Dr. Eugen End Physiological Occlusion of Human Dentition · 2014-12-10 · Physiological Occlusion...

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Physiological Occlusion of Human Dentition Dr. Eugen End Diagnosis & Treatment

Transcript of Dr. Eugen End Physiological Occlusion of Human Dentition · 2014-12-10 · Physiological Occlusion...

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PhysiologicalOcclusion of Human Dentition

Dr. Eugen End

Diagnosis & Treatment

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Verlag Neuer Merkur GmbH

PhysiologicalOcclusion of Human Dentition

Dr. Eugen End

Diagnosis & Treatment

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Bibliografische Informationen der Deutschen BibliothekDie Deutsche Bibliothek verzeichnet diese Publikation in der Deutschen Nationalbibliografie; detailliertebibliografische Daten sind im Internet über http://dnb.ddb.de abrufbar.

© 2006 Verlag Neuer Merkur GmbHPostfach 60 06 62, D-81206 München

Copyright under the International Copyright Laws. All rights reserved. This book is protected by copyrightand all applicable laws. No part of this book may be reproduced in any manner or by any means withoutwritten permission from the publisher. In spite of all efforts undertaken by the authors as well as the publis-her to exclude any mistakes possible, neither may be held responsible for any misoccurances resultingfrom information in this book.

Dr. Eugen EndPhysiological Occlusion of Human Dentition – Diagnosis and TreatmentOriginal title: Die physiologische Okklusion des menschlichen Gebisses – Diagnostik und Therapie 2005

Translated from German into English language by Louise Cyffka

1st Edition 2006ISBN 3-937346-36-8 ISBN 978-3-937346-36-6

Layout: Ute-Buchholz-Gall

Printed by Bonifatius GmbH, Druck-Buch-Verlag, Paderborn

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Table of contents

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Table of contentsPreface ...................................................................................................................................7

Foreword................................................................................................................................8

Introduction........................................................................................................................15

Part A The anatomy of natural dentition ..................................................................231. Function and tooth mould ..............................................................................................232. The physiological centric ................................................................................................273. Individuality and freedom in occlusion ........................................................................304. Anterior Posotioning........................................................................................................43

Teil B The physiology of human dentition ...............................................................491. The physiological movements of the mandible ..........................................................492. The non-physiological movements of the mandible ..................................................69

Teil C Physiology applied to the modelling of teethin fixed dental restorations...............................................................................81

1. Incisors and canines ........................................................................................................821.1. Modelling of the upper central incisor ..................................................................891.2. Modelling of the upper lateral incisor ...................................................................911.3. Modelling of the upper canine ...............................................................................941.4. Modelling of the lower incisors...............................................................................961.5. Modelling of the lower canine.................................................................................99

2. The premolars ................................................................................................................1012.1. Modelling of the first upper premolar .................................................................1052.2. Modelling of the second upper premolar ...........................................................1082.3. Modelling of the first lower premolar ..................................................................1102.4. Modelling of the second lower premolar ............................................................113

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3. The molars ......................................................................................................................1163.1. Modelling of the first upper molar .......................................................................1213.2. Modelling of the second upper molar .................................................................1243.3. Modelling of the first lower molar ........................................................................1273.4. Modelling of the second lower molar ..................................................................130

Teil D The application of the physiological occlusion in complete denture prosthetics ...................................................................135

1. Position and setup of the anteriors .............................................................................1402. The occlusal plane and its horizontal, sagittal and helicoidal curve

of occlusion .....................................................................................................................1443. The occlusal height ........................................................................................................1474. The physiological centric and its registration ............................................................1535. Setup, overbite and contacts in the anterior area .....................................................1556. Position and setup of the posteriors ...........................................................................1587. Occlusal freedom ...........................................................................................................1658. The physiology of mastication and setup of the molars ...........................................167

Explanation of Terms.....................................................................................................173

Bibliography ....................................................................................................................179

Key word index ................................................................................................................185

