influence of length and diameter of implants associated ... of length and diameter of...

Influence of Length and Diameter ofImplants Associated With Distal Extension

Removable Partial DenturesFellippo Ramos Verri, DDS, MSc,* Eduardo Piza Pellizzer, DDS, PhD,† Eduardo Passos Rocha, DDS, PhD,†

and Joao Antonio Pereira, PhD‡

In spite of the technological devel-opment of current dentistry, teethcontinue to be lost. Of the prob-

lems resulting from these losses,mainly those related to posterior man-dibular losses, these have been thereason for much research and will prob-ably continue to be so during the nextfew decades.1 Due to the dual nature ofsupport, dental and mucous, with differ-ent resilience, this rehabilitation iscomplex, as there is movement of thebase when it is rehabilitated with aclass I conventional removable partialprosthesis. There are suggestions forbalancing the loads distributed amongthe tooth and mucosa of the residualridge, such as making functionalmolding, using a wide prosthetic basewithin the physiological limits of eachpatient, periodic re-basing of the pros-thetic seat, indications of clasps or at-tachments, splinting of distal supports,among others.2–7 All these resourcesseek a common objective: to distributethe loads as axially as possible on thesupporting tooth, which, theoretically,would distribute the loads originatedat occlusion to the supporting struc-tures in the most physiological anduniform manner.8

Implantology has made it possiblefor osseointegrated implants to be used in partially edentulous patients.

However, not all patients have suffi-cient bone height in the posteriorregion, either because of bone absorp-tion resulting from tooth losses, oreven by anatomical limitations, likethe position of the inferior alveolarnerve or inferior wall of the maxillarysinus.9–11 Furthermore, frequently, pa-tients are disinclined to submit them-selves to invasive surgeries prior to theplacement of the implants. These in-

clude bone-grafting procedures in theregion, sinus lift, or even nerve later-alization of the inferior alveolar nerve,which may also result in permanentparesthesia of the inferior alveolarnerve. Added to this there is still thefinancial factor, as any interventionof this kind increases the cost of theproposed treatment. For these pa-tients, another solution should beproposed. One option would be theassociation of the distal extension

*Student, Doctorate Course at the Dentistry Faculty ofAracatuba, UNESP, Aracatuba, Sao Paulo, Brazil.†Assistant Professor Doctor of the Dental Materials andProsthesis Department at the Dentistry Faculty of Aracatuba-UNESP, Aracatuba, Sao Paulo, Brazil.‡Professor of the Mechanical Engineering Department of theIlha Solteira Engineering Faculty-UNESP, Ilha Solteira, SaoPaulo, Brazil.

ISSN 1056-6163/07/01603-270Implant DentistryVolume 16 • Number 3Copyright © 2007 by Lippincott Williams & Wilkins

DOI: 10.1097/ID.0b013e31805007aa

Purpose: The aim of this studywas to evaluate the influence of thelength and diameter of the implantincorporated under the saddle of adistal-extension removable partialdenture, acting as support.

Materials and Methods: Six hemi-mandibular models were made with thepresence of left inferior cuspid and firstbicuspid, with the following differences:model A, without removable partialdenture; model B, removable partialdenture only; model C, removablepartial denture and implant of3.75 � x mm; model D, removablepartial denture and implant of3.75 � x3 mm; model E, removablepartial denture and implant of 5 � xmm; and model F, removable partialdenture and implant of 5 � x3 mm.These models were designed with theaid of AutoCAD 2000 (Autodesk, Inc.,San Rafael, CA) and processed forfinite element analysis by ANSYS 5.4(Swanson Analysis Systems, Houston,PA). The loads applied were 50 Nvertical on each cuspid point.

Results: It was noted that thepresence of the removable partial den-ture overloaded the supporting toothand other structures. The introductionof the implant reduced tensions,mainly at the extremities of the eden-tulous edge. Both the length and diam-eter tended to reduce tensions as theirdimensions increased.

