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- NEETMDS- courses
NEET MDS Lessons
Oral Pathology

  • Dentigerous Cyst (Follicular Cyst):

    • Most common Developmental Odontogenic Cyst.

    • Always associated with the crown of an unerupted/impacted tooth.

    • Derived from Reduced Enamel Epithelium (REE).

    • Differential diagnosis: Eruption cyst, Paradental cyst (also from REE).

  • Nasopalatine Duct Cyst (Incisive Canal Cyst/Median Anterior Maxillary Cyst - MAMC):

    • Most common Developmental Non-odontogenic Cyst.

    • Located in the midline of the anterior maxilla.

  • Radicular Cyst (Periapical Cyst):

    • Most common Odontogenic Cyst overall.

    • Always associated with a non-vital tooth.

    • Inflammatory origin.

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

    • Primordial Cyst: An OKC found in place of a missing tooth.

    • Protein Content: Less than 4 gm/dL.

    • Aggressive Behavior: High mitotic activity, high PCNA index, and Ki67 activity.

    • Derived from Rests of Serres (remnants of dental lamina).

  • Mucocele:

    • Common term for:

      • Mucous Extravasation Phenomenon (Pseudocyst): No epithelial lining.

      • Mucous Retention Cyst (True Cyst): Has an epithelial lining.

  • SLE → IgG, IgM, IgA deposits at BMZ + superficial lamina propria
  • Lichen Planus (Erosive/Atrophic) → Autoimmune T-cell; BMZ involvement
  • Cicatricial Pemphigoid → Subepidermal blistering from anti-BMZ antibodies

  • Actinomycosis (Sulfur Granules):

    • Yellow sulfur granules: Are actually bacterial colonies.

    • Histopathology: Colonies appear "cotton wool" shaped. (Note: "Cotton wool appearance" is seen radiographically in Paget's disease).

  • Tuberculosis (TB):

    • Diagnosis (Gold Standard): Presence of acid-fast bacilli in sputum.

    • Staining Method: Ziehl-Neelsen staining method is used to identify acid-fast bacilli.

    • Scrofula: TB of cervical lymph nodes.

    • Lupus Vulgaris: TB of skin.

  • Tongue & Gingival Appearance in Systemic Conditions:

    • Strawberry tongue and Raspberry tongue: Seen in stomatitis of Scarlet Fever.

    • Strawberry Gingivitis: Seen in Wegener's Granulomatosis.

 Streptococcus mutans Mechanism

  • Key Substrate: Sucrose
  • Metabolic Pathway: Phosphorylation → Glycolysis → Lactic acid
  • Enzymes:
    • Invertase: Converts sucrose to glucose + fructose
    • Glucosyltransferase (GTF): Forms sticky glucans
    • Fructosyltransferase (FTF): Produces fructans

Actinomyces naeslundii

  • Fimbriated surface → fuzzy texture
  • Type 1 fimbriae: Bind tooth surfaces/collagen
  • Type 2 fimbriae: Bind galactose/galactosamine (epithelial/bacterial targets)

  • Inverted Pear-shaped Radiolucency: Globulomaxillary cyst.

    • Associated teeth need not be non-vital.

    • Klestadts’s cyst: Soft tissue variant of Globulomaxillary cyst.

  • Tear Drop-shaped Radiolucency: Lateral Periodontal Cyst.

    • Associated teeth are vital.

  • Cluster of Similar Cysts / Cluster of Grapes: Botryoid Odontogenic Cyst.

Macroglossia

  • Feature: Crenated (scalloped) lateral tongue borders

Lymphangioma of Tongue

  • Appearance: Tapioca pudding/Frog's egg

Geographic Tongue

  • Associated With: Fissured tongue
  • Histopathology: Similar to psoriasis
  • Key Feature: Munro's abscesses

Median Rhomboid Glossitis

  • Unique Sign: "Kissing lesion" on soft palate due to tongue contact

Hairy Tongue

  • Misnomer: Elongated filiform papillae—not actual hair

Acute suppurative osteomyelitis

  • Serious sequela of periapical infection.
  • Leads to spread of pus through the medullary cavities of bone.
  • Depending upon the main site of involvement of bone, can be of two types-
  1. Acute intramedullary
  2. Acute subperiosteal

Acute Intramedullary Osteomyelitis

CLINICAL FEATURES:

  • Patient experiences dull , continuous pain , indurated swelling forms over the affected region of jaw involving the cheek , febrile.
  • When mandible involved, loss of sensation occurs on lower lip on affected side due to involvement of inferior alveolar nerve.
  • Teeth become loose later along with tender on percussion
  • Pus discharge , trismus , foul smell , regional lymphadenopathy , weakness

RADIOGRAPHIC FEATURES

  • Earliest radiographic change is that trabeculae in involved area are thin, of poor density & slightly blurred.
  • Subsequently multiple radiolucencies appear which become apparent on radiograph.
  • In some cases there is saucer shaped area of destruction with irregular margins.
  • Loss of continuity of lamina dura, seen in more than one tooth.

HISTOLOGIC FEATURES:

  • Dense infiltration of marrow by polymorphonuclear leukocytes.
  • Bone trabeculae in involved site (sequestrum) are devoid of cells in the lacunae.
  • separation of considerable portions of devitalized bone.

 

Acute Subperiosteal Osteomyelitis

CLINICAL FEATURES

  • Pain , febrile condition , i/o and e/o swelling , parasthesia
  • Bone involvement limited to localized areas of cortex.
  • Pus ruptures rapidly through the overlying cortex, tracks along the surface of mandible under the periosteal sheath.
  • Elevation of periosteum from cortex is followed eventually by minute cortical sequestration.

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