Clinical Corner: Information on Dental Procedures

Articles

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Direct Preparation Of Preexisting Implant Abutments For Case Rehabilitation
Flextime Xtreme: The 80/20 Rule
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When Advancing the Bur, One Can Feel the Presence of Dentinal Caries
Precision Trimming and Finishing of Current Dental Restorations Using the Safe End Bur System
Indirect Restorative Tooth Preparation: Extreme Efficiency and Accuracy
Creating Maximum Efficiency and Accuracy In Indirect Restorative Tooth Preparation
Preparation Protocol To Ensure Predictable Aesthetic Restorations
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Fissurotomy: Proactive Treatment for Incipient Decay
Anatomically Adapted Carbide Finishing Burs - Creating Super-Smooth Composite Surfaces in Two Steps
Directions for Use: Dr. David Clark Kit
Placing Traditional Sealants with Enhanced Magnification: Methodology to Increase Both Short-term and Long-term Success - David Clark, DDS
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SS White Surgical Length Oral Surgery Burs: Atraumatic Removal of Teeth for Maximum Bone Preservation

"Ultra Conservative Dental Technique - Fissurotomy® Resin Restorations: Combating Hidden Decay with Early Detection"

George Freedman DDS, FAACD, FACD
Associate Director, Esthetic Dentistry Education Center, SUNY Buffalo
Director, Post-graduate Programs in Esthetic Dentistry, Universities of Minnesota, California (San Francisco), Florida and the Eastman Dental Center
Private practice, Markham, Ontario
Past president of the American Academy of Cosmetic Dentistry

Fay Goldstep DDS, FADI
American Dental Association Speaker on Dentist Health
Faculty, Post-graduate Programs in Esthetic Dentistry, Universities of Buffalo, UCSF, UMKC, Minnesota and Florida
Private Practice Markham, Ontario

Conservative Dentistry

Natural enamel and natural dentin are still the best dental materials in existence, and thus, minimally invasive dental procedures that conserve a greater part of the original, healthy tooth structure must be considered preferable. This statement is the basis for the subculture known as Conservative Dentistry. Conservative Dentistry is a treatment process whereby a minimum of the healthy tooth structure is removed during the restoration process which is inherently a desirable dental objective.

The administration of conservative dental procedures benefits the patient as well. Minimally invasive dental procedures aid in the conservation of healthy tooth structure, there is less discomfort, less need for a local anesthesia, and the real prospect that the repaired tooth will last for a lifetime. The replacement of amalgam restorations often leads to ever larger restorations, each with a shorter life spans than its predecessors, and the replacement procedures themselves may cause damage to adjacent healthy teeth¹.

In many countries, restorative dentistry has been incorrectly labeled- conservative dentistry. It has hardly been conservative of tooth structures, however; traditional methods and materials have been aggressive and highly invasive, and required the removal of otherwise healthy enamel and dentin for various reasons, including the extension of the cavity for the retention of the final restoration and the extension of a preparation for the prevention of recurrent decay. Thus, healthy tooth structures were condemned by the preparation demands of non-adhesive restorative materials.

Figure 1 Fissurotomy Kit

Fortunately, the current era of dentistry has witnessed the development of new materials, new techniques, and new instruments that make conservative dentistry practical and ultraconservative dentistry a reality. Adhesive restorations eliminate the need for more extensive retentive preparations. Enamel-like composites (both hybrid and flowable) offer long-lasting tooth structure replacement with minimum requirements for restorative bulk; little or no healthy tooth material needs to be removed simply to allow for an adequate thickness of the filling material. Early detection and ultraconservative restoration prevent redecay. New instruments such as microabrasion devices and Fissurotomy® burs (SS White®, Lakewood, NJ) offer the dentist the techniques of minimal preparation and maximum patient acceptance (Fig. 1).

Why Watch and Wait?

Routine diagnosis and treatment of large, visible dental decay is relatively easy. Its presence and location are readily accessible. Over the past several decades, however, there have been major changes in the pattern of dental decay. Due largely to the advances in the dental education of the public, there is a greatly increased dental awareness among many population groups. Combined with more frequent and more thorough preventive care by dentists, this has led to fewer and smaller cavities, particularly among the younger age groups.

While this represents great progress for the dental profession (as well as the general population), this trend to fewer and smaller cavities has brought with it some new questions:

1. How to effectively diagnose these much smaller lesions in the teeth?
2. Should these smaller lesions be left to grow larger for easier diagnosis and access or should they be intercepted while they are still small?

