Dental Traumatology 2005; 21: 141–145 All rights reserved
Copyright Blackwell Munksgaard 2005 DENTAL TRAUMATOLOGY
Study of calcium hydroxide apexification in 26 young permanent incisors Dominguez Reyes A, Mun˜oz Mun˜oz L, Aznar Martı´n T. Study of calcium hydroxide apexification in 26 young permanent incisors. DentTraumatol2005;21:141–145. BlackwellMunksgaard,2005. Abstract Abstra ct – This This st stud udyy was ca carr rrie ied d ou outt in order order to ob obse serv rvee th thee effectiveness effectiv eness of apexification apexification in young permanent incisors. The sample sam ple compri comprised sed 26 young young perman permanent ent inciso incisors rs with necroti necroticc pulp and open apices. The time taken to obtain apical closure, its form and size were analysed in order to find out if closure was influenced by existing pathology or size of apex. The treated trea ted teeth teeth were compare compared d with their their corres correspon pondin ding g contracontralateral teeth. The test of McNemar and anova was used and a result of P 0.0 0.05 5 was consid considered ered signifi significan cant. t. Teeth Teeth with with pretreat pret reatmen mentt apical apical shapes shapes that that were were converg convergent ent or parall parallel el all resulted resulte d in physiologica physiologicall apical shapes after treatment. treatment. Eight teeth had divergent apical shapes before treatment. Of these, one had a physio physiolog logica icall sha shape, pe, five ended ended with with rounded rounded apices and two teeth had straight apices post-treatment. Apical closure was obtained in 100% of the cases studied, of these 88.4% needed three to four sessions of calcium hydroxide treatment (an average of 3.23 sessions) in order to obtain apical closure, the average time employed employed was 12.19 12.19 months. months. Clinical symptoms symptoms resolved in all teeth that presented with symptoms. Preoperative symptoms did not affect outcome. Pathology of the tooth before treatment does not influence the time needed to obtain apical closure.
˜ ˜ oz ˜ o A. Dominguez Reyes, L. Mun oz Mun oz, z, T. Aznar Martı´´ n School of Dentistry, University of Seville, Seville, Spain
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After traumatic injuries the pulps of young permanent teeth often often necrose necrose.. This This occurs occurs most comcommonly in the permanent maxillary incisors leaving the teeth teeth with with incompl incomplete ete radicul radicular ar develo developme pment nt and open apices. In these cases treatment is aimed at promoting complete apical closure. At a later date a complete filling of the root canal is carried out in order to prevent inflammatory stimulators affecting the periapex. Several different treatments have been described in orde orderr to ac achi hiev evee ap apic ical al clos closur uree (1 (1). ). One One is apex apexific ificat atio ion, n, which which is define defined d as the the in indu ducti ction on of apic apical al clos closure ure in a to toot oth h with with no nonn-vi vita tall pulp. pulp. This Th is in induc ducti tion on is pr prom omot oted ed by stim stimul ulat atin ing g the formati form ation on of mineral mineralize ized d tissue tissue (osteo (osteocem cement) ent) at the the end end of th thee ro root ot (2 (2), ), eith either er wi with th or wi with thou outt radicular growth.
Key words: calcium hydroxide hydroxide apexification; apexification; young permanentt incisors permanen incisors Dr Antonia Dominguez Reyes, C/Alfonso de Cossı´o n 1, 1 A 1, 41004 Sevilla, Spain Tel.: 01134954421932 01134954421932 Fax: 01134954421932 01134954421932 e-mail:
[email protected] Accepted 7 April, 2004
Since its first presentation by Kaiser and Frank in 1964, apexification has been used with great success by many researchers (3–9). It is a treatment that co comp mpli lies es with with the af afor orem ement entio ione ned d ob obje jecti ctive ves: s: it allows apical closure and promotes radicular lengthening if the Hertwig’s epithelial root sheath has not been irreversibly damaged (3). The drawback of this technique is that the time needed for treatment is prolonged. For this reason some authors prefer to carryy out apexificat carr apexification ion in just just one sessi session on (10 (10)) or ob obtu tura rati tion on of the radi radicul cular ar canal canal with with a gutt guttaaperch per cha a foll follow owed ed by apic apicect ectom omyy with with retro retrogr grad adee filling. Many kinds of materials have been used to induce apexifi ape xificati cation on in tee teeth th with with immatu immature re apices: apices: antiantiseptic pastes, antibiotic pastes (11), ceramic tricalcium phosphate, the osteogenic protein-1, mineral
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trioxide aggregate (MTA) (12–14), calcium hydroxide mixed with different substances in solution (3–9), etc. etc.;; howe howeve ver, r, tr trea eatm tmen entt with with ‘pur ‘pure’ e’ calc calciu ium m hydroxide has become the standard. This study was carried out for several reasons: in order to verify the effectiveness of this technique of apexification apexifi cation using calcium hydroxide; hydroxide; to observ observee the length of time time require required d for apical closure; closure; to
with pure, pro-analysis calcium hydroxide powder [Ca(OH)2 ] dissolved in distilled water. In order to facilitate treatment in further sessions a co cotto tton n pelle pellett was was pla placed ced on the ch cham ambe berr flo floor or,, IRM or ionometer was added, and finally the tooth was restored with a permanent material in order to avoid the possibility of leakage. Patien Pat ients ts unde underwen rwentt a cli clinic nical al and rad radiol iologi ogical cal
an anal alys ysee th the e shap shape an and d size size oftooth, th thee ap apex exfinally fo form rmed ed compared with thee contralateral and to find out if the shape of the apex has any bearing on the time taken to achieve apical closure.
