Creativity in Dental Implants

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Creativity in

Dental Implants

by Dr. Jason Luchtefeld Private Practice

Pompano Beach, Florida

Educational objectives:

Upon completion of this course, participants should be able to achieve the following: • Effectively evaluate candidates for dental implants – surgically and restoratively. • Begin to analyze implant design and how it relates to the patient.

• Analyze the implant restoration possibilities.

• Provide instructions to the lab for the implant restoration.

• Insert and maintain the implant and restoration for the life of the patient. Dental implants are the standard for tooth replacement today. They come in all shapes and sizes. Placement and restoring options are nearly unlimited. The deter-mination in which patients are good candidates as well as performing treatment on those selected patients can create problems. The objectives of this article are to pro-vide you with a basic foundation to select patients, evaluate surgical sites, select an implant, and then restore the implant.

In the selection process for any and all phases of implant dentistry we must keep specific goals in mind. The restoration of the patient must result in adequate form, function, comfort, aesthetics, and speech. Occasionally, a compromise will be nec-essary. We will review these items briefly for each case presented.

We will begin with implant design, move onto bone evaluation (site selection), and then into restorative options and cases. An extensive review and explanation of every area of implant design would require a textbook (Misch has two excellent choices). For the sake of space and time we will simply review a few of the impor-tant concepts.

Dentaltown is pleased to offer you continuing education. You can read the following CE article in the magazine and go online to www.dentaltown.com to take the post-test and claim your CE credits, free-of-charge,

or you can mail in your post-test for a nominal fee. See instructions on page 74.

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Dentaltown.com, Inc. is an AGD PACE Recognized Provider. This course offers 2 AGD PACE Continuing Education Credits free-of-charge.

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Implant Design

Thread design

Each thread design is going to place specific stresses on the bone. A cylinder will place predominantly shear stresses on the bone when loaded while a square thread will place predominantly compressive force. Typically, bone responds more favor-ably to compressive force and negatively to shear stress. The square thread should be able to withstand more load. With this in mind one should consider the poten-tial load and bone type when selecting an implant.

Selecting implant length and width

Longer implants have increased initial stability. This has increased importance in soft bone, immediate extraction sites, and immediate load situations. Once heal-ing has occurred, differences in length have less importance… to a point. Historically, implants less than 10mm in length had significantly lower long-term success rates. More recent research is showing that we might have a little more flex-ibility in this area.

Implant width is most important in load distribution. The coronal few millime-ters of the implant places the most stress on the bone. A wider implant will distrib-ute those forces over a larger area. Typically, the widest implant for a given site is the best to use. However, this statement gets modified when considering aesthetic areas, adjacent teeth, and bone quality. Most importantly, vital structures must be evaluated prior to implant placement. The placing doctor must have knowledge of the location of the sinuses, vascular structures, nerves, and adjacent teeth.

Functional surface area

“The area that actively serves to dissipate compressive and tensile non-shear loads through the implant-to-bone interface and provide initial stability of the implant following surgical placement.” – Carl E. Misch

Teeth are uniquely designed to function ideally for the site in which they are located. An implant replacing a given tooth should be selected to best receive the forces that tooth is designed to receive. The average human premolar has a func-tional surface area of 195mm2_{(figures 1 and 2). A cylinder implant that is 4mm x} 10mm has a surface are of 138mm2_{, while a threaded implant of the same size will} have a surface are of 110mm2_{– 210mm}2_{depending on the manufacturer. Check} with the manufacturer of the implant system you are using in order to find out what the functional surface area is of their implant.

Abutment connection

We will be demonstrating the internal connection in the cases presented here. Bone

Available bone is categorized using the Misch-Judy Classification. Type A – >5mm width (buccal-lingual dimension), >10mm height (vertical),

>7mm length (mesial – distal dimension), <30 degrees angulation, and a crown-implant ratio better than 1:1.

Type B – Barely sufficient in 1 or more measurement Type Bw – Barely sufficient width

Type Cw – Compromised width Type Ch – Compromised height Type D – Deficient.

continued on page 66 Thread Designs

Photos courtesy of BioHorizons.

Cylinders Reverse Buttress

V-Shaped Square

Figure 1 Figure 2

Photo courtesy of BioHorizons.

