Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5223_Библиотеки_им_академика_М_И_Перельмана.pdf
7
OSSEODENSIFICATION FOR IMMEDIATE MOLAR IMPLANT PLACEMENT
118
As well, maxillary molar implants generally achieve
lower insertion torque values (ITVs) than mandibular
sites due to lower bone density. Walker et al10 reported
the implant survival rate in immediate mandibular
molar sites to be 86% when initial ITV was low (≤ 15
Ncm), but 90% to 96% when initial ITV was medium
to high (30 to 50 Ncm). Often, low initial stability in
molar extraction sockets dictates the need for widerbody implants and/or for primary full soft tissue
closure to promote predictable healing.
11
Molar septum preservation during extraction is
a key element needed to achieve implant stability,
and this preservation is achieved with unpredictable
results utilizing standard drills.
12–14
Adequate septum
width is essential for achieving implant stability. A
minimum septum mesiodistal width of 3 mm or
more is reported as an essential required element for
successful expansion and adequate implant placement.
13–15
erefore, the preservation and the expansion of the septal bone is an important factor for this
treatment modality. Historically, rotary expanders,
osteotomes, and specialized piezoelectric tips have
been utilized to expand the septum in mandibular and
maxillary molar extraction sites as well as to elevate
the sinus oor and sinus membrane prior to immediate implant placement.
3,14–22
How Osseodensifi cation Works
One recent instrumentation method was introduced
by Huwais and Meyer23 for the achievement of
adequate stability, both primary and secondary, using
osteotomy site preparation via “osseodensi cation.”
Rather than removing or excavating bone as is the
case with standard implant drilling, osseodensi cation preserves bone by compacting it along the surface
of the developing osteotomy, tripling the bone-toimplant contact.
23,24
Large animal histologic studies
have demonstrated that the high stability on the day
of implant placement using osseodensi cation is
maintained throughout the osseointegration process,
and that the retained compacted bone can act as nucleating surfaces for osteoblastic bone deposition, facilitating the bridging of bone and implant surface
regardless of the implant macro or micro geometry.
25
Osseodensi cation is facilitated using specially
designed burs (Versah) that are run in reverse (counterclockwise or CCW) mode generally at 800 to 1,200
rpm (Figs 7-1 and 7-2). ey increase peri-implant
bone density and bone-to-implant contact with associated substantial increases in primary stability of
the implant.23 is increase in primary stability is
facilitated by the compaction/autografting of bone
particles into the trabecular space, creating an elastic
strain. is in turn results in a spring-back e ect of
bone toward the implant body, enhancing its primary
stability without the traditional need to undersize
the osteotomy diameter.
23,26,27
Osseodensi cation
burs are used under copious saline irrigation and are
thought to deform bone via viscoelastic and plastic
mechanisms. e recommended technique is for the
surgeon to utilize a constant, well-controlled “modu-
FIG 7-1 Densah burs (Versah) range in maximum diameter from 2.5 to 5.8 mm and are used in reverse mode to create osteotomies by
osseodensi cation.
119
Literature on Osseodensifi cation
lating” motion of the bur within the osteotomy, creating a hydraulic pressure wave ahead of the point of
contact while avoiding untoward overheating of bone.
e irrigation uid being forced into the osteotomy
will also result in autografting of bone particles into
the trabecular space along the inner surface of the
osteotomy, further densifying its walls.
23,27
is is in
contrast to the situation with standard drilling (ie,
clockwise or CW) protocols where bone particles are
either extracted out of the osteotomies by the irrigation uid or remain in the drill utes.
Osseodensi cation facilitates a controlled plastic
deformation of trabecular bone.
