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Anterior Single-Tooth

Implant Restorations

Steven

Lewis, DMD

he opptication af impiant dentistry to the treatment of partial edentulism

has necessitated the development afnew components and techniques.

his article reviews the various systems and techniques u sed to fabricate

success fui anterior single-tooth implant restorations Placement techniques

for nonsegmented, sarew-retoined abutments: segmented, screw-retained

abutm ents: and segmented , cement-retained abutm ents ore illustrated.

IntJ Periodont Rest Dent

1995;

15:31-41)

•Private Practice,

San

Antonio, texos.

Reprint requests; Dr Sleven Lewis, 7 Inwood Point, San Antonio,

Texas 782d8.

The successful t reatment

edentu l i sm wi th osseo in t

gra ted prostheses hos iead to

revolution in dentistry. With th

success ul t imateiy came th

desire to appiy the same tec

noiogy to the partiaiiy edent

lous popu ia t ion as

we

i-iowever, many different ciinic

chaiienges were encountere

when this adaptation was in

t ia i iy at tempted, ond i t soo

b e c a m e e v i d e n t t h a t n e

components and techn ique

were necessary to overcom

some of the probiems uniqu

to the par t ia i i y edentu iou

pct ient , Ohe of the greate

cha i ienge s was tha t o f th

anterior singie-impiant restor

tion and the abiiity to achiev

a stabie and esthetic impia

restorat ion. Var ious syste

designs and restorotive tec

niques used to create succes

fu i an ter io r s ing ie- imp ia

restorations are reviewed in th

articie.

One ciassification divid

impiant components and

tec

niques into those restorotio



3

Fig 1 Nonsegmented single-tooth

implant restorations UCi-A abutment)

ñt directly to the implant fixfure and

must engage the hexagon of the

impiant tar antiratation

that are cement-retained and

those that are screw-retained,

Anather classificatian relates

to

fhe averall design, either non-

segmented Of segmented. The

nonsegmented design consists

of

a

restoration that connects

direofiy

fo

the impiant fixture,

while the segmented design

inciudes

a

restoration that fits

over

a

fitanium abutment. The

categories of single-tooth tech-

nique described in this artioie

are 1)

the

nonsegmented

sorew-retained abutment,

(2) the segmented screw-

retained abutment and

(3)

the segmented, cement-

retained abutment. Examples

of fhe nonsegmented, sorew-

retained,

and

segmented,

cement-retained types will

be

of the same clinicai restoration

to allow oomparison.

Nonsegmented, screw-

retained restoration

The nonsegmenfed restoration

connects direotiy

to the

implant fixfure. This technique,

introduced

by

Lewis

et

al,

is

populariy referred

ta

as the

UCLA abutment. Far single-unit

UCLA abutment implant

restorations,

it

is criticai to utilize

implant fixtures that cantain

hexagcns

on

their coronal

aspect. Because the restoration

is begun directly at the impiant

fixture, it

is possible

to

incorpo-

rate

a

hexagon within the base

of the restoration

to

engage

the hexagon

at

the implant

(Fig

1 ). With

this connection, the

restoration shouid exhibit the

antirotation neoessary for a sfa-

bie single-tooth restoration.

Also,

with proper implant coun-

tersinking,

beginning

the

restoration

at

this level shouid

allow adequate vertical space

to develop

a

natural and grad-

ual emergenoe prafiie, provid-

ing exceilenf esfhetios and

easy aooess

for

aral hygiene

measures.

With

the

nonsegmented

technique, only screw-retained

restorations are recommen-

ded.

Cementing directly

to

the

implant makes retrievabiiity

and access to the implant itself

quite difficuif,

To tabricate fhe nonseg-

mented screw-retained resto-

ration

to fit

directiy

to the

implant fixture, an impression

coping that fits directiy

to

the

implant fixture must be used.

