Pédiatrie Dentistry

The treatment of nonvital immature teeth with calcium hydroxide-sterilewater paste: Two case reports

Gamze Erdogan, DDS, PhD*

Abstract Death of the dental pulp before completion of rool development results in a toolhwith an open apex. During endodontic treatment, the open apex makes obturationdifficult, because there is no apical stop against which iheJUling can be packed andcondensed. For many years, open apices have been treated by root canal fillingsor by periapical surgery wilh or without a reverse seat. Currently. Ihe conservativeapproach is preferred over surgical management, to avoid the physical andpsychological trauma ofsttrger}- to a young patient. Two patients were treated bycalcium hydroxide-sterile water paste to promote the apexification of the nonvitalteeth with an Incompletely formed apex. Nortnal endodontic preparation of thecanal had been carried out in the Immature tooth. Radiologie examination after6 to 9 months showed that the apex of the maxillary incisors was completed bynewly formed tisstie. (Quintessence Int 1997;28:681-686.)

Clinical relevance

Calcium hydroxide might be a good choice forinducing apical closure in young patients because ofits antibacterial and calcification-inducing proper-ties.

Introduction

The teeth most commonly traumatized in children arethe maxillary central incisors. The peak incidence fortrauma occurs between 8 and 10 years of age, when theroots of the incisors are developing. If. during thistime, the pulp becomes nonvital as a consequence ofthe traumatic episode, no ftirther development andmaturation of the root will take place, resulting in anonvital incisor with an open apex and incompleteroot development.'

' Chief, Dental Pédiatrie Clinics of Marly and Villars-s-Olâne.Fribourg,Switzerland.

Repritit requests: Dr Gamze Erdogan. 3, tue du Leman, 1301 Geneva,Swit¿er!and, Fax: 41-22-738-7544.

Apexification is a method of inducing apical closurethrough the formation of mineralized tissue in theapical pulp region of a non-vital tooth with anincompletely formed root and an open apex.- Variousclinical techniques have been aimed at inducingapexificalion in immature permanent teeth with necro-tic pulps.- Inducing apical closure by the formation ofan apical stop, generally with calcium hydroxide,[Ca(OH,)] is one of the most widely used methods oftreating a tooth that has a necrotic pulp and an openapex.-"-"

Calcium hydroxide (Caixyl) was introduced byHermann in the 1920s for endodontic treatment. In1930, Hermann'- advocated using Caixyl (OCODirmslein) for pulp capping, pulpotomy. pulpectomy,and treatment of infected canals. In 1938. Teuscherand Zander" atid Zander''' introdttced calcium hydrox-ide in the United States as a pulpotomy agent. Theinduction technique was first addressed in the UnitedStates in 1964 with separate presentations by Kaiser(Scientific session, Washington DC. 17 Apr 1964) andFrank (Table clinic, Washington DC. 19 Apr 1964) atthe 21st annual meeting of the American Associationof Endotdoctists. It was presented in the literature in1966 and popularized as the Frank technique.^^

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The use of calcium hydroxide paste to promote theformation of a calcific apical barrier prior to theplacement of a gulta-percha root filling has becomewell accepted.** In 1972, Cvek" reported periapicalhealing and closure ofthe immature apical foramen byhard tissue in 90% of nonvital permanent incisorstreated with calcium hydroxide. When Andreasen'^reviewed the literature, he found that barrier formationoccurred in 74% to 94% of teeth treated with calciumhydroxide. Ghose et al'*' reported that apical closureoccurred in 96% of nonvital immature incisor teeth.

In 1988. Mackie and coworkers' reported a tech-nique using calcium hydroxide paste, which alsoproduced apical barrier formation in 96% of teethtreated. Meanwhile, Yates'^ and KJeier and Barr.'̂using various calcium hydroxide pastes, reported100% success in achieving apical barrier formation.Treatment was regarded as successful if hard tissue hadformed and closed the root canal apically and provideda base for a later permanent root filling.'' Apicalclosure that was observed after treatment in teeth inwhich the development of the root had ceased wasdescribed as a hard tissue barrier, varying in radio-graphic density, position in the canal, and the time itrequired to form.'''

