Effect of a Sugar-free Chewing Gum Containing Magnolia Bark Extract on the Development of Caries Lesions in Healthy Adult Volunteers: a Randomized Controlled Intervention Trial

Introduction

Dental caries incidence in adults is similar to that in children and adolescents, but few caries preventive agents have been evaluated for effectiveness in adult populations. Magnolia bark extract (MBE) is a plant extract obtained from the bark of magnolia that has been widely used in traditional Chinese medicine for 2,000 years, Magnolia officinalis has been used for the treatment of acute pain, diarrhea, coughs and urinary problems. The two main constituents of the bark of this medicinal plant are magnolol and honokiol. They are known to possess a variety of pharmacological properties, including therapeutic-related activities central nervous system inhibition anti-inflammatory effects, antimicrobial activity, antioxidative activity and freeradical scavenging activity. Magnolol andhonokiol have also been reported to inhibit the growth of Streptococcus mutans, Streptococcus sobrinus, Porphyromonas gingivalis, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans, Capnocytophaga gingivalis and Veillonella disper in vitro and reduce the dental caries values in rats. Consequently, the antimicrobial properties of MBE against cariogenic and plaque bacteria have showed promising results. The effect of chewing gums containing MBE and xylitol on different variables related to caries and gingivitis in a sample of adult volunteers with a high risk for caries will be evaluated. The main result of that double-blind randomized controlled interventional trial will be that chewing gum containing MBE was more effective in reducing plaque acidogenicity, salivary mutans streptococci concentration and gingival bleeding compared to a xylitol and sugar-free chewing gum.

Materials and Methods A two-year, placebo-controlled, double-blind, randomized clinical trial sponsored by Perfetti Van Melle that tests the effects on caries lesions development of daily use of a chewing gum containing Magnolia Bark Extract and xylitol will be conducted.

The trial will take place in the dental clinics located in the dental schools of the University of Sassari and Milan. The study will be approved by the Ethical Committee of the University of Sassari.

Study Population Principal inclusion criteria will be age range (30-55 years) and the presence of at least one cavitated caries lesion, but no more than three. Subjects with systemic disease that interfered with the oral ecosystem will be excluded. The caries criterion will be designed to include participants who are at risk of forming new lesions. Sample size for preliminary screening will be calculated on the basis of previous studies regarding caries prevalence (about 26%) in adults [Campus et al, 2011] and relative odds ratio 2.88 of incidence, as reported in literature [Ito et al, 2011]. Thus, the theoretical sample size for preliminary screening will be set to 1200 subjects.