Isotypic antibody response to plaque anaerobes in periodontal disease

BACKGROUND: It has been suggested that locally produced immunoglobulin (Ig)A could be more protective than IgG and that there could be a relationship between crevicular fluid-specific IgA levels and the onset of periodontal disease. This study was designed to investigate this hypothesis regarding specific immune responses towards 4 plaque anaerobes in gingival crevicular fluid and saliva from patients with periodontopathies and controls. METHODS: Gingival crevicular fluid (GCF) and whole saliva were collected from 35 adults with periodontitis and 24 periodontally healthy adults (controls). Antigens were extracted from Actinomyces actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, and Fusobacterium nucleatum and used to set up specific enzyme-linked immunosorbent assay (ELISA) tests to assess IgA and IgG levels to these microorganisms in the fluids collected. RESULTS: The crevicular fluid of periodontitis patients contained significantly higher levels of IgG to the 4 microorganisms tested than that of controls (P < 10(-6) for all comparisons). IgA levels to the 4 bacteria were statistically significantly much higher in control crevicular fluid (P < 10(-7) for all comparisons). Controls also had statistically significantly higher levels of specific salivary IgA than patients (P < 0.02 for all comparisons). CONCLUSIONS: These data support the potentially protective role of specific IgA directed to oral microorganisms involved in the onset and development of periodontal disease.     

Classification of oral clefts by affection site and laterality: a genotype-phenotype correlation study

Objectives – The aim of this study was to classify the phenotypes found in a series of patients with non‐syndromic cleft lip (CL) with or without cleft palate (CP) and isolated cleft palate. Additionally, the frequency distribution of cases belonging to families linked to markers on chromosomes 6 and 2 within these phenotypic patterns were estimated. Design – A retrospective examination of all the available affected cases collected in Italy. Setting and Sample Population – Ninety‐seven affected subjects aged 5–18 years belonging to 38 families were considered. Patterns were identified by variance of the cleft (lip, primary palate, secondary palate) and stratified according to the side of occurrence (right, left, or bilateral). Latent class analysis was used as main statistical tool for carrying out the results. Results – Three homogenous classes were identified (P < 0.0001) by means of latent class analysis. Individuals were assigned to the most suited class. All three variables (lip, primary and secondary cleft palate) generated a specific class. Optimal findings were reported in cases having `any isolated cleft lip' (class 1); `secondary CP with or without bilateral/right primary cleft palate + bilateral/right cleft lip' (class 2); and `left primary cleft palate + left/bilateral cleft lip with or without secondary CP' (class 3). Correspondence to the evidence of linkage to chromosome 6 showed that 9 of 10 cases presenting with `right primary CP + right CL with secondary cleft palate' (class 2) belonged to a linked family. The same combination, but occurring on the left side (class 3), revealed that only three of nine cases belong to families linked to chromosome 6 (P‐value=0.02). The two patterns (right and left) never occurred in the same family. Three reliable groups were identified based on laterality and the presence of a cleft. A single right sided pattern displayed a statistically different distribution of linkage to chromosome 6 when compared with the homologous left side. Conclusion – Non‐syndromic CL with/without CP can be classified according to laterality that can be under genetic control.     

Prevalence of carpal tunnel syndrome and median mononeuropathy among dentists

BACKGROUND: The authors undertook a study to determine the prevalence in dentists of abnormal sensory nerve conduction and/or symptoms of carpal tunnel syndrome, or CTS, the most common nerve entrapment syndrome. METHODS: In a cross-sectional study, dentists (n = 1,079) were screened during the American Dental Association's Annual Health Screening Program in 1997 and 1998 by means of standard electrodiagnostic measures in the dominant hand and a self-reported symptom questionnaire. The authors diagnosed a median mononeuropathy from a 0.5- or 0.8-millisecond, or ms, prolongation of the median sensory-evoked peak latency compared to the ulnar latency. They diagnosed CTS if the subject also had accompanying symptoms of numbness, tingling or pain. RESULTS: Thirteen percent of screened dentists were diagnosed with a median mononeuropathy (using a 0.5-ms prolongation as the criterion), but only 32 percent of these had symptoms consistent with CTS (4.8 percent overall). When the 0.8-ms prolongation was used as the electrodiagnostic criterion, only 2.9 percent (overall) were diagnosed with CTS. People with diabetes, rheumatoid arthritis and obesity were more likely to have a median mononeuropathy. CONCLUSIONS: The prevalence of symptoms consistent with CTS in the dominant hand among dentists was higher than the prevalence in the general population. However, when electrodiagnostic confirmation is added, the prevalence of CTS was nearly the same as that among the general population. CLINICAL IMPLICATIONS: Early recognition of CTS can lead to more effective management. Education regarding ergonomic risk factors can be an effective preventive measure.     

Immunodominant region of Actinobacillus actinomycetemcomitans 40-kilodalton heat shock protein in patients with rheumatoid arthritis

Bacterial heat shock proteins have been implicated in the pathogenesis of several diseases, and the immunological relationship between rheumatoid arthritis (RA) and Escherichia coli DnaJ has been reported. Since there are similarities in the tissue destruction process of RA and periodontitis, we examined the reactivities of antibodies in sera from RA patients to the DnaJ protein from Actinobacillus actinomycetemcomitans. An enzyme-linked immunosorbent assay showed that IgG titers to the N-terminal conservative region of the DnaJ are significantly higher in RA patients compared with the healthy controls (p < 0.05). Furthermore, we examined IgG titers of disease controls to determine the specificity of the immune responses to this region in RA patients. The difference between RA and infectious disease patients was also significant (p < 0.05). These results suggest that the N-terminal region of DnaJ from A. actinomycetemcomitans may contribute to the etiologic analysis of RA.     

Influence of environmental conditions on dentin bond strengths of recently developed dentin bonding systems

A study was conducted to investigate the influence of temperature and relative humidity (RH) on the bond strengths of several recently developed dentin bonding systems. Six environmental conditions, (A) 25+/-0.5 degrees C, 50+/-5% RH, (B) 25+/-0.5 degrees C, 80+/-5% RH, (C) 25+/-0.5 degrees C, 95+/-5 % RH, (D) 37+/-0.5 degrees C, 50 +/-5 % RH, (E) 37+/-0.5 degrees C, 80+/-5% RH, (F) 37+/-0.5 degrees C, 95+/-5 % RH were used. Bovine mandibular incisors were mounted in self-curing resin and the facial surfaces were ground on wet #600 SiC paper to expose the dentin. After the tooth surface had been treated according to each manufacturer's instructions, adhesives were applied, followed by condensation of resin composites into a mold placed on the dentin surface. Fifteen specimens per group were stored in distilled water at 37 degrees C for 24 h, and then shear-tested at a cross-head speed of 1.0 mm/min. Statistical analysis was carried out with two-way ANOVA followed by Tukey's test (P<0.05). Dentin bond strengths decreased with increasing relative humidity but were not influenced by environmental temperature. Even though one-bottle adhesive systems require a wet dentin surface, their bond strengths are affected by an increase in environmental humidity.     

Induction of dental pulp fibroblast matrix metalloproteinase-1 and tissue inhibitor