Efficacy of Non-instrumentation Endodontic Treatment With an Antibiotic Mix Paste in Primary Molars: a Multicenter Randomized Clinical Trial With 2 Years of Follow-up

Most techniques for endodontic treatment in primary teeth require instrumentation of root canals and filling with an absorbable paste. This filling material could be pastes based on zinc oxide and eugenol, calcium hydroxide or iodoform, or filling materials composed by mixture of some of these components. This method, however, requires a long clinical time, which can be a challenge in the Pediatric Dentistry clinical practice. Therefore, some alternative techniques in which non-instrumentation is necessary have been purposed.

The non-instrumentation technique most used in Brazil is a technique previously described, in 1964. This method involves the access to pulp chamber and removal of necrotic tissue with irrigation. After that, with no instrumentation of the root canals, a medicament containing zinc oxide and eugenol and two antibiotics, chloramphenicol and tetracycline, is placed in the entrance of the canals, and the restoration of the teeth is performed. Although the non-instrumentation methods for endodontic treatment of primary teeth are attractive and demand a short clinical time, strong evidence from well-conducted clinical trial lacks.

Therefore, this four-center parallel-arms non-inferiority randomized clinical trial was designed to evaluate the efficacy of a non-instrumentation of root canals and use of a paste containing antibiotics (chloramphenicol and tetracycline) and zinc oxide and eugenol (CTZ) technique for endodontic treatment of primary molars. The hypothesis is that the efficacy of non-instrumentation treatment is non-inferior to the standard treatment involving manual instrumentation of root canals and filling with zinc oxide and eugenol (ZOE) paste after 24 months of follow-up. Children who look for dental treatment in one of four participating centers and who have at least one primary molar requiring endodontic treatment will be eligible. If the child has more than one molar with pulp involvement, the included tooth will be determined by chance. Other teeth will be treated, but they will not be included in the study. The participating centers are the dental schools of Santa Catarina Federal University, University of Sao Paulo, Rio de Janeiro State University and Iguaçu University. Included children will be randomly allocated to one of the two groups (allocation ratio of 1:1): CTZ group (non-instrumentation technique) and ZOE group (standard treatment).

Randomization list will be generated in an appropriate website (www.sealedenvelopes.com), in permuted blocks (2, 4, and 8 samples) and stratified for the center. The sequence will be enclosed in individual opaque envelopes separated by the stratum. The disclosure of the allocated group will occur when the children will be seated in the dental chair, after the anesthesia, rubber dam isolation and opening of the tooth included for that child. Than the included tooth will be allocated to the CTZ group or to ZOE group. After the treatment, children will be followed-up for 6, 12, 18 and 24 months. Evidence of treatment failure in any period will be recorded, and the teeth will be extracted.

The primary endpoint will be the success of the dental treatment after 24 months of follow-up (teeth with no evidence of failure in all follow-ups). The sample size calculation was estimated based on a success rate of 92% obtained in pulpectomies using ZOE from a previous systematic review (Coll et al., 2020), a non-inferiority limit of 15%, a significance level of 5% and statistical power of 90%. It was added 20% to this number to contemplate possible drop-outs and 60% due to the multi-center design. The anticipated sample size was 218 teeth (109 per group), divided among the centers.