INTRODUCTION
As I ponder my 42-year profession, I’m struck by how a lot progress has been made in the area of dentistry generally and in dental impressions specifically. Two different observations additionally strike me: First, it’s just about inconceivable for youthful dentists to totally respect simply how far the apply of dental impressions has are available in the previous 70 years. Second, many dentists of all ages are unsure about the position—and even the very existence—of typical dental impressions in the period of digital dentistry.
This article is meant to shed what I hope might be some useful mild on the previous, current, and future of dental impressions.
BALANCING THE ART, SCIENCE, AND BUSINESS OF DENTAL IMPRESSIONS
Suppose you’ve got learn any of my different articles or attended any of my lectures. In that case, you might be in all probability conscious of my deep conviction that true success in personal apply comes solely when the dentist constantly finds the steadiness between the artwork, science, and enterprise of dentistry. Metaphorically talking, I imagine that dental success rests on the following “3-legged stool”:
- Art—creating one thing lovely
- Science—utilizing an evidence-based strategy incorporating the newest analysis
- Business—having the ability to affordably reproduce procedures in a well timed method
You can create a stupendous restoration out of completely different shades of cleaning soap, nevertheless it received’t final as a result of it’s constructed on dangerous science, and it received’t be good enterprise as a result of it won’t final. Conversely, you could possibly make a entrance crown out of strong titanium that may final endlessly, nevertheless it received’t be lovely, and the affected person won’t settle for it. Or you could possibly do a really fast process that may earn you numerous on a per-hour foundation, nevertheless it wouldn’t be based mostly on sound science or look lovely and finally wouldn’t be acceptable to sufferers. Only when you’ll be able to test all 3 bins—nice artwork, nice science, and nice enterprise—will you have the ability to obtain sustained success in your apply. And that maxim is especially true with dental impressions.
IMPRESSION-TAKING MATERIALS: HOW FAR WE’VE COME
Here’s a quick historical past of the impression supplies our career has relied on over the final century-and-a-half:
- 1800s—wax or plaster of Paris dominated
- Forties—alginate supplies had been launched
- Fifties—elastomeric impression supplies had been launched, that includes silicon-based supplies, polyethers, and polysulfides
- Nineteen Sixties—reversible hydrocolloid impression supplies gained reputation due to the main development these hydrophilic supplies introduced in phrases of capturing correct impressions regardless of the presence of saliva and blood.
- Seventies—a brand new era of elastomeric impression supplies was launched, providing extra viscosity and elasticity, related to rubber-based supplies, and enabling floor supplies to be captured much more precisely.
And, of course, now we’ve got the choice of taking digital impressions. Figures 1 and 2 dramatically illustrate simply how far we’ve include dental impression know-how.
Figure 1. Copper bands for impression taking.
Figure 2. Digital impressions.
The key, as I’ll focus on under, is to create these analog impressions by:
- Selecting the correct strategies
- Using these strategies exactly the means they’re designed to be used, and
- Using the proper supplies with these strategies.
The reality is that, with the correct approach, it’s nonetheless doable to use a easy copper band to create a beautiful impression. However, it’s very troublesome for the practitioner and very uncomfortable for the affected person. In distinction, digital impressions are a lot simpler for each practitioner and affected person. But for all the advantages of digital impressions, there are various conditions for which analog impressions will not be solely extremely related however clearly preferable.
The 3 factors above apply not simply to impression-taking however to just about each dental process. Unfortunately, they too typically aren’t taken to coronary heart by our career. As dentists, we’ve got no proper to criticize the efficacy of a method once we don’t use it correctly.
IMPRESSION TAKING HAS NEVER BEEN EASIER
Remember how troublesome your first impression was in dental college? I bear in mind getting supplies throughout myself and my process associate and pondering that I’d by no means grasp this talent. Fortunately, dramatic enhancements have been made in all the bodily features of impression supplies: wettability, hydrophobic properties, hydrophilic properties, working time, accuracy, sustaining dimensional stability, tear energy, and even the style of the supplies. Moreover, the capability to mechanically combine impression supplies in weapons and cartridges has made them a lot simpler to deal with than mixing them up manually on a pad, which introduces air and different issues to the supplies.
