Morphology of azurophil lysosomes in polymorphonuclear leukocytes from humans with rapidly progressive periodontitis.

Previous investigations have shown that subjects with rapidly progressive periodontitis (RPP), an early-onset aggressive form of periodontitis, have polymorphonuclear leukocytes (PMNs) with increased intracellular levels of beta-glucuronidase, a characteristic enzyme of azurophil lysosomes. The current study attempted to account for that increase. Ten healthy controls and 10 otherwise healthy subjects with RPP participated. PMNs from peripheral blood were separated, fixed and reacted for peroxidase to identify azurophil lysosomes. Using transmission electron microscopy, 20 PMNs per subject were photographed at 10,000x. Photographs were subsequently digitized and analyzed by computer. RPP PMNs had a higher percentage of the area of the cell profile occupied by azurophil lysosomes compared to control subjects' PMNs. The RPP subjects also had greater absolute numbers of azurophil lysosomes per cell. Lysosome shape was assessed visually. There were no differences between RPP and control groups for lysosome shape, with the majority of lysosomes in each group exhibiting a round or oval shape. RPP lysosomes did exhibit a significantly greater mean size.

Implications of resource-ratio theory for oral microbial ecology.

The ability to compete for the limited nutrients available to the microorganisms of dental plaque is a strong ecological determinant of the structure of the subgingival ecosystem. This paper introduces a new concept from the field of ecology, resource-ratio theory, and applies it to the dynamics of microbial dental plaque with emphasis on the putative periodontal pathogens. Resource-ratio theory is a mechanistic theory of resource competition that utilizes pairs of growth-limiting nutrients in a stoichiometric fashion to predict zones of competitive dominance, exclusion, and coexistence for organisms competing for these resources. Once these resource pairs are identified for plaque organisms, resource-ratio theory may provide predictions of changes in the microbial community structure of plaque based on directional changes in their resource supply ratios.

Clinical evaluation of restored maxillary incisors: veneers vs. PFM crowns.

This cross-sectional study compared the periodontal health and clinical acceptability of maxillary incisors restored with porcelain veneers vs. porcelain-fused-to-metal crowns. The authors evaluated 60 patients, a total of 120 restorations, in groups according to the age of the restorations (zero to 60 months). Margins of veneers were generally more supragingival with less gingival inflammation. All veneers were clinically acceptable, while 5 percent of PFMs failed because of secondary caries.

Increased intracellular levels of lysosomal beta-glucuronidase in peripheral blood PMNs from humans with rapidly progressive periodontitis.

Release of potent lysosomal enzymes by degranulation of polymorphonuclear leukocytes (PMNs) in host gingiva may contribute significantly to tissue destruction and the pathogenesis of periodontal disease. A pilot study established that peripheral blood PMNs from humans with rapidly progressive periodontitis (RPP) contained significantly increased amounts of intracellular lysosomal beta-glucuronidase as compared to healthy controls. This investigation gained insight into the question: are the increased levels of beta-glucuronidase in persons with RPP an a priori genetically determined PMN characteristic, or a reactive phenomenon induced by the periodontal disease process during granulopoiesis? Twelve healthy controls and twelve otherwise healthy individuals with RPP participated in a repeated measures design to T0 (initial, baseline), T1 (four weeks after disease control therapy), and T2 (two months later). At each visit clinical indices (GI, pocket depths, GCF flow, plaque index) were performed and peripheral blood obtained. PMNs were isolated and suspended as 5 x 10(6) cells in 2.0 ml of HBSS. PMN suspensions were tested for total intracellular beta-glucuronidase, degranulation induced by 1 x 10(-6)M and 5 x 10(-7) M FMLP challenges, and unchallenged for non-specific enzyme release. PMNs from individuals with RPP contained significantly higher absolute amounts of beta-glucuronidase and released greater absolute amounts at FMLP challenge at T0, T1, and T2 compared to controls. No relationship was found between any of the clinical indices and beta-glucuronidase levels and no pattern was discovered relating to the repeated measures over time. We conclude that RPP peripheral blood PMNs contain elevated levels of beta-glucuronidase that are not induced by the periodontal disease process.

The effects of the Nd:YAG laser on in vitro fibroblast attachment to endotoxin-treated root surfaces.

