The Microtensile Bond Test: A Review

David H. Pashleya/ Ricardo M, Carvalhob/ Hidehiko SanoVMasatosiii Nakajima«^/ Masahiro Yoshiyama^/YasuoSinonoV

Carios A. FernandesS/ Franklin Tay'

Purpose: The purpose of this review is to describe ail of the various modifications of the microtensilebond test in one paper, so that investigators can select the modification that best suits their needs.

Methods: The essence of the microtensile test is the division of resin-bonded teeth into siabs between0.5 and 1.0 mm thick that are then trimmed in such a manner that tensile force will be concentrated onthe bonded interface during testing. Among the many advantages of the technique are that each toothproduces multiple specimens. Further, there is no need for a matrix to limit the bonded surface area,since the area is determined by the dimensions of the trimmed specimens.

Results: The various modifications of the microtensile test have been used to measure differences in re-gional bond strength across occiusal dentin, down the external surface of teeth from crown through roots,down the internal surface of root oanals from cervical to apical thirds, as well as tc ccmpare normal vscaries-affected occiusai dentin and normal vs sclerotic cervical dentin. The technique is ideal for evaiuat-ing the long-term duraüiiity of resin-hard-tissue bonds.

Conclusion: The microtensile test methods offer versatility that cannot be achieved by conventional meth-ods. It is more labor-intensive than conventional testing, but holds great potential for providing insight intothe strength of adhesion of restorative materiais to clinicaiiy reievant sites and substrates.

JAddesive Dent 1999; 1:299-309. Submitted for puàlication:11.08.99: accepted forputilication:17.09.99.

a Regent's Professor, Department of Orai Bioiogy and MaxiilofacialPathology, School of Dentistry, Medicai College of Georgia. Au-gusta. Georgia. USA.

b Assistant Professor. Department of Operative Dentistry, BauruSchooi of Dentistry. University cf Sao Pauio, SP, Brazii.

c Professor, Department of Operative Dentistry. School of Dentistry,Hokloido University. Sapporo. Japan.

d instructor. Department of Operative Dentistry, Tokyo Medical and

Dental University, Tokyo, Japan,

e Assistant Professor. Department of Consen/ative Dentistry School

of Dentistry, Tokushima University, Tokushima. Japan.

f Assistant Professor, Department of Operative Dentistry, Kyushu

Dentai Coilege, Kitakyushu City, Japan,

g Assistant Professor, Department of Operative Dentistry. School of

Dentistry. University of Estadual De Ceaia. Fortaleza, Brazil,

h Assistant Professor. Department of Conservative Dentistry, ThePrince Philip Dentai Hospital. Hong Kong, China.

Reprint requests: Dr. David H. Pashiey, Dept of Orai Bioiogy andMaxWofaoiai Pathoiogy, Schooi of Dentistry Medicai Coiiege of Geor-gia. Augusta. Georgia 30912-1129. USA. Tei: ++1-706-721-2033,Fax: ++1-706-721-6252, e-maii: dpashley@maii.mcg.edu

Many laboratories use simple shear or tensile

bond tests to compare products or evaluate

the infiuence of expérimentai variables on resin-

dentin bond strength. Generally, they limit the ioca-

tion of the bond to the center of the occiusai or

iabiai surface of midcoronal normal dentin. The

bonded surface is demarcated using a 3- or 4-mm-

diameter hole punched in sticky tape, or some type

of matrix is used that is 3 to 4 mm in diameter (7 to

12 mm2). These simpie tests served well when

resin-dentin bond strengths were reiatively low (ca

10 to 15 MPa). iHowever, as bonding techniques

and materials improved, the bond strengths be-

came high enough to cause cohesive faiiures in

dentin. That is, dentin broke from dentin, leaving

the resin-dentin interface intact. The frequency of

cohesive failures of dentin can be as high as 80%

when bond strengths reach 25 iViPa.^ Such faiiures

of the substrate preciude measurement of interfa-

cial bond strengths and limit further improvements

Vol 1, No 4,1999299

Pashiey et al

in bonding formulations, since the tests can nolonger detect improved adhesion. Such cohesivefailures in dentin do not mean that the resin-dentinbonds are uniformiy stronger than the intrinsicstrength of dentin, but that the manner in which thebond is stressed is so non-uniform that it is concen-trated or focussed at one highiy iocaiized regionwhere it opens a crack in dentin, that then fails-These stress concentrations often exceed 100MPa, even though the calcuiated average bondstrength is only 25 MPa,20-22

