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17A NEW APPROACH IN REMOVABLE DENTURE PROSTHETICSDENTALNEWS, Volume VIII, Number I, 2001

Prosthet ic Dent istry

The Biofunctional Prosthetic System (BPS)

A new approach inremovable denture prosthetics

Dr. O. He1 - Dr. P. Mariani2

1- Olivier He. Vice-Dean and Lecturer, Dental Clinic Htel-Dieu, UniversityParis VII Denis Diderot, rue Lincoln, F-75008 Paris

2- Paul Mariani. University Professor, Dental Faculty Marseilles, Departmentfor Dental Research and Education, Centre Gaston Berger, 19, boule-vard Mireille-Lauze, F-13010 Marseilles

I N T R O D U C T I O NThe treatment of edentulous patients fre-quently goes hand in hand with a numberof clinical and technical problems.According to the authors Olivier He andPaul Mariani, the BPS system, developed

by Ivoclar under the supervision ofProfessor U. Stttgen (University Dssel-

dorf), represents an efficient approach tothe prosthetic treatment of edentulousand partially edentulous patients. As thispublication will show, the Stratos 200articulator is a decisive component of theBPS system. Given the fact that thedesign of the articulator is based onanatomic and geometric concepts, whichwill be described in detail by our authors,the Stratos 200 permits the fabrication of

dentures by means of the template tech-nique. After the comprehensive descrip-

tion of the mode of function of the articu-lator, the working steps involved in settingup denture teeth will be explained indetail.

INDICES: removable denture prosthetics, BPS complete denture prosthetics

external auditorymeatus

Campers plane

occlusal plane

Fig. 1: Orientation of the occlusal plane in relation to the different Camper'splanes (depending on the selection of the posterior reference point) 1: upperposition; 2: central position; 3: lower position).

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18 A NEW APPROACH IN REMOVABLE DENTURE PROSTHETICSDENTAL NEWS, Volume VIII, Number I, 2001

Prosthet ic Dentistry

The Stratos 200 articulator

T h e g e o m e t r i c c o n c e p t

The Biofunctional Prosthetic System(BPS) is based on a logical concept forthe treatment of edentulous and partial-ly edentulous patients. The correspond-

ing therapy concept combines impor-tant treatment steps and provides bothclinicians and dental technicians with anexact and logical method.Today, the use of clinical protocols andsimple, reliable treatment methods thatcan be easily adjusted to the needs ofthe majority of the patients is gaining inimportance. The golden standarddeveloped overseas complies with theabove finding.In the field of complete denture pros-thetics, the BPS System and the Stratos200 articulator, combined with a specif-

ic technique to setup denture teeth,strive to meet these requirements aswell.

This Arcon type articulator has beendeveloped by Ivoclar in cooperation ofProfessor Stttgen (UniversityDsseldorf). It is a multifuctional articu-lator, which means that it is suitable forthe two main concepts of analysis andreproduction of the jaw movements, i.e.the geometric concept and the anatom-ic concept.

The Stratos 200 is based on four maingeometric conditions, which will bedescribed below in the sequence oftheir appearance.

1. Camper's plane

Camper defined this reference plane

during excavations conducted in thesouthwest of Spain in 1780. When theskulls found in the course of the exca-vation were placed in a straight line on atable, all of them resting on the occlusalsurfaces of the maxillary teeth, Camperidentified a plane with the external audi-tory meatus and the sides of the nose asreference points, which ran parallel tothe table surface and thus parallel to theocclusal plane. In the clinical practice,this plane, which runs through the ante-

rior nasal concha and the tragus, wasand still is used as a reference plane inprosthetics.The determination of the anterior refer-ence point is relatively easy and reliable.However, this is not valid for the tragus.There are three possibilities: should theupper edge, the centre, or the lowerpart of the tragus be used as the refer-ence point? The selection of this angleis important as far as the final alignmentof the occlusal plane is concerned(Fig. 1, Table 1).According to the investigations ofKarkaris et al., it seems to be preferableto take the lower part of the tragus as

the reference point.

Occlusal Average Standard Rangeplane value deviationCamper 1 5.25 3.35 -2.0 to 11.50

Camper 2 2.75 3.64 -5.0 to 9.0Camper 3 0.50 3.55 -8.0 to 6.5

Table 1: Average angles between thedifferent Camper's planes and theocclusal plane [2].

