A 100-Year Journey From GV Black to Minimal Surgical Intervention

A 100-Year Journey fromGV Black to MinimalSurgical InterventionCE

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Compendium • March 2007;28(3):130-135130

Minimally invasive dentistry(MID), or minimal interven-tion dentistry, is a dental care

concept based on the assessment of apatient’s caries risk and the applicationof the current therapies to prevent, con-trol, and treat the disease.1,2 It is oftenreferred to as treating dental caries witha biologic, therapeutic, or medicalmodel.3 Tyas and colleagues state thatthe MID model has several tenetsincluding, at a minimum, the follow-ing3: (1) remineralization of early lesions;(2) reduction in cariogenic bacteria toeliminate the risk of further demineral-ization and cavitation; (3) minimal sur-gical intervention of caries lesions; (4)repair rather than replacement of defec-tive restorations; and (5) disease con-trol. Although MID includes riskassessment, remineralization, and bac-terial management, this article will dis-cuss the operative aspects of MID. The

minimal surgical procedures currentlyperformed are different from the opera-tive dentistry practiced a generationago. This article will discuss how thenew operative dentistry has beenderived from the tenets of GV Blackpublished over a century ago.

Black published a series of papersand texts on dental materials andpreparation and restoration techniquesbetween 1869 and 1915. Althoughmany current authors have credited orblamed these tenets for overly aggres-sive preparations and restorations inmodern dentistry,2,4 the present authorscontend that Black was the first dentistto propose treating dental caries usingminimal intervention based on theknowledge and materials available atthat time.

In the middle of the 19th century,the exact cause of dental caries wasunknown. Dental preparations were

Mark S Wolff, DDS, PhDProfessor and Chair

Kenneth Allen, DDS, MBAAssistant Professor

James Kaim, DDSProfessor and Associate Chair

Department of Cariology andComprehensive CareNew York University College of DentistryNew York, New York

Abstract

Over the past 140 years, dentistry has matured from the original tenets of GV Blackby moving from “extension for prevention” to a minimal intervention approach. Thisis part of an evolution that stresses a medical, rather than a surgical model for cariesmanagement. This transition has been facilitated by the introduction and advance-ment of adhesive dentistry, which encourages preservation of tooth structure. Evenwith these changes, some of the original writings of Black are still relevant today:“The day is surely coming…when we will be engaged in practicing preventive, ratherthan reparative, dentistry.”

• explain the history behind “extensionfor prevention” and why it no longerapplies.

• discuss why an indirect compositerestoration may be a better choicethan a crown when a single cusp isfractured.

• explain how the introduction of etch-ing and bonding has played a key rolein minimally invasive dentistry.

• describe the advances achieved basedon the changes made to the composi-tion of amalgam.

Learning ObjectivesAfter reading this article, the reader should be able to:

designed at the option of the operating dentist. Dentalamalgam, frequently formulated by the dentist, had littlestandardization, which resulted in materials demonstrat-ing poor performance. Black, a dentist of considerableexperience and observational skills, noted the frequentfailure of dental amalgam restorations with recurrentcaries at the corroded margins of the restorations. Therestorations of that time used an alloy that corroded rap-idly and experienced problems with expansion; there-fore, they failed relatively quickly. Patients were observedto develop caries on virgin interproximal surfacesbecause of the stagnation of food in these uncleansableareas. Patients also were observed to develop cariesaround occlusal restorations that failed to include sus-ceptible pits and fissures.

