A comparison of cord gingival displacement with the gingitage technique

A comparison of cord gingival gingitage technique

displacement

with the

Robert G. Tupac, D. D.S.,” and Kit Neacy, D.D. S. * University of California, School of Dentistry, Los Angeles, Calif.

F

ixed prosthodontic procedures requiring tooth preparation below the level of the free gingival margin (within the gingival sulcus) must be accompanied by gingival displacement to accurately record the prepared tooth margin during impression making. “Gingitage” involves simultaneous subgingival tooth preparation and intentional rotary diamond instrument curettage of the inner lining of the gingival sulcus. The definitive tissue removal allows room for placement of retraction cord and insertion of impression materials. This technique has been described in the literature for removal of healthy or inflamed gingival tissue during tooth preparation. However, in the past 6 years, it has been popularized in clinical circles, with a special set of diamond instruments produced for this purpose. To date, no clinical or histologic evidence has been presented in the literature to compare the use of the diamond instrument gingitage with routine cord gingival displacement procedures. The purpose of this study was to determine whether there is a significant difference between cord gingival displacement and the gingitage technique, using a canine model. LITERATURE

REVIEW

Historically, gingival retraction or displacement has been achieved by mechanical, chemical, or electrosurgical means. Numerous articles have reported the effectiveness of. procedures involving

gingival displacement and gingival sulcular removal for making retractions.l~‘O* Anneroth and Nordenram’l presented guidelines for insertion and removal of cord to prevent injury to the sulcular lining. Electrosurgical methods use an electrical current, in a “troughing” procedure, to remove the lining of the gingival sulcus. This was introduced by Strock” and shown by Klug13 to result in a loss of only 0.1 mm of gingival height. Malone and ManningI and Podshadley and Lundeen15 have demonstrated that electrosurgery is safe for gingival retraction if properly used. Rotary curettage has been described for use in conjunction with tooth preparation and has also been used for sulcular tissue removal without accompanying tooth preparation. Moskow’G concluded that gingival curettage done with a rotary diamond instrument removed pocket epithelium in five out of six patients treated. Gingitage or rotary gingival curettage, promoted as a method for handling the interfering tissue during restorative procedures, is intended to eliminate the trauma of pressure packing or the necessity of electrosurgery around subgingival tooth preparations. A series of diamond instruments of special shape and grit allows the crevicular epithelium to be removed at the same time the preparation finish line is completed. Increased impression material volume is allowed in the finish line areas. Emphasis is placed on nonpressure retraction cord insertion.‘? MATERIAL

This project was supported by BRSG Grant RR05304, awarded by the Biomedical Research Support Grant Program, DRR, National Institutes of Health. Presented at the Pacific Coast Society of Pmsthodontists, Monterey, Calif. *Lecturer, Division of Hospital Dentistry, Department of Maxillofacial Prosthetics.

0022-3913/81/110509

+ 07foo.70/00

1981 Tbe C. V. Mosby

Co.

AND

METHODS

Fifteen young adult mongrel dogs weighing 20 to 25 kg were obtained 7 days prior to the start of the experimental period. The dogs were sedated with 1 to 2 cc of Innovar (fentanyl droperidol 2.55 mg dose/cc) and the caries-free canine teeth were scaled *Koper,

A.: Personal

communication,

THE JOURNAL

1974.

OF PROSTHETIC

DENTISTFtY

SO9

TUPAC

AND

NEACY

Fig. 1. Diagram of measurement of distance from reference point to gingival crest (RC) and from reference point to sulcular depth (RD).

Fig. 3. Clinical appearance lowing gingitage.

0A

0B

0C

Fig. 2. A, One millimeter deep shoulder prepared at height of free gingival margin. B, Gingitage. C, Beveled shoulder and sulcular area following gingitage. with curettes and polished using a rotating rubber cup with medium-grit pumice. Following the initial prophylaxis, a 0.2% chlorhexidine solution was swabbed on the experimental teeth three times weekly for the duration of the experiment.18-z1 The dogs were divided into three groups of five animals per experimental time period. After the week of initial preparations, the techniques were performed and compared at 0, 7, and 21 days for groups 1 to 3, respectively. On day 0, the dogs were anesthetized with intravenous phenobarbital sodium 60 mg dose/cc given

510

of experimental

region

fol-

30 mg/kg, and an endotracheal tube was placed. At this time, some of the parameters of comparison of the techniques were measured. Periodontal evaluation of the gingiva in the experimental area was made using the plaque index and gingival index.2” In addition, crevicular fluid vo1ume23-Z6 was measured with a Periotron (Harco Electronics Ltd., Winnipeg, Canada), according to the manufacturer’s instructions.” All clinical measurements were made by one investigator (K. N.). Reference points, made with a No. 34 inverted cone bur in the middle third of the labial surfaces of the experimental teeth, were filled with amalgam. A Michigan 0 probe calibrated at 1 to 9 mm was used to measure the distance from the reference point to the gingival crest [R-C) and from the reference point to the depth of the gingival sulcus (R-D) (Fig. 1). Adhesive markers placed on the probe allowed computation to be made with a Boley gauge. A periodontal probe was placed into a needlepoint hole made in the gingiva at the level of the sulcular depth to measure the tissue thickness.