Misch-Judy Classification A Abundant

B Barely Sufficient Bw Barely Sufficient Width Cw Compromised Width Ch Compromised Height D Deficient

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When B or Bw is found you might either modify the site to place a standard size or use a slightly smaller implant. Clinical judgment should be utilized to deter-mine the best protocol. Type Cw and Ch will require modification prior to implant placement; typically, this will involve bone grafting of some type. Type D available bone will require significant modification for implant placement or no implant placement at all.

Bone density

Bone density is a critical factor in implant placement. Very dense bone is less vascular, more difficult to drill through, and provides an environment for more compressive force. On the other hand, very soft bone will have a tendency to be more vascular, easy to drill through, and provide an environment where there is more shear stress and less compressive stress.

Implant selection should take bone density into consideration. Soft bone (D3 and D4) might require an implant with more surface area and/or a square-type thread design to adequately distribute the load to the bone.

Bone density is related to bone strength. D1 bone is the strongest. It is 10 times stronger than D4 bone. Again, keep this in mind when selecting an implant, plac-ing the implant and then restorplac-ing that implant.

After placement of an implant in bone, there is a window of time where the bone remodels and integrates the implant. This window of time and the bone response is partially dependent on the surgical procedure. The procedure should be such that bone is kept as cool as possible. Alterations in drill sharpness, speed, con-tact time, depth, pressure, and speed can help depending on the bone density the surgery is taking place upon.

Restoration

Implants are currently being restored anywhere from the same day to several months after the implant placement. The timing in restoring an implant is deter-mined by the factors listed previously (implant designs and bone type) as well as host factors. We will be focusing on the restoration process rather than the various times when the implant can be restored.

This is the section where we will really begin to see how we can evaluate the form, function, aesthetics, comfort and speech.

Provisionalizing the implant

The PEEK abutment is a replica of the BioHorizons abutment that can be used during the provisional phase of treatment. This would allow soft tissue maturation without having to modify the final abutment. Also, by utilizing the PEEK abut-ment, one could visualize the future shape necessary for the final abutment.

Next we have to decide what kind of final abutment we are going to use. Basically, we have two choices – custom (Figure 3) or stock (Figure 4). What you do with the abutment will determine which you need to use. Both custom and stock abutments can be used in most situations. A custom abutment oftentimes will be more expensive; however, it provides complete customization for a given site. Stock abutments (like the 3inOne abutment from BioHorizons) can usually be modified (either in the mouth or in the lab) to fit a situation. Clinical judgment should be utilized for the best outcome.

When selecting a restoration shape, basic tooth morphology should be followed except for the occlusal surface of posterior teeth. The occlusal surface and buccal cusps of posterior teeth must be reduced to minimize forces transmitted to the continued on page 68 Bone Density

Classification D1 Dense cortical

Anterior mandible

D2 Variable thickness cortical bone with course trabecular within. Posterior mandible

D3 Thin cortical bone with fine trabecular within.

Posterior mandible, anterior maxilla D4 Fine trabecular bone

Posterior maxilla

D5 Immature, non-mineralized bone. Recent extraction sites

A Classification for Restoration Types

as developed by Misch

FP - 1 Fixed restoration that looks like the tooth it is replacing. FP - 2 Fixed restoration that looks

slightly longer than normal. FP - 3 Fixed restoration replacing

tooth and gingival. RP - 4 Removable restoration –

will not be covered here. RP - 5 Removable restoration – will not be covered here.

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implant. Other items to keep in mind include shade, emergence, embrasure shapes, contact position and dimension.

Laboratory communication

Communication with the laboratory technician is an ongoing problem. The technician rarely receives enough information to provide the quality of restoration we prefer. It falls on the dentist’s shoulders to provide proper information concern-ing the implant type, position, shade, opposconcern-ing teeth and adjacent teeth in order for the technician to utilize his/her talents. Thorough descriptions, accurate intra-oral records and lots and lots of pictures form the basis of communication for the laboratory technician.

Long-term success is most dependent on proper management of forces trans-mitted to the implant-bone interface. As long as those forces are within the accept-able threshold of the bone, success can be expected. The force factors that must be eliminated, reduced, or balanced are:

-Magnitude -Duration -Direction -Type

-Magnification

Regular monitoring of the implant and restoration is necessary in order to insure these force factors are kept within range.

