John C. Gunsolley

Aggregatibacter actinomycetemcomitans and Its Relationship to Initiation of Localized Aggressive Periodontitis : Longitudinal Cohort Study of Initially Healthy Adolescents

ABSTRACT Aggregatibacter actinomycetemcomitans is frequently associated with localized aggressive periodontitis (LAP); however, longitudinal cohort studies relating A. actinomycetemcomitans to initiation of LAP have not been reported. A periodontal assessment was performed on 1,075 primarily African-American and Hispanic schoolchildren, ages 11 to 17 years. Samples were taken from each child for A. actinomycetemcomitans. A cohort of 96 students was established that included a test group of 38 A. actinomycetemcomitans-positive students (36 periodontally healthy and 2 with periodontal pockets) and 58 healthy A. actinomycetemcomitans-negative controls. All clinical and microbiological procedures were repeated at 6-month intervals. Bitewing radiographs were taken annually for definitive diagnosis of LAP. At the initial examination, clinical probing attachment measurements indicated that 1.2% of students had LAP, while 13.7% carried A. actinomycetemcomitans, including 16.7% of African-American and 11% of Hispanic students (P = 0.001, chi-square test). A. actinomycetemcomitans serotypes a, b, and c were equally distributed among African-Americans; Hispanic students harbored predominantly serotype c (P = 0.05, chi-square test). In the longitudinal phase, survival analysis was performed to determine whether A. actinomycetemcomitans-positive as compared to A. actinomycetemcomitans-negative students remained healthy (“survived”) or progressed to disease with attachment loss of >2 mm or bone loss (failed to “survive”). Students without A. actinomycetemcomitans at baseline had a significantly greater chance to remain healthy (survive) compared to the A. actinomycetemcomitans-positive test group (P = 0.0001). Eight of 38 A. actinomycetemcomitans-positive and none of 58 A. actinomycetemcomitans-negative students showed bone loss (P = 0.01). A. actinomycetemcomitans serotype did not appear to influence survival. These findings suggest that detection of A. actinomycetemcomitans in periodontally healthy children can serve as a risk marker for initiation of LAP.

Clinical efficacy of antimicrobial mouthrinses

OBJECTIVE The goal of this report is to present the current state of the evidence evaluating the efficacy of anti-plaque, anti-gingivitis mouthrinses and to determine the clinical relevance of the evidence. MATERIAL AND METHODS To accomplish this goal a two stage approach was used. First a systematic review of the literature was done to find any systematic review that evaluated the efficacy of anti-plaque, anti-gingivitis mouthrinses from long term (six months) randomized placebo controlled clinical trials. Secondly, the clinical relevance was determined by comparing the percent reduction in plaque and gingivitis attributable to the anti-plaque, anti-gingivitis mouthrinses to change over time in the placebo groups attributable to adult prophylaxis and oral hygiene instructions. RESULTS Three systematic reviews and one meta-analysis were found that evaluated the efficacy of anti-plaque, anti-gingivitis mouthrinses. The systematic reviews concluded that there is strong evidence supporting the efficacy of chlorhexidine and essential oils as anti-plaque, anti-gingivitis mouthrinses. The evidence for cetyl pyridinium chloride (CPC) was weaker due to few clinical trials testing the same formulations of CPC. There was one meta-analysis of studies from a manufacture of Delmopinol, but it was not a systematic review of the literature. The report based on the meta-analysis concluded that Delmopinol was an effective anti-plaque, anti-gingivitis agent. Evaluation of clinical relevance by estimating percent reduction due to the active agents and changes over time in the placebo groups, demonstrated that the clinical effect of both chlorhexidine and essential oil containing mouthrinses met or exceeded reductions over time for placebo groups. Again the results for CPC were less consistent, but were similar to reductions over time in the placebo groups. CONCLUSIONS These results suggest that the clinical benefits of anti-plaque, anti-gingivitis mouthrinses are similar to the benefits of oral prophylaxis and oral hygiene instructions at six month recall appointments.

