Role of lactoferrin and lactoferrin-derived peptides in oral and maxillofacial diseases.

The oral cavity harbors different taxonomic groups, the evolutionary coexistence of which develops the oral ecosystem. These resident microorganisms can alter the balance between the physiologic and pathologic conditions that affect the host, both locally and systemically. This highly sophisticated nature of the oral cavity poses a significant therapeutic challenge. Numerous human and animal studies have been conducted to potentiate the efficacy and competence of current treatments of pathologic conditions as well as to develop novel therapeutic modalities. One of these studies is the use of the potent antimicrobial agent lactoferrin (LF), which was originally derived from the host immune system. LF is an 80-kDa glycoprotein that has a free iron sequestration mechanism with evident antimicrobial, anti-tumor, and immunomodulatory properties. A wide range of active peptides have been isolated from the N-terminal region of LF, which possess antimicrobial activities. In this review, we discuss the role of LF and LF-derived peptides under a heterogeneous group of oral and maxillofacial conditions, including bacterial, fungal, viral infections; head and neck cancers; xerostomia; and implantology-bone-related manifestations.

Human lactoferrin protects against Streptococcus mutans-induced caries in mice.

OBJECTIVES: The objective of this study is to evaluate the importance of human lactoferrin (hLF) in an experimental caries induced by Streptococcus mutans in a lactoferrin-knockout (LFKO(-/-)) mouse model compared with C576J/BL wild-type (WT) mice. MATERIALS AND METHODS: The WT and LFKO(-/-) mice were infected with S. mutans (1 × 10(8) cells) and/or sham infection. Furthermore, the effect of hLF administration was evaluated in LFKO(-/-) mice infected with S. mutans. Mice were assessed for colonization, salivary pH, and caries development. RESULTS: The results showed that the lactoferrin-knockout infected (LFKO(-/-) I) mice had significantly higher colonization with S. mutans (P = 0.02), lower salivary pH (P = 0.01), and more carious lesions (P = 0.01) when compared to wild-type infected (WTI) mice. In addition, the administration of hLF did not show any evidence of S. mutans colonization as well as carious lesions (P = 0.001) in LFKO(-/-) I mice when compared to untreated LFKO(-/-) I mice. CONCLUSION: These results show that endogenous LF protects against S. mutans-induced caries and that exogenous hLF can exert a protective effect against caries development.

The Opioid Analgesic Reduction Study (OARS) Pilot: A Double-Blind Randomized Multicenter Trial.

BACKGROUND: With addiction rates and opioid deaths increasing, health care providers are obligated to help stem the opioid crisis. As limited studies examine the comparative effectiveness of fixed-dose combination nonopioid analgesia to opioid-containing analgesia, a comparative effectiveness study was planned and refined by conducting a pilot study. METHODS: The Opioid Analgesic Reduction Study (OARS) pilot, a stratified, randomized, multisite, double-blind clinical trial, was designed to test technology and procedures to be used in the full OARS trial. Participants engaged in the full protocol, enabling the collection of OARS outcome data. Eligible participants reporting to 1 of 5 sites for partial or full bony impacted mandibular third molar extraction were stratified by biologic sex and randomized to 1 of 2 treatment groups, OPIOID or NONOPIOID. OPIOID participants were provided 20 doses of hydrocodone 5 mg/acetaminophen 300 mg. NONOPIOID participants were provided 20 doses of ibuprofen 400 mg/acetaminophen 500 mg. OARS outcomes data, including pain experience, adverse effects, sleep quality, pain interference, overall satisfaction, and remaining opioid tablets available for diversion, were collected via surveys, electronic medication bottles, eDiary, and activity/sleep monitor. RESULTS: Fifty-three participants were randomized with 50 completing the OARS pilot protocol. Across all outcome pain domains, in all but 1 time period, NONOPIOID was better in managing pain than OPIOID (P < 0.05 level). Other outcomes suggest less pain interference, less adverse events, better sleep quality, better overall satisfaction, and fewer opioid-containing tablets available for diversion. DISCUSSION: Results suggest patients requiring impacted mandibular third molar extraction would benefit from fixed-dose combination nonopioid analgesia. KNOWLEDGE TRANSFER STATEMENT: Study results suggest fixed-dose nonopioid combination ibuprofen 400 mg/acetaminophen 500 mg is superior to opioid-containing analgesic (hydrocodone 5 mg/acetaminophen 500 mg). This knowledge should inform surgeons and patients in the selection of postsurgical analgesia.

