Download - j Am Dent Assoc 2005 Christensen 1711 3
-
7/28/2019 j Am Dent Assoc 2005 Christensen 1711 3
1/3
JADA, Vol. 136 http://jada.ada.org December 2005 1711
Endodontic therapy is amajor part of general
dental practice and asignificant income-producing procedure.
General dentists report thatendodontic therapy is increasingin need. Many practice adminis-
tration courses stress the impor-tance of making endodontic
therapy a fast, easy and effec-tive part of practice, and den-tists are eager to accomplish
endodontic treatment. Althoughreports concerning the long-termsuccess of endodontic therapy
vary, American dentists seem tobe relatively satisfied with theclinical success and pre-
dictability of endodontic treat-
ment. Many adults have bene-fited from at least one
endodontically treated tooth.Few dental maladies are aspainful as a tooth that needs
endodontic therapy, and fewdental patients are as pleased
with their dental therapy as arethose who receive successfulendodontic treatment.
However, why are more teethdying? Why is so much
endodontic therapy needed? Is itbecause more teeth are being
heroically saved, or becausepatients are living longer thanin the past and, therefore,
retaining more teeth that laterneed endodontic therapy? Or arewe inadvertently killing more
pulps with some of the tech-niques, instruments and
materials commonly used today?This article includes some of
the potential ways to kill a
dental pulp, based on observa-tions I have made in visits tomany dental offices, and on my
discussions with thousands ofdentists around the world aboutthe clinical methods they use in
their day-to-day dental practices.
DENTAL TECHNIQUESPOTENTIALLY RELATEDTO PULPAL DEATH
Resin-based composite usedto restore posterior teeth.I have been told by numerous
endodontists that one of themost significant factors relatedto the increase in need for
endodontic therapy has been thepopularity of resin-based com-
posite to restore posterior teeth.Without proper use of dentin
bonding/sealing materials, it iswell-known that Class I and IIresin-based composite restora-
tions cause postoperative toothsensitivity and potential pulpaldeath. Fortunately, this cause of
pulpal death appears to bedecreasing in incidence because
more practitioners are usingdesensitizing liquids containingglutaraldehyde or hydroxyethyl
methacrylate, resin-modifiedglass ionomer liners and self-etching primers instead of total-
etch primers.1 These materialsseal dentinal canals by impreg-nating them with resin or coagu-
late or physically seal dentin.
However, because of resin-basedcomposites known ability to irri-
tate the pulp, there still is resis-tance on the part of some den-tists to using this restorative
material in posterior teethinstead of conventional
amalgam. Resin-based com-posite can be used withoutpulpal sensitivity and subse-
quent pulpal death when properbonding agents, liners and
How to kill a tooth
OBSERVATIONS GORDON J. CHRISTENSEN, D.D.S., M.S.D., Ph.D.
Copyright 2005 American Dental Association. All rights reserved.
-
7/28/2019 j Am Dent Assoc 2005 Christensen 1711 3
2/3
1712 JADA, Vol. 136 http://jada.ada.org December 2005
desensitizing solutions are used.Resin-based composite
cement for indirect restora-tions. In recent years, dentistshave reported that their
patients have experienced unac-ceptable postoperative pulpalsensitivity and some pulpaldeath when total-etch bonding
systems were used before resincements were placed.2 However,some manufacturers continued
to advertise and teach that theirresin cements and bonding sys-tems did not produce such ill
effects. Apparently, the total-etch primer concept used before
placment of resin cement did notpredictably provide the neces-sary dentinal seal to seat crowns
or fixed prostheses without pro-ducing tooth sensitivity andeventual pulpal death. This
unfortunate situation dissuadeddentists from seating restora-tions with resin cements and
from using indirect restorationsrequiring resin cement. Somepopular products, including the
first one introducedPanavia,in its various forms (Kuraray,
New York)had a separatebottle of self-etching primer (inPanavias case, ED Primer) that
had to be used before the resincement component of theproduct was placed on the tooth.
The Panavia concept dominatedthe marketplace for severalyears and was quite successful.
Other companies copied the con-
cept, and although strengthvalues and other properties
were good with these products,improper use caused occasionallingering postoperative sensi-
tivity, and infrequent pulpaldeath occurred. On the advent of
the self-etching primerresincement combination productsMaxcem (Kerr, Orange, Calif.),
RelyX Unicem (3M ESPE, St.Paul, Minn.) and Universal
Resin Cement (Pulpdent, Water-town, Mass.)the dilemma wassolved.
When use of resin cements isindicated for crown cementation,
I suggest that self-etch resincement products should be usedto eliminate the problemsdescribed here.
Deeply cut veneer prepa-rations. There is a growing ten-dency to cut tooth preparations
for veneers deeply into dentin.3
Usually, the veneers are seatedwith resin cement over bonding
agents that are in the total-etchcategory. Because the ceramicveneer can be made thick, this
technique makes matching thedesired tooth color easier than
when the veneer preparationsare cut to a shallow level. How-ever, veneer preparations that
are cut deeply into dentin andthen treated with total-etchprimers can have objectionable
characteristics. These problemsinclude postoperative tooth sen-sitivity, debonding after thermal
changes, occlusal stresses while
eating and pulpal death. I sug-gest that veneer tooth prepara-
tions should be made in enamelwhenever possible. Such prepa-rations do not cause these
problems.Deeply cut tooth prepara-
tions for all-ceramic crownsand fixed prostheses. Thegrowing popularity of all-
ceramic crowns and fixed pros-theses has created an increase
in postoperative tooth sensi-tivity and pulpal death. Often,to change tooth color, contour or
occlusion, these restorations areplaced on nearly virgin teeth
with large pulps or on youngteeth with large pulps and wide-open dentinal canals. Thesetooth preparations must be at
least 1 to 11/2 millimeters deepon all surfaces, except theocclusal surface, where the
reduction should be 11/2 to 2 mm.Such deep tooth preparations onteeth with large pulps require
meticulous care to avoid toothsensitivity or worse effects. For-
tunately, some of the alumina-or zirconia-based all-ceramicrestorations can be seated with
resin-modified glass ionomercement (such as RelyX LutingCement, 3M ESPE, or GC
FujiCEM, GC America, Alsip,Ill.), which reduces or eliminatespostoperative tooth sensitivity.
