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The major difficulties associatedwith dental implant placementare related to inadequate quantity

and quality of available bone at the pro-posed implant site. Placement ofimplants in sites with inadequate bonemay cause complications such asimpingement on vital anatomic structuressuch as the mandibular canal and neu-rovascular bundle, and perforation of cor-tical plates by implant threads.

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Dental Implants - NewHorizons in Diagnosis andTreatment Planning

From Our Officeto Yours...

The replacement of missingteeth with osseointegrated im-plants has proven to be a reliable,and in most situations, a prefer-able alternative to other fixed andremovable prosthetic devices. Inmost clinical situations, it producespredictable and satisfactory treat-ment results. Abundant researchshows that dental implants haveexceptional long-term survivalrates and a proven ability to main-tain the integrity of the alveolarbone.

This current issue of ThePerioDontaLetter reviews themany new technologies now avail-able to overcome the major diffi-culties associated with implantplacement to ensure their long-term success.

As always, we welcome yourcomments and suggestionsregarding these matters and lookforward to participating with youin implant treatment planning foryour patients.

In an effort to overcome suchanatomic problems, a short implant maybe required and could be too short to sus-tain the occlusal loads to which the result-ing prosthesis will be subjected. Normalbone, and especially bone of poor quality,placed under such levels of functionalloading may result in microfractures ofthe crestal bone adjacent to the implant.This, in turn, can result in loss ofosseointegration.

Figure 1. This patient wanted toreplace two Maryland bridgeswhich were replacing congenitally-missing lateral incisors.

Figure 2. The Maryland bridgeswere removed and minor toothmovement completed prior tosurgery to permit implant placement.

I. Stephen Brown, D.D.S. 220 South 16th Street, Suite 300, Philadelphia, PA 19102 (215) 735-3660

The Brown

I. Stephen Brown, D.D.S., Periodontics & Implant Dentistry

Sites with multiple missing teeth arebest x-rayed with radiopaque markersdefining each of the projected placementsites. Such markers are incorporated into astable template appliance (stent) preciselyfabricated to fit the edentulous ridge and/oradjoining teeth (made from a diagnosticwaxup). It is desirable to supplementpanoramic radiographs with periapicalfilms. In conjunction with bone sounding,this combination of radiographs can pro-duce a good estimate of the three dimen-sions of the edentulous area.

CT Scanning

Computer assisted tomography (CTScan) and complex motion tomography aretwo techniques which are recommended formore complex planning, for multiple sites,and to assess the true width of availablebone as well as its length and height(Jacobs, 1998). Spiral CT (one of severalavailable CT methods) produces extremelyaccurate radiographic data (accurate towithin 0.5mm) with minimal radiationexposure. These scans permit three-dimen-sional visualization of multiple sites with asingle scan of the individual arch to be treat-ed. A newer technique, cone beam CT scan-ning, requires less radiation and is also wellsuited for dental implant treatment studies.

Films produced by the CT scanner canbe viewed in all three planes of space. Themost typical formatting of the CT data pro-duces panoramic, axial, and cross-sectionaloblique views. Utilizing one of several

Furthermore, when implants are placedin bone of poor quality, they often lack ade-quate initial stability. Micromovement ofthe implant of as little as 100 microns(.01mm) causes a fibrous rather than bonyunion, producing an increased incidence ofshort- or long-term implant failure.

Radiographic Techniques

To ensure implant success, thoroughclinical examinations must be supported byradiographic techniques which permit anassessment of the length, height and widthof bone, as well as degree of mineralizationand density. Both Branemark and Mischhave developed classifications of the boneavailable for dental implants which may beused to assist the clinician in case planning.Osseointegration may also be negativelyaffected by local and systemic conditions,such as osteoporosis, menopause, diabetesor smoking. Smoking represents the great-est challenge to the healing response arounddental implants and bone-grafted sites.

With the advent and accessibility ofmore sophisticated radiographic techniquesto evaluate the potential for successfulimplant placement, it is now incumbentupon the clinician to determine what levelof radiographic evaluation is case appropri-ate. The optimum level and quality of radi-ographic information must be obtainedwhile minimizing risk and expense to thepatient. A variety of possibilities existwhich will satisfy the individual and variedneeds of each patient.

In some situations, a single, periapicalfilm obtained using the long cone, parallel-ing technique, may be sufficient; for exam-ple, when immediate implant placementfollowing extraction is anticipated and thesite is well defined, bordered by adjacentteeth and without the presence of associatedpathology. Ensuring implant success usingsingle films is dependent upon radiographicevidence illustrating that the implant can bewell positioned to fill the residual socket.The x-ray film must also provide informa-tion ensuring that the clinician can engagenative bone beyond the former tooth apex,providing the implant with enhanced stabil-ity. Even when sufficient radiographic evi-dence is available, clinical bone soundingalong with a knowledge of tooth root anato-my (size and shape) should be employed tosupport the radiographic findings.

