Written by William C. Strupp, Jr, DDS, and Daniel J. Melker, DDS, Thursday, 01 May 2003 00:00
Each dentist approaches treatment planning of aesthetic restorative cases in a unique way. Treatment plans are the product of an individual dentist’s knowledge, skill, care, and judgment based on his or her experience, circumstances, and objectives. The treatment plans that result from this combination of elements can vary on the same case from 28 units of crown and bridge to no treatment at all. Dissimilarities in treatment planning should not be judged right or wrong. Dissimilarities exist because all dentists are different. However, if any treatment plan disrespects basic biological principles, it must be considered unacceptable.
Although it is difficult to argue with the importance of evidence-based dentistry in the proper development of one’s treatment planning, many dentists frequently treatment plan cases guided solely by experience and result-based concepts. To achieve optimum health for patients, the best treatment plans are conceived when both evidence-based and result-based treatment, guided by experience, are used in concert with one another.
This article presents a case that incorporates both of these concepts; ie, solid science as well as clinical experience to achieve an excellent result from the viewpoints of a periodontist and a restorative dentist who have worked together for more than 25 years and have comprehensively treated more than 3,000 cases with comparable results.
Diagnosis and Treatment Planning
A 32-year-old white female presented to the office with the following request: “I want new crowns on my 2 front teeth.” This patient perceived her treatment request to be simple. However, after the initial examination, several complexities became apparent.
|Figures 1 through 3. This patient presented with short, full-coverage, metal-ceramic restorations on the maxillary central incisors. Initial examination revealed many complex clinical challenges.|
Short, full-coverage, metal-ceramic restorations were present on the maxillary central incisors (Figures 1 through 3). Their short appearance was due in part to the centrals lacking incisal length. The central and lateral incisors were about the same length. In addition, the gingival line of the centrals was coronal to that of the laterals. The combination of too much gingiva and too little incisal length made the crowns on the centrals appear squatty.
Tissue infection was present. Bleeding occurred upon probing, especially around the restored teeth. However, inflammation was also present facially around tooth No. 10. Bleeding was more severe around tooth No. 8. It was concluded that the etiology of the tissue infection around tooth No. 8 was microbial growth under the crown that could not be controlled by the patient. The inflamed tissue was tender to brush, thus plaque accumulation was greater around the restorations on the central incisors. The papillae between the incisors were swollen and engorged with blood. Infected raw and bleeding tissue is common around restorations with subgingival margins.1-4
When the patient smiled, her short upper lip revealed the gingival line on teeth Nos. 3 through 10. The gingival line of teeth Nos. 11 through 15 was covered by the lip. The occlusal function coupled with anterior crowding prevented complete active eruption of teeth Nos. 11 and 12. The incisal tip of tooth No. 6 was worn flat, while there was minimal wear on the incisal tip of tooth No. 11. The incisal tip of tooth No. 11 was apically positioned relative to the incisal tip of tooth No. 6 by 2.5 mm.
The restorations on the patient’s central incisors were placed during her teenage years, secondary to trauma. Altered passive eruption was present on teeth Nos. 8 and 9, which is not unusual when restorations are placed before passive eruption is complete.5-8 If a crown margin is placed subgingivally before biologic maturity, the process of passive eruption is frequently interrupted. This type of altered passive eruption is not caused by restorations with supragingival margins. However, many patients with no restorations routinely present with altered passive eruption, accounting for many of the surgical procedures necessary to create excellent gingival aesthetics.
The patient’s tissue infection around the central incisors was aggravated by a frenum pull. The width of the frenum was unusually wide. Periodontists with an appreciation and understanding of gingival aesthetics can perform a very simple noninvasive surgical procedure to correct many frenum problems, without causing papillae loss.
The asymmetry of the patient’s gingival line was caused by the altered passive eruption and the incisally inferior tooth positions of teeth Nos. 11 and 12. These conditions would have required orthodontics followed by periodontal surgery to be completely corrected. This patient was not a candidate for full-band orthodontics.