Conclusions: Increasing thelength of the implant had a great in-fluence on the decrease of displace-ment and von Mises tension values.Increasing the diameter of the implanthad a great influence on the decreaseof von Mises tension values, but didnot influence the displacement values.According to the results of this study,it is a good choice to use the greaterand larger implant possible in the as-sociation between implant and distalextension removable partial denture.(Implant Dent 2007;16:270–280)Key Words: removable partial den-ture, dental implant, biomechanics,finite element analysis

270 EVALUATION OF THE INFLUENCE OF THE LENGTH AND DIAMETER OF THE OSSEOINTEGRATED IMPLANT

removable partial denture with os-seointegrated implants, which maynot only attenuate the problem of thebase movement but also reduce thecost of the treatment.1,12,13

Variations of the implant geome-try, more precisely the length and di-ameter, have also been the subject ofresearch.14 –17 The overload on im-plants acting only as partial support oreven as retention of removable partialdentures would be less than that onimplants acting as the pillar of fixedprostheses; shorter implants could beefficient.13 Furthermore, in the litera-ture, the benefits brought about by theuse of wide diameter implants is al-ready evident, as opposed to the im-plants of conventional diameter.15,18,19

This being so, the aim of this studywas to check the behavior of implantsof different sizes and diameters thatare to be used as support in associationwith a mandibular distal extension re-movable partial denture, as measuredby the bi-dimensional finite elementsanalysis.

MATERIALS AND METHODS

The methodology used was basedon the study of Darbar et al20 andmodified by Rocha et al.1 For thestudy, 6 mandibular models weremade, simulating a partially edentu-lous hemi-arch, with the presence ofthe left cuspid and first bicuspid only.The characteristics of the remainingteeth, support structures, and artificialteeth in the models that have themwere standardized in all of the models.The configuration of the models is il-lustrated in Table 1.

To make the models, the assisteddrawing program AutoCAD 2000(Autodesk, Inc., San Rafael, CA) wasused. This program is widely used inthe area of engineering and graphiccomputation. It allows drawings with

dimensions very close to reality to bemade. The dimensions of the elementsindividualized in the models, such asimplant, mucosa, teeth, alveolar bone,removable partial denture metal frame-work, among others, could thus be re-produced in the most faithful mannerpossible. The dimensions were all ex-tracted from articles published in thedental literature.1,21,22

The implant system used was theBrånemark System (Nobel Biocare,Goteborg, Sweden). In the models thathave an implant, a healing abutmentcompatible with the implant diameterwas put in, with a height of 2 mm at alltimes. The 3.75-mm diameter im-plants were of the standard type, andthe 5.00-mm implants were of theMKIII type. In all the situations tested,the implants acted only as the supportelement.

After creating the models inAutoCAD, they were exported to thefinite element program, ANSYS 5.4(Swanson Analysis Systems, Houston,PA) for analysis of the von Mises dis-placement and tension maps. The ele-ment chosen for generating the meshwas the solid bi-dimensional PLANE2, which allowed an appropriate re-finement of the mesh, mainly in placesof greatest interest, like the threads ofthe implant and the bone adjacent to it.An example of the mesh generated ispresented in Fig. 1, which in this caseillustrates model E.

Next, the mechanical properties ofthe materials of each structure wereincorporated according to the valuesalso established in the literature.20,23–26

To simulate symmetry in the model,the entire right and left side were fixedin the direction x, to the horizontal.The base of the model was fixed in the2 directions, x and y. Thus, the move-ment of intrusion was not blocked inany structure to be analyzed; the cor-

tical bone of the base being like thetrue support of the entire model. Thestructures were simulated homoge-neously, isotropic, and linearly elastic,and the models were considered in aplane state of tensions.

The loading of the forces wasdone on the points of the cuspid of thenatural and simulated artificial teeth,in the models that had them, distribut-ing a total of 50 N on each cuspidpoint, divided into 5 points of 10 N,which represents a total of 100 N inmodel A and 400 N in the other models.

RESULTS

The general displacement maps il-lustrate the tendency for movement ofthe systems after the application of thesimulated forces, generating values inmillimeters. From the analysis of thegeneral displacement maps, it waspossible to state that the introductionof the removable prosthesis provided amovement of the structures that sup-ported it, increasing the tendency formovement of the support tooth by ap-proximately 2 times when the apicalregion is used as parameter. The intro-duction of the implant in models C, D,E, and F do not show significant dif-ferences in the apical region of thesupport tooth, in spite of reduction ob-served in the values of displacementmaps. However, in the distal region ofthe models with implant, there was areduction in the tendency to move,mainly distal to the implant.

