ACID ETCHING IN COMPOSITE RESTORATIONS

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INTRODUCTION

  • Acid etching is a process by which naturally smooth tooth surface is roughend to create micromechanical interlocking of surfaces.
  • the end point of etching is creation of irregular tooth surface that appears frosty white due to light refraction.
  • recommended etching time to prepare the enamel surface for bonding is 15-20 sec.
    • primary teeth-60 sec.
    • teeth effected by fluorosis-60-120 sec.
  • 37% phosphoric acid is ideal concentration for the purpose.

Types

  • liquids
  • gels

LIQUIDS- useful when-

  • larger surface area is to be etched as they flow easily.
  • surfaces have deep grooves or fissures as it easily penetrates the irregularities.
  • applied using-
    • small cotton pellets
    • foam sponges
    • micro sponges
    • special applicator tips

GELS-

  • They were developed by adding small amount of micro fillers or cellulose as thickening agents.
  • they show less flow and higher viscosity.
  • useful when controlled applications are required such as preparation walls, bevels and margins.
  • applied using-
    • brushes
    • paper points
    • syringe applicators.

KENNEDY’S CLASSIFICATION

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  • This is the most accepted classification given by EDWARD KENNEDY.
  • The Kennedy’s classification is based on the relationship of the saddles to the natural teeth.
  • It has four main group with modifications of each of the first three of these:

CLASS-1

Bilateral edentulous area located posterior to the remaining natural teeth.

CLASS-2

Unilateral edentulous area located posterior to the remaining natural teeth.

CLASS-3

Unilateral edentulous area with natural teeth both anterior and posterior to it.

CLASS-4

Single bilateral edentulous area located anterior to the remaining natural teeth.

MERITS

  • Classification is simple and universally accepted.
  • It allows to clearly communicate, to write, or to diagnose the condition of the oral cavity in which teeth are to be replaced.
  • It permits visualization of the type of partially edentulous arches being considered.
  • Type of design can be decided.
  • Easy to apply.
  • Forms basis for Applegate, Kennedy and Swenson classification.
  • Type of support can be determined.

DEMERITS

  • Does not give proper information of teeth present and their positions.
  • Does not mention about abutment teeth.
  • Not applicable to single standing tooth.
  • It tells about spaces but not all teeth to be replaced.

FOCAL EPITHELIAL HYPERPLASIA(HECK DISEASE)

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HPV- induced local epithelial hyperplasia.

ETIOLOGY

Caused by HPV-B and HPV-32

CLINICAL FEATURES

SEX- no gender prediliction

AGE- Children

SITE- labial, lingual, buccal mucosa.

clinical presentation

  • LESION-
    • Papular in nature
    • broad based
    • same colour as skin-pale/white.
  • 0.3-1 cm, discrete ,well demarcated plaques
  • smooth surfaced/flat topped are commonly seen.
  • they cluster closely together that they give COBBLE STONE/FISSURED APPEARANCE.

HISTOLOGIC FEATURES

  • ACANTHOSIS of oral epithelium.
  • RETE RIDGE FORMATION
    • normal
    • but are indented, confluent and club-shaped
  • MITOSOID CELL
    • Result from viral alteration of the cells.
  • PAPPILARY PROJECTIONS.

TREATMENT

  • Conservative excisional biopsy.
  • Spontaneous regression is observed.

FORDYCE GRANULES

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A developmental anomaly characterized by heterotrophic collections of sebaceous glands at various sites in oral cavity.

ETIOLOGY

  • Results from inclusion in oral cavity of ectoderm having some potentialities of skin in course of development of maxillary and mandibular process during embryonic life.

CLINICAL FEATURES

  • SEX- no gender prediliction
  • AGE- adults
  • SITE- Oral mucosa

clinical presentation

  • Small yellow spots either discreatly seperated/forming relatively large plaques-projecting slightly above the surface of the tissue.
  • bilaterally symmetrical pattern.
  • most common sites include-
    • oral mucosa
    • lips
    • retromolar area
    • tongue
    • gingiva
    • frenum
    • palate

HISTOLOGIC FEATURES

  • Lobules of sebaceous duct beneath the epithelium.
  • sebaceous cells are polygonal with centrally located nucleus and foamy cytoplasm.
  • these sebaceous glands are unassociated with hair follicles.
  • may show keratin plugging.

TREATMENT

No treatment is required.