Robert S. Hirsch

The effects of intra-arterial epinephrine and nicotine on gingival circulation

The purpose of this study was to test the hypothesis that acute necrotizing ulcerative gingivitis (ANUG) was the result of ischemia resulting from three predisposing factors. Vascular stasis, stress, and smoking were said to combine and induce severe vascular constriction at the end arterial locations of the gingivae, resulting in necrosis of the part. The experimental animal used was the rabbit; clinical doses of epinephrine and nicotine were infused intraarterially and the gingival circulation was monitored by the heat-diffusion principle. It was found that the chemicals caused a severe reduction in flow rates in spite of greatly increased pressure within the system. The finding supports the hypothesis that ischemia could play an important role in the initiation of ANUG.

Azithromycin in periodontal treatment: more than an antibiotic.

Azithromycin is a macrolide antibiotic used extensively in medicine for the treatment of a wide range of infections such as upper respiratory tract infections, middle ear infections, sexually transmitted infections and trachoma. It is also effective against the most common periodontopathogens. The versatility of the macrolides extends beyond their antibiotic properties as a result of their well-documented immune-modulating/anti-inflammatory effects. Macrolides, including azithromycin, are therefore used to treat diseases not associated with bacteria, such as severe asthma, chronic obstructive pulmonary diseases and, more recently, cystic fibrosis. Azithromycin is concentrated in neutrophils, macrophages and particularly fibroblasts; all of these cells are central players in the pathogenesis of most periodontal diseases. This paper reviews the diverse properties of azithromycin and the clinical periodontal studies of its effects in both the treatment of periodontitis and in resolving drug-related gingival overgrowth. Evidence exists to support the use of a single course of azithromycin in the treatment of advanced periodontal diseases. Azithromycin could have a triple role in the treatment and resolution of periodontal diseases: suppressing periodontopathogens, anti-inflammatory activity and healing through persistence at low levels in macrophages and fibroblasts in periodontal tissues, even after a single course of three tablets. If future periodontal research confirms these properties, it could become a valuable host-modulator in periodontal treatment.

Antibacterial and immunomodulatory properties of azithromycin treatment implications for periodontitis

Macrolide antibiotics have been found to possess not only antimicrobial properties, but also modulate inflammation. In this review the multi-faceted properties of azithromycin are discussed. Due to the unique anti-inflammatory and antimicrobial properties, macrolides, and especially azithromycin, are currently used for a number of conditions which have both an inflammatory and microbial component. For the same reason, azithromycin may be of value as an adjunct in the management of periodontitis which, although driven by an infectious component, is largely a result of uncontrolled chronic inflammation.

Periodontal healing and bone regeneration in response to azithromycin

Azithromycin, first synthesized in 1980, is a macrolide antibiotic related to erythromycin. It is widely used by the medical profession as a broad-spectrum antibiotic in the treatment of pneumonia, urinary tract infections and tonsillitis. In addition to its antibiotic properties, azithromycin has immune-modulating effects and is used for this reason in the management of cystic fibrosis and chronic obstructive pulmonary diseases. The drug is taken up by neutrophils, macrophages and fibroblasts, and is slowly released by these cells. Three diverse case reports are presented in which a single course of azithromycin (consisting of one 500 mg tablet being taken a day for three days) was prescribed before any periodontal intervention occurred. Azithromycin was the principal mode of treatment of severe chronic and aggressive periodontitis in Cases 1 and 2. Azithromycin, together with monthly subgingival debridement, was the treatment in Case 3 (severe chronic periodontitis in a poorly controlled diabetic complicated by gingival overgrowth related to medication with a calcium channel blocker). Favourable resolution of inflammation, reduction in pocket depths and evidence of bone regeneration were evident, even when no periodontal treatment had occurred. In Case 3, resolution of gingival overgrowth occurred over eight months. The potential implications for periodontal management, understanding of the pathogenesis of periodontal diseases and periodontal research are briefly discussed.

