Aesthetic Restorative Dentistry: Principles and Practice potx

Chu, DDS, MSD, CDT 6 Chapter Aesthetic Management of Nonvital Discolored Teeth With Internal Bleaching.. AESTHETIC MANAGEMENT OF NONVITAL DISCOLORED TEETH WITH INTERNAL BLEACHING 7 Ming-

Aesthetic Restorative Dentistry Principles and Practice

Dennis P Tarnow Stephen J Chu Jason Kim

Stephen J Chu

Dr Stephen J Chu, DMD, MSD, CDT, is presently the Director of Advanced and International Continuing Dental Education Programs

in Aesthetic Dentistry, a Clinical Professor in the Department of Periodontology and Implant Dentistry at the New York University College of Dentistry, and is a board member of the Advisory Committee Education Policy at the New York Technical College He is also a partner at the New York Center for Specialized Dentistry He is also Section Editor of the Prosthodontics division for

Practical Procedures & Aesthetic Dentistry (PPAD) Over the course of his distinguished career, Dr Chu has received academic honors

that include the Columbia Dentoform Corporation Award in Operative Dentistry and Fixed Prosthodontics and the Granger-Pruden Award for Excellence in Prosthodontic Research

Jason J Kim

Master Dental Technician, Jason J Kim Dental Laboratories/Oral Design, New York, NY; Clinical Assistant Professor, New York University College of Dentistry, New York, NY Mr Kim is a renowned craftsman whose restorations are used by many of the world's

Dennis P Tarnow

As Professor and Chair of the Department of Periodontology and Implant Dentistry at the New York University College of Dentistry, Dr.Tarnow is one of dentistry’s foremost educators and most well-recognized authorities in restorative care He is a recipient of the University’s prestigious Outstanding Teacher of the Year Award and numerous other honors for his dedication to his students and his expertise in implant dentistry Dr.Tarnow has published in leading scientific dental journals for decades and has lectured worldwide on periodontal therapy and implant dentistry

Light and Color 4

Stefan J Paul, DMD

1

Chapter

Current Perspectives on Dental Adhesion 4

Jorge Perdigão, DMD, MS, PhD • Lorenzo Breschi, DDS, PhD

1

Chapter

Dental Luting Cements 4

Douglas A Terry, DDS

1

Chapter

The Interdental Papillae: Aesthetic Parameters Between Teeth and Implants 4

Dennis P Tarnow, DDS

1

Chapter

Laboratory Essentials for the Restorative Dentist 4

Jason J Kim, CDT, MDT • Walter Gebhard, MDT

1

Chapter

Restorative Space Management: Precision Tooth Preparation for Aesthetic Restorations 4

Galip Gurel, DDS • Stephen J Chu, DMD, MSD, CDT • Jason Kim, CDT, MDT

1

Chapter

Restorative-Orthodontic Interrelationships: Orthodontic Aspects

in Aesthetic Restorative Dentistry 4

Frank Celenza, Jr, DDS

1

Chapter

Restorative-Periodontal Interrelationships 4

Robert N Eskow, DMD, MScD • Robert S Lowe, DDS • Stephen J Chu, DMD, MSD, CDT

1

Chapter

Dental Implants 4

Nicolas Elian, DDS • Ziad Jalbout, DDS • Sang-Choon Cho, DDS • Dennis P Tarnow, DDS • Edwin S Rosenberg, BDS, MScD, HDD, DMD

1

Chapter

Diagnosis, Etiology, and Treatment Planning 4

Stephen J Chu, DMD MSD, CDT • Dennis P Tarnow, DDS

1

Chapter

Essentials in Aesthetics 4

Alan Sulikowski, DMD

2

Chapter

The Anterior and Posterior Determinants of Occlusion 4

Stefano Gracis, DMD, MSD • Stephen J Chu, DMD, MSD, CDT

3

Chapter

Tooth Preparation Principles and Designs for Full-Coverage Restorations 4

Jacinthe M Paquette, DDS • Cherilyn G Sheets, DDS, • J ean C Wu, DDS • Stephen J Chu, DMD, MSD, CDT