The increase in length influencedthe tendency to move, decreasing thevalues of the displacement map,mainly from the median region to theimplant and distally to this. The in-crease in diameter, in turn, showed asimilar result only when this in-creased diameter was analyzed in the13.0-mm long implants. In the7.0-mm implants, the increased di-

Table 1. Configuration of the Models Made for the Study. All Models Representing a Hemi-Mandibular Section, With AllStructures Standardized

Model

A Presence of teeth 33 and 34, without RPD and without implantB Presence of teeth 33 and 34, with RPD and without implantC Presence of teeth 33 and 34, with RPD and with associated implant of 3.75 � 7.00 mmD Presence of teeth 33 and 34, with RPD and with associated implant of 3.75 � 13.00 mmE Presence of teeth 33 and 34, with RPD and with associated implant of 5.00 � 7.00 mmF Presence of teeth 33 and 34, with RPD and with associated implant of 5.00 � 13.00 mm

RPD indicates removable partial denture.

IMPLANT DENTISTRY / VOLUME 16, NUMBER 3 2007 271

ameter did not lead to an increase inthe displacement map values. Figs.2–7 show the displacement maps ofall the models.

The general displacement maps il-lustrate the von Mises tensions found inthe models after the application offorces, generating values in MPa. Fromanalysis of these maps, it was possible tonote that some structures presented witha greater concentration of tension. How-ever, in order to obtain better visualiza-tion and make a better comparisonamong the models, the main structureswere individualized. Table 2 synthesizesthe maximum and minimum values foreach model and for each structure ana-lyzed individually.

From the comparison of the corti-cal bone between models A and B, it ispossible to prove that the cortical boneof the cortical alveolar bone of thesupport tooth suffers an overload withthe introduction of the removable par-

tial denture. This increase in the ten-sion levels also occurs in the toothadjacent to the support tooth, althoughon a lesser scale. Another area thatsuffers an increase in tension levels isthat of the edentulous edge, where theremovable partial denture comes intocontact with the mucosa of the eden-tulous edge.

The introduction of the osseointe-grated implant, acting as support forthe removable partial denture, showedsignificant changes in the corticalbone, mainly in the region of the eden-tulous edge, which showed a decreasein the tension levels in the region closeand distally to the implant in all of themodels with the associated implant.The cortical alveolar bone did not showa similar relation. In the wide diameterimplants, the increase in length had littleinfluence, slightly reducing the tensionsfound between the support tooth andosseointegrated implant.

In the spongy bone, the changeswere more visible. Four different areasmay be noted: the apex region of thenatural teeth; the edentulous ridge re-gion between the support tooth andosseointegrated implant, when this ispresent; the region adjacent to the im-plant neck; and the apex region of theimplant.

When models A and B are com-pared, it is clear that the introductionof the removable partial denture in-creases the tension levels in all theaforementioned areas, and the distalsupport tooth, which receives the sup-port of the removable partial denture,is more overloaded than the other nat-ural tooth simulated; this, by over 2times (Figs. 2 and 3).

In a direct comparison betweenmodel B and the other models thatreceived the osseointegrated implant,it may be noted that the apical regionof the implant suffers an overload, andthe region of the apexes of the simu-lated natural teeth do not undergomuch change. However, in the area ofthe edentulous ridge between the sup-port tooth and implant, and distal tothe implant, there is a reduction intension levels. Figs. 4–6 illustrate thespongy bone of models C, D, and F,respectively.

When comparing the implants ofdifferent lengths, it is noted that theonly areas that undergo alteration arethe apex of the implant. The increasein length of implant tends to raise thetensions in the apex, and the region ofthe neck and of the first threads of theimplant, which tend toward a decreaseof the tension levels with an increasein the implant length. The region be-tween the support tooth and implantalso undergoes a decrease in tensions,although slight, when the implantlength is increased (Figs. 4 and 5). Theincrease in the implant diameter, inturn, presents differences only in theregion of the implant apex and tendstoward a reduction in the tension lev-els in this area. The distribution oftensions was shown to be similar forthe periodontal connection in all themodels analyzed, not showing signif-icant alterations among any of themodels analyzed (Figs. 5 and 6).

