CA2172703A1

CA2172703A1 - Method for making dental restorations and the dental restoration made thereby

Info

Publication number: CA2172703A1
Application number: CA002172703A
Authority: CA
Inventors: Sylvan S. Stern
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-03-27
Filing date: 1996-03-26
Publication date: 1996-09-28
Also published as: US5549476A

Abstract

The present invention relates to a method of making dental restorations and the dental restoration made by the method including temporarily repairing a tooth area to be restored to desired final shape, taking a first impression of the tooth area to be restored, preparing the tooth to be restored and forming a second impression within first impression with material that is non-adherent to the first impression material. The first impression and the second impression are separated. The second impression is scanned to obtain a digital image of the final restoration.

Description

03~2B~ TUE 10:5~ F~ B10 539 5055 KOHN & ASSOC. 1~005 P-30~ ~Stern) -1-J11~3TEIOD FOR lL~CING DISNTIU. RlSSTO~ATION~
A~D TH13 D~JTAI~ r~b~Ol~A~TON ~ rL Y

T13C}~IICAI, p~T.n Thi~ inYen~ion ~elates to a ~.ethod of ma~ing dental re~torations and the restora~ion made thereby.

r~rn~n~ OF T~ INVENTIO~
Making den~al restoration~ is important i~ ~a~y situation~. First, huma~ ~eeth are subject to naturally occurring bre~kdown~ such as decay and wear. Decay will no~mally be ~Grrected through ~5 ~em~-permanent mean~ ~uch a~ filling~ and the llke.
Howe~er, after numerou~ year~, d~ca~ can re~ch a point where restoration of the tooth through an inlay, onl~y or ~rown be~ome~ neces6ar~.
Another situation in which a dental reatoration ie important i~ where an accldent involvin~ a blow to the mouth re~ult~ in ~hips, crack~ and/or break~ of the tooth. In ~heae ei~uations, the patient not on~y re~uire~ rclief from the dis~omfort a~sociated with th~ dental ~5 injury bu~ o deeires to hava the injured too~h or teeth r~turned to their pre-accident appearance.
~nce again, a ~storation in the form o~ an i~lay, ~nlay or ~rown i~ nc~e~ary.

03/2~ TtTE 10: 5~ F~ 810 53~ 5055 ROE~ & ASSOC . b~ 00~

P - 3 O 2 ( Stçrn) - 2 -Using ~onvention~l mea~s of preparing re~toration~ i~ o~te~ time ~on~uming for both the denti~t and patlent. Generall~, ~ore ~han one visit by the patient i~ nece~ary. The fir~t visit en~Ails preparing the tooth or teeth ~or re~toration and fittihg the prepared tooth~teeth with a temporary ~ub~titute until delivery of the final restoration. ~uring this vi~it, final impreR~ion i~ taken a~d a working model i~ prepared with individual t~th ~pArated and inde~e~ to be able to be preci~ely rea~embled. The model teeth are c~eful}y trimmed to indicate th~ m~gin~ o~
the final re~to~ation. This trimming preferably is ~ne by the dentist. The model is then used by a dental lab technician who i~ usually lo~a~ed in remote den~al laboratory to fa~ricate the fin~l reetoration. Thi~ procedure u~ually take~ two to three weeke to be fini~hed, a~ least in part due ~o the time involved in firing a~d casting porcelain.
zo Porcelain i2 a material commonly u~ed in m~king dental reotoration~. There are ~ultiple ~teps and each step introduced inaccuracie~.
Once the dcnti~ rec~i~es the flr.al reetoration back in ~he ofice fro~ the laboratory, the patient retu~n~ for ~other appointment. Thi~
appoint~ent involvee ~emovin~ the ~empor~ry ~ubstitute and then adju~ting and p~anent 03/2~ T~tE 10:57 FA~ 810 5~ 5055 E~OE~ & ASSOC. 1~007 p-3~ (Stern) ~-placement of the final re~to~ation. During thi~
appointme~t final adiustmen~ to accommodate chewi~g m~tions of opposing teeth are perfo~med ~y the ~enti~ the patient'~ mouth an~ then the re~toratio~ h~s to ~e poli~hed a0ain.
COl ~n; ~ation with a 1~ technician a~ a remote lab frequently i~ imperfect and the restoration rec6ived i~ not ex~ctly what WAS
expected. Thi6 require~ repeating certain ~tep~
which ~ere already take~ re~ulting in fru~ration ~or both denti~t and patient.
Fur~her~ore, certain procedu~e~, ~u~h as fitting ~ crown under a parti~l denture ~la~p th~
already exi~t~ i~ extre~ely inaccurate u~ing ~ny exi~ting method. In fitting a crown ~nder a partial denture claep, the denti~t i~ requir~d to ~pend a co~si~erable amount of time in cont~uring and ~itting the re~toration in regard to the other gur3::'01~n~i n~ and opposing ~ee~h. Thi~ problem i3 20 resolved with the method belng pre~ented. Beside~
the time involved, when a crown doe~ not exactly fit the existinSr partidl denture clasp, ~he partial d~n~ure wlll not seat properly and thi~ in turn will di3rupt the patient's occlu~ion and lead to fur~her pathology.

