Journal of
Oral Rehabilitation
Journal of Oral Rehabilitation 2014 41; 306--313
A double-blind randomised clinical trial of two techniques for gingival displacement H. R. SARMENTO*, F. R. M. LEITE†, R. V. F. DANTAS*, F. A. OGLIARI‡, F . F . D E M A R C O † & F . F A O T † *Graduate Program in Dentistry, Federal University of Pelotas, Pelotas,
†
School of
‡
Dentistry, Federal University of Pelotas, Pelotas and Materials Engineering School, Federal University of Pelotas, Pelotas, Brazil
Knowledge about security and the potential damage originated by the gingival displacement techniques has not been described through randomised clinical studies. This crossover, double-blind, randomised clinical trial evaluated clinical and immunological factors related to conventional and cordless gingival displacement (GD) techniques, and patients’ perceptions in 12 subjects with the employment of 2 GD techniques: conventional (gingival cord + 25% AlCl3 astringent gel) and cordless (15% AlCl3 astringent-based paste). In each subject, two anterior teeth were treated and a 10-day wash-out period separated the two treatments. Periodontal indices were evaluated before (baseline) and 1 and 10 days after GD. Interleukin 1b, interleukin 6 and tumour necrosis factor a concentrations in gingival crevicular fluid were measured before and 1 day after GD. Subjective parameters (pain, unpleasant taste and stress) were also evaluated. Data were analysed by one-way repeated-measures analysis of variance and Tukey’s test (immunological factors), the SUMMARY
Introduction Regardless of the technique selected for dental impression, gingival displacement is an essential procedure; this is especially true when making impressions of subgingival finishing lines because a moisture-free sulcus is required for an effective impression. A range of gingival retraction techniques (conventional and cordless) and products (fluids and gels, mainly astringents and vasoconstrictors) is available, but their efficacy has not been well documented (1). © 2014 John Wiley & Sons Ltd
Friedman test (periodontal parameters) and Fisher’s exact or chi-squared test (subjective parameters), with a significance level of 95%. Gingival bleeding index, probing depth and plaque index values did not differ significantly between groups at any timepoint. Neither technique resulted in worse periodontal indices. Both techniques yielded similar results for pain and unpleasant taste, but conventional GD was significantly more stressful than cordless GD for volunteers. Both treatments significantly increased mean concentrations of the three cytokines, with the conventional technique producing the highest cytokine levels. Cordless GD is less stressful for patients and results in lower post-treatment levels of inflammatory cytokines compared with conventional GD. KEYWORDS: astringents, cytokines, dental prosthesis, gingival crevicular fluid, gingival retraction techniques, periodontal index Accepted for publication 29 December 2013
Astringents are based on aluminium chloride, aluminium sulphate or ferric sulphate; aluminium chloride products are used most widely (2). Astringents have only local action, which is an advantage because the systemic actions of adrenergic vasoconstrictors limit their clinical indications (3). Astringents have shown good clinical results (4), although some in vivo (5) and in vitro (6, 7) studies have demonstrated that these products can induce undesirable effects in tissues of the gingival margin, mainly due to their low pH (1–3) (2). doi: 10.1111/joor.12142
CLINICAL TRIAL OF GINGIVAL DISPLACEMENT TECHNIQUES Cordless techniques for gingival retraction have been introduced recently with the promise of many advantages, such as the reduction in chair time, greater patient comfort and minimal invasiveness (8). A clinical trial (4) evaluated the effects of two cordless gingival displacement techniques employing aluminium chloride and an elastomeric material, respectively, in comparison with the conventional corded technique. All three techniques caused temporary gingival inflammation, but the cordless techniques did not induce bleeding during or after gingival displacement (4). During gingival retraction for prosthetic purposes, in addition to mechanical trauma, the actions of chemical agents can induce an inflammatory response in gingival tissue (5). This response is mediated by inflammatory cytokines released by immune cells (macrophages and neutrophils) and fibroblasts (9). These cytokines are present in gingival fluid, the volume of which increases due to the presence of inflammatory exudate (10). Innate immunity causes the rapid production of interleukin (IL)-1, IL-6 and tumour necrosis factor alpha (TNF-a) when tissue injury occurs (11). However, a review of the major literature databases identified no study assessing inflammatory cytokine levels in gingival crevicular fluid after gingival displacement focusing on comparisons between different techniques. The aim of this randomised clinical trial was to assess clinical and immunological factors related to two gingival displacement techniques (conventional and cordless), as well as patients’ perceptions of these treatments. The null hypotheses evaluated were that the choice of gingival displacement technique would not influence (i) inflammatory cytokine levels in gingival crevicular fluid, (ii) clinical gingival parameters or (iii) individual factors such as pain, stress and unpleasant taste during gingival displacement.
Materials and methods The design of this crossover, double-blind, randomised clinical trial followed the guidelines of the Consolidated Standards of Reporting Trials (12). A flowchart of this trial is presented in Fig. 1. The local ethics committee approved the study protocol (#54/2011), which is registered in the ClinicalTrials.gov database (NCT01848496). All subjects were informed of the © 2014 John Wiley & Sons Ltd
Fig. 1. Flow diagram of the trial.
risks and benefits of the treatment and provided written consent prior to enrolment. Study overview This study was carried out during 28 days (day 0–day 27; Fig. 1). On day 0 was performed a clinical examination of all anterior teeth, and two non-adjacent teeth were prepared and received provisional restorations. On day 4, a prophylactic biofilm control was performed with pumice stone and rubber cup on all teeth of each volunteer. On day 7, teeth were dried slightly with an air spray; one tooth (tooth A) of each voluntary was selected for control group and received randomly the first impression technique. Then, dental impressions were taken. On day 8, gingival crevicular fluid (GCF) collection was performed on tooth A and a clinical examination on all anterior maxillary teeth. After a 10-day wash-out period, other clinical examination was performed and the tooth B received the second impression technique (day 17). Days 17, 18 and 27 for the second treatment represented days 7, 8 and 17 for the first treatment.
