Maxillary sinusitis of endodontic origin: a scoping review of definitions, diagnosis, and management.

A. Background and rationale The floor of the maxillary sinus is intimately related to the apices of the maxillary posterior teeth, providing a natural conduit through which pulpal and periapical disease can extend into the sinus. Maxillary sinusitis arising from such endodontic pathology — pulp necrosis, apical periodontitis, or failing root canal treatment of maxillary posterior teeth — was formally designated maxillary sinusitis of endodontic origin (MSEO) by the American Association of Endodontists in 2018, in order to distinguish the endodontic subset from other odontogenic causes such as implants, extractions, bone grafts, periodontal disease and oroantral communications. Apical periodontitis is recognised as the principal endodontic source. Despite increasing recognition, the condition remains inconsistently defined and frequently overlooked across dentistry, otolaryngology and radiology. A systematic review of diagnostic criteria for odontogenic sinusitis documented extreme heterogeneity in how the condition is diagnosed, varying by imaging modality, specialty and case definition (Allevi et al., 2021). Terminology is used interchangeably (odontogenic, dental and endodontic sinusitis; sinus mucosal change versus rhinosinusitis), and the cone-beam computed tomography (CBCT) signs proposed for the endodontic subset — mucosal thickening, periapical osteoperiostitis (PAO) and periapical mucositis (PAM) — depend on thresholds (for example, mucosal thickening greater than 2 mm) that are contested. Reported management spans non-surgical root canal treatment, endodontic microsurgery, extraction, endoscopic sinus surgery and multidisciplinary care, with no consensus on indications or sequencing. The evidence underpinning MSEO is correspondingly heterogeneous in design — ranging from case reports and case series to retrospective CBCT cross-sectional and cohort studies, and more recently machine-learning detection studies — and conceptually fragmented. Existing reviews address only parts of the field: diagnostic criteria for the broader odontogenic category (Allevi et al., 2021), global prevalence (Vitali et al., 2023), or narrative overviews of diagnosis. To date, no review has systematically mapped the full clinical pathway — definitions, diagnosis, treatment and outcomes — specifically for the endodontic subset. Where the purpose is to chart the extent, range and nature of available evidence and to clarify inconsistently used concepts rather than to estimate a pooled effect, a scoping review is the appropriate and recommended approach (Arksey & O'Malley, 2005; Munn et al., 2018; Peters et al., 2020). This protocol describes a scoping review that will map the current knowledge on MSEO across definitions, diagnosis and management, and will identify knowledge gaps to guide future research and to support more consistent interdisciplinary clinical recognition. B. Review objective and questions The objective of this scoping review is to systematically map the extent, range and nature of the evidence on maxillary sinusitis of endodontic origin — how it is defined, diagnosed and managed — and to identify knowledge gaps relevant to future research and clinical practice. Primary review question. What is known about the definition, diagnosis and management of maxillary sinusitis of endodontic origin? Sub-questions: 1. How is MSEO defined, and what terminology and diagnostic criteria are used across studies and specialties? 2. What diagnostic methods are reported (clinical and endodontic testing; radiographic signs on CBCT/CT including mucosal thickening, PAO, PAM and opacification; microbiology), and what thresholds are used to define disease? 3. What treatment and management approaches are reported (non-surgical root canal treatment, endodontic microsurgery, extraction, endoscopic sinus surgery, antibiotics, multidisciplinary care)? 4. What outcomes are reported, and how are they measured (radiographic resolution, symptom resolution, healing rates, follow-up duration)? 5. What are the characteristics of the evidence base (study designs, populations, settings, geography, time), and where are the knowledge gaps?