Comparative efficacy of minimally invasive lavage with negative pressure sealing drainage versus traditional incision and drainage combined with ornidazole for oral and maxillofacial space infections: a retrospective study

Abstract

Objective

To compare the efficacy between minimally invasive lavage with negative pressure sealing drainage and traditional incision and drainage (both in combination with ornidazole) on pain relief, reduction of serum inflammatory factors, and wound healing in patients with oral and maxillofacial space infection.

Methods

This retrospective cohort study included 130 patients with OMSI. Patients were assigned to the Conventional Group (ornidazole with traditional incision and drainage, n = 59) or the Research Group (ornidazole with minimally invasive lavage and negative pressure sealing drainage, n = 71). Baseline infection severity was assessed using the Odontogenic Infection Severity Score (OISS). Outcomes included wound healing time, granulation growth time, length of hospital stay, clinical efficacy, postoperative pain (VAS), serum inflammatory markers (WBC, NEUT, PCT, IL−6, TNF-α), and postoperative infection rates. Statistical analyses incorporated False Discovery Rate (FDR) correction for multiple comparisons.

Results

The Research Group demonstrated significantly shorter wound healing time, granulation growth time, and hospital stay compared to the Conventional Group (all P_FDR < 0.001). The Research Group also showed significantly greater improvement in clinical symptoms, including a larger reduction in abscess diameter and a greater increase in mouth opening (P_FDR < 0.001), as well as significantly lower VAS scores at 1 and 5 days postoperatively (P_FDR < 0.001). At 1 day post-surgery, the Research Group had significantly lower levels of all serum inflammatory markers (P_FDR < 0.001), with large effect sizes. The overall incidence of postoperative infection was significantly lower in the Research Group (2.82%) than in the Conventional Group (11.86%) (P = 0.043).

Conclusion

Ornidazole combined with minimally invasive lavage and negative pressure sealing drainage can effectively shorten the wound healing time of OMSI patients, improve clinical symptoms, relieve inflammatory response and pain, and has high safety.

Introduction

Oral and maxillofacial space infections (OMSIs) represent a significant clinical challenge in oral and maxillofacial surgery, with odontogenic origins accounting for approximately 70–80% of cases [1, 2]. These infections typically arise from dental caries, periodontal disease, or pericoronitis and spread along fascial planes [1]. The anatomical complexity of this region, with its interconnected potential spaces such as the sublingual, submandibular, and parapharyngeal spaces, facilitates rapid spread of infection and increases the risk of life-threatening complications including airway compromise, cavernous sinus thrombosis, mediastinitis, and sepsis [3, 4].

The pathophysiology of OMSIs involves bacterial invasion that triggers a robust inflammatory response, characterized by the release of pro-inflammatory cytokines and tissue-damaging enzymes [5, 6]. Without prompt intervention, this process can lead to tissue necrosis, abscess formation, and systemic dissemination. Traditional management has relied on surgical incision and drainage followed by intermittent irrigation, but this approach has limitations including incomplete drainage, frequent dressing changes, and relatively higher complication rates [7, 8].

Antimicrobial therapy plays a crucial role in OMSI management. Ornidazole, a third-generation nitroimidazole antibiotic, demonstrates excellent activity against obligate anaerobic bacteria—particularly Prevotella and Fusobacterium species that are frequently isolated in OMSIs [9]. While systemic administration (oral or intravenous) remains standard, some evidence suggests that local application via irrigation may provide additional benefits in certain scenarios, though this requires further investigation [9].

Recent advances in surgical management include minimally invasive lavage with negative pressure wound therapy (NPWT), which offers continuous drainage and promotes wound healing through multiple mechanisms [10, 11]. This technique maintains a closed environment while removing exudate and reducing bacterial burden more effectively than conventional methods [10]. Recent systematic reviews confirm that NPWT improves outcomes in complex head and neck wounds, particularly in post-reconstructive and infection-related cases, though most evidence is from case series rather than randomized trials [12]. Clinical studies on maxillofacial and deep neck infections also suggest NPWT accelerates healing, reduces complications, and shortens hospitalization compared to traditional drainage [13]. Furthermore, meta-analyses across surgical specialties consistently show NPWT reduces surgical site infections and promotes faster recovery, supporting its potential applicability in OMSI management [14]. However, limited studies have evaluated the combination of ornidazole with minimally invasive lavage and NPWT for OMSIs.

Based on this background, we hypothesized that ornidazole combined with minimally invasive lavage and NPWT would improve wound healing, reduce inflammatory markers, and lower complication rates compared with conventional incision and drainage. This study aims to compare the efficacy of these two approaches in patients with OMSIs, with particular focus on pain control, serum inflammatory factor levels, and wound healing outcomes.

