ORIGINAL ARTICLE

RK Henry M Carkin

Authors’ affiliations: RK Henry, M Carkin, Division of Dental Hygiene, The Ohio State University, Columbus, OH, USA Correspondence to: R. K. Henry Division of Dental Hygiene The Ohio State University 3082 Postle Hall 305 W 12th Ave. Columbus OH 43210, USA Tel.: 614 292 2089 Fax: 614 292 8013 E-mail: [email protected]

The effect of gum chewing on sensitivity associated with in-office whitening procedures Abstract: Objectives: Tooth sensitivity is the most common side effect of in-office tooth-whitening procedures. The purpose of this study was to determine whether chewing gum containing 0.6% casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) before tooth whitening would reduce tooth sensitivity during an in-office whitening procedure. Methods: Thirty participants were enrolled and randomized into three groups as follows: group 1 was instructed to not chew gum during the study period; group 2 chewed five pieces of gum (with 0.6% CPP-ACP) for 10 min each day 1 week before whitening; and group 3 chewed five pieces of gum (without CPP-ACP) for 10 min each day 1 week before whitening. All participants had their teeth whitened with a 30% hydrogen peroxide in-office whitening procedure. The participants’ shades of teeth were evaluated with a spectrophotometer four times during the study: at the initial screening visit, immediately before whitening, immediately after whitening and 1 week after whitening. Participants’ sensitivity levels were evaluated each time the shades were evaluated and additionally at 24 h after whitening using a 100-mm visual analogue scale. Results: Thirty participants were enrolled in the study. The average shade change was 2.27 (2.07). The average sensitivity for all groups at visit 1 was 5.12 (13.94). The average sensitivity for all groups after whitening was 19.81 (13.95). There were significant differences in sensitivity between groups 2 and 3 (P = 0.02), but neither group was significantly different from the control group (P = 0.86, P = 0.07). Conclusions: Chewing gum before whitening, including gum with CPP-ACP, did not reduce sensitivity during in-office whitening procedures. Key words: chewing gum; hydrogen peroxide; in-office whitening; sensitivity; tooth whitening

Dates: Accepted 31 January 2015 To cite this article: Int J Dent Hygiene 13, 2015; 308–314 DOI: 10.1111/idh.12136 Henry RK, Carkin M. The effect of gum chewing on sensitivity associated with in-office whitening procedures. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd

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Introduction Current tooth-whitening products use various strengths of hydrogen or carbamide peroxide. The exact mechanism of teeth whitening is not clear. Some studies have shown that the peroxides form free radicals and anions that decompose intrinsic organic coloured molecules in the enamel (1). Another study has shown radicals and anions oxidize the organic matrix of the enamel (2). In either case, the peroxide diffuses through the enamel and into the dentin to whiten the teeth (1, 3, 4). There are many options for tooth whitening with peroxide including toothpaste, whitening gels, over the counter strips and professionally dispensed trays

Henry and Carkin. Effect of gum chewing on sensitivity and whitening

or nightguards; but one common side effect is sensitivity. Tooth sensitivity is the most common side effect of toothwhitening procedures, followed by gingival sensitivity or irritation (5). The movement of the peroxide molecules through the tubules and into the pulp can cause stimulation of the nerves, causing pain and sensitivity during and after whitening (6–8). In one study evaluating sensitivity with take-home whitening trays, 50% of subjects reported mild sensitivity, 10% reported moderate sensitivity and 4% reported severe sensitivity. Sensitivity lasts up to 2 weeks after the whitening procedure is completed (9). In-office whitening procedures are shown to have greater sensitivity than take-home whitening modalities. Studies show 63–90% of patients report mild-tomoderate sensitivity with in-office whitening (6, 10–13). Gingival sensitivity is more common during in-office whitening than home whitening procedures (10, 14). To prevent or decrease sensitivity associated with whitening, several strategies have been tested. Potassium nitrate gel at a 5% concentration has been used in trays for 30 min before whitening. Potassium nitrate used in this manner significantly decreased the sensitivity experiences during the first 24 h after whitening when compared to a placebo (15). A combination of fluoride and potassium nitrate has also been investigated (6, 16, 17). In one study, a combination of 5% potassium nitrate and 1000 ppm (0.2%) sodium fluoride gel was used after nightguard whitening. The use of a potassium nitrate and sodium fluoride gel alleviated sensitivity and allowed patients to continue with the whitening regimen (17). Bonafe et al. (16) found that a 5% potassium nitrate with 2% sodium fluoride gel applied before whitening procedures did not decrease the incidence of sensitivity but it did decrease the intensity of the sensitivity. Another study found that a 5% potassium nitrate and 2% sodium fluoride gel used before in-office bleaching decreased the incidence of sensitivity (6). Additionally, the use of potassium nitrate toothpaste before whitening has been shown to reduce sensitivity during and after tooth-whitening procedures (18–20). Another option for reducing tooth sensitivity is the use of non-steroidal anti-inflammatories before whitening. Ibuprofen, a non-steroidal anti-inflammatory drug, works by blocking the chemical prostaglandins that are responsible for pain. Charakorn et al. (21) demonstrated that a 600-mg dose of ibuprofen 30 min before in-office whitening decreased sensitivity during

