Let’s Stick Together Simplifying indirect and direct restoration choice, bonding, and cementation
2013-2014
Jack D Griffin, Jr DMD Diplomat American Board of Aesthetic Dentistry
Accredited American Academy of Cosmetic Dentistry Master Academy of General Dentistry
Thank you for choosing to spend your time with us. We know that there are many choices in continuing education and we sincerely want this to be one of the best experiences in dental CE today. Our goal is to help you gain greater understanding, confidence, and skill that will allow you to take your restorative practice to the next level in dentistry……making your practice more efficient. Please let us know if there is anything we can do to help you as we take a journey down the road of long term restoration success together.
If you don’t know where you are going, any road will take you there.
Let’s Stick Together How do we keep our restorations stuck to the teeth as long as possible? How do we choose materials that last for many years without sensitivity, leakage, fracture, or failure? So many materials, so little time. With a myriad of newer restorative materials and seemingly endless choices in luting materials and bonding systems could this stuff be any more confusing? There are excellent materials today that can help us minimize sensitivity, decrease de-bonding, stop micro-leakage, and reduce problems we may have with our restorations. They key is having an arsenal that is versatile and almost universal in application and understanding how and when to use them. When do we etch, bond, cement, rinse, blow, cure......? How many layers do we need in a posterior composite and how do we get tight contacts and great contours every time? Ever had a patient say “Doc, that tooth was never a problem until you fixed it”? Let’s stop the madness.
The goal of this course is to simplify materials and techniques to provide great success with an increased efficiency with both indirect and direct esthetic restorations. We will learn indications for newer indirect materials such as Lithium Dislicate and Zirconia with preparation and placement methods for each. We will learn how to prep fast for success, do great build-ups, and simplify esthetic post placement with new universal bonding materials. Time will be spent learning BIOACTIVE materials that actually stimulate tooth formation. We will
eliminate problems you have with posterior composites such as weak contacts, sensitivity, and slow placement with predictable matrix systems, bulk fill materials, and great bonding techniques. We will learn how to do it right the first time and to make the practice more enjoyable and efficient.
ourse outline:
1. New indirect materials…. The strongest, most durable and best looking ever 2. Lithium disilicate and zirconia…when and how to use to revolutionize your practice success 3. BIOACTIVE materials…instead of just replacing tooth structure, can we make tooth grow? 4. Universal bonding agents…the new “GOTTA HAVE” materials 5. Making cementation easy and predictable….what type of cement to use and when to use it 6. Bulk fill materials for posterior restorations…more predictable, more efficient 7. The foundation for success…great post and cores, preps, and impressions 8. Predictable bonding, shaping, and contact formation for efficient posterior composites 9. New impression systems…is it time to go digital?
Indirect restorations: They are sexy, they are strong. For many viable reasons lithium disilicate and zirconia have had most of the headlines for indirect restorations in the past few years. There are good reasons for this. They work extremely well if used in the right cases with the right preps and cementation techniques. The vast majority of restorations we place feature one of these 2 materials. If used
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correctly, we are seeing successes passing everything except all gold restorations. There are certainly some things to understand for maximum performance. Let’s go over them…
1. of or pertaining to a monolith. 2. made of only one stone: a monolithic column. 3. consisting of one piece; solid or unbroken: a boat with a monolithic hull. 4. constructed of monoliths or huge blocks of stone: the monolithic monuments of the New Stone Age. 5. characterized by massiveness, total uniformity, rigidity, invulnerability, etc.: a monolithic society.
In dentistry, we are talking about a material with no layering material or add on material…”total uniformity”. The weak link with many of our indirect materials is the add-on porcelain which increases esthetics but gives us only 80-150 MPa of bond to the substrate. Chipping, de-lamination, fracture and other problems are associated with this layering stuff. We have all seen many cases where the porcelain has broken off of the metal of a PFM crown or zirconia framework. The material choice comes down the strongest we can find that meets the minimum cosmetic needs of the patient.
