ENDODONTICS
- Root Canal Therapy
Endodontic Surgery
Many dentists
believe that the objective of endodontic surgery is to eliminate
infected root apicies and/or periapical tissue. Often endodontic
surgery is referred to incorrectly as an apicoectomy.
Actually, apicoectomy by itself is seldom enough to resolve root
canal failures. The purpose of an apicoecomy is only to allow
us to read the root and examine the canals. To seal the canals,
some form of retrofilling is usually necessary.
Apicoectomy may
be considered definite treatment, however, in cases of mechanical
failure such as apical blockage or perforation. Such complications
may result in failure of an otherwise perfectly obturated root
canal system. Surgical removal of the untreated apical portion
of the root will correct the problem.
Apicoectomy is
merely one step toward the final objective - the retroseal.
Retroseal is
the process that finally resolves most endodontic failures. Since
the 1950s most clinicians have realized that virtually all failures
result from leaking root canal systems. The often quoted Study
attributed root canal failures to apical percolation (63.46%),
operator error (14.42%) root perforation (9.61%), calcified canals
(3.85%), broken instrument (.96%), or case poor selection. Apicoectomy
and retroseal can reverse all of these errors except improper
case selection and some types of operator error.
It should be emphasized that endodontic surgery is not to be used
instead of conventional endodontics. Surgery is indicated when
conventional techniques cannot be used.
Indications
for Endodontic Surgery
There are nine
indications for resorting to endodontic surgery, and they are
as follows:
1. Aberrant
Anatomy
Maxillary molars,
mandibular incisors, and mandibular first premolars are often
problematic simply by virtue of their anatomy.
At least 50% of all maxillary molars have a second canal in the
mesiobuccal root. The ones that start in the pulp chamber are
easy to clean and fill, but if the canal divides part of the way
down the canal, diagnosis and obturation are difficult or impossible.
Thank goodness
lower anteriors are the least treated of all teeth in the mouth,
because two thirds of them have two canals, and half of those
have a second apical foramen. Normal X-ray angulation does not
reveal these potential problems.
Lower premolars
(bicuspids) have a mesial invagination (groove) of the root sheath,
formed during embryogenesis. One of the diagnostic signs of a
lower first premolar is the mesial groove. The invagination of
the root often creates a second canal, but fortunately, those
second canals usually calcify shut. If they do not, endodontic
failure may result.
2. Conventionally
Blocked Apices
If you have a
case with a post and core that would have to be removed prior
to conventional retreatment, and such removal would jeopardize
the ultimate prognosis of the case, surgery is the most conservative
treatment.
Endodontic surgery usually takes less than 30 minutes and is is
successful most of the time.
3. Iatrogenic
Repair
Sometimes the
only way to remove a broken file is with endodontic surgery. If
a portion of the broken file protrudes through the apex, surgery
is indicated.
4. Acute
Pain
When a patient
remains in so much pain that there seems to be no other relief.
Often the tooth has been opened for drainage, but there is no
relief. The tooth remains exquisitely painful to the touch.
The tooth and
tissue are numbed. As soon as the pushed back the tissue, pus
may be expelled, relieving the pressure, and the patient will
experience immediate comfort.
When you achieve
this type of drainage, itıs important that you do the root canal
right then. Thereıs no reason not to.
You can see the apex, so quickly clean and shape the canal. File
long, flush and dry with the three-way syringe. Push a master
point through the apex, grab it with a pair of cotton pliers,
pull it tight, and cut off the point.
If treatment
is delayed, it may leave the periapical area open to further infection.
It only takes 10 or 12 minutes to complete the case at the time
of surgery, and the patient will go home and start getting better
right away.
If a patient
has cellulitis, however, that is not the time to do endodontic
surgery.
The local anesthetic
will not work because the pH is so low the anesthetic is neutralized.
When you make an incision, nothing but blood comes out. You try
to manipulate the tissue, and it feels like the hardest rubber
you can imagine. Tese patients should be placed on a strong antibiotic
regime until the swelling subsides.
5. Persistent
Cyst
The most misunderstood
area in all of endodontic surgery is the notion that all cysts
must be completely removed to promote healing. If root canal problem
is completed, then the cystic area will reverse. Therefore, 100%
enucleation of the cyst is not necessary. If the cyst starts to
encroach on sensitive anatomy, only a portion of it should be
carefully removed. A cystic area will not recur following complete
sealing of the apex.
If a cyst is
removed, it should be sent it for a biopsy. If it's worth taking
out, itıs worth sending out for biopsy. This is standard of care
in the endodontic community.
6. Cracked
root
Cracked roots
are very difficult to diagnose. When you find one, you can often
do a root resection at the bottom of the crack. When the cracked
portion is removed, the typical narrow, deep pocket will disappear.
7. Perforated
Apex
The real problem
with root perforation is that a portion of the canal is left unfilled.
Apicoectomy removes the unfilled section of the canal, and retrofilling
seals the new apex.
8. Diagnosis
Raising a flap
is a tremendous diagnostic tool. You usually will see the cause
of the problem and be able to treat it immediately.
9. Treatment
alternatives
You often can
save the patient a lot of time and money with apical surgery.
It is often quicker and more cost effective to do an apicoectomy
and retrofill than to remove and replace a post, core, and crown.
Silver point too long? Raise a flap and tap it back up and out
of the canal.
Treatment Considerations
The fear of exposing
the Maxillary sinus causes great hesitation among many GPs. If
you use the proper flap design (full thickness), opening the maxillary
sinus is not a problem. The patient should be warned not to blow
his nose for 36 hours and put on antibiotics. Within minutes of
replacing the flap, the vascularity will be re-established will
begin.
Once it is found
that the sinus is not a problem, access can be gained to the palatal
root of molars and premolars through the sinus, and that approach
is much more predictable than raising a palatal flap. Use fiber-optic
illumination for good visibility in the sinus.
Apex
Location
Usually when
a flap is lifted, it will be found that a hole in the bone or
a discoloration of the osseous structure is present. The granuloma
usually erodes the buccal plate. If that has not happened, the
high buccal approach to safely locate the root apex is indicated.
For the high
buccal approach, a small window 2mm to 3mm below the crest of
the bone to locate the root is performed, and then the root is
traced to the apex. Slowly the window is enlarged apically to
the root apex.
Molar roots are
the most difficult to locate.
If the canal length is known, a rubber stopper on a file aligned
over the long axis of the involved tooth helps pinpoint the apical
area. This technique only works for straight- rooted teeth, and
in general is not applicable to posterior teeth.
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