Fig. 2: The Balkwill angle is formed bythe occlusal plane and the straightline that connects the incisal pointwith the articular processes.

Fig. 3: The posterior vertical dimensionof occlusion equals L sin (L = dis-tance between the hinge axis and theincisal point; = Balkwill angle accord-ing to Orthlieb).

hinge axis

occlusal plane

referenceplane

Balkwillangle

Fig. 4: Bonwill triangle. An equilateraltriangle between the incisal point (A)and the upper edges of the articularprocesses (B-C). The angle LAD corre-sponds with the Balkwill angle.

reference plane

Fig. 5 Geometric relationship betweenthe Bonwill triangle and theChristensen angle.

2. Balkwill angle

The Balkwill angle was first described onthe occasion of a congress in London in1866. It corresponds with the angle pro-duced by the mandibular occlusal planeof dentulous patients and a secondplane, which runs through the incisalpoint and the two upper edges of thearticular processes (Fig. 2). According tothe author, the corresponding valueranges from 22 to 30.This angle corresponds with the values

suggested by Khler (21 to 22), Hart(20) and Bergstrm (18) as the aver-age, with the extreme values rangingfrom 12 to 24. For the Stratos 200articulator, the Balkwill angle wasdefined at 15, which is rather low com-pared with the above values.In this context, it has to be pointed outthat the Balkwill angle is directly relatedto the distance between the occlusalplane and the condylar axis of rotation.The importance of this distance has

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T h e a n a t o m i c c o n c e p t

been proven by Orthlieb [7] (Fig. 3).According to this author, the bendingradius of the compensation curve woulddepend on the Balkwill angle.

3. Bonwill triangle

After approximately 6000 measure-

ments of mandibles and 4000 measure-ments conducted on living individuals,Bonwill found out that the triangleformed between the incisal point andthe upper edges of the two articularprocesses [8] is an equilateral trianglewith a side length of 104 mm (Fig. 4).Other authors, however, have chal-lenged these results, particularly themeasurements of skulls showing devia-tions of up to 10 mm. Bonwill's measure(104 mm), however, is still a universallyaccepted value. In the articulator inquestion, this value was defined at

108 mm.

4. Monson template [9]The template theory attributed toMonson is based on the theory of theBonwill triangle. According to this theo-ry, the mandibular cusps are arrangedon a part of a circle that measures10.4 cm. Its centre is located on thecrista gali apophysis. However, theabove circle must not be confused withthe curve of Spee [10].

s 110 mm 100 mm 90 mm

() = 110 x sin 60 = 100 x sin 60 = 90 x sin 60

15 0.79 3.64 0.79

30 2.26 2.50 2.78

45 2.26 2.50 2.78

50 3.20 3.53 3.94

/ 30 26 22 18 14 10

5 0.32 0.30 0.30 0.29 0.29 0.28

10 0.61 0.60 0.59 0.58 0.57 0.57

15 0.88 0.87 0.86 0.86 0.86 0.86

20 1.15 1.14 1.13 1.13 1.14 1.1525 1.40 1.40 1.40 1.41 1.43 1.45

30 1.65 1.66 1.68 1.70 1.73 1.76

Table 2a: Incidence of the measures of the Bonwill triangle (s) and the condylarpath () on the Christensen angle [13].

Table 2b: Christensen angle in dependence of the changes of the Balkwill angle() and the condylar path () [14].

Critical analysis

The Balkwill angle, the measures of theBonwill triangle, and the condylar pathare directly related to the phenomenondescribed by C. Christensen [11], as wasconfirmed by the examinations of F.T.

Christensen [12, 13, 14]. The individualfactors can be expressed with the fol-lowing formula (Fig. 5):

sin {(/)/} =sin (/) + p/ sin

= Condylar path = Christensen angle = Balkwill angle = Measures of the Bonwill trianglep = Protrusion length

The combined deviations of the condy-lar path and the measures of the Bonwilltriangle result in a change of 3.15 in theangles of Christensen's phenomenon(Tables 2a and 2b). Likewise, the devia-tions of the Balkwill angle combinedwith the deviations of the condylar pathresult in a change of 1.44 of theChristensen angle. In view of theseresults, it has to be pointed out that theinclination of the condylar path, theBalkwill angle, and the measures of the

Bonwill triangle demonstrate only limit-ed incidence as far as the Christensenangle (i.e. the cusp height) is concerned,which is necessary to achieve a bilater-

ally balanced occlusion. Consequently,the average values that were selectedfor the Stratos 200 articulator are excel-lently suitable for the fabrication of com-plete dentures.

