For almost a hundred years dentistry has tried, with limited success, to find a way to replace missing teeth with artificial teeth that attach to the jawbone. Forty-five years ago, the technique was perfected, and now hundreds of thousands of patients have dental implants placed each year.
Implants are titanium alloy posts that are placed in the bone to serve as the replacement for the root portion of a missing natural tooth. The implant is biocompatible with human tissue, and in three decades of use there have been no known foreign body reactions (i.e. there are no allergies to titanium). Dental implants are made of the same medical grade titanium commonly used in hip & knee replacement prostheses, spinal fusion surgeries, cardiac pacemakers and defibrillators.
During the initial healing period following implant placement, a chemical bond is formed between the implant surface and the surrounding bone. This process is called osseointegration. The implant-bone bond is stronger than that between bone-bone.
Benefits of Dental Implants
- Replace one or more missing teeth without affecting adjacent teeth.
- Resolve joint pain or bite problems caused by teeth shifting into missing tooth space.
- Restore a patient’s confident smile.
- Restore chewing, speech, and digestion.
- Restore or enhance facial tissues.
- Support a bridge or denture, making them more secure and comfortable.
Implant Replacement for Single Teeth
While a single tooth can be replaced with a removable appliance, the looks, function, and convenience of a “permanent” replacement are far superior. In the past this could only be accomplished with a bridge, where the teeth on either side of the missing tooth are crowned, with the replacement tooth connected to the crowns.
This is an excellent restoration, but many people would prefer not to have to “prepare,” or cut down, the adjacent teeth. Today, implants have become so predictable they are often recommended in place of a bridge to replace single missing teeth.
Dental Implants Case #1
|The maxillary right and left lateral incisors are missing. There is minimal interradicular space.||The implants are positioned within the available spaces. [X-ray]
Dental Implants Case #2
|Right and left implant restorations are placed and refined with single crowns.|
|Implants were placed in the maxillary lateral positions. After 6 months of healing their connections were made.
|Photograph of the final restorations.
|A close-up of the final restoration demonstrates restoration of a natural appearance|
Dental Implants Case #3
|At times in the Posterior two implants are required to support one tooth|
|An x-ray demonstrates the need for two implants in a molar position.||Clinical photograph demonstrating 2 implant support in one molar space.
Dental Implants Case #4
|Implant inserted to replace missing right central incisor||X-ray of implant with crown in place
Dental Implants Case #5
|X-ray of single tooth implants
|Close-up of beautiful cosmetic result. It is difficult to tell which teeth were replaced with the implant/crown.|
The advantages of implants over bridges include:
- It is not necessary to drill down the adjacent natural teeth to make crowns.
- The teeth remain separate, making cleaning (flossing) easier.
- If a bridge fails, the entire bridge must be removed. Implants are stand-alone.
- Implants cannot decay the main reason for bridge failure.
Implant Replacement for Multiple Teeth
Implants can be used to support multiple teeth, or bridges. They are very useful when the natural teeth are not strong enough to support a bridge, or when there are no teeth available to which a bridge can be connected. In these cases, implants offer the only solution for a permanent restoration, and an alternative to a removable appliance.
Dental Implants Case #6
|X-ray of implants in place.||Completed implant supported bridge.|
Dental Implants Case #7
Multiple Tooth Replacement Case Example
Dental Implants Case #8
Dental Implants Case #9
Immediate Implant Placement- at the time of extraction
Studies have been done (Wagenberg 2006) which demonstrates similar success rates of implants placed at the time of extraction and delayed placement or placement in native bone.
Dental Implants Case #10
Immediate Tooth Replacement- at the time of extraction
When a tooth has to be replaced in the esthetic zone immediate tooth replacement is considered. In this case the tooth is extracted, implant replaced, connection is made and a provisional restoration is placed the same day.
Dental Implants Case #11
In order to keep all pressure off the healing implant the temporary tooth must be out of occlusion and the patient must be capable of not chewing on it.
Full Arch Replacement
For patient missing all of their teeth on one or both dental arches, implant therapy could drastically change the way they function and feel about their mouths. Different options for full arch implant rehabilitation include:
Dental Implants Case #12
Dental Implants Case #13
|Magnets are often used to stabilize a full denture.||The under surface of the denture houses the other side of the magnets.