Why monolithic lithium disilicate or zirconia crowns:
1. More esthetic than metal 2. Higher tensile strength than other tooth colored materials 3. Conservative tooth preparation similar to gold 4. Sufficient esthetics to decrease need for layering porcelain 5. Can be bonded or cemented 6. Can have very fast turnaround from lab or in office milling 7. Versatile materials
Lithium Disilicate – e.max A glass with lithium disilicate fillers which is perhaps the most versatile indirect material we have today. It comes in a pressable form (e.max Press, Ivoclar) or as a CAD/CAM block (e.max CAD, Ivoclar). As a monolithic restoration, we have a flexural strength nearly 400MPa and 6 choices in material opacity. Most of the “LiDi” crowns from the lab are used in a pressed form. In office CAD/CAM systems like CEREC and E4D use the material in a block form in a non-crystalized state often called a “blue block”. They become tooth colored and hardened when placed in an oven under vacuum = crystallization. They can be cemented or bonded in place and in the posterior or anterior… this makes it versatile a very versatile material. We bond in all with less than perfect retentive preps or when esthetics is critical. We non-adhesively cement very few.
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Why adhesively cement? 1. Less sensitivity, less microleakage 2. Stronger bond strengths, higher “wettability” 3. Less chance of restoration fracture by “sealing” iatrogenic porcelain cracks, craze lines 4. Universal bonding agents and easier clean up luting materials make it more efficient
We have done CEREC since 1999 with over 10,000 restorations to date. We’ve seen great success…we’ve seen significant failure. Despite the changes in software and milling machinery, e.max is the the most significant change in the chairside CAD/CAM and monolithic world since gold. Tooth preparation: Great bonding cannot compensate for poor tooth preparation. When materials have questionable ability to be bonded, the prep is critical to long term retention. The preparation of the tooth must fit the characteristics of the restorative material and designed to aid in restoration resistance to dis-lodging and fracture. Lithium disilicate bonds very well but may not compensate for preps designed with walls of excessive taper, the “tee-pee” prep, or those with very short axial walls, less than 3mm, and the practitioner may experience more restoration de-bonding. It must be stressed again that this material is very versatile. For veneers 0.3mm reduction with normal veneer guidelines (prep on enamel when possible, no sharp internal angles, quality bonding, etc) is acceptable. For full monolithic crowns 1.0mm in all directions is acceptable with a rounded shoulder or shamfer, no sharp internal line angles, identifiable margins. The more layering porcelain you need, the more reduction that is needed. Restoration cementation – adhesive or non-adhesive Cementing is either adhesive or non-adhesive. A major clinical advantage of zirconia and lithium disilicate is that they can be cemented or bonded in place depending upon the resistance of the preparation and preference of the dentist. In those cases where preparation design is retentive in nature, cementation is a viable option with the amount of surface area and degree of divergence of the prepared walls can provide sufficient micromechanical retention. Resin reinforced glass ionomer cements like RelyX Luting (3M ESPE) or GC Fuji Plus (GC America) and newer bioactive cements like Ceramir (Doxa) have been popular choices because of lower reported sensitivity, ease of use, and long term clinical success on retentive preparations. These cements are often more opaque and less esthetic than the resins and so the more translucent the e.max the more this matters.
The 2 critical junctions during definitive placement of any restoration is first the bond of the luting material to the internal surface of the restoration and secondly to the tooth. When preparations are short, overly tapered, or occlusal forces heavy, resin bonding is indicated and would provide maximum restoration retention, microleakage prevention, and increased fracture/fatigue resistance of the restorative material itself. Failure most often occurs at the cement/restoration interface and not at the cement/dentin interface.
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Important points: UNIVERSAL BONDING AGENTS: (i.e. All Bond Universal, Bisco;
Scotchbond Universal, 3M) have changed our bonding protocol…simpler and better. These are giving us the best all around bond strengths ever to a variety of surfaces whether dry or wet, etched or not etched, metal or porcelain. So…Universal Bond Agents simplify things – no more total and self-etch bond agents, no zirconia or metal primers, no worry about too wet or too dry.