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H . R . S A R M E N T O et al. Sample size Sample size calculation was based on a previous study (13) using the following parameters: smallest expected difference between means, standard deviations of the difference between means, beta error of 10% and one-tailed alpha error of 5%. The sample size was increased by 20% to account for potential losses and refusals. These calculations determined that 12 participants were required for this clinical trial. Recruitment was conducted through posters displayed at the School of Dentistry, Federal University of Pelotas, Rio Grande do Sul, Brazil. Eligibility criteria, randomisation and blinding Prior to dental examination, each subject filled out a medical history form and underwent complete dental prophylaxis to remove any biofilm present. Twenty subjects were examined to obtain 12 individuals in good general and dental health who met the inclusion criteria. Study subjects had indications for prosthetic dental crowns on at least two maxillary anterior teeth with thick gingival biotype and good periodontal health, characterised by regular gingival margins with ≥2 mm attached gingiva, non-fibrotic gingival tissue, no marginal recession, probing depth ≤3 mm, no evidence of significant loss of bone insertion and no visible plaque or gingival bleeding (14). Individuals with systemic disease, those who had used antibiotics or anti-inflammatory drugs in the last 60 days, pregnant women and smokers were excluded from the study. In each subject, one tooth to be restored (control) was randomly selected by lottery from opaque envelopes. All patients received uniform instructions on oral hygiene. The gingival displacement technique (conventional or cordless) used for each tooth was selected randomly by lottery. Dental preparation restorations
and
manufacture
of
temporary
On day 0, the teeth were prepared for metal-ceramic crowns using diamond burs (#4138, #3168, and #3203*) with 1-mm subgingival margin and chamfer finish line. A metallic manual instrument protected gingival margin. In the same clinical session, tempo-
rary crowns were fabricated from a non-irritating polyethyl methacrylate resin (TRIMâ II†). Clinical periodontal examination A single examiner recorded probing depth (PD), clinical attachment level (CAL), gingival bleeding index (GBI), plaque index (PI) and tooth mobility for all maxillary anterior teeth (14). Cold-air sensitivity tests were performed on the selected teeth before and after gingival displacement through a 1-s application of cold air from a dental unit syringe (20 3 °C at 60–65 psi). The operator assessed and recorded gingival bleeding during displacement and after the application of each technique. Subjects were also asked to report the presence or absence of pain, stress and unpleasant taste during gingival displacement. To obtain these data, it was used the Likert scale in which subject report the event intensity (1-none to 5-very much) (15). Gingival displacement, impressions and gingival crevicular fluid collection The temporary crowns were removed and GCF was collected from the control area performed with sterile absorbent paper strips (Periopaperâ†), which were inserted 1 mm into the mesiobuccal surface of the gingival sulcus for 60 s. After 90 s, a new paper strip was inserted into the distobuccal surface of the sulcus and a second sample was collected. The two absorbent paper strips with the collected material were stored in one cryotube identified by a code known only to the researcher performing collection. Each cryotube contained 100 mL phosphate-buffered saline‡. The samples were centrifuged and supernatants were frozen at –80 °C until laboratory analysis. Then, gingival displacement was performed on each subject’s control tooth. Throughout the gingival displacement procedures, a cotton roll was used to isolate the area and suction was applied to remove saliva. The conventional technique used the following protocol: application of a 25% aluminium chloride-based astringent gel (Viscostat Clearâ§)
†
Bossworth Company, Skokie, IL, USA.
‡
Oraflow Incorporated, Amityville, NY, USA.
*KG Sorensen, Cotia, SP, Brazil.
§
Sigma Chemical Co., St. Louis, MO, USA. © 2014 John Wiley & Sons Ltd
CLINICAL TRIAL OF GINGIVAL DISPLACEMENT TECHNIQUES around the gingival margin, followed by insertion of a gingival cord (Ultrapakâ Cord #00¶) with the aid of a packer (Fischer’s Ultrapak Packer, 45° small size¶). Then, Viscostat Clearâ was reapplied around the gingival margin, according to the manufacturer’s instructions. After 10 min, the cord was removed gently from the sulcus, and an air/water spray was applied to remove the astringent. Single cord technique was used to avoid additional mechanical trauma and focus on the cytotoxic effects of the different astringents employed. The cordless technique was also performed according to the manufacturer’s instructions: the gingival margin was gently air-dried, and Expasylâ** was applied around it for 2 min. The Expasylâ was then removed by an air/ water spray. Dental impressions were obtained with polyvinyl siloxane (Expressâ XT††) using a single-step doubleimpression technique. Casts were poured 1 h later to avoid bubbles caused by hydrogen liberation during polyvinyl siloxane polymerisation. A blinded examiner quantified IL-1b, IL-6 and TNFa levels (pg/lL) in GCF using cytokine-specific enzyme-linked immunosorbent assays‡‡ according to the manufacturer’s recommendations. Data analyses The SigmaStatâ software package§§ was used for data analyses. The Friedman test was used to analyse differences in ranked periodontal parameters (PD, GBI and PI) obtained at the three visits for each technique. Subjectively reported parameters (pain, stress and unpleasant taste) during gingival displacement were dichotomised following the Likert scale scores in ‘yes’ (2, 3, 4 or 5) or ‘no’ (1) and analysed by Fisher’s exact test or the chi-squared test, according to data distribution. CAL, tooth mobility, sensitivity to cold air and bleeding during and after the procedure were analysed using simple descriptive statistics, including the calculation of frequencies. Cytokine concentrations were analysed by one-way repeated-measures analysis of variance, followed by Tukey’s test. IL-1b data violated the assumptions of equality of variance ¶
Ultradent Products, South Jordan, UT, USA.
**Pierre Rolland, M erignac, France. ††
3M ESPE, St. Paul, MN, USA.
‡‡
Invitrogen Corporation, Carlsbad, CA, USA.
§§
Systat Software Corporation, San Jose, CA, USA.