It

is important that the impression

coping contain

a

hexagonai

base that matches the hexa-

gon

of

fhe implanf. This is crifi-

cai, because fhe tinal restora-

tion must engage the impiant

hexagan;

theretore, the rota-

tional aiignment

of

the hexa-

gon

in

the wori<ing oast must

match that

of fhe

actuai

impianf. When fhe impression

coping is seated intraoraliy

to

the impiant,

a

radiograph

is

necessary

to

ensure that the

hexagons are matched and

compiete seating is achieved.

After fhe impression is made,

a



3

labo rato ry im plon t rep l ica is

connected to the impression

coping and a cost is poured

Fig 2), The lab ora tory replica

must a lso conta in o hexagon

identicol to the implant fixture.

Because the implont fixture

snould ideally be positioned 3

to 4 mm beneath the gingival

margin to create an esthet ic

anterior restoration with a grad-

ual emergence profile, the finai

cast should contain a tiexible

materiai that duplicotes the sul-

cular tissue around the implant

Fig 3). This soft t issue ca st

a l lows the laboratory techni -

c i a n t o f a b r i c a t e t h e t i n a i

res tora t ion w i thout acc iden-

taily altering the soft tissue con-

tours.

Mony technicians prefer

that this materiai be separable

from th e master cast. Thus, as

the restoration is being waxed

and contoured, the soft t issue

mate r i o l may ac tuo i l y be

removed f rom the cast , ideai

emergence prot i les can then

be aftained without being dic-

t a ted by the des ign o f t he

heal ing abutment or subgingi-

val port ion of the impression

coping.

The UCLA abutment inifioiiy

was a piastic burn-out pattern

that connected direcf iy to fhe

imp lanf t ix tu re . One pa t te r n

con ta ined o round base fo r

muit iple implant restorat ions,

wh i ie the o ther conta ined a

hexagonal base for the antiro-

ta t io n necessary in s ing le -

imp lan t res toro t ions . Today

these plastic pafterns may still

Fig 2 An imptanf fixfure onalog is con-

nected to the impression cop ing

before the cast is poured

be uti l ized, or m ach ine d goid

al loy cyl inders may be used.

These fit to the impiant fixtures

as do the p iast ic pat terns.

Fabrication of a restoration w ith

the p last ic pot tern invoives

secur ing fhe pa t te rn to the

implant f ixture repl ioo of the

moster oast and incorporating

it withih the substructure pot-

tern Fig 4). The wox an d p lastic

burn out otter being invested,

resulting in a tramework with o

cast base. The m achin ed cylin-

der would also bec om e part of

the wax substructure, but after

investing,

it does not burn out.

After the wox burn out, o frome-

work is made by casting to the

machined oyi inder. Thus, the

bose of the metal substructure

contains o mochined cyl inder

w i th a mach ined hexogona l

paftern. he adva nta ge of this is

thot the quality of the fit of the

restoration to the impiont fixture

Fig 3 The master oasf contains fhe

implanf tixfure replica wifft the fofation

ol alignmen t of the hexago n identical

to thot of fhe acfuai implant.

The

soft

tissue maferial wiil preserve the soft fis

sue contours during fobricafion of fhe

tinai restoration.

Fig d The UCL abutment burn-ouf

pattern

ñts

direcfly to the implanf fix-

ture and has a hexagonai paftern at

the base that

ñfs

over

f i ie

implant

hexagon. Once secured fo fhe tixture

anaiog the burn ouf potfern will

become parf of the substructure wax

pottern.



34

Fig Tile com pieteú porcelain-fuse d-to-metal restoration

fits directly to fhe top of fhe implont ñxfure matcfiing the hex

of the fixture and is refaihed wifh a titanium alloy screw

fighfened fo 20 Ncm

Fig 6 The nonsegmenfed impiant resforotion replaces the

max iiiary left central incisor with a natural appeara nce.

is always pre de term ined with

the machined cylinder. In con-

trast, the quality of the fit with

the castable plastic pattern is

more technique sensit ive and

di f fers f rom restorat ion to

restoration. In any case, no ma t-

ter w hich tech nique is utilized, it

is always best to check the fit of

the res tora t ion to an ac tua i

implant tixture microscopically.