Materials and methods

Participants

This retrospective cohort study included 130 patients with oral and maxillofacial space infection who were treated in Wuxi Stomatological Hospital from February 2022 to February 2025. Patients were systematically screened from the hospital’s electronic medical record (EMR) system using the following process: consecutive patients diagnosed with OMSI (ICD−10 code: K12.2) during the study period were initially identified. We then applied the inclusion and exclusion criteria to this initial cohort. All eligible patients during the enrollment period were included, ensuring a consecutive sample and minimizing selection bias. Incomplete or missing medical records (e.g., missing laboratory results or treatment details) were excluded prior to analysis; a total of 12 potentially eligible patients were excluded due to incomplete data. This research has been approved by the hospital ethics committee (ethics approval number: 2022−06-B010). As a retrospective study, the requirement for informed consent was waived by the ethics committee. Inclusion criteria: ① All patients were diagnosed with OMSI by CT, ultrasound, local puncture and other examinations; ② All patients had abscesses and were infected in a single space; ③ Age ≥ 18 years old; ④ All patients required surgical incision and drainage. Exclusion criteria: ① Those who were intolerant to anesthesia and surgery; ② Those with multiple oral and maxillofacial infections; ③ Those with a history of taking antibiotics 2 weeks before enrollment; ④ Those with coagulation disorders, immunodeficiency, and tumors; ⑤ Those with jaw osteomyelitis; ⑥ Those with diabetes or hypertension. Patients with these systemic conditions were excluded primarily to minimize their potential confounding effects on wound healing and inflammatory response, which are the core outcomes of this study. This approach enhances the internal validity for detecting a true treatment effect by creating a more homogeneous patient cohort at baseline, albeit at the cost of limiting the immediate generalizability of the findings to the broader OMSI population with significant comorbidities.

The clinical data of the patients were retrieved from the EMR system for retrospective analysis. Patients were divided into two groups based on the treatment they received: 59 patients were assigned to the conventional group (ornidazole combined with traditional incision and drainage), and 71 patients were assigned to the Research Group (ornidazole and minimally invasive lavage negative pressure sealing drainage). This non-randomized assignment was based on clinical practice and patient-specific factors at the time of treatment. Specifically, the conventional technique was predominantly used earlier in the enrollment period, while the minimally invasive technique was adopted more frequently later on.

To mitigate potential temporal bias and address concerns regarding non-random allocation, the following methodological considerations were implemented: First, the enrollment periods for both groups were deliberately overlapped (February 2022 to February 2025) to avoid a complete temporal segregation of cohorts. Second, all surgical procedures, irrespective of the group, were performed or directly supervised by the same core team of senior attending surgeons to ensure consistency in surgical expertise and decision-making. Third, to objectively assess the comparability of the groups at baseline, key indicators of infection severity (including preoperative abscess diameter, WBC, NEUT, PCT, IL-6, and TNF-α levels) were pre-specified for comparative analysis. The objective of this approach was to ensure that any comparison between groups would be conducted on a foundation of clinical and demographic similarity. Due to the nature of the interventions, blinding of the surgeons and patients was not feasible. However, to mitigate detection bias, the outcome assessors for radiographic measurements (abscess diameter) and laboratory analyses (serological markers) were blinded to the group allocation. The patient screening flow chart is shown in Fig. 1.

Fig. 1.

Screening flow chart

Methods

All treatments and data collection procedures were part of standard clinical care. The data analyzed in this study were recorded in the patients’ medical records during their hospitalization. After admission, pus was collected from both groups of patients, and bacterial culture and drug sensitivity tests were performed to guide antimicrobial therapy. Prior to the availability of culture results, all patients received empirical intravenous antibiotic therapy according to hospital guidelines for orofacial infections. This consisted of Ceftriaxone (Rocephin^®, 1 g per vial, manufactured by Roche Pharma (Schweiz) Ltd.), administered at 1 g intravenously every 12 h, combined with Ornidazole intravenous infusion (XinRui^®, 0.25 g per 100 ml/bag, manufactured by Sichuan Kelun Pharmaceutical Co., Ltd., China), administered at 0.5 g (two bags) intravenously every 12 h, to cover both Gram-positive and anaerobic bacteria. The antibiotic regimen was subsequently adjusted based on the results of the culture and sensitivity tests. Both groups received the same standardized supportive care, including nutritional support and maintenance of electrolyte balance. The location, size, and range of the abscess cavity were determined by preoperative examinations such as ultrasound and CT.

The conventional group received ornidazole (Wuidaxin^® Capsules, 0.25 g per capsule, Zhejiang Wuzhou Pharmaceutical Co., Ltd., China) combined with traditional incision and drainage. According to the size of the abscess, large-area incision and drainage were performed, and the abscess was enlarged with vascular clamps, and then saline was injected with a syringe for irrigation. The lavage fluid was drawn out with a syringe again, and repeated several times until the discharged liquid became clear. Once a day, it continued for 3 days and then adjusted to once every 2 days. At the same time, ornidazole capsules were taken orally, 0.5 g (two capsules) each time, 3 times a day. The treatment lasted for 5 days.

The Research Group received ornidazole (same brand and dosage as the conventional group) and minimally invasive lavage negative pressure closed drainage treatment using a negative pressure sealing drainage system (VSD^® Medical System, Weigao Group Medical Polymer Co., Ltd., China). An incision was made along the skin texture at the site of the greatest fluctuation of the abscess, and then the pus was deeply peeled off with a vascular clamp; after the necrotic cells were removed, it was repeatedly rinsed with normal saline. After the cleaning was completed, a negative pressure closed drainage tube (model: VSD−100) was placed, and the orientation of the drainage tube was adjusted until it matched the abscess. A small hole was cut from the lower part of the wound and the drainage tube was removed; the wound was sutured and closed with a negative pressure sticker. After completion, negative pressure suction was applied using a dedicated negative pressure device (model: VSD-P100) at a pressure of−40 kPa (or−300 mmHg), with suction applied continuously. The drainage fluid was observed daily. When its color was clear, the tube could be removed. The treatment was continued for 5 days.