check-up every months, unless At they missed their appointment or 3were on holiday. each check-up apical size and shape were measured, and clinical sympto sym ptoms ms obs observ erved. ed. The mat materi erial al used used for filling filling was was repl replace aced d and and th thee techni technique que of apex apexifi ificat catio ion n formerly described was repeated until the existence of a barrier or apical stop was found. When this occurre occ urred d root root filling filling wit with h guttagutta-perc percha ha and sea sealer ler was performed. performed. The shape of the open apices was classified classified before treatmen trea tmentt in the follow following ing way: way: conver convergent gent walls walls (CAW), parallel apical walls (PAW), or blunderbuss (DAW); after treatment as closed form, physiological closure (PC) or similar, round apical closure (RC) and straight bridge (SBC). The apical diameters of
Material and methods
This study involved 19 patients, 14 boys and five girls, between the ages of 6 and 9 years old. They attended our teaching unit of Integrated Paediatric Dentistry at the Dental School between 1995 and 1998. All children who presented with pulp necrosis sis in th thei eirr in inci ciso sors rs were were in incl clude uded d in this this stud study. y. They Th ey were were all all tr trea eated ted by stud student entss from from th thee fin final al year of Dental studies, supervised by a professor. A cl clin inic ical al re reco cord rd was was ta take ken n an and d an exam examin inat atio ion n carried out (inspection, (inspection, palpation, palpation, percuss percussion ion and mobili mob ility) ty).. There There was als also o a radiolo radiologic gical al examin examinaation (periapical (periapical X-rays with positioner) positioner) and direct observa obs ervatio tion n of the pulp pulp space. space. Alth Althoug ough h vitali vitality ty tests tests wer weree also also ca carri rried ed ou out, t, they they ha have ve no nott been been included in this study due to their subjectivity. Out of the the 19 pati patient entss in inclu clude ded d in ou ourr study study one girl girl stopped attending our unit because she moved to another city. Therefore, this study was completed with 18 patients (14 boys and four girls), and 26 teeth tee th were were tre treat ated ed (2 (22 2 centra centrall in incis cisor orss and and fo four ur lateral incisors). These incisors were compared with their healthy contralateral incisor (seven patients/13 teeth).