The Stratos 200 is a semi-adjustablearticulator that follows the concept ofsimulating the displacement of themandible.

The maxillary model is aligned with thejoint axis by means of the facebow. Theaxial infra-orbital plane, which is veryclose to the Frankfort horizontal, is usedas the reference plane for the facebow.It is important to note that the presentarticulator demonstrates an angle differ-ence of 15 between Camper's planeand the axial infra-orbital plane. This factis important for the subsequent selec-tion of the correct joint inserts.These inserts are different from conven-tional ones. The concept behind theseinserts rather tends to correspond with

the Condylator articulator according toGerber. The upper part of the joint insertholder does not really simulate thecanine fossa. Rather, the inserts are guid-ing joint inserts, which slide over a hori-zontal, metallic protuberance and actual-ly represent the condyles. The exchange-able joint inserts are available with vari-ous angles, ranging from 15 to 60.If the articulator is used with Camper'splane as the reference plane, the 30inserts are required. If the Frankfort hori-zontal is used as the reference plane,the 45 inserts are needed.

Furthermore, it is also possible to usejoint inserts that are specifically fabricat-ed according to the recordings of theoptical pantograph system according toKlett. However, this technique is notusually applied in clinical practice and isrestricted to certain complex cases(Figs. 6a and 6b).The horizontal displacement of the bal-ancing condyle is achieved by means ofexchangeable Bennet inserts (Figs. 7aand 7b), while that of the vertical

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displacement is adjusted by the innereminence of the TMJ protuberance. Inthis way, the working condyle is lowered(Fig. 8).

Critical analysis

The analysis of this articulator refers toits multifunctionality and the selection ofthe reference plane.How is this multifunctionality achieved?It is the result of two objectives, whichstrongly contrast in the analysis andreproduction of the mandibular move-ments. This contrast was already provenby Monson, who noted that the princi-ples of mandibular movements aredominated by two important concepts.

Fig. 6a: The joint insert holder with thesecuring mechanism for the jaw rela-tion.

Fig. 6b: Exchangeable joint insertsranging from 15 to 60.

The first one assumes that the occlusionof the teeth is determined by the shapeand the movements of the condyles.The second one suggests that the

occlusion of the teeth is the determiningfactor, which controls the shape of thecondyles as well as their movements inthe canine fossa. [15]The first assumption is advocated by allthe supporters of gnathology. The sec-ond concept is backed by the works ofMonson, which have since been redis-covered by Pankey, Mann and Schuyler.The BPS concept is based on the sec-ond assumption and uses canines thathave been designed according to theocclusal morphology defined by Strack.

Fig. 7a: Bennet insert attached to thejoint mechanism of the articulator.

Fig. 7b: Exchangeable Bennettinserts: red = 15; black = 30

Selecting the reference planeIn complete denture prosthetics, there isno generally applicable scientificmethod for the definition of the occlusalplane. Rather, the various methods maybe divided into two groups:Occlusal plane and maxillary arch:Although, from a historical point of view,Camper's plane proved to be the refer-ence plane most frequently used, a vastnumber of studies have shown that this

Downward movement of

the working condyle

Fig. 8: The 'condyle' of the articulator.In a lateral movement, the inner ridgeresults in a downward movement ofthe working condyle. The guiding joint

insert of the upper holder (a) slidesalong the 'condyle' of the lower artic-ulator frame (b).

plane does not seem to run parallel tothe occlusal plane [16, 17, 18, 19].This objection caused a number ofauthors to prefer the Frankfort horizon-tal as the reference plane. The use ofanatomically-correct articulators furtherbacks their decision [20]. In this context,however, it is important to point out thatthis approach is based on a major mis-

conception. The Frankfort horizontalmust never be confused with the axialinfra-orbital plane, since the angle differ-ence between these two planes is 6.5.This fact also explains why the differ-ence between the axial infra-orbitalplane and the Camper's plane of theStratos articulator is 15 and not 10 asit is the case in other articulators, whichare erroneously based on an angle of9.8 as suggested by Downs [21].

