Periodontal considerations in operative dentistry

Fixed prosthodontics and operative dentistry

Periodontal

considerations

in

James G. Burch, D.D.S., M.Sc.* University of Kentucky, College

M

uch restoration (2)

to

attention has ( 1) to prevent

allow

a patient

Much attention restorations.+” to finish, tours of

has All

to

more

Dentistry,

of

dentistry

Le.xington,

to the development caries and plaque

effectively

also been given restorative dentistry

with a total restorations patient

been given recurrent

operative

remove

Ky.

of adequate collection and dental

to the development procedures should

plaque

allow

the

This concept is related for the periodontium

to cleanse

the to and

tooth (1) (2)

surfaces

to prevent

restorations restorations

caries

which which

from

of a and

the

area.lm3

of the occlusal anatomy be carried out, from

preventive concept in mind.’ This article and associated periodontal considerations.

eases. ment

margins retention

of start

discusses coronal The restorations and

conwill

periodontal

dis-

establish a favorable environcan easily be cleansed by the

patient.

PROXIMAL In

SURFACES

viewing

the

proximal

surfaces

of

thirds of the tooth is either flat or slightly and the cement-enamel junction.” There as occlusoapically. sectioning buccolingual

at

A

group

the level concavity

the buccolingual concavity, comprehend what happens of, for instance, a second the concavity is untouched removed. surface

of

of or

of

teeth

premolar by the

may

156

(Fig.

be set adjacent

to each

of the proximal floss is stretched

tooth. As floss. Thus,

dental plaque

surfaces across floss in

Occlusion.

the

cervical

other

two

surface. Even which should evicted

from

after

to clean requires

one can surface

the depth may not

of be

the proximal a curette

or

with these be reproduced the

cross-

characteristic Envisioning

of the teeth, the proximal

is tightened, the concavity

Use of a special instrument or brush becomes necessary this type of root. r”, I1 Adequate root curettage also

of

1))

junction (Fig. 2). The proximal surface is apparent.

scaler which conforms to the shape of that tooth tions in mind, it is the form of the natural tooth ceptance by the adjacent periodontal tissues. Often, a papilla of the gingiva is mechanically *Director

tooth

concave between the proximal contact area is a relative flatness buccolingually as well

the cement-enamel flatness of the or flatness, when dental

a natural

embrasure

considerafor acdue

to

Periodontal

considerations

Fig. 1. Buccal view of a mandibular premolar illustrating clusoapically between the contact and the cement-enamel Fig. 2. An occlusal junction, presenting

cross-sectional view the buccolingually

of mandibular flat or slightly

in operative

a flat or slightly junction. teeth at the level concave proximal

Fig. 3. A buccal view of a crown presenting with a convex tact and cervical areas. The facial papilla has been evicted probe is in the pocket.

dentistry

concave

surface

157

OC-

of the cement-enamel surfaces.

proximal surface between the confrom the embrasure. A periodontal

overcontouring of the proximal surface of a restoration (Fig. 3). A periodontal pocket may form with rolled, red, and inflamed gingiva. This pathologic gingival architecture can be correlated with the improperly developed proximal surface convexity and should be prevented.” Upon seating of a proximally overcontoured restoration, mechanical impingement of the gingival papillae and vulnerable gingival ~01 may occur, and a chronic food trap results. Due to the violation of proximal contours followed by development of a pathologic gingiva, it is more difficult for a patient to readily cleanse the area. The gingival co1 area (Fig. 4) has a very thin protective epithelial covering.*” Even in good health, the co1 is vulnerable to attack. The epithelial covering of the co1 can be readily disrupted. The bacterial toxins and enzymes easily attack the connective tissue, and pathosis results. A flat or slightly concave proximal contour, buccolingually as well as occlusoapically, should be created in a restoration. This environment is conducive to tissue integrity and the least bacterial retention and allows the patient to readily cleanse the area. These same characteristic proximal contours should be developed next to the gingiva near a solder joint in a fixed partial denture to prevent encroachment of the embrasure and impingement of the tissues (Fig. 5). Fig. 6 demonstrates the proximal surfaces of three well-formed wax patterns. The proximal contact points have been kept in the occlusal third. The proximal surfaces present a flatness or a slight concavity occlusoapically as well as buccolingually, and the margins are well fitted and smooth. Once the replicated gingival tissues have been removed in trimming the die to allow proper waxing, one can no longer consult the gingival areas of the dies to determine coronal contours. Therefore, one must

158

J. l’rosthet. Aupst.

Burch

Fig. 4, A proximal histologic view of a posterior gingival co1 area: C, proximal E, thin epithelial covering; CT, connective tissue; and B, bone.

