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Complications of surgical crown lengthening for a maxillary molar with four roots: A clinical report
Complications of surgical crown lengthening for a maxillary molar with four roots: A clinical report Peter M. Di Fiore, DDS, MSa College of Dentistry, University of Kentucky, Lexington, Ky.
The unique occurrence of 4 rooted maxillary molars with 2 palatal roots has been documented. 1-5 The restoration of an endodontically treated tooth commonly requires the placement of a complete crown. The margin of the complete crown restoration should minimally extend into the gingival crevice because crown margins that encroach on the subcrevicular tissues can induce a progressive inflammatory response.6,7 The dimensions of the structural components of the supraosseous soft tissues were studied by Gargiulo et al,8 who measured the dentoalveolar tissues at 325 tooth surfaces of 287 clinically normal human autopsy specimens. They reported mean dimensions for all age categories of 0.69 mm for sulcular depth (range 0.00 to 5.36 mm), 0.97 mm for junctional epithelium (range 0.08 to 3.72 mm), and 1.07 mm for connective tissue attachment (range 0.00 to 6.52 mm). Although this study revealed gingival attachments with wide variations within a normal range, the mean values reported for each of the tissue components have served as guidelines for desirable dimensions before placement of artificial crowns. As a result, surgical crown lengthening procedures with removal of crestal alveolar bone have become common. Surgical crown lengthening also has been recommended when crown fractures, root caries, resorptions, or perforations extend subcrestally.9-12 A mucoperiosteal flap is reflected and apically positioned after crestal bone is removed to allow adequate connective tissue attachment and epithelial junction that will be commensurate with the restorative crown margin.9-12 Although the apically positioned flap preserves the attached gingiva, the osseous surgical component of this procedure necessitates removal of supporting bone from adjacent teeth to develop a physiologic postsurgical gingival contour.9-12 Orthodontic tooth extrusion has been offered as an alternative to surgical crown lengthening because the gingival attachment apparatus migrates coronally while maintaining crestal bone. Minimal osseous surgery is required after extrusion, and there is little effect on the supporting bone around adjacent teeth.13-16 Orthodontic extrusion also can be
aAssociate
Professor, Department of Endodontics; and Former Director, Dental School, Northwestern University, Chicago, Ill. J Prosthet Dent 1999;82:266-9. 266 THE JOURNAL OF PROSTHETIC DENTISTRY
used successfully on molars as an alternative to osseous surgery for the restorative management of subcrestal root defects.16 When crown lengthening procedures for molar teeth are considered, root structure is a critical factor. The number and locations of furcations should be considered before osseous surgery. In a study of the root structure of a large collection of extracted human teeth, the furcation entrances for molar teeth ranged from 3 to 5 mm apical to the cementoenamel junctions (CEJ).17 These values are well within the limits of dimensional tissue changes that occur with osseous surgery. Surgical crown lengthening procedures that involve the removal of bone around the root trunks of multirooted teeth can adversely compromise periodontal health if furcations become exposed.18 This clinical report presents an endodontically treated 4-rooted maxillary molar with subsequent periodontal and restorative complications associated with crown lengthening surgery.
CLINICAL REPORT A 31-year-old man was referred for endodontic treatment of the maxillary right first molar with a history of an acute exacerbation of a chronic pulpitis. The patient was in good general health with no significant past or present illnesses. Clinical examination revealed a maxillary molar with a disto-occlusal temporary restoration. The gingival attachment apparatus was normal and intact without gingival recession or inflammation. Neither furcation involvement nor periodontal pockets were observed, and tooth mobility was physiologic. Pain and tenderness were absent on percussion and palpation. Radiographic examination did not reveal radiolucencies at the apices or furcations; however, it did reveal the probability of a molar with 4 roots (Fig. 1). An endodontic diagnosis of irreversible pulpitis was made. Endodontic treatment was initiated. After access into the pulpal chamber, 4 separate canal orifices were identified and negotiated in 4 quadralaterally placed separate roots (mesiobuccal, distobuccal, mesiopalatal, and distopalatal). The unique root trunk structure of this molar had 4 entrances to the furcation (buccal, palatal, mesial, and distal). The measurements of the lengths of the 4 distinct roots were taken and adjusted, and the root canals were debrided and prepared. Root canals VOLUME 82 NUMBER 3
DI FIORE
Fig. 1. Preoperative periapical radiograph.
