Paper 211 MS International Journal of Paediatric Dentistry 2000; 10: 313±321
Primary molar pulp therapy ± histological evaluation of failure P. J. WATERHOUSE1, J. H. NUNN1, J. M. WHITWORTH2 & J. V. SOAMES3 1
Department of Child Dental Health, 2Department of Restorative Dentistry and Department of Oral Pathology, The School of Dentistry, University of Newcastle upon Tyne, Newcastle upon Tyne, UK 3
Summary. Objectives. Qualitative comparison of the clinical, radiographic and
histological outcomes in a small sample of cariously exposed primary molars, extracted after unsucessful pulp treatment by two vital pulpotomy methods. Subjects and methods. The primary molars were extracted, because of treatment failure, during a longitudinal clinical investigation of the relative efficacy of 20% Buckley's Formocresol versus calcium hydroxide powder as pulp dressings in vital pulp therapy (in press). Fifty-two child patients were sequentially enrolled in the longitudinal clinical investigation, 26 boys and 26 girls. Primary molar teeth requiring vital pulp therapy were randomly allocated to either the formocresol group (F) or the calcium hydroxide group (C). Coronal pulp amputation was prescribed only in teeth with vital, cariouslyexposed pulp tissue. All cases were reviewed using predefined clinical and radiological criteria. Seventy-nine cariously-exposed primary molars required vital pulp therapy. Forty-four teeth were included in group F and 35 in group C. Five per cent (n = 2) of teeth in group F and 11 per cent of teeth (n = 4) in group C were terminated from the trial due to clinical and/or radiographic failure. Of the six teeth extracted, five were sufficiently intact to be retained for histological evaluation. Results. Post-extraction radiographs taken before specimen preparation showed reactionary dentine barrier (bridge) formation in teeth treated with calcium hydroxide. However, the narrowing of root canals, indicative of appositional reactionary dentine deposition, was seen in both groups (F and C). Histological examination confirmed these findings and revealed that pus cells were evident in all specimens examined. There was also histological evidence of resorption of reactionary dentine within the root canal and that forming the calcified barrier (dentine bridge). Conclusion. The clinical and radiographic outcomes for the five teeth correlate well with the reported findings from decalcified histological section. Although numbers are small, the histological findings may indicate possible reasons for treatment failure. There are few reports of this sort in the literature of this under-researched treatment modality.
Introduction A recent review of Buckley's Formocresol used as a primary molar pulpotomy medicament [1] showed Correspondence: Mrs Paula Jane Waterhouse, Department of Child Dental Health, The School of Dentistry, Framlington Place, Newcastle upon Tyne, NE2 4BW, UK. E-mail: p.j.waterhouse@ncl.ac.uk
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the agent to have a long history of clinical success. The use of a one-®fth dilution of this medicament appeared to be equally e ective [2]. However, formocresol contains formaldehyde, and as a consequence concern has been expressed over its use in dentistrry because of its carcinogenic and mutagenic potential [3±7]. As a consequence, other medicaments and techniques have been evaluated [8±14].
