cast based guided implant placement /certified fixed orthodontic courses by Indian dental academy

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


SURGICAL GUIDE
 GPT 8: a guide used to assist in proper surgical

placement and angulation of dental implants.
 DESIGNS:

Nonlimiting,
Partially limiting,
Completely limiting


• Designs of surgical guides:
 Nonlimiting design

provides the surgeon an
indication as to where the proposed prosthesis is in
relation to the selected implant site.
 Partially limiting design
offers the possibility to have
a guide sleeve direct the first drill used for the osteotomy.
 The remainder of the osteotomy and implant placement is
then finished freehand by the surgeon.


 The completely limiting design

restricts all of the
instruments used for the osteotomy in a buccolingual and
mesiodistal plane.
 The addition of drill stops limits the depth of the
preparation and, thus, the positioning of the prosthetic
table of the implant.
 As the surgical guides become more restrictive, the ease
and precision of implant placement is enhanced.
 Information acquired in the preoperative planning phase is
transferred to the surgical guide.


 If a completely restrictive guide is relied upon during

implant placement, the surgeon must ensure that the
clinical data has been accurately transferred to the surgical
guide.
 Guides that are not completely restrictive require
interoperative radiographs to confirm the mesiodistal
trajectory; the initial twist drill.
 Since, with guides that are not 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 completely restrictive
guide.

 Bone sounding has been used in clinical dentistry to

acquire an understanding of the thickness of the soft tissue
overlying the bone.
 By subtracting the thickness of the soft tissues from the

total width of the alveolar ridge, an estimation can be
made of the bone volume at the measured sites.
 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.
 The x-axis is clinically the mesiodistal plane,
 the y-axis represents the buccolingual plane, and
 the z-axis determines the length at the apex of the implant

and the depth of the prosthetic table at the top of the
implant.


 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, available bone volume,
again in combination with the prosthesis, will guide the
desired implant location.
 Considering the final axis, the position of the top of the
implant is based on clinical parameters and desires, while
the length of the implant is generally set by the proximity
to anatomic structures or body cavities.


 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 surgical guide is then used, following established
guided surgery protocols, to place a dental implant.
 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.

TECHNIQUE
Data acquisition:
 1. Select a stock impression tray
 2. Palpate the area of the proposed implant site and
determine if there are areas susceptible for soft tissue
deformation.
 3. Apply a utility wax strip to the tray, to create positive
pressure on the easily deformed areas.
 4. Use irreversible hydrocolloid to make the impression.
 5. Use a pinless tray and die system to section the cast, and
reposition the sections in the correct spatial relationship.
 6. Create a cast by casting the impression with, lowviscosity, casting vinyl polysiloxane (VPS), while casting
the base with a medium-viscosity VPS material.

• 7. Remove the
impression from the cast
once the material has
polymerized.
 8. Make a partial
overimpression over the
soft tissue area and
adjacent teeth of the
proposed implant site
with a stiff VPS material.
 9. Fit a sterile (27 G)
dental needle with an
endodontic rubber stop
at the apex of the needle.

Crestal penetration of measuring needle

 10. Anesthetize the patient as needed. Make the first

measurement at the crest of the edentulous ridge.
 11. Remove the needle from the measured site and record
the distance between the apex of the needle and the rubber
stop, as the thickness of the soft tissue at the crest.
 12. Make the second measurement on the buccal surface at
the most apical part of the proposed implant site which is
still accessible.
 13. Make the third measurement in a similar position on
the lingual surface, while measurements 4 & 5 are made in
between the crest and most apical portion.


 Transfer of clinical data to the cast
 14. 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.
 15. Adjust the digital image using an image manipulation
program to create a true1:1 image.
 17. On the modified radiograph, use scissors to cut out the
bone between the root structures and the occlusal surface
of the teeth.
 18. Place the modified radiograph on the cast, to coincide
with the occlusal and interproximal surfaces onthe cast.

 19. Outline the position

of the root structures on
the cast with a pen. Mark
the area available for
implant placement in the
mesiodistal direction.
 20. Mark the best
position for the midline
of the proposed implant.
 21. Remove the cast from
the Accu-Trac.
 22. Cut the cast exactly in
the selected plane with a
large 45-mm diamondcoated disk.

Transposition of root structure onto cast

Cast sectioned at proposed axis of implant

 23. Select 1 portion of the sectioned cast to transfer the
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clinical tissue depth measurements.
24. Mark the depths on the cast in positions similar to
those from which they were acquired clinically.
25. Connect the marking points, and mark with red ink the
tissue surface above the line. Visualize the underlying area
of the available bone volume in the buccolingual plane.
26. Select the implant diameter based on the availability of
bone in both the mesiodistal and buccolingual planes.
27. Determine the axis for the buccolingual plane, guided
by the availability of bone and the prosthetic
reconstruction.
28. Mark the axis on the cast. Transfer the position of the
axis onto the gingival crest, as this will later indicate the
starting point for the cast osteotomy.

 29. Mark the depth of the implant platform with a

horizontal line perpendicular to the implant axis. Follow
the parameters as determined by the available bone and
the emergence profile of the prosthetic crown; most often
this will range from 2 to 3 mm from the proposed buccal
marginal gingival border.
 30. Place the marked cast piece back into the Accu-Trac
tray and place both onto a survey table. Orient the cast to
the previously identified path of insertion.
 31. Place a drill bit, the size of the selected implant
diameter, in the chuck of a drill press.
 32. Lower the press, to place the drill at the height of the
cast on the surveyor table.

