Gingival enhancement Microbiologic findings Thomas Michael

F. Flemmig, CL Newman,

in fixed prosthodontics.

Dr.Med.Dent.,* John A. Sorensen, D.D.S.,*** and Sushma Nachnani,

Part

II:

D.M.D.,** M.S.****

University of California, School of Dentistry, Los Angeles, Calif. This study assessed the changes of the subgingivaUmargina1 microflora during fixed prosthodontic procedures and evaluated the effect of adjunctive rinsing with 0.12% chlorhexidine on the subgingivaVmargina1 microflora during Bxed prosthodontic treatment. Thirty patients scheduled for fixed prosthodontics were randomly assigned to either rinsing with 16 ml of tap water b.i.d. (control) or rinsing with 16 ml of 0.12% chlorhexidine gluconate b.i.d. (experimental). Subgingival and marginal plaque was analyzed at baseline, before crown preparation (2 weeks), before cro-wn cementation (5 weeks), and 2 weeks after cementation (7 weeks). The fixed prosthodontic procedures alone altered the subgingival and marginal microhiota toward a more health-associated flora. Adjunctive rinsing twice daily with 0.12% chlorhexidine had a significantly greater effect in reducing putative periodontal pathogens compared with the control regimen. This medication was a useful adjunct to regular oral hygiene during fixed prosthodontic procedures by permitting the establishment and maintenance of a microflora compatible with periodontal health. (J PROSTHET DENT 1991;65:366-72.)

T

he establishmentand maintenanceof periodontal health is a prerequisite for successfulfixed prosthodontic proceduresaswelUaslongterm successfor fixed prostheses. On the basisof the bacterial etiology of periodontal disease, periodontal health is mainly dependent on plaque control. In preventing and reducing gingivitis, nonspecific plaque control is effectrive and can be augmented by chlorhexidine.‘-‘j Chlorhexidine has been shownto be the most efficaciousagent in reducing supragingival plaque and gingivitis when compared with other antimicrobial agents.7-11 Hence, adjunctive chlorhexidine may have a beneficial effect on the subgingival and marginal microflora of teeth undergoing tied prosthodontic treatment. The microbial dynamics during fixed prosthodontic procedureshasnot beenstudied. Elucidation of the microbial changesduring fixed prosthodontic procedureswould provide information about gingival responsesseen during prosthodontic treatment.12 In gingivitis, a greater amount of dental plaque and a qualitative changein bacterial composition of supragingival and subgingival plaque is found compared with good

Presented before the Pacific CoastSociety of Prosthodontists meeting, Sun River, Ore., and the American Academy of Periodontilogy meeting, San Diego, Calif.

This studywassupportedin part by the ProcterandGambleCo., Cincinnati, Ohio. *Visiting Assistant Professor, Section of Periodontics. **Assistant Professor, Director, Graduate Prosthodontics. ***Adjunct Professor, Section of Periodontics. ****Research Associate, Section of Periodontics. 10/l/26533

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gingival health.13-16 With gingivitis, elevated levels of Actinomyces sp, Lactobacillus sp, black pigmented Bacteroides sp,Fusobacterium nucleatum, spirilla, and spiro-

chetesare found in the subgingival area.17-20 Placement of overhanging restorations resulted in an increase of the proportions of gram-negative anaerobic bacteria in the subgingival microflora and was positively correlated with increasedgingivitis scoresand bone 10ss.~~-~ The bacterial compositionof the subgingivalplaque in gingivitis, periodontitis and gingival health has individually unique characteristics.lg,24-32 This study assessed the changesof the subgingival and marginalmicroflora during fixed prosthodontic procedures and evaluated the effect of adjunctive 0.12% chlorhexidine gluconate rinsing on subgingival and marginal microflora during fixed prosthodontic treatment.