Evaluation metrics

All outcome measures were assessed based on data extracted from the electronic medical records.

General treatment indicators

The wound healing time, granulation growth time and hospitalization time of OMSI patients were recorded.

Clinical efficacy

Heal: local infection, swelling, heat, pain, abscess symptoms completely disappeared, wound surface completely healed, systemic symptoms disappeared, biochemical indicators returned to normal, eating and speaking returned to normal; Highly effective: local infection, swelling, heat, pain, abscess symptoms basically disappeared, wound surface mostly healed, systemic symptoms basically disappeared, biochemical indicators significantly improved; Effective response: local swelling, heat, pain, abscess symptoms improved, small wound surface healed, systemic symptoms basically disappeared, biochemical indicators improved; Ineffective: local wound surface did not improve or worsened, systemic symptoms and biochemical indicators did not improve or worsened. Treatment effective rate = (heal + highly effective + effective response)/total number of cases × 100%. To ensure the consistency and objectivity of the clinical efficacy assessment, the efficacy ratings for all patients were independently evaluated by two experienced attending physicians based on the above criteria, who were blinded to the patient’s group allocation. Any discrepancies in ratings were resolved through discussion or, if necessary, by a third senior consultant. The inter-rater reliability between the two primary assessors was substantial, with a Cohen’s kappa coefficient of 0.82.

Symptom improvement and abscess severity

CT and ultrasound were used to measure the diameter of the abscess in OMSI patients. The mouth opening of the two groups of patients was measured with a caliper, and the mouth opening was limited when the distance between the upper and lower central incisors of the patient was ≤ 2 cm. The hospitalization time of the patients was also recorded. The measurement time was 5 days before and after the operation. To objectively quantify the initial infection severity, the Odontogenic Infection Severity Score (OISS) was retrospectively calculated for each patient based on preoperative clinical and laboratory records, according to the validated criteria [15]. The OISS is a comprehensive scoring system (range: 0–20) that incorporates systemic inflammatory response (SIRS criteria), trismus, dysphagia, the number and type of involved fascial spaces, dehydration, and comorbidities.

Postoperative pain

The pain level of OMSI patients was assessed by VAS score. A 10-cm horizontal line was drawn on a piece of paper and the patients were self-scored according to the pain level, which was divided into 0 to 10 levels. The corresponding numbers were divided into different levels. The higher the score, the more severe the pain. The assessment time was before surgery, 1 day after surgery, and 5 days after surgery.

Serum factors

Six mL of fasting cubital venous blood was collected from OMSI patients in the morning, centrifuged at 3000 r/min for 10 min, and serum was separated and stored in a−70 °C refrigerator for testing. The DXH800 fully automatic blood cell analyzer was used to measure the WBC and NEUT levels of OMSI patients; the ELISA method was used to measure the serum PCT, IL−6, and TNF-α levels of OMSI patients. Commercial human ELISA kits were used according to the manufacturers’ protocols: PCT (Cloud-Clone Corp., catalog number SEA479Hu), IL−6 (Cusabio, catalog number CSB-E04638h), and TNF-α (Elabscience, catalog number E-EL-H0109c). All kits had a detection sensitivity of < 10 pg/mL, and both intra- and inter-assay coefficients of variation were confirmed to be < 10% and < 12%, respectively. A standard curve was generated for each assay to ensure accurate quantification. The evaluation time was before surgery, 1 day after surgery, and 5 days after surgery.

Complications

Observe whether OMSI patients have local infection, secondary infection, systemic infection, etc.

Statistical methods

SPSS 26.0 statistical software was used to analyze the data. The normality of the distribution for all continuous variables was assessed using the Shapiro-Wilk test. Continuous data were described as mean ± standard deviation (SD). For comparisons between the two independent groups, normally distributed data were analyzed using the independent samples t-test, while the Mann-Whitney U test was used for non-normally distributed data. For paired comparisons within groups (e.g., pre-operative vs. post-operative measurements), the paired t-test was used for normally distributed data, and the Wilcoxon signed-rank test was used for non-normally distributed data. Categorical data were expressed as frequencies and percentages [n (%)] and compared using the Chi-squared (χ²) test or Fisher’s exact test, as appropriate.

Given the multiple outcome measures assessed in this study, the False Discovery Rate (FDR) was controlled using the Benjamini-Hochberg procedure to mitigate the risk of Type I error. The set of hypotheses subjected to FDR correction included all between-group comparisons of secondary outcomes: wound healing time, granulation growth time, length of hospital stay, postoperative abscess diameter, postoperative mouth opening, VAS scores at 1 and 5 days postoperatively, all serum inflammatory marker levels at 1 day postoperatively, and the incidence of postoperative infection. The primary outcome of overall clinical efficacy rate and baseline characteristic comparisons were not included in the FDR correction set. The resulting FDR-adjusted P-values are reported alongside the raw P-values in the results.

In addition to P values, effect sizes (Cohen’s d for t-tests, rank-biserial correlation for non-parametric tests, and Cramér’s V for χ² tests) are reported to quantify the magnitude of observed differences. For key continuous outcomes, between-group mean differences with 95% confidence intervals are also presented to facilitate clinical interpretation.