THE JOURNAL OF PROSTHETIC DENTISTRY
Fig. 3. Three-year follow-up recall photograph (buccal view) demonstrates buccal gingival recession.
Fig. 2. Postoperative radiographic (straight view) of gutta percha obturated root canals and silver alloy amalgam postcore structure.
Fig. 4. Three-year follow-up recall photograph (palatal view) demonstrates palatal furcation exposure.
were obturated with gutta percha and sealer with a lateral and vertical condensation technique. Spaces were left in each canal for a coronoradicular reconstruction. A matrix band retainer was placed and distally wedged, the cavity preparation and root canal spaces were coated with cavity varnish, and a silver amalgam alloy postcore reconstruction was placed and adjusted occlusally (Fig. 2). Clinical examination at this time did not reveal any signs or symptoms of gingivitis or periodontitis. The patient was then referred for a complete crown restoration, and the attending dentist referred the patient for crown lengthening. Subsequently, the tooth was treated with surgical crown lengthening and restored. Shortly thereafter, the patient left the country for 3 years. On returning, the patient reported with a chief complaint of painful, sore, tender, and bleeding
gums around the maxillary right first molar. Clinical examination revealed gingival inflammation, gingival recession, furcation exposures, and proximal periodontal pockets (Figs. 3 and 4). This condition was specifically localized to the right first molar area, and there were no other signs or symptoms of periodontal disease anywhere else in the mouth. The patient’s oral hygiene was good, except where the painful gingivae around the maxillary right first molar prevented thorough plaque removal. Radiographic examination revealed interproximal bone rarefaction, cervical root notches, and a furcation radiolucency (Fig. 5). Radiographic examination indicated that the periapical tissues of all 4 roots were normal (Fig. 6). Diagnoses made were acute gingivitis, chronic periodontitis, and cervical root gouges. The patient was referred for periodontal and
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THE JOURNAL OF PROSTHETIC DENTISTRY
DI FIORE
Fig 6. Three-year follow-up recall radiograph (distal angled view) demonstrates normal periapices.
Fig. 5. Three-year follow-up recall bite-wing radiograph demonstrates interproximal bone loss, cervical root notches, and furcation radiolucency.
restorative treatment with a guarded prognosis for retention of this molar.
