Response of periapical pathosis to endodontic treatment in monkeys

endodontics Editor. MILTON SISKIN, D.D.S.

College of Dentistrv The Uni\~ersity of Tenrlessee XI 7 Mor1rw ‘4 l’l’nilc Mrmphis.

T~~rulcssw 38163

Response of periapical pathosis to endodontic treatment in monkeys James Malooley, Jr., D.D.S., M.S.D.,* Samuel S Patterson, D.D.S.. M.S.D.. ** and A/&l Kafrawy, B.D.S., M.S.D., *** Indianapolis, Ind. IKDIANA

(‘NIVERSITY

SCHOOL

OF DENTISTRY

Response of induced periapical lesions in monkeys to a conventional endodontic technique was investigated at varying periods ranging from 15 to 365 days after treatment. The findings indicate that response to treatment is influenced by the extent of the root canal filling, the time lapse between treatment and death, and the presence or absence of bacteria in the apical portion of the canal.

T

he conservative approach to endodontic therapy is based on the premise that, with the removal of the noxious stimuli from the root canal, the normal reparative processes already set in motion by chronic inflammation will be able to complete normal connective tissue repair. Periapical healing and repair are important considerations in Grossman’s’ description of endodontic objectives. The objectives are the biomechanical instrumentation of the root canal to eliminate the reservoir of bacteria and the thorough sterilization and hermetic sealing of the root canal. Ingle” described the objectives of root canal obliteration as the development of a fluid-tight seal at the apical foramen and total obliteration of the root canal space. This prevents “apical percolation” or stagnation and subsequent degradation of the blood serum into the unfilled or partially filled portion of the root canal. This degraded blood serum then becomes a physiochemical irritant and causes periapical inflammation to persist. Seltzer” gave several reasons for filling the root *In the private practice of endodontics, Indianapolis, Ind. **Professor and Chairman, Department of Endodontics. ***Associate Professor. Department of Oral Diagnosis/Oral icine. ~~()-122(!/7Y/Oh(,1.5t

IO%01 W/O

0

1979

The c. V Moaby

CO

Med-

canal. He stated that if the root canal is not obliterated, granulation tissue will invade it. The persistence of this granulation tissue will cause resorption of the root, and a treatment failure will result. Also, any space between the root canal filling and the wall of the canal will enable tissue fluid, microorganisms, tissue debris, and metabolites to stagnate and become periapical tissue irritants. The purpose of this study was to evaluate the response of induced periapical lesions in monkeys to conventional endodontic therapy. MATERIALS

AND METHODS

Four male Macaca speciosa monkeys with healthy permanent dentitions were used. Prior to each treatment procedure the animals were anesthetized by intravenous injection of Somonpentyl,” 1 C.C. per 5 pounds of body weight. A series of intraoral radiographs? were taken on each animal prior to the initiation of lesions and at subsequent stages of the study. The exposure settings were 60 KVP and 10 Ma. for % second at a 16-inch focal*Pitman-Moore Company, Indianapolis, Ind. tKodak Ultra-Speed film Eastman Kodak Company. N. Y.

Rochester.

545

film distance. Developing time was 3 minutes at 6X” F. The tilms were fixed for 15 minutes, washed, and dried. The radiographs showed no evidence of any pathosis at the initial examination. Periapical pathosis was induced in thirty-seven teeth. The pulp chambers of the teeth were exposed with a No. 557 bur in a high-speed air-driven handpiece and a No. 6 round bur in a belt-driven low-speed handpiece. The pulp tissue was macerated by barbed broaches passed into the root canals until they just began to meet resistance of the walls in the apical third. On all maxillary posterior teeth. a pulpotomy was performed over the buccal roots because these canals were not acceptable for cndodontic treatment. The buccal pulps were capped with Dycal* and covered with zinc phosphate cement. The opened canals were allowed to remain exposed to the oral flora for I meek. At this point, theq were closed by placing a pledget of cotton in the pulp chamber and covering this with zinc phosphate cement This was done to enhance the development of periapical pathosis. Twenty-three teeth of three of the monkeys were treated cndodontically at 30. 60. and 90 days subsequent to the date of closure. These animals were killed at 10.5 days after the canals were sealed with contaminants. Thus, in retrospect. for histologic and radiographic analysis, the treated lesions were IS day5 35 days. and 75 days postoperative. Two random untreated teeth with the canals sealed with contaminants for 10.5days served as controls. In the fourth animal. ten teeth were treated 2 months subsequent to closure. Postoperative radiographs were taken 6 months and 1 year postoperatively. In this monkey two teeth were left untreated and served as control. The fourth monkq was killed 1 year after completion of cndodontic treatment. The following technique was used for endodontil, treatment.’ I_ The rubber dam was used for single-tooth is&tion. and this was held in place with the aid of ;I clamp on the tooth and an &tbyt rubber-dam frame. The tooth and dam were then swabbed with ;I I : 7,500 tincture of Metaphen.$ 2. Access to the root canal was gained by removing the previous zinc phosphate cement cavity seal. 3. During the first appointment. the proper tile length was determined and the canals were dCbridcd. enlarged. and sealed with CMCP.S; 4. On the second appointment, the canals were cul*The L. tllnion *Abbott $King’s