To avoid cohesive failures of dentin during bondtesting, it IS necessary to improve stress distribu-tions during testing. This can be accomplished bythe singie-plane lap-shear system,^ or by the mi-crotensile bond testing methods described in thisreview. Both are more iabor-intensive methods thanconventional methods, but both avoid inducing co-hesive faiiures in dentin. Both methods tend toiower the variance associated with testing to 10% to25%, instead o f t he more common 30% to 50%variance seen in conventionai testing. Both meth-ods have been used to evaluate regionai differ-ences in the strength of dentin or resin-dentinbonds, although this is more easiiy accompiishedwith the microtensiie method. Regionai differencesin resin-dent in bond strength have been re-ported,12.is indicating that these differences aregreater than tooth-to-tooth variations.

In some parts of the world, it is difficult to obtainextracted teeth, especially intact premolars andthird molars. The microtensile testing method per-mits multiple specimens to be prepared from eachtooth. Thus, there is a trade-off between the extralabor involved in using this method, and the extradata that can be obtained per tooth,

Microtensile bond testing was originaiiy designedto permit evaiuation of bond strengths between ad-hesive materiais and smaii regions of dental tissue(eg, occiusal vs middle vs cervical third of ena-mei,^^ normai vs adjacent caries-affected dentin,^occiusal vs gingivai walis of Class V wedge-shapediesions),2^ One advantage of the technique is thatthe bonded interface of smail (ca 1 mm2) speci-mens has a better stress distribution during load-ing, so that there are fewer cohesive failures indentin than are found with more conventional test-ing.8 This is thought to be due to a reduction inflaw density. Using this method often results inhigher apparent bond strengths at failure than arefound using large specimens,2

Since the introduction ofthe technique,i3 a num-

ber of iaboratories have made numerous modifica-tions to it. The purpose of this review is to describeall of the various modifications of the microtensilebond test in one paper so that investigators can se-lect the modification that best suits their testingneeds. The advantages and disadvantages of thevarious techniques are aiso discussed.

MATERIALS AND METHODS

The original microtensile testing was done on min-eraiized dentin to measure its ult imate tensilestrength (iJTS) and moduius of eiasticity," To mea-sure UTS, the specimens were trimmed to an hour-giass profiie (simiiar to Fig IF) to produce uniformstressing of the smaiiest oross-sectional area. Tomeasure the modulus of eiasticity in tension, theneed of a known gauge-iength required that thespecimens be tr immed to the outline of an " I "beam,! ' ' j ^ a t approach has also been used tomeasure the UTS and eiastic moduius of the dem-ineraiized dentin matrix^^ by protecting the minerai-ized ends of the specimens with nail varnish, whiiethe central region was demineralized in EDTA,

in the originai microtensiie bond test, the oc-ciusai surface of the tooth was ground fiat (Fig IB),The entire surface was bonded, and a iarge resincomposite buiidup was created (Fig IC), The needfor a matrix or mold that defined the bonded sur-face area was eliminated, and with it, attendantconcerns about uneven thickness of adhesives,meniscus effects, creation of flashing, etc.s Indeed,there is theoreticaily no need to produce a fiat sur-face using polishing devices. The surface to bebonded can be fractured, polished, or bur cut. Thisconcept has never been evaluated, but could easilybe tested, Microtensile testing can be done enteeth prepared exactly as they are restored ciini-caiiy, because the bonded surface area is deter-mined af ter bonding, not before bonding, bytrimming (Fig IC to F),

if bond strengths are relatively iow (ca 5 to 7MPa), the use of a high-speed handpiece to trim thespecimen may cause premature failure of the bond.This is due to slight eccentric movements ofthe burwhich cause vibrations in the specimen, as well asuneven cutting force when trimming is done "free-hand."