Occlusal hyperfunction/parafunction with maxillary and mandibular incisal edge wear and fracturing had occurred on the incisors. Tooth No. 10 was worn more than tooth No. 7, creating the appearance of a shorter tooth. Incisal parafunction with wear is not extraordinary and is particularly common in patients who snore and have breathing abnormalities. Many breathing problems are secondary to allergies. The wear is caused by protrusive posturing of the mandible and incisal edge bracing that occur when the patient clenches or bruxes. Such parafunctional habit patterns, if severe, require the use of a night guard to prevent occlusal damage.
Upon exploration, open margins on the central incisor restorations were readily visible. Impressions are frequently missed when margins are placed subgingivally. Imperfect impressions result in imperfect dies that can compromise the laboratory technician’s ability to perfect the final restorations. When these metal-ceramic restorations were placed by the patient’s childhood dentist, they were essentially the only aesthetic choice available, thus necessitating subgingival margins. Nonetheless, the subgingival margin placement was also responsible for much of the subsequent pathology that had occurred.
Caries was evident along the root surface and apical to the margins of the crowns on teeth Nos. 8 and 9. Caries is the primary cause of failure in crown and bridge dentistry.9-11 If restorations are cemented into a pool of blood or other oral fluids when acid-soluble cements are used, cement dissolution, microbial growth, and pathology are inevitable. The process of cement dissolution and microbial growth under crowns that causes this pathology is referred to as “cement sepsis.” Caries that occurs under restorations, along margins, and on root surfaces, necessitating the replacement of the restorations, is primarily the result of cement sepsis. Tissue infection, typified by a red cuff of tissue inflammation around restorations, is also a result of cement sepsis. Restorations with subgingival margins frequently display such signs of infection.
Tooth No. 8 was positioned lingually to tooth No. 9, which caused the facial tissue on tooth No. 8 to proliferate coronally relative to the tissue on tooth No. 9. Gingival line asymmetry is frequently caused by crowded teeth, particularly where the lingually positioned teeth have excessive tissue. Bone on the facial surface of these lingually positioned teeth is thicker and supports more tissue, thus creating a shorter tooth with gingival line asymmetry. After surgery, tissue often shrinks facially on lingually positioned teeth, even though the facial bone levels remain the same. This case experienced this type of postsurgical complication.
Owing to the thickness of the marginal contour on the proximal surfaces of the metal-ceramic restorations, the complication of root proximity between teeth Nos. 7 and 8 and teeth Nos. 9 and 10 could not be adequately evaluated. For the proper assessment of this potential problem, it would be necessary to remove the existing restorations. Many problems that can compromise a case are camouflaged by the old dentistry and are not apparent until its removal.
The porcelain appeared opaque, especially along the gingival aspect of the restorations. The primary reason to choose an all-ceramic restoration over one that is metal-ceramic is to avoid the use of the opaque porcelain that is required to mask a metal substrate in the thin gingival aspect of the restoration. Opaque restorative materials create a visually blatant transition from tooth structure to restorative material that compromises aesthetics and creates the umbrella effect.12 One can completely avoid these aesthetic complications by marginating supragingivally with all-ceramic restorations and using translucent porcelain along the gingival aspect of the restoration.