Impact of DHCWs' Safety Perception on Vaccine Acceptance and Adoption of Risk Mitigation Strategies.

OBJECTIVES: To estimate the association between safety perception on vaccine acceptance and adoptions of risk mitigation strategies among dental health care workers (DHCWs). METHODS: A survey was emailed to DHCWs in the New Jersey area from December 2020 to January 2021. Perceived safety from regular SARS-CoV-2 testing of self, coworkers, and patients and its association with vaccine hesitancy and risk mitigation were ascertained. Risk Mitigation Strategy (RiMS) scores were computed from groupings of office measures: 1) physical distancing (reduced occupancy, traffic flow, donning of masks, minimal room crowding), 2) personal protective equipment (fitted for N95; donning N95 masks; use of face shields; coverings for head, body, and feet), and 3) environmental disinfection (suction, air filtration, ultraviolet, surface wiping). RESULTS: SARS-CoV-2 testing of dental professionals, coworkers, and patients were perceived to provide safety at 49%, 55%, and 68%, respectively. While dentists were least likely to feel safe with regular self-testing for SARS-CoV-2 (P < 0.001) as compared with hygienists and assistants, they were more willing than hygienists (P = 0.004; odds ratio, 1.79 [95% CI, 1.21 to 2.66]) and assistants (P < 0.001; odds ratio, 3.32 [95% CI, 1.93 to 5.71]) to receive the vaccine. RiMS scores ranged from 0 to 19 for 467 participants (mean [SD], 10.9 [2.9]). RiMS scores did not significantly differ among groups of DHCWs; however, mean RiMS scores were higher among those who received or planned to receive the COVID-19 vaccine than those with who did not (P = 0.004). DHCWs who felt safer with regular testing had greater RiMS scores than those who did not (11.0 vs. 10.3, P = 0.01). CONCLUSIONS: Understanding DHCWs' perception of risk and safety is crucial, as it likely influences attitudes toward testing and implementation of office risk mitigation policies. Clinical studies that correlate risk perception and RiMS with SARS-CoV-2 testing are needed to demonstrate the effectiveness of RiMS in dental care settings. KNOWLEDGE TRANSFER STATEMENT: Educators, clinicians, and policy makers can use the results of this study when improving attitudes toward testing and implementation of risk mitigation policies within dental offices, for current and future pandemics.

Human salivary cystatin SA exhibits antimicrobial effect against Aggregatibacter actinomycetemcomitans.

