Endodontics

Healing of large periapical lesions following nonsurgical endodontictherapy: Case reportsAbdulrahman Mohammad Al-Kandari" /Omar Abdulla Al-Quoud-'^ /Johnson David Gnanasckhar*

The cases of two patients with large cystlike periapical lesions are presented. The lesionsformed as a result of trauma to the associated teeth. Following conservative nonsurgical endo-dontic treatment, there was complete resolution ofthe lesions. These results suggest that thelargeness of a periapical lesion does not mandate its surgical removal and that even cystlikeperiapical lesions heal following conservative endodontic therapy.(Quintessence Int 1994:25:115-119.)

Introduction

Trauma to a tooth can damage its pulp even if thecrown and root are not fractured. The pulp may surviveor undergo necrosis, depending on the severity of thetrauma and the type of inflammatory reaction that fol-lows. This reaction may lead to extensive destruction ofthe periapical tissue and an ensuing periapical lesion.

On the basis of histologie findings, chronic periapicallesions of pulpal origin are diagnosed as either periapi-cal granulomas or cysts. Tn the past, large, chronic peri-apical lesions were generally managed by root canaltreatment ofthe involved teeth and surgical excision ofthe periapical lesions. This was particularly true if theperiapical lesion was suspected to be a cyst. Now, be-cause of improvements in conventional endodontictherapy' and a better understanding of the healing po-tential of periapical tissues, fewer patients need peri-apical surgery.

* Special Center Ior the Advancement of Dental Services,PO Bos 27172, 13132 Safal,Kuwaii.

* ' Chief, Dental Center, Sharq, PO Box 5, Safat, Kuwait.

Address ail correspondence to Dr AM Al-Ktindari, PO Box 3234,22033 Salmivah, Kuwait.

Presented here are two cases of periapieal lesions ofthe maxilla that were sueeessfully treated by nonsurgi-cal endodontic therapy. This article suggests that surgi-cal removal of periapical lesions of pulpal origin is notmandatory, and that, irrespective of the size of the le-sion, every effort should be made to treat such lesionsbv conservative means.

Case reports

Case 1

A 15-year-oId boy factured his maxillary central inci-sors in a playground accident 5 years previously. Atthat time he did not seek any treatmetit for the frac-tured teeth. Three days before he reported for treat-ment, he felt a dull pain in the fractuted teeth, and onthe following day the upper hp and right cheek becameswollen and painful.

Exiraoral examination revealed a diffuse swelling onthe right cheek and upper lip. Intraoral examinationshowed discolored, fractured, and tender maxillaryright central and lateral ineisors. The maxillary right ca-nine and premolars were also tender. Periapical radio-graphs showed a large radiolucent lesion with a well-defined margin around the apices of all the tender teethwith the exception of the tnaxillary left central incisor(Figs la and lb). All these teeth were insensitive tothermal and electrical pulp testing. When the root ca-nals of the nonvital teeth were opened, suppurative

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Endodontics

Figs laand Ib Periapieal lesion associated with the maxiliary righl incisors, canines, and premolars.

Figs Icand Id Complete resolution of the lesion 12 months after endodontic therapy.

fluid flowed out. This tluid, which was examined underthe microscope, was found to contain cholesterol crys-tals.

The canals of these teeth were dried and debridedand the access openings were closed with provisionalrestorations. Five days after the root eanals wereopened, the facial swelling completely subsided. Dur-ing the next 3 weeks the patient was examined weekly,and in each visit the canals were debrided and dried.The root canals were obturated with gutta-percha andthe patient was reviewed every 3 months. Twelvemonths after the completion of the root canal therapy,there was complete resolution of the lesion {Figs lc andId).

Case 2

A 25-year-old woman was referred for treatment of agradually increasing swelling in the palate of 4 weeks'duration. Three years previously, in an automobile ac-cident, the patient's upper lip and maxillary incisorswere injured.

Examination revealed a soft, slightly tender swellingin the palate just behind the eentral incisors (Fig 2a).The maxillary incisors were nonvital and periapieal ra-diographs showed two separate, well-defined radiolu-cent lesions around their apices (Fig 2b). When the roofcanals of the nonvital teeth were opened, straw-col-ored fluid flowed out. On compression of the palatal

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Fig 2a Fluctuant sweiiing on the palate Fig 2b Two weii-defined radiolucent iesions associatedwith the apices of the maxiiiary incisors.

Fig 2c Compiete disappearance of the palatal swellingfolloviiing endodontic therapy.

Fig 2d Complete resolution of the radiolucent lesions 15months after endodontic therapy.

swelling, more fluid was expressed through the canals.The fiuid contained cholesterol crystals.

The canals were debrided and dried and the accessopenings were closed with provisional restorations. Aweek later the canals were once again dehrided, dried,and obturated with gutta-percha. At this time the pala-tal swelling had completely subsided: however, thearea was still soft as if there were no bone under thepalatal mucosa. The patient was reviewed every 3months, and, 15 months after completion of endodontictherapy, there was complete resolution of the lesions(Eigs2cand2d).

