Study of surface characteristics of natural teeth and restorations adjacent to gingivae

Study of surface characteristics of natural restorations adjacent to gingivae A. Volchansky, B.D.S.,* P. Cleaton-Jones, B.D.S., M.B., D. H. Retief, B.D.S., M.Sc.*** Dental Research Unit of the University of the Witwatemand South African Medical Research Council, Johannesburg,

teeth

B.Ch.,**

and

and

and South Africa

M

any types of restorative material are placed adjacent to or below the gingival margin. The surfaces of these restorations have been implicated as possible factors in the onset of gingival disease. Waerhaugh,lT 2 in studying the effect of restorative materials on the gingiva, noted inflammatory changes to all of them. He suggested that it was due to a chemical or bacterial irritation, not a mechanical one, and that overhanging edges were not a mechanical irritant but rather that the plaque that accumulated on the rough areas was the cause. The rough surface facilitated retention of bacterial plaque. L6e3 reported that roughness of restorations, probably more than chemical irritation, produced periodontal lesions. He concluded that one should not extend for prevention but that, if it is necessary to do so, restorations should be well polished. This view was also held by others.43 5 Karlsen6 placed supra- and subgingival gold crowns, porcelain crowns, and gold and acrylic resin inlays in dogs and monkeys. Gingival inflammation increased with poor fit and subgingival placement of the restorations. He found that the marginal fit was important. Silness? observed that bridge retainers seated below the gingival crest accumulated more plaque than did control teeth. He said that this was probably due to the plaque-retention properties of rough surface areas in the gingival crevice. Laratoss g recognized that roughened areas, including restorations, allowed for bacterial accumulation and, therefore, plaque deposition. This was particularly true when restorations had defective areas such as those caused by washing out of cements. *Periodontist and Honorary **Chief Research Officer. ***Professor and Director.

Research Assistant.

411

412

Volchansky,

Cleaton-Jones,

and Retief

Fig. 1. Points of assessments of the Talysurf profiles: u-b, ma1 peak-to-valley height; L, length of tracing used.

J. Pro&et. Dent. April, 1974

length of Talysurf

profile;

c-d,

L

Fig. 2. Scanning electron magnification X1,000.)

micrograph

of surface of enamel and Talysurf

profile.

(Original

Plaque has been studied with the light microscope using a variety of methods, but many technical problems, such as specimen preparation, existlo Boyde and Lester,ll Jones,12 and Newmani studied plaque using scanning electron microscopy (SEM) . JoneP also examined the tooth surface including plaque, calculus, cuticle, and cementurn. SEM was used by Conway and BaumhammerP and McLundie and Murray lG to investigate the surfaces and margins of restorative materials.

Volume Number

Fig. 3. x2,000.)

31 4

Surface

Surface

appearance

of

gold

characteristics

inlay

and

Talysurf

of

teeth

profile.

and

restorations

(Original

413

magnification

Another technique used in studying the surface of materials employs the various surface-roughness measuring instruments, and these were used, among others, by Volchansky,17 Valcke,l” Glantz and Larsson,19 and Fusayama and Yamane?O To date, no studies have been done using a combination of SEM and surface-roughness measuring instruments on restorations that have been in the mouth and in contact with the gingival margin for some time-hence the present investigation.

MATERIALS AND METHODS Sound and restored extracted human teeth, as well as several restorations, were used in this study. All specimens were washed in running water immediately after extraction, and the teeth were stored in a deep freeze at -4’ C. until needed. The teeth and restorations were reduced to a convenient size to fit the SEM mounting stubs using a Kent Mark II polishing machine.* They were then *Engis

Ltd.,

Maidstone,

England.

414

Volchansky,

Cleaton-Jones,

I0

.

J. Prosthet:

and Retie/

.