Once again, the introduction ofthe removable partial denture gener-ated an increase in the tension levels

Fig. 1. Model E after generating the finite elements mesh.Fig. 2. Tension map of the spongy bone of model A.Fig. 3. Tension map of the spongy bone of model B.Fig. 4. Tension map of the spongy bone of model C.Fig. 5. Tension map of the spongy bone of model D.Fig. 6. Tension map of the spongy bone of model F.


observed in the fibromucous of thefree end when models A and B werecompared, being double the value insome areas. The introduction of theimplant acting as support had a similarresult to the ones found for the corticalbone, showing a relief in the areasadjacent to the implant and distal to it,when model B is compared to the mod-els that have an associated implant. Boththe increase in length and diameter re-duced the concentration of tensions.Figs. 7 and 8 illustrate the distribution oftensions in the fibromucous of the mod-els B and F, respectively.

All implants presented a similardistribution of tensions, although thetension levels were different. On theleft side of all the implants, as well asin the region of the first internalthreads, are the most overloaded areas,and the values are higher as the im-plant length is increased. With theincrease in diameter, the inverse sit-uation occurs, and a reduction in thetension levels is seen.

DISCUSSION

From analysis of the displacementmaps obtained in this study, in agree-ment with other studies, it was possi-ble to show that the introduction of aremovable partial denture in a distalextension generated a greater displace-ment of the support tissues.2–7 By sim-ilar methodology, Rocha et al1 found

almost twice the movement when aremovable partial denture was associ-ated with a distal extension mandibu-lar model. As the degree of implantmovement is much smaller than thedegree of movement that the periodon-tal membrane allows the tooth, theidea of using an implant as a way tominimize the vertical movement of theprosthetic base in the residual ridgewas shown to be effective. These re-sults are observed even in associationwith a short implant of 7.00 mm,which is in agreement with the sug-gestions made by Keltjens et al.13

However, as the displacement mapsshow only a tendency toward defor-mation, it is not possible to affirm thatthe implant also has the function ofreducing stress on the natural tooth.Therefore, the von Mises tensionanalysis is carried out, which showsinteresting data in connection withthe association.

Some studies suggest that even ashort implant could provide supportfor a distal extension removable par-tial denture, and it is expected that itwould be less overloaded.12,13,27 Onlylongitudinal studies will be able toverify this affirmation. From the re-sults of this study, the introduction ofa 3.75 � 7.00-mm implant, which wasthe smallest one used, did not showvery high stress levels at the apex ofthe support tooth. When comparedwith the levels found in the modelswith only a removable partial dentureand without removable partial denture,the results were similar.

In relation to the tension maps, theresults also showed that the introduc-tion of the removable partial dentureoverloaded the distal support tooth.This fact is in agreement with the stud-ies related in the literature, which em-phasized the problems generated indistal support teeth by this type ofprosthesis.5,8

From the methodology of thisstudy, the closest studies and thosethat served as a parameter for compar-ison are those of Craig and Farah8 andRocha et al,1 who also used the bi-dimensional finite element analysis. Inspite of Craig and Farah8 not havingsimulated a distal extension withoutthe presence of the removable partialdenture, they found that under theapplication of vertical load concen-

trated in the region of occlusal restand marginal crest of the supporttooth, there was a decrease in tensionvalues observed at the alveolar edgewhen compared to the values ob-tained by the application of verticalloads on artificial teeth of the remov-able partial denture. Rocha et al,1

also using vertical load, concludedthat the presence of the removable par-tial denture overloaded the supportstructures more than the model with-out removable partial denture. In thisstudy, the introduction of the distalextension removable partial denture inthe model analyzed provided a con-centration of tensions at the alveolaredge distal to the support tooth. Thiswas not observed in the model with-out the prosthesis, and it could benoted both in the general and indi-vidualized models. Moments offorce are responsible for these in-creases in tension, and probably thelonger the power arm of this levercreated with the fulcrum on the mostposterior tooth is, the higher the val-ues will be.8 Even more complex isthe rehabilitation with distal exten-sion removable partial denture, whenthe edentulous area is long and thebone implant of the support teeth iscompromised.