Discussion

The precise mechanism involved in the formation ofperiapieal lesions is not fully understood. Neverthelessit is generally agreed that if the pulp becomes necrotic,its environment becomes suitable to allow microorgan-isms to multiply and release various toxins into theperiapical tissues, initiating an inflammatory reactionand leading to the formation of a periapical lesion.^^Several studies have been carried out to examine therole of bacteria in the formation of periapical le-sions,^"'" and it has been observed that microorganismsare present in root canals of all teeth associated withperiapicai lésions.^"'The endodontic flora consisted of

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a mixture of tods, cocci, spirochetes, and filamentousforms," However, only a few periapical lesions haveshown the presenee of bacteria within the body of thelesion,^" '̂' One study'" even demonstrated an absenceof bacterial colonies in ail IS periapical lesions exam-ined except for the occasional isolated intracellularbacteria, which the investigators believed to be bacte-ria phagocytosed hy tnacrophagelike cells,

Tn another experiment, periapical lesions were pro-dueed by injeeting sonic extracts of cariogenic bacteriainto pulps,'̂ Consequently, the inflammatory reactionin the periapical lesion may resist the spread of bacteriaby confining them within the root canal, and periapicallesions may be caused not necessarily by microorgan-isms alone, but by other factors such as bacterial prod-ucts and decomposition products of necrotic pulp, Im-munopathologic mechanisms may also play a role inthe initiation of periapical lesions. Tliis may be as-sumed because of the presence of substantial quantitiesofimtnunologicallycotnpetent cells"'"and variousim-munoglobulins" within the lesion.

The histogenesis of periapical cysts is uncertain, butremnants of the epithelial eell rests could possibly bethe source of the epithelium in cyst lining, and variousfactors may contribute to the growth of periapical cysts.The inflammation in the periapical region may stimu-late the proliferation of epithehum, which, by acting asa semipermeable membrane, could draw fluid into thecyst cavity by osmotic pressure,'•* Bone-resorbing fae-tors such as prostoglandins could contribute to furtherexpansion of the eyst,'̂

A comprehensive radiographie and histopathologicevaluation of periapical lesions''' showed that cysts arethe most common periapical lesion. Depending on theradiographie area, diameter or length, from 53% to100% of periapical lesions were cysts. Among periapi-cal lesions with an area greater than 200 mtn', 92% ormore were cysts,'"' Thus, the larger the periapical lesion,the greater the chance for it to be a cyst. In case 1, theradiographie area tjf the periapical lesion was morethan 200 mm-. On the basis of its size, the presence ofcholesterol within the lesion contents, and the well-de-fined radiographie margin, the lesion was probably aperiapicai cyst. Because the treatment consisted of onlyconservative endodontic therapy, histopathologic ex-amination ofthe lesion was not possible.

One concept for the treatment of periapical cysts wasto treat the involved teeth endodontically and surgi-cally excise the cyst hning,'^"' Other reports suggestthat periapical cysts heal spontaneously after conserva-tive endodontie therapy,''""" The exact mechanism by

which periapical cysts heal is not clearly understood.One theory is that as healing takes place njllagen de-posits compress the capillaries supplying the cyst,thereby cutting the blood supply to the epithelial limng.The lining degenerates and is then removed by themacrophages,-' Bhasker"* suggested that, if root canaltherapy is extended beyond the apical foramen, the in-flammatory reaction that develops destroys the cystlining and converts the lesion into a granuloma. Oncethe causative factors are eliminated, the granulomaheals spontaneously.

Healing of periapical lesions following endodontictherapy has been compared to the healing of extractionsockets,---' But, unlike periapical cysts, extractionsockets do not have an epithelial lining that has to beeliminated during healing. Therefore these two lesionsmay not be comparable. Onee the causative factors of aperiapieal lesion are removed, tissue-forming eells re-place lost bone with new bone, while resorbed cemen-tum and dentin are replaced by only cementum. Heal-ing is completed when apical periodontal hgament re-stores its normal architecture,-- A periapical scar,which appears as a residual radioiucent periapical le-sion, may sometimes form. The scar may be ignored if acontinuous apical periodontal hgament of normalthickness is present around the involved teeth.""'

The periapical lesions in both patients were large andafter nonsurgical endodontic therapy the lesions com-pletely resolved without any scar. Mandatory surgicalexcision of cysts greater than 20 mm in diameter, as rec-ommended previously,'"' may not be necessary. Theperiapical tissues have a rich blood supply, lymphaticdrainage, and abundant unditferentiated cells," Allthese structures are involved in the process of inflam-mation and repair. Therefore, because the periapicaltissues have the potential to heal, treatment of periapi-cal lesions should be directed toward only removal ofthe causative factors.

References

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4, Yanagiswa S, Pathologic study of periapicai tesions, Periapiealgranulomas: Clinical, histopathologic and itnmunohistopatho-logic studies. J Oral Pathol 19B0;9:2SS-3ÜO,

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16, Shafer WG, Hme MK, Levy BM, A Testbook of Oral Patholo-gy, ed 3, Philadelphia: Saunders, 1974:451,

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19, Bender rB, Commentary on General Bhaskcr's bypolbesis.Oral Surg 1972;34:469^76.

20, Al-Kandari AM, Al-Ououd OA, Si:khar JDG. Healing of ;ilarge periapical lesion witb conventional treaiment. J KuwaitMed Assoc 1989:23:208-210,

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22, Torabinejad M, Walton RE, Pulp and periapical pathosis. In:Walton RE, Torabinejad M (eds). Principles and Practice of En-dodonljcs, Philadelphia: Saunders, 1989:47-48,

23 Amler MH, The time sequence of lissue regeneration in humanextraction wounds. Oral Surg l%9:27:309-318.

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