Part 3 Theories (Random) Flashcards
How did you assess the patient’s vertical dimension?
Niswonger’s Physiologic rest space (3 mm) Measured vertical dimension of rest compared with vertical dimension of occlusion and used Silverman/Pound closest speaking space phonetics as a guide
Notable observations included the harmony of the lower third of the face and the interocclusal rest space.
What is the Interocclusal Rest Space average for Class 1, 2, and 3?
Who wrote about it?
2-4mm
Class I average is 3-5mm; Class II average is >5mm; Class III average is <3mm.
Niswonger
Who discussed the S sound in relation to vertical dimension?
Pound and M Silverman
M Silverman defined closest speaking space as the difference between closest speaking position and centric occlusion.
What is the Classic S clearance?
S sound produced when upper and lower incisors are 1mm apart
75% of people have this.
What are the different ways to evaluate vertical dimension according to Turrell (11)?
Pretreatment records, physiologic rest, cephalometrics, closing forces, tactile sense, facial dimensions, phonetics, deglutition, esthetics, open rest method, wear
Each method has its own unique approach and findings.
How do you evaluate vertical dimension with cephalometrics?
Use cephalometric landmarks and anterior reference planes in reference to the Frankfort Horizontal (Chaconas)
This is a baseline used in cephalometric analysis.
What is the golden proportion?
Who discusses this initially and who found that it isn’t a reliable predictor of facial esthetics?
A repeated ratio of 1:1.618 that produces aesthetically pleasing results
Lombardi 1973
Disproved by Mashid 2004 as well as Johnston 2004
Originated in ancient Greece and applied to architecture and dentistry.
What did Robert Vig and Gerald Brundo (UCLA) publish in 1978 regarding tooth display and gender, tooth display and race, and tooth display and age?
On average, men display 2 mm of max central and women display 3.5 mm.
Caucasian’s display 2.5, asian 2, black 1.5.
60+: 0
50-59: .5 max central
40-49: 1 mm
30-39: 1.5
20-29: 3.4
Frush and Fisher (1958) - What did they talk about with dentogenics?
Tooth selection should be sex, personality, and age appropriate. Rounder for more gentle female. Worn for older
What was the conclusion regarding changes in vertical dimension?
Abudo 2012 - Patients adapt to changes in vertical dimension as long as the clinician is careful
Research supports this adaptability in various studies.
Who stated that patients may not adapt to changes in vertical dimension?
Sheppard
Sheppard noted that severely overclosed patients may not adapt to increased vertical dimension.
What information can be obtained from provisional restorations?
Incisal length, incisal palatal contours, vertical dimension, stability of gingival crest after crown lengthening
These factors are crucial for assessing the success of the restorative process.
What is an arcon semiadjustable articulator?
An articulator with condylar path elements in the upper member and condylar elements on the lower member
It accepts a facebow and allows for adjustments based on average condylar pathways.
What classification of articulator was used?
Class III
Class III articulators simulate condylar pathways and accept facebow transfers.
What occlusal scheme was used? Who first promoted it?
Canine Guidance
Mentioned by Damico and supported by various researchers for its benefits in muscle activity.
Also discussed by Williamson, Schuyler, Shupe
What does the term ‘intercondylar distance’ refer to?
The distance between the two condyles
Measured with a pantograph or Cadiax and typically set at 110mm on semiadjustable articulators.
What does Chang’s paper recommend regarding readings for programming articulators?
Using the 10mm readings because they are the most repeatable
This approach minimizes errors in setting the articulator.
How does the electronic pantograph compare to the mechanical pantograph?
Eliminates transfer errors by not requiring facebow transfer
Accuracy is comparable according to Chang (2004).
What is the average intercondylar distance used in most semiadjustable articulators?
110mm
This average helps in setting the articulator for proper function.
What is the average intercondylar distance used by most semiadjustable articulators?
What two authors wrote about this?
110mm
Aull, Lundeen
What effect does increased intercondylar distance have on gothic arch tracing for mandibular molars
Who wrote about this?
Produces a more acute tracing and more distal position of DB groove
Taylor; Aull
What should be in harmony with the incisal guidance?
Posterior determinants
It may override posterior determinants during certain movements.
What factors can be modified in the Hanau quint?
- Condylar Inclination
- Incisal Guidance
- Compensating Curve
- Cusp Height
- Plane of Occlusion
What is Theilmann’s formula for balanced occlusion?