A panoramic radiograph is moredesirable than a periapical radiographalone when the proposed implant lengthcreates a risk of impinging on neurovascu-lar sites, such as the mandibular canal,mental foramen and nasopalatine canal.Adjustments can be made for the inherent25-30% distortion attributed to panoramicfilms by placing a radiopaque marker ofknown diameter in the area to be studied(Babbush, 1991). The measurements canthen be extrapolated to produce usefuldata regarding length and height. It isaxiomatic, however, that panoramic filmscannot define the buccal-lingual (thirddimension) width of the alveolus.Therefore, clinical bone sounding shouldalso be undertaken.

Figure 3. Osteotomes were utilized towiden the edentulous ridge, therebycreating enough buccal-lingual widthfor implant placement.

Figure 4. The ridge expansionallowed for ideal implant placement,which facilitated a pleasing cosmeticrestoration.

Figure 5. A single tooth implant wasdesired to replace the upper firstmolar.

PerioDontaLetter, Winter

available software programs, the cliniciancan simulate the placement of implants onthe computer screen.

Case planning software programs pro-vide the clinician with the opportunity to“place” the implants in optimal positions,making certain that the sites chosen willprovide sufficient surrounding bone foreach implant and good positioning of theimplants in relation to each other. One caneasily alter the locations of the implants toprovide proper functional positioning and,in addition, to measure the quality (density)of alveolar bone surrounding each implantfixture. Software programs for treatmentplanning are available for complex motiontomography and cone beam CT machines.

Using available CT data, in hard copyor on a computer monitor, the current pro-grams can reformat the data into a three-dimensional image from which a stereolith-ographic model can be constructed. Themodel is machined with CADCAM tech-nology into an accurate replica of the hardtissues of the jaw which will receive theimplants.

Using the size and positional data ofthe implants from a CT study created on thecomputer, a surgical template can be fabri-cated which precisely fits the model of thepatient’s jaw. This surgical guide ensuresprecise implant placement in the exact posi-tions and inclinations that were worked outduring the planning process.

Multiple researchers have shown thatthese implant guides can be machined toaccommodate the requisite drill sizes ofmost implant systems. The clinical applica-

tion of this methodology allows the clini-cian to create implant osteotomies, with arotational error of less than two degrees anda translation error of less than 0.3mm.

The availability of such precise drillingtolerances opens the door for flapless, lessinvasive surgery and permits the placementof implants directly through the soft tissues.This technique has been developed for com-pletely edentulous (all bone supported) sur-gical guides, as well as tooth- and soft tis-sue-supported guides for partially dentatepatients.

As the cost of computed tomographycontinues to decline and the availability ofsuch sophisticated placement methodsincreases, the use of CT scans becomesmuch more advantageous when indicated.Recently there have been some reports inthe literature regarding the future potentialof Magnetic Resonance Imaging, whichuses no ionizing radiation, for dentalimplant application.

We are excited about these new hori-zons in implant diagnosis and treatmentplanning as they continue to expand ourability to provide quality services. Alongwith currently available regenerative proce-dures and enhanced surgical tools, thesenew diagnostic techniques now make it pos-sible for an implant surgeon to placeimplants precisely where they are needed inorder to produce functionally and cosmeti-cally excellent restorations with outstandingpredictability.

These new technologies promise todeliver greater ease of implant placement,shorter treatment protocols, and less inva-

sive surgery. We anticipate that these inno-vations will make implant therapy possiblefor increasing numbers of your patients.Dental implants have truly become theFIRST choice for the replacement of manymissing teeth and the current Standard ofCare from a medico-legal standpoint.

Figure 7. Osteotomes were utilized totap up the floor of the sinus and abone graft and implant were placedsimultaneously.

Figure 8. Five months followingimplant placement, the final restoration was placed.

Figure 6. Radiographs revealed 4mmof alveolar bone below the floor of thesinus.

Examination Protocols

Single Tooth Implant1. Clinical Examination2. Periapical Radiograph3. Bone Sounding4. Panoramic Radiograph as Indicated5. Occasionally, Tomograms and/or CT Scans

Multiple Tooth Implants, Partially Dentate1. Clinical Examination 2. Periapical Radiograph3. Panoramic Radiograph 4. Bone Sounding5. Tomograms and/or CT Scans as Indicated6. Articulated Models with Diagnostic Waxup

Edentulous Mandible or Maxilla withIntact Residual Ridge1. Clinical Examination2. Periapical Films as Indicated3. Panoramic Radiograph 4. Bone Sounding5. Tomograms and/or CT Scans6. Articulated Models with Diagnostic Waxup7. Stereolithographic Models with Implant Drill

Guides

Highly Resorbed, Complex Sites; MultipleImplant Placements; Compromised BoneQuality, and Combinations of All Three1. Clinical Examination2. Periapical Films as Indicated3. Panoramic Radiograph4. Tomograms and/or CT Scans5. Stereolithographic Models with Implant Drill

Guides6. Articulated Models with Diagnostic Waxup7. MRI as Indicated

Dr. Jaime Lozada, a prosthodontistand Director of the ImplantDepartment at Loma Linda

Dental School, and his residents recentlyreviewed 50 years of literature on thesuccess, complications and failure ratesof the most routinely recommendedtooth restorations.

