GENDT830: A Semester in Review from Dr. Perry

What is 'Piezoelectricity' in the context of dentin?

A small electrical charge generated when teeth are mechanically deformed; it seems to affect dentin more than enamel.

Why should Mylar strips be preferred over manual polishing where possible?

The surface against a Mylar strip is the smoothest possible finish. Polishing is essentially creating progressively smaller scratches; once you touch the surface with a bur/disc, it will never be as smooth as the Mylar finish.

What is Biodentine and how is it used in VPT?

A calcium silicate material used for repair. It is placed 1.5 to 3mm thick over exposed pulp. It sets in 10-12 minutes and mimics the mechanical behavior of human dentin.

Define 'Hue' in the context of tooth color.

Hue distinguishes one color family from another (e.g., red, yellow). It corresponds to the wavelength of light reflected by the tooth.

Which radiographic view is the standard for detecting Class II lesions not visible clinically?

Bitewing radiographs.

What is an 'Endocrown' and when is it indicated?

A single-piece restoration (core+crown) usually made of ceramic. It requires preparation into the pulp chamber and offers better stress distribution when traditional ferrule is incredibly difficult to achieve.

What are the three main goals of VPT?

1. Treat reversible pulpal injuries. 2. Neutralize existing pulpal contamination. 3. Prevent further contamination via microleakage.

What makes Dentin more difficult to bond to than Enamel?

Dentin has higher water content, presence of organic collagen, and fluid-filled tubules. It also contains proteases that can degrade the bond over time.

What precaution should be taken if curing for a longer duration than standard?

Air cool the tooth with the air/water syringe to prevent thermal damage to soft tissue/pulp.

Which generation of bonding agents has the best proven track record (12 years) for NCCL restoration?

4th Generation bonding agents (90% retention rate).

What is the role of the 10-MDP functional monomer?

It ionically bonds to hydroxyapatite (calcium) to form stable MDP-Ca salt nano-layers, improving the long-term integrity of the dentin bond.

Who developed the first composite resin in 1962?

Dr. Rafael Bowen.

What makes 'Brownie' points effective for occlusal adjustments?

They are efficient at removing/polishing composite but very inefficient at removing natural tooth structure. They must be used with water.

What is the recommended thickness for a temporary restoration (like Cavit) to ensure a seal?

Minimum 3-4 mm in thickness at the periphery to prevent microleakage.

How do GICs bond to tooth structure?

They bond CHEMICALLY via an ionic bond between the acidic carboxyl groups (-COOH) of the GI and Calcium ions (Ca+) from the tooth.

What is the 'Chiclet Appearance' and why is it avoided?

An unesthetic, blocky/square look caused by improper width-to-height proportions or over-contouring.

What is the 'Sandwich Technique' and when is it indicated?

Placing a 1-2 mm layer of RMGI (like Activa BioActive) in the gingival box before composite. Indicated when margins are close to/below the gingiva or caries recurrence is a concern.

What are the two most common etiologies for Class IV restorations?

Trauma (horizontal fractures) and Caries (where a large Class III undermines the incisal edge).

What does HEMA do in a primer?

HEMA is a molecule able to displace moisture and allow for the penetration of hydrophobic bonding agents (like bis-GMA) into the collagen matrix.

Where are Class III carious lesions typically located?

On the proximal surfaces (mesial or distal) of anterior teeth, typically at and gingival to the contact area, without involving the incisal angle.

How does tooth dehydration affect shade selection?

Dehydration causes teeth to appear lighter (higher value) and more opaque. Shades must be selected BEFORE isolation or rubber dam placement.

Define 'Full Pulpotomy'.

The surgical removal of the entire coronal portion of a vital pulp to preserve the vitality of the remaining radicular (root) portion.

What defines the setting reaction of a Glass Ionomer?

An Acid-Base reaction where polyacrylic acid attacks the glass, causing 20-30% of it to 'melt' into a salt gel matrix, trapping unreacted glass within.

Differentiate between 'Infected' and 'Affected' dentin.

Infected dentin is soft/leathery and must be removed. Affected dentin is demineralized but still has a sound collagen matrix (harder) and can often be preserved.

What is the 'Gold Standard' for dentin bond strength?

4th Generation (Three-step Etch-and-Rinse) because the separate hydrophobic bonding resin layer reduces water sorption.