Evidence that periodontal treatment improves biomarkers and CVD outcomes

AIM The aim of this review was to critically appraise the evidence on the impact of periodontal treatment of cardiovascular diseases (CVDs) biomarkers and outcomes. METHODS A systematic search was performed in Cinhal, Cochrane, Embase and Medline for relevant articles up to July 2012. Duplicate screening and reference hand searching were performed. Data were then summarized and evidence graded in tables. RESULTS The search resulted in: (a) no evidence on the effects of periodontal therapy on subclinical atherosclerosis, serum levels of CD40 ligand, serum amyloid A and monocyte chemoattractant protein-1, (b) limited evidence on the effects of periodontal therapy on arterial blood pressure, leucocyte counts, fibrinogen, tissue necrosis factor-α, sE-selectin, von Willebrand factors, d-dimers, matrix metalloproteinases, oxidative stress and CVD events, and (c) moderate evidence suggesting a negligible effect of periodontal therapy in reducing interleukin-6 and lipids levels, whilst a positive effect in reducing serum C-reactive protein levels and improving endothelial function. CONCLUSIONS Periodontal therapy triggers a short-term inflammatory response followed by (a) a progressive and consistent reduction of systemic inflammation and (b) an improvement in endothelial function. There is however limited evidence that these acute and chronic changes will either increase or reduce CVD burden of individuals suffering from periodontitis in the long term.

Oral microbiome of deep and shallow dental pockets in chronic periodontitis.

We examined the subgingival bacterial biodiversity in untreated chronic periodontitis patients by sequencing 16S rRNA genes. The primary purpose of the study was to compare the oral microbiome in deep (diseased) and shallow (healthy) sites. A secondary purpose was to evaluate the influences of smoking, race and dental caries on this relationship. A total of 88 subjects from two clinics were recruited. Paired subgingival plaque samples were taken from each subject, one from a probing site depth >5 mm (deep site) and the other from a probing site depth ≤3mm (shallow site). A universal primer set was designed to amplify the V4–V6 region for oral microbial 16S rRNA sequences. Differences in genera and species attributable to deep and shallow sites were determined by statistical analysis using a two-part model and false discovery rate. Fifty-one of 170 genera and 200 of 746 species were found significantly different in abundances between shallow and deep sites. Besides previously identified periodontal disease-associated bacterial species, additional species were found markedly changed in diseased sites. Cluster analysis revealed that the microbiome difference between deep and shallow sites was influenced by patient-level effects such as clinic location, race and smoking. The differences between clinic locations may be influenced by racial distribution, in that all of the African Americans subjects were seen at the same clinic. Our results suggested that there were influences from the microbiome for caries and periodontal disease and these influences are independent.

Systematic review and meta-analysis on the nonsurgical treatment of chronic periodontitis by means of scaling and root planing with or without adjuncts.

BACKGROUND Conduct a systematic review and meta-analysis on nonsurgical treatment of patients with chronic periodontitis by means of scaling and root planing (SRP) with or without adjuncts. METHODS A panel of experts convened by the American Dental Association Council on Scientific Affairs conducted a search of PubMed (MEDLINE) and Embase for randomized controlled trials of SRP with or without the use of adjuncts with clinical attachment level (CAL) outcomes in trials at least 6 months in duration and published in English through July 2014. The authors assessed individual study bias by using the Cochrane Risk of Bias Tool and conducted meta-analyses to obtain the summary effect estimates and their precision and to assess heterogeneity. The authors used funnel plots and Egger tests to assess publication bias when there were more than 10 studies. The authors used a modified version of the US Preventive Services Task Force methods to assess the overall level of certainty in the evidence. RESULTS The panel included 72 articles on the effectiveness of SRP with or without the following: systemic antimicrobials, a systemic host modulator (subantimicrobial-dose doxycycline), locally delivered antimicrobials (chlorhexidine chips, doxycycline hyclate gel, and minocycline microspheres), and a variety of nonsurgical lasers (photodynamic therapy with a diode laser, a diode laser, neodymium:yttrium-aluminum-garnet lasers, and erbium lasers). CONCLUSIONS AND PRACTICAL IMPLICATIONS With a moderate level of certainty, the panel found approximately a 0.5-millimeter average improvement in CAL with SRP. Combinations of SRP with assorted adjuncts resulted in a range of average CAL improvements between 0.2 and 0.6 mm over SRP alone. The panel judged the following 4 adjunctive therapies as beneficial with a moderate level of certainty: systemic subantimicrobial-dose doxycycline, systemic antimicrobials, chlorhexidine chips, and photodynamic therapy with a diode laser. There was a low level of certainty in the benefits of the other included adjunctive therapies. The panel provides clinical recommendations in the associated clinical practice guideline.

