Goodacre Tooth Prep & Clinical Complications Flashcards
- Who first published on total occlusal convergence? What numbers?
- Who offered different numbers?
- What TOC does Goodacre, Campagni, and Aquilino recommend?
- Which authors did research to recommend these numbers?
- TOC is important in what two ways for a crown’s resistance to dislodgement?
- 1923 Prothero 2-5 degrees (also maybe GV Black)
- 1994 Wilson and Chan 6-12 degrees
- 10-20 degrees ToC
- Dodge, Shillingberg
- Resistance to lateral forces and retention along the path of insertion
- Who originally published on “critical convergence angles”?
- For a 10 mm diameter molar tooth prep, what occlusocervical dimension and TOC was found sufficient from that study?
- Which two authors countered this to say it was inadequate and recommended greater occlusal dimension?
- Parker 1988
- 10 mm diameter molar tooth prep with 3 mm of occlussocervical dimension and 17.4 degrees of less of TOC
- Woolsey and Matich found that 3 mm of OC dimension was enough resistance but only at 10 degrees TOC. Insufficient at 20, so study supports greater dimension.
- What factor leads to anteriors and premolars having adequate resistance despite variations in prepared tooth form and dimensions?
- Why do molars have typically less resistance with typical preparations?
- What’s recommend OC/Fl ratio for all teeth?
- What 1984 study is this based on on?
- Favorable OC/FL ratios.
- Molars have larger faciolingual dimension and shorter occlusocervical dimension to produce a lower ratio and poor resistance to dislodgment. Also greater TOC.
- 0.4 ratio
- Weed and Baez 1984- inadequate crown resistance with 10 mm die, 3.5 mm OC dimension, 22 degrees TOC.
- After anatomic reduction, teeth have what shapes?
- What authors in 1978 recommended where proximal grooves should be to provide complete resistance to faciolingual forces?
- Mand molars: rectangular, Max molar: rhomboid, Premolar and anteriors: Oval
- Woolsey and Matich; proximal groove
- Garguilo 1961 proposed that what apparatus should be 2 mm?
- What authors discussed this relation further and coined “biologic width”
- Dimension of epithelial attachment combined with connective tissue attachment occlusal to bone
- Cohen and Ross 1968
- Malament and Socransky 1999 found what in regards to strength of ceramic crowns and thickness? (for DICOR crowns)
- Unable to correlate failure of restorations with thickness when bonded to prepared teeth with resinous cement. No difference between those less than 1 mm thick and greater than 1.5. Recommended to reduce based on ceramic thickness required to get color/contour.
Most common single crown complications? (5)
- Need for Endo (3%)
- Porcelain fracture (3%)
- Loss of retention (2%)
- Perio (0.6%)
- Caries (0.4%)
Most common FPD complications? (8)
- Caries (8% prostheses/18% abutments)
- Need for Endo (7% prostheses, 11% abutments) the
- Loss of retention (7%)
- Esthetics (6%)
- Perio (4%)
- Fracture (3%)
- Prosthesis fracture (2%)
- Porcelain veneer fracture (2%)
Total occlusal convergence
10 to 20º
3 mm for anteriors/PM’s and 4 mm for molar’s references what measurement?
Incisocervical and occlusocervical measurements for resistance
0.4 mm references what measurement?
Occlusocervical to faciolingual ratio
Circumferential morphology should resemble what?
Natural tooth shape (preservation of shape). Rhomboid for max molar, rectangle for mand molar, ovals for anteriors and premolars
Wound Healing
- Hemostasis (within minutes to hours)
Platelets accumulate for a blood clot and trigger the formation of fibrin matrix
Wound Healing
- Inflammatory (24 hours to first week)
Granulation tissue forms and angiogenesis and epithelization begins.
Vasodilation occurs, trigger macrophages and PMLN leukocytes to arrive.
Bone morphogenic proteins and growth/differentiation factors are released. Collagen is deposited and early bond formation occurs.
Wound Healing
- Proliferation (days to weeks)
Mesenchymal cells arrive and differentiate into osteoblasts. Osteoclasts and osteoblasts to begin distance and contact osteogenesis
- Completion of epithelization around three weeks and formation of woven bone
Wound Healing
- Remodeling (3 months)
Osteoblasts/osteoclasts remodel woven bone into lamellar bone
Featherstone
- Most common complications for FPD’s
Goodacre review - Caries was most common complication due to marginal gaps and difficult access to clean
Featherstone - RPD’s
Increased caries and plaque for abutment teeth
Fluoride mechanism in managing caries
- Inhibiting demineralization
- Enhancing remineralization
- At high levels, inhibiting metabolism of bacteria
Factors potentiating caries? (7)
- Acidogenic bacteria
- Reduced salivary function
- Restorations harboring plaque
- Frequent consumption of carbohydrates reducing pH
- Decreased compliance with oral hygiene
- Root exposure
- Wearing FPD or RPD.
Protective factors for caries (4)
- Saliva
- Salivary flow rate
- Antibacterials
- Other factors that raise pH and improve potential for remineralization
Toothpaste fluoride levels
- OTC
- Prescription?
- Varnish? What percent decrease risk in caries? How often to apply?
1000 ppm - reduces caries by 20 to 35%
5000 ppm
12000 ppm - 30% reduction - 3 times a year
Chlorhexidine - mechanism
Strong base with cationic properties. The molecules bind to negatively charged bacteria cell walls and weaken bacteria over time
Interaction between CHX and fluoride?
Should be delivered 1 hour apart as fluoride ion is negative and CHX ion is positive.
Amorphous calcium phosphate - MI Paste - mechanism
Remineralizes tooth structure with high concentrations of calcium and phosphate
Normal salivary rate?
- What is in saliva? (5)
1.5 L/day
- Water
- Buffering agents
- Enzymes
- Remineralization agents (calcum, phosphate, fluoride)
- Fungicidal and antibacterial agents
Key Findings from Weed & Baez (1984)
- Taller crowns provide what?
- Lower tapers (more parallel walls) increase what?
- Shorter preps require what?
- Resistance form is critical in preventing what?
Taller crown preps provide greater resistance to lateral forces
- Lower tapers increase resistance
- Shorter preps require additional features like grooves or boxes
- Resistance form is critical in preventing crown dislodgment under lateral or oblique forces