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Preface

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PrefaceThe so-called scientific nature of occlusal concepts is a controver-sial issue. What may have been founded on a plausible theore-tical basis for years is often simply accepted without any furtherclinical evaluation. Before we know it, based on clinical acceptan-ce, they are deemed scientifically evident and these theoriesare accepted as correct for daily clinical application. The objec-tive of any study should be to evaluate the scientific evidenceof the proposed concept. The scientific basis for these studieswas established long ago. Theophrastus Bombastus of Hohen-heim (1493 – 1541) – better known as Paracelsus – is still consi-dered today to be the founder of a modern understanding of sci-ence. He defines the basis of scientific activity as unbiased ob-servation. The merit of this author is that he has done preciselythis consistently over a number of years. The results of these ob-servations are presented in this book, and the logical conclusi-on is the concept of physiologically based occlusion. That is whythis new publication deserves our undivided attention. It analy-ses, summarizes and develops new perspectives on occlusion –a subject we actually thought we already knew all the theoriesand explanation models.

Witten, Germany, May 2005

Prof. Dr. Axel Zöllner

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ForewordIt is a result of occlusion that the temporomandibular joint is theonly human joint with a fixed end point. Both the centric supportand the vertical adjustment via the posterior teeth make the phy-siological adjustment of the discus/condyle complex with refe-rence to the temporal joint structures possible. Even if the signi-ficance of occlusion for maintaining the health of the masticato-ry organ has recently become increasingly disputed, there isnevertheless no doubt that an non-functional occlusion can leadto dysfunctions of the stomatognathic system.

It is a good thing, therefore, that the author has made bio-logi-cal occlusion the subject of this book. His main interest is focu-sed on the correct three-dimensional adjustment of the centricwith stable point-contact support in the main centre of occlusalforce. According to his observations of numerous healthy denti-tions in every age group, the number of occlusal contacts increa-ses in the area of the second premolar and the first molar. Thisis in keeping with the habilitation treatise of my former colleague,P. Rammelsberg, who has statistically proven that the loss of thevertical support zone in the posterior area can be seen as a riskfactor for the development of structural joint alterations.

According to Dr. End's philosophy the reconstruction of lost toothsubstance is thus not to be seen as a single, isolated structurewhich must be reconstructed, as it were, in a vacuum. The occlu-sional reconstruction is individually variable in a neuromuscularsense and within certain limits. True to the anatomical principleof the reproduction of form and function, our goal should alwaysbe the axial loading of the tooth.

Foreword

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Foreword

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This book provides valuable hints to the dental technician not on-ly for the design of the occlusal surface, but also for the tooth inits entirety. Dental students are given useful basic principles andinstructions – particularly valuable for their first semester – withregard to the correct anatomy of the teeth. For all types of prost-hetic rehabilitation from the single crown to complete dentureprosthetics, this book offers the dental practitioner not rigid, me-chanistic rules, but more flexible general guidelines based onbiological and neuromuscular principles.

In this context I would like to offer my best wishes for the widecirculation of this book and the principle of bio-logical prosthe-tics.

Munich, Germany, May 30, 2005

Prof. Dr. Dr. h.c. W. Gernet

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Foreword

ForewordWith this book I would like to create a true– and truly infectious – atmosphere of lear-ning, in which every reader can comparehis and my viewpoint with the various dif-ferent schools of thought and offer criti-cism with an open-minded attitude. Myown point of view is based on the princi-ples of natural dentition. This book is sim-ply the result of my observations of nature,which I have emulated and taken as thebasis for my work.The development process of the theorieson this subject should be kept in motionby a creative and critical spirit, while at thesame time exercising rigorous disciplinein one's thinking.

Throughout the course of the years, I ha-ve had the opportunity to communicatewith a great many people, make extensivestudies of the literature and gather expe-rience as a dental practitioner in order todevelop both in theory and practice theobservations made from nature.

It all began with a study of 60 natural den-titions which I carried out in collaborationwith my friend Hermann Geldreich duringmy studies at the Department of Conser-vative Dentistry of the University of Frei-

burg under the leadership of Prof. M. S.Schreiber and Senior Physician Dr. B. Klai-ber in 1976.

The controversial discussion on occlusion,the differing practical applications in thedepartments of the Faculty of Dentistry,the discrepancy between the theoreticalpostulates and the possibility of their prac-tical application left me in a state of per-plexity. I sought the answer in nature andin naturally conserved dentition. What Idiscovered in its diagnosis and studies ofthe literature moved me to devote myselfto this subject with even greater enthusi-asm than before.

