New theoretical model to measure pressure produced during impression procedure for complete denturesVisual inspection of impression material flow

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  • d e n t a l m a t e r i a l s 2 9 ( 2 0 1 3 ) 530534

    Available online at www.sciencedirect.com

    jo ur n al homep age : w ww.int l .e lsev ierhea l th .com/ journa ls /dema

    New theoretical model to measure pressure producedduring impression procedure for complete denturesVisualinspe

    G. Nishia Occlusion b DepartmenShikata-choc DepartmenPharmaceut

    a r t i c

    Article histor

    Received 24

    Received in

    6 November

    Accepted 13

    Keywords:

    Impression

    Pressure

    Complete d

    CorresponKitaku, Oka

    E-mail a0109-5641/$http://dx.doction of impression material ow

    gawaa,, Y. Maruoa, M. Irieb, M. Okac, Y. Tamadaa, S. Minagi c

    and Removable Prosthodontics, Okayama University Hospital, 2-5-1, Shikata-cho, Okayama 700-8525, Japant of Biomaterials, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1,

    , Kitaku, Okayama City 700-8525, Japant of Occlusal and Oral Functional Rehabilitation, Okayama University Graduate School of Medicine, Dentistry andical Sciences, 2-5-1, Shikata-cho, Kitaku, Okayama City 700-8525, Japan

    l e i n f o

    y:

    July 2012

    revised form

    2012

    February 2013

    enture

    a b s t r a c t

    Objective. A theoretical model, based on uid dynamics, was developed to measure impres-

    sion pressure. The purpose of this study was to evaluate the validity of this theoretical model

    by comparing its theoretical analysis against actual pressure measurements conducted

    using an impression tray and edentulous oral mucosa analog embedded with pressure

    sensors.

    Methods. In the theoretical model, a hollow tube was mounted onto an impression tray

    by penetrating through the tray. When force was applied to the tray, pressure was pro-

    duced which then caused the impression material to ow into the hollow tube. Length of

    impression material which owed into tube was denoted as l. In the calculation formula

    for theoretical model, pressure impulse I was expressed as a function of impression ow

    length l. For actual pressure measurements, four electric pressure sensors were embedded

    in an experimental edentulous arch. To visually observe and measure length of impression

    material ow, four transparent silicon tubes were mounted vertically at different positions

    on tray. During tray seating, impression material owed into tubes and pressure which

    caused material ow movement was measured by the embedded sensor at each tubes

    position.

    Results. Based on actual pressure measurements under one experimental condition,

    regression analysis of pressure data acquired from electric sensors yielded the formula,

    Y = 0.056X2 + 0.124X. Based on theoretical analysis using a particular viscosity value, the

    numerical formula yielded was Y = 0.057X2, which resembled that of the regression formula.

    Signicance. Theoretical model presented in this paper augured well for clinical application

    as an easy and economical means to examine magnitude and distribution of impression

    pressure by measuring lengths of impression material ow in tubes xed to impression

    tray.

    2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

    ding author at: Occlusion and Removable Prosthodontics, Okayama University Hospital, 2-5-1, Shikata-cho,yama City 700-8525, Japan. Tel.: +81 86 235 6687; fax: +81 86 235 6689.ddress: goro@md.okayama-u.ac.jp (G. Nishigawa).

    see front matter 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.i.org/10.1016/j.dental.2013.02.005

  • d e n t a l m a t e r i a l s 2 9 ( 2 0 1 3 ) 530534 531

    1. Introduction

    1.1. Precomplete desensors

    To design ation area isimpressionexerted by tseating thetissue, andrial causesdistributionan importaresult in anarea [15].

    In dentaimpressionimpressionsion pressuinvestigatio[2,11,12].