The use of osseointegrated im-plants is no more than an attempt toeliminate the lever problem generatedin the cases of distal extension remov-able partial denture. Theoretically,there would be a transformation of aKennedy class I tooth-mucous-supported prosthesis into a Kennedyclass III tooth-implant-supported, oreven retained one, should a retentionelement be incorporated to the im-plant.12 In spite of the few studies fo-cusing on the association of removablepartial denture and osseointegratedimplants,1 some consider it to be apromising alternative in relation toconventional distal extension remov-able partial dentures.1,13 Furthermore,some very successful clinical cases inconnection with the association havebeen published.10–13,28,29

The main factor to be consideredis the difficulty of finding a bone heightand thickness in the posterior regionsufficient for placing osseointegratedimplants to support a fixed partial pros-thesis without the need for sinus lift

Fig. 7. Tension map of the fibromucous ofmodel B.Fig. 8. Tension map of the fibromucous ofmodel F.


surgery, nerve lateralization of the man-dibular nerve or bone graft.10,11,27 Somealternative solutions have been sug-gested in the literature.10,11 In this con-text, another alternative is to place animplant in the distal extension to supporta removable partial denture, whose fo-cus was the theme of this study, varyingthe length of the implant at values veryclose to the maximum and minimumlimits of length for the retromolar re-gion: 13.00 and 7.00 mm, respectively.

In this study, the introduction ofan osseointegrated implant to supporta removable partial denture showedalterations in the form of von Misesgeneral distribution of tensions,mainly overloading the osseointe-grated implant, under analysis of thegeneral tension map. It is reasonableto expect that the tension in the otherstructures would be reduced, as a largeamount of the deformation energy isconsumed by the implant, involving areduction of the stress distributed tothe rest of the set.30 The benefits of theassociation, like the decrease of ten-sions on the fibromucous distal to thesupport tooth, were the results of thisand other studies.1 Both the corticalbone and spongy bone showed reduc-

tion of tensions after the introductionof the implant at the distal extension.It is, however, difficult to predict towhat extent the bone structure is ben-efited by this reduction in tension,since even today, it is not known whatthe ideal amount of stress on the boneis so that bone atrophy does not oc-cur.17,30 It is, however, predictable thatas lower amounts of tension will betransmitted to the fibromucous and al-veolar bone, chewing efficiency andpatient comfort will be enhanced,since the clinically limiting factor for aremovable partial denture user is stillthe problem resulting from the traumato the oral mucosa caused by the pros-thetic base. At least an implant at thedistal extension may help to stabilizethe appliance. Furthermore, just asfound in other studies,1 tension levelsobserved in the cortical bone aroundthe implant were not so high, remain-ing below the values found at the apexof natural teeth, which suggests thefeasibility of clinical application, clin-ically speaking, when reabsorption oc-curs around the implant, it starts in theregion of the crest of the bone after theapplication of occlusal loads and, gen-erally, by overload.1,27 Therefore, in

spite of the benefits pointed out, thepotential function of an implant usedin this way of reducing stress on thenatural support tooth does not seem tooccur, at least on the vertical loadsunder the conditions of this study, be-ing in disagreement with the study ofKeltjens et al.13

Some considerations with regardto the implant geometry may also bemade. Generally, a protocol to be fol-lowed in oral rehabilitation is the useof the largest amount of bone avail-able, which means the use of the long-est possible implant and by a largebone surface area, which would deter-mine a more favorable distribution ofstress.27 Short implants present greaterfailure rates in any situation.31 Pro-spective studies have also indicatedthat short implants fail more than longones, mainly those of standard diame-ter, and reinforce this theory.18,19 Somestudies showed that from the point ofview of stress distribution, other fac-tors may be more important than theimplant length, like its inclination ormandibular flexion.32,33 However, in thisstudy, where the loads applied werestrictly vertical, by bi-dimensional finiteelement analysis, the implant length had

Table 2. Maximum and Minimum Values of Displacement and von Mises Tension

Model A Model B Model C Model D Model E Model F

General displacement mapsMin 0 0 0 0 0 0Max 0.069061 0.131717 0.127701 0.12132 0.127398 0.121088

General tension mapsMin 0.02187 0.183337 0.643 E-03 0.184 E-03 0.01067 0.005166Max 41.395 103.389 353.538 407.082 182.165 265.306

Spongy boneMin 0.02187 1.167 0.581421 0.259383 0.384346 0.241532Max 8.641 18.025 19.633 21.736 17.167 18.854

Cortical boneMin 0.024989 1.197 1.596 1.382 1.429 0.984353Max 30.868 103.389 76.999 97.727 76.823 68.938

FibromucousMin 0.026799 0.519598 0.308152 0.446818 0.197654 0.223828Max 16.192 21.017 25.956 20.848 21.048 20.903

Periodontal membraneMin 0.641254 0.46601 0.414452 0.393143 0.418845 0.391254Max 10.36 29.007 31.804 31.213 34.989 30.926

CoCr frameworkMin — 9.431 5.924 4.065 6.3 3.386Max — 95.973 110.623 114.675 97.517 114.292

Implant (Ti)Min — — 0.643 E-03 0.184 E-03 0.01067 0.005166Max — — 278.062 372.82 182.165 265.306

The displacement values were obtained in millimeters, and the tension values were obtained in MPa. The blank cells indicate that this structure does not exist in the model considered.