(CG x IG)/(CC x CH x OP) = 1
What are the fixed factors in occlusion according to Boucher?
- Condylar Guidance
- Occlusal Plane
How did Trapozzano and Boucher modify Hanau’s quint?
Trapozzano: Three most important factors: CG, IG, cusp angle. Argues occlusal plane fixed and compensating curve determined by above three.
Boucher: CG, IG, occlusal plane
What is progressive disclusion?
Gnathological concept where each tooth must barely disclude the tooth posterior to it in lateral excursions
How is the occlusal plane determined?
Esthetics of anterior teeth and smile line; posterior occlusal plane developed with a 20° template
What does the facebow accomplish?
Orients the maxillary teeth to the terminal hinge axis
Who said that you do not need to find true hinge axis?
Stuart and Stallard (1960)
Ramjford and Ash (1982)
Okeson
- Stuart & Stallard (1960s)
• Suggested that while hinge axis location is important in theory, minor discrepancies using an arbitrary hinge axis do not significantly affect occlusion in full-mouth rehabilitation.
• Reference: Stuart CE, Stallard H. “Failure in Full Mouth Rehabilitation.” J Prosthet Dent. 1960. - Boucher (1975)
• Stated that arbitrary facebows provide sufficient accuracy, and minor errors in hinge axis location do not compromise clinical outcomes.
• Reference: Boucher CO. “A Clinical Guide for Complete Denture Prosthodontics.” J Prosthet Dent. 1975. - Ash & Ramfjord (1982)
• Noted that an arbitrary hinge axis location is generally adequate and that true hinge axis determination is unnecessary for most prosthodontic cases, including full-mouth rehabilitations.
• Reference: Ramfjord SP, Ash MM. Occlusion. 4th ed. WB Saunders, 1982. - Shafagh, Ash, & Newton (1983)
• Conducted studies demonstrating that using an arbitrary hinge axis does not significantly affect occlusal accuracy in extensive prosthodontic reconstructions.
• Reference: Shafagh I, Ash MM, Newton JP. “Effect of Arbitrary and True Hinge Axis on Occlusal Accuracy.” J Prosthet Dent. 1983. - The Pankey-Mann-Schuyler Philosophy
• Advocates for a practical approach, emphasizing function and occlusal harmony rather than strict hinge axis location.
• Reference: Dawson PE. Evaluation, Diagnosis, and Treatment of Occlusal Problems. Mosby, 1989. - Okeson (Contemporary)
• States that precise hinge axis location is not necessary for most full-mouth rehabilitations, as functional occlusion is adaptable.
• Reference: Okeson JP. Management of Temporomandibular Disorders and Occlusion. Mosby, 2020. - McNeill (1997, The Academy of Prosthodontics)
• Acknowledged that while true hinge axis is biomechanically ideal, the differences between arbitrary and true hinge axes are often clinically insignificant.
• Reference: McNeill C. “Science and Practice of Occlusion.” Quintessence Publishing, 1997.
What is the Frankfurt Horizontal Plane?
Lowest point on orbit to highest point on external auditory meatus (Porion to orbitale)
What is the normal range of rotary jaw movements according to Posselt?
20 mm hinge
What is TMD?
Abnormal, incomplete or impaired function of the TMJ
GPT-7
What is the primary treatment approach for TMD?
Treat with reversible modalities first
What are the treatment goals for TMD?
- Relief of Pain
- Stabilization of condyles in centric relation
What is the cause of TMD according to McNeill?
- Organic
- Nonorganic
- Multifactorial: anatomic, psychological, occlusion
What is the normal Frankfort-Mandibular Angle (FMA)?
Which Army COL wrote about connection between FMA and occlusion?
25° +/- 5
Girard DiPietro - Low FMA (20º): Disclusion
High FMA (29º) group function
How much discrepancy can occur if the facebow is more than 5 mm off anterior-posterior of true hinge axis?
Who published this?
If there is a 5mm error with a 3 mm thick record for hinge axis location, the record is off by .2mm at the 2nd molar
Weinburg’s calculations
What did Teterick and Lundeen find about the true hinge axis?
76% of true hinge axes are within 5mm of the arbitrary hinge axis
What did Preston indicate regarding errors with hinge axis location?
Superior-inferior error produces greater error than comparable anterior-posterior
What percentage correlation of commonly estimated points fall within 5 mm of the kinematic axis according to:
- Schallhorn
- Walker
- 95% correlation
- 20% correlation
When is the kinematic hinge axis truly needed according to Guichet?