4

Chapter

Porcelain Bonded Tooth Preparation Designs & Principles 4

Cherilyn G Sheets, DDS • Jacinthe Paquette • DDS, Jean C Wu, DDS

5

Chapter

Restorations of Endodontically Treated Teeth:

New Concepts, Materials, and Aesthetics 4

Yoshihiro Goto, DDS, MSD • Jeffrey Ceyhan, DDS, MSD • Stephen J Chu, DDS, MSD, CDT

6

Chapter

Aesthetic Management of Nonvital Discolored Teeth With Internal Bleaching 4

Syngcuk Kim, DDS, PhD, MD(hon) • Ming-Lung Yang, DMD

7

Chapter

Impression Making 4

Ernesto A Lee, DMD

8

Chapter

Provisional Restorations 4

Ricardo Mitrani, DDS, MSD

9

Chapter

AESTHETIC MANAGEMENT OF NONVITAL DISCOLORED TEETH WITH INTERNAL BLEACHING

7

Ming-Lung Yang, DMD†

Aesthetic considerations have a significant role in defining the direction of treatment in contemporary restorative dentistry Present trends have established the “perceptual need” for whiter teeth, since whiteness is associated with cleanliness and health

Natural teeth display a variety of shades

Color correction or whitening of vital and, more specifically, nonvital teeth has become

an increasing challenge Among the many options available, internal or intracoronal bleaching provides one of the best methodologies to predictably treat nonvital discolored teeth.The benefits include:

• Conservation of remaining coronal tooth structure;

• Nonrestorative intervention (which pre-serves the existing periodontium and rep-resents a cost-effective treatment option);

• Maintenance of original occlusal contacts and relationships;

• Color-matching adjacent teeth with natural color and translucency; and

• Color correction of the tooth preparation

or “stump” shade prior to restoration

*Louis I Grossman Professor and Chairman, Department of Endodontics, University of Pennsylvania School of Dental Medicine, Philadelphia, PA; private practice, New York, NY.

†Clinical Assistant Professor, Department of Endodontics, University of Pennsylvania School of Dental Medicine, Philadelphia, PA; private practice, Falls Church, VA.

The purpose of this chapter is to delineate the history, diagnosis, rationale, techniques, methods, outcomes, and possible complica-tions utilized in the predictable treatment of nonvital discolored teeth Emphasis is placed on the diagnosis and etiology of discol-oration, which has significant bearing on the predictability of treatment outcomes that can be expected.This is particularly valid when treating stump shades, which require foundation restorations (see Chapter 6) and subsequent full-coverage restorations

A HISTORY OF NONVITAL BLEACHING

The history of internal bleaching can be traced back more than a century Chloride was first used inside the pulp chamber as an internal bleaching agent, but the results were not efficacious In 1958, Pearson was impressed by the positive bleaching effect of 30%

hydrogen peroxide on the external surface of teeth.1The solution was used internally on a pulpless tooth for 3 days with great success In 1961, Spasser mixed sodium perborate and water as an internal bleaching medium and placed the mixture into the tooth, employing interval appointments.2Nutting and Poe furthered the work of Spasser by replacing water with 30% hydrogen peroxide

to maximize the bleaching effect.3The sodium perborate/30% hydrogen peroxide paste was sealed within the pulp chamber for durations of up to 7 days This procedure was eventually termed the “walking bleach” technique With small variations and modifi-cations from the original protocol, the methodology for current internal bleaching techniques has remained intact

B ETIOLOGY OF DISCOLORATION

Discolorations may be categorized as either extrinsic or intrinsic Extrinsic discoloration is attributed to food substances such as tobacco, coffee, and tea Lack of adequate oral hygiene can be a contributory factor These stains can be removed predictably by professional prophylaxis and, in severe situations, in combination with extrinsic bleaching techniques An intrinsic factor, such as fluorosis, may cause surface defects that can promote the formation of extrinsic stains