Case Presentations

Three cases are highlighted for different reasons. Case 1 demonstrates an uncovering and then provisionalization utilizing a PEEK abutment (Figure 5). Case 2 demonstrates a start-to-finish case involving surgery through the final crown. Case 3 demonstrates a start-to-finish case with a slightly different technique. Case 1:

An implant was placed in area of tooth #12. After healing the implant is ready to be uncovered and provisionalized for soft tissue healing/contouring (see figure 1a). This particular patient will be in a provisional for an extended period of time, so we will utilize the PEEK abutment rather than the final abutment. This allows us to develop and maintain proper tissue contours for later. It also allows us to visu-alize the necessary shape for the final abutment and crown.

Just enough tissue removed to expose the platform of the fixture. Notice the nice band of keratinized tissue remaining. The PEEK abutment is placed (figure 1b).

Another view of the PEEK abutment in place. Small lines have been digitally drawn to demonstrate approximately where we will want to contour the PEEK abutment initially (figure 1c).

A view of the prepared PEEK Abutment. Note similarity in shape to the pre-pared tooth #13 (figure 1d).

Another view of the PEEK abutment (figure 1e).

A typical provisional is then fabricated and then cemented in place. Various views of the provisional are pictured:

Buccal View (figure 1f ) Emergence view (figure 1g) Occlusal view (figure 1h)

continued on page 70 Fig. 5 Fig. 1a Fig. 1b Fig. 1c Fig. 1d Fig. 1e Fig. 1f Fig. 1g Fig. 1h

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Case 2:

This next case is a demonstration of a tooth removal, implant placement and then restoration. In this case tooth #13 fractured at the gum line (figure 2a). The tooth was extracted and the socket grafted and left to heal. After healing (figure 2b) a 4mm x 12mm BioHorizons implant was placed (figure 2c). At this point it is important to evaluate the bone level on the implant. The threads must be visible in the radiograph to adequately evaluate the bone height on the threads. If the threads are blurry a new radiograph should be taken at the proper angle. This site had soft bone (Type D3), plenty of available bone (Type A), and contours to allow for an FP-1 restoration. In a case like this, the drilling sequence can go very fast because the bone is very easy to cut through. The implant initial stability is enhanced by the length and thread design.

Upon uncovering the BioHorizons 3inOne abutment was placed (figure 2d). This was then pre-pared in the mouth to normal tooth preparation contours (figure 2e). A standard crown and bridge

impression is taken (figure 2f ). A standard laboratory prescription asking for shade, contour, and occlusal specificity is all that is necessary. The laboratory will fabricate a beautiful crown for cementation. Figure 2g demonstrates a buccal view of the final restoration with slightly shorter buccal cusp to

reduce chances of interference. Figure 2h shows the occlusal view and slightly smaller occlusal table ideal for implant restorations. Finally, figure 2i reveals the final radiograph of an integrated implant with proper fitting restoration. Note form, function, comfort, aesthetics and speech.

Case 3:

Our final case is another full surgery through restoration case. This one, however, involved a little more creativity in the use of the BioHorizons sys-tem. This patient had an existing bridge and was interested in other options for the area (figure 3a). We decided implants could be a great option so he was sent for a panoramic radiograph to help identify

bone levels in relationship to the IAN, as well as tooth root positions (figure 3b). Prior to placement, we also palpated lingually to determine any excessive lingual concavity. Since I had a tooth mesial and distal to the surgical site, I did not fabri-cate a surgical stent; however, it is wise to always have one ready.

I determined bone availability to be Type Bw. With this in mind, we discussed bone grafting to add bone or to utilize a slightly smaller diameter implant and then splint them together. We opted for the latter option.

We anesthetized and began to place two BioHorizons implants. Upon begin-ning I found the bone to be incredibly soft – a Type D4 bone. In these instances you must be able to visualize the implant placement height level because you can

Fig. 2d Fig. 2e Fig. 2f Fig. 2g Fig. 2h Fig. 3b Fig. 3c Fig. 2a Fig. 2b Fig. 2c Fig. 2i Fig. 3a continued on page 72

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easily overtorque during insertion and strip the osteotomy (figure 3c). The abutments were removed and transmucosal healing abutments were placed (figure 3d). These allow soft tissue contouring dur-ing healdur-ing and avoids a second surgery.