23
is allows for
trabecular bone expansion outwardly to produce the
osteotomy. is combination of plastic deformation
and the compaction/autografting facilitates implant
placement with sufficient stability in sites with
less-than-optimum bone quantity and quality (eg, IMI
sites). Trisi et al28 studied densi cation histologically,
reporting that they were able to place and successfully
integrate 5-mm-diameter implants into bone ridges
in sheep iliac crest that were originally only 5 mm in
width. More recently, Koutouzis et al29 studied human
clinical outcomes using osseodensi cation to facilitate
plastic ridge expansion at healed edentulous sites with
di erent alveolar ridge widths. In their retrospective
case series, implant sites were divided into four groups
according to their initial buccolingual/palatal ridge
widths, as follows:
• G1: 3–4 mm
• G2: 5–6 mm
• G3: 7–8 mm
• G4: 10–11 mm
G1 ridges demonstrated the largest amount of ridge
expansion (75%), followed by G2 (28%), G3 (17%), and
G4 (0%). e authors concluded that G4 ridges had
enough trabecular bone content to absorb the hydraulic wave generated by the densifying burs without
showing any physical plastic expansion. In contrast,
G1 (3–4 mm) ridges had insu cient trabecular bone
in their cores to fully absorb the hydraulic wave generated, needing maximum plastic physical expansion.
At each site, an implant equal in diameter or slightly
wider (up to 0.7 mm wider) than the nal bur was
inserted, and any hard and/or soft tissue grafting
deemed necessary was done with primary ap closure
where needed. In total, 28 implants were placed in 21
patients (12 women and 9 men). Two implants failed
to integrate, likely due to a low trabecular-to-cortical
bone ratio, while the remainder became integrated
and were restored, making the success rate 92.8%. It
was concluded that the minimum ridge width required
for predictable plastic expansion through osseodensi cation is 4 mm, of which at least 2 mm should be
trabecular bone.
a b
FIG 7-2 Densah burs are dual-action tools. ey can be
used with standard surgical implant engines with adequate
irrigation to produce osseodensi cation when rotating in
the noncutting direction (CCW), ie, densifying mode (a),
or to excavate bone when rotating in the cutting direction
(CW), ie, cutting mode (b). In either mode, the burs are
run at 800 to 1,200 rpm.
7
OSSEODENSIFICATION FOR IMMEDIATE MOLAR IMPLANT PLACEMENT
120
In addition to plastic expansion of ridges, clinical
short- and long-term studies have demonstrated
that osseodensication achieves enhanced implant
stability and high implant success rates regardless of
implant micro and macro geometry in several clinical
scenarios, including immediate and early loading.
30–34
Tanello et al31 reported results of a multicenter retrospective 5-year follow-up clinical study in which osseodensication protocols were used in both the maxilla
and the mandible to place 254 implants with six dier
ent geometries in 184 patients. High implant primary
and secondary stabilities were reported regardless of
implant design, with an overall success rate of 97.7%.
Additional clinical studies have reported on implant
placement in conjunction with crestal sinus elevation
and grafting, again with high success rates utilizing
osseodensication.
33,35,36
Preoperative CBCT scans are essential in determining whether or not osseodensication can assist in
placing mandibular IMIs while also reducing the risk
of surgical damage to the mandibular canal and/or
lingual plate of bone. It has been suggested that at
least 4 mm of bone apical to mandibular molar root
apices will be required to achieve adequate primary
stability of an IMI,37 but this requirement is less of an
issue if osseodensication is being planned. Mandibular rst molars most commonly have type B sockets,38 and IMIs placed here will most likely achieve the
required stability within the connes of an expanded
IRS and not necessarily require the usual 4 mm of
native apical bone. In the posterior maxilla, the principle of osseodensication oers even greater advantage. Bone density generally is low here and can benet from compaction. Further, maxillary rst molars
commonly have type A sockets,38 making them ideal
for densication—often without need to elevate the
associated sinus oor. However, if sinus oor elevation is needed, it can easily and atraumatically be
dealt with using specic osseodensication protocols.
Support for this application and its clinical protocols
comes from a recent multicenter retrospective clinical study.
35
Surgical Considerations
As discussed elsewhere in this book, IMI placement
is best done using apless surgery, coronectomy, and
then gentle removal of each molar root separately.
