## 2 Materials and Methods  
### Study Design and Participants  
This retrospective observational study was conducted at Chosun University Dental Hospital and included patients diagnosed with trigeminal nerve injury involving the orofacial region between January 2014 and December 2023. The aim of the study was to investigate sensory changes and treatment outcomes over time, as well as to evaluate the influence of various clinical and therapeutic factors. This study was designed and reported in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines [19]. A completed STROBE checklist is provided in Table S1 (Supplementary Materials). Eligible patients were those who had sustained peripheral trigeminal nerve injury following trauma to the orofacial region, including both general facial injuries and procedure-related trauma, such as third molar extraction, dental implant placement, and endodontic surgery. Inclusion criteria were as follows: (1) the development of neurosorsory symptoms such as hypoesthesia, allodynia, hyperalgesia, or dysesthesia after the traumatic event; (2) the availability of visual analog scale (VAS) scores at both the initial and final clinical visits; and (3) the receipt of at least one form of therapeutic intervention during the observation period. Patients were excluded if they had a prior history of neuropathic pain unrelated to orofacial trauma or if complete VAS data were not available. Sensory function was evaluated using a normalized VAS ratio. Patients rated the intensity of tactile stimuli on the affected area relative to the contralateral normal side (defined as 100%), and the scores were divided by 100. A ratio of 1.0 represented normal sensation; values below 1.0 indicated hypoesthesia, while values above 1.0 reflected hypereesthesia or allodynia. Negative values were not permitted, as the sensory scores were calculated as ratios and could not fall below zero. As this was a retrospective chart review, no randomization or blinding was implemented during the data collection or analysis. Demographic and clinical variables were obtained from the patient medical records, including the trauma etiology, the anatomical distribution of the nerve injury, and the treatment modality. A total of 122 patients were screened during the study period from January 2014 to December 2023. The mean follow-up (F/U) duration was 7.86 months (SD = 9.60). After excluding two patients (one for not meeting the inclusion criteria and one due to missing data), a final cohort of 120 patients was included in the analysis. The yearly and cumulative number of patients enrolled over the 10-year period is shown in Figure 1, indicating a gradual increase in case identification and referral. The patient inclusion process and the classification based on the etiology of the nerve injury are summarized in a STROBE-compliant flow diagram (Figure 2). While all cases of orofacial trauma-related trigeminal nerve injury were reviewed to assess the overall epidemiological patterns--including anatomical distribution, sex differences, and trauma etiology--a focused subgroup analysis was performed for patients with implant-induced neuropathy, as this etiology represented the most frequent cause within the dataset. This allowed for a comparison of the clinical characteristics and treatment outcomes between the implant-related and non-implant-related cases. This study was approved by the Institutional Review Board (IRB) of Chosun University Dental Hospital (Approval Number: CUDHIRB 2407 003). As this was a retrospective chart review study, all patient data were de-identified and anonymized prior to analysis. The  
Figure 1: Histogram showing the number of newly-diagnosed patients with post-traumatic trigeminal neuropathic pain (PTTNP) for each year between 2014 and 2023. Each bar represents the number of new cases in a one-year interval, and the cumulative total is plotted as a line graph at the midpoint of each interval. The cumulative number reached 120 by the end of 2023.