Occlusal plane and mandibular arch:In contrast to the above controversy, the

mandibular reference points seem to bepreferred by the majority of the authors.They are most often intra-oral referencepoints, such as the tongue equatorplane, maximum buccinator curvature,or the retromolar triangles [22]. All ofthese references are subsequentlypassed on to the dental laboratory withthe mandibular occlusion pattern. TheStratos articulator offers the indisputableadvantage that it has been designed formodel transfer and orientation accord-

continued on page 25

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C l i n i c a l a p p l i c a t i o n s

ing to the various reference planesselected by the individual practitioners.In clinical practice, there are two meth-ods to mount the models for completedentures in the articulator, dependingon whether the practitioner has selecteda maxillary reference point or amandibular reference point.

Fig. 9: The maxillary model is mountedby means of the bite fork attached tothe lower articulator frame.

Fig. 10: The principle of determiningthe occlusal plane. It runs in the cen-tre of the distance between the low-est points of the folds towards theupper thirds of the retromolar trian-

gle.

Method No. 1: First, the maxillarymodel is positioned in the articulator bymeans of a facebow or a setting-up tem-plate. The facebow allows the spatialposition of the maxilla to be transferredby selecting Camper's plane or the axialinfra-orbital plane as the referenceplane (Fig. 9). Subsequently, the maxil-lary model is mounted in the articulatorusing conventional, clinical techniques.

In a second step, the mandibular modelis aligned in the correct relation to themaxillary model by means of the biteregistrations.

In this case, the measures of the Bonwilltriangle are taken into account, with theexception of the intercondylar distance,which remains unchanged. The (anteri-or/posterior) position of the incisal pointand the Balkwill angles, however, aremore individualized.In the dental office, the practitioneradjusts the ridge of the maxillary modelaccording to the usual criteria: paral-lelism with the pupil line and Camper'splane, lip support, identification of themedian plane.In the laboratory, the model is posi-

tioned on the setting-up template bymeans of the base record and subse-quently secured to the upper frame ofthe articulator. In this case, the Bonwilltriangle of the articulator is exactly main-tained. However, the Balkwill angle isnot individualized.

Method No. 2: If this method is applied,the mandibular model is positioned first.For this step, either the usual anatomicreference points or the base record areused.

In the dental office, the vertical dimen-sion of occlusion is determined and thejaw relations recorded. All these dataare passed on to the laboratory bymeans of the base record.Basically, the occlusal plane meets thefollowing criteria: In the anterior region,the occlusal plane runs at an equal dis-tance between the bottom of themandibular and the maxillary folds,while it runs through the upper third ofthe retromolar triangle in the posteriorregion (Fig. 10). These reference pointsseem to match exactly the ideal course

of the occlusal plane, which has alsobeen confirmed by the works of Cbelic[22].In the laboratory, the models are mount-ed according to the following method:What is known as the horizontal guide(Fig. 11) is used to position the mandibu-lar model in the articulator. This compo-nent is attached to the upper frame ofthe articulator and is equipped with asmall ruler that can be vertically adjust-ed. Furthermore, it features a horizontal

insert that can be adjusted towards thefront and the rear.In a first step, the reference point of themaxillary centre (between the central

incisors) is transferred to the mandibularmodel. After that, the distance betweenthe lowest points of the mandibular andmaxillary folds is measured (Fig. 12).In the second step, the small ruler isadjusted to a value that corresponds tohalf the distance between the two foldswith the two ends of the ruler resting atthe bottom of the folds. In the posteriorregion, the wings of the horizontal guidetouch the upper third of the retromolartriangles (Fig. 13). The mandibular modelis mounted on the horizontal guide withsticky wax or silicone. Subsequently, the

entire unit is attached to the upperframe of the articulator (Fig. 14). In thisway, the mandibular model is exactlyoriented according to the Bonwill trian-gle. However, the Balkwill angle is notindividualized. Finally, the maxillarymodel is positioned in the articulatorwith the help of the base record.