CLEAN after try in: on pre-etched porcelain of any kind (and for zirconia) maximum bond strengths can only be achieved after removing salivary contaminants. Ivoclean (Ivoclar) does this better than anything and conditions the surface for better bonding (particularly zirconia). Must reapply silane Ivoclean use.
If there is little or no enamel, we don’t etch. The universal bonding agents are terrific non-etch adhesives on dentin or prepped enamel… both Bisco and 3M have dual cure universal DBA’s to insure set under opaque restorations. If lots of enamel, selectively etch it first.
Research is showing less long term breakdown of dentin bonds by protease/enzymes if we use something to kill bacterial like chlorhexiding or benzalkonium chloride (BAC) prior to bonding. We use an etch (Etch 37 with BAC, Bisco) when we etch. Certainly an antimicrobial scrub (Concepsis, Ultradent: Cavity Cleanser, Bisco) makes sense as well.
Self-adhesive dual-cure resin cements Like RelyX Unicem (3M), SpeedCem (Ivoclar), SmartCem (Dentsply) show very good retention, little sensitivity, and ease of use as long as the retention of the prep is good. While these cements are popular, the retention and microleakage is not nearly as good as a separate bonding agent applied to the tooth and restoration followed by a dual cure resin cement like All Bond Universal+DuoLink Universal (Bisco) or Scotchbond Universal+RelyX Ultimate (3M).
Adhesive protocol for maximum lithium disilicate dependability (crowns, veneers, etc):
1. Limit layering porcelain where not needed for esthetics 2. Retentive preps – 4-8 degree taper, minimum 3-4mm walls, strong core 3. e.max press – make sure the lab has etched and silanated 4. e.max CAD in office – 20 second 5% HF etch, rinse well, silane, resin depending on
system used for luting 5. Try in. Rinse. Clean with Ivoclean 20 seconds. Rinse well. 6. Universal bonding agent applied to restoration. Air thinned. NO CURE. 7. Isolate tooth. Clean dentin…alcohol on microbrush or aluminum chloride scrub or
chlorhexidine, or pumice 8. Universal bonding agent applied to tooth. Air thinned. NO CURE. 9. Luting material…dual cure resin for crowns or opaque anteriors, light cure only resin for
thin veneers or translucent anteriors (to avoid shade shifting)
Try in, clean……………….Universal DBA on porcelain and tooth…...air thin both…………….place resin cement
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Esthetics of LiDi is at the limit of the ceramist. With proper cut back and addition of layered porcelain, esthetics can be as good as any material out there. Again, lab selection is the determining factor. Blocking dark color is not quite as dependable as more opaque materials like metal and zirconia. Remember, a monolithic piece of LiDi has much less chance of failure than one with layering porcelain, but for highly esthetic cases we use this material for almost all of them. The combination of strength and esthetics with e.max is unsurpassed in esthetic dentistry today. The case above is e.max press, moderate translucency, cut back and customized. Important points of interest:
1. Always show lab the color of the tooth so they can use the correct opacity. There are 5 different opacities of e.max press ingots.
2. Sand blasting with AlO3 may cause tiny fractures which may grow and IS NOT RECOMMENDED by Ivoclar…If you do with e.max CAD, use light pressure, far distance, glass beads, only to remove investment
3. Cementation is allowed for retentive preps, but bonding improves retention and may strengthen porcelain by reducing crack propagation from inside and other iatrogenic problems
4. Don’t over etch … slightly frosty, not chalky… only 20 seconds with 5% HFl, rinse well, silanate 5. Not strong enough for posterior or high stress anterior bridges 6. Adjustments should be done with high speed finish diamonds, water, light pressure. Polish done
with a porcelain polish system. Polish paste on chamy or felt wheel optional. 7. For veneers a minimal prep is supported by Ivoclar…as little as 0.3mm
Zirconia The quest for stronger, longer lasting esthetic restorations has continued since the practice of dentistry began. Today our goal is to combine ease in prep and placement, accepted esthetics, and predictable clinical longevity all at an in a manner that increases practice efficiency in a troubled economy. As we balance the functional performance of a material with the heightened esthetic standards of today, we sometimes have to think about taking a cosmetic step backward to gain more strength and durability. Along with these philosophical dilemmas there is often conflicting information on how best to use and
handle newer materials and techniques: etch or no etch, sand blast or not, light or chemical cure, cement or bond? Advances with indirect esthetic materials the last few years have brought the profession higher levels of strength and esthetics than ever before with materials like lithium dislocate and zirconium oxide . Yttria-stabilized tetragonal zirconia polycrystal, Y-Tzp, has become very widely used the last few years because of its fracture resisting flexural strength over 1000MPa, non-metalic color, kind wear patterns on opposing teeth, easy intraoral polishability, tooth preparation similar to other all porcelain crowns, and excellent long term clinical success.