    Apart fremerged onpressure. Nvisually exon the dynatray seatinments in aupper dent

    Today, tmainstreamimpressionin impressipressure [1devices mucostly. Theon the edension makinpressure dumeasuremeprohibitivetask due tolies the imto measure

    1.2. Noimpression

    During theor grooves,when trappthe impresor grooves.esized thais a functimaterial onrmed, it c

    alternative and a more affordable means than electric pres-sure sensors to measure pressure.

    con bas

    imp

    Hys em

    impr

    luatdel ntulre sehe ase to

    Aim

    m ofnstrudel, sional walculnsored.tatisticalion ed frsionf extr

    Ma

    Thsion

    retic showty F appe prmoventu

    tubeas asuid iis in

    modbe exal, l,

    Expsion

    perim mossure involved in making impressions forntures and pressure measurement using

    complete denture, the contour of denture founda- obtained by using an impression material and an

    tray. During the impression procedure, pressure ishe impression material on basal seat mucosa while

    impression tray. Basal seat mucosa is compressive pressure applied upon it by the impression mate-

    slight distortion. Therefore, the magnitude and of impression material-produced pressure hasnt impact on impression making, because it may

    inaccurate record of a distorted denture-bearing

    l clinics, escape holes and/or relief space in the tray provide relief for the pressure built up in the material [610]. To evaluate the changes in impres-re caused by relief space and escape holes, severalns were carried out using electric pressure sensors

    om electric pressure sensors, few reports have using alternative means to measure impressionishigawa et al. [13] used video camera recording toamine the effects of escape holes and relief spacemics of the impression material during impressiong. In another study, Rihani [14] used uid move-

    manometer to measure the pressure exerted onure-bearing area during impression making.he use of electric pressure sensors remains the

    method of measuring pressure produced during making. In many studies, they are either mountedon trays or on experimental jaw models to measure1,1517]. However, as these sensors and measuringst be custom-made, they are usually complex and

    magnitude and distribution of pressure producedtulous mucosa play a decisive role in nal impres-g, as the mucosa was distorted easily by excessivering impression taking. For this reason, pressurent should not be viewed by patients as a cost-

    task or by dental practitioners as an intimidating the need for many measuring points. Thus, hereinpetus to develop an easy and economical method

    impression pressure.

    vel theoretical model to measure pressure using material ow

    seating of an impression tray with escape holes pressure buildup within the impression materialed between the tray and edentulous mucosa forcession material to extrude through the escape holes

    On this premise, the authors of this paper hypoth-t the volume of impression material extrudedon of the pressure exerted by the impression

    basal seat mucosa. If this hypothesis were con-ould be used to develop an apparatus to be an

    To formedversus

    1.3. sensoractual

    To evatal moan edepressutime, trespon

    1.4.

    The aithe cocal moimpresmateriwas casure seextrud

    If stheoreregressacquirimpresume o

    2.

    2.1. impres

    A theomodelviscosiForce producrial to The evsilicon

    It wcous analysreticalcould materi

    2.2. impres

    The exacrylicrm this hypothesis, theoretical analysis was per-ed on a uid dynamics model of exerted pressureression material ow.

    pothesis evaluation using electric pressurebedded in edentulous oral mucosa analog andession material ow

    e the hypothesis of this study, an experimen-was constructed in the laboratory. It comprisedous oral mucosa analog embedded with electricnsors to measure exerted pressure. At the samectual volume of impression material extruded in

    each pressure magnitude was also recorded.

    of this study

    this study was to prove the hypothesis by usingcted experimental model. Based on the theoreti-a theoretical formula between pressure exerted by

    material and the volume of extruded impressions derived. On the other hand, regression equation

    ated for the pressure measured by electric pres-s and the volume of impression material actually

    tical similarity could be observed between the formula derived from theoretical model and theequation calculated from actual measurementsom the experimental model, it would prove that

    pressure could be measured by measuring the vol-uded impression material.

    terials and methods

    eoretical model of impression pressure versus material ow

    al analysis was performed using the uid dynamicsn in Fig. 1. In this model, impression material of

    was assumed to be a Newtonian viscoelastic uid.lied to impression material caused the latter to

    essure P, which then caused the impression mate-e through silicone tube of diameter d at speed .al length of impression material which owed into

    was l.sumed that the numerical formula for ow of a vis-n a channel [18] could be applied to the theoretical

    this study. The calculation formula for the theo-el given in Table 1 shows that pressure impulse Ipressed as a function of the length of impressionowing into the silicon tube.

    erimental edentulous arch model and material ow

    ental edentulous arch was a at, circular-shaped,del of 60 mm diameter. Four electric pressure

  • 532 d e n t a l m a t e r i a l s 2 9 ( 2 0 1 3 ) 530534

    F

    Impression Material

    (viscosit y: )

    d

    l

    P

    : speed of impress ion materia l

    moved through si licone tube

    Fig. 1 Theoretical model of impression pressure versusimpression material ow. Force F applied to impressionmaterial (vimpressiontube (diamtube is l.

