Manual and Rotatory Instrumentation Pulpectomy in Primary Mandibular Molars

Introduction

Dental caries is a prevalent chronic disease, affecting 60-90% of school-age children in industrialized countries; although in the last four decades the prevalence and severity of caries lesions have decreased, it is still a frequent disease for this age group. The American Dental Association (ADA) classifies dental caries by clinical presentation as initial, moderate, and severe; furthermore, the ADA classifies the disease using the international caries detection and diagnosis system (ICDAS II; International Caries Detection and Assessment System II) and by a radiographic presentation of the proximal faces based on the E0-E2, D1-D3 notation system. Within the non-vital pulp treatments, pulpectomy is indicated in temporary teeth; pulpectomy is a conventional endodontic treatment for teeth with exposed, infected, and/or necrotic tissue to eliminate pulp and periradicular infection.

In a recent systematic review that compared three different strategies for the management of deep caries lesions (i.e. complete caries removal, selective caries removal, and step caries removal), Aïem and colleagues (2020) report an increased restoration failure risk when selective removal is used compared to complete removal of caries. In a study where French dentists were surveyed on the management of deep caries lesions in primary dentition, the majority of respondents mentioned performing deep caries removal in a single step. Endodontic procedures in the pediatric population can assist to keep temporary teeth until exfoliation, which is a key principle of pediatric dentistry. Vital pulp and non-vital pulp treatments are employed in the treatment of severe lesions and deep caries; meanwhile, pulpectomy is a treatment largely used in the primary dentition. In pulp therapy, a pulpotomy is performed by removing the pulp from the chamber, while in a pulpectomy, all the tissue from both the chamber and the root canals is removed.

There are two parameters used to determine root canal treatment success: 1) the morphology and shaping of the canal; and 2) the duct cleanliness or the adequate level of disinfection provided by the type and quantity of intra-canal irrigation (e.g. chlorhexidine, sodium hypochlorite, citric acid, profuse irrigation). A pulpectomy is the technique of choice for primary dentition in deep carious lesions with pulp necrosis since pulpectomy has a higher success rate than pulpotomy. While the time for access to the root canal is less with the use of rotary instrumentation systems compared to a manual technique, manual techniques have the same efficacy as rotary systems in root canal cleaning procedures. Rotary systems have greater clinical success compared to manual techniques, in addition to having advantages in instrumentation time, canal shaping, reduction in working time, better cooperation and less patient fatigue, improvement in the conicity of the root canal, and promoting a higher quality of obturation. In a recent meta-analysis, Manchanda and colleagues (2020) conclude that rotary instrumentation has similar clinical and radiographic success rates to manual techniques in primary dentition; additionally, rotatory techniques show lower levels of postoperative pain and less instrumentation time. In the only study in the Mexican population that compared a rotary system (i.e. K3) against a manual technique (i.e. K-file) it was found that the instrumentation and obturation time was shorter, being a promising technique in children.

Given the limited comparative literature about rotatory techniques used in pulpectomy treatment, it is necessary to conduct clinical trials that compare both manual and rotatory techniques in first dentition treatment. So far, studies have been carried out comparing rotary systems designed for adults in the pediatric population. Recently, interest to validate and implement safe and effective protocols for the management of rotary systems in primary dentition has emerged in pediatric dentistry. Below is a protocol designed to investigate the advantages and disadvantages associated with the use of rotary systems designed for our population of interest.

Study design

Population: patients with pulpectomy indication according to the criteria mentioned by Kuo and colleagues (2006).

Place: Pediatric Dentistry Clinic, Universidad Latinoamericana, Campus Valle.

Time frame: January 2021 - December 2021

Sampling technique: convenience sampling with group randomization.

Study groups: 4 (n= 100 teeth)

1. Patients who are treated with a manual pulpectomy and a K-file system.
2. Patients who are treated with a manual pulpectomy and a Kedo-SH system.
3. Patients who are treated with a rotatory technique pulpectomy and a K3 system.
4. Patients who are treated with a rotatory technique pulpectomy and a Kedo-S system.

PICOS framework

P: pediatric population

I: manual system pulpectomy

C: rotary system pulpectomy

O: instrumentation and obturation time, filling quality by radiographic evaluation, postoperative pain levels at 12hr and 24hr, frequency of complications (e.g. fistulas, thinning of the mesiodistal walls, periapical or furcation radiolucency) after a 3-, 6-, 9-, and 12-month follow-up.

S: a randomized controlled trial

Research question

Are there differences between the use of a manual system compared to a rotary system in the pediatric population?

Main objective

Compare the performance between a manual technique and a rotatory technique during biomechanical work.

Particular objectives

1. Compare the instrumentation (i.e. during biomechanical work) and filling time between a manual technique and a rotatory technique.
2. Compare the filling quality by radiographic evaluation between a manual technique and a rotatory technique at the end of the procedure.
3. Compare postoperative pain levels using the visual analog scale at 12 and 24 hours.
4. Compare the frequency of complications (e.g. fistulas, thinning of the mesiodistal walls, periapical or furcation radiolucency) after a 3-, 6-, 9-, and 12-month follow-up between the two techniques.

Hypotheses

H1: The rotatory techniques will take less instrumentation and obturation time than the manual techniques.

H1: The quality of the obturation in the rotatory technique will be reported radiographically more frequently as optimal than the manual technique.

H1: The pain levels reported by patients will be lower in the rotatory technique than in the manual technique.

H1: The rotatory technique will have a lower frequency of complications such as fistulas, thinning of the mesiodistal walls, periapical or furcation radiolucency at each time point compared to the manual technique.

Statistical analysis

Descriptive statistics will be performed on all variables. Statistical analysis will be performed using SPSS 25 (SPSS Inc., Chicago, IL). All variables will be examined to determine the existence of outliers and whether or not they meet the Gaussian distribution assumption; furthermore, Gaussian distribution will be determined with the Shapiro-Wilk test and by visualizing the data through histograms and Q-Q graphs. The demographic and clinical variables will be summarized in proportions and percentages. Nominal variables will be evaluated with Chi-square tests to assess differences between groups. Categorical variables will be evaluated to determine statistical inferences with the Mann-Whitney test. Continuous variables will be assessed for statistical inferences using t-tests and Levene's test to assess variance equality. Statistical significance will be set at p= 0.05 and a Bonferroni correction will be made for multiple comparisons.

Sample size

The sample size necessary to detect statistically significant differences was calculated by taking the following parameters; α = 0.05 and statistical power of 0.8 (i.e. 1-β). For the calculation of the sample size, the time of instrumentation was used as a measure of clinical outcome. The sample was calculated based on the article by Ochoa-Romero and colleagues (2011) where instrumentation time was used as the primary outcome. The sample calculator used can be found on the website: https://clincalc.com/stats/samplesize.aspx. The calculator designed for two independent groups for continuous variables was selected, using the mean for each group (i.e. group 1: rotatory technique 1.7 minutes ± 0.5; group 2: manual technique 2.5 minutes ± 0.8) taking into account an enrollment 1:1 ratio for this study. The total sample size was 24 teeth (i.e. at least 6 teeth per group to find statistically significant differences in instrumentation time).