NOVEMBER

1981

VOLUME

46

NUMBER

5

CORD

DISPLACEMENT

VERSUS

GINGITAGE

Table I. Raw data (mean Group

Time

(days)

1

0

2

0

Technique

0

21

k Indicates

standard

error

Table II. Technique

1

2 3

GI

0.5 C 0.22 0.6 + 0.24 0.8 f 0.2 Ok0 0.2 -+ 0.2 0.2 t 0.2 0.3 k 0.12 1.6 f 0.6 1.2 k 0.48 0.5 +- 0.22 0.6 + 0.24 0.2 t 0.2 0.5 + 0.22 0.8 z!z 0.37 0.8 k 0.37

0.6 0.8 0.8 0.8 1.0 0.4 0.7 1.2 1.4 0.9 0.6 0.4 0.7 1.4 1.2

technique

G*

f t + zk -t It k f t +k + f i f

CF 0.29 0.37 0.48 0.25 0.31 0.24 0.25 0.37 0.4 0.4 0.4 0.4 0.25 0.4 0.37

R versus

f 5.87 t 3.31 f 7.52 + 0.38 f 3.08 f 2.68 f 2.42 + 4.06 k 2.44 -c 1.77 f 1.19 1+_1.65 t 1.5 f 8.39 k 3.35

5.05 4.54 5.2 4.6 4.8 4.8 4.8 4.7 4.6 3.57 4.14 3.66 3.59 4.3 3.7

k 0.26 f 0.87 -c 0.48 t 0.48 2~ 0.37 + 0.2 +- 0.33 r 0.3 +- 0.24 + 0.29 +- 0.28 f 0.52 r 0.22 k 0.39 j; 0.44

of differences

7.74 7.26 7.96 6.9 6.8 6.9 7 7.2 8 6.18 7.08 6.36 6.19 7.16 6.94

RD-RC(mm)

?I 0.81 z!r 1.24 + 0.47 -+ 0.33 t 0.37 f 0.24 ?z 0.27 3~ 0.2 i 0.54 -c 0.33 " 0.43 f 0.45 + 0.55 f 0.5 f 0.5

2.69 2.72 2.76 2.3 2 2.1 2.2 2.5 2.4 2.61 2.94 2.7 2.6 2.86 3.24

GI

CF

RC

RD

T

0.67 0.587 1

0.262 0.749 0.374

0.414 0.765 0.121

0.794 0.838 0.277

0.927 0.242 0.771

0.082 N/At N/At

difference

between

R and

G at 0, 7, and

Group 1 2 3 21

R” versus

p values

f-test

Tbm) 1-1-o l&O 0.9 f 0.1 0.9 f 0.06 If0 0.8 +- 0.12 -

1.03 f 0.06 1+0 If0 -

-

controlt

of differences

PI

GI

CF

RC

RD

T

0.217 0.098 0.468

0.836 0.142 0.108

0.154 0.055 0.076

0.763 0.838 0.216

0.803 0.587 0.342

0.429 N/AS N/AS

*R greater than control but not significant. tNo significant difference between R and control

at 0, 7, and 21

days.

$Not

Random selection was used to determine the experimental and control teeth. Each dog had four canine teeth studied-one with retraction cord, one with gingitage, and two as controls. Using a highspeed handpiece with a straight No. 557 fissure bur, a shoulder was prepared from the mesiolabial line angle to distolabial line angle 1 mm in depth at the height of the free gingival margin (Fig. 2, A). For half of the experimkntal teeth, a Pascord No. 9 retraction cord was placed into the gingival sulcus using a plastic instrument with light pressure. The prepared shoulder was then beveled to approximately half the depth of the gingival sulcus without tissue laceration (technique R-retraction cord). For the other experimental teeth, the prepared shoulder was beveled to approximately half the depth of the gingival sulcus with simultaneous removal of the sulcular tissue (technique G-gingitage) (Fig. 2, B and C). The Pascord No. 9 retraction cord was then placed into the gingival sulcus without pressure using a plastic instrument. The cord remained in the gingival sulcus for 5 minutes before removal for all experimental

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RD(mm)

Table III. Technique

PI

*No significant days. t Not available.