DISCUSSION This clinical report illustrates the significance of evaluating the indications, contraindications, and possible complications of prerestorative crown lengthening surgery for each patient. On initial clinical examination, there was adequate clinical crown present for a retentive crown preparation, and the distal restorative margin although subgingival appeared clinically within tolerable limits for an adequate epithelial and connective tissue attachment. The periapical radiograph (Fig. 1) did not suggest that surgical crown lengthening was necessary. A bite-wing radiograph, which would better illustrate the level of crestal bone, would likely have shown more supraosseous tooth structure than observed on the periapical radiograph. In this clinical report, the root trunk presented with severe restrictions for osseous surgery with 4 furcal entrances close to the CEJ and gingival crest, increasing the likelihood for surgical exposure. In addition, and most critically, the profound divergence of the roots from the cervical root trunk into the alveolar 268
bony housing made it difficult to remove crestal bone without cervically altering the root trunk surfaces. Although the crown contour and margins were not physiologic (Figs. 3 and 4), and the bite-wing radiograph (Fig. 5) suggested molar malocclusion with occlusal interferences and marginal ridge discrepancies, the most likely cause for the localized periodontitis was the severe root damage. Injudicious removal of alveolar bone with coarse diamond stones or large carbide burs can cause permanent and irreparable damage to the roots. These gouged root surfaces are virtually impossible to restore by the dentist or maintain by the patient, and chronic progressive localized periodontitis is likely to occur. Surgical crown lengthening requires the reflection of mucoperiosteal flaps to expose the cervical root surfaces and crestal alveolar bone. Osseous reduction can be accomplished without altering the surfaces of the roots by first reducing the crestal bone with an end-cutting bur. Small round stones or burs and periodontal hand chisels can then be used to contour and finish the osseous margins. Bone must be differentiated from cementum, and adequate hemostasis, along with copious irrigation, is necessary to ensure visibility. Crown lengthening should not always be considered a routine, prerestorative procedure. An assessment of root trunk and furcation is essential before selecting crown lengthening procedures for multirooted teeth. When crown lengthening is indicated, the cervical root surfaces must not be damaged during the osseous reduction procedure. REFERENCES 1. Diamond M. Dental anatomy including anatomy of the head and neck. 3rd ed. New York: Macmillan; 1952. p. 203-5. 2. Slowey RR. Radiographic aids in the detection of extra root canals. Oral Surg 1974;37:762-72. 3. Thews ME, Kemp WB, Jones CR. Aberrations in palatal root and root canal morphology of two maxillary first molars. J Endod 1979;5:94-6.
VOLUME 82 NUMBER 3
DI FIORE
THE JOURNAL OF PROSTHETIC DENTISTRY
4. Stone LH, Stroner WF. Maxillary molars demonstrating more than one palatal root canal. Oral Surg Oral Med Oral Pathol 1981;51:649-52. 5. Christie WH, Peikoff MD, Fogel HM. Maxillary molars with two palatal roots: a retrospective clinical study. J Endod 1991;17:80-4. 6. Newcomb GM. The relationship between the location of subgingival crown margins and gingival inflammation. J Periodontol 1974;45:151-4. 7. Maynard JG Jr, Wilson RD. Physiologic dimensions of the periodontium significant to the restorative dentist. J Periodontol 1971;50:170-4. 8. Gargiulo AW, Wentz FM, Orban B. Dimensions and relations of the dentogingival junction in humans. J Periodontol 1961;32:261-7. 9. Palomo F, Kopczyk RA. Rationale and methods for crown lengthening. J Am Dent Assoc 1978;96:257-60. 10. Lovdahl PE, Gutmann JL. Periodontal and restorative considerations prior to endodontic therapy. Gen Dent 1980;28:38-45. 11. Fugazzotto PA. Periodontal restorative interrelationships: the isolated restoration. J Am Dent Assoc 1985;110:915-7. 12. Davis JW, Fry HR, Krill DB, Rostock M. Periodontal surgery as an adjunct to endodontics, orthodontics, and restorative dentistry. J Am Dent Assoc 1987;115:271-5. 13. Ross S, Dorfman HS, Palcanis KG. Orthodontic extrusion: a multidisciplinary treatment approach. J Am Dent Assoc 1981;102:189-91. 14. Biggerstaff RH, Sinks JH, Carazola JL. Orthodontic extrusion and biologic width realignment procedures: methods for reclaiming nonrestorable teeth. J Am Dent Assoc 1986;112:345-8.
Noteworthy Abstracts of the Current Literature
15. Oesterle LJ, Wood LW. Raising the root. A look at orthodontic extrusion. J Am Dent Assoc 1991;122:193-8. 16. Lythgoe JR, Torabinejad M, Simon JH. Extrusion techniques for the general dentist. Gen Dent 1980;28:42-9. 17. Gher ME, Vernino AR. Root morphology—clinical significance in pathogenesis and treatment of periodontal disease. J Am Dent Assoc 1980; 101:627-33. 18. Burnett RR, Diaz R, Waldrop TC, Hallmon WW. Clinical perspectives of periodontal and restorative interactions. Compendium 1994;15:644-55.