MATERIAL

AND

METHODS

Patients were recruited from the School of Dentistry at the University of California, Los Angeles, who required tied prosthodontic treatment. Patients were excluded from the study if they had any systemic diseaseor took medications(including antibiotics, antimicrobials, or fluoride rinses)affecting gingival health 2 months before baseline. Patients meeting the entrance criteria were randomly assignedto one of two groups: Control group:Rinsingwith 15 ml water twice daily for 30 seconds after regular oral hygienefor 7 weeks Chlorhexidine group: Rinsing with 15 ml of 0.12% chlorhexidine

digluconate(Peridex,The ProcterandGambleCo.,Cincinnati, Ohio) twice daily for 30 seconds after regular oral hygiene for 7 WH&S

365

Scanning electron of specimens

Plaque sample Fig. 1. Study design.

At baseline, the medication was dispensed and the patients were instructed to start the rinsing regimen. Oral hygiene instructions were given but no professional cleaning was performed. Teeth were prepared and temporized at 2 weeks and the definitive crown was delivered and cemented at 5 weeks. Two weeks after crown cementation (7 weeks) the medication was terminated (Fig. 1).

Microbiological

analysis

Marginal and subgingival plaque samples were taken from one or two interproximal tooth sites of all 30 patients at baseline and at 2,5, and 7 weeks. Plaque samples were obtained from the same site in each patient throughout the entire study. For plaque sampling, supragingival plaque was removed with gauze before marginal and subgingival plaque were collected with a sterile curette.33*34 The plaque samples were immediately placed in 25% strength prereduced Ringer’s solution in 1 ml vials and processed within 30 minutes (Fig. 2). The samples were dispersed in an ultrasonic bath (Ultrasonic T-14, L and R Manufacturing, New Jersey) for 15 seconds and then vortexed for 10 seconds. Tenfold serial dilutions of the plaque sample were made and 0.1 ml aliquots of each dilution plated on trypticase soy agar supplemented with 5% sheep blood (TS-SB) (BBL Microbiology Systems, Cockeysville, Md.) supplemented with 5% rabbit blood (TS-RB) (BBL) and trypticase soy vancomycin bacitracin (TSVB) agar.35 TS-SB and TS-RB plates were incubated in an anaerobic glove box (85 % Ns, 5% COz, and 10% Hz). TSVB was incubated in Hz-CO2 atmosphere (Gas Pack Anaerobic System, BBL). Presumptive identification of the general cultivable microbiota was performed by use of colonial and cellular morphology, biochemical tests, aerotolerance, and Gram stainss~ 37; examiners were blind to the treatment regimens. Total counts of colony forming units (CFU) for all isolates were assessed with TSA-SB. Total counts for black pigmented Bacteroides sp (BPB) were assessed with TSA-RB and for Actinobacillus actinomycetemcomitans (A.a.) with TSVB. The proportional composition of the analyzed samples were used for the general descriptive microbiota from TSA-SB and for BPB from TSA-RB.

366

microscopy

preparation

For scanning electron microscopy, the acrylic resin provisional restoration wss carefully removed to leave the marginal and subgingival portion of the provisional restoration as unaltered as possible. The provisional restoration was immediately placed in 3% glutaraldehyde with phosphate buffer solution for transport and fixation (Fig. 2). For scanning electron microscopy the specimens were dehydrated in increasing concentrations of ethanol. Subsequently, the specimens were critical-point dried and sputter-coated with gold-palladium. The specimens were examined with an SEM (Autoscan, ETEC Corp., Hayward, Calif.) at magnifications of x30 to x3000 by an examiner blind to the treatment groups.ssl 3gPhotographs were taken from representative aspects of the outer surface of the provisional margins adjacent to the gingiva (marginal and subgingival), the composition of plaque was described, and the amount of bacterial colonization was estimated by surface coverage. Photographs in combination with the records were used for qualitative analysis.

Statistical

analysis

All analyses were performed with the patient as the statistical unit. In patients who had two sites sampled, the means of CFU and proportions from both sites were used for analysis. Logarithmic transformation (logic) of CFU was performed40 and repeated measures analysis of variance41 was used for the assessment of (1) intragroup changes over time, (2) difference of the intragroup changes between the two groups, and (3) overall time and treatment effect.

RESULTS The results of the subgingival and marginal plaque assessment for all four study visits could be included in the statistical analysis for 26 patients. The patients had a mean age of 38.7 + 13.5 years; 12 were men and 14 were women.