I was thus influenced to a great extent, forexample, by the insights of Dr. Carl Hilte-brand, who distanced himself at an earlystage from the mechanical articulationtheory in favor of the dynamic, physiolo-gical approach. It is interesting to see thatproblems in dentistry which are now onceagain topical have already been discus-sed decades before this. It is rather asto-nishing, and hardly surprising that the fun-damental results obtained in 1978 by H.C.Lundeen and Ch. H. Gibbs on the humanprocess of mastication to this day still donot have the standing they deserve in viewof their significance for their implementa-tion in the manufacture of dental restora-

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tions. Their experimental results corre-spond to my observations of the conser-vation of tooth morphology under physio-logical conditions.

I was further helped to understand thephysiological movements of the mandibleby the results of the classical experimentby W.Gernet. He observed the propriocep-tive behaviour of the control of mandibu-lar movements in patients with good oc-clusion and those with inbuilt occlusal in-terferences. He used the mandibularkinesiography to record the speed at whichthe centric is taken up with and withoutpremature contacts.

During my studies he was an Assistant inthe Prosthetics Department of the Univer-sity of Freiburg under Prof. Dr. W. Reither,and at all times maintained a critical andanalytical stance towards all theories.

It was Prof. Dr. A. Puff who made me sit upand pay attention in his anatomy lectureswhen he spoke of his knowledge about thephysiological anatomy of the mandible;that according to radiocinematographicstudies the mandibular movement slowsdown shortly before centric contact occurs,and is subsequently brought into a newopening movement by a kind of switch inthe direction of movement.

The gnathological era, gave me the oppor-tunity during my first semester in denti-stry in Munich to study the waxup techni-que according to E. V. Payne and H. C. Lun-deen. However, this experience clashedwith my growing understanding of physio-logical occlusion in the fact that in additi-on to waxed-up occlusal surfaces it was al-so customary to set up partial dentureswith reduced and simplified occlusal re-lief patterns.

Functional analyses in diagnosis and the-rapy according to Arne G. Lauritzen show-ed me the more technical static and me-chanical correlations between the tempo-romandibular joint, tooth guidance, teethin the dental arch and occlusal surface de-sign. They were largely based on geome-trical principles. In accordance with theseprinciples it was sought to construct andto find centres of movement that were re-sponsible for the paths of movement ofthe mandible in relation to the maxilla un-der tooth and joint guidance.

From the 1960s to the 1980s mandibularmovements were predominantly under-stood as ideal movements. The hinge axiswas determined and the border move-ments and other parameters such as thehorizontal condylar path inclination, theBennett angle, the intercondylar distance

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and the side-shift were recorded. Thesewere mounted in partially or fully program-med articulators in different, assumed,ideal centric positions

The analysis of natural dentitions and theirdeductive anatomical and physiologicalinterpretation awakened in me the under-standing that we cannot find a finishedtemplate of a centric position in the me-chanical sense. It is much more a questionof finding a way of working in a biologicalenvironment.

As a dental student from 1972 to 1977 I wasobliged to make complete denture prost-heses with bilateral balancing and was te-sted on this in my State Examination.Gausch, however, began in 1976 to intro-duce anterior/canine guidance to the the-rapy of complete denture prosthetics. An-terior/canine guidance was, and still is, formany authors today, the domain for fixeddental restorations. One example I haveexperienced is vehemently and uncom-promisingly represented in continuingeducation courses by Bob Lee in theKempten study group.

With increasing knowledge and experiencegained from the observation of naturaldentition, I continued to rely more and mo-re on neuromuscular guidance. From 1977

onwards I departed farther and fartherfrom the concepts of tooth and joint gui-dance.

In the 1980s and 1990s the departure fromstatics towards more dynamics and functi-on was revealed in the biomechanicaltheories, represented by Freesmeyer, Sla-viceck, Kubein-Meesenburg, Polz orSchulz.

The considerations with regard to muscu-lar dynamics of Graber, W. Gernet, B. Jen-kelson and W. Schöttl have recently begunto challenge many dogmas to date. Theirobservations demonstrate with increasingclarity that the movements of the mandi-ble cannot be performed and recorded withacribic mechanical precision, but that it mo-ves biologically in a flowing balance that iscontrolled by regulatory mechanisms.