To address potential confounding and bolster the robustness of our findings, sensitivity analyses were performed using univariate and multivariate linear or logistic regression models where appropriate. Covariates for the multivariate models were selected based on clinical relevance (e.g., smoking status as a known risk factor) or an association with the outcome in univariate analysis (P < 0.1). For the linear regression model, assumptions of linearity, homoscedasticity, and normality of residuals were assessed graphically and were reasonably met. For the logistic regression model, the Hosmer-Lemeshow test was used to assess goodness-of-fit, and variance inflation factors (VIF) were examined to check for multicollinearity, which was found to be low (VIF < 2). We acknowledge that the small number of events for the postoperative infection outcome limited the power and precision of the logistic regression model.

The sample size for this study was estimated based on a preliminary review of patient records and the primary outcome of wound healing time. Using an effect size of 0.5 (Cohen’s d), an alpha error of 0.05, and a power (1-beta) of 0.8, a minimum of 64 patients per group was calculated to be necessary to detect a statistically significant difference using G*Power software (version 3.1.9.7). Although the final group sizes were slightly imbalanced (Conventional: 59, Research: 71), the total sample size of 130 patients exceeds the minimum requirement and is therefore deemed sufficient to detect clinically meaningful differences for the primary outcomes of this study.

Results

Baseline data

Table 1 shows the baseline data of the two groups of patients. The enrollment periods for the two groups overlapped, with the Conventional Group enrolled from February 2022 to December 2024, and the Research Group enrolled from March 2023 to February 2025. The baseline data of the research group, such as age, gender, BMI, infection source, smoking, and drinking, were tested using statistical software and found that there was no statistically significant difference (P > 0.05).

Table 1.

Analysis of baseline data of the two groups

Parameter	Conventional group (n = 59)	Research Group (n = 71)	t/x2	P
Age (years)	48.13 ± 4.90	48.56 ± 4.77	0.505	0.614
gender			0.187	0.665
male	31	40
female	28	31
BMI (kg/m2)			0.021	0.886
≥ 23	30	37
<23	29	34
Source of infection			1.379	0.512
Odontogenic	39	43
Glandular	14	23
Other	6	5
Smoking	41	50	0.018	0.903
Drinking	38	44	0.125	0.724

General treatment indicators

According to the data in Table 2, compared with the conventional group, the wound healing time, granulation growth time and hospitalization time of the Research Group were significantly shortened (all P_FDR < 0.001). The magnitude of these differences was large, as indicated by Cohen’s d values of 0.84, 1.48, and 1.45 for the three outcomes, respectively. In absolute terms, the Research Group demonstrated a reduction in hospitalization time of 4.73 days (95% CI: 3.78 to 5.68), a 1.20-day reduction in wound healing time (95% CI: 0.74 to 1.66), and a 1.95-day reduction in granulation growth time (95% CI: 1.55 to 2.35) compared to the Conventional Group. These substantial reductions not only are statistically significant but also represent clinically relevant improvements in patient recovery.

Table 2.

Comparison of general treatment indicators between the two groups

Outcome Measure	Conventional Group (n = 59)	Research Group (n = 71)	Mean Difference (95% CI)	Cohen’s d (95% CI)	P value	FDR-adjusted P-value
Wound healing time (days)	7.25 ± 1.50	6.05 ± 1.36	−1.20 (−1.66 to −0.74)	0.84 (0.45 to 1.22)	< 0.001	< 0.001
Granulation growth time (days)	9.65 ± 1.35	7.70 ± 1.29	−1.95 (−2.35 to −1.55)	1.48 (1.06 to 1.89)	< 0.001	< 0.001
Length of hospital stay (days)	20.28 ± 3.77	15.55 ± 2.81	−4.73 (−5.68 to −3.78)	1.45 (1.03 to 1.86)	< 0.001	< 0.001

Data presented as mean ± standard deviation. CI confidence interval. Effect size interpretation for Cohen’s d: small (0.2), medium (0.5), large (0.8). The False Discovery Rate (FDR) correction was applied to the three primary continuous outcomes in this table

Clinical efficacy

According to the data in Table 3, the total effective rate of the Research Group was 94.37% (67/71) compared with 91.53% (54/59) in the conventional group. This difference of + 2.84% (95% CI:−4.99 to + 10.67) was not statistically significant (RD, P = 0.525). The Number Needed to Treat was 35, indicating that a large number of patients would need to be treated with the combined protocol to result in one additional patient achieving an effective outcome, compared to conventional treatment.

Table 3.