Reprint requests to: DR PETER M. DI FIORE COLLEGE OF DENTISTRY UNIVERSITY OF KENTUCKY LEXINGTON, KY 40536 FAX: (606) 257-1847 E-MAIL: [email protected] Copyright © 1999 by The Editorial Council of The Journal of Prosthetic Dentistry. 0022-3913/99/$8.00 + 0. 10/1/99580
Color perception of laboratory-fired samples of body-colored ceramic Geart JL, Kinirons MJ. J Dent 1999;27:145-8.
Purpose. This study compared the perceived shade of ceramic chips by controlled observers with the shade guide system suggested by the ceramic manufacturer. Material and methods. Eight shades each of 4 ceramic systems were used to create ceramic disks 0.7 mm in thickness. Disks were created and polished as recommended by the respective manufacturers for porcelain veneers. A group of 20 observers who had no color vision deficiencies viewed samples in a controlled environment. Mid gray boards were used as a neutral background, illumination was from a color corrected lamp, and samples were viewed a distance of 1 mm from the background. Observers were asked to match each disk with the appropriate tab from a Vita Lumin shade guide. For individual measurements, the observed color of each sample was categorized as (1) matching the manufacturer’s specified shade, (2) having a higher value, or (3) having a lower value. Results. Of the 32 samples examined, 6 were scored as positive matches with the recommended shade guide. Of these shades, B1 was assessed as a positive match by the majority of the observers. Fourteen agreed shades were found, wheras the remaining 12 shades were deemed as unidentified shades. The majority of observations disagreed with the manufacturer’s designated shade. Overall, laboratory fabricated ceramic shade tabs were rated higher in value than specified by the manufacturers. Significant differences in the pattern of shade matches and disagreements between brands were also found. Conclusion. Alternative shade determination systems and ceramic color modifications are required if color fidelity between the shade guide and materials tested is to be improved. 10 References. —ME Razzoog
SEPTEMBER 1999
269
The unique occurrence of 4 rooted maxillary molars with 2 palatal roots has been documented. 1-5 The restoration of an endodontically treated tooth commonly requires the placement of a complete crown. The margin of the complete crown restoration should minimally extend into the gingival crevice because crown margins that encroach on the subcrevicular tissues can induce a progressive inflammatory response.6,7 The dimensions of the structural components of the supraosseous soft tissues were studied by Gargiulo et al,8 who measured the dentoalveolar tissues at 325 tooth surfaces of 287 clinically normal human autopsy specimens. They reported mean dimensions for all age categories of 0.69 mm for sulcular depth (range 0.00 to 5.36 mm), 0.97 mm for junctional epithelium (range 0.08 to 3.72 mm), and 1.07 mm for connective tissue attachment (range 0.00 to 6.52 mm). Although this study revealed gingival attachments with wide variations within a normal range, the mean values reported for each of the tissue components have served as guidelines for desirable dimensions before placement of artificial crowns. As a result, surgical crown lengthening procedures with removal of crestal alveolar bone have become common. Surgical crown lengthening also has been recommended when crown fractures, root caries, resorptions, or perforations extend subcrestally.9-12 A mucoperiosteal flap is reflected and apically positioned after crestal bone is removed to allow adequate connective tissue attachment and epithelial junction that will be commensurate with the restorative crown margin.9-12 Although the apically positioned flap preserves the attached gingiva, the osseous surgical component of this procedure necessitates removal of supporting bone from adjacent teeth to develop a physiologic postsurgical gingival contour.9-12 Orthodontic tooth extrusion has been offered as an alternative to surgical crown lengthening because the gingival attachment apparatus migrates coronally while maintaining crestal bone. Minimal osseous surgery is required after extrusion, and there is little effect on the supporting bone around adjacent teeth.13-16 Orthodontic extrusion also can be
aAssociate
Professor, Department of Endodontics; and Former Director, Dental School, Northwestern University, Chicago, Ill. J Prosthet Dent 1999;82:266-9. 266 THE JOURNAL OF PROSTHETIC DENTISTRY
used successfully on molars as an alternative to osseous surgery for the restorative management of subcrestal root defects.16 When crown lengthening procedures for molar teeth are considered, root structure is a critical factor. The number and locations of furcations should be considered before osseous surgery. In a study of the root structure of a large collection of extracted human teeth, the furcation entrances for molar teeth ranged from 3 to 5 mm apical to the cementoenamel junctions (CEJ).17 These values are well within the limits of dimensional tissue changes that occur with osseous surgery. Surgical crown lengthening procedures that involve the removal of bone around the root trunks of multirooted teeth can adversely compromise periodontal health if furcations become exposed.18 This clinical report presents an endodontically treated 4-rooted maxillary molar with subsequent periodontal and restorative complications associated with crown lengthening surgery.
