Objective To investigate the effects of nursing interventions based on Health Behavior Process Theory (HAPA) on periodontal health and treatment compliance in patients undergoing immediate implantation following traumatic tooth loss. Methods A total of 80 patients who underwent immediate implant surgery for traumatic tooth loss at Guiyang Stomatological Hospital between May 2023 and May 2025 were selected and randomly divided into an observation group (receiving HAPA nursing intervention) and a control group (receiving conventional care) using a random number table, with 40 cases in each group. Postoperative periodontal health indicators, peri-implant bone resorption volume, treatment compliance, self-efficacy regarding periodontal health, and nursing satisfaction were compared between the two groups. Results After intervention, the observation group exhibited significantly lower values for all periodontal health indicators and peri-implant bone resorption compared to the control group (P<0.05). The observation group also demonstrated higher overall treatment compliance, self-efficacy scores, and nursing satisfaction than the control group (P<0.05). Conclusion HAPA nursing care can improve periodontal health in patients undergoing immediate implantation following traumatic tooth loss, reduce peri-implant bone resorption, and enhance patient treatment compliance, self-efficacy, and nursing satisfaction.