13.57 6.82 13 7.99 7.26 6.6 10.45 17.08 16 5.66 3.52 4.22 5.4 23.28 11.18

RC(mm)

of the mean.

f-test p values Group

PI

C R G C R G C R G C R G C R G

7

3

values)

OF PROSTHETIC

DENTISTRY

available.

Table IV. Technique

p values

f-test

Group 1 2 3

G versus

controlt

of differences

PI

GI

CF

RC

RD

T

0.653 0.105 0.468

0.169 0.108 0.298

0.402 0.02 0.047

0.599 0.688 0.790

0.643 0.2 0.311

0.261 N/AS N/AS

*G greater than control but not significant. ~No significant difference between G and control days. $Not available.

at 0, 7, and 21

teeth. Reversible hydrocolloid impressions were then made using stock metal trays. The prepared shoulder was undercut to allow placement of amalgam to restore the natural contour of the labial surface and to simulate a provisional restoration ((Fig. 3). Tooth preparation, tissue retraction, impression making and provisional restorations were again performed by a single investigator (R. T.). At this time, group 1 dogs were killed with an overdose of intravenous

511

TUPAC

Table V. Technique f-test Difference

R versus

p values

corrected

technique

Table VII. Technique

G*

for time Ot

f-test

PI

GI

CF

RC

RD

0.648

0.242

0.47

0.815

0.08

0.178

1.000

0.146

0.679

0.412

1 week-

time 0 3 weekstime 0

*R venus G (both corrected for time 0 level) cant. tChange in scores from time 0 to 3 weeks.

are not signili-

Difference 1 weektime 0 3 weekstime 0

t-test Difference 1 weektime 0 3 weekstime 0

PI

p values

R versus corrected GI

control*

CF

RC

0.207

0.468

0.013

0.468

0.426

0.688

0.011

0.071

0.735

0.926

*Change in R from time 0 to 1 week is no more significant change in control from time 0 to 1 week.

than

pentobarbital sodium; groups 2 and 3 were returned to their cages to be maintained on a hard diet with water available at all times, until the determined time of sacrifice. At the time of sacrifice the clinical measurements were repeated and recorded. Following sacrifice, block sections of the maxilla and mandible were removed with a Stryker saw and fixed in 10% formalin. After fixation, the specimens were decalcified in formic acid/sodium citrate, cut into small blocks, embedded in paraffin, and cut into sections six p thick. The sections were stained with Harris’ hematoxylin and eosin.

RESULTS Clinical The experimental regions were clinically healthy at time 0. Table I gives the mean plaque index scores, gingival index scores, and crevicular fluid measurements. For all groups at time 0, mean plaque index scores were not greater than 1. Mean crevicular fluid measurements for all groups at time 0 were in a range attributable to tissue health. Over all, the baseline level of clinical tissue health was maintained for the control teeth in groups 2 and 3 throughout the course of the experiment. In some instances, the experimental teeth showed a slight increase in inflammation. The mean baseline s&us depths

512

corrected

for time 0

PI

GI

CF

RC

RD

0.052

0.011

0.267

0.374

0.061

0.235

0.116

0.111

Cl.916

0.378

Histologic

Group RD

control*

p values

results

Sulcus

for time 0

G versus

NEACY

*Change in G from time 0 to 1 week and from time 0 to 3 weeks is not significant when corrected for time 0.

Table VIII. Table VI. Technique

AND

1

2 3 Tissue thickness

(mean)

depth

(RD-RC)

(raw

data)

(mm)

C

R

G

2.9 2.85 2.92

2.74 2.15 2.75

2.24 2.49 3.61

= 1.59 mm.

(RD-RC) were also clinically consistent for the control teeth in groups 2 and 3. Mean s&us depths for the experimental teeth in these groups showed a slight increase. Postoperative RC measurements in groups 2 and 3 showed that no gingival recession occurred as a result of the procedure. Tissue thickness at time 0 was consistent for all groups. The group means were compared using the one way analysis of variances computer program BMDP3D.** Probability values (P) were computed comparing techniques R and G within each group and comparing techniques R and G to the control teeth within each group. In addition, probability values were computed for the above comparisons corrected for time 0, to eliminate any influence that change of the whole system over time may have had on the statistical analysis. Tables II to IV show no significant difference (p > .05) between R and G, between R and the control, and between G and the control at 0,7, and 2 1 days. Tables V to VII show no significant difference between R and G, between R and the control, and between G and the control when all were corrected for time 0, at 0, 7, and 21 days. There were a few isolated significant p values, but these do not form a coherent pattern and the number of s,mall p values is not larger than what is expected given the number of comparisons we have performed. Therefore, we conclude that these data are consistent, with rio differences beyond chance in this experimental setting.