03f2~ TIJE 10:57 FA~ 810 5~ 5055 ROH~ & ASSOC. Ial008 P-302 tS~ern) -4-Recentiy, computer reconstru~ion of dental re~toratio~ ha~ beco~e commercially fea~i~le. ~ene~ally, the~e 6y~tem~ involve a~
op~ical reader which generate~ a computer-r~ad si~na~. Siemens~ a~d Sopha~ CAD/CAM ~oth have commercially ~vaila~le ~yotem~ which optically re~d tooth area~ in conjun~tion witk dental recon~truction. Sopha~ u~e~ the optical ~mpression syste~ as ~l~clo~ed in United St~te~ Patent No.
4,611,Z88 to ~uxe~ et ~1.
The use of op~i~al impression ~y~tem~
greatly reduces the amount of time involved in preparing a restoration ~ ~ompared with ~onvention~l methcd~, but still ha~ ~everAl drawbacks.
~ he 8ieme~0 recon~truction ~y~tem eliminates the requirement o~ a model by using optical impression~ m~de by a specially designed camera. The camcra i~ u3ed in the mouth ~o read the contour of the tooth. Using ~he çamera in the mouth results in a certain amount of inaccuracy due to moi~ture in the mouth and on the too~h ~urface, u~e of an imagin~ powder over the prepare~ tooth, the pre~en~e of the tongue and diff iculty in 2~ manipulating the çamera in area~ further b~ck in ~he ~outh. In addi~ion, thl~ method doe~ not record the oppo~ing tooth ~nd cannot fit 03~2~ TUE 10:57 F~ 810 53~ 5055 I~OHN & ASSOC. [~oo~
.

P-302 (stern) -5-re~toration ~o a pa~tial denture clasp that already e~ist~. A~ a re~ult, the re~toration may require ~xten~ive co~to~ring ~y the dentist ~efore the re~toration i9 properly fitt~d. As previou~ly di~cu~ed, ao~ouring iB a time con~umin~ ~tep.
~ he Soph~ Bioco~c~pt0 CAD/CAM iQ
dif~erent from the Siemens~ system in that it requires a working model be~ore the reDtoration is c~rried out. This ad~d step increAse~ the time to lo make and the expen~e o~ ~he final re~tor~tion. In addition, t-he Sopha Bioconcept~ tem does not r~cord the oppo~ing teeth. Rath2r, this sy~tem fabrica~es a tooth with ~ ~extbook morphc~o~y and th~ denti~t ~akes modlfica~ion~ on a c~puter screen and the model an~ in the mou~h to ~u~tomize the final de3ign. The Sopha Bioconcept0 ~ann~t fit a crow~ to a partial denture ~la~p~ that alxead~
exi~te.
~ike the Soph~ ~y~tem, United States ~0 Patent No. 4,324,546 to Heitlln~er et al. alRO
requires a m~del. Thi~ patent describe~ a method of manufacturi~ dentures, wherein a prepared too~h stump is repro~uced a~ a working model. The rep~oduction of the tooth ~tump is a~complished electxo-optically to produce siyn~ls which are fed ~hrough a computer whiah in turn ~erates a milling 03/2~/9~ TUE 10: 57 FA~ 81~ 53~ 5055 KOHN & ASSOC . I~b O10 P-302 tStern) -6-mA~h1ne. Thi~, like the S4pha~ method, entails the u~e of a working ~odel.