© 2014 John Wiley & Sons Ltd
and normal distribution of errors, and data were transformed by ranking. A significance level of 95% was used for all analyses.
Results Twenty-four maxillary anterior teeth (15 vital; 9 nonvital) in 12 subjects (10 women and 2 men) with no sign of gingivitis were included in this study. The mean age of participants was 47 74 (range, 39–60) years. Mean values for periodontal parameters are presented according to gingival displacement technique in Table 1 and ranked in Tables 2 and 3. Tooth mobility, CAL, GBI, PD and PI values were homogenous in the two groups into each timepoint (Table 1). Considering the same treatment, neither of the two evaluated techniques resulted in a significant increase in PD, GBI or PI (Tables 2 and 3). No gingival bleeding was observed during or after gingival displacement in either group. No difference in CAL, tooth mobility, sensitivity to cold air or bleeding was observed in either group throughout the experimental period. Subjects reported significantly (P = 0014) more stress during conventional gingival displacement than during cordless displacement. The occurrence of pain (P = 0193) and unpleasant taste (P = 0221) did not differ between techniques (Table 4). Both gingival displacement techniques increased the mean concentrations of the three evaluated cytokines, with the highest concentrations (P < 0,001) observed in association with the conventional technique (Table 5).
Discussion This study was the first randomised clinical trial to compare the efficacy of conventional and cordless gingival displacement techniques using clinical, immunological and individual parameters. One previous study clinically compared these techniques, but only periodontal indices and subjective parameters were evaluated (4). Another study evaluated TNF-a levels in GCF after conventional gingival displacement, without comparison with other techniques (16). The null hypotheses of the present study were partially rejected, as the gingival displacement techniques affected inflammatory cytokine levels in GCF and patients’ stress during the procedure.
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H . R . S A R M E N T O et al. Table 1. Subject distribution for periodontal parameters at the three visits for each technique (Cordless, Expasyl; Conventional, Ultrapak Cord + Viscostat Clear) Subjects distribution
Parameter PD (mm) 1 2 Mean SD Median P* GBI 0 1 Median P* PI 0 1 Median P* Mobility 0 CAL 0
Before displacement
1 day post-displacement
10 days post-displacement
Cordless
Conventional
Cordless
Conventional
Cordless
Conventional
12 0 10 1 NE
12 0 10 1
12 0 10 1 0166
10 2 117 039 1
11 1 108 029 1 0359
12 0 10 1
11 1 0 0359
12 0 0
11 1 0 0580
10 2 0
12 0 0 NE
12 0 0
11 1 0 0359
12 0 0
12 0 0 NE
12 0 0
12 0 0 0359
11 1 0
12
12
12
12
12
12
12
12
12
12
12
12
PD, probing depth; GI, gingival index; PI, plaque index; CAL, clinical attachment level; NE, not evaluated. *Mann–Whitney U-test (confidence level: 95%).
Table 2. Mean ranks of probing depth (PD), gingival bleeding index (GBI) and plaque index (PI) for the Cordless technique group
Table 3. Mean ranks of probing depth (PD), gingival bleeding index (GBI) and plaque index (PI) for the Conventional technique group
Index
Time
n
Mean rank
P*
Index
Time
n
Mean rank
P*
PD
Before displacement 1 day post-displacement 10 days post-displacement Before displacement 1 day post-displacement 10 days post-displacement Before displacement 1 day post-displacement 10 days post-displacement
12 12 12 12 12 12 12 12 12
100 100 100 000 000 000 000 000 000
0368
PD
GBI
0368
PI
12 12 12 12 12 12 12 12 12
100 100 100 00 00 00 00 00 00
0135
0368
Before displacement 1 day post-displacement 10 days post-displacement Before displacement 1 day post-displacement 10 days post-displacement Before displacement 1 day post-displacement 10 days post-displacement
GBI
PI
0135
0368
*Friedman test (P < 005).
*Friedman test (P < 005).
The cordless technique used in this study employed Expasylâ, a gingival displacement material with a paste-like consistency that combines the haemostatic properties of aluminium chloride with the hygroscopic expansion of kaolin to provide moderate displacement of the gingiva approximately 2 min after its applica-
tion and contact with the GCF (8). However, the predictability and efficacy of this technique have not been established (17). Appropriately designed and conducted randomised clinical trials are considered to be the gold standard in assessing healthcare interventions (12). In clinical © 2014 John Wiley & Sons Ltd
CLINICAL TRIAL OF GINGIVAL DISPLACEMENT TECHNIQUES Table 4. Subjective parameters reported by subjects after gingival displacement Parameter Pain Yes No Unpleasant taste Yes No Stress Yes No
Cordless
Conventional
P
2 10
6 6
0193*
4 8
8 4
0221†
0 12
6 6
0014*
*Fisher Exact test (P < 005). Qui-square test (P < 005).
†
Table 5. Mean cytokine concentration (pg/lL) standard deviation (SD) before (control) and after treatments Cytokine (pg/ll SD) Technique
IL-1b
IL-6
TNF-a
Baseline Cordless Conventional
60 04A 1573 13B 1793 07C
287 03A 1182 13B 1387 08C
461 04A 678 05B 812 05C
Capital letters denote statistically significant differences into the same column (Tukey’s test, P < 005).
