Restorative Dentistry PDF

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RESTORATIVE DENTISTRY

Introduction to Operative Dentistry - History, Factors and Advances Definition -

“Operative dentistry is the art and science of the diagnosis, treatment, and prognosis of defects of teeth that do not require full coverage restorations for correction. Such treatment should result in the restoration of proper tooth form, function, and esthetics while maintaining the physiologic integrity of the teeth in harmonious relationship with the adjacent hard and soft tissues, all of which should enhance the general health and welfare of the patient.” - Sturdevant

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Operative Dentistry is the art and science of the prevention, diagnosis, treatment and prognosis of defects in the enamel and dentin of individual teeth.

Operative Dentistry versus Restorative Dentistry Restorative Dentistry - The branch of dentistry that deals with the restoration of diseased, injured, or abnormal teeth to normal function, as by crowns. Is this the same as Operative Dentistry? History of Operative Dentistry

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Operative Dentistry was considered to be the entirety of the clinical practice of dentistry.

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Has been recognized as the foundation of dentistry and the base from which most other aspects of dentistry evolved.

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In United States, dentistry originated in the 17th century when several barbers were sent from England.

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The practice of these early dentists consisted mainly of tooth extraction and practice of dentistry during the founding year was not based on scientific knowledge.

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Baltimore College of Dental Surgery in 1840 ⇒ dental education

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Harvard University in 1867 ⇒ dental program

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In France, Louis Pasteur discovered the role of microorganisms in disease ⇒ have a significant impact on the developing dental + medical profession.

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In United States, G.V. Black became the foundation of the dental professions ⇒related the clinical practice of dentistry to a scientific basis.

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The scientific foundation for operative dentistry was further expanded by Black’s son, Arthur Black.

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Others made significant contributions in the early development of Operative Dentistry: *

Charles E. Woodbury: pioneered gold foil as teeth filling, designed 400 dental instruments

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E.K. Wedelstaedt: understudy of GV Black, invented the Wedelstaedt enamel chisel

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George Hollenback: designed dental instruments, standardized the criteria for manipulating amalgam

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Joseph Lister: pioneer of antiseptic surgery, Listerine was named after him

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Operative Dentistry plays an important role in enhancing dental health and new branched into dental specialties.

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Today, Operative Dentistry continues to be a most active component of most dental practice.

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Epidemiologically, demand for Operative Dentistry will not decrease in the foreseeable future.

Goal of Dental Science *

Elimination of disease and restoration of oral health, form and function.

Function and Purpose *

An understanding and appreciation for infection control.

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Examination not only the affected tooth but also the oral and systemic health of the patient.

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A diagnosis of the dental problem and must be correlated with other bodily tissues.

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A treatment plan that has a potential to return the affected area to a state of health and function.

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An understanding of material to be used to restore the affected area with a realization of both the material limitations and demands.

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An understanding of the oral environment into which the restoration will be placed.

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To understand the biological basis and function of the various tooth components and supporting tissues although the knowledge of correct dental anatomy

Purposes of Operative Dentistry *

DIAGNOSIS - Includes restoring form, function, phonetics, and esthetics.

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RESTORATION - Preservation of the vitality and periodontal support of remaining tooth structure.

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PRESERVATION - Preventing further loss of tooth structure by stabilizing an active disease process.

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INTERCEPTION - To prevent any recurrence of the causative disease and their defect.

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PREVENTION - Proper diagnosis is vital for treatment planning.

Consideration for Operative Dentistry *

The placement of a restoration in a tooth requires the dentist to: *

Practice applied human biology + microbiology

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Possess highly developed technical skills

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Demonstrate artistic abilities

Indications for operative procedure *

Dental caries

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Tooth wear

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Trauma

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Developmental defect

Dental Caries

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Dental caries is an infectious microbiological disease of the teeth that results in localized dissolution and destruction of the calcified tissue, caused by the action of microorganisms and fermentable carbohydrates.

Tooth Wear *

Maybe defined as the surface loss of dental hard tissues other than by caries or trauma.

Trauma *

Traumatic injuries are acquired suddenly.

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May involve the hard dental tissues and the pulp ⇒ required immediate operative management.

Developmental Defect *

Teeth do not always develop normally and there are a number of defects in tooth structure or shape which occur during development and become apparent on eruption.

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Teeth are often unsightly or prone to excessive tooth wear ⇒ require restoration to: *

Improve appearance or function

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Protect the underlying tooth structure

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Examples: *

Enamel hypoplasia

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Hypomineralized enamel

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Enamel fluorosis

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Tetracycline stain

Factors Affecting the Practice of Operative Dentistry *

Because of the dynamic status of dental practice, many developments and advancements will occur in the future.

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Advances in technology, science and materials will have a significant impact on the future of and demand for dental practice.

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Factors: *

Demographics ⇒ population ↑ and will change

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Economic factors

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Dental health

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Dental manpower

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Dentist must continue to broaden its knowledge on biologic basis.

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Practitioners must continually familiarize themselves with the advances being made.

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Increased research activity and continued practitioner adaptability will result in improved oral health of population throughout the world.