Another method of trimming is to create a plexi-glass table on an Isomet saw (Buehler, Lake Forest,IL, USA) and trim the specimen under microscopic

300 The Journal of Adhesive Dentistry

F i g l Schernatic illustrating the essen-ce of the microtensiie bond testing tech-nique. A tooth surface is prepared (B| anda resin composite crown is created (C).One day later the restored tooth is verti-cally serially sectioned into 0.7- to 1.0-nim-thick slabs (D|. Each slab (E) is then trimm-ed to concentrate the stress to the bondedinterface of interest, using a gentle curve(F] or a slot (G¡. A single siab (E¡ can be fur-ther divided into two specimens (E') thatcan be trimmed (E"). When dividing the re-stored tooth into slabs (D), the tooth can berotated 90° and the slabs converted intosticks (D'). Each stick can be tested withouttrimming (D") or it can be turned in a mi-crolathe to form an hourglass cylindricalshape (D"').

observation, using the device like a table saw. Thiscreates a very narrow channel of removal of dentinand resin composite {Fig lG). i ' The width of thischannef can be increased by mal<ing multiplepasses or by placing a shim on one side of theblade to make it eccentric, thereby cutting a widerswath through the specimen as it turns (Dr RobertChappeii, personal communication). There hasbeen no systematic evaluation of the effect ofshape of the trimmed specimen on measured bondstrength, aithough Phrukkanon et al found that

there was no effect of cylindrical vs rectanguiarcross sections.ii

Due to the strong effect of cross-sectional areaon resin-dentin bond strength,^^ ¡ ¡g important tomake certain that there is no statistically significantdifference in bonded cross-sectional areas betweenexpérimentai groups, if differences exist, then onemust adjust for the covariant of bonded area usingthe Least-Squares Means test, which adjusts forsuch differences prior to comparing bond strengths.We prefer to trim specimens to 0.8 to 1.0 mm .

Vol 1, No 4, 1999 301

Pashley et al

Fig2 Schematic i l lustrat ion of thecrown of a tooth that was used to measureregional differences in resin-enamel bondstrength (A], Bonded specimens (B) werethen divided in half tc provide lingual andbuccal specimens (C), Each half was thenvertically serially sectioned tc produce mul-tipie siabs that were trimmed to the appro-priate cross-sectional area (D) and site.From Shono et al^^ with permission.

In tbe original method, a large resin-bondedmolar yielded 5 to 8 siabs when vertically sectioned(Fig lC to F), depending upon the thickness of theblade and the desired thickness of the slabs. Thus,eacb tooth yieided 5 to 8 specimens for bond test-ing, instead of a singie specimen using conven-tionai testing. This also creates statisticaiproblems. Should one calcuiate a mean ± standarddeviation per tooth or pool the specimens of sev-erai teeth? We prefer tbe latter approach. This willbe discussed in more depth below.

To determine the relationship between resin-dentin bond strength and tootb location, one mustdivide dentin into small specimens, Watanabe et alreported differences in the intrinsic strength ofdentin in different regions,23 However, Shono et alfound no consistent influence of region on resin-dentin bond strengths on occiusal surfaces.^^ Theyalso found no differences in resin-enamei bondstrengths between buccal and lingual surfaces.^^Pbrukkanon et al, using a modification of tbe mi-crotensile technique [Fig ID"), reported there waslittle difference in resin-dentin bond strengths witblocation or in tensile vs shear testing,12

The original method has been modified by Car-valbo (unpublished observations] by dividing theflat occlusai plane of dentin (Fig IB) into two equaihalves by lightiy scoring a line across the surface

with a bur. One side of the tooth can serve as a con-trol. This provides paired specimens for improvedstatistics. Another modification is to vertically di-vide siabs into two halves to double the number ofspecimens that can be created from a single siab(Fig IE' and F"), Carvalho has aiso divided a singlelarge slab into three smaller siabs, each of whichcan be trimmed. In a simiiar manner, Shono et aldivided molars into buccai vs Iinguai halves, andeacb halt was then divided into 4 individual slabs(Fig 2),i8

The use of such small specimens requires spe-ciai testing jigs that insure application of pure ten-siie forces and avoidance of torquing forces. Thishas been done using the Bencor Multi-T (Fig 3, ieft)device (Danville Engineering, Danville, CA, USA) op-erated in an instron machine (Instron, Canton, MA,USA). More recently, severai groups have begunusing an even smaller jig designed by Dr BernardCiucch|9'io and shown in Fig 3 (right),

A natural progression of siab reduction intosmaiier and smaller components was the creationof what we cali the non-trimming microtensile bondstrength test. In this technique, each of the 5 or 6siabs is cut into 7 to 8 sticks or beams (Fig 4) thetop half of which is resin composite end the bottomhaif of which is dentin. Using this technique, a sin-gle tooth yields 25 to 30 such specimens with

