appearance of titanium al ented with different luting materials S,” W. James Wright, Jr., DDS,” and William F. Bowles, III, DDSb University of Tennessee, College of Dentistry, Memphis, Tenn. Eight luting materials were compared to determine which of them obscured the radiographic image of a cemented titanium alloy prefabricated post. Eight extracted, endodontically treated, maxillary molar teeth were selected for the study. A post chaunel was prepared in the lingual root canal of each tooth and a titanium alloy prefabricated post was cemented with one of the selected luting materials. Preoperative, precementation, and postcementation radiographs were compared visually to determine the outline of the cemented titanium alloy post. Glass ionomer cements obscured the outline more than composite resin cements but less than zinc phosphate or polycarboxylate cements. Further study is indicated before recommendation of a luting material with titanium alloy prefabricated posts. (J PKOSTRET DENT 1992;67:632-7.)

itanium alloy is considered more biocompatible than stainless steel alloy; thus titanium alloy prefabricated posts have been suggested for treatment of coronally debilitated endodontically treated teeth.l They are, however, less radiopaque than stainless steel prefabricated posts, and radiolucent luting materials should be used to improve their radiographic imaging.2 This study tested different dental luting materials for masking the radiographic image of cemented titanium alloy posts. ETNODS Eight maxillary molar teeth were selected for this study on the basis of radiographic evidence of suitable lingual

aAssistant Professor, Department of Prosthodontics, Division of Fixed Prosthodontics. bProfessor and Chairman, Department of Prosthodontics. 10/1/35598

Fig. 1. Specimen 1. Left to right, with Flecks zinc cement.

Preoperative,

canal morphology for the insertion of a prefabricated post. Each tooth was numbered and matched with a preoperative radiograph. The teeth were previously mounted in autopolymerizing methyl methacrylate blocks, instrumented, and obturated with gutta-percha and an endodontic sealer. The preoperative radiographic image of the hngual canal of each selected molar tooth was visually compared with the Para-Post system twist drill assortment (Whaledent International, New York, N.Y.) for estimation of the diameter and length of the maximum-size twist drill. The temporary stopping in the access opening of each tooth was removed to the pulpal Aoor witb a round bur so that the canals could be observed. The gutta-percha was then removed from the lingual canal with a heated endodontic instrument for visualization of the canal immediately apical to the orifice. Each post channel preparation was completed with a 0.9 mm diameter Para-Post system (PPS) twist drill mounted in a 102 reduction contra-angle handpiece to the estimated length. After the length was confirmed clinically, a 1 mm diameter PPS twist drill was

precementation,

and postcementation

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Fig. 2. Specimen 2. Left to right, with Durelon cement.

Table

I. Materials

Preoperative,

Flecks zinc cement Durelon Keta-Cem radiopaque Ketac-Cem Parke11 cement/liner type 1 Flexi-Flow

Material

Lot No.

Liq.-H61050785 Pow.-D15032385 Liq.-0010 Pow.-0080 Liq.-0013 Pow.-0002 Liq.-0015 Pow.-0105 Pkg. 0587172

type

Manufacturer/distributor

Zinc phosphate cement

Glass ionomer cement

Mizzy, Inc., Clifton Forge, Va. ESPE-Premier Sales Corp., Norristown, Pa. ESPE-Premier Sales Corp.

Glass ionomer cement

ESPE-Premier Sales Corp.

Glass ionomer cement

Parke11Biomaterials Division Farmingdale, N.Y. Essential Dental Systems, Inc., New York, N.Y. The L. D. Caulk Division, Dentsply International, Milford, Del. J. Morita USA, Inc., Tustin, Calif. Whaledent International, New York, N.Y. ESPE-Premier Sales Corp.

Polycarboxylate cement

Pkg. 060189

Composite cement

Biomer

Pkg. 041387

Composite cement

Panavia EX

Pkg.64160

Composite cement

Para-Post Plus

Titanium alloy prefabricated post

Ketac-Silver

Glass ionomer restorative materiai

used to enlarge the diameter of the post channel to the desired length. When each lingual canal preparation was completed, a 1 mm diameter titanium alloy Para-Post-Plus prefabricated post (Whaledent International) was inserted in the post channel. A precementation radiograph was made to confirm seating and determine the visual radiopacity of the post. The radiographs were numbered and matched to each specimen. Eight dental cements were selected on the basis of common clinical acceptance or manufacturer’s specific recommendations (Table I). Each Para-Post-Plus (PPP) prefabricated post was sectioned with a Carborundum separating disk to prevent extension up to the occlusal surface when

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Table

II.

Specimen NO.

Specimen to Ming

material

pairing

TYPO

Trade name

1

Zinc phosphate

2 3

Polycarboxylate Glass ionomer

3 5

Glass ionomer Glass ionomer

6 I 8

Composite Composite Composite

Fleck’s zinc cement Durelon Ketac-Cem radiopaque Ketac-Gem Parke11 cement/ liner type 1 Flexi-Flow Biomer Panavia EX

Illustration

Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8

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Table III.