The etiology of intrinsic discoloration covers a broad range and may present significant variations.The basic factors initiating intrinsic discolorations include genetic, systemic, medication-related, pulp-related, and dental material-related:

Medication-related—Tetracycline (Figure 7-1);

Fluorosis(Figures 7-2 and 7-3);

Pulp-related—Root canal obliteration due to aging, pulp necrosis, and/or hyperemia due to trauma (Figure 7-4); and

Dental material-related—Restorative or endodontic materials (Figures 7-5 and 7-6).

Figure 7-1 Figure 7-2 Figure 7-3

Figure 7-4 Figure 7-5 Figure 7-6

Figure 7-1 Clinical depiction of tetracycline staining

Figure 7-2 Intrinsic discoloration can also be attributed to the presence of opaque fluorosis

Figure 7-3 Illustration of brownish fluorosis on the anterior dentition

Figure 7-4 Clinical image shows grayish discoloration due to pulpal necrosis from trauma

Figure 7-5 Occlusal view of dis-coloration on surrounding tooth structure due to corrosion from amalgam filling

Figure 7-6 Illustration shows metallic discoloration from palatal amalgam filling on maxillary right lateral incisor

Aesthetic Management of Nonvital Discolored Teeth With Internal Bleaching} {

B1 Pulp-Related Discoloration

Most of the intrinsic discoloration encountered in everyday practice is caused by the breakdown of blood products of the pulp tissue, due to trauma or a traumatic incident (Figure 7-7).This type of discoloration (ie, blood degradation) occurs during hemolysis, when iron is released from hemin, hemosiderin, hematin, and hematoidin Through the addition of the bacterial product hydrogen sulfide, iron is converted to ferric sulfide, resulting in the discoloration of the tooth.The dental enamel tends to change color either

to orange, brown, or dark gray in color (Figure 7-8) In addition to blood product breakdown, the degradation of necrotic pulp tissue may also cause discoloration Fortunately, most discolorations resulting from these factors can be predictably corrected by utilizing the present internal bleaching techniques (Figures 7-9 through 7-11)

B2 Dental Materials-Related Discoloration

Stains caused by dental materials are not uncommon (Figure 7-6) Among the discolorants found in dental materials, metallic ions are considered to be the most difficult to bleach.The metallic corrosion products may lead to a dark gray or black appearance that will

be visible through the remaining tooth structure, including the root structure (Figures 7-12 and 7-13) The severity of discoloration and the success of bleaching depend upon the amount of metallic ions penetrating the dentinal tubules Although the severity cannot

be determined prior to the treatment, bleaching should be attempted first It may be necessary to remove the stained tooth structure mechanically and follow with the restoration using a tooth-colored material to achieve an improved aesthetic result

Discoloration caused by other root canal filling materials has also been reported (Figure 7-14).4-6 Different materials used inside the pulp chamber will penetrate the dentinal tubules and cause varying color changes in the tooth.This type of discoloration is not pre-dictably corrected with internal bleaching (Figures 7-15 and 7-16).

Figure 7-7 Facial view of a typical dental trauma with very mild discoloration

Figure 7-8 Several years following dental trauma, more noticeable orange discoloration is evident

Figure 7-7 Figure 7-8

B3 Medication-Related Discoloration

Tetracycline was introduced in the middle of the twentieth century and was used widely for the relief of nausea associated with morning sickness In 1963, the Food and Drug Administration (FDA) issued a warning against the use of tetracycline as an

antibiot-ic for young children and pregnant women due to irreversible dental staining Tetracycline affects the teeth during the formation period, ranging from the embryo in the second trimester of pregnancy to the eighth year of the child’s life.The tetracycline molecule affects the dentin by carrying the hydroxyapatite crystal that causes a yellowish-gray color (Figure 7-1) The severity of the tetracy-cline stains may vary When the stain is not concentrated or localized as a band, it usually responds well to bleaching (Figure 7-17) When the band of the discoloration becomes noticeably darker, the bleaching technique has limited value In such cases, a combi-nation of bleaching and veneering techniques might be the recommended course of treatment