Black wrote a series of papers that addressed theproblems of caries at the margins of restorations,5-7 amal-gam composition,8 and tooth restorations.9 These papersrepresented the earliest workbooks on the quality ofoperative dentistry of that era, and these papers werebased on the best knowledge available. Black describedthe placement of the outer enamel margins in “self-cleansable areas” so that they terminated in regions lesssusceptible to recurrent caries. Black wrote:

“Certainly that portion near the proximate contact…ismost liable to be attacked; and the liability diminishes as werecede from that point.… It is to cut the enamel marginsfrom lines that are not self-cleansing to lines that are self-cleansing.…When a cavity has occurred in the occludingsurface of a molar, the dentist prepares for filling with theidea that the fissures in this part of the enamel have favoredthe occurrence of the cavity. For this reason, the fissures andgrooves adjoining the cavity, even though not decayed, arecut away to such a point as seems to give opportunity for asmooth, even finish of the margins of the filling. This is doneas a prevention of future recurrence of decay.…”

This led to the now infamous term “extension forprevention,” which could be summarized as “…theremoval of the enamel margin by cutting from a point ofgreater liability to a point of lesser liability to recurrenceof caries.…” Black developed an amalgam alloy less like-ly to corrode and suffer marginal breakdown, whose for-mula remained essentially unchanged until the 1970swhen high copper silver amalgams were introduced.10

Black developed standard and meticulous placementtechniques for dental amalgam that used proper isolation:“…Restorations of cohesive gold and amalgam… requirethe application of the rubber dam….The student or den-tist who earnestly desires to give the best service will,when in doubt, apply the rubber dam.” This remained the

state of dental education and clinical practice until the1950s, 1960s, and 1970s. During this period, severalevents occurred that allowed for the improvement of den-tal amalgams and the introduction of bonded restorations:(1) Amalgams were improved by the development of aprocess where the amalgam alloy was triturated with theideal quantity of mercury (Eames Technique11); (2) clini-cal research resulted in the determination that higher cop-per content alloys have less creep and marginal break-down12-14; and (3) clinical research demonstrated thatsmaller preparations last longer.15 These breakthroughseach led to changes in preparation design and restorationsthat were smaller and more effective.

It is in the breakthroughs associated with bondingthat MID has had its greatest advances. In 1955,Buonocore described a technique for etching enamel sur-faces to make them retentive for a restoration.16 In 1962,Bowen submitted a patent, entitled a “Dental fillingmaterial comprising vinyl silane treated fused silica anda binder consisting of BIS phenol and glycidyl acrylic,”that enabled the restoration of a tooth with a tooth-col-ored plastic better known today as Bis-GMA. These 2developments have led to the creation of tooth conserva-tion or minimally invasive surgical dentistry.

DiscussionDentists have a variety of treatment options for the

restoration of cavitated caries lesions. Restorationoptions range from minimal tooth preparation on theocclusal surface to placement of a crown over the entirecoronal tooth structure. What factors determine thetreatment decisions? The minimal intervention philoso-phy mandates that the least invasive effective therapy,preparation, and restoration be used to restore lesionswith cavitation. This philosophy maintains as a tenet thatsurface demineralization is the first stage in the develop-ment of a caries lesion and is a condition that may bereversed with remineralization therapy (not discussed inthis paper17-19). The basic philosophy recognizes the factthat all restorations have a finite life and that largerestorations (composite or amalgam) have a shorterlongevity than smaller ones.15

Black made a similar observation over a century ago(1891) saying: “…And if the filling should serve for five,ten, or fifteen years, valuable teeth will have been savedto the patient that much longer by filling and afterwardcrowning, than by present crowning....” In other words,always choose the least invasive option because the moreinvasive option is usually available for a later date. The

Compendium • March 2007;28(3):130-135 131

The restorations of that time used an alloy that corroded rapidly and

experienced problems with expansion.

During this period, several events occurred that allowed for the improvement

of dental amalgams and the introduction of bonded restorations.

following are a few examples of the application of MIDprinciples with esthetic restorations:

The changes in the paradigms for restoration ofocclusal caries lesions using a bonded restoration areamong the most dramatic changes in treatment philoso-phy. Black recommended the removal of the entire grooveand the placement of an amalgam regardless of the size ofthe caries lesion (Figure 1A). This protected the unin-volved groove from future caries (Figure 1B). Minimalintervention on the occlusal surface was first described bySimonsen20 and refined by Ripa and Wolff21 as a preventiveresin restoration. The preventive resin preparationrequires the removal of only the caries lesion followed bya composite restorative material. The remaining suscepti-

ble groove or groovesreceive an acid-etched pitand fissure sealant materi-al (Figure 1C). The his-toric rationale for removalof the groove was preven-tion of future caries. Theconcern of future caries inthe groove is easily dealtwith by placement of asealant, a technique welldocumented over the past25 years to prevent caries.22

It has even been demon-strated that properly placed sealants, even if placed overactive caries, have the ability to arrest caries activity formore than a decade.23 This is the same concept as Black’sextension for prevention but uses the advantages of therelatively new restorative materials without the need forsurgical extension.