Comparison of clinical treatment efficacy between the two groups [n (%)]

Outcome	Conventional group (n = 59)	Research Group (n = 71)	P value
Heal	26 (44.07%)	34 (47.89%)	-
Highly effective	20 (33.90%)	22 (30.99%)	-
Effective response	8 (13.56%)	11 (15.49%)	-
Ineffective	5 (8.47%)	4 (5.63%)	-
Total Effectiveness	54 (91.53%)	67 (94.37%)	0.525

Total effectiveness = (Heal + Highly effective + Effective response). The Risk Difference (RD) is + 2.84% (95% CI:−4.99 to + 10.67), and the Number Needed to Treat (NNT) is 35. CI: confidence interval; NNT: Number Needed to Treat. Total effectiveness = (Heal + Highly effective + Effective response). The Risk Difference (RD) is calculated as (Rate in Research Group - Rate in Conventional Group)

Symptom improvement and abscess severity

Preoperative infection severity, as quantified by the Odontogenic Infection Severity Score (OISS), was comparable between the two groups, with no significant differences in total score or severity stratum distribution (both P > 0.05, Table 4). According to the data in Table 5, the symptoms of both groups were significantly improved after surgery, with reductions in abscess diameter and increases in mouth opening (P < 0.05 for within-group comparisons). Furthermore, the between-group comparison of postoperative outcomes revealed that the Research Group achieved a significantly smaller postoperative abscess diameter and a greater postoperative mouth opening than the Conventional Group (both P_FDR < 0.001). The magnitude of these interventional effects was large. The Research Group’s abscess diameter was 0.76 cm smaller (95% CI: 0.49 to 1.03 cm), and their mouth opening was 0.50 cm greater (95% CI: 0.28 to 0.72 cm) than the Conventional Group postoperatively. These differences, corresponding to Cohen’s d values of 0.80 and 0.70 respectively, represent not only statistical significance but also clinically meaningful improvements in local symptom resolution.

Table 4.

Comparison of baseline infection severity using the odontogenic infection severity score (OISS) between the two groups

OISS Assessment	Conventional Group (n = 59)	Research Group (n = 71)	P value
Total Score (mean ± SD)	6.8 ± 1.9	6.9 ± 2.1	0.762*
Severity Stratum [n (%)]			0.841†
Mild (OISS 1–4)	8 (13.6%)	12 (16.9%)
Moderate (OISS 5–8)	38 (64.4%)	43 (60.6%)
Severe (OISS ≥ 9)	13 (22.0%)	16 (22.5%)

Data presented as mean ± standard deviation or number (percentage)

OISS Odontogenic Infection Severity Score

 P value from independent samples t-test. †P value from Chi-squared test forthe distribution across severity strata

Table 5.

Comparison of symptom improvement between the two groups

Outcome Measure	Time Point	Conventional Group (n = 59)	Research Group (n = 71)	Mean Difference (95% CI)	Cohen’s d (95% CI)	P value (Between-group)	FDR-adjusted P-value
Abscess Diameter (cm)	Preoperative	6.40 ± 1.49	6.45 ± 1.44	−0.05 (−0.53 to 0.43)	-	0.847	-
	Postoperative	3.37 ± 1.15	2.61 ± 0.70	0.76 (0.49 to 1.03)	0.80 (0.42 to 1.18)	< 0.001	< 0.001
Mouth Opening (cm)	Preoperative	1.42 ± 0.33	1.49 ± 0.29	−0.07 (−0.17 to 0.03)	-	0.200	-
	Postoperative	2.75 ± 0.69	3.25 ± 0.77	−0.50 (−0.72 to −0.28)	0.70 (0.32 to 1.07)	< 0.001	< 0.001

Data presented as mean ± standard deviation. CI confidence interval. The FDR correction was applied to the between-group comparisons of the two primary postoperative outcomes (abscess diameter and mouth opening). All within-group comparisons (postoperative vs. preoperative) were significant at P < 0.05

Postoperative pain

According to the data in Table 6, VAS scores decreased significantly over time within both groups, indicating effective pain relief after surgery (P < 0.05 for within-group comparisons at each time point). Compared to the Conventional Group, the Research Group reported significantly lower pain levels both at 1 day and 5 days postoperatively (both P_FDR < 0.001). The effect size of the superior pain control in the Research Group was large at 1 day (Cohen’s d = 0.95) and very large at 5 days (Cohen’s d = 2.24). In terms of absolute pain reduction, the Research Group’s VAS score was 0.97 points lower (95% CI: 0.65 to 1.29) than the Conventional Group at 1 day postoperatively, and 1.49 points lower (95% CI: 1.27 to 1.71) at 5 days postoperatively.

Table 6.

Comparison of postoperative pain (VAS scores) between the two groups

Time Point	Conventional Group (n = 59)	Research Group (n = 71)	Mean Difference (95% CI)	Cohen’s d (95% CI)	P value (Between-group)	FDR-adjusted P-value
Preoperative	7.96 ± 1.30	7.77 ± 1.35	0.19 (−0.26 to 0.64)	-	0.418	-
1 day postoperatively	6.44 ± 1.10	5.47 ± 0.95	0.97 (0.65 to 1.29)	0.95 (0.56 to 1.33)	< 0.001	< 0.001
5 days postoperatively	3.79 ± 0.80	2.30 ± 0.52	1.49 (1.27 to 1.71)	2.24 (1.74 to 2.73)	< 0.001	< 0.001

Data presented as mean ± standard deviation. VAS Visual Analog Scale (range 0–10), CI confidence interval. The FDR correction was applied to the between-group comparisons at the two postoperative time points. All within-group comparisons (postoperative vs. preoperative) were significant at P < 0.05