General

cultivable

microbiota

In the control group the proportions of coccal organisms increased significantly and the proportions of rod-shaped organisms decreased significantly from baseline to 5 weeks (p I 0.05) and 7 weeks (p I 0.01). Although not statistically significant, there was a trend toward increased proportions of gram-positive organisms and reduced proportions of gram-negative organisms over time (Table I). Gram-positive facultative cocci increased significantly in percentage from baseline to 7 weeks @ I 0.05) (Table II). No significant intragroup changes were found in the log10 CFU of the general cultivable microbiota in the control group (Table III). In the chlorhexidine group the proportions of coccal organisms increased significantly (p 5 0.05) from 2 to 5 weeks and the proportions of rod-shaped organisms de-

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General

cuttuvable

microbiota alac+ipignk?nted Bactemid0.s Actinolwillus actinomycetemcomitans

dilution

Biochemical

Scanning Microscopy

Electron

2. Microbiological methods.

Fig.

Table

identification

I. General cultivable microbiota. Morphology and Gram stain (% ) Baseline Group

Cocci*

2 Wks

(n)

Mean

SD

Mean

CHX (14)

40.5

23.3

38.5

Control (12)

30.9

15.9

CHX (14)

I

Mean 59.3

30.2 28.4

23.4

61.5 llu

L

69.1

15.9

50.3

organisms?

Gram-negative organisms$

46.6

19.2

54.5 50.5

22.0 20.0

44.2 61.7 55.8

Control (12)

45.5

22.0

38.3

30.2

30.0 YfT

significant

(p zz 0.05) intragroup

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51.5

26.6

21.2 27.3 21.2

31.3

all

changes over time; w

30.7 1

48.5

29.2

55.8 65.8 33.5

27.3

51.7 ((I

26.6

48.3 aa

30.7 _I

25.4 23.0 24.0

48.3 68.7 51.7

25.7 27.6 25.7

23.0

31.3

27.6

I 30.0 statistically

@ 5 0.01) intragroup

changes over

time effect. treatment effect. treatment effect.

creasedsignificantly (p I 0.05) from baselineand 2 weeks to 5 weeks(Table I). The proportions of gram-negative organismsalsodecreasedsignificantly (p I 0.01) from 2 to 5 weeks(Table I). Gram-positive facultative cocci increased significantly (p I ‘0.05) in logreCFU and percent from 2 to 5 weeks (Table III). Gram-positive facultative rods decreasedsignificantly (p I 0.05) in log10CFU and proportions from baselineto 5 weeks.Gram-negative facultative rods were significantly reduced (p 5 0.05) in log10CFU from baselineto 5 and 7 weeksand from 2 weeksto 5 weeks. Gram-negative anaerobic rods decreasedsignificantly (p I 0.05) in the chlorhexidine group in log10CFU from

THE

33.6

1 45.6

28.4

I

Statisticaly

SD

J

CHX (14) Control (12) CHX (14)

Repeated measwe analysis of variance: m time. *Statistically significant (p 5 0.05) overall tSt&istically significant @ 5 0.01) overall ~Statistically significant @ 5 0.05) overall

Mean

25.4

I

Gram-positive

SD

J

’ 57.5

7 Wks

I

II

nF

58.4

Control (12)

SD

42.5

I Rods*

6 Wks

DENTISTRY

baseline(Table III) and in proportions from 2 weeksto 5 weeks(Table II). The changesin log10CFU of gram-negative facultative rods over time were significantly different (p 5 0.01) between the chlorhexidine and control group. The log10 CFU of this bacterial group decreasedin the chlorhexidine group and increasedin the control group from baselineto I weeks. A significant overall time effect 0,~ 0.05) wasfound for the proportions of coccalorganisms,including gram-positive facultative cocci and rod-shapedorganisms. A significant overall treatment effect in percent of gram-positive

FLEMMIGETAL

Table

II.

General cultivable microbiota (% ) Baseline Group

Gram-positive facultative cocci*

2 Wks

6 Wks

7 Wks

(II)

Meall

SD

Mean

SD

Mean

SD

MeaIl

SD

CHX (14)

24:2

14.3

28.8

23.2

49.4

27.9

38.3

24.9

Control (12)

23.6

15.3

34.7

29.1

39.1

23.4

44.4

30.5

15.6

3.3

6.4

7.2

10.7

22.6 21.5 13.5 15.7

24.4 19.1 12.2 20.5

29.6 14.2 14.6 25.1

17.3

11.7

17.0

L-,1 Gram-positive facultative rods?

