Gingivitis Reducing Effect of Dentifrices Containing Zinc Citrate

Original Article Int J Clin Prev Dent 2017;13(4):217-222 ㆍ https://doi.org/10.15236/ijcpd.2017.13.4.217 ISSN (Print) 1738-8546 ㆍ ISSN (Online) 2287-6197 Gingivitis Reducing Effect of Dentifrices Containing Zinc Citrate Soo-A Kim 1, Ja-Won Cho 1,2 1 Department of Oral Health, Graduate School of Health and Welfare, Dankook University, 2 Department of Preventive Dentistry, College of Dentistry, Dankook University, Cheonan, Korea Objective: This study tried to explore the preventive effect of zinc citrate-containing dentifrices on oral diseases based on their gingivitis reducing effect by measuring and comparing the changes of gingival-periodontal indices and dental plaque in each time period. Methods: A total of 120 adults with mild to moderate gingivitis were selected and divided into experimental group and control group (60 adults per group). Using experimental and control dentifrices containing respectively zinc citrate and just dental-type silica, we measured and recorded Calculus, Papillary Marginal Attachment (PMA), Gingival, Patient Hygiene Performance (PHP), and Plaque index at four time points (before, and 1, 2, 4 weeks after, oral examination) over the study period. Results: One week after the examination, statistically significant gingivitis reducing effect was found in all indices except for Calculus index in the experimental group. At 2 and 4 weeks after the examination, gingivitis was also significantly reduced in the experimental group (p<0.05). Conclusion: Zinc citrate-containing dentifrices have a remarkable effect on reducing gingivitis and mitigating bad breath. Keywords: toothpastes, dentifrices, gingivitis Introduction Corresponding author Ja-Won Cho Department of Preventive Dentistry, College of Dentistry, Dankook University, 119 Dandae-ro, Dongnam-gu, Cheonan 31116, Korea. Tel: +82-41-550-1953, Fax: +82-41-553-6582, E-mail: priscus @dku.edu Received October 22, 2017, Revised December 6, 2017, Accepted December 6, 2017 Periodontal disease is one of the two major oral diseases along with dental caries. It is characterized by periodontal pocket formation, alveolar bone loss, and tooth mobility caused by inflamed tissues surrounding the tooth [1] and has higher prevalence in older people [2]. In addition, this disease is classified into gingivitis and periodontitis depending on its severity. The former is relatively mild, recovers rapidly, and is found only in gums (soft tissue), while the latter is advanced to gums and even to bone surroundings [3]. Tooth brushing is an act eliminating dental plaque formed on the surface of teeth and gums using dentifrices, which is recommended as the most basic method for oral care. Accordingly, it may prevent oral diseases such as dental caries and periodontal disease and reduce bad breath as well [4]. Dentifrice is an accessory used in the process of tooth brushing to brush tooth surface, commonly referred to as toothpaste. It is not a prescription, but an over-the-counter (OTC), drug such as soap or detergent. It is called dental cream dentifrice in Copyright c 2017. Korean Academy of Preventive Dentistry. All rights reserved. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/ by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 217

International Journal of Clinical Preventive Dentistry America and dentifrice in Japan. However, only for dentifrices currently on the market containing ingredients that may react pharmacologically, they are denominated as toothpaste because belonging to medicine [5]. The fundamental role of dentifrices is to raise efficiency in eliminating glycoproteins and dental plaques attached on the tooth surface [6]. Recently, other ingredients are additionally mixed to achieve a variety of purposes including elimination of bad breath, reduction of gingivitis, inhibition of calculus formation, prevention of tooth sensitivity and dental caries, and reduction of oral-specific bacteria [6-8]. Major ingredients widely used in toothpaste include abrasive, surfactant, binding agent, and humectant. Other ingredients such as water, favoring agent, sweeting agent, preservative, and other major ingredients for oral prevention are mixed in toothpaste. Coloring or