Oxygen metabolism,oxidative stress and acid-base physiology of dental plaque biofilms

Dental plaque is a natural biofilm which has been a focus of attention for many years because of its known roles in caries and periodontal diseases. Acid production by plaque bacteria leads to the erosion of tooth mineral in caries, and the cariogenicity of plaque is related to population levels of acid-tolerant organisms such as mutants streptococci. However, the biofilm character of plaque allows for survival of a diverse flora, including less acid-tolerant organisms, some of which can produce ammonia from arginine or urea to counter acidification. Plaque is often considered to be relatively anaerobic. However, evidence is presented here that both supragingival and subgingival plaque have active oxygen metabolism and that plaque bacteria, including anaerobes, have developed defenses against oxidative stress. Even in subgingival plaque associated with periodontitis, measured residual oxygen levels are sufficient to allow for oxygen metabolism by organisms considered to be extremely anaerobic such asTreponema denticola, which metabolizes oxygen by means of NADH oxidases and produces the protective enzymes superoxide dismutase and NADH peroxidase. The finding that plaque bacteria produce a variety of protective enzymes is a good indicator that oxidative stress is a part of their everyday life. The biofilm character of plaque allows for population diversity and coexistence of aerobes, anaerobes and microaerophiles. Overall, agents that affect oxidative metabolism offer possibilities for reducing the pathogenic activities of plaque.     

Preliminary assessment of safety and effectiveness in humans of ProBiora3 ™, a probiotic mouthwash

Aims:  To conduct a pilot human clinical trial to assess the safety and to test the ability of a probiotic mouthwash, ProBiora³, to affect the levels of Streptococcus mutans and certain known periodontal pathogens in the mouth when administered twice daily over a period of 4 weeks.
Methods and Results:  The mouthwash contained three specific strains of naturally occurring oral bacteria and was tested at two dose levels: 10⁶ and 10⁸ colony forming units each of Strep. oralis strain KJ3sm, Strep. uberis strain KJ2sm, and the spontaneous lactic acid-deficient variant of Strep. rattus , strain JH145. Substantial decreases in the levels of the marker bacteria were observed. No safety issues were noted with the twice daily application of this mouthwash.
Conclusions:  Despite the small number of subjects and the use of young, orally healthy adults, along with the inherent variability in the microbiological measurements, the probiotic mouthwash was able to substantially affect the levels of dental pathogens in saliva and periodontal pathogens in subgingival plaque.
Significance and Impact of the Study:  The results of this pilot human study suggest that the probiotic mouthwash product may be safe for daily use as an aid in maintaining both dental and periodontal health.     

Fluoride profiles in the cementum and root dentine of human permanent anterior teeth extracted from adult residents in a naturally fluoridated and a non-fluoridated area

Objectives: To determine the effect of water fluoride concentration on the fluoride profile across the entire thickness of the cementum and root dentine of human permanent anterior teeth in adults. Subjects: Twenty-eight human permanent anterior teeth from individuals aged from 30 to over 60 years were studied. Setting: Teeth were obtained from a natural high-fluoride area (West Hartlepool, UK; 1.0–1.3 ppm F in drinking water, WHP) and the other from a non-fluoridated naturally low fluoride area (Leeds, UK; 0.1 ppm F in drinking water, LDS). Design: Cementum and root dentine were sampled using an abrasive micro-sampling technique from the cementum surface to the pulpal surface of root dentine. Results: Fluoride concentration was higher in tooth roots (the cementum and dentine) taken from the naturally fluoridated area (WHP) than from the non-fluoridated area (LDS). Age and average fluoride concentration showed a positive correlation in WHP dentine, middle region of the root (r = 0.78, P < 0.001) and in the apical region of the root (r = 0.67, P < 0.05). WHP cementum had the strongest fluoride concentration correlation with age in the cervical region of the root (r = 0.67, P < 0.01). An analysis of variance (ANOVA) showed that the area (water fluoride content), age and number of years lived in the area combined with total age were significant. Conclusions : The fluoride content of cementum and root dentine in adult residents is related to fluoride content in drinking water.     

