Evaluation of Postoperative Pain and Bacterial Load After Hyalone or Calcium Hydroxide Medication in Mandibular First Molars

This randomized controlled clinical trial aims to evaluate the effect of Hyalone hydrogel compared with calcium hydroxide as an intracanal medicament on postoperative pain and bacterial load reduction in mandibular first molars with necrotic pulp and symptomatic apical periodontitis. The rationale for the study is based on the important role of intracanal medicaments in reducing residual microorganisms between treatment appointments. Calcium hydroxide is widely used because of its antimicrobial activity and alkaline pH; however, it has limitations related to its distribution, adherence to canal walls, antimicrobial spectrum, and effectiveness against microorganisms in complex root canal anatomy. Hyaluronic acid hydrogel has demonstrated potential benefits in dentistry, including supporting tissue healing and reducing inflammation and pain, and may therefore represent a promising alternative intracanal medicament.

The study will include 28 patients, equally divided into two groups of 14 participants. Patients will be recruited from the Endodontic Department outpatient clinic at the Faculty of Oral and Dental Medicine, Future University in Egypt. Eligible participants will be medically healthy patients aged 20-40 years, with mandibular first molars diagnosed with necrotic pulp and symptomatic apical periodontitis. Teeth should have closed apices, be restorable, be sensitive to percussion, and demonstrate slight widening of the lamina dura radiographically. Patients with systemic diseases, pregnancy or lactation, allergies to study medications, recent use of antibiotics or analgesics, swelling or acute apical abscess, open apices, vital pulp, periodontal mobility, previous root canal treatment, or abnormal/calcified canal anatomy will be excluded.

All participants will receive standardized endodontic treatment over two visits. During the first visit, medical and dental histories, clinical examination, radiographic examination, and preoperative pain assessment using the Numerical Rating Scale (NRS) will be performed. Following local anesthesia, caries removal, access cavity preparation, and rubber dam isolation, working length will be determined using an electronic apex locator and confirmed radiographically. The initial bacteriological sample (S1) will then be collected using sterile #15 paper points placed in the canal for one minute each. The samples will be processed microbiologically, and bacterial counts will be expressed as colony-forming units per milliliter (CFU/mL).

Cleaning and shaping will then be performed using a crown-down rotary instrumentation technique, with sterile saline irrigation between instruments. Following completion of instrumentation, a second bacteriological sample (S2) will be obtained to determine the reduction in bacterial load resulting from chemomechanical preparation. Patients will subsequently receive either Hyalone or calcium hydroxide, according to their randomized allocation. The medicament will be placed under aseptic conditions, and the access cavity will be temporarily restored using glass ionomer.

At the second visit after 7 days, the temporary restoration and intracanal medicament will be removed. The canals will be irrigated with sterile saline and a third bacteriological sample (S3) will be collected. This sample will allow assessment of the additional bacterial reduction associated with the intracanal medicament. Following sampling, the canals will be irrigated with 2.5% sodium hypochlorite and obturated using the cold lateral condensation technique with gutta-percha and resin sealer. The teeth will then receive a final composite restoration.

The primary outcome of the study is postoperative pain. Pain will be recorded using an 11-point NRS ranging from 0 (no pain) to 10 (pain as bad as could be). Patients will record their pain preoperatively and at 6, 12, 24, 48, and 72 hours and one week following treatment. Pain scores will also be categorized as none, mild, moderate, or severe.

The secondary outcome is the antimicrobial effect of the two intracanal medicaments. Bacterial samples obtained at S1, S2, and S3 will be analyzed using the serial dilution technique, with bacterial counts expressed as CFU/mL. Samples will be processed under aerobic and anaerobic conditions to assess the cultivable bacterial population. The changes in bacterial load before instrumentation, after chemomechanical preparation, and after intracanal medication will then be compared.

The sample size was calculated based on a previous study, with a minimum required sample of 11 participants per group. The number was increased to 14 participants