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Layering porcelain can be added to a zirconium coping to heighten esthetics but the weak adherence of the stacked or pressed layer has been a common area of clinical failure if the layering material is in function. Zirconia is a very strong monolithic restoration and an excellent substructure but the bond between layering porcelain and the zirconia is very clinically significant. Fracture or chipping of the veneering porcelain has been seen in a high percentage of cases and it’s use has been challenged by several researchers there is less failure. It is certainly less opaque and better looking than it has been in years past. Esthetic limitations for monolithic zirconia are overcome these days by using some of the less ugly newer zirconia formulations plus the external staining of the lab. With flexural strengths exceeding 1000MPa, the ability to withstand mastication forces is extremely good with proper prep and impression techniques. The newer less opaque zirconias have made the PFM obsolete in many practices. For molars and teeth being restored to less than the highest cosmetic standards, monolithic zirconia must be considered. The fit is fantastic and the longevity is unsurpassed by anything but gold. Tooth preparation:
Great bonding cannot compensate for poor tooth preparation. Just like we said with lithium disilicate, the prep is critical to long term retention. The preparation of the tooth must fit the characteristics of the restorative material and designed to aid in restoration resistance to dis-lodging and fracture. Zirconia bonding may not compensate for preps designed with walls of excessive taper, the “tee-pee” prep, or those with very short axial walls, less than 3mm, and the practitioner may experience more restoration de-bonding. For full monolithic crowns 1.0mm in all directions is acceptable with
a rounded shoulder or shamfer, no sharp internal line angles, identifiable margins. The more layering porcelain you need, the more reduction that is needed. Cementation Cementing is either adhesive or non-adhesive. A major clinical advantage of zirconia is that it can be cemented or bonded in place depending upon the resistance of the preparation and preference of the dentist. In those cases where preparation design is retentive in nature, cementation is a viable option with the amount of surface area and degree of divergence of the prepared walls can provide sufficient micromechanical retention. Resin reinforced glass ionomer cements like RelyX Luting (3M ESPE) or GC Fuji Plus (GC America) and newer bioactive cements like Ceramir (Doxa) have been popular choices because of lower reported sensitivity, ease of use, and long term clinical success on retentive preparations. These cements are often more opaque and less esthetic than the resins and so as zirconia gets less opaque, this may become a factor when higher esthetics is warranted. The 2 critical junctions during definitive placement of any restoration is first the bond of the luting material to the internal surface of the restoration and secondly to the tooth. When preparations are short, overly tapered, or occlusal forces heavy, resin bonding is indicated and would provide maximum restoration retention, microleakage prevention, and increased fracture/fatigue resistance of the restorative material itself. Failure most often occurs at the cement/restoration interface and not at the cement/dentin interface.
