Evaluation of different treatment modalities for vital pulp of immature permanent molars: a randomized clinical trial

INTRODUCTION

The management of permanent teeth with insufficient root growth and impaired pulpal health is particularly challenging; hence, all efforts should be undertaken to preserve their vitality until maturity process is completed [1]. The widely recognized therapeutic approach for exposures in carious pulp of immature permanent teeth is pulpotomy, aiming at maintaining radicular pulp’s vitality and promoting continuity of roots’ growth [2]. For vital pulp therapy (VPT), calcium hydroxide (CH) has been the most frequently employed pulpotomy material [3]. Its high pH level and capacity to promote mineralization are the main reasons for utilization in dentistry, along with its antimicrobial features [4]. However, CH had lost the acceptance of being a first-choice treatment modality in pulpotomy due to drawbacks, including resistance of some microbes to CH powder mixed with saline [5], inadequate sealing, gradual disintegration, and creation of tunnel deficiencies below dentinal bridges [6].
Mineral trioxide aggregate (MTA) possesses dimi­nished solubility level and has the ability to maintain physical integrity after placement, as compared with traditional materials. Its poor solubility, radiopacity, hydrophilicity, bio-activity, and bio-compatibility, are all among the favorable properties of a VPT material [7]. Histologically, one of the most important features influencing MTA’s clinical efficacy is formation of a strong barrier against leakage of fluids and bacteria [8]. With its desirable properties, MTA has some disadvantages, including elevated pH levels during setting, inclusion of toxic ingredients, increased cytotoxic effect when newly mixed [9], challenging handling properties [10], prolonged setting duration [11], discoloration of teeth [12], and high cost [13].
Apexogenesis process requires a long treatment time, which can increase the risk of treatment failure. Consi­dering this fact, a method used to accelerate the process is of increasing interest [14]. Previous studies had shown that laser therapy can accelerate tissue repair by formation of a fibrous matrix and dentin bridge [15].
Because diode laser radiation has a sterilizing effect on target tissue in addition to its regenerative or reparative properties, it provides a conservative, biological alternate to other pulpotomy techniques [16]. Another factor contributing to the effectiveness of diode laser is hemostatic effect [17, 18]. Since this laser is a contact laser, its effects are limited to soft tissues, which come into direct contact with its tip. Hard tooth structures, such as enamel, dentine, and cementum, minimally absorb the laser energy, leaving them mostly unaffected [19]. Therefore, using soft-tissue diode lasers might affect the treatment results, and can be considered a reliable technique for VPT [16].

OBJECTIVES

The aim of this study was to assess apexogenesis outcomes clinically and radiographically after pulpotomy in young, immature permanent molars utilizing CH, MTA, laser, and laser-assisted MTA.

MATERIAL AND METHODS

Ethics

The research protocol was approved by the Mansoura University’s Ethics Committee for Scientific Research at the Faculty of Dentistry, under coded number of M 03060722. Study subjects were recruited for the research after obtaining parental written, informed consent.

Study model

The protocol complied with the consort statement suggestions in Figure 1. This was a randomized controlled clinical trial under ClinicalTrials.gov, with identification code of NCT05498337.

Sample size calculation and subject selection

The current study employed a sample size of 25 molars for every investigated group, which was sufficient to demonstrate validity and 80% power, based on an earlier study by Kaur et al. [20]. Sample size was determined using IBM SPSS (Statistical Package for Social Sciences, IBM) power release 3.0.1.
For this research, 100 first permanent molars from 100 patients of the Pediatric Dentistry Clinic at the Faculty of Dentistry, Mansoura University, were chosen, using the following inclusion criteria: children of both genders, with age ranging from 6 to 9 years, appearing to be in good health, and free of any chronic or systemic conditions. Regarding teeth, first permanent molars were included if were carious, restorable, and with immature roots, which met the clinical and radiographic standards, with no external or internal pathological root resorption, no sign or symptom of periapical infection, no sign or symptom of irreversible pulpitis or pulpal degeneration, such as spontaneous pain, periapical lesion, or presence of sinus tract. Tooth vitality was firstly assessed using cotton pellet dipped in ethyl chloride (Endo-Frost, Roeko, Germany), after the tooth was dried and well isolated.

Randomization

Children were chosen randomly with simple randomization method using a closed envelope technique by pulling a closed envelope with the name of a method that would be used for treatment. Each child independently selected the group name on a piece of closed paper that was normally not available to the operator. The goal of using this randomization technique was to achieve an equal and balanced groupings. In order to avoid inter-operator variability, the operator performed all clinical procedures rather than deciding which teeth were assigned to which testing group.

Group assignment

One hundred selected permanent molars were divided into 4 equal groups (25 molars in each group): Group 1 = CH, group 2 = MTA, group 3 = laser, and group 4 = laser-assisted MTA treatment.