situations, two or more teeth can receive gingival displacement through different techniques at the same time. However, to avoid an overlapping effect and confounding results, we used the crossover study model. In the present study, a 10-day wash-out period was used based on a previous study finding that the tissue damage caused by conventional gingival displacement is histologically resolved after this period (18). The main disadvantage presented in the adoption of a crossover model in the clinical routine of this study was the fact that it would be necessary one more clinical session to make a transfer impression incorporating the metal substructures previously to the ceramic application. Sample size calculation took into account the main outcome of this study, considering immunological parameters (IL-1b, IL-6 and TNF-a levels) reported by another study (13). Other secondary outcomes, such as periodontal indices, bleeding and self-reported subjective parameters, were also evaluated. Baseline values for these parameters were similar between groups, and no difference in periodontal indices was © 2014 John Wiley & Sons Ltd
observed between groups at any timepoint (baseline, 1 day and 10 days post-displacement). Furthermore, subjective assessments of pain and unpleasant taste did not differ between groups. Another study (4) with a larger sample (n = 60) also found no difference in periodontal indices between areas treated with conventional and cordless techniques, except for the gingival index. The authors reported that bleeding during and after displacement was induced only by the conventional technique in approximately 30% of subjects (4). In contrast, we observed no bleeding in our study subjects. The occurrence of gingival bleeding in the previous study was probably due to the use of a non-impregnated cord and no haemostatic solution, whereas we performed conventional gingival displacement with a non-impregnated cord and an aluminium chloridebased astringent solution. Although our sample size did not provide adequate statistical power to measure secondary outcomes, a significant difference in patient-reported stress in favour of the cordless technique was observed between groups. This result may be explained by the difficulty of performing the conventional technique, which depends on the operator’s familiarity, consumes much clinical time and leads to bleeding and patient discomfort (16). All volunteers of this study presented thick gingival biotype, which is more resilient and tend to be more resistant to mechanical trauma. Thus, the minimisation of this trauma caused by gingival displacement in the stimulation of inflammatory cytokines production, which would be a confounding factor, was minimised focusing on the cytotoxic effects of the astringents employed. During gingival displacement for prosthodontic purposes, mechanical trauma and astringents may induce a gingival inflammatory response (5), which increases GCF volume due mainly to the presence of inflammatory exudate (10). This exudate is composed primarily by pro-inflammatory cytokines of innate immunity (e.g. IL-1b, IL-6 and TNF-a) (11). In this study, both gingival displacement techniques increased IL-1b, IL-6 and TNF-a concentrations compared with baseline. The presence of GCF may significantly compromise the quality of dental impressions. To avoid this effect, the sulcus must be dried using chemical products, such as astringents. Aluminium chloride is a widely used astringent that acts predominantly via the
311
312
H . R . S A R M E N T O et al. precipitation of proteins and inhibition of plasma protein transcapillary movement (17). Both techniques used in this study employed aluminium chloridebased products. The conventional technique produced the highest cytokine levels. This result is in agreement with that of another study (19), which showed that the same cordless technique resulted in more effective sulcus drying compared with epinephrine-impregnated cords. Moreover, another study showed that the Expasylâ (Pierre Rolland, M erignac, France) cordless technique resulted in a higher percentage of histologically observed intact junctional epithelium compared with the conventional technique (20). The results of this study indicate that the cordless technique is a more conservative periodontal treatment that is less stressful for patients. However, as observed in another study (19), the cordless technique provided narrower sulcus opening compared with the use of retraction cords in many cases in the present study. The objective of this study was not to evaluate the relative effectiveness of gingival displacement techniques or impression accuracy; however, further research should focus on these issues because scanning techniques are available. Even though gingival recession and pocket depth could be monitored by consecutive dental impressions as previously described (21), in the design of this study, the trauma caused to the tissue could mask the results increasing marginal recession (22). Moreover, the positive attributes of each displacement technique should be associated with the specific challenges presented by individual patients.
Conclusions Cordless gingival displacement resulted in lower proinflammatory cytokine levels in GCF and less patient stress compared with the conventional technique.
Acknowledgments The present study was approved by the local ethics committee and registered in the ClinicalTrials.gov database. The authors thank Labordental Distributor of Dental Products for providing some of the materials used in this study. H.R.S. is grateful to CAPES/ Brazil for an MSc scholarship. This study was supported by FINEP/Brazil (Grant no. 1407/10,
Agreement no. 01.11.00.88.00) and CAPES/Brazil (no. 23038.028455/2009-12).
Disclosure No conflict of interests declared.
References 1. Jokstad A. Clinical trial of gingival retraction cords. J Prosthet Dent. 1999;81:258–261. 2. Nowakowska D, Saczko J, Kulbacka J, Choromanska A. Dynamic oxidoreductive potential of astringent retraction agents. Folia Biol (Praha). 2010;56:263–268. 3. Polat NT, Ozdemir AK, Turgut M. Effects of gingival retraction materials on gingival blood flow. Int J Prosthodont. 2007;20:57–62. 4. Al Hamad KQ, Azar WZ, Alwaeli HA, Said KN. A clinical study on the effects of cordless and conventional retraction techniques on the gingival and periodontal health. J Clin Periodontol. 2008;35:1053–8. 5. Kopac I, Cvetko E, Marion L. Gingival inflammatory response induced by chemical retraction agents in beagle dogs. Int J Prosthodont. 2002;15:14–19. 6. Kopac I, Batista U, Cvetko E, Marion L. Viability of fibroblasts in cell culture after treatment with different chemical retraction agents. J Oral Rehabil. 2002;29:98–104. 7. Kopac I, Sterle M, Marion L. Electron microscopic analysis of the effects of chemical retraction agents on cultured rat keratinocytes. J Prosthet Dent. 2002;87:51–56. 8. Perakis N, Belser UC, Magne P. Final impressions: a review of material properties and description of a current technique. Int J Periodont Restorative Dent. 2004;24:109–117. 9. Gustafsson A, Ito H, Asman B, Bergstr€ om K. Hyper-reactive mononuclear cells and neutrophils in chronic periodontitis. J Clin Periodontol. 2006;33:126–129. 10. Ho W, Eubank T, Leblebicioglu B, Marsh C, Walters J. Azithromycin decreases crevicular fluid volume and mediator content. J Dent Res. 2010;89:831–835. 11. Garlet GP. Destructive and protective roles of cytokines in periodontitis: a re-appraisal from host defense and tissue destruction viewpoints. J Dent Res. 2010;89:1349–1363. 12. Schulz KF, Altman DG, Moher D, Group C. CONSORT 2010 statement: updated guidelines for reporting parallel group randomised trials. Br Med J. 2010;340:c332. 13. Passariello C, Puttini M, Virga A, Gigola P. Microbiological and host factors are involved in promoting the periodontal failure of metaloceramic crowns. Clin Oral Investig. 2012;16:987–995. 14. Ainamo J, Bay I. Problems and proposals for recording gingivitis and plaque. Int Dent J. 1975;25:229–235. 15. Zhao Y, He SL. Development of the Chinese version of the Oro-facial Esthetic Scale. J Oral Rehabil. 2013;40:670–677. 16. Feng J, Aboyoussef H, Weiner S, Singh S, Jandinski J. The effect of gingival retraction procedures on periodontal
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CLINICAL TRIAL OF GINGIVAL DISPLACEMENT TECHNIQUES
17. 18. 19.