Only needed if increasing vertical dimension on the articulator
What is the impact of condylar surtrusion on occlusion?
Is surtrusion or detrusion more “critical” of an adjustment
Increases working cusp height
Detrusion more critical. Can result in interferences and shorter cusp heights
What is the effect of shallow condylar inclination and increased lateral translation?
Requires shorter cusps and more mesial position of DB groove of mandibular 1st molar
Kattadiyil 2021 BECP on CR concluded what about techniques and materials?
Chin point guidance (Lucia), biman manipulation (Dawson), power centric, Gothic arch tracing (Guys), leaf gauge, and anterior deprogramming device are comparable in precision and clinical accuracy.
VPS and Polyether perform best.
What did Kantor and Simon conclude in their papers on CR recording?
Kantor: Biman manipulation most accurate/reproducible, anterior jig retrudes, myomonitor and free closure more anterior.
Simon: Chin point guidance, chin pt with ramus support, biman manipulation no difference
What is the standard medication for GERD?
- H2 blockers
- H+ pump inhibitors
What other medical problems can result from GERD?
Must rule out premalignant changes (Barrett’s esophagus)
What is the definition of retention in dental preparations?
The ability to resist dislodgement along the path of insertion
What is the definition of resistance in dental preparations?
Features that resist mediolateral forces
Describe Parker’s Limiting Taper?
What’s ideal prep taper according to him, but what is acceptable?
Maximal allowable taper that allows for retention and resistance form
Ideal TOC: 2-6º (three degrees on each side). Max 10-20º
What is the role of a gastroenterologist in GERD cases?
Must send all GERD to gastroenterologist to rule out premalignant changes (Barrett’s esophagus).
ADA spec for elastomeric impression materials?
To what micron can the VPS you used reproduce?
25 microns
3M Imprint 4 and Aquasil claim up to 1 micron
What types of erosion can be seen intraorally?
- Rumination Erosion (6-10% in institutionalized patients)
- Bulimia Erosion: Max anterior palatal
- Alcoholics
- Citrus Fruit Erosion/Carbonated beverages: incisal 1/3 max anterior
What is the normal oral pH and gastric contents pH?
Normal oral pH = 6.5; Gastric contents pH = 1.
What is the difference between abrasion, erosion, and abfraction?
- Abrasion: wearing away of tooth through mechanical process
- Erosion: loss of tooth substance by chemical processes that do not involve bacterial action
- Abfraction: multifactorial, thought to be due to tooth flexure from biomechanical loading forces.
Contrast abfraction with abrasion
An abfraction is more angular with sharper margins and absence of a frosted appearance seen in toothbrush abrasion.
What is the abfraction etiology theory proposed by Lee and Eakle?
Parafunctional occlusal loading may result in tooth bending or flexure, inducing stress concentration at the cervical aspect of the tooth.
Who developed a classification system on wear?
Ken Turner and Misssirlian developed a classification system for wear with three categories relative to VDO.
What are the categories of Ken Turner’s classification system?
- Excessive wear with loss of VDO
- Excessive wear without loss of VDO and available space
- Excessive wear without loss of VDO and limited space
Who wrote about porcelain wear?
Oh, Delong, Anusavice.
What is the effect of low fusing ceramics on wear?
They are found to be more abrasive than human enamel and less wear resistant than other feldspathic porcelains.
What is the effect of decreasing oral pH on enamel solubility?
Decreasing the oral pH from 6.5 to 5.5 increases solubility of enamel by 7-8x.
What is Ante’s Law?
The pericemental area of the abutment teeth should equal that of the teeth being replaced.
What is the recommended crown-to-root ratio for FPDs?
Minimum 1:1; Ideal 1:2.
What is the Law of Beams?
Bending or deflection varies directly with the cube of the length and inversely with the cube of the original thickness of the Pontic.
What type of lever is the mandible?
Class III (e.g., fishing pole).
Why use a chamfer margin?
To preserve as much tooth structure as possible and provide adequate marginal seal.
Who discussed margin distortion?
Preston, Campbell, Shillingburg.
What are the effects of oxidation on margin distortion?
Distortion occurs during the oxidation cycle; release of casting stresses improves marginal fit.
What factors determine margin placement?
- Esthetics
- Gingival health
- Retention
- Finishing on sound tooth structure
What is the recommended depth for chamfer margins?
Metal ceramic depths of 1mm or more are recommended.
What is the significance of the limiting taper?