39,40
Avoiding elevation of a ap, particularly on the buccal
aspect, will minimize disruption of its periosteal blood
supply, which in turn will reduce the risk of crestal
bone loss as well as preserve keratinized soft tissues.
Following their systematic review and meta-analysis
of 1,106 IMIs, Ragucci et al41 concluded that more
marginal bone loss occurred with ap reection, especially in conjunction with thin gingival biotype cases.
Depth of implant placement also has an impact on
crestal bone loss, with the preferred approach being
to place the implant prosthetic table 1 to 2 mm sub crestally on the buccal aspect.42 e usual protocol for
placing a mandibular molar IMI using osseodensication is illustrated in Fig 7-3.
44
Anatomical Considerations
Generally, socket anatomy permitting, in order to
achieve optimal placement, IMIs are best placed into
the IRS bone. Smith and Tarnow
38
presented a classication of molar socket anatomy based on the dimensions of the remaining IRS bone after the tooth has
been atraumatically extracted. In this classication,
type A sockets were dened as those with sucient
bulk and width of IRS to stabilize and totally house
the coronal aspect of the chosen implant. Type B
sockets were those with sucient bulk and width
of IRS to stabilize but not fully house the implant,
while type C were denoted as those with insucient
IRS to stabilize an IMI. Osseodensication is of value
with both types A and B. With type A sockets, it can
increase the density of the IRS osteotomy walls to
enhance implant stability, while type B sockets can
be expanded to house more of the implant periphery within the septal bone. As discussed elsewhere
in this book, type C sockets, most commonly seen at
mandibular second molar sites, are best treated with
wider-diameter implants or with socket preservation
and delayed implant placement (see chapters 1 and 3).
e authors of this chapter also recently conducted
a multicenter clinical study utilizing osseodensication to place implants into 145 molar septal sites (87
mandible, 58 maxilla) in 131 patients (90 female, 41
male). Initial septum width ranged from 2.5 to 4.1 mm
with an average width of 3.3 mm (ie, generally type B
sockets).44 Maxillary septa were wider than mandibular ones. Osteotomy widths generated using osseodensication became 3.8 to 5.5 mm, with an average of
121
Anatomical Considerations
FIG 7-3 (a) Step 1: Separate the molar roots at the furcation without compromising the integrity of the IRS to permit their separate
and atraumatic removal. (b) Step 2: After degranulating the socket as needed, use a pilot drill of 1.3 to 1.6 mm in diameter in CW mode
(or a piezoelectric surgery tip) to begin preparation of the osteotomy into the IRS, continuing to a depth 1 mm beyond that of the
planned implant length. is extra 1-mm depth will be needed to accommodate the bone shavings forced apically by subsequent burs,
which will be run in reverse (CCW) mode. (c) Step 3:Depending on the implant type and diameter, follow the corresponding Densifying
Reference Guide (https://versah.com/implant-system-drilling-protocols/), starting with the smallest diameter (2.0-mm) Densah bur,
again to a depth 1 mm beyond the intended implant length. For site expansion, Densah burs must be operated in reverse mode (CCW)
with drill speed 800–1,200 rpm and copious irrigation. Subsequent Densah burs should increase the osteotomy diameter in the smallest
possible increments to avoid overstressing the bone during its expansion (ie, from 2.0 mm to 2.3 mm to 2.5 mm to 3.0 mm). e nal
bur can be chosen to be equal to or slightly larger in diameter relative to the major diameter of the selected implant, remembering that
the expanded osteotomy walls will spring back once the nal bur is removed. (d) Step 4: Implant placement can then be at an equicrestal
or subcrestal position, depending on the implant design. (e) Step 5: Graft any remaining peri-implant gaps with a bone graft material
if needed, preferably using an allograft with a high cancellous-to-cortical bone ratio. Consider sealing the site with biologics like an
autologous platelet-rich brin (PRF) clot43 or a collagen plug, and place a large-diameter healing abutment to help in protecting the
grafted gaps. (f) Step 6: A large stock or wide custom healing abutment must be placed to seal the grafted extraction socket.
a b
c d
e f
7
OSSEODENSIFICATION FOR IMMEDIATE MOLAR IMPLANT PLACEMENT
122
4.65 mm (Fig 7-4). Implant stability was measured by
both ITVs and implant stability quotient (ISQ) values.