Armed with the fundamental insights gai-ned from naturally conserved dentitionsand with their anatomical, physiologicaland deductive theory of cognition, it wasat times highly interesting to observe thedevelopment of traditionally accepted oc-clusal theories.

As a student in 1976 I went to Vita Zahnfa-brik in Bad Säckingen with a set of poste-rior teeth I had modelled myself in kee-

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ping with this new concept of occlusion. Ihad the idea of having denture teeth pro-duced according to nature's example. Den-tistry was primarily in the gnathological'spirit of the age', however, and it wasagreed to delay design and manufacturingof these dentures for another ten years.Mr. Henry J. Rauter kept a watchful eye ondevelopments and sensed when a changebegan to occur. It is he to whom I am mostgratefully indebted. In 1986 he introducedthe beginning of the technological deve-lopment of an artificial tooth according tonature's example. This led the way in 1992to Physiodens becoming our model interms of form and philosophy for a wholenew generation of prosthetic teeth.

I would like to mention Martha Freyer anindefatigable and undaunting member ofthe product management for teeth; shewas regrettably obliged to leave the fielddue to health reasons in 1998. With her ex-pertise, single-minded sense of purposeand sheer ability to get things done, she“sponsored” the new teeth. I would like totake this opportunity to express my speci-al thanks to her.

In Viktor Fürgut, dental technician and de-partmental manager of the acrylics prost-hetics department of the laboratory UlrichGötsch in Ravensburg, I have the good for-

tune of an outstanding partner in dentaltechnology. Viktor has systematically deve-loped the physiological theory of cogniti-on and implemented it biologically par ex-cellence in the set-up of complete and par-tial dentures. His work strives to perfection – but withoutlosing an ounce of its practice-oriented ap-proach. Even complete denture prostheses,virtually indistinguishable from nature inshade and form, can be easily integrated in-to his procedure in the day-to-day routineof the dental laboratory. I would like to of-fer him my very special and sincere thanks. Ms. Solvey Bossen modelled the Physio-dens anteriors and is also responsible forthe illustrations in Part C of this book, “Phy-siology applied to the modelation of teethin fixed dental restorations”. Helmut Sil-mann placed at our disposal his experti-se in dental technology by assisting in themodelation of the posteriors.I would also like to offer my warmestthanks to Ulrich Götsch, Master DentalTechnician and proprietor of the dental la-boratory, for his generosity in putting hismaterials and the time and know-how ofhis employees at our disposal.My patients and I have had the benefit of25 years of his dental technology experi-ence, and the standards he sets are a sour-ce of inspiration to his laboratory team.

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Christoph Freihöffer, Master Dental Tech-nician, began in his daily work – initiallyunknown to me – to wax up and layercrowns in functional occlusion accordingto my Physiodens set-up brochure. His im-proved results and his successes even inproblem cases, his expertise and knowled-ge thus brought us together, so that I amgrateful to him to now have the opportuni-ty of holding courses jointly with him inbio-logical prosthetics in the field of fixeddental restorations.

While working on the manuscript I founda dedicated assistant in Frieder Bertele,who put the handwritten work and photo-graphs I submitted onto reproducible da-ta media in the form required by the pu-blishers. The word processing was under-taken by Steffi Schmid; I am much obligedto both of them.Without the excellent assistance of my pro-fessionally trained dental assistants overmany years with the innumerable typingassignments, analyses and dental assistan-ce tasks, this successful teamwork suchwould not have been possible. I wouldtherefore particularly like to thank Corne-lia Bucher, Helga Foss-Roos and Irina Frei.

My wife and my daughter Eva were obligedto make many sacrifices during the years ofthe development of the Physiodens teeth,

the continuing education courses and notleast this book, for which I would like to gi-ve them too my warmest thanks.To my daughter Anne, who is studying den-tistry in her 4th semester, I would like togive an illuminating insight into the pro-blematics of occlusion. And for mydaughter Andrea, a student of law, I wouldlike to impart the most important princi-ple of justice: “Audiatur et alta pars” (li-sten also to the other side), also a basicprinciple for me, to which I add, “et credipoco” (and believe little).As a student of medicine, my daughter Ka-trin can critically examine the aspects ofmedicine and their deduction from nature.For my stepdaughter Anna I quote a sen-tence from Nikos Kazantzakis: “Everythingwhich does not exist we have not desiredenough”.My warm thanks go to Mrs. Louise Cyffkafor the English translation of my book. Shetranslated the difficult text with interestand love for the subject.