Effects of caloric restriction on inflammatory periodontal disease

OBJECTIVE Dietary caloric restriction (CR) has been found to reduce systemic markers of inflammation and may attenuate the effects of chronic inflammatory conditions. The purpose of this study was to examine the effects of long-term CR on naturally occurring chronic inflammatory periodontal disease in a nonhuman primate model. METHODS The effects of long-term CR on extent and severity of naturally occurring chronic periodontal disease, local inflammatory and immune responses, and periodontal microbiology, were evaluated in a cohort of 81 (35 female and 46 male; 13-40 y of age) rhesus monkeys (Macaca mulatta) with no previous exposure to routine oral hygiene. CR monkeys had been subjected to 30% CR for 13-17 y relative to control-fed (CON) animals starting at 3-5 y of age. RESULTS Same sex CR and CON monkeys exhibited similar levels of plaque, calculus, and bleeding on probing. Among CON animals, males showed significantly greater periodontal breakdown, as reflected by higher mean clinical attachment level and periodontal probing depth scores, than females. CR males exhibited significantly less periodontal pocketing, lower IgG antibody response, and lower IL-8 and ss-glucuronidase levels compared to CON males, whereas CR females showed a lower IgG antibody response but comparable clinical parameters and inflammatory marker levels relative to CON females. Long-term CR had no demonstrable effect on the periodontal microbiota. CONCLUSION Males demonstrated greater risk for naturally occurring periodontal disease than females. Long-term CR may differentially reduce the production of local inflammatory mediators and risk for inflammatory periodontal disease among males but not females.

Single nucleotide polymorphisms of pattern recognition receptors and chronic periodontitis

BACKGROUND AND OBJECTIVE Periodontitis is a multifactorial disease influenced partly by genetics. Activation of pattern recognition receptors (PRRs) can lead to the up-regulation of inflammatory pathways, resulting in periodontal tissue destruction. Hence, functional polymorphisms located in PRRs can explain differences in host susceptibility to periodontitis. This study investigated single nucleotide polymorphisms of PRRs including toll-like receptor (TLR)2 (G2408A), TLR4 (A896G), TLR9 (T1486C), TLR9 (T1237C) and CD14 (C260T) in patients with chronic periodontitis and in periodontally healthy subjects. METHODS One-hundred and fourteen patients with chronic periodontitis and 77 periodontally healthy subjects were genotyped using TaqMan® allelic discrimination assays. Fishers exact test and chi-square analyses were performed to compare genotype and allele frequencies. RESULTS The frequency of subjects with the CC genotype of CD14 (C260T) (24.6% in the chronic periodontitis group vs. 13% in the periodontally healthy group) and those expressing the T allele of CD14 (C260T) (CT and TT) (75.4% in the chronic periodontitis group vs. 87% in the periodontally healthy group) was statistically different among groups (p = 0.04). Homozygocity for the C allele of the CD14 (C260T) polymorphism (CC) was associated with a two--fold increased susceptibility to periodontitis (p = 0.04; odds ratio, 2.49; 95% confidence interval, 1.06-6.26). Individuals with the CC genotype of TLR9 (T1486C) (14.9% in the chronic periodontitis group vs. 28.6% in the periodontally healthy group) and those expressing the T allele of TLR9 (T1486C) (CT and TT) (85.1% in the chronic periodontitis group vs. 71.4% in the periodontally healthy group) were also significantly differently distributed between groups without adjustment (p = 0.03). Further analysis of nonsmokers revealed a significant difference in the distribution of genotypes between groups for TLR9 (T1486C; p = 0.017) and CD14 (C260T; p = 0.03), polymorphisms again without adjustment. CONCLUSION The CC genotype of CD14 (C260T) is related to susceptibility to chronic periodontitis in Caucasians. In addition, differences observed in the distribution of TLR9 (T1486C) genotypes between groups warrant further investigation.

