p.1
Chemical Properties and Behavior of Gypsum
What is the chemical name of Gypsum?
Calcium Sulfate Hemihydrate.
p.1
Applications of Gypsum in Dentistry
What is Gypsum primarily used for?
It is the main composition in many forms of plaster and stone.
p.1
Manipulation and Setting of Gypsum Products
What happens to Gypsum when heated at atmospheric pressure at 120°C?
The powder particles become porous and irregular (β hemihydrate, plaster).
p.1
Manipulation and Setting of Gypsum Products
What is the result of heating Gypsum under pressure?
The powder particles are regular and less porous (α hemihydrate, or dental stone).
p.9
Models Fabrication Techniques
What instruments are needed for hand mixing?
A clean rubber bowl, a clean plaster spatula, a clean plaster knife, and an automatic vibrator.
p.3
Models Fabrication Techniques
What is flasking in the context of dental models?
Flasking is the process of enclosing a model in investment material to create a mold.
p.36
Applications of Gypsum in Dentistry
What is the primary application of Thermo-plastic Vacuum Adapted Resin?
It is used in dental applications, particularly for creating dental prosthetics.
p.33
Special Impression Trays
What are the two main categories of impression trays?
Stock trays and custom trays.
p.17
Technological Advancements in Dental Materials
How does laser powder-bed fusion work?
It adds successive layers of metal powder and uses a laser to melt each layer into place.
p.36
Manipulation and Setting of Gypsum Products
What process is used to adapt Thermo-plastic Vacuum Adapted Resin?
It is adapted using a vacuum process.
p.2
Applications of Gypsum in Dentistry
What does investment refer to in the context of gypsum applications?
It refers to the process of encasing a dental model for casting.
p.32
Impression Materials and Their Types
What is the importance of pouring impressions immediately?
To prevent shrinkage and ensure accuracy.
p.18
Models Fabrication Techniques
What characteristics do different dental materials have?
Resistance to discoloration and deterioration, and a beautiful finish.
p.11
Manipulation and Setting of Gypsum Products
What is the importance of the W/P ratio in the procedure?
It determines the required amount of cast material and distilled water for mixing.
p.33
Special Impression Trays
What are the types of stock trays?
Metallic (sterilizable and reusable) and disposable (for convenience).
p.33
Special Impression Trays
What types of stock trays are available for dentulous and edentulous patients?
Dentulous tray and edentulous tray.
p.14
Models Fabrication Techniques
What are the two parts of the cast composed of?
Anatomical part and base portion.
p.32
Impression Materials and Their Types
What is recommended for the surface of elastomer impressions like silicone rubber or poly-sulphide?
Coat with a wetting agent such as Aurofilm to lower surface tension.
p.34
Special Impression Trays and Their Requirements
What material is commonly used to fabricate custom trays?
Self-cured Poly Methyl Methacrylate (PMMA).
p.21
Dental Articulators and Their Applications
What type of movement does a Simple Hinge Articulator allow?
Only hinge rotational movement; opening and closing.
p.21
Dental Articulators and Their Applications
What additional motions does an Average Value Articulator permit?
Horizontal as well as vertical motion.
p.27
Impression Materials and Their Types
What is the purpose of a final or master impression?
To get a detailed negative imprint of the arch for a master or working model.
p.9
Models Fabrication Techniques
Name a disinfectant commonly used in infection control.
Sodium hypochlorite, Iodophors, or Chlorine dioxide.
p.2
Applications of Gypsum in Dentistry
What is a plaster index used for in dentistry?
It is used for making plaster indices.
p.2
Applications of Gypsum in Dentistry
What is the purpose of mounting models in an articulator?
To simulate jaw movements and occlusion.
p.23
Dental Articulators and Their Applications
What types of records are required for centric relation?
Centric relation record, protrusive records, and lateral record.
p.23
Models Fabrication Techniques
What methods can be used for fixing a model to an articulator?
Plaster, magnet, retentive pin, screw mounting plate, and special shape of mounting plaster.
p.14
Models Fabrication Techniques
What should be done if the alginate impression dried before cast separation?
Soak in water for 5 minutes.
p.18
Models Fabrication Techniques
How are materials chosen for dental milling?
According to their purpose.
p.42
Special Impression Trays and Their Requirements
What type of wire is recommended for reinforcing the shellac tray?
At least 1.5mm stainless steel round wire.
p.21
Dental Articulators and Their Applications
What does a Semi-adjustable Articulator simulate?
Condylar pathway using average or mechanical equivalents.
p.28
Impression Materials and Their Types
What is the water to powder ratio for Impression Plaster (Plaster of Paris)?
60 ml of water to 100 g of powder.
p.43
Models Fabrication Techniques
What is the purpose of heating the thermo-plastic resin sheet?
To soften the sheet gradually.
p.33
Special Impression Trays
What is the purpose of an impression tray?