If the occlusal plane of the wall of themandibular base record is aligned withthe mandibular reference points, thehorizontal guide is attached to the ridge.In this process, the median plane andthe centre line between the centralincisors have to be taken into consider-ation. Subsequently, the mandibularmodel is positioned in the articulator. Ifthe models are positioned by means ofthe base plate or the horizontal guide,

Fig. 11: Horizontal guide.

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the 2D setting-up template may be usedto set up the posterior teeth.If a facebow is used, however, the mod-els are not oriented according to thegeometric reference points. In these

Fig. 12: Measuring the distancebetween the lowest point of themandibular fold and the maxillary fold.

Fig. 13: In the distal area, the horizon-tal guide rests in the upper third ofthe retromolar triangles. In the front,the end of the small ruler rests in the

median plane.

Fig. 14: The mandibular model attachedto the horizontal guide is positioned inthe articulator and secured by meansof a fast-setting plaster.

cases, a setting-up template is requiredthat permits three-dimensional orienta-tion of the teeth (Figs. 15a and 15b).These two setting-up templates demon-

strate a curve radius of 125 mm, whichis 20 mm more than the value suggest-ed by Monson. However, the incidenceof occlusion between these two radiidoes not exceed 0.1 mm.

Setting up the denture teeth

The setup is carried out according to thetemplate technique, in other words, anocclusal pattern, in which all occlusalforces are directed according to theRobin support cone. This method pro-motes the stability of the dentures (ofthe mandibular dentures in particular).The suggested setup technique offersthe following two sets of features: In thelaboratory, this method is both easy tocarry out, as well as exact and codified.The suggested working steps enabletechnicians to set up the teeth in opti-mum symmetry. At the same time, thecorrect relationships between the twodental arches can be checked at alltimes. Moreover, the sagittal and frontalcompensation curves may be estab-

lished in harmony with the morphologi-cal properties of the occlusal surfaces.

In the dental office, the use of a setting-up template permits quick and reliablechecking of the position and the corre-sponding orientation of each group orunit of teeth.However, the following seven workingsteps must be meticulously observed inorder to benefit from the above advan-tages:

1st working step: Recording the vari-

ous reference points

Analysis of the models: In addition tothe classical reference points, such asthe median plane or the perpendicularcanine plane in the anterior region(which runs through the central palatalfold), the axes of the posterior sectorsare defined for the maxillary model. Inthis process, it has to be made sure thatthese axes run through the outer quar-ter of the tubera (Fig. 16).

Fig. 15a: Underside of the 2D setting-up template.

Fig. 15b: The 3D setting-up templatepermits three-dimensional orientationof the template.

As far as the mandibular model is con-cerned, the reference points recordedare comparable, i.e. axis of symmetry ormedian plane, anterior ridge axis in thefrontal plane, axis of the posterior sec-tors, which points towards the positionof the canine in the inner quarter of thepear-shaped elevation or retromolar tri-angle (Fig. 17).

Analysis of the interocclusal relationof the dental arches: The general axesare extended in the distal parts of themodel. This enables the practitioner toassess the transverse relations and todetermine the bucco-lingual position ofthe intercuspal fissure (Figs. 18a and18b). In this context, the fact that thefrontal inclination of the occlusal planein the Stratos 200 articulator dependson the transverse size of the arch andnot on the inclination of the axisbetween the two ridges must be takeninto account. This approach is different

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from Gysi's, who assumed that the incli-nation between the ridges influencesthe frontal inclination of the occlusalplane (Fig. 19) [23].

2nd working step:Setting up the maxillary anterior teethOnce the size and the shade of the teethhave been selected, the maxillary ante-riors are set up according to one of thefollowing two methods:

Observing the ridge determined by thepractitioner: The teeth are set upaccording to the usual criteria, such ascentral lip support, symmetry, etc.

Observing the anatomic criteria: Withthe BPS System, anatomic reference

Fig. 16: Reference lines of the maxil-lary arch: (a) median plane, (b) the axisof the posterior sectors runs throughthe outer quarter of the tubera, (c)canine plane, (d) tubera.

Fig. 17: Reference lines of the

mandibular arch: (a) median plane, (b)the axis of the posterior sectors runsthrough the inner quarter of the retro-molar triangle, (c) canine plane thatruns through the vertex of the frontalridge, (d) retromolar triangle.

points, i.e. the palatal folds, are takeninto consideration when positioningthe anterior teeth.