When utilizing the proper strategies, the proper bonding materials, and the proper composite with the proper hue worth and chroma and maintaining in thoughts what the occlusion and the anterior steerage must be and doing it in a well timed method, you’ll obtain steadiness of the artwork, science, and enterprise of dentistry. Now let’s speak about impression taking for composite restorations.
CROWN AND BRIDGE IMPRESSIONS: 3 TECHNIQUES
The following 3 strategies are ceaselessly in use right this moment. The first 2 are typical strategies, whereas the third is unconventional.
1. All-in-one approach:
- A full- or dual-arch impression tray is concurrently stuffed with impression materials whereas a light-body flowable wash is squirted round the tooth with a syringe.
- A standard vinyl polysiloxane (VPS) impression materials is usually used.
2. One-step putty wash approach:
- A putty impression is made, and the tray is taken out of the mouth. The mild physique is squirted into it with a syringe, and the tray is reseated in the mouth.
- Putties from 2 tubs are blended and used as the impression materials.
3. Hydraulic and hydrophobic (H&H) approach:
- The underlying idea is to use hydraulics to push a hydrophobic impression materials succesful of displacing blood and saliva. A preliminary impression is taken; it’s not relieved and doesn’t use a spacer. It’s then lined with the hydrophobic impression materials. The affected person is instructed to chew again into the impression, inflicting the materials to be extruded from the impression. The ensuing hydraulic stress forces it into the sulcus laterally and occlusally all through the complete impression. The tray is rarely faraway from the mouth.
- A high-durometer VPS impression materials is required for the preliminary impression. A lightweight-body impression is used inside the preliminary impression.
Crown and Bridge Impressions: The H&H Technique
Let’s go into extra element about the H&H approach for 3 causes. First, it’s much less effectively understood than the 2 typical strategies. Second, in my expertise, it’s the handiest approach. And third (full disclosure time), I invented and patented the approach.
I launched the H&H approach in 1998 to tackle one of the most irritating features of making last impressions for crowns and bridges: managing end traces that stretch subgingivally. Dentists had been having to deal with issues like relapsing gingival tissue that may hinder the move of impression materials into the sulcus. This was most frequently managed by packing a retraction wire, which was time-consuming, troublesome, and typically uncomfortable for the affected person.
Dentists had been additionally having to deal with gingival hemorrhaging that might fill the sulcus with blood and intrude with the move of impression materials. This was most frequently managed with hemostatic brokers that might require a number of purposes and style dangerous. Moreover, hemorrhaging may recur spontaneously or when the wire was eliminated. And the hemostatic brokers used to tackle the hemorrhaging contained sulfur that might inhibit the setting of VPS impression supplies.
Yet one other downside was that saliva may flood the area if the assistant was unable to keep satisfactory suction and isolation, which was not unusual for some sufferers.
Making last impressions of subgingival end traces can nonetheless be a problem, even below the greatest of circumstances. Fortunately, the H&H impression approach eliminates the want for retraction of the gingival tissue, the want to apply hemostatic brokers, the want for syringe-able retraction clay, and the want for sustaining a dry area. Here’s a fast abstract of how to use this method:
1. Inject a high-durometer VPS (Honigum Pro Putty [DMG America]) onto a plastic or metallic triple tray.
2. The affected person closes into the high-durometer VPS, which types a “peripherally sealed customized tray” round the prep space (Figure 3).
Figure 3. Initial impression with high-durometer VPS (Honigum [DMG America]).
Figure 4. Honigum Pro mild physique (DMG America) syringed onto VPS whereas nonetheless seated in the mouth (blue).