Minimally invasive surgical procedures apply torestoration of the proximal surface as well. A proper diagno-sis of the location of the caries is essential. Caries that canbe identified radiographically on the proximal surface aspenetrating at least to the dentoenamel junction (somewould advocate penetration even further before interven-tion) requires preparation and removal. The conventional“Black” preparation requires the incorporation of theocclusal groove as part of the restoration. Minimal interven-tion mandates that the groove remain intact unless there iscaries on the surface (even if it is stained) (Figure 2). If thegroove is intact, it can be sealed at the end of the procedure.

The preparation of the proximal box for the “slot”preparation differs from the design discussed by Black,which requires that the margins be brought into a cleans-able area of the interproximal embrasure. Where possible,for composite restorations, the facial and lingual embra-sures are designed to remain closed, providing that thedecay can be accessed and removed. As proximal cariesgenerally occur gingival to the contact area, the gingivalembrasure must always be open to ensure the removal ofall decay (Figure 3A). After the decay is excavated and thefinal restoration is placed, the remaining grooves receivea sealant to complete the restoration (Figure 3B).


Figure 1—(A) Minor decay isolated to the pit areas on a maxillary molar. (B) Typical amalgam restoration removing theentire groove. (C) Preventive resin restoration, removing decay from the pits and sealing the remaining groove structure(adapted from Ripa, LW and Wolff MS, 1992).

Figure 2—Caries present to the dentoenamel junction (DEJ) on the distal of themaxillary first and second bicuspid, almost to the DEJ on the mesial of themaxillary second premolar, and minimal penetration on the mesial of the max-illary first molar. Note the occlusal caries on the mandibular first molar.

Figure 3A—Decay is exposed and excavated. Facial and lingual walls maynot require removal depending on the extension of the caries.

Figure 3B—Tooth is restored with composite and the occlusal surface issealed.

Posterior teeth requiring cusp replacement can berestored using gold restorations as described by Black over100 years ago. These gold restorations may be an onlayreplacing only missing tooth structure. The teeth also maybe restored using full-coverage crowns. The process ofpreparing a full crown involves the destruction of a signif-icant amount of sound tooth structure to develop parallelwalls to create a retentive preparation. A minimally inva-sive esthetic alternative restoration could be the placementof a direct placement composite. However, large directcomposite restorations are difficult to place because of theneed to both maintain strict and complete isolation forlong periods of time and to achieve good physiologicalcontours with well-polished interproximal areas.

These teeth, requiring replacement of a cusp, also maybe restored using indirect composite or porcelain materials.The indirect onlay restorations take advantage of the abili-ty to design and produce a restoration outside the mouth.The restorations may be adjusted, modified, and recon-toured, providing ideal contours in the dentist’s or techni-cian’s hands. These large, indirect esthetic restorations maybe prepared with minimal destruction of additional soundtooth structure as would occur in the fabrication of full-coverage crowns. The onlays are bonded into the prepara-tion so that there is less need to design the restorations tobe mechanically retentive (beyond the bonding).

These restorations can be fabricated using either indi-rect laboratory techniques or using computer-aided designand computer-assisted manufacturing (CAD/CAM). Thelaboratory indirect technique involves making an impres-sion of the preparation, temporization, and the return for asecond visit for the final insertion. The CAD/CAM tech-nique involves an optical impression, computer design ofthe restoration, and a final milling of the onlay during thepatient visit. These restorations, when etched and treatedwith silane, are bonded in place using composite resinsmodified from the original Bowen composition.