After sufficient healing the abutments were removed and the 3inOne abutment was inserted with a ball top screw (figure 3e). A radiograph was taken to verify seating (figure 3f ). The ball top screw allows an easy transfer to the laboratory. After a stan-dard impression, the abutment and ball top screw were removed and then attached to an implant ana-log (figure 3g). These were then inserted into the impression using the ball as a positive seat and the flat surface of the abutment as reference (figure 3h).

The laboratory could now pour the model. They replaced the ball top screw with a normal screw and then prepared the abutments to ideal contours (fig-ure 3i). In this case, I sent pict(fig-ures and a description of tissue heights so they could prepare the abut-ments accordingly and then fabricate the crowns.

The lab returned the abutments, an index, and the crowns. The crowns were inserted and seating was verified (figure 3j). Once they were torqued into place, the crowns were tried on (in this place splinted crowns). Seating was verified (figure 3k). Form, function, comfort, aesthetics, and speech were verified (figure 3l).

Dr. Jason Luchtefeld is a general dentist in Pompano Beach, Florida. He practices all aspects of general dentistry with a par-ticular interest in implant dentistry. Dr. Luchtefeld graduated from Southern Illinois University School of Dental Medicine in 2000. He then completed a GPR at the VA Medical Center in Denver, Colorado.

Dr. Luchtefeld achieved his Fellowship in the AGD in 2005 in Washington, D.C. In 2006, he completed the Misch Institute dental implant surgical training program. Finally, in 2007 he was awarded his Fellowship in the ICOI.

Disclosure: Dr. Luchtefeld declares having received an honorarium from BioHorizons Implant Systems, Inc. for this course.

Author’s Bio

This CE activity is supported by an unre-stricted grant from BioHorizons.

Fig. 3d Fig. 3e Fig. 3g Fig. 3h Fig. 3i Fig. 3l Fig. 3f Fig. 3j Fig. 3k References

Butz, et al., Three-dimensional bone-implant inte-gration profiling using micro-computed tomography. Int J Oral Maxillofac Implants. 2006 Sep-Oct;21(5):687-95

Grassi S, et al., Histologic evaluation of early human bone response to different implant surfaces. J Periodontol. 2006 Oct;77(10):1736-43. Misch, Carl E., Contemporary Implant Dentistry.

1999

Misch CE, Oral Health 2000;8:7-15 Misch, ce Dent Today. 2002 Sep;21(9):76-81 Misch, Carl E., Dental Implant Prosthetics. 2005 Novaes AB Int J Oral and Maxillofac Implants

2002;17:377-383

Piattelli M J Oral Implantol 2002;28:2-8 Quek et al., Int J Oral Maxillofac Implants. 2006

Nov-Dec;21(6):929-36

Steigenga et al J Periodontol. 2004 Sep;75(9):1233-41

Tolstunov, Implant Dentistry 2006 Dec., 15 (4): 341-344.

Personal experience…

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1. Which of the following are objectives of implant dentistry? A. Form B. Function C. Aesthetics D. Comfort E. Speech

F. All of the above

2. Which bone classification is desig-nated as “barely sufficient” for implant placement?

A. Type A B. Type B C. Type Cw D. Type D

3. Which bone density is the strongest? A. Type D1

B. Type D2 C. Type D3 D. Type D4 E. Type D5

4. True or false? An implant restoration should have a larger occlusal table to

insure sufficient force is placed upon the restoration and implant.

A. True B. False

5. Which of the following should be evaluated prior to implant surgery? A. Radiographic bone height B. Gingival levels

C. Sinus location D. IAN location E. All of the above

6. If your final radiograph to evaluate the implant placement shows com-pletely blurred threads you should: A. Take another radiograph at the

proper angle.

B. Make a note and take a radi-ograph in two weeks.

C. There is no need to take another radiograph.

7. Which implant thread design pro-vides the most compression to be placed on the bone?

A. Square thread

B. Reverse buttress thread C. V-shaped thread

8. True or false? The ball top screw is the retention for the final restoration to stay in place.

A. True B. False

9. True or false? The 3inOne abutment can be modified by the laboratory to provide ideal contours for the restoration. A. True

B. Falsew

10. An implant restoration should have which of the following?

A. Smaller occlusal table than an average tooth it is replacing. B. Larger occlusal table than an

aver-age tooth it is replacing.

C. Taller non-working and working cusps.

D. Shorter non-working and work-ing cusps.

E. A and D are correct.

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