To transport the impression material to the mouth, confine the material to the surfaces being recorded, and control and support the impression material during taking and setting.
p.32
Impression Materials and Their Types
What should be done to the unsupported area of a Zinc-Oxide Eugenol impression?
It should be kept away from the heat source.
p.32
Impression Materials and Their Types
How should alginate impressions be covered before pouring?
With wet napkins to avoid shrinkage.
p.33
Special Impression Trays
What are the different arch types for impression trays?
Full arch and partial arch (quarter, anterior, posterior).
p.2
Applications of Gypsum in Dentistry
What is flasking in dental applications?
It is the process of enclosing a model in a flask for processing.
p.14
Models Fabrication Techniques
What should be ensured before separating the cast from the impression?
No part of the tray should be connected to the gypsum.
p.20
Dental Articulators and Their Applications
What is a dental articulator?
A mechanical device that represents the temporomandibular joint (TMJ) and jaw members, allowing maxillary and mandibular casts to be attached to simulate upper and lower jaw movements.
p.13
Models Fabrication Techniques
What method is used to mix the cast material?
Mechanical mixing method.
p.21
Dental Articulators and Their Applications
What is a characteristic of the Average Value Articulator regarding TMJ?
It does not orient the motion of TMJ.
p.11
Manipulation and Setting of Gypsum Products
How should the cast material be mixed?
By mechanical mixing to avoid air bubbles.
p.27
Models Fabrication Techniques
What is a preliminary or study model?
A model obtained by pouring the preliminary impression.
p.11
Manipulation and Setting of Gypsum Products
What is the disadvantage of the Single Stage Technique?
The cast material might not stick to the inner surface of the inverted impression, affecting dimensional accuracy.
p.31
Impression Materials and Their Types
How should an impression be preserved to maintain its integrity?
It should be suspended in a tray holder or supported in a tray stand, avoiding unnecessary touching or displacing.
p.28
Manipulation and Setting of Gypsum Products
Why is a color pigment added to Impression Plaster?
To distinguish it from cast/model materials.
p.13
Models Fabrication Techniques
What is the first step in the boxing technique for crown and bridge?
Use beading wax to stick around the periphery for sufficient depth of sulcus.
p.13
Models Fabrication Techniques
What is the purpose of wrapping a wax strip around the beading wax?
To form a box for pouring the cast material.
p.13
Models Fabrication Techniques
How should the cast material and distilled water be measured?
According to the recommended water-to-powder (W/P) ratio.
p.34
Classification of Special Trays
What are spaced perforated trays used for?
They allow for the impression material to flow through the perforations.
p.22
Dental Articulators and Their Applications
What does the ability to adjust distances between the condyles in a fully-adjustable articulator allow?
It allows for full simulation of the condylar structures.
p.27
Models Fabrication Techniques
What is a cast or model in dentistry?
The positive likeness or duplication of the patient’s oral situation, such as the arch or group of teeth.
p.4
Types and Classifications of Gypsum Materials
How does gypsum material compare in terms of ease of use?
Gypsum materials are known for their ease of use.
p.20
Types and Classifications of Gypsum Materials
What characterizes a non-adjustable articulator?
It can accept a single static registration, has no mandibular movement except opening and closing, and is commonly called a 'Hinge Articulator'.
p.24
Models Fabrication Techniques
What is the first step in preparing the cast for assembly?
Trim the cast to a suitable size to facilitate assembly and future flasking.
p.27
Impression Materials and Their Types
What are the two common types of impression materials?
Rigid impression materials and elastic impression materials.
p.25
Models Fabrication Techniques
What is the first step in preparing models for mounting on a Fixed Condylar Path Articulator?
Preparation before mounting the upper cast onto the mounting platform.
p.24
Models Fabrication Techniques
What adjustment should be made for parallelism of the arms?
Adjust the screw and increase the distance if the cast is too large.
p.38
Special Impression Trays and Their Requirements
What are the components of special design for impression trays?
1. Periphery extension 2. Perforation 3. Handle 4. Finger press 5. Stopper 6. Spacer.
p.10
Manipulation and Setting of Gypsum Products
What is the purpose of placing the rubber bowl on the vibrator during hand mixing?
To remove large air bubbles from the mixture.
p.25
Models Fabrication Techniques
What should coincide with the midline of the platform during mounting?
The median suture line of the upper cast.
p.36
Technological Advancements in Dental Materials
What type of material is Thermo-plastic Vacuum Adapted Resin?
It is a type of thermoplastic material.
p.12
Models Fabrication Techniques
What is the first step in the Two Stages Technique procedure?
Measuring materials, mixing the cast material, and pouring the impression up to the pencil mark.
p.18
Models Fabrication Techniques
Name some types of disk materials used in dental milling.