Drnt. 1975

contact area;

aim for the development of proximal contours which are slightly concave or flat buccolingually and occlusoapically. Occasionally, in fabricating the distal surface of a maxillary first molar restoration, a very slight convexity of that distal surface may be acceptable.14 BUCCAL

AND

LINGUAL

SURFACES

In the past, much consideration had been given to the belief that, during chewing, food passes over both the buccal and lingual surfaces of the teeth onto the marginal gingivae. I5 Dentists at that time, felt it necessary to protect the marginal gingivae from the active passage of food during mastication. They advocated the development of a cervical bulge on the lingual and buccal surfaces of a restoration. Subsequent studies have shown that food does not pass directly to the marginal gingival tissues during mastication. I6 If food is allowed to lie within the gingival sulcus, the bacteria will live, eat, and proliferate in this stagnant environment, producing toxins and enzymes which attack the gingival tissues, and cause periodontal pathoses. Currently, restorations are described which contain contours to prevent debris and plaque retention and which are more easily cleansed.17 Therefore, the protective bulge is no longer desirable.17 The facial height of contour of all teeth appears in the cervical third of the crown (Fig. 7) .6, I4 The lingual height of contour, or crest of convexity, usually appears in the cervical third of the crown. Lower molars and premolars may present a lingual height of contour which is located further occlusally (Fig. 7) . The greatest buccolingual dimension of the crown of most teeth is no greater than 1 mm. larger than the buccolingual dimension of the tooth at the cement-enamel junction, except in lower molars and premolars with larger lingual curvatures.l4,~ Occasionally, a patient shows an apparent lack of facial convexity on broken and abraded teeth (Fig. 8). It is apparent that the facial convexities have been missingfor a number of years. Upon periodontal examination, there were no sulcus depths ex-

Volume Numbrr

Fig.

34 2

5. A lingual

Periodontal

view

of a fixed

splint

considerations

on which

Fig. 6. A lingual view of three well-contoured the gingival tissue has been removed. Fig. 7. A proximal view of a mandibular vatures and the normal heights of contour:

long wax

solder crown

in operative

joints patterns

occur

159

interproximally.

on dies from

molar exhibiting the gentle B, buccal; L, lingual.

dentistry

buccal

which and

much

lingual

of cur-

ceeding 2 mm. and no bleeding points. A knife-edge, stippled, pink, marginal gingiva was observed. Patients presenting these features have little need of protection for the gingiva through creation of sizable cervical convexities. Other patients present restorations with good contours but with enlarged buccolingual dimensions (Fig. 9). This violation of tooth contour should be prevented. The points to emphasize are: ( 1) in their greatest buccolingual dimension, restorations should be no more than 1 mm. larger than the die at the approximate cement-enamal junction, (2) the facial or lingual crest of contour should not extend more than 0.5 mm., buccally or lingually, beyond the cement-enamel junction, and (3) the slight convexity should be gradual and in the cervical third of the tooth. These features allow less food entrapment and allow the patient access to the sulcus and tooth surface for cleansing. Facial and lingual restorations are to be restored accordingly. LINE ANGLES The axial line angles of a tooth are the mesiobuccal, distobuccal, distolingual, and mesiolingual ones. The four line angles of individual teeth are straight between the proximal contact area and the cement-enamel junction.” The labial line angles of the maxillary incisors and the lingual line angles of the maxillary molars may be slightly convex. There is a strong tendency to violate the principle of the straight line angle in developing a restoration by making the line angles somewhat convex, leading to gingival impingement and plaque retention adjacent to the corners of the teeth. The photograph of a gold casting (Fig. 10) sh ows line-angle areas which are not straight from the proximal contact area to the cement-enamel junction. This bulk of gold should be reduced from the restoration to attain straight line-angle areas.

160

J. Yrosthet. Dent. August, 1975

Burch

Fig. 8. A buccal abraded

teeth

Fig. 9. An premolar,

view of the of long standing.

mandibular dentition There is no evidence

occlusal view of a porcelain-fused-to-gold which is much too large in the buccolingual

of a 73-year-old of any protective crown on the dimension.

Fig. 10. A three-unit fixed bridge. Arrows indicate erroneous Fig. 11. A buccal view of a maxillary second molar plunger dibular

marginal

PROXIMAL

ridges.

