infectious aspects of periodontal regeneration
DESCRIPTION
this article describes the infectious aspects of periodontal regenerationTRANSCRIPT
Periodontology 2000, Val. 19, 1999, 164-1 72 Printed in Denmark . All rights reserved
C o p y r i g h t 0 Munksgaard 1999
PERIODONTOLOGY 2000 ISSN 0906-6713
Infectious aspects of periodontal regeneration J 0 R G E N SLOTS, ERIKA SMITH MACDONALD & HESSAM NOWZARI
The development of predictable procedures to facili- tate the formation of new periodontal ligament, ce- mentum and bone over previously diseased root sur- faces remains an important goal in periodontal ther- apy. Periodontal regeneration has been attempted using extraoral or intraoral autogenous bone grafts, allografts, various alloplasts, growth factors, nonre- sorbable or resorbable barrier membranes, or their combinations (2).
Regenerative approaches to treat periodontitis lesions offer exciting possibilities; however, they fre- quently fail to produce the desired clinical outcome due to infectious complications (27). Because re- generative periodontal devices are placed in a poten- tially highly infected environment, their successful application depends upon the prior removal or marked suppression of microbial pathogens at the treated site(s). Infection control may be particularly important with barrier membranes because they may induce a foreign body-like reaction with re- duced host defenses (53) .
This chapter reviews the microbiota that may in- terfere with periodontal regeneration. It also pro- vides guidance on antimicrobial therapies that may reduce the risk of infectious failures with periodontal regeneration. Emphasis is placed on infections as- sociated with expanded polytetrafluoroethylene bar- rier membranes because most of the available data are concerned with this type of regenerative device.
Microbiota of failing periodontal regeneration
Table 1 presents studies that have examined the ef- fect of microbial biofilms or specific bacteria on re- generative periodontal therapy.
Oral bacteria have a propensity to colonize barrier membranes (26, 38). Moreover, in vitro data suggest that bacterial species vary in ability to attach to bar-
rier membranes of different materials. Wang et al. (50) compared the in vitro attachment of 15 oral microorganisms to expanded polytetrafluoroethy- lene, polyglactin 910 and collagen barrier mem- branes. Streptococcus mutans revealed the strongest attachment in all experiments except for Porphyro- monas gingivalis, which exhibited higher cell counts on collagen membranes. S. mutans attached signifi- cantly more to the expanded polytetrafluoroethylene and the collagen barrier membranes than to the po- lyglactin 9 10 membrane. Actinobacillus actinomyce- temcomitans, Actinomyces viscosus, Fusobacterium nucleatum and Selenomonas sputigena showed simi- lar attachment to the 3 barrier membranes studied. S. sputigena revealed the lowest attachment poten- tial of the test bacteria.
Ricci et al. (34) demonstrated varying in vitro af- finity for J? gingivalis to attach to 6 types of bioab- sorbable and nonbioabsorbable barrier membranes. A polyglactin and two collagen barrier membranes demonstrated high I? gingivalis counts. Polylactic acid and synthetic glycolide and lactide copolymer barrier membranes showed lowest J? gingivalis counts. Expanded polytetrafluoroethylene barrier membranes revealed I! gingivalis cells mainly in the fibrillar areas of both the internal and external sides of the membrane. Ricci el al. (34) also showed the in vitro ability of I? gingivalis to penetrate barrier mem- branes from one side to the other. Simion et al. (40) reported that an expanded polytetrafluoroethylene barrier membrane had to be exposed for at least three weeks for complete bacterial penetration.
Using scanning electron microscopy, Selvig et al. (38) identified cocci, filaments and short curved rods in the outer and inner surfaces of retrieved barrier membranes. The patients had been prescribed tetra- cycline for 2 weeks postsurgically and chlorhexidine rinses during the period of membrane insertion. Sel- vig et al. (39) showed an inverse relationship be- tween the extent of barrier membrane microbial contamination and gain in clinical attachment level.
164
Infectious asDects o f Deriodontal regeneration
Grevstad & Leknes (14) detected gram-negative rods and spirochetes in the occlusive and apical por- tions of expanded polytetrafluoroethylene barrier membranes despite systemic penicilllin therapy and chlorhexidine rinses. The authors attributed the mi- crobial growth on barrier membranes to ineffective antimicrobial therapy.
