Read an Excerpt
A Patient's Guide to Dental Implants
By Thomas Balshi, William Becker, Edmond Bedrossian, Peter Whörle, Bob Hogenmiller
Addicus Books, Inc.Copyright © 2003 Thomas Balshi, D.D.S., William Becker, D.D.S.,
All rights reserved.
Why We Lose Teeth
A smile can speak volumes. It is part of a universal language. And probably nothing affects our smiles as much as the appearance of our teeth. We Americans spend millions of dollars a year on our teeth, all in effort to maintain or improve our appearance. We buy toothpastes with whitening agents. We buy gels "guaranteed" to brighten our smiles. In addition to these cosmetic efforts, we schedule appointments for cleanings, fillings, crowns, and root canal treatment — all with the hope of preserving our "pearly whites."
Despite all the efforts, many Americans are missing teeth and are in need of tooth replacement. According to a report on oral health from the Surgeon General, by age seventeen, more than 7 percent of the population is missing at least one permanent tooth. By age fifty, the average American is missing twelve teeth. One-third of those over sixty-five are missing all their teeth. With increasing interest, the aging population is examining options for replacing missing teeth.
Good Oral Health
The better our oral health, the less likely we are to lose teeth. What constitutes good oral health? An individual with good oral health has gums that fit snugly around the teeth. The gums are light pink and do not bleed when brushed or probed. The teeth fit together in an orderly fashion and are free of decay. The tooth's enamel is smooth and white.
A tooth has two main structures — the clinical crown and the root structure. The clinical crown is the outer, white portion, which we refer to as a "tooth." The pulp, which contains blood vessels, nerves, and arteries, is located on the inside of the tooth and extends into the root. The root structure extends into the jawbone, anchoring the tooth. The health of the root determines the long-term survival of the entire tooth. The root is like the foundation of a house — the stronger the foundation, the longer the house will last.
What Happens When Teeth Are Lost?
Aside from the cosmetics of having a missing tooth, even a small gap in your upper or lower set of teeth can create dental problems. When space is created by a missing tooth or several missing teeth, it may put stress on the remaining teeth, causing them to shift. This shifting may result in teeth that tilt and become loose. If you lose all your teeth, the gums begin to recede and the jawbone shrinks. As a result, facial tissue loses support and begins to "cave in."
Reasons for Tooth Loss
Tooth decay is, in large part, a result of not brushing and flossing our teeth adequately. When we do not properly care for our teeth, plaque, a sticky substance loaded with bacteria, clings to our teeth. This plaque typically forms after we have eaten sugars or starchy foods — the bacteria thrive on these foods. Accumulated plaque secretes an acid that begins to "melt away" the minerals in the tooth structure. The result is what we commonly call cavities; your dentist probably refers to them as caries.
How long does it take before the bacterial acid starts eating away at your tooth? It varies with each person; however, the acid may begin eroding the tooth's surface as soon as seventeen hours after the plaque has been allowed to collect.
Interestingly, we don't totally outgrow the tendency for tooth decay. In adults, decay often occurs around the edges of fillings or around the root structure of the tooth. If your gums recede, part of the root may be exposed. The roots are coated with cementum, a substance softer than enamel, making them susceptible to decay. According to the American Dental Association, the majority of people over fifty have some tooth-root decay.
Commonly called "gum disease," periodontal disease is an infection of the tissues and ligaments that hold the teeth in place. These tissues are like "shock absorbers," and they stimulate bone to form next to our teeth. But the formation of bacteria and infection causes the ligaments to begin dissolving. Spaces or "pockets" form between the tooth and the gums. As bone loss occurs around the tooth, the tooth becomes loose.
Advanced periodontal disease, or periodontitis, is a leading cause of tooth loss among adults. Dental health professionals diagnose periodontal disease initially by examination. They'll see gums that are red and puffy and bleed easily. They confirm the diagnosis by "probing for pockets" around the gumline. A calibrated probe, similar to a very small millimeter ruler, is used to measure the depth of periodontal pockets — spaces between the gums, teeth, and bone. The pockets will have developed if the bone is dissolving. X-rays are also helpful in detecting the presence of periodontal disease.
Stages of Periodontal Disease
Also known as gingivitis, Stage I periodontal disease is superficial inflammation of the gums, in which the gums begin to sag or pull away from the teeth. It is usually reversed with professional cleanings, followed by good hygiene — frequent brushing and flossing.
This stage of the disease is marked by greater inflammation, swelling, and gums that bleed when touched. Pocket depths around the gums are three to five millimeters.
A more advanced form of periodontal disease, Stage III is characterized by pocket depths of five to six millimeters. Usually more swelling is apparent, often with pus coming from the pockets, and some teeth begin to loosen in the sockets.