CHX (14)

22.0

26.9

13.3 Q

Gram-negative facultative rods Gram-negative anaerobic rods

1

Control (12) CHX (14) Control (12) CHX (14)

25.5

21.5

25.7

21.2 19.0

15.9

29.1

14.4

17.5 14.3

21.5 19.0

Control (12)

19.4

23.2

9.0

1 27.0 17.4 15.8 22.0 ST

I

Repeated measure analysis of variance: I Statistically significant *Statistically significant (p 4 0.05) overall time effect. tStatistically significant (p 5 0.01) overall treatment effect.

Table

III.

(p 5 0.05) intragroup

23.7 18.4 12.4 6.6

15.1

I 8.4

changes over time.

General cultivable microbiota mm0 cfu) Baseline Group

Mean

(n)

Gram-positivefacultative cocci

CHX

Gram-positivefacultativerods

Control(12) CHX (14)

(14)

2 Wks SD

Mean

5 Wks SD

Gram-negativeanaerobicrods

5.00

0.79

4.62

1.23

4.65

0.66 1.74

4.62 3.66

0.96

4.68

1.60

2.59

1.41 1.63

5.16 2.67

0.99 1.63

4.19

CHX (14)

4.66

Control (12)

3.99

CHX (14)

4.04

significant

e

1.40

I I

3.96

3.88

n

0.75

4.43

1.36

4.24

1.68

3.17

cultivable

microbiota

In the control group no significant changesoccurred over time in the selectedbacterial species(Tables IV and V). In

368

1.69

(p 5 0.05) intragroup

organisms@ I O.Ol), including gram-positive facultative rods (p I 0.01) and gram-negative organisms,(p I 0.05) wasseen.The chlorhexidine group showedlower proportions of gram-positive facultative rods and gram-positive organisms,and higher proportions of gram-negative organismsthan the control group (Tables I through III).

Selected

SD

1.48

4.17

Statistically

Mean

3.91 -“I

1.81

I

1.07

I

3.40

q

3.89

u

3.66

1.48

3.89

1.62

2.70

2.02

4

mY

I

Repeated measure analysis of variance: m of intragroup changes over time.

SD

0.90

Control (12)

Control(12)

Mean

4.83

I

Gram-negativefacultativerods

7 Wks

I 3.49

2.19

1.96

4.22

1.32

1.20

3.85

1.64

2.02

3.31

1.76

1.68

I 1.64

changes over time;

2.78 statistically

significant

(p 5 0.01) difference

9%

the chlorhexidine group the only significant changesseen (p I 0.05) were in reduction of log10CFU of Cupnocytophuga spp from baselineto 7 weeks(Table V). The changes over time were significantly different (p 5 0.05) betweenthe chlorhexidine and control group for Capnocytophaga spp (baseline to 7 weeks), Bacteroides gingiualis (baselineto 2 weeks),and Actinobacillus actinornycetemcomitans (2 to 5 weeks) (Tables IV and V). There wasa significant treatment effect (p I 0.01) that resulted in an overall lower CFU of B. gingidis in the

MARCH

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GINGIVAL

Table

ENHANCEMENT.

II: MICROBIOLOGY

IV. Selected

cultivable

microbiota

(%) 2 Wks

Baseline Group

Surface

translocating

Capnocytophuga

bacteria

CHX (14) Control 12) CHX (14)

spp

Bacteroides

intermedius

Bacteroides

gingiualis

Table

(STB)

Mean

(ll)

Control (12) CHX (14) Control (12) CHX (14) Control (12)

