Bacterial Colonization of the Condyle in Patients with Advanced Mandibular Osteoradionecrosis: Analysis of Hemimandibulectomy Specimens

Abstract

Advanced mandibular osteoradionecrosis (ORN) sometimes requires extended resection (e.g., hemimandibulectomy). Bacterial infection contributes to ORN pathogenesis. To control infection and determine the extent of debridement required, an understanding of bacterial spread within sites of mandibular ORN is important. The current study used a histopathological approach to assess bacterial colonization in the mandibular condyle and elucidate possible paths of bacterial spread towards the mandibular condyle. Four hemimandibulectomy specimens were selected. Areas of bone destruction were macroscopically assessed and confirmed using hematoxylin and eosin staining. Bacterial presence within mandibular condyle was confirmed with Gram staining. Bone exposure was observed in the molar area in all specimens. Macroscopic bone destruction was apparent especially near the medial side of the cortical wall. Gram staining revealed bacterial colonization of the mandibular condyle in three of the four specimens. In conclusion, bacteria tended to spread posteriorly and through the medial side of the mandibular cortical wall. In patients with advanced ORN, the potential for bacterial colonization of the mandibular condyle should be considered during treatment.

Figure 1

Lateral three-dimensional volume rendering computed tomography images (a–d) and macroscopic images of hemimandibulectomy specimens from patients with ORN (a'–d'). Black arrowheads indicate posterior directions. Black box indicates area of intraoral exposed bone. (a) Patient 1. (a') Black circle indicates macroscopic bone destruction of the medial side of cortical bone near the inferior margin of the mandible. (b) Patient 2. (b') Black circle indicates bone destruction of the medial side of cortical bone near the mandibular angle. (c) Patient 3. (c') Black circle indicates bone destruction of the medial side of cortical bone of mandibular ramus. (d) Patient 4. (d') Black circle indicates apparent bone destruction of the medial and lateral side of cortical bone of mandibular ramus.

Figure 2

Preoperative CT images (a–c) and results of hematoxylin and eosin staining (a'–c') in patient 3. White dotted circle in (a) and (a') indicate mandibular canal. Results of Gram staining of areas indicated with white dotted boxes are shown in enlarged images (a”–c”). Severe bone destruction and inflammation in mandibular body (a') and ramus (b'). Apparent bacterial colonization is evident (a” and b”). Bone marrow hollowing and inflammatory cell infiltration (c'), as well as bacterial colonization (c”), are evident in mandibular condyle. Asterisk (∗) indicates the articular surfaces of condyle. Scale bar = 20 μm.

Figure 3

Preoperative CT images of condyles (a–c) and results of hematoxylin and eosin staining (a'–c') in mandibular condyles of patients 1, 2, and 4. Results of Gram staining of areas indicated with black dotted boxes are shown in enlarged images (a”–c”). Within the region of partial bone marrow hollowing, inflammatory cell infiltration (a') and bacterial colonization (a”) are evident in condyle of patient 1. Within the region of cortical hollowing, chronic fibrosis (b) and bacterial colonization (b”) are evident near condyle of patient 2. Although fibrosis and fatty degeneration are evident in bone marrow area (c'), no bacterial colonization is evident (c”) in condyle of patient 4. Asterisks (∗) indicate the articular surfaces of condyles. Scale bar = 20 μm.