• Retention Cyst of Maxillary Sinus: Characteristic X-ray feature is a dome-shaped/hemispherical radio-opacity in the antrum.

• Abfraction: Appears as a subgingival, deep, narrow "V" shaped notch in the cervical areas of teeth.

• Abrasion vs. Abfraction:

  • Abrasion: Commonly affects cuspids and bicuspids.

  • Abfraction: Affects only a single tooth (adjacent tooth is unaffected).

• Erosion (Gastric): Erosion due to gastric secretions is termed Perimolysis.

• Pioneer Bacteria: S. mutans are considered pioneer bacteria as they multiply and synthesize extracellular matrix polymers, initiating biofilm formation.

• Caries Progression - Key Bacteria:

  • Initiation of caries: S. mutans.

  • Progression of caries / Dentinal caries: Lactobacillus.

  • Root surface caries: Actinomycetes.

• Body of the Lesion (Enamel Caries): Shows increased prominence of the striae of Retzius.

• Sugar Intake: Frequency of sugar intake is of more importance than the total amount consumed in caries development.

Chronic Osteomyelitis

• As soon as pus drains intra or extraorally, condition ceases to spread and chronic phase commences.
• Infection is localized but persistent as bacteria are able to grow in dead bone inaccessible to body’s defenses.

Clinical features

• Primary – insidious in onset , slight pain , gradual increase in jaw size.
• Secondary - Pain is deep pain and intermittent, temperature fluctuations , pyrexia , cellulitis eventually leading to abscess
• New bone formation leads to thickening causing facial asymmetry.
• Thickened or “wooden” character of bone in cr sec osteomyelitis.
• Eventually cures itself as the last sequestra is discharged.

Radiographic Features

• Trabeculae in the involved area become thin or appear fuzzy & then lose their continuity.
• After some time “moth eaten” appearance is seen
• Sequestra appear denser on radiographs.
• Where the subperiosteal new bone formation , the new bone is superimposed upon that of jaw, “fingerprint” or “orange peel” appearance is seen
• Cloacae seen as dark shadows passing through opacity.

Histologic features

• Areas of acute and subacute inflammation in the cancellous spaces of the necrotic bone.
• Foci of acute inflammation
• Active osteoclastic resorption of bone noted in peripheral portions

Chronic Subperiosteal Osteomyelitis

• Cortical plate deprived of its blood supply undergoes necrosis, underlying medullary bone  is slightly affected.
• Multiple small sequestra form, eventually discharged through sinuses with pus.
• Following extrusion of sequestra, healing occurs.
• Spontaneous drainage poor in submassetric area.
• Much of  body of mandible is lost due to poor central blood supply of the region.

D/D

• Paget’s disease – particularly wen periosteal bone is involved
• Fibrous dysplasia
• Osteosarcoma

Chronic sclerosing osteomyelitis

– focal

- diffuse

Focal Sclerosing Osteomyelitis

Clinical features

• Most commonly in children and young adults, rarely in older individuals.
• Tooth most commonly involved is the mandibular third molar presenting with a large carious lesion.
• No signs or symptoms other than mild pain associated with infected pulp.

Radiographic features

• Entire root outline always visible with intact lamina dura.
• Periodontal ligament space widened.
• Border smooth & distinct appearing to blend into surrounding bone

D/D for focal sclerosing osteomyelitis

• Local bone sclerosis
• Sclerosing cementoma
• Gigantiform cementoma

Treatment & prognosis

• Affected tooth may be treated endodontically or extracted.
• Sclerotic bone  not attached to tooth and remains behind after tooth is removed.
• This dense area may not get remodeled.
• Recognizable on bone years later and is referred as bone scar.

Diffuse Sclerosing Osteomyelitis

• May occur at any age, most common in older persons, esp in edentulous mandibles
• vague pain, unpleasant taste.
• Many times spontaneous formation of fistula seen opening onto mucosal surface to establish drainage
• Slowly progressive, not particularly dangerous since it is non destructive & seldom produces complications

Radiographic features

• Diffuse patchy, sclerosis of bone – “cotton wool” appearance
• Radiopacity may be extensive and bilateral.
• Due to diffuse nature, border between sclerosis & normal bone is often indistinct

D/D for DIFFUSE sclerosing osteomyelitis

FLORID OSSEOUS DYSPLASIA

SCLEROTIC CEMENTAL MASSES

TRUE CHR DIFFUSE SCLEROSING OSTEOMYELITIS

FIBROUS DYSPLASIA

Treatment & Prognosis

• Resolution of adjacent foci of chronic infection often leads to improvement.
• Usually too extensive to be removed surgically,
• Acute episodes treated with antibiotics.

• Calcifying Odontogenic Cyst (COC) / Gorlin Cyst: Characterized by Ghost Cells.

• Aneurysmal Bone Cyst (ABC): Associated with a "blood-soaked" appearance on gross examination.

• Radicular Cyst - Common Site: Maxillary anterior teeth (due to higher incidence of trauma).

• Odontogenic Keratocyst (OKC) / Keratocystic Odontogenic Tumor (KCOT):

  • Most common site: Posterior mandible (similar to ameloblastoma).

  • Expansion: Tends to expand antero-posteriorly; buccal and lingual expansion seen in late stages.

  • Basal layer histology: Tall columnar cells with palisaded nuclei – "row of tombstones" or "picket fence appearance."

  • Classification: Now considered a benign odontogenic neoplasm (KCOT) in recent WHO classifications.

• Hyperplastic Candidiasis: The only form of candidiasis that is non-scrapable. Often appears as admixed white and red areas, known as speckled leukoplakia or erythroleukoplakia.

• Median Rhomboid Glossitis: Etiology is controversial (developmental vs. fungal); if forced to choose, developmental.

• Gilchrist's Disease: Another name for North American Blastomycosis.

• Mucormycosis: More common in diabetic patients. Has a strong propensity to invade blood vessels.