Non-metallic zirconia, ceramic, wax, PMMA (acrylic resin), titanium, and cobalt.
p.34
Classification of Special Trays
What is a close fitted special tray?
A type of special tray that fits closely to the patient's dental arch.
p.23
Models Fabrication Techniques
What should be checked if bite rims are used before mounting?
Correct fitting to ensure accurate articulation.
p.14
Models Fabrication Techniques
Why should care be taken when removing the tray and impression material?
To avoid breaking teeth, particularly for single standing teeth.
p.20
Types and Classifications of Gypsum Materials
What is the classification of dental articulators?
Class I: Non Adjustable, Class II: Average Value, Class III: Semi Adjustable, Class IV: Fully Adjustable.
p.11
Models Fabrication Techniques
What technique is used to pour the cast material into the impression?
Pour a small amount at one end and use a vibrator to allow it to run over the impression.
p.42
Special Impression Trays and Their Requirements
What is the purpose of duplicating a model with agar in the heat-cured acrylic procedure?
To create a working model for the tray.
p.42
Special Impression Trays and Their Requirements
What is done after packing the flask with clear denture base material?
Polymerize the resin with the recommended curing cycle.
p.26
Impression Materials and Their Types
What undesirable outcome can result from a preliminary impression?
Over extension due to excessive impression material pushing the cheek out, creating a false record of the sulcus.
p.10
Manipulation and Setting of Gypsum Products
What is the recommended W/P ratio for hand mixing stone powder?
Usually 300g of powder for one impression including base.
p.40
Special Impression Trays and Their Requirements
What is the recommended outline level for non-critical areas in tray fabrication?
Down to the gingival level.
p.35
Special Impression Trays and Their Requirements
Why is it important for special trays to cover all required oral tissues?
To provide accurate anatomical extension.
p.5
Types and Classifications of Gypsum Materials
What are Type IV and Type V gypsum materials used for?
Die Stone, Low Expansion (Type IV) and Die Stone, High Expansion (Type V).
p.7
Manipulation and Setting of Gypsum Products
What happens if too much water is added to the gypsum mix?
It results in a thin mix.
p.3
Dental Articulators and Their Applications
What is a plaster index used for?
It is used for mounting models in an articulator.
p.3
Models Fabrication Techniques
What does the composition of investment typically include?
A mixture of various materials designed for mold-making.
p.32
Impression Materials and Their Types
What should be done to avoid drying shrinkage in irreversible hydrocolloid or agar impressions?
Wrap or cover with wet napkins.
p.34
Special Impression Trays and Their Requirements
What are custom or special trays used for?
They are specially designed and fabricated for individual patients.
p.42
Special Impression Trays and Their Requirements
What material is recommended as a spacer when using shellac?
A mixture of plaster and pumice or wet non-asbestos casting lining material.
p.22
Dental Articulators and Their Applications
What features can be adjusted in a fully-adjustable articulator?
Condylar width, angle, condylar post angle, and incisive angle.
p.20
Dental Articulators and Their Applications
What are some applications of dental articulators?
Diagnosis of occlusal relationships, diagnostic waxing, artificial teeth setting, treatment planning, and fabrication of dental appliances like dentures, crowns, and bridges.
p.13
Models Fabrication Techniques
What is an advantage of the boxing technique?
Can control the form of the cast easily and has higher density and strength.
p.30
Impression Materials and Their Types
What are the different types of rubber impression materials based on viscosity?
Light, regular, and heavy-body.
p.4
Chemical Properties and Behavior of Gypsum
What contributes to the strength of gypsum products?
Porosity and the shape of particles.
p.30
Requirements for Accurate Impression
What must be ensured regarding the impression material on the tray?
It must be firmly secured.
p.35
Special Impression Trays and Their Requirements
What is the purpose of providing suitable space for impression material in special trays?
To achieve the best result in capturing details.
p.37
Special Impression Trays and Their Requirements
What feature allows for easy adjustments to special trays?
Easy chair-side modification.
p.38
Special Impression Trays and Their Requirements
What is the periphery extension coverage for edentulous patients?
Normally down to the deepest part of the sulcus, 1mm above the sulcus.
p.43
Models Fabrication Techniques
What is done after the resin sheet is adapted to the model?
Trim the excess material and add S.S. wire or acrylic handle.
p.35
Special Impression Trays and Their Requirements
How do special trays minimize tissue distortion?
By providing a stable and accurate impression environment.
p.43
Technological Advancements in Dental Materials
What technological advancement is mentioned in relation to trays and articulators?
3D Printed Trays & Articulator.
p.28
Impression Materials and Their Types
Why is impression compound not suitable for detailed impressions?
It cannot copy the detail of oral tissue and is affected by heat.
p.15
Impression Materials and Their Types
How can you separate impression plaster from the cast?
By tapping gently on the impression plaster surface with an instrument like Lecorn.
p.25
Models Fabrication Techniques
What is the next step after removing the mounted upper cast from the articulator?