Excessive reduction in the form of shoulder preparations coupled with subgingival margin placement is required to obtain aesthetic results in the gingival one third of metal-ceramic restorations. The science is unequivocal; if subgingival margins are placed, then periodontal pathology occurs.13,14 The clinical evidence is equally compelling; a significant number of metal-ceramic restorations observed clinically have either tissue infections with red bleeding gums, or opaque porcelain and/or oxidized metal that is visible at the gingival aspect of the crown. If the margins are buried deep enough into the tissue in order to conceal them and achieve a better aesthetic result, the tissue often becomes inflamed. In addition, infection proliferates as a result of poor-fitting restorations or compromised cement. No matter how nicely one polishes a bamboo shoot before it is shoved into the biology of the fingernail bed, a negative tissue reaction is certain to occur. The same is true of gingival tissue. Invading the biology of the body invariably produces a similar result, regardless of the location of the point of invasion. Furthermore, the destruction of tooth structure necessitated by the use of shoulder margin designed to accommodate these restorations frequently results in pulp death. According to published reports, many teeth experience pulp death within 5 years of crown placement.15 Reports derived from insurance statistics show that 50% of all crowns require endodontics within 5 years of placement.16 Red gums and dead pulps are clearly not indications of healthy dentition or of good health in general. In fact, they have been implicated as an etiologic factor in heart attacks and stroke.17-22
Radiographic evaluation of the patient revealed a rather large and lengthy post in tooth No. 8. The endodontic fill appeared adequate. Bone levels were acceptable. Caries could not be identified radiographically.23
Because of the existing tissue complications, the patient was referred to a periodontist for correction of the tissue infection and gingival line problems. The periodontist suggested surgical intervention to correct the altered passive eruption, frenum pull, and tissue infection conditions. He requested that the old restorations be removed and the caries controlled, followed by core buildups so a determination could be made of the apical extent of the caries and other pathology that could compromise the biologic width. Surgical provisional restorations were required on teeth Nos. 8 and 9 to permit the tissue to heal. At the time of surgery, the provisionals would be removed to facilitate complete access to the roots for reshaping.24-26 Periodontal surgery would be greatly compromised without the use of surgical provisionals because of the inability of the surgeon to visualize and treat the existing pathology. In addition, the surgical procedure can be managed more easily and with more precision when the tissue is pink, epithelialized, and free from problems caused by cement sepsis. Inflamed and infected tissue, which is much more difficult to manage surgically, heals nicely with provisionals that are well made if they are placed with an antimicrobial cement at least 2 weeks or more before surgery.
The periodontal treatment plan was to correct the altered passive eruption surgically within the proper framework of the biologic width; ie, to create an appropriate crown length of 11 mm. In addition, sufficient space would be provided for the soft tissue biology coronal to the bone so that it would not be compromised by the restorations.27-30 If one were to remove soft tissue without proper osseous management, complete periodontal failure would result.31-33
|Figures 4 and 5. The existing restorations on teeth Nos. 8 and 9 are removed atraumatically.|
The patient agreed to the treatment plan presented. An appointment was scheduled to place surgical provisionals. At this appointment, the old restorations were cut off atraumatically (Figures 4 and 5). Because the teeth and periodontal tissues can be severely damaged by “pounding” off old restorations, a diamond was used to cut through the porcelain until metal was exposed. Then a No. 330 carbide bur was used to cut through to the tooth. Care was taken not to cut too deeply into the tooth structure, nor to cut into any tooth structure in the subgingival zone. Large amounts of water were used to avoid overheating the tooth and to keep the instruments cutting efficiently. The old restorations were easily removed by spreading the slit open with a hand instrument.
After removal of the restorations, it became apparent that gross cement sepsis had occurred, especially on tooth No. 8. Excessive reduction and a gray substrate color were also observed on tooth No. 8. In addition, the stainless steel post was loose, which was partly responsible for the gray substrate discoloration. This kind of discoloration occurs through a bio-metallic process of microbial metabolism with the stainless steel. This bio-metallic process of metal degradation also occurs with amalgam alloy. For this reason, it is important not to use amalgam in a tooth where color is an issue for aesthetic purposes. In this instance, the patient’s tooth had been unnecessarily compromised by the placement of the post. At the time the restorations were initially done, an adequate amount of tooth structure existed for a definitive restoration, without the need to place a post. Needless to say, there are a myriad of complications that can occur secondary to post placement.