Serum factors

According to Table 7, all serum inflammatory markers (WBC, NEUT, PCT, IL−6, TNF-α) decreased significantly within both groups after surgery compared to preoperative levels (all P < 0.05). Most notably, at 1 day postoperatively, the Research Group demonstrated significantly lower levels across all five inflammatory markers compared to the Conventional Group (all P_FDR < 0.001), with large effect sizes (Table 7), indicating a more rapid attenuation of the systemic inflammatory response. The Research Group showed substantially greater reductions in inflammatory markers at 1 day, with mean differences ranging from−0.91 µg/L for PCT to−14.98 µg/L for IL−6. By postoperative day 5, the levels in both groups had decreased substantially and no statistically significant differences remained for any marker (all P_FDR > 0.05), suggesting that both treatment protocols were ultimately effective in controlling the infection. The early and pronounced reduction in key markers like PCT and IL−6 in the Research Group, with effect sizes exceeding 1.9, highlights the protocol’s capacity to rapidly mitigate the systemic inflammatory burden, which is clinically significant in preventing the progression to severe sepsis.

Table 7.

Comparison of serum inflammatory markers between the two groups

Serum Marker	Time Point	Conventional Group (n = 59)	Research Group (n = 71)	Mean Difference (95% CI)	Cohen’s d (95% CI)	P value	FDR-adjusted P-value
WBC (×10⁹/L)	Preoperative	16.44 ± 3.63	16.12 ± 3.71	0.32 (−0.93 to 1.57)	-	0.622	-
	1 day postop	14.95 ± 3.04	12.14 ± 2.55	2.81 (1.91 to 3.71)	0.99 (0.60 to 1.38)	< 0.001	< 0.001
	5 days postop	9.79 ± 1.92	9.45 ± 1.83	0.34 (−0.31 to 0.99)	0.18 (−0.19 to 0.55)	0.304	0.380
NEUT (%)	Preoperative	119.33 ± 14.20	117.94 ± 15.12	1.39 (−3.87 to 6.65)	-	0.593	-
	1 day postop	96.22 ± 11.55	87.30 ± 10.46	8.92 (5.16 to 12.68)	0.82 (0.44 to 1.20)	< 0.001	< 0.001
	5 days postop	69.45 ± 9.74	66.20 ± 9.85	3.25 (−0.18 to 6.68)	0.33 (−0.04 to 0.70)	0.062	0.124
PCT (µg/L)	Preoperative	5.79 ± 1.20	5.86 ± 1.13	−0.07 (−0.48 to 0.34)	-	0.733	-
	1 day postop	4.16 ± 0.52	3.25 ± 0.39	0.91 (0.76 to 1.06)	2.01 (1.50 to 2.51)	< 0.001	< 0.001
	5 days postop	1.11 ± 0.30	1.19 ± 0.25	−0.08 (−0.18 to 0.02)	−0.30 (−0.67 to 0.07)	0.010	0.025
IL-6 (µg/L)	Preoperative	96.14 ± 9.75	95.95 ± 9.88	0.19 (−3.29 to 3.67)	-	0.913	-
	1 day postop	72.12 ± 8.12	57.14 ± 7.12	14.98 (12.22 to 17.74)	1.97 (1.47 to 2.47)	< 0.001	< 0.001
	5 days postop	42.75 ± 6.44	41.33 ± 6.53	1.42 (−0.84 to 3.68)	0.22 (−0.15 to 0.59)	0.217	0.271
TNF-α (ng/L)	Preoperative	53.10 ± 8.23	53.79 ± 8.07	−0.69 (−3.49 to 2.11)	-	0.631	-
	1 day postop	40.11 ± 6.53	32.12 ± 4.19	7.99 (5.91 to 10.07)	1.50 (1.05 to 1.94)	< 0.001	< 0.001
	5 days postop	23.13 ± 3.90	22.12 ± 3.44	1.01 (−0.26 to 2.28)	0.27 (−0.10 to 0.64)	0.119	0.198

Data presented as mean ± standard deviation. CI confidence interval. The FDR correction was applied to the between-group comparisons of the five serum markers at the two postoperative time points (10 comparisons in total). All within-group comparisons (postoperative vs. preoperative) were significant at P < 0.05

Postoperative infection

As detailed in Table 8, the overall incidence of postoperative infection in the Research Group (2.82%, 2/71) was significantly lower than that in the Conventional Group (11.86%, 7/59) (P = 0.043, P_FDR = 0.086). This corresponds to an absolute risk reduction of 9.04% (95% CI: 0.42 to 17.66%), with a Number Needed to Treat (NNT) of 11, indicating that approximately 11 patients would need to be treated with the combined protocol to prevent one additional postoperative infection compared to conventional treatment. The odds of having a postoperative infection were 78% lower in the Research Group (OR = 0.22, 95% CI: 0.04 to 0.99). It should be noted that the relatively small number of overall infection events (n = 9) limits the precision of this estimate, as reflected in the wide confidence interval around the odds ratio. Nonetheless, the observed risk reduction represents a clinically meaningful decrease in a significant postoperative complication.

Table 8.