Radiographic Recognition of Dental Implants as an Aid to Identifying the Deceased

Abstract:  This study was undertaken to determine if dental implants can be radiographically differentiated by company type to aid forensic identification of the deceased. Recognition of dental implants on intraoral radiographic images was assessed in a blind study using a radiographic examination guide to highlight differences between dental implants. Inter‐ and intra‐examiner comparisons were conducted and a computer program (Implant Recognition System®) was evaluated to see whether it improved the accuracy of implant recognition. The study found that dental implants could be radiographically differentiated by company type. The Implant Recognition System® in its current form was of little benefit for radiographic assessment of dental implants for forensic odontologists. Prior knowledge of implant types, with a McNemar’s statistical value of 92.9, proved to be most significant in identification.

Periodontitis and angular alveolar lesions: A critical distinction

Modern anthropologic and epidemiologic studies reveal that the incidence of periodontitis is low in both ancient and modern populations. The distribution of plaque and gingivitis has little or no correlation with the distribution of pathologic alveolar bone loss or with periodontitis. The assumption that a distance from cementoenamel junction to alveolar crest (CEJ-AC distance) greater than 2 mm equates with disease overlooks the interrelationship between the CEJ-AC distance and continuous eruption in compensation for tooth wear and growth of the lower face height. Anatomic, physiologic, and pathologic factors increasing CEJ-AC distances are reviewed. Where horizontal periodontitis does result from gingivitis, it is usually of minimal significance and probably occurs when the host defenses have been diminished by environmental factors commonly associated with other chronic diseases. A pulpal-alveolar explanation for localized angular alveolar lesions better fits the clinical features of this form of periodontal bone loss than does the conventional hypothesis of primary periodontal infection by specific oral bacteria.

Azithromycin suppresses human osteoclast formation and activity in vitro

Azithromycin is an antibiotic with anti‐inflammatory properties used as an adjunct to treat periodontitis, a common inflammatory mediated condition featuring pathologic alveolar bone resorption. This study aimed to determine the effect of azithromycin on human osteoclast formation and resorptive activity in vitro. Osteoclasts were generated from peripheral blood mononuclear cells stimulated with macrophage colony stimulating factor (M‐CSF) and receptor activator of nuclear factor kappa B (RANK) ligand. The effects of azithromycin at concentrations ranging from 0.5 to 40 µg/ml were tested. Osteoclast formation and activity, acidification, actin ring formation and expression of mRNA, and protein encoding for key osteoclast genes were assessed. The results demonstrated that azithromycin reduced osteoclast resorptive activity at all concentrations tested with osteoclast formation being significantly reduced at the higher concentrations (20 and 40 µg/ml). mRNA and protein expression of key osteoclast transcription factor Nuclear Factor of Activated T cells (NFATc1) was significantly reduced by azithromycin at later stages of osteoclast development (day 17). Azithromycin also reduced tumor necrosis factor receptor associated factor‐6 (TRAF6) mRNA expression at day 14, and cathepsin K mRNA expression at days 14 and 17. Integrin β3 and MMP‐9 mRNA expression was reduced by azithromycin at day 17 in osteoclasts cultured on dentine. The osteoclast proton pump did not appear to be affected by azithromycin, however formation of the actin ring cytoskeleton was inhibited. This study demonstrates that azithromycin inhibits human osteoclast function in vitro, which may account for at least some of the beneficial clinical effects observed with azithromycin treatment in periodontitis. J. Cell. Physiol.

Juvenile periodontitis — A new perspective

Juvenile periodontitis (JP) is a severe disease of the periodontium in adolescents. It is usually localized to the first permanent molars and (less commonly) the central incisors. The bacteria Actinobacillus actinomycetemcomitans (Aa) is currently implicated in the aetiology of JP since its numbers are high in JP pockets and low in subjects with healthy periodontal conditions or with adult periodontitis. However, Aa harvested from JP pockets and transferred to healthy sites in the same mouth are unable to colonize these areas or initiate disease (17). The conflicting evidence implicating intrinsic or induced impairment of host defence is reviewed. It is hypothesised that JP lesions are primarily of endodontic origin. By-products of an inflammatory process in the pulp enter the periodontium via dentinal tubules, lateral or furcation canals and drain through the periodontium into the mouth. The environmental conditions of the sinus select for bacteria such as Aa which secondarily infect the site and exacerbate the clinical situation by their potent virulence factors. Localized deep defects involving only one side of an interproximal space in an otherwise periodontally healthy mouth result. Studies of the pulpal status of JP teeth are indicated.