3. After the high-durometer VPS units, the affected person opens whereas your fingers retain the impression on the opposing arch. Note that it’s essential that the tray stay in the mouth at this level. Do not take away and reseat as that is pointless and can lead to reseating errors. The affected person should be in a position to chew again into the impression, and if there are damaged items or interproximal tags, they should be eliminated.
4. Spray, wash, and dry the impression floor whereas in the mouth.
5. Using an auto-mix tip, syringe light-body impression materials (Honigum Pro mild physique [DMG America]) onto the high-durometer VPS in the prep areas and adjoining areas (Figure 4). There’s no want to syringe light-body materials instantly onto the tooth as that tends to lure bubbles. You solely want to syringe the light-body materials into the prep space (Figure 5).
Figure 5. The quantity of mild physique obligatory.
6. Instruct the affected person to shut totally and forcefully, thereby exerting hydraulic drive on the light-body impression materials, and wait till the materials units on the tip of the gun to take away it. The mild physique flows and follows the path of least resistance, first flowing subgingivally since the periphery is sealed by the high-durometer VPS. Typically, the mild physique flows previous the margins. The extra then flows out the periphery. Note that it’s excellent to maintain your hand on the affected person’s chin and masseter muscle whereas the mild physique polymerizes to keep away from affected person motion (Figure 6).
Figure 6. Patient closed (with assist).
7. After the preliminary forceful closure, the affected person ought to stay closed and keep regular stress. When the materials is ready on the tip of the gun, you then can take away and examine your impression (Figure 7).
Figure 7. Final impression (blue and yellow).
As you’ll be able to see, the H&H approach doesn’t name for the preliminary impression tray to be faraway from the mouth after the high-durometer VPS has been used, which implies the impression by no means wants to be reseated.
Over the previous 24 years, the H&H approach has been used efficiently by 1000’s of dentists and written about in dozens of articles. While most of these articles have been favorable, a couple of have levied some criticisms. One criticism is that reseating the impression in the mouth typically leads to a step in the impression. What this criticism fails to perceive is that the H&H approach doesn’t name for the impression tray to be faraway from the mouth, which implies the impression shouldn’t be reseated.
A associated criticism from some is that the approach typically leads to occlusal interferences. The reality is that this won’t occur in case you test to make sure that the tray seats correctly when you’ve got the affected person re-bite into the tray. Occlusal interferences might be averted by having the affected person (1) chew into the tray; (2) open his or her mouth, leaving the tray resting on the reverse arch; and (3) apply biting again into the tray to make sure that she or he does it correctly. By the means, in case you have any materials that breaks off from the interproximals, simply fastidiously transfer it and/or rinse it away from the underside of the tray.
Another occasional criticism has been that there’s an elevated danger of the wash not utterly bonding to the set putty materials due to salivary contamination. The downside is definitely averted in case you merely rinse and dry it—as the approach requires—so there might be no salivary contamination. Some have additionally complained that hydrostatic stress may cause a rebound impact. The reality is that in case you use a high-durometer preliminary impression materials—which, like a typical chew registration materials, might be stiff after setting—there might be no rebound impact. Most high-durometer VPS supplies, resembling DMG’s Honigum Pro line, exhibit the correct stiffness.
FULL DENTURE IMPRESSIONS
The denture impressions approach utilized by most dentists includes doing a primary impression with a inventory tray utilizing an alginate impression materials. The affected person leaves the apply sporting his or her previous denture, after which a customized tray is constituted of the preliminary impression (Figure 8). The affected person then returns per week or so later for the second and last impression utilizing the customized tray.
Figure 8. Custom tray mimicking the affected person’s previous denture.
There is a system known as AccuDent System (Ivoclar Vivadent) that permits you to use a particular proprietary inventory tray with 2 varieties of alginates to create a last impression. While some would possibly desire this feature, I’d reasonably not have to create a mannequin in my workplace earlier than sending it to the dental lab.