Chen et al. (4) compared the rate at which 11 com- mon oral bacterial species colonized expanded poly- tetrafluoroethylene, collagen and polylactic acid bar- rier membranes in vivo. Total bacterial attachment increased over the 2-week study period, but the 3 barrier types did not differ in numbers or species of colonizing bacteria.
Tempro & Nalbandian (45) recovered predomi- nantly Streptococcus and Actinomyces species and occasionally Haemophilus and Capnocytophaga spe- cies from the microstructure and the occlusive por- tions of expanded polytetrafluoroethylene barrier membrane. They proposed that barrier membrane infections may in part be responsible for the varying clinical outcome with guided tissue regeneration.
De Sanctis et al. (8, 9) evaluated bacterial colon- ization of expanded polytetrafluoroethylene and po- lyglicolactic barrier membranes at 4-6 weeks after membrane insertion. In scanning electron micro- scopy, 57% of exposed and only 17% of nonexposed barrier membranes revealed bacteria in the mid-part of the tooth-facing surface of the barrier membrane (8). De Santis et al. (8) associated bacterial coloniza- tion in the mid-part of the inner surface of the bar- rier membrane with an almost 50% reduction in po- tential gain of clinical attachment.
Nowzari & Slots (25) demonstrated an inverse re- lationship between microbial counts on expanded polytetrafluoroethylene barrier membranes and gain of probing attachment in treatment of furcation and two- to three-wall intraosseous periodontal lesions. Eighty percent of teeth having membranes with less than lo8 total viable counts gained 3 mm or more in probing attachment, whereas teeth with membranes harboring more than lo8 total viable counts either lost attachment (50%) or showed increases in attach- ment of only 1 or 2 mm.
Mombelli et al. (21) recovered specific bacterial species from barrier membranes retrieved from peri- odontal sites showing 1-5 mm gain in clinical attachment. The patients performed strict plaque control and rinsed with chlorhexidine but received no systemic or topical antibiotic therapy. Gram- negative anaerobic rods made up 31% of total mem- brane isolates at 6 weeks postsurgery. One site yielded high proportions of I? gingivalis, 6 sites dem-
onstrated Prevotella intermedia and 6 sites showed Prevotella melaninogenica. Fusobacterium and Cap- nocytophaga species were also frequent membrane isolates. No analysis was performed to determine the possible role of specific microorganisms on clinical outcome.
Specific bacteria seem to assume particular im- portance in failing periodontal regeneration. Nowza- ri & Slots (25) detected I? gingivalis in 3 periodontal sites that experienced a net loss of clinical attachment after membrane removal. A. actinomycetemcomitans was recovered from a periodontal site that gained as little as 1 mm of probing attachment. Campylobacter rectus comprised 14% of the membrane microbiota at a tooth that demonstrated 1 mm gain of clinical attachment. Total microbial counts and percentage of Peptostreptococcus micros, Capnocytophaga species and motile rods on barrier membranes seemed also negatively to affect periodontal regeneration. Nowzari et al. (28) found most gain in clinical attachment in sites that showed no periodontal pathogens on the tooth-facing surface of the barrier membrane. Sites exhibiting little or no gain in clinical attachment dem- onstrated several species of periodontal pathogens on both sides of the barrier membrane.
Machtei et al. (17) implicated A. actinomycetem- comitans in failing regenerative periodontal therapy. Demolon et al. (10) found an association between I? gingivalis and Bacteroides forsythus on polyte- trafluoroethylene barrier membranes and clinical signs of inflammation.
Microbial colonization of barrier membranes may already start at the time of membrane insertion (29). Also, periodontal pathogens that contaminate a bar- rier membrane during insertion may persist on the membrane for a prolonged period (29). Pathogen colonization of barrier membranes during the initial intraoral manipulation has been associated with re- duced gain of clinical attachment (29). Bacteria col- onizing barrier membranes during the time of inser- tion probably originate from saliva or, in case of in- sufficient debridement, from the membrane-treated lesion itself. Patients having high subgingival counts of periodontal pathogens in periodontitis lesions other than the site receiving regenerative therapy ex- hibit an increased risk for barrier membrane colon- ization by motile rods, I? gingivalis, I? intermedia, I? micros, Propionibacterium species and spirochetes (29). Most likely, the membrane infecting pathogens are transferred via saliva from infected periodontal lesions or tongue dorsum to the regenerative-treated periodontal site(s).