And finally, I would like to express my sin-cere thanks for the excellent collaborati-on of the publisher Neuer Merkur.

Ravensburg/Weingarten, Germany, October 2004

Eugen End

Foreword

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Introduction

IntroductionThere is hardly a more heated topic for dis-cussion in the field of dentistry than thefundamental principles of occlusion, theirfunctionally oriented diagnostics, treat-ment planning and therapy in our masti-catory system.

The main aspect of dental occlusion whichtends to frustrate students of dentistry,dental technicians and dentists alike is thedeep chasm that exists between the dif-ferent schools of thought in the sector ofocclusal therapy. The existing therapeuticrequirements were – and still are today –in conflict with the possibilities for theirpractical implementation on a consistentbasis.

At the time I was a student of dentistryfrom 1972 till 1977, the concept of bilate-rally balanced occlusion (Gysi, Spee, andMcCollum) was predominant. In the fieldof fixed partial dentures the concepts ofgroup guidance (Schuyler, Pankey, Mann,Ramfjord, Slaviceck) and anterior guidan-ce (Dawson, D'Amico, Lee, Lauritzen) we-re controversially discussed and practical-ly implemented in different ways. In or-thodontics, the classification criterion fornormal occlusal relationships in the ante-

rior area was considered to be an overbi-te of 2 to 3 mm (Schulze, Rakosi). Unfortu-nately the results often permitted toothguidance or group guidance with freedomin balancing either with great difficulty ornot at all.

Partial dentures and combinations of par-tial and complete denture prosthetics ca-ses with fixed dental restorations or natu-ral dentition were caught up – as they stillare today – between the various theoreti-cal and practical demands made on occlu-sion with regard to statics and dynamics. Interms of the history of dentistry, the con-cepts in dynamic and static occlusion haddeveloped mainly from the discipline ofcomplete denture prosthetics, since thisis the area that requires the complete newdesign of the dental arches.

By the early 1950s recognition was begin-ning to emerge that the concept of bila-teral balancing can result in unphysiologi-cal stresses on natural dentition. Further-more, that these stresses in turn can giverise to parafunctions which may damagethe hard tooth substance as well as the sur-rounding periodontal tissue.

In 1976 Gausch began to introduce ante-rior/canine guidance to the field of com-plete denture prosthetics. As a result of

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Introduction

his studies (published in 1986 in the Ger-man periodical DZZ) and the Innsbruckschool of thought that followed him, weknow today that complete denture prost-heses function also with anterior guidance.

Also in the field of static occlusion the con-cepts differ in terms of the number of con-tact points, their position and whether theyare point or area contacts. A much-deba-ted topic both in theory and in terms of itspractical implementation is whether thecontacts take place in habitual intercuspa-tion, in a more ventral or retral contact po-sition firmly anchored with maximal inter-cuspation, or with more freedom in thecentric position

In the concept of "point-centric" habitualintercuspation and the retral contact po-sition with maximum multi-point contactconcur and result in a maxillomandibularrelation so that freedom of movement isnot given in this position.

In the concept of "long-centric" no inter-locking takes place in centric occlusion,but instead a sagittal mandibular move-ment under tooth contact which allows mo-re freedom within an occlusal space witha sagittal extension of approximately 0.2 –0.8 mm (Dawson) with point-area support.In the concept of “freedom in centric” the

mandible is given more freedom of move-ment by means of freedom in the ante-rior/canine area within this centric occlu-sal space on both sides, also in the initialphase of tooth-guided excursion move-ments.

Our masticatory system has evolved slowlyover the millennia. Theories of occlusionhave undergone a transformation in thecourse of the last 100 years; these co-existin controversy with one another, with dif-ferent concepts all competing to attainscientific recognition.

Scientific discoveries, however, cannot beultimate truths (Popper). The sciences andthe arts have always been subjected tochallenge with regard to the dogmas theyhave established, and have thus been ob-liged to question themselves.