BACKGROUND AND OBJECTIVE: Healthy subjects who do not have Aggregatibacter actinomycetemcomitans in their oral cavity may possess factors in saliva that might demonstrate antibacterial activity against the bacterium. The aim of this study was to identify and purify proteins from saliva of healthy subjects that might demonstrate antibacterial activity against A. actinomycetemcomitans and test the same against the bacteria. MATERIAL AND METHODS: Saliva from 10 healthy volunteers was tested individually for its anti-A. actinomycetemcomitans activity. Among the 10 subjects, eight demonstrated anti-A. actinomycetemcomitans activity. Saliva was collected from one healthy volunteer who demonstrated the highest antimicrobial activity against A. actinomycetemcomitans. After clarifying the saliva, it was subjected to an affinity chromatography column with A. actinomycetemcomitans. The proteins bound to A. actinomycetemcomitans were eluted from the column and identified using mass spectrometry (MALDI-TOF/TOF MS). Among other proteins that bound to A. actinomycetemcomitans, which included lactoferrin, immunoglobulin A and kallikrein, cystatin SA was observed in significantly higher concentrations, and this was purified from the eluate. The purified cystatin SA was tested at different concentrations for its ability to kill A. actinomycetemcomitans in a 2 h cell killing assay. The bacteria were also treated with a proteinase inhibitor, leupeptin, to clarify whether the antimicrobial effect of cystatin SA was related to its protease inhibitory function. Cystatin SA was also tested for its ability to prevent binding of A. actinomycetemcomitans to buccal epithelial cells (BECs) in an A. actinomycetemcomitans-BEC binding assay. RESULTS: Cystatin SA (0.1 mg/mL) demonstrated a statistically significant antimicrobial activity against A. actinomycetemcomitans. The effect of cystatin SA decreased with lower concentrations, with 0.01 mg/mL showing no effect. The addition of monoclonal cystatin SA antibodies to the purified sample completely negated the antimicrobial effect. Treatment of A. actinomycetemcomitans with leupeptin resulted in no antimicrobial effect, suggesting that the antimicrobial activity of cystatin SA is independent of its protease inhibitory function. A. actinomycetemcomitans pretreated with cystatin SA showed reduced binding to BECs, suggesting a potential role for cystatin SA in decreasing the colonization of A. actinomycetemcomitans. CONCLUSION: The present study shows that cystatin SA demonstrates antimicrobial activity against the periodontopathogen A. actinomycetemcomitans, and future studies determining the mechanism of action are necessary. The study also shows the ability of cystatin SA to reduce significantly the binding of A. actinomycetemcomitans to BECs.

N-nitrosamines in the rubber and tire industry.

Airborne N-nitrosomorpholine (0 to 27 micrograms per cubic meter) was found in two of four rubber industry factories. N-Nitrosodimethylamine was also found in two factories, but at lower levels. These findings may be relevant to the reported increased risk of certain types of cancer in rubber workers in some of the same areas where the N-nitrosomorpholine levels were highest.

Lactoferrin: A Roadmap to the Borderland between Caries and Periodontal Disease.

Lactoferrin is one of a number of multifunctional proteins that are present in or on all mucosal surfaces throughout the body. Levels of lactoferrin are consistently elevated in inflammatory diseases such as arthritis, inflammatory bowel diseases, corneal disease, and periodontitis. Single-nucleotide polymorphisms (SNPs) in lactoferrin have been shown to be present in individuals susceptible to Escherichia coli-induced travelers' diarrhea and in tear fluid derived from virally associated corneal disease. Here, we review data showing a lactoferrin SNP in amino acid position 29 in the antimicrobial region of lactoferrin that acts against caries associated bacteria. This SNP was initially discovered in African American subjects with localized aggressive periodontitis (LAP) who had proximal bone loss but minimal proximal caries. Results were confirmed in a genetic association study of children from Brazil with this same SNP who showed a reduced level of caries. In vitro data indicate that lactoferrin from whole saliva derived from subjects with this SNP, recombinant human lactoferrin containing this SNP, or an 11-mer peptide designed for this SNP kills mutans streptococci associated with caries by >1 log. In contrast, the SNP has minimal effect on Gram-negative species associated with periodontitis. Moreover, periodontally healthy subjects homozygous for this lysine (K) SNP have lactoferrin in their saliva that kills mutans streptococci and have reduced proximal decay. The review summarizes data supporting the ecologic plaque hypothesis and suggests that a genetic variant in lactoferrin with K in position 29 when found in saliva and crevice fluid can influence community biofilm composition. We propose that, for caries, this SNP is ethnicity independent and protective by directly killing caries-provoking bacteria (reducing proximal decay). However, the clinical effect of this SNP in LAP is ethnicity dependent, destructive (increases LAP incidence), and complex with mechanisms still to be determined.

Codon usage in Actinobacillus actinomycetemcomitans.