What is the purpose of incremental filling in Class II restorations?

To minimize 'C-Factor' (Configuration Factor) issues, reducing polymerization shrinkage stress on the bond.

How long should you typically etch and light cure for when completing resin sealants?

Etch for ~30 seconds. Light cure for 30-40 seconds.

What type of composite is Filtek Supreme Ultra and why is it used?

It is a nanofilled composite. It is used for aesthetic cases because it retains polish better than nanohybrids and offers 35 shades/opacities.

What setting and bur type are used for caries removal and smoothing?

BLUE 12 (Slow-speed) using a carbide round latch bur (No. 2 or No. 4).

What are the indications for sealants?

Newly erupted permanent molars and premolars, patients with high caries index, and primary/permanent teeth with deep pits and fissures at risk.

How long does the full GIC reaction take to reach maturity?

The full reaction takes 24 to 48 hours to mature.

Why might Glass Ionomer (GIC) be preferred for partially erupted molars?

GIC is moisture-tolerant and better for cases where salivary contamination is expected and isolation is difficult.

Why are bulk fill materials translucent upon placement but opaque after curing?

Fibers are aligned initially to allow improved light penetration, then realign when cured to become opaque for better esthetics.

If a surface is contaminated with saliva after light-curing the adhesive, what is the protocol?

You must start over: Rinse, Etch, and re-apply Bonding Agent (as per instructions).

Name the main strength and weakness of microfill composites.

Strength: Highly polishable and specialized aesthetic material. Weakness: Physically very weak; should only be used for enamel replacement (veneers, small class Vs).

What are the primary visual cues to look for during a caries diagnosis on a clean, dry tooth?

Opacity (chalkiness), cavitation, or grayish shadowing under the enamel (indicating dentinal involvement).

How are Cavity Sealers defined?

Liquids (varnishes or resins) placed to block or occlude dentin tubules to prevent fluid flow and sensitivity.

What is 'Chromatic Induction' (After-Image) in dentistry?

Staring at the red gingiva and then looking at a white tooth can cause a complementary green hue to appear, distorting perception.

What is the difference between hybrids and microfills regarding filler?

Hybrids contain various sizes of glass filler particles to improve physical properties. Microfills have uniformly sized, small particles (50-70% loading) primarily for aesthetics.`

What is the relationship between tooth mobility and the development of abfractions?

Inverse relationship: Loose teeth (periodontally involved) tend to have fewer abfractions because the stress is dissipated by movement.

How does a Glass Ionomer Class V prep differ from a Composite prep?

GI requires a 'box' form for bulk strength and MUST NOT be beveled (brittle material). Composite is saucer-shaped and beveled on enamel margins.

What should you check on the Light Curing Unit (LCU) tip before exposure?

Check for damage, debris (composite resin), and ensure the disposable clear barrier is placed correctly without seams blocking the beam.

Why is dentin called the 'Weak Link' in bonding compared to enamel?

Dentin is less mineralized, contains collagen, and is prone to hydrolysis and enzymatic degradation by MMPs (Matrix Metalloproteinases) activated by etching.

How is the 'C-Factor' calculated and why does it matter?

C = Bonded Walls / Unbonded Walls. As C-Factor increases, polymerization stress increases, potentially weakening the tooth-restorative bond.

What is the recommended internal geometry for Class II preparations to reduce stress?

Rounded internal line angles. Sharp angles concentrate stress; rounded ones conserve structure and enhance resin adaptation.

What is the primary purpose of a dental post?

To retain the core. Note: A post does NOT reinforce or strengthen the tooth; it may actually weaken it through structure removal.

What is a major contraindication for sealants mentioned in the text?

Interproximal decay (sealants are for occlusal pits and fissures).

What are the three primary goals of root canal obturation?

1. Coronal seal 2. Lateral seal 3. Apical seal (To create a watertight seal and maintain a clean environment for periapical health).

What is the mineral composition of Enamel vs. Dentin?

Enamel is 92% Hydroxyapatite. Dentin is 70% Hydroxyapatite (with 18% organic collagen and 12% water).

Why did early Silicate Cements (used into the 1960s) have a short life span?

They were porous, stained easily, and had no actual adhesion to the tooth structure, typically lasting less than 4 years.

