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Causes of Periapical Infection*
CAUSES OF PERIAPICAL INFECTION* By C A R L J. G R O V E , P h .G ., D .D .S ., F .A .C .D ., St. Paul, M innesota
H E R E are a number o f important causes o f periapical infection which time w ill not permit discussing in this presentation. It is difficult to de termine which o f these play the most important part in the production o f peri apical disease. Frequently, the factors associated with periapical disturbances existing before infection occurs in fluence or control the development o f the disease; therefore, no one cause produces periapical infection. T h e eti ology o f periapical disease w ill not be fu lly understood until an exploration o f all the important factors involved has been made. O n e factor which w ill withstand the most critical inquiry but is not receiving the recognition it deserves, is the liquid diffusion which takes place through permeable root-canal-filling materials used by many dentists. D iffusion o f equal importance takes place through the porosity sometimes existing in the secondary dentin deposited in the root canals. In the laboratory experiments on which the foregoin g conclusions are based, freshly extracted teeth were used, large openings being made into the pulp chambers. T h e teeth were then boiled in sodium hydroxid to aid in rem oving the tissue in the canal. A barbed broach
T
*Read before the Section on Anatomy, Physiology, Materia Medica and Therapeutics at the Seventh International Dental Congress, Philadelphia, Pa., A ug. 26, 1926.
Jour. A.
D . A ., January, 1928
52
was used to remove the remaining pulp tissue. T h e root canals were then filled with the various pastes or solution ma terials
n ow
employed,
guttapercha
cones, methylene blue being sealed in the pulp chamber. T h e ch ie f purpose o f these experi ments was to ascertain whether it was not possible fo r diffusion to take place through
the
lateral
branches o f
the
dentinal tubules. D ifferent methods to bring about diffusion through the lateral branches were employed without suc cess. M ost o f the dentin in the pulp chamber was cut away to give the colorin g solution used access to all the lateral branches o f the tubules. Liquids extending into the permeable root fillin g also penetrated the entire length o f the dentinal tubules to the cementum, but did not pass into or through the cementum. C olorization o f the dentin occurred only where perme able pastes and solution materials were used, and where porous secondary den tin existed. T h e conclusions to be derived from the results o f these experiments are that bacteria have an avenue o f escape fr o m the dentinal tubules to the periapical tissue, infection resulting where per meable root fillings are used. Liquid nutritive material fo r maintaining the growth o f bacteria in the dentin could also be carried through the permeable root fillin g, either fro m the periapical
Grove— Causes o f Periafical Infection
53
tissue or by diffusion through the open
sults o f
occlusal portion o f the tooth with illfitting crowns and inlays, where the
offered as p r o o f that all pulpless teeth
cement has been partly washed out. In the face o f these facts, there can be no uncertainty about the part these conditions play in the production o f periapical in fection , and they should, therefore, receive the serious considera tion o f all dental practitioners p erform ing root-canal operations. T h e practical value o f these experi ments is the demonstration that the es sential physical properties o f a root-canal material must be impermeable and that secondary dentin should be removed before the canals are filled. W h en bacteria are present in the dentin o f teeth with putrescent pulps, it is plain that periapical infection could result when root canals are filled with materials permitting bacteria to reach the periapical tissue. A root-canal solution material pos sessing the essential physical qualities is rosin solution. In these experiments, I used a white rosin solution and gutta percha cones. In all the experiments conducted with the rosin solution, it was dem on strated that only a thin coating o f the solution is required to seal the openings o f the dentinal tubules. T eeth treated in this manner, with the root canals le ft open, were immersed in methylene blue fo r a number o f days without any resultant colorization o f the dentin; which proved that the tubules were closed. T h e medical and dental literature has been replete fo r the past decade with articles calling attention to the fact that a growth o f streptococcus is invariably obtained when root tips are snipped off and placed in culture mediums. T h e re