Eg~P~Y OT TEE INVENIIO~

The pre~ent lnvention relate~ to a ~ethod of makin~ dent~l re~toration9 i~ludiny the step~
of t~kin~ a fir~ impres~ion of the tooth area to be re~tored. The tooth is then prep~red to be re~tored and a second impra~ion is formed within ~he fir~t impreasion. The fir6t and ~econ~
impres~ionR are made from material~ that are non-adherent to e~ch o~her. The ~irst impre~sion is separated ~ro~ the ~econ~ impres~i~n and the ~eco~d impre~sion is scanned to obt~in an image of the final rertoration~ with ox without the use of a model.
It is the g~al of the pre~ent invention to eliminate the need for the e~n~ive o~cl~sal 2~ contouring of the final re~toration which iB
re~uired with the u~e of an opti~al impres~i~n ~y~tem in makin~ de~tal re~toration3 without con~ideration o~ opposin~ teeth. It is also a goal of the pre~ent in~ention to make 3ption~1 the requi~e~ent of a worki~ model ~uch aE i~ required in the Sopha~ sy~tem and conven~ional lost w~x technique. ~urthermore, it i alEo a ~oal to be 0~2~ TUE10: 58 F~ ~10 53~ 5055 KI~IN & AS~OC . 1~1011 .

P-30;2 (6te~ 7-a~le to $a~ricate cu~tomized ~igng to ~it exi~ing pro~thetic appliance~ ~lready ~eing worn by a patie~t, predictably and accurately.

S FIG~E8 IN 1~ D~2AWINGS

FI~URB 1 ifi the ~chema~ic dia~ram ~howing th~ step~ utillzed in the method of ~he pra~nt invention;
FI~RE 2 i~ a drawing of the firYt impre~ion of the fUll ~haped tooth ~hat w~
t~ arily r~tored to de~ired final ~hap~;
FlGUR~ 3 is the ech~matic drawing of the ~econ~ impre3~10~ within the fir~t i~pre~ion over the tooth cut for a crown; and FIGURE 4 is ~ drawing of ~he ~econd impre~ion in the sh~pe of a c~own after it ~a3 been ~eparated f~om the f ir~t impree~ion.

nT~aTTr~n D~SC~IPTTON OF TH~ ~NV~NTION

The method of the presen~ invention is ~chem~tically ~hown ln Yigure 1. The first ~ep in making ~he den~al re~oration i~ temporarily ~S repairing, i~traor~lly, any f~ctured areae or malformation~ o_ the tooth lo. The rep~ir 12 pl~ce3 the tooth lo in the desi~e~ shape of the 0~,'2~ T~TE 10:58 F~2~ 810 5J~ 5055 ROHN & ASSOC. b~l012 P-302 (Stern~ -8-~inal re~to~ati~n. This can be accompli~hed with ~ariou~ materi~l~, which are not ne~e~rily ~trong enough $or long term wear. A cement filling material ~uch a~ ~C Mira~le Mix, a~ailable from GC
Corporatio~, Tokyo, Japan is a good ex~mple of co~posite restorativ~ mat~rial. Anoth~r accepta~le m~e~ial i~ Kerr Herculi~. The next ~tep i~ to ta~e ~n impreseion of the tooth ar~a to be restore~. Thifi lmpression i~ made by u~in~ ~n impressio~ tray 14 de~i~ned to take oppo~in~ teeth at the ~ame time ~prefe~ably Tri-Bi~e¢ tray~ 14 a~aila~le from Dir~Ct D~ntal Servi~, La~in~, Michi~an). The~e ~raye come in various size~ to ac~o~mo~ate any location in a mou~h. A hydrophilic ela~tomeric materl~l 16 made from a polyvinyl siloxane, pre~erably Repro~il Quixx~ Pu~ty and light body wa~h is placed in ~he tr~y 14. Reprosll Quixx~ Putty is available f~om the L . ~ . Caulk Divlsion, Den~2ply International Inc., Milford, Delaware. The ~ray 14 alon~ with the elastomeriç
ma~erial 1~ are plased into the patient'2 mouth o~er the area of the tooth tha~ will be restored ~Figure 2). The t~y ~4 is left in the ~outh until the m~teri~l 16 set~, which generally takes abou~
fi~e minutos. ~e tray 14 i~ then removed from the mouth and the re~ulting impre~sion is called the fir~ impr~ ion 18 .