Caries was present in the post space of tooth No. 8 after the post was removed. Moreover, after removing the post and the caries from tooth No. 8, little tooth structure remained above the tissue. Similarly, caries on tooth No. 9 coupled with an aggressive shoulder preparation had compromised the volume of residual tooth structure. However, enough structure was left to predictably restore the tooth using a core buildup.
|Figure 6. A titanium alloy post is positioned within a mass of Core Paste using a clear, vacuum adapted preparation guide.|
A 0.50 titanium alloy post (Para Post XP, Coltene Whaledent) was bonded into the re-prepared post space of tooth No. 8 with Panavia 21 TC (Kuraray). Enamel Shade Core Paste (Den-Mat) was used to displace as much of the Panavia 21 as possible.34 The post was positioned within the mass of Core Paste using a clear, vacuum adapted preparation guide so it would be enveloped by the Core Paste and not be visible facially (Figure 6). Contrary to popular belief, titanium alloy posts do not compromise the substrate color, provided Core Paste covers the post. In addition, titanium alloy is not as susceptible to the microbial process of biometallic degradation that affects stainless steel. Fiber and ceramic posts do not significantly improve the ultimate tensile strength of Core Paste when significant occlusal function is a factor. The tooth is weakened more than strengthened with the placement of a fiber or ceramic post.
Because all-ceramic restorations were planned, the use of Enamel Shade Core Paste was mandated. Any other shade of resin composite core material would negatively impact the substrate color, thus increasing the amount of opacification required in the all-porcelain restorations. The more opaque one makes these restorations, the less they look like natural teeth and the more they look like metal-ceramic restorations.
|Figure 7. Teeth Nos. 8 and 9 are minimally prepared using thin chamfer margins.||Figure 8. The provisionals are cemented with polycarboxylate cement, which helps control microbial growth.|
Minimally invasive preparation designs using thin chamfer margins were made (Figure 7). In doing so, a substantial amount of tooth structure/Core Paste remained to enhance the strength of the residual tooth. It is very common to see grossly overcut teeth under full crowns with shoulder margins. Core buildups are routinely required to predictably manage teeth previously treated in such a manner. Provisional restorations were made using an indirect technique. The provisionals were then cemented with polycarboxylate cement, which helps to control the microbial growth that can occur under them (Figure 8). Facilitating this antimicrobial environment allows the infected tissue to heal before surgery. In addition, it is desirable to avoid using soluble eugenol or non-eugenol provisional cements because they negatively impact pulp and tissue health as a result of their rapid dissolution and subsequent replacement with microbes. An increased incidence of pulp and tissue problems is caused by the cement sepsis that occurs when soluble provisional cements are used with surgical provisionals, even though they are only in place for 2 weeks or less. The tissue around teeth with well-fitting provisionals placed with polycarboxylate cement heals almost completely within 2 weeks. The healthy tissue is easier to manage and does not complicate tissue positioning at surgery.
It frequently becomes necessary to cut off a raw, bleeding, and infected piece of “hamburger meat” tissue rather than simply apically repositioning it at the time of surgery. Removing this tissue reduces the amount of attached tissue that could protect against recession.35 In addition to the excellent healing the tissue experiences as a result of well-fitting provisionals placed with polycarboxylate cements, pulp health is greatly enhanced. In fact, many restored teeth with sensitivity to hot, cold, and biting pressure become symptom-free after provisional placement. On the other hand, when provisionals are not properly used, many of these teeth require endodontic treatment that otherwise could have been avoided.
|Figure 9. At the initial periodontal evaluation, the length of the central incisors is measured with a probe to establish crown length.|
The patient was scheduled for an appointment with the periodontist to perform surgery 2 weeks after the placement of the surgical provisionals. At the initial periodontal evaluation, the length of the central incisors was measured with a probe to establish how much crown length existed (Figure 9). Tooth No. 8 measured 8.5 mm and tooth No. 9 measured 9 mm. The surgical plan encompassed lengthening the central incisors to 11 mm for a more aesthetic length-to-width ratio and better gingival line symmetry. Surgery was also planned to completely eliminate the periodontal pathology as well as the cause of the pathology.