The codon usage patterns of 21 genes encompassing 5800 codons from Actinobacillus actinomycetemcomitans were analyzed. A. actinomycetemcomitans genes could be divided into two groups based on their function and G + C content. One group included those genes encoding basic cellular functions. This group displayed an average G + C content of 48%. A second group comprised genes encoding the leukotoxin determinant, an insertion sequence and a plasmid. This group displayed an average G + C content of 36%. These findings suggest that portions of the A. actinomycetemcomitans genome may have been acquired by horizontal gene transfer from one or more distantly related species. We present a table of A. actinomycetemcomitans codon usage. These data may be used to establish standards for computer programs that predict A. actinomycetemcomitans protein coding regions and may be useful in designing degenerate oligonucleotide probes.

Clinical use of antibiotics in dental practice.

Inappropriate use of antibiotics by clinicians leads to development of antibiotic resistance. For the most part, antibiotics are prescribed in dental practice for prophylactic and therapeutic reasons. Prophylactic antibiotics are prescribed to prevent diseases caused by members of the oral flora introduced to distant sites in a host at risk or introduced to a local compromised site in a host at risk. In most cases, prophylaxis is used for prevention of endocarditis. Therapeutic antibiotics are prescribed, in most cases, to treat diseases of hard and soft tissues in the oral cavity after local debridement has failed. Antibiotics used for prophylaxis must: (1) be active against the major pathogens; and (2) achieve a tissue loading dose before the bacteria are introduced. Antibiotics used for therapy are required in cases where the infection is already present and thus the agent must reach the site of infection at a high enough level for a long enough time to produce the desired effect. For an exogenous agent the goal is to eliminate the agent from the site of infection. In the case of an endogenous agent the antibiotic must suppress the organism at the site of infection. Recent evidence underscores the important role of antibiotics in the treatment and prevention of diseases initiated in the oral cavity that have the potential to spread to distant organs in the body.

Incorporating new technologies in periodontal diagnosis into training programs and patient care: a critical assessment and a plan for the future.

New diagnostic technologies may be capable of providing the dental practitioner with powerful tools that can assist in the early identification of periodontal disease that can result in expediated treatment. In this paper, clinical, host, and microbiological parameters will be evaluated for their ability to assess disease activity and to assist in the treatment decision-making process. The discussion will focus on: 1) the perceived need for markers of disease activity; 2) the most commonly proposed markers of disease activity currently under consideration for clinical application; and 3) a plan for future use of disease activity markers. The review concludes that: 1) tooth loss and most forms of rapid disease progression is limited to a small subset of patients within the periodontally diseased population; 2) no single parameter will stand alone as a measure of disease activity; 3) different aspects of treatment may require different combinations of tests to successfully intercept disease in this vulnerable patient group; and 4) early diagnosis can affect long-term periodontal status. Best estimates are presented for: 1) pre-disease identification of high-risk population groups; 2) early diagnosis of disease activity on a site and patient basis; and 3) assistance in the therapeutic decision-making process. It is further concluded that the complexity of the problem may require a re-examination of priorities such that more time and money is allocated to early diagnosis as opposed to treatment in this highly vulnerable patient population.

Lactoferrin iron levels affect attachment of Actinobacillus actinomycetemcomitans to buccal epithelial cells.