B4 Fluorosis

Fluorosis is the result of an excessive intake of fluoride during enamel formation and calcification, usually the third month of gestation through the eighth year after birth When high concentrations of fluoride are absorbed by the body, the metabolic function of the ameloblasts is altered, which leads to defective matrix formation and hypocalcification (Figure 7-2) This type of discoloration can affect the primary and the permanent dentition Histologically, a hypomineralized porous subsurface, covered by a well-mineralized surface enamel layer, is observed Based on the severity, fluorosis has a variety of prognoses following bleaching When the appear-ance of pigmentation is limited to a brownish appearappear-ance only (Figure 7-3), fluorosis responds to bleaching well Once a severe opaque discoloration or pitted surface defects can be observed (Figure 7-18), a bonding technique is usually necessary in addition

to bleaching to achieve aesthetic success

In summary, internal bleaching is not indicated in all clinical situations to correct all forms of discoloration.The majority of discolored anterior teeth are nonvital, however, and the discoloration is caused by traumatic injury The efficacy of internal nonvital bleaching treatment for a predictable aesthetic outcome in these clinical scenarios is high In dental materials-related discolorations, however, nonvital bleaching has limited and unpredictable results

Figure 7-9 Image demonstrates the presence of a brownish discoloration from trauma after teeth have been prepared for all-ceramic restorations

Figure 7-10 In order to prevent the discoloration from showing through the all-ceramic restoration, internal bleaching is performed

Figure 7-11 After bleaching, the teeth match adjacent teeth in color and translucency and provide a more pre-dictable outcome for the anticipated all-ceramic restoration

Figure 7-12 Note the black appear-ance on cervical root surface of a maxillary left central incisor with porcelain-fused-to-metal restoration and recessive gingival tissue

Figure 7-13 A black discoloration, attributed to the corrosion of the metal dowel, is present after the crown is removed

Figure 7-9 Figure 7-10 Figure 7-11

Figure 7-12 Figure 7-13

Aesthetic Management of Nonvital Discolored Teeth With Internal Bleaching} {

C INDICATIONS AND CONTRAINDICATIONS FOR BLEACHING

Since not all the dental discolorations can be bleached effectively, it is important to recognize the etiology of discoloration and to communicate the information to the patient, along with the available treatment options, alternative treatment, and their potential outcomes Nonvital bleaching is indicated when the discoloration is due to pulpal necrosis, pulpal hemorrhage, endodontic filling materials, or mild to moderate tetracycline staining The most important prerequisite for internal bleaching of a tooth is the quality

of the endodontic therapy Nonvital bleaching procedure should be avoided when the root canal treatment is inadequate Superficial enamel stains can be removed by pumice polishing, microabrasion, or an external bleaching technique rather than internal bleaching

If the discoloration is caused by metallic salt, or there is a lack of sound tooth structure caused by extensive restorations, fractures, hypoplastic or severely undermined enamel, a full-coverage restoration or veneer is the recommended treatment

D INTERNAL BLEACHING AGENTS

D1 Hydrogen Peroxide (30% to 35%)

Thirty to 35% hydrogen peroxide is the most commonly used solution in nonvital bleaching procedures, and it can be activated by heat or light application When such solutions are activated, they decompose into perhydroxyl ions and active oxygen, which break the double bond of the chromophore structure of the organic molecules into simpler and lighter colored molecules.7 Because 30%

to 35% hydrogen peroxide is relatively unstable, storage in a dark container and cool environment is mandatory.These solutions lose approximately 50% of their oxidizing strength within a 6-month period In order to achieve the best performance, a fresh amount should be prepared for each subsequent bleaching

D2 Sodium Perborate

Sodium perborate is another commonly used agent for nonvital bleaching It is manufactured in powder form and is alkaline in nature