20.
indices and crevicular fluid cytokine levels: a pilot study. J Prosthodont. 2006;15:108–112. Donovan TE, Chee WW. Current concepts in gingival displacement. Dent Clin North Am. 2004;48:433–444. Loe H, Silness J. Tissue reactions to string packs used in fixed restorations. J Prosthet Dent. 1963;13:318–323. W€ ostmann B, Rehmann P, Balkenhol M. Influence of different retraction techniques on crevicular fluid flow. Int J Prosthodont. 2008;21:215–216. Phatale S, Marawar PP, Byakod G, Lagdive SB, Kalburge JV. Effect of retraction materials on gingival health: a histopathological study. J Indian Soc Periodontol. 2010;14:35–39.
© 2014 John Wiley & Sons Ltd
21. Yang JC, Tsai CM, Chen MS, Wei JY, Lee SY, Lin CT. Clinical study of a newly developed injection-type gingival retraction method. Chinese Dent J. 2005;24:147–151. 22. Labban N. A simple technique to reduce the risk of irreversible gingival recession after the final impression. J Prosthodont. 2011;20:649–651. Correspondence: Fernanda Faot, School of Dentistry, Federal University of Pelotas, Goncßalves Chaves St., 457, Center, Pelotas, RS 96015560, Brazil. E-mail: [email protected]
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Oral Rehabilitation
Journal of Oral Rehabilitation 2014 41; 306--313
A double-blind randomised clinical trial of two techniques for gingival displacement H. R. SARMENTO*, F. R. M. LEITE†, R. V. F. DANTAS*, F. A. OGLIARI‡, F . F . D E M A R C O † & F . F A O T † *Graduate Program in Dentistry, Federal University of Pelotas, Pelotas,
†
School of
‡
Dentistry, Federal University of Pelotas, Pelotas and Materials Engineering School, Federal University of Pelotas, Pelotas, Brazil
Knowledge about security and the potential damage originated by the gingival displacement techniques has not been described through randomised clinical studies. This crossover, double-blind, randomised clinical trial evaluated clinical and immunological factors related to conventional and cordless gingival displacement (GD) techniques, and patients’ perceptions in 12 subjects with the employment of 2 GD techniques: conventional (gingival cord + 25% AlCl3 astringent gel) and cordless (15% AlCl3 astringent-based paste). In each subject, two anterior teeth were treated and a 10-day wash-out period separated the two treatments. Periodontal indices were evaluated before (baseline) and 1 and 10 days after GD. Interleukin 1b, interleukin 6 and tumour necrosis factor a concentrations in gingival crevicular fluid were measured before and 1 day after GD. Subjective parameters (pain, unpleasant taste and stress) were also evaluated. Data were analysed by one-way repeated-measures analysis of variance and Tukey’s test (immunological factors), the SUMMARY
Introduction Regardless of the technique selected for dental impression, gingival displacement is an essential procedure; this is especially true when making impressions of subgingival finishing lines because a moisture-free sulcus is required for an effective impression. A range of gingival retraction techniques (conventional and cordless) and products (fluids and gels, mainly astringents and vasoconstrictors) is available, but their efficacy has not been well documented (1). © 2014 John Wiley & Sons Ltd
Friedman test (periodontal parameters) and Fisher’s exact or chi-squared test (subjective parameters), with a significance level of 95%. Gingival bleeding index, probing depth and plaque index values did not differ significantly between groups at any timepoint. Neither technique resulted in worse periodontal indices. Both techniques yielded similar results for pain and unpleasant taste, but conventional GD was significantly more stressful than cordless GD for volunteers. Both treatments significantly increased mean concentrations of the three cytokines, with the conventional technique producing the highest cytokine levels. Cordless GD is less stressful for patients and results in lower post-treatment levels of inflammatory cytokines compared with conventional GD. KEYWORDS: astringents, cytokines, dental prosthesis, gingival crevicular fluid, gingival retraction techniques, periodontal index Accepted for publication 29 December 2013
Astringents are based on aluminium chloride, aluminium sulphate or ferric sulphate; aluminium chloride products are used most widely (2). Astringents have only local action, which is an advantage because the systemic actions of adrenergic vasoconstrictors limit their clinical indications (3). Astringents have shown good clinical results (4), although some in vivo (5) and in vitro (6, 7) studies have demonstrated that these products can induce undesirable effects in tissues of the gingival margin, mainly due to their low pH (1–3) (2). doi: 10.1111/joor.12142
CLINICAL TRIAL OF GINGIVAL DISPLACEMENT TECHNIQUES Cordless techniques for gingival retraction have been introduced recently with the promise of many advantages, such as the reduction in chair time, greater patient comfort and minimal invasiveness (8). A clinical trial (4) evaluated the effects of two cordless gingival displacement techniques employing aluminium chloride and an elastomeric material, respectively, in comparison with the conventional corded technique. All three techniques caused temporary gingival inflammation, but the cordless techniques did not induce bleeding during or after gingival displacement (4). During gingival retraction for prosthetic purposes, in addition to mechanical trauma, the actions of chemical agents can induce an inflammatory response in gingival tissue (5). This response is mediated by inflammatory cytokines released by immune cells (macrophages and neutrophils) and fibroblasts (9). These cytokines are present in gingival fluid, the volume of which increases due to the presence of inflammatory exudate (10). Innate immunity causes the rapid production of interleukin (IL)-1, IL-6 and tumour necrosis factor alpha (TNF-a) when tissue injury occurs (11). However, a review of the major literature databases identified no study assessing inflammatory cytokine levels in gingival crevicular fluid after gingival displacement focusing on comparisons between different techniques. The aim of this randomised clinical trial was to assess clinical and immunological factors related to two gingival displacement techniques (conventional and cordless), as well as patients’ perceptions of these treatments. The null hypotheses evaluated were that the choice of gingival displacement technique would not influence (i) inflammatory cytokine levels in gingival crevicular fluid, (ii) clinical gingival parameters or (iii) individual factors such as pain, stress and unpleasant taste during gingival displacement.