CLINICAL REPORT A 31-year-old man was referred for endodontic treatment of the maxillary right first molar with a history of an acute exacerbation of a chronic pulpitis. The patient was in good general health with no significant past or present illnesses. Clinical examination revealed a maxillary molar with a disto-occlusal temporary restoration. The gingival attachment apparatus was normal and intact without gingival recession or inflammation. Neither furcation involvement nor periodontal pockets were observed, and tooth mobility was physiologic. Pain and tenderness were absent on percussion and palpation. Radiographic examination did not reveal radiolucencies at the apices or furcations; however, it did reveal the probability of a molar with 4 roots (Fig. 1). An endodontic diagnosis of irreversible pulpitis was made. Endodontic treatment was initiated. After access into the pulpal chamber, 4 separate canal orifices were identified and negotiated in 4 quadralaterally placed separate roots (mesiobuccal, distobuccal, mesiopalatal, and distopalatal). The unique root trunk structure of this molar had 4 entrances to the furcation (buccal, palatal, mesial, and distal). The measurements of the lengths of the 4 distinct roots were taken and adjusted, and the root canals were debrided and prepared. Root canals VOLUME 82 NUMBER 3
DI FIORE
Fig. 1. Preoperative periapical radiograph.
THE JOURNAL OF PROSTHETIC DENTISTRY
Fig. 3. Three-year follow-up recall photograph (buccal view) demonstrates buccal gingival recession.
Fig. 2. Postoperative radiographic (straight view) of gutta percha obturated root canals and silver alloy amalgam postcore structure.
Fig. 4. Three-year follow-up recall photograph (palatal view) demonstrates palatal furcation exposure.
were obturated with gutta percha and sealer with a lateral and vertical condensation technique. Spaces were left in each canal for a coronoradicular reconstruction. A matrix band retainer was placed and distally wedged, the cavity preparation and root canal spaces were coated with cavity varnish, and a silver amalgam alloy postcore reconstruction was placed and adjusted occlusally (Fig. 2). Clinical examination at this time did not reveal any signs or symptoms of gingivitis or periodontitis. The patient was then referred for a complete crown restoration, and the attending dentist referred the patient for crown lengthening. Subsequently, the tooth was treated with surgical crown lengthening and restored. Shortly thereafter, the patient left the country for 3 years. On returning, the patient reported with a chief complaint of painful, sore, tender, and bleeding
gums around the maxillary right first molar. Clinical examination revealed gingival inflammation, gingival recession, furcation exposures, and proximal periodontal pockets (Figs. 3 and 4). This condition was specifically localized to the right first molar area, and there were no other signs or symptoms of periodontal disease anywhere else in the mouth. The patient’s oral hygiene was good, except where the painful gingivae around the maxillary right first molar prevented thorough plaque removal. Radiographic examination revealed interproximal bone rarefaction, cervical root notches, and a furcation radiolucency (Fig. 5). Radiographic examination indicated that the periapical tissues of all 4 roots were normal (Fig. 6). Diagnoses made were acute gingivitis, chronic periodontitis, and cervical root gouges. The patient was referred for periodontal and
SEPTEMBER 1999
267
THE JOURNAL OF PROSTHETIC DENTISTRY
DI FIORE
Fig 6. Three-year follow-up recall radiograph (distal angled view) demonstrates normal periapices.
