Biomechanical Aspects of MonoblockImplant Bridges for the Edentulous Maxilla

and Mandible:Concepts of Occlusion and Articulation

Rainer Bocklage, DrMedDent, DUI*

Implant treatment consists of 2components: biology of the jawbone and mechanics on implants

and supraconstruction.1 Connectivetissue-integrated implants are inferiorthan osseointegrated implants, be-cause their mobility is increased dur-ing functional loading. However, os-seointegrated implants can loseosseointegration by overload on theimplant bodies.2,3

For implant placement and fabri-cation of implant bridgework, severalfactors are important: the number andposition of implants, the available im-plant surfaces for load transmission onthe jaw bone, the relation betweenlength of the supraconstruction to theimplant body, and finally, the adjust-ment of correct occlusion and articu-lation patterns.4,5 According to the ba-sics of mechanics, a mechanical loadcauses deformation. The stressed bodyworks against this load with the sameforce (action � reaction). Duringloading time, there is a much higherdeformation on the mandible (flexion)than on the maxillary arch. Even thedistance of implants placed betweenthe mental foramina is diminished dur-ing loading. The maximum verticalcomponent of bite force in occlusionin the molar region is 6 to 10 timeshigher than during natural chewingfunction. Supraconstructions have tobe passive and must fit correctly to the

implant abutments. In cases in whichthey do not fit to the abutments, ten-sion on the cortical bone can be notedin the horizontal plane. In the verticalplane, an addition of tensile forces onthe implants is often noticed.

To avoid damages to implants, itis important to respect the followingrules: small differences of the implantaxis in the vertical plane to the otherimplants (parallelism) and clearness inthe concepts of occlusion and articu-lation. Analysis of cantilever bridgesplaced on 4 or 6 implants reveals theharmlessness of forces within the sup-porting polygon.6 Similar axial forceson both posterior cantilevers, how-ever, create undesirable forces: com-pressive force on the posterior im-plants and tensile force on the anteriorimplants. The loading of only one sideof the cantilever bridge is very unfa-vorable. These constructions are ratherdangerous and destructive for poste-rior implants. The implant-supported

bridges presented by the author are notfixed cantilever bridges.7 Setting im-plants in the posterior areas of maxillaand mandible, the monoblock restora-tions are also supported distally. Theocclusion and articulation concept ofimplant-supported bridges has to es-tablish a centric jaw relation and fi-nally to protect implants from over-load and unfavorable forces(compressive, tensile, shear).8,9

CONCEPTS OF OCCLUSION ANDARTICULATION

The common purpose of thoseconcepts is a protection of implants.Occlusion and articulation of implant-supported restorations have to reducestress on the implants.10 For rehabili-tation of the edentulous maxilla andmandible with fixed monoblock resto-rations, the articulation pattern ischanged in a bilateral group guidance.

In a first step, this change is real-

*Private practice.

ISSN 1056-6163/04/01301-049Implant DentistryVolume 13 • Number 1Copyright © 2004 by Lippincott Williams & Wilkins

DOI: 10.1097/01.ID.0000116452.45096.E0

The knowledge of forces that in-fluence implants and suprastructureis important for the restorative den-tist to realize the surface areas andvertical dimension of fixed restora-tions. The purpose of the concepts ofocclusion is to respect the protectionof implants that receive stress trans-mission and being aware of destruc-tive forces. In cases in which theedentulous maxilla and mandibleare provided with large monoblockimplant bridges, the author recom-mends a bilateral balanced group

guidance. If biomechanical princi-ples are not respected, implant lossand restoration failure will result.For the first adjustment of occlusionand articulation patterns immedi-ately after implantation, fixed tem-poraries are placed on the implants.Another 40 to 60 days later, the tem-poraries are exchanged for defini-tive implant bridgework. (ImplantDent 2004;13:49–53)Key Words: biomechanics, forces,overload, group guidance

IMPLANT DENTISTRY / VOLUME 13, NUMBER 1 2004 49

ized by fixed metal/resin temporariesplaced immediately after implantationfor 40 to 60 days on the implant abut-ments.11,12 Applying this procedureshortly after operation, the patientshould adapt easily to group guidance.