Based upon the water content, various types of preparations are available Sodium perborate should be kept dry When it is mixed with acid, water, or warm air, it decomposes into sodium metaborate, hydrogen peroxide, and active oxygen Hydrogen peroxide continues to break down into perhydroxyl ions If sodium perborate is mixed with hydrogen peroxide, more perhydroxyl ions are released due to its alkalinity, thereby increasing the effectiveness of the bleaching mixture.8Several studies have shown that hydrogen peroxide releases more calcium, lowers the calcium to phosphate ratio,9and decreases the microhardness of the tooth structure.10

It also damages the dental hard tissue surfaces.11 The application of sodium perborate, however, minimizes the negative effect of hydrogen peroxide on the tooth structure.8-11

Figure 7-14 Illustration shows dis-coloration caused by gutta-percha

Figure 7-15 Image of discoloration caused by the corrosion of the metal dowel Internal bleaching is

to be attempted to resolve the discoloration

Figure 7-16 After few bleaching attempts, the tooth structure remains dark in shade

Figure 7-17 Facial view demon-strates result of bleaching performed on teeth with less-concentrated tetracycline staining

Figure 7-18 Teeth that exhibit fluorosis with pitted surface are not good candidates for bleaching

Figure 7-14 Figure 7-15 Figure 7-16

Figure 7-17 Figure 7-18

E INTERNAL BLEACHING PROCEDURE

E1 Examination and Diagnosis

A thorough examination and inspection for caries, existing restorations, the integrity of the tooth structure and the health of sur-rounding gingival tissue should be made prior to bleaching Any external stains or existing restorations should be removed The etiology of the discoloration should be determined Root canal obturation should be examined radiographically to ascertain that it

is filled to the apex The coronal seal should be complete to minimize the potential of leakage Probing should also be performed

on the labial, mesial, palatal, and distal aspects of the tooth to evaluate the relationship between the tooth and its surrounding epithe-lial attachment and to establish baselines (Figure 7-19).Finally, treatment procedures, the expected outcome, and the potential for subsequent complications should be explained to the patient

E2 Precautions

Bleaching agents are mostly caustic, and the procedure requires that patients are provided with protective eyewear and a plastic drape.The oral environment must be protected by use of a rubber dam, ligature, and oral protective ointment.The epithelial attach-ment should be reexamined after bleaching Such examination is necessary, since the bleaching agents are caustic, and an accidental leakage may cause the breakdown of the epithelial attachment

E3 Shade Documentation

While matching the color of the bleached tooth to that of the adjacent dentition can present a challenge, it is essential to establish

a color baseline prior to initiating the bleaching procedure.The tooth color is compared with the matching shade guide, and a pho-tograph is then taken to maintain a record During each recall visit, the same procedure should be consistently repeated to monitor the improvement

E4.Tooth Isolation

The use of a rubber dam is essential It should be placed on the teeth to be bleached with waxed dental floss, and the floss should

be tightened around the cervical portion of the tooth with a knot Prior to placing the rubber dam, an oral protective ointment should be swabbed around each tooth underneath the dam and on the surrounding gingival tissue for additional protection

Figure 7-20 and 7-21 Figure 7-19

Figure 7-22 Figure 7-23

Figure 7-19 Illustration shows probing

on the distal, labial, and mesial aspects of the tooth to evaluate the relationship between the tooth and its surrounding epithelial attachment and to establish the base lines

Figures 7-20 and 7-21.Tooth access should be conservative, but no pulp horns or undercuts should be left behind

Figure 7-22 Image demonstrates the use of an ultrasonic tip #2 to remove discolored dentin

