Many patients can be restored by routine removable prostheses such as complete, over- or removable partial dentures. However, there are those patients who cannot tolerate a removable prosthesis by nature of their adaptive response. Zarb refers to this response as that which occurs individually to each patient and has to do with their skilled performance.
Some patients fail to respond to treatment and come in again and again complaining about their prostheses even though there may be no obvious sign of injury or disease and their prosthesis may be deemed acceptable. For these patients, an implant offers some hope. Others feel that why not offer implants to everyone since they are an acceptable method of treatment, have an excellent success rate, and have many advantages over removable alternatives.
Each clinician must decide with their patient the best treatment plan. Implants are not for everyone but they should be offered to everyone. Implants have helped many patients unable to adapt to conventional prostheses.
Dr. Branemark did his clinical trials with patients who were totally edentulous in both the upper and lower jaws. The main indications for implants are in
- The totally edentulous jaw – (Figure
Figure 1: The totally edentulous jaw
- The partially edentulous ridge
- Single tooth replacements
- Extraoral maxillo-facial prostheses such as ear, nasal and orbital (eye) prostheses; hands, arms, legs
- Patients who might have unrealistic denture expectations
- Patients who have a psychological inability to wear a removable prostheses
- Patients who are dental phobics
- Patients who have unfavorable morphological conditions for complete or removable partial dentures, e.g., poor ridge
- Patients who have poor oral muscular coordination
- Patients who have parafunctional habits that dislodge complete dentures
- Patients who have a sensitive gag reflex
- Patients who have a low tolerance of mucosal tissues, i.e., their tissues irritate easily
- Patients who have an unfavorable number and position of
their remaining teeth. (Figure 2)
Figure 2: Patient with Unfavorable Number and Position of Teeth
- Patients who have congenital deformities that result in missing teeth, e.g., ectodermal dysplasia
The main criteria for an implant is the proper amount of height and width of bone which, in general, is 10 mm height and 6 mm width (minimum.)
When considering implants for an edentulous patient, it is necessary to thoroughly review the patient’s previous denture experience (if any), the patient’s expectations of a denture, perform a complete oral examination of the denture bearing surfaces as well as an evaluation of the patient’s existing prostheses. Implants should be treatment planned for all edentulous patients, even though the patient may opt not to select them.
Many patients with a complete denture are dissatisfied with their prostheses and complain of poor fit, inability to chew and discomfort. An objective evaluation of the dentures themselves may show an excellent result. Each patient adapts to complete dentures differently. This is called (after George Zarb) the “adaptive response”. The patient’s ridges may be excellent and the dentures objectively retentive and yet the patient may not have been able to learn the techniques used to stabilize the dentures or may just be someone who would do better with the advantage in retention that an implant overdenture offers.
Even in patients who are doing well with complete dentures, the placement of 2 lower implants to stabilize an implant overdenture may also help preserve bone.
Edentulous patients could also have 6-8 implants placed in an arch and then have a fixed implant prosthesis. In our school, this is done only in the postgraduate prosthodontics or the implant center clinic.
Dental implants are absolutely contraindicated in:
- Alcohol or drug abusers
- Patients with psychological disorders such as:
- emotional instability
- psychotic syndrome
- severe character disorder
- dysmorphophobia (fear of looking aberrant or weird)
- cerebral lesion syndromes such as senile dementia or Alzheimer’s disease
- Pregnant patients
- Patients with debilitating or uncontrolled disease such as uncontrolled diabetes
- Patients with poor motivation
- Patients unable to manage oral hygiene
- Patients desiring unattainable prosthodontic reconstruction
- Fibrodysplasia patients
Other relative contraindications seem to be:
- Radiation therapy
Patients who have irradiation to the head and neck areas can be successfully treated with implants. The surgical and postoperative healing phase must be carefully done at facilities that have hyperbaric oxygen chambers. The success rates range from 50% - 100% depending upon the area of the head where the implants are placed.
Smokers have lower success rates. Implants can be placed in these patients but more implants may be necessary. These patients should be warned that some or all of their implants may fail. They should be strongly urged to quit smoking.