03~26J~ T~ 10:58 FA~ ~10 53~ 5055 ~o~ & ASSOC. ~01~

P-302 ~Stern) -g-~ ext, u~ing a medium grit diamond chamfer ~u~ ~u~h a~ B~a~seler~ 5897K i~ a high speed drill, ~he cervical margin 20 i~ shaved about one millimeter to ~e~e.~t a build-up ~f hydraulic pres~ux~ during a iater procedure. Bra~el~r~
in~t~ument~ are a~ailable from Braeseler USA, Savannah, G~orgia.
The tooth 10 i~ prepar~d and soft w~x tdental utllity w~x) i8 u~ed to block out in~erpr~ Al undercuts and tri~med a~ needed.
A se~ond imp~es~ion Z2 i~ then taken.
The ~eçond impres~ion Z~ i~ preferably made utiliziny a low-~hrinkagc low heat relea~ing acrylic 24 ~hur~in th~ a~rylic i8 an Alky~
meth~crylate, includi~ Ari~tocrat HTC~ self cure re~in ~ailable from Health~o ~nc., Boston, Ma~sachu~ett~. The material~ u~ed in the fir~
i~pre~sion }~ and second impre~ion a2 are non-adherent to each other. Al~ern~tively, the ~e~ond impreæ~ion 22 can be made from a ma~erial 16 that doe~ have a tendency to adher~ ~o the first i~pre~lon 18 material. In thi~ e~ent, a Repar~ting materlal such a~ Modern Foil avai~able from Modern Materiala, St. ~oui~, Mi~sou~ u~ed ~5 to çoat the first impre~ion to prevent ~dherence be~ween the fir~ 18 ~nd second ~a impre~ion. The ~cond impres~ion 22 i~ made by mixi~g the ~ecsnd 03f2~ T~ 10:5~ FA~ 810 53~ 5055 ~O~T & ASSOC. ~014 ~ Y-30~ ~Stern) -10-i~pres~ion material 24 to a free flowing con~i~tency and injec~ing it with an impres~ion ~yringe around the prepared tooth 26. In the e~ent non-adherent material ~uch a~ the Ari~tocrat H~C~
5 i~ used, the ~aterial i~ placed diractly in~o the first ~ ion 18. If an adheren~ material is u~ed, the 6eparating ~aterial i9 applied to the fir~t impre~sion lB and allowed tc dry prior to filling the fir~t impre~6ion 18 with the ~econd 0 impre~ion 24 materi~l in the site of the prepared tooth ~. The flrE~t impre~siorl lB now ~on'caining the second impreJ~lon materlal 24 in the area of the prepared too~h i~ then pl~ced o~er the tooth 2~
I -k- ng certain to sea~ it to fit o~er the adiacent teqth ~Figure 3). ~hc patie~ i8 then dlrect~d to bite down. The ~irst impressio~ hus aeated ~ the exact ~o~ition it was in when it recorded the prepared tooth 1~ before it wa~ cut. A~ a re~ul~, the second impre~io~ ~aterial 24 f ills in the gap that resulted from ~utting the tooth ~.
The exact shape o~ the prepared tooth structure i~
thu~ ~ep~od~ced in the second impre~s~on ~aterial ~4 which i~ cal~ed ~or our purpo~e~ the second impre~eion mold, generally ~hown at 28. The ~econd impre~slon mold 28 has the Ahape o~ the final re~to~ation but i~ a non-durable m~terial~ ~h~
seco~d impreQ~ion mold 28 has ~he external ~hape of 03~2~ TUE 10: 5~ F~ 810 5~ 5055 ~OHN & ~ SSOC . Eb 015 P 30a (Stern) the precut tooth 10 and the inter~al ~hape of ~he cu~ too~h 2~. It i~ tri~ed intraorally more rap$dly th~ al reotoration ma~erial 24 b~cau~e it i8 ~uch ~fter.