April,

Dent. 1974

, bYY?c,

Fig. 4. Surface of cementum and Talysurf profile. (Original

1000

magnification

~2,000.)

mounted on aluminum stubs using an alcohol colloidal graphite solution,* and then they were coated with gold-palladium in an Edwards Coating Unit.? The specimens were viewed in a Cambridge Stereoscan S4$ scanning electron microscope, in which the beam/specimen angle was varied to give the best visual field, and the results were recorded on Ilford Pan F 35 mm. film. Later, the same specimens were examined with a Taylor-Hobson Talysurf model 3s surface-roughness testing machine set on external datum and approximated to the general curvature of the specimen to keep the pen on the recording chart. The stylus pressure was 100 mg. throughout the study. enamel, cementum, amalgam, synthetic, The following surfaces were examined: gold inlay, porcelain-fused-to-gold, and calculus. The length of time that the restorations had been in the mouth was unknown, but none was present for less than one year. *DAG dispersion 580, Achesoa Colloids Ltd., England. tMode1 E12E4, Edwards Ltd., Crawley, Kent, England. SCambridge Scientific Instruments Ltd., Cambridge, England. §Rank Precision Industries, Leicester, England.

Volume

Number

31

Surface

4

I.. u

,

0

Fig. 5. Surface ~2,500.)

The following

of

silicate

specimens methods.

were

characteristics

of teeth

.

, .,

cement

restoration

graded

in

and

Talysurf

an order

Line-length

Peak C. The

maximum

in peaks

frequency peak-to-valley

index

II

profile.

per

=

millimeter

Length Length

height

L

peak

(mm.

in micrometers

magnification

roughness

an

opisometer,

surface

was

using

and

the

a line-

a-b L

of specimen

Total Length

(Original

of increasing

=

415

1000

w

1. Visual interpretation of scanning electron micrographs. 2. Visual interpretation of the Talysurf profiles. 3. Evaluation of the Talysurf profiles (Fig. 1) . A. The length of each Talysurf profile was measured using length index was calculated using the following formula:

B. The peak frequency the formula:

and restorations

determined

using

number

of specimen is shown

surface) by height

c-d in Fig.

1.

RESULTS ning

The surface appearances of the various specimens, as seen under the scanelectron microscope, together with a tracing of their Talysurf profiles are

416

Fig.

Volchansky,

6. Surface

Cleaton-Jones,

of porcelain

restoration

J. Ptosthet. Dent. April, 1974

and Retief

and Talysurf

profile.

(Original

magnification

~2: ,000.)

shown in Figs. 2 to 8. From the Talysurf profiles, the line-length index, number of peaks per millimeter, and maximum peak-to-valley height were determined and are listed in Table I. Enamel showed a slightly pitted but otherwise featureless surface (Fig. 2). The gold inlay had numerous surface depressions as well as a large number of scratches (Fig. 3). Cementum presented with many small elevations in an irregular cobblestone manner (Fig. 4). A few fine cracks due to shrinkage during dehydration were seen in other areas of the specimen. The silicate cement restoration had a surface comprising cracks and depressions, both large and small, as well as what appeared to be particles of the material projecting above the surface (Fig. 5). Porcelain consisted of flakes of material interspersed with both fine and large depressions (Fig. 6). The surface of the amalgam restoration was pitted and cracked with granules or debris sticking out of the surface (Fig. 7). Calculus presented large and small aggregations of material with valleys between them (Fig. 8). Table II shows the visual grading by decreasing roughness using the SEM results and Talysurf profiles, and it presents the three quantitative methods used. Enamel was the only specimen seen to be identical by grading with all four methods.

c

.

0

Fig.

7. Surface

of amalgam

Surface

characteristics

.

.

restoration

. and

of teeth

. w

and restorations

417

1000

Talysurf

profile.

(Original

magnification

~2,500.)

DISCUSSION The most important problem encountered in this study was the interpretation of the term roughness. The Concise Oxford DictionaryZ1 defines roughness as diversified or “an uneven or irregular surface, not smooth or level or polished, broken by prominences, hairy, shaggy, coarse in texture, or rugged.” Stedman’s Medical Dictionaryz2 calls roughness “that which is not smooth, denoting the irregular.” These are subjective terms, and an objective definition is required. Authors such as Fusayama and Yamane 20 have used a measuring instrument similar to the Talysurf which produces an objective profile tracing, and they then analyzed roughness using merely subjective evaluation. Unfortunately a quantitative expression of surface roughness in the form of a simple numerical index has not yet been formulated.* Two commonly used expressions in engineering are “center line average” (CLA) and “R,,, values,” both of which were used by Glantz and Larsson I9 in their laboratory study of the surface roughness of composite resins. *Duggan,

T. O’D.:

Personal

communication,

1973.