302 The Journal of Adhesive Dentistry

Pashley et al

Fig 3 Schematic illustration of two testing devices. TheBencor Multi-T device (ieft) was designed to permit a wide va-riety of shear and tensile testing. It was modified for triemicro-tensile test by creating opposing flat surfaces on stain-less steel cylinders. The Ciucchi device (right) is muchsmaller (note tlie scale) and is not avaiiabie commercially al-though any machinist could duplicate it. Due to the smallsize of the test specimens, they can not De "gripped" in theclassic sense, but are glued to the testing apparatus withquick-set cyanoacryiate. The devices insure that pure tensileloads are applied during testing.

square cross sections of 0.7 to 1,2 mm^, depend-

ing upon hovii it is done (Fig ID and D'), These

sticks are created using the piexigiass table on an

Isomet saw under microscopic observation. Alterna-

tively, tbe composite resin buildup can be sectioned

into 5 or 6 slabs with care, so that the blade does

not pass entirely through the base. The tooth is

then rotated 90 degrees and another 5 to 6 sec-

tions are made, resulting in 25 to 30 sticks that re-

main attached to the base. After iabeling each

stick, they are separated from the base of the tooth

for testing (Fig ID*'], If care is taken to identify the

buccal, lingual, mesial, and distal regions of the

tooth, this method can be used to evaluate the uni-

formity of bond strength across an occlusal

surface,19 Although that study showed that bond-

ing to dentin is not very uniform, there was no con-

sistent variation in bond strength as a function of

location. The non-trimming method apparentiy

piaces less stress on adhesive bonds, because it

Fig 4 Schematic illustration of the non-trimming micro-tensile test. The restored tooth (A) is vertically sectioned (B)into siabs with care taken to identify the buccolingusi andmesiodistal location of each slab and of each subsequentlycreated stick (C). Each stick is glued to the flat stainless steel"grip" with cyanoacryiate (D). In actual testing, the cyanoacry-iate covers the entire surfaces of both ends of the stick to in-crease the surface area of the cyanoacrylate-stainiess steeibond. If too little cyanoacryiate is used, the strength of theresin-dentin bond may exceed the strength of the cyanoacry-l3te-steei bond, requiring re-gluing.

has been able to measure the bond strengths of

mater ials that produce relativeiy low bond

strengths. Bond strengths as iow as 5 MPa have

been measured using the non-trimming technique.

Recently, a f inite element (FE) analysis was

made on the stress distributions of the hourglass

profile of trimmed specimens vs the same cross-

sectional area from a cylindricai fo rm, i i The FE

analysis cieariy demonstrated the improved stress

distribution of the cylindricai hourglass configura-

tion, aithough actuai testing of specimens made in

Voi 1, No 4, 1999 303

Pashiey et al

Preparation of alongcavity in enamel andfniddie dentin of acuspid tooth

Application ol adhesiveon the cavity and build-upof resin composite

Sectioning into 15 slabs(0,75 mm thick) at rightangles to the iong axis

enamel

coronai dentinC6r\/ical dentinmiddie root dentinapicai root dentin

Trimming ot bondedsurfaces to give a bondedsurface area ot 1

Measurement ot tensilebond strengths at across-head speed ot1 mm/min

Fig 5 Schematic illustration of the longclass V cavity preparation that begins inenamel and foilows the labial surface of thetooth to the apex of the root. After condi-tioning, priming and appiying of adhesive,the tooth is incrementally restored in resincomposite that is over-ccntoured to provideadditional bulk for handling. Muitipie hori-zontal serial sections are made with careto note the location. These sections arepiaced on moistened paper towels to pre-vent drying. Each section is then trimmedto provide a 1 x 1 mm test area, and thengiued to the test device. This technique of-fers simple screening of the regionai differ-ences in bond strength of adhesivemateriais. if a water-fiiied tube is placed inthe apex of the root and the tooth is sus-pended from the tube 15 to 20 cm belowthe height of the meniscus in the tube, thebonding and storage can be done underphysiological pulpal pressure.

the two configurations showed no differences. Thatgroup aiso demonstrated no difference in thestrength of dentin whether it was shear or tensiletested, when the specimen cross-sectional areaswere small.^^