the procedure. Another mechanism to decrease sensitivity is the use of a glutaraldehyde and 2-hydroxyethyl methacrylate desensitizer. Glutaraldehyde and 2-hydroxyethyl methacrylate were placed on the labial surfaces of teeth before in-office whitening was shown to significantly reduce sensitivity compared to a placebo (22). While many of these treatment options have shown to reduce sensitivity with whitening, the incidence of sensitivity is still prevalent, most notably during in-office whitening procedures. Casein phosphopeptides (CPPs) are safe for use in oral care products and can function as a carrier for calcium, phosphate and fluoride ions (23). One example of CPP functioning as a carrier is with amorphous calcium phosphate (ACP). Casein phosphopeptide-amorphous calcium phosphate effectively inhibits demineralization of enamel, promotes remineralization, inhibits caries formation and causes regression of white spot lesions (24). Casein phosphopeptide-amorphous calcium phosphate added to at-home whitening gels has shown a reduction in sensitivity (25). In a study comparing 10% CPP-ACP gel to a 2% sodium fluoride gel, a placebo found that the 10% CPPACP gel and the 2% sodium fluoride gel both reduced the sensitivity to a moderate level but were not different (26). Chewing gum is one of the most recent desensitizing treatments studied. One study determined that chewing gum after whitening can decrease sensitivity; sugar-free gum and sugarfree gum with CPP-ACP decreased sensitivity equally (11). Studies of using chewing gum before whitening to alleviate sensitivity have not been published. The aim of this study was to compare tooth sensitivity during and after in-office whitening with 30% hydrogen peroxide following a week of chewing gum with CPP-ACP, sugarless gum with no CPP-ACP or no gum chewing.

Study population and methodology Study type

The Institutional Review Board at The Ohio State University, Columbus, OH, reviewed and approved the study procedure and consent. This double-blind randomized control clinical study utilizes a sample of 30 participants (N = 30) who responded to a study advertisement and met established inclusion criteria (Table 1). Recession was not included in the

Table 1. Inclusion and exclusion criteria Inclusion criteria

Exclusion criteria

18 years of age or older In general good health (ASA I or II) Tooth shade of A3 or darker on all anterior teeth Presence of anterior teeth (canine to canine)

Significant medical problems (ASA III or greater) Pregnant or nursing Presence of caries in anterior teeth as determined by a clinical examination Periodontal disease in anterior teeth as indicated by a PSR score of ≥3 Facial restorations on anterior teeth Tooth whitening in the last 6 months Evidence of gross pathology Internal tooth discolouration due to tetracycline staining, fluorosis or pulpless teeth Milk protein allergies Taking pain relieving medication on a daily basis

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criteria for participation in the study. Study participants were informed that the areas of recession would not whiten. This criterion was not included for participation to allow for a population that best reflected the general population. Informed consent was obtained before treatment began.

the 100-mm line on the VAS. One end of the line was labelled ‘no pain’, and the other end of the line was labelled ‘severe pain’. Data were analysed using PROC MIXED (mixed model) in SAS 9.3 (SAS Institute, Cary, NC, USA). A Tukey adjustment was used on all significance levels to correct for multiple comparisons.