these experiments have been
are infectious and should, therefore, be extracted. The
mere
fa ct that a growth
of
streptococcus can be obtained by this method does not necessarily prove that such teeth are infected or infectious. T h e investigator’s assumption is that streptococcus is obtained fro m the outer surface o f the root end, whereas it may be obtained fro m the inner portion o f the root by this method. It must be remembered that, although bacteria may be present in the dentin, it is not possible fo r it to pass through the cementum to the outer surface o f the root when the foram en is hermeti cally sealed. It w ould not be possible fo r bacteria to escape fro m the dentin to the periapical tissue; but when the tubules are filled with bacteria, it must be expected that a grow th o f strepto coccus w ill be obtained in snipping o ff the root ends o f such teeth, since a part o f the dentin is cut o ff with the tips used in these experiments. T h e average thickness o f the cementum at the apex is less than 1 m m ., which w ould not be sufficient fo r these experiments. Since it is not possible to determine the thick ness o f the cementum before the root end is cut off, it cannot be maintained that only cementum is used in these experiments. Periapical infection has its inception in that part o f the membrane which fold s into the foram en. In the destruc tion o f this tissue, the underlying ce mentum is denuded o f its covering and its nutrition; which may result in the death o f the cementum, making it a foreign body productive o f irritation, fo llo w e d by further destruction o f peri apical tissue. It can hardly be expected
54
T h e Journal o f the American Dental Association
that permanent repair w ill fo llo w any
mentum on other parts o f the root.
form
also supplies nutrition to this tissue. R oot fillings composed o f vital tissue,
of
treatment where
a chronic
condition exists. T h ere are three causes fo r the de
are
struction o f these tissues:
form ed
( 1 ) mechan
ical causes, such as instrumentation and trauma produced by pressure o f root fillin g ; ( 2 ) infection through lack o f asepsis in root canal operations, and also through permeable root canal fillin g materials, and ( 3 ) the use o f drugs having destructive properties. It is more than a decade since I first called attention to the fa ct that i f the tissue existing in the foram en is re tained, it is possible that cementum may replace this tissue. M y opinion is that such teeth are no more susceptible to in fection than teeth having vital pulps, provided the root canals have been properly filled. T h e periodontal m em brane is attached to and covers this new ly form ed cementum as it does ce
ideal.
Sometimes,
scar
It
tissue
is
instead o f cementum, and it
must be remembered that such tissue has a high resistance, which makes it fa r preferable to any known artificial root-fillin g material. Success in this branch o f dentistry in marked degree w ill not be attained by any root-canal operator w h o does not fu lly recognize the value o f root end tissue. T h ree ch ief causes fo r periapical in fections are ( 1 ) a disregard fo r rootend tissue; ( 2 ) failure to observe asepsis to the fullest extent, and ( 3 ) the use o f permeable root-canal fillin g material permitting the escape o f bacteria fro m the tubules o f the dentin to the peri apical tissue. Pulp removal is not nec essarily a cause o f periapical infection.
THE HISTOLOGIC CHARACTERISTICS OF THE PERI APICAL TISSUE WITH REGARD TO ROOTCANAL TREATMENT* B y A R T H U R H O P E W E L L -SM IT H , Sc.D ., L .R .C .P ., M .R .C .S ., L.D.S., Philadelphia, Pennsylvania
N the limited period at my disposal, it is impossible to do more than pre sent the outlines o f my subject.
I
cementum,
alveolodental
periosteum
and bone, generally needs revision. W ith
regard to nomenclature, the
i.
s o ft fibrous connective tissue which acts
T h e usual conception o f the articu lation tissues o f the teeth, viz.,
as a fibrous gomphosis, and articulates the teeth firm ly, solidly, and im m ov ably to their sockets, is named variously the pericementum, periodontium, dental ligament, peridental membrane and periodontal membrane. Each o f these
*Read before the Section on Anatomy, Physiology, Materia Medica and Therapeu tics at the Seventh International Dental Con gress, Philadelphia, Pa., A u g. 26, 1926.