Discrepancies may be over-

come with a milling instrument

when necessary.

Use of alioys with at least

50

go ld hos be en rec om -

mended with the UCLA abut-

ment technique, ' This should

minimize the potential for gai-

vanism or corros ion at the

implant - res toro t ion junc t ion .

However, the long-term ramifi-

cations of placing two dissimilar

metals at this level are st i l l

unknown.

Porceloin is ap plie d to the

casting and the restoration is

co m pi e te d (Fig 5) . This f ina l

restorat ion is reta ine d to the

implant fixture with the use ot a

titanium alloy screw tightened

to a force of 20 Ncm (Fig ó).

Rad iographs ore abso lu te ly

c r i t i ca l t o assu re adequa te

seating.

Unless the hexagon ot

the res tora t ion i s per tec t l y

o l igned wi th the hexagon ot

the implant tixture, the restora-

tion vi/ill not be seo ted .

The screw-access channel

is uitimately sealed with gutta-

percha and either amaigam or

resin. If the restorative materia

surrounding the surface ot the

screw-access o pen ing is m etal,

amalgom is p re ter red . I t the

screw -acce ss o pe nin g is sur-

rounded by porcelain, resin is

used. In either case , the restora

tive ma teriai is easily rem ove d

when access to the retent ion

sorew is desired. The gutta-per-

cha protects the heod ot the

sc rew t rom be ing damaged

when access is being gained,

because this material may be

removed w i th an excava to r

rather than a hondpiece.



3

Fig 7 The titanium EsfhetiCane is secure d to the top of the

impiant fixture w ith a pure titanium abutment screw The

external walls of the abutm ent may b e used for antirotatian.

FigB The ¡ mm collar EsfhetiCone abutment wil iallow the

restoration to begin 2 fo 3 mm beneath Ihe gingival margin.

he

restoration has a natural ond gradual eme rgence profile

Segm ented, screw-retained

restoration

Segmented restorat ions may

be cons idered those tha t f i t

over t i tanium abutment cy l in-

d e rs r a t h e r t h a n c o n n e c t

directly tc the implant fixtures.

Thus, the re are var ious seg -

ments to th e restaration.

Advantages of having the

t i tanium abutment include the

ta ct th at the re is now a t i ta-

nium-t i tanium interface at the

leve l o f the imp lan t f i x tu re .