B. Caulk Company. Milford. Del Broach Company. Inc., Long Island City. Laboratories, North Chicago. III Specialty Company, Fort Wayne. Ind

N \I

lured urth a \tcrilr paper point and a 0. I percent agal and thioglycollate medium. The canals acre prepared to the final si/e for tilling on the ncxl appointment if a negati\c culture uas obtained. Throughout the proccdure. the canal\ \vcre copiously irrigated hith 3 percent c-hloramine-T‘+ solution. 5. The canals w;erc filled on the third appolntmenr It the previous culture was negative. The filling consisted of Mynol gutta-perchaf and Tubli-Seal root curl sealer$ with lateral condensation. The master point uas titted and radiographed. The sealer was mixed accorcling to the manufacturer’s specitications. The master point W;IS coated with sealer and carried to the root canal with grooved endodontic pliers. Lateral condcnsation u ith smaller gutta-percha points Mas employed to oblitcratc the canal space, 6. After the canal has filled. the cxcesx gutta-percha and sealer L\\ercrcmovcd from the pulp chamber uith a hot plastic instrument, fhc coronal preparation Mas cleaned with a round bur In ;I low-speed handpiece and tilled with /In< phosphate cemenl The monkey\ lvere ii?jecteti intraperitoncaliy with an solution of’ Procion Brilliant Red H-XBS$ each aqueous time root c;~nal fillings wcrc completed and 6 months after treatment in the I Lear stud! animal The dosage Mah 100 mg per kilogram of body acight Mith IO ml. ot xtcrilc water. fhc I ital clkc was used to demonstrate the formation 01 an> periapical calcified tissue that \tould hc deposited after treatment. Follo\ving the cuperimcntal period. the monkech \vere killed with an overdose of pentobarbital sodium administered intravenousI>. The mandible and maxilla of each animal Lvcrc removed in toto with a scalpel and electric bone \,IU and placed in IO percent formalin. Block sections c,ontaining the teeth and periapical areas were then separated into segments with a band sau Ail the specimen\ were tiscd for a period of I week in IO percent i‘ormalin and decalciticd in 5 percent t’ormic acid for h to X \\ecks. Semiserial paraffin WCtions 7 ,~m thick wcrc prepared Ever> lourth section was stained with hematoaylin and eoxrn. .ActJacentseetlonh \ccrc \taincd by the Brown and Brcnn method for bacteria. and unstained sections wart’ t?XitllliIld \\ith iluoresccnt microscop} for Procion labeling. RESULTS Clinical findings

Throughout the. experimental period, the animals appeared health!, with no cvidencc of acute episodes

Table I. Radiographic and histologic findings, 90 days infected, 15 days treatment PI.Clrwltll<‘tlt r-o~liolu~~erlc~\

T~wth .Vil. 7 I‘l 76 7 2 12

__“Evidcncc

Rudioluceno a, deurh

uith

Perirrpicd

Granuloma/qst Healing* Granuloma Granuloma/cyst Granuloma/cyst Granuloma

Evident None Evident

No change None Decreasing

Short Even Even

Evident

Decreasing Decreasing None

Long Long Long

Evident NOW

of healing

Hisfologic~ extem of fill

inflammation

associated

with particles

of sealer and/or

WSpO,,W

necrotic

debris in

Brrcrrriu Apical

<,anal -

Aptcal

canal -

penapicalti>hues

Table II. Radiographic and histologic findings, 60 days infected, 45 days’ treatment

___-.

Prc~fr-ecrrI?rewr rtrtliolucY~tK\

/‘00/h .l’o.