The philosophy of minimal surgical intervention andminimal tooth destruction extends to the anterior esthet-ic procedures (eg, diastema closure and peg laterals). Theaddition of a small amount of direct bonded composite, awell-respected art form in the 1980s, can still be usedrather than aggressively preparing the tooth for a porce-lain laminate or full-coverage porcelain crown. The finalrestorative results are esthetic, functional, and can berepaired or replaced without any tooth destruction.(Figures 4A and 4B).

Minimal surgical intervention possibilities have beenfurther expanded by the introduction of new technolo-gies. Hard-tissue lasers, air abrasion, and mini-burs makesmaller, less invasive preparations possible. Each devicepermits the clinician to use a more conservative, lessdestructive approach toward the removal of infectedtooth structure. These devices, along with adhesive den-tistry, allow for a truly defect-specific approach towardcaries removal.

ConclusionMID is the natural evolution of dentistry. As new

materials and techniques are developed, dentistry is obli-gated to review and use the most conservative techniques.Overly aggressive tooth preparation results in increasedincidence of unneeded sequelae, often at great pain andexpense for the patient. The concept of MID is more thana series of “surgical” techniques. MID is a comprehensivepackage of dental care and caries intervention thatinvolves: (a) identifying patients for risk of developingdental caries using existing oral and health conditions as apredictor24; (b) implementing aggressive preventive strate-gies including fluoride therapy, antimicrobial therapy, dietmodification, xylitol and calcium supplementation toreduce the risk such as those described in the tenet of min-imal intervention3; and (c) conservative use of surgicaldentistry to improve the well-being of the patient at the


The changes in the paradigms for restoration of occlusal caries lesions using a bondedrestoration are among the most dramatic

changes in treatment philosophy.

Figure 4A—Lateral incisor with a diastema. Figure 4B—Lateral incisor with diastema closed with composite.

The final restorative results are esthetic, functional, and can be repaired or replaced

without any tooth destruction.

lowest monetary cost, preserving the maximum amount oftooth structure.

MID recognizes that dental caries is a reversible dis-ease that starts with demineralization of the tooth andmay eventually progress to cavitation if the risk factorsare not brought under control. Black commented back in1896 on the future of dentistry and the philosophy ofprevention in a speech to young dentists25:

“The day is surely coming and perhaps within thelifetime of you young men before me, when we will beengaged in practicing preventive, rather than reparativedentistry. When we will so understand the etiology andpathology of dental caries that we will be able to combatits destructive effects with a systemic medication.”

References1. McIntyre J. Minimal intervention dentistry. Ann R Aust Coll

Dent Surg. 1994;12:72-79.2. Chalmers JM. Minimal intervention dentistry: part 1.

Strategies for addressing the new caries challenge in olderpatients. J Can Dent Assoc. 2006;72:427-433.

3. Tyas MJ, Anusavice KJ, Frencken JE, et al. Minimal interven-tion dentistry—a review. FDI Commission Project 1-97. IntDent J. 2000;50:1-12.

4. Mount GJ. Minimal intervention dentistry: rationale of cavitydesign. Oper Dent. 2003;28:92-99.

5. Black GV. The management of enamel margins. Dental Cosmos.1891;33:1-14.



8. Black GV. The effect of oxidation on cut alloys for dental amal-gams. Dental Cosmos. 1896;38:43-48.

9 Black GV. A Work on Operative Dentistry in Two Volumes.Chicago, Ill: Medico-Dental Publishing Co; 1908.

10. Anusavice KJ. Phillips’ Science of Dental Materials. 11th ed. StLouis, Mo: Saunders; 2003.

11. Eames WB. Preparation and condensation of amalgam withlow mercury alloy ratio. J Am Dent Assoc. 1959;58:78-83.

12. Osborne JW, Norman RD. 13-year clinical assessment of 10amalgam alloys. Dent Mater. 1990;6:189-194.

13. Letzel H, van’t Hof MA, Marshall GW, et al. The influence ofamalgam alloy on the survival of amalgam restorations: a sec-ondary analysis of multiple controlled clinical trial. J Dent Res.1997;76:1787-1798.

