**1. Introduction**

Dental pulp pathologies are often associated with high levels of pain, requiring appropriate local treatment to effectively relieve the patient [1]. While reversible pulpitis is currently managed by vital pulp therapies [2], the treatment of cases diagnosed clinically as irreversible pulpitis is more invasive. It indeed consists in a pulpotomy as emergency procedure [3], followed by complete root canal treatment.

However, a trend towards more conservative strategies has been observed in recent years notably the consideration of pulpotomy as a permanent treatment [4–7]. This evolution is related to improved knowledge in pulp biology and biomaterials. First, histological studies of teeth with pulpitis have highlighted the existence of a gradient of inflammation within the pulp tissue. Healthy pulp tissue was shown to persist underneath areas with high levels of inflammation and sometimes necrosis [8]. Second, tricalcium-silicate cements were reported in histological studies to have the potential of inducing more favorable pulp

**Citation:** Beauquis, J.; Setbon, H.M.; Dassargues, C.; Carsin, P.; Aryanpour, S.; Van Nieuwenhuysen, J.-P.; Leprince, J.G. Short-Term Pain Evolution and Treatment Success of Pulpotomy as Irreversible Pulpitis Permanent Treatment: A Non-Randomized Clinical Study. *J. Clin. Med.* **2022**, *11*, 787. https:// doi.org/10.3390/jcm11030787

Academic Editors: Massimo Amato, Giuseppe Pantaleo and AlfredoIandolo

Received: 12 January 2022 Accepted: 29 January 2022 Published: 31 January 2022

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**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

responses compared to previous calcium-hydroxide pulp capping materials [9]. A trend in favor of these materials was also identified in clinical studies [9,10].

Preserving pulp tissue by pulpotomies followed by pulp capping has several potential benefits. These include preservation of immunocompetent tissue, reduction in the cost of treatment for both the patient and healthcare systems, and reduction in the treatment complexity and duration. It has nevertheless been stated that additional prospective works are necessary to confirm the positive trend in favor of this treatment strategy [2,11]. Moreover, apart from a few studies [12–14], most available works have a rather limited follow-up time ( ≤12 months).

While some works consider pulpotomy as a treatment of teeth with carious exposures [15,16], regardless of clinical symptoms, others, like the present one, focused on the treatment of clinically-diagnosed irreversible pulpitis. In the latter case, it is important to consider not only long-term outcomes, but also the effectiveness of short-term pain relief. For this purpose, numerical rating scales and/or category judgments that are subsequently converted into numerical values have been widely used as they are easily understood by patients and considered suitable for the measurement of dental pain [17–19]. With regard to appropriate times for assessing post-endodontic treatment pain, one day and one week have been described as key time points [20].

Finally, the level of experience of practitioners has, to our knowledge, never been considered in the design of the studies evaluating these procedures. However, as mentioned above, the pulpotomy as permanent treatment is referred to as an easier procedure, therefore potentially accessible to less experienced practitioners, including non-specialists. To take this aspect into account, we designed a non-randomized clinical study to compare the alternative strategy to what is considered as "best available therapy". Two groups were considered: (1) pulpotomy as permanent treatment performed by non-specialist junior practitioners (test group), and (2) root canal treatment performed by specialized endodontists in private practice (control group).

The objective of the present work was to evaluate (1) the short-term evolution of pain and (2) the treatment success of full pulpotomy as permanent treatment of irreversible pulpitis in mature molars.

#### **2. Materials and Methods**

#### *2.1. Patient Selection*

The present prospective study conformed to STROBE guidelines and received approval from the ethics committee of Cliniques universitaires Saint-Luc (Brussels, Belgium) (Reference# 2016/19JAN/016) and was registered at clinicaltrials.gov with registration number NCT02920606.

The study included adult patients with a diagnosis of irreversible pulpitis in mature molar teeth, respecting eligibility criteria for inclusion and exclusion (Table 1). Irreversible pulpitis was defined as spontaneous, radiating pain that lingers after removal of cold stimulus [2]. The inclusion period was from June 2016 to June 2020. An information letter was given to all patients, and informed consent was signed.

In the design of the present study, a difficulty in including patients was expected, due to aspects such as patient motivation (emergency cases) or predictable heterogeneity between groups (population consulting specialists compared to those visiting a dental emergency department). In this context, the present study was initially designed as a pilot study with 50 patients per group as a realistic target.

Systematic forms were used to collect the data for each patient on the day of inclusion.

The study consisted of a non-randomized comparison between two groups (test and control) (Figure 1).


**Table 1.** Eligibility criteria for inclusion in the clinical study.

The test group included patients treated in the dental department of Cliniques universitaires St-Luc (Brussels, Belgium). The treatment consisted in a full pulpotomy as permanent treatment, and was performed by non-specialist junior practitioners (≤3 years residents).

The control group included patients treated in private specialist dental practice. The treatment, considered as gold standard, consisted in a root canal treatment performed by specialized endodontists in two different practices.

#### *2.2. Clinical Procedure*

Following patient inclusion and prior to anesthesia, pain and pre-operative data were collected. Bitewing and a periapical radiographs were taken systematically.