Ga l van i sm and co r ros ion

shou ld no longer be o con-

cern. The interface at this level

is now betw een tw o mach ined

c o m p a n e n t s a n d t h u s t h e

technique sensitivity of a cast-

ing is e l iminated. Also, there

now exists a titanium -soft tissue

i n t e r f a c e . A l t h o u g h s o m e

researchers oons ider the

p o t e n t i a l h e m i d e s m o s o m a l

attachment betvyeen the t i ta-

nium and soft tissue to be an

important factor for long-term

success,^'^ others feel that this

sa-cal led b io logic seal may

minimize pocket depth but will

in no way inhib i t epi thel io l

downgrow th . shou ld t he

implant become mobi le, St i l l

o thers moin ta in tha t o

hemidesmosomal ottachment

to sott tissue is not unique to

t i t on ium and con oc tuo l l y

occur with ceramics or a vori-

ety c t m etal alloys.^ Thus, the

true significance of this inter-

face is somewha t unclear

Ta achieve an acc ep tab le

esthetic result, it is critical that

the restoration beg in 2 to 3 mm

beneoth the mucosa. With the

nonsegmented technique, the

restorot ion begins direct ly at

the im plo nt f ix ture. Wi th the

placement ot a ti tanium abut

me nt, however, the restoratio

must begin closer to the ging

val morgin. Titanium abutment

such as the Esthet iCon

(Nobelpharma) are designe

for subgingival restorations (Fi

7), These abutm ents con ta i

either

1 -,

2-, or 3-mm collars a

the bas e. The restora tion fit

over the abutment down t

the top ot the collar. Thus, wit

the 1-mm titonium collar, th

restorot ion may beg in 1 mm

from the implont fixture. s lon

OS the implant f ixture is pos

t ioned 3 to 4 mm beneath th

mu cosa , the restorat ion ha

adequate room (2 to 3 mm) t

develop o natural and gradu

em ergenc e profile (Fig 8). Wit

a properly positioned implan

the result is the a pp ea ran ce o

a to oth at the gingival margin



36

i 9 The gold alioy cylinder contains an

internal hexagon that engages the

iater

al walls af the Estheti one abutment

Fig 1 a The ¡mpressian coping con

tains an internal hexagan ta prope riy

align the laboratory repiica

Fig IQb The laboratory replica IS

similar to the EsthetiCane abutment

replica use d for muitipie implant

restorations (left) excep t that it con

tains an externai hexagonal pattern

(right) that is necess ary far single tooth

restorations.

Whi ie the Es the t iGone

abutment was or ig inai iy cre-

a ted fo r mu i t i p i e imp ian t

restorations oniy, ^ modifications

have been made to al low i ts

use as a singie-tooth impiant

restoratian. To provide stabiiity,

an ant i rotat ionai des ign was

necessary. The goid aiioy cyiin-

ders that become part of the

wax pattern and then part of

the meta i subs t ruc ture now

conta in an in te rna i hexagon

t h a t m a t c h e s t h e e x t e r n a i

hexagon o f the Es the t iCone

ab ut m en t (Fig 9). The impres-

s ion cop ings and labora tory

repl icas aiso contain hexago-

n a i p a t t e r n s m a t c h i n g t h e

hexagon of the abutment so

that the rotationai ai ignment of

the abutment hexagon is trans-

ferred to the master cast (Figs

10a and 10b).

The technique of fabricat ing

a singie-impiant restorat ion is

fa ir iy s imp ie . i h e ab u t m en t

cy i inde r is ca nn ec te d to t he

imp lant f i x tu re , an d a rad i -

ogra ph is taken to ensure th at

the hexagon of the abutment

base is a i ig ne d prop er iy wi th

the he xag on o f t he imp ian t

f ix tu re , a l i ow ing co m p ie fe

seating.

The titanium abu tme nt

screw is the n t ig hte ne d to 20

Ncm.

The

impression coping fits

over the abutm ent cyiinder a nd

is reta ined vy i th a guide p in.

Because the internai aspect of

this impression c op ing contains

a hexag on matching th at of the

abutment, care must be taken

to ensure proper

seating.

radi-

ograph is often useful to con firm

this,

and the same radiograph

that evaluates abutment seat-

ing may aiso be used to evaiu-

a te t he impress ion cop ing

seating.

The impression coping is

retrieved with the impression,

and t f ie iaboratory abutment

rep i i ca w i th the hexagon is

connected (Fig 11). As with the

UCLA a butm ent an d aii subgin-

gival impiant restorations, a soft

tissue cast is fab rica te d (Fig 12).

The goid ai ioy cyl inder is

s e c u r e d t o t h e i a b o r a t o r y

repi ica and becomes incorpo-

rated wi th in the wax pat tern.

The buccai inci inat ion of thé

imp ian t f ixture is cr i t ic ai with

th is tec hn iqu e, bec aus e th e

restoration wiii co nta in a screw-

access opening on the surface.

An imp ian t ang ied too fa r

faciaiiy wiii resuit in an unac-

cep tab ie faciai screw chan nel.

