Dental ImplantAn introduction to dental implant

What is a dental implant?

• A dental implant is an artificial tooth root that is placed into jaw to hold a replacement tooth or bridge. Dental implants may be an option for people who have lost a tooth or teeth due to periodontal disease, an injury, or some other reason.

What Are the Types of Implants?

• There are three types of implants, and they can be described according to their shape and how they are attached to the jaw.

1. ENDOSSEOUS (en-doss-ee-us)-“within the bone”

2. SUBPERIOSTEAL (sub-pear-ee-oss-tee-al)-“on top of the bone”

3. TRANSOSTEAL (trans-oss-tee-al)-“through the bone”

ENDOSSEOUS “within the bone”

These implants are usually shaped like a screw or cylinder and are made either of metal, metal covered with ceramic, or ceramic material. They are placed within the jawbone. There are also blade-shaped endosseous implants

SUBPERIOSTEAL -“on top of the bone”

• These implants consist of a metal framework that attaches on top of the jawbone but underneath the gum tissue.

TRANSOSTEAL -“through the bone”

• These implants are either a metal pin or a U-shaped frame that passes through the jawbone and the gum tissue, into the mouth.

Parts of dental implant

What are the implants made of?

• Modern dental implants can fuse with bone through a biologic process called Osseointegration. Materials such as titanium, and some ceramics form this bone integration instead of causing a foreign body reaction as found with most other materials.

OSSEOINTEGRATION

• A direct structural and functional connection between ordered living bone and the surface of a load carrying implant

• Dental implants work by a process known as osseointegration, which occurs when bone cells attach themselves directly to the titanium surface, essentially locking the implant into the jaw bone. New studies shown Osseointegration will be completed within 8 weeks.

BONE QUALITY

• Greater density; better chance of success

Ideal Implant Spacing

• Remember 2 mm as a key figure. An implant needs about 2 mm of bone between it and the neighboring tooth to allow normal bone metabolism. This space allows for normal bone metabolism to maintain the periodontium around the tooth, and enough space for force-adaptation of the osseointegrating column of bone around the implant. 2 mm is also minimal safe distance to plan from the tip of the implant to any anatomical limitation.

Ideal Implant Spacing

• The second important number is 3 mm. This refers to the minimum distance between implants. Since there is no periodontal ligament around implants, there is inherently less blood supply around implants than around a natural tooth, which receives a rich blood supply from the PDL. The effects of a lower blood supply has manifested over time clinically and in the literature as more bone loss between implants that are closer than 3 mm. Cleansability is even more ideal with closer to 4 mm between implants.

Ideal Implant Spacing

• The last number to remember is 7 mm, referring to the minimum amount of space from the top of the implant to the opposing dentition. 9 mm occlusal space is more ideal, and a little less is acceptable for a short, squatty screw-retained restoration.

Different approaches to placement DI

1. Immediate post-extraction implant placement.

2. Delayed immediate post-extraction implant placement (two weeks to three months after extraction).

3. Late implantation (three months or more after tooth extraction).

Basic implant surgical procedure

• Most implant systems have five basic steps for placement of each implant:

• 1. Soft tissue reflection: An incision is made over the crest of bone, splitting the thicker attached gingiva roughly in half so that the final implant will have a thick band of tissue around it. The edges of tissue, each referred to as a flap are pushed back to expose the bone. Flapless surgery is an alternate technique, where a small punch of tissue (the diameter of the implant) is removed for implant placement rather than raising flaps.

Ridge missing tooth

Basic implant surgical procedure

2. Drilling at high speed: After reflecting the soft tissue, and using a surgical guide or stent as necessary, pilot holes are placed with precision drills at highly regulated speed to prevent burning or pressure necrosis of the bone.

3. Drilling at low speed: The pilot hole is expanded by using progressively wider drills (typically between three and seven successive drilling steps, depending on implant width and length). Care is taken not to damage the osteoblast or bone cells by overheating. A cooling saline or water spray keeps the temperature low

Slow speed drill

Tissue opened

Basic implant surgical procedure

4. Placement of the implant: The implant screw is placed and can be self-tapping, otherwise the prepared site is tapped with an implant analog. It is then screwed into place at a precise torque so as not to overload the surrounding bone (overloaded bone can die, a condition called osteonecrosis, which may lead to failure of the implant to fully integrate or bond with the jawbone).

5. Tissue adaptation: The gingiva is adapted around the entire implant to provide a thick band of healthy tissue around the healing abutment. In contrast, an implant can be "buried", where the top of the implant is sealed with a cover screw and the tissue is closed to completely cover it. A second procedure would then be required to uncover the implant at a later date.

Healing abutment

Implant fixture

Adjunctive surgical procedures(bone grafting and

soft tissue surgery)

• Three common procedures are:

1. The sinus lift

1. Lateral alveolar augmentation (increase in the width of a site)

1. Vertical alveolar augmentation (increase in the height of a site)

loading of dental implants

1. Immediate loading procedure.

2. Early loading (one week to twelve weeks).

3. Delayed loading (over three months)

Healing time (old Studies)

• For an implant to become permanently stable, the body must grow bone to the surface of the implant (Osseointegration)

• Based on this biologic process, it was thought that loading an implant during the osseointegration period would result in movement that would prevent osseointegration, and thus increase implant failure rates. As a result, three to six months of integrating time (depending on various factors) was allowed before placing the teeth on implants.

Healing time (New Studies)

• the initial stability of the implant in bone is a more important determinant of success of implant integration, rather than a certain period of healing time. As a result, the time allowed to heal is typically based on the density of bone the implant is placed in and the number of implants splinted together, rather than a uniform amount of time. When implants can withstand high torque (35 Ncm) and are splinted to other implants, there are no meaningful differences in long-term implant survival or bone loss between implants loaded immediately, at three months, or at six months. The corollary is that single implants, even in solid bone, require a period of no-load to minimize the risk of initial failure.( 8 weeks)

Risks and complications (During surgery)

• Placement of dental implants is a surgical procedure and carries the normal risks of surgery including infection, excessive bleeding and necrosis of the flap of tissue around the implant. Because the surgeon is blind to the location of the tip of the drill when it is in the bone, nearby anatomic structures can also be injured such as the inferior alveolar nerve, the maxillary sinus and blood vessels.

Immediate post-operative risks

1. Infection (pre-op antibiotics reduce the risk of implant failure by 33 percent but have no impact on the risk of infection)

2. Excessive bleeding

3. Flap breakdown (less-than 5 percent)

General considerations

• Planning for dental implants focuses on the general health condition of the patient, the local health condition of the mucous membranes and the jaws and the shape, size, and position of the bones of the jaws, adjacent and opposing teeth. There are few health conditions that absolutely preclude placing implants although there are certain conditions that can increase the risk of failure. Those with poor oral hygiene, heavy smokers and diabetics are all at greater risk for a variant of gum disease that affects implants called peri-implantitis, increasing the chance of long-term failures. Long-term steroid use, osteoporosis and other diseases that affect the bones can increase the risk of early failure of implants

THANK YOU

Morteza Parmis