cast based guided implant placement/ general dentistry

INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

To aid the surgeon in this endeavor,many types of surgical guides
have been proposed
Design concepts vary from
1. nonlimiting,
2. partially limiting
3. completely limiting surgical guides

Information acquired in the preoperative planning phase is
transferred to the surgical guide.
Since with guides that are completely restrictive, the exact
position of the implant is not known before surgery, the
prefabrication of a provisional restoration might be less precise
compared to a provisional restoration developed following
the fabrication of the nonlimiting guide

Bone sounding has been used in clinical dentistry to acquire an
understanding of the thickness of the soft tissue overlying the
bone.
Perez et al have shown that this technique provides a depiction of
available bone volume that is slightly less than is actually
available. Clinically,this provides the clinician reliable information
with a small margin of safety.
By subtracting the measured tissue thickness of the
corresponding sites on a dental cast, a 3-dimensional (3-D)
representation of the bone volume will be created. Within this
volume of bone, the correct position of the dental implant can be
established.

When determining the position of a dental implant, 3 axes must
considered separately
When considering the position of the implant in the mesiodistal
plane, the proximity to the adjacent teeth is the greatest limiting
determinant, followed by the requirements of the prosthetic
reconstruction.
In the buccolingual direction, the available bone volume, again in
combination with the prosthesis, will guide the desired implant
location.

This article demonstrates a combination of analog techniques to
produce a surgical guide, allowing placement of a dental implant in
a precise predetermined position.
The surgery is a flapless procedure, improving patient comfort.
Since the implant position relative to the surrounding dentition is
known, a provisional restoration and, if desired, the definitive
abutment, can be prefabricated, so that it can be inserted at the
time of surgery if an immediate provisional restoration is desired.

Data acquisition
Select a stock impression tray
Palpate the area of the proposed implant site and determine if
there are areas susceptible for soft tissue deformation.
Apply a utility wax strip
Use irreversible hydrocolloid

Use a pinless tray and die system
Create a cast by casting the impression..
Remove the impression from the cast once the material has
polymerized.
Make a partial overimpression over the soft tissue area and
adjacentteeth of the proposed implant site with a stiff VPS
material.

Fit a sterile 0.4 x 8-mm (27 G) dental needle with an endodontic
rubber stop
Anesthetize the patient as needed. Make the first measurement

Remove the needle from the measured site and record the
distance
Make the second measurement on the buccal surface
Make the third measurement in a similar position on the lingual
surface, while measurements 4 and 5 are made in between the
crest and the most apical portion.

Make a periapical radiograph of the proposed site in such a way
that foreshortening or elongation is prevented and the image is
dimensionally true, while capturing the apices of the adjacent
teeth as much as possible.
Adjust the digital image using an image manipulation program
(Photoshop CS3; Adobe Systems, Inc, San Jose, Calif ) to create
a true 1:1 image
From the IMAGE menu, select SIZE, set the image size to the
size of the digital radiograph sensor in millimeters, SAVE, then
PRINT. The printed image is now 1:1. Use conventional
analog film as is.

On the modified radiograph, use scissors to cut out the bone
between the root structures and the occlusal surface of the teeth.
Place the modified radiograph on the cast, to coincide with the
occlusal and interproximal surfaces on the cast .

Outline the position of the root structures on the cast with a pen.
Mark the area available for implant placement in the mesiodistal
direction.
Mark the best position for the midline of the proposed implant.
Remove the cast from the Accu-Trac (Coltene/Whaledent, Inc).
Cut the cast exactly in the selected plane with a large 45-mm
diamond- coated disk

Select 1 portion of the sectioned cast to transfer the clinical tissue
depth measurements.
Mark the depths on the cast in positions similar to those from
which they were acquired clinically.
Connect the marking points,
Select the implant diameter based on the availability of bone in
both the mesiodistal and buccolingual planes.

