A model of periodontitis in the rat: effect of lipopolysaccharide on bone resorption, osteoclast activity, and local peptidergic innervation

OBJECTIVE: To establish and characterise a rat model of periodontitis that reiterates the features of human disease. METHODS: Periodontal inflammation was induced by a single injection of 10 microg liposaccharide (LPS) (Salmonella typhimurium) in 1 microl saline into rat mandibular gingiva at the buccomesial aspect of the second molar. Animals were killed after 3, 7 and 10 days, mandibles dissected and sectioned for histological and immunocytochemical analysis. RESULTS: LPS injection resulted in a significant gingival and periodontal inflammation with inflammatory infiltrate, apical migration of the junctional epithelium, interdental bone loss, and activation of osteoclasts at the site of injection 7 and 10 days after injection. At 10 days post injection, there was a significant trend for bone loss on both sides of the mandible. Periodontal inflammation was associated with alteration in the levels of calcitonin gene-related peptide-like immunoreactivity in nerve terminals innervating the inflamed gingival papilla. CONCLUSION: Intragingival injection of LPS in the rat provides an easily induced reproducible experimental model of periodontal inflammation that reiterates features of human disease.     

Sensitivity, specificity, and positive predictive value of oral opportunistic infections in adults with HIV/AIDS as markers of immune suppression and viral burden

OBJECTIVES: The purpose of this study was to assess the use of human immunodeficiency virus (HIV)-related oral opportunistic infections as markers of immune suppression and viral burden in adults with HIV/acquired immunodeficiency syndrome (AIDS). METHODS: The population consisted of a single institution observational cohort involving 606 patients with HIV/AIDS with CD4 count data and 277 with plasma viral load measurements examined between 1995 and 1999 for the presence of oral manifestations of HIV. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value is reported for the association of specific oral lesions and lesion sets with CD4 counts <200 cells/mm(3) and with plasma HIV RNA >/=20,000 copies/mL. RESULTS: Lesions with moderate-to-high PPVs for CD4 <200 cells/mm(3) were as follows: Kaposi's sarcoma (100%; P =.035), pseudomembranous candidiasis (82. 2%; P <.001), linear gingival erythema (70.0%; P =.015), hairy leukoplakia (66.3%; P <.001), angular cheilitis (60.0%; P =.128), and erythematous candidiasis (58.3%; P =.061). Necrotizing ulcerative periodontal diseases, HIV salivary gland disease, oral ulcers, and oral warts had PPVs below 50%. Concurrent infection with candidiasis and hairy leukoplakia had the highest PPV of 89.3%; P <. 001. PPVs for HIV RNA >/=20,000 copies/mL ranged from 27.3% to 100%, with significant association only for pseudomembranous candidiasis. CONCLUSIONS: Specific common oral lesions are strongly associated with immune suppression, as measured by CD4 cell counts, and are modestly associated with high viral burden, thus serving as potential clinical markers of HIV viremia and the consequent destruction of the immune system with progressive HIV disease.     

Ridge preservation utilizing an acellular dermal allograft and demineralized freeze-dried bone allograft: Part II. Immediate endosseous implant placement

When maxillary anterior teeth are extracted, subsequent ridge collapse can significantly compromise esthetics. Preservation of an adequate volume of bone is vital to successful implant placement. Ridge preservation achieved utilizing an acellular dermal matrix as a barrier membrane with a demineralized freeze-dried bone allograft has been previously reported. In this case presentation, guided bone regeneration was achieved around an immediate endosseous implant when this same technique was used. As in the previous case reports, this technique demonstrated an acceptable esthetic result with virtually no loss of ridge height or width. Soft tissue dimensions were also preserved. Both the hard and soft tissue grafts were well accepted by the body and healing was rapid and without significant discomfort. This surgical technique provides the clinician with an option to provide immediate implant therapy when primary closure cannot be achieved.     

Use of xylitol chewing gum among Finnish schoolchildren

The preventive, and partly the remineralizing, effect of xylitol was shown in Finland in the Turku Sugar Studies in 1971-73. Since then, several clinical trials in many countries have confirmed these results. In Finland, oral health personnel have recommended daily use of xylitol chewing gum in their dental health education. Moreover, commercial companies have advertised xylitol, emphasizing in particular its caries preventive effects. All Nordic dental associations have given their recommendations for xylitol use. The aim of this study was to describe how this health habit has been adopted by Finnish schoolchildren. The study was part of the comprehensive cross-national survey on Health Behavior in School-aged Children (HBSC Study)--a WHO Collaborative Study. The data were collected using standardized questionnaires to which pupils in grades 5 (11 years), 7 (13 years) and 9 (15 years) responded anonymously in school classrooms during the spring term 1998. The response rate varied between 87% (15-year-old boys) and 94% (11- and 13-year-old girls). Among boys, the percentages of daily users of xylitol chewing gum were 47% (11 years), 46% (13 years), and 44% (15 years), and among girls, 57% (11 years), 65% (13 years), and 69% (15 years), respectively. Use of sugar-sweetened chewing gum was very rare (1%), as also was use of chewing gum with other artificial sweeteners (1%). It may be concluded that since 1991 the use of xylitol chewing gum has further increased in Finland and currently more than a half of all schoolchildren benefit from it.     