In this study all cases of pulp necrosis were due to traumatic injuries, with a higher percentage of boys (7 (73. 3.4% 4%)) th than an gi girl rlss (26. (26.3% 3%). ). The The pati patient entss were were trea treated ted unti untill apic apical al cl clos osur uree was was ac achi hiev eved. ed. One One patien pat ientt (5.26% (5.26%)) was excluded excluded fro from m the stu study dy due to missed missed appointments appointments.. Twenty-six Twenty-six incisors incisors were studied and apical closure was 100% successful. At
Al Alll te teet eth h we were re tr trea eate ted d wi with th th thee tech techni niqu quee of apicoformation after local anaesthetic and use of a rubber dam. The chamber ceiling was perforated with wit h a tungsten tungsten 330 high-s high-spee peed d refrige refrigerat rated ed 330 burr.. The remain burr remaining ing corona coronall pulp was remove removed d with a tungsten low-speed round burr and with the help hel p of broach broaches. es. This was followed followed by irriga irrigatio tion n with 5% sodium hypochlorate until the entrance to the canals canals was thorou thoroughl ghlyy visual visualized ized.. In order order to avoid surpassing the apical constriction the length of the root root canal canal was determi determined ned with with high-ca high-calib libre re K-files (numbers 25–30) (conductectomy). When the workin wor king g length length had been ascerta ascertaine ined d the ins instrutrument me ntat atio ion n of th thee cana canals ls wi with th KK-fil files es was was comcommenced. The first used had the same measurement as th that at us used ed for for the meas measur urem emen entt of th thee canal canals; s; larger calibre files were used progressively in order to widen the canal. After each step the canals were flushed with 0.5% sodium hypochlorate, then filled
the first examination eight of these teeth presented no cl clin inic ical al sign signss or symp sympto toms ms (30. (30.8% 8%)) an and d 18 pres present ented ed symp sympto toms ms (69. (69.2% 2%). ). Thes Thesee sign signss and and symptoms were: spontaneous pain 57.7%, provoked pain 11%, fistula 3.8%, slight periodontal widening 19 19.2 .2%, %, apica apicall radi radiol oluce ucency ncy 11 11.5 .5%. %. All All cl clin inic ical al sympto sym ptoms ms disappe disappeare ared d after after tre treatm atment ent (100%, (100%, 26 P < 0.0005) (Table 1). There was no relateeth) ( P tion tionsh ship ip foun found d betw between een ti time me ne neede eded d for for apic apical al closur clo suree and the clinica clinicall sympto symptoms ms prior prior to trea treattment. Thee shape Th shape of th thee apex apex af after ter apexi apexifica ficati tion on was was similar to the physiological shape (73.1%), rounded (19.2%) and straight (7.7%) (Table 2). After taking into account the shape of the apex befo before re tre treat atme ment nt and and th thee shap shapee ob obta tain ined ed af afte terr treatmen trea tmentt the result resultss showed showed that 100% of teeth teeth with open apices and CAW (seven teeth) obtained apic apical al cl clos osure ure which which was was very very simi simila larr to phys phys--
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the treated teeth were compared, whenever possible, with their matching contralateral teeth if these were health hea lthy. y. They They were were measur measured ed with with a milime milimetri trical cal ru rule ler. r. The The stat statis isti tica call te test stss used used were were anova and MacNemar. Results
Study of calcium hydroxide apexification Table 1. Sympt Symptoms oms observe observed d in incisors incisors before and after apexi apexificati fication on Symptoms
Before treatme tment (%) After ter treatment (%)
Without symptoms With symptoms Provoked pain Spontaneous pain Fistula Abscess Mobility Apical image Widening of periodontal ligament
8 18 3 15 1 – – 3 5
(30.8)* (69.2) (11.5) (57.7) (3.8)
(11.5) (19.2)
26 (100)* – – – – – – – –
*P < 0.0005.
Table 3. Apica Apicall diameters diameters before and after apexificati apexification. on. Comparison Comparison with contralateral tooth Apical size (mm) 0.6–1 1.1–2 2.1–3 3.1–4 4.1–5 Average SD
To Toot oth h wi with th ap apex exifi ifica cati tion on BT 1 (3.8) 9 (34.6) 10 (38.43) 5 (19.2) 1 (3.8) 2.69 0.91
AT 4 14 5 3
(15.4) (53.8) (19.2) (11.5)
– 2.17 0.81
Co Cont ntra rala late tera rall to toot oth h BT
AT
2 (15.4) 5 (38.46) 6 (46.15) –
4 (30.8) 9 (69.23) – –
– 2.15 0.75
– 1.62 0.46
Values in parentheses are in percentage. BT, before treatment or during the period of time taken to complete treatment; AT, after treatment or after period of time taken to complete treatment; SD, standard deviation.
Table 2. Apica Apicall shapes before and after treatment treatment Apical shape before apexification Convergent apical walls (CAW) Parallel apical walls (PAW) Divergent apical walls (DAW)
7 (26.9) 11 (42.3) 8 (30.8)
Apical shape after apexification Apic Apical al cl clos osur uree si simi mila larr to ph phys ysio iolo logi gica call clos closur uree (P (PC) C) Rounded apical closure (RC) Straight apical closure (SBC)
19 (73. (73.1) 1) 5 (19.2) 2 (7.7)
Values in parentheses are in percentage.