. 3. Specimen 3. Left to right, Preoperative, with Ketac-Cem radiopaque cement.

precementation,

and postcementation

Fig. 4. Specimen 4. Left to right, Preoperative, with Ketac-Cem cement.

precementation,

and postcementation

Advertised

Trade name

Flecks zinc cement Durelon Ketac-Cem radiopaque Ketac-Cem Parkell cement/ liner type 1 Flexi-Flow Biomer Panavia EX

radiopacity

of luting materials

Manufacturer

Radiopaque

Sales Corp. Sales Corp.

Yes Yes Yes

ESPE-Premier Sales Corp. Parke11 Biomaterials Division

No Yes

Essential Dental Systems, Inc. L. D. Caulk Division, Dentsply International J. Morita USA, Inc.

Yes No

Mizzy, Inc. ESPE-Premier ESPE-Premier

Yes

inserted in the post channel. After each PPP post was shortened, it was cemented with a different luting material and recorded by the number of each specimen (Table II). When the cement had set, the access opening was restored

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with Ketac-Silver glass ionomer cement and a postcementation radiograph was made. All radiographs were made for 0.3 second at 90 kV and 15 mA with a source-to-film distance of 15 inches and processed in the standard cycle of an automated processor. Each radiograph was copied to black and white photographic film. The negatives of each specimen are illustrated with a preoperative, precementation, and postcementation view on each print (Figs. 1 through 8).

RESULTS Comparison of the titanium alloy posts with the guttapercha in each precementation radiograph (Figs. 1 through 8) demonstrated the similar radiopacity of the two materials. Zinc phosphate cement (Fig. 1) was the most radiopaque, but polycarboxylate cement (Fig. 2) was similar, and both cements effectively obscured the outline of the PPP prefabricated posts. The glass ionomer cements (Figs. 3 through 5) demonstrated almost equal radiopacity; Ketac-Cem (Fig. 3) was slightly more radiopaque. The glass

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Fig. 5. Specimen 5. Left to right, Preoperative, precementation, and postcementation with Parke11cement/liner type 1.

Fig. 6. Specimen 6. Left to right, Preoperative, precementation, and postcementation with Flexi-Flow cement.

ionomer cements partially disguised the outline of the PPP prefabricated posts. The composite resin cements (Figs. 6 through 8) were the least radiopaque of the luting materials, minimally concealing the outline of the Para-Post-Plus prefabricated posts. DISCXJSSION The PPP prefabricated post was selected for this study because the design met the reported requirements.3-6 The post length was estimated and then prepared to the length of the clinical crown without invading the apical third of the root to simulate clinical application with minimal stress to the tooth.7 Each tooth/post specimen was randomly assigned a cement, but there was no attempt to match a cement to specimen-specific cliaical indication. The zinc phosphate cement was mixed for 3 minutes and the other luting materials were manipulated according to manufacturers’ instructions. After placement in plastic photographic slide mounts,

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the radiographs were compared visually without magnification on a standard radiograph viewer to determine the relative radiopacity of the PPP prefabricated posts and luting materials. Visual radiopacity of an image results from radiographic film contrast, density, x-ray energy, and x-ray absorption. The x-ray absorption of a material is related to its thickness and density.s The density and contrast of all the study radiographs were similar. The slight radiopacity of the titanium alloy prefabricated posts was apparent and consistent in each precementation radiograph (Figs. 1 through 81, demonstrating a radiopacity similar to gutta-percha. The luting materials demonstrated differing degrees of radiopacity in the postcementation radiographs (Figs. 1 through 8). The more radiopaque cements completely masked the outline of the posts, and those that were less radiopaque tended to make the posts appear as poorly condensed gutta-percha. Six of the cements selected for this study are advertised as radiopaque by the manufacturers (Table III). Biomer resin cement is less radiopaque than zinc phosphate, that

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Fig. 7. Specimen 7. Left to right, Preoperative, precementation, and postcementation with Biomer cement.

Fig. 8. Specimen 8. Left to right, Preoperative, precementation, and postcementation with Panavia EX cement.

is, 1.5 on a scale that scores zinc phosphate as 5.g Panavia EX cement and Flexi-Flow cement are luting agents that are also advertised as radiopaque, but in this study neither demonstrated greater radiopacity than Biomer cement. If a titanium alloy prefabricated post is used in restoring an endodontically treated tooth, a cement that enhances its radiographic image is indicated. A cement that obscures the radiographic image of the post would create a problem in subsequent diagnosis or retreatment of an endodontitally treated tooth. Because of their minimal radiopacity, the composite resin luting materials appear indicated for luting titanium alloy prefabricated posts. Tjan et al.1° reported that posts cemented with composite resin in mechanically corrugated post spaces had greater retention than posts spaces that had the smear layer removed with 17 % EDTA without mechanical corrugation. However, because Leary et al.tl reported that removing internal structure weakens the tooth, such an accommodation for improving retention of prefabricated posts, when a composite resin luting material is used, presents a clinical enigma.