Also called "advanced periodontitis," this form of the disease involves extensive bone loss and many teeth are loose in the sockets. There is no hope for saving these teeth. They may soon fall out or will require extraction. Abscesses are frequently present.
Periodontal disease affects three out of four adults over the age of thirty-five. Although poor hygiene is a major cause of periodontal disease, other factors such as diabetes and smoking increase one's risk. For individuals whose diabetes is not controlled, circulation may be poor as a result of thickened blood vessels; consequently, cells are not nourished and do not carry away waste products efficiently. This may weaken the resistance of gum and bone tissue to infection. Smokers are five times more likely to develop gum disease. Why? Smokers have a decreased response to infection and have impaired circulation. If you are a smoker, are age forty-five or older, and have diabetes, you are twenty times more likely to develop periodontal disease.
Accidents or Trauma
Car and sporting accidents are the two major causes of broken facial bones in the United States. Understandably, many individuals lose teeth in such accidents as well. Considering all causes of accidental tooth loss, some two million teeth are lost to trauma annually. Losing even a single tooth creates more problems in the mouth than one may realize. Think of it as a "domino effect." With a gap in the teeth, the remaining teeth start shifting, pushing against other teeth. This shifting allows bacteria to accumulate more easily between the teeth, and the biting force is no longer aligned correctly. This pressure may cause bone loss, resulting in the teeth becoming loose.
In some cases a lost tooth can be reinserted; however, the tooth often becomes discolored, requires a root canal treatment, or is destroyed when the bone absorbs the root.
Congenital anomalies are a category of health conditions present at birth in which deviation occurs from normal growth, development, and function. The anomaly may have developed in the fetus during pregnancy or may be hereditary.
Several hereditary diseases may result in a person being born with tiny permanent teeth or no permanent teeth at all. This condition is known as congenital anodontia, a term referring to the complete or the partial lack of a normal number of teeth. This condition affects about 7 percent of the population. The upper lateral incisors, those next to the "front" teeth, are the most commonly absent teeth, although the lower incisors and bicuspids are also often missing.
Ectodermal dysplasia is another such congenital anomaly. It is characterized by missing teeth or by teeth that are cone- or peg-shaped. The teeth typically have defective enamel, which increases the likelihood for decay and further tooth loss. This syndrome affects males more than females and is hereditary, passed on by the mother.CHAPTER 2
Dental Implants: How They Work
For thousands of years, mankind has tried to replace missing teeth. The Etruscans are reported to have made false teeth out of ivory as early as 700 B.C. History tells us of man's ongoing efforts to create false teeth, ranging from those made with human teeth in the 1700s to the first porcelain false teeth, invented in Italy in 1837.
Moreover, archeological records show that some civilizations tried to create a crude dental implant. Egyptians and South Americans tried pounding pieces of sea shells and hand-shaped ivory into the gumline. Centuries later, in the 1800s, when implants made of human teeth failed, inventors tried gold and platinum implants. The quantum leap in oral implantology was achieved in Sweden in the early 1950s.
History of Modern Dental Implants
In 1952, in a modestly appointed laboratory in the university town of Lund, Sweden, Professor Per-Ingvar Brånemark, M.D. made a discovery by accident. A physician and researcher interested in wound healing, Dr. Brånemark was using living rabbits to study bone biology. He inserted tiny metal tubes into the rabbits' bones so that he could place a microscope to study bone tissue. The tubes were made of titanium, a light, strong, non-corrosive metal.
After several months, Brånemark attempted to remove the titanium sleeves from the rabbits' bones. Brånemark was surprised to discover that he was unable to extract them. The titanium had formed an irreversible bond with the living bone.
His curiosity aroused, Dr. Brånemark subsequently demonstrated that, under carefully controlled conditions, bone could be integrated with titanium with a very high degree of predictability. The titanium did not appear to cause inflammation in the surrounding soft tissue, nor was it rejected by the living bone. Brånemark named the process of bone bonding to titanium osseointegration. Before marketing his implants he spent ten years testing them on animals and fifteen years testing them on a group of Swedish patients who had no teeth.
In 1965 the first practical application of osseointegration in dentistry was used. A man who had lost all his teeth received the first titanium dental implants. However, it was 1982 before the Food and Drug Administration gave approval for the use of titanium dental implants in the United States.
What Are Dental Implants?
Dental implants are metal posts inserted into the jawbone and serve as replacement roots for missing teeth. The replacement teeth that are later attached to the implants, look, feel, and function like natural teeth.
Implants are made of medically pure titanium, the same metal also used in the manufacture of orthopedic appliances such as hips, knees, wrists, and elbows. Thanks to the process of osseointegration, the jawbone fuses to the titanium implants, creating anchors for new, prosthetic teeth.
Dental implant-supported teeth consist of three basic components:
Implant: A titanium post or "fixture," inserted in the jawbone, which functions as an artificial root. It is often shaped like a screw.
