Commentary

Recently, there has been a resurgence of research on pulp therapy and pulp medicaments for primary teeth. More and more clinicians wish to avoid the use of formocresol, traditionally used as pulp medicament after pulpotomies. This generally well conducted study, from a respected research group, addressed a clearly focused question to assess clinically and radiographically, the effects of MTA as pulp dressing material following pulpotomy in primary molars compared to Formocresol. Most of the basic principles of clinical prospective research which are desirable, but sadly lacking in many clinical studies, were followed. In addition to including teeth with pulp exposure, teeth asymptomatic teeth with deep carious lesions were also included in the study. This is a strength of the study because it is well known that teeth with deep proximal carious lesions, but no pulp exposure manifest pulp inflammation and should also be included in such studies

Teeth were allocated using coin toss then alternation, but allocation concealment was not applied. Randomisation was done at the tooth level therefore, some children may have had several teeth included with different treatments which is not considered a good practice from a statistical view point but sometimes unavoidable in clinical research where access to a large sample is difficult. After the pulp amputation, for those cases where formocresol was used as a medicament, zinc oxide eugenol (ZOE) was applied on the remaining root canal tissue. It is well known that ZOE itself has an inflammatory effect on the pulp and therefore this is a compounding factor that may affect the treatment outcome. Also, different types of final restorations with different success rates, were placed after the pulp therapy, which may confound the outcomes, though in this article all the failures were observed in the teeth restored with stainless steel crowns.

Success (shedding) or failure rate of both interventions was determined at different follow-up periods according to defined failure criteria. An important outcome that was not assessed in this study is pain. Intention to treat analysis which aims to reduce bias was not performed to include the 2 drop outs from the FC group, but as the number of drop outs was small it should not have influenced the results.

The author's conclude that MTA showed a higher (not statistically significant) long term clinical and radiographic success rate than FC and can be recommended as a replacement for FC. We calculated the 95% CI for the difference in means (Table 1), and observed very wide intervals indicating that more data should be collected before anything definite can be said about the studied parameters. Furthermore, based on the high risk of selection bias, performance bias, confounders and the small number of subjects in this study, the evaluation of long term success rates, costs, risks of harm, and expectations of benefit of MTA compared to FC in primary molar pulpotomies cannot yet be done.

Table 1 Follow-up times and confidence intervals
Full size table