Study design

Study participants were randomly assigned into one of three groups: group 1 (n = 10) was instructed not to chew any type of chewing gum during the study period; group 2 (n = 10) chewed sugar-free gum with 0.6% CPP-ACP (Trident Xtra Care; Cadbury Adams USA LLC, Parsippany, NJ, USA); group 3 (n = 10) chewed sugar-free gum without calcium casein peptone-calcium (Orbitz; William Wrigley Jr. Co., Chicago, IL, USA). All participants received a dental screening to evaluate for clinically visible caries, periodontal status and medical history 1 week before the start of tooth whitening. All study participants were given the same oral hygiene instructions which included brushing with a soft toothbrush provided by the researchers (Oral B Cross Action Soft; Procter and Gamble, Cincinnati, OH, USA), toothpaste containing sodium fluoride (Crest Cavity Protection; Procter and Gamble) and dental floss (Oral B Satin Floss; Procter and Gamble) twice a day. All products were given to the study subjects to help control for extraneous variables related to home oral hygiene products and habits. Subjects were then given instructions on chewing gum specific to their randomized group assignment. Groups 2 and 3, who were instructed to chew gum, were instructed to chew five pieces of gum throughout the day for 10 min, leaving at least 1 h between each piece of gum. The regimen for gum chewing was the same between the two groups, the only difference being the type of gum chewed. Study participants were given a log to track their gum chewing and returned the log 1 week later at the next study visit. Group 1 was asked to refrain from chewing gum for the week prior to the whitening treatment. Study participants returned 7 days after the initial visit to have the whitening treatment completed. Shades were recorded using a spectrophotometer (Vita Easyshade; Vident, Brea, CA, USA) on tooth numbers 6–11 and 22–27. Tooth sensitivity was recorded using a 100-mm visual analogue scale (VAS). Study participants were asked to mark a location on

Study procedures

Two examiners, the primary investigator and a research assistant, were trained and calibrated on whitening and study procedures. The study consisted of a total of four visits to the dental clinic. The first visit (1) included inclusion/exclusion screening, a medical history, consent, a dental screening, study instructions and evaluation of shade and sensitivity. The study timeline and data collected at each visit are outlined in Table 2. Whitening procedure

Participants’ lips were retracted and isolated using whitening product manufacturer-provided retractors and gauze (Dash; Philips Oral Healthcare, Andover, MA, USA). Gingival tissue was isolated around all teeth with a light-cured resin dam (Liquidam; Philips Oral Healthcare). A 2-mm-thick application of 30% hydrogen peroxide whitening gel (Dash; Philips Oral Healthcare) was applied to tooth numbers 6–11 and 22–27 for 15 min. Subsequently, whitening gel was removed with highvolume evacuation, and a new application of whitening gel was applied. This application procedure was followed for a total of three 15-min whitening sessions. After the last application, whitening gel was rinsed and evacuated, and retractors were removed. Study participants were instructed to use only the oral hygiene products given to them by the researchers and to refrain from chewing gum after the whitening was completed. Shades were evaluated and recorded at four points throughout the duration of the study: the initial screening visit, before whitening, immediately after whitening and 1 week after whitening. Shades were evaluated with the spectrophotometer placed halfway between the incisal and cervical edges of the teeth and halfway between the distal and mesial edges. Shade

Table 2. Study timeline by group assignment Day

Group 1 (control)

Group 2

Group 3

1 (visit 1)

Screening and consent Randomization Instructions Shade evaluation and VAS In-office whitening Shade evaluation and VAS

Screening and consent Randomization Gum and instructions Shade evaluation and VAS In-office whitening Shade evaluation and VAS Collect gum log VAS Shade evaluation VAS

Screening and consent Randomization Gum and instructions Shade evaluation and VAS In-office whitening Shade evaluation and VAS Collect gum log VAS Shade evaluation VAS

7 (visits 2.1 and 2.2)

8 (visit 3) 14 (visit 4)

VAS, visual analogue scale.

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VAS Shade evaluation VAS

Henry and Carkin. Effect of gum chewing on sensitivity and whitening

values (Table 3) were analysed using descriptive statistics and a t-test. Sensitivity assessment

Sensitivity was evaluated and recorded at five points throughout the duration of the study using a VAS. Sensitivity values were recorded at the initial screening visit, before whitening, immediately after whitening, 24 h after whitening and 1 week after whitening. Sensitivity values were analysed using PROC MIXED (mixed model) with a Tukey adjustment for multiple comparisons.

Results Thirty participants were enrolled into the study and randomized into the three groups (Table 4). Two subjects did not

Table 3. Value-oriented Vita Easyshade* guide rankings used for colour assessment Value

Vita Easyshade

Assigned numerical colour ranking

Lightest

B1 A1 B2 D2 A2 C1 C2 D4 A3 D3 B3 A3.5 B4 C3 A4 C4

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Darkest

*Classical Vita Shade Guide is manufactured by Vident.