Dental Implants Case #14
|Three implants were placed to stabilize a bar.|
|Radiograph of the implants and bar.||The clips will engage the bar stabilizing the denture.|
Dental Implants Case #15
Fixed “Hybrid” Denture
Dental Implants Case #16
Dental Implants Case #17
There are several approaches that may be used in implant placement, depending on the patient’s particular needs. Generally, an implant restoration consists of three phases: (1) placement of the implant itself, (2) following implant healing, insertion of a post or other fixture that emerges through the gum, and (3) seating the final crown or prosthesis. Below is an example of a typical treatment sequence for a common restoration, the single tooth replacement.
Stage 1: Implant surgery
The gum tissue is gently elevated from the jawbone. An osteotomy is prepared in the bone (hole for the implant) and the implant fixture is threaded into the bone. The gum tissue is sutured, covering the implant, and the implant is allowed to heal: 2-4 mo.’s in the mandible and 4-6 mo.’s in the maxilla.
Appointment 1: Examination and treatment planning
|Missing tooth to be replaced|
Appointment 2: Placement of implant
|Hole prepared to receive implant||Implant seated and gum closed|
Appointment 3 (10 – 14 days): Sutures removed
Appointment 4 (4 weeks): Site examined to assure proper healing
Appointment 5 (3 – 6 months): Implant exposed, if submerged at the insertion appointment. A connection is placed to maintain the opening to the implant.
|Access hole in gum to expose implant|
Appointment 6 (1 – 3 weeks after exposure): Study models taken that record exact location of implant
When the study models are poured they produce an exact replica of the patient’s jaws, with the implant simulation in place. Using the models, the dentist orders the exact size of post or fixture that will be attached to the implant and used to hold the restoration (such as a crown). The surgeon or the restorative dentist may perform this step.
Stage 2: Abutment Connection
Following adequate healing, a small incision or tissue punch is made in the gum to expose the implant. An abutment (or post) is then attached to the implant, exiting the gum so as to not allow the tissue to grow over and cover the implant.
The restorative dentist can use the study models, with the post attached to the simulated implant, to analyze the case before the patient is seen. The post may be contoured to the desired shape on the models, so only minimal refinements are needed when seated in the mouth.
Appointment 7: Post seated permanently in the implant, and shape refined. Temporary crown placed on post (Final impressions for the crown may be taken at this appointment)
|Post seated in implant||Post shaped to receive crown|
Appointment 8 (if needed): Final impression for crown taken and sent to lab
Stage 3: Crown
A temporary or definitive restoration is placed on the abutment. The final restoration is similar to a crown on a natural tooth, and is not removable. It feels and functions as a normal tooth.
Appointment 9: Final crown seated and occlusion (bite) refined
There can be a number of variations in treatment. Under ideal circumstances it may be possible to place the implant without reflecting the gum, using a small punch hole for access to the jaw. In these cases a healing cap may be placed at the surgical appointment, negating the need for the secondary implant exposure surgery (Appointment 5). Conversely, surgery may reveal less bone than expected, and implant placement may be delayed while more bone is generated.
In many cases, it is feasible to place the implant at the time of tooth extraction (immediate implant placement). This affords the patient the benefit of less surgery as well as decreased healing time. In esthetic cases, we offer patients immediate tooth replacement – the hopeless tooth is extracted, the implant placed with the abutment connection, and a temporary crown is fabricated, all in the same day. Patients greatly appreciate a single surgical solution to replacing a tooth without the need for a removable provisional. With the latest advances and techniques in implant dentistry, we also provide full arch immediate teeth replacement – extraction of hopeless dentition, placement of 6-10 implants, abutment connections, and fabrication of a full arch temporary prosthesis, all in the same day (Immediate loading).
This ability to add a tooth where it is needed has changed the way dentistry is practiced.
Implant placement is surprisingly easy, and generally there is little more than “aspirin pain” post-operatively. This is because the bone that receives the implant has no nerve endings, and the only minor discomfort is the incision in the gum. The implants are checked regularly after placement to follow healing. It takes 3-6 months for the implants to integrate (bond) with the jawbone, at which time the post is placed. The last phase is placement of the final crown or appliance.
Patient Selection, Replacement, & Risks
For successful implant placement, there must be sufficient bone height and width to hold the implant. In the lower jaw there must also be sufficient bone available above the mandibular nerve, which runs within the jawbone. The amount of bone available is determined by clinical exam, and by x-rays. If insufficient bone exists, we now have the ability to increase the amount of bone with ridge augmentation procedures. In the upper arch, the proximity of the sinus may reduce the amount of bone available. Sinus lift procedures can add bone to the floor of the sinus, allowing for implant placement.