Determine the axis for the buccolingual plane, guided by the
availability of bone and the prosthetic reconstruction.
Mark the axis on the cast.
Mark the depth of the implant platform with a horizontal line
perpendicular to the implant axis.
Place the marked cast piece back into the Accu-Trac tray

Place a drill bit, the size of the selected implant diameter, in the
chuck of a drill press
Unlock the table, and place the sectioned part of the cast against
the drill to transfer the mesiodistal plane

Rotate the table to coincide with the marking of the buccolingual
axis, while taking care to not change the previously established
mesiodistal plane

Lock the surveyor table, and confirm both planes to be parallel
with the drill bit
Remove the Accu-Trac tray from the surveyor table, and
reposition the remaining section of the cast in the tray.
Place the Accu-Trac tray back onto the surveyor table, then move
the cast under the drill bit
Make the cast osteotomy at a depth slightly deeper than the
length of the implant laboratory analog

Remove the Accu-Trac tray from the surveyor table, open and
remove 1 section of the cast. Visually inspect
Position a laboratory implant analog in the section of the cast
osteotomy, with the platform at the previously selected depth.
Secure with cyanoacrylate glue

Coat the contralateral part of the cast osteotomy with
cyanoacrylate glue
Remove the area above the analog and between the adjacent
teeth
with a scalpel to start the creation of simulated gingival tissue.
Place a 2-mm healing cap onto the analog.
Perforate the previously made, preoperative, stiff VPS impression
at opposing sites and reposition the preoperative impression on
the cast.

Inject a heavy-body polyether impression material .Once the
material has polymerized, cut the soft tissue mask to simulate the
desired emergence profile

Select a guide sleeve consistent with the selected implant width
Weld 2 sections, 10 cm by 0.5 mm, of metal wire to the lateral
sides of the sleeve

Assemble a laboratory guide pin (Nobel Biocare USA) onto the
laboratory analog in the cast.
Bend the wires to create a framework around the teeth

Place a 2-cm section of polyethylene tubing over the top of the
laboratory guided cylinder pin
Isolate the cast with a spray of separator , as both materials are
VPS and otherwise will bind together.
Perforate a small disposable plastic impression tray so that it will
fit over the tubing.

Inject a stiff VPS occlusal record registration material surrounding
the teeth and the guided cylinder. Place the plastic impression tray
over the tubing and VPS

Upon the completion of polymerization, unscrew and disassemble
the guided laboratory pin.
Remove the buccal and lingual walls next to the guide sleeve to
create access for the clinical surgical instrumentation .

Place the completed surgical guide intraorally and make a
periapical radiograph parallel to the occlusal portion of the sleeve
Extend the lateral borders of the sleeve on the radiograph and
confirm the correctness of the mesiodistal trajectory . Disinfect the
approved guide for 12 minutes in a disinfectant

Fabricate the provisional restoration or definitive abutment-
provisional restoration combination, since the exact position of the
implant is known before the surgery.

Prepare and anesthetize the patient as needed.
Place the surgical guide and introduce the tissue punching drill
with water irrigation through the sleeve. Puncture the soft tissue
and create a starting point for the osteotomy

Place a 2-mm drill guide in the sleeve, to allow precise guidance
of the 2-mm drill.
Place a drill stop on the 2-mm and subsequent drills at the implant
length plus 10 mm, per the system requirements

Gradually enlarge the osteotomy, depending on the diameter and
the resistance of the bone, to the appropriate size
Place the implant on the guided implant mount , and introduce it
through the guide into the osteotomy.
Make the lobe marking on the implant mount to correspond with
the lobe mounting on the surgical guide. Ensure that the implant
mating surface is in the same orientation intraorally as on the cast

Remove the implant mount and use a tissue punch to clean soft
tissue tags that might interfere with the seating of the prosthetic
components.
Place the screw-retained provisional restoration or
abutment/provisional restoration combination if sufficient initial
stability (35 N/cm) is obtained

Ensure that the provisional restoration does not have
interproximal and occlusal contact, as to limit excess motion
during the osseointegration healing period

Fabrication and use of a simple implant placement guide:
Richard J. Windhorn, (J Prosthet Dent 2004;92:196-9.)
This article describes an acrylic resin implant placement
guide which is simple to fabricate and easy to use.
This device guides the surgeon in the precise position and
angulation planned for the implant, yet allows for some flexibility in
the event slight adjustments are necessary during surgery

Diagnostic cast with wooden stick in
place.
Handpiece head in place on wooden stick as
reference for molding acrylic resin.
Trimmed acrylic guide placed back on cast with reference line drawn on vertical wall.www.indiandentalacademy.com

Implant surgical guide fabrication for partially
edentulous patients :Jeffrey L. Shotwell, et al
J Prosthet Dent 2005;93:294-7.
This article presents an innovative method for the fabrication
of implant drill guides for partially edentulous patients. Using
a light-polymerized composite material and drill blanks
placed in the prosthodontically driven implant position,
surgical guides for each implant drill are constructed on the
diagnostic cast.