bleaching agents are also mixed [5]. In particular, many dentifrices have been developed for mitigating bad breath and treating tooth sensitivity. Among these, zinc citrate is now highlighted because it can inhibit bacterial growth and reduce bad breath [9-11]. Meanwhile, antiplaque properties of zinc have been widely known over a long period of time. Zinc ions in dental plaque inhibit its metabolism by maintaining high ph even in the presence of sugar. They prevent plaque from being accumulated on tooth surface as well. Having no side effects such as destruction of normal bacteria despite the long-term use of zinc-containing products, they may exert greater influence on inhibiting dental plaque accumulation when used for an extended period of time. Moreover, it has been reported that zinc contributes to inhibiting calculus formation due to its anti-crystallizing property as an ancillary role of zinc ions [12,13]. It has been also shown that zinc puts a restraint on bacterial growth in the end by inhibiting bacterial acid synthesis and their metabolism in dental plaque. These metal ions are preserved in dental plaque by binding to extracellular and intracellular components [14-16]. Accordingly, in this study, we examined the preventive effect of zinc citrate on oral diseases based on its gingivitis reducing effect after using dentifrices containing zinc citrate with ability to reduce bad breath and suppress bacterial growth. Table 1. Sex and age distribution of subjects Sex Age (yr) Total 20s 30s 40s 50s Total (n) 120 45 24 31 20 Male (n) 45 16 7 16 6 Female (n) 75 29 17 15 14 Materials and Methods 1. Subjects 1) Study subjects In this study, 120 adult volunteers with early gingivitis aged 20 years or more to less than 60 years were recruited as subjects. After obtaining consent forms for study participation, we conducted a study for 4 weeks from December 2016 to January 2017, aimed at subjects who brush regularly their teeth 2 times or more a day. But, as a result of dental examination, those with the following conditions unsuitable for study were excluded: 1) subjects without gingivitis, 2) subjects equipped with orthodontic appliances or partial or complete dentures, 3) subjects treated recently with antibiotics within a year. Demographic characteristics (sex and age distribution) of the subjects were summarized in Table 1. 2) Study dentifrices Dentifrices were divided into experimental dentifrice (S) and control dentifrice (T). Major ingredients in each dentifrice were shown in Table 2, 3. 2. Study methods 1) Acquisition of institutional review board (IRB) This study was conducted after approved from Dankook University IRB (Approval No.: DKU 2015-10-012-001) complying with relevant regulations. Subjects also received sufficient explanations about study purposes and submitted consent forms for participation before the study. 2) Classification of subjects This examination was designed as a parallel comparison, random distribution, double blind, and control group study. It was conducted for four weeks. Subjects, enrolled in this study Table 2. Major ingredients in the experimental dentifrice (S dentifrice) Ingredient name Content (%) Dipotassium glycyrrhizate 0.01 Cetylpyridinium 0.05 Dental type silica 15.00 Zinc citrate (trihydrate) 0.50 Table 3. Major ingredients in the control dentifrice (T dentifrice) Ingredient name Content (%) Dental type silica 15.00 218 Vol. 13, No. 4, December 2017

Soo-A Kim and Ja-Won Cho:Gingivitis Reducing Effect of Dentifrices Containing Zinc Citrate by signing voluntarily an examination consent form, were selected by on-site evaluation based on inclusion or exclusion criteria. Selected subjects were randomly assigned to one of two groups (experimental group and control group) in the order of enrollment after a run-in period for one week. Each group included 60 subjects. 3) Method and period of using dentifrices Dentifrices were appropriately assigned to each group. Subjects brushed their teeth two times or more a day for 4 weeks (28 days) using a rotation method for 3 minutes. 