Figure 7-23 Illustration shows the use

of heated instruments to remove gutta-percha from the canal

E5 Access Cavity Preparation

All restorative material should be removed from the access cavity, using a high-speed handpiece with copious irrigation The access should be as conservative as possible, but care should be taken not to leave any pulp horns or undercuts behind (Figures 7-20 and 7-21) Any residual pulp tissue or dental materials left in the chamber might cause further discoloration once the bleaching is complete A slow-speed handpiece may be used to remove the remaining debris on the dentinal wall Specially fabricated ultrasonic tips, attached to a Piezo-ultrasonic unit, can be valuable instruments for carefully ablating the discolored dentin and removing it in small increments (Figure 7-22)

E6 Space for Barrier

Gutta-percha should be removed from the canal orifice to a level of 2 mm below the corresponding epithelial attachment.This can

be done by using a heated endodontic instrument and heated Glicks instrument.The use of heated endodontic instruments is more favorable than that of rotary instruments, because they remove gutta-percha more efficiently without damaging any tooth structure

(Figure 7-23).

E7 Barrier Placement

Once the space for a barrier is established, it must be sealed with specific materials.The purpose of placing a barrier is to block the potential leakage of bleaching agents through dentinal tubules to the epithelial attachment This step is important for prevention of cervical resorption The outline of the barrier should follow the corresponding probing of the epithelial attachment (Figure 7-24).

Cavit (3M Espe, St Paul, MN) has been reported to provide better seal as a barrier than either intermediate restorative material or temporary endodontic restorative material.12,13 The thickness of the barrier is important as well; in order to prevent leakage, the barrier should be placed 1 mm incisal to the level of the epithelial attachment and extend at least 2 mm apically

Aesthetic Management of Nonvital Discolored Teeth With Internal Bleaching} {

Figure 7-25 Figure 7-26 Figure 7-24

Figure 7-24.The outline of the barrier should follow the corresponding probing

of the epithelial attachment

Figures 7-25 and 7-26 A cotton pellet saturated with 30% to 35% hydrogen peroxide is placed in the chamber, where heat causes the bubbling effect

E8 Application of Bleaching Agents E8a.The Thermocatalytic Technique

The thermocatalytic technique uses heat to activate 30% to 35% hydrogen peroxide in the chamber A cotton pellet saturated with the hydrogen peroxide is placed in the chamber, and the heat causes a bubbling effect (Figures 7-25 and 7-26) The heat application can be as long as 5 minutes, providing the cotton is kept saturated at all times The temperature should be maintained at 73°C (165°F) to avoid causing any discomfort to the patient

E8b.The Light Technique

The light technique can also be used to activate hydrogen peroxide in the chamber As with the thermocatalytic technique, a cotton pellet saturated with superoxide is placed in the chamber, and a bright light source is positioned directly above the crown, nearly touching the buccal surface, for 3 to 5 minutes The light source may be a regular desk lamp light; the light of the microscope at full power is also an effective light source

E8c.The “Walking Bleach” Technique

In the “walking bleach” technique, the mixture of sodium perborate and 30% to 35% hydrogen peroxide is placed in the chamber and sealed for 7 days (Figure 7-27) The sodium perborate and 30% to 35% hydrogen peroxide are mixed in a ratio of 2 g perborate/ml of 30% to 35% hydrogen peroxide, which results in a thick, white paste After placing an adequate amount of the mixing paste into the chamber, a temporary filling material is used as a sealer Patients should be informed that the same procedure may have to be repeated, if necessary, and that another recall visit is required in 7 days

E9 After Bleaching the Restoration

After the desired result is achieved, which may take more than one visit, the remaining bleaching agent should be removed thor-oughly from the chamber If composite resin is the material of choice for the final restoration, the access cavity should be filled com-pletely with a noneugenol temporary base material A loss of bond strength has been found if glass ionomer or composite resin is bonded to dentin or enamel immediately following bleaching If increased microleakage may be observed around composite restora-tions, it could be due to the residual bleaching agent within the dentinal tubules and enamel It is therefore suggested that final restoration be delayed for at least one week following bleaching

Figure 7-27.The mixture of sodium perborate and 30%

to 35% hydrogen peroxide is placed and sealed in the chamber for seven days as the “walking bleach”

technique

Figure 7-27