It is the boundary line between tapers that provide resistance form; Parker’s research indicates its importance in clinical success.
What is the setting reaction of Fuji Plus cement?
Acid-base reaction between fluoroaluminosilicate glass powder and aqueous solution of polyalkenoic acids.
What are the advantages of using PVS for impressions?
- Excellent elastic recovery and dimensional stability
- Excellent fine detail reproduction
- Higher patient acceptability
What are Fuji Plus’s ingredients?
fluoroaluminosilicate glass, polyacrylic acid, water, HEMA
What is the recommended thickness for custom trays?
2-2.5mm spacer is recommended for least variation.
What are the disadvantages of using Fuji Plus cement?
Hydrophilic nature causes hygroscopic expansion, contraindicated for all ceramic restorations.
What is the setting reaction of fluoroaluminosilicate glass?
An acid-base reaction between:
* fluoroaluminosilicate glass powder
* aqueous solution of polyalkenoic acids (modified with pendant methacrylate groups)
* chemically initiated free radical polymerization of methacrylate groups.
What types of cements are available?
Types of cements include:
* Glass ionomer
* Resin
* Zinc phosphate
* ZOE (Zinc Oxide Eugenol)
* Tempbond
* Zinc Polycarboxylate (long term provisionalization)
What is the liquid component of glass ionomer RRGI?
Polyacrylic acid
What is the powder component of glass ionomer RRGI?
Fluoroaluminosilicate glass
What is the diametral tensile strength of Fuji Plus? How does this compare to resin and glass ionomer?
30-60 MPa, 180-250 MPa
GI: 10-25; 150-200
Resin: 80-120; 250-400
What is the compressive strength of Fuji Plus?
180-255
What is the ADA specification for cement film thickness?
Cement between two glass slabs must be <25 microns.
Does fluoroaluminosilicate glass release fluoride?
Yes, it contains fluoride but evidence of its effectiveness in caries prevention is inconclusive.
What causes microleakage in dental cements?
Microleakage can be caused by:
* Cement dissolution
* Microfracture of cement
Which cement is the most resistant to microleakage?
Resin composite cement
What type of stone was used for the dies?
Silky Rock Type IV Gypsum
Modified alpha hemi calcium sulfate hemi hydrate
Why was Silky Rock-Type IV Gypsum chosen for dies?
It is a high strength gypsum product with minimal expansion.
How are stones classified?
Stones are classified as:
* Type I: Impression plaster
* Type II: Model plaster
* Type III: Dental stone
* Type IV: Die stone
* Type V: High expansion die stone
What is the Munsell Color System?
A three-dimensional color system with hue, value, and chroma as coordinates.
What is cieLAB?
L=lightness, a+b=chromatic component.
A: Red to green
b: Blue to yellow
What shade guide was used?
Vita-Lumen
What does the Fisher angle represent?
The difference between NW and Protrusive in the sagittal plane.
What is the gap size for soldering?
Approximately 0.31 mm (calling card thickness).
What is the difference between PMMA and PEMA?
PMMA is relatively strong with high polymerization heat, while PEMA has low polymerization shrinkage and heat.
What is the effect of silver in gold-palladium-silver alloys?
It increases expansion and castability, but can cause greening.
What is in solder?
Primarily Au-Ag-Cu.
What is pantographic tracing?
A method for recording mandibular movements.
What adjustment was made to the mandibular lateral translation during voluntary recording?
Increased from 0.5mm to 1mm.
What is contained in feldspathic porcelain?
- Quartz (59%)
- Kaolin (4%)
- Feldspar (10%)
- Alumina (20%)
- Sodium Oxide (7%)
- Calcium Oxide (1%)
What mechanisms hold porcelain on metal?
- Compressive forces
- Chemical bonding
- Mechanical bonding
- VanderWaals forces
What is the ideal difference in coefficients of thermal expansion for porcelain and alloy compatibility?
1 x 10-6 or less.
Metal: Higher CTE than porcelain (porcelain expands and contracts less than the metal)
Ceramic lower CTE
What oxides are added to opaque porcelain to alter refractive index?
- Titanium
- Zirconium
- Tin
- Cerium
How does Feldspathic porcelain differ from all-ceramic systems?
Feldspathic has a random lattice; all ceramics have a more crystalline phase.
What are the firing temperatures for porcelain?
- Opaque: 980C
- 2nd opaque: 950C
- Body (dentine): 920C
- Incisal: 910C
- Glaze: 930C
What are firing temps for Ivoclar Ceram?