Rutiiolucet~c~,~ or drath

Exrent offill

tvident

No change

Short

Evident Evident tciclcnt hone

No change No change Decreasing increasing No change No change Decreasing Increasing Increasing No change No change

Short Short

Konc2

Evident Evident Evident Lvident None

None ~Evtdcncc

of healing

with inHan~n~ation

associated

with particles

Prriclpkrl

Healing” Healing* Granuloma Healing* Healing* Healing* Healing* Healed Granuloma/abscess Granuloma/abscess Healing* Healing*

Short Short Short Even Even Long Long Long Long of sealer and/or

manifested by intraoral or facial swelling. One monkey had a chronic purulent discharge through the gingival sulcus adjacent to a tooth that had been infected for 60 days and treated for 45 days. A second monkey had a similar discharge at the gingival margin adjacent to an untreated control tooth that had been contaminated for 105 days. The monkey used for the long-term study had two molars that were infected and untreated for 440 days. One molar of this animal had a chronic draining sinus tract into the adjacent buccal vestibule. The other molar had a chronic purulent exudate at the gingival sulcus from the buccal aspect of the furcation. Radiographic

rrspom “

findings

A radiographic evaluation of the periapical area of each treated root was made at the time of contamination, at completion of endodontic treatment, and again just prior to death of the animals. In the l-year study, radiographs were also taken 6 months after treatment. No periapical pathosis was evident radiographically at the time of contamination of the selected teeth for this study. A comparison was made of the relative change in size of the pretreatment radiolucency and the radiolucency at the time of death for each periapical

necrotic

debris in periapical

area. The radiographic Tables I to IV. Histologic

Chamber Chamber Apical canal Apical canal

Chamher Apical Apical

canal canal

.____ tissues.

findings are summarized in

findings

Reactions of the periapical tissues were classified into one of the following categories or a combination thereof: (1) periapical granuloma. (2) periapical cyst, (3) abscess. or (4) healing. The criteria for each classification follow. A periapical granuloma appeared as a well-organized lesion with clumps of chronic inflammatory cells (lymphocytes, plasma cells, and macrophages). Occasionally, a few polymorphonuclear leukocytes were present. Interspersed with the chronic inflammatory cells were fibroblasts. fibrous connective tissue, and capillaries. The lesion was encapsulated with a band of fibrous connective tissue. Isolated nests or strands of epithelium were also present occasionally. When epithelial proliferation was more prominent, with the formation of numerous anastomosing strands, the granuloma was considered to be undergoing cystic transformation. The presence of an epithelium-lined cavity was considered to be necessary to classify a periapical lesion as a cyst. A periapical lesion was classified as a granuloma

Table III. Radiographic and histologic tindings. 30 days infected, 75 days’ treatment

13

Evident

‘h 2.3

Evident Evident None kvident Evident Evident None Evident r!VldClN tvidsnt Evident

IO 20 Distal root Mcrial root IO 7 IO 7 IX I)t\tal root llestal root ‘Evtdencc

of healing

with inflammation

Decreasing Ikcrcastn~ IkCtUWl&! Yotlt~ I kcrcastng Increasing L)ecreasinp NOllC f)eiwa\tng Decr~winp lkcrcabing Decreasing associated

with particles

Short Shwt Short s hart h1p I.mp I .otq! Long I Al,‘;

~;r~ttluloma/c!\t (?anuloma (kmulotna (;ratlulmla

(~ranulotnaic~sr (;rilnulotlla/abscr\s Healing’ (kmuloma (iratrul(~n~uii~!\t HL2ling* Healing i (;ranull)trla/abscess

i.,mg Long I .ong of sealer and/or

necrotic

drbrt> tn periaptcal

tiwueh

Table IV. Radiographic and histologic findings, 60 daqs infected, 365 daqs treatment

Table V. Untreated controls

Ir$krni 1115 L/t/\ \ 3 I hlesial roc,t Dihral root I9 Mcsial root Distal root /,!frm/ 440 ikl,l \ 3 I Mesial roo( Distal root 18 Mesial root Distal root

Granulotnas/absces~ Granulomas/absce\s Granulomas/abscess C;ranulomas/absc~~s Granulomas/absccs\ Granuloma.s/abscea Ah\ces\

tibroblastlc and ostcoblastic activity,. At the outer margin. trabcculae of newly formed bone. confirmed \vith Procion labeling. were evident and began to lill the fibrous area. Periapical areas categorized a< “healing almost complete” showed an essentially similar picture but also had strands of connective tissue bcparating small areas of chronic inflammatory cells. These foci ot chronic inflammation wet-c associated with necrotic debris or particles of sealer which had been extruded into the periapical tissue. The histologic lindings are summarized 111Tables I lo v.