Table 4. (a) Sessio Sessions ns of calc calcium ium hydroxide hydroxide treatment. treatment. (b) Time taken to obtain apical closure Teeth
Sessions
(a) 2 (7.7) 15 (57.82) 8 (30.8)
1 3 4
1 (3.8) 3.23 Average
5 Time (months)
iological closure. Teeth (100%) with parallel apical walls (11 teeth) obtained apical closure, which was very similar to physiologica physiologicall closure; closure; eight teeth had open ope n apices apices with with diverg divergent ent walls walls before before apicofo apicoforrmation, of which one tooth obtained an apex similar to the physiological shape, five teeth round apices and two teeth straigh straightt apices apices.. On compari comparing ng the apical form of the affected teeth with their matching contralateral teeth it was observed that any healthy apical form gave rise to physiological closure. This is not true of teeth with apicoformation as the wider the apices the greater the different forms of apical P closure ( P 0.000108). The apical diameter of teeth with apicoformation progres pro gressiv sively ely decreas decreased ed in size size during during treatme treatment nt ( P P 0.00 0.0010 1049 49); ); th thee sa same me occu occurr rred ed wi with th th thei eirr healthy contralateral teeth ( P P 0.019295) (Table 3). Teeth Teet h (88.4% (88.4%)) studie studied d obtain obtained ed apical apical closur closuree after after three thr ee to four four se sess ssio ions ns of tr treat eatme ment nt with with ca calci lcium um hydroxide hydrox ide (average 3.25 sessions). sessions). The average time needed need ed for apical apical clo closur suree was 12.19 12.19 mont months hs (Table (Table 4). The following results were observed after taking into account the apical shape before treatment and the time needed to obtain apical closure: one tooth with divergent walls needed five sessions of calcium hy hydro droxi xide; de; ei eigh ghtt teeth teeth ne neede eded d fo four ur se sess ssio ions ns,, of which whi ch thre threee had diverg divergent ent walls walls and five paralle parallell walls; 15 teeth obtained closure with three sessions, four of these teeth had divergent walls, six parallel wall wallss and and fiv fivee co conve nverg rgen entt wall walls. s. There There were were two teeth that needed only one session of treatment and ¼
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(b) 3 (11.5) 2 (7.7) 12 (46.2) 4 (15.4) 4 (15.4) 1 (3.8) Average 12.19
3 10 12 15 16 20
Values in parentheses are in percentage.
both had convergent walls. It can be observed that more sessions of treatment with calcium hydroxide ar aree ne neede eded d for for te teeth eth with with dive diverge rgent nt apica apicall wall wallss ( P P 0.003686). ¼
Discussion
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In this study apical closure was obtained in 100% of teeth teet h trea treated ted and is therefo therefore re in accord accordance ance with results obtained by other authors (between 74 and 100% 100%)) (4–9 (4–9). ). Some Some au auth thor orss cons consid ider er th that at th thee existe exi stence nce of radi radiolu olucent cent apical apical images images lar larger ger tha than n 5 mm mm dela delays ys th thee form format atio ion n of apica apicall barri barriers ers or provokes the formation of irregular apical barriers (7,, 15). (7 15). In th this is stud study, y, th ther eree we were re th thre reee ca case sess of radi radiol oluc ucent ent apic apical al imag images es but but no none ne result resulted ed in delayed or irregular irregular closure. closure. These radiolucencies radiolucencies disa disapp ppea eared red in 10 100% 0% of cas cases es.. Th This is is a high higher er percentage than that found by Heithersay (3), 1975 (9 (95. 5.2 24%) 4%) or by Morfi Morfiss and and Si Sisk skos os (8), (8), 19 1991 91 (89.66%). In the present study, it is considered that
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apic apical al le lesi sion onss were were clos closed ed th thro roug ugh h the the us usee of a precise technique. technique. Ghose states that in 78% of cases apical closure is obtained 5 or 6 months after completing treatment and two sessions of calcium hydroxide treatment are usually required (4). Mackie et al. obtain closure in an av aver erag agee ti time me of 10.3 10.3 mont months hs (1 (16) 6);; Yate Yatess in 9 mon month thss (17) (17);; Cvek Cvek in 18 18.2 .2 mont months hs (1 (15) 5).. Many Many
Although Althou gh the succes successs of apex apexific ificati ation on with with cal cal-cium hydroxide treatment is widely accepted, nowadays the use of other materials such as MTA (12– 14) or pastes pastes contai containin ning g tet tetracy racycli cline ne (11 (11)) is bei being ng studied.