They have developed in the course of theirhistory from observations, experiences,experiments, concepts and critical discus-sions. Discoveries and insights are onlytemporarily certain. There is no guaranteethat they will be disproved at a later da-te. Unremitting skepticism is essential inall scientific disciplines.

Our theories of cognition must be subjec-ted to ongoing critical evaluation. If they

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Introduction

can withstand this scrutiny on a continualbasis they will gain an ever-increasing de-gree of reliability and scientific stature.

Considering the interpretation of the mea-ning of the concept of scientific stature, wemust come to the conclusion that it hasbeen significantly altered in the course ofhistory.

With Aristotle introduced to the field ofscience the inductive method of reasoningby means of experiments, and to a greatextent did not permit doubt with regardto established scientific dogmas.

The paradigm, i.e. the current scientific un-derstanding of a subject area of the age,is, however, very strongly influenced bythe individual who performs the experi-mental study and consequently sets up adogma (Kant). Secondly, the finite num-ber of experiments can have only a limi-ted significance in the finding of truth (Hu-me). A paradigm shift can take place onlywhen we make the effort to think criticallyand outside the confines of our acquiredand programmed ways of thinking, and tologically deduce our conclusions from this.

In the scientific way of thinking we shouldreturn to the critical rationalism of the Pre-Socratic philosophers, who spoke not of

an absolute truth, but placed the main em-phasis on the hypothesis itself and the for-mulation of a question. (Parmenides, He-raclitus). When asked about their knowled-ge they replied: “I do not know; I ammerely making an assumption. And if youare interested in my problem, then I amgratified at your critical doubt and subse-quent confirmation, amendment or refu-tation of my hypothesis”.In the words of Albert Einstein: “Assump-tion is more vital than knowledge. The me-re formulation of a problem is often morequintessential than its solution, which ismerely a matter of mathematical or expe-rimental dexterity. To pose new questionsand to view old problems from a new per-spective requires creative vision and cha-racterizes true progress in science”.

Our knowledge, not only in the field of me-dicine, must establish itself in the face ofongoing critical evaluation. It thereby gainsan increasing degree of reliability and un-der these premises is considered undertoday's criteria to be scientifically recog-nized. New insights may correct, or mayeven be the downfall of previous ones, asillustrated by numerous examples from allscientific disciplines. In science as well asin practice we should have learned by nowthat it is premature to regard laws as defi-nitive and universally applicable. Our per-

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Introduction

spective today is moving away from thestatic, linear and mechanical towards a wi-der, more flexible and dynamic model thatpermits what I like to call “flowing balan-ces”.

“Panta rhei – everything flows” was thequintessence of the epistemology of theGreek philosopher Heraclitus of Ephesus.This originated 2,500 years before his ti-me and is regaining a whole new signifi-cance today.

The concept of flowing balances in fact do-es not permit definitive laws as such, butat the most general principles. These pro-vide a framework which allows a certaindegree of freedom; not, however, totalfreedom, but freedom within a permittedspectrum and according to certain “rulesof the game” as it were. One must even setup the hypothesis that it is in fact not al-ways possible to set up definitive soluti-ons.

The dilemma posed by the differing oc-clusion concepts and what is expected oftheir practical implementation is illustra-ted in the following quotes. As Ramfjordsays: “Neither the point-centric nor thelong centric nor the freedom in centric con-cept is to be found in normal human den-tition. There is no scientific proof for the

assumption of canine guidance or canineprotection as the criterion for an ideal oc-clusion.”Hofmann states: “All forms of occlusion oc-cur in nature, even if according to our observations to date absolute canine gui-dance with direct disclusion is exceedinglyrare.”

This was the climate of uncertainty whichprevailed at the time I was a student ofdentistry in 1976 I came to ask myself thefollowing simple questions:

6What is the occlusion concept of natural,healthy, intact, physiologically functio-ning dentition?

6What is the occlusion concept of nature?

6 Does nature in fact use one of the exi-sting static and dynamic concepts whichhave been therapeutically postulatedto date?

I sought and found the answer in the dia-gnosis of natural, healthy, intact, physio-logically functioning and untreated, or vir-tually untreated dentition, on which I car-ried out clinical and functional analyses. Ichose particular dentitions for this purpo-se according to the following selection cri-teria:

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Introduction

6 They had to have no or virtually no ab-raded surfaces. I disregarded minimalabraded surfaces of up to 1 mm.

6 I accepted small occlusal fillings in thedepth of fissures or small anterior fil-lings which did not alter the anatomy.