The accurate diagnosis of minute lesions may be quite difficult with traditionally accepted techniques. The shape of pit and fissure lesions tends to mask the size and the extent of the defect when the dentist is using an explorer. Forty two percent of these fissures have a narrow occlusal opening and vary in shape as they progress inwards the tooth². Caries is initiated in the lateral walls of the fissure and progresses downward towards the enamel-dentin junction³. The narrow occlusal opening tends to prevent the entry of the explorer into the larger chambers of the lesion, and often only a stickiness of the instrument in the tooth surface is reported. In fact, histologic cross-section has confirmed a ratio of 1:4 (25%) accuracy in diagnosing decay underlying the occlusal surface using the traditional explorer method⁴. This is hardly an impressive rate of success.

Figure 2 Caries not visible radiographically., but seen on cross-section of the tooth

Radiographic diagnosis is an important tool for the practicing dentist. Radiographs can detect caries when none are observed clinically. But negative radiographic results can be misleading. All too often, there are caries present in the tooth that the radiographic process will not reveal (Fig. 2). This is known as the phenomenon of hidden caries,^5,6,7 a condition where the tooth appears caries-free clinically and/or radiographically, but is found to be carious by other diagnostic means. Subsequent cross-sectioning of the tooth clearly reveals caries that has originated at the base of a fissure, and is now spreading along the dentino-enamel junction (DEJ).

Thus, the dilemma of clinically diagnosing small caries at an early stage is a very real problem which cannot easily be solved by existing diagnostic techniques^8,9,10. Explorers and radiographs are simply not adequate tools for this common type of dental lesion.

A further complication is the aggressive use of fluoride on a regular basis by all the members of fluoridated communities. A study in the Netherlands has determined that the entire Dutch population (among others) may be overdosing on fluoride,¹¹ and that this may have resulted in an undiagnosed hidden caries level of approximately 15% in the younger population. The surface-hardening effect of the fluoride on the enamel has the effect of making the tooth surface more impenetrable to exploration, while at the same time masking the carious activity occurring just below the tooth surface and along the DEJ.

The clinical dentist is faced with the option of watching and waiting for early-looking caries, which may in fact be quite active, and invisibly so, just underneath the enamel surface, to become bigger and destroy more healthy tooth structure, or to aggressively eliminate these early lesions and to restore the cavities with ultraconservative restorations.

The time-honored tradition of "watching" incipient decay is no longer tenable. Extensive recent research has clearly indicated that incipient decay may, particularly in fluoridated communities, mask much greater sub-surface carious activity within the tooth. Incipient decay must be intercepted at the earliest possible opportunity to prevent the spread and growth of caries, and to permit the most conservative restoration possible.

The practice of sealing pits and fissures has enjoyed widespread acceptance^12,13,14. There has been continued concern, however, about the placement of sealants over undiagnosed caries. Since it is often difficult to determine caries activity in fissures, an exploratory technique, or excisional biopsy, offers the best access and the best diagnostic/conservative technique for the maximum retention of healthy tooth structures combined with the certain removal of all decay. The excisional bur remodels the anatomy of the fissure, facilitating the access, the acid etching and the bonding of composite resin into the cavity preparation¹⁵.

If this can be accomplished with minimal patient discomfort, preferably without the need for anaesthetic, patient acceptance will be high, and the dentist's conservationist goals can be attained.

Ultraconservative Preparation

The goals of ultraconservative preparation are quite simple:

1. Recontouring the fissure and pit anatomy for access and visibilityExploration of the cavity to ensure that no decay remains undetected
2. Ultraconservative (but complete) caries removal

The practitioner has a number of choices of armamentarium in pursuing the Ultraconservative treatment approach.

Small round burs. While these familiar burs will provide a conservative preparation, good explorer access, and require no learning curve, they are slow and inefficient in cutting through enamel. Local anaesthetic is often required and the shape of the preparation will leave undercut enamel.

Air abrasion. In recent years, many dentists have begun working with air abrasion technology for the preparation of cavities. Air abrasion provides a conservative removal of tooth structure, good explorer access into the preparation, and requires minimal local anesthetic. There is, however, a learning curve associated with these devices in terms of direction, cutting depth and focus of the spray, since unlike burs, there is no tactile feedback during the preparation process. The equipment may be expensive, and most air abrasion procedures are rather messy as the excess abrasive dust tends to spread around the operatory.

Figure 3 Fissurotomy Burs

Excisional Biopsy burs. The Fissurotomy® burs (Fig. 3), specifically designed for recontouring the fissures and accessing decay with minimal enamel removal, are fast-cutting , conservative, and inexpensive. They are instruments that are familiar to every dentist. In almost all cases, no anaesthetic is required by the patient throughout the entire procedure. The use of the Fissurotomy® burs is limited to pits, fissures, and grooves, however, and not indicated for treatment of larger decay.