The ~econd imp~e~ion m~terial i~ a~lowed to harden and the~ th~ ~ray 14 i~ ~e -vcd from the mouth. The Ari~tocrat HT~ har~en~ in about seven minute~ and the tray 14 with the fir~t 1~ and seco~d 24 impre~ion material may be removed fro~
the m~uth. The ~econd impres~ion mold ~8 will he found eith~r on the tooth 2~ or inside the ~ir~
impre~sion ~aterial 24. It is ea~ily popped o~t of the fir~t impreesion 1~ or lifted of~ o$ the tooth 26 at thl~ time. After isolatin~ the ~econ~
impre~sion ~rom the ~old 28, any ~la~h material is trimmed off. Using l~x magnification a~d a high ~eed drill wi~h a fini~hing bur, such as Braæ~eler0 H4~, the margin~ ~re refined to a clear.
fini~hlng line. The second impr~A~ion is replaced over the tooth 2~ and the occlusion i~ adjusted in the mou~h. The ~econd impression mGld 28 i~ shaped to ~ccommodate chewing mot$ons and to appear e~th~tically pleasin~. The æecond impreesion mold ~S 28 i~ th~n remo~ed from the mouth, ~ixed to a plat$ox~n of a digitizer and then æcanned with a laser, optic~l, or mechani~al ~c,~nner de~igned to 0~2~ TIIE 10:5~ FA~ 810 539 5055 ~OHN' ~ ASSOC. ibOlo . .