BACKGROUND: Prior reports have suggested that the iron-binding protein lactoferrin (LF) may either kill Actinobacillus actinomycetemcomitans (Aa) or interfere with its binding to host cells. Other studies have indicated that the degree of iron saturation of LF might play a role in these interactions. However, these studies utilized strains that had lost critical attachment characteristics found in well-preserved clinical isolates of Aa. The purpose of this work was to study the effect of LF iron levels on survival and attachment of well-preserved clinical isolates of Aa. METHODS: LF containing 0%, 30%, and 100% iron saturation was tested for its ability to kill clinical isolates of Aa and to inhibit their binding to buccal epithelial cells (BECs). RESULTS: Neither iron-free LF (apo-LF) nor iron-saturated LF killed Aa clinical isolates. Increasing the iron saturation of LF resulted in an increased inhibition of Aa binding to BECs (P < or =0.005). This effect was consistent for the 3 clinical isolates tested. Pretreatment of Aa with iron-saturated LF reduced binding to BECs by 58%, 61.8%, and 64.2%, respectively, for each of the 3 clinical strains tested (P < or =0.005). Pretreatment of Aa strains with apo-LF, iron alone, or bovine serum albumin had no effect on binding. Pretreatment of BECs with LF (either apo-LF or iron-containing LF) had no influence on Aa binding. CONCLUSIONS: These results indicate that reduction in binding of Aa to epithelial cells is maximized by pretreatment of Aa cells with iron-saturated lactoferrin. These in vitro results suggest that patients with lactoferrin containing lowered levels of iron would be more susceptible to Aa colonization.

Caries levels in patients with juvenile periodontitis.

The degree and distribution of tooth decay in a group of juvenile periodontitis ( JP ) patients were compared with tooth decay in an age- and sex-matched periodontally normal control group. The experimental group was comprised of 13 patients of no more than 20 years of age who were designated as localized juvenile periodontitis patients ( LJP ) according to the definition of Baer, and 10 patients of no more than 25 years of age who were designated as generalized juvenile periodontitis patients ( GJP ), as described by Manson and Lehner . Twenty-three age- and sex-matched patients with no periodontal disease served as the control group. Caries was evaluated by standard clinical and radiographic criteria and quantitated by decayed, missing, filled teeth and surfaces (DMFS). Decay was further categorized as active proximal decay and as total proximal decay, which included both active proximal caries and restored proximal surfaces. A Student's t test revealed no statistical differences between the LJP and GJP groups. Moreover, there was no difference in the number of missing or filled teeth in the JP group as compared to the control group. However, 17 of the 23 JP patients had no proximal decay, whereas all but two of the 23 control patients had some proximal decay. Moreover, in the JP group ( LJP and GJP ) the mean values for active proximal decay and total proximal decay were both significantly lower than those in the control group (P less than 0.001). Thus, a low number of proximal carious lesions were found in the presence of juvenile periodontitis.(ABSTRACT TRUNCATED AT 250 WORDS)

Sorption of fibronectin to human root surfaces in vitro.

The purpose of this study was to determine the conditions that favor the sorption and retention of human plasma fibronectin to cementum. Rectangular root segments prepared from teeth extracted for orthodontic reasons were mounted on a capillary pipette and immersed in solutions of 125I fibronectin for assay of cementum sorption under various conditions. Kinetic studies showed sorption to be rapid, with 77% of the maximum fibronectin sorption occurring within 1 minute. Fibronectin sorption was reduced when added in conjunction with serum and was inhibited by monovalent ions (such as sodium), but enhanced in the presence of divalent cations (such as calcium). Exposure of cementum to serum partially blocked subsequent sorption of fibronectin, while cementum bound fibronectin was eluted by subsequent exposure to serum. Treatment of cementum with citric acid pH 1.1 (4 minutes) followed by 5% sodium hypochlorite (5 minutes) caused a significant increase in fibronectin sorption with maximum retention upon subsequent exposure to serum (P less than 0.05). Fibronectin sorption to cementum was: rapid, electrostatic in nature, competitive, reversible, Ca+(+)-facilitated, and maximized by prior treatment of the root with citric acid and sodium hypochlorite. It is concluded that sorption of fibronectin to cementum can be achieved for clinical gain; however, conditions of application can significantly influence both accumulation and subsequent release of root sorbed material.

Lactoferrin iron levels are reduced in saliva of patients with localized aggressive periodontitis.

