Adopting a New Philosophy: Minimal Invasion

Many of you reading this article (or family members or people you know) have had the benefit of a less invasive procedure in medicine that changed an outcome. Whether it be arthroscopic surgery, LASIK, ultrasonics for kidney stones, or one of a huge variety of procedures, the practice of medicinehas constantly sought a less invasive way of treating various maladies.
Dentistry is equally seeking a similar approach to finding the most appropriate way to obtain a less invasive method to reach the outcome the patient desires. Materials have changed to allow earlier intervention and smaller restoration of decayed areas, veneers or onlays have taken the place of crowns for many applications, and implants are replacing bridges. However, the philosophy of using minimally invasive procedures is not yet pervasive in dentistry. It is the hope of the World Congress of Minimally Invasive Dentistry (MID) that an acceptance of a philosophy toward "less is more" will become the standard of care.

MINIMALLY INVASIVE STARTS WITH PREVENTION

Figure 1. Extreme caries. Figure 2. Recurrent decay from distal, around facial.
Figure 3. ATP score (very high) of patient in Figure 2.

Minimally invasive procedures have evolved over time in dentistry and have been practiced by any dentist who saw the benefit of doing so. Whether it is the smallest amalgam that would restore the preparation, the least traumatic extraction, or placing an onlay instead of a crown, the evolution continues. Technology and science have brought us to the stage, as in medicine, where we can really concentrate on preservation of each type of tissue - hard or soft - so that the outcome shows a respect for the remaining healthy tissue. If tissue preservation is the focus, then prevention is the keystone to all MID.
Figure 1 exhibits a mouth that had been restored, in the past, for a very high-income attorney living in an exclusive suburb. The issue: what was not done to help this patient manage his or her dental health portends the change needed in how dentistry has been/is practiced. The fix-and-fill approach has denied the medical model of treating the disease (caries), with only the symptoms (decay) being treated.
The MID model includes Caries Management by Risk Assessment (CAMBRA), whereby a patient such as in Figure 1, or a patient with one new lesion (Figure 2), is tested for caries. A correlation exists between the level of ATP (adenosine triphosphate, a high-energy phosphate molecule required to provide energy for cellular function) and levels of Streptococcus mutans and Lactobacillus in the biofilm attached to teeth. Currently, I am using a test for caries brought to dentistry by Dr. Kim Kutsch, whereby ATP is measured for any patient exhibiting any carious activity. Figure 3 shows a very high level of ATP for the patient in Figure 2. (An ATP level of below 1,500 is low risk.) If the outcome of CAMBRA shows moderate to high levels of S. mutans and Lactobacillus, a regimen including chlorhexidine and high-dose fluoride can be instituted by the patient to disrupt the biofilm sheltering these acid-producing bacteria and control the destruction.

EXAMPLES OF LESS INVASIVE PROCEDURES: IMPLANTS ARE MID

Recently this author undertook the education to place implants. Restoring implants for more than 20 years allowed an understanding of how successful and less invasive implants were. Patient acceptance of this treatment was increasing, and it became obvious that I would have more influence in case acceptance if I personally placed the implant(s). However, the real education was not only in placing the implant but in performing the bone grafting necessary for a good outcome.
My instructors, Drs. William Dapper and Nicholas Shubin of the California Academy of Implant Dentistry, taught me that bone grafting is not only the standard of care but the correct application for preservation of an extraction site for future treatment. In addition, Dr. Carl Misch makes the point that without bone grafting an extraction socket, the patient continually loses bone.
Bone grafting is now part of my MID philosophy. The benefits of offering grafting of the site to every patient for whom you are going to extract a tooth will not only satisfy the standard of care but also provide him or her the integrity of a ridge. Ridge preservation will allow for a better pontic site, especially for an upper anterior pontic, or support for a removable appliance. The graft will enhance the future placement of an implant, whether in the short term or long term.
What I learned about the types of grafts has changed my procedure mix. Providing the correct type of graft depends upon the patientís choice of having an implant or not, and it depends upon when the implant may be placed. If the patient would never want an implant placed, a xenograft (synthetic) material such as BioPlant (Kerr) would be used. These grafts do not convert to a bone type conducive for implant placement. If the patient is going to have an implant placed (a true MID procedure), then the timing of implant placement helps direct what type of bone graft to place.