4) Method of observation and screening (by visit) (1) Baseline visit, week 0: This visit was done for screened subjects at intervals of one week or more. They were examined using oral examination indices first and were also educated about a rotation tooth brushing method after their usual dietary patterns were investigated. Afterwards, relevant dentifrices and explanations were provided to them to make them brush their teeth with the dentifrices. (2) Closing visit, week 1: This visit was done at one week after visit 1 (week 0) to check adverse events and measure oral examination indices. (3) Closing visit, week 2: This visit was done at two weeks after visit 1 (week 0) to check adverse events and measure oral examination indices similarly to visit 2. (4) Closing visit, week 4: This visit was done at four weeks after visit 1 (week 0) to check adverse events and measure oral examination indices similarly to visit 2. 5) Oral examination Subjects were examined a total of four times (before, and 1, 2, 4 weeks after, using dentifrices) by Calculus, PMA, Talbott- Mandel-Chilton Gingival, Loe-Silness Gingival, and Quigley- Hein Plaque index (Truesky modification). (1) Calculus index (CI): Among simplified oral hygiene indices, the simplified calculus index was employed to measure and record calculus conditions. It was graded based on the following criteria [17-19]. <Grading criteria> 0: No observable calculus debris. 1: Calculus covering one-third of the buccal tooth surface. 2: Calculus covering two-thirds of the buccal tooth surface, or subgingival calculus attached on the relevant area in other, not circular, forms. 3: Calculus attached on the trisected anterior teeth crown. (2) Papillary marginal attachment index (PMA index): To investigate gingival conditions in the anterior tooth, we divided respectively 10 gingival units based on five interdental papillae in the upper and lower anterior tooth (central incisor, lateral incisor, and canine) into three parts such as papillary, marginal, and attached gingiva, and summed the number of mesial gingivae. 1 or 0 point was respectively given if gingivitis was observed in the examined area or not. The extent of gingivitis was then measured using PMA index. Maximum point per jaw was 15. Maximum and minimum point in the upper and lower jaws were respectively 30 and 0 [20,21]. (3) Talbott-mandel-chilton gingival index (GI): This index is scored based on a 0-3 scale. In accordance with the grading standard of Loe (Talbott, Mandel and Chilton modification), we divided respectively buccolingual gingival margins around teeth into mesial, distal, and central gingivitis, and measured six parts. Individual GI was calculated by dividing the sum of measurements by the number of target teeth (16th, 11th, 26th, 46th, 31th, and 36th) [22]. <Grading criteria> 0: Normal gingiva. 1: Mild gingivitis - Slight color change and slight edema. 2: Intermediate gingivitis. 3: Extreme gingivitis. (4) Loe-silness gingival index (GI): This index was designed by Loe and Silness. It shows the location and progress of gingivitis. We divided a tooth surface into several parts as shown in Table 4 so as to examine gingivae in the relevant area. GI was calculated with the following formula [21,23]. GI= Table 4. Target teeth and division standards (buccal surface)6 (lingual surface)6 Sum of total grades Number of total examined tooth surfaces <Grading criteria> 0: No observable inflammation and healthy state. 1: Slight change in color and slight edema but no bleeding on probing. 2: Redness, edema and glazing, bleeding on probing. 3: Marked redness and edema, ulceration with tendency to spontaneous bleeding. (5) Patient hygiene performance index (PHP Index): Before examination, tooth surface was stained by disclosing agents and slightly washed by water. Considering the remaining colored state, labial (or buccal) and lingual surface of each tooth were (labial surface)1 1(labial surface) 6(buccal surface) 6(lingual surface) www.ijcpd.org 219