Advances in the field of Operative Dentistry *

Many significant advancements in health care occurred in the twentieth century; included in these advancements are genetic alterations, genetic engineering, public education, vaccines, fluoridation, x-rays, computed tomography (CT) scans, magnetic resonance imaging (MRI), antibiotics, ultrasound procedures, and sanitation

Advances – Caries Detection *

DIAGNOdent - uses a pulsed red light to illuminate the tooth and analyses the emitted fluorescence from bacterial products which changes with tooth demineralization.

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Digital Imaging Fiber-Optic Transillumination - DIFOTI uses visible light, for the detection of caries on approximal, smooth, and occlusal surfaces. DIFOTI uses the scattering of light by carious tissue as a method of distinguishing it from healthy enamel.

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Fiber-Optic Transillumination - FOTI is as accurate as a detailed visual inspection in detecting occlusal caries

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Quantitative Light-Induced Fluorescence - The quantitative lightinduced fluorescence (QLF) system uses a blue light to illuminate the tooth, which normally fluoresces a green color.

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More Accurate RADIOGRAPHS

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Electrical Conductance - uses the increase in electrical conductivity of a tooth when it is demineralized

Advances – Caries Removal *

Lasers - Traditional removal of carious dentin with a bur does involve some discomfort.

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Advantage: absence of vibration, which alleviates discomfort experienced s.

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Disadvantage: absence of tactile contact à make detection of softened dentin difficult for the dentist.

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Polymer Bur - Boston (2000) has described a polymer bur that only removed softened and infected dentin and not normal dentin. The cutting elements of the bur were made of a softer polyamide/imide polymer material

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Micropreparation Burs - The Fissurotomy Bur is designed to allow exploration of the fissure with minimal removal of enamel.

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Air Abrasion (or Kinetic Cavity Preparation) - uses a stream of small aluminum oxide particles, that impact the caries and abrade it away.

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Photoactivated Disinfection - uses a disinfectant solution that is applied to deep caries, allowed to penetrate into the remaining softened dentin

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Carisolv Gel - a chemomechanical method of removing dental caries that is minimally invasive

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Atraumatic Restorative Treatment - first introduced in rural areas of developing countries; soft caries is removed with hand instruments and the cavity restored with a glass ionomer restoration.

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Caries-Detector Dyes

Advances in Materials *

Better composites

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Use of ceramic inserts - Ceramic inserts reduce the amount of polymerization shrinkage by reducing the bulk of resin composite needed to restore the tooth.

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Nanotechnology - With these new “nanocomposites,” the esthetics are better as the resin composite blends with the surrounding tooth enamel, while strength is not compromised

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Packable Composite Resin Materials - Several manufacturers have introduced “packable” composite resin materials, which claims to make it easier during insertion to obtain a contact point with the adjacent teeth.

Advances in Techniques *

“Total Etch” Technique - simultaneous etching of both enamel and dentin

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Pit and Fissure Sealants - Fissure sealants are indicated to protect the occlusal surface of newly erupted teeth in caries-prone children

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Preventive Resin Restorations - These restorations are indicated when occlusal caries has involved a minimal amount of dentin

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The “Sandwich” Technique - Glass ionomer is sandwiched between the teeth and composite. Composite resin has better mechanical properties but does not have the chemicomechanical retention that glass ionomer has. The technique is indicated in those patients with a high caries rate who require large posterior tooth restorations.

Oral Anatomy in Relation to Operative Dentistry Oral Anatomy & Restorative Dentistry 

Knowledge of correct tooth anatomy is important in the restoration of teeth. “FUNCTION depends on FORM”

The individual form of a tooth and the contour relationships with adjacent & opposing teeth are major determinants of function in  Mastication  Esthetics  Speech  Protection 

Classes of teeth: form & function

Tooth form predicts the function of teeth  Incisors: cutting, esthetics, phonetics  Canines: seizing, piercing, tearing of food  Premolars: tearing, grinding food  Molars: crushing, grinding, chewing

Main Functions of Teeth Normal tooth form & proper alignment ensure these functions are served: – Mastication – Esthetics – Speech – Protection of supporting tissues Physiology of Tooth Form 

Contours

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Proximal Contact Areas

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Embrasures

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Cusps, grooves, fossae, ridges

Contours Facial & lingual Convexities: Location: – Cervical 3rd on facial surfaces of all teeth & lingual of incisors, canines

– Middle 3rd on lingual of posterior teeth Contours Functions of the Facial & lingual convexities: 

Protects and stimulates supporting tissues during mastication

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Deflects food to gently massage gingiva

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Altering the Facial & lingual convexities/contours:

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Too great curvature = inadequate stimulation of gingiva

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Too little contour = irritation & trauma to soft tissues

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Overcontouring – will result in: flabby, red-colored, chronically inflamed gingiva and increased plaque retention

Proximal Contours Proper proximal contour provides: 

Contacts with adjacent teeth which prevents food impaction

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Adequate embrasure space gingivally for the gingiva, supporting bone, vessels & nerves

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Refers to the area of the proximal height of contour of the mesial or distal surface of the tooth that contacts its adjacent tooth in the same arch.

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Upon eruption, there initially is a contact point.

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This becomes a contact area as a result of proximal wear.

Functions of properly formed & located proximal contacts: 

Promote normal healthy interdental papillae

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Stabilizes & maintains integrity of dental arches

Altering these proximal contacts may result in: 

Food impaction

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Periodontal disease

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Caries

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Possible tooth movement

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Halitosis

Location: 

Incisal 3rd in maxillary & mandibular central incisors

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Facial to center of proximal surface facio-lingually

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Posteriorly, contacts are positioned lower cervically: junction of incisal & middle 3rd or in middle 3rd.

Embrasures 

V-shaped spaces that originate at the proximal contact areas between adjacent teeth

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Named for the direction toward which they radiate: facial, lingual, incisal or occlusal, gingival

 Functions: 

Provide escape of food from the occlusal surfaces during mastication

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Gingival embrasure houses the interdental papilla

 Results of altering the embrasures: 

Too large embrasures = food may be forced into interproximal space by an opposing cusp

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Too small gingival embrasure = may crowd in gingival tissue

Functional Cusps 

Functional cusps: These cusps contact the opposing teeth in their corresponding facio-lingual center on a marginal ridge or a fossa

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Characteristics: – They contact the opposing tooth in occlusion. – They support the vertical dimension of the face.

– They are nearer the faciolingual center of the tooth than nonfunctional cusps. – Their outer incline has the potential for contact. – They have broader, more rounded cusp ridges than nonfunctional cusps. Non-Functional Cusps 

overlap the opposing tooth without contacting the tooth

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These cusps have sharper cusp ridges that serve to shear food as they pass close to the supporting cusp ridges during chewing strokes

Histology in Relation to Restorative Dentistry Structures of the Teeth: Enamel  formed by cells called ameloblasts, which originate from the embryonic germ layer known as ectoderm  enamel is thicker at the incisal and occlusal areas of a tooth and becomes progressively thinner until it terminates at the CEJ  Thickness: 2 mm at the incisal ridges of incisors, 2.3 to 2.5 mm at the cusps of premolars, 2.5 to 3 mm at the cusps of molars Chemical Composition:

 95-98 % inorganic = mostly hydroxyapatite  1-2 % organic  4 % water Structural composition:  Enamel rods or prisms  Rod sheath or inter-rod substance  Cementing inter-rod substance Enamel Rods:  Densely packed & intertwined in wavy course  Extends from DEJ to external surface  Oriented perpendicular to DEJ & tooth surface, except in cervical of permanent teeth  Composed of millions of tightly packed apatite crystals  At the head of the rod: long axis of crystallites are parallel to rod long axis  At the tail: inclined up to 65˚ to prism axis **Why do we need to know the orientation of the crystals?:

 To know how susceptible the enamel is to caries  Head (body): the dissolution process occurs more in this area, prone to acid attack  Tail and periphery of the head: less prone **SEM shows the direction of the enamel crystals within a single enamel rod Physical Properties:  Hardest substance of the human body  High modulus of elasticity = very brittle  Low tensile strength = rigid  Requires a dentin base to withstand forces  Semitranslucent = color depends on color of dentin, enamel thickness, amount of stain in enamel  Loss of loosely-bound water = change in color  Permeable to certain ions & molecules  Incapable of self-repair

Important Anatomic Structures: Enamel tufts:

 Hypomineralized structures of enamel rods & inter-rod substance that project from the DEJ into enamel  May play role in spread of caries Enamel Lamellae  Thin, leaflike faults between enamel rods that extend form the enamel surface to the DEJ  Weak area predisposing tooth to bacterial entry & spread of caries Enamel Spindles:  Extensions of odontoblastic processes into enamel  May serve as pain receptors Dentino-enamel Junction  Scalloped & wavy in outline  Hypermineralized zone about 30 microns thick

Dentino-enamel junction (Enamel, DEJ, Dentin)  Structures of the Teeth: Dentin

 formed by cells called odontoblasts, which originate from the embryonic germ layer known as mesoderm  forms the largest portion of the tooth structure extending almost the full length of the tooth  forms the walls of the pulp cavity Chemical Composition:  75 % inorganic  20 % organic = collagen  5 % water Structural Composition:  Dentinal tubules: small canals with odontoblastic processes (Tomes fiber) extending from DEJ to pulp & dentinal fluid  Peritubular dentin: lining each tubule  Intertubular dentin: dentin between tubules

Dentinal Tubules:  Number of tubules: 15,000-20,000/mm2 at DEJ; 45,000-65,000 at the pulp

 Lumen diameter increases towards pulp  Course: slight S-curve in crown, straighter in ridges, cusps, roots  Ends of tubules perpendicular to DEJ Types of Dentin:  Primary dentin: forms during dentinogenesis until 3 yrs post-eruption  Secondary dentin: physiologically forms without external stimuli; takes a different directional pattern than primary dentin  Tertiary/reparative dentin: forms in response to moderate level irritants; chemically & structurally different, highly atubular Physical Properties:  Softer than enamel but harder than bone & cementum  Becomes harder with age ...