Light-polymerizing material adapted and
contoured at buccal aspect to provide reference
to proposed gingival margin of restoration.
Orientation of cast with aid of dental surveyor to
establish proper angulation of implant
Implant site with reference lines drawn to determine
bucco-lingual as well as mesio-distal placement of
implant. www.indiandentalacademy.com

Drill blank placed in opening showing orientation of
proposed implant and light-polymerized material
adapted to cast and drill blank from lingual aspect.
View of implant drill guide used during
implant site osteotomy.
View of presurgical
radiographic guide, and
drill guides for each
implant drill (from bottom
to top).

A surgical guide for dental implant placement in
edentulous posterior regions :Saadet Saglam Atsu,
J Prosthet Dent 2006;96:129-33.
This article describes a simple technique for fabricating a
vacuum-formed surgical guide to assist in dental implant
placement in edentulous posterior regions

Implant sites prepared through occlusal
surfaces of artificial teeth with dental
surveyor.( vacuum-formed, rigid clear template)
Stainless steel tubes placed in channels
drilled through artificial teeth.
Smaller metal tubes inserted into larger metal tubes to
facilitate drilling pilot holes for implant placement Surgical guide.www.indiandentalacademy.com

Since the volume of the cast is used to subtract the measured
thickness of the overlying intraoral tissue, it is imperative that the
relationship of the soft tissue to the bone is determined correctly.
Areas that might be susceptible for errors are the tissue overlying
the lingual concavity of the posterior mandible and the buccal
mucosal fold
Conventional impressions are cast in a dental stone. While this is
a viable technique, this article proposes the use of a stiff VPS. The
material allows for the creation of a cast with acceptable accuracy,

Soft tissue measurements are made to determine the bone
volume
in a buccolingual direction (y-axis); the radiograph is used to
determine the mesiodistal plane (x-axis).
The thickness of the soft tissue overlying the bone is measured at
the middle of the estimated implant site from a mesiodistal
perspective. This position is selected as it is, in most situations,
due to resorption, the narrowest part of the residual ridge, and the
interest is in acquiring knowledge of the smallest dimension
available.

Traditionally, restrictive surgical guides are fabricated with an
autopolymerizing acrylic resin or composite resin.
If in a hard guide, a small area is not correct, it will prevent the
guide from seating completely.
In contrast to a hard guide, a slightly flexible guide will seat
completely even when small discrepancies are encountered. In
addition, this type of guide will snap over the height of contour
of the covered teeth and, thus, be retentive
The fabrication process of the VPS guide is rapid, comparatively
inexpensive,

The surgical implant placement appointment is different compared
to conventional surgery.
All decisions regarding implant positioning have been previously
made. It is a matter of executing the plan according to the
restrictive surgical guide
In the author’s experience, implant and provisional restoration
placement require 5 minutes or less. Although preplanning is more
time consuming

Cast-based guided implant surgery allows for the precise
placement of dental implants with the possibility to continue with
an immediate load protocol.
The fast flapless procedure allows for minimal patient discomfort,
while attaining a high level of precision.
This article describes the unique use of VPS material for the
fabrication of the cast and the surgical guide.

Fabrication and use of a simple implant placement
guide :Richard J. Windhorn, :J Prosthet Dent
2004;92:196-9.
Implant surgical guide fabrication for partially
edentulous patients: Jeffrey L. Shotwell :J Prosthet
Dent 2005;93:294-7.
A surgical guide for dental implant placement in
edentulous posterior regions :Saadet Saglam Atsu,: J
Prosthet Dent 2006;96:129-33.
Atsu SS. A surgical guide for dental implant placement
in edentulous posterior regions. J Prosthet Dent
2006;96:129-33.

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cast based guided implant placement/ general dentistry

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