Restoration evaluation composite
of endodontically treated anterior teeth: An of coronal microleakage of glass ionomer and resin materials
A. M. Diaz-Arnold, University
D.D.S., M.S.,* and L. R. Wilcox,
of Iowa, College of Dentistry, Iowa City, Iowa
A glass ionomer material was evaluated for coronal microleakage in permanent lingual access restorations of endodontically treated anterior teeth. The material was tested as a restoration, placed over a zinc oxide-eugenol base, and as a base with an acid-etched composite resin veneer and a dentinal bonding agent. Restored teeth were thermocycled, immersed in silver nitrate, developed, and sectioned to assess microleakage. Significant coronal leakage was observed with all materials used. (J PROSTHET DENT 1990;64:643-6.)
ndodontically treated teeth are usually restored with dowel cores and complete coverage restorations.’ This type of restoration supports both esthetic and functional requirements. A more conservative restorative approach is indicated with caries-free teeth.2 As with complete coverage restorations, the conservative restoration must satisfy esthetic requirements and preserve the integrity of the tooth and the endodontic treatment. Microleakage around a conservative access restoration can result in intrinsic discoloration of the tooth as well as dissolution of the endodontic sealer, thus compromising the prognosis of the tooth. 3,4 Due to their cariostatic and adhesive properties, glass ionomer materials are advocated for use in situations where microleakage or recurrent caries are likely.5-7 These materials can be used as the sole restoration or as bases for a composite resin veneer.8-10 This study evaluated the extent of in vitro microleakage of a glass ionomer dental material (Ketac-fil, ESPEPremier, Norristown, Pa.) in lingual access preparation. The material was tested as a restoration, as a restoration placed over a zinc oxide-eugenol (ZOE) base, and as a base material with an acid-etched composite resin veneer and Scotchbond 2 (3M Co., St. Paul, Minn.) as a dentinal bonding agent.
Thirty-two extracted, noncarious human teeth were stored in water and were used for this study. Lingual access was prepared. Canal patency was determined by passing a No. 10 file (K-flex, Kerr-Sybron, Romulus, Mich.) through the access opening to the apical foramen. Working length was established by subtracting 1 mm from the measurement obtained with the No. 10 file placed into the canal and its tip visible at the apex. The canals were prepared with
*Assistant Professor,Department of Family Dentistry. **Associate Professor,Department of Endodontics. IO/1121923
g& lo”omer Composlte resin
Fig. 1. Experimental groups.
K-type files and Gates Glidden drills (Union Broach, Long Island City, N.Y.). The step-back technique was used for canal flaring. Each canal was obturated with gutta percha (Kerr-Sybron) and Roth’s 811 sealer (Roth Drug Co., Chicago, Ill.). The lateral condensation technique was used for obturation. A heated instrument was used to remove the gutta percha to the level of the cementoenamel junction. Each access was then temporized with cotton and Cavit material (ESPE-Premier). All teeth were stored at 37’ C in deionized water for 24 hours. The teeth were randomly divided into three groups of 10 teeth each (experimental) and one group of two teeth (controls): group 1 = lingual access restored with a ZOE base (IRM, L.D. Caulk Co., Milford, Del.) and a Ketac-fil veneer; group 2 = lingual access restored with Ketac-fil material; group 3 = lingual accessrestored with a Ketac-fil base and a veneer of acid-etched composite resin (Herculite XR, Kerr-Sybron) with Scotchbond 2 as the dentinal 643
I. Mean lengths of materials and leakage (mm)
Mean restoration length (n = 10)
Mean restoration leakage (n = 10)
Mean base length (n = 10)
Mean base leakage (n = 10)
Mean gutta percha length (n = 10)
Mean gutta percha leakage
(n = 4)
(n = 8)
1.85 (n = 5)
Table II. Ratio of mean restoration + base leakage (mm) to restoration + base length (mm)
Duncan multiple range group
n = IO; Alpha = 0.05.
2. Microleakage within restorative materials, evident in all groups. Arrow denotes extent of silver nitrate penetration.
bonding agent; group 4 = positive and negative controls (one tooth each)-the positive control tooth was not restored, the negative control tooth was restored with Ketac-fil material. Fig. 1 illustrates the experimental groups used in this study. Manufacturers’ recommendations were followed for each restorative material. Following removal of the cotton and Cavit temporary restoration, the lingual surface of all teeth was cleaned with a slurry of nonfluoridated flour of pumice in a rubber cup. Group 1 was initially restored to the cavosurface with an IRM base. A No. 555 bur was used to remove 2.5 mm of the base. The teeth were pumiced, rinsed, and air dried. Polyacrylic acid (Durelon, ESPE-Premier) was applied for 10 seconds to remove the smear layer. The teeth were rinsed for 30 seconds and dried. A Ketac-fil Applic capsule was activated, placed in a high-speed amalgamator (Varies Mix II, L.D. Caulk), and triturated for 10 seconds. The Applic applier instrument provided by the manufacturer was used to place the restorative material directly into the lingual access preparation. A layer of Visio-Bond bonding agent (ESPE-Premier) was placed over the entire restoration and polymerized for 20 seconds with a visible-light instrument (Elipar II, ESPE Gmbh, Seefeld, W. Germany). No additional trimming or finishing was performed. In group 2, the lingual accessof teeth was restored using Ketac-fil material and a layer of Visio-Bond material.
