Acute Oroantral Communication Closure: Resorbable Collagen Membrane vs. Buccal Advancement Flap Outcomes
Phase: NA
Conditions: Oroantral Communication, Acute Oroantral Communication, Oroantral Fistula, Post-extraction Maxillary Sinus Communication
Sponsor: Medical University of Silesia

 
 
 
Acute Oroantral Communication 
Closure: Resorbable Collagen 
Membrane vs. Buccal Advancement 
Flap Outcomes: A Clinical Trial 
 
PCN/0022/KB1/94/20/21 
12.02.2021 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Study Protocol and Statistical Analysis Plan 
Protocol Overview and Rationale 
This investigator-initiated, prospective, non-randomized, parallel-group clinical study was 
designed to compare the clinical effectiveness and early radiographic healing associated with 
two surgical techniques for closure of acute oroantral communication (OAC) diagnosed 
within 24 hours after extraction of posterior maxillary teeth. The study was conducted at the 
Department of Dental Surgery, Faculty of Medical Sciences in Zabrze, Medical University of 
Silesia. The protocol was approved by the Institutional Review Board 
(PCN/0022/KB1/94/20/21), and all participants provided written informed consent prior to 
enrollment. 
The study hypothesis was that minimally invasive closure using a resorbable heterogeneous 
collagen membrane would better preserve soft tissue architecture and reduce postoperative 
morbidity compared with the conventional Rehrmann buccal advancement flap, while 
maintaining comparable early bone healing. 
Study Population and Enrollment 
Consecutive adult patients presenting with acute OAC within 24 hours following extraction 
of a maxillary posterior tooth were screened for eligibility according to predefined inclusion 
and exclusion criteria. Twenty-four patients were enrolled; twenty completed the full 90-day 
follow-up and were included in the final analysis. The mean defect diameter was 3.5 ± 1.0 
mm (range 2 to 5 mm), verified clinically and with limited-field CBCT on day 0. 
Interventions and Standardization 
Participants were assigned to one of two parallel treatment arms based on a predefined 
clinical protocol and the availability of the membrane technique at the time of treatment. 
Formal randomization and allocation concealment were not implemented. 
All surgical procedures were performed by the same experienced oral surgeon to minimize 
operator-related variability. Preoperative preparation, socket debridement, smoothing of 
sharp bony margins, antibiotic prophylaxis, sinus precautions, analgesic recommendations, 
and follow-up schedules were standardized across both groups. 
Experimental arm: closure using submucosal placement of a resorbable heterogeneous 
collagen membrane (Creos Xenoprotect) stabilized with horizontal mattress sutures following 
limited mucoperiosteal elevation without vertical releasing incisions. 
Control arm: closure using the classical Rehrmann buccal advancement flap involving 
trapezoidal full-thickness mucoperiosteal flap elevation with vertical releasing incisions and 
periosteal releasing incision to permit tension-free coronal advancement. 
Follow-up Schedule and Data Collection 
Clinical assessments were conducted at baseline (day 0) and on postoperative days 1, 7, 14, 
and 90. The final radiographic assessment using limited-field CBCT was performed at 
baseline and at 90 days. 
Clinical measurements (vestibular depth, keratinized gingiva width, alveolar socket 
dimensions) were performed using a calibrated WHO periodontal probe by an independent 

examiner blinded to the surgical procedure. Examiner calibration was performed prior to 
study initiation using repeated measurements in a subset of patients. 
Radiographic measurements and region-of-interest (ROI) density analyses were conducted by 
two trained investigators using standardized protocols in Romexis (v6.4) and ImageJ 
(v1.53k). Discrepancies were resolved by consensus. 
Outcome Measures 
Primary endpoint: 
• 
Change in vestibular depth from baseline to 90 days. 
Secondary endpoints: 
• 
Change in keratinized gingiva width. 
• 
Change in alveolar socket dimensions. 
• 
Postoperative pain intensity measured with the Visual Analogue Scale (VAS) at days 
1, 7, and 14. 
• 
Incidence of postoperative complications (swelling, hematoma, epistaxis, wound 
dehiscence, persistent communication, fistula formation, clinical sinusitis). 
• 
Normalized bone density at the surgical site derived from CBCT. 
Radiographic Density Methodology 
Because CBCT gray values are not directly equivalent to absolute Hounsfield Units, density 
measurements were normalized to adjacent cortical bone within the same scan to reduce 
inter-individual variability and acquisition-related bias. Regions of interest were placed at 
three standardized vertical levels of the alveolus (crestal, mid-alveolar, and apical). The 
arithmetic mean of normalized values was used for statistical analysis. 
Statistical Analysis Plan 
All analyses were performed using STATISTICA version 13.0. Continuous variables are 
presented as mean ± standard deviation. Categorical variables are presented as counts and 
proportions. 
Assumption testing: 
• 
Normality assessed with the Shapiro–Wilk test. 
• 
Homogeneity of variance assessed with Levene’s test. 
Between-group comparisons: 
• 
Independent-samples t test for normally distributed variables with equal variances. 
• 
Mann–Whitney U test when parametric assumptions were violated. 
Multiplicity control: 
The primary endpoint retained a two-sided alpha of 0.05. Because multiple secondary 
endpoints were analyzed, Bonferroni correction was applied for secondary comparisons, and 
these results were interpreted as supportive. 

Handling of missing data: 
Only participants who completed the 90-day follow-up were included in the final per-
protocol analysis. No imputation of missing values was performed. 
Power considerations: 
Given the final sample size (n = 20), the study was adequately sensitive for detecting large 
between-group differences in soft tissue outcomes but underpowered for moderate 
radiographic density effects. Therefore, CBCT density findings were prespecified as 
exploratory. 
Bias Control Measures 
• 
Single experienced surgeon to reduce procedural variability. 
• 
Independent blinded clinical assessor. 
• 
Dual-investigator radiographic analysis with consensus resolution. 
• 
Standardized postoperative management in both arms. 
• 
Objective probe-based measurements at predefined time points. 
Safety Monitoring 
Participants were monitored at each follow-up visit for adverse events, including infection, 
dehiscence, hematoma, epistaxis, persistent OAC, fistula formation, and signs of maxillary 
sinusitis. All complications were recorded prospectively. No serious adverse events related to 
the interventions were reported. 
Ethical Considerations 
The study complied with the Declaration of Helsinki and applicable institutional 
requirements. Participation was voluntary, and patients could withdraw at any time without 
affecting their treatment. Data confidentiality was maintained throughout the study. 
Protocol Limitations 
The protocol acknowledges limitations including non-randomized allocation, small sample 
size, short follow-up duration, and the known constraints of CBCT-derived density 
measurements. Findings related to bone regeneration are therefore considered hypothesis-
generating and require confirmation in adequately powered randomized controlled trials with 
longer observation periods. 
This Statistical Analysis Plan was finalized prior to database lock and outcome analysis.