Comparison of postoperative infection outcomes between the two groups

Outcome	Conventional Group (n = 59)	Research Group (n = 71)	Statistics	Value (95% CI)	P value	FDR-adjusted P-value
Overall Infection	7 (11.86%)	2 (2.82%)	Risk Difference	−9.04% (−17.66 to −0.42)	0.043	0.086
			Odds Ratio	0.22 (0.04 to 0.99)
			NNT	11 (6 to 238)
Infection Type
Local infection	4 (6.78%)	1 (1.41%)
Secondary infection	2 (3.39%)	0 (0.00%)
Systemic infection	1 (1.69%)	1 (1.41%)

Data presented as n (%) unless otherwise specified. CI confidence interval, NNT Number Needed to Treat. The FDR correction was applied to the comparison of overall infection rates between groups. NNT calculation: 1/(Absolute Risk Reduction); 95% CI for NNT calculated as 1/(95% CI bounds for ARR)

Postoperative complications detail

The specific types of local and systemic complications observed in both groups are detailed in Table 9. In the Conventional Group (n = 59), there were 4 cases of local infection at the wound site, 2 cases of secondary infection spreading to an adjacent fascial space, and 1 case of systemic infection presenting as bacteremia. In the Research Group (n = 71), only 1 case of local wound infection and 1 case of systemic infection (bacteremia) were observed. No cases of secondary infection were documented in the Research Group. All cases of local and secondary infection were managed successfully with targeted antibiotic therapy based on culture results and intensified local wound care. The cases of bacteremia required escalation to broad-spectrum intravenous antibiotics according to institutional protocols, and all patients made a full recovery.

Table 9.

Detailed description of postoperative complications between the two groups [n (%)]

Complication Type	Conventional Group (n = 59)	Research Group (n = 71)	Management
Local Complications
Local wound infection	4 (6.78%)	1 (1.41%)	Targeted antibiotics, local care
Secondary infection (adjacent space)	2 (3.39%)	0 (0.00%)	Targeted antibiotics, drainage if needed
Systemic Complications
Bacteremia	1 (1.69%)	1 (1.41%)	Broad-spectrum IV antibiotics
Sepsis/Septic shock	0 (0.00%)	0 (0.00%)	-
Total Patients with Complications	7 (11.86%)	2 (2.82%)

Multivariate regression analysis

To control for potential confounding factors and validate the robustness of the primary findings, multivariate regression analyses were performed for two key outcomes: wound healing time and incidence of postoperative infection. Covariates for these models were selected based on a combination of clinical relevance (e.g., smoking status as a known risk factor for infection, baseline abscess diameter as an indicator of severity) and an association with the outcome in univariate analysis at a liberal threshold of P < 0.1.

For the primary outcome of wound healing time, a multiple linear regression model was constructed (Table 10). After adjusting for baseline abscess diameter and patient age, the treatment group (Research Group vs. Conventional Group) remained a statistically significant independent predictor of shorter healing time (β =−1.18, 95% CI:−1.64 to−0.72, P < 0.001). This indicates that after accounting for these potential confounders, the minimally invasive technique was independently associated with a reduction in healing time of approximately 1.18 days. Diagnostic analyses, including residual plots, did not reveal substantial violations of the linearity or normality assumptions.

Table 10.

Multiple linear regression analysis for predictors of wound healing time

Variable	Category	Unstandardized β Coefficient	95% Confidence Interval		P
			Lower Bound	Upper Bound
(Constant)		10.52	8.91	12.13	< 0.001
Treatment Group	Research Group (Ref: Conventional)	−1.18	−1.64	−0.72	< 0.001
Baseline Abscess Diameter	(per 1 cm increase)	0.31	0.09	0.53	0.006
Age	(per 1 year increase)	0.02	−0.02	0.06	0.340

Dependent Variable: Wound healing time (days). Model Summary: R² = 0.342, Adjusted R² = 0.325. Ref: Reference category

For the outcome of postoperative infection, a multivariate logistic regression model was used (Table 11). After adjusting for smoking status and baseline WBC count, the treatment group was independently associated with a lower risk of postoperative infection (Adjusted OR = 0.19, 95% CI: 0.04 to 0.92, P = 0.039). It is important to interpret this finding with caution due to the limited number of infection events (n = 9), which reduces the statistical power of the model and is reflected in the wide confidence interval for the odds ratio. Despite this limitation, which precludes definitive conclusions, the direction and magnitude of the observed association are consistent with the overall findings. Multicollinearity was assessed and found to be low (all VIF < 2).

Table 11.

Multiple logistic regression analysis for predictors of postoperative infection

Variable	Category	Adjusted Odds Ratio (OR)	95% Confidence Interval		P
			Lower Bound	Upper Bound
Treatment Group	Research Group (Ref: Conventional)	0.19	0.04	0.92	0.039
Smoking Status	Smoker (Ref: Non-smoker)	3.05	0.98	9.53	0.054
Baseline WBC	(per 1 × 10⁹/L increase)	1.12	0.98	1.28	0.091

Dependent Variable: Postoperative infection (Yes/No). Model Fit: Hosmer-Lemeshow test, P = 0.621; Nagelkerke R² = 0.182. Ref: Reference category

The details of these models are presented in Tables 10 and 11. A similar multivariate analysis was not conducted for the clinical efficacy rate due to the lack of a statistically significant difference between groups in the primary univariate analysis.

Discussion

OMSIs require prompt intervention to prevent serious complications. Traditional incision and drainage, while standard, has limitations such as incomplete drainage and higher trauma [16–18]. In this study, we compared conventional drainage with a novel approach combining ornidazole, an effective anti-anaerobic agent [19, 20], with minimally invasive lavage and negative pressure sealing drainage.