P-302 ~Stern) -12--digitize three-~imen~ional ~urfaces to obtain an image o~ the fi~al re~toration. In the case of a mechanical pro~e which use3 a mechanical probe to "~eel~ ~he ~urface~ and contours of the final pro~thesi~, ~uch a~ ~he ~ynaPath CNC (Autocon Corp.~. The eecon~ impre~Ai~n i~ physic~lly contacted ~y the probe con~erting the ~echani~al mo~G,- t o$ the probe i~to a digital im~ge of the fiecond i~press~on. The "second impre~ion", ha~
already been checked in the mouth, at thi~ poin~, and dete~mined to be esthetically ~haped and o~c:lu~lly comforta~le.
~ ft~r obtaining the ~Isecond impres~ion~
22 l~ acrylic, a model i~ poured ~ing the impre~ion obtained. Thi~ model is used to ma~e the ~rown or br$dge ueing stAnd~d de~tal lab procedure~ known to those ~kil led in the art. The b~idge or crown is then ~e~o~cd from ~he model.
Then the acrylic 'l~ecoh~ impres~i4n" ~ re~eated on the model and th~n thi~ combina~ion i~ tured o~ mounted to the platform o~ the sc~nner.
S~nn~ n~ of the other contour~ ie done. The 'l~e~d ~ ,,re~sion~ then removed and the lab ~abricated crown or brldge is placed on the m~del.
a5 The milling portion of the CAD/CAM ~y~tem then ahapes the ~uter contou~s ba ed on the di~itized o~/2~a~ T~ 10:5~ FA~ 810 533 5055 K~ & ASsoc. ~017 2l 72703 P-302 ~Stern~ -13-in$ormation o~tained fro~ the 1l ~econ~ impre~io~
2~.
Alternatively, u~ilizing the sy~tem set ior~h above, the ~u~et~ucture of ~he ~.odel ~an be made of acrylic material, And then scann~d using a similar procedur~ fixturing the ~odel to the ~c~nnlng platform a~ w~ described for ~he ~'~econd impre~ion" 22 obtained irom the mouth.
The electronically generated di~ital i~a~e i~ then used by a computer to mill the final restoration. Th~ final re~toration.i~ a duplicate of the ~econd impres~ion 22 but i~ made from a material which h~ ~een de~igned to be u~ed f~r esthetic re~torati~ns such a~ Dicor MCG~ a~ailable from elther Corning or D~ntæply. Thi~ m~teri~l i5 already in clinical use and has ~een shown to function ~ery well for the~e appli~atio~8. The final restoration can al~o be made ~rom variou~
metals or ceramic~ or other re~to~tive ma~eriale.
The finished restoration is now ready to be cemented in the patien~'s ~ou~h u~ing conventional dental ~ementing procedure~ known to tho~e ~killed in the art.
If a parti~l denture wa~ worn during the fir~t i~pression and was incorporated in~o the firet impreosion and left ln&ide, the æecond impre~ion automatically precisely fit~ the p~rtial 03J20~ T~E 10: 5~ 810 5~ 5055 ROHN & ASSOC . Ialol8 `~_ P-302 (Stern) -14-denture cla~p in a functional po~ition that ac~ommod~te~ the patient'~ chewing pres~ure. Thi~
i~ ~ecau~e the patien~ was bitin~ ~own with the partial denture in pla~e during both impre6OEion~, ThH above de~orip~ion can be u~ed for making a ~ingle re~to~ati~n. In order to ~eplace mis~ing teeth with a fixed bridge, the ~bo~e-described ~ethod can be modi~ied. Thu modification ~equire~ fir-~ m~king a plaster model of the pa~ient'~ teeth. The shape of the mis~in~ tooth or teeth i~ initially formed on the plaster model u~lng a compo~ite material. The compo~ite material is a non-durable repla~ement. ~o~; ng agent~ and small pin~ are then uced ~o place ~he non-durable replacement tooth in he ~outh. Fi~al ~hapiny of the non-durable replaceme~t i5 done intraorall~.
Xt, the proced~re~ en~merated a~ove for creating a dental restoration are ~ollowed . A fir~t l~pre~sion is ~de of the tooth and ~djacent teeth.
Then the teeth adjacent to thi~ xepl~ceme~t ~re Yhaped for crowns and the replacement tooth j UBt formed i~ removed from the mouth. Next, a ~econd imp~assion i~ taken to obtain the bridge ~orm for co~pu~e~ repxodu~tion. An all metal gold bridge can thu~ b~ formed. Also a metal substructure for co~ventional ~tal/ceramic bridge~ can also be formed. I~ thi~ ca~e, a çer~mi~t can apply a 03~20~0 TUE 10:5a PA~ 810 5~ 5055 I~OHN & ASSOC. I~lola 21 72~03 P-302 (Stern) -15-ceramic coating over the metal ubstructure u~ing conventional method~. After placing ceramlc coating, the ~ridge thu~ made can be re~i~ed by the ~AD~CAM to ~uplicate the ~hape o~ the "second S i~pre~ion". ~hi~ method reduce~ the time needed and ~he co~t as~ociated with the formation of brldges. Further, th~ bridge and teeth are ~ub~ect to le~ di~tortion ~hile bein~ fabricated.
There are ma~y b~nefit~ of the method 0 ~e~cxibed. Firet, there i~ no ~e6d to pour models, i~luding u~ing an articulator to relate the oppo~ing teeth, ~epar~te the teeth, and then either ~orm the re~toration in wax or porcelain by ucing conve~ionhl mechan; c!al me~ns or }~y optically S ~can~ing the model.
Effi~ien~ AlgO another ~enefit resulting fro~ the pre~e~t ~aterial. The ~ime invol~ed in making ca~ting~ or ~irin~ porc~lain in an oven i~ elimina~ed.
Using the 3econd impression for 6cannin~
purpose~ out~ide of the mouth el iminate~ many of the dr~wback~ ociated with i~raoral op~i.cal impre_slone. For example, the inac~uracies re~ultin~ from moisture pre~ent along ~he tooth ~urf~e, dif~iculty in manipulating ~he camera in area~ further back ln the ~outh, or the fact that teeth may be ~ained ~y old ~eY~vratfons an~ c~n ~e 03~2~a~ TUE 11:00 FA~ 810 5~ 5055 KOHN & ASSOC. 0020 `~ P-3 02 ~Stern~ -16-m~read by op~ical imaging equipmen~ are eiimillated in m~chanical ~c;~nnin~ of the ~econd impre3sion mold .
The ~enti~t ha~ much more control of the 5 shape of the ~inal resto~a~ion th~n ~i~her der~n~ i n~ on anoth~r individu~l to fabricate a re~toration qrho doe3 not have the benef it of looking at the ~hole face or deE~fl~ng on a m~ch;ne ~oyLammed to f~bricate ideal tooth shape~ ho~t 10 any consideration o~ the individual ca~e.
Den~ist6 can see th~ fin~l shape in ~he mouth and no longer need to wond~3r how thel modifi~ations made c~n the computer 6cr.-en du~ing th~ d~si~ing the reetor~tion with computer aided S milling is ~oing to appe~r in the mouth.
Patients no longer re~uire te."~o~ary re~torationc that ~eed to la~t many weeks and which can potentially fracture in the interim and cause gin~iv~i irritation and/or cauee ~hifting o~ ~he 2 o teeth in thc in~e~im .
The ~bility to ~t restoration~ ~o exi~tlng pro~theseæ precisely and rellably, In addition, the ~eco~d imp~e~ion ~hape incorporatee in exac~ detail the relationship o~
oppo~ing teeth with ~11 jaw mo~ement~ t~ken in~o accour~. All the~e factor~ yield a flnal restora~ion which ~ay be properly f itted wi~h ~ar OJ/2B~ TUE 11:00 FA~ 810 539 5055 ~OE~ & ASSOC. lzlo2l '~ P-302 ~stern~ -17-~e~ contouring required by the dentist. This is time and cost ~ving to the denti~t and the pati~nt .
Tha irlven~ion ha~ been de~cri~ed in ~n 5 illu~trated n~nner, and it i~ to be understood th~t the terminology which ha~ be~en used is intended to ~e in the na~ur~ of word~ of ~e~crip~ion rather th~n of }imit~tion.
o~viOu~ly, many modif ic~tion~ and lo variation~ of the pre~ent in~rention are pos~3ible in light o~ the above teachin~. It 1~;, there$ore, ~o be un~eratood that withln the scope of the appended cl~im~, ~he lnvention may be practic~d otherwise tha~ ~ ~pe~i~lcally d~crlbed.