Materials and methods The design of this crossover, double-blind, randomised clinical trial followed the guidelines of the Consolidated Standards of Reporting Trials (12). A flowchart of this trial is presented in Fig. 1. The local ethics committee approved the study protocol (#54/2011), which is registered in the ClinicalTrials.gov database (NCT01848496). All subjects were informed of the © 2014 John Wiley & Sons Ltd
Fig. 1. Flow diagram of the trial.
risks and benefits of the treatment and provided written consent prior to enrolment. Study overview This study was carried out during 28 days (day 0–day 27; Fig. 1). On day 0 was performed a clinical examination of all anterior teeth, and two non-adjacent teeth were prepared and received provisional restorations. On day 4, a prophylactic biofilm control was performed with pumice stone and rubber cup on all teeth of each volunteer. On day 7, teeth were dried slightly with an air spray; one tooth (tooth A) of each voluntary was selected for control group and received randomly the first impression technique. Then, dental impressions were taken. On day 8, gingival crevicular fluid (GCF) collection was performed on tooth A and a clinical examination on all anterior maxillary teeth. After a 10-day wash-out period, other clinical examination was performed and the tooth B received the second impression technique (day 17). Days 17, 18 and 27 for the second treatment represented days 7, 8 and 17 for the first treatment.
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H . R . S A R M E N T O et al. Sample size Sample size calculation was based on a previous study (13) using the following parameters: smallest expected difference between means, standard deviations of the difference between means, beta error of 10% and one-tailed alpha error of 5%. The sample size was increased by 20% to account for potential losses and refusals. These calculations determined that 12 participants were required for this clinical trial. Recruitment was conducted through posters displayed at the School of Dentistry, Federal University of Pelotas, Rio Grande do Sul, Brazil. Eligibility criteria, randomisation and blinding Prior to dental examination, each subject filled out a medical history form and underwent complete dental prophylaxis to remove any biofilm present. Twenty subjects were examined to obtain 12 individuals in good general and dental health who met the inclusion criteria. Study subjects had indications for prosthetic dental crowns on at least two maxillary anterior teeth with thick gingival biotype and good periodontal health, characterised by regular gingival margins with ≥2 mm attached gingiva, non-fibrotic gingival tissue, no marginal recession, probing depth ≤3 mm, no evidence of significant loss of bone insertion and no visible plaque or gingival bleeding (14). Individuals with systemic disease, those who had used antibiotics or anti-inflammatory drugs in the last 60 days, pregnant women and smokers were excluded from the study. In each subject, one tooth to be restored (control) was randomly selected by lottery from opaque envelopes. All patients received uniform instructions on oral hygiene. The gingival displacement technique (conventional or cordless) used for each tooth was selected randomly by lottery. Dental preparation restorations
and
manufacture
of
temporary
On day 0, the teeth were prepared for metal-ceramic crowns using diamond burs (#4138, #3168, and #3203*) with 1-mm subgingival margin and chamfer finish line. A metallic manual instrument protected gingival margin. In the same clinical session, tempo-
rary crowns were fabricated from a non-irritating polyethyl methacrylate resin (TRIMâ II†). Clinical periodontal examination A single examiner recorded probing depth (PD), clinical attachment level (CAL), gingival bleeding index (GBI), plaque index (PI) and tooth mobility for all maxillary anterior teeth (14). Cold-air sensitivity tests were performed on the selected teeth before and after gingival displacement through a 1-s application of cold air from a dental unit syringe (20 3 °C at 60–65 psi). The operator assessed and recorded gingival bleeding during displacement and after the application of each technique. Subjects were also asked to report the presence or absence of pain, stress and unpleasant taste during gingival displacement. To obtain these data, it was used the Likert scale in which subject report the event intensity (1-none to 5-very much) (15). Gingival displacement, impressions and gingival crevicular fluid collection The temporary crowns were removed and GCF was collected from the control area performed with sterile absorbent paper strips (Periopaperâ†), which were inserted 1 mm into the mesiobuccal surface of the gingival sulcus for 60 s. After 90 s, a new paper strip was inserted into the distobuccal surface of the sulcus and a second sample was collected. The two absorbent paper strips with the collected material were stored in one cryotube identified by a code known only to the researcher performing collection. Each cryotube contained 100 mL phosphate-buffered saline‡. The samples were centrifuged and supernatants were frozen at –80 °C until laboratory analysis. Then, gingival displacement was performed on each subject’s control tooth. Throughout the gingival displacement procedures, a cotton roll was used to isolate the area and suction was applied to remove saliva. The conventional technique used the following protocol: application of a 25% aluminium chloride-based astringent gel (Viscostat Clearâ§)
†
Bossworth Company, Skokie, IL, USA.
‡
Oraflow Incorporated, Amityville, NY, USA.
*KG Sorensen, Cotia, SP, Brazil.
