides optimal separationbetween maxilla and mandible.• If not measured accurately, thejoint will be strained.• If the VD is altered, severediscomfort to both TMJ andmuscles of mastication.
• Tooth : Acts as a vertical stop.• Musculature : Opening and closingmuscles tend to be in a state ofminimal tonic contraction.
Two measurablelengths of the face are importantguides in making maxillo -mandibular relation records andare referred to as :• Vertical dimension of rest orphysiologic rest position. (VDR).• Vertical dimension of occlusion(VDO).
• Vertical separation of the jawswhen the opening and closingmuscles of mandible are in a stateof minimal tonic contractionsufficient only to maintain posture.
• The position assumed by themandible when the head is in anupright position, the muscles are inequilibrium in tonic contractionand the condyles are in a neutralunstrained position is thephysiologic rest position of themandible.
• Vertical separation of the jawswhen the teeth or occlusion rimsare in contact.
It is generally considered thatthe teeth should not be in contact when the jawsare at the vertical dimension of rest position. The 2to 4mm distance between the upper and lowerteeth when the mandible is at physiologic restposition is called interocclusal distance (IOD)frequently referred to as the “free way space”.
INCREASE IN VDO / DECREASE IN IOD• The chin-nose distance will increase, and thenpatients will have an appearance of openmouth.• Constant pressure to the basal seat area whichwill lead to bone resorption.• Soreness of the tissues of the basal seat.• “Clicking”, of dentures during speech.• Improper phonetics
DECREASE IN VDO / INCREASE IN IOD• Potentially damaging to the TMJ.• The normal tongue space is limited. Facialdistortion appears more noticeable with overclosure that with the slightly opened closurebecause with over closure the chin appears to becloser to the nose, the commissure of the lips turnsdown and the lips lose their fullness.• The muscles of facial expression lose their tonicityand the face appears flabby instead of firm and full.• Over closure of jaws may lead to angular chelitis
• FACIAL MEASUREMENT AFTERSWALLOWING AND RELAXING.• SPEECH• TACTILE SENSE• MEASUREMENT OF ANATOMICALLANDMARKS• FACIAL EXPRESSION.
• Patient is asked to sit upright andcomfortably, eyes looking straightahead.• Insert maxillary occlusal rim.• Place 2 points of reference.• Instruct the patient to wipe his lipswith his tongue, to swallow and todrop his shoulders – rest position.• Measure - repeat and take average.
• Instruct the patient to stand erectand open the jaws wide until strainis felt in the muscles.• When the opening becomesuncomfortable, ask him to closeslowly until the jaws reach acomfortable relaxed position.• Measure the distance and compareit.
2 methods:• 1st method :Ask the patient to repeatedlypronounce the letter ‘M’, a certainnumber of times. Distance is measuredimmediately after the patient stops.• 2nd method:keep talking to the patient andmeasure the distance immediatelyafter the patient stops talking.
• Distance between the pupil of theeye and Rima oris and the distancebetween anterior nasal spine andlower border of mandible ismeasured using Willis guide.• If both the distances are equal,jaws are considered at rest.
• Patients jaw will be in rest positionwhen he is relaxed.• Skin around the eyes and chinshould be relaxed.• Nostrils are relaxed and breathingis unobstructed.• Upper and lower lips have slightcontact in one plane.
a) Mechanical methods• Ridge relation Distance from incisive papilla to mandibularincsiors. Parallelism of ridges.• Pre-extraction records: Profile photographs Profile silhouettes Radiography Articulated casts Facial measurements• Measurement from former dentures
b)Physiological methods• Power point• Using wax occlusal rims• Physiological rest position• Aesthetics• Swallowing threshold• Tactile sense or neuromuscularperception• Patient’s perception of comfort.
Ridge relation :Defined as positional relationship ofthe mandible ridge to the maxillaryridge.a) Distance from the incisive papilla to themandibular incisors.• The distance of the papilla from theincisal edges of lower anterior teethaverages approximately 4mm in naturaldentition. The incisal edges of themaxillary central incisors are an average6mm below the incisive papilla. Basedon this value VDO can be calculated.
b) Parallelism of the ridges:• Sears suggested that correctvertical dimension of occlusion is ata point where the jaws are parallelwith a 5 degree opening in theposterior region.