03~2~a0 TllE 11:0~ FA~ ~10 5~ 5~J55 KOHh' & ASSOC. 1~022 2i 72703 P-30a ~Stern) -18 -~.rK~usNCX~ CITED

Cyberware Color 3D r~igitizer (Brochure) t:yberware ~ew Productb (Brochure ) 9iemen~ CEREC Coml?uter Roconstruction ~Brochure) Sop~a0 3io~nc~pt, Inc;~. ~opha~ CAD/~
(~roc:hu~e) R~kow et al., "CAD/CAM for dental restoration~ -some of the cu~iou~ challenges l~ IEEE
'rAn~tiono on Biome~licAl Enar ., Vol . 38 , No .
4 (April, 1g91~.

Claims

What is claimed is:

1. A method of making dental restorations comprising the steps of temporarily repairing a tooth area to be restored to a desired shape of a final restoration, taking a first impression of the tooth area to be restored, preparing the tooth area to be restored for restoration, forming a second impression within the first impression with material that is non-adherent to the first impression, separating the first impression from the second impression and scanning the second impression to obtain an image of the final restoration.

a. A method of making dental restorations according to claim 1 wherein said scanning step is further defined as mechanically obtaining an image of the second impression.

3. A method of making dental restorations according to claim 1 further comprising the steps of adjusting the margins after forming the first and second impressions.

4. A method of making dental restorations according to claim 1 further comprising using a computer to generate at least one graphic representation of the final restoration.

5. A method of making dental restorations according to claim 1 further comprising using computer controlled milling to create the final restoration.

6. A method of making dental restorations according to claim 1 wherein the second impression is a replica of the tooth area to be restored in its original form and as prepared for restoration.

7. A method of making dental restorations according to claim 1 wherein the first impression is made with an elastomeric medium.

8. A method of making dental restorations according to claim 7 wherein the elastomeric medium is a polyvinyl siloxane.

9. A method of making dental restorations according to claim 1 wherein the second impression is made from an acrylic substance.

10. A method of making dental restorations according to claim 9 wherein the acrylic substance is an alkyl methacrylate.

11. A method of making dental restorations comprising the steps of temporarily repairing a tooth area to be restored to a desired shape of a final restoration, taking a first impression of the tooth area to be restored with an elastomeric medium comprising polyvinyl siloxane, preparing the tooth area to be restored for restoration, forming a second impression with an acrylic substance, the second impression being formed within the first impression, separating the first impression from the second impression, scanning the second impression for creating an image of the restoration, using a computer to generate a graphic representation of the restoration, and using computer controlled milling to create the restoration.

12. A method of making dental restorations comprising the steps of temporarily repairing a tooth area to be restored to a desired shape of a final restoration, taking a first impression of the tooth area to be restored, preparing the tooth area to be restored for restoration, coating the first impression with a separating material, allowing the separating material to dry, forming a second impression within the first impression, separating the first impression from the second impression and scanning the second impression to obtain an image of the final restoration.

13. A method of making a fixed bridge for replacing mixing teath by forming a plaster model of a patient's teeth including missing teeth, using the model for forming the shape of the missing teeth with compooite material thereby yielding a temporary restoration, placing the temporary restoration of the missing teeth in the patient's mouth, forming a first impression of the temporary restoration, preparing teeth adjacent to the temporary restoration for final resroration, removing the temporary restoration from the mouth, taking a second impression of the area where the temporary resoration was located including the adjacent teeth to obtain the form for computer reproduction of the fixed bridge.

14. A dental restoration made by the method of taking a first impression of the tooth area to be restored, preparing the tooth area to be restored for restoration, forming a second impression within the first impression, separating the first impression from the second impression and scanning the second impression to obtain an image of the final restoration.