6 The dentitions had to correspond, ornearly correspond, to Angle's class I.

6 The test subjects had not undergone or-thodontic treatment.

6 The test subjects had no pathologicalfunctional findings.

The questions to be asked in the diagno-sis of these dentitions were:

1. Are there always abraded surfaces in ourdentition, and are there abraded surfa-ces caused by anterior guidance – so-cal-led anterior guidance surfaces – as wor-king surfaces on the working side or ba-lancing surfaces on the balancing side?

2. Where are the contact points situated inhabitual intercuspation under lighttouch contact, and how many are there?

3. Is there a difference between the pa-tient's habitual intercuspation and a re-

laxed, comfortable, neuromuscularlyadopted centric position that is takenup by the patient himself any numberof times from the rest position of themandible in a comfortable, upright bo-dily posture without effort and withoutexternal manipulation?

The diagnostic results of these naturallyconserved dentitions share common fea-tures with theories to date. They also de-viate, however, from the therapeutic po-stulates of the classical concepts and evenentail experiences to the contrary.I would like to emphasize at this point thatI do not wish to discard the proven andestablished theories entirely, but ratherto modify and supplement these. At thesame time, however, I would also like toinvite the reader to try and think outsidethe confines of the learned and acquireddoctrines.

The application of these general princi-ples of natural dentition to any type ofprosthetic treatment has come to be called“Bio-logical Prosthetics”. Bio-logical Prost-hetics is the diagnostic principle of the oc-clusion of natural, healthy dentition. It canbe universally applied to fixed and remo-vable, partial and complete denture prost-hetics as well as implant and combinationprosthetics.

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Introduction

Knowledge – or the attainment of know -ledge – begins with the formulation of ahypothesis. “He who does not expect theunexpected shall not find it; it will remainundiscoverable and inaccessible to him.”This quotation from Democritus testifiesto the assumptive nature of humanknowledge – which affirms the necessityand calls for the courage to anticipateboldly that which we do not know, and inso doing, to prove the theories to be va-lid, and their originators to have taken theright path in the end.

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The anatomy of natural dentition Part A

1. Function and tooth mould

The answer to the first question as to whet-her abraded surfaces must always be pre-sent in our dentition must be answeredwith a definite “no”.

6 The conservation of natural toothmorphology is found in all agegroups all the way from youthfulto very elderly dentition!

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PART A

The anatomy of natural dentition

fig. 2 21-year old LJfig. 1 21-year old UJ

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Part A The anatomy of natural dentition

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fig. 3 25-year-old UJ fig. 4 30-year-old UJ

fig. 5 30-year-old UJ

fig. 7 43-year-old UJ

fig. 6 37-year-old UJ

fig. 8 70-year-old UJ

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The anatomy of natural dentition Part A

Tooth morphology is functional. Teeth ha-ve retained their form and positional re-lation to one another in order to each ful-fill their own unique task of the grippingand the processing of food for the durati-on of our entire lifetime. Intact natural den-tition observed in teeth of all ages up tovery elderly (figs. 1 to 8) shows that naturehas equipped the chewing organ in sucha way that the basic tooth morphology isphysiologically conserved and not destroy-ed. –This conservation serves the purpo-se of fulfilling, for the organism as a who-le, the tasks specific to each individualtooth. Correspondingly, each tooth has adifferent morphology according to its par-ticular function and as we shall see later,also different contact points.

The anterior teeth must be able to bite offfood and to hold it. The expression "inci-sors" refers only to a part of their function.The incisors form a functional unit with thecanines with the overall purpose of hol-ding the food while it is bitten so that weare able to tear it off using our hand. Thatis why the upper incisors have a trapezoidform, while the lower incisors are morewedge-shaped.They are not razor-sharp for the purposeof cutting, but are rather blunt. The upperincisors also have an incisal edge with aridge-like thickness. The canines are the