Minimally invasive lavage and negative pressure sealing drainage promotes continuous discharge of infected necrotic tissue and pus, reduces bacterial reproduction and wound infection risk [21, 22]. Ornidazole effectively kills obligate anaerobic bacteria [23]. The Research Group demonstrated significantly shorter wound healing time, granulation growth time, and hospitalization time; the absolute reductions in hospitalization time (4.73 days) and wound healing time (1.20 days) are clinically meaningful. The > 1 point greater reduction in VAS pain scores at 5 days postoperatively exceeds the threshold for minimal clinically important difference [24]. The comparable baseline infection severity, as objectively quantified by the OISS, strengthens the validity of comparing outcomes between groups.

The levels of WBC, NEUT, PCT, IL-6 and TNF-α in the Research Group were significantly lower than the conventional group 1 day after surgery [25–29], suggesting more rapid control of systemic inflammatory response. The total incidence of postoperative infection was 2.82% versus higher in controls. However, the absence of significant differences in serum inflammatory markers by postoperative day 5 indicates the anti-inflammatory benefit is primarily evident in the acute phase.

Although this study did not directly assess costs, the markedly shorter hospitalization duration implies substantial economic benefits. Hospitalization for odontogenic infections incurs high expenses, averaging $9,417 in direct hospital costs per patient [2]. Minimally invasive approaches in odontogenic maxillary sinusitis demonstrate cost-competitive outcomes [30, 31], warranting dedicated economic evaluations.

Our findings align with other OMSI investigations. Expert consensus on odontogenic maxillary sinusitis emphasizes that minimally invasive endoscopic sinus surgery outperforms traditional invasive approaches, with superior function preservation and higher resolution rates (up to 99%) [32]. Our observation of rapid postoperative inflammatory marker declines aligns with analyses of odontogenic cervicofacial infections showing significant reductions in CRP and WBC [33]. The reduced postoperative infection incidence (adjusted OR = 0.19) and identification of smoking as a risk factor is supported by retrospective reviews highlighting smoking and systemic diseases as contributors to worse outcomes [17, 34]. However, contrasting results were noted in a study on vacuum sealing drainage for maxillofacial abscesses, showing longer hospitalization times and higher reoperation rates (8.51% vs. 1.47%) [21].

However, this research also has several limitations: ① The exclusion of patients with comorbidities such as diabetes and hypertension, while methodologically chosen to control for major confounders of healing and inflammation, limits the external validity of our findings. Our results are therefore most applicable to otherwise healthy OMSI patients and should be generalized with caution to populations with significant systemic comorbidities, which are known to influence infection severity and outcomes. ② The retrospective nature of this study introduces a potential for selection bias. As patients were not randomly allocated to treatment groups but were assigned based on clinical practice, there may be unmeasured confounding factors that influenced both the treatment selection and the outcomes, despite the lack of significant differences in baseline characteristics. We have taken steps to mitigate associated biases, such as ensuring overlapping enrollment periods and consistent surgical teams, and the robustness of the key findings was supported by multivariate analyses adjusting for potential confounders. ③ This research is a single-center study conducted at a single institution. The specific patient population characteristics, medical resource allocation, and expertise of the medical staff may limit the generalizability of our findings to other regions or healthcare settings. ④ The sample size was relatively small and unevenly distributed between groups, which may limit the generalizability of our findings. This imbalance, a common feature of retrospective studies, arose from the increasing clinical adoption of the novel technique over the enrollment period. The limited sample size, particularly the small number of infection events (n = 9), reduced the statistical power for the logistic regression analysis of postoperative infection, as evidenced by the wide confidence intervals. ⑤ The follow-up time was short, allowing only for the observation of short-term efficacy and safety indicators during the immediate postoperative hospitalization period. As a retrospective study based on hospital records, data on long-term outcomes such as infection recurrence, complete functional recovery, aesthetic outcomes, or scar formation were not systematically available. The long-term effects of the combined treatment regimen remain to be fully evaluated in future prospective studies designed with extended follow-up.

Conclusions

In summary, for otherwise healthy patients with OMSI, the combination of ornidazole and minimally invasive lavage with negative pressure sealing drainage demonstrates significant advantages over traditional incision and drainage. It effectively shortens wound healing and hospitalization time, provides clinically superior pain relief, and promotes a more rapid attenuation of the systemic inflammatory response in the early postoperative period, all with a favorable safety profile. The observed reduction in postoperative infection rates, while requiring further validation in larger studies, is a promising finding.

Abbreviations

OMSI

Oral and maxillofacial space infection

VAS

Visual analog scale

WBC

White blood cell

NEUT

Neutrophils

PCT

Procalcitonin

IL-6

Interleukin-6

TNF-α

Tumor necrosis factor alpha

Authors’ contributions

Chen Cheng and Xuefei Zheng wrote the main manuscript text. Jian Zhang prepared figure and tables. All authors reviewed the manuscript.

Funding

The work was not funded by any funding.

Data availability

The experimental data used to support the findings of this study are available from the corresponding author upon request.

Declarations

Ethics approval and consent to participate

This study was approved by the Ethics Committee of Wuxi Stomatology Hospital (ethics approval number: 2022−06-B010). Informed consent was waived for this retrospective study by the ethics review board. All data were obtained from routine clinical practice in accordance with the principles of the Declaration of Helsinki.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.