Pertapical radiolucenctes were present tn all ir;frcte~l control teeth at death Hea\) bacterial deposits were evtdent in the BrowwandHrenn-jtalned section5 of all control canals

Teeth sealed with contaminants treated for 15 days

abscess when it showed. in addition to the I’eatures described as a granuloma. areas of dense PMN intiltration undergoing liquefaction. The periapical abscess showed a central area ot liquefaction necrosis and a dense aggregation of polymorphonuclear leukocytes. Proceeding peripheralI\. the neutrophilic intiltration decreased and plasma cells. lymphocytes, and macrophages were present. The periapices showing healing demonstrated marked

SIX teeth with a total of six roots were In this group. One root was tilled short of the apical foramen. with debris packed between the end of the filling and the apical foramen. No bacteria were evident in the debris or periapical tissue. The periapical area had a granuloma with early cystic transformation manifesting a marked proliferation of cell rests which formed anastomosing strands of epithelium (Fig. I) Two specimens were filled even with rhe apical foramina. One of these showed evidence of over-

for 90 days and

Response of periapical

pathosis

to endodontic

treatmrnt

549

Fig. 1. Photomicrographof the periapical region of a tooth 15 days after endodontic treatment. The canal was infected for 90 days before treatment. The fill did not extend into the apical portion of the canal. A periapical granuloma with early cystic transformation is evident. Circular anastomosing strandsof epithelium are apparent with central lumen formation. (Hematoxylin and eosin stain. Original magnification, X35.)

Fig. 2. Photomicrographof the periapical region of a root 15 days after endodontic treatment. The canal was infected for 90 days before treatment. New bone formation and fibroblastic activity mark the onset of healing at this early posttreatment period. Foci of inflammatory cells are evident and are associatedwith debris and particles of sealerthat were pushed from the canal into the periapical tissues. (Hematoxylin and eosin stain. Original magnification, X 35J

instrumentation with some particles of sealer and necrotic debris in the periapical tissue which were associated with an inflammatory infiltrate composed of lymphocytes, plasma cells, and macrophages. There was evidence that healing was underway with definite fibroblastic and osteoblastic activity (Fig. 2). The other root filling was poorly condensed, with necrotic debris and bacteria present in the apical canal. The periapical area showed a granuloma. Three apices had overextended but poorly condensed fillings, with much necrotic debris between the fillings and canal walls. Two of the three apices had granulomas demonstrating early cystic transformation. The third apex showed a periapical granuloma.

There was a slight inflammatory infiltrate associated with particles of extruded sealer or debris in the apical foramen area (Fig. 3). A small granuloma was present at the apex of one canal with a short fill. Bacteria and necrotic debris were present in the apical portion of this canal. Two roots were filled even with the apical foramina, and both showed evidence of healing (Fig. 3). However, there was an inflammatory infiltrate associated with necrotic debris and particles of sealer that were extruded into the periapical tissues. Four roots demonstrated an overextension of the gutta-percha fill. Two of these demonstrated healing with an attempt at encapsulation of the overextended gutta-percha and sealer (Fig. 5). The other two roots with overextended fillings were from the same lower molar. Each of these roots had a granuloma abscess at the apices; bacteria were present in the apical third of the canal in each root.

Teeth sealed for 60 days and treated

for 45 days

Ten teeth, including twelve roots, were in this group. Six roots were filled short of the apical foramina, and five of these demonstrated almost complete healing.

Fig. 3. Photomlcrograph of the apical region of ;i canal 45 clay, after treatment. The canal wa+, Infected for hO days bcfore treatment. Inflammation is onI> at the apical foramen III association uith debns in the apical portion of the canal Active osteoblasts and new bone formation indicate healing. (Hematoxylin and eosin stain. Original magnification. ~35. j

Teeth sealed for 30 days and treated Ten teeth. for

30 days

including

and treated

Four roots were

filled

of these had necrotic tissues.

strands

bacteria fillings

present

debris with

pushed early

three

granulomas

(Fig.

6). Two

in the

periaptcal

tissue.

contaminated

extruded

sealer

for

remaining

75 days.

foramina.

