Histologic evaluation of human extraction sockets treated with demineralized freeze-dried bone allograft (DFDBA) and cell occlusive membrane.

This study evaluated new bone formation in human extraction sockets treated with demineralized freeze-dried bone allografts (DFDBA) and celloc occlusive membranes. Hard tissue biopsies of 7 sites in 6 patients were obtained 14 weeks to 13 months following extraction and grafting. Histologic analysis revealed that individual particles of DFDBA were discernible up to 13 months in situ. In all samples, all particles of DFDBA were well incorporated within new bone, which exhibited osteocyte-containing lacunae. Distinct cement lines clearly demarcated the DFDBA particles from the surrounding, intimately-apposed woven and lamellar bone. The marrow demonstrated a mild degree of fibrosis without signs of inflammatory reaction. There was also a notable lack of fibrous encapsulation of the allograft, and little osteoclasis was observed. Our findings demonstrate that commercially available DFDBA has the potential to function physically as a nidus for appositional new bone growth in alveolar sockets following tooth extraction. Further investigations of the biological activity of DFDBA in situ are warranted.

Effect of inflammation on the proliferation of human gingival epithelial cells in vitro.

The adaptive or pathologic responses of epithelial cells to inflammation are poorly characterized. The purpose of this study was to determine if epithelial cells cultured from clinically healthy and inflamed human gingival tissues express differences in proliferation rate and viability. Briefly, the inflammation status of individual donor sites from 101 patients was visually assessed at the time of periodontal surgery and categorized as either non-to-slightly inflamed, moderately inflamed, or severely inflamed. Discarded gingival tissues were then processed to obtain primary cell cultures, for which proliferation rates were determined by calculating the ratio of mean population doublings to the number of days required for cultures to become confluent. In general, the cells in the minimally inflamed group exhibited characteristics different than cells in the moderately and severely inflamed groups. Specifically, the cells obtained from clinical sites which exhibited no-to-slight inflammation had a significantly higher mean proliferation rate than cells in either the moderate inflammation group or the severe inflammation group. Based on trypan blue exclusion, the cells obtained from clinical sites which exhibited no-to-slight inflammation also were more viable than cells obtained from sites with moderate inflammation or severe inflammation. Microscopic evaluation showed morphological changes associated with increased inflammation. Cell cycle analysis by fluorescent-activated cell sorting (FACS) revealed a directly proportional relationship between the degree of inflammation and apoptosis, and a strong inversely proportional trend between the degree of inflammation and the numbers of cells undergoing mitosis. Taken together, these data suggest that epithelial cell proliferation and viability are inversely associated with the degree of gingival inflammation, once a putative "adaptive threshold" is exceeded. Elucidation of the underlying mechanisms will likely lead to improvements in clinical diagnosis and treatment.

Use of a serially layered, double connective tissue graft approach to enhance maxillary anterior esthetics.

The demands of current periodontal practice require that clinicians use varied approaches to resolve poor esthetic appearances. In particular, patients are becoming less and less accepting of exposed roots and lost interdental papillae, especially in the maxillary anterior sextant. This report describes a surgical technique that combines the advantages of a root-coverage procedure using subepithelial connective tissue grafts and an incision design that preserves interdental papillae, coupled with the use of enamel matrix derivative (Emdogain) to maximize the regenerative potential.

GBR in human extraction sockets and ridge defects prior to implant placement: clinical results and histologic evidence of osteoblastic and osteoclastic activities in DFDBA.

This study evaluated new bone formation in 3 types of osseous defects following treatment with demineralized freeze-dried bone allografts (DFDBA) and cell-occlusive membranes. For 8 patients electing to receive implant treatment, a distinction was made among 3 clinical situations: (1) existing alveolar ridge defects; (2) extraction sockets with lost buccal plate; and (3) extraction sockets with an intact alveolus. Implants were placed a mean of 6 months after the regenerative procedure. Clinical examination of bone width and height at the time of implant placement showed sufficient augmentation or preservation, and implants were inserted without incident. Histologic examination of hard tissue biopsies obtained from the implant sites revealed no discernible differences among the 3 types of defects. Specifically, all sites demonstrated DFDBA particles surrounded by woven or lamellar bone. No fibrous encapsulation of DFDBA or inflammatory reaction was observed. Osteoblasts were found lining marrow spaces. Howeship's lacunae, with and without resident osteoclasts, were clearly seen in several DFDBA particles; this finding supports the belief that DFDBA undergoes osteoclasis in vivo. These results demonstrate that commercially available DFDBA has osteoconductive properties that lead to appositional new bone growth in both self-contained and non-self contained osseous defects.

Physical and chemical aspects of saliva as indicators of risk for dental caries in humans.

The etiology and pathogenesis of dental caries are known to be multifactorial, but the interplay between intrinsic and extrinsic factors is still not fully understood. As in other host/parasite interactions, there appear to be marked variations in individual susceptibility to the disease. It therefore is likely that intrinsic host factors play a key role in modulating the initiation and progression of caries. The objective of this systematic review was to evaluate critically the evidence supporting the role and effects of saliva in caries pathogenesis. The full-length evidence report, including evidence tables, and the structured abstract presented at the NIH/NIDCR Consensus Development Conference on the Diagnosis and Management of Dental Caries Throughout Life, March 26-28. 2001, can be accessed at the web site http://www.nidcr.nih.gov. The present abridged report is a summary of the main findings from our evidence-based review.

Anesthetic management of lithium-treated patients.

