Lec 2 Flashcards
also called as alginate
IRREVERSIBLE HYDROCOLLOID
→ preferred impression material in creating diagnostic casts
→ are essentially sodium or potassium salts of alginic acid and are
therefore water-soluble
IRREVERSIBLE HYDROCOLLOID
True or false
because irreversible hydrocolloid is largely water, it readily
absorbs (by inhibition) as well as gives off (by syneresis) liquid
to the atmosphere, causing distortion of the impression
True
True or false
Alginate impression is the negative copy of the oral cavity. Mixing time is measured from the beginning of integration of alginate with water until consolidation stage.
True
→ impression trays
→ modeling compound
→ mixing bowl
→ mixing spatula
→ gauze squares
→ irreversible hydrocolloid
→ American Dental Association (ADA) type IV or V stone
→ vacuum mixer
→ humidor
→ disinfectant
DIAGNOSTIC IMPRESSION TECHNIQUE
(ARMAMENTARIUM)
True or false
In TRAY SELECTION, tray selection should have a clearance of 1⁄8 inch
True
True or false
→ in reaching an important area in the palate, impression trays
are modified by extending the border with wax or modeling
compounds
→ plastic trays do not retain alginate as well as the metal trays
True
True or false
IMPRESSION MAKING
→ material is mixed to a homogeneous consistency and loaded into the tray, and its surface is smoothed with a moistened gloved finger
→ for optimum results, the teeth should be cleaned and the mouth thoroughly rinsed; some drying is necessary, but excessively dried tooth surfaces cause the irreversible hydrocolloid impression material to adhere
→ a slow gradual force is used in removing the impression taken using irreversible hydrocolloid
True
seemingly minor inaccuracies that can lead to serious diagnostic errors
EVALUATION
for an analysis, the diagnostic casts need to be attached to an articulator, a mechanical device that stimulates mandibular movement
ARTICULATOR SELECTION
True or false
articulators can simulate the movement of the condyles in their corresponding fossae; they are classified according to how closely they can reproduce mandibular border movements
their use often leads to restorations with occlusal discrepancies because these instruments do not have the capacity to reproduce the full range of mandibular movement
SMALL NON-ADJUSTABLE ARTICULATORS
practical approach to obtaining the necessary diagnostic information while minimizing the need for clinical adjustment during treatment
SEMI-ADJUSTABLE ARTICULATORS
has a wide range of positions and can be set to follow a patient’s border movements
FULLY ADJUSTABLE ARTICULATORS
→ this is useful when doing maxillofacial reconstructions
→ these are caliper-like devices used to record the anteroposterior
and mediolateral position of the maxillary occlusal surfaces
FACEBOWS
two types of facebows are recognized:
arbitrary and kinematic
True or false
the mandibular hinging movement around the transverse horizontal axis is repeatable
o facebows are used to record the anteroposterior and
mediolateral spatial position of the maxillary occlusal surfaces in relation to this transverse opening and closing axis of the patient’s mandible
o the facebow is then attached to the articulator to transfer the recorded relationship of the maxilla by ensuring that the corresponding cast is attached in the correct position in relation to the hinge axis of the instrument
True
less accurate; suffice for most routine dental procedures
Arbitrary Facebow
indicated when it is crucial to precisely reproduce the exact opening and closing movements of the patient on the articulator
Kinematic Facebow
HINGE AXIS RECORDING
KINEMATIC FACEBOW TRANSFER
KINEMATIC HINGE AXIS FACEBOW
the clinician can determine the hinge axis of the mandible to within 1 mm by observing the movement of kinematic facebow styli positioned immediately lateral to the temporomandibular joint, close to the skin
HINGE AXIS RECORDING
the kinematic facebow consists of (3) components: a transverse component and two adjustable side arms
HINGE AXIS RECORDING
attached to the portion of the clutch that protrudes from the patient’s mouth
Transverse Rod
attached to the transverse member and adjusted so that the styli are as close to the joint area as possible
Side Arms
→ is time consuming and so, its use is generally limited to extensive prosthodontics, particularly when a change in the occlusal vertical dimension is to be made
→ a less precisely derived transfer would then lead to unacceptable errors and compromise the result
KINEMATIC FACEBOW TRANSFER
ANTERIOR REFERENCE POINT
FACEBOW TRANSFER
CENTRIC RELATION RECORD
JAW MANIPULATION
ANTERIOR PROGRAMMING DEVICE
CENTRIC RELATION RECORDING TECHNIQUE
ARBITRARY HINGE AXIS FACEBOW
→ approximate the horizontal transverse axis and rely on anatomic average values
→ manufacturers design these facebows so that the relationship to the true axis falls within an acceptable degree of error
ARBITRARY HINGE AXIS FACEBOW
the use of an anterior reference point enables the clinician to duplicate the recorded position on the articulator at future appointments
ANTERIOR REFERENCE POINT
an anterior reference point, such as the inner canthus of the eye or a freckle or mole on the skin, is selected
ANTERIOR REFERENCE POINT
ARMAMENTARIUM
→ arbitrary hinge axis facebow
→ modeling compound
→ cotton rolls
FACEBOW TRANSFER
→ provides the orientation of mandibular to maxillary teeth in CR in the terminal hinge position, in which opening and closing are purely rotational movements
CENTRIC RELATION RECORD
centric relation is defined as the ________ relationship
maxillomandibular
→ the condyles should remain in the same place throughout the opening-closing arc
→ trying to force the mandible backwards leads to downward translation of the condyles and restorations made to such a mandibular position are in supraclusion at the evaluation stage
JAW MANIPULATION
→ in some patients in whom CR does not coincide with MI, resistance may be encountered when the mandible is hinged
→ the teeth can be kept apart with cotton rolls, a plastic leaf
gauge, or a small anterior programming device made of autopolymerizing acrylic resin (also known as a Lucia jig)
ANTERIOR PROGRAMMING DEVICE
the choice of recording medium is, to some degree, a function of the casts to be articulated
CENTRIC RELATION RECORDING TECHNIQUE
a malleable material for recording the CR position
REINFORCED ALUWAX RECORD
measures only certain components of mandibular movement thought to be of greatest clinical significance
Simplified Pantograph
fully adjustable articulators
Pantographic Recordings
designed to record and measure functional and border movements
Electronic Pantograph
cut or mold a three-dimensional recording of the jaw movements
Stereograms
tooth contacts and by the shape of the left and right temporomandibular joints
Anterior Guidance
to simulate protrusive guidance and they have lateral wings that can be adjusted to approximate lateral guidance
Mechanical Anterior Guide Table
s used for accurately transferring to an articulator the contacts of anterior teeth
Custom Acrylic Anterior Guide Table
with the advances in computer-aided design and computer-aided manufacturing (CAD/CAM), optical scanning of entire arches has become a fairly straightforward procedure
VIRTUAL ARTICULATORS