Bruxers or people who grind their teeth will damage all types of dental prostheses. As a result implants, implant prostheses and all dental prostheses will not last as long in these patients. It is probably a good idea to place more implants in these patients and warn them that some or all of these implants may fail. Their implant prostheses will be subject to wear and tear, and will constantly need maintenance and repair. The patient will have to pay for all of this. In addition, a mouth-guard should be made for these patients, both before, during and after treatment to protect their prostheses.
Most people feel that a patient who can have routine oral surgery, such as an extraction, is eligible for an implant. Dental implants have been placed successfully in:
- Diabetics (as long as they are controlled diabetics)
- Kidney diseased patients
- Patients with cardiovascular disease
- Patients with blood dyscrasias
- Patients on corticosteroid therapy
As long as the disease element is controlled, there is no contraindication. You must work closely with the patient’s physician before and during the surgical phase.
Age is not a contraindication to dental implants. Osteoporosis has also not been proven to be a contraindication, although it may be an additional risk factor. Patients must be cooperative, and have the manual dexterity to perform oral hygiene procedures.
One big contraindication to implants is the dentist’s own lack of knowledge/training. The dentist should have taken courses to learn about implants. Surgical courses should include hands-on-training.
4. Initial Evaluation
Good oral hygiene should be present and the oral tissues should be healthy. Some feel that an edentulous patient should have worn a conventional denture for at least one year, but others see no need for this precondition.
The existing dental prosthesis should be carefully evaluated in light of the patient's chief complaint to ascertain if routine dentistry might in fact solve the complaint, such as a new, better fitting removable prosthesis. However, many patients today will express a sincere desire to have a dental implant even though they are told that a better removable prosthesis will help. Many patients just simply want something fixed (not removable) in their mouth or they recognize their own inability to tolerate and adapt to a removable prosthesis.
The initial visit should include:
- A thorough oral and head and neck examination
- An examination of the existing prosthesis
- A radiographic analysis (panoramic radiograph and FMX)
- A psychological evaluation
For the psychological evaluation some clinicians do an on-the-spot assessment of the patient's mental state; others have the patient fill out a short psychological survey. If either of these techniques lead to a question about the patient's mental capacity to handle an implant, they can be referred to a psychiatrist or psychologist for a more thorough evaluation.
The patient should be fully informed of the implant procedure. For this, a written pamphlet outlining the proposed treatment is helpful. These are available from the various implant manufacturers, some even specially designed for the patient to take home with them. The patient should be aware of all the risks and benefits and should be informed appropriately. Prior to their surgical appointment, they should be asked to sign an informed consent, which includes restorative and surgical consent.
Tentative (not final) fees should also be discussed with the patient at the initial visit. Many patients do not realize how expensive implant therapy is, and it may help them to begin planning. The biggest reasons patients opt NOT to have implants are:
- Fear of surgery
An informed consent must be signed by the patient.
4.1. Oral Examination
A thorough oral examination should be done as usual. The area of potential implant placement should be evaluated for height and width of ridge. Palpation – squeezing the width of the ridge – may help determine the thickness of soft tissue vs. bone. (Figure 3)
|Figure 3: Palpation of Implant Site|
Patients can be given local anesthesia and then metal calipers or needles may be used to gently penetrate the soft tissue to test the bony width. Facial concavities should be noted as they are potential sites for guided tissue (bone) regeneration (GTR).
The height of the patient’s lip-line should be noted. The interridge distance should be checked with the patient in occlusion.
4.2. Existing Prosthesis
The patient’s existing complete denture should be checked for its contribution to the lip support. If it contributes greatly, a removable implant prosthesis may be possible (it still has a flange) where as a fixed prostheses would be contraindicated (no flange).
4.3. Radiographic Analysis
The initial visit should include a periapical radiograph of the potential implant site. Before the final treatment plan is done, a full mouth series of radiographs and a panoramic radiograph is necessary. The dentist must analyze all dental needs and not just the implant area.
The radiographs can give further information on the height of bone available, any periapical pathology, and interfering anatomical structures such as the mandibular nerve, mental foramen, maxillary sinus, and adjacent tooth roots.
If more information is needed, CT (computed tomography) scans of the jaw can be done. This is an added expense to the patient and should only be done when indicated. The cost may be as high as $500.00 per arch. Neither dental nor medical insurance will cover this fee. The dentist should decide on the need for a CT scan after consulting with their surgeon.