Manufacturers’ recommendations were followed for both materials. Group 3 was initially restored with Ketac-fil material and a layer of Visio-Bond material. Fifteen minutes after the placement of Ketac-fil material, a No. 330 bur with water spray was used to remove 1.5 mm of the restorative material. The Scotchbond 2 dental adhesive system was then applied. This system included applications of Scotchgel enamel etchant (3M Co.), Scotchprep dentin primer (3M Co.), and Scotchbond 2 adhesive. Herculite XR composite resin was subsequently placed to restore lingual contour. The composite resin was polymerized for 40 seconds with visible light. No additional finishing was performed. All teeth were stored at 37’ C in deionized water for 18 hours. The teeth were then thermocycled for 24 hours in deionized water baths maintained at 5” and 60’ C. The cycle rate was one cycle every 80 seconds with a 30-second dwell time in each bath; 1080 cycles were completed. After thermocycling, each tooth was painted with two layers of finger nail varnish. Experimental and positive control teeth were varnished to cover all surfaces to within 1 mm of the access.The negative control was varnished on all surfaces including total coverage of the access restoration. All teeth were placed in a 50% (by weight) aqueous solution of silver nitrate and were stored in darkness for 3 hours.ri The teeth were rinsed with tap water and placed in photodeveloper solution under fluorescent light for 16 hours. The specimens were then rinsed with tap water and sectioned buccolingually through the center of the restorations. The extent of silver nitrate penetration was determined with a measuring microscope (BI-5, Mitutoyo Mfg. CO.
III. Ratio of mean gutta percha leakage (mm) to gutta percha length (mm)
Duncan multiple range
A (n = 4) A + B (n = 8) B (n = 5)
Tokyo, Japan) calibrated to 0.001 mm at 30 power. The depth of silver nitrate penetration along the restorationtooth interface was recorded. The lengths of the veneer restorations, the bases, and the gutta percha were also recorded. Results were expressed as a ratio of leakage depth over length. RESULTS The positive control tooth exhibited leakage involving the total length of the gutta percha. The negative control tooth did not demonstrate any leakage. All experimental teeth exhibited leakage (Fig. 2, Table I). Analysis of variance (ANOVA) and Duncan’s multiple range tests (p = 0.05) were used to compare the ratios of mean restoration + base leakage (mm) to mean restoration + base length (in millimeters) for the groups. Statistical analysis did not reveal significant differences among groups in microleakage depth through the veneer restorations or bases (Table II). The ratio of mean gutta percha leakage (in millimeters) to gutta percha length (in millimeters) demonstrated significant differences between the groups (Table III). Leakage into the gutta percha was evident in some specimens of all experimental groups (Fig. 3). Four teeth in group 1 exhibited leakage into the gutta percha. Eight of the 10 teeth in group 2 demonstrated leakage into the gutta percha. In group 3, five teeth demonstrated leakage into the gutta percha.
omer restoration failed to completely seal the enamel-dentin-restorative interface. Glass ionomer bases with composite resin veneers are advocated in locations of wear or high abrasion.*-lo In this study, the composite resin veneer placed with acid etch and new dentinal bonding techniques also failed to provide a complete seal. The small size of the silver nitrate molecule may lead to overestimation of the in vivo extent of leakage. Controlled, long-term clinical trials are needed to better predict the durability of these materials in restorations where leakage control is a critical factor.
The results of this study indicate that ZOE cement, glass ionomer materials, and composite resin materials exhibit leakage. This leakage could compromise the prognosis of the endodontically treated tooth. Previous studies have documented the leakage of zinc phosphate cement and temporary stopping materials.12, l3 Leakage of ZOE materials has also been examined.12sl4 In this study, ZOE did not demonstrate superior sealing qualities. The response of these materials to thermal stress and their compatibility with glass ionomer materials warrants further investigation. Previous investigations have demonstrated varying degrees of leakage with glass ionomer materials.15-20It is clear that the methodology used has a significant effect on the results. Under our experimental conditions, the glass ion-
1. All restorative materials used in this study permitted leakage of silver nitrate along the tooth-restorative interface. 2. No group was clearly superior in preventing microleakage of silver nitrate.
Fig. 3. Leakage into gutta percha, evident in all groups. Arrow denotes extent of silver nitrate penetration.
REFERENCES 1. Shillingburg HT, Kessler JC. Restoration of the endodontically treated tooth. Chicago: Quintessence Publishing Co, 1982:13-44. 2. Halpern BG. Restoration of endodontically treated teeth: a conservative approach. Dent Clin North Am 1985;29:293-303. 3. Swanson K, Madison S. An evaluation of coronal microleakage in endodontically treated teeth. Part I. Time periods. J Endodont 1987;13: 56-9. 4. Madison S, Swanson K, Chiles SA. An evaluation of coronal microleakage in endodontically treated teeth. Part II. Sealer types. J Endodont 1987:13:109-12.