|Figure 10. On the day of surgery, the crown length with provisionals in place is measured.|
On the day of surgery, the crown length with the provisionals in place was measured (Figure 10). Any alteration in the incisal length of the provisionals was recorded and factored into the surgical procedure. The tissue was probed to see if it had healed from the placement of the surgical provisionals. Minimal bleeding occurred because good plaque control and an excellent healing response to the surgical provisionals had been attained.
|Figure 11. The provisionals are removed and a full-thickness/split-thickness flap is performed.|
The provisionals were removed and a full-thickness/split-thickness flap was undertaken using a No. 15 blade (Figure 11). A full-thickness flap is created to the mucogingival junction with crown-lengthening procedures requiring osseous surgery. A split-thickness flap is made beyond that point. A split-thickness flap leaves periosteum on the bone and allows the flap to be sutured into a precise position. When bone removal is not necessary, only a split-thickness flap is undertaken.
The bone was in a coronal position on teeth Nos. 8 and 9 in relationship to teeth Nos. 7 and 10. It was necessary to remove the bone from these teeth in order to achieve a proper gingival line with tissue health. When the excessive tissue is lasered away without proper attention paid to the biologic width, the “red ring around the crowns” syndrome results, which is frequently observed postoperatively in cases where only gingivectomy is performed.36
|Figure 12. The provisionals are replaced after flap surgery, and an exact measurement is made with a probe from the incisal edge to the bony crest for each central incisor.|
The provisionals were replaced after the flap was made so an exact measurement could be made with a probe from the incisal edge to the bony crest on each central (Figure 12). The measurement of 12.5 mm indicated the necessity for the removal of 1.5 mm of bone to achieve the treatment-planned aesthetic length of the central incisor restorations (11 mm) and space for the biologic width (3 mm) to exist in harmony. (Figure 12 photo was taken before the osteotomy was performed.)
|Figure 13. After osseous surgery, the provisionals are placed and a probe measurement is made from the incisal edge to the bone for each central incisor.|
After osseous surgery, the provisionals were placed and measured with a probe; the measurement was 14 mm from incisal edge to bone (Figure 13). The bone was removed on the facial aspect of teeth Nos. 8 and 9 with a No. 8 round carbide bur using copious water and left in an apical position relative to teeth Nos. 7 and 10. In addition, the facial root surfaces were reshaped beginning with a coarse F-82 diamond bur (Pollard), followed by a superfine F-82 diamond bur, and finished with an ultrafine F-82 diamond bur. It was determined that root proximity was not a problem. However, if it had been a problem, it could have been corrected easily by root reshaping to provide an adequate space for tissue health. The ultrafine diamond bur, which has a grit size of 40 µm, leaves the reshaped root surface exceedingly smooth. The original margin placed by the previous dentist and any rough root surfaces or grooves were completely smoothed.
Such root reshaping often enables the restorative dentist to marginate on extremely smooth root surfaces several millimeters coronal to the position of the original margin of a crown that may have been “buried to the bone.” Conventional surgery to recreate a new biologic width that is harmonious with margins of restorations buried to the bone in a nonaltered passive eruption case would require removal of 3 mm of bone beyond the ideal crown length. Such aggressive osseous surgery not only compromises the long-term periodontal support, but is also likely to destroy the aesthetics of the case by creating the infamous postperiodontal surgery nightmare of long teeth and “black holes.” In addition, excessive bone removal can cause mobility and migration. If the restorative dentist is handicapped by the subgingival position of the original margin of a previous restoration, then root reshaping is mandated to achieve an uncompromised clinical result.