This is tr ue of th e no ns eg -

mented or UGi-A abutment as

weil. The screw-ohannei open-

ing with the segmented tech -

nique wiii be smaiiet, however,

because the retention screw is

a smaii goid aiioy screw that fits

wi th in the t i tanium abutment

screw. The s eg m en ted t e c h -

nique ut i i izes a iarger screw

th a t is th e sam e size as an

abu tme nt screw.



3

F/g í î (lefr) The

impresión ooping

Is

retrieved with the impression and fhe

at:>utment repiica is connected.

Fig 12 (right) The master oast contains

the hexed abutment replica.

The

soft tis

sue m aterial wiii preserve the satt tissue

contours during laboratory procedu res.

Fig 13 ( left) The compieted porcelain

tused to metai restoration contains the

gold aiiay cylinder with the internal

hexagon.

Fig 14 ( r igM) The tinal restoration is

secured in piace by tightening the

gold aiioy screw to 1 Nom.

A variety of alloys may be

cast to the gaid alloy cyiinder.

as iong as a nonpreciaus aiioy

is av oid ed . The g old aiioy cylin-

de r wou ld be des t royed a t

temperatures h igh enough to

cast th e non precious aiioys.

An infraora l fry-in is not neo -

essary tor the metal substruc-

t u re , because the f i t o f th is

res tora t ion i s p redetermined

by fhe f i t be tween fhe

mach ined go ld cy i inder and

the mach ined t i tan ium abut -

me nt . Porcela in is ap pl ie d to

the metal substructure and fhe

restoration is readied for a clini-

ca l try-in (Fig 13). A t this time ,

the interpraximal contacts are

adjusted,

the occlusion is eva lu-

ated, an d the final esthetics are

deveioped.

The restoration is secured

in p lace wi th a gold a l loy

re tent ion screw (Fig 14). This is

the same screw used to retoin

multiple implant restorations on

the EsthetiCone abutment sys-

t e m . These screws are t ight-

ened to 10 Ncm. Radiographs

are usefu l to evaluate com-

plete seating. As with fhe non-

s e g m e n t e d t e c h n i q u e , t h e

screw channeis are then obtu-

rated wi th gut ta-peroha and

either resin ar am alga m .

The advantage of this seg-

m en te d teohn ique is t ha t a

so rew- re ta i ned , re t r i evab le

impiant restoration that can be

both esthetic and funotionaiiy

sfabie is fabricated. Al though

this is s imi iar to the advan-

tages o f t he nonsegm en ted

restorat ion, the t i tanium-t i ta

nium implant-abutment junc

tion and the titanium-soft tissue

inter face are b iomeohanioa

considerations that are more

similar to the time-tested and

wel l -dooumented oy l indr ioa

titanium abutments used in 15

year olinioai trials. The long

te rm rami f i ca f ions o f fhe

changes infroduoed wifh fhe

nonsegmented technique are

stiii unknown.



38

Segmented, cement-

retained restoration

The CeraOne abutm ent (Nobel-

ph arm a) is a pure t i tan ium

obu tmen f cy i i nde r t ha t p ro -

vides a cem en t retained singie-

to o th restoration^ (Fig 15), The

obutment conta ins coi iars at

the bose just i ike the

Es the t iCone abu tmen t a i -

though 4- and 5-mm collars are

available as well. Thus, the tita -

n iu m C e r a O n e o b u t m e h t

adheres to the b io iogic and

mechanicol pr inc ip les of the

EsthetiCone abutment by pro-

v id ing o moch ined t i tan ium-

titanium interface at the ievei

ot the implan t fixture and a tita-

n ium-sof t t i ssue in te r face

between the t i tan ium co l ia r

an d suicuiarep itheiium (Fig 16).