The bucco-lingual dimensions of the

central incisors are always identical inthe cervical area (7 mm), which indirect-ly facilitates their setup. The centralincisors are set up on either side of thecentral palatal fold (seen from the medi-an plane) (Fig. 20). The incisal edges arelocated two millimetres in front of thehalfway point between the two ridges. Inthis way, a slight anterior overbite isensured. The actual degree of the over-bite is adjusted to the correspondingsetup method used for the posteriorteeth (0.5-1 mm with a lateral overbite;2-3.5 mm with a pronounced lateral

overbite).Positioning the setting-up template onthe lower part of the articulator allowsthese parameters and the correspon-ding symmetry to be checked.After that, the maxillary canines are setup, for which the palatal folds are usedas the reference points. There is a cor-relation between the position of thecanines and the first two palatal folds[24]. The tips of the canines are locatedon an imaginary straight line that runsthrough the large axis of the palatal

folds. The cervical areas of the caninesare positioned two millimetres awayfrom the end of the folds. In this way, thevestibular side of the teeth are nine mil-limetres away from these ends (Figs. 21and 22). Finally, the lateral incisors areset up, taking the morpho-physiologicalcharacteristics of the patient intoaccount.

Fig. 18a: In the Stratos system, thefrontal orientation of the occlusalplane is independent of the inclinationof the axis between the ridges.

curvature ofthe setting-up

template

3rd working step:Setting up the mandibular canines

During the setup of the mandibularcanines, it has to be made sure that thedistal sides are located perpendicular tothe tips of the maxillary canines. Thissetup prevents the mandibular caninesfrom producing a pronounced over-turning moment during excursive move-ments (Figs. 23a and 23b). At the sametime, an overbite of approximately onemillimetre is achieved.

4th working step:Setting up the mandibular posteriorteethThe morphology and the mould of theposterior teeth are selected accordingto the jaw relation type (angle class)(Table 3).When positioning the setting-up tem-plate, the front part has to be positionedat the height of the distal angle of themandibular canines. The canine tipsmust protrude over the front edge of thesetting-up template by 1 mm.

The posterior teeth are set up accordingto the defined axis that runs from theanterior region to the posterior region.All the vestibular cusps of the mandibu-lar teeth come in contact with the set-ting-up template (Fig. 24). However, onlythe lingual cusps of the second premo-lars and the mesial cusps of the secondmolars touch the template. The graduat-ed reference points allow continuouschecks of the symmetry and the lineari-ty of the setup.

Fig. 18b: According to Gysi, the frontalorientation of the occlusal planedepends on the inclination of the axisbetween the ridges.

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5th working step: Setting up the maxil-lary posterior teethThe maxillary posterior teeth are set upin such a way that optimum occlusionwith the mandibular teeth is achieved.For that reason, the contact cusps musttouch the corresponding contact sur-faces in the antagonist dental arch(cusp/interdental area in the premolarregion and cusp/fossa in the molarregion (Fig. 25)).

6th working step: Setting up themandibular incisorsThe mandibular incisors are the lastones to be set up. In this process, thesagittal overbite proportional to theangle class and the height of theocclusal plane must be observed. Withthis method, the ideal occlusal relations

between the incisors, the premolars,and the molars, which have been estab-lished with the previous working steps,can be maintained.

7th working step: Checking the occlu-sion

At this point, the harmony of the setupduring lateral movements is checked:

In protrusion, the mesial inclines of thepremolars, the mandibular molars, as

Fig. 19: Reference lines of the axesbetween the ridges. The axes of themaxillary sectors (a) and the mandibu-lar sectors (b) are extended in theposterior part of the model. The gen-eral setup axis (c) is located in thecentre of the distance between themaxillary reference points (a') and thereference points of the mandibularaxes (b).

well as the free edges of the mandibu-

lar anteriors touch the inclines of theantagonist maxillary teeth.

During lateral movements, the incisorsand the mandibular premolars on theworking side touch the inner inclinesof the maxillary premolars. In contrast,the lingual cusps of the premolars andall the molar cusps are not in occlusion(Fig. 26).

width of tooth neck

Fig. 20: Position of the incisors in rela-tion to the central palatal fold.