The ideal candidate for dental implants is in good general and oral health. Smoking, while not a contraindication, is a risk factor.
Recently, concern has grown over bisphosphonate use and osteonecrosis of the jaw following dental surgery (extractions or implants). Studies indicate that while this is more common with intravenous bisphosphonate therapy (zoledronic acid or pamidronate – used to treat certain cancers and Paget’s disease of bone), complications in healing with use of oral bisphosphonates (i.e. Fosamax, Actonel, Boniva) is far less common, with incidents between 0.09% – 0.34% following tooth extraction (Mavrokokki et al. Journal of Oral Maxillofacial Surgery 2007). Those who did show a reaction had a high incidence of untreated periodontal disease.
Studies also show that dental implant surgery does NOT place these patients at higher risk for osteonecrosis. A study from Montefiore Medical Center, Albert Einstein College of Medicine, reported that of 115 patients taking oral bisphosphonates, none showed any evidence of osteonecrosis following implant surgery. A total of 468 implants were placed; 466 were in function and successful, with no reports of osteonecrosis (Grant et al. J Oral Maxillofacial Surgery 2008).
Creating Bone in the Upper Jaw
There are two procedures which can be utilized to increase the amount of bone where there is a low sinus. They are:
- Internal Sinus Lift (ISL) [more conservative] – The small amount of bone is pushed up and augmented- the implant is placed at the same visit.
Dental Implants Case #18
|The maxillary sinus is low leaving minimal amount of bone for retention of the implants.
|An ISL was performed increasing the bone around the implants.|
Dental Implants Case #19
|Radiograph showing a low sinus with inadequate bone for implants.||6 years after augmentation and implant placement this radiograph shows the increased amount of bone.|
Dental Implants Case #20
|Pre-op x-ray showing minimal bone below the right and left sinuses.||X-ray 6 months later after bilateral internal sinus lifts have been done at the time of implant placement.|
2. Window Sinus Lift – This procedure is utilized when there is inadequate bone and to stabilize an implant. A window is cut in the side of the jaw, the sinus is lifted and bone is placed to keep it up. After 6-8 months of healing implants are placed followed by another 4-6 months of healing. At times the patient’s blood is drawn, spun down and the patient’s own cells are utilized to aid healing.
Dental Implants Case #21
Dental Implants Case #22
|Bone loss and infection is demonstrated in this x-ray. A window sinus lift was performed followed by implant placement 6 months later.
|Final radiograph of the implants and restorations- 3 years later.
When traditional dental x-rays do not provide sufficient information on the shape and amount of bone, a CAT scan is recommended. This digital information is then sent to Columbia Scientific, Inc., a company that reformats the data for dental use. Using a computer program called Sim/plant, we can view the jawbone from various angles. It becomes easy to determine the height, width, and density of the bone, and the location of the mandibular nerve and the maxillary sinus. Implant simulations can be done on the computer, so the exact size and ideal location for the implant is known.
An implant of similar size (width and length) is placed into position on the computer to simulate the actual implant.
For the majority of implants, clinical examination with x-rays is sufficient for treatment planning. However, for more complex cases, the Sim/plant provides precise information about jaw anatomy and warrants the extra expense.
Risks of Implant Placement
As with any surgical procedure, there are risks involved with implants. The greatest single concern with implant placement is impingement on the mandibular nerve, which is found in the lower back jaw. Damaging this nerve can cause a permanent numbness of that side of the lower lip. By carefully evaluating the position of the nerve with x-rays or Sim/plant, the risk of injury is very small and seldom occurs.
Another complication of implant placement is infection, an unusual occurrence that generally develops within six months of placement and may cause failure. We usually do not know why the implant fails, but it is thought it may be due to bacteria that were already present in the bone before the implant was placed. Prior to and during implant placement, we minimize the bacterial load in the oral cavity by prescribing preoperative antibiotics and antibacterial mouthrinses (Peridex), as well as performing the procedure under a full surgical scrub (similar to a hospital operating room). Sometimes the bone just does not bond to the implant. We do know that there is no such thing as bone rejection of an implant. Fortunately, most failed implants can be replaced with another implant. The success rate of implants reported in the dental literature ranges from 92%-97%, depending on the study. Implants can successfully be placed in adults of any age, although certain health problems may contraindicate their use. Your dentist will determine if you are a candidate for dental implants after a careful review of your dental and medical history.
If an implant fails (there is a 2-4% chance of failure) it may be replaced immediately with another implant or the ridge may have to be augmented with bone. In that case there is a 3-4 month healing period prior to implant placement