    Table 1 analysis b

    P = (/2)(l/=32(l/

    (: coefcNext,

    = dl dl =

    Integrating

    l2/2 =I = (1

    From these

    expressestreamed

    sensors (PSthe edentuactually ex

    Flat imclosely wit

    made from transparent acrylic. To enable visual observationand recording of the volume of impression material extrudedfrom holes in tray, four transparent silicone tubes (diame-ter: 1.0 mm, length: 60 mm) were vertically mounted on theimpression tray and positioned at the center of each of the fourpressure sensors embedded in the experimental arch model(Fig. 2). With this setup, the volume of impression materialextruded from the inside of tray could be visually observed; atthe same time, the pressure which caused the extrusion couldbe recorded from the corresponding pressure sensor embed-ded in the experimental arch model.

    2.3. Measurement of impression pressure and volumeof impression material extruded from tray intotransparent tubes

    A polysulde rubber impression material (Surex F Regular,GC Corp., Japan) was mixed and placed into the impres-

    ray. . Traode

    ting mg con

    Fig. 2 Meelectrical piscosity ) caused pressure P to build up within material. P forced material to ow into siliconeeter d) with speed . Length of material ow into

    sion t1.0 mmarch msal tesSeatinCalculation formula for theoretical model andased on uid dynamics.

    d)2 = (/2)(64/d)(l/d)2

    d2)ient of friction of tube, : density of uid).

    l/dt = (P/32)d2/l(d2/32)P dt

    once, we obtain,

    (d2/32) t

    0P dt

    6/d2)l2

    results, impression pressure I(

    = t

    0P dt

    )can be

    d as a function of length of impression material into tube l.

    10KB, Kyowa Dengyo, Japan) were embedded inlous oral mucosa analog to measure the pressureerted by the impression material (Fig. 2).pression tray (2 mm thickness), designed to th the experimental edentulous arch model, was

    or 1.0 mm oDuring t

    sensors emwere transJapan) (Fig.were calculrial which as caused b

    3. Re

    During the cosity valuea rheometeical formulobtained frtheoreticalsure impulimpressionrial: 350, 40

    asurement of actual impression ow and pressure using an ederessure sensors.Two tray spacer thicknesses were used: 0.5 andy was then seated on the experimental edentulousl at a speed of 10 or 20 mm/min using a univer-achine (Autograph DCSC-2000, Shimadzu, Japan).tinued until each tray generated, respectively, 0.5f impression material movement.ray seating, signals registered by the four pressurebedded in the experimental edentulous arch modelmitted to a Signal Processor (Nihon Denki San-ei,

    2). Pressure impulses detected from each sensorated by this processor. Lengths of impression mate-were extruded into the transparent silicone tubes,y built-up pressure, were measured.

    sults

    tray seating procedure of the experiment, three vis-s of the impression material were measured usingr: 350, 400, and 450 Pa s. Accordingly, three numer-ae each corresponding to a viscosity value wereom the calculation formula of [I = (16 /d2)l2] for the

    model: Y = 0.057X2, 0.065X2, and 0.073X2 (Y: pres-se produced by impression material; X: length of

    material in tube; viscosity of impression mate-0, or 450 Pa s; d: 1.0 mm).

    ntulous oral mucosa analog with embedded

  • d e n t a l m a t e r i a l s 2 9 ( 2 0 1 3 ) 530534 533

    Fig. 3 Relation between length of impression material extruded into tube and pressure measured by sensors afxed onexperimental edentulous arch model surface (tray spacer thickness: 0.5 mm).

    Relations between the length of impression materialextruded into the transparent silicon tubes (X-axis) and themagnitudeshown in Fsion formutray spacer

    As seenregression fless, curvesthe experimthe area of most part. results seem

    4. Di

    4.1. Tharch model

    The authorimpression

    function of the pressure built up during tray seating. In theconceptualizing of the theoretical model, volume of extruded

    siontrudus thperimn fon pral whe eensoe, noressuarennter uilt u

    withn bebe abe ex.