There

has been

a loss of proximal

convex cusp with contact.

man with broken facial contour. mandibular

line

and

left

second

opposing

man-

angles.

missing

INTEGRITY

Plunger cusps (Fig. 11) actively pass food into the embrasure areas and destroy periodontal integrity. I9 Of more importance is the proximal retention of food which encourages bacterial growth and tissue destruction. Absence of secure proximal contact and unequal heights of marginal ridges lend themselves to food retention. One should: (1) p ro d uce definite marginal ridges, (2) create equal heights of adjacent marginal ridges, (3) reshape plunger-type cusps, (4) develop occlusal contours to allow escape of food from the embrasure, and (5) establish proximal contact to preserve arch stability. Proximal contacts should be buccal to the buccolingual centers of the teeth, therefore creating an embrasure that is longer and broader lingually than buccally (Fig. 12) .O, I4 From a facial or a lingual view, the proximal contact areas should be in the occlusal third of the adjacent teeth. A proximal contact between the distal surface of the maxillary first molar and second molar may occasionally be adequately located in the middle third of the crown both from an occlusal view and a buccal view. The restoration should not, however, encroach upon the embrasure or proximal gingiva.

Periodontal

considerations

in operative

Fig. 12. An occlusolingual view to the buccolingual centers of

of two premolars presenting proximal the teeth and in the occlusal third

Fig. 13. Mesial to the attachment. The probe tact.

canine periodontal

Fig. 14. A view marginal gingiva

mandibular indicates

of a periodontal probe buccal to the mandibular

Fig. 15. An incisal view of a crown prepared by use of an electrosurgical

LOST

PROXIMAL

CONTACT

preparation technique

a narrow

around which the for impression making.

161

contact areas occlusocervically.

is a diastema with a clinically pocket depth associated with

being used to confirm first premolar.

dentistry

healthy a slight

zone gingival

buccal

periodontal loss of con-

of attachment sulcus

of

has been

OR DIASTEMA

Of greater concern than a diastema is a slight loss of proximal c0ntact.r” There is a greater propensity for food retention in an area of slight loss of proximal contact than in a proximal area of a diastema (Fig. 13). If no mobility or trauma is apparent in the teeth adjacent to a diastema, one can often accept the arch integrity that exists and not create an unsightly, food-and-plaque-retaining restoration in order to close a diastema. The soft tissues of a diastema area are tough like those of masticatory mucosa, which are well keratinized, more easily cleansed, and less vulnerable to breakdown than the co1 area associated with a slight loss of proximal contact (Fig. 13). ATTACHED

GINGIVA

attached gingiva. If the facial Much controversy exists as to what is ‘Ladequate” surface of the first premolar tooth (Fig. 14) is not to be restored, any amount of attached gingiva would be adequate as long as it is attached. If a restoration is to be placed with the margin above the gingiva, any small amount of attachment is ade-

162

J. Prosthet. Dent. August, 1975

Burch

quate as long as it is not impinged upon during the technical procedure. If the margin of a restoration must be placed in the gingival sulcus, 2 mm. or more of attached gingiva, cervical to the margin of the restoration, should be attained. Margins of restorations should be maintained supragingivally unless there is a definite indication for subgingival placement. Some reasons are ( 1) to develop crown length for retention of the restoration, (2) to esthetically hide the margin, (3) to replace a cervical restoration, or (4) to restore areas of root caries or root sensitivity.z0l ‘l Finishing restorations at a supragingival position prevents tissue trauma during technical procedures and prevents surface retention of plaque in the sulcus, as occurs with subgingival restorations2” ELECTROSURGICAL

RETRACTION

An electrosurgical technique for gingival retraction should be considered prior to impression making. A small, trough-like sulcus should be created in the gingival sulcus at the margin of the preparation (Fig. 15). This need be only large enough to place impression material at the margin of the preparation.23 A straight tip can be used for this purpose. One should not remove or recontour tissues at this time. A small portion of the free marginal gingiva may be removed along with most of the epithelial lining of the sulcus. Avoid complete removal of the attached gingiva at any point around the tooth. 24 The tip of the electrosurgical instrument should never touch the alveolar bone, DISTANCE

FROM

ALVEOLAR

CREST

No restoration should be placed with a margin less than 1.5 mm. from the alveolar crest of bone, interproximally, buccally, or lingually. The periodontium, whether healthy or diseased, re-establishes a so-called “biologic width” between the bottom of and uncontrolled bone loss the sulcus and the alveolar bone. 25 To avoid inadvertent of the alveolar housing, one should retain at least 1.5 mm. of tissue attachment between the alveolar crest and the margin of a restoration. If this is not possible, a crown-lengthening periodontal surgical procedure is indicated. SUMMARY Periodontal and preventive considerations, other than marginal fit and occlusion, are discussed as they relate to the fabrication of restorations in operative dentistry. The development of buccal, lingual, proximal, and transitional line contours is presented as related to maintenance of healthy periodontal tissues. Proximal contacts and marginal ridge relationships are related to food retention and arch integrity. The gingival attachment is described, as it determines certain techniques of tooth preparation and impression making. References 1.

