Gregori M. Kurtzman

Douglas F. Dompkowski

International journal of oral implantology and clinical research january-april 2011;2(1); 31-35

Benefits of CBCT in implant planning

Implant planning in many cases can be very straight forward; yet in some cases ; the remaining anatomy can be deceptive in standard radiograph and clinically.

The growing use of the cone beam computerized tomography ( CBCT ) has given new view to the practitioner on what lies below the soft tissue and within bone.

Age : 46

Sex : Female

Latin American

Chief complaint : Edentulous maxilla prior to age of 20

Wearing denture over 28 years

Dis-satisfied with removable denture and wants implant supported dentures.

Medical history : No significant

Examination : very steep premaxilla with dominant resorption as comparison to cuspid region where bone volume was more.

A CBCT ( Sirona Galileos ) was taken to evaluate the bone for treatment planning.

Using a DICOM file (Galileos software) image analysis and implant planning was done.

Severe resorption was concluded on the premaxilla with sufficient bone on the cuspid region bilaterally and also distal to it.

Virtual implant was place in the software at potential position and the treatment plan was developed.

A new scan with a barium infused CT – stent was decided to be taken to determine the thickness of the soft tissue on the area where implant was to be placed.

Patients current maxillary denture was used as the template for CT – stent.

Using a Lang denture duplicator the denture was duplicated using 40% barium infused acrylic and a addition of 20% barium infused acrylic over the tooth region.

A second CBCT was taken with the patient wearing the barium infused CT – stent.

Using the implant software axial slices were made at the planned implant sites.

The benefit of CBCT is the ability to look at these axial slices which were taken in buccal-lingual direction allowing the practitioner a true determination of the volume of the bone available.

Traditional radiograph do not allow this view and the bone volume can be deceptive in using them to plan implant placement.

Axial slide presented with adequate bone at the implant site and confirmed the need for augmentation to the height at the molar sites via bilateral sinus lift procedure which was carried out in a single appointment.

Analysis of the premaxilla with barium CT stent showed need for extensive cortical block grafting.

Soft tissue gave deception that more volume of bone was present.

If done with traditional radiograph and flapless approach there would have been no bone to drill

Using a co-axis implant ( southern implant , CA USA ) which is available in several diameter and length and provides a prosthetic angle correction in the implant of either 12 to 24 degree

Thus allowing the surgeon to angle the implant to place the fixture in the triangle of the bone but not compromise the prosthesis by having the screw access emerge at the facial or require correction in the abutment to align the fixture.

Greater volume of bone buccal to cuspid and premolar made it the site for implant placement.

Barium CT stent was modified with holes at selected site to accommodate the pilot drill.

For grafting a crestal incision was made from the tuberosity on the right to left and vertical releasing incision was made on the buccal region.

Full thickness flap were elevated with extension to the nasal fossa in the anterior and zygoma in the posterior.

A large window was created in the buccal osseous plate at the molar site and eleveted.

Osteotomies were created in the molar site to accommodate the selected implant diameter and the elevated sinus area was filled with a mixture of autogenous bone and ALLoOss ; a mineralized allograft.

The molar fixture was placed to the proper depth.

The placement head were left on the fixture to help align the co-axis implant that would be placed anterior to the molar site.

The osteotomies were created for the remaining fixtures paralleling the platforms to simplify the prosthetic restorations.

The placement head were removed and cover screw placed.

To remove the undercut and easier anterior prosthetic restoration , second surgery was carried out using a mouldable allograft material ( Regegeform ) was placed from premolar to premolar.

A collagen membrane ( RCM 6 ) was placed over graft and closure was done.

A final CBCT was taken to document the implant position

Enlargement of the posterior segment allows us to see the implants lie within bone in each dimension

To confirm that each fixture is surrounded by osseous tissue at the cervical;

Illustrates how accurate the virtual planning positions can be replicated 3D with actual position after placement

The dentures was modified and relined with soft liner (Premasoft )

A healthy period of 6 months will be allowed for integration of the fixtures and incorporation of the graft.

Good preplanning on implant requires information about bone in all three axis ( X , Y , and Z ) as well as how this bone relates to anatomical features that could hamper placement , such as nerve and sinus.

Traditional radiograph provides 2D image i.e. Only X and Y axis .

CBCT provides 3D image so that the implant can be placed avoiding the important structure and within available bone.