The f inai restorat ion is

designed to cement over the

CeroOne abutment . Becouse

there is no need for a restora-

tive retention screw, there is no

need fo r on ex terna l sc rew

channe l . The porallel waiis of

the abutment cyiinder provide

exceilent retention. However, if

the abutment sc rew were to

l oosen ,

acce5S to this screw

would be di f f icul t and i t moy

be necessary to sect ion the

final restoration, it is for this rea-

son tha t the a bu tm en t sorew

joint was designed to be tight-

ened to a torce of 32 Ncm. The

retentive strength of this screw

jo in t is ap p ro x im a te l y t h ree

t imes that ot the EsthetiCone

go ld sc rew . This a bu tm en t

screw itself is also m ad e out o f

a differeht materioi than other

a b u t m e n t s c r e w s m a n u t a c -

tu red by Nobe lpha rma . The

CeraOne abutment sc rew is

m ad e ot a g oid aiioy.

The abutment screw must

be t ightened with an electr ic

torque controiier, whioh can be

p r o g r a m m e d t o 3 2 N c m . A

cou nter to rque dev ice is o lso

utiiized to prevent the possibiiity

damaging the bone-impiant

intertace during tightening.

The segmented, cemeht -

retained restorations described

in the fo l iow ing pora grap hs

(both al i -ceramic ond porce-

iain-fused-to-metai) were fobri-

ca fed to rep iace the same

tooth used to iiiustrate the non-

s e g m e n t e d , s c r e w - r e t o i n e d

technique.

The impression coping fits

over the various sized abut-

ments and remains in p iace

through t r ic t ional res is tohce.

Because plastic provides better

frictionai resistance than does

meta l , the impression coping

and the laboratory repiico are

made of plastic. The impression

co p i ng is p ic ke d up in the

impression, and the laboratory

repiioa is inserted into it (Fig 17).

A soft tissue cast is then poured

(Fig 18).

The CeraOne system allows

several prosthetic designs. An

ail-ceramic restoration may be

t a b r i c o t e d b y i n c o r p o r a t i n g

the a luminous ox ide cap: a

p o r c e i a i n - f u s e d - t o - m e t a i o r

even ali-metal restoration moy

be made by Inoorporoting the

gold a l loy cy l inder. Both the

ceromic c o p a nd gold cylinder

are designed to f i t prec lseiy

over the abutment. Thus, when

either one becomes incorpo-

rated in the final restoration, the

restorat ion is ce m en ted onto

fhe abutment cyiinder, seating

to the ievei ot the collar.

The ce ram ic c a p is ava i i -

ab le in tw o sizes, short and toll

(Fig 19), These aiuminous ox ide

caps moy be ground down as

iong as they remain at leost 0,5

m m t h ic k . A d d i t i o n a l c o r e

m a t e r i a l m a y b e a d d e d t o

increase the size of the core

and to prevent excess unsup-

po rte d porc ela in in the t inai

res to ra t i on . The po r ce lo i n

added to the cop to develop

the restorotion must be an alu-

minous oxide porcelain rather

than felspathic porcelain (Fig

20).

The ma te r i a i rec om

m en de d is Vitddur Alpha (Vita

Zahnfabr ik ) , The f ina i a i l -

ce ram ic restoration is the n per-

manently cemented into posi

tion (Fig

21).

Temporary cemen

is not recommended with this

restoration, because fracfure af

t he oe ramic ma te r i a l cou ld

ocour dur ing any a t tempt to

remove the c rown f rom the

paraliel-sided abu tme nt.



39

Fig

5

left)

The

CeraOne abutment

is

o pure titanium abutme nt held to the

impiant fixture with a gold a lloy a but-

ment screw.

Fig

IÓ

right)

The

CeraOne abutment

siiouid allow the testorotion to begin

approximately 2 to 3 mm beneath the

gingival margin.

The

finai restoration wili

be cemented over the obutment.

i

7

left)

The

impression coping

comes out with the impression.

The

plas-

tic laboratory abutm ent replica

is

then

inserted into the impresión coping.

Fig IS right) Tiie mas ter cast contains

the plastic laboratory ob utmen t replica

with soft

tissue

material surrounding it.

