Cementation vs Bonding (and dental technology) Flashcards
What is digital dentistry? What are the advantages?
using dental technology to perform dental procedures and techniques instead of relying on outdated mechanical and electronic devices
advantages:
- better fitting resto
- more diversity
- increased speed
- lower cost
- more predictable outcomes
What are some examples of digital dentistry? (4)
- Computer aided design/computer aided manufacturing (CAD/CAM)
- digital radiographs (fast, clear, less radiation)
- intra-oral camera (accurate image of oral anatomy and tooth defects)
- CBCT (3D image)
Why should you never use chamfer margins on zirconia crown preps that are being digitally scanned?
the scanner cannot differentiate the chamfer margin from the gingival margin
What can software like TRIOS 3Shape Smile Design and patient monitoring?
3SS - helps quickly design a smile and show it to the patient before sending it to the lab (greater patient input, better results)
the diagnostic aid via intra-oral scan can help you monitor patients dental situation over time and track changes that are not visible to the eyes and that you can’t rmb e.g. erosion and the effect over time, excellent way to illustrate to the patient what is going on
What are some advantages of digital impressions? (not in lecture)
- labs prefer as they can download info directly into milling system (eliminates stone models and errors)
- reduces remakes via cleaner prep and high accuracy
- better fitting resto that requires minimal adjustment
Property of Rely X Unicem?
acts like a GIC cement
dual cure: both self cures (4mins) and light cures (quicker) - good as it ensures deep interproximal areas are set
Cement or bond zirconia crowns?
with adequate retention and ceramic material thickness can be cemented conventionally (w/o the many technique sensitive bonding steps)
- > 3M Rely X Unicem or Rely X Unicem 2 (self etching adhesive cement)
- > GIC Fuji II LC (also dual cure)
ONLY if not preparation lacks retention -> bonding
Patient comes in with fractured onlay placed 7 years prior. What must be done?
due to lack of retention of prep –> needs full contour zirconia crown
also crown lengthening and adjustment of opposite tooth for tx to be successful
Process for cementing a Zirconia crown. (6) ***
- Request lab blast fitting surface with 25-50microns aluminium oxide (micromechanical retention)
- Clean crown w alcohol before try in
- Treat/clean crown with Ivoclean by Ivoclar (40s, rinse, dry) to remove calcium & phosphate ions contamination from saliva/blood
- Treat surface with Scotchbond universal or monobond plus (universal primers for indirect restos)
- Silanate tooth with primer
- Cement with Nexus 3
Materials for cementing zirconia/
- Rely X Unicem or RXU2
- Fuji II LC
(these avoid technique sensitive bonding steps w silanation etc)
Types of indirect cements?
- Temporary cement e.g. nogenol
- GIC
- RMGIC (Fuji +)
- Resin (Nexus 3)
- Self-etching (Rely X Unicem)
Why dont u have to use Ivoclean with Emax (lithium disilicate glass) and gold crowns
doesnt attract Ca and PO4 ions like Zirconia does
How does Ivoclean work?
has spheres of material have a much larger surface area for calcium and phosphate ions to adhere to than to the ceramic restoration (4x SA of circle)
Why do you need to aluminium oxide blast not etch Zirconia vs Emax?
HF acid doesn’t etch Zirconia, only Emax (which you dont need to alum oxide blast)
Safer alternative to 9.5% HF acid etch and why?
Ivoclean and Monobond Plus /Monobond etch and prime
-> silanates Emax, apply 40s wash and dry then can go straight to bonding resin (HF needs silane primer after)
HF acid causes skin burns
Chemical property of Ivoclar’s SpeedCEM Plus - A CHEMICAL BONDING AGENT (not in written lec, video shown)
contains MDP monomer which forms bonds strongly to Zirconia
phosphate and hydrogen groups bond to Zirconia oxide
+
methacrylate group bonds to composite resin
+
bonds to tooth structure
What MUST you do after adjusting zirconia? What do you use to polish and how/when?
MUST polish, to avoid wear of adjacent teeth
the adjusted surface can develop microcracks otherwise
How to polish and with what?
- > Zircon-Brite polishing paste after using rubber discs (only the former at JCUD)
- try in and use articulating paper BEFORE CEMENTING/BONDING
- take off and put onto the die
- adjust using slow speed with a fine bur (NOT high speed)
- back into the mouth and check occlusion again
but if adjusting crown after it has been cemented/bonded, will be difficult inside mouth as Zircon-Brite bristle brush uses a straight handpiece
OR just adjust the opposing tooth