My most popular approach for denture impressions includes utilizing a inventory edentulous tray with a high-durometer VPS (Honigum Pro), making that inventory tray right into a customized tray, and then relining it with light-body VPS. This means you’ll be able to take your last impressions on the affected person’s first go to and save her or him a visit to your workplace. Figure 9 exhibits a last denture impression created utilizing this method. Note its capability to reproduce tissue landmarks in nice element.
Figure 9. The last denture impression reproduced tissue landmarks in nice element in a single go to.
The affected person’s time is effective, and she or he will drastically respect having the ability to keep away from a second go to. What’s extra, having the ability to produce the last impression in a single go to drastically reduces your prices and will increase your revenue. It’s the traditional win-win situation for affected person and apply, and it’s laborious to think about why any apply wouldn’t embrace this single-visit impression approach.
Accurate full denture impressions like the one depicted in Figure 9 permit you to obtain 3 essential components:
1. Stability and retention
2. Soft-tissue and alveolar ridge preservation
3. Patient consolation
PARTIAL DENTURE IMPRESSIONS
In my expertise working with advanced partial dentures, it’s very troublesome to create an correct main connector and minor connectors and to seize the delicate tissue utilizing digital impressions. When utilizing digital denture strategies, the try-in is commonly modified utilizing impression supplies and by scanning the impression and sending it over the Internet to the lab for last modifications.
A posh partial denture was clearly required for a affected person who saved breaking his partial dentures (Figures 10 to 15). He was very annoyed by tooth breaking off and having to pay for repairs. He succinctly posed his solely requirement for his partial denture: “I would like to have the ability to chew bones with out my partial breaking.”
Figure 10. Preoperative retracted view.
Figure 11. Final impression of a posh partial denture.
Figure 12. Underside of the advanced partial denture mannequin.
Figure 13. Underside of the mannequin with a significant connector.
Figure 14. The mannequin with denture tooth in place.
Figure 15. Postoperative view.
This made it obligatory to have the partial be metal-supported. The proven fact that such a partial couldn’t be modified with acrylic meant we would wish a level of accuracy of the soft-tissue pickup that may be very troublesome to obtain with digital impressions.
THE BENEFITS OF DIGITAL IMPRESSIONS
There is not any query that digital impressions can seize nice element, as is demonstrated in the printed mannequin in Figure 16.
Figure 16. Printed fashions constituted of digital impressions.
Another benefit of digital know-how because it applies to impression taking is illustrated in Figure 17. The picture exhibits how a chew taken utilizing a digital impression revealed inadequate clearance with the restoration. This enabled a modification to be made earlier than sending the digital file to the laboratory for fabrication of the crown or 3D printing.
Figure 17. A digital impression reveals inadequate clearance.
While digital know-how can provide many benefits in lots of areas of dentistry, not each dental apply can afford to incorporate all of the digital know-how that’s accessible. Fortunately, the dental laboratories might be in a position to digitize the impressions the apply makes utilizing typical impression supplies.
THE RELEVANCE OF ANALOG IMPRESSIONS
Whether you personal your individual digital 3D printer and associated digital gear otherwise you depend on your lab to provide the digital functionality, the reality is that any apply coping with very refined dentistry or treating edentulous sufferers will nonetheless want to depend on analog impression taking.
The efficient creation of dental impressions for advanced implant restorations requires understanding how impressions are to be taken when doing a number of models. In many instances, analog impressions might be the most popular—or solely—choice. For instance, in implant instances, digital scanning is unable to decide up metallic abutments (Figure 18). This requires the use of scan our bodies to decide up the relationship of the implants so {that a} last prosthesis might be manufactured (Figure 19).
Figure 18. Implant abutments make digital scanning impractical.
Figure 19. Final implant prosthesis.