§
Sigma Chemical Co., St. Louis, MO, USA. © 2014 John Wiley & Sons Ltd
CLINICAL TRIAL OF GINGIVAL DISPLACEMENT TECHNIQUES around the gingival margin, followed by insertion of a gingival cord (Ultrapakâ Cord #00¶) with the aid of a packer (Fischer’s Ultrapak Packer, 45° small size¶). Then, Viscostat Clearâ was reapplied around the gingival margin, according to the manufacturer’s instructions. After 10 min, the cord was removed gently from the sulcus, and an air/water spray was applied to remove the astringent. Single cord technique was used to avoid additional mechanical trauma and focus on the cytotoxic effects of the different astringents employed. The cordless technique was also performed according to the manufacturer’s instructions: the gingival margin was gently air-dried, and Expasylâ** was applied around it for 2 min. The Expasylâ was then removed by an air/ water spray. Dental impressions were obtained with polyvinyl siloxane (Expressâ XT††) using a single-step doubleimpression technique. Casts were poured 1 h later to avoid bubbles caused by hydrogen liberation during polyvinyl siloxane polymerisation. A blinded examiner quantified IL-1b, IL-6 and TNFa levels (pg/lL) in GCF using cytokine-specific enzyme-linked immunosorbent assays‡‡ according to the manufacturer’s recommendations. Data analyses The SigmaStatâ software package§§ was used for data analyses. The Friedman test was used to analyse differences in ranked periodontal parameters (PD, GBI and PI) obtained at the three visits for each technique. Subjectively reported parameters (pain, stress and unpleasant taste) during gingival displacement were dichotomised following the Likert scale scores in ‘yes’ (2, 3, 4 or 5) or ‘no’ (1) and analysed by Fisher’s exact test or the chi-squared test, according to data distribution. CAL, tooth mobility, sensitivity to cold air and bleeding during and after the procedure were analysed using simple descriptive statistics, including the calculation of frequencies. Cytokine concentrations were analysed by one-way repeated-measures analysis of variance, followed by Tukey’s test. IL-1b data violated the assumptions of equality of variance ¶
Ultradent Products, South Jordan, UT, USA.
**Pierre Rolland, M erignac, France. ††
3M ESPE, St. Paul, MN, USA.
‡‡
Invitrogen Corporation, Carlsbad, CA, USA.
§§
Systat Software Corporation, San Jose, CA, USA.
© 2014 John Wiley & Sons Ltd
and normal distribution of errors, and data were transformed by ranking. A significance level of 95% was used for all analyses.
Results Twenty-four maxillary anterior teeth (15 vital; 9 nonvital) in 12 subjects (10 women and 2 men) with no sign of gingivitis were included in this study. The mean age of participants was 47 74 (range, 39–60) years. Mean values for periodontal parameters are presented according to gingival displacement technique in Table 1 and ranked in Tables 2 and 3. Tooth mobility, CAL, GBI, PD and PI values were homogenous in the two groups into each timepoint (Table 1). Considering the same treatment, neither of the two evaluated techniques resulted in a significant increase in PD, GBI or PI (Tables 2 and 3). No gingival bleeding was observed during or after gingival displacement in either group. No difference in CAL, tooth mobility, sensitivity to cold air or bleeding was observed in either group throughout the experimental period. Subjects reported significantly (P = 0014) more stress during conventional gingival displacement than during cordless displacement. The occurrence of pain (P = 0193) and unpleasant taste (P = 0221) did not differ between techniques (Table 4). Both gingival displacement techniques increased the mean concentrations of the three evaluated cytokines, with the highest concentrations (P < 0,001) observed in association with the conventional technique (Table 5).
Discussion This study was the first randomised clinical trial to compare the efficacy of conventional and cordless gingival displacement techniques using clinical, immunological and individual parameters. One previous study clinically compared these techniques, but only periodontal indices and subjective parameters were evaluated (4). Another study evaluated TNF-a levels in GCF after conventional gingival displacement, without comparison with other techniques (16). The null hypotheses of the present study were partially rejected, as the gingival displacement techniques affected inflammatory cytokine levels in GCF and patients’ stress during the procedure.
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H . R . S A R M E N T O et al. Table 1. Subject distribution for periodontal parameters at the three visits for each technique (Cordless, Expasyl; Conventional, Ultrapak Cord + Viscostat Clear) Subjects distribution
Parameter PD (mm) 1 2 Mean SD Median P* GBI 0 1 Median P* PI 0 1 Median P* Mobility 0 CAL 0
Before displacement
1 day post-displacement
10 days post-displacement
Cordless
Conventional
Cordless
Conventional
Cordless
Conventional
12 0 10 1 NE
12 0 10 1
12 0 10 1 0166
10 2 117 039 1
11 1 108 029 1 0359
12 0 10 1
11 1 0 0359
12 0 0
11 1 0 0580
10 2 0
12 0 0 NE
12 0 0
11 1 0 0359
12 0 0
12 0 0 NE
12 0 0
12 0 0 0359
11 1 0
12
12
12
12
12
12
12
12
12
12
12
12
PD, probing depth; GI, gingival index; PI, plaque index; CAL, clinical attachment level; NE, not evaluated. *Mann–Whitney U-test (confidence level: 95%).
Table 2. Mean ranks of probing depth (PD), gingival bleeding index (GBI) and plaque index (PI) for the Cordless technique group
Table 3. Mean ranks of probing depth (PD), gingival bleeding index (GBI) and plaque index (PI) for the Conventional technique group
Index
Time
n
Mean rank
P*
Index
Time
n
Mean rank
P*
PD
Before displacement 1 day post-displacement 10 days post-displacement Before displacement 1 day post-displacement 10 days post-displacement Before displacement 1 day post-displacement 10 days post-displacement
12 12 12 12 12 12 12 12 12
100 100 100 000 000 000 000 000 000
0368
PD
GBI
0368
PI
12 12 12 12 12 12 12 12 12
100 100 100 00 00 00 00 00 00
0135
0368
Before displacement 1 day post-displacement 10 days post-displacement Before displacement 1 day post-displacement 10 days post-displacement Before displacement 1 day post-displacement 10 days post-displacement
GBI
PI
0135
0368
*Friedman test (P < 005).