Accurately and firmly articulate it with the lower cast.
p.25
Models Fabrication Techniques
What should be done after the plaster sets?
Trim the excess plaster with a Stanley knife or model trimmer, then smoothen with sandpaper.
p.9
Models Fabrication Techniques
What is a recommended method for infection control during mixing?
Spray rather than immerse.
p.2
Applications of Gypsum in Dentistry
How is gypsum used in constructing dental models?
It is used to create models and dies.
p.23
Dental Articulators and Their Applications
What are the types of dental articulators mentioned?
Fully adjustable, semi-adjustable, and non-adjustable.
p.42
Special Impression Trays and Their Requirements
Why is shellac seldom used for making special trays?
It is brittle, thermo-plastic, dimensionally unstable, and can clog burs during adjustment.
p.22
Dental Articulators and Their Applications
What is the main characteristic of the Arcon type articulator?
The condylar tracks are on the upper arm and the condylar head is on the lower arm, resembling the TMJ.
p.22
Dental Articulators and Their Applications
How does the Non-Arcon type articulator differ from the Arcon type?
In the Non-Arcon type, the condylar tracks are on the lower member and the condylar heads are on the upper arm, reversing the TMJ.
p.20
Dental Articulators and Their Applications
What are the common features of dental articulators?
They consist of upper and lower arms to which maxillary and mandibular casts are attached, with a movable joint mechanism representing the temporomandibular joint.
p.34
Classification of Special Trays
What is a two-part tray?
A sectional tray that consists of two parts for easier handling.
p.30
Impression Materials and Their Types
How is the rubber impression material supplied?
In pastes (Base & Catalyst).
p.13
Models Fabrication Techniques
What is a disadvantage of the boxing technique?
It is time-consuming to make the 'box'.
p.21
Dental Articulators and Their Applications
What types of relations can a Semi-adjustable Articulator accept?
Both centric and eccentric relation.
p.5
Types and Classifications of Gypsum Materials
How does the strength of Model Plaster compare to Dental Stone?
Model Plaster produces a weak cast compared to Dental Stone.
p.30
Requirements for Accurate Impression
What is a requirement for an accurate impression?
A rigid tray covering all required surface details.
p.27
Impression Materials and Their Types
What are rigid impression materials used for?
They are used for impressions of areas without undercuts, such as edentulous cases.
p.40
Special Impression Trays and Their Requirements
What is the purpose of the stopper in tray fabrication?
To keep the tray at an optimum distance from the oral tissue for the best properties of impression materials.
p.28
Chemical Properties and Behavior of Gypsum
What is a key characteristic of Impression Plaster regarding its stability?
It is dimensionally stable but easily broken.
p.26
Impression Materials and Their Types
What happens in over areas of an impression?
Large amount of contraction occurs.
p.24
Models Fabrication Techniques
How should the upper and lower casts be held in place?
Using sticky wax and toothpicks.
p.7
Manipulation and Setting of Gypsum Products
How does the water to powder ratio affect gypsum materials?
It affects setting time, working time, expansion, strength, and accuracy.
p.28
Impression Materials and Their Types
What is the primary use of impression compound in clinical settings?
To modify the contour and border of the tray.
p.15
Impression Materials and Their Types
What tool can be used to remove the tray from impression plaster?
A plaster knife, by inserting it between the tray and impression material.
p.24
Models Fabrication Techniques
What should be marked on the mounting plaster?
Necessary data/measurements such as vertical dimension, date, and articulator number.
p.41
Models Fabrication Techniques
What is the recommended mixing ratio used for?
To mix the tray material.
p.25
Models Fabrication Techniques
What should be marked onto the mounting plaster?
The necessary data/readings.
p.3
Models Fabrication Techniques
What is the purpose of investment in dental procedures?
It is a mixture of materials used to make a mold.
p.17
Technological Advancements in Dental Materials
What type of 3D printer is described in the text?
Laser powder-bed fusion type.
p.18
Models Fabrication Techniques
What is a dental milling machine used for?
To process prosthetics such as fillings and crowns to replace missing teeth.
p.32
Impression Materials and Their Types
What is the best practice for pouring alginate impressions?
To pour the impression immediately.
p.14
Models Fabrication Techniques
Can the base portion be poured with or without a vibrator?
Yes, it can be poured with or without a vibrator.
p.11
Models Fabrication Techniques
What is the first step in the Single Stage Technique Procedure?
Rinse the impression with running water to remove dirt and saliva, then blow away excess water.
p.23
Models Fabrication Techniques
What is the first step in preparing for mounting on a simple hinge articulator?
Remove occlusal interference on the upper and lower casts.
p.30
Impression Materials and Their Types
What type of rubber is commonly used for master impressions?
Poly-sulfide Rubber/Silicone Rubber.
p.34
Classification of Special Trays
What is the purpose of a bleaching tray?