H E R E are a number o f important causes o f periapical infection which time w ill not permit discussing in this presentation. It is difficult to de termine which o f these play the most important part in the production o f peri apical disease. Frequently, the factors associated with periapical disturbances existing before infection occurs in fluence or control the development o f the disease; therefore, no one cause produces periapical infection. T h e eti ology o f periapical disease w ill not be fu lly understood until an exploration o f all the important factors involved has been made. O n e factor which w ill withstand the most critical inquiry but is not receiving the recognition it deserves, is the liquid diffusion which takes place through permeable root-canal-filling materials used by many dentists. D iffusion o f equal importance takes place through the porosity sometimes existing in the secondary dentin deposited in the root canals. In the laboratory experiments on which the foregoin g conclusions are based, freshly extracted teeth were used, large openings being made into the pulp chambers. T h e teeth were then boiled in sodium hydroxid to aid in rem oving the tissue in the canal. A barbed broach
T
*Read before the Section on Anatomy, Physiology, Materia Medica and Therapeutics at the Seventh International Dental Congress, Philadelphia, Pa., A ug. 26, 1926.
Jour. A.
D . A ., January, 1928
52
was used to remove the remaining pulp tissue. T h e root canals were then filled with the various pastes or solution ma terials
n ow
employed,
guttapercha
cones, methylene blue being sealed in the pulp chamber. T h e ch ie f purpose o f these experi ments was to ascertain whether it was not possible fo r diffusion to take place through
the
lateral
branches o f
the
dentinal tubules. D ifferent methods to bring about diffusion through the lateral branches were employed without suc cess. M ost o f the dentin in the pulp chamber was cut away to give the colorin g solution used access to all the lateral branches o f the tubules. Liquids extending into the permeable root fillin g also penetrated the entire length o f the dentinal tubules to the cementum, but did not pass into or through the cementum. C olorization o f the dentin occurred only where perme able pastes and solution materials were used, and where porous secondary den tin existed. T h e conclusions to be derived from the results o f these experiments are that bacteria have an avenue o f escape fr o m the dentinal tubules to the periapical tissue, infection resulting where per meable root fillings are used. Liquid nutritive material fo r maintaining the growth o f bacteria in the dentin could also be carried through the permeable root fillin g, either fro m the periapical
Grove— Causes o f Periafical Infection
53
tissue or by diffusion through the open
sults o f
occlusal portion o f the tooth with illfitting crowns and inlays, where the
offered as p r o o f that all pulpless teeth
cement has been partly washed out. In the face o f these facts, there can be no uncertainty about the part these conditions play in the production o f periapical in fection , and they should, therefore, receive the serious considera tion o f all dental practitioners p erform ing root-canal operations. T h e practical value o f these experi ments is the demonstration that the es sential physical properties o f a root-canal material must be impermeable and that secondary dentin should be removed before the canals are filled. W h en bacteria are present in the dentin o f teeth with putrescent pulps, it is plain that periapical infection could result when root canals are filled with materials permitting bacteria to reach the periapical tissue. A root-canal solution material pos sessing the essential physical qualities is rosin solution. In these experiments, I used a white rosin solution and gutta percha cones. In all the experiments conducted with the rosin solution, it was dem on strated that only a thin coating o f the solution is required to seal the openings o f the dentinal tubules. T eeth treated in this manner, with the root canals le ft open, were immersed in methylene blue fo r a number o f days without any resultant colorization o f the dentin; which proved that the tubules were closed. T h e medical and dental literature has been replete fo r the past decade with articles calling attention to the fact that a growth o f streptococcus is invariably obtained when root tips are snipped off and placed in culture mediums. T h e re