NOVEMBER

1981

VOLUME

46

NUMBER

5

CORD

DISPLACEMENT

VERSUS

GINGITAGE

CRG

CRG Moderate

Mild Fig. 4. Histologic

degree of inflammation.

Histologic features For each tooth, the following histologic features were evaluated. The sulcus depth was measured from the crest of the gingiva to the apical end of the sulcular epithelium, using the amalgam reference point. Tissue thickness was measured from the external surface of the oral epithelium to the’ tooth surface at the level of the apical end of the sulcular epithelium. The level of inflammation was rated on a 0 to 3 scale for no inflammation, mild inflammation (diffusely scattered cells), moderate inflammation (continuous cellular infiltrate), and severe inflammation (heavy cellular infiltrate), respectively. Mean sulcular depths are presented in Table VIII. The mean tissue thickness measured was 1.59 mm. The degree of inflammation is presented in Fig. 4. It shows all specimens to be within the mild and moderate inflammation groups, according to the measurement criteria. The group 1 control teeth all had intact epithehum within the sulcular area. The R teeth showed some tearing of the sulcular epithelium. The G teeth showed thinning or removal of the sulcular epithelium (Fig. 5). The group 2 control, R and G teeth had intact epithelium with rete peg development seen in the coronal portion of the sulcular epithelium. The group 3 control, R and G teeth had intact epithelium with rete peg development in the coronal half of the sulcular epithelium and well-developed, underlying connective tissue (Fig. 6).

DISCUSSION The results of this study indicate that there is no significant difference between cord gingival displace-

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OF PROSTHETIC

DENTlSTRY

Fig, 5. Sulcular areas at time R. C, Technique G.

0.

A, Control. B, Technique

ment and the gingitage technique. The experimental setting differed from human clinical practice in a number of ways. The canine model has different anatomic toothtissue relationships from the human. The canine cuspid tooth widens incisogingivally a.nd lacks constriction at the cementoenamel junction. There is no height of contour of the labial surface to limit access for subgingival tooth preparation. This anatomic feature made it easier to use the gingitage diamond without reducing the height of the gingival crest. The canine cuspid tooth has a wider zone of attached gingiva than the human. This may have contributed to the lack of gingival recession seen in this study. Under general anesthesia, the gingival cuff lacked tonus. As a result, the flaccid gingival i.issues seemed more easily deflected from the tooth surface by the handpiece air spray, allowing for a more minimal removal of the sulcular lining. Efforts were made to maximize gingival health. The levels of inflammation recorded clinically may have been more easily controlled in the experimental setting than in clinical practice. The minimal increase in sulcus depths of the experimental teeth in groups 2 and 3 may be a reflection of the slightly higher levels of inflammation. Tissues moderately inflamed histologically appeared less inflamed clinically. Nevertheless, the changes in the experimental teeth were no more significant than the changes in the control teeth for their respective time periods. Any critical analysis of two different procedures requires exacting technique. In the study, shoulder preparation, bevel placement, retraction cord placement, rotary curettage, and impression making were carefully performed. The Class V amalgams, burnished smooth and well marginated, restored normal

513

TUPAC

AND

NEACY

6. Use atraumatic impression techniques. 7. Make anatomically contoured temporary rations.

resto-

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tooth contour and simulated well-fitting temporary restorations. In addition, the general anesthesia contributed to the ease in performing these procedures, due to relaxation of the gingival cuff, allowing greater control. In processing the tissue sections, the intraoral tooth-tissue relationship was not maintained at times. As a result of tearing and separation, the sulcus depth was sometimes difficult to measure accurately. All histologic sections showed intact connective tissue underlying the gingitaged area.

SUMMARY

AND CONCLUSIONS

Fifteen young adult dogs were divided into three groups representing 0,7- and 21-day healing periods. Randomly selected cuspid teeth were used to compare cord gingival displacement and gingitage techniques for subgingival tooth preparation and impression making. Clinical and histologic measurements were used as a basis for comparison. Results indicate that (1) the experimental teeth were clinically healthy at the beginning of the experiment, (2) clinical health of the gingival tissues was controlled throughout the course of the experiment, and (3) within this experimental setting, there was no significant difference between the cord gingival displacement technique and the gingitage technique.

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