To hold bleaching agents against the teeth for whitening.
p.21
Dental Articulators and Their Applications
What features can be adjusted in a Semi-adjustable Articulator?
Adjustable condylar guidance and adjustable incisal guide table.
p.4
Types and Classifications of Gypsum Materials
What allows gypsum materials to accurately reproduce fine detail?
Their accurate reproduction capabilities.
p.37
Special Impression Trays and Their Requirements
What is a key requirement for special trays in dentistry?
They must be dimensionally stable and rigid.
p.11
Models Fabrication Techniques
What is an advantage of the Single Stage Technique?
It is fast, making it suitable for diagnostic casts.
p.26
Impression Materials and Their Types
What happens in thin areas of an impression?
Small contraction occurs.
p.31
Impression Materials and Their Types
What should be done if there is distortion of the impression material from the tray?
Check the accuracy of the impression; questionable impressions should be discarded by the dentist.
p.37
Special Impression Trays and Their Requirements
What should the surface of special trays be like?
Clean, smooth, and without sharp edges.
p.35
Special Impression Trays and Their Requirements
What is one material used for special trays?
Self-cured Poly Methyl Methacrylate (PMMA).
p.41
Models Fabrication Techniques
What is the purpose of applying a separating medium?
To prevent adhesion between the tray material and the cast.
p.39
Special Impression Trays and Their Requirements
At what angle should the handle be positioned for edentulous cases?
About 5 to 15 degrees to the vertical.
p.15
Impression Materials and Their Types
What should you do to soften impression compound?
Immerse the impression and cast into hot water.
p.7
Manipulation and Setting of Gypsum Products
What is hygroscopic expansion in gypsum?
It occurs when gypsum soaked during setting, causing water to fill pores and increase volume.
p.8
Manipulation and Setting of Gypsum Products
How does increasing the water-to-powder ratio affect setting time?
It retards setting, resulting in a weaker and inaccurate model.
p.8
Manipulation and Setting of Gypsum Products
What can act as retarders in the setting reaction of gypsum?
Blood, saliva, and alginate.
p.17
Technological Advancements in Dental Materials
What is the purpose of the laser in laser powder-bed fusion?
To melt each layer of metal powder into place on the part being created.
p.12
Models Fabrication Techniques
What is done after inverting the impression in the Two Stages Technique?
Put it onto the cast material on the flat plate and trim the excess with a plaster knife.
p.12
Models Fabrication Techniques
What is the advantage of the Two Stages Technique compared to the single stage technique?
Higher density and strength, resulting in more accuracy.
p.11
Models Fabrication Techniques
What should be drawn around the periphery of the tray?
A predict line using an indelible pencil, about 3mm above the periphery.
p.13
Models Fabrication Techniques
What technique is used to pour the mixed cast material into the impression?
Use a vibrator to allow the cast material to run over the impression without trapping air bubbles.
p.34
Classification of Special Trays
What is a spaced non-perforated tray?
A tray that has space for impression material but no perforations.
p.27
Models Fabrication Techniques
What is a master/working model used for?
It is used to fabricate dental appliances and is obtained from the impression using a custom tray.
p.26
Impression Materials and Their Types
What is a preliminary impression?
An impression using a stock tray to get the first negative imprint of the arch for a study model.
p.43
Models Fabrication Techniques
Where is the duplicated cast placed during the procedure?
On the center of the pressure forming machine (e.g., Dufomat).
p.16
Manipulation and Setting of Gypsum Products
What are some trimming considerations in dental applications?
Proportion of base to anatomical part, parallelism, use of bite registration, outer border of cast, and shaping of anterior part of upper and lower arches.
p.35
Special Impression Trays and Their Requirements
How do special trays enhance the retention of impression materials?
By improving the grip of the impression material onto the tray.
p.25
Models Fabrication Techniques
Where should the center line be located when mounting the upper cast?
On the incisor mark on the platform or the incisal pin of the articulator should point to the center line.
p.10
Manipulation and Setting of Gypsum Products
What is the first step in the hand mixing procedure?
Measure the stone powder and distilled water according to the recommended W/P ratio.
p.43
Models Fabrication Techniques
How is the softened resin sheet applied to the model?
By pressure and vacuum adaptation.
p.28
Manipulation and Setting of Gypsum Products
What must be added to separate the impression material from the stone?
A separating medium, such as water glass.
p.4
Types and Classifications of Gypsum Materials
What is the significance of good color contrast in gypsum materials?
It aids in visual differentiation and detail recognition.
p.10
Manipulation and Setting of Gypsum Products
What instruments are needed for mechanical mixing?
A clean plaster spatula, a mechanical mixing vessel/jar, a mechanical vibrator, and a vacuum mixer.
p.37
Special Impression Trays and Their Requirements
What is a property of special tray materials regarding manipulation?