International Journal of Clinical Preventive Dentistry examined. In addition, dividing equally a tooth surface into five parts, mesial, distal, incisal, occlusal, cervical, and central plaques, as well as buccal surface of the left-right maxillary first molar, labial surface of the upper-lower anterior tooth, and lingual surface of the left-right lower mandibular first molar, were examined. Plaque state was evaluated by a 0-5 point scale. 1 or 0 point was respectively given based on whether or not dental plaque was attached in the examined area. Maximum point per surface is 5. Dividing points by six examined teeth, maximum and minimum index points are 5 and 0, respectively [24,25]. (6) Plaque index: Before examination, tooth surface was stained by disclosing agents and were slightly washed by water. Considering the remaining colored state, plaque index was measured with a probe and mouth mirror on the dental unit-chair regarding the teeth (#16, #11, #26, #36, #31, and #46). Grades of dental plaque were determined by Quigley-Hein plaque index [26] (Turesky modification [27]). That is, we calculated the average by dividing gingivae per target tooth by two tooth surfaces (buccal and lingual surface) and dividing again the sum of these values by the number of teeth. <Grading standards> 0: No observable dental plaque on tooth surface. 1: Punctiform dental plaque in the gingival margin. 2: Dental plaque attached on the line along the gingival margin (applicable to 1 mm or less dental plaque). 3: Dental plaque covering one-third of the buccal tooth surface. 4: Dental plaque covering two-third of the buccal tooth surface. 5: Dental plaque covering more than two-third of the buccal tooth surface. 6) Statistical analysis Collected data were statistically analyzed using Microsoft Excel Program 2016 and IMB SPSS Statistics ver. 23.0 (IBM Co., Armonk, NY, USA). Statistical significance was set at p<0.05. Two-sample t-test and paired t-test were respectively employed to compare data between groups and within each group. Results 1. Results for gingival and periodontal examinations Measures and their variations were summarized in Table 5. 2. Results for dental plaque examinations Measures and their variations were summarized in Table 6. Discussion The major cause of oral diseases is uncontrolled dental plaque. To preserve our teeth in good condition, a number of factors including dental plaque or calculus, food debris, and exogenous pigments, should be eliminated. The primary way is tooth brushing. But, if trying to remove dental plaque and calculus on teeth just by tooth brushing, we face limitations in terms of effectiveness [28]. Accordingly, it is required to select good oral hygiene products, most importantly, dentifrice and toothbrush [29]. Dentifrices are largely classified into commonly used cosmetic and pharmacologically reacting therapeutic ones. In a special purpose, ingestable dentifrices were also cur- Table 5. Measures of gingival and periodontal indices and their variations Value Group Base After 1 week After 2 weeks After 4 weeks PMA S (n=60) 6.62±3.09 5.95±2.98* 5.42±2.54* 4.87±2.55* T (n=60) 7.15±4.01 7.05±4.11 6.75±3.61 6.62±3.70 p-value a 0.416 0.096 0.021 0.003 CI S (n=60) 0.29±0.20 0.30±0.21 0.29±0.24 0.31±0.22 T (n=60) 0.32±0.35 0.32±0.39 0.33±0.38 0.34±0.40 p-value a 0.635 0.700 0.530 0.537 LGI S (n=60) 2.20±2.03 1.95±1.69* 1.41±1.18* 1.20±1.06* T (n=60) 2.22±2.22 2.18±2.05 1.93±1.74 1.75±1.57* p-value a 0.949 0.507 0.059 0.026 TGI S (n=60) 3.79±2.98 3.23±2.31* 2.46±1.80* 2.12±1.48* T (n=60) 3.86±3.21 3.64±2.97 3.15±2.43* 2.84±2.24* p-value a 0.906 0.403 0.079 0.038 Values are presented as mean±standard deviation. PMA: papillary marginal attached gingival index, S: experimental group, T: control group, CI: calculus index by oral hygiene index, LGI: gingival index by Loe and Silness, TGI: gingival index by Talbott, Mandel and Chilton. *p<0.05 by paired t-test between baseline and after. a p-value: p-value by two-sample t-test. 220 Vol. 13, No. 4, December 2017

Soo-A Kim and Ja-Won Cho:Gingivitis Reducing Effect of Dentifrices Containing Zinc Citrate Table 6. Measures of dental plaque-related indices and their variations Value Group Base After 1 week After 2 weeks After 4 weeks PHP S (n=60) 2.59±1.02 2.30±1.00* 1.84±1.30* 1.55±1.34* T (n=60) 2.59±0.79 2.46±1.10 2.08±1.03* 1.98±1.02* p-value a 0.987 0.411 0.279 0.048 PI S (n=60) 5.35±3.54 5.18±3.67 4.10±2.85* 3.02±2.11* T (n=60) 5.53±4.16 5.15±4.11 4.40±3.37* 4.01±3.13* p-value a 0.795 0.963 0.596 0.044 Values are presented as mean±standard deviation. PHP: patient hygiene performance index, S: experimental group, T: control group, PI: plaque index. *p<0.05 by paired t-test between baseline and after. a