Max indicates maximum; Min, minimum.


a direct influence on the stress transmit-ted to some structures. The fibromu-cous, cortical bone, and spongy bone allshowed a reduction in tensions as theimplant length was increased. The onlypoint where the length did not help toreduce tensions was at the apex of theimplant, which does not invalidate thebenefits generated by an increase of im-plant length because when bone loss oc-curs around the implants, the first area isgenerally around the implant neck.34

Furthermore, the stress levels found inspongy bone apical to the implant aresimilar to the levels found at the apex ofthe support tooth. The fixation of thebase of the models to allow the finiteelement analysis could influence the re-sult, since the proximity of the corticalbone at the base of the models may havelimited the load absorption of thespongy bone.

The advantages of using wide di-ameter implants are expounded in theliterature.1,15,16,18,19,32,34 –36 Prospectivestudies also affirm that using a well-defined surgical protocol, no large di-ameter implant was lost during 10years of control.18 Himmlova et al34

affirmed that the implant length doesnot have as much influence as the di-ameter with regard to stress distribu-tion. The results of this study are inagreement with all of these studies, asit also found advantages with the useof wide diameter implants in the dis-tribution of the stress transmitted tosupport structures, although the lengthalso had a significant influence on theresults. The increased diameter alsoreduced the tension values observedinternally in the implant itself andhealing abutment. It is not easy to pre-dict a reasonable limit for implantdimensions, but certainly, withinphysiological limits, to use the longestand widest implant would be very in-teresting from the point of view ofstress distribution. Both the length anddiameter influenced stress distributionin a positive manner, favoring the fi-bromucous, cortical bone distal to thesupport tooth, and the spongy bone,mainly in the area of the edentulousridge and at the implant neck. How-ever, from the results pointed outabove, even an implant of 3.75 �7.00-mm length, acting as support fora distal extension removable partialdenture, has shown improvements in

stress distribution and does not indi-cate potential risks to rehabilitation.

The internal distribution of ten-sions in implants showed that the leftside, both of the implant and healingabutment, were shown to be moreoverloaded, in addition to the first in-ternal threads that also received con-siderable tensions. This shows that theresulting loads are not parallel to theimplant but inclined due to the flexionundergone by the removable partialdenture framework. As this result isinclined, it may justify the findings ofTuncelli et al17 that show that angledimplants have advantages over stan-dard implants with regard to resistingthe damaging effects of horizontalforces. Further studies varying the in-clination of the load applied may pro-vide more data for this discussion.

The finite element analysis is amathematical method with a pro-grammed behavior and is a goodsource of predicting the reaction of thebone to the implant; but, at the sametime, it is necessary to have reliabledata on the mechanical properties ofthe human cortical and spongy bone,which may help to explain the incon-sistencies existent between the theo-retical and practical aspects of oralimplantology.37 Its use in the dentistryarea has increased greatly over the lastfew decades.38 From the results ob-tained in this study, the method wasshown to be efficient, translating intoresults compatible with clinical realityand in accordance with the specializedliterature published on the subject.There are many difficulties in carryingout the method, mainly with regard tothe interpretation of the systems ofloads generated by this type of appa-ratus, which must be programmed inthe computer, but the final result,without doubt, encourages furtherstudies and also controlled clinicalcases to be carried out in order toprove in vivo the results obtained invitro. Three-dimensional analysesmay provide richer details of stressdistribution and should be the objec-tive of whoever is inclined to workwith the method described.

CONCLUSIONS

By the proposed methodology, itwas possible to conclude that:

1. The increase in length of the im-plant had a great influence on thedecrease of displacement and vonMises tension values according tothe methodology of this study.

2. The increase of the diameter of theimplant had a great influence onthe decrease of von Mises tensionvalues by the methodology of thisstudy but did not influence the dis-placement values.

