Most general
dentists perform routine tooth extractions, some impacted third
molar extractions and, to a lesser degree, apical and periodontal
surgeries. However, a much-needed surgical procedure should
be incorporated into more practices-alveolar ridge preservation.
This procedure is simple, easy, fast and relatively inexpensive.
It does not require a significant learning time.
The esthetic
and functional advantages of ridge preservation are impressive.
After practitioners see the result of ridge preservation, they
become committed to the concept. This article discusses indications
for ridge preservation, describes the technique and explains
what outcomes to expect over a period of time.
INDICATIONS FOR RIDGE
PRESERVATION
Dentists often encounter clinical
situations in which teeth have been extracted in areas of esthetic
concern. As a result, the alveolar bone has resorbed, the soft
tissues have shrunk and the final non-anatomical prosthesis
appears to be false. Such negative results usually can be avoided
by using ridge preservation
techniques.
The primary indication for alveolar
ridge preservation is a collapse of alveolar bone and soft tissue
that would cause unacceptable
prosthesis esthetics.
Such situations usually involve
maxillary and mandibular anterior
teeth, as well as maxillary and mandibular premolars. Another
excellent indication for ridge preservation is a collapse of
the alveolar ridge that would cause irregularities inalveolar
form, making denture construction difficult.
A third, less common but highly
important indication is tooth extraction, after which ridge
preservation should be performed to provide adequate bone for
subsequent implant placement.
There has been discussion about the desirability of ridge preservation
after all tooth extractions.
However, taking such an aggressive approach
is a decision for each practitioner.
SELECTING THE APPROPRIATE
METHOD AND MATERIAL
Deciding to perform ridge preservation.
Carefully observe the site where a tooth is to be extracted.
Would shrinkage of alveolar bone beyond its current level make
prosthodontic placement difficult? If bone shrinkage appears
to be a potential problem, ridge preservation should be performed.
Selecting material for ridge
preservation. There are several excellent, easily used materials
available for ridge preservation. The concept is simple! A biologically
compatible material is placed in the debrided alveolar socket
to prevent collapse of bone to the extent usually expected.
Some of the available materials stimulate bone growth. The materials
resorb, and after a few months the extraction site appears normal
in radiographs. Other non-resorbable materials remain in place
indefinitely, stimulating bone
growth in and around the implanted material. Such materials
are usually observable in radiographs indefinitely.
Most bone-fill materials work
best when used with a membrane over them, which keeps soft tissue
from growing into the extraction socket (a process called guided
tissue regeneration, or GTR). Such materials usually require
primary soft tissue closure, although some research has shown
that they will work satisfactorily without primary closure.
Other materials do not require
a protective membrane or primary soft-tissue closure. Such materials,
obviously, are easier and less expensive to use.
One of the easiest methods of
preserving ridges without using
GTR employs a material with a long history of acceptability.2
This material (Hard Tissue Replacement, or HTR, Septodont Inc.)
consists of porous polymethyl methacrylate spheres, coated with
polyhydroxyethyl methacrylate and calcium hydroxide.
Two sizes of
spheres are available-24 (0.75 millimeters) and 40 (0.55 mm).
The larger size (24) is used for ridge preservation. The major
reasons for using this material are its ease of placement, the
lack of need for membrane (GTR) placement, and the lack of need
for primary soft-tissue closure. The cost is moderate. Other
materials certainly may be used, but the simplicity of using
HTR makes it an excellent choice.
THE TECHNIQUE
- Tooth removal. Accomplish
tooth removal atraumatically. Preserve bone, and do not break
pieces of bone away from the
ridge.
- Socket debridement. Remove
any soft-tissue debris from the tooth socket. If the socket
had a cystic lesion, roughen the bone surrounding the soft-tissue
lesion. Stimulate bone bleeding.
- Incorporation of blood and
HTR. Place the filter on the tip of the HTR syringe in the socket
and aspirate blood from the socket into the syringe. Avoid blood
from soft tissue; use blood from the bleeding bone. Let the
blood-HTR combination sit for a short time. It will soon thicken,
making it easier to use.
- Place the blood-HTR mixture
in the socket. Inject the jellylike mass ofHTR into the socket,
filling it to the crest of the bone. Use a blunt instrument
to compact the HTR into the socket, making sure it is dense.
Remove any excess spheres that are coronal to the bone crest.
- Close soft tissue. If there
is enough soft tissue present, suture the soft tissue together
and perform primary closure. If there is not enough soft tissue
present to close the wound, cut a piece of
cellulose (Gelfoam, Upjohn) to fill the coronal portion of the
soft-tissue void, extending the cellulose about 2 mm lateral
to the void. Place the soft tissue on top of the cellulose with
sutures over it to hold it in place. Have the patient bite on
the wound for a few minutes until an initial blood clot forms.
The patient should avoid chewing on the extraction site for
several days
THE OUTCOME
HTR appears radiopaque in the
extraction socket. The material is not resorbed. Radiopacity
of HTR remains apparent in the
future, but it will blend with bone and become somewhat less
obvious. The socket will retain much of its original size, because
HTR does not allow bone collapse to the normal degree. Research
shows that ridge preservation techniques can lead to a significant
reduction in the normal 40 to 60 percent loss of bone that occurs
within two to three years of a tooth extraction.34
If you have planned to place
a fixed prosthesis with a pontic in the extraction site, be
aware that the longer you wait after the ridge preservation
procedure before making the final tooth preparations, the more
mature will be the bone in the extraction site, and the more
predictable will be your esthetic result. I prefer that the
site heal for at least two months before I make final tooth
preparations. If you plan to place an implant in the extraction
site, wait about one year before doing so to allow bone maturation.
OTHER USES
HTR can be used in apicoectomy
sites, periodontal defects and around bone voids at the time
of implant placement or in other areas.
SUMMARY
Ridge preservation should be
a commonly used dental procedure. However, it is not. Simple
ridge preservation techniques, using materials such as HTR,
provide undeniable esthetic and functional benefits to patients
and dentists.