MID SINUS LIFTS

The very latest MID procedure to surface in the implant arena is a sinus lift using one of several different procedures. A sinus lift procedure using the lateral window approach has been the usual way of placing a bone graft between the Schneiderian membrane and the bone below it to increase the bone available for an implant. One new crestal approach with a Waterlase laser (Biolase), through an implant hole preparation short of the sinus by approximately 2 to 3 mm, is much easier, faster, and less invasive. Dr. John Hendy uses a Waterlase laser instead of a trephanation bur, which can create heat and bone necrosis, to complete an osteotomy that is a very rapid, clean, and safe approach to the sinus. As the bone is completely ablated in a circle, the sinus membrane balloons into the sinus cavity, preventing a perforation. Also, the laser tip can be aimed in an enlarging elliptical pattern, which can lift a large area of the sinus, facilitating other implants to be placed in the future if necessary. Insertion of the chosen implants raises the circle of bone, lifting the membrane and allowing the implant to be placed safely. The bleeding that results from the surgery allows for differentiation into bone below the membrane, thus an MID sinus lift.
A second crestal approach sinus lift according to Drs. Kfir, Kfir, Mijiritsky, Rafael-off, and Kaluski is their technique that is a minimally invasive antral membrane balloon elevation followed by maxillary bone augmentation and implant fixation. Their experience suggests that hydraulic sinus condensing is a predictable and minimally invasive alternative for prosthetic rehabilitation of maxillary anterior and posterior regions in the presence of anatomical restrictions to implant placement.
These aforementioned two techniques incorporate into the clinical practice minimally invasive crestal approaches to sinus augmentation, resulting in increased case acceptance with reduced treatment duration, trauma, and cost.

MINI IMPLANTS

Figure 4. Mini implants for immediate overdenture loading.

Dr. Gordon Christensen, writing in the Journal of the American Dental Association (March 2006), says, In my opinion, I find more indications for narrow-diameter implants (~1.8 mm) than for standard-diameter implants if dental implants are ever to achieve their optimum service potential for typical, average-income dental patients, methods need to be found to allow placement of implants in areas of remaining natural bone, using minimally invasive procedures without grafting. The mini-diameter implants have the potential to assist in this challenge. Dr. Todd Shatkin wrote about mini implants in the March 2006 issue of Dental Products Report, saying that he switched to using them exclusively because the procedure is minimally invasive, and patients prefer that option to a long process of multiple procedures.
In the area of removable prosthetics, mini dental implants, also known as MDI, are ultra-small, biocompatible, titanium alloy implant screws approximately 1.8 mm in diameter with a retaining fixture containing an o-ring that is incorporated into the base of a patients denture. The head of the implant is shaped like a ball, and the retaining fixture acts like a socket. The o-ring snaps over the ball when the denture is seated and holds the denture at a predetermined level of force. When seated, the denture gently rests on the patients gum tissue. The implant fixtures allow for micro-mobility while withstanding natural lifting forces. Figure 4 shows my first placement of 3 MDI with the immediate capture of the heads in the denture keeper fixtures. The patient had immediate stability he had not experienced for the many years since losing his last abutment teeth. This minimally invasive technique is fast becoming the system of choice for stabilizing the prosthesis of dental patients.

OTHER EXAMPLES OF MID

Figure 5. Glass ionomer (Fuji Triage) sealant, erupting tooth.

Figure 6. Painful tongue lesion.

Figure 7. One-day healing of lesion in Figure 6.

Figure 8. Minimally invasive carbide burs.

Figure 9. Rapid-cutting carbide burs.

Figure 10. Isolation and mouth prop.