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Non-adhesive cementation without bonding is much easier to clean up…less hygienists screaming at doctors. The reality is that bonding is stronger despite being more technique sensitive. We have to bond when retention is poor or the material is weak. Don’t be afraid of adhesive cementation, work on your protocol and be rock solid in your decision making. That said, non-adhesive cementation feels good to us: easy clean up, fast, dependable, little sensitivity. Remember that even when using
Adhesive cementation gives us the most dependable bond at both cement interfaces. Dual cure resin cements that are bonded both to the zirconia and the tooth are warranted in cases with excessively tapered preps, short preps or small teeth, or questionable occlusal forces. In these cases it is prudent to maximize bonding. A primer (z-Prime Plus, Bisco) should be used with dual cure resin cements if not light curing and a Universal Bonding Agent (All Bond U, Bisco; Scotchbond U, 3M) if light curing for maximum strengths.
“Bio-regenerative” cementation is a newer method where the cement actually stimulates the formation of hydroxyapatite resulting in very little leakage and great retention. Ceramir (Doxa) is such a cement and the bond strength increases and microleakage decreases with time. It is a unique cement combining glass inonomer and calcium aluminate resulting in a “bioactive” formulation. No primer, silane, or bonding agent is neeed. This cement may be the easiest to clean up on the market. Bonding to dentin: Quality adhesive boning to dentin is critical for restoration retention, reduction in sensitivity, and microleakage control. The strongest long term dentin bond is still total phosphoric acid, rinsing, and then application of a dentin bonding agent (DBA). Many practitioners have reservations about completely removing the smear layer because of experience with postoperative sensitivity. To that regard, self-etch self-priming systems with the UNIVERSAL BONDING AGENTS (All Bond Universal – Bisco, Scotchbond Universal – 3M) have shown to give superior bond strengths to dentin, porcelain, zirconia and etched enamel without the nervousness not removing the smear layer by a total etch technique. After blowing thin their low film thickness (~10 microns) will not interfere with restoration seating. Bonding to zirconia: Zirconia (ZrO2) is a silica-free, acid resistant, polycrystalline ceramic making glass etching treatments such as hydrofluoric acid (HFl) followed by silane USELESS. Great bonding depends upon micromechanical interlocking to a roughened surface from sand blasting followed by chemical bonding from a primer followed by a quality dual cure resin-based cement. Dual cure resin cements are preferred in adhesive cementation because of because of the ability to self-cure through opaque zirconia, control of set time is in staff hands, and margins can be light cured to insure setting at this critical junction.
Adhesive protocol for maximum monolithic zirconia dependability:
1. Limit layering porcelain where not needed for esthetics 2. Retentive preps – 4-8 degree taper, minimum 3-4mm walls, strong core 3. Light sandblasting of zirconia 4. Clean zirconia after try in with Ivoclean – primes surface for bonding 5. Universal dual cure DBA applied to zirconia, air thinned 6. Isolate tooth, clean dentin 7. Universal dual cure DBA, air thin, no cure 8. Use dual cure resin cement – always light cure the margin for highest conversion rate
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Important points of interest:
1. Cement whenever the retention is good –3-4mm wall height in all directions
2. When doing adhesive cementation same protocol to tooth and restoration with universal bonding agent
3. Don’t etch tooth unless significant enamel remains 4. Practice distance and cure time with your light to get easy
clean up initial set down in your office… don’t cure contacts at all until flossing done
5. Floss after clean up of buccal and lingual 6. When cleaning up or flossing, make sure pressure is maintained to prevent movement 7. Isolate well when bonding…microleakage is often a direct result of contamination with blood or
saliva
Direct restorations: For many of us who don’t live full time in the Beverly Hills front teeth only world, direct restorations is where we spend much of our clinical time. The key is to be efficient to be profitable while doing work that doesn’t have to be “re-done” or adjusted later. We will briefly touch on a few procedures that can make or break our office efficiency. Post and cores/build ups The foundation is the key. Often little thought goes into the strengthening of