The purpose of this study was to evaluate the effects of the Nd:YAG laser on in vitro fibroblast attachment to endotoxin-treated root surfaces and to describe any laser-induced cementum surface alterations. Thirty 4 mm x 4 mm cementum segments were obtained from unerupted third molars. The treatment groups were as follows: 1) control, healthy root segment; 2) non-lased, endotoxin treated; and 3) lased, endotoxin treated. The endotoxin treated roots were soaked in E. coli 055:B5 lipopolysaccharide (556 EU/ml) for 72 hours. The lased, endotoxin-treated root segments were treated with a Nd:YAG laser using a 320 microns contact optic fiber handpiece with an energy setting of 80 mJ at 10 pulses per second for one minute. The root segments were subsequently placed in fibroblast culture dishes for 40 hours and then prepared for scanning electron microscopy (SEM) observation. SEM examination revealed two different types of attachment: flat and round. Flat cells represented firmly attached cells due to well-defined points of attachment and numerous lamellapodia. Round cells possessed few attachment processes and were, therefore, considered poorly attached. The lased, endotoxin-treated root segments had significantly decreased numbers of flat fibroblasts versus the control and non-lased, endotoxin-treated root segments. The absence of flat fibroblasts in the laser treated root segments was a consistent finding. The non-lased, endotoxin-treated root segments had significantly increased numbers of round fibroblasts versus the control and lased, endotoxin treated groups. The lased root segments exhibited surface alterations which included charring, crater formation, cementum meltdown, and tracking.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of Nd:YAG laser exposure on root surfaces when used as an adjunct to root planing: an in vitro study.

The purpose of this study was to evaluate the effects of Nd:YAG laser treatment on root surfaces in vitro when used alone or in combination with conventional scaling and root planing. The study population consisted of 18 unerupted third molars, each with a 3 mm diameter treatment site outlined on the root surface. Three specimens were randomly assigned to each of 6 different treatment groups: 1) untreated control; 2) root planed only; 3) laser treated only using 1.25 W of energy; 4) laser treated only using 1.50 W of energy; 5) laser treated with 1.25 W of energy followed by root planing; and 6) laser treated with 1.50 W of energy followed by root planing. Following their respective treatment, all specimens were prepared for evaluation by scanning electron microscopy. Specimens from Group 2, root planed only, exhibited a smear layer of scale-like texture with parallel instrument tracks resulting from curet use. Specimens treated by laser only, Groups 3 and 4, featured various surface changes not observed in controls such as charring and carbonization of the cementum surface, randomly distributed pitting and crater formation, and melting of the root mineral phase with subsequent resolidification as porous globules. Those specimens treated by laser followed by root planing, Groups 5 and 6, exhibited surface characteristics similar to those noted in Group 2 specimens. Further, there were areas of exposed dentinal tubules resulting from a "peeling" of the cementum layer. The results of this in vitro study suggest that laser use during root preparation, even at relatively low energy levels, will result in physical changes to the root surface.(ABSTRACT TRUNCATED AT 250 WORDS)

Interrater agreement on subgingival calculus detection following scaling.

Accurate and reliable detection of subgingival calculus is a difficult skill which relies on subjective tactile sensations for determinations. This one year retrospective study examined the interrater agreement among a large, generalized pool of clinical examiners who scored residual subgingival calculus after student scaling. Four thousand one hundred and sixty tooth surfaces were analyzed for examiner agreement. Interrater reliability for all paired clinical ratings was low (Kappa = .33). A second, companion study evaluated accuracy and reliability using raters' assessments about the existence of simulated calculus on the root surfaces of manikin teeth. In the second study interrater reliability also was low (Kappa = .34); the true positive and true negative ratios were 49 percent and 88 percent respectively, while the false positive and false negative ratios were 12 percent and 51 percent. These data suggest that there is a need in periodontics for effective examiner calibration methodologies and objective subgingival calculus detection techniques.

Fate of pocket epithelium in an apically positioned flap.