    Fig. 4 Relexperimen of pressure measured by the sensors (Y-axis) areigs. 3 and 4. Using regression analysis, four regres-lae were obtained from two seating speeds and two/impression material thicknesses.

    in Figs. 3 and 4, coefcients of the theoretical andormulae did not show proximate values. Nonethe-

    of the four regression formulae calculated fromental edentulous arch model were drawn within

    the curves of the three theoretical formulae for theTherefore, both the experimental and theoreticaled to show some similarity.

    scussion

    eoretical model versus experimental edentulous to measure pressure

    s of this paper hypothesized that the volume of material extruded from escape holes in tray is a

    impresrial exand ththe exculatiobetweemateri

    At tsure ssurfacting, pTranspthe cesure bagreedrelatiointo tucould modelation between length of impression material extruded into tube tal edentulous arch model surface (tray spacer thickness: 1.0 mm was represented by the length of impression mate-ed into transparent tube to simplify the model e vertical mounting of silicon tubes into tray onental model. From the theoretical model, a cal-

    rmula of [I = (16 /d2)l2] showing the relationshipessure impulse and volume of extruded impressionas obtained.xperimental edentulous arch model, electric pres-rs were afxed on the experimental jaw modelt on the tray surface. During impression tray sea-re signals registered by the sensors were recorded.t silicon tubes were xed in the tray right aboveof each pressure sensor, ensuring that the pres-p in the impression and at each tubes position

    the pressure at sensor surface. On this premise,tween length of impression material extrudednd pressure magnitude at each tubes positionamined using the experimental edentulous archand pressure measured by sensors afxed on).

  • 534 d e n t a l m a t e r i a l s 2 9 ( 2 0 1 3 ) 530534

    4.2. Comparison of numerical formulae obtained fromtheoretical and experimental models

    Despite differences in tray seating speed (10 or 2 mm/min) andtray spacer thickness (0.5 or 1.0 mm), similar quadratic curvesshowing the relation between actual pressure measured andlength of impression material extruded into tubes were drawn(Figs. 3 and 4). These results showed that the relation betweenimpression material and pressure was approximately consis-tent regard

    Viscositing, and it measuremmeasurem450 Pa s at tnumerical 400, and 45oretical mo

    The threcal model (to the four tal model theoreticalsal validitytheoreticalspeed and

    4.3. Apmeasureme

    Only one kstudy. Furthship betwematerial frowith differe

    Within tmeasuringholes and gmethod of tubes enabdistributionedentulous

    In termsings of thiseconomicato measure

    r e f e r e n

    [1] Koran bearing1980;24

    [2] Kikuchi M. Rheological properties of elastomer impressionmaterials. Aichi Gakuin Daigaku Shigakkai Shi1990;28:1287302.

    [3] Sato M. Inuence of various impression procedures formandibular distal extension removable partial denture ondisplacement of residual ridge. Kokubyo Gakkai Zasshi1996;63:88107.

    [4] Kof NJ, Kof KG, Assi KD. Why should we use plaster for theprime impression in complete removable prosthodontics.Odontostomatology 2005;28:1722.

    gnondimepres312orrowocedosby ein IEchniqsuesrb Gosthuis: Tmbrpresmova98;80ncanpresosthekuchocedotets-Ahm

    Presalogsign101ishigasual presucoshabihanipres

    hizukethopporllegeigetostribuentu

    the r95;8:igetostribuentuwdeurnairose .; 19less of tray seating speed or relief space thickness.y of the impression material increased after mix-changed continuously during the entire pressureent period. Viscosity at the beginning of pressureent was approximately 350 Pa s, and it increased tohe end of tray seating procedure. Therefore, threeformulae according to the viscosity values of 350,0 Pa s were used for validity evaluation of the the-del.e numerical formulae obtained from the theoreti-I = (16 /d2)l2; Table 1) seemed to bear resemblanceregression formulae obtained from the experimen-(Figs. 3 and 4). These results suggested that the

    model presented in this paper might have univer-. Therefore, the numerical formula obtained from

    analysis could tolerate variations in tray seatingtray spacer thickness.

