Written by Stephen D. Poss, DDS Thursday, 31 August 2006 19:00
With the dramatic increase in aesthetic dentistry being performed over the last decade, the technique sensitivity of the total-etch process has become a primary concern. The clinician can easily over-etch the dentin with the phosphoric acid or over-dry the dentin after rinsing the phosphoric acid. In late 2004, a self-etch, self-adhesive, dual-cure resin cement (Maxcem [Kerr]) was introduced to address this concern while simultaneously providing excellent bond strengths, aesthetics, and simplicity. The chemistry of this cement allows the material to be delivered directly into a restoration using a dual-syringe with an automix tip.
Figure 1. One-year-old belleGlass MOD inlay that was cemented with Maxcem.
Figure 2. One-year-old belleGlass DO inlays (on first and second premolars) that were cemented with Maxcem. The marginal integrity of each inlay is very acceptable, and no fractures or microleakage are present.
This case represents one of my typical cases and is a 1-year follow-up. An MOD inlay was placed in a first molar (Figure 1), and DO inlays were placed in first and second premolars (Figure 2), all fabricated with belleGlass (Kerr) and cemented using Maxcem. The marginal integrity of each of the restorations is still very acceptable, and no fractures or microleakage are present.
There are 2 simple steps critical to using Maxcem successfully. The first has to do with initial set time, and the second has to do with cleanup. First, many clinicians place a restoration and then immediately light-cure or tack it into place. Light-curing or even tacking immediately after placement does not give the self-etching properties of Maxcem adequate time to react with the tooth structure. This practice will decrease bond strength and could possibly cause micro-leakage or failure of the adhesive process.
Second, many clinicians often clean excess cement too aggressively immediately following cementation. In doing so, they inadvertently pull Maxcem from the margins before it has had an opportunity to set or be light-cured. This practice will eventually cause marginal degradation and microleakage.
Figure 3. Preoperative view of failed restoration with thermal and pressure sensitivity.
Figure 4. Preparation after amalgam and decay removed.
Figure 5. Gingival retraction paste being applied to retract tissue and dry crevicular fluid.
Figure 6. Detailed impression for laboratory use.
Figure 7. Bis-acrylic temporary material being injected into preformed matrix for provisional.
Figure 8. Provisional restoration after polishing.
Figure 9. Rotary bur cleaning debris after removal of provisional.
Figure 10. Maxcem cement being automix tip-delivered directly into the restoration. No trituration, hand-mixing, or dispensing devices are necessary.
Figure 11. Maxcem being easily cleaned while still in its gel state.
Figure 12. Final belleGlass restoration polished to a high gloss.
This case demonstrates the use of Maxcem with an onlay. A 34-year-old female presented with complaints of thermal and pressure sensitivity in tooth No. 3 (Figure 3). Pressure sensitivity was specific to the distolingual cusp, possibly due to a deep oc-clusal amalgam. There was also distal decay. Instead of treatment planning a more aggressive full-coverage preparation, I chose a conservative restorative approachóa laboratory-created resin onlay.
Figure 4 shows the tooth after removing the amalgam and decay. Since the decay was slightly subgingival, I placed Expasyl gingival retraction paste (Kerr) for 2 minutes to retract the tissue slightly and dry the crevicular fluid around the margins (Figure 5). After rinsing Expasyl thoroughly, I used a fast-acting impression material (Kerrís StandOut, in Fast Set) to take an impression (Figure 6).
The tooth was scrubbed with chlorhexidine and air-dried. A bis-acrylic material (Fill-In [Kerr]) was injected into a previously created matrix (Figure 7) and then placed on the tooth for one minute to make the provisional restoration. The provisional was trimmed and placed with a temporary resin cement (TempBond Clear [Kerr]). The excess was cleaned off, and the provisional was light-cured for 20 seconds. Various polishing cups and points were used to polish the provisional (Figure 8).
The patient returned approximately 2 weeks later to have the final restoration seated. The tooth and surrounding tissue were anaesthetized, and the provisional was removed. A rotary bur (OptiClean [Kerr]) was used to ensure all the debris was removed from the tooth (Figure 9). The tooth was cleaned with chlorhexidine and rinsed, and then the restoration was tried in to verify fit.
I placed Kerr's Silane Primer on the internal surface of the onlay, allowing it to air-dry one minute. I then dispensed Maxcem directly into the restoration (Figure 10). After seating the restoration firmly, only the gross excess cement was removed. After 90 seconds, the restoration was tacked into place for 2 seconds with a curing light. Tacking the restoration (rather than light-curing it) will allow time to floss and remove the additional excess cement while it is still in the gel stage, making cleanup easy (Figure 11). The entire restoration was light-cured for a minimum of 20 seconds, and a fluted 7404 carbide bur (Axis Dental) was used to clean the remaining excess cement. Various polishing points and brushes were used to obtain a high gloss to the belleGlass restoration (Figure 12).
(Note: Studies have shown that blasting the internal aspect of an onlay with CoJet [3M ESPE] in a microetcher improves bond strength by embedding silicate ceramic particles into the resin, which becomes "porcelain-like" and can then be silanated.1)
Many dentists often experience great trepidation in exploring the total-etch technique because of the problems associated with multi-step systems and potential postoperative sensitivity. As described in this article, Maxcem provides a reliable alternative to this technique-sensitive cementation practice.
1. Miller M. CoJet. In: Reality. Vol 16. Houston, Tex: Reality Pub Co; 2002:461.
The author would like to thank Ray Foster and Las Vegas Esthetics for their excellent laboratory work for these cases.
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