4.4. Initial Surgical Consultation
A brief visit may be scheduled to meet the surgeon. The final surgical consultation will occur after the diagnostic mounting.
4.5. Advanced Radiographic Techniques in Implant Dentistry: CT Scans
There are CT software programs designed for assessment of the type, amount, and anatomic configuration of the maxillary and mandibular bone considered for implant placement. (Figure 4)
|Figure 4: CT-Scan|
Dental CAP (clinical application package) is an independent computer workstation with a software package. It is the product of ISG Technologies, Ontario, Canada. Dental CAP allows for precise preoperative visualization of dental anatomy. Unlike the standard panorex and intraoral films, Dental CAP provides visualization of the mandible and maxilla in three planes axial, oblique sagittal (cross sectional) and panorex. Working with transaxial slice data from virtually any CT scanner, ISG's Dental CAP offers oral surgeons, periodontists and dentists the optimal presentation of 2D and 3D anatomical information for:
- Localization of the inferior alveolar nerve.
- Localization of the maxillary sinus.
- Measurement of bone density and volume for implant anchorage.
- Assessment of any bony abnormality or pathology.
The examination takes about 20 minutes from start to finish. There is about a five minute set up time in which the patient is allowed a little motion, then about 10 minutes of continuous scan time in which the patient is instructed not to move at all. We have gone to great effort to make this exam as comfortable and quick as possible.
The Dental CAP stacks the CT images (this is possible because the images are made of a matrix of data points), and a line is drawn around the curve of the mandible or maxilla. The computer then draws prospective lines to represent sagittal oblique images every 2 mm around the curve. It assigns five lines around the first curve that was drawn to represent the panorex images usually at 1.5 (or 1.0) mm intervals.
Types of images:
- Oblique Cross Sections Reformats
- Comprehensive set of 3D images (multiplanar reformat)
This program plays three important roles in patient management:
- It identifies patients preoperatively who have insufficient bone for implantation, obviating the need to contend with this sometimes unanticipated condition during surgery. Alternative treatment plans can now be made in advance.
- It identifies the optimum site for implantation by locating the exact position of the inferior alveolar canal, maxillary sinuses and incisive canal and the area of maximum bone height, width and density.
- It identifies implant sites in patients who, based on standard radiographs, were once considered to be inoperable because of insufficient bone.
4.6. Sequence of Treatment
On a case by case basis, it can be considered that implants may be surgically placed early in the patient’s treatment plan, but only when the following minimum treatment has been accomplished:
- Phase I periodontal care
- Caries control
- Endodontics completed for all teeth with:
- periapical radiolucencies
- Soft tissue health achieved in edentulous areas (tissue conditioning treatment performed)
- Emergency extraction of hopeless teeth
That is, active disease is under control.
4.7. Diagnostic Mounting
All advanced or complicated prosthetic treatment plans should occur with a diagnostic mounting. All implant treatment plans need the benefit of a diagnostic mounting. The purposes of a diagnostic mounting are multiple:
- Anatomic considerations for prosthetic design
- Diagnostic wax-up for try-in of teeth.
- Surgical template fabrication
- Fabrication of Interim prostheses (transitional crowns, fixed partial dentures, removable partial dentures and transitional/Interim complete dentures)
The purposes of a wax try-in are:
- Verification of all records
- Esthetics-patient approval of tooth position/ shade
- Final determination of implant position/ feasibility
- The purpose of a surgical template is to guide the surgeon to the ideal implant position.
Types of surgical templates include:
- Processed acrylic resin
- Autopolymerized acrylic resin
- Both of these with or without radiopaque markers
Note: Always try in the surgical template before the surgical appointment
4.7.1. Diagnostic Mounting Procedures – General Considerations
- Preliminary impressions are made in irreversible hydrocolloid of the dentulous arch(s) or the edentulous arch(s).
- Record bases are made when there are inadequate teeth to attain accurate records: partially edentulous ridges with distal extensions or completely edentulous ridges.
- Records include determination of vertical dimension of occlusion in edentulous cases; facebow transfer and centric relation record or intercuspation position in all cases.
4.7.2. Edentulous Considerations for Diagnostic Mounting
It should not be assumed that the patient’s existing complete denture(s) is at the correct vertical and esthetic position. Record bases and occlusion rims should be made on the preliminary casts. These are then used with the patient to determine:
- Correct vertical dimension of occlusion
- Planes of occlusion
- Lip support
Then a facebow transfer is used to mount the upper preliminary cast. This is important since one can then make changes in vertical dimension on the articulator. A centric relation record is used to mount the lower cast.