Clinical procedures

After obtaining pre-operative periapical radiograph, 2% lignocaine with 1 : 80,000 adrenaline was used to administer local anesthesia, followed by a rubber dam insertion. A low-speed round bur or large spoon excavator were employed to remove caries. Using a large, sterile, sharp spoon excavator, the exposed pulpal tissue was excised up to the level of canal orifices. Using a cotton pellet wetted with normal saline, hemostasis was accomplished, as shown in Figure 2A. For every group, treatment was administered as follows:
• Group 1 (CH group): CH powder (Chema, Jet, Egypt) was combined with sterile saline on a sterile glass slab, and applied in a 2 mm layer to cover the exposed pulpal tissue, as illustrated in Figure 2B.
• Group 2 (MTA group): MTA (Bio-MTA, Cerkamed, Poland) was mixed as per the manufacturer’s guidelines. Using an amalgam carrier, a 3 mm layer was applied above the pulp tissue, and a condenser was used to gently pack it in, as in Figure 2C.
• Group 3 (Laser group): The root canal orifices were targeted by laser energy applying a continuous mode of application for around two seconds utilizing a diode laser device (Solase dental diode laser; Lazon Medical Laser Co., Ltd., Shenyang, China) supplied by a 300 μm optical fiber tip in contact mode at 1.5 W power [21]. When applying the laser, patients, parents, assistant, and the operator all wore the proper eye protection, as demonstrated in Figure 2D.
• Group 4 (Laser-assisted MTA group): The clinical procedures performed for group 3 were also done in group 4; after that, MTA was combined as per the manufactu­rer’s instruction, and applied in a layer of 3 mm above the pulp tissue.
For all groups, a thick layer of reinforced zinc oxide–eugenol cement base (Zinconol; Prevest Direct, India) filled the coronal pulp chamber. Next, glass ionomer filling cement (Medifil; Promedica, Germany) was used to fill the whole cavity, as in Figure 2E. A stainless-steel crown (Perma crown; Shinhuang, Korea) was cemented with GIC (Medicem; Promedica, Germany) to ensure intimate coronal seal. Post-operative periapical radiograph was obtained, as shown in Figure 2F.

Evaluation

At 6 and 12 months of follow-up, clinical and radiographic evaluations were conducted on all immature permanent molars under examination. Two experienced examiners, who were blind to all of the experimental groups, assessed the molars clinically and radiographically. Also, each observer was blinded to the other observer’s examination outcomes. A final consensus meeting was scheduled to resolve differences in two evaluators’ scores after an independent assessment. When two examiners assigned different evaluations, a third examiner re-evaluated the case. Inter-examiner consistency was calculated using κ statistics, taking the mean of the measures, and it was found to be above 85%.

Clinical evaluation

Clinical assessments were carried out at 6 and 12 months according to parameters showed by Johns et al. [22]. The purpose of these evaluations was to observe for various signs and symptoms, including swelling or presence of sinus tract (which indicated symptomatic pulp necrosis and abscess formation), pain, tenderness to percussion or pressure (which indicated periapical tissues inflammation), and tenderness to palpate of adjacent soft tissues.

Radiographic evaluation

Radiographic assessments were carried out at 6 and 12 months in compliance with specified standards provided in Eid et al. study [23]. The following were the objectives of these evaluations: periapical lesion, development of the root, root canal width, radiographic apex closure, internal or external root resorption, and widening of the periodontal ligament.

Statistical analysis

SPSS version 26.0 (PASW statistics for Windows, Chicago, SPSS Inc., IBM Co., USA) was employed to analyze data. Mean ± standard deviation was used to describe quantitative, normally distributed data, and Kolmogorov-Smirnov test was applied to verify data normalization. Qualitative data were described with percentages and numbers. Chi-square and Monte Carlo tests were performed to compare qualitative data between groups. One-way ANOVA test was employed for comparing more than two independent groups, and post-hoc Tukey test was used for pair-wise comparisons. P ≤ 0.05 was considered statistically significant.

RESULTS

Clinical assessment

After 6 and 12 months of follow-up, among the groups under investigation, molars were scored as clini­cal success if there was no pain either spontaneous or induced by cold, hot, or percussive stimuli with no swelling (abscess or fistulation). There were no statistically significant variations in the success or failure rates. At 12 months, group 1 (CH) achieved a clinical success rate of 98%, group 2 (MTA) 98%, group 3 (laser) 100%, and group 4 (laser-assisted MTA) 100%.

Radiographic assessment

At 6 and 12 months of follow-up, among the groups under investigation, no statistically significant differences were observed. Positive root development and closure of radiographic apex were detected in 92%, 92%, 100%, and 100% of CH, MTA, laser, and laser-assisted MTA groups, respectively. None of studied groups had positive internal or external root resorption. Positive periapical lesion and periodontal ligament widening were noted as 8% of CH and MTA groups, respectively, and for every failure, the same molar showed both criteria, as demonstrated in Table 1.