418

Volchansky,

Cleaton-Jones,

[I,. 0

J. Prosthet. Dent. April, 1974

and Retief

I,.

w

Fig. 8. Surface of calculus and Talysurf profile. (Original

1000

I

magnification

~2,200.)

The CLA has been defined as the numerical assessment of the average height of the irregularities constituting surface texture.23 The R,, value is an indication of the maximum peak height. This sounds straightforward, but it is unfortunately not so. The CLA value may only be used on planar surfaces or surfaces having a regular curvature (e.g., a ball bearing). Approximation of the measuring instrument to the irregular tooth and restoration surfaces, such as was investigated in this study, would not allow the use of the CLA value. value is also ideally applicable to laboratory specimens. Fig. 9 shows The IL, texture, the three components of surface texture. 23 In this, A represents the primary B is the secondary texture or waviness, while C is the error of form. In A, the R,,, value is height a-b. However, all profiles are a superimposition of A, B, and C (i.e., D). In D, a-c would be the R,,, value. This diagram also shows a regular secondary texture and error of form which are not evident on teeth and restorations. A specific mention of the R,,, value or of how the maximum peak-valley height measured in the present study is needed. The five simple assessments used in this investigation are all valid, we feel, but in spite of evaluating the same specimens with each method, five different orders of roughness were found, with enamel being the only constantly assessable surface.

Volume Numbet

31 4

Surface

characteristics

of

teeth

and

Fig. 9. The three types of surface texture are represented: A, primary secondary surface texture; C, error of form; D, combination of all three maximal peak height; a-c, apparent maximal peak-to-valley height.

restorations

419

surface texture; textures; u-b,

B, true

Table I Maximum valley

Line-length index

Specimen Enamel Porcelain Cementum Gold inlay Calculus Amalgam Silicate cement

Peaks/mm.

1.2 1.3 1.4 2.1 3.0 3.3 3.4

peak-toheight (Pm)

3 8 10 20 17 18 19

2.2 8.0 3.8 15.0 15.9 14.3 17.0

Table II Talysurf Order of increasing roughness 1 2 3 4 5 6 7

SEM (visual) Enamel Gold inlay Cementum Silicate cement Porcelain Amalgam Calculus

Visual Enamel Porcelain Cementum Gold inlay Silicate cement Amalgam Calculus

surface-roughness

Line-length index Enamel Porcelain Cementum Gold inlay Calculus Amalgam Silicate cement

recordings

Peak/mm. Enamel Porcelain Cementum Calculus Amalgam Silicate cement Gold inlay

Maximum peak-to-valley height Enamel Cementum Porcelain Amalgam Gold inlay Calculus Silicate cement

CONCLUSIONS The conclusions from this study follow. 1. While a generally acceptable definition of roughness to suit all scientific disciplines will never be possible, a definition for the assessment of surfaces for dental purposes is required. 2. Standard methods of quantitative assessment of roughness are needed.

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Cleaton- Jones,

and Retief

J. Prosthet: Dent. April, 1974

3. Koughness studies should be carried out not only on laboratory specimens but also on surfacesand restorations that have been present in the oral environment for various lengths of time. 4. Enamel is probably the smoothest and most acceptable surface in the mouth, and all natural and restored surfaces should be compared to it. 5. A correlation of roughness, degree of plaque formation, and gingival irritation should be determined. We gratefully acknowledge the assistance of Mr. T. O’D. Duggan of the School of Mechanical Engineering, Mr. R. F. Rawiel of the Department of Surveying, and the staff of the Electron Microscope Unit of the University of the Witwatersrand, and we thank Miss B. Slack for her accurate typing.