One

into the periapical

cystic

canals

with

and the apical

here

endodontically

The other

associated

epithelial

rootx.

short of the apical

A granuloma

was present. were

twelve

for 75 days

with

transformation short

containing

fillings isolated

of these specimens

necrotic

debris

between

had the

Of the eight overfilled two lower molars. One

cases. four were the roots ot molar had a granuloma with

early cystic transformation associated with one root and a granuloma abscess associated with the other apex. Bacteria

were demonstrable

in the necrotic

apical third of the canal between canal wall in each root. The other of healing

at one apex

two apices

loma

and the other

cystic

transformation.

debris

in the

the filling and the molar had evidence

and a granuloma

abscess

other apex. The latter showed bacteria present apical portion of the canal. Two single-rooted with overextended fillings had healing evident

at the in the teeth in the

Intlammatlon necrotic

assoclatetl

debris

in this categor! had a small

Seven teeth. year after

Including

habing

jcven

filled

short

with 7)

the

01’ the

on<> had a granuwith

carI>

for 60 days and roots.

been contaminated

were

iFis.

granuloma

Teeth sealed with contaminants treated for 1 year

of these roots

foramina.

with and

\jcrc

treated

I’or 60 days.

of the apical

tar I Five

foramina.

Debris was present in all cases between the tills and the apical foramina. Three of these had almost complete healing with a few chronic inflammatory cells ad,jacent to the apical foramina only; no inflammation was C‘VIdent in the periapical tissues. The other two short tills were associated with a granuloma and ;I pranuloma abscess. Each of thcsc teeth had bacteria 111the necrotic debris In the apical canals. Two teeth had ovttroxtended tills. There w’as fibrou\ encapsulation of the ovt’rcxtended infiltrate

gutta-percha (Fig.

8).

with

a \light

chronic

Intlammatorq

Response of periapical pathosis to endodontic treatment

Volume 47

551

Number6

Fig. 5. Apical region of a canal 4.5 days after treatment. The canal was infected for 60 days before treatment. Healing is evident with an attempt at encapsulation of the extended fill and sealer. Note associated foci of inflammatory cells. (Hematoxylin and eosin stain. Original magnification, X3.5.)

Control teeth sealed with contaminants

for 105 days

Four roots were not treated endodontically but remained infected for 105 days. All four were associated with granuloma abscess formation (Fig. 9). Bacteria were numerous in all four root canals down to the apical foramina. Control teeth sealed with contaminants

for 440 days

Two lower molars were left untreated for 440 days. Three roots had bacteria present in the canals and in the periapical tissue near the apical foramina. These three roots were associated with large granuloma abscesses. The fourth root was associated with a large abscess. Bacteria

were present throughout

the root canal to the

apical foramen (Fig. 10). DISCUSSION

The reactions of the periapical tissues of monkeys to root canal treatment were studied histologically in thirty-three teeth, including thirty-seven apices, at various intervals from 15 days to 365 days. The response to treatment was found to be influenced by the extent of

Fig. 6. Apical region of a canal 75 days after treatment. The

canal was infected for 30 days before treatment. The filling was poorly condensed, and a small periapical granuloma is evident. Brown and Brenn stain showed that bacteria were

present in the necrotic debris in the canal. (Hematoxylin and eosin stain. Original magnification, X35.) the root canal filling, the time lapse between treatment and death, and the presence or absence of bacteria in the apical portion of the root canal. Those cases in which gutta-percha and sealer were confined to the canal elicited the most favorable response. Periapical inflammation was milder, and evidence of healing was apparent earlier. Seltzer and associates” in a study of monkey teeth, also found that tissue reactions following instrumentation short of the apex were milder than those reactions that followed instrumentation beyond the apex. Ingle’ and Strindberg7 found a high percent of successful endodontic results in human patients when there was a slight underfilling of the canal. However, Nygaard-&tbyR claimed that optimum results were obtained with instrumentation beyond the apex. When sealer and/or necrotic debris from the root canal was present in the periapical tissues, healing appeared to be somewhat hindered. These foreign materials elicited an inflammatory response of plasma cells, lymphocytes, macrophages, and occasional foreignbody giant cells. Polymorphonuclear leukocytes were