the tooth core and root system. Of course we were taught in school that the post and core does nothing to “strengthen the tooth” but merely to aid in restoration retention. Of course, that was before adhesive dentistry. We must by as diligent and meticulous with our pre-crown foundation as we are when we place veneers. Important points of interest:
1. The strongest post is a sand blasted metal post bonded in place with a resin cement 2. We seldom do them any more because of esthetics and potential root fracture 3. Use a post system with tapered drills and posts for easier seating and removal of less dentin 4. When using etch down a canal, rinse thoroughly and change angles with the water to make sure
of complete removal 5. Only blot dry the canal or paper point, keep moist so the dual cure DBA goes into canal easier 6. Air thin, do not cure 7. A dual cure DBA followed by resin cement/build up from an automix gun (i.e. Core Flo – BISCO,
Build-It – Pentron) and inject filling the canal only. An option is to cement the post with a self-adhesive dual cure resin cement without etching and DBA (ie SpeedCem, SmartCem 2, Rely X Unicem)
8. Place DBA coated post into canal, cure – this will prevent movement of the post while shaping core
9. Complete the core with the build up material, shape, cure
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Direct composites We will spend most of our time on 2 things, bulk filling and contacts. Everyone has their own favorite composite and much of the marketing is spent on delivery these days. Again, pay attention to details when placing them and be meticulous in your steps. Important points of interest:
1. Isolation is key…rubbge dam, Isolite, DentaPop-DryTips. 2. Use new #330 bur on EVERY patient, light pressure, good water. 3. Bond strength to decay is ZERO. Check with caries indicator and
verify how good you really are (Sable Seek, Ultradent). 4. For deep restorations or pulp capping there is a terrific new liner
that stimulates apetite formation called TheraCal (Bisco). A game changer! Biodentine (Septodont) works just as well to stop sensitivity and “heal” dentin but is much harder to use. For TheraCal place on deepest part of prep over pulp, place on slightly moist dentin, 2mm or more from margins, 1mm deep at most, light cure well. Etch and DBA after curing well. Restore as normal.
5. Use a versatile sectional and ring system…it’s a no brainer (ComposiTight 3dXR – Garrison, V3 – Triodent). Pre-wedging is a great way to protect gingiva and aid in sectional placement.
6. Tools like “ReelMatrix or PinchMatrix” (Garrison) are awesome for large restorations and Perform Contact instruments are great for those tough cases.
7. When doing total etch, phosphoric acid with antibacterial only 10-15 seconds, rinse thoroughly, blow only to remove standing water or use suction only to remove excess water
8. Newer UNIVERSAL DBA’s (All Bond Universal, Bisco and Scotchbond Universal, 3M ESPE) are very promising. Etch or no etch, dry or wet, direct or indirect, zirconia or porcelain or composite.
9. At this point in 2013, the best long term bonds to dentin and enamel are with total etch and separate DBA. SELECTIVE etching makes the most sense at this point. That is, etching the enamel only for 10 seconds, thorough rinse, suction dry, followed by a universal DBA on both enamel and dentin.
10. Air thin the solvent well… the ethanol or acetone can cause sensitivity and lessen bond strengths so air thinning us a MUST.
11. If more than 1mm between prep margins on back-to-back restorations, it is more predictable to do one at a time.
12. At this point, the wedge should only hold the matrix against the tooth, the matrix provides shape to the restoration, and the ring is what provides separation to compensate for the matrix
13. Bulk fill dentin replacements (i.e. Venus Bulk Fill – Heraeus, Sure fill – Dentsply, SonicFill – Kerr) are terrific…cover or they’ll be grey.
14. Don’t underestimate trans-enamel curing – cure from 30 seconds occlusal, then facial, then lingual for a more complete cure. Always have the assistant re-cure after final shaping
15. Consider strongly a newer class of flowable restorative giomer materials (Beautifil Flow Plus, Shofu) as a great all round flowable with the ability to withstand occlusal forces. Terrific for many situations … even class II. This stuff is pretty amazing…awesome flow, strength, and beauty for a flowabe and studies have even shown a great ability to hold up in occlusal and Class II situations. Plus, it has a high fluoride release that is RECHARGEABLE. Home fluoride treatments work extremely well with this material for root decay patients, rampant decay, and those patients with less than ideal home care.
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Success is where preparation meets opportunity.
Jack D Griffin, Jr DMD MAGD AACD ABAD [email protected] www.Eurekasmile.com NOTES:
