Dental Anatomy Class II Amalgam Preparation
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Questions and Answers

Where are Class II lesions found?

On the proximal surfaces (sides) of posterior teeth.

What kind of cavity is a Class II lesion?

A smooth surface cavity.

Where are Class II lesions typically found in regard to contact points?

Mesially and distally below the contact points.

Explain the difference between D1, D2, and D3 caries.

<p>D1 - Just into the DEJ (outer third of dentin) - mild; D2 - Into the middle third of dentin - moderate; D3 - Inner third of dentin, closer to the pulp chamber - deep.</p> Signup and view all the answers

How do you know whether a box would be mesial or distal on a mandibular 2nd premolar?

<p>Look at the box. The bigger cusp is toward the mesial.</p> Signup and view all the answers

What does an MOD prep indicate?

<p>Caries on medial, occlusal, and distal surfaces. TWO BOXES.</p> Signup and view all the answers

How would you classify the Class II by complex?

<p>Compound.</p> Signup and view all the answers

If you have caries that involve three surfaces, how would you classify it?

<p>Complex; involves three surfaces.</p> Signup and view all the answers

Describe how the progression of Class II lesions begins.

<p>With a broad decalcification of enamel.</p> Signup and view all the answers

Describe Class II caries progression.

<p>Broad decalcification of enamel --&gt; cone of decay progresses toward dentin (x-ray) --&gt; at DEJ, decay spreads out, forms a cone of decay toward pulp --&gt; flares at DEJ once dentin reached --&gt; proximal surface intact --&gt; eventually surface breaks down/explorer can penetrate --&gt; then lesion progresses toward pulp.</p> Signup and view all the answers

What is the clinical appearance of smooth surface caries?

<p>It may not have a clinical appearance</p> Signup and view all the answers

What would you likely find if a patient has a purple-gray tint on their premolar?

<p>Very deep caries.</p> Signup and view all the answers

Describe noncavitated caries.

<p>Surface intact, opacity of the proximal surface may be present, superficial radiolucency may be present. The marginal ridge is not discolored.</p> Signup and view all the answers

Describe cavitated caries.

<p>The surface is broken, detected visually or possibly tactilely. The marginal ridge may be discolored or there could be a shadow. Radiolucency is present beyond the DEJ.</p> Signup and view all the answers

Why is the occlusal surface normally included in a Class II prep?

<p>Convenience form; extension (into central and buccal grooves) for prevention of future caries.</p> Signup and view all the answers

What area is not included in the maxillary molar prep outline for a Class II?

<p>The intact oblique ridges.</p> Signup and view all the answers

Transverse ridge is a feature of what premolar?

<p>Mandibular first premolar.</p> Signup and view all the answers

Why do you not include the transverse ridge in the mandibular first premolar Class II prep?

<p>To avoid weakening the small lingual cusp.</p> Signup and view all the answers

What is a slot prep? When is it used?

<p>It is a proximal box preparation only. We do this for composite (tooth-colored) restorations, usually - not with amalgam.</p> Signup and view all the answers

Name the different surfaces in the proximal box.

<p>Mesiobuccal, mesiolingual, axial.</p> Signup and view all the answers

Name the horizontal aspects of the Class II prep.

<p>Pulpal floor (occlusal) and gingival floor (proximal box).</p> Signup and view all the answers

The gingival floor needs to always be cut to the point where there is no contact left with the adjacent tooth.

<p>True</p> Signup and view all the answers

What is a line angle?

<p>A place where two walls meet.</p> Signup and view all the answers

What is a point angle?

<p>A place where three walls meet.</p> Signup and view all the answers

Name all the line angles you'd find in a Class II.

<p>Distopulpal line angle, linguopulpal line angle, buccopulpal line angle, axiopulpal line angle, linguogingival line angle, gingivoaxial line angle, linguoaxiogingival point angle, buccoaxiogingival point angle.</p> Signup and view all the answers

What is a linguoaxiogingival point angle?

<p>Where the lingual, axial, and gingival walls come together to form a point angle.</p> Signup and view all the answers

Is a linguopulpal line angle convergent or divergent?

<p>False</p> Signup and view all the answers

What is the most retentive part of the box?

<p>The linguoaxiogingival point angle.</p> Signup and view all the answers

Where do we condense first in the box?

<p>The linguoaxiogingival point angle.</p> Signup and view all the answers

A Class II prep box should be convergent.

<p>True</p> Signup and view all the answers

The walls of the box in the Class II prep are __________ to the occlusal table and ____________ to the long axis of the tooth.

<p>Parallel; perpendicular.</p> Signup and view all the answers

How far down does your box go?

<p>As far as you need to in order to break gingival contact.</p> Signup and view all the answers

Why is a mandibular first premolar hard to do?

<p>It has a dovetail because the pulpal floor slants.</p> Signup and view all the answers

Do the mandibular molars have a dovetail?

<p>False</p> Signup and view all the answers

A maxillary molar MO: only the _____ portion of the occlusal surface is included.

<p>Mesial.</p> Signup and view all the answers

A maxillary molar DO: only the _____ portion of the tooth is included.