Steiner and Vim Hassel-" have found Ihe formationof cementlike hard tissue after treatment of artificiallyinfected monkey teeth with calcium hydroxide mixedwith camphorated monochlorophenol. The formationof such hard tissue is believed to occur only in theabsence of microorganisms.-' -- Heithersay-' exam-ined the newly formed apex histoiogically and foundthat it consists mainly of irregular dentin. He theorizedthat the alkalinity ofthe material may have acted as abuffer to acidic inflammatory reactions. Accordirtg toKlein and coworkers.^ the histologie finding of newbone and cementum in the apical area is evidence ofsuccessHil treatment, but the mechanism of apicalclosure is still in question. Frank-'' postulated thatHenwig's sheath may play a role in root apexformation once the infection has subsided. Seltzer-^has found that, after deposition of root dentin.Hertwig"s sheath disintegrales in a coronal directionfollowing the ingrowth ofthe connective tissue ofthedental sac. When the root sheath begins to disinte-grate, cells ofthe connective tissue differentiate intocementoblasts. and cementum is deposited on thedentin. Stanley^ suggests that if the root has notcompleted its formation, in some cases, the cells ofthedental sac surrounding the wide-opened apex retainthe genetic code that predisposes them to diflerentiateinto cementoblasts.

Tronstad and coworkers"*" have shown thai the pHof untreated teeth with pulpal necrosis is between 6.0and 7,4, Teeth with complete root formation have a pHbetween 7.4 and 9.6 in the dentin away from the pulpand from 8.0 to 11.1 in the dentin next to the pulp.These investigators maintain that Ca( OH )-, neutralizesacids produced by osteoclasts.-'' Anthony and co-workers'* concluded that the alkaline environmentwould favor the formation of calcium phosphate[Ca(PO) I complexes, which would, in turn, serve asa stimulus for further calcification. Studies by Abiko-'suggest that the presence of calcium ion may activateadenosine triphosphate activity, which in turn mayaccelerate the mineralization of hard tissue such asdentin or bone, Javelet and coworkers-" also indicatedthat the alkalinity is a significant feature in the abilityof Ca(OH)., to induce hard tissue formation. Vaes'̂and Bourne-̂ " contended that CaiOH), creates anunfavorable environineni for osteoclastic activity orcan activate alkaline phosphatase enzymes,

Binnie and Rowe" compared periapical healing ofexperimentally infeeted dogs' teeth after filling theroot canals with Grossman's sealer. Calxyl. andCa(OH ), mixed with water. The Ca(OH),-waterpastedid equally well in teeth that were closed and in teeththat were left open to the oral environment.

In previous investigations, calcium hydroxide hasbeen mixed with camphorated monochlorophenol.camphorated paracholorophenol, sterile water.'- Rin-ger's solution, methyl cellulose, or iodoform''chloro-thymonal.-''' To provide opacity and thus aid in radio-graphic interpretation of the extent of the calciumhydroxide paste in the root canal system, bariumsulfate powder is added to the paste. The purpose ofthe present article is to describe results in two patientswho were treated with calcium hydroxide mixed withdistilled water.

Case reports

Case I

The maxillary left central incisor ofa 7-year-old girlhad suffered a traumatic incident 5 months previouslyThis tooth had been fractured without any obviouspulpal exposure, and the fractured surface area hadbeen covered with Dyca! (DeTrey Dentsply-Kon-stanz) and a basket crown by the general dentist towhom she had been referred. She complained thatintermittent aching had been present in the tooth forIhe previous month. Pulp testing confirmed that themaxillar>' right incisor was nonvital. and a radiographrevealed an incompletely formed apex (Fig la).

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Fig 1a The Ieit central incisor had ahistory of trauma that had resulted in anecrotic pulp. The fractured area hadbeen covered with Dycal and a basketcrown 5 monfhs previously. The canalwas debrided and obturated with cal-cium hycfroxide-sterile water paste.(arrows) Immature apical formation.

Fig fb Apical development has con-tinued after the pulpecfomy procedurewith calcium hydroxide (6-month inter-val).

During the patient's first appointment, a rubber damwas placed to isolate the involved tooth, the basketcrown was removed, and the access opening into thepulp chamber was prepared. The access, through thelingtial surface of the incisor, was accomplished byremoving all impinging tooth structure at the rootcanal orifice. After the root canal was debridedbiomechanically, it was irrigated with sodium hypo-ehlorite and dried with an inverted coarse paper point,

A ratio of one part barium sulfate to eight partscalcium hydroxide was mixed with distilled water, andthe paste was placed into the root canal. The canal wasfilled with the aid ofa lentulo needle, and the paste waspressed toward the apex with cotton wool pellets ( Figlb). The paste filling in the canal was then coveredwith IRM cement (DeTrey Dentsply),

Monthly appointments revealed no clinical symp-toms, and the radiograph taken after 6 monthsrevealed the closure of the apex. The final apicalclosure permitted a fitted gutta-percha point withetidomethasone to fili the canal adequately (Fig lc).