They should allow easy laboratory manipulation.
p.7
Manipulation and Setting of Gypsum Products
What causes setting expansion in gypsum?
Crystal growth during setting.
p.15
Impression Materials and Their Types
How can you remove the tray with compound from the cast?
By lifting the handle of the tray.
p.38
Special Impression Trays and Their Requirements
What is the layering requirement for a partial perforated tray?
One layer of sheet wax on teeth (5mm away from gingival) and one layer covering both teeth and oral tissue.
p.5
Types and Classifications of Gypsum Materials
What is Type II gypsum material used for?
Diagnostic cast, mounting of stone cast, art portion of working cast, flasking procedure for full acrylic dentures.
p.11
Models Fabrication Techniques
What is done with the remaining cast material after filling the impression?
Place it onto a flat plate with a height of 2 to 3 cm and larger area than the impression size.
p.28
Impression Materials and Their Types
What type of impression material is Impression Plaster classified as?
Mucostatic impression material.
p.35
Special Impression Trays and Their Requirements
What is one advantage of using a special tray in dental impressions?
Compatible with selected impression material.
p.26
Impression Materials and Their Types
What causes distortion in an impression?
If the tray does not fit well or if the impression material is not uniform in thickness.
p.16
Technological Advancements in Dental Materials
What advancements in technology are mentioned for improving dental treatments?
Intra-oral scanners, digital impressions, 3D printing, and milling.
p.16
Technological Advancements in Dental Materials
How do intra-oral scanners benefit dental treatments?
They provide direct information of oral tissue for milling prostheses or sending digital information to dental laboratories.
p.31
Manipulation and Setting of Gypsum Products
When should an impression be poured?
As soon as possible after the impression material recovers from its memory.
p.29
Impression Materials and Their Types
What is the purpose of Zinc-Oxide Eugenol (ZOE) paste?
Used for non-undercut situations such as edentulous cases, relining, or rebasing partial denture cases.
p.38
Special Impression Trays and Their Requirements
What is the periphery extension requirement for crown and bridge cases?
1-2mm below the gingival and 3-4mm in the crown/bridge area.
p.40
Special Impression Trays and Their Requirements
What should be done a day or more ahead of tray use?
Make trays, as acrylic undergoes polymerization shrinkage for 24 hours.
p.31
Manipulation and Setting of Gypsum Products
How should impression plaster be stored to avoid drying shrinkage?
It should be kept in a plastic bag.
p.35
Special Impression Trays and Their Requirements
What type of resin is adapted for thermo-plastic vacuum/pressure?
Thermo-plastic Vacuum/Pressure Adapted Resin.
p.29
Impression Materials and Their Types
What are some examples of elastic impression materials?
Alginate, Silicone Rubber, Polysulphide Rubber, Elastomers.
p.39
Special Impression Trays and Their Requirements
Where is the finger press used in edentulous cases?
On the crest of the ridge near the second premolar/first molar region.
p.41
Models Fabrication Techniques
What should be done with excess tray material?
Cut it with scissors or a scalpel.
p.8
Manipulation and Setting of Gypsum Products
What happens when the water-to-powder ratio is decreased?
It shortens the setting time but makes the mix difficult to manipulate and can include bubbles.
p.6
Chemical Properties and Behavior of Gypsum
What is a characteristic feature of Dental Stone, high strength (Type IV)?
It is often colored pink and is stronger than Type III stone.
p.6
Types and Classifications of Gypsum Materials
How does the strength of different types of gypsum products rank?
Type I < Type II < Type III < Type IV.
p.28
Manipulation and Setting of Gypsum Products
What additives can be used to regulate the setting time of Impression Plaster?
Accelerators like potassium sulphate or retarders like borax.
p.27
Models Fabrication Techniques
What is a working cast/model?
A duplicate of the master model on which all steps in fabricating the dental appliance will be done.
p.24
Models Fabrication Techniques
What is the purpose of making an index on the base of the cast?
For the split cast technique.
p.31
Impression Materials and Their Types
What should be done to an impression before disinfection?
Remove saliva and dirt by rinsing under running water, then soak in disinfectant.
p.37
Special Impression Trays and Their Requirements
What is necessary for the impression materials in special trays?
They should provide correct space and uniform thickness.
p.7
Manipulation and Setting of Gypsum Products
What is the golden rule for proportioning water to powder ratio in gypsum?
Manufacturer instructions should always be followed.
p.38
Special Impression Trays and Their Requirements
How far above the sulcus should the periphery extension be for dentulous patients?
1 to 2mm above the deepest part of the sulcus.
p.24
Models Fabrication Techniques
What should be done after applying plaster to the base of the lower cast?
Place the center line of the upper cast on the center line of the articulator.
p.31
Chemical Properties and Behavior of Gypsum
What is water glass composed of?