Fig. 7. Apical region of a canal 75 days after treatment. T’hc canal was infected for 30 dayx before treatment. Healing ib apparent. with inflammation associatedonly with extended sealer and debris. (Hematoxylin and eosin stain. Original magnification. X3S.r sparse or absent. The presence of macrophages and multinucleated giant cells suggested that an attempt was being made to remove the foreign material from the periapical tissues. The presence of lymphocytes and plasma cells associated with sealer and/or debris may indicate the presence of a local immune reaction. In spite of the foci of inflammation associated with debris and /or sealer in periapical tissues. healing was evident and was manifested by fibroblastic and osteoblastic activity at the periapex. Not only did the length of the canal instrumentation and till prove to be important, but the diameter of the canal preparation had to be large enough to remove the tissue from the apical third of the root canal. When the filling did not obturate the apical third of the canal and infected tissue remained lateral to the sealing material. healing did not ensue. This emphasizes the importance of properly preparing the apical canal and condensing the fill material. Furthermore, the space between the fill and the root canal may have allowed fluids to stagnate. with a subsequent degradation which could cause the periapical inflammation to persist. Difficulty in obturating the apical portion of the canal in this study seemed

Fig. 8. Apical region 01.a canal I year at’tcr trcatmellt. I tic canal was infected for 60 days before trentmt’nt. Hcal~ng I\ complete. There is slight overextension of the gutta-percha with encapsulation and very slight inflammation adjacent to the o\t‘rextension. (Hematoxylin and eo\in \tain. Oriylnal Magnification. 7.3.5 / to be due to the ribbon-shaped morphology of root canals in monkeys. As expected, the length of time following treattnent influenced the microscopic picture. In the 15da> treatment specimens, the balance was shifted in favor of the local tissues, but only slight evidence of healing was observable. In the as-day treatment specimens. the healing process was well underway in all treated hpcc imens except those with bacteria demon~truble In the apical third of the root canal. The periapiccs of the 75 day treatment specimens showed various responhc\ Those fills which were well condensed, whether slightI> overextended or underextended. demonstrated c~\‘Idence of healing. Poorly condensed fills. whether lony or short, did not display healing. None of the roots V.ith bacteria demonstrable in the apical third of the canal showed a tendency toward healing. In the I-year animal, the periapical tissues were aimost normal in the slightly underextended fills. In the slightly overextended fills, healing lagged somewhat behind but was definitely evident.

Fig. 9. Apical region of a control canal infected for 105days. Granuloma abscessand root resorption are evident. (Hematoxylin and eo\in stain. Original magnification. X35.)

Fig. 10. Heavy bacterial infection in a control canal contaminated for 440 days. (Brown and Brenn stain. 0rig)nal magnification. X250.)

Although a negative culture was obtained in all cases before tilling of the canals, twelve of thirty-seven roots in bacteria were demonstrable in the apical third of the canals. This may demonstrate the ineffectiveness of our culturing technique to assess the presence or absence of bacteria in the root canal. This is due partially to our inability to reach the apical canal for a culture sample and partially to the inability of our media to grow aerobic and anaerobic microorganisms. Eleven of twelve canals in which bacteria were demonstrable were associated with either a granuloma, a granuloma abscess. or a granuloma showing cystic transformation. In the one case in which healing was evident relatively few bacteria were demonstrable in the necrotic debris in the apical canal. The fill was dense in this instance. Although it is not possible to determine the viability of these bacteria, their presence appeared to indicate a negative factor in the healing response. This negative factor may be due to direct insult. bacterial breakdown products, or specific bacterial antigens. Bacteria were not demonstrable in the periapical tissues of any treated specimens. All eight control canals were heavily infected. In two of these cases, bacteria were demonstrable in the periodontal tissue

immediately adjacent to the apical foramen but not deep in the periapical lesion or in the bone. This is in agreement with the findings of Langeland, Block, and Grossman ,!I When the radiographic appearance of the periapex at the time of treatment was compared to the radiograph at death, twenty-five lesions showed a decrease in size. Eleven of these areas were diagnosed histologically as granulomas, granuloma abscesses, or granulomas with early cystic transformation. Although there was apparent radiographic evidence of healing, the histologic appearance was that of persistent inflammation. Three periapical areas showed no radiographic evidence of pathosis initially or were diagnosed at death as periapical granulomas. One lesion that showed an increase in size radiographically showed a predominance of fibrous healing histologically. These findings indicate that radiographic assessment of the histologic situation at the periapex should never be considered quantitatively precise, regardless of the effort that is extended to standardize angulation, film-target distance, and film development. Other investigators agree that there is little correlation between the radiographic and histologic diagnoses of periapical lesions.rO