However, to provide adequatestrength for pressed ceramicindirect restorations, and to
avoid the hygroscopic expansionof the resin-modified glass
ionomer cements on these some-what weaker restorations, therestorations should be cemented
with resin-based compositecements. I suggest that pressedceramic restorations should be
cemented with the self-etchprimerresin cements suggestedpreviously in this article to
reduce or eliminate postopera-
tive problems.Occlusion too high on res-torations. Fixed prosthodonticprocedures are carried out farmore frequently now than they
were in years past. On manyoccasions in my practice, I have
observed crowns and fixed pros-theses, placed elsewhere, thatwere left in supraocclusion after
cementation. I have seen den-tists seat fixed prostheses
O B S E R V A T I O N S
When use of resin
cements is indicated
for crown
cementation, self-etchresin cement products
should be used.
Copyright 2005 American Dental Association. All rights reserved.
-
7/28/2019 j Am Dent Assoc 2005 Christensen 1711 3
3/3
without checking and correctingocclusal contacts, with the resultthat the affected tooth or teeth
soon become highly sensitive. Toavoid the high occlusion, the
teeth move in the bone to loca-tions that do not have the samehigh occlusion. Often, theaffected teeth cannot move far
enough to get out of the zone ofocclusal trauma. The clinicalresult is a widened periodontal
ligament, mobile teeth, painfulteeth, open contact areas,chipped ceramic, loosening of
implants or implant abutments,and eventual pulpal death of the
restored or opposing teeth. Inmy opinion, clinicians must paymore attention to correcting
occlusion when seating compre-hensive restorations.
Aggressive or dry toothcutting and dull rotaryinstruments. High-speed airrotor handpieces, and especially
electric high-speed handpieces,cut extremely rapidly and cancause significant vibration in
the teeth being prepared. Also,many dentists do not use signifi-
cant water lavage when cuttingteeth. I have seen teeth developblack burn marks as high-speed
handpieces and dull burs orworn-out diamond rotary instru-ments are used with too much
pressure while cutting. Howmuch trauma can a dental pulptake before dying, and how long
after cutting a tooth preparation
does the pulp die? We dontknow. I suggest using new car-
bide burs for each patient when-ever possible and new, single-use rotary diamond instruments
for every patient. When usingnew rotary instruments each
time, the clinician has no doubtthat the instruments are sharp
and concentric. Additionally, Isuggest using careful low-loadcutting with either air rotors or
electric handpieces. These hand-pieces cut fast and well, even if
high cutting load is not used onthem.
High exothermic activityin provisional restorations.Try holding an unset piece ofpolymethyl methacrylate orpolyethyl methacrylate in your
hand while the specimen sets.You will have to release it as itgoes through its exothermic set-
ting reaction. Imagine that samehigh temperature on a deeply
prepared tooth. Pulpal damageis unavoidable with improperlyused provisional materials.
These materials must be cooledas they are polymerizing. Dentalassistants making these types of
provisional restorations need toknow the significance of highexothermic activity and high
pulpal temperatures. I suggestusing bisacryl provisionalmaterials for one unit or short
fixed prosthodontic situations.These materials do not have a
significant exotherm. When thestrength and color stability ofpolymethyl methacrylate is
needed, I suggest using alaboratory-made polymethylmethacrylate shell for the
exterior of the provisional resto-ration and a liner made ofpolyethyl methacrylate, which
gives off a lower exotherm, in
the mouth for the shell.Dentist error. In addition tothe problems I already havedescribed, numerous other com-monly occurring clinical situa-
tions could be described that log-ically should injure or kill the
dental pulp. Perhaps we den-tists are our own enemies. Per-
haps we are one of the majorreasons for the increased needfor endodontic therapy by virtue
of creating deep preparations,leaving dentinal canals
unsealed, carrying out trau-matic preparations and prema-turely abandoning occlusaltreatment of restored teeth. Per-
haps we are too hasty in accom-plishing endodontic therapy onteeth that are sensitive but may
become nonsymptomatic ifallowed to rest withoutendodontic therapy for a few
more weeks. I feel that is thecase.
SUMMARY
Many dentists report increased
activity in endodontic therapy.Although retention of teeththrough most of life by many
patients and the aging popula-tion are potential reasons forthis increase, it is possible that
some of the new dental pro-cedures, instruments ormaterials that have become pop-
ular in recent years also are sig-nificant causative factors. Sev-
eral potential preventablereasons for increased pulpaldeath and the resultant need for
endodontic therapy arediscussed in this article. s
Dr. Christensen is co-founder and seniorconsultant, Clinical Research Associates, 3707N. Canyon Road, Suite 3D, Provo, Utah 84604.Address reprint requests to Dr. Christensen.
Bibliography1. Christensen GJ. Preventing postoperative
tooth sensitivity in Class 1, 2 and 5 restora-tions. JADA 2002;133:229-31.2. Clinical Research Associates. Artglass,
belleGlass, and Targis System crowns com-pared at one year. CRA Newsletter 1998;22(10):1-3.
3. Christensen GJ. What is a veneer? JADA2004;135:1574-6.
JADA, Vol. 136 http://jada.ada.org December 2005 1713
O B S E R V A T I O N S
Copyright 2005 American Dental Association. All rights reserved.