 33. Unlock the table, and place

the sectioned part of the cast
against the drill to transfer the
mesiodistal plane
• 34. Rotate the table to coincide
with the marking of the
buccolingual axis, while taking
care to not change the
previously established
mesiodistal plane.
 35. Lock the surveyor table, and
confirm both planes to be
parallel with the drill bit.
 36. Remove the Accu-Trac tray
from the surveyor table, and
reposition the remaining
section of the cast in the tray.
Close the hinges of the tray so
the sections again relate to each
other as before sectioning.

Orientation of drill bit for mesiodistal plane.

Orientation of drill bit for buccolingual plane.


 37. Place the Accu-Trac tray back

onto the surveyor table, then move
the cast under the drill bit. Lower
the drill on the marking on the
crest, indicating the buccolingual
axis.
 38. Make the cast osteotomy at a
depth slightly deeper than the
length of the implant laboratory
analog.
 39. Remove the Accu-Trac tray
Occlusal view of completed cast osteotomy.
from the surveyor table, open and
remove 1 section of the cast.
Visually inspect the buccolingual
cast osteotomy as made and
reaffirm that it is correct before
proceeding.
 40. Position a laboratory implant
analog in the section of the cast
osteotomy, with the platform at the
previously selected depth. Secure
with cyanoacrylate glue.
Laboratory analog at selected platform depth.


 41. Coat the contralateral part of

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the cast osteotomy with
cyanoacrylate glue, mate the cast
sections in the Accu-Trac tray, and
close the tray.
42. Remove the area above the
analog and between the adjacent
teeth with a scalpel to start the
creation of simulated gingival
tissue.
43. Place a 2-mm healing cap onto
the analog.
44. Perforate the previously made,
preoperative, stiff VPS impression
at opposing sites and reposition the
preoperative impression on the
cast.
45. Inject a heavy-body polyether
impression material. Once the
material has polymerized, cut the
soft tissue mask to simulate the
desired emergence profile.

Platform placed 2 mm below proposed
buccal free gingival margin.


 Transfer of the cast information
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to the surgical guide
46. 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.
47. Assemble a laboratory guide Modified sleeve positioned on laboratory pin.
pin onto the laboratory analog
in the cast.
48. Bend the wires to create a
framework around the teeth.
49. Place a 2-cm section of
polyethylene tubing over the top
of the laboratory guided
cylinder pin to prevent overflow
of the VPS material over the top
of the guide sleeve.
Wires bent to create supporting framework.

 50. Isolate the cast with a spray of

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separator, as both materials are
VPS and otherwise will bind
together.
51. Perforate a small disposable
plastic impression tray so that it
will fit over the tubing.
52. 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.
53. Upon the completion of
polymerization, unscrew and
disassemble the guided laboratory
pin.
54. Remove the buccal and lingual
walls next to the guide sleeve to
create access for the clinical
surgical instrumentation.

Application of stiff VPS.

Completed surgical guide; note relationship with
laboratory analog and future implant platform.

 55. Place the completed surgical

guide intraorally and make a
periapical radiograph parallel to
the occlusal portion of the
sleeve.
 56. Extend the lateral borders of
the sleeve on the radiograph
and confirm the correctness of Radiograph to confirm correctness of
mesiodistal trajectory.
the mesiodistal trajectory.
 57. Fabricate the provisional
restoration or definitive
abutment-provisional
restoration combination, since
the exact position of the
implant is known before the
surgery. Mark the position of
the orientation lobe of the
analog to the surgical guide.
Provisional restoration premade on cast
previously used for surgical guide fabrication.


Implant placement surgery
 58. Prepare and anesthetize
the patient as needed.
 59. 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.
 60. Place a 2-mm drill guide
in the sleeve, to allow precise
guidance of the 2-mm drill.
 61. Place a drill stop on the 2mm and subsequent drills at
the implant length plus 10
mm, per the system
requirements.

Tissue perforation start drill guided
through surgical guide.

Twist drill with limiting depth stop, guided
through surgical guide.


 62. Gradually enlarge the

osteotomy, depending on the
diameter and the resistance
of the bone, to the
appropriate size. Guide each
drill by the corresponding
drill guide.
 63. Place the implant on the
guided implant mount, and
introduce it through the
guide into the osteotomy.
Ensure that the implant
mating surface is in the same
orientation intraorally as on
the cast, so that the
abutment or screw
provisional will be correctly
orientated.

Relationship of dental implant to surgical
guide and, thus, intraoral situation.

Hand torquing of implant; note position of
internal lobe markings.


 64. Remove the implant mount

and use a tissue punch to clean
soft tissue tags that might
interfere with the seating of the
prosthetic components.
 65. Place the screw-retained
provisional restoration or
abutment/provisional
restoration combination if
sufficient initial stability (35
N/cm) is obtained, as indicated
by the insertion torque device.
 66. Ensure that the provisional
restoration does not have
interproximal and occlusal
contact, as to limit excess
motion during the
osseointegration healing period.

Postoperative radiograph.

Provisional restoration in place. Note lack of
occlusal and interproximal contacts.


DISCUSSION
 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, in an expedient manner.
 In addition, the properties of the VPS material allow for
easy handling during the remainder of the process.
 Since the cast must be transversely cut, a system to
reposition the cast pieces back into the correct relationship
is used.
 Traditionally, pin systems are used for sectioned casts, but
if the cast is fabricated in the dental office, a pinless
system, like that described, may facilitate the process.

SUMMARY
 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.


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cast based guided implant placement /certified fixed orthodontic courses by Indian dental academy