A mix case of a partial and a crown would even be very troublesome to obtain utilizing digital scanning, making an analog restoration like the one proven in Figure 20 advisable. Figure 21 exhibits a closeup of the single crown the place the margins are essential. A single impression was made for the crown and then “pulled” in the grasp impression. The relationship of the single crown to the partial requires an excellent working data of the digital software program. Until this course of turns into less complicated, the conventional analog workflow is smart for many practitioners.
Figure 20. Master impression for a mixture case.
Figure 21. Single-crown impression “pulled” in a grasp impression.
A single impression was taken for the crown, related to how a copper band impression is taken, and then a grasp impression was taken utilizing a high-durometer VPS impression and a light-body impression materials to decide up all of the particulars. Note the element of the crown preparation first and then the grasp impression for the main connector framework.
You would possibly need to take a hybrid strategy that includes typical impressions, scanning them, and having your lab use its digital know-how to fabricate the prosthesis utilizing printed supplies. We’re combining the greatest of each worlds: analog and digital dentistry.
THE HYBRID APPROACH TO IMPRESSION TAKING
A great instance of how analog and digital impression taking can and ought to coexist was demonstrated with a affected person who determined to redo her higher tooth (Figure 22). As might be seen in Figure 23, digital know-how made it straightforward to precisely seize the appropriate chew.
Figure 22. Pre-op view.
Figure 23. Digital picture enabling seize of the appropriate chew.
I then took each digital (Figure 24) and analog (Figure 25) impressions and took a postoperative picture (Figure 26). I’ll depart it to you to guess whether or not it was the digital or analog impression that was used to assist produce this final result.
Figure 24. Digital impression.
Figure 25. Analog impression.
Figure 26. Post-op view.
WE’RE ONLY TRYING TO GET TO PERFECTION
With the proper mindset, supplies, and approach, reaching the excellent margins, the excellent contours, the excellent occlusion, and the excellent shade is simple to do.
Its important that we have the ability to depend on producers to present us with the highest high quality supplies and devices so we will pursue the perfection that all the time appears to elude us.
To have the ability to attempt new, probably higher methods of doing issues, you’ve got to be prepared to stick your neck out. As president and sole member of the Giraffe Society, I apply this daily, impressed by quotes like these from my hero, Albert Einstein:
- “If you’ll be able to’t clarify it merely, you don’t perceive it effectively sufficient.”
- “Anyone who has by no means made a mistake has by no means tried something new.”
- “The measure of intelligence is the capability to change.”
- “Everything should be made so simple as doable. But not less complicated.”
- “Creativity is intelligence having enjoyable.”
If you’re studying this, you’ve almost completed the article. Because that tells me you might be clearly prepared to think about new concepts, I hereby dub thee an honorary member of the Giraffe Society.
CONCLUSION
So can we obtain the steadiness of artwork, science, and enterprise of dentistry?
If we use the greatest supplies and strategies to create lovely dentistry based mostly on the most present science associated to impression supplies, and if we do it in a well timed method so we will earn the highest return on funding for ourselves and our workers, we are going to completely obtain the steadiness of artwork, science, and enterprise of dentistry generally, and dental impressions specifically, and strategy the ever-elusive objective of perfection.
ACKNOWLEDGMENTS
I have to acknowledge the help of my companions and workers for “permitting me to do what I do,” together with Murray Kaiser Dental Lab and North Star Dental Lab, however I’d not or couldn’t have achieved any of it with out Betsy Smirnoff Hoos, who has been by my facet for 50 years. She has been to so many lectures and edited so many articles that “she may do it herself.”
ABOUT THE AUTHOR
Dr. Hoos acquired his MS diploma in biology from the University of Bridgeport, his BA in zoology from Drew University, and his DMD diploma from Tufts University School of Dental Medicine. He lectures nationally and internationally on superior strategies in addition to revolutionary procedures that he’s developed. He maintains a apply, Brush & Floss Dental Center, in Stratford, Conn. He might be reached at [email protected].
Disclosure: Dr. Hoos studies no disclosures.
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