Once mounted, the rims can be removed so the ridges can be studied.
4.7.3. Partially Edentulous Considerations for Diagnostic Mounting
If there are enough teeth remaining anterior and posterior to the edentulous site considered for implant placement, a record base and occlusion rim may not be necessary. If the area of edentulism is a distal extension area, a record base is necessary. (Figure 5)
|Figure 5: This patient needs a record base.|
The upper preliminary cast should be mounted with a facebow. If enough teeth are present, the lower preliminary cast can be hand articulated with the upper. If not, a record is taken in the maximum intercuspation position or centric relation and is used to mount the lower cast.
5. Facebow Transfer
- Relate center of condyles to maxillary occlusal plane
- Facebow apparatus
- Sticky wax
- Pink wax or compound
- Alcohol torch or compound heating water bath
- Bunsen burner
- Manufacturer’s instructions about facebow transfer technique. (The following is a general outline of the technique. The actual technique outlined by the manufacturer is what should be followed).
|Duties of Dentist and Assistant|
|Coats bite fork with sticky wax.|
|Heats baseplate wax with Bunsen burner (compound may be used instead, without the initial coat of sticky wax).|
|Places wax (compound) on facebow fork.||Hands dentist facebow.|
|Places facebow bite fork on maxillary teeth. Patient may close into wax (compound) just to stabilize bite fork on maxillary teeth. (Centric relation is not made with facebow or bite fork.)|
|Places facebow earpieces gently into external auditory meatus.||Holds bow steadily in place.|
|Aligns bite fork with attachment to facebow.||Holds bow so that it does not bind on face or in ears.|
|Aligns infraorbital pointer.||Holds bow steadily so that it does not bind on face or in ears.|
|Tightens fork into place on facebow with hex wrench or appropriate device.||Holds steadily and follows dentist’s movements so that apparatus doesn’t drop.|
|Loosens facebow apparatus in preparation for removal.||Places equipment in appropriate box.|
|Places equipment in appropriate box.|
6. Centric Relation Record with Hard Wax Wafer
- To relate mandibular occlusal surfaces to maxillary occlusal surfaces with the condyles centered in the fossae.
- Hard wax sheet (hard pink wax)
- Alcohol torch
- Hot water (135º-140ºF in water bath)
- Scalpel blade and handle (#15 or #11 scalpel blade and handle or sharp blade handle and #25 blade)
- Registration material (zinc oxide and eugenol bite registration paste)
- Mixing pad
- Cement mixing spatula
- Rubber bowl with cold water
|Duties of Dentist and Assistant|
|Places ½ sheet of hard wax in hot water, until it becomes pliable.|
|Places softened wax gently on maxillary cusp tips and incisal edges.||Hands scissors to dentists|
|Removes from mouth and trims softened wax to within 2 mm of cusp tips.||Reheats wax.|
|Rehearses patient into centric relation.||Hands softened wax to dentist.|
|Places softened wax on edges and cusp tips of maxillary teeth and guides jaw into centric relation and to first contact on softened wax.||Gently chills wax with air and water spray intraorally.|
|Removes wax wafer and trims wax to cusp tip and incisal edge indentations using scalpel.||Blows excess wax off with air syringe.|
|Re-inserts wax in mouth and checks centric relation position.||Rinses off wax wafer in cold water.|
|Dries off wax.||Mixes ZnOE paste and places very small amount on wax wafer in thin layer in area of cusp tips on both sides of wafer.|
|Places wafer on maxillary teeth and guides mandible to first centric relation contact on wax.|
|Blows trimmed ZnOE paste off using air syringe.|
7. Centric Relation Record with Temporary Registration Base and Rims
- To relate mandibular occlusal surfaces to maxillary occlusal surfaces with the condyles centered in the fossae.