BACKGROUND: Actinobacillus actinomycetemcomitans (Aa) is associated with localized aggressive periodontal disease in juveniles (LAgP). Lactoferrin (LF) is an iron-binding salivary protein that has been shown to kill Aa in its iron-free form (apo) and reduce binding to host cells in its iron-saturated form (halo). However, recent in vitro studies show that LF does not kill clinical isolates of Aa, and LF with reduced levels of bound iron does not interfere with its attachment. These findings suggest that colonization of Aa may occur more readily in an environment containing LF with low iron levels. The purpose of this study was to examine the relationship of LF iron levels in saliva of LAgP patients as compared to their age-, gender-, and race-matched controls. METHODS: Whole and parotid saliva was collected from LAgP patients and matched controls. Micrograms of LF/mg of protein as well as nanograms of iron/micrograms of LF were determined. Iron binding was determined in parotid saliva by addition of nonlabeled and 59Fe labeled iron. RESULTS: LAgP patients' whole saliva had higher LF levels than controls, but their LF contained less iron (P < or =0.005). No iron was found in LF from parotid saliva in either group. When iron was added to parotid saliva, the LAgP saliva bound 20 to 30 times less iron than controls (P< or =0.001). Finally, LF was identified as the major iron-binding protein in parotid saliva by 59Fe autoradiography and Western blotting. CONCLUSIONS: This study shows that the level of bound iron in LF is significantly reduced in LAgP patients compared to controls. These data suggest that LF from LAgP patients has a reduced capacity to bind iron and that LF iron levels may play an important role in Aa-induced LAgP.

Proximal caries in juvenile periodontitis patients.

BACKGROUND: Caries is recognized as the prevalent proximal dental disease in adolescents, while proximal bone loss is minimal to non-existent in this population. Adolescents demonstrating an inverse disease pattern, i.e., minimal caries and active periodontitis, could provide powerful clues with regard to both diseases. However, data are inconsistent. This study was designed to clarify this relationship by comparing proximal caries prevalence in a juvenile periodontitis (JP) group to a matched non-periodontally diseased control group. METHODS: Two groups (cases [JPs] and control patients [CPs]) were matched for age, sex, and race and evaluated for decayed, missing, filled teeth and surfaces (DMFS) by radiographic analysis. Statistical analysis was performed by ANOVA and Student t test. The study consisted of four phases. Phase I was based on data from a previous study that failed to include race in the analysis. Thus, the original 23 JP patients (mostly African-Americans from New York City) were rematched for race as well as sex and age with CPs from Newark, NJ. The effect of water fluoridation (found in NYC) was evaluated in Phase II by matching the 23 original CPs (mostly Caucasian from NYC) with 23 CPs from NJ. Since differences were seen, we rematched our original JPs from NYC with a new set of race-matched CPs from NYC (Phase III). Finally, 13 JP patients from the University of Medicine and Dentistry of New Jersey (UMDNJ) were matched with CPs from NJ (Phase IV). RESULTS: Phase I and III indicated that JP patients had significantly less proximal caries than their matched CPs (P < or =0.05). Phase II confirmed the role of fluoride in caries reduction. Phase IV (NJ sample) supported our previous data and suggested that JP patients had less proximal caries than CPs (P < or =0.05). CONCLUSIONS: JP patients had significantly less proximal caries than their matched CPs when groups were balanced and radiographic evaluations were performed. In-depth studies of JP patients could provide important clues about both caries and periodontal disease etiology and pathogenesis.

Efficacy of preprocedural rinsing with an antiseptic in reducing viable bacteria in dental aerosols.