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Radke et aLI reported that zinc phosphate and glass ionomer cements were more retentive than polycarboxylate and composite resin cements for cast gold posts using an earlier Parapost system design. Maniatopoulos et a1.13 reported that glass ionomer cements demonstrated the greatest tensile shear strength with threaded posts,

This study revealed that glass ionomer luting materials obscured the outline of titanium alloy prefabricated posts more than composite resin, but less than zinc phosphate or polycarboxylate cements. More research is suggested to review retention however, before a specific material can be recommended for luting titanium alloy prefabricated posts. C!ONCLUSIONS This study supported earlier reports? that titanium alloy prefabricated posts and gutta-percha have similar radiopacity and that certain cements obscure the radiographic image oftitanium alloy prefabricated posts. This study also demonstrated that the radiopacity of cements is dependent

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on their thickness and density. Since minimal space for cement remains in an adequately prepared channel for a prefabricated post, luting agents advertised as radiopaque might not perform as expected because the radiopacity is due primarily to the post.

7. a. 9.

10.

REFERENCES 1. Restorative Dentistry Symposium.Memphis: University of Tennessee, College of Dentistry, October 28, 1988. 2. Wright WJ. Clinical observations of a titanium alloy prefabricated post. Compend Contin Dent Educ 1990;11:248-51. 3. DeSort KD. The prosthodontic use of endodontically treated teeth: theory and biomechanics of post preparation. J PROSTHETDENT 1983;49:203-06. 4. Goerig AC, Mueninghoff LA. Management of the endodontically treated tooth. Part I: concept for restorative designs. J PROSTHETDENT 1983;49:340-45. 5. Goerig AC, Mueninghoff LA. Management of the endodonticaly treated tooth. Part II: technique. J PROSTHETDENT 1983;49:491-97. 6. Tjan AHL, Whang SB. Retentive properties of some simplified dowelcore systems to cast gold dowel and core. J PROSTHETDENT 1983; 50:203-06.

anagement

for the highly

11. 12.

13.

Hunter AJ, Feiglin B, Williams JF. Effects of post placement on endodontically treated teeth. J PROSTHETDENT 1989;62:166-72. Wuehrmann AH, Manson-Hing LR. Dentai radiology. 3rd ed. St Louis: CV Mosby, 1973:44. Printed material (Form #512980 [4/89]) provided by L.D. Caulk Division, Dentspiy International, Inc. Milford: Del 19963.0359. Tjan AHL, Than AH, Grieve JH. Effects of various cementation methods on the retention of prefabricated posts. J PROSTHETDENT 1987; 58:309-13. Leary JM, Aquiline 54, &are CW. An evaluation of post length within the elastic limits of dentin. J PROXHET DENT 198’7;57:277-81. Radke RA, Barkhordar RA, Podesta RE. Retention of cast endodontic posts: comparison of cementing agents. J PROSTHETDENT 1938;59:31823. Maniatopoulos C, Pilliar RM, Smith DC. Evaluation of shearstrength at the cement-endodontic post interface. J PROSTHETDENT 1988; 59:662-69.

Reprint requeststo: DR. WILLIAM F. BOWLESIII ROOMS501 DUXN DENTAL BLDG. 875 UNION AVE. MEMPHIS,TN 38163

caries-susceptible

pati

Gonzalo I. Par-do, DDS,= and Leo M. Sreebny, DDS, MS, PhDb State University of New York at Stony Brook, School of Dental Medicine, Stony Brook, N.Y. Despite dramatic improvement in caries treatment during the past 30 years, a substantial number of patients remain highly susceptible and do not respond to conventional treatment. It is possible, using simple chairside caries-susceptibility tests, to identify the etiologic factors responsible for the disease and to design a rational approach to treatment that addresses the specific needs of the patient. (J PROSTIIET DENT 1992;67:637-44.)

Ithough the incidence of caries has diminished dramatically over the past 3 decades, a few highly susceptible individuals do not respond to conventional treatment. Unsuccessful treatment can often be attributed to treatment procedures that do not address the etiology of the disease. A common sequence for treating a patient with virulent caries consists of diagnosis, oral hygiene training, dietary counselling, fluoride therapy (both topical and self-applied), excavation of decay (with or without temporary stopping), restoration, and recall. Implicit in this approach is the assumption that the causes of dental caries will be successfully eliminated during treatment. This is presumptive and may explain treat-

aAssociate Professor, Department of Restorative Dentistry. bProfessor, Department of Oral Biology and Pathology. 16/l/35851

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ment failure in highly caries-susceptible patients. The perceptive dentist confirms with objective evidence that infection control has been achieved before assuming the caries is eradicated. The treatment regimen presented does not satisfy this criterion, but could with the addition of two elements: (1) preliminary tests to identify the factors contributing to the patient’s caries susceptibility and (2) follow-up tests to ensure that the etiologic factors are under control. This can be accomplished using tests recently developed in Europe. THE

TESTS

Five parameters have demonstrated a correlation to caries susceptibility: resting salivary flow rate, stimulated sal-

ivary flow rate, salivary buffer capacity, salivary lactobacillus count or, alternately, salivary streptococcus count and salivary yeast counts. The tests for all five parameters can be performed at chairside by a dentist or an auxiliary in approximately 20 minutes. The test data provide clues

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