5. McLean JW, Wilson AD. The clinical development of the glass ionomer cement. II. Some clinical applications. Aust Dent J 1977;22:120-7. 6. McLean JW, Wilson AD. The clinical development of the glass ionomer cement. III. The erosion lesion. Auat Dent J 1977;22:190-5. 7. Mount GJ. Glass ionomer cements: clinical considerations. In: Clark JW, ed. Clinical dentistry. vol 4. Philadelphia: JB Lippincott Co, 19841-24. 8. McLean JW, Presser HJ, Wilson AD. The use of glass-ionomer cements in bonding composite resins to dentine. Br Dent J 1985;158:410-4. 9. McLean JW. Limitations of posterior composite resins and extending their use with glass ionomer cements. Quintessence Intl1987;18:517-29. 10. McLean JW. New concepts in cosmetic dentistry using glass-ionomer cements and composites. Can Dent Assoc J 1986;14:20-7. 11. Wu W, Cobb E, Dermann K. Detecting margin leakage of dental composite restorations. J Biomed Mater Res 1983;17:37-43. 12. Marosky JE, Patterson SS, Swartx M. Marginal leakage of temporary sealing materials used between endodontic appointments and assessed by calcium 45-an in vitro study. J Endodont 1977;3:110-3. 13. Wilcox LR, Diax-Arnold AM. Coronal microleakage of permanent lingual access restorations in endodontically treated anterior teeth. J Endodont 1989;15:584-7.
Reliability and validity location instrument
14. Tamse A, Ben-Amar A, Gover A. Sealing properties of temporary filling materials used in endodontics. J Endodont 1982;8:332-5. 15. Alperstein KS, Graver HT, Herold RCB. Marginal leakage of glass-ionomer cement restorations. J PROSTHET DENT 1983;50:803-7. 16. Baez RJ, Weed RM, Morales F. Microleakage of glass ionomer restorations. J Dent Rest 1984;63(special issueh294. 17. Hembree JH, Andrews JT. Marginal leakage of anterior restorative materials: a five-year study. J Tenn Dent Assoc 1984;64:28-30. 18. Herrin KH, Shen C. Microleakage of root caries restorations. Geriodontics 1985;1:156-9. 19. Welsh EL, Hembree JH. Microleakage at the gingival wall with four class V anterior restorative materials. J PROSTHET DENT 1985;54:370-2. 20. Robbins JW, Cooley RL. Microleakage of Ketac-Silver in the tunnel preparation. Oper Dent 198&13:8-11. Reprint requests to: DR. A. M. DLU-ARNOLD COILEGE OF DENTJSTRY UNlVERSlTY OF IOWA IOWA CITY, IA 52242
of a transverse
John F. Bowley,
D.D.S., M.S.,* and Calvin J. Pierce, D.M.D., Ph.D.** College of Dentistry, Columbus, Ohio; and University of Pittsburgh, School of Dental Medicine, Pittsburgh, Pa.
Previous studies have demonstrated a relatively accurate location of the transverse horizontal axis (THA) with several different instrument systems. This study statistically evaluated the reliability and validity of an instrument used to locate a known THA on a mannequin. Three experienced prosthodontists were the subjects. Each operator used 15 mm of interincisal arc to locate the THA. The mandibular stylus was aligned by the investigator with the known horizontal axis. The vertical microdot flags were positioned so the stylus was over a known coordinate and were repositioned so the operator could attempt to locate the axis. The known coordinates were varied with each of four trials. Subjects No. 1 and 3 demonstrated the best coefficient of reliability, 0.25. The 96% confidence interval for linear deviation from the known was 0.44 + 0.10 mm on the right side and 0.97 ? 0.10 mm on the left side. These confidence intervals did not include zero. A statistically better result was achieved on the right side compared with the left side (Fl$ = 131.24, p = 0.0014). The results of this study indicate that a random error factor of 0.3 to 1.2 mm can be expected when this instrument system is used clinically. (J PROSTHET DENT 1990;64:646-50.)
he transverse horizontal axis (THA) as defined in the Glossary of Prosthodontic Terms1 is “an imaginary line around which the mandible may rotate through the sagittal plane.“l This axis is important clinically to properly mount the maxillary cast on an articulator with a face-bow transfer.2 *Assistant Professor, Restorative tion, The Ohio State University,
and Prosthetic Dentistry College of Dentistry.
**Assistant Professor,Behavioral SciencesDepartment, University
Preston2 presented the problems associated with a maxillary cast mounted with a face-bow inconsistent with this axis. In this case, interocclusal records at an open vertical dimension or an arbitrary increase in the occlusal vertical dimension will result in occlusal errors. These occlusal errors result from differences in the arc of closure on the articulator compared with that on the patient. The inferior and superior deviations were the most critical errors, assuming colinearity. The precision of the location of the THA has been widely investigated to determine the reliability and validity of various operators.3-6 The variation among these studies was DECEMBER1990