Dental Utilization by Low-income Mothers

Objective : This study examines the influence of predisposing, enabling, and need variables on whether low-income mothers sought dental care during the past year. This report is a substudy of mothers and children on their self-reported health status, utilization, access, and satisfaction with health care in general. Methods : A convenience sample of 502 mothers and youngest child younger than 6 years old was administered a face-to-face questionnaire in four Ohio counties. Information was collected at county human services offices and WIC clinics between November 1995 and July 1996. Using whether or not the mother sought dental care as the dependent variable, logistic regression models were created for the variables within the predisposing, enabling, and need characteristics separately and together. Results : Fewer than one-half of the mothers sought dental care during the past year. Variables associated with the predisposing characteristic explained little about who sought care. Those mothers who have Medicaid coverage are 2.7 times more likely to have a dental visit than those without insurance. Moreover, those mothers who perceive any dental need are several times less likely to have received dental care than those who have no perceived need. Conclusion : Even among a somewhat homogeneous population of low-income women, source of payment for dental services and perceived need for dental care are discriminating variables in determining who seeks dental care.     

Host response in experimental periodontal disease

Experiments were performed to determine the role of the immune response in rat periodontal disease. Germ-free rats were fed defined antigen-free liquid diets or a diet containing ovalbumin(OVA) as a prototype antigen. The OVA-fed rats demonstrated increased gingival lymphocytes (mainly T at early times), OVA-sensitized spleen cells, and increased periodontal bone loss. In further studies, rats pre-sensitized with OVA, and receiving OVA in the diet, showed elevated IgG antibody, sensitized spleen cells, and elevated periodontal bone loss scores. The concept that bone loss was due to mixed hypersensitivity reaction is consistent with the periodontal pathology. The effects of pre-immunization with A. actinomycetemcomitans (Aa) on periodontal bone loss in Actinobacillus (Aa) - infected rats was examined. Delayed hypersensitivity (DTH) was present in immunized rats throughout the experimental period. Sham-immunized rats showed DTH after 30 days of infection. In addition, immunized rats showed elevated bone loss scores. These experiments support the contention that a combination of hypersensitivity reactions (i.e., mixed hypersensitivity to Aa) could give rise to the periodontal pathology observed. Congenitally athymic rats (nude) were shown to have more periodontal bone loss than did normal littermates. However, bone loss in thymus-cell reconstituted nude rats was not different from that in control rats. Normal rats receiving Aa-sensitized T lymphocytes prior to infection with Aa demonstrated increased DTH and periodontal bone loss. These studies support the concept that T-cell functions and thymic regulation of immune responses can exert protective and/or destructive effects in periodontal disease. In order to modify disease, it will be necessary to enhance the protective aspects of the immune response and to minimize the detrimental aspects.     

Cell-to-cell communication of osteoblasts.

Osteoblasts were investigated by two methods, electrical conductance and dye injection. Current injection into one cell caused a change in the recorded transmembrane potential of a second cell, indicating high conductance pathways between the two cells. Dyes injected into a single osteoblast were transmitted to numerous surrounding cells.     

Facial duplication -- the unique case of Antonio.

A case of facial duplication with its surgical correction in childhood and the consequences on facial growth is reported. It is a unique case in the duration of observation. The following structures were fully duplicated: the nose, the premaxilla, the cribriform plate, the crista galli. In addition there was an enormous facial cleft including lip, alveolus and palate. Additionally there were two rudimentary eye sockets, eyes, and two supplementary eyebrows. The monstrous hypertelorism with the facial duplication was corrected at the age of ten. The surgical procedure is described and the postoperative complications are discussed. Gross lack of growth of the middle third of the facial skeleton was observed. This was probably the consequence of the initial corrective surgery. Overgrowth of the mandible created a gorilla-like appearance by the end of the growth period. This was corrected in one operation by advancement of the middle third in three sections and repositioning of the mandible as a whole together with the mandibular anterior alveolar segment. Finally all parts of the lower half of the nose had to be enlarged, both soft tissues as well as the cartilaginous framework. A pharyngoplasty in addition to the correction of the intermaxillary abnormalities did much to improve the speech quality of the patient. A large secondary cranial defect was successfully reconstructed with the use of 14 halved ribs. In spite of the removal of four ribs from one side and three ribs from the other, there were no postoperative respiratory problems. Spontaneous rib regeneration was found where ribs had been removed one year earlier.