these experiments have been
are infectious and should, therefore, be extracted. The
mere
fa ct that a growth
of
streptococcus can be obtained by this method does not necessarily prove that such teeth are infected or infectious. T h e investigator’s assumption is that streptococcus is obtained fro m the outer surface o f the root end, whereas it may be obtained fro m the inner portion o f the root by this method. It must be remembered that, although bacteria may be present in the dentin, it is not possible fo r it to pass through the cementum to the outer surface o f the root when the foram en is hermeti cally sealed. It w ould not be possible fo r bacteria to escape fro m the dentin to the periapical tissue; but when the tubules are filled with bacteria, it must be expected that a grow th o f strepto coccus w ill be obtained in snipping o ff the root ends o f such teeth, since a part o f the dentin is cut o ff with the tips used in these experiments. T h e average thickness o f the cementum at the apex is less than 1 m m ., which w ould not be sufficient fo r these experiments. Since it is not possible to determine the thick ness o f the cementum before the root end is cut off, it cannot be maintained that only cementum is used in these experiments. Periapical infection has its inception in that part o f the membrane which fold s into the foram en. In the destruc tion o f this tissue, the underlying ce mentum is denuded o f its covering and its nutrition; which may result in the death o f the cementum, making it a foreign body productive o f irritation, fo llo w e d by further destruction o f peri apical tissue. It can hardly be expected
54
T h e Journal o f the American Dental Association
that permanent repair w ill fo llo w any
mentum on other parts o f the root.
form
also supplies nutrition to this tissue. R oot fillings composed o f vital tissue,
of
treatment where
a chronic
condition exists. T h ere are three causes fo r the de
are
struction o f these tissues:
form ed
( 1 ) mechan
ical causes, such as instrumentation and trauma produced by pressure o f root fillin g ; ( 2 ) infection through lack o f asepsis in root canal operations, and also through permeable root canal fillin g materials, and ( 3 ) the use o f drugs having destructive properties. It is more than a decade since I first called attention to the fa ct that i f the tissue existing in the foram en is re tained, it is possible that cementum may replace this tissue. M y opinion is that such teeth are no more susceptible to in fection than teeth having vital pulps, provided the root canals have been properly filled. T h e periodontal m em brane is attached to and covers this new ly form ed cementum as it does ce
ideal.
Sometimes,
scar
It
tissue
is
instead o f cementum, and it
must be remembered that such tissue has a high resistance, which makes it fa r preferable to any known artificial root-fillin g material. Success in this branch o f dentistry in marked degree w ill not be attained by any root-canal operator w h o does not fu lly recognize the value o f root end tissue. T h ree ch ief causes fo r periapical in fections are ( 1 ) a disregard fo r rootend tissue; ( 2 ) failure to observe asepsis to the fullest extent, and ( 3 ) the use o f permeable root-canal fillin g material permitting the escape o f bacteria fro m the tubules o f the dentin to the peri apical tissue. Pulp removal is not nec essarily a cause o f periapical infection.
THE HISTOLOGIC CHARACTERISTICS OF THE PERI APICAL TISSUE WITH REGARD TO ROOTCANAL TREATMENT* B y A R T H U R H O P E W E L L -SM IT H , Sc.D ., L .R .C .P ., M .R .C .S ., L.D.S., Philadelphia, Pennsylvania
N the limited period at my disposal, it is impossible to do more than pre sent the outlines o f my subject.
I
cementum,
alveolodental
periosteum
and bone, generally needs revision. W ith
regard to nomenclature, the
i.
s o ft fibrous connective tissue which acts
T h e usual conception o f the articu lation tissues o f the teeth, viz.,
as a fibrous gomphosis, and articulates the teeth firm ly, solidly, and im m ov ably to their sockets, is named variously the pericementum, periodontium, dental ligament, peridental membrane and periodontal membrane. Each o f these
*Read before the Section on Anatomy, Physiology, Materia Medica and Therapeu tics at the Seventh International Dental Con gress, Philadelphia, Pa., A u g. 26, 1926.