ITV was higher in the mandible (35 to 60 Ncm) than
the maxilla (20 to 60 Ncm) with a mean of 41.1 Ncm.
ISQ values were taken at surgery (range of 60 to 82)
and at the time of the restorative impression (range of
70 to 88). Implants were fully loaded between 3 and
9 months (average of 4.7 months) postimplantation.
Ten implants failed at the restorative phase, resulting
in a 93.1% implant survival rate.
Implant failures appeared to be associated with
the use of nonsealing narrow-diameter immediate
healing abutments. Osseodensication instrumen-
tation facilitated bone preservation and expansion in
septa with widths as small as 2.5 mm and adequate
implant stability. Osseodensication also may facilitate septum bone preservation and conversion of type
C molar sockets to type B and type B sockets to type A.
e authors suggested a further classication of molar
IRS into four types based on their widths. SI IRS was
dened as having widths > 4 mm while SII widths were
3 to 4 mm. SIII IRS widths were proposed to be 2 to 3
mm and SIV < 2 mm or missing (Fig 7-5). Based on the
new classication, type SIII can be converted to type
SII and type SII to type SI using osseodensication.
FIG 7-4 Molar septum expansion via osseodensication at 145 sites in 131 patients with follow-up of 12
to 60 months. e mean preoperative septal width was
3.2 mm, and this was increased with densication to a
mean of 4.65 mm.
44
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
Molar septum
initial width
Post-expansion
osteotomy diameter
131 Patients
145 Septa
87 Mandible
58 Maxilla
93.1% Success rate
3.2 mm
4.65 mm
a b
c
d
FIG 7-5 (a) SI IRS width > 4 mm. (b) SII IRS width 3 to 4 mm. (c) SIII IRS width 2 to 3 mm. (d) SIV IRS width < 2 mm or none. Based
on the new classication, type SIII can be converted to type SII and type SII to type SI using osseodensication.
SI SII
SIII SIV
123
Sample Cases
Sample Cases
Case 1: Mandibular molar with type
B socket
Case 1 displays the procedure performed at a mandibular type B socket according to the Smith and Tarnow
classication.38 e patient was a 47-year-old nonsmoker with controlled hypertension presenting
with a loose restoration in an endodontically treated
mandibular left rst molar. After removal of the restoration, the tooth was deemed hopeless due to a root
fracture. CBCT scanning suggested suitability for
placement of an IMI (Figs 7-6a and 7-6b). e two
roots were separated and removed individually without raising a soft tissue ap (Figs 7-6c and 7-6d). e
implant chosen was a 12 × 4.5–mm Dentium Superline, and using the Densah bur reference guide for
this implant type and its dimensions (Fig 7-6e), the
osteotomy was begun in the IRS. Accordingly, after the
pilot bur had been used in cutting mode to a depth of
13 mm (Figs 7-6f and 7-6g), a sequence of ve burs
with progressive, small increases in bur diameter
(Densah burs VT1525, VT1828, VT2535, VT2838,
and nally VT3545) was used, all in CCW mode, to
create an osteotomy within the IRS (Figs 7-6h to 7-6l).
Implant insertion followed (Fig 7-6m) with an initial
torque of 30 Ncm and an ISQ value of 74.
To complete the procedure, all remaining periimplant gaps were lled with an allograft of 70%
cancellous and 30% cortical bone particles (Fig 7-6n;
Osteogenics). Immediately prior to surgery, a sample
a b
c d
FIG 7-6 (a) A mandibular left rst molar was deemed hopeless and a candidate for an IMI. is sagittal radiographic view and its
coronal counterpart suggested a type B IRS and adequate bone to receive a 12 × 4.5–mm IMI utilizing septal expansion with osseodensication burs. (b) A coronal CBCT image of the furcal bone of the tooth in question. (c) e clinical presentation of the tooth after
removal of the restoration and separation of the two roots through the furcation. (d) e two roots were removed atraumatically without
a need to raise a mucoperiosteal ap, with preservation of the type B IRS.