The fate of periodontal pocket epithelium when sulcular incisions are used in apically positioned flap surgery was investigated by serial histology. Human subjects received apically positioned flap segments on the facial aspect of anterior teeth timed to give 1, 3, 5, 7, 21 and 35 days of healing on the day of extraction. Companion surgeries for comparison consisted of similar flaps, but utilized an inverse bevel primary incision. Assessment of the sulcular incision specimens revealed that epithelial degeneration and dissolution occurred within 7 days and resulted in a collagen-to-collagen attachment of the periodontal flap to the alveolar bone. The inverse bevel incision was consistently effective in removing the pocket epithelium and resulted in healing by a connective tissue union of the flap to the alveolar bone. By 21 days of healing, the 2 surgical methods were indistinguishable histologically. On the basis of this investigation, it is suggested that the inverse bevel primary incision traditionally advocated for apically positioned flap surgeries may be replaced by the more rapid and simple sulcular incision as the preferred technique.

Increased intracellular levels of beta-glucuronidase in polymorphonuclear leucocytes from humans with rapidly progressive periodontitis.

The tissue destruction resulting from release of lysosomal enzymes by exocytosis and degranulation of polymorphonuclear leucocytes in host gingiva may contribute significantly to periodontal diseases. In this investigation peripheral blood was obtained from healthy controls and otherwise healthy individuals with rapidly progressive periodontitis. Polymorphonuclear leucocytes were isolated and suspended in HBSS for subsequent in vitro FMLP challenge to induce degranulation. The supernatant was tested for beta-glucuronidase. Polymorphonuclear leucocytes from patients with rapidly progressive periodontitis contained significantly higher absolute amounts of beta-glucuronidase (p less than 0.001) and released greater amounts at various molarities of FMLP antigenic challenge (p less than 0.01). Such an increase in lysosomal enzyme activity may provide an enhanced potential for tissue destruction in this periodontal disease.

Assessment of curette sharpness.

Nothing to date has appeared in the literature addressing the relationship of specific bevel dimension and clinical sharpness of curette blades. This study investigated the degree of clinical sharpness of Gracey curettes following four periods of simulated root planning and, using the scanning electron microscope (SEM), determined the approximate number of strokes at which loss of clinical sharpness became apparent. Seventy-five new stainless steel curette blades were standardized and randomly assigned to one of five groups: control, 30-stroke, 50-stroke, 70-stroke, and 90-stroke. With the exception of the control group, blades underwent a simulated root-planing procedure, on extracted, periodontally involved teeth, which employed a device to standardize pressure and stroke length. Blades were then tested for clinical sharpness using light reflection, with two degrees of magnification; and plastic stick, a tactile evaluation. Blades were photographed under the SEM at a magnification of x1,000. Bevel width was measured at 10 standardized locations on the photomicrographs, and a mean was calculated. Nonparametric data were analyzed using the Kruskal-Wallis statistical test and SEM parametric data using ANOVA and post hoc Newman-Kuels tests. Results showed no significant differences among treatment groups when either tactile or magnification sharpness tests were used. Analysis of the SEM data showed no statistically significant differences among bevel dimensions for any of the five groups. A Spearman rank order correlation, used to compare the clinical data to the SEM bevel measurements, showed no correlation of clinical sharpness and SEM-determined bevel dimension.

Effects of an air-powder abrasive device used during periodontal flap surgery in dogs.

An air-powder abrasive system, the Prophy-Jet, is a commercially available product product intended for use during dental prophylaxis procedures. The purpose of this investigation was to assess the effects on periodontal tissues when the device is used as an adjunct to hand instrumentation in root preparation during periodontal surgery. The degree of tissue injury was assessed by evaluating clinical healing and by histometric analysis of the intensity of the inflammatory response at selected healing times. Surgical sites subjected to Prophy-Jet treatment tended to have slightly lower histometric inflammation scores than control sites treated by hand instrumentation alone. As judged by the inflammatory response and clinical healing, additional effects to surgical exposure of tissues of the periodontium were benign. Use of the Prophy-Jet instrument during periodontal surgery is effective and well tolerated.

Efficacy of face masks in preventing inhalation of airborne contaminants.

Use of surgical face masks has been advocated to protect clinicians from inhalation of aerosols containing organic and inorganic particulates. This study examined the ability of a 22 micron tracer particle to bypass the filtering capability of face mask material by peripheral marginal leakage of inspired air. For two popularly used face masks taped to a facial moulage, recovery of the tracer particle by an in vitro system was very low. When the masks were placed in the manner in which the product is commonly worn, however, significantly higher numbers of particles were recovered. Passage of inspired air around the periphery of two types of face masks appears to circumvent the masks' ability to screen airborne contaminants.