Efficacy of pre- and postirradiation hyperbaric oxygen therapy in the prevention of postextraction osteoradionecrosis: a systematic review.

PURPOSE There is still considerable controversy regarding whether hyperbaric oxygen (HBO) therapy used preoperatively and postoperatively will prevent osteoradionecrosis in previously irradiated patients undergoing tooth extraction. The purpose of this systematic review was to evaluate the best evidence available in an attempt to find an answer to this question. MATERIALS AND METHODS The literature search on Medline covered the period from January 1948 to March 2008. Included were randomized clinical trials, prospective studies without randomization, case-control studies, retrospective studies, and observational studies with and without control groups. This search retrieved 696 citations, which was reduced to 14 acceptable publications based on an assessment of methodologic quality. They included 1 randomized clinical trial, 8 cohort-controlled studies, and 5 observational studies. These were analyzed for radiation dose, type of radiation, use of adjunctive cancer treatments, number and location of extractions, method of extraction, HBO protocol, and use of adjunctive therapy besides HBO. RESULTS Most of the studies had a small sample size, lacked specific inclusion and exclusion criteria, did not report the interval between radiation and extraction, and provided limited information on the method of extraction. There was also variation in HBO protocols, radiation dosage, the use of antibiotics, and the use of adjunctive cancer therapy. CONCLUSION On the basis of the best available evidence, there is currently insufficient information to show that the use of HBO reduces the incidence of osteoradionecrosis in irradiated patients requiring tooth extraction.

Antibody of the IgG2 Subclass, Actinobacillus actinomycetemcomitans, and Early-Onset Periodontitis*

Susceptibility to early-onset periodontitis (EOP) appears to be attributable to a gene inherited in an autosomal dominant pattern. This explains why EOP clusters in families and why about half of the family members develop periodontal disease early in life. Manifestation of EOP is variable, with some patients having a localized form restricted to first molars and incisors (LJP) and others with a severe generalized form of periodontitis (SP). The extent and severity of disease is less in patients who are seropositive for Actinobacillus actinomycetemcomitans than in seronegative patients, and this relationship prompted the hypothesis that anti-A. actinomycetemcomitans helps limit disease. The dominant antibody is an IgG2 reactive with the serotypespecific carbohydrate. The incidence of the LJP form of EOP is about 10 times higher in blacks than in whites. Interestingly, blacks have higher levels of serum IgG2, a higher frequency of anti-A. actinomycetemcomitans antibody, and higher serum titers of IgG2 anti-A. actinomycetemcomitans which may help explain why the disease is localized. Studies in progress suggest that smoking reduces serum IgG2 levels in SP patients and is associated with more severe periodontal destruction. In marked contrast, IgG2 does not appear to be reduced in LJP patients who smoke, and smoking does not appear to increase periodontal destruction. We think that IgG2 anti-A. actinomycetemcomitans is playing a role in limiting the extent and severity of disease in patients genetically susceptible to EOP. J Periodontol 1996;67:317-322.

Application of metagenomics in understanding oral health and disease

Oral diseases including periodontal disease and caries are some of the most prevalent infectious diseases in humans. Different microbial species cohabitate and form a polymicrobial biofilm called dental plaque in the oral cavity. Metagenomics using next generation sequencing technologies has produced bacterial profiles and genomic profiles to study the relationships between microbial diversity, genetic variation, and oral diseases. Several oral metagenomic studies have examined the oral microbiome of periodontal disease and caries. Gene annotations in these studies support the association of specific genes or metabolic pathways with oral health and with specific diseases. The roles of pathogenic species and functions of specific genes in oral disease development have been recognized by metagenomic analysis. A model is proposed in which three levels of interactions occur in the oral microbiome that determines oral health or disease.