- Temporary acrylic resin registration bases with wax rims made on study cast
- Alcohol torch
- #15 or #11 scalpel blade and handle or #25 sharp blade and handle
- Registration material (wax, ZnOE paste)
- Mixing pad
- ZnPO4 mixing spatula
- Denture powder
- Water bath at 135º-140ºF
|Duties of Dentist and Assistant|
|Tries in registration base (one at a time). Makes certain bases do not have occlusal prematurities (especially retromolar pads or tuberosities.)||Retracts lips.|
|Heats baseplate wax registration rim in water bath for 15 seconds.||Lays out ZnOE paste or heats small pieces of wax.|
|Inserts registration base and guides patient Into centric relation.|
|Tells patient to close as far as possible Into softened wax occlusion rim|
|Cuts back wax to just remove all registration of cusp tips.||Blow away excesswax with air syringe.|
|Flames surface of registration rim with alcohol torch.|
|Replaces base and guides patient to centric relation.|
|Repeats (if necessary) with opposing registration base.|
|Recontours opposing registration rim heights so that only slight contact occurs in centric relation.|
|Puts several V-shaped indexing notches across the rim which will not have ZnOE paste or wax added to it.|
|Rehearses centric relation position repeatedly with patient.||If ZnOE record, scores wax rim with knife to provide retention for paste. If wax record, makes half-inch wide two-layered strip.|
|Places ZnOE paste on un-notched rim or heats wax rim in water bath for five (5) seconds||Mixes ZnOE paste or lutes wax strips to unnotched rim with hot #7 spatula.|
|Places base in mouth and guides to centric relation. It may be necessary to stabilize the base (or bases) with denture powder.|
|Removes bases one at a time.||Rinses and wipes off powder in cold water if necessary.|
|Trim excess ZnOE paste or chilled wax back to cusp tip registration only.||Blows debris away with air syringe.|
8. Evaluation of Mounted Casts/Anatomic Considerations
This evaluation should include a study of the:
- Interridge distance (minimum of 6 mm per arch)
Figure 6: Consider the Interridge distance, supererupted or malposed teeth and width of edentulous space(s)
- Occlusion (Figure 7)
Figure 7: Occlusion
- Class I, II, or III
- Crossbite in anterior or posterior
- Vertical or horizontal overlap
- Supererupted or malposed teeth (Figure 6)
- Amount of hard and soft tissues to be replaced (Figure
Figure 8: Amount of tissue to be replaced
- Number and position of remaining teeth
- Width of edentulous space: 6-7 mm needed (Figure 6)
- Height of ridge crest compared to adjacent natural teeth
Figure 9: Height of ridge crest compared to adjacent teeth
- Occlusal plane
- Buccal and lingual concavities (need for ridge augmentation)
Figure 10: Buccal and lingual concavities
- Amount of bone loss in edentulous areas
Esthetic considerations – high lip line/lip support (Figure 11)
|Figure 11: Esthetic considerations: lip line/support|
9. Diagnostic Wax-up/Wax Try-in
- Denture teeth are selected of the appropriate size, shape and shade.
- Teeth are set on the edentulous and/or partially edentulous record bases and tried in the patient’s mouth for verification of occlusion, esthetics and function.
10. Edentulous Considerations for Diagnostic Try-in
An entire maxillary and mandibular anterior and posterior tooth set-up must be done as a diagnostic procedure prior to implant placement. With the patient, the vertical dimension of occlusion, lip support, esthetics, phonetics and centric relation are confirmed. Then one can plan the type of implant prosthesis (fixed or removable) and the location and number of implants necessary.
For example, after a diagnostic try-in, it was determined that the patient needed a full denture flange to support the lip for proper esthetics. A fixed implant prosthesis would be contraindicated here as it has no flange. A removable implant prostheses would be planned instead.
11. Partially Edentulous Considerations for Diagnostic Try-In
Even if only one tooth is being replaced, it should be tried in for the patient. This tooth try-in should not have a facial flange as the final result will not. The try-in allows us to confirm the position, color and shape of the planned implant crown(s).
For example: at a diagnostic try-in it was determined that the 3 upper left posterior implant crowns would have to be in crossbite because of the amount of ridge resorption present. The patient would either:
- Have to accept the crossbite
- Have a bone graft to correct the ridge position
- Have a removable prosthesis instead of an implant
12. Fabrication of Interim Prosthesis
- Extraction of remaining nonrestorable teeth often
necessitates the fabrication of an Interim prosthesis. This can include
- Interim immediate denture
- Transitional removable partial denture
- Provisional (temporary) crowns
- These can be made on the diagnostic mounting.