7
OSSEODENSIFICATION FOR IMMEDIATE MOLAR IMPLANT PLACEMENT
124
of venous blood had been taken from the patient and
centrifuged to create leukocyte- and platelet-rich brin
(L-PRF) clots.
43,45
is biologic membrane was then
used to cover the implant and graft particles before
a wide-diameter healing abutment was connected to
the implant (Fig 7-6o). e healing abutment was 8.5
mm in diameter and helped to protect the grafted
gaps (Figs 7-6p and 7-6q). A postoperative CBCT scan
FIG 7-6 (cont) (e) Reference guide for inserting a 12 × 4.5–mm Dentium Superline implant using Densah burs with small-increment
increase. (f) An intraoperative periapical radiograph shows Densah Bur VT1525 expanding the initial osteotomy depth of 13 mm. An
osteotomy was created for a 12 × 4.5–mm Dentium Superline implant in a type B socket IRS using the following osseodensication bur
sequence. (g) Pilot bur in CW mode to a depth of 13 mm. (h) Densah bur VT1525 (2.0) in CCW mode to 13 mm. (i) Densah bur VT1828
(2.3) in CCW mode to 13 mm. (j) Densah bur VT2535 (3.0) in CCW mode to 13 mm. (k) Densah bur VT2838 (3.3) in CCW mode to 13
mm. (l) Densah bur VT3545 (4.0) in CCW mode to 13 mm. Because of the small increases in Densah bur and osteotomy diameter, the
expanding IRS remained intact throughout. (m) At the time of implant placement, the initial torque was recorded at 30 Ncm, while
resonance frequency testing showed an ISQ value of 74. (n) e peri-implant gaps were lled with allograft to help in minimizing socket
shrinkage during site healing. (o) An autogenous leukocyte- and PRF clot43 was attened and used as a barrier membrane to seal the
site prior to placing a large-diameter healing abutment.
e f
g h i
j k l
m n o
125
Sample Cases
showed the implant to be in the optimal prosthetic
position for a molar crown (Fig 7-6r).
After 3 months of healing, the implant had an ISQ
value of 79 and was considered ready for restoration
(Fig 7-6s). A porcelain-fused-to-metal crown was delivered 1 month later and is shown after 4 months in
function in Figs 7-6t and 7-6u, and again after 4 years
in function in Figs 7-6v and 7-6w.
FIG 7-6 (cont) (p) An 8.5-mm-diameter healing abutment was
connected to the implant and interrupted sutures placed interproximally to stabilize the papillae. Note that the large healing
abutment provides a protective seal for the underlying grafted
peri-implant gaps. (q) e immediate postoperative radiograph of
the implant with the healing abutment. (r) A postoperative CBCT
scan shows the implant to be in the optimal prosthetic position
for a molar crown. (s) After 4 months’ healing, the implant was
ready for restoration. e ISQ value 1 month earlier had been 79.
(t) e denitive restoration 4 months following insertion. (u) e
radiographic appearance at 4 months postrestoration. (v) e clinical appearance after 4 years in function. (w) e radiographic
appearance after 4 years in function. Note that platform switching
has helped to minimize crestal resorption.
p q
r
u v
w
s t
7
OSSEODENSIFICATION FOR IMMEDIATE MOLAR IMPLANT PLACEMENT
126
Case 2: Maxillary molar with type A
socket
A second case shows the management of a type A
maxillary IRS38 at a left rst molar site in a 53-yearold nonsmoker with no signicant medical history.
e tooth was nonvital with a large periapical abscess
as well as buccal and palatal bone loss (Figs 7-7a and
7-7b). Possible treatment options (all with extraction
of the tooth) were discussed, and the patient opted
for an IMI. e implant chosen was a 10 × 4.5–mm
Anyridge (MegaGen) implant. e tooth was decoronated using a high-speed bur and sectioned at the level
of its furcation to allow separation of the three roots
for individual removal atraumatically (Figs 7-7c and
7-7d). No soft tissue ap was elevated. Once the tooth
roots had been removed, a large type A IRS remained,
with its narrowest diameter being 4 mm (Fig 7-7e).