SD

3.9

Mean

6.8 2.4 8.4 8.0 6.9 0.0 0.0 6.2

1.5 6.6 5.1 2.6 0.0 0.0 3.2

5 Wks SD

Mean

11.9 1.5 1.6 2.5 12.6 3.7 8.2 3.1

7.5 3.8 5.4 1.7 5.0 1.5 3.2 1.1

SD

6.3 2.2 2.2 2.5 2.3 0.2 0.0 1.9

12.6 3.8 4.5 4.0 8.6 0.6 0.0 5.5

Mean

SD

3.5 1.0 3.8 4.0 3.0 0.2 1.5 2.1

7.2 1.3 6.7 6.6 7.7 0.8 3.0 5.1

V. Selecteldcultivable microbiota vmho

Baseline Group

Surface

translocating

Capnocytophaga

bacteria

intermedius

Bacteroides

gingioalis*

Actinobacillus

(STB)

spp

Bacteroides

actinomycetemcomitans

(n)

Mean

CHX (14) Control (12)

3.43 2.61

CHX

3.78

(14)

SD

I 1

3.07 2.92

1.48 1.52

1.63

3.26

1.47

2.75

1.46

2.69

1.43

1.20 1.40 0.00 0.00

3.08 2.23 2.08 2.00

1.52 1.41 1.41 1.06

3.14 1.74 1.61 1.64

1.78 0.99 0.46 0.59

3.39 2.12 1.48 2.00

0.00 0.98

1.08

2.02

1.16

2.41

1.69

0.97

A 1.68 I

0.40

1.77

0.74

1.03

1.84

0.68

1.76

0.79

2.16

Repeated measures analysis of variance:& of intragroup changes over time. *Statistically significant (p 5 0.01) overall

Statistically

treatment

1.70

significant

(p 5 0.05)

P

I I

electron

microscopy

The scanningmicroscopy of the outer surfaceof the provisional restoration margins contacting the gingiva revealed great variat.ion in the microbial colonization patterns. In somecases, only sparseplaque wasfound; in others a densemicrobial la.wnwasseen.The bacterial composition of the plaque varied from predominantly coccoid to predominantly rods and filaments (Figs. 3 and 4). No consistent pattern wasobservedthat would allow qualitative differentiation between the two groups basedupon scanning electron microscopic findings alone.

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1.64 changes

over

0.52 time.

2.07

A statistically ,b=i

1.47 1.09

1

significant

(p 5 0.05) difference

effect.

chlorhexidine group comparedwith the control group (Table V).

Scanning

0.53 intragroup

SD

1.60 1.59

1.92

(12)

Mean

3.03 3.20

1.51

Control

SD

1.34 1.68

2.64

(14)

Mean

3.46 3.04

Control CHX

SD

7 Wks

1.30 1.31

3.26 2.13 1.48 1.48

I I

5 Wks

Mean

Control (12) CHX (14) Control (12) CHX (14) (12)

cfu)

2 Wks

I

THE

7 Wks

DISCUSSION At baselinethe subgingival and marginal microflora of the analyzed teeth in both groupsrevealed only low numbers and proportions of periodontal pathogens.The composition of the flora found is compatible with gingivitis.14 It was demonstrated in this study that during fixed prosthodontic procedures alone, a shift toward a more health-associatedsubgingival and marginal microflora occurs. Although only partially significant statistically (predominantly from baselineto 5 and 7 weeks),these trends were observed in most microbial groups. These changes over time may be explained by the subgingival and marginal debridement effect of tooth preparation and gingival displacement.It may alsobe related to the so-calledHaw-

369

FLEMMIG

Fig. 3. Scanning electron micrograph of provisional margin shows predominance of coccoid microorganisms. Bar = 5rm. (Original magnification x3000.)

thorn effect42 and a result of behavior changes in subjects aware of their participation in a clinical trial. As previously demonstrated, the introduction of subgingival overhangs results in a shift of the microflora toward higher proportions of gram-negative anaerobe rods, black pigmented Bacteroides sp, Capnocytophaga sp, and anaerobic vibrio.21t 22Hence, it was surprising that placement of provisional restorations did not result in an increase of periodontopathic organisms as could be expected by the usually less than ideal fitting provisional restorations. Concomitantly with the microbiological changes, a reduction of supragingival plaque and an improvement of gingival health were seen in the control group.12 The short-term improvement of gingival health after tooth preparation, gingival displacement, impression making, and provisionalization with acrylic resin restorations is in agreement with a previous study.43 Adjunctive 0.12% chlorhexidine rinsing twice daily resulted in a significantly greater shift of the bacterial composition toward health-associated microflora than tooth brushing alone. The most pronounced intragroup changes of the microbial composition occurred after tooth preparation and provisionalization (from 2 to 5 weeks). In periodontitis patients, chlorhexidine rinsing was found to retard bacterial recolonization after debridement by scaling and root-planing. U Another finding of this study was that, since microbiological changes were greater from weeks 2 to 5 than observed from baseline to 2 weeks, chlorhexidine

370

ET AL

Fig. 4. Scanning electron micrograph of provisional margin shows predominance of rod-shaped and filamentous microorganisms. Bar = 5pm. (Original magnification x3000.)

rinsing appears to have its greatest effect in retarding the bacterial recolonization after the inadvertent debridement taking place during tooth preparation, gingival retraction, and impression procedures. Chlorhexidine rinsing also has reduced plaque and gingivitis scores significantly greater than tooth brushing alone.12 In periodontal maintenance patients it has been demonstrated that the beneficial microbiological and clinical effect of rinsing with 0.12% chlorhexidine twice daily for 6 weeks after debridement does not extend beyond the period the medication is used.45 Hence, it is unlikely that chlorhexidine rinsing over the 7-week period during fixed prosthetics has a long-lasting effect on the reduction of putative periodontal pathogens after cessation of the treatment regimen and when oral hygiene is not performed adequately. However, this question needs further investigation. Long-term maintenance of periodontal health is dependent on other factors such as oral hygiene, location of the final restoration margin, fidelity, and contour. In cross sectional and longitudinal studies, gingivitis scores, attachment loss, gingival recession, and pocket probing depth were greater in teeth with subgingival margins compared with teeth with supragingival restoration margins or unrestored teeth.46-50 Patients on a 2- to 3-month periodontal maintenance cycle demonstrated elevated gingivitis scores adjacent to restorations at the gingival margin.51

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The chlorhexidine regimen used in the present study can establish health-associated subgingival and marginal microflora that provide the foundation for periodontal health and gingival enhancement for teeth receiving fixed prosthodontic treatment.

CONCLUSIONS For the period of this ‘I-week clinical study: 1. A mild shift toward more health-associated subgingival and marginal microflora was observed during the course of fixed prosthodontics. 2. Adjunctive rinsing twice daily with 0.12% chlorhexidine resulted in a significantly greater reduction of putative periodontal pathogens compared with the control group. 3. Adjunctive rinsing twice daily with 0.12% chlorhexidine had its greatest effect on the subgingival and marginal microflora after tooth preparation, gingival displacement, and impression procedures during the provisional phase and appeared to retard bacterial colonization. We are indebted lo M.-A. Akers for her assistance in SEM, Drs. J. J. Lee and J. Gornbein for their aid in statistical analysis, and Dr. A. Rodrigues testing.

for his help

and support

in the microbiologic

REFERENCES 1. L&z H, The&de E:, Jensen SB. Experimental gingivitis in man. J Periodontol 1965;36:177-87. 2. Theilade E, Wright WH, Jensen SE. Experimental gingivitis in man II. A longitudinal, clinical and bacteriological investigation. J Periodont Res 1966;1:1-13. 3. Stamm JW. Epidemiology of gingivitis. J Clin Periodontol 1986;13: 360-6. 4. Sturzenberger OP, Bosma ML, Moore DJ, Grossman E. Clinical benefits of chlorhexidine in sustaining gingival health following prophylaxis. J Clin Dent 1988;1:24-7. 5. Liie H, Schiiitt CR, Glavind L, Karring T. Two years oral use of chlorhexidine in man. I. General design and clinical effects. J Periodont Rea 1976;17:135-44. 6. Grossman E, Rieter D, Sturzenberger OP, et al. Six-month study on the effect of a chlorhexi,dine mouthrinse on gingivitis in adults. J Periodont Res 1986;16(Suppl):33-43. 7. Wennstram J, Lindihe J. The effect of mouthrinses on parameters characterizing human periodontal disease. J Clin Periodontol1986;13:86-93. 8. Segreto VA, Col1in.s EM, Beiswagner BB, et al. A comparison of mouthrinses containing two concentrations of chlorhexidine. J Periodont Res 1986;21(Sulppl):23-32. 9. Siegrist AE, Gusberti FA, Brecx ML, Weber HP, Lang NP. Efficacy of supervised rinsing ,with chlorhexidine diiluconate in comparison to phenolic and plant alkaloid compounds. J Periodont Res 1986;21 (Suppl):60-73 10. Gusberti FA, Sampathkumar P, Siegrist BE, Lang NP. Microbiological and clinical effects of chlorhexidine gluconate and hydrogen peroxide mouthrinses on devs8loping plaque and gingivitis. J Periodonto 1988; 15~60-7. 11. Svantun B, Gjermo P, Eriksen HM, Rolla G. A comparison of the plaque-inhibiting effect of stannous flouride and chlorhexidine. Acta Odontol Stand 1977;35:247-250. 12. Sorensen JA, Doherty FM, Newman MG, Flemmig TF. Gingival enhancement in fixed prosthodontics. Part I: Clinical findings. J PROSTHET DENT 1991;65:100-7. 13. Slots J. Microflora in the healthy gingival sulcus in man. Stand J Dent Res 1977;85:247-54.

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OF PROSTHETIC

DENTISTRY

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A clinical evaluation relationships Michael Urstein, David Moskona,

D.M.D.,* D.M.D.,*** Harold S. Cardash, B.D.S., Maurice Tel Aviv,

and Gabriela

Goldschleger

of materials Simon Fitzig, and L.D.S., R.C.S. School

of Dental

Reprint

requests

to:

DR. JOHN A. SORENSEN CHS 33-041 SCHOOL OF DENTISTRY UNIVER~ITV OF CALIFORNIA Los ANGELES, CA 90024

Contributing

authors

Calsina, M.D., D.M.D., Visiting Scholar, Section of Periodontics, University of California, School of Dentistry, Los Angeles, Calif. Frances M. Doherty, B.S., RegisteredDental Hygienist, Staff, Research Associate, Section of Periodontics, University of California, Schoolof Dentistry, Los Angeles, Calif. J. Jack Lee, PhD, D.D.S., Adjunct Assistant Professor, Department of Biostatistics, Schoolof Public Health, University of California, Los Angeles, Calif. Gloria

used in registering

interjaw

D.M.D,** (Eng.)****

Medicine,Tel Aviv University,

Israel

Three recording media used to relate stone casts for 15 dentate patients were compared for accuracy. Interjaw relationships at the maximum intercuspation position and the retruded contact position were recorded using impression plaster, wax, and Duralay acrylic resin. A Lucia programming jig was used in the retruded contact position. The vertical distance and horizontal deviation between the casts were measured from reference points on the casts using each recording material. The average percentage differences between the recording materials were calculated. Hand articulation was the most accurate method of relating the casts at maximum intercuspation. The most accurate recording medium was impression plaster, followed by dental wax and Duralay resin at the maximum intercuspation and retruded contact positions. (J PROSTEET DENT 1991;65:372-7.)

T he ultimate accuracy in relating maxillary and mandibular dental castsis dependent on the accuracy and dimensionalstability of the material usedto record the interjaw relationships. This investigation comparedthe accuracy of three recording media used to relate artificial

*Instructor, Department of Oral Rehabilitation. **Clinical Lecturer, Department of Occlusion. ***Clinical Lecturer, Department of Oral Pathology and Oral Medicine. ****Senior Clinical Lecturer, Department of Oral Rehabilitation.

10/l/22252

372

stone casts at the maximum intercuspation (IC) and retruded contact (RC) position with the use of the Lucia programming jig.l MATERIAL

AND

METHODS

Fifteen patients with intact dentitions up to the second molarsand with Angle classI occlusionswere selected.The patients were free of temporomandibular joint symptoms and periodontal diseaseexcept for mild gingivitis in a few instances.No restorations were present in the teeth. Two impressionsof eachjaw were made using Blue print regular irreversible hydrocolloid impressionmaterial (DeTrey, Surrey, England). The impressions were immediately

MARCH1991

VOLUME65

NUMBER3