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The success of vital pulp therapy techniques in cariously exposed primary molar teeth is thought to be dependent upon the technique employed, the in¯ammatory status of the coronal and radicular pulp tissue, the type of pulp therapy agent used, the period of observation and the criteria used to diagnose success. One of the outcomes felt to indicate a successful pulpotomy is the presence of a `dentine bridge' at the site of pulp amputation. This phenomenon was thought to indicate healing of the pulp tissue and to be promoted by the application of calcium hydroxide [15]. However, this supposition is not without controversy as it is known that pulpal obliteration/dentine bridge formation results from the deposition of reactionary dentine also termed `irritation dentine'. It has been postulated that healing of reversibly in¯amed pulps requires an active wound dressing such as calcium hydroxide [16]. Studies have indicated that an exposed pulp possesses inherent ability to produce dentine in response to operative procedures or trauma, irrespective of the agent applied to the amputation site [17]. Infection control appears to be a key issue, calci®c barrier formation has also occurred after formocresol pulpotomies in primates [18]. Calcium hydroxide as a pulpotomy medicament is not without disadvantage. It has not been advocated as a primary molar pulp therapy agent because of the unwanted sequela of internal resorption consequent on the production of an extrapulpal blood clot during treatment. Histological studies have shown that internal resorption can also occur when formocresol is used [19]. The primary aim of this investigation was to compare qualitatively the clinical, radiographic and histological features of primary molar teeth terminated from a longitudinal clinical investigation because of clinical and/or radiographic signs and symptoms of treatment failure. The secondary aim was to evaluate the histological ®ndings, particularly with respect to the presence and site of reactionary dentine and the occurrence of internal resorption in secondary and reactionary dentine. Materials and methods Fifty-two child patients were sequentially enrolled in the clinical investigation, 26 males and 26 females with an age range of 3.3±12.5 years. Primary molar teeth requiring vital pulp therapy were randomly
allocated to either the formocresol group (F) or the calcium hydroxide group (C). The total number of teeth treated was 84. Topical anaesthesia was achieved with 20% benzocaine gel (Xylonor1 gel; Septodont Incorporate, Newcastle, Delaware, USA) before 2% lignocaine with 1 : 80 000 adrenaline local anaesthetic solution was administered (Astra Pharmaceuticals Ltd, Kings Langley, UK). Isolation was achieved with rubber dam or cotton wool rolls and saliva ejection. Cavity outline was established at high speed with round and ®ssure diamond burs. Caries was removed with slow-speed round steel blurs. Pulpal exposure to bacteria from the carious lesion was deemed present if pulpal haemorrhage could be seen, access to pulp chamber could be detected with a probe, or if the root of the pulp chamber was su ciently thin to see pulpal tissue. If pulpal exposure was con®rmed, the roof of the pulp chamber was removed with a sterile, non-end cutting low-speed bur (Batt cone bur ISO 016, Maille er Instruments, Ballaigues, Switzerland). Sterile, physiological saline was delivered by syringe and needle to wash away dentine debris. Coronal pulp amputation was achieved with small and medium slow-speed sterile round burs, taking care to avoid cutting the pulp chamber ¯oor. The remaining pulp tissue was excavated with sterile excavators and the chamber irrigated with sterile, physiological saline. Haemorrhage was controlled using sterile pledgets of dry cotton wool applied with pressure. Group F. A sterile pledget of cotton wool was placed in 20% solution of Buckley's Formocresol and immediately blotted dry on sterile gauze. The pledget was placed directly over the radicular pulp stumps and covered with dry cotton wool, to avoid seepage of the agent from the cavity. The cotton wool was removed after 5 min. If pulpal haemorrhage occurred after placement of the medicament (`post-placement' haemorrhage), this was gently blotted with a sterile cotton wool pledget and its occurrence recorded. Group C. Calcium hydroxide powder was delivered to the pulp chamber using a small, sterile endodontic amalgam carrier (`PD' Messing root canal gun1; Produites Dentaires SA., Vevey, Switzerland). The powder was gently packed over the pulp stumps with an amalgam condenser and
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small pledgets of cotton wool. Excess agent was meticulously removed from cavity walls with an excavator. If post-placement pulpal haemorrhage occurred, seen as a `halo' of blood around the powder, this was gently blotted with a sterile cotton wool pledget and its occurrence recorded. Groups F and C. A lining of zinc oxide-eugenol cement (Kalzinol1; DeTrey, Konstanz, Germany) was placed, to seal the coronal pulp chamber, and allowed to set. The tooth was restored with amalgam (Dispersalloy1; Dentsply International Incoroporate, Millford, DE, USA), glass-ionomer cement (Ketac-Fil1 Aplicap1 ESPE; Dental-Medezin GmbH and Company K.G., Seefeld, Germany) or compomer (Dyract1; DeTrey, Konstanz, Germany). A pre-formed stainless steel primary molar crown (Ion1; 3M Dental Products, Loughborough, Leicestershire, UK) was placed if indicated. Occlusal contacts were checked and adjusted where necessary. Details of each pulpotomy were recorded together with details of ®ndings at subsequent clinical and radiographic reviews. Assessment Treated teeth were reviewed clinically at 1 month, 6 months, 12 months post-treatment and then annually for the presence or absence of the following: Clinical
. Symptoms from the treated tooth reported by the
child or parent; spontaneous pain, or pain initiated by stimuli; . signs of a defective restoration or recurrent caries; . signs of mobility, sinus formation, tenderness to percussion, soft tissue swelling. Treated teeth were reviewed radiographically on the day of treatment, at 6 months, 12 months and annually for the presence or absence of the following: Radiographic
. Defective restoration or recurrent caries; . periradicular pathology such as periapical, or furcal radiolucency; . internal resorption, replacement resorption, intra-canal calci®cations, physiological resorption.
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Extraction If treatment failed, clinical and radiographic reasons were documented. Treatment failure was said to have occurred if the test tooth showed either clinical signs or symptoms of infection with or without radiographic signs of infection. If tooth extraction was required and local anaesthesia acceptable to the child, topical anaesthesia was achieved with 20% benzocaine gel before 2% lignocaine with 1 : 80 000 adrenaline local anaesthetic soluttion was administered. One tooth was removed under general anaesthesia. All extractions were undertaken with standard primary molar extraction forceps and/or elevators. Post-extraction Following extraction, the tooth was immediately preserved in 10% bu ered formalin. The time lapsed since pulpotomy was recorded. Extracted teeth were stored until the censor date of the clinical investigation (December 1997). One tooth was fractured at the time of extraction and was discarded. The remaining ®ve teeth were photographed and examined radiographically before histological preparation. Histological preparation Those teeth with su cient tissue remaining to permit slide preparation were forwarded for routine decalci®cation and histological reporting. Sections were stained using haematoxylin and eosin. The sections were evaluated by an oral pathologist and a report provided. The interface between the medicament and radicular pulp tissue was examined. Results The treatment phase of the trial began in October 1994 and ended in December 1996. The censor date for the last review was December 1997. Six teeth were extracted because of signs and/or symptoms of failed pulp therapy. The overall mean time elapsed between treatment and extraction was 11 months (range 6±16 months). Post-extraction radiographs These were undertaken for ®ve teeth and the ®ndings relevant to the formation of reactionary
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dentine are shown in Table 1. Cases 1 and 4, from Group F show no radiographic evidence of dentine bridge formation. However, four of the ®ve canals from the aforementioned cases showed evidence of appositional dentine formation. Cases 2, 3 and 5, from Group C, displayed calci®ed barriers indicative of dentine bridges in four of the six canals. The remaining two canals showed evidence of appositional dentine deposition. Histology Histological ®ndings are shown in Figures 1±4 and outlined in Table 2. These demonstrate that reactionary dentine deposition occurred in all teeth examined. Calci®ed barrier (dentine bridge) formation at the amputation site was seen in three specimens from group C (cases 2, 3 and 5), two of which also showed evidence of dentine apposition on the walls of the root canals. Dentine apposition was seen in a further two specimens without any evidence of bridge formation from group F (cases 1 and 4). In cases 2 and 4 the dentine deposition was complete, suggesting either complete calci®c barrier (case 2, group C) formation or obliteration of the apical pulp by calci®ed repair tissue (case 4, group F). Purulent exudate was identi®ed in all specimens. Speci®c histology notes were made for each specimen and can be seen in the ®nal column of Table 2. The comments associated with cases 1, 4 and 5 indicate possible reasons for failure of the pulp therapy.
Discussion When pulp tissue from primary molar teeth, deemed clinically successful after pulp therapy, was evaluated histologically the number of cases classed as successful, reduced [19,21]. For example, a chronically in¯amed pulp may be symptom free and therefore clinically `successful' until signs of an acute exacerbation occur. For all six primary molar teeth in this study, extraction was undertaken because of signs and symptoms of infection: for example, pain, mobility, swelling or sinus formation. These teeth were clinical failures with or without concomitant radiographic signs of failure. Teeth that were classed as clinically `successful' were not extracted. Although numbers were small, post-extraction radiographs revealed more evidence of root canal calci®cation than that discernible from pre-extraction radiographic examination of the teeth in situ. These calci®cations included calci®ed barrier (den-
Table 1. Types of root canal calcifications seen from postextraction radiographs. Number of roots seen
Dentine bridge
1F
2
✕
2C
2
3C
2
4F
3
✔ 2 canals ✔ 1 canal ✕
5C
2
Case number
✔ 1 canal
Canal obliteration ✔ 2 canals ✕ ✔ 1 canal ✔ 2 canals ✔ 1 canal
Key: Fdenotes tooth from Group F, treated with formocresol and C from Group C, treated with calcium hydroxide. Dentine bridge refers to radiographic evidence of calcification, `complete' or `incomplete', at the site of amputation. Canal obliteration refers to radiographic evidence of narrowing or loss of patency of a root canal.
Fig. 1. Photomicrograph of one root canal from case 3, treated with calcium hydroxide. This tooth was removed because of tenderness on biting. The section shows the presence of reactionary dentine obliterating the canal (A) with pulp tissue apical to the calci®cation (B). Magni®cation 6180.
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Fig. 2. Photomicrograph of one root canal from case 3, treated with calcium hydroxide. This tooth was removed because of tenderness on biting. The section shows a partial reactionary dentine barrier (C). Resorption has occurred within the barrier and at the walls of the canal (D and E). Initially the barrier may have been complete. Purulent exduate and necrotic debris can be seen apical to the barrier. There was an apical abscess associated with this root. Magni®cation 6180.
Fig. 3. Photomicrograph of one root canal from case 4, treated wth a one-®fth solution of Buckley's Formocresol. The tooth was removed because of sinus formation and furcation radiolucency. Root canal obliteration by appositional reactionary dentine can be seen (F). There is evidence of residual pulp tissue, with localised pulp abscess within the pulp chamber (G). Internal resorption of the pulp chamber is evident (H). Magni®cation 6180.
tine bridge) formation, appositional deposition and pulp obliteration by calci®ed repair tissue. The superimposition of bone and soft-tissue may have obscured the calci®cations in vivo, thus making the perception of pulpal calci®cation from pre-extraction radiographs more di cult. One would expect more calci®cation to be evident within the root systems of successfully treated teeth, because in this study, calci®ed barrier (dentine bridge) formation was detected subjacent to the pulp dressing, from in vivo radiographic examination, in less than 25% of cases. It was seen more frequently in teeth from Group C. Post-extraction radiographs and histological sections demonstrated that bridge and appositional dentine were deposited in teeth classed as clinical failures. Amorphous, reactionary dentine was identi®ed in the presence of pus cells, chronic apical abscess, and furcation resorption.
Howship's lacunae were seen at the peripheries of both calci®ed barrier and appositional dentine, indicating that pathological resorption had occurred within reactionary dentine prior to extraction. The resorption was not discernible radiographically either in vivo or post-extraction. Radiographic evidence of intra-pulpal calci®cation from teeth in which treatment failed supports the hypothesis that reactionary dentine formation is a sign or consequence of attempted repair processes within the pulp tissue. Perhaps after an initial attempt by the pulp tissue to `wall-o ' insult, the protective or reactive process failed, leading to clinical failure. In two of the teeth examined histologically, the report stated that dentine barrier (bridge) formation was seen to be complete or that a canal was obliterated by reactionary dentine for that plane
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foci of soft tissue within calcification, chronic abscess associated with second root
✔
✔ periapical radiolucency
2
1
4F
5C
sinus
2 3C
TTP
furcation radiolucency
✔ 2 canals ✔ partial 1 canal TTP 2 2C
gingival swelling
✔ 1 canal
✔ complete in 1 canal 1 canal apical 2/3 ✔
✔
✔ 2 canals
✔ 2 canals
✔
✔ coronal 1/3
✔ ✔
✔
✔
✔ ✔ ✔ partial
furcation radiolucency furcation radiolucency recurrent caries sinus 2 1F
Radiographic outcome Clinical outcome Number of roots Case number
of section. These statements require careful interpretation: the slide represents a single plane of section and not a three-dimensional representation. Histological sections would not allow unequivocal diagnosis of complete barrier formation because serial sections were not used. In addition, studies using scanning electron microscopy to evaluate dentine bridge morphology have con®rmed the irregular nature of seemingly complete areas if dentine [17,22]. It appears that dentine deposition, be it barrier formation, appositional or pulp obliteration from within the pulp tissue, may be described as `sieve-like'. This has important clinical relevance. First, one may initially review a pulpotomized primary tooth and ®nd the patient symptom-free and the tooth exhibiting radiographic signs of pulpal calci®cation. However at a later review, the same tooth ± initially thought to be responding
Table 2. Histological features described in pathology reports.
Fig. 4. Photomicrograph of one root canal from case 5, treated with calcium hydroxide. This tooth was removed because of gingival swelling and periapical radiolucency. Reactionary dentine barrier formation has occurred (J) together with appositional depostion (K). Resorption lacunae are present within both these areas (arrows). Purulent exudate (L). Magni®cation 6180.
baceria seen in canal pus apical to dentine bridge resorption in bridge suggests initially complete localized pulp abscess in pulp chamber with residual pulp tissue
P. J. Waterhouse et al. Findings in histology report ÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐ Resorptn Inter-radicular Apical Dentine Dentine Resorptn n bridge apposit of bridge of walls Pus cells resorptn resorpta Other comments
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to treatment ± may be painful with associated signs of failed pulp therapy despite evidence of pulp calci®cation. The consequence of coronal leakage as a possible reason for failure of pulp therapy is important when the true nature of the morphology of the reactionary dentine is appreciated. Bacteria and food particles may gain access to the radicular pulp by a poorly sealed coronal restoration. The sieve-like nature of the dentine will subsequently allow passage of these agents to the radicular pulp. Second, if the radicular pump is in¯amed at the time of coronal pulp amputation, although some pulp tissue may react by producing calci®cation, elsewhere in the pulp in¯ammation may persist, initiating odontoclastic activity and subsequent resorption of reactionary dentine. This would lead to symptoms of irreversible pulpitis. The histology reports o er explanations as to why treatment failed. All sections showed evidence of purulent exudate, indicating possible microbial contamination, perhaps from poor coronal seal. A section of one tooth (case 1), showed dental plaque within a root canal, therefore the absence of a coronal seal, with subsequent bacterial contamination, was a likely cause for failure. This tooth was restored using a preformed stainless steel crown, which was di cult to ®t and subsequently decemented twice. A second tooth (case 4) had a localised pulp abscess in the pulp chamber within residual pulp tissue; inadequate amputation of the coronal pulp allowed chronic in¯ammation to persist, or compromised the seal of the coronal restoration. Case 5 may have been a poor candidate for pulp therapy, in that there was evidence suggesting that the radicular pulp tissue was irreversibly in¯amed. This may be detected empirically by prolonged bleeding from the radicular pulp stumps after coronal amputation. Case 5 showed a bleeding time of 14 min (time taken from removal of roof of pulp chamber to cessation of bleeding from amputated pulp stumps). The bleeding times recorded for the other four cases ranged between 5 and 6 min. Advocates for the use of calcium hydroxide suggest that the sequela of internal resorption can be prevented by the direct contact of calcium hydroxide with cut pulp tissue [16]. This can be technically di cult to achieve and is biologically suspect, because an incision into vital tissue produces both haemorrhage and exudation.
319
Conclusion The clinical and radiographic outcomes for the ®ve teeth correlate well with the reported ®ndings from histological sections and may indicate possible reasons for treatment failure. Radiographic evidence of reactionary dentine should not be an indicator of successful outcome of pulp therapy, but viewed as a reaction by traumatised pulp tissue that may serve to act as a partial barrier. Success may be more dependent upon adequate coronal seal and correct choice of teeth as candidates for vital pulp therapy. To this end, the following recommendations are suggested:
. Radiographic monitoring is essential after pulp therapy.
. During coronal pulp amputation, if haemostasis
of the radicular pulp stumps cannot be achieved, the tooth should be treated by pulp extirpation or extraction. . Restorations should be well placed and monitored for signs of inadequate seal. Acknowledgements This work was supported by grants from the Shirley Glasstone-Hughes Memorial Prize, the British Dental Association and the European Society of Endodontology. The authors wish to thank Mrs J. Howarth, Department of Photographic Illustration Newcastle Dental Hospital for preparation of photographic material. ReÂsumeÂ. Objectifs. Comparaison qualitative des reÂsultats cliniques, radiographiques et histologiques au sein d'un eÂchantillon reÂduit de molaires temporaires exposeÂes aÁ la carie, extraites aÁ la suite de leur traitement sans succeÁs par deux meÂthodes de pulpotomie vitale. Sujets et MeÂthodes. Les molaires temporaires ont eÂte extraites, suite aÁ un eÂchec theÂrapeutique, au cours d'une eÂtude clinique longitudinale sur l'e cacite respective de formocreÂsol de Buckley aÁ 20% et de l'hydroxyde de calcium en poudre, utiliseÂs comme pansements pulpaires lors d'un traitement pulpaire vital (sous presse). Cinquante deux enfants ont eÂte inclus dans l'eÂtude clinique longitudinale, 26 garcËons et 26 ®lles. Les molaires temporaires neÂcessitant une theÂrapeutique pulpaire vitale ont eÂte reÂparties au hasard dans le
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groupe formocreÂsol (F) ou hydroxyde de calcium (C). L'amputation pulpaire coronaire a eÂte reÂserveÂe aux dents vitales avec exposition pulpaire due aÁ la carie. Tous les cas ont eÂte revus selon des criteÁres cliniques et radiographiques preÂde®nis. Soixante dix-neuf molaires temporaires carieÂes ont neÂcessite une theÂrapeutique pulpaire vitale. Quarante quatre dents ont eÂte incluses dans le groupe F et 35 dans le groupe C. Cinq pour cent (n=2) des dents du groupe F et 11 pour cent des dents (n=4) du groupe C ont eÂte retireÂes de l'eÂtude apreÁs signe radiographique et/ou clinique d'eÂchec. Cinq des six dents extraites eÂtaient su samment intactes pour eÃtre retenues en vue de l'eÂtude histologique. ReÂsultats. Il n'y avait pas de di eÂrence signi®cative entre les enfants transplanteÂs et les enfants teÂmoins, concernant les caries, la plaque ou la gingivite. Les enfants avec transplantation cardiaque ou cúurpoumon avaient signi®cativement un plus grand nombre de deÂfauts de l'eÂmail et une plusgrandeprofondeur de sillon que les enfants teÂmoins. Les enfants du groupe transplantation cardiaque avaient signi®cativement plus de saignement gingival. Il y avait peu de di eÂrence concernant les connaissances dentaires et les pratiques reconnues entre le groupe transplant et le groupe teÂmoin. Zusammenfassung. Ziele. Ein qualiftativer Vergleich von Klinischen, roÈntgologischen und histologischen Resultate eines kleines Muster von Milchnolaren, deren Pulpen durch Karies eroÈ net waren und extrahlert wurden, dies nach misslungener vitaler Pulpaamputationen mit 2 Methoden. Subjekte und Methode. Die Milchmolaren wurden extrahiert wegen gescheiterte Wurzelbehandlung waÈhrend einer logitudinalen Studie zur Beurteilung der Buckleys Formokresol Methode versus der Kalzium Hydroxid PuiverMethode, als WundverbaÈnde.52 Kinder, 26 Knaben 26 MaÈdchen nahmen teil an dieser Studie. Milchmolaren welche eine Pulpamputation noÈtig hatten wurden wilkuÈrlich der Formokressol (F) oder der Kalzium Hydroxid (C) Gruppe zugeteilt. Die FaÈlle wurden nach voraus bestimmten klinischen und roÈntgologischen Kriterien beurteilt. Von 79 Milchmoiaren wurden 44 ZaÈhne der F Gruppe und 55 der C Gruppe zugeteilt. Bei 5% (n=2) der Gruppe F und 11% (n=4) der Gruppe C scheiterte die Therapie. Von diesen 6 extrahierten ZaÈhne weren 5 geeignet fuÈr histologische Beurteilung.
Resumen. Objetivos. ComparacioÂn cualitativa de los resultados clõ nicos, radiogra®cos e histoloÂgicos en una muestra pequenÄa de molares temporales expuestos a caries, extraõ dos despueÂs de un tratamiento pulpar no exitoso seguÂn dos meÂtodos de pulpotomõ a. Sujetos y meÂtodos. Los molares temporales se extrajeron debido a fallo en el tratamiento, durante una investigacioÂn clõ nica longitudinal sobre e®cacia relativa entre el formocresol de Buckley al 20% y el hidroÂxido de calcio en polvo como recubrimiento pulpar en tratamientos de pulpa vital. En la investigacioÂn clõ nica longitudinal se registraron de forma secuencial cincuentaidos ninÄos, 26 varones y 26 ninÄas. Los molares temporales que requerõ an tratamiento pulpar se distribuyeron aleatoriamente, en el grupo de formocresol (F) o en el grupo de hidroÂxido de calcio (C). La amputacioÂn de la pulpa coronaria se prescribio soÂlo en los dientes con tejido pulpar vital expuesto por caries. Todos los casos fueron revisados usando criterios radioloÂgicos y clõ nicos prede®nidos. Setentainueve molares temporales expuestos por caries requirieron tratamiento pulpar vital. Cuarentaicuatro dientes se incluyeron en el grupo F y 35 en el grupo C. El 5% (n=2) de los dientes en el grupo F y el 11% de los dientes (n=4) en el grupo C terminaron para el estudio debido a fallo clõ nico y/o radiogra®co. De los 6 dientes extraõ dos, cinco estaban su®cientemente intactos para ser utilizados en el examen histoloÂgico. References 1 Waterhouse PJ. Formocresol and alternative primary molar pulpotomy medicaments: a review. Endodontics and Dental Traumatology 1995; 11: 157±162. 2 Morawa APS, Stra on LH, Han SS, Corpron RE. Clinical evaluation of pulpotomies using dilute formocresol. ASDC Journal of Dentistry for Children 1975; 42: 360±363. 3 Lewis BB, Chestner SB. Formaldehyde in dentistry: a review of mutagenic and carcinogenic potential. Journal of the American Dental Association 1981; 103: 429±434. 4 's-Gravenmade EJ. Some biochemical considerations of ®xation in endodontics. Journal of Endodontics 1973; 1: 233±237. 5 Pashley ELM, Myers DR, Pashley DH, Whitford GM. 14 Systemic distribution of C-formaldehyde from formocresol-treated pulpotomy sites. Journal of Dental Research 1980; 59: 602±607. 6 Nocentini SM, Moreno G, Coppey J. Survival, DNA synthesis and ribosomal RNA transcription in monkey kidney cells treated by formaldehyde. Mutation Research 1980; 70: 231±240.
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15 Foreman PC, Barnes IE. A review of calcium hydroxide. International Endodontic Journal 1990; 23: 283±297. 16 SchroÈder U. E ect of an extra-pulpal blood clot on healing following experimental pulpotomy and capping with calcium hydroxide. Odontologisk Revy 1973; 24: 257±267. 17 Cox CF, Subay RK, Ostro E, Suzuki S, Suzuki SH. Tunnel defects in dentine bridges: their formation following direct pulp capping. Operative Dentistry 1996; 21: 4±11. 18 RoÈlling I, Melsen B. Dentin formation in formocresol pulpotomized primary monkey teeth studied by tetracyccline and 3H-proline incorporation. Scandinavian Jounal of Dental Research 1979; 87: 403±414. 19 Magnusson BO. Pulpotomy in primary molars: long-term clinical and histological evaluation. International Endodontic Journal 1980; 13: 143±155. 20 Ketley CE, Goodman JR. Formocresol toxicity: is there a suitable alternative for pulpotomy of primary molars? International Journal of Paediatric Dentistry 1991; 2: 67±72. 21 Magnusson BO. Therapeutic pulpotomies in primary molars with the formocresol technique. Acta Odontologia Scandinavia 1977; 36: 157±165. 22 Goldberg F, Massone EJ. Evaluation of the dentine bridge after pulpotomy and calcium hydroxide dressing. Journal of Endodontics 1984; 10: 318±320.
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