<p>Distal.</p> Signup and view all the answers

What burs do you need to do Class II preps?

<p>Same as Class I: 330 pear, 245 elongated pear, 170 tapered fissure.</p> Signup and view all the answers

What is the small hatchet width?

<p>1.0 mm (10-7-14) - 8/9 for premolar.</p> Signup and view all the answers

What is the large hatchet width?

<p>1.5 mm (15-8-14) - 10/11 for molar.</p> Signup and view all the answers

What is the isthmus width for external outline form?

<p>Keep width equal to or less than 1/4 the distance between the cuspal line angles.</p> Signup and view all the answers

For retention purposes, the proximal portion of the Class II will be wider _______________ at the gingival level and narrower at the __________________.

<p>Wider buccolingually; narrower at the occlusal portion.</p> Signup and view all the answers

A wooden wedge can be placed gingival to what? Should it come in from the buccal or lingual?

<p>The contact area; lingual.</p> Signup and view all the answers

What can you place interproximally to prevent damage to adjacent teeth?

<p>A matrix band.</p> Signup and view all the answers

Where do you start your box?

<p>Always start the box proximal at the occlusal pit and work in the confines of the marginal ridge.</p> Signup and view all the answers

The proximal box is thinned with the bur as specified before, but leave _______________________

<p>A thin shell of intact enamel in contact.</p> Signup and view all the answers

Proximal box placement and size is dictated by what?

<p>Contact.</p> Signup and view all the answers

Clearance between the teeth is ______, measured with the tip of the explorer along the entire buccal, lingual, and gingival walls of the box.

<p>0.5 mm.</p> Signup and view all the answers

Occlusogingivally, our axial wall should be at least ______ long.

<p>1 mm.</p> Signup and view all the answers

Clinically, we go gingivally until we ______________________.

<p>Break contact.</p> Signup and view all the answers

It is often easiest to break contact where?

<p>Lingually.</p> Signup and view all the answers

Do you often need a reverse S curve on the lingual?

<p>False</p> Signup and view all the answers

What would you do about a sharp axiopulpal line angle?

<p>Change it; where pulpal and axial wall meets, needs to be round.</p> Signup and view all the answers

When do we do a dovetail?

<p>In premolars that don't have two lingual cusps.</p> Signup and view all the answers

Facial and lingual walls form a 90-degree surface with the proximal surface of the tooth called a?

<p>Butt joint.</p> Signup and view all the answers

Study Notes

Class II Amalgam Preparation Overview

  • Class II lesions occur on the proximal surfaces of posterior teeth.
  • These cavities are classified as smooth surface cavities.

Cavity Classification

  • Class II lesions are commonly found mesially and distally below contact points.
  • Caries can be classified into three categories:
    • D1: Enamel to outer third of dentin (mild)
    • D2: Middle third of dentin (moderate)
    • D3: Inner third closer to pulp chamber (deep)

Cavity Preparation and Design

  • An MOD (mesial-occlusal-distal) preparation involves two boxes indicating caries on three surfaces.
  • Class II cavities are termed compound as they involve two surfaces, while three surfaces indicate a complex cavity.
  • The progression of Class II lesions begins with broad decalcification of enamel.

Caries Progression

  • Decay initially forms a cone shape that spreads horizontally at the dentin-enamel junction (DEJ), forming a cone toward the pulp.
  • Clinical appearance of smooth surface caries can be subtle, sometimes showing only opacity over the marginal ridge.

Types of Caries

  • Noncavitated caries exhibit a surface intact with possible opacity and superficial radiolucency.
  • Cavitated caries show visual or tactile breaks in the surface and may be accompanied by discoloration or radiolucency beyond DEJ.

Class II Preparation Details

  • The occlusal surface is usually included in Class II preparations for convenience form and future caries prevention.
  • For maxillary molar preparations, intact oblique ridges are not included.

Instrumentation and Techniques

  • Class II preparation uses burs similar to Class I: 330 pear, 245 elongated pear, and 170 tapered fissure.
  • The width of the hatchet for premolars is 1.0 mm, and for molars, it is 1.5 mm.

Box Configuration

  • A Class II box starts proximal at the occlusal pit and should be wider buccolingually at the gingival level but narrower at the occlusal level.
  • Clearance between adjacent teeth during preparation should be 0.5 mm.

Special Features in Preparation

  • The proximal box's size is determined by the contact point, ensuring the gingival floor is cut to avoid any remaining contact.
  • A sharp axiopulpal line angle should be rounded to ensure smooth transitions.

Matrix and Wedges

  • Wooden wedges are placed gingival to the contact area, ideally coming from the lingual side.
  • A matrix band can be used interproximally to protect adjacent teeth during restoration.

Miscellaneous

  • The lingual and axillary walls should ideally create a converging form in preparation.
  • Dovetail preparation is specific to premolars lacking two lingual cusps to enhance retention.

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Description

This quiz covers the overview of Class II amalgam preparations, focusing on cavity classification, preparation design, and caries progression. It details the specific characteristics of Class II lesions and their clinical implications in dentistry.

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