Due to variations in the structure of dentin be-tween coronal and radicular dentin, the strength ofresin-dentin bonds may vary. Another modificationof the miorotensiie test that is very useful in rapidiyevaiuating regional differences in bond strength iscalied the "iong Class V cavity preparation."^eUsing diamond burs in a high-speed handpiece withcopious air-water spray, about 1 mm of enamel and2 mm of coronal dentin and cementum-root dentinIs removed to form a cavity that is about 4 mm wideX 2 mm deep x 12 to 16 mm long (Fig 5).26^27When the surfaces are acid etohed, rinsed, primed,and bonded, the original contour of the tooth is re-stored with a light-cured composite. The surface

and margins are then finished using standard ciini-cai polishing techniques. The restored tooth is thenplaced in 37°C water for 24 h. The next day, thespecimens are removed, and the restored surfacesare acid etched with 35% phosphoric acid gei for15 s and rinsed. Subsequently, a bonding agent isappiied, and a iarge excess of composite resin isapplied to the originai composite. The buildup isdone in 1.5-mm increments with 40 s light curing toa depth of about 3 to 4 mm. The restored tooth withthe excess iabiai composite resin is placed in anIsomet saw, and serial slabs about 1.0 mm thickare cut and placed in the order that they were cutonto a piece of moist paper towel. By knowing theoriginai length of the prepared cavity, the thicknessof the biade, and the thickness of each siice, onecan caicuiate whence the slab originated (eg, cervi-cai, middle, apical third of root dentin, etc). Thespecimens are then trimmed to an hourglass shape

304 The Journai of Adhesive Dentistry

Fige Illustration of the preparation ofpost space in a root (A-D). Some systemsinclude a brush (E) to olean out debris.After inserting a post or flowabie compos-ite, the root is serialiy sectioned horizon-tally (F), trimmed into equal halves (G) andthen a test site is seiected and isolated (H)by trimming so that the smallest cross-sec-tionai area (cs 0,8 x 1,C mm) exists at thetest site. Excess cyanoacryiate is used togiue both ends of the trimmed specimen tothe testing device (I),

and tested in the tensiie tester (Fig 5), Although thistechnique does not simuiate ciinicai practice, it pro-vides a convenient survey of bonding to enameiand ooronal and rootdentin.26.2"^

Another variation of this technique is usefui formeasuring regional variations in resin bondstrength to endodontic posts or the inside of rootcanais, Fernandes and Pashiey (unpubiished corpo-rate report) recently developed that techniquewhich is shown in Fig 6,

To better simuiate ciinicai practice, Yoshiyama etai obtained extracted teeth with wedge-shaped cer-vicai iesions.2^ These were bonded with one ofthree adhesive systems and restored as one wouiddo in clinical practice. The controi teeth were ex-tracted normai teeth with no cervicai lesions.Wedge-shaped cavities were prepared in them thathad the same shape and depth as the authentic ie-sions (Fig 7A and A'). These teeth were bonded justlike the other teeth. One day iater, the finished com-posites and surrounding dentin were acid etched,treated with bonding agent, and excess compositeresin was added (Fig 7B and B'), Four to six slabswere made in a buccoiinguai direction, each 0,7 to

0,8 mm thick (Fig 7C and D'), The first slab wastrimmed to an hourgiass profile, with the narrowestarea at the bonded interface at the occiusai floor ofthe wedge-shaped lesion (Fig 7D), The second slabwas trimmed so that the narrowest region was atthe resin-dentin interface of the gingival floor of thewedge-shaped lesion (Fig 7E), By using alternatesiabs, one can evaiuate the bond strengths of bothwalls of wedge-shaped lesions in the same restora-tion. Alternate siabs could also be used to evaiuatethe bond strength of the peripheral half vs the cen-tral half of the gingival fioor aione,

Ciucchi^ was the first to use the microtensiiemethod to evaluate resin-dentin bonds to differentregions of restored MOD preparations (Fig 8A to F),This study was technicaiiy demanding, but demon-strated the utiiity of this innovative approach. Thenon-trimming (stick-forming) method couid alsohave been used in this type of study. The essenceof the Ciucchi method is the different planes usedto section compiex restorations (Fig SC vs C).These preparations have compiex C-factors,"* butthese can be controiied for through proper expéri-mentai design, 'i

Vol 1, No 4,1999 305

Pashley étal

D'

Fig 7 Schematic illustrattng the use of the mtcrotensile test to measure resin-denttn bond strength to the upper and lower mar-gins of wedge-shaped sclerotic dentin. Wedge-shaped lesion (natural or artificial) (A, A'). After restoration to contour, excess com-posite is added (B, B'j to provide enough bulk for specimen preparation ¡C¡. Alternate slabs of the vertical serial sections aretrimmed at the upper (D) vs the lower (E) margins.