Osseodensication was planned to preserve and
expand the septum, and the osteotomy was begun
using a 1.6-mm-diameter pilot drill in cutting mode
(Fig 7-7f). e drilling depth was 10 mm. Unlike the
situation in the mandible, where the bone is generally
denser, there is no need to drill to a deeper depth than
the actual implant length being used in the posterior
maxilla. Densication then was begun using the bur
VT1525 (2.0) in reverse mode followed by a periapical radiograph that conrmed close proximity to the
sinus oor (Fig 7-7g). Further development of the
osteotomy was achieved using Densah burs VT2535
(3.0), VT2838 (3.3 mm), and VT3545 (4.0) all to the
same depth of 10 mm (Fig 7-7h). A torqueing force of
40 Ncm was required to seat the implant (Fig 7-7i),
and a subsequent radiograph conrmed that the sinus
oor had not been breached (Fig 7-7j). While some
clinicians46 consider grafting of gaps around an IMI
placed in a type A IRS to be unnecessary, the treating clinician elected to place an allograft mixture of
70% cancellous and 30% cortical bone particles (Fig
7-7k). Because the implant had an ITV of 40 Ncm and
ISQ value of 77, it was decided to place an immediate custom chairside provisional composite crown to
a b
FIG 7-7 (a) e maxillary left rst molar showed periapical infection with extensive bone loss buccally and palatally. (b) is 3D image
conrms loss of buccal bone at the apices of the roots of the rst molar. (c) e tooth was decoronated and sectioned to allow removal
of each of the three roots separately. (d) e three roots were removed intact without raising a mucoperiosteal ap. (e) After removal
of the roots, a type A IRS remained, with its narrowest diameter being 4 mm and with intact socket soft tissue walls.
c
d
e
127
Sample Cases
support soft tissue healing and deliver some nonocclusal loading to accelerate bone healing.
47,48
When
the custom healing abutment was ready for insertion,
a PRF clot prepared from the patient’s venous blood
was skewered over the crown retention screw and the
latter screwed into place45 (Figs 7-7l to 7-7o). After 3
months of healing (Figs 7-7p to 7-7r), implant stability
was recorded as ISQ 81, and 1 month later, the denitive restoration was placed (Figs 7-7s and 7-7t). Both
clinical and radiographic images of the implant and
crown can be seen after 3 years in function in Figs
7-7u and 7-7v.
FIG 7-7 (cont) (f) A pilot drill was used to establish the initial osteotomy
depth of 10 mm. (g) A radiograph taken after using the rst densication
bur conrmed that the sinus oor remained intact. (h) After using the
required sequence of densifying burs, the osteotomy was seen to have
been expanded and fully contained in the type A IRS. (i) e insertion
torque required to seat the 10 × 5–mm implant was 40 Ncm. (j) A radiograph taken after implant insertion conrmed ideal positioning for a
molar crown. (k) Allograft was placed in the peri-implant gaps with slight
overll to compensate for possible shrinkage during healing. (l) e
implant had an insertion torque of 40 Ncm and ISQ value of 77, and with
this degree of stability, it was decided to place an immediate custom
chairside fully contoured composite healing abutment. (m) e healing
abutment was fabricated and adjusted to allow for immediate, nonocclusal
loading while protecting the graft material. (n) An autogenous PRF clot
that had been prepared from the patient’s venous blood was stretched
over the retention screw and base of the restoration as a biologic seal
between the graft particles and the restoration.
44
(o) e fully contoured
custom healing abutment was adjusted to experience nonocclusal loading
only.
f g h
i j k
l m n
o