p-value: p-value by two-sample t-test. rently developed, which are taken into the mouth without tooth brushing [5]. Addy et al. [30] contended that varied ingredients should be added to the existing dentifrice ingredients. These dentifrices have a diversity of functions such as mitigation of bad breath, inhibition of calculus formation, and tooth whitening, besides their basic roles such as elimination of dental plaque, prevention of cavities and periodontal diseases. Major ingredients are composed of abrasive, humectant, binding agent, detergent, medicinal agent, sweeting agent, favoring agent, and others [31]. It has been reported that zinc, which is one of the mixed ingredients of dentifrices and an antimicrobial, is less poisonous, cheap, and does not cause tooth coloring, thereby it is very useful for preventing and controlling periodontal diseases and bad breath [12,13]. Accordingly, in the present study, we conducted a number of experiments to examine the effect of dentifrices on dental plaque-related indices and the gingivitis reducing effect by comparing two groups, 1) S group using experimental dentifrices with zinc citrate, 2) T group using control dentifrices without zinc citrate. A total of four visits were done to measure the relevant indices by making subjects maintain their usual dietary patterns and brush their teeth. As a result, when dentifrices containing zinc citrate were used, all oral examination indices except for CI showed significantly lower grades (p<0.05). For PMA indices in S and T groups, they were decreased from 6.62 and 7.15 at week 0 to 5.95 and 7.05 at week 1, 5.42 and 6.75 at week 2, and 4.87 and 6.62 at week 4, respectively. At 4 weeks after oral examination, results of the S group were significantly lower than those of the T group (p<0.05). For CI indices in S and T groups, they were altered from 0.29 and 0.32 at week 0 to 0.31 and 0.34 at week 4, respectively, showing no statistical significance (p>0.05). For Loe-Silness GI, results of S and T groups were decreased from 2.20 and 2.22 at week 0 to 1.95 and 2.18 at week 1, 1.41 and 1.93 at week 2, and 1.20 and 1.75 at week 4, respectively. At 4 weeks after oral examination, results of the S group were significantly lower compared to those of the T group (p<0.05). For Talbott-Mandel-Chilton GI, grades of S and T groups were declined from 3.79 and 3.86 at week 0 to 3.23 and 3.64 at week 1, 2.46 and 3.15 at week 2, and 2.12 and 2.84 at week 4, respectively. At 4 weeks after oral examination, results of the S group were significantly lower than those of the T group (p<0.05). As results of PHP index, grades of S and T groups before oral examination were 2.59 and 2.59, respectively. These grades were decreased to 2.30 and 2.46 at week 1, 1.84 and 2.08 at week 2, and 1.55 and 1.98 at week 4, respectively. At 4 weeks after oral examination, results of the S group were significantly lower than those of the T group (p<0.05). For PI index, results of S and T groups were decreased from 5.35 and 5.53 at week 0 to 5.18 and 5.15 at week 1, 4.10 and 4.40 at week 2, and 3.02 and 4.01 at week 4, respectively. Similarly, at 4 weeks after oral examination, results of the S group were significantly lower than those of the T group (p<0.05). Therefore, these results revealed that dentifrices containing zinc citrate exerted influence on eliminating dental plaque and reducing gingivitis, finally showing a greater gingivitis reducing effect at week 4 than the control ones. The present study examined the gingivitis reducing effect of dentifrices within a short period. Clinical studies over a few months from various angles should be conducted in the future to validate this effect. Conclusion To evaluate the gingivitis reducing effect of dentifrices containing zinc citrate, we selected 120 subjects and divided them into experimental and control groups (60 subjects in each group), and made them use dentifrices with or without zinc citrate for 4 weeks and finally investigated Calculus, PMA, Gingival, PHP, and Plaque index at four time points (before, and 1, 2, 4 weeks after, oral examination). Consequently, a greater gingivitis reducing effect was found in the experimental, com- www.ijcpd.org 221

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