13. Treatment Plan
Once the diagnostic try-in is complete, it is time to finalize the treatment plan with the patient. The overall soft tissue, tooth and implant treatment plan and fee should be presented to the patient for approval.
14. Final Surgical Consultation
Now is the appropriate time for the final consultation with the surgeon. Findings from the diagnostic mounting are communicated to the surgeon as well as the overall treatment plan. Sequencing of treatment, final number of planned implants, and then fee needed for any additional surgical procedures should be decided at this time.
It is helpful if the restorative dentist with the mounted casts can be present at this visit. Often in private practice, casts are sent with a letter of referral from the restorative dentist explaining the patient’s needs/treatment plan.
- Zarb G, Bolender C, Carlsson. Boucher’s 11th Prosthodontic Treatment for Edentulous Patients. Ed. CV Mosby, 1997.
- Schwarz M, Rothman S, Rhodes M, Chafetz N. Computed Tomography: Part 1. Preoperative Assessment of the Mandible for Endosseous Implant Surgery. Int’l J Oral Maxillo Implants 2:137-141, 1987.
- Schwarz M, Rothman S, Rhodes M, Chafetz N. Computed Tomography: Part 2. Preoperative Assessment of the Maxilla for Endosseous Implant Surgery. Int’l J Oral Maxillo Implants 2:143-148, 1987.
17. Sample General Informed Consent for Treatment
We are asking you to read and sign the following. It means that you understand the recommended or alternative treatment plans that have been presented to you.
An understanding of the risks and benefits of the treatment will help you to make a decision as to treatment you wish to pursue when informed of the risks and benefits of treatment. We feel you will be happier with the final outcome.
This document’s purpose is to supplement the treatment plan explanation provided to you by the student doctors and faculty, to assure your understanding of recommended or alternative treatment plans and to document your consent to either the recommended treatment plan or one of its alternatives.
I [patient name here] have been informed by [student doctor name here] of the need to undergo dental treatment as presented to me, and the relevant information regarding my treatment has been read by me and explained to me on [date here]. I have been fully informed about the diagnosis, details, and cost of recommended treatment and alternatives. I agree to accept this recommended treatment as present diagnosis dictates at this time.
I understand that as treatment proceeds there may be a need to change the treatment plan. If this occurs, I expect to be informed before any changes are instituted.
I have discussed all of the above with my student doctor and faculty, and all of my questions have been answered. I have been informed that success of treatment depends upon my cooperation in keeping scheduled appointments, following home care instructions, including oral hygiene and dietary instructions, taking prescribed medications, and reporting to my student doctor any changes in health status.
I acknowledge that student doctors, faculty, and school have not made any warranties or guarantees concerning treatment or its long-term success.
PUBLICATION OF RECORDS: Because I have sought treatment in a dental school, I authorize that records of my case, including progress notes, x-rays, photographs, slides, or any other relevant material can be made available for third party insurance/reimbursement and/or teaching purpose; every effort will be made to prevent my identity from being revealed. I expect no compensation or other remuneration, and I specifically release and agree to hold harmless the University and all others from liability or other obligations arising from the taking or use of photographs. I further understand and intend that this release shall be binding on heirs, my executors, administrators, successors, assigns and me.
I further understand that individual reactions to treatment cannot be predicted, and that if I experience any unanticipated reactions during the following treatment, I agree to report them to my student doctor as soon as possible.
I also realize that Medicare and Medicaid may not pay for certain procedures. If I choose to have these treatments, I understand I will be responsible for payment of these services.
Following explanation, discussion and answers to my questions, I authorize my student doctor, under supervision of faculty, to perform treatment as described. I have read the informed consent explanations and alternatives to care that checked or otherwise indicated below and have initialed those areas.
|1. Local Anesthesia||5. Crown and Bridge||9. Removable Partial Dentures (RPD)|
|2. Periodontics||6. Fixed and Partial Denture||10. Complete Dentures|
|3. Operative Dentistry||7. Tooth Fracture||11. Implant Restorations|
|4. Endodontics||8. Grinding or Clenching|
There are separate informed consents for the areas of oral surgery, pediatric dentistry, cranio-mandibular disorders and implant surgery.
Patient’s Printed Name:
Student’s Printed Name:
Instructor's Printed Name: