Primary molar pulp therapy--histological evaluation of failure.
OBJECTIVE
Qualitative comparison of the clinical, radiographic and histological outcomes in a small sample of cariously exposed primary molars, extracted after unsuccessful pulp treatment by two vital pulpotomy methods.


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, cariously-exposed 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).


CONCLUSIONS
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.
Waterhouse
P J
PJ
Department of Child Dental Health, School of Dentistry, University of Newcastle upon Tyne, Newcastle upon Tyne NE2 4BW, UK. p.j.waterhouse@ncl.ac.uk
Nunn
J H
JH
Whitworth
J M
JM
Soames
J V
JV
D002126:Calcium Hydroxide / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D003731:Dental Caries / Q000000981:diagnostic imaging / Q000473:pathology / Q000628:therapy*; D003784:Dental Pulp Calcification / Q000000981:diagnostic imaging / Q000473:pathology; D003785:Dental Pulp Capping; D003789:Dental Pulp Exposure / Q000000981:diagnostic imaging / Q000473:pathology / Q000628:therapy; D003809:Dentin, Secondary / Q000000981:diagnostic imaging / Q000473:pathology; D005260:Female; D005566:Formocresols / Q000627:therapeutic use; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008963:Molar / Q000000981:diagnostic imaging / Q000473:pathology*; D011672:Pulpotomy / Q000379:methods*; D011859:Radiography; D012388:Root Canal Irrigants / Q000627:therapeutic use; D013492:Suppuration; D014094:Tooth, Deciduous / Q000000981:diagnostic imaging / Q000473:pathology*; D017211:Treatment Failure; D015035:Zinc Oxide-Eugenol Cement
D005566:Formocresols; D012388:Root Canal Irrigants; D015035:Zinc Oxide-Eugenol Cement; C031025:formocresol; D002126:Calcium Hydroxide