Fig. 21: The cervical ridge of thecanines is located at a 2-mm distancefrom the ends of the main palatal fold.

Therefore, the design of the workingside corresponds with the principle of

group guidance. This concept, however,is entirely contrary to the principle of thedynamic rest cone according to RobinFisher [18]. This approach might resultin an overturning moment, partic-ularlyif severe atrophy is present in the area ofthe maxillary cusps. Together with thebalancing side, the two rearmost molarsare in contact.Subsequently, the dentures are complet-ed, polymerized, polished and incorpo-rated into the oral cavity of the patient.With the BPS System, selective grindingis not required. The concept of occlu-

sion should permit optimum balanceduring the various lateral movements ofthe mandible.

Fig. 22: The reference points on thesetting-up template attached to thelower frame of the articulator permitthe checking of the symmetry.

Fig. 23a: Position of the canine inocclusion.

Fig. 23b: In lateral movement, the dis-tal incline of the mandibular canineslides along the mesial incline of themaxillary canine.

Jaw relations Type of tooth

Class I N

Class II T

Class III K

Table 3 Properties and indications ofthe posterior teeth according to theangle class.

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Fig. 24: Setup in the mandible in con-tact with the setting-up template.

C o n c l u s i o n s

A c k n o w l e d g e m e n t

A streamlined setup procedure as apart of a comprehensive denture fab-rication system undoubtedly repre-sents an advantage for patients, prac-titioners, and dental technicians alike.In this respect, the BPS System meetsthese requirements. However, the fol-lowing three points must be takeninto consideration:

1. Golden standards: Although theconcept has been developed in theUnited States, the trend is such thatthe system is particularly popular in

Germany and the Scandinavian coun-tries. Moreover, certain selection cri-teria and technical possibilities of theconcept can be explained if oneknows the country of origin.

2. Selection of Camper's plane: Theentire German teachings according toGysi and Gerber are based onCamper's plane. Do we have to

renounce this approach in favour ofthe Frankfort horizontal or the axialinfra-orbital plane? Undoubtedly, it ismore a habit than a real therapeutic'plus', even if certain investigations

[Literature available from the authors]

We would like to thank Ivoclar for thetechnical support.Ivoclar AktiengesellschaftBendererstrasse 2FL-9494 Schaan / LiechtensteinFax ++423 / 235 33 60

Fig. 25: Intercuspation.

Fig. 26: Setup during lateral movement.

have attempted to demonstrate thetherapeutic superiority of orientingthe occlusal plane according to theFrankfort horizontal instead of the

Camper's plane.

3. Selection of the articulator and thesetup method: The BPS System cer-tainly offers a number of decisiveadvantages when it comes to settingup denture teeth. Even if the templateprinciple of starting the setup with theposterior sectors in the mandible hasbeen known for quite a while, therevival of this method satisfies a gen-uine technical necessity. It permitsoptimum control of the lingual spaceand improved distribution of the

occlusal stress on the underlying restareas.

Le professeur Pierre RISCALLAH me fait ungrand honneur en me demandant dcrireune prface ce nouveau livre.Je nai pas prsenter le professeur

RISCALLAH au public professionnel libanais,spcialis ou non. Tous connaissent cet mi-nent MatreCet ouvrage reprsente lnorme travaildun auteur qui sait prendre ses respons-abilits.Il pense offrir au spcialiste dOrthopdieDento-Faciale une possibilit effective de

mieux cerner les problmes thoriques etpratiques qui sont la base de la Spcialitet restent non rsolus. Il espre ainsiramener LO.D.F., qui vient de traverser,selon lui, une priode de dsorientation, sur

une voie quil juge la fois nouvelle etexacte.Le professeur RISCALLAH sait combien jap-prcie son attachement ses ides.Loriginalit de ses conceptions mrite uneapprobation sans rserve, du moins un sen-timent admiratif pour la qualit et la naturede son savoir.

Il tente dans cet ouvrage de nous fairepartager sa philosophie fruit de quaranteans dexprience.Je souhaite quil y parvienne

Zouhair SKAFF

Directeur, Socit Libanaise dOrthodontie

PRECIS DORTHODONTIE

PRECIS DORTHODONTIE

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