    plication of theoretical model for pressurent in clinical situations

    ind of impression material was evaluated in thiser investigations are needed to clarify the relation-en impression pressure and volume of extrudedm tray for different kinds of impression materialsnt rheological properties.he limitations of this study, it was concluded that

    the impression material extruded from escaperooves in tray could potentially be an alternativemeasuring impression pressure. The transparentled clear visual inspection of the magnitude and

    of pressure during impression tray seating on the arch.

    of clinical signicance and implications, the nd- study could be leveraged to develop an easy andl apparatus that does not require electric sensors

    pressure during impression making in the future.

    c e s

    III A. Impression materials for recording the denture mucosa. Dental Clinics of North America:97111.

    [5] Ri3-im60

    [6] MprM

    [7] Kltetis

    [8] ZaprLo

    [9] Duimre19

    [10] DuimPr

    [11] KiprH

    [12] AlE.ande95

    [13] NViimmRe

    [14] Riim

    [15] IsmsuCo

    [16] Shdiedof19

    [17] ShdiedpoJo

    [18] HCo-Bret C, Dupuis R, Gaudy JF. Application of ansional measurement system to complete denturesions. Journal of Prosthetic Dentistry 2002;87:.

    RM, Rudd KD, Eissmann HF. Dental laboratoryures, Vol. I. Complete dentures. St. Louis: The CVCo.; 1980., Broner AS. Complete denture secondary impressionue to minimize distortion of ridge and border. Journal of Prosthetic Dentistry 1985;54:6604.A, Bolendar CL, Hickey JC, Carlsson GE. Bouchersetic treatment for edentulous patients. 10th ed. St.he CV Mosby Co.; 1990.igue HB, Esquivel JF. Selective-pressure singlesion procedure for tooth-mucosa-supportedble partial dentures. Journal of Prosthetic Dentistry:25961.

    JP, Raghavendra S, Taylor TD. A selective-pressuresion technique for the edentulous maxilla. Journal oftic Dentistry 2004;92:299301.i M. Pressures produced in a tray during impressionures. Maxillary edentulous impressions. Nihonu Shika Gakkai Zasshi 1987;31:5906.ad A, Masri R, Driscoll CF, von Fraunhofer J, Romberg

    sure generated on a simulated mandibular oral by impression materials in custom trays of different. Journal of Prosthodontics 2006;15:.wa G, Natsuaki N, Maruo Y, Okamoto M, Minagi S.observation of the dynamic ow of elastomer rubbersion material between the impression tray and orala while seating the impression tray. Journal Orallitation 2003;30:60813.

    A. Pressures involved in making upper edentuloussions. Journal of Prosthetic Dentistry 1981;46:6104.a I, Mizokami T. Relationship between impressiond of mucosa-borne area and denture pressuretability through the denture. Bulletin of Tokyo Dental

    1993;34:2332. N, Hamada T, Iwanaga H, Murata H. Pressuretion using tissue conditioners on simpliedlous ridge models. Part 1. The inuence of the heightesidual ridge. International Journal of Prosthodontics4905.

    N, Hamada T, Iwanaga H, Murata H. Pressuretion using tissue conditioners on simpliedlous ridge models. Part 2. The inuence of ther particle size and ethanol content. Internationall of Prosthodontics 1995;8:55763.K. Nagaregaku [Fluid dynamics]. Tokyo: Kyoritsu Publ.80.

    New theoretical model to measure pressure produced during impression procedure for complete denturesVisual inspection of ...1 Introduction1.1 Pressure involved in making impressions for complete dentures and pressure measurement using sensors1.2 Novel theoretical model to measure pressure using impression material flow1.3 Hypothesis evaluation using electric pressure sensors embedded in edentulous oral mucosa analog and actual impression ...1.4 Aim of this study

    2 Materials and methods2.1 Theoretical model of impression pressure versus impression material flow2.2 Experimental edentulous arch model and impression material flow2.3 Measurement of impression pressure and volume of impression material extruded from tray into transparent tubes

    3 Results4 Discussion4.1 Theoretical model versus experimental edentulous arch model to measure pressure4.2 Comparison of numerical formulae obtained from theoretical and experimental models4.3 Application of theoretical model for pressure measurement in clinical situations

    References

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