This double-blind, controlled, cross-over, clinical study evaluated the effect of preprocedural rinsing with an antiseptic mouthrinse on the level of recoverable viable bacteria in an aerosol generated during a typical dental procedure. Eighteen subjects participated. Following 24 hours of abstention from all oral hygiene procedures, subjects received a 10-minute ultrasonic scaling of a randomly selected one-half of their mouth which served as the unrinsed control. They were then randomly assigned either antiseptic mouthwash or a control rinse and rinsed with 20 ml for 30 seconds, after which the remaining half mouth (experimental side) was scaled ultrasonically for 10 minutes. During each 10-minute scaling period aerosolized bacteria were collected on a sterile filter using a modified vacuum air-sampling device. Microbes captured on the sterile filter were quantitated by overlaying the filters onto trypticase soy agar, incubating the filters aerobically at 37 degrees C for 24 to 72 hours, and counting the resulting colony forming units (CFU). Preliminary experiments had confirmed that neither the collection method nor residual antiseptic mouthwash in the aerosol adversely affected the number of viable bacteria recovered from the filter. Rinsing with the antiseptic mouthwash produced a 94.1% reduction in recoverable CFUs compared to the non-rinsed control, while the control rinse produced a 33.9% reduction. The difference between the mouthwash and control was statistically significant (P < .001). This study indicates that preprocedural rinsing with an antiseptic mouthwash can significantly reduce the microbial content of aerosols generated during ultrasonic scaling and may have potential in-office use as part of an infection control regimen.

Endotoxin levels in periodontally healthy and diseased sites: correlation with levels of gram-negative bacteria.

This study investigated the correlation between endotoxin levels and the percentage of Gram-negative bacteria in healthy sites and in periodontitis sites. Twelve healthy adults participated. Each subject provided 3 periodontitis sites with 5 to 8 mm probing depths that bled on gentle probing and 3 healthy sites with sulcus depths of 1 to 3 mm that did not bleed. Clinical examinations and sterile paper point sampling of all study sites were conducted on days 0, 7, and 14, and site-specific endotoxin levels and percentage of Gram-negative bacteria were determined. There were significant differences in both endotoxin levels and percentage Gram-negative bacteria between healthy and periodontitis sites across all 3 sampling periods, but no difference across sampling periods in the healthy sites and the periodontitis sites, respectively. Correlation coefficients revealed a high degree of correlation between site-specific endotoxin levels and percentage of Gram-negative organisms. Using a sample dilution of 1 x 10(4), endotoxin levels differentiated healthy from periodontitis sites with a specificity of approximately 91% and a sensitivity of approximately 90%.

Adjunctive use of a subgingival controlled-release chlorhexidine chip reduces probing depth and improves attachment level compared with scaling and root planing alone.

The present studies evaluated the efficacy of a controlled-release biodegradable chlorhexidine (CHX) (2.5 mg) chip when used as an adjunct to scaling and root planing on reducing probing depth (PD) and improving clinical attachment level (CAL) in adult periodontitis. Two double-blind, randomized, placebo-controlled multi-center clinical trials (5 centers each) were conducted; pooled data are reported from all 10 centers (447 patients). At baseline, following 1 hour of scaling and root planing (SRP) in patients free of supragingival calculus, the chip was placed in target sites with PD 5 to 8 mm which bled on probing. Chip placement was repeated at 3 and/or 6 months if PD remained > or = 5 mm. Study sites in active chip subjects received either CHX chip plus SRP or SRP alone (to maintain study blind). Sites in placebo chip subjects received either placebo chip plus SRP or SRP alone. Examinations were performed at baseline; 7 days; 6 weeks; and 3, 6, and 9 months. At 9 months significant reductions from baseline favoring the chlorhexidine chip compared with both control treatments were observed with respect to PD (chlorhexidine chip plus SRP, 0.95 +/- 0.05 mm; SRP alone, 0.65 +/- 0.05 mm, P < 0.001; placebo chip plus SRP, 0.69 +/- 0.05 mm, P < 0.001) and CAL (chlorhexidine chip plus SRP, 0.75 +/- 0.06 mm; SRP alone, 0.58 +/- 0.06 mm, P < 0.05; placebo chip plus SRP, 0.55 +/- 0.06 mm, P < 0.05). The proportion of patients who evidenced a PD reduction from baseline of 2 mm or more at 9 months was significantly greater in the chlorhexidine chip group (19%) compared with SRP controls (8%) (P < 0.05). Adverse effects were minor and transient toothache, including pain, tenderness, aching, throbbing, soreness, discomfort, or sensitivity was the only adverse effect that was higher in the chlorhexidine group as compared to placebo (P = 0.042). These data demonstrate that the adjunctive use of the chlorhexidine chip results in a significant reduction of PD when compared with both SRP alone or the adjunctive use of a placebo chip. These multi-center randomized control trials suggest that the chlorhexidine chip is a safe and effective adjunctive chemotherapy for the treatment of adult periodontitis.

