Medial Sigmoid Depression of the Mandibular Ramus as a Lesion-Mimicking Anatomical Variation: A Systematic Review.

Andy Wai Kan Yeung,Natalie Sui Miu Wong

doi:10.3390/ijerph18084271

Abstract

(1) Background: Medial sigmoid depression (MSD) of the mandibular ramus is an anatomical variation that resembles non-odontogenic cystic lesion. (2) Aim: The aim of this systematic review was to survey the literature to identify the relevant journal publications, reveal their scientific impact in terms of citations and compare the reported prevalence of MSD. (3) Materials and methods: PubMed, Google Scholar, Scopus and Web of Science were queried to identify relevant publications. The search string was: “medial depression of mandibular ramus” OR “medial depression of the mandibular ramus” OR “medial depression of the mandibular rami” OR “medial depression of mandibular rami” OR “medial sigmoid depression”. (4) Results: Eight studies were identified. Dry mandibles and patient dental panoramic radiographs were evaluated in four and seven of the eight studies, respectively. The prevalence of MSD varied from 20.2% to 82.0%. In male and female patients, the prevalence was 18.3–76.0% and 22.0–64.0%, respectively. MSD tended to occur bilaterally and most prevalent in patients with Angle’s Class II occlusion. The semilunar and triangular shapes were more common than teardrop and circular shapes. The most cited study had 12 citations. (5) Conclusions: MSD was a seldom investigated and cited anatomical variation that was not uncommon. Its recognition should be further promoted.

Highlights

Four decades have lapsed since the publication of this pioneer work in the “Triple O” journal. This anatomical entity was not indexed by Terminologia Anatomica and common dental radiology textbooks such as the ones by Whaites and Drage [2], White and Pharaoh [3] and Koenig et al [4]
On a dental panoramic radiograph, the medial sigmoid depression may present as a radiolucent lesion inferior to the sigmoid notch that may or may not be connected to the latter (Figure 1A)
The radiolucency may resemble a mandibular nonodontogenic cystic lesion that could lead to a dentist referring the patient to receiving additional advanced three-dimensional imaging with increased radiation dose

Summary

Introduction

Four decades have lapsed since the publication of this pioneer work in the “Triple O” journal (known as Oral Surgery, Oral Medicine, Oral Pathology at that time). This anatomical entity was not indexed by Terminologia Anatomica and common dental radiology textbooks such as the ones by Whaites and Drage [2], White and Pharaoh [3] and Koenig et al [4]. Dentists are much more aware of the Stafne cavity ( known as Stafne cyst, defect or lacuna) that presents as a mandibular bone depression commonly located in the lingual posterior region of the mandible [6]. A common belief is that a hyperplastic or hypertrophic lobe of the major salivary glands may exert pressure upon the cortex of

Methods

Results

Discussion

Conclusion