Using natural canine guidance insuch cases can cause problems forlong-term success of implants. Duringlateral movement of the mandible, ahigh compression force is noted in thearea of the artificial canine and, aswell, a significant compression on thepremolar and molar zones of the work-ing side. On the disclusion side, animportant tensile force on the implantsis evident. Compression on the work-ing side and tensile force on the con-tralateral side of the arch induce amicromovement of the monoblockbridgework with the unpleasant resultsof bone loss combined with possibleimplant loss. Lots of failures arecaused by this phenomenon. (As Istarted the rehabilitation of the eden-tulous maxilla and mandible withimplant-supported fixed bridges in theearly 1990s, I had a lot of problems 3to 4 years after definitive placement ofthe bridgework because I applied acanine guidance in these cases.)

Using unilateral group guidance,the compressive force is distributed onpremolars and molars of the workingside. Nevertheless, tensile forces arenoted on the contralateral side. Theseforces are less destructive but alsodangerous (Fig. 1A).

Therefore, the author recom-mends a bilateral balanced occlusionin such implant cases. This guidancecauses better loading transference tothe jaw. Under this condition, tensileforces are minimized. The compres-sive force is distributed over almostthe whole arch. During chewing func-tion, the contralateral side is also sup-ported (Fig. 1B). Furthermore, it isimportant to eliminate the palatal con-tacts of the upper incisors during pro-trusive movement. Otherwise, signifi-cant tensile forces are noted in theposterior areas on both sides of theupper bridgework. This lever is espe-cially dangerous for implant patientswith parafunctional habits (Fig. 1C).Finally, it is recommended to elimi-nate prematurities on the occlusal ta-ble of bridgework during lateralmovements.

If the edentulous maxilla is sup-plied with an ordinary removableprosthesis and the edentulous mandi-ble with an implant-supported mono-block bridge, the canine guidance canbe maintained. If in such cases theshearing forces are too high, the upperprosthesis cannot be kept stable on themaxilla. Therefore, these forces arenot destructive to the implants in theedentulous mandible.

According to clinical observationin the last 15 years, in situations inwhich implants are tied together withnatural teeth to restore the jaw with a

monoblock bridge, the natural canineguidance can also be maintained.There are no destructive forces onteeth and implants.

CASE PRESENTATIONSCase No. 1

The edentulous maxilla and man-dible are provided with implants. Theimplants are immediately loaded withfixed metal/resin temporaries. Forty to60 days postoperatively, the definitivemonoblock bridges (metal/porcelain)are fabricated.

The following aspects arerespected:

• Centric jaw relation (Fig. 2)• No canine guidance, but a bilat-

eral balanced group guidance(Fig. 3)

• Prematurities are eliminated dur-ing lateral movements (Fig. 4)

• No palatal contacts of the upperincisors in protrusive movements(Fig. 5)

Case No. 2

The maxilla is restored with aconventional prosthesis. The edentu-lous mandible is provided with animplant-supported monoblock bridge.In this case, the natural canine guid-ance is maintained (Fig. 6).

Case No. 3

In the upper jaw, implants andnatural teeth are tied together with amonoblock bridge. The mandible hasconventional bridgework. Accordingto my clinical observation in the last15 years, canine guidance has no de-structive effects on teeth and implants(Fig. 7).