What are the pros and cons of In-Office whitening?

Pros: Quick results. Cons: Quick rebound, higher chance of sensitivity, technique sensitive, and potential for tissue burns.

When are custom-cast posts indicated over prefabricated posts?

For very tapered canals, roots with oval shapes, substantial developmental depressions, or when >3/4 of the coronal structure is lost.

Which specific tooth type is most frequently affected by NCCLs?

Maxillary Premolars

What are the three main reasons layering is traditionally done?

1. Reduce Shrinkage Stress 2. Ensure Depth of Cure 3. Maintain Density of Fill

What are the benefits of using Lime-Lite Enhanced under posterior composites?

It covers dentin to decrease sensitivity, releases calcium, phosphate, and fluoride, and helps reduce the effects of shrinkage stress.

What are the 4 key elements of the MUSC bonding process?

1. Remove Biofilm (Pumice) 2. Etch (Total etch 15s) 3. Disinfect (FiteBac/Chlorhexidine) 4. Prime and Bond (Universal Agent)

What is the primary difference between 'Finishing' and 'Polishing'?

Finishing removes excess composite ('flash') and shapes the contour. Polishing imparts luster or shine to the surface.

What are the first three steps in the Diastema Restoration workflow?

1. Shade matching 2. Rubber dam isolation 3. Tooth preparation (roughening surfaces)

What material is ideal for DME and why?

Dual-cured materials (like Activa Bioactive Restorative) or RMGIC, because they ensure a complete cure even in deep areas with limited light access.

What are the three primary methods of diagnosing Class III lesions?

1. Visual/Tactile (eyes/explorer) 2. Radiographic (interproximal radiolucency) 3. Transillumination (light through contact area)

When should you choose Glass Ionomer (GI) over Composite for a Class V?

In high caries risk patients, when margins are mostly cementum/dentin, or when isolation is difficult. GI provides chemical bonding and fluoride release.

How do Dual-Cure Bulk-Fill restoratives work?

They have a self-cure mechanism (activated when 2 pastes mix) and a light-cure mechanism. This allows them to cure at any depth (e.g., 10mm molds).

Where do Class V lesions occur?

In the gingival third of facial and lingual tooth surfaces. They can involve enamel, cementum, and dentin.

What material should NOT be used to clean debris from a tooth before restoration?

Prophy paste, as it will contaminate the site. Use a slurry of pumice or air abrasion instead.

When should you consider a referral for a diastema case?

Spaces > 3mm, skeletal discrepancies, peg laterals requiring interdisciplinary planning, or suspected mesiodens.

What are the four primary causes of premature failure in posterior resins?

1. Moisture contamination 2. Shrinkage stress 3. Bonding issues 4. Material issues

List three common 'Physical Restraints' that can cause a diastema.

1. Mesiodens (supernumerary tooth) 2. Abnormal Frenum attachment 3. Retained deciduous teeth

What does it mean for a material to be 'Bioactive'?

It elicits a specific biological response at the interface, resulting in a bond between the tissue and the material (e.g., fluoride/ion release and uptake).

What is the primary function of the Mylar Matrix in Class III/IV restorations?

To provide proper contour/adaptation, reduce gingival flash, and allow light transmission for polymerization.

According to Ng et al (2010), what is the 8-10 year survival rate of root-filled teeth?

87%. The main reasons for extraction are often caries, periodontal disease, or lack of definitive restoration (not just endodontic failure).

Why is the Lingual Approach preferred for Class III preparations?

It preserves facial enamel for superior esthetics and maintains the natural color/texture of the labial surface.

What is the recommended exposure adjustment for deep proximal boxes (5-8mm away)?

Increase exposure time because the recommended time is usually given for short distances.

What is the 'Tootsie Roll Pop Effect' in composite curing?

A restoration that is solid/cured on the outside but soft/uncured on the inside, leading to sensitivity, cytotoxicity, and pulpal damage.

What is a Cavity Liner?

A viscous coating used as a physical barrier and/or for therapeutic medicinal purposes (e.g., Dycal or Vitrebond).

Which peroxide is known for 'Fast Action' vs 'Slow Release'?

Hydrogen Peroxide is 'Fast Action' (lifts stains fast). Carbamide Peroxide is 'Slow Release' (remains active longer).