Because passive eruption was altered by the placement of the crowns in this case, the removal of 1.5 mm of bone was not considered aggressive osseous surgery. Its purpose was merely to remove the bone that would have resorbed naturally had complete passive eruption occurred. Removing the least amount of bone possible to achieve an aesthetic result should be the objective in crown-lengthening procedures.
|Figure 14. After suturing, the clinical crown lengths of teeth Nos. 8 and 9 are measured with a probe.|
A frenectomy was performed and then the tissue was precisely positioned for an 11-mm crown length by suturing to periosteum; 5.0 chromic gut was used to close the wound. No periodontal dressing was used because such dressings harbor microbes and impede wound healing. After suturing, the clinical crown length of teeth Nos. 8 and 9 measured 11 mm with a probe (Figure 14). The surgical provisionals were carefully recemented with polycarboxylate cement. Close attention was paid to ensure cement was not left in the tissue.
The patient was provided 0.2% chlorhexidine (Dial Surgical Scrub) for rinsing, and was instructed not to brush or floss the surgical site for 14 days after surgery. The patient was scheduled for weekly appointments to polish the root surfaces free of plaque and debris. Duraphat (Colgate), a desensitizing agent, was applied after each polishing to minimize the surgically induced sensitivity. After 14 days, the patient was permitted to begin gingerly brushing and flossing, but was cautioned to avoid the interproximal papillae.
|Figure 15. The appearance of the tissue 24 days postsurgery is excellent.|
The appearance of the tissue 24 days postsurgery was excellent (Figure 15). At this time, the provisionals were remade using an indirect technique and cemented with polycarboxylate cement. The margins of the new provisionals were left 1 mm coronal to the tissue.34 The ideal time to remake the provisionals following periodontal surgery is at 4 weeks. The 4-week time frame allows the epithelial surface to heal completely so bleeding does not complicate the remake. The new provisionals cover many dentinal tubules left open from root reshaping. Closing tubules minimizes pulp complications. However, a zone of exposed dentin remains in the 1-mm zone from the margin of the provisional to the tissue level. The tubules were sealed using Super Seal (Phoenix Dental). Super Seal was also used at the time of surgery both before and after wound closure.
All vestiges of cement were carefully removed. Even a tiny piece of residual cement can cause catastrophic tissue damage. The new provisionals were made with flowable resin composite so the patient could bleach her teeth without causing the provisionals to discolor. Provisionals made with methylmethacrylate turn orange in color when exposed to carbamide peroxide. It is preferable to use methylmethacrylate provisionals because they can be flexed when they are removed, if cemented with polycarboxylate cement. In addition, they can be finished to a knife-edge smooth margin, unlike bis-acryl and resin composite provisionals that chip and fracture as they are finished, thus leaving rough areas for plaque to accumulate. Inflexible provisionals made of bis-acryl or resin composite must be sectioned for removal. Consequently, they cannot be recemented if necessary. However, patients do not readily accept orange teeth. For this reason, resin composite was used.
An indirect technique to remake provisionals causes far less damage to the tissue than relining the surgical provisionals directly in the mouth. Direct techniques that expose tender, immature tissue to harsh chemicals can impede the healing process and should therefore be avoided. The margins of the provisionals were left 1 mm supragingivally so the tissue could heal against “virgin” tooth surface. When placed at the tissue level, provisional margins interfere with tissue healing.
It is imperative not to remarginate when the surgical provisionals are removed because the exact location of the tissue—and therefore the final margin position—cannot be determined for an additional 3 months. It is only at this time that the appropriate biologic width for each tooth will be established by the individual biology and anatomy of the patient.
When the surgical provisionals were removed, the polycarboxylate cement used by the periodontist was removed with a sonic scaler, Sonicflex No. 2000N/L (Kavo). The reshaped root surfaces that were now accessible were smoothed with a composite polishing point or cup (Centrix) using copious water. The exceptional smoothness created by such polishing results in exceptionally healthy pink ti
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