Fig 1c Adequate penapical closurehas taken place to allow permanentendodonfic therapy

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Fig 2a The maxillary right incisor had a history of traumaresulting in a necrotic pulp. As a result, the apex isincompletely formed

Figs 2b and 2c Nine months after the übturation v./\'\i calcium hydroxide paste, apicalclosure is adequate to permit root canal obturation wifh gutta-percha and endamethasone.

Case 2

An 8-year-old girl was referred for therapy on hermaxillary right central incisor, which had been frac-tured in an accident 4 months previously. The toothgave no response to vitality and thermal lests. Theradiographie examination revealed an incompletelyformed apex (Fig 2a),

Access to the root canal was accomplished byremoving all carious tissue, and therapy was initiatedwith biomechanical instrumentation ofthe root canal.After irrigation of the canal, the canal space wasobturated with a paste of calcium hydroxide.

Nine months after the first visit, apical closure wasadequate to allow permanent root catiai ñlling wilhgutta-percha and endamethasone (Figs 2b and 2c),

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Discussion

Necrosis or the dental pulp before completion ofroot(development results in a lootli with an open apex.^ Thetreatment of nonvitiil teeth in children can present theclinician with a challenge because ofthe immature rootformation.^ According to Frank,^•" successful endo-dontic treatment requires that the apex ofthe treatedtooth be completely and densely sealed with root canalfilling material.

Currently there are at least five methods of treating atooth thai has a necrotic pulp and an open apex.According to Morse and coworkers,- these methodsare 11) filling the root canal wilh the large end of agutta-percha cone or customized gutta-percha conesand a sealer; (2) filling the root canal well short oftheapex (before the walls have divei^ed) wilh gutta-percha and sealer or zinc oxide-eugenol alone: (3)filling the root canal with gutta-percha and sealer aswell as possible and then performing periapical surgerywith or without a reverse amalgam seal; (4) inducingapical closure by the formation of an apical stop(calcium hydroxide is generally used) against which apermanent root canal filling can subsequently beinserted; and (5) placing a biologically acceptablesubstance in the apical portion of the root canal(dentinai chips or tricalcium phosphate has been used )thus forming an apical barrier; which is followed byfilling ofthe root canal with gutta-percha sealer.

Techniques that induce apical closure have beendeveloped to provide a calcule barrier at the end oftheroot, to act as a stop against which a gutta-percha rootfilling can be condensed. The most frequently usedprocedure appears tobeapexification with CaiOH),."Although calcium hydroxide possesses many proper-ties that infiuence induction of apical closure, apexifi-cation has also been successful without the use of anymedicament in some cases.- Experimental endodonticwork carried out by Torneck and Smith'" on partiallydeveloped incisor teeth in young monkeys showedhistologically the process of root development thatoccurred after pulpotomies and pulpectomies. Theaccess cavities were sealed with amalgam, but rootfillings were not inserted. The conclusion reached wasthat root formation may continue after such treatmentwithout remedial therapy, but growth is retarded^andirregular.'̂ According to Morse and coworkers,- thecommon aspects of all apexification procedures aredebridement. cleaning, and reduction of the root canalspace with a material, thus leading to a favorableperiapicai environment.

The two cases presented are examples of closure of

immature root apices subsequent to treatment withcalcium hydroxide mixed with sterile water. Thismaterial was left in the root canal in two patients untiladequate apical closure occurred through continuedapical development. The process of apical develop-ment continued to its potential after routine endodon-tic therapy with gutta-percha and cndamethasone. Atthe end ofthe treatment, the apices were closed anddid not allow excess gutta-percha to be expressedperiapically. In these two patients, no periapicalpathosis or root résorption was recorded.

Cvek'' suggested that the effect ofthis material mightbe explained by the assumption that calcium hydroxideacts as a long-lasting antibacterial agenl. He alsoindicated that once the infection is eliminated andperiapical tissues reorganize, it is possible for calculedevelopment to take place.-"'

The mechanism of action of this paste may bepartially dependent on its high pH; thus, one ofthemost important reasons for mixing calcium hydroxidewith a physiologic vehicle such as sterile water is itsexpected alkaline pH.

Conclusion

The literature is replete with articles offering additionalmodes of therapy for a nonvital tooth with an openapex. Two case reports have shown thai the techniqueof apical closure with calcium hydroxide-sterile waterpaste proved highly successful. Results related closelyto data obtained in the past. This method is easy tocarry out and is well accepted by patients. For thoseclinical situations in which apexification or barrierformation is necessary, calcium hydroxide-sterile waterpaste might be a good choice, especially in childrenwho are anxious about surgical procedures.

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