References 1. 2. 3. 4. 5.

6. 7. 8. 9. 10.

11. 12. 13. 14. 15. 16. 17.

18.

Waerhaug, J.: Effect of Rough Surfaces Upon Gingival Tissue, J. Dent. Res. 35: 323-325, 1956. Waerhaug, J.: Effect of Zinc Phosphate Cement Fillings on Gingival Tissues, J. Periodontol. 27: 284-290, 1956. Lije, H.: Reactions of Marginal Periodontal Tissues to Restorative Procedures, Int. Dent. J. 18: 759-778, 1968. Berman, M. H.: The Complete Coverage Restoration and the Gingival Sulcus, J. PROSTHET. DENT. 29: 301-309, 1973. Swedlow, D. B., Kopel, H. M., Grenoble, D. E., and Katz, J. L.: Dental Amalgam Polishing With Discs as Observed by Scanning Electron Microscopy, J. PROSTHET. DENT. 27: 536-543, 1972. Karlsen, K.: Gingival Reactions to Dental Restorations, Acta Odontol. Stand. 28: 895904, 1970. Silness, J.: Periodontal Conditions in Patients Treated With Dental Bridges, J, Periodont. Res. 5: 219-224, 1970. Larato, D. C.: Influence of Silicate Cement Restorations on Gingiva, J. PROSTHET. DENT 26: 186-188, 1971. Larato, D. C.: Influence of a Composite Resin Restoration on the Gingiva, J. PROSTHET. DENT. 28: 402-404, 1972. Schroeder, H. E., and De Boever, J.: The Structure of Microbial Dental Plaque, in McHugh, W. D., editor: Dental Plaque, Edinburgh, 1970, E. & S. Livingstone, Ltd., pp. 17-26. Boyde, A., and Lester, K. S.: Scanning Electron Microscopy of Carious Cavity Plaque After Ethylene Diamine Treatment, Arch. Oral Biol. 13: 1413-1419, 1968. Jones, S. J.: Natural Plaque on Tooth Surfaces, Apex 5: 93-98, 1971. Newman, H. N.: Structure of Approximal Human Dental Plaque as Observed by Scanning Electron Microscopy, Arch. Oral Biol. 17: 1445-1453, 1972. Jones, S. J.: The Tooth Surface in Periodontal Disease, Dent. Pratt. Dent. Rec. 22: 462473, 1972. A.: Scanning Electron Microscopic Examination of Conway, J. C., and Baumhammers, Surfaces and Margins of Restorations, J. PROSTHET. DENT. 27: 622-631, 1972. McLundie, A. C., and Murray, F. D.: Silicate Cements and Composite Resins. A Scanning Electron Microscope Study, J. PROSTHET. DENT. 27: 544-551, 1972. Volchansky, A.: A Comparative Study of Natural and Restored Surfaces of Teeth Adjacent to the Gingival Margin, J. Dent. Res. 52: 609, 1972. (Int. Assoc. Dent. Res. Abst.) Valcke, C. F.: Polishing Porcelain. A Note on New Rotatory Abrasive Tools, J. Dent. Assoc. S. Afr. 28: 278-280, 1973.

Volume 31 Numhrt 4 19. 20. 21. 22. 23.

Surface

Glantz, P-O., and Lawson, After Finishing, Acta Odontol. Fusayama, T., and Yamane, ing Techniques, J. PROSTHET. The Concise Oxford Dictionary, Stedman’s Medical Dictionary, pany, p. 1315. British Standard 1134, 1961,

characteristics

of teeth

and

restorations

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L-A.: Surface Roughness of Composite Resins Before and &and. 30: 335-347, 1972. M.: Surface Roughness of Castings Made by Various CastDENT. 29: 529-535, 1973. ed. 5, London, 1969, Oxford University Press, p. 1088. 1961, The Williams & Wilkins Comed. 20, Baltimore, Her

UNIVERSITY OF THE WITWATERSRAND JAN SMUTS AVE. JOHANNESBURG, SOUTH AFRICA

Majesty’s

Stationery

Office,

pp.

8-13.