Herpesviruses have recently been implicated in
165
Tab
le 1
. Rel
atio
nshi
p be
twee
n ba
rrie
r m
embr
ane
biof
ilm a
nd f
ailin
g pe
riod
onta
l re
gene
ratio
n
Ref
eren
ce
-_
__
N
oppe
, Wac
htel
, Ber
nim
oulin
, E
bert-
Kay
ser
(23)
Selv
ig, N
ilveu
s, Fi
tzm
orri
s,
Ker
sten
, Kho
rsan
di (3
8)
Val
letta
, Sbo
rdon
e, R
arna
glia
, C
iagl
ia, S
pagn
uolo
, Len
ci (
48)
Type
of
mem
bran
e E
xpan
ded
poly
tetr
aflu
oroe
thyl
ene
-__
__
- ~
-
Type
of
peri
odon
tal d
efec
t Pl
aque
ana
lysi
s 40
intr
aoss
eous
R
etrie
ved
defe
cts
mem
bran
es
for l
ight
and
tr
ansm
issi
on
elec
tron
ic
mic
rosc
opy
Exp
ande
d 14
intr
aoss
eous
and
R
etrie
ved
poly
tetr
aflu
oroe
thyl
ene
6 fu
rcat
ion
defe
cts
mem
bran
es fo
r
-~
-
~_
_
-_
__
scan
ning
ele
ctro
n m
icro
scop
y
Mic
robi
olog
ical
fin
ding
s an
d cl
inic
al o
utco
me
His
tolo
gica
lly, a
ll ex
pose
d pa
rts
of t
he b
arri
er m
embr
ane
wer
e co
ntam
inat
ed b
y m
icro
orga
nism
s, w
hich
wer
e fo
und
be-
twee
n ne
utro
phds
, deg
ener
ated
col
lage
n fi
brils
and
nec
rotic
ce
ll co
mpo
nent
s. C
linic
ally
, mos
t ca
ses
show
ed m
embr
ane
ex-
posu
re w
ith g
ingi
val r
eces
sion
and
poc
ket f
orm
atio
n be
twee
n m
embr
ane
and
ging
iva.
B
acte
rial
col
onie
s ex
tend
ed in
to th
e m
idpa
rt o
f th
e m
em-
bran
e. F
ibro
blas
t-lik
e cel
ls, b
lood
ves
sels
and
fib
rous
str
uc-
ture
s w
ere
also
foun
d. T
he o
cclu
sive
por
tion
of t
he m
embr
ane
had
a sp
arse
ness
of
adhe
rent
tis
sue
elem
ents
. No
corr
elat
ion
was
mad
e be
twee
n m
icro
biol
ogic
al a
nd c
linic
al fi
ndin
gs.
~-
-
Exp
ande
d C
lass
I1 f
urca
tion
defe
cts
poly
tetr
aflu
oroe
thyl
ene
Sbor
done
, Cia
glia
, Spa
gunu
olo,
L
enci
, Bar
one,
Ram
aglia
(37
) 1
nona
bsor
babl
e an
d 1
abso
rbab
le
2 pe
riod
onta
l def
ects
__ ~
Selv
ig, K
erst
en, C
ham
berl
ain,
E
xpan
ded
12 in
trao
sseo
us d
efec
ts
Wik
esjo
(39
) po
lyte
traf
luor
oeth
ylen
e
Gui
llem
in, M
ello
nig,
E
xpan
ded
30 in
trao
sseo
us d
efec
ts
Bru
nsvo
ld (
15)
poly
tetr
aflu
oroe
thyl
ene
__
~
.
Gre
vsta
d, L
ekne
s (1
4)
Exp
ande
d 8
intr
aoss
eous
po
lyte
traf
luor
oeth
ylen
e pe
riod
onta
l def
ects
Tem
pro,
Nal
band
ian
(45)
E
xpan
ded
6 pe
riod
onta
l po
lyte
traf
luor
oeth
ylen
e in
trao
sseo
usde
fect
s and
2
furc
atio
n de
fect
s
Ana
erob
ic c
ultu
re
Mic
robi
olog
ical
dat
a un
ders
core
d th
e si
gnif
ican
ce of
sur
gica
l in
stru
men
tatio
n in
inte
r-ra
dicu
lar t
reat
ed s
ites
and
con-
fi
rmed
the
need
to m
aint
ain
heal
ing
site
s fr
ee o
f pe
riod
onta
l pa
thog
ens.
N
o cl
inic
al d
iffe
renc
e bet
wee
n ty
pe o
f m
embr
anes
em
ploy
ed.
The
aut
hors
sug
gest
ed th
at h
ealin
g si
tes
shou
ld b
e fr
ee o
f pe
riod
onta
l pat
hoge
ns.
Ret
rieve
d C
ompa
riso
ns b
etw
een
ultr
astr
uctu
ral f
indi
ngs a
nd c
linic
al o
b-
mem
bran
es
serv
atio
ns re
veal
ed t
hat
the
exte
nt o
f ba
cter
ial c
olon
izat
ion
for
scan
ning
of
the
mem
bran
e co
rrel
ated
inve
rsel
y w
ith c
linic
al a
ttach
men
t el
ectr
on m
icro
scop
y ga
in. E
xten
t of
oral
exp
osur
e may
be
an in
dica
tor o
f lo
ng-t
erm
su
cces
s or
failu
re o
f gui
ded
tissu
e re
gene
ratio
n.
30 r
etri
eved
N
o cl
ear p
atte
rn o
f m
icro
bial
col
oniz
atio
n or
cel
l adh
eren
ces
mem
bran
es b
y in
eith
er s
ide
of t
he m
embr
ane.
The
pre
senc
e of
pla
que
on
scan
ning
ele
ctro
n th
e m
embr
ane
did
not
ham
per
clin
ical
hea
ling
duri
ng th
e fi
rst
mic
rosc
opy
4-6
wee
ks.
4 pa
rtia
lly e
xpos
ed
3 s
truc
tura
lly d
iffe
rent
gro
ups
of b
acte
rial
agg
rega
tions
wer
e m
embr
anes
by
obse
rved
1) g
ram
-pos
itive
coc
ci a
nd r
ods
in th
e ex
tern
al
elec
tron
ic
part
of
the
open
mic
rost
ruct
ure,
2)
cocc
i, ro
ds a
nd fi
lam
en-
mic
rosc
opy
tous
mic
roor
gani
sms
embe
dded
in
fibr
in-m
ed s
pace
s, a
nd
3) g
ram
-pos
itive
coc
ci a
nd ro
ds, g
ram
-neg
ativ
e m
icro
orga
n-
ism
s an
d sp
iroc
hete
s in
the
occl
usiv
e pa
rt o
f th
e m
embr
ane.
N
o co
rrel
atio
n w
as m
ade
with
clin
ical
out
com
e.
6 re
trie
ved
Tra
nsm
issi
on e
lect
ron
mic
rosc
opy
show
ed n
umer
ous
bact
eria
m
embr
anes
for
incl
udin
g co
cci,
rods
and
fila
men
ts. A
naer
obic
cul
ture
yie
lded
tr
ansm
issi
on e
lect
ron
Stre
ptoc
occu
s and
Act
inom
yces
spe
cies
, and
gra
m-n
egat
ive
fa-
mic
rosc
opy
and
culta
tive
rods
, mai
nly
Hue
rnop
hilu
s spe
cies
. It w
as a
ssum
ed
anae
robi
c cu
lture
th
at b
acte
rial
col
oniz
atio
n of
mem
bran
e af
fect
s pe
riod
onta
l co
nnec
tive
tissu
e re
gene
ratio
n.
Not
kno
wn
- __
D
emol
on, P
erss
on, M
oncl
a,
Exp
ande
d 19
cla
ss I1
fur
catio
n Sc
anni
ng e
lect
ron
Aug
men
tin"
grou
p sh
owed
less
bar
rier
-mem
bran
e ex
posu
re
John
son,
Am
mon
s (1
0)
poly
tetr
aflu
oroe
thyl
ene
defe
cts
mic
rosc
opy
than
con
trol
s. B
. jor
syth
us a
nd E
! gin
givu
lis w
ere
asso
ciat
ed
with
gin
giva
l inf
lam
mat
ion
duri
ng in
itial
hea
ling.
Aug
men
tin@
se
emed
to h
ave
little
eff
ect o
n ba
rrie
r-m
embr
ane
mic
ro-
biot
a.
Tabl
e 1.
Con
tinue
d N
owza
ri, S
lots
(25
) E
xpan
ded
11 2
- to
3-w
all a
nd
Sele
ctiv
e an
d In
vers
e re
latio
nshi
p be
twee
n m
icro
bial
cou
nts
and
gain
of
poly
tetr
aflu
oroe
thyl
ene
furc
atio
n de
fect
s no
n-se
lect
ive
prob
ing
atta
chm
ent.
80%
of t
eeth
hav
ing
mem
bran
es w
ith
less
than
lo8
tota
l via
ble
coun
ts g
aine
d 3
mm
or
mor
e in
at
tach
men
t; te
eth
with
mem
bran
es h
avin
g m
ore
than
lo8
bac-
te
ria
lost
or h
ad s
mal
l pro
bing
atta
chm
ent i
ncre
ases
of 1
-2
mm
. N
ovae
s, G
utie
rrez
, Fra
ncis
chet
to,
Cel
lulo
se
10 c
lass
I1 fu
rcat
ion
Scan
ning
ele
ctro
n Sc
anni
ng e
lect
ron
mic
rosc
opy
and
DN
A p
robe
ana
lyse
s di
d N
ovae
s (2
4)
defe
cts
mic
rosc
opy
and
not
reve
al p
erio
dont
al p
atho
gens
at
the
time
of m
embr
ane
anae
robi
c cu
lture
an
d D
NA
pro
be
DN
A p
robe
ex
posu
re. N
o cl
inic
al re
sults
wer
e re
port
ed.
ari,
Mat
ian,
Slo
ts (2
8)
Exp
ande
d 18
two-
to th
ree-
wal
l Se
lect
ive
and
The
Aug
men
tine
grou
p ha
d an
incr
ease
in m
ean
prob
ing
poly
tetr
aflu
oroe
thyl
ene
intr
aoss
eous
def
ects
no
n-se
lect
ive
atta
chm
ent o
f 36
.5%
of
pote
ntia
l gai
n as
com
pare
d w
ith
anae
robi
c an
d DN
A e
22.4
% fo
r con
trol
gro
up. T
he A
ugm
entin
@ gr
oup
show
ed 9
- fo
ld fe
wer
org
anis
ms t
han
cont
rols
. D
e Sa
nctis
, Zuc
chel
i, C
laus
er (9
) E
xpan
ded
poly
tetr
aflu
oroe
thyl
ene
Zuc
chel
i, C
laus
er (8
) Po
lygl
ycol
actic
aci
d
Mac
htei
, Gro
ssi,
Dun
ford
, E
xpan
ded
10 a
ngul
ar b
ony
defe
cts
Scan
ning
ele
ctro
n m
icro
scou
v 10
ang
ular
bon
y de
fect
s Sc
anni
ng e
lect
ron
mic
rosc
opy
Bac
teri
al c
olon
izat
ion
in th
e m
id-p
art
of b
arri
er m
embr
ane
redu
ced
pote
ntia
l pro
bing
atta
chm
ent
by 5
0%.
Gai
n of
pro
bing
atta
chm
ent w
as g
reat
er fo
r non
-exp
osed
than
for
expo
sed
mem
bran
es (
4.22
0.5
mm
vs
3.3k
0.6
mm
resp
ec-
tivel
y). S
cann
ing
elec
tron
mic
rosc
opy
show
ed th
at 4
1% of
ex-
D
osed
mem
bran
es h
ad b
acte
rial
col
oniz
atio
n.
56 C
lass
I1 fu
rcat
ion
Ana
erob
ic c
ultu
re
defe
cts
10 m
andi
bula
r fu
rcat
ion
Ana
erob
ic cu
lture
de
fect
s
Site
s col
oniz
ed w
ith l?
int
erm
edia
exh
ibite
d le
ss f
avor
able
cl
inic
al re
sults
com
pare
d w
ith s
ites
free
of
the
orga
nism
. F
usob
acte
rium
, I! i
nter
med
ia a
nd A
ctin
omyc
es o
dons
olyt
icus
w
ere
mos
t com
mon
mem
bran
e is
olat
es. S
ites t
reat
ed w
ith a
ba
mer
mem
bran
e te
n o
be p
ositi
ve fo
r 15
targ
et m
icro
- or
gani
sms m
ore
ofte
n si
tes t
reat
ed w
ithou
t a m
em-
bran
e.
Now
zari,
Sm
ith M
acD
onal
d,
Exp
ande
d 42
man
dibu
lar
post
erio
r Se
lect
ive
and
Patie
nts
trea
ted
with
hll
-mou
th o
sseo
us s
urge
ry re
veal
ed
Lon
don,
Fly
nn, M
orri
son,
po
lyte
traf
luor
oeth
ylen
e 2-
to 3
-wal
l def
ects
no
n-se
lect
ive
low
er le
vels
of
peri
odon
tal p
atho
gens
on
barr
ier
mem
bran
es
Slot
s (2
9)
and
grea
ter g
ain
in c
linic
al a
ttach
men
t th
an c
ontr
ols
(3.4
us
1.4
mm
res
pect
ivel
y).
anae
robi
c cu
lture
an
d D
NA
pro
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failing periodontal regeneration. Smith MacDonald et al. (44) studied 4 membrane-treated periodontal sites having human cytomegalovirus or Epstein-Barr type 1 virus. The 4 virally infected sites revealed an average gain in clinical attachment of 2.3 mm com- pared with 16 virally negative sites that showed a mean clinical attachment gain of 5.0 mm (P=0.004). This observation may be important because the two herpesviruses have been associated with adult peri- odontitis (5, 31) and with acute necrotizing ulcer- ative gingivitis in Nigerian children (6) and they pos- sess an array of virulence factors pertinent for de- structive periodontal disease (5). It is also of interest that cytomegalovirus is the most common viral in- fectious complication in patients receiving organ and bone marrow transplants (35). Cytomegalovirus can infect and alter the function of fibroblasts (201, thereby potentially impairing regeneration of the periodontal ligament. More research is warranted on the possible relationship between periodontal her- pesvirus infections and suboptimal healing after re- generative periodontal procedures.
Thus, it seems that several oral microbial species can colonize barrier membranes, that microbial con- tamination of barrier membranes can significantly hamper periodontal tissue regeneration, and that certain microbial species and maybe some herpesvi- ruses are particularly detrimental to periodontal re- generation.
An ti - in fec tive therapy in periodontal regeneration
To prevent infectious failures with regenerative peri- odontal therapy, efforts should be directed towards the elimination or marked suppression of pathogens in the treated site as well as in the entire mouth prior to regenerative surgery and throughout the healing phase.
The dental professional possesses a variety of means to prevent or control barrier membrane-as- sociated infections. Anti-infective therapy in peri- odontal regeneration includes mechanical debride- ment with or without concomitant periodontal surgery, local or systemic delivery of antimicrobial agents, possible application of slow-release anti- microbial agents to the barrier membrane material and proper oral hygiene measures by the patient.
Diligent mechanical instrumentation (that is, seal- ing and root planing) to remove dental plaque, cal- culus, altered cementum and cytotoxic microbial products on the root surface is a prerequisite for op-
timal periodontal healing. Patients may also benefit from treatment of periodontal lesions other than those designated for regenerative therapy before per- forming the regenerative procedures. Nowzari et al. (29) showed that patients who received pocket-re- duction therapy of existing periodontal lesions prior to barrier membrane placement revealed the lowest levels of periodontal pathogens in the membrane and exhibited most clinical attachment gain. A non- surgical approach to periodontal therapy may also be successful in reducing the oral load of periodontal pathogens, provided appropriate considerations are given to the specific pathogenic microbiota of the patient. As discussed by van Winkelhoff et al. (49), systemic antimicrobial therapy may be necessary to suppress A. actinomycetemcomitans and other peri- odontal pathogens in the human oral cavity. Sys- temic antimicrobial treatment allows antibiotics to reach pathogens residing in the depth of periodontal pockets and on the tongue and buccal mucosa.
Systemic administration of amoxicillin-clavulanic acid (Augmentin9 (28) and ornidazole (22) have demonstrated clinical benefits in regenerative peri- odontal therapy. However, since an antibiotic agent may be active against one and demonstrate resist- ance against another periodontal pathogen and since the periodontal microbiota of individual pa- tients often shows several pathogenic species simul- taneously, it is often advantageous to prescribe a combination therapy of two antibiotics. Metronida- zole and ciprofloxacin exhibit synergy and constitute a valuable drug combination for periodontitis pa- tients with anaerobic pathogens together with su- perinfecting enteric bacteria (32, 42). The metronid- azole-ciprofloxacin drug combination is also effec- tive against A. actinomycetemcomitans and several other periodontal pathogens (42). Resistant organ- isms are mainly streptococci (421, which exert antag- onistic activity against several periodontal patho- gens (42, 49). Optimally, systemic antibiotics in peri- odontics should be prescribed on the basis of an appropriate microbiological analysis (41, 46). If mere clinical judgment forms the basis for the selection of antibiotics, the clinician may not choose the optimal drug regimens and may not obtain the desired clin- ical results (43).
Nowzari et al. (29) recommended washing extra- oral skin areas with a iodophor before regenerative periodontal surgery to prevent membrane coloniza- tion by dermal pathogens during membrane inser- tion. Sutures used in regenerative procedures are particularly prone to contacting the lips and the face and thereby adsorbing dermal microorganisms.
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Infectious aspects of periodontal regeneration
Sander et al. (36) evaluated the effect of local ap- plication of 1 g of a 25% metronidazole gel on peri- odontal healing after guided tissue regeneration. At 6 months postsurgery, significantly more gain of clinical attachment occurred in the metronidazole- treated periodontal sites than in sites treated with barrier membrane alone (36). At 1 week postsurgery, metronidazole-treated sites showed significantly lower levels of total viable bacteria and lower pro- portions of black-pigmented anaerobic rods than control sites (12). However, no microbiological dif- ference between test and control sites was observed at later observation times (12), suggesting that the microbiological benefit of the metronidazole gel was confined to the initial regeneration phase. Local pocket delivery of chemotherapeutic agents other than metronidazole may also help reduce pathogens in barrier membrane-treated sites (33).
Antimicrobial coating of barrier membranes con- stitutes a novel approach to controlling membrane- associated infections. Harvey et al. (16) have described the potential of antibiotic bonding to po- lytetrafluoroethylene by means of the cationic sur- factant, tridodecylmethylammonium chloride (Poly- sciences, Inc., Warrington, PA, USA). Tridodecyl- methylammonium chloride has been safely used for more than a decade in vascular shunt (3) and urinary tract catheter (1 1) surgeries. Our laboratory has studied the clinical benefit of applying tetracycline- HC1 to the surface of expanded polytetrafluoroethy- lene membranes (30). Barrier membranes were sub- merged for 1 minute in a 5% solution in absolute alcohol of tridodecylmethylammonium chloride. After drying at room temperature, the specimens were immersed for 1 minute into a freshly prepared, basic 3% tetracycline-HC1 solution (one 250 mg cap- sule dissolved in 7.5 ml distilled water; pH adjusted from 1.7 to 9.5 using sodium hydroxide) and then dried at room temperature. In vitro studies showed that, despite exhaustive washing, the tetracycline- coated barrier membranes released biologically ac- tive tetracycline for 3-6 weeks (Fig. 1). Tetracycline- coated barrier membranes harbored significantly fewer cultivable pathogens for the first 2 weeks after membrane insertion than non-coated membranes (30). Also, after 6 weeks, tetracycline-coated mem- branes were associated with more gain in clinical attachment than non-coated membranes (30). Most dental offices can readily perform the tetracycline coating described above. Undoubtedly, additional methods for slow release of antibiotics or other bio- logically active agents from regenerative devices will be developed in the future.
Fig. 1. Tetracycline coating of a section of polytetra- fluoroethylene barrier membrane by means of tridodecyl- methylammonium chloride. After 21 days of washing in double distilled water with frequent water changes, the membrane still released active tetracycline, as evidenced by the zone of inhibition of Escherichia coli growth around the membrane.
The optimal supportive periodontal treatment after regenerative periodontal therapy has not been firmly delineated, and treatment may have to be modified to fit specific individual needs. However, most anti-infective principles of conventional peri- odontal maintenance therapy are applicable to re- generative procedures (52).
Proper oral hygiene is important to decrease plaque levels for the benefit of the tissue healing. Studies have shown regenerative periodontal pro- cedures to be more successful in patients having little or no dental plaque than in patients with high plaque levels (47). Also, patients with good oral hy- giene can preserve the clinical attachment gain after regenerative periodontal therapy for many years (7, 13, 18, 19, 51). Commonly, patients are instructed in twice-daily use of toothbrushing and dental flossing. Chlorhexidine rinses seem to offer therapeutic bene- fits during healing (211, even though in uitro experi- ments have revealed an ability of chlorhexidine to damage fibroblasts (1).
Some clinicians advocate supportive periodontal treatment once a week for the first 6 weeks of barrier membrane treatment and then once a month for the first 6 months after regenerative therapy (29). In bar- rier membrane-treated sites, mechanical plaque re- moval should be performed in a gentle manner in order not to disturb tissue healing. Also, to avoid a foreign body-like reaction, pumice or other particu- lar matter that may remain in regenerative sites dur- ing the healing phase should be used carefully and sparingly.
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Slots e t al.
Recommendations and concluding remarks
Regeneration of periodontal tissue is predicated upon controlling periodontal pathogens in the bar- rier membrane-treated site and probably also in other parts of the oral cavity prior to the membrane insertion and during initial healing. I! gingivalis, A. actinomycetemcomitans, B. forsythus, I? intermedia, l? micros and C. rectus have been associated with failing regenerative periodontal therapy. Herpesvi- ruses may play a detrimental role in periodontal re- generation as well. Topical antiseptic and systemic antibiotic therapy might be employed to control pathogens in periodontal regeneration.
A practical approach to antimicrobial therapy in regenerative periodontal therapy is outlined below:
institution of effective oral hygiene measures; subgingival scaling and root planing of the entire dentition, possibly combined with periodontal surgery to gain access to affected root surfaces; surgical reduction of periodontal pockets (except for the site(s) of regenerative surgery) or appropri- ate nonsurgical therapy of periodontally affected teeth; possible utilization of a tetracycline-coated bar- rier membrane; thorough root planing of barrier membrane- treated sites using ultrasonic, rotary or hand in- strument; application of antimicrobial agent to diseased root surfaces (iodophor, metronidazole, tetracycline or citric acid, but probably not chlor- hexidine due to its toxic effect on fibroblasts); and suturing of surgical flaps for complete coverage of the barrier membrane; possible systemic antibiotic therapy with an ap- propriate antimicrobial agent to eradicate or markedly suppress periodontal pathogens. Anti- biotic therapy may begin 1-2 days prior to regene- rative surgery and continue for at least 8 days for most antibiotics; 0.12% chlorhexidine rinse (15 ml, twice daily) during the first 2 weeks after regenerative surgery; the anti-inflammatory ibuprofen (400 mg, four times daily) may be prescribed for 3 days post- surgery; frequent professional plaque removal during the healing period. Supportive periodontal treatment may be scheduled once a week for 6 weeks and then once a month for 6 months. Subgingival scal- ing, probing and pumicing of regenerative sites should be minimized or avoided for the first 6
months not to disturb the maturing of newly formed connective tissue; and institution of an individually tailored mainten- ance care program.
This chapter has focused on infectious aspects of membrane-assisted periodontal regeneration. How- ever, the concept of infection control is applicable also to other types of regenerative periodontal ther- apy and to guided bone regeneration. It is important to realize that the formation of new connective peri- odontal attachment is contingent upon the elimin- ation or marked reduction of pathogens at the treated periodontal site.
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