Abutment: An extension to the implant, this cap-like device screws onto the implant and holds the artificial tooth. The abutment appears just above the gumline.
Crown: Also referred to as the "tooth."
The average titanium implant measures one-half to three-quarters of an inch and is gently screwed or pressed into the jawbone, where it becomes the foundation for the new, prosthetic teeth. Once new bone grows around them, implants become permanent. The titanium fixtures are immovable. More than three decades of research in Sweden and the United States has recognized titanium for its biological compatibility with the human body. Studies show that the earliest patients treated with titanium osseointegrated implants continue to have good dental function.
Today, many types of implants are available for various needs of patients. There are implants for soft bone, implants that bond to bone more quickly, those that work well in very dense bone, and those for varying bone widths and heights. Implant shapes and surfaces are designed to bond quickly and predictably with the surrounding bone.
Also made of titanium, the abutment is a cap-like structure that is about one-third the size of the implant. The abutment is screwed into the internal thread of implant and may be positioned slightly above or even below the gumline. It provides a base on which the crown will be placed. You might think of the abutment as the "shaved down" natural tooth on which dentists cement traditional crowns.
The crown, or prosthetic tooth, is also commonly referred to as the restoration. Crowns usually have a substructure or core that is made of metal, often gold because of its strength. In other cases, the core may be made of ceramic or zirconium, a hard, grayish -white metal that resists corrosion. The core structure is typically fused with an outer coating of porcelain, the dental material that most closely resembles the appearance of natural teeth. Crowns are custom-designed and shaded so that they look like natural teeth.
Understanding Dental Terminology
As you begin to investigate dental implants, you may come across terms that are confusing. So, let's take a moment to clarify the other common terms you will likely hear, such as "restorations," "prosthesis," "bridges," and "dentures."
Often these terms can be used interchangeably, which creates some of the confusion for those new to the topic. Perhaps this short glossary will help you navigate more smoothly.
Restoration: This term simply refers to your teeth being restored. The words restoration and crowns are often used interchangeably. When it's time to receive your permanent crowns, you will be in the restoration phase of the process.
Prosthesis: This term refers to your new, "man-made" teeth. They are artificial replacement teeth. "Prosthesis" could refer to a single tooth, a bridge, or a denture — all of which can be used with implants.
Bridge: A bridge refers to several teeth, bonded together, used to fill the space where natural teeth are missing. As you're discovering, modified bridges are used with implants. A bridge is commonly referred to as a prosthesis.
Denture: Modified dentures, also used with implants, may be referred to as a prosthesis or your prosthetic teeth. Implant -supported dentures may be removable or may be securely fastened to the implants.
Who Performs Dental Implant Surgery?
Several types of dental professionals perform dental implant surgery. Today, oral surgeons, periodontists, and prosthodontists have the most experience in implant placement.
In addition, many dentists who have received training in implant surgery provide this service. More information on the various types of dental professionals is covered in Chapter 3.
The Standard Procedure
The standard procedure for dental implant treatment takes place over a three- to six-month period. Why does it take this long? Once the implants are inserted into the jawbone, it takes several months for the bone to fuse, or osseointegrate with the titanium implants. Here's an overview of the entire three-stage process.
In the first stage of treatment, if diseased or damaged teeth are present, they are carefully extracted with attention paid to preserving the adjacent bone. Generally, after extraction, the titanium implants are surgically inserted into the jawbone. The gums are sutured closed and the bone is allowed to fuse with the implants. So the patient won't be totally without teeth during the months the bone is attaching to the implants, he or she is usually given a temporary prosthesis to wear. The prosthesis may be a removable partial denture or a bridge that is bonded to adjacent natural teeth.
In the second stage, three to six months later, the patient returns to the dental specialist. The patient's gums are anesthetized and a small incision is made in the gum to uncover the implants. The abutments are attached to the implants. Temporary crowns are then placed on the abutments. Now the implants are capable of withstanding the pressure applied during chewing.
Several weeks later, the dental specialist will take impressions, or imprints, of the inside of the patient's mouth, including the implant abutments, in preparation for making the permanent crowns. The impressions are sent to the dental laboratory, where a technician will make a model or cast; these casts are used to make the final implant crowns. Once the crowns are made, the patient will return to the dental office to try the crowns for fit. The dental professional will evaluate the accuracy of the fit with an x-ray. Once fitted with precision, the crowns will be affixed to the top of the implants.
Excerpted from A Patient's Guide to Dental Implants by Thomas Balshi, William Becker, Edmond Bedrossian, Peter Whörle, Bob Hogenmiller. Copyright © 2003 Thomas Balshi, D.D.S., William Becker, D.D.S.,. Excerpted by permission of Addicus Books, Inc..
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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