14. Mahler DB. The high-copper dental amalgam alloys. J DentRes. 1997;76:537-541.

15. Osborne JW, Gale EN. Relationship of restoration width, toothposition, and alloy to fracture at the margins of 13- to 14-year-old amalgams. J Dent Res. 1990;69:1599-1601.

16. Buonocore MG. A simple method of increasing adherence ofacrylic filling materials to enamel surfaces. J Dent Res. 1955;34:849-853.

17. Reynolds EC, Walsh LJ. Additional aids to remineralization oftooth structure. In: Mount GJ, Hume WR. Preservation andRestoration of Tooth Structure. Los Gatos, Calif: KnowledgeBooks and Software; 2005:111-118.

18. Reynolds EC. Anticariogenic complexes of amorphous calci-um phosphate stabilized by casein phosphopeptides: a review.Spec Care Dentist. 1998;18:8-16.

19. Tung MS, Eichmiller FC. Amorphous calcium phosphates fortooth mineralization. Compend Contin Educ Dent. 2004;25(9suppl 1):9-13.

20. Simonsen RJ. The preventive resin restoration: a minimallyinvasive, nonmetallic restoration. Compend Contin Educ Dent.1987;8:428-432.

21. Ripa LW, Wolff MS. Preventive resin restorations: indications,technique, and success. Quintessence Int. 1992;23:307-315.

22. Bader JD, Shugars DA. The evidence supporting alternativemanagement strategies for early occlusal caries and suspectedocclusal dentinal caries. J Evid Base Dent Pract. 2006;6:91-100.

23. Mertz-Fairhurst EJ, Curtis JW Jr, Ergle JW, et al. Ultracon-servative and cariostatic sealed restorations: results at year 10.J Am Dent Assoc. 1998;129:55-66.

24. Fontana M, Zero DT. Assessing patients’ caries risk. J Am DentAssoc. 2006;137:1231-1239.

25. Black GV. Speech to young dental students 1896. In: Ring ME.Dentistry and Illustrated History. New York, NY: Mosby-YearBook, Inc; 1985:276.



1. Tyas and colleagues state that minimally inva-sive dentistry (MID) model has several tenetsincluding:a. demineralization of early lesions.b. reduction in cariogenic bacteria.c. replacement rather than repair of defective

restorations.d. all of the above

2. In the middle of the 19th century, the exactcause of dental caries was:a. bacteria.b. fungus.c. mold.d. unknown

3. Black wrote a series of papers that addressedthe problems of:a. tooth restorations.b. amalgam composition.c. caries at the margins of restorations.d. all of the above

4. Black developed an amalgam alloy less likelyto corrode and suffer marginal breakdown,whose formula remained essentiallyunchanged until when?a. 1950sb. 1960sc. 1970sd. 1980s

5. The process where the amalgam alloy was trit-urated with the ideal quantity of mercury iscalled the:a. Eames Technique.b. Black Technique.c. Osborne Technique.d. Mercury Technique.

6. The basic philosophy of minimal interventionrecognizes the fact that all restorations have afinite life and that large restorations have______ smaller ones.a. greater longevity thanb. a shorter longevity thanc. the same longevity asd. equal to greater longevity than

7. As described by Simonsen, the preventiveresin restoration requires the removal of onlythe caries lesion followed by:a. an amalgam restoration and sealant.b. a silicate cement restoration and sealer.c. a composite restorative material.d. an acrylic (mma) resin and sealer.

8. The conventional “Black” preparation requiresthe incorporation of the _____ as part of therestoration.a. occlusal grooveb. gingival marginc. dentoenamel junctiond. lingual surface

9. Which device permits the clinician to use amore conservative, less destructive approachtoward the removal of infected tooth structure?a. air abrasionb. mini-burc. hard-tissue laserd. all of the above

10. MID recognizes that dental caries is areversible disease that starts with what?a. caries lesionb. demineralization of the toothc. cracked restorationd. spontaneous bleeding

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A 100-Year Journey From GV Black to Minimal Surgical Intervention