DISCUSSION

The study’s objective was to assess the effectiveness of pulpotomy technologies using CH, MTA, laser, and laser-assisted MTA, for young, immature permanent molars. During pulpotomy of immature fragile permanent molars, it is critical to achieve necessary goals of complete development of the root apex and thickening of the root walls [24]. The study subjects were limited to children in the age range of 6 to 9 years, in accordance with other studies, i.e., Mota et al. [25] and El-Hady et al. [26], considering that it is the age of molar eruption and development while their roots are still incompletely formed. Within this age range, a sample consisting only of first permanent molars was chosen, as Agrawal et al. [27] showed that they are the first permanent teeth to erupt in the oral cavity and are more susceptible to dental caries.
CH was selected as a traditional pulpotomy agent, because of its alleged ability to stimulate stem cells differentiation [28, 29]. MTA was chosen due to a number of benefits, including improved apexogenesis ability, antibacterial properties, and bio-compatibility. These attributes make MTA a special agent that has been effectively utilized in a range of clinical purposes [30]. Laser-assisted pulpotomy as a treatment modality was chosen for the study, considering its reported benefits, such as painless procedure and shorter chairside times, which enhance pediatric patient cooperation. Additio­nally, the diode laser was selected, because it is commonly used as a soft tissue laser in dentistry due to its dependability, versatility, and ease of use as well as its portability and straightforward setup [31].
Zinc oxide-eugenol cement mixed with high P/L ratios (10 : 1) [32] was applied in all groups’ patients, in line with Eid et al. [33], who showed that this mixture ratio shows significantly fewer eugenol release and diffusion, demonstrating anti-inflammatory and local anes­thetic effects on the dental pulp.
Prior researches have underlined the significance of biological seal, in which definitive restorative dressings and materials should be provided for preventing any possible micro-leakage during the restoration interface, both in the short- and long-term [34-36]. Therefore, stainless steel crowns were chosen as the definitive restoration in this study to reduce the risk of any possible leakage.
Although cone-beam computed tomography (CBCT) certainly has a place in pediatric dentistry, peripheral radiographs were selected for radiographic evaluation in the current study, because routine use of CBCT is not acceptable clinical practice, and its use must be justified on an individual basis, where benefits must clearly outweigh the potential risks [37]. CBCT is associated with a higher exposure of radiation compared with traditional dental radiographic exposures. Radiation risk from pediatric dental CBCT remains a health problem, even if literature data reveal no significant correlation between dental CBCT exposure and childhood cancer risk [38].
In the current study, the higher success rate of laser and laser-assisted groups (100%) compared with the success rate of CH and MTA groups (98%) may be attributable to the main benefits of laser-supported VPT, including the effects of bio-stimulation, hemostasis, and purification, also during VPT. Maintaining a sterile field during such procedures is essential, and it has been shown that laser-assisted treatment is superior to conventional antibacterial agents [39], since diode lasers have a large capacity for scattering light and may penetrate dentin deeply (range, 500-1,100 μm) [40, 41]. The hemostatic capability of diode laser is attributed to the marked amount of laser light absorbed by hemoglobin and melanin, which ensures that the targeted site will dries as quickly as possible [39]. The diode laser bio-stimulation impact reduces inflammation and pain, promotes cell migration and proliferation, stimulates cyto-differentiation of odontoblast-like cells, synthesizes dentin extra-cellular matrix, and forms reparative dentin in damaged pulpal tissue [42].
There are some limitations of this research, which need to be acknowledged, including a relatively short follow-up duration of one year only. Also, periapical radiographs were applied as the only method used for radiographic evaluation, which presents a challenge in reliable radiographic assessment. There was difficulty in describing the technique of laser application (as a safe technique) to some parents. Moreover, educating and motivating the parents on the importance of follow-up presented a considerable challenge in the current study due to the relatively low socio-economic level of most of the participants.

CONCLUSIONS

All studied pulpotomy techniques using CH, MTA, laser, and laser-assisted MTA demonstrated clinically and radiographically success, while laser and laser- assisted MTA pulpotomy techniques showed the best clinical success rates. Therefore, they can be recommended as alternatives to the conventional pulpotomy techniques. Based on the outcomes of this research, a longer follow-up duration is recommended for future studies, and for a more precise radiographic evaluation, CBCT utilization is advised.

Disclosures

1. Institutional review board statement: This study was approved by the Mansoura University’s Ethics Committee for Scientific Research at the Faculty of Dentistry (approval number: M 03060722).
2. Assistance with the article: The children and their parents, as well as the nursing staff at Mansoura University’s Pediatric Dental Clinic, are acknowledged by the authors for their support in this study.
3. Financial support and sponsorship: None.
4. Conflicts of interest: The authors declare no potential conflicts of interest concerning the research, authorship, and/or publication of this article.

References