Fig. 5. Three-year follow-up recall bite-wing radiograph demonstrates interproximal bone loss, cervical root notches, and furcation radiolucency.
restorative treatment with a guarded prognosis for retention of this molar.
DISCUSSION This clinical report illustrates the significance of evaluating the indications, contraindications, and possible complications of prerestorative crown lengthening surgery for each patient. On initial clinical examination, there was adequate clinical crown present for a retentive crown preparation, and the distal restorative margin although subgingival appeared clinically within tolerable limits for an adequate epithelial and connective tissue attachment. The periapical radiograph (Fig. 1) did not suggest that surgical crown lengthening was necessary. A bite-wing radiograph, which would better illustrate the level of crestal bone, would likely have shown more supraosseous tooth structure than observed on the periapical radiograph. In this clinical report, the root trunk presented with severe restrictions for osseous surgery with 4 furcal entrances close to the CEJ and gingival crest, increasing the likelihood for surgical exposure. In addition, and most critically, the profound divergence of the roots from the cervical root trunk into the alveolar 268
bony housing made it difficult to remove crestal bone without cervically altering the root trunk surfaces. Although the crown contour and margins were not physiologic (Figs. 3 and 4), and the bite-wing radiograph (Fig. 5) suggested molar malocclusion with occlusal interferences and marginal ridge discrepancies, the most likely cause for the localized periodontitis was the severe root damage. Injudicious removal of alveolar bone with coarse diamond stones or large carbide burs can cause permanent and irreparable damage to the roots. These gouged root surfaces are virtually impossible to restore by the dentist or maintain by the patient, and chronic progressive localized periodontitis is likely to occur. Surgical crown lengthening requires the reflection of mucoperiosteal flaps to expose the cervical root surfaces and crestal alveolar bone. Osseous reduction can be accomplished without altering the surfaces of the roots by first reducing the crestal bone with an end-cutting bur. Small round stones or burs and periodontal hand chisels can then be used to contour and finish the osseous margins. Bone must be differentiated from cementum, and adequate hemostasis, along with copious irrigation, is necessary to ensure visibility. Crown lengthening should not always be considered a routine, prerestorative procedure. An assessment of root trunk and furcation is essential before selecting crown lengthening procedures for multirooted teeth. When crown lengthening is indicated, the cervical root surfaces must not be damaged during the osseous reduction procedure. REFERENCES 1. Diamond M. Dental anatomy including anatomy of the head and neck. 3rd ed. New York: Macmillan; 1952. p. 203-5. 2. Slowey RR. Radiographic aids in the detection of extra root canals. Oral Surg 1974;37:762-72. 3. Thews ME, Kemp WB, Jones CR. Aberrations in palatal root and root canal morphology of two maxillary first molars. J Endod 1979;5:94-6.