authors consider that the sizeapical of theclosure apical (16, opening before treatment influences 17). The results of this study confirm their findings. No evidenc evi dencee has been found found to prove prove that that sympto symptoms ms such as severe pain or severe infections affect the time time re requ quir ired ed to obta obtain in ap apic ical al clos closur uree (7 (7,, 15), 15), possib pos sibly ly because because no such sympto symptoms ms were were present present in this study. According to Torneck and Smith (18) the reopening of the canal at each session delays apical api cal formati formation. on. However However,, Morfis Morfis and Siskos Siskos (8) and Ghose et al. (4) consider apicoformation to be totall totallyy indepen independent dent to the number number of sessio sessions ns of treatment, or age or sex of the patient. Cvek (15) states that calcium hydroxide treatment should be repeated after 3–4 months because after this time
Apex Apexifica ificatio tion n using usifor ng filling calcium calcium hydrox hydeffective roxide ide as a tem temporary material is an means of induci ind ucing ng api apical cal closur closure. e. Thi Thiss has been achiev achieved ed with an average of 3.23 sessions of treatment over an average period of 12.19 months. There was no evidence to indicate that signs or symptoms prior to tr treat eatme ment nt ha had d any any influe influence nce on th thee ti time me ta take ke to ac achi hiev evee ap apic ical al cl clos osur ure. e. Th Thee most most freq freque uent nt sh shap apee af after ter cl clos osure ure was was physi physiol olog ogic ical al (73. (73.1% 1%), ), follow followed ed by rounde rounded d (19.2% (19.2%)) and str straig aight ht bridge bridge (7.7%). The apical diameter of teeth treated with apicoformation progressively decreased after treatment me nt.. This This fa fact ctor or indi indica cate tess th that at tr trea eatm tmen entt is in inst stru rume ment ntal al in ac achi hiev evin ing g apic apical al cl clos osure ure.. Th Thee more divergent the apical walls the longer it takes
calcium hydroxide appears to lose its antibacterial propert pro perties ies its abilit abilityy to form an apical apical barrier. barrier. A recent study carried out on monkeys (19) seems to indicate that there is no advantage in carrying out a greater number of sessions of apexification before 6 months have passed (20). The apical apical shape shape most most frequent frequently ly observe observed d in this this study study was simila similarr to the physio physiolog logica icall shape shape (73. (73.11 11%) %),, foll follow owed ed by a ro round unded ed fo form rm (1 (19. 9.2% 2%)) an and d a st stra raig ight ht form form,, or br brid idge ge (7 (7.7 .7%) %).. Thes Thesee results differ from those of Morfis, which indicate that that the the str trai aigh ghtt brid bridge ge is the the mos most freq freque uent nt (66.7% (66 .7%), ), and from Ghose Ghose (65% (65% rounded rounded closur closures es and 24% straight straight bridge bridges). s). For some author authorss the shap shapee of th thee apic apical al barri barrier er is co comp mplet letel elyy in inde de-pendent pend ent to the apical apical diamet diameter er before before treatme treatment nt (4 (4,, 8). 8). In thi this stu tudy dy,, the the teet teeth h that that pres presen ente ted d conv conver erge gent nt or pa para rall llel el wa wall llss be befo fore re trea treatm tmen entt ob obta tain ined ed a clos closure ure simi simila larr to the physi physiol olog ogic ical al shap shape. e. Howev However er,, when when the walls walls were were dive diverg rgent ent ther theree was was no re rela lati tion onsh ship ip fo foun und d be betw twee een n th thee shape of the walls and apical closure as rounded, stra straig ight ht or phys physio iolo logi gical cal sh shap apes es were were al alll fo foun und. d. The physiolo physiologic gical al shape was due to the fact that that the the HERS HERS ha had d no nott been been irrev irrever ersi sibl blyy damag damaged ed.. Fo Forr th this is reaso reason n 10 100% 0% of he heal alth thyy co cont ntra rala late tera rall teet teeth h ha had d a phys physio iollog ogic ical al deve develo lopm pmen entt that that showed pointed apices with a small diameter. The apical diameter of teeth with apexification decrea dec rease sess duri during ng tr trea eatm tment ent.. This This is al also so true true of healthy antagonist teeth as the root develops, due to the HERS or to odontogenesis of the apex. In most cases the apical diameter of a treated tooth is larger than its healthy contralateral tooth.
to obtain obtain apical apical closur closure. e.
