This study will recruit 180 molars diagnosed with irreversible pulpitis. Full pulpotomy will be performed on 120 teeth, while RCT (root canal treatment) will be conducted on another cohort of 60 teeth as the control for assessing long-term outcomes. Additionally, 12 blood samples and pulp tissues from healthy teeth receiving elective RCT will be collected as the controls. The first pulpal blood sample will be collected after caries removal and pulp exposure. Subsequently, the entire coronal pulp tissue will be removed and collected for histological examination, image-based spatial and scRNA-seq analyses. A second pulpal blood sample will be collected from the radicular pulp tissue. Both blood samples will be used to profile the inflammation-related biomarkers through multiplex immunoassays. The remaining pulp tissue will be covered by Biodentine and restored with resin-based composite. Pulpotomy treatment outcomes will be evaluated clinically and radiographically at 6 and 12 months. The biomarkers identified in the pulpal blood and histology and the single-cell transcriptomes of the coronal pulp will be compared with the treatment "success" and "failure" groups upon one year. The outcome of RCT will be compared with that of full pulpotomy at 24 months.

Inclusion Criteria:

• Permanent molars showing clinical and radiographic evidence of a deep carious lesion (extend to the three-quarters thickness of dentine radiographically) extending close to the pulp chamber
• Clinical diagnosis of irreversible pulpitis, including spontaneous pain, lingering pain with cold stimulation, no or mild tenderness to percussion, normal apical tissue or widening of the periodontal ligament space but with no signs of periapical periodontitis (i.e., PAI score 1 or 2)
• Positive response to cold and electric pulp test.

Exclusion Criteria:

• Tooth with no response to the cold and electric tests, presence of apical radiolucency (greater than periodontal widening), signs of canal calcification and resorption, history of trauma, unrestorable or nonfunctional teeth, and evidence of perio-endo lesion
• Intraoperative bleeding time is more than 10 minutes or less than 10 μL pulpal blood can be obtained
• Patients with a compromised immune status (such as HIV or organ transplant) or with any history of taking analgesics/antibiotics in the past one week.