What temp for sintering ZirCad Prime?
700-800º C
1500º
Ivoclar Ceram Glaze composition (3)
- Glass frits (silica and alumina)
- Metal oxides (like zirconium oxide and iron, cobalt chromium for color)
- Binders (organic resins like HEMA that burn out during firing)
Four bonding steps of Ivoclar Ceram to zirconia?
Oxide Layer Formation: The sintered zirconia develops an oxide layer (ZrO₂) as a receptive surface for bonding.
- Glaze Melting: The glass frit melts and interacts with the zirconia’s oxide layer.
- Chemical Bonding: Formed between glass frit in the glaze and zirconium oxide on surface.
- Micromechanical Bonding: The glaze material flows into surface micro-irregularities, providing additional retention.
What is the normal depth of a sulcus?
1-3mm.
What is the average sulcus depth reported by Gargiulo?
0.67 mm.
How long did the practitioner wait before taking impressions after crown lengthening?
5 months.
What is the active ingredient in Peridex and its effects?
Chlorhexidine gluconate; antimicrobial with plaque and gingivitis reduction.
Positively charged molecule that binds to cell wall and interferes with osmosis
What hemostatic agent was used during the procedure?
Hemodent (21.3% aluminum chloride).
Vasoconstriction and coagulation
What is the mechanism of action of sialagogue therapy?
Stimulates salivary glands.
What is the antibiotic prophylaxis regimen for a patient allergic to penicillin?
- Clindamycin 600mg 1hr before procedure
- Cephalexin or Cefadroxil 2g
- Azithromycin or Clarithromycin 500mg
What are signs of HIV in an intraoral examination?
- Kaposi’s Sarcoma
- Hairy leukoplakia
- Recurrent Herpes
- Candidiasis
- Angular Cheilitis
What are the contraindicated drugs for glaucoma patients?
Anticholinergics.
How does the stress-strain curve differ for stiff vs. flexible materials?
Stiff material has a high modulus of elasticity
What is yield strength?
Stress at which a material exhibits a specified deviation from proportionality of stress to strain
What is ultimate strength?
The maximum stress that a material can withstand without fracture
What is the proportional limit?
The greatest stress that a material can withstand without deviating from the stress-strain proportion
What is elastic limit?
The greatest stress that a material can withstand without permanent deformation
What is resilience?
Resilience = elastic region under curve only
What is toughness?
Toughness = elastic + plastic region under curve
What is modulus of elasticity?
Measure of stiffness calculated as the slope of the stress/strain curve
Which literature discusses anterior guidance?
Williamson, Shupe
Damico
Which studies indicate patients adapt to increased OVD?
Abduo
Gross, Hellsing, Shupe
What does force equal?
Load
What does moment equal?
Torque
Crown lengthening healing phases?
- Hemostasis
- Proliferation (first 4 weeks) - granulation tissue forms
- Remodeling (1-3 months) - PDL begins to reconnect. Excess bone resorbs, new bone forms. Soft tissue becomes firmer, gingival margin settles around tooth. Keratinization begins as epithelial cells from surrounding gingiva migrate.
- Long term healing (3-12 months) - Final maturation/stability of soft tissue. Permanent sulcus forms.
CTG Healing Phases?
“HIPP REM”
Hemostasis/inflammation- Graft becomes white and desquamatized
1 week - graft “takes” with vascularization and fibroblasts proliferate
Proliferation (1st month) Granulation tissue forms.
Post-surgical healing (1 to 2 months) - Collagen production and graft integration (fibroblasts)
Remodeling/ Establishment of New Attachment 2-6 months (graft matures, fibroblasts lay new collagen fibers align, keratinization increases)
Maturation 6-12 Months (Graft is stable and well-integrated)
Difference between FGG and CTG
FGG: KG/CT harvested; Goal: increase KG
CTG (Only CT, leave behind epithelium) - Goal: Root coverage, gingival thickening
Why was frenectomy necessary?
What are frenums comprised of?
Because it is nonkeratinized, unattached alveolar mucosa and has the potential pull on healthy marginal gingival to create an esthetic defect and a hygienic problem in the area.
Non keratinized, unattached alveolar mucosa with an underlying fibrous attachment to bone.
Difference between aluminum chloride and ferric sulfate?
AlCl3 - Astringent (vasoconstrictor) and coagulates
Ferric sulfate (strong coagulation effect)