VOLUME 82 NUMBER 3
DI FIORE
THE JOURNAL OF PROSTHETIC DENTISTRY
4. Stone LH, Stroner WF. Maxillary molars demonstrating more than one palatal root canal. Oral Surg Oral Med Oral Pathol 1981;51:649-52. 5. Christie WH, Peikoff MD, Fogel HM. Maxillary molars with two palatal roots: a retrospective clinical study. J Endod 1991;17:80-4. 6. Newcomb GM. The relationship between the location of subgingival crown margins and gingival inflammation. J Periodontol 1974;45:151-4. 7. Maynard JG Jr, Wilson RD. Physiologic dimensions of the periodontium significant to the restorative dentist. J Periodontol 1971;50:170-4. 8. Gargiulo AW, Wentz FM, Orban B. Dimensions and relations of the dentogingival junction in humans. J Periodontol 1961;32:261-7. 9. Palomo F, Kopczyk RA. Rationale and methods for crown lengthening. J Am Dent Assoc 1978;96:257-60. 10. Lovdahl PE, Gutmann JL. Periodontal and restorative considerations prior to endodontic therapy. Gen Dent 1980;28:38-45. 11. Fugazzotto PA. Periodontal restorative interrelationships: the isolated restoration. J Am Dent Assoc 1985;110:915-7. 12. Davis JW, Fry HR, Krill DB, Rostock M. Periodontal surgery as an adjunct to endodontics, orthodontics, and restorative dentistry. J Am Dent Assoc 1987;115:271-5. 13. Ross S, Dorfman HS, Palcanis KG. Orthodontic extrusion: a multidisciplinary treatment approach. J Am Dent Assoc 1981;102:189-91. 14. Biggerstaff RH, Sinks JH, Carazola JL. Orthodontic extrusion and biologic width realignment procedures: methods for reclaiming nonrestorable teeth. J Am Dent Assoc 1986;112:345-8.
Noteworthy Abstracts of the Current Literature
15. Oesterle LJ, Wood LW. Raising the root. A look at orthodontic extrusion. J Am Dent Assoc 1991;122:193-8. 16. Lythgoe JR, Torabinejad M, Simon JH. Extrusion techniques for the general dentist. Gen Dent 1980;28:42-9. 17. Gher ME, Vernino AR. Root morphology—clinical significance in pathogenesis and treatment of periodontal disease. J Am Dent Assoc 1980; 101:627-33. 18. Burnett RR, Diaz R, Waldrop TC, Hallmon WW. Clinical perspectives of periodontal and restorative interactions. Compendium 1994;15:644-55.
Reprint requests to: DR PETER M. DI FIORE COLLEGE OF DENTISTRY UNIVERSITY OF KENTUCKY LEXINGTON, KY 40536 FAX: (606) 257-1847 E-MAIL: [email protected] Copyright © 1999 by The Editorial Council of The Journal of Prosthetic Dentistry. 0022-3913/99/$8.00 + 0. 10/1/99580
Color perception of laboratory-fired samples of body-colored ceramic Geart JL, Kinirons MJ. J Dent 1999;27:145-8.
Purpose. This study compared the perceived shade of ceramic chips by controlled observers with the shade guide system suggested by the ceramic manufacturer. Material and methods. Eight shades each of 4 ceramic systems were used to create ceramic disks 0.7 mm in thickness. Disks were created and polished as recommended by the respective manufacturers for porcelain veneers. A group of 20 observers who had no color vision deficiencies viewed samples in a controlled environment. Mid gray boards were used as a neutral background, illumination was from a color corrected lamp, and samples were viewed a distance of 1 mm from the background. Observers were asked to match each disk with the appropriate tab from a Vita Lumin shade guide. For individual measurements, the observed color of each sample was categorized as (1) matching the manufacturer’s specified shade, (2) having a higher value, or (3) having a lower value. Results. Of the 32 samples examined, 6 were scored as positive matches with the recommended shade guide. Of these shades, B1 was assessed as a positive match by the majority of the observers. Fourteen agreed shades were found, wheras the remaining 12 shades were deemed as unidentified shades. The majority of observations disagreed with the manufacturer’s designated shade. Overall, laboratory fabricated ceramic shade tabs were rated higher in value than specified by the manufacturers. Significant differences in the pattern of shade matches and disagreements between brands were also found. Conclusion. Alternative shade determination systems and ceramic color modifications are required if color fidelity between the shade guide and materials tested is to be improved. 10 References. —ME Razzoog
SEPTEMBER 1999
269