3. According to the results of thisstudy, it is a sound choice to use aslarge an implant as possible in theassociation of implant and remov-able partial denture.

Disclosure

Not applicable.

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Reprint requests and correspondence to:Fellippo Ramos Verri, MScRua Jose Bonifacio 1193Vila Mendonca 16.015-050Aracatuba, Sao Paulo, BrazilPhone/Fax: (18) 3636-3245E-mail: [email protected]

Abstract Translations

GERMAN / DEUTSCHAUTOR(EN): Fellippo Ramos Verri, MSc, Eduardo PizaPellizzer, PhD, Eduardo Passos Rocha, PhD, Joao AntonioPereira, PhD. Schriftverkehr: Fellippo Ramos Verri, MSc,Rua Jose Bonifacio 1193, Vila Mendonca (Zip Code) 16.015-050, Arac�atuba, Sao Paulo, Brasilien. Telefon/Fax: (18)3636-3245, eMail: [email protected] des Einflusses von Lange und Durchmesser desKnochengewebsintegrierenden Implantats in Verbindung mitherausnehmbaren Unterkieferteilprothesen des Typs I

ZUSSAMENFASSUNG: Zielsetzung: Die vorliegendeStudie zielte auf eine Beurteilung des Einflusses von Langeund Durchmesser des Implantats ab, das als Stutze unter demSattel einer distal verlangernden herausnehmbaren Teilproth-ese eingepflanzt wurde. Materialien & Methoden: 6 Halbse-itige Unterkiefermodelle wurden unter Vorhandensein des linkenunteren Eckzahns sowie des ersten vorderen Backenzahns herg-estellt, mit den Unterschieden wie nachfolgend: MA – ohne HTP;MB – nur HTP; MC – HTP und Implantat (Abmessungen3,75 � 7 mm); MD – HTP und Implantat (Abmessungen 3,75 �13 mm); ME – HTP und Implantat (Abmessungen 5 � 7 mm);


MF – HTP und Implantat (Abmessungen 5 � 13 mm); DieseModelle wurden unter Zuhilfenahme von AutoCAD 2000 er-stellt und zur abschließenden Elementanalyse mittels Ansys 5.4weiterverarbeitet. Es wurden vertikale Krafte von 50 N auf jedenEckzahnpunkt aufgebracht. Ergebnisse: Es wurde festgestellt,dass die Existenz einer HTP den Stutzzahn sowie die anderenStutzstrukturen uberlastete. Wurde ein Implantat zusatzlich miteingesetzt, verringerten sich die Spannungen. Dies betraf haupt-sachlich die außeren Enden des zahnlosen Randes. Mit Zu-nahme der Ausmessungen schienen sowohl Lange als auchDurchmesser zu einer Verringerung der Spannungen beizutra-gen. Schlussfolgerungen: Die Erhohung der Lange einesImplantats hatte großen Einfluss auf die Verringerung einermoglichen Zahnluxation und der von Mises-Spannungswerte.Die Erhohung des Durchmessers des Implantats spielte einegroße Rolle hinsichtlich der Verringerung der von Mises-Spannungswerte, beeinflusste dabei aber die Zahnluxation-swerte nicht. Aufgrund der Ergebnisse dieser Studie stellt sichbei Verbindung von Implantaten mit einer distal verlangerndenherausnehmbaren Teilprothese das Implantat mit dem großtmoglichen Durchmesser und der großt moglichen Lange als diebeste Wahl heraus.

SCHLUSSELWORTER: Herausnehmbare Teilprothese,Zahnimplantat, Biomechanik; finite Elementanalyse.

SPANISH / ESPAÑOLAUTOR(ES): Fellippo Ramos Verri, MSc, Eduardo PizaPellizzer, PhD, Eduardo Passos Rocha, PhD, Joao AntonioPereira, PhD. Correspondencia a: Fellippo Ramos Verri,MSc, Rua Jose Bonifacio 1193, Vila Mendonca (Zip Code)16.015-050, Arac�atuba, Sao Paulo, Brasil. Telefono/Fax (18)3636-3245, Correo electronico: [email protected] de la influencia de la longitud y el diametro delimplante oseointegrado en una dentadura parcial removible(RPD) mandibular clase I

