Evaluating a patient's jawbones for implant placement.

The long-term success of a dental implant will be highly dependent upon the bone in which it is placed.

Because of this, the treating dentist will need to examine the patient's jawbones so to determine that both the quantity and quality of the bone in the region of the surgical site is adequate.

They'll also need to insure that the location for the implant is distant enough from neighboring anatomical structures, and is pathology free.

The dentist's examination will need to be twofold.

  • One aspect will involve routine techniques: Visualization, palpation (touching, feeling), and measuring the jawbones.
  • The other will involve the use of dental x-rays.
A panoramic dental x-ray.

What type of x-rays will be needed?

In many cases, a combination of a panoramic film (a single x-ray that shows both of the patient's jaw bones and all of their teeth, see picture) and a few periapical radiographs (the small individual x-rays most often taken in dental offices) will be satisfactory for a patient's examination.

In other cases, however, the anatomy of the patient's mouth may such that the dentist feels that they require the type of detailed visualization that only the 3-D imaging of a CT scan ("computed tomography", CAT scan) can provide.

Factors the dentist must evaluate -

1) The patient's jawbone must offer an adequate quantity and quality of bone.

A dental implant requires an adequate amount of bone.

The dentist must determine that there is an adequate quantity of bone in the region of the planned tooth implant and that this bone is of sufficient quality.

  • Making this determination will involve evaluating the shape of the bone (both width and height).
  • It will also involve evaluating the density of the bone. The dentist can get a hint of this from the x-rays and CT scans that have been taken.

2) Reasons why a patient's jaws may be unsuitable for implants.

There can be situations where the treating dentist will find that the bone in the region of the planned implant is not adequate.

a) Naturally occurring deficiencies.

The bone problem can be naturally occurring, such as that bone resorption (bone loss) that takes place in those regions where teeth have been extracted. This type of defect is most common in those cases where multiple teeth were extracted many years previously.

The magnitude of post-tooth extraction bone loss can be as much as 40 to 60 percent within the first three years after teeth have been removed. Beyond that point, the rate of loss typically subsides substantially.

The cause of this resorption is typically attributed to disuse atrophy, decreased blood supply, localized inflammation and/or unfavorable pressure from a dental appliance (denture or partial denture).

b) Bone damage due to disease.

In other cases, a patient's bone deficiency may be attributed to a dental condition, such as bone loss due to advanced periodontal disease (gum disease).

With this condition, significant amounts of bone can be lost from around the person's teeth, to the point where if they need to be extracted, there may no longer be adequate bone into which to place a tooth implants.

c) Bone loss due to other factors.

In some cases, a bone deficiency may be associated with a previous surgical procedure such as a difficult tooth extraction or the removal of a cyst or tumor.

A dental implant cannot be placed in the area of the maxillary sinus.

d) Bone pathology.

The dentist must search for evidence of pathology within the jawbone (such as tumors, cysts or other pathologic conditions).

Additionally, impacted teeth and the presence of tooth root fragments (remnants of past extractions) need to be identified and removed as the dentist feels is indicated.

A dental implant cannot be placed in the area of the mandibular nerve.

e) Anatomical considerations.

The location of anatomical structures, such as sinuses, nerves, blood vessels and the roots of adjacent teeth must be identified.

This is important because tooth implants must be positioned in a fashion where they are suitably distant from these objects.

Bone grafting may be necessary before an implant can be placed.

Since the success of a dental implant will be greatly dependent upon the bone in which it's placed, the treating dentist may feel that it's necessary for them to perform a bone-grafting procedure first, so to replace missing bone structure or enhance existing bone.

This is typically a separate procedure that must be performed (and allowed to heal) prior to placing the implant.

We discuss one such grafting procedure called a Sinus Lift. It's frequently performed prior to placing implants that replace upper back teeth.

Evaluating the patient's soft tissues.

A portion of the dentist's clinical examination of a prospective dental implant patient must also involve the evaluation of the soft tissues of their mouth. Of course, the dentist must find that these tissues are free of pathology and appear to be health.

They must also evaluate both the quantity and type of the gum tissue in the immediate area where the tooth implant will be placed. The right type of gum tissue (attached gingiva) must surround the implant to insure its long-term success.

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