Polymorphisms in sweet taste genes (TAS1R2 and GLUT2), sweet liking,and dental caries prevalence in an adult Italian population

The aim of the study was to assess the relationship between sweet taste genes and dental caries prevalence in a large sample of adults. In addition, the association between sweet liking and sugar intake with dental caries was investigated. Caries was measured by the decayed, missing, filled teeth (DMFT) index in 647 Caucasian subjects (285 males and 362 females, aged 18–65 years), coming from six villages in northeastern Italy. Sweet liking was assessed using a 9-point scale, and the mean of the liking given by each individual to specific sweet food and beverages was used to create a sweet liking score. Simple sugar consumption was estimated by a dietary history interview, considering both added sugars and sugar present naturally in foods. Our study confirmed that polymorphisms in TAS1R2 and GLUT2 genes are related to DMFT index. In particular, GG homozygous individuals for rs3935570 in TAS1R2 gene (p value = 0.0117) and GG homozygous individuals for rs1499821 in GLUT2 gene (p value = 0.0273) showed higher DMFT levels compared to both heterozygous and homozygous for the alternative allele. Furthermore, while the relationship sugar intake–DMFT did not achieve statistical significance (p value = 0.075), a significant association was identified between sweet liking and DMFT (p value = 0.004), independent of other variables. Our study showed that sweet taste genetic factors contribute to caries prevalence and highlighted the role of sweet liking as a predictor of caries risk. Therefore, these results may open new perspectives for individual risk identification and implementation of target preventive strategies, such as identifying high-risk patients before caries development.

Electronic supplementary material

The online version of this article (doi:10.1007/s12263-015-0485-z) contains supplementary material, which is available to authorized users.     

Genetic sensitivity to bitter taste of 6-n Propylthiouracil: A useful diagnostic aid to detect early childhood caries in pre-school children

PURPOSE:

Genetic factor to bitter taste perception appears to be largely mediated by the TAS2R38 gene. The insensitivity to bitter compounds like 6-n-propylthiouracil (PROP) is mediated by this gene. PROP, a pharmacological drug used in treatment of Graves’ disease, proved to be useful tool in determining the genetic sensitivity levels to bitter and sweet taste. The purpose of this study is to show much simpler PROP sensitivity technique for the clinical examiner and its application as a diagnostic aid in Early Childhood Caries (ECC) detection among preschool children.

MATERIALS AND METHODS:

A total of 119 children belonging to the age group of 36 to 71 months of both sexes, were recruited from A. J. Institute of Dental Sciences, Mangalore (Karnataka). PROP sensitivity test was carried out to determine the inherent genetic ability to taste a bitter or sweet substance. This study used simpler scaling method to find out genetic sensitivity to bitter taste; one who tasted bitter as taster and one who was not able to differentiate/tasted like paper as non-taster. A questionnaire was provided to evaluate their dietary habits and caries experience was recorded. Collected data were tabulated and subjected to statistical analysis.

RESULTS:

In the total of 119 children the mean dmfs was definitely higher in non-taster children compared to tasters. The tasters had a mean dmfs value of 9.5120 (S.D. 7.0543) and non-tasters had a value of 7.7250 (S.D. 8.33147), which was statistically significant. The results suggested that there was increase in caries experience among the group of non-tasters as compared to tasters. Tasters tended to be sweet dislikers and non-tasters tended to be sweet likers. On the whole, tasters had a bad dentition as compared to non tasters.

CONCLUSION:

The PROP sensitivity test (filter paper test) proved to be a useful diagnostic tool in determining the genetic sensitivity levels of bitter taste. The knowledge of a child''s taste perception can help us in identifying the children who are at higher risk for ECC.     