Colonization and persistence of rough and smooth colony variants of Actinobacillus actinomycetemcomitans in the mouths of rats.

Fresh isolates of Actinobacillus actinomycetemcomitans (Aa) bind avidly to surfaces in vitro, but existing in vivo studies of the adherence of Aa are limited. This study had two goals: (1) to compare the oral colonization of two isogenic strains of Aa-CU1010, a clinical isolate that expresses the adherent phenotype, and CU1012, a minimally adherent laboratory variant-and (2) to check for phenotypic reversion of these strains in a clinical setting. Rifampicin-resistant strains, developed for tracking in Sprague-Dawley rats, were tested in vitro to determine their stability and binding. In study 1, after antibiotic suppression, six rats (group I) received CU1010 in their feed. The eight rats in group II received CU1012 in their feed and four were supplemented by oral swabbing and four by gastric gavage. Group III consisted of three sham-inoculated controls. All rats were inoculated for 4 days. Microbiological data were collected at 1, 4 and 8 weeks after inoculation. Supporting data were supplied by antibody titres and clinical measures of alveolar bone loss. Study 2 consisted of six rats in each of three groups as above, but tagged strains of Aa were delivered by food alone. At all time-points in both studies, Aa was absent before inoculation and controls had no Aa or antibody to Aa. In study 1, all six rats in group I yielded positive cultures for Aa at 8 weeks. In group II, five of eight had positive cultures for Aa at 1 week, two of eight at 4 weeks and none had Aa at 8 weeks (P < or =0.001). All six rats in group I had serum anti-Aa titres compared to group II, where titres were seen in four of eight rats (P < or =0.015). In vitro data paralleled those found in vivo. No phenotypic reversion of either strain was seen in vivo. In study 2, four of six rats in group I showed Aa and had titres to Aa, while no other animals showed Aa at any time. The model provides convincing evidence that, unlike laboratory variants, clinical isolates colonize, persist and integrate into an already established, albeit reduced, econiche.

Tenacious adhesion of Actinobacillus actinomycetemcomitans strain CU1000 to salivary-coated hydroxyapatite.

Adherence of Actinobacillus actinomycetemcomitans to hard-tissue surfaces was evaluated by comparing a phenotypically stable, well-maintained clinical isolate (strain CU1000) to Streptococcus gordonii G9B, an extensively studied oral-colonizing bacterium. Standard innocula of radiolabelled bacteria were added to saliva-coated hydroxyapatite (SHA) and the ratio of bound to unbound cells counted. Several other clinical isolates as well as laboratory strain Y4 were studied. In other experiments, cell detachment from SHA was compared in static and shaking vessels to calculate controlled desorption of cells over time. A sonic-displacement assay was used to measure avidity of binding to HA and SHA. To better define the attachment properties of CU1000, bacteria were treated with a variety of agents including detergents, salts and enzymes before or after incubation with SHA. Results indicated that CU1000 bound better than G9B (a minimum of 10-fold greater; p < or = 0.05) and did not desorb from SHA, while G9B desorbed to equilibrium in 4 h. Furthermore, Langmuir isotherm calculations indicated that, unlike G9B, CU1000 did not follow second-order adsorption kinetics and thus did not achieve saturation. In addition, of the agents tested only periodate reduced attachment and resulted in detachment of CU1000 from surfaces. These experiments suggest that clinical isolates of A. actinomycetemcomitans possess unique binding properties that promote adsorption to and impede desorption from SHA. The characteristics described for the actinobacillus in this study have been previously underestimated, appear to be mediated by glycoconjugates, and may resemble attachment described for several biofilm-forming, non-oral pathogens.