Test group—The tooth was then anesthetized using either Scandonest (3%) or Septanest (4%, 1:200,000 adrenalin) (Septodont, Saint-Maur-des-Fossés, France), respectively, for inferior alveolar nerve block (lower molars) and infiltration anesthesia (upper molars); complementary intra-ligament injections were performed with Scandonest when required. Rubber dam was placed, and the carious lesion was thoroughly excavated when present. The pulp chamber was then accessed with a new sterile bur, and the coronal pulp was completely eliminated. The pulp chamber was rinsed with NaCl, and hemostasis was obtained with a sterile cotton pellet soaked in NaCl. The cavity was gently dried with air spray, and the pulp tissue was capped with a tricalcium-silicate cement (Biodentine, Septodont, Saint-Maur-des-Fossés, France), which was left to set for 15 min. Whenever possible, a permanent composite restoration was placed on the same appointment using a combination of Clearfil SE Bond 2 (Kuraray-Noritake, Japan) and a highly filled composite, either GrandioSO (VOCO, Germany) or Clearfil Majesty Posterior (Kuraray-Noritake, Japan). When permanent restoration could not be placed directly, it was performed within the four weeks after the procedure. All permanent restorations were placed by the investigating team within the dental department. The use of magnification was systematic, mostly loupes, and sometimes microscopes, to properly evaluate pulpal status and compliance with inclusion/exclusion criteria (Table 1).

**Figure 1.** Experimental design.

Control group—No specific recommendations were given on how to perform root canal procedures, considering that the treatments were performed based on the ESE quality guidelines [21]. The aim was to let the specialist practitioners carry out their treatments according to their usual procedure, to be as close as possible to their routine work. The use of operative microscope was systematic, and allowed to evaluate compliance with inclusion/exclusion criteria corresponding to control group (Table 1). They were encouraged to perform their treatments in one appointment whenever possible, but were allowed to delay root canal obturation when time was lacking. A temporary glass ionomer restoration was placed between the appointments. A permanent coronal restoration was placed within the four weeks after the procedure by the referring dentist (either composite, crown or onlay/overlay).

#### *2.3. Short-Term Evolution of Pain*

Pain score was measured using the Heft–Parker scale [22]. The latter is based on verbal descriptors of clinical pain (used with patients), which are then converted into numerical values (by the investigators) (see Supplementary Materials Figure S1). The Heft–Parker scale has the specificity of presenting the clinical pain levels with an unequal

numerical spacing between pain descriptors, in order to better reflect the differences in word meaning [17].

Besides pre-operative measurement of pain intensity, the investigators conducted a telephone follow-up at 24 h (24 h) and 7 days (7 d) for patients in both groups. The pain scale (verbal descriptors only) was given to patients at the initial appointment to facilitate their evaluation at each timepoint.

In the control group, if the treatment was performed in more than one appointment, pain score was recorded after each appointment and the highest pain level was taken into account for the analysis.

#### *2.4. Treatment Success*

The evaluation of treatment success was performed in both groups based on similar criteria. One or more controls were performed depending on patient availability and compliance. Bitewing and periapical radiographs were taken systematically at each followup appointment. Three outcomes were considered.

*Global* success was defined as the combination of *clinical* and *radiographic* success.

*Clinical* success was defined as the absence of clinical signs (swelling, sinus tract, tooth mobility or deep periodontal probing) and symptoms (pain or discomfort). Therefore, any documented endodontic re-intervention or extraction for endodontic reasons at any time was considered as *clinical* failure.

*Radiographic* success was considered for cases with ≥12 months follow-up. It was determined as follows: first, no root resorption or furcal bone loss shall be observed; second, the periapical index (PAI) evolution shall either be a maintenance or return to healthy status (PAI 1 or 2), a maintenance of PAI 3 or a decrease in PAI if a true periapical lesion was pre-existing (PAI > 3).

The radiographs were submitted to two independent evaluators for analysis (JPVNH and SA). They were previously calibrated on 30 cases selected outside the present study based on the PAI scoring system defined by Ørstavik et al. [23]. The analysis of all radiographs were performed in a random order, under the same light conditions and on the same screen. Since multi-rooted teeth were studied, the highest PAI score at the root level was attributed to the tooth. In case of hesitation between two PAI scores, evaluators were asked to favor the higher one. The evaluation was repeated in a similar manner 3 weeks later. At the end of each session, disagreements were identified by the principal investigators (JB and JGL) and discussed between both evaluators to reach a consensus. Cohen's kappa coefficient was calculated to assess evaluator agreement.

#### *2.5. Histological Analysis*

For any successful case extracted for non-endodontic reasons in the *test* group (e.g., non-restorable factures or prosthetic reasons), teeth were placed in paraformaldehyde 4% for fixation and processed for histological evaluation according to the procedure described in [24].

#### *2.6. Statistical Analysis*

The data were submitted to analysis of normality using the Shapiro–Wilk test.

For short-term evolution of pain, a non-parametric Wilcoxon test was performed to test the effect of group (at each timepoint). For the effect of time, since normality could not be demonstrated, a Wilcoxon signed rank test was used.

For treatment success, a Pearson chi square or Fisher test were performed to compare *clinical*, *radiographic* and *global* success between test and control groups.

A logistic regression or test of independence was performed to test the impact of several variables, on the one hand on attribution of patients to both groups, and on the other hand on treatment success. A significance level of 0.05 was chosen for short-term analyses and sample distribution. Since three outcomes were considered for treatment success, a Bonferroni correction was applied and a significance level of 0.017 was chosen.