Thomas, B. Periodontal 2. Wright, W. 3. Gilmore, N., J. Periodontol

0. A. : The Relationship of Operative Procedures Tissues, J. Am. Dent. Assoc. 39: 522-532, 1949. H.: Local Factors in Periodontal Disease, Periodontics and Sheiham, A.: Overhanging Dental Restorations 42: 8-12, 1971.

to the

Health

1: 163, 1963. and Periodontal

of

the

Disease,

Volume 34 Numbrr 2 4. 5.

6.

7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24.

25.

Periodontal

considerations

in operative

dentistry

163

Stuart, C. E., and Stallard, H.: Oral Rehabilitation and Occlusion, San Francisco, 1959. University of California. Thomas, P. K.: Full Mouth Waxing Technique for Rehabilitation Tooth-to-Tooth CuspFossa Concept of Organic Occlusion, Syllabus, San Francisco, 1967, University of California. Amsterdam, M., and Abrams, L.: Periodontal Prosthesis, in Goldman, H. M., and Cohen, D. W.: Periodontal Therapy, ed. 5, St. Louis, 1973, The C. V. Mosby Company, pp. 9771013. Part I, J. PROSTHET. DENT. 10: Mann, A. W., and Pankey, L. D.: Oral Rehabilitation, 135-150, 1960. Lundeen, H. C.: Introduction to Occlusal Anatomy, Gainesville, 1970, University of Florida. Barkley, R. F.: A Preventive Philosophy of Restorative Dentistry, Dent. Clin. North Am. 15: 569-575, 1971. Glickman, I.: Clinical Periodontology, ed. 4, Philadelphia, 1972, W. B. Saunders Company, p. 464. Burns, R. L.: A New Approach to Interproximal Hygiene, Dent. Surv. 43: 77-80, 1967. Prichard, J. F.: Advanced Periodontal Disease: Surgical and Prosthetic Management, Philadelphia, 1965, W. B. Saunders Company, p. 12. Glickman, I.: Clinical Periodontology, ed. 4, Philadelphia, 1972, W. B. Saunders Company, p. 8. Kraus, B. S., Jordan, R. E., and Abrams, L. A.: Dental Anatomy and Occlusion, Baltimore, 1969, The Williams & Wilkins Company, pp. 245-263. Wheeler, R. C.: A Textbook of Dental Anatomy and Physiology, Philadelphia, 1965, W. B. Saunders Company, pp. 95-123. Wilcox, C. E., and Everett, F. G.: Friction of the Teeth and the Gingiva During Mastication, J. Am. Dent. Assoc. 66: 513-520, 1963. Perel, M. L.: Axial Crown Contours, J. PROSTKET. DENT. 25: 642-649, 1971. Wheeler, R. C.: A Textbook of Dental Anatomy and Physiology, ed. 4, Philadelphia, 1965, W. B. Saunders Company, p. 13. Hirschfeld, I.: Food Impaction, J. Am. Dent. Assoc. 17: 1504-1528, 1930. Larato, D. C.: Effect of Cervical Margins on Gingiva, J. Calif. Dent. Assoc. 45: 19-22, 1969. Burch, J. G.: Ten Rules for Developing Crown Contours in Restorations, Dent. Clin. North Am. 15: 611-618, 1971. Loe, H.: Reactions of Marginal Periodontal Tissues to Restorative Procedures, Int. Dent. J. 18: 759-778, 1968. Podshadley, A. G., and Lundeen, H. C.: Electrosurgical Procedures in Crown and Bridge Restorations, J. Am. Dent. Assoc. 77: 1321-1326, 1968. Glickman, I., and Imber, L. R.: Comparison of Gingival Resection With Electrosurgery and Periodontal Knives-A Biometric and Histologic Study, J. Periodontol 41: 142-148, 1970. Gargiulo, A. W., Wentz, F. M., and Orban, B. 0.: Dimensions and Relations of the Dentogingival Junction in Humans, J. Periodontol 32: 261-268, 1961. UNIVERSITY OF KENTUCKY COLLEGE OF DENTISTRY LEXINGTON, KY. 40506