The Fissurotomy® Kit

Figure 4 Traditional #330 bur on left. Anatomically designed Fissurotomy bur on right

The Fissurotomy® bur is a new approach to Ultraconservative dental treatment. The shape and size of the three unique burs (Original Fissurotomy®, Fissurotomy® Micro STF, and Fissurotomy® Micro NTF) are designed specifically for the purpose of treating pit and fissure lesions. The head length of the Fissurotomy® Original and Fissurotomy® Micro NTF burs is 2.5mm, allowing the dentist to limit the bur tip to cut to just below the DEJ, and not further into the dentin (conservation). The head length of the Fissurotomy® Micro STF is 1.5mm and makes this bur suitable for primary teeth, adult premolars, enameloplasty and for improved sealant retention. The tapered shape of the bur allows the cutting tip to encounter very few dentinal tubules at any given time, and has been designed to minimize heat build-up and vibration. Since the cutting of the Fissurotomy® bur is restricted largely to enamel, patient discomfort is minimized and the need for local anaesthetic eliminated in most cases. The comparison of a Fissurotomy® bur to a regular 330 bur demonstrates the lessened invasiveness of the new design (Fig. 4). Traditional cutting burs remove far more enamel at any depth of cut and are designed to access caries which has progressed well beyond the DEJ, while the Fissurotomy® bur has been anatomically designed to enlarge the fissure and eliminate small caries without removing excessive healthy enamel or dentin.

The cavity preparation must be matched with suitable restorative materials. The closest analog of enamel (direct materials) is composite resin. Since the typical Fissurotomy® preparation is generally a very narrow, long, and irregularly deep space, it is important that the restorative material flow easily into all the nooks and crannies. The dental material of choice for this type of preparation at this time is a flowable composite resin. While hybrid composites are stronger and more wear resistant than flowables, there may be some clinical difficulty ensuring that they penetrate the intricate geometry of the narrow preparation to eliminate all the bubbles and gaps. Packable composites are even more technique sensitive in very small cavities.

The Fissurotomy® Kit includes the Original Fissurotomy® bur, the Fissurotomy® Micro NTF, the Fissurotomy® Micro STF, and the #7406 and #7901 twelve blade finishing burs.

Flowable Composite

Heliomolar Flow (Ivoclar North America, Amherst NY), a well-established flowable microfill (Fig. 5) is the composite material used in the case presentation. This composite flows very readily into all the crevices of the prepared tooth and adapts to any existing adhesive-bonded internal anatomy. It is also easily polishable to a high shine.

Figure 5 Heliomolar® Flow (Ivoclar N.A., Amherst, NY)

The Ultraconservative Technique

1. Probe all pit and fissure areas. Note that while there is no apparent decay, the fissures are somewhat "sticky" to the explorer. Use the Fissurotomy® bur to perform an excisional biopsy of all the carious and suspect fissure areas (Fig. 6). Explore the fissures for decay with the bur, and contour the surrounding enamel to a gentle taper (Fig. 7).	Figure 6 Fissurotomy bur accessing the fissures	Figure 7 The fissure is cleaned and contoured (Step 1)
2. Once the initial preparation is completed, verify the removal of the decay with the caries indicator (Fig. 8). Wash away the caries indicator after 10 seconds, and examine the preparation. The remaining areas of decay are stained red (Fig. 9). Remove these caries with the Fissurotomy® bur. Repeat the caries indicator step until there is certainty that no decay has been left in the fissure.	Figure 8 Caries indicator is painted into the preparation	Figure 9 Remaining decay is stained red by the caries indicator
3. The tapered preparation just within the DEJ is complete (Fig. 10). Should the caries be shallower, there is no need to go as far as the DEJ. 4. Etch the preparation with 37% orthophosphoric acid for 15 seconds (Fig. 11), and then rinse thoroughly with air and water. Leave moist for wet bonding adhesion16.	Figure 10 Final preparation, tapered walls, ending just inside the DEJ (x-section)	Figure 11 Etching the preparation (x-section)
5. Apply Excite (Ivoclar North America, Amherst NY) (Fig. 12), to the water moistened preparation (Fig. 13), and allow 15-20 seconds for hybridization to occur.	Figure 12 Excite adhesive (Ivoclar N.A., Amherst, NY)	Figure 13 Application of Excite adhesive (x-section)
6. Blow off the excess solvent with a short one second blast of air (Fig. 14). Light cure the adhesive for 10 seconds (Fig. 15). Note the curing light transmission through the enamel and the diffusion of the light throughout the occlusal portion of the tooth (Fig. 16).	Figure 14 Eliminating excess adhesive with air syringe (x-section)	Figure 15 Light curing the adhesive for 10 seconds
7. Examine the prepared surface within the fissure for the even, glossy appearance of the light-cured adhesive (Fig. 17). The successful application of the adhesive will minimize or eliminate post-operative sensitivity.	Figure 16 Note light transmission through enamel and dentin (x-section)	Figure 17 Glossy appearance of the light-cured adhesive
8. Inject the Heliomolar Flow into the preparation (Fig. 18). Note the excellent adaptation of the restorative material to the cavity walls. 9. Light cure for 20-40 seconds (Fig. 19), depending on the depth of the fissure.	Figure 18 Injecting the Heliomolar® Flow into the preparation (x-section)	Figure 19 Light transmission through the enamel and the flowable composite restoration (x-section)
10. The finished Ultraconservative restoration (Fig. 20). Check the occlusion. Reduce and polish the occlusal surface of the composite material as required. Note the ultraconservative width of the restoration (1/8-1/10 the intercuspal distance) as compared to a conventional small amalgam (1/3-1/2 the intercuspal distance).		Figure 20 The cured, finished Ultraconservative restoration (note the minimal width of the preparation) (x-section)