Sodium oxide (Na2O) and silica (SiO2).
p.35
Special Impression Trays and Their Requirements
Name another material used for special trays.
Light-cured Acrylic Resin.
p.37
Special Impression Trays and Their Requirements
What is a desirable characteristic of special tray materials in terms of safety?
They should be non-toxic and non-irritating.
p.10
Models Fabrication Techniques
What are the three techniques for pouring casts?
Single Stage Technique, Two Stages Technique, and Boxing-In Technique.
p.38
Special Impression Trays and Their Requirements
What is the spacer requirement for an edentulous/complete tray?
One layer of sheet wax, no need to block undercut unless too severe.
p.29
Special Impression Trays and Their Requirements
What type of tray is required for Alginate impressions?
A perforated spaced tray.
p.15
Models Fabrication Techniques
What should the base of the cast be trimmed to provide?
A flat base with the stone teeth/ridge standing horizontally.
p.8
Manipulation and Setting of Gypsum Products
How does spatulation affect gypsum setting?
Rapid and prolonged spatulation accelerates setting and increases setting expansion.
p.8
Manipulation and Setting of Gypsum Products
What are accelerators and retarders in gypsum manipulation?
Chemicals added to alter gypsum solubility and setting time; accelerators speed it up, while retarders slow it down.
p.6
Types and Classifications of Gypsum Materials
What distinguishes High Strength, High Expansion Dental Stone (Type V)?
It is the most costly of all gypsum materials and has the lowest W/P ratio with higher compressive strength.
p.26
Impression Materials and Their Types
What is an impression in dentistry?
A negative imprint from which a positive reproduction of the arch can be made in the form of casts/models.
p.28
Impression Materials and Their Types
What type of tray is used for master impressions with Impression Plaster?
Spaced non-perforated tray.
p.4
Manipulation and Setting of Gypsum Products
How does the amount of water mixed with gypsum powder affect its strength?
Higher porosity requires more water, leading to a weaker cast.
p.5
Types and Classifications of Gypsum Materials
What is the process of creating a cast using gypsum?
An impression (negative replica) is poured into gypsum to make a cast (positive replica).
p.27
Impression Materials and Their Types
Name a few examples of rigid impression materials.
Impression plaster, impression compound, and zinc-oxide eugenol paste.
p.25
Models Fabrication Techniques
How should the upper cast be positioned on the mounting platform?
The upper cast must be firmly placed with the occlusal plane touching the platform.
p.40
Special Impression Trays and Their Requirements
How thick should the tray periphery be?
2 - 3 mm thick and rounded.
p.35
Special Impression Trays and Their Requirements
What is a specific design consideration for special trays?
Design for different oral situations, such as Oral and Maxillofacial Surgery (OMFS).
p.29
Manipulation and Setting of Gypsum Products
How is Zinc-Oxide Eugenol paste prepared?
Equal lengths of Base and Hardener are mixed on a paper pad for approximately 45 seconds.
p.29
Special Impression Trays and Their Requirements
What type of tray is used with Zinc-Oxide Eugenol paste?
A close fit special tray.
p.40
Special Impression Trays and Their Requirements
What is the first step in the general procedure for making special trays?
Outline the periphery/extension of the tray.
p.31
Manipulation and Setting of Gypsum Products
What precautions should be taken when handling impression materials?
Keep them away from heat sources and handle with care.
p.7
Manipulation and Setting of Gypsum Products
How can setting expansion be decreased?
By adding accelerators like Potassium Sulphate or retarders like Borax.
p.6
Types and Classifications of Gypsum Materials
What is the primary use of Dental Stone, high strength (Type IV)?
Fabricating wax patterns of cast restorations (crown & bridge), implants, and precision attachments.
p.8
Manipulation and Setting of Gypsum Products
How should gypsum be stored to prevent setting issues?
In an airtight, dry area to avoid moisture exposure.
p.24
Models Fabrication Techniques
What should be applied to the arms for separation?
A thin layer of Vaseline.
p.16
Technological Advancements in Dental Materials
What is the impact of technological advancements on dental treatments?
They make treatments more efficient, accurate, and less invasive, improving patient outcomes and technician efficiency.
p.31
Manipulation and Setting of Gypsum Products
How long can irreversible hydrocolloid materials be stored without significant distortion?
Up to 1 hour in a zip-lock plastic bag.
p.37
Special Impression Trays and Their Requirements
What design features should special trays have?
Suitable handle and special designs in correct position and shape.
p.10
Manipulation and Setting of Gypsum Products
What is the first step in the mechanical mixing procedure?
Measure the stone powder and water.
p.7
Manipulation and Setting of Gypsum Products
What is the final setting time for gypsum?
Reached when the materials can be safely handled and the exothermic reaction is over.
p.25
Models Fabrication Techniques
What should be ensured when pressing the upper arm onto the plaster?