Measurement of the former dentures:• A Boley’s gauge is used to measurethe distance between the border ofthe max and mand denture ,when thedentures are in occlusion.Thismeasurement is used to determinethe VDO.
Pre extraction recordsProfile radiographs :• Made with teeth in occlusion.These are compared with thosemade with occlusion rims inposition.• DISADV- Time consuming, Imagedistortion, Radiation hazard.
Profile Photographs• Taken in maximum occlusion ofteeth. The photographs should beenlarged to the actual size of thepatient. The distance between thetwo anatomic landmarks is thencompared with that of patient toavoid errors.Casts of the teeth in occlusion
Facial Measurements:Tatoo points are markedon tip of the nose and base of thechin. The vertical dimensionbetween the anatomic landmarksis then compared with that ofpatient to avoid errors. Willis gaugeis also used to measure facialdimension . One arm contacts thebase of the nose and the other armcontacts the base of the chin.
Niswonger’s method(1934) :• Two markings are made , one on theupper lip below the nasal septum, andthe other on the chin.The patient is toldto swallow and relax. The distancebetween the marks is measured. Theocclusal rims are adjusted until thedistance between the marks is 2-4 mmless during occlusion.• Disadv- The marks move with theskin.
Phonetics and esthetics.The dentist asks the pt tospeak certain words and thenmakes certain observations of therelationship of the occlusion rimsto each other and to the lips.
Using ‘m’sound:The pt repeats the letter‘m’. When the lip just touches ask thepatient to hold the jaws still. Thedistance between tip of the nose andchin is measured (VDR).The occlusionrims are adjusted and againmeasured. The second measurementshould be 2-4mm less than the firstmeasurement(VDO)
The ch,s,and j sounds:• There should be 1mm spacebetween the occlusion rims in theanterior area at correct VDO.Using 33 :• When repeating this word thereshould be enough space for the tip ofthe tongue to protrude between theanterior teeth.Using f or v sounds:• The max incisors/occlusion rimsshould lightly contact the lower lip atthe vermillion border when ptpronounces these words.
SILVERMAN’S CLOSEST SPEAKINGSPACE• The 2mm space between theincisors at correct VDO when ptpronounces words containing ‘S’eg.• The closest speaking spacemeasures vertical dimension whenthe mandible and muscles involvedare in physiologic function ofspeech.
ESTHETICSIn normal relaxed positionthe lips are even anteroposteriorlyand in slight contact. If the faceappears strained the vertical heightmay be more. If the corners of themouth droop, making the chinappear too close to the nose, thenvertical dimension may be too less.
Swallowing threshold.The technique is based onthe fact that when a personswallows, the teeth come togetherwith a very light contact at thebeginning of the swallowing cycle.If the occlusion rims do not comeinto contact during swallowingthen the VDO is less.
Method:Cones of soft wax havingexcessive height are placed on thelower base. Salivation is stimulated( using candy) and the pt isinstructed to swallow. Therepeated swallowing reduces theheight of the wax to the occlusalvertical dimension.
• Tactile sense and Patient- perceivedcomfort.The pt’s tactile sense is used asa guide to the determination of thecorrect vertical dimension. Using acentral bearing plate attached to mand:occlusion rim and central bearing screwattached to max: occlusion rim, VD isincreased too high. Then in progressivesteps the screw is adjusted downwarduntil the pt signifies overclosure. Theprocedure is then reversed until the ptsignifies that its just right.
• BOOS BIMETER(POWER POINT)Boos(1940) stated thatmaximum biting force occurs atVDO.A device that measures thebiting force (Bimeter) is attached tothe mand: record base and a metalplate to maxillary.A screw is turned toadjust the vertical relation . Themaximum power point on the gaugeindicates the correct VDO.
• Electromyography• Rest position can be determined byrecording the minimal activity ofmuscles of mastication.• SCRIBING GUIDE LINES