RESULTS

The occlusion and articulation ofan implant-supported suprastructurehas to diminish stress on the implants.For the treatment of the edentulousmaxilla and mandible with fixed im-plant bridges, the occlusion patternhas to be changed to a bilateral bal-anced group guidance. Canine guid-ance in these cases can cause destruc-tive forces on implants andbridgework. Loss of implants and fail-ure of the restoration are the conse-quences. The first adjustment shouldbe executed with fixed temporaries

Fig. 1. Effects of compressive and tensileforces on implants of monoblock bridges. (A)Lateral movement in unilateral balanced oc-clusion: Compressive force (white arrow) inthe premolar and molar area causes a tensileforce (red arrow) on the contralateral side. (B)Lateral movement in bilateral balanced occlu-sion: Compressive force (white arrow) in thepremolar and molar area causes no tensileforce on the contralateral side. (C) Protrusivemovement: Compressive forces (white ar-rows) on the upper incisors cause tensileforces (red arrows) on both sides of the upperbridgework.

50 MONOBLOCK IMPLANT BRIDGES

(metal/resin) on the implants. They areused for 40 to 60 days after operation.Applying the results of occlusion, ar-ticulation and vertical dimension thetransitional bridges are exchanged fordefinitive bridgework (metal/porcelain).

Beside group guidance, it is im-portant for these bridges to eliminatecontacts on the upper incisors duringprotrusive movement and prematuri-

ties on the occlusal table of bridge-work during lateral movement.13 In theother implant cases that are presented,the canine guidance is applied similarto natural teeth arches.

DISCUSSION

In function, the mandible workslike a hammer and the maxilla repre-sents the anvil. The forces that influ-ence implants and bridgework arecompressive, tensile, and shearingforces. Overload on fixtures leads toan osteolysis around the implants.14,15

The fixtures lose their osseointegra-tion. Without correct articulation, adestructive load transmission is notedon the fixtures. The consequencescould be implant loosening and im-plant fracture. Applying screw-retained bridgework, loosening andfracture of the fixation screws are alsopossible. Implant loosening is oftennoticed in the porous maxillary boneand fracture in the dense mandibularbone jaw. These observations appearto take place especially in the posteriorimplant sites of the lower jaw.

Working according to the princi-ples of gnathology in placing the con-dyles in the most retruded position aspossible (centric bite), and applying abilateral balanced occlusion, the me-chanical load is transmitted over thesuprastructure on all implants. Stressreduction is achieved. A main problemin implantology is bruxism.16 Bruxismis the vertical and horizontal, nonfunc-tional grinding of teeth. Bruxism is themost common oral habit. The maxi-mum biting force of bruxers is greaterthan conventional biting forces. Themaximum vertical component of biteforce in occlusion in the molar regionis 6 to 10 times higher than duringnatural chewing function. In the natu-ral dentition, the maximum force isapproximately 400 N, patients withimplants approximately 200 N, andpatients with conventional prosthesesapproximately 100 N.17

Bruxism imparts overload on im-plants. Even by adapting correct oc-clusion and articulation patterns, theresults in these cases are oftenunfavorable.

CONCLUSION

A knowledge of forces that affectimplants and suprastructure is impor-tant for the restorative dentist to real-ize. This includes the surface areasand vertical dimension of occlusion offixed restorations. The goal is to pre-vent destructive forces on implantbridgework and fixtures. In cases inwhich the edentulous maxilla andmandible are provided with largemonoblock implant bridges, the authorrecommends a bilateral balancedgroup guidance.

Fig. 2. Maxillary and mandibular castsmounted on the articulator.

Fig. 3. A bilateral balanced occlusion of themonoblock bridges is realized.

Fig. 4. Intraoral view of implant-supportedbridgework during lateral movement.

Fig. 5. No palatal contacts of the upper inci-sors in protrusive movement.

Fig. 6. Prosthesis and implant-supportedmonoblock bridge with natural canineguidance.

Fig. 7. Monoblock bridge (teeth and implantstied together) in the maxilla and classicbridgework with canine guidance.

IMPLANT DENTISTRY / VOLUME 13, NUMBER 1 2004 51

DISCLOSURE

The author claims to have no fi-nancial interest in any company or anyof the products mentioned in thisarticle.

REFERENCES

1. Misch CE. Clinical biomechanics inimplant dentistry. In: Misch CE, ed. Con-temporary Implant Dentistry, 2nd ed. St.Louis: Mosby; 1999:303–316.