Sufficient plaster should cover the locking pin.
p.40
Special Impression Trays and Their Requirements
What is the final step in the tray-making procedure?
Final polishing and cleansing of the tray.
p.7
Manipulation and Setting of Gypsum Products
When is the gypsum material considered ready?
When compressive strength reaches 80% of the strength attained after 1 hour.
p.6
Types and Classifications of Gypsum Materials
What is Dental Stone (Type III) primarily used for?
Making full or partial denture models, orthodontic models, and flasking procedures for partial acrylic dentures.
p.15
Models Fabrication Techniques
How wide should the sulcus area be in relation to its height?
Double the height of the sulcus.
p.31
Manipulation and Setting of Gypsum Products
What must be applied to the surface of impression plaster before pouring stone?
A separating material such as water glass.
p.15
Impression Materials and Their Types
How can you disengage impression plaster from the cast?
Immerse the impression with cast into hot water to swell the starch.
p.25
Models Fabrication Techniques
What should be done with the plaster before lowering the upper arm?
Place a small amount of plaster onto the base of the upper cast.
p.28
Impression Materials and Their Types
What is a significant drawback of impression compound regarding heat?
It is brittle and should be kept away from heat sources.
p.38
Special Impression Trays and Their Requirements
What characterizes a close fitted tray?
It has no spacer and needs to block undercuts.
p.39
Special Impression Trays and Their Requirements
How should the handle be positioned for partial cases?
Nearly extend horizontally or with a bit upward.
p.41
Models Fabrication Techniques
What is the purpose of the light curing machine?
To polymerize the tray material.
p.6
Manipulation and Setting of Gypsum Products
What is the W/P ratio for Dental Stone, high strength (Type IV)?
100g: (specific amount not provided).
p.6
Applications of Gypsum in Dentistry
What is the primary application of Plaster (Type II)?
Diagnostic models, mounting, and flasking.
p.41
Models Fabrication Techniques
What is applied to the cast according to the impression material used?
Suitable layers of spacer.
p.38
Special Impression Trays and Their Requirements
What is the purpose of the spacer in special trays?
To provide room for impression material and determine tissue displacement due to pressure.
p.29
Impression Materials and Their Types
What are the properties of elastic impression materials?
They show flexibility and elastic properties when set, suitable for taking impressions with undercut areas.
p.37
Special Impression Trays and Their Requirements
What is a cost-related requirement for special tray materials?
They should be inexpensive.
p.29
Manipulation and Setting of Gypsum Products
What is the recommended water to powder ratio for Alginate?
Usually 1:1 as recommended by the manufacturer.
p.15
Impression Materials and Their Types
What is the recommended action if you have difficulty removing alginate from the cast?
Cut away the alginate that came out from the perforation, then section and remove it.
p.15
Impression Materials and Their Types
How do you soften zinc-oxide eugenol for removal?
Immerse the impression and cast into hot water.
p.6
Chemical Properties and Behavior of Gypsum
How does the strength of Dental Stone (Type III) compare to plaster?
It is stronger than plaster.
p.6
Chemical Properties and Behavior of Gypsum
Why is higher expansion needed in Type V dental stone?
To compensate for the solidification contraction of some alloys used as base metals for dental casting.
p.39
Special Impression Trays and Their Requirements
What is the purpose of the finger press during impression taking?
For resting fingers and even the impression material.
p.38
Special Impression Trays and Their Requirements
What is the layering requirement for a conservation/partial non-perforated tray?
Two layers of sheet wax covering teeth and all other tissues, 1-2mm away from gingival and 3-4mm for crown and bridge area.
p.41
Models Fabrication Techniques
What is added to the tray for handling?
The handle and finger press.
p.41
Models Fabrication Techniques
What is done to finalize the shape of the tray?
Adapt the sheet material onto the cast and mold the shape.
p.8
Manipulation and Setting of Gypsum Products
What effect does increasing water temperature have on gypsum setting?
It speeds up setting and increases setting expansion, shortening the working time.
p.29
Special Impression Trays and Their Requirements
How is Alginate secured onto the inner surface of the tray?
Glue or adhesive is applied.
p.7
Manipulation and Setting of Gypsum Products
What instruments are used for hand mixing gypsum?
Rubber bowl and plaster spatula.
p.8
Manipulation and Setting of Gypsum Products
Why is it important to keep relevant equipment clean when working with gypsum?
To avoid unwanted acceleration of setting due to set gypsum.
p.8
Manipulation and Setting of Gypsum Products
What are some examples of accelerators for gypsum?
Potassium sulfate and set gypsum (slurry water).
p.6
Applications of Gypsum in Dentistry
What is the primary application of Die Stone (Type IV & V)?
Working models for crown and bridge works.
p.9
Models Fabrication Techniques
What are the two main mixing methods mentioned in Chapter 2?
Hand Spatulation and Mechanical Spatulation.