Antimicrobial peptide control of pathogenic microorganisms of the oral cavity: a review of the literature

Antimicrobial peptides, molecules produced in many different organisms, have high biocidal activity against several microorganisms. However, several questions about these molecules remain unclear. Therefore, this report details a systematic survey of the literature on the use of antimicrobial peptides against oral pathogens and indicates which peptides and microorganisms are most extensively studied. Articles were located using the PubMed and Science Direct databases with the following inclusion criteria: publication date between 2002 and 2011; keywords "biofilm OR biological film OR biological layer OR bacterial growth" AND "peptide" AND "oral cavity OR mouth OR buccal mucosa OR oral mucosa OR mouth mucosa"; and abstract in English. A total of 73 articles were selected after refinement of the data. An increase in publications focusing on the use of antimicrobial peptides against oral microorganisms was observed. In addition, the peptides produced by cells of the oral mucosa (defensins, LL-37 and histatins) as well as Streptococcus mutans (among cariogenic bacteria) and Porphyromonas gingivalis (among periodontal bacteria) were the most studied subjects. It was concluded that the use of antimicrobial peptides as a tool for microbial control is of increasing importance, likely due to its widespread use, mechanism of action, and low rates of bacterial resistance.     

Analysis of socio-demographic and systemic health factors and the normative conditions of oral health care in a population of the Brazilian elderly

doi: 10.1111/j.1741‐2358.2010.00446.x
Analysis of socio‐demographic and systemic health factors and the normative conditions of oral health care in a population of the Brazilian elderly Objective: To investigate the association of socio‐demographic and systemic health factors according to the normative conditions of oral health care (dental caries, edentulism, periodontal disease and oral mucosal lesion) in elderly individuals. Material and methods: A cross‐sectional study was carried out in a group of elderly with access to community health care (n = 200). The normative conditions of oral health were then investigated according to the WHO and the SB Brazil criteria. Bivariate analyses were evaluated by the chi‐square test and Fisher’s exact test. An estimation of prevalence for the covariates was performed using Poisson’s regression models. Results: The prevalence of edentulism and oral mucosal lesions was detected in 58% and 21.5% of elderly patients, respectively. In the dentate subjects, the prevalence of dental caries and periodontal disease was 51.2% and 20.8%, respectively. Older men and individuals from lower‐income groups exhibited a higher prevalence of dental caries. Elderly women, illiterate individuals, and individuals over the age of 65 years exhibited a higher prevalence of edentulism. Elderly 60–64 years old and those who are employed had a significant association with periodontal disease. Conclusion: Socio‐demographic factors were associated with some notable oral diseases in the elderly.     

Relative contribution of caries and periodontal disease in adult tooth loss among patients reporting to the Institute of Dental Sciences,Belgaum, India

Objectives: To examine the reasons for tooth loss in an adult population. Methods: Patients who reported to the department of prosthodontics in Institute of Dental Sciences, Belgaum, located in the north‐western part of the state of Karnataka, in the southern region of India over a period of 2 months, with at least one missing tooth (excluding third molars) constituted the sample size. There were a total of 365 patients (185 females and 180 males) within the age group of 16–84 years (mean age 51.06 ± 16.47 years) who fulfilled this criterion. Socio‐demographic profile was recorded along with a clinical examination for assessing the number and pattern of tooth loss. The reasons for tooth loss were recorded according to the history reported by the patient. Results: In the present study of 365 patients, 58.9% of the patients were completely edentulous, 41% were partially dentate, of which 20.8% had lost their teeth from caries, 11% from periodontal disease and 9.3% from a combination of reasons. More females had lost their teeth because of dental caries whereas more males had lost their teeth because of periodontal disease, this being statistically significant. (χ² = 16.53, p = 0.001). Highly significant results were obtained for age and reasons for tooth loss. (χ² = 150.39, p < 0.001). Irrespective of the socio‐economic status, dental caries was the most common cause for tooth loss in partially dentate patients though it was not statistically significant (χ² = 13.62, p = 0.325). Mandibular first molars were the teeth most frequently lost due to dental caries. The maxillary left central incisor was most frequently lost due to periodontal disease, followed by the maxillary right central incisor. Conclusions: Since both dental caries and periodontal disease contributed to tooth loss at different ages, risk indicators need to be identified.