2. Weinberg LA. Reduction of implantloading with therapeutic biomechanics.Implant Dentistry. 1998;7:277–285.

3. Adell R, Lekholm B, Rockler B, et al.A 15-year study of osseointegrated im-plants in the treatment of the edentulousjaw. Int J Oral Maxillofac Surg. 1981;10:387–396.

4. Engleman MJ, Sorensen JA, Moy P.Optimum placement of osseointegratedimplants. J Prosthet Dent. 1988;59:467–473.

5. Bahat O. Treatment planning andplacement of implants in the posteriormaxillae: Report of 732 consecutive No-

belpharma implants. Int J Oral MaxillofacImplants. 1993;8:151–157.

6. Misch CE. Chapter 10. Diagnosticcasts, preimplant prosthodontics, treat-ment prostheses, and surgical templatesIn: Misch CE, ed. Contemporary ImplantDentistry, 2nd ed. St. Louis: Mosby; 1999:140–141.

7. Bocklage R. Rehabilitation of theedentulous maxilla and mandible with fixedimplant-supported restorations applyingimmediate functional loading: A treatmentconcept. Implant Dentistry. 2002;11:154–158.

8. Stuart CE. The geometrics of thegnathic system. J Gnathol. 1982;1:6–13.

9. Kantor M, Silverman S, Garfinkel L.Centric relation recording techniques: Acomparative investigation. J ProsthetDent. 1972;28:593–600.

10. Weinberg LA. Axial inclination andcuspal articulation in relation to force distri-bution. J Prosthet Dent. 1957;7:804–813.

11. Bocklage R. Advanced alveolarcrest atrophy: An alternative treatmenttechnique for maxilla and mandible. Im-plant Dentistry. 2001;10:30–35.

12. Tarnow DP, Emitiag S, Classi A.Immediate loading of threaded implants at

one stage surgery in edentulous arches:Ten consecutive case reports with 1 to 5year data. Int J Oral Maxillofac Implants.1997;12:319–324.

13. Stuart CE. Overlap of the upper an-terior teeth and its determinants.J Gnathol. 1983;2:3–10.

14. Misch CE. Bone response to me-chanical loads. In: Misch CE, ed. Contem-porary Implant Dentistry, 2nd ed. St. Louis:Mosby; 1999:317–328.

15. De Lange G, De Putter C. Structureof the bone interface to dental implants invivo. J Oral Implantol. 1993;19:123–135.

16. Misch CE. Dental evaluation. In:Misch CE, ed. Contemporary Implant Den-tistry, 2nd ed. St. Louis: Mosby; 1999:124–127.

17. Braun S, Hnat WP, FreudenthalerJW, et al. A study of maximum bite forceduring growth and development. AngleOrthodont. 1996;66:261–264.

Reprint requests and correspondence to:Rainer Bocklage, DrMedDent, DUILangemarkstr.11, D-41539Dormagen, GermanyE-mail: info@drbocklage.de

Abstract Translations [German, Spanish, Portugese, Japanese]

AUTOR: Rainer Bocklage, Dr. med. dent.,DUI. *Privat praktizierender Arzt. Schrift-verkehr: Rainer Bocklage, Dr. med. dent.,DUI, Langmarkster 11, D-41539 Dormagen.eMail: info@drbocklage.de

Biomechanische Aspekte von einteiligen Implantatbrücken für den zahnlosen Ober-und Unterkiefer: Konzeptionen zu Zahnreihenschluss und Artikulation

ZUSAMMENFASSUNG: Die genaue Kenntnis der auf die Implantate und deren Überbaueinwirkenden Kräfte ist für den behandelnden Zahnarzt bei der Wiederherstellungsbehan-dlung von größter Bedeutung, da nur so die Oberflächenbereiche und vertikalen Ausde-hnungen der festen Wiederherstellungsmedien exakt festgelegt werden können.