Through careful trimming, the microtensiie bondtesting method permits isolation of specific types ofdentin in addition to specific locations. Nai ajima etal^ were the first to use this method to measure thebond strengths of resin adhesives to caries-affecteddentin {Fig 9). Using caries-detector stain to identifythe presence of infected dentin, the occlusai sur-faces of carious dentin were ground down untiihard, opaque, caries-affected dentin was reached,surrounded by normai dentin (Fig 9B|. After bondingand creating a composite resin crown (Fig 9C), ser-ial vertical sections were made through the entirecrown, creating a series of slabs through both nor-mal and caries-affected dentin. Using a high-speedhandpiece and an uitrafine diamond bur, the nor-mal dentin surrounding canes-affected dentin wasremoved from both sides to create an hourglassshaped specimen (Fig 9D and E). This insured thatthe entire test area was iocated in caries-affected

dentin. Slabs of normal dentin were trimmed in thesame manner to the same cross-seotional area toserve as controls. This technique demonstratedthat the use of 10% phosphoric or maleic acid oncaries-affected dentin produced lower bondstrengths, and that the combination of 32% to 35%phosphoric acid and moist bonding produced resinbonds to caries-affected dentin that were as high asthose made to normal dentin.^.^ Similar studiesneed to be done on caries-affected dentin in com-plex preparations where the C-factors are higherthan those obtained on flat surfaces.'^'2i

in the past, few studies have been done on thebond strength of resin-dentin bonds aiiowed tofunction in vivo for more than a day, because thetesting methods required large flat surfaces. Re-cently, Sano et al placed composite resins in largeClass V preparations in moni<ey teeth in vivo.^^They extracted teeth at 1 day, 6 months, or 12

306 TheJournai of Adhesive Dentistrv

Pashleyetal

Fig 8 Use of the microtensiie testing technique to measure resin-dentin bond strengths to different regions of a MOD resin-composite restoration (A], When serially-sectioned in the mesipdistal direction (B, C, D), the slabs can be trimmed tc isolate thepulpal or gingival resin-dentin bonds (E) or the bonds to the axial walls (F), When sectioned in tine buccolinguai direction (B'j, otherregions can be tested (C, D', E).

Fig 9 Schematic iliustrating the use ofthe microtensiie technique for measuringresin bond strength to normal and caries-affected dentin in the same tooth. The oc-clusal surface (A) was ground flat afterstaining the carious lesion with caries-de-tector solution. Flat surfaces avoid thecomplications Pf varying C-factors,'' Afterreaching hard, opaque caries-affecteddentin (B), the entire surface was thenbonded and a resin composite crown cre-ated ¡C), that was verticaliy-sliced into siabsID), Note that some of the siabs were com-posed entireiy of normai dentin, whiie otherslabs contained caries-affected dentin sur-rpunded by normal dentin (D¡, Using an ul-trafine diamond bur, the normal dentin wasremoved so that the entire bonded inter-face was on caries-affected dentin (E¡, Sim-ilar t r imming was done to specimensbonded to normal dentin as controls.

Vol 1, NP 4, 1999 307

Pashley et ai

months, and prepared them for microtensile bondtests. The Ciearfii Liner 2 (Kuraray, Osaka, Japan)bond strengths were ail about 19 MPa, regardiessof time in function, but SEM examination of thefailed bonds demonstrated a deterioration of boththe composite resin and the hybrid iayer at 6 and12 months. Indeed, the small size of the bonded in-terface permits both sides of the failed bond to beplaced on the same SEM stub. The number oftubules per mm^ in middle dentin is about 20,000to 30,000. Thus, even a 0,5- x 0,5-mm specimenwith a surface area of 0.25 mm^ contains 5000 to7500 tubuies. However, these can be readily sur-veyed by SEM, This permits good correlations to bemade between the bond strength of tbat specimenand the SEM appearance of the interface.^ Thesesmall specimens aiso facilitate the examination ofthe bonded interface by TEM (Tay, unpublished ob-servations).

