Dental caries is among the most common childhood diseases that can progress and involve the dental pulp if left untreated; however, pulp therapy (e.g. pulpotomy) is usually successful for primary teeth with extensive caries1. Pulpotomy is currently the most commonly practiced efficient method for pulp treatment of asymptomatic primary molars. In this procedure, the residual radicular pulp tissue is capped and protected with a biomaterial to preserve its viability and reparability2.

Formocresol was a well-accepted gold-standard agent for pulpotomy of primary molars for many years, mainly because of its bacteriostatic and fixative properties, resulting in a high success rate. However, some concerns exist about its toxicity due to the presence of burning, mutagenic, and carcinogenic materials such as cresol and formaldehyde in its composition1,3.

Over the past years, numerous studies have investigated the efficacy and superiority of different capping agents proposed to improve the quality of pulpotomy in primary teeth, such as ferric sulphate, glutaraldehyde, calcium hydroxide (CH), freeze-dried bone, mineral trioxide aggregate (MTA), and sodium hypochlorite1, 2, 3.

Researchers have reported acceptably high success rates for many tested pulp capping agents; however, evidence suggests MTA as the most efficacious, but relatively expensive, capping agent for pulpotomy of primary teeth1. MTA, calcium enriched mixture (CEM) cement, and Biodentine have been recommended as optimal pulp capping agents for pulpotomy of permanent teeth4; therefore, researchers in the field of pediatric dentistry have attempted to evaluate the efficacy of these capping agents for application in primary teeth5.

MTA is mainly composed of calcium silicate compounds. The desirable properties of this hydraulic cement are optimized in presence of moisture, making MTA the highly favorable pulpotomy agent. MTA has a good sealing ability, low cytotoxicity, and optimal biocompatibility as well as some degrees of antibacterial activity. It can also induce dentinal bridge formation6,7. MTA is suggested as the gold standard for pulpotomy of primary teeth; however, it has some drawbacks such as high cost, difficult manipulation, causing tooth discoloration, and long setting time1.

CEM cement is a tooth-colored, water-based, alkaline endodontic biomaterial. Moreover, it releases calcium and phosphate ions to form hydroxyapatite and induce dentinal bridge formation8. Successful results reported by several studies support the application of CEM cement for pulpotomy of primary teeth9,10 even in cases with irreversible pulpitis11,12. It is affordable, and has easy manipulation and relatively short setting time.

CH is a traditional pulp protecting agent which is highly alkaline, easily accessible, and affordable. According to Waterhouse et al,3 CH in its pure powder form is a clinically acceptable alternative to formocresol. However, recent studies reported internal resorption in primary teeth pulpotomized with CH, and lower clinical and radiographic success rates compared with MTA in pulp therapy of primary molars3,13. Nonetheless, another study showed that pulpotomy with CH plus bio-stimulation yielded a clinical success rate comparable to that of pulpotomy with MTA and formocresol14.

Since no consensus has reached on the most appropriate technique for pulpotomy of primary teeth3,13, 14, 15, many recent studies evaluated the successful application of laser therapy in pulpotomy of primary teeth16, 17, 18, 19, 20, 21, 22, 23, 24, 25. Laser therapy can serve as an alternative or adjunct to traditional soft and hard tissue pediatric dental procedures. In the past couple of decades, laser therapy with different exposure parameters was used for vital pulp therapy and pulpotomy as an alternative to various conventional pharmacotherapeutic techniques. The therapeutic effects of laser therapy are due to its biological effects on wound healing, hemostasis, collagen synthesis, and nerve/bone regeneration depending on the type and the energy of laser applied16, 17, 18, 19, 20,25.

Diode lasers have been proposed as one of the most suitable laser types in pediatric dentistry. They are more frequently used in dental clinics, and have long been tested and suggested as the most effective laser type for pulpotomy of primary teeth. Diode laser delivered through a fiber optic cable aids in its clinical dental application while its small size and relatively low cost further contribute to its convenient application. The diode laser in Low-Level Laser Therapy (LLLT) mode has output powers typically less than 500 mW of energy. These lower-power lasers currently known as photobiomodulation (PBM)25.

Photobiomodulation offers advantages such as enhanced tissue healing, has lower risk of postoperative infection, and requires minimal or no need for anesthesia17, 18, 19, 20,25.It exerts anti-inflammatory effects, enhances collagen synthesis and induces revascularization and epithelization20,22. PBM has analgesic effects, and changes the pain threshold by increasing the release of endorphins and decreasing the release of bradykinin. Moreover it enhances wound healing and stimulate natural biologic processes and mainly affects cells in a decreased oxidation-reduction reaction.16,17,20,25.

Although several studies have been conducted on laser pulpotomy in the recent years, they mostly focused on clinical and radiographic success rates of laser pulpotomy in comparison with other materials/techniques, and reported conflicting results16, 17, 18, 19, 20, 21, 22. Considering the significant effect of pulp capping agents on the success of treatment and the possible effect of photobiomodulation on pulp tissue response to capping agents, this split-mouth randomized clinical trial was designed to assess the clinical and radiographic success rates of diode laser-assisted pulpotomy in non-contact mode with the use of three different pulp capping agents, i.e. MTA, CEM cement, and CH.