Fig 19 The tall ceramic cap

is

placed

ah the master cast

This

ceramic cap

has been mod ified by slight grinding.

Fig 20 The

Una

ati-ceramic restoration

is

fabricated by adding porceiain to

the ceramic cap.

i 2 The

ali-ceramic restoration

is

permanentiy cemented aver the

CeraOne abutment.



40

Fig 22 (ieft)

he

gold alloy cylinder fíts

over the laboratory replico as does th,-

ceramic cap.

his

cylinder allows the

fabrication of a porceiain-fused-to-

metal restoration.

Fig 23 (rigtit) Th e inal estcraflon con-

tains

tfie gold

cylinder

which provides the

fit

of the restorafian onto the abutm ent

The gold al loy cyl inder is

designed to o i low porcelo in-

tused-to-metal restorations (Fig

22),

Similar to the pro pe rt ies

of the EsthetiCone gold cylin-

der , the go ld a l loy cy l inder

bec om es pa r t o f t he wax

pat tern and then part of the

metal substructure. Ultimately

the porce la in - fused- to -meta l

restorat ion contoins this gold

cyl inder as i ts core, al lowing

i t to fi t over the ab ut m en t

(Fig

23).

While a va rief/ of olloys

may be used to c rea te the

subs t ruc tu re , nonp reo ious

al loys are not recommended,

because the gold alloy cylinder

would be destroyed under the

high-temperature condi t ions.

Conventional felspathic porce-

lains may then be appl ied ta

the m eta l subs t ruc ture . The

advantages of the porcela in-

fused - to -me ta l res to ra t i on

inc lude the possib i l i ty of

improved structural integrity as

wel l as the obi l i ty to ut i l ize

tem po ra ry ce men t. It is less risky

to affempt to remove a porce-

lain-fused-to-metal restoration

than ah all-ceramic restoration.

The metal lingual surface also

provides the obility to place o

ce m en t es cop e c han ne l. This

allows the restoration to seat

more easily during the cemen-

tation process and minimizes

the amount ot excess cement

at the subgingival restorative

marg ih . This ce m eh t eso ap e

channe l cou ld u l t imate ly be

restored with resin or amalgam.

Another poss ib le advan-

tage of the porcelain-fused-to-

metal technique

s

the ability to

create G screw-access op en-

ing in the restoration. Thus, the

CeraOne res to ro t i on cou ld

actually be considered screw-

r e t a i n e d a n d r e t r i e v a b l e .

Without the obility to ploce the

countericrque device ever the

cemen ted res to ra t i on , how-

ever, the gold al loy abutment

screw should probably not be

t ightened more than 20 Ncm,

This would still provide consider-

qbly more retent ive s t rength

than the Es the t iCone go ld

retehtive screw, which is much

smaller and tightened to only

10 Ncm, Retrieval would actu-

ally involve retrieving the crown

o n d a b u t m e n t o s o n e s eg

men t , beca use the c row h

v^ou ld be cemen ted to t he

abutment . Even i f permonen

oement were used, this cemen

cou ld bu rn ou t a t opp rox i

mately 1,OOOF if it were nece

sary to separa te the c rown

from the abutment. The screw

access open ing wou ld a l so

p r o v i d e a c e m e n t e s c a p e

channel dur ing the cementa

tion procedure, although Vi/ith

this technique the crown could

be oemented to the abutmen

either intraorally or extraorally.

If size of the screw-access

opening is o concern, it should

be no ted tha t t he CeraOne

a n d t h e U C L A a b u t m e n

screws are similar a nd consider

ab l y l a rge r i n d i ame te

(app rox im a te l y 35 l a rge r

than the EsthetiCone gald alloy

screw. W i th a Vi /e l l -p laced

implant, hov^ever. the screw

channels are en the lingual sur

face and once obturated with

res in or omalgam prov ide a

very normal lingual contour.