Hopefully, as more investigators understand thebroad utility of the microtensile test methods, morelong-term in vivo evaluations of composite resinbond strength will be performed. Since the trimmedspecimens are very small, they can be preparedfrom restored teeth that have been in function forvarying periods of time,i6

This same technique can be used to measurechanges in the strength of resin-cement iuted cast-ings to dentai tissue. That is, one would performsuch experiments on teeth that were scheduied tobe extracted for periodontal, orthodontic, orprosthodontic reasons. The cemented castingwould be allowed to function for a defined periodand then the tooth would be surgically removed.After cleaning the casting with an air abrasion sys-tem, the crown would be embedded in resin. Afterpolymerization, serial verticai sections would bemade through the extracted tooth and excess resinto form multiple slabs. The slabs would be trimmedcarefully so that the thinnest portion of the speci-men was at the point of interest (eg, resin ce-ment-dentin interface).

In conclusion, the microtensiie bond testingmethods offer versatility that cannot be achieved byconventional methods. It is more labor-intensivethan conventional testing, but hoids great potentialfor providing insight into the strength of adhesion ofrestorative materials used in dentistry as a functionof time.

ACKNOWLEDGMENTS

This wurk was siippurted, in pan, by grant DE 0642'? from theNIDCR (10 DHP) and FAPESP grant 95/3895-9 (to RM<-'l

REFERENCES

1, Armstrong SR, Boyer DB, Keller JC, Microtensile bondStrength testing and faiiure analysis of two dentin adhesives.Dent Mater 1998; 14:44-50.

2, Cardoso PEC, Braga RR, Carrilho MRO. Evaluation of micro-tensile, shear and tensile tests determining the bondstrength of three adhesive systems. Dent Mater1998; 14:394-398.

3, Ciucchi B. Bonding characteristics of resin composite restora-tions on dentin Class II cavity wails, in vitro ¡thesis]. Geneva;Univ of Geneva, Switzerland, 1997,

4, Davidson CL, deGee AJ, Feilzer AJ, The competition betweenthe ccmposite-dentin bond strength and the polymerrzatiorcontraction stress. J Dent Res 1984;63;1396-1399,

5, Inai N, Konemura N, Tagami J, Watanabe LG, Marshall SJ,Marshall GW, Adhesion between collagen depleted dentinand dentin adhesives. Am J Dent 1998;11;123-127,

6, Nakajima M, Sano H, Burrow MF, Tagami J, Yoshiyama M,Ebisu T, Pashley DH, Tensile bond strength and SEM evglua-ticn of caries-affected dentin using dentin adhesives. J DentResl995;74:1679-1688,

7 . Nakajima M, Sano H, Zheng L, Tagami J, Pashley OH. Effectof moist vs. dry bending tc normai vs. caries-affected dentinwith Scotchbond Multi-Purpose Plus. J Dent Res 1999:78; 1398-1303.

8. Pashley DH, Sano H, Ciucchi B, Voshiyama M, Canjalho RM.Adhesion testing of Oentin bonding agents; A Review. DentMater 1995;11:117-125.

9 . Paul SJ, Weiter DA, Ghazi M, Pashiey DH. Nanoieakage at thedentin-adhesive interface vs, |j-tensile bond strength, OperDent 1999;24; 181-188.

10. Paul SJ, Leach M, Rueggeberg FA, Pashley DH. Effect ofwater content on the physicai properties of model dentineprimer and bonding resins. J Dent 1999:27;209-214.

11. Phrulikanon S, Burrow MF, Tyas MJ, Effect of cross-sectionalsurface area on bond strengths between resin and dentin.Dent Mater 199S; 14:120-128,

12. Phrukkanon S, Burrow MF, Tyas MJ. The effect of dentine lo-cation and tubule orientation on the bond strengths betweenresin and dentine, J Dent 1999;27;365-274,

13. Sane H, Sonoda H, Shono J, Tskatsu T, Ciucchi B, CarvalhoRM, Pashley DH, Relationship between surface area fcr ad-hesicn and tensrie bond strength - Evaluation of a microten-sile bend test. Dent Mater 1994a: 10:236-240,

14. Sano H, Ciucchi B, Matthews WG, Pashley DH, Tensile proper-ties of mineralized and demineralized human and bovinedentin. J Dent Res 1994:73:1205-1211.