In order to establish a protocol for the anesthetic management of patients undergoing lithium therapy, one must consider the mechanisms of lithium action. Many proposals for different mechanisms appear in the literature which attempt to explain the pharmacology, physiology, metabolism, administration, dosage and adverse effects of lithium. This paper reviews the pertinent scientific and clinical information to enable the anesthesiologist to rationally administer anesthesia to patients on a lithium regimen.

Vitamin D and periodontal health in older men.

Vitamin D, an anti-inflammatory mediator, has potential benefits for physical and oral health. Although it is produced endogenously, some individuals have a greater need for dietary and supplemental sources. This repeated-measures cross-sectional study assessed associations between total vitamin D intake and periodontal health in older men. Participants were 562 members of the Department of Veterans Affairs Dental Longitudinal Study, mean age 62.9 years, who were examined 1 to 4 times between 1986 and 1998. A calibrated examiner measured probing pocket depth (PPD) and attachment loss (AL) on each tooth. Alveolar bone loss (ABL) was determined from radiographs. Severe periodontal disease was defined as PPD ≥ 5 mm on ≥ 1 tooth and AL ≥ 6 mm at ≥ 2 sites (not on same tooth), and moderate-to-severe alveolar bone loss as ABL ≥ 40% at ≥ 3 sites. Generalized estimating equations were used to compute the odds ratios (OR) and 95% confidence intervals (95% CI) of having periodontal disease by level of vitamin D intake. Total vitamin D intake ≥ 800 IU was associated with lower odds of severe periodontal disease (OR = 0.67, 95% CI = 0.55-0.81) and moderate-to-severe ABL (OR = 0.54, 95% CI = 0.30-0.96) relative to intake < 400 IU/day. Vitamin D intake may protect against periodontal disease progression.

Host responses in the etiology and pathogenesis of periodontal disease.

Periodontal disease is an inflammatory condition of the supporting structures of teeth. This condition is actually considered to be caused by a number of different diseases, possibly associated with different etiologies, rather than a single disease. Due to limitations in our present understanding of cellular and molecular events involved in the pathogenesis of various periodontal diseases, many therapeutic failures still occur. For this reason, studies concerning the responses of the host to pathogenic bacteria are thought to be critically important. This review presents current opinions on the role of host responses in periodontal disease.

Isolation and characterization of heparan sulfate proteoglycans produced by cloned rat microvascular endothelial cells.

We have isolated heparan sulfate proteoglycans (HSPGs) from cloned rat microvascular endothelial cells using a combination of ion-exchange chromatography, affinity fractionation with antithrombin III (AT III), and gel filtration in denaturing solvents. The anticoagulantly active heparan sulfate proteoglycans (HSPGact) which bind tightly to AT III bear mainly anticoagulantly active heparan sulfate (HSact) whereas the anticoagulantly inactive heparan sulfate proteoglycans (HSPGinact) possess mainly anticoagulantly inactive heparan sulfate (HSinact). HSact and HSinact were also isolated by a combination of ion-exchange chromatography, treatment with protease and chondroitin ABC lyase, and affinity fractionation with AT III. HSact and HSinact have molecular sizes of about 25-30 kDa with the same overall composition of monosaccharides except that HSact exhibits about nine glucuronsyl 3-O-sulfated glucosamines/chain whereas HSinact possesses about three glucuronsyl 3-O-sulfated glucosamines/chain. Direct isolation of the AT III-binding site of HSact by exposing carbohydrate chains to Flavobacterium heparitinase in the presence of protease inhibitor revealed only a single interaction site which contained two to three glucuronsyl 3-O-sulfated glucosamine residues. The core proteins of HSPGact and HSPGinact were isolated by treatment with Flavobacterium heparitinase and purification by ion-exchange chromatography. The molecular sizes of the core proteins were established by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and their primary structures were examined by cleavage with trypsin or endopeptidase Glu-C as well as separation of peptides by reverse-phase high performance liquid chromatography. The results showed that both sets of core proteins exhibited three major components with molecular sizes of 50, 30, and 25 kDa, respectively. The 25-kDa species appears to be a proteolytic degradation product of the 30-kDa species. The peptide mapping revealed that HSPGact and HSPGinact possess extremely similar core proteins.

Identification of early microbial colonizers in human dental biofilm.

AIMS: To elucidate the first colonizers within in vivo dental biofilm and to establish potential population shifts that occur during the early phases of biofilm formation. METHODS AND RESULTS: A 'checkerboard' DNA-DNA hybridization assay was employed to identify 40 different bacterial strains. Dental biofilm samples were collected from 15 healthy subjects, 0, 2, 4 and 6 h after tooth cleaning and the composition of these samples was compared with that of whole saliva collected from the same individuals. The bacterial distribution in biofilm samples was distinct from that in saliva, confirming the selectivity of the adhesion process. In the very early stages, the predominant tooth colonizers were found to be Actinomyces species. The relative proportion of streptococci, in particular Streptococcus mitis and S. oralis, increased at the expense of Actinomyces species between 2 and 6 h while the absolute level of Actinomyces remained unaltered. Periodontal pathogens such as Tannerella forsythensis(Bacteroides forsythus), Porphyromonas gingivalis and Treponema denticola as well as Actinobacillus actinomycetemcomitans were present in extremely low levels at all the examined time intervals in this healthy group of subjects. CONCLUSION: The data provide a detailed insight into the bacterial population shifts occurring within the first few hours of biofilm formation and show that the early colonizers of the tooth surface predominantly consist of beneficial micro-organisms. SIGNIFICANCE AND IMPACT OF THE STUDY: The early colonizers of dental plaque are of great importance in the succession stages of biofilm formation and its overall effect on the oral health of the host.