Table 4. Demographic data of study participants All study participants n = 30 Age Gender (%) Male Female Group 1, n = 10 Age Male Female Group 2, n = 10 Age Male Female Group 3, n = 10 Age Male Female

Mean = 32.1 (11.17) n = 9 (30.00) n = 21 (70.00) Mean = 29.5 (10.48) n=4 n=6 Mean = 32.5 (12.36) n=1 n=9 Mean = 34.3 (11.24) n=4 n=6

complete whitening treatment during the study, one subject in group 1 and one subject in group 3. The average shade change for all groups was 2.27 (2.07). T-tests showed no significant differences in tooth shade change from screening or from visit to before whitening between the three groups; however, groups 1 and 3 show a significant difference (P = 0.0318) in raw average tooth shades. Group 3 consistently showed an average tooth shade 0.053–3.12 points higher than the average tooth shade in group 1 across all visits, but all three groups showed similar patterns of tooth shade change across visits (Fig. 1). A t-test revealed a significant difference between tooth shade at visit 1 and tooth shade at visit 4 (P = 0.017) across all three groups. No other significant differences were found between tooth shades at any other pair of visits overall, or between any pair of visits within groups. The mean sensitivity for all groups at visit 1 was 5.12 (13.94). The values before whitening at visit 2 were similar at 5.26 (13.95). After whitening was completed, overall mean of sensitivity increased to 19.81 (13.95). Twenty-four hours after whitening, the mean sensitivity was at a level of 18.12 (13.98). Sensitivity levels dropped to 4.55 (13.96) a week after the whitening was completed. The means of each visit by group are listed in Table 5. The mixed model output indicates that group and visit are significant predictors of mean VAS score (Table 6), demonstrating that all three groups behaved the same through the duration of the study. The interaction between group and visit was found not to be significant (P = 0.68). A Tukey–Kramer adjustment for multiple comparisons showed significant differences between groups 2 and 3 (P = 0.02), but neither group was significantly different from the control group (P = 0.86, P = 0.07) (Table 7). No significant differences were found when comparisons were made by group and specific visits (Table 8). An analysis on sensitivity levels and gender was found not to be significant (P = 0.12). Analysis was not conducted on sensitivity levels as related to participants’ age.

Discussion The subjects in this study experienced less shade change than in other studies. The average shade change in all groups for this study was 2.27 (2.07), and shade change was similar across all three groups. Tang and Millar (11) used a 15% hydrogen peroxide activated with a light and found an average of 4.8 shade changes when measuring with the Vita shade tabs. A study using 35% hydrogen peroxide found that the shade change was 4.1 measuring with Vita shade tabs and 4.4 measuring with a spectrophotometer (16). Pal e found a shade change of 3.75 to 4.87 using 28% hydrogen peroxide with a light-emitting diode activation (15). Others have found shade changes from 6.1 to 11 measuring with Vita shade tabs (6, 22). While the shade change was less than in other studies, gum chewing did not inhibit the whitening activation because all three groups had similar average shade changes. Not all studies evaluating shade change use an objective measurement, and many employ the Vita Classical Int J Dent Hygiene 13, 2015; 308--314 |

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Interaction plot of group and time

15 0

5

10

Mean VAS

20

25

30

Group Overall Group 1 Group 2 Group 3

1

2B

2A

3

4

Visit

Table 5. Mean visual analogue scale scores by group and visit

Group 2

Group 3

Visit overall means

Visit

N

Mean

Standard error

1 2.1 2.2 3 4 Overall 1 2.1 2.2 3 4 Overall 1 2.1 2.2 3 4 Overall 1 2.1 2.2 3 4

10 10 10 7 9 46 10 9 9 6 9 43 10 9 9 7 8 43 30 28 28 20 26

5.00 3.40 24.40 23.71 3.56 12.43 9.60 10.00 26.00 16.17 7.56 13.99 0.90 2.44 9.11 14.28 2.50 5.29 5.12 5.26 19.81 18.11 4.55

1.63 1.0349 6.5578 6.6142 1.3654 2.1243 4.8813 5.6150 6.9262 5.1408 5.3648 2.163 0.6904 1.3551 5.4555 8.7088 2.2281 2.2261 2.5449 2.6371 2.6371 3.125 2.7374

Table 6. Type 3 tests of fixed effects

Group Visit Group*visit

Num d.f.

Den d.f.

F-value

Pr > F

2 4 8

116 116 116

4.25 7.86 0.71

0.0165

The effect of gum chewing on sensitivity associated with in-office whitening procedures.

Tooth sensitivity is the most common side effect of in-office tooth-whitening procedures. The purpose of this study was to determine whether chewing g...
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