15. Sano H, Takatsu T, Ciucchi 8, Russeli CM, Pashley DH, Ten-sile properties cf resin-infiltrated demineraiized humandentin. J Dent Res 1995;74:1093-1102,

16. Sano H, Yoshikawa T, Pereira PNR, Kanemura N Morigami MTagami J, Pashley DH, Long-term Ourability of dentin bondsmade with a self-etching primer in vivo, J Dent Ra= IQQQ-78;906-911, ^ '

308 TheJournal of Adhesive Dentistry

Pashiey et al

17, Schreiner RF, Ohappeii RP, Glaros AG, Eick JD. Microtensiletesting cf dentin adhesives. Dent Mater 1998:14:194-202.

IS. Shone V, Terashita M, Pashiey EL. Brewer PD, Pashiey OH. Ef-fects of surface area on resin-enamel tensiie bond strength.Deni Mater 1997;13;290-296.

19. Shono Y, Ogawa T. Terashita M, Oarvalhc RM, Pashiey EL,Pashiey DiH, Regionai measurements of resin-dentin bondingas an array. J Dent Res 1999;78:699-705.

20. Samsfi S, Van Noort R, Do dentin bond strength tests sefve auseful purpose? J Adhes Dent 1999;1;57-B7.

21. Van Noort R, Norcczi S. Howard IC, Cardew G. A critique ofbond strength measurements. J Dent 1989; 17:61-67.

22. Versiuis A, Tantbirojn D, Dougias WiH. Why do shear bondtests pull out dentin? J Dent Res 1997:76:1298-1307.

23. Watanabe LG. fviarshaii GW. Marshaii SJ, Dentin shearstrength; Effects of tubuie orientation and intratooth iocation.Dent Mater 1996:12:109-115.

24. Voshikawa T, Sano H, Burrow MF, Tagami J, Pashiey OH. Ef-fects of dentin depth and cavity configuration on bondstrengths to dentin. J Oent Res 1999:78:898-905.

25. Yoshiyama M, Sano H. Ebisu S, Tagami J. Ciucchi B, OarvaihoRM, Johnson MiH, Pashiey DH. Regionai strengths of bondingagents to cervical sclerotic dentin, J Dent Res 1996:75:1404-1413.

26. Yoshiyama M, Oarvaiho RM, Sano i-l. Homer JA, Brewer PD,Pashiey DiH. Regicnai bond strengths of resin to human rcotdentine. J Dent 1996:24:435-442.

27. Ycshiyama M, Matsuo T Ebisu S, Pashiey DH. Regionai bondstrengths of self-etching/seif-priming adhesive systems. JDent 1998:26:609-616.

28. Zhang Y, Agee K, Nor J, Carvaiho RM. Sachar B, Russell OM,Pashiey DH, Effects of acid-etching on the tensiie propertiesof demineralized dentin matrix. Dent Mater 1998:14:222-228.

Vol 1, No 4, 1999 309

ORAL HEALTHfor the Orthodontic Patient

Siegward 0. Heintze. Paul-Georg Jost-Brinkmann,Christian Finke, Rainer-Regioald Miethke

This booi< focuses on practicai, preventiveoral hygiene measures for the orthodontic

patient. The authors emphasize patient educa-tion and motivation, as well as preventivetechniques, with the goai of optimal orthodon-tic results. Also presented is a fundamentaianalysis of the detailed factors involved in thedeveiopment and prevention of caries andperiodontitis in the orthodontic patient.

Using this book, the entire dental team candevelop individuaiized preventive programs forpatients with orthodontic appliances.

160 pp (soßcover),i 70 iiius ¡most in coior):ISBN 0-86715-295-8:US $5B/S24

Oral Healthfor

Orthodontic Patient

Chapter I Effects of Orthodontic Treatmenton Oral Health

Chapter 2 Evaluation of Oral Health andMeasurement of Risk

Chapter 3 Professional Measures forReducing Oral Bacteria

Chapter 4 Home-Care Measures forReducing Oral Bacteria

Chapter 5 Pharmaceutical Adjuvants forPreventing Caries and PeriodontaiDisease

Chapter 6 Systematic Program for PreventingCaries and Periodontai Disease inOrthodontic Patients

T o O R D E R

Call Toll Freeor Fax

1-800-621-03871-630-682-3288

Quintessence Publishing Co, IncVisit our web site [ittp://www,quintpub.oom