The Fissurotomy® technique offers an innovative bur design and restorative system that provides both speed of treatment along with patient comfort, using instruments that are familiar to the dentist and that do not require an investment in new equipment.

Summary

Dentistry benefits the practitioner and the patient alike when Ultraconservative dental procedures are promoted. The conservation of healthy tooth structure is the most important benefit that a doctor can offer to their patients and represents a great step forward for dentistry. The key is early detection and treatment of hidden caries, "Watch and Wait" is no longer acceptable theory for the treatment of hidden carious lesions. Untreated caries, although they may be very small in stature, can be extremely and very rapidly destructive. The earliest detection and treatment of carious lesions promotes complete and sound dental health.

References

1. Mertz-Fairhurst EJ, Ergle JW. Cariostatic and ultraconservative sealed Class I restorations: nine year results. IADR Abstract #2513 J Dent Res 1994;73:416
2. Nagano T. The form of pit and fissure and the primary lesion of caries. Dent Abstr. 1960;6:426.
3. Fejerskov D, Melsen B, Karring T. Morphometric analysis of occlusal fissures in human premolars. Scand J Dent Res. 1973;81:505-509.
4. Al-Sehaibany F, White G, Raney JK. J Clinical Pediatric Dentistry 1996; 20(4):293-298
5. Wenzel A, et al. Radiographic detection of occlusal caries in non-cavitated teeth. Oral Surg Oral Med Oral Pathol. 1991; 72:621-626
6. Weerheijm KL, Gruythuysen RJM, van Amerongen WE. Prevalence of hidden caries. J Dent for Children 1992: 408-412
7. Ricketts D, Kidd E, Weerheijm KL, de Soer H. Hidden caries: What is it? Does it exist? Does it matter? International Dental Journal 1997; 47:259-265
8. Ismail AI. Clinical diagnosis of precavitated carious lesions. Community Dental Oral Epidemiol 1997;25:13-23
9. Verdonschot EH et al. Performance of some diagnostic systems in examinations for small occlusal carious lesions. Caries Res 1992; 26:59-64
10. Weerheijm KL et al. Sealing of occlusal hidden caries lesions: an alternative for curative treatment? Journal of Dentistry for Children 1992:263-267
11. Kalsboek H et al. An gepast advies over het gebruik van fluoride. Ned Tendheeldkd 1990;97:239-242
12. Handelman S, Washburn F, Wooperer P. Two-year report of sealant effects on bacteria in dental caries. J AM Dent Assoc. 1976;93:967-970.
13. Handelman S. Effect of sealant placement on occlusal caries progression. Clin Prevent Dent 1982;4:11-16
14. Mertz-Fairhurst E, et al. Cariostatic and ultraconservative sealed restorations: six-year results. Quintessence Int. 1992;23:828-838.
15. Do Rego MA, Araujo C. A 2-year clinical evaluation of fluoride containing pit and fissure sealants placed with an invasive technique. Quintessence Int. 1996:27(2);99-103.
16. Freedman GA. 5th Generation Bonding Systems. Dentistry Today 1996: 15(11) 68-75.