Dr. Henry Evans wrote in Dentistry Today recently (February 2006) how he protects partially erupted permanent molars. Research shows that the operculum-covered portion of the tooth has a prolonged acid attack and is 4 times more likely to develop dentin lesions.1,2 Because of the inability to isolate the occlusal surface under the operculum, a hydrophilic restorative (glass ionomer) is the material of choice.3 The product used was GC Americas Fuji Triage (Figure 5).
Lasers can make a big difference in healing for many applications. For example, when a lesion such as the one seen in Figure 6 is encountered, the low wattage applied either from a diode or a YSGG laser can promote healing one day later (Figure 7).
The use of recently created carbide burs, when used for minimally invasive preparations (Figure 8), can conserve tooth structure compared to more extensive preparations. The concept of removing only the tooth tissue needed to restore the lesion refutes G.V. Black concepts. The resulting preparation would be appropriately restored with a bonded restoration, either composite or glass ionomer.
Another concept of MID relates to the time patients spend in the chair. Each patient would obviously appreciate the increased speed offered by technology such as fast-cutting carbide burs (Figure 9). For example, when a crown is to be prepared, Dr. Bill Blatchford uses the analogy of cutting a board. A diamond for preparation is like using a belt sander from the end of the board, but by using a carbide, it is like cutting the board in half right where you'd like it cut. Enhanced carbides cut so well that they significantly shorten the time of preparation, which patients appreciate.
Every now and then a product comes along that helps the patient and the dentist to make the experience of dentistry easier for both. Isolite (Figure 10) allows for the patient to have mouth support (bite block), isolation of the throat, moisture control for more ideal dentistry, light for better visibility, and the ability of the dentist to work alone as needed. The MID feature is the patients experience it is a better physical experience, and technically better dentistry can be accomplished with retraction.
Dealing with bruxism has been a somewhat problematic issue for years. Many of us have made nightguards with full coverage of an arch. The problem with full coverage has been an increase in the intensity of clenching activity when the posterior teeth have a surface on which to clench. This has often led to increased muscle stress, and headaches may follow. The most MID approach to this problem is the appliance called an NTI-TSS (Keller Labs), which provides for anterior disclusion on a 6-mm wide bar with mandibular freedom of movement and no cupid interference. I have had great success with this appliance, patients appreciate the much smaller design, it can be made easily in a 20-minute visit, and the cost can be reduced from what a lab-processed nightguard costs.
Finally, no-prep veneers are certainly the closest MID approach we have for smile enhancement. Although a few experts insist that veneers can only be put on prepped teeth, the profession is proving them wrong in many cases. Dr. Robert Ibsen (who taught me the veneering concept in 1982) has been focused on tooth preservation for years, with more labs copying his 0.3-mm veneer.
Too many in our profession may be among those who prepare teeth that may not need it, or prep more than is necessary. Dr. Christensen advocates the least preparation possible, if for no other reason than bonding to enamel is certainly more predictable than bonding to dentin. Consider a new way of looking at your veneer cases and see how they may be done with minimal prepping. Explain it to the patient and see if he or she doesn't appreciate your MID approach.

SUMMARY

Dentistry is a dynamic profession with new trends evolving. Minimally invasive dentistry is becoming not just a concept but a way of practicing. Creative people are finding ways, materials, and technology that enable patients to experience less hard-tissue or soft-tissue removal, improved prevention and maintenance, and increased attention to a philosophy of less is more.
The World Congress of Minimally Invasive Dentistry was formed to facilitate the sharing of these new concepts. The members embrace change, and dentistry offers the constant opportunity for such. As the standard of care moves toward minimally invasive dentistry, patients will benefit.


References

1. Milicich G. The dawn of a new era. Presented at: Fifth Annual World Congress of Minimally Invasive Dentistry Conference; August 2004; San Francisco, Calif.

2. Taifour D, Frencken JE, van't Hof MA, et al. Effects of glass ionomer sealants in newly erupted first molars after 5 years: a pilot study. Community Dent Oral Epidemiol. 2003;31:314-319.

3. McLean JW. Clinical applications of glass-ionomer cements. Oper Dent. 1992;5(suppl):184-190.


Dr. Whitehouse is a founding member and past president (2003-2005) of the World Congress of Minimally Invasive Dentistry. He is currently the editor of the WCMID column in Dental Products Report. He practices in Castro Valley, Calif, and can be reached at (510) 881-1924 or This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Note: The World Congress of Minimally Invasive Dentistry will be holding its annual conference from August 16 to 19 in Seattle. Keynote speakers are Drs. Louis Malcmacher and Dan Fisher. For more information, visit wcmid.com.

 

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