52 Spectrum dialogue – Vol. 11 No. 1 – January 2012 Utilizing Lingualized Posterior Occlusion in the Construction of Complete Dentures Dr. Laszlo Petruska Dr. Laszlo Petruska received his D.M.D. degree with “summa cum laude” in 1988 from a prestigious dental school in Hungary. Shortly after he immigrated to the U.S. and began his licensing process. He has been practicing in Santa Barbara and Ventura for 16 years. He is specialized in removable prosthodontics and related implant dentistry. Over the years he’s developed or modified many procedures in denture construction such as impression techniques, post dam design, lab communication, improving the natural esthetics, fit and chewing efficiency of partial and complete dentures. Dr. Petruska is a clinical consultant to the American Tooth Industries in Oxnard, and offers continuing education seminars for dental technicians, dental assistants and dentists on dentures and simplified implant techniques.
Lingualized occlusion was originallydeveloped to combine the advantages of theanatomical posterior set up (good esthetics,
easy to arrange and adjust) and the monoplane setup. Using this concept good denture stability canbe obtained utilizing bilateral balanced occlusion.
The lingualized occlusion concept is a variationof the bilaterally balanced occlusion concept. Thepremolars and molars are arranged so that only thelingual cusps of the upper posterior teeth makecontact with the central fossae of the lowerposterior teeth. Exceptions are the firstpremolars which are arranged theopposite way, because it is difficult toestablish contact in the central fossa ofthe first mandibular premolar due toits anatomy. The buccal cusps of themandibular premolars and of themolars do not make contact with theiropposing cusps in central occlusion orduring function.
In comparison to the conventionalanatomical set-up, the number ofocclusal contacts is reducedconsiderably with the lingualizedocclusion concept, only the lingualcusps of the posterior teeth of theupper denture make contact in centricrelation in the central fossae of thelower posteriors. The buccal cusps areout of contact. There is therefore onlyone “centric stop” between upper andlower antagonistic pair of posteriorteeth. This is achieved by arrangingthe teeth in such a way that on boththe working (active) side and thebalancing (passive) side there aresimultaneous bilateral balancingcontacts. Bite forces are therebydistributed over the largest possiblesurface of the edentulous jaw.
With the help of anatomicallyshaped upper posterior teeth, anaesthetically pleasing result can beachieved, while on the lower denture0 degree or 10 degree anatomicalposterior teeth can be used to provide morefunctional benefits. Although any type ofanatomically formed posteriors molars can be usedfor the lingualized occlusion concept by means of
grinding, special combinations have beendeveloped by American Tooth Industries.
In order to guarantee a balanced occlusion, acompensation curve is arranged during the set-upof the mandibular posterior teeth. No posteriorteeth are placed in the ascending part of themandible in order to prevent protrusivedislocation of the lower denture. In most cases thisresults in a reduction of the number of teeth byleaving out the second premolars or the secondmolars, depending on the space available.
Protrusive balanced contacts may only occurbetween the maxillary lingual cusps and themandibular posteriors; in other words, even duringfunctioning the anterior teeth are out of
Fig. 1: Centric Occlusion Contact in Lingualize set-up
occlusion. If anterior interference occurs, eithermove or grind the opposing lower anterior teethslightly or increase the distal incline on the lowermolars by increasing the compensating curve.
To ensure that the supporting upper lingualcusps move completely free in the lower centralfossae, the fossae of the lower posterior teeth mustbe broadened, mainly by means of selectivegrinding. The buccal cusps are just out of contact.For this purpose the upper buccal cusps are groundwhen in contact to create buccal clearance. Thisway the working and balancing cusp contacts aresimplified, since only the upper lingual cuspcontacts the lower occlusal surfaces.
Advantages of lingualized occlusion
In prosthodontics we have always been concernedwith the maintenance of the alveolar bone. Manyideas concerning occlusion and its role inpreservation of the residual alveolar ridge havebeen proposed. It is now widely accepted thatanatomically shaped teeth, if arranged properlyprovide an efficient and aesthetically pleasingposterior set-up for most patients. The presence ofcusps, however does introduce potentiallydestructive forces to the alveolar ridges.
The use of the lingualized occlusion conceptbrings great comfort to these patients as a result of
Fig. 5: Anatomically shaped teeth, if arranged properlyprovide an efficient and aesthetically pleasing posteriorset-up for most patients.
Fig. 6: The facial muscles and the cheeks are well supported bythe more buccally placed maxillary molars, which increasesthe aesthetics value even more.
the modified posteriors of the lower dentures,where aesthetics are not a problem unlike in theupper arch. This is due to the following:
As a result of advanced alveolar boneresorption, a discrepancy arises between thenarrower upper arch and the wider lower jaw.Since only the upper lingual cusps are active theymust be set over the upper alveolar crest, so thebuccal cusps of the upper posterior teeth will belocated close to their optimal location providingthe patient with a broader smile . The occlusalsurfaces of the lower posterior teeth are widened,this way they also can be set closer to their ideallocation. This has the following benefits:
• Because of the reduced number of occlusalcontact points the lingualized occlusion iseasier to set-up, verify and adjust both on thearticulator and in the mouth. This set-up isalso more forgiving since the centric stops canbe placed in an ideal position on the widenedlower occlusal table.
• The anatomical upper posteriors provide thepatient great chewing efficiency since lingualcusps are tall, pointy and their axis isperpendicular to the ridges and the flat lowerocclusal table.
• The advantages of both the anatomical teeth(i.e. aesthetics and chewing efficiency) and thenon-anatomical teeth (i.e. less horizontalforces) are utilized, particularly in patients withsevere alveolar bone resorption.
• Vertical forces are directed more centrally onthe mandibular alveolar ridge, which createsless tilting therefore more stability for thedentures.
• The upper posteriors can be positioned morebuccally on the ridge, because only the lingualcusps are active and should be situated at thetop of the maxillary ridge. In many cases, thiseliminates the need for crossbite arrangementand improves the functional and the aestheticaspects of the dentures.
• The facial muscles and the cheeks are wellsupported by the more buccally placedmaxillary molars, which increases theaesthetics value even more.
In general it can be said that there are nocontra-indications for the lingualized occlusionconcept. This concept is indicated for doctors andpatients who place high aesthetic requirements ontheir dentures and when the goal is to minimizethe horizontal forces during mastication andparafunctional movements in cases of severealveolar bone resorption, flabby and knife edgeridges, abnormal jaw relation and large inter-alveolar space.