strongest and most sensitive biting andholding organs, and according to this pur-pose, have a corresponding crown and rootanatomy (see Part C on the modelation ofphysiological tooth forms). The evolutionary development of theteeth has resulted in optimized functionalmorphology which serves the purpose ofthe intake and the processing of food. Af-ter the biting off and/or the intake of food,the food bolus is conveyed to the poste-rior area via the premolars with the aid ofthe lips, cheek and tongue. The shape ofthe first premolars reflects their functionalmorphology as a transitional function bet-ween the initial gripping and the subse-quent processing of the food. Thus the firstupper premolars still display a pronoun-ced buccal cusp which supports the hol-ding function of the canine for the purpo-se of biting off hard and tough food that isbrought into this area. The second premo-lars and the molars have the task of pro-cessing the food. Their functions too arelikewise reflected in their morphology,which I shall explain in detail in Part 2, "TheModelation of Physiological Tooth Forms".

The food is held, rotated, turned over, andmoved from one side of the mouth to theother, covered in saliva and processed toa bolus on the narrow corridor of the row ofteeth by means of the tongue and the

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Part A The anatomy of natural dentition

cheeks and the opening and closing mo-vements of the mandible until it is finallyexpelled reflectorily from the oral cavityby the act of swallowing. Balters referred tothis as the chewing corridor. Functionallythe chewing corridors on the left and theright-hand side of the oral cavity are con-nected to one another via the tongue/palatal area within an enclosed chewingspace.

The comparison of the anterior tooth andthe occlusal surface morphology of natu-rally conserved dentition show that the re-lief design is characterized by a high de-gree of individuality.The morphology of natural tooth mouldsvaries from delicate and intricate to clearand simple structures. Nevertheless thetypically recurring characteristic of eachtooth can be recognized. Furthermore, theteeth of the left and right quadrants arenot entirely symmetrical – in the same wayas our face, and in fact the whole humanbody is not exactly symmetrical. We needto break free from the postulate of absolu-te symmetry and complete harmony withstandardized, waxed-up occlusal surfaces.Nature itself is our model – no less – andit makes no sense whatsoever to try to al-ter and improve on nature’s example.Tooth morphology remains unchanged foryears and decades in its genetically deter-

mined, pre-eruptive form even after erup-tion from deciduous to permanent denti-tion (figs. 1 to 8).

6 The physiological activities ofswallowing, chewing and speechdo not lead to loss of tooth mor-phology.

As dentition ages, the teeth will certainlyshow signs of use, but under physiologi-cal conditions it will never undergo the de-struction and loss of the occlusal surfacerelief of the posterior or anterior toothmoulds, but its morphology will always beconserved.

6 Physiology conserves natural toothmorphology.

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The anatomy of natural dentition Part A

2. The physiological centric

The distribution of the contact points in na-tural, healthy, physiologically functioningdentition deviates from the classical, staticocclusion concepts – both in terms of thenumber and the position of the contacts.

In healthy dentition the patient’s habitualbite (habitual intercuspation) correspondsto a neuromuscularly guided and adoptedcentric position. This position is taken upby the patient himself again and again fromthe rest position of the mandible effortless-ly and without external manipulation in a re-laxed, comfortable upright bodily posture.

This contact is called the physiological cen-tric.

6 The physiological centric of natural dentitionTaking a leaf out of nature’s book –the principles of natural dentition:

1. Virtually homogeneous and simultane-ous points of contact in the posteriorarea showing a typical distribution withan individual range of variation fromtooth to tooth and patient to patient.

2. An average of ten contact points is to befound per quadrant in the posterior arearanging from 6 – 14 contact points.

3. The contact points are situated mainlyon the working cusps – on the lingualcusps in the upper jaw and the buccalcusps in the lower jaw. They are locatedmainly at different heights on the innerslopes, but also centrally on the highestridges.

4. There are fewer marginal ridge contacts.5. There are fewer contacts on the inner

slopes of the non-working cusps – the-se are located on the inner slopes of thebuccal cusps in the upper jaw and theinner slopes of the lingual cusps in thelower jaw.

6. The anteriors can all, or only partiallyhave contact, virtually homogeneouslyand simultaneously with the posteriors.Anterior contacts tend to be light touchcontacts with an average of five contacts.

These six characteristic features representgeneral principles of natural dentition.These leaves taken from nature's book, ho-wever, are not static laws but more resem-ble general principles which leave scopefor individual variation – and which are al-ways to be understood as flowing balan-ces.

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