Das Okklusionsprinzip zielt darauf ab, gestressten Implantaten den erforderlichen Schutzzukommen zu lassen und ein Bewusstsein für eventuell vorliegende zerstörerische Kräftezu entwickeln. Wird ein zahnloser Ober- oder Unterkiefer mittels einteiliger Implantat-brücke wiederhergestellt, empfiehlt der Autor des Artikels den Einsatz einer bilateralaustarierten Gruppenführung.

Missachtet man bei der Behandlung die normalen biomechanischen Prinzipien, muss alsErgebnis mit Implantatverlust und Fehlschlagen der gesamten Wiederherstellungsbehan-dlung gerechnet werden. Für die Erstanpassung des Zahnreihenschlusses und der Artiku-lation unmittelbar nach erfolgter Implantierung werden feste Provisorien auf den Implan-taten befestigt. Nach 40 bis 60 Tagen werden diese Provisorien dann durch dieendgültigen Implantatbrücken ersetzt.

SCHLÜSSELWÖRTER: Biomechanik, Kräfte, Überlastung, Gruppenführung

AUTOR: Rainer Bocklage, Dr. med. dent,DUI. *Práctica Privada. Correspondencia a:Rainer Bocklage, Dr. med. dent., DUI, Lange-markster 11, D-41539, Dormagen, Alemania.Correo electrónico: info@drbocklage.de

Aspectos biomecánicos de los puentes de implante de un solo bloque para el maxilar yla mandíbula edentulosa: Conceptos de oclusión y articulación

ABSTRACTO: En el conocimiento de las fuerzas que influencian a los implantes y lasupraestructura es importante que el dentista de restauración tenga en cuenta las áreas dela superficie y la dimensión vertical de las restauraciones fijas.

El propósito de los conceptos de oclusión es respetar la protección de implantes que

52 MONOBLOCK IMPLANT BRIDGES

reciben la transmisión de tensión y estar al tanto de sus fuerzas destructivas. En casosdonde el maxilar y la mandíbula edentulosa se incluyen con puentes de implantes de unsolo bloque grande, el autor recomienda una guía grupal equilibrada bilateral.

Si los principios biomecánicos no son respetados, resultará en la pérdida del implante yla falla de la restauración. Para el primer ajuste de la oclusión y la articulación inmedia-tamente luego de la colocación, se colocan en los implantes puentes temporarios fijos.Otros 40 a 60 días después, se cambian los temporarios por el puente definitivo conimplantes.

PALABRAS CLAVES: biomecánica, fuerzas, sobrecarga, guía grupal.

AUTOR: Rainer Bocklage, Doutor em Odon-tologia, DUI. *Clínica particular. Corre-spondência para: Rainer Bocklage, Dr. med.dent,, DGI, Langemarkster. 11, D-41539, Dor-magen, Germany. e-mail: info@drbocklage.de

Aspectos biomecânicos das Pontes de Implante Monobloco para as e Mandíbula:

Conceitos de Oclusão e Articulação

RESUMO: O conhecimento de forças que influenciam os implantes e a supra-estrutura éimportante para o dentista restaurador perceber as áreas de superfície e a dimensão verticalde restaurações fixas.

O objetivo dos conceitos de oclusão é respeitar a proteção de implantes que recebem atransmissão de tensão e ser consciente das forças destrutivas. Nos casos em que a e amandíbula são providas de grandes pontes de implante monobloco, o autor recomendadireção de grupo bilateral e equilibrada.

Se os princípios biomecânicos não forem respeitados, o resultado será perda de implantee falhas na restauração. Para o primeiro ajuste de padrões de oclusão e articulaçãoimediatamente após a implantação, próteses temporárias fixas são colocadas nos implan-tes. Uns 40 ou 60 dias mais tarde, as próteses temporárias são trocados por próteses deimplante definitivas.

PALAVRAS-CHAVE: biomecânica, forças, sobrecarga, direção de grupo

IMPLANT DENTISTRY / VOLUME 13, NUMBER 1 2004 53