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Conclusions
References ´ n: Revisio´n 1. Morse DR, O’Larnic O’Larnic J, Yesil Yesilsoy soy C. Apexificacio Apexificacio de la Literatura. Literatura. Quintaess Quintaessence ence (edic. esp.) 1991;4:59– 1991;4:59–70. 70. 2. American American Associatio Association n of Endodo Endodontics. ntics. An annote annoted d glossa glossary ry of terms used in endodontics, 3a edic. J Endod 1981;7:12– 13 (Spec Iss). 3. Heithe Heithersa rsayy GS. Cal Calciu cium m hyd hydrox roxide ide in the treatm treatment ent of pulples pulp lesss teeth teeth wit with h ass associ ociate ated d pat pathol hology ogy.. J Br End Soc 1975;8:74–93. 4. Ghose Ghose LJ, Baghdad Baghdadyy YS, Hik Hikmat mat YM. Ape Apexifi xificat cation ion of immature apices of pulpless permanent anterior teeth with calcium hydroxide. hydroxide. J Endod 1987;13:28 1987;13:285–90. 5–90. 5. Tha¨er M, Mare´ chau chaux x S. Indu Induce ced d ro root ot apex apexifi ifica cati tion on following traumatic injures of the pulp in children: followup study. ASCD J Dent Child 1998;55:190–5. 6. Chawla HS. Apexification: follow-up after > 6 < 12 years. J Indian Soc Pedo Prev Dent 1990;8:38–40. 7. Kleier Kleier DJ, Barr ES. A stu study dy of endodon endodontic tically ally apexified apexified teeth.. Endod Dent Trauma teeth Traumatol tol 1991;7:112–7 1991;7:112–7.. 8. Morfis AS, Siskos G. Apexification with the use of calcium hydr hydrox oxid ide: e: a cl clin inic ical al st stud udy. y. J Cl Clin inic ic Pedi Pediat atrr Dent Dent 1991;16:13–9. 9. Erdogan Erdogan G. The treatme treatment nt of nonvit nonvital al immature teet teeth h with cal calcium cium hyd hydrox roxideide-ste steril rilee wat water er pas paste: te: two cas casee rep report orts. s. Quintessence Int 1997;28:681–6. 10. Harbert H. One-step apexification without calcium hydroxide. J Endod 1996;22:690–2. 11. Das S, Das AK, Murphi RA. Experimental apexigenesis in baboons.. Endod Dent Traumatol 1997;13:31–5. baboons 1997;13:31–5. 12 12.. Shab Shabah ahan ang g S, To Tora rabi bine neja jad d M, Bo Boyn ynee PJ PJ,, Ab Abedi edi HR, HR, McMilla McM illan n P. A com compar parati ative ve stu study dy of roo root-e t-end nd inducti induction on using osteogenic protein-1, calcium hydroxide, and mineral trioxide aggregate in dogs. J Endod 1999;25:1–5. 13. Morse DR, O’Larni O’Larnicc J, Yesil Yesilsoy soy C. Apexificacio Apexificacio ´ n: Revisio´ n de la Literatura. Literatura. Quintess Quintessence ence (edic. esp.) 1991;4:59– 1991;4:59–70. 70. ´ chau 14. Tha¨te terr M, Ma Mare re chaux x S. Ind Induc uced ed ro root ot apex apexifi ifica cati tion on following traumatic injures of the pulp in children: followup study. ASDC J Dent Child 1988;55:190–5.
Study of calcium hydroxide apexification 15. Cvek M. Tre Treatm atment ent of non non-vi -vital tal perman permanent ent inci incisor sor wit with h calcium calciu m hydrox hydroxide. ide. Odont Revy 1972;2 1972;23:27–4 3:27–44. 4. 16. Mackie IC, Bentley EM, Worthington HV. The closure of open apices in non-vital immature incisor teeth. Br Dent J 1988;162:169–73. 17. Yates Yates JA. Bar Barrie rierr for format mation ion tim timee in non non-vi -vital tal teeth teeth wit with h open apices. Int Endod J 1988;21:313–9. 18. Torneck CD, Smith J. Biologic effect of partial and total pulp remov removal. al. Oral Surg 1970;3 1970;30:258– 0:258–63. 63.
19. Cho Chosac sackk A, Sela Sela J, Cleato Cleaton-J n-Jone oness P. A histol histologi ogical cal and quantitativ quanti tativee histo histomorpho morphometri metricc study of apexification apexification of nonvital nonvit al permanent permanent incisors of verve vervett monkey monkeyss after repeated root filling with a calcium hydroxide paste. End Dent Traumatol 1997;13:211–7. 20. Wiscovich Wiscovich JG, Wiscovich GJ. Surgic Surgical al apical repair with SuperSup er-Eba Eba cem cement ent:: a one one-vi -visit sit altern alternati ative ve treatm treatment ent to apexification. J Endod 1995;21:43–6.
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