His findings are paralleled in anotherexcellent literature review on this topicby Goodacre published in the Journal ofProsthetic Dentistry in 1999.

Conventional Single Crowns (8 studies)• The failure and complication rate in 1- 4

years was 16%.• The failure and complication rate after 5

years dropped to 7% for a total failurerate of as high as 23%.

Three-Unit Fixed Bridge (15 studies)• The failure rate at 10 years was 15%. • After 15 years, the failure rate rose to

16% - 31% for a total failure rate of as high as 46%

• At 10 years, 5% of all abutment teethhad to be extracted.

All Ceramic Crowns (22 studies)• The failure and complication rate at

1- 4 years was 5%.• The failure and complication rate after

5 years rose 13% for a total failure rateof 18%.

Resin Bonded Prostheses (48 studies)• The failure and complication rate at

1-4 years was 25%.• The failure and complication rate after

5 years rose to 28% for a total failurerate of 53%.

Post and Cores (12 studies)• The failure and complication rate at

1- 4 years was 14%. • The failure and complication rate after

5 years dropped only to 13% for a totalfailure rate of 27%.

Endodontic Treatment: (3 studies)• A study by Bennett published in the

Journal of Endodontics, May, 2002showed a 91% initial success rate forendodontic therapy delivered in a schoolenvironment, but only 84% long-termsuccess rate in private practice.

• A presentation by Gulabivala to the IrishDental Association provided a meta-analysis of 67 studies published inEngland, Ireland and the US, whichshowed that the failure rate of endodontictreatment averaged 16-22%.

Surgical Endodontics• A study by Hepworth in the Journal of

the Canadian Dental Association, 1997,showed a failure rate of 41%. However,the report further indicated that there wasan uncertain healing rate of another 22%.

Based on such data defining an unex-pectedly high level of complications andfailures for many routine dental procedures,Dr. Lozada’s clear message is that cliniciansMUST critically evaluate the true long-termvalue of ANY TOOTH before suggesting apatient submit to multiple, conventionaldental procedures.

In many clinical situations, Dr.Lozada believes that a well-planned,well-executed and well-restored dentalimplant offers patients a more pre-dictable, more efficient and a longer last-ing solution to tooth replacement. Theaverage success rate of implants is morethan 90 percent.

Prosthodontic treatment planning haschanged, he says, because it is no longerappropriate to consider high-risk proce-dures when a more predictable alternativesuch as an implant is available. Higher riskendondontic or periodontal procedures tosave teeth for prosthodontic abutments areof questionable value because of the pre-dictable alternative of dental implants.

He acknowledges that implants placedin grafted bone are somewhat less pre-

dictable than those placed in edentuloussites where adequate healing has resulted ingood quality bone; and, that implantsplaced in some maxillary anterior areas, inpatients who were smokers, and very shortimplants were subjected to higher compli-cation/failure rates when compared toimplants in general. Notwithstanding thesespecial situations, he says, implants stillappear to be the restoration of first choicefor a great majority of tooth replacements.

Dr. Lozada’s final recommendation is:do not extract teeth (especially in the maxil-lary anterior region) before discussing pos-sible implant-supported restorations withthe surgical team member. Without antici-pating the requisite regenerative proce-dures, the soft tissue shrinkage and boneresorption following extraction make high-ly esthetic and functional implant restora-tions substantially more difficult.

We periodontists have many non-surgi-cal and surgical techniques to save teeth.We certainly acknowledge that healthy nat-ural teeth are our best “implants.” On theother hand, there has been a clear paradigmshift in our thinking regarding teeth whichrequire multiple dental procedures.

The question of whether to “save thetooth” or “save the bone” must still beanswered by each individual clinician.Considering the increased evidence of lessthan ideal long-term outcomes for manyprocedures, the dental implant has emergedas a particularly appealing alternative.

When faced with the decision-makingprocess inherent in delivering optimum lev-els of dental care, we encourage you to callupon us to assist in the decision-makingprocess BEFORE presenting comprehen-sive treatment plans to your patients, espe-cially when multiple “tooth related” proce-dures are anticipated.

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Success, Complications and Failure Ratesof the Most Common Tooth Restorations

I. Stephen Brown, D.D.S. 220 South 16th Street, Suite 300, Philadelphia, PA 19102 (215) 735-3660