41

For impiants that are posi-

tioned with a siightiy buocai

inci inat ion, the cement-

retained CeraOne restoration is

the technique of choice.

Screw-retained restorations in

this situation would contain a

screw channei through the

incisai edge or faciai surface,

seriousiy compromising the

restoratian. A cement-retained

restoration contains no externai

screw channei and so the

externai surface wouid not be

compromised trom the buccai

inciination.

Summary

Singie anterior implant restora-

tions are categorized as either

nonsegmented or segmented.

Nonsegmented restorations

connect direotiy to the impiant

fixture and are screw-retained.

These restorations are fabri-

cated with either piastic burn

out patterns resuiting in a cast

base or the use of prefabri-

cated goid aiioy cylinders that

are cast-to, becoming part of

the metai substructure. Screw-

retained and cement-retained

segmented restorations are

thase that fit aver titanium

abutm ent cyiinders. This may

be advantageaus. because

the bioiogic considerations of

piacing t i tanium abutments

subgingivaiiy inciuding a tita-

nium-titanium interface at the

levei of the impiant fixture as

well as a titanium-soft tissue

intertace, have been weii doc-

umented over extended peri-

ods of time.

Utilization of a goid alloy

cylinder with an internal hexa-

gon allows the fabrication of

singie-impiant restorations on

the EsthetiCone abutment. The

OeraOne abutment is primariiy

designed for cemenf-retoined

singie impiant restorations.

Geromic cops aiiow the tabri-

cation of aii-ceramic restora-

tions and goid alioy cyiinders

aiiow the fabrication ot porce-

lain-fused-to-metal restorations.

Although not originally in-

tended tor this modification,

the use of the gold cylinder

does give the opportunity for

screw retention on the

GeraOne abutment.

With these components, a

variety ot techniques exist

today for the fabrication of

esthetic singie-tooth impiant

restorations. iHowever, despite

the evoiution in components

and techniques, paramount to

the finai prosthetic success are

proper impiant placement and

soff tissue management.

Restorative components can-

not overcome deficiencies in

either of these two criticoi

aspects.

References

1

Lewis S, Beurre r J, Per i G, Hom burg

W. Sing le-tooth im plan t -su ppo r ted

restora t ions. In t J Ora l Moxi l lo tac

Implonis 1988:3:25-30.

2. Gou ld TRL Brunette DM , Westbury L.

The a t t a c h m e n t m e c h o n i s m o f

epith elial cells to fitan ium in vitro. J

PeriodonI Res 1981:16:61 l-óló.

3. Honsson HA, Albrektsson T Branemark

P-l. Structural a spe cts of the inter-

face be tween t i ssue and t i t an ium

imp lon ts . J P ros the t D en f 1983

50:108-113.

4.

ten Co te AR. The gingival junc tion. In

Brân em atk P-l, Zarb G , Albrektsson T

(eds). t issue-Integrated Proslheses

Osseointegration in Clinical Dentistry

C h i c a g o Q u i n t e s s e n c e , 1 98 5

145-153.

5. Jansen JA. Epittielial oeil adh esion to

den ta l imp lan t ma te r i o l s [ t hes i s ]

Nijmegen, The Netherlands, Caitiolic

University. 1984.

6. Lewis, S. An esthet ic t i taniu m ab ut

ment : Report a f o techn ique. In t J

Ora l Max i l l o foc Imp lan ts 1991

6:195-201.

7. Ad el l R, Lek ho lm U, Rookler B

Bran ema rk P-l . A 15-year study o

o sse o i n t e g r o t e d i mp l o n t s i n t t i e

treotment ot the edentulous jow. In

J O ral Surg 1981:0:387-416.

8 . Andersson 6 , O dm an R Car lsson L

Branemark P-l. A new Branemark sin

g le - toa th abu tmen t : Hond l i ng an

early clinical experiences. Int J Oro

Maxillotac Implonts 1992:7:105-111

rehabilitación de hexágono externo

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