*Friedman test (P < 005).
The cordless technique used in this study employed Expasylâ, a gingival displacement material with a paste-like consistency that combines the haemostatic properties of aluminium chloride with the hygroscopic expansion of kaolin to provide moderate displacement of the gingiva approximately 2 min after its applica-
tion and contact with the GCF (8). However, the predictability and efficacy of this technique have not been established (17). Appropriately designed and conducted randomised clinical trials are considered to be the gold standard in assessing healthcare interventions (12). In clinical © 2014 John Wiley & Sons Ltd
CLINICAL TRIAL OF GINGIVAL DISPLACEMENT TECHNIQUES Table 4. Subjective parameters reported by subjects after gingival displacement Parameter Pain Yes No Unpleasant taste Yes No Stress Yes No
Cordless
Conventional
P
2 10
6 6
0193*
4 8
8 4
0221†
0 12
6 6
0014*
*Fisher Exact test (P < 005). Qui-square test (P < 005).
†
Table 5. Mean cytokine concentration (pg/lL) standard deviation (SD) before (control) and after treatments Cytokine (pg/ll SD) Technique
IL-1b
IL-6
TNF-a
Baseline Cordless Conventional
60 04A 1573 13B 1793 07C
287 03A 1182 13B 1387 08C
461 04A 678 05B 812 05C
Capital letters denote statistically significant differences into the same column (Tukey’s test, P < 005).
situations, two or more teeth can receive gingival displacement through different techniques at the same time. However, to avoid an overlapping effect and confounding results, we used the crossover study model. In the present study, a 10-day wash-out period was used based on a previous study finding that the tissue damage caused by conventional gingival displacement is histologically resolved after this period (18). The main disadvantage presented in the adoption of a crossover model in the clinical routine of this study was the fact that it would be necessary one more clinical session to make a transfer impression incorporating the metal substructures previously to the ceramic application. Sample size calculation took into account the main outcome of this study, considering immunological parameters (IL-1b, IL-6 and TNF-a levels) reported by another study (13). Other secondary outcomes, such as periodontal indices, bleeding and self-reported subjective parameters, were also evaluated. Baseline values for these parameters were similar between groups, and no difference in periodontal indices was © 2014 John Wiley & Sons Ltd
observed between groups at any timepoint (baseline, 1 day and 10 days post-displacement). Furthermore, subjective assessments of pain and unpleasant taste did not differ between groups. Another study (4) with a larger sample (n = 60) also found no difference in periodontal indices between areas treated with conventional and cordless techniques, except for the gingival index. The authors reported that bleeding during and after displacement was induced only by the conventional technique in approximately 30% of subjects (4). In contrast, we observed no bleeding in our study subjects. The occurrence of gingival bleeding in the previous study was probably due to the use of a non-impregnated cord and no haemostatic solution, whereas we performed conventional gingival displacement with a non-impregnated cord and an aluminium chloridebased astringent solution. Although our sample size did not provide adequate statistical power to measure secondary outcomes, a significant difference in patient-reported stress in favour of the cordless technique was observed between groups. This result may be explained by the difficulty of performing the conventional technique, which depends on the operator’s familiarity, consumes much clinical time and leads to bleeding and patient discomfort (16). All volunteers of this study presented thick gingival biotype, which is more resilient and tend to be more resistant to mechanical trauma. Thus, the minimisation of this trauma caused by gingival displacement in the stimulation of inflammatory cytokines production, which would be a confounding factor, was minimised focusing on the cytotoxic effects of the astringents employed. During gingival displacement for prosthodontic purposes, mechanical trauma and astringents may induce a gingival inflammatory response (5), which increases GCF volume due mainly to the presence of inflammatory exudate (10). This exudate is composed primarily by pro-inflammatory cytokines of innate immunity (e.g. IL-1b, IL-6 and TNF-a) (11). In this study, both gingival displacement techniques increased IL-1b, IL-6 and TNF-a concentrations compared with baseline. The presence of GCF may significantly compromise the quality of dental impressions. To avoid this effect, the sulcus must be dried using chemical products, such as astringents. Aluminium chloride is a widely used astringent that acts predominantly via the
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H . R . S A R M E N T O et al. precipitation of proteins and inhibition of plasma protein transcapillary movement (17). Both techniques used in this study employed aluminium chloridebased products. The conventional technique produced the highest cytokine levels. This result is in agreement with that of another study (19), which showed that the same cordless technique resulted in more effective sulcus drying compared with epinephrine-impregnated cords. Moreover, another study showed that the Expasylâ (Pierre Rolland, M erignac, France) cordless technique resulted in a higher percentage of histologically observed intact junctional epithelium compared with the conventional technique (20). The results of this study indicate that the cordless technique is a more conservative periodontal treatment that is less stressful for patients. However, as observed in another study (19), the cordless technique provided narrower sulcus opening compared with the use of retraction cords in many cases in the present study. The objective of this study was not to evaluate the relative effectiveness of gingival displacement techniques or impression accuracy; however, further research should focus on these issues because scanning techniques are available. Even though gingival recession and pocket depth could be monitored by consecutive dental impressions as previously described (21), in the design of this study, the trauma caused to the tissue could mask the results increasing marginal recession (22). Moreover, the positive attributes of each displacement technique should be associated with the specific challenges presented by individual patients.
Conclusions Cordless gingival displacement resulted in lower proinflammatory cytokine levels in GCF and less patient stress compared with the conventional technique.
Acknowledgments The present study was approved by the local ethics committee and registered in the ClinicalTrials.gov database. The authors thank Labordental Distributor of Dental Products for providing some of the materials used in this study. H.R.S. is grateful to CAPES/ Brazil for an MSc scholarship. This study was supported by FINEP/Brazil (Grant no. 1407/10,
Agreement no. 01.11.00.88.00) and CAPES/Brazil (no. 23038.028455/2009-12).
Disclosure No conflict of interests declared.
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