What is the 'C-factor' and how is it calculated?

Configuration Factor: The ratio of Bonded surfaces to Unbonded surfaces (C = B/U). A higher C-factor (like a Class I box) leads to higher contraction stress.

What is the Coefficient of Thermal Expansion (CTE) and why does it matter?

The expansion/contraction of material during temp changes. Composite CTE is 2-6x higher than tooth structure. Thermal cycling creates stress, marginal gaps, and microleakage.

What are the two main purposes of Copal Varnishes?

1. Seal/occlude dentinal tubules to minimize sensitivity. 2. Eliminate silver salt staining from amalgam breakdown.

What are the criteria for restoring Non-Carious Cervical Lesions (NCCLs)?

Restore if: Active caries is present, structural integrity is threatened, intolerable sensitivity exists, esthetics are unacceptable, or etiologic habits can't be stopped.

What are the key properties of Calcium Hydroxide liners (like Dycal)?

High pH (>10), antimicrobial, promotes reparative dentin, but is weak and highly soluble.

What is the recommended clinical sequence when matching the three dimensions of color?

1. Value (first) 2. Chroma 3. Hue (last)

What is the role of Lime-Lite Enhanced in the VPT workflow?

It acts as a remineralizing liner and protective barrier. It is used to cover affected dentin or materials like Biodentine to enable composite bonding and provide thermal protection.

Describe the characteristic shape and margin of an 'Abfraction' lesion.

V-shaped (wedge) with sharp, ragged, or 'chippy' enamel margins. Often rough surface.

What is a PRR and when is it performed?

Preventive Resin Restoration. It is performed when a groove is suspected of being carious and investigation is needed to determine the depth of decay.

Define the 'Oxygen Inhibited Layer'.

A thin (1-3μ) layer of non-polymerized resin on the surface caused by atmospheric oxygen. It consists of uncured monomers and allows composite to bond to itself.

What are the two primary components of a conventional Glass Ionomer?

1. Powder: Calcium fluoroaluminosilicate glass (Base) 2. Liquid: Polyacrylic acid (Weak Acid) *Note: Strontium is also an important component mentioned in the slides.

What term is the dental literature beginning to use to replace 'Erosion'?

Biocorrosion (chemical or electrochemical degradation).

What is the 'Gold Standard' for isolation in composite dentistry?

Rubber Dam isolation.

What is the '5mm Rule' regarding interdental papilla fill?

If the distance from the contact point to the osseous crest is 5mm or less, there is a 100% chance of complete papilla fill. Probability drops by 50% for every 1mm above 5mm.

What are the three essential steps during light curing?

1. Wear Eye Protection 2. Stabilize the tip 3. Watch the restoration while light curing

What is the 'Closed Sandwich' technique?

The GIC is buried under a restorative material (like composite) and is not exposed to the oral environment. It acts as a base to protect pulp and reduce shrinkage stress.

What distinguishes a Class IV from a Class III lesion?

Class IV involves the proximal surface AND the incisal angle of anterior teeth.

What is Lime-Lite Enhanced?

A bio-interactive, light-cured liner that releases Calcium, Phosphate, and Fluoride.

Define 'Value' and its range.

Value is the relative lightness or darkness (brightness) of a color. It ranges from black (0) to white (10) on the gray scale.

What is the correct finishing sequence?

Finish the interproximal area first (using 7902 or Diamond ET), then finish the occlusal area (using OS2/OS1 or Football Carbide).

At what point does a procedure shift from a sealant code to an Occlusal Composite code?

When decay extends into the dentin. Sealants are for enamel-only or preventative measures.

Define the 'Ferrule Effect' and its ideal dimensions for a post/core.

Definition: Cervical tooth structure apical to the core that resists fracture. Height: 1.5-2 mm circumferential wall. Thickness: >1 mm around root canal.

What are the two main benefits of 'pre-wedging' before starting the preparation?

1. Keeps the rubber dam compressed. 2. Creates slight separation to protect the adjacent tooth and help in creating the final contact.

According to the Total Etch protocol, how long should phosphoric acid be applied?

15 seconds.

Under what specific condition is 'No Treatment' recommended for a child?

A child in mixed dentition with spacing < 2mm, where canine eruption is expected to close the space naturally.