ABSTRACTO: Proposito: El objetivo de este estudio fueevaluar la influencia de la longitud y el diametro del implanteincorporado bajo la silla de una dentadura parcial removiblecon extension distal, actuando como soporte. Materiales yMetodos: Se fabricaron 6 modelos hemimandibulares con lapresencia del canino inferior izquierdo y el primer premolar,con las siguientes diferencias: MA – sin RPD; MB – RPDsolamente; MC – RPD e implante de 3,75 � 7 mm; MD –RPD e implante de 3,75 � 13 mm; ME – RPD e implante de5 � 7 mm; MF – RPD e implante de 5 � 13 mm. Estosmodelos fueron disenados con la ayuda de AutoCAD 2000 yprocesados con el analisis finito de elementos de Ansys 5.4.Las cargas aplicadas fueron verticales de 50 N en cada puntodel canino. Resultados: Se noto que la presencia del RPDsobrecargo al diente de apoyo y otras estructuras. La intro-duccion del implante redujo las tensiones, principalmente enlas extremidades del borde edentuloso. Ambas, la longitud yel diametro tendieron a reducir las tensiones, a medida queaumentaron sus dimensiones. Conclusiones: El incremento

de la longitud del implante tuvo mucha influencia en lareduccion del desplazamiento y los valores de tension vonMises; el aumento del diametro del implante tuvo muchainfluencia en la reduccion de los valores de tension vonMises, pero no influenciaron a los valores de desplazamiento.Segun los resultados de este estudio, es una buena opcionusar el implante mas grande y mas largo posible en la aso-ciacion entre el implante y la dentadura parcial removible conextension distal.

PALABRAS CLAVES: Dentadura parcial removible, im-plante dental, biomecanica, analisis finito de elementos

PORTUGUESE / PORTUGUÊSAUTOR(ES): Fellippo Ramos Verri, Mestre em Ciencia,Eduardo Piza Pellizzer, PhD, Eduardo Passos Rocha, PhD,Joao Antonio Pereira, PhD. Correspondencia para: FellippoRamos Verri, MSc, Rua Jose Bonifacio 1193, Vila Mendonca(Zip Code) 16.015-050, Arac�atuba, Sao Paulo, Brazil. Tele-fone/Fax (18) 3636-3245, e-mail: [email protected] da Influencia da Extensao e Diametro do Im-plante Osseointegrado Associado com RPD MandibularClasse I

RESUMO: Objetivo: O objetivo deste estudo era avaliar ainfluencia da extensao e diametro do implante incorporadosob a sela de uma dentadura parcial removıvel de extensaodistal, atuando como suporte. Materiais & Metodos: 6 mod-elos 6 hemi-mandibulares foram feitos com a presenca decuspide inferior esquerda e primeira bicuspide, com asseguintes diferencas: MA – sem RPD; MB – RPD apenas;MC – RPD e implante de 3,75 � 7 mm; MD – RPD eimplante de 3,75 � 13 mm; ME – RPD e implante de 5 � 7mm; MF – RPD e implante de 5 � 13 mm. Esses modelosforam projetados com o auxılio de AutoCAD 2000 e proces-sados para a analise de elemento finito por Ansys 5.4. Ascargas aplicadas eram verticais de 50 N em cada ponto dacuspide. Resultados: Observou-se que a presenca do RPDcarregou o dente de apoio e outras estruturas. A introducao doimplante reduziu as tensoes, principalmente nas extremidadesda borda desdentada. Tanto a extensao quanto o diametrotenderam a reduzir as tensoes, a medida que suas dimensoesaumentavam. Conclusoes: O levantamento da extensao doimplante teve grande influencia na diminuicao do desloca-mento e valores de tensao von Mises, mas nao influenciou osvalores de deslocamento; pelos resultados deste estudo, euma boa escolha usar o maior e mais largo implante possıvelna associacao entre o implante e a dentadura parcial remov-ıvel de extensao distal.

PALAVRAS-CHAVE: Dentadura parcial removıvel, im-plante dentario, biomecanica, analise de elementos finitos

RUSSIAN /��: Fellippo Ramos Verri, �� , Eduardo Piza Pellizzer, �� , Edu-


ardo Passos Rocha, �� , João AntônioPereira, �� . �� : Fellippo RamosVerri, MSc, Rua José Bonifácio 1193, Vila Mendonça (ZipCode) 16.015–050, Araçatuba, São Paulo, Brazil. ��/��: (18) 3636–3245, �� . ��:[email protected]�� ,�� RPD �� I

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