SUMMARY

Periapical lesions were induced in thirty-seven teeth of four male monkeys by exposing the pulp of the experimental teeth to the oral flora for 1 week; the teeth were then closed with zinc phosphate cement to enhance development of the lesions. A series of radiographs was taken of each animal before the lesions were induced and at subsequent stages of treatment and follow-up. Four infected teeth were not treated endodontically and served as controls. The monkeys were injected with an aqueous solution of Procion Brilliant Red H-XBS each time root canal fillings were completed and 6 months after treatment was completed in the one animal that had a l-year follow-up. The root canals were treated according to conventional endodontic principles. A negative culture was obtained in all cases before the root canals were filled with gutta-percha. Following the animals’ death ISdays, 45 days. 75 days, and 365 days after completion of endodontic therapy, semiserial block sections of the teeth and their supporting tissues were prepared. Every fourth slide was stained with hematoxylin and eosin. Unstained sections were examined with fluorescent microscopy for Procion labeling. Selected slides were stained with Brown and Brenn stain for bacteria. The response to treatment was found to be influenced by the apical extent of the root canal filling. the time lapse between treatment and death. and the presence of bacteria in the apical portion of the root canal. Those cases in which gutta-percha and sealer were confined to the root canal elicited the most favorable response. When sealer and/or necrotic debris from the root canal was present in the periapical tissues, healing appeared to be underway but was hindered. The length of time following treatment influenced the microscopic picture. In the 15day specimens the balance was shifted in favor of the local tissues. but only slight evidence of healing wah noted. In the 3S-and 75da> specimens with well-condensed fills. whether slightly overextended or underextended, there was evidence of healing. Poor]? condensed tills did not display healing. In the I-year animal. the periapical

tissues were almost normal in the underextended tills. In the slightly overextended fills. healing lagged behind but was definitely evident. Although negative cultures were obtained in all cases before the canals were filled. twelve of thirty-seven roots had bacteria demonstrable in the apical third ol the canal. Eleven of the twelve canals in which bacteria were apparent did not show healing but were associated with either a granuloma, a granuloma abscess. or a granuloma showing cystic transformation. Bacteria were not demonstrable in the periapical tissues of an) treated specimens. Little correlation was found betw’een the radiographic and the histologic diagnoses of the condition ot the periapical tissues. REFERENCES Grossman. I. I.. Endodontic Practice. cd 7. Philadelphia, 1970. Lea & Febtger. Ingle. J. I.: Endodontics, ed. 2. Yea Yorh. 1976, Lea & Feblger. Seltz.er. S.: Endodontology: Biologtc Conslderatlons in l-& odontics. New York. 1971. McGraw-Hill Book Cornpan\ Healey. H.: Endodontics, St. Louis, 1960. The C. V. Mo\b) Company. Seltzer. S.. Soltanoff, W.. Sinai. I.. and Smith. 1. Biologic Aqxcts of Endodontics. IV. Periapical Tissue Reactions t(’ Root-Filled Teeth Where Canals Had Been Instrumented Short of Their Apices. ORAL SURG. 2S: 724. 1969. Ingle. J.: Root Canal Obturation. J Am Dent. A\wc. 5.3: .I-:. 1956. Strmdberg. L A The Dependenw of the Result> ot Pulp Thcrspy on Certain Factors: An Analytic Stud) Based on Radiographic and Clinical Follou-up Enammationx. Acta Odont<>l Stand. 14: Supp. 21. 1956. Nygaard-ostby. B.. l-he Role ot Blood Cl11t5 In l:nd~ldontic Therapy, Acta Odontol. Stand. 19: 323. 1961 Langeland. K.. Block. R. M.. and Grossman. I I ,A HI\topathologic and Histobactertologic Study of 35 Perlaplcal Endodontic Surgical Specimens. .I. Endod. 3: 8. 1977 Grossman. 1. I.. and Rossman. S. R.: Corrclatlon of’ Cl~mcai Diagnosis and Histopathologic Findings in Teeth With Apical Radiolucent Areas. ORAL SVRG. 17: 36X. 1964 Hcprr11,

rcyuc’.trc

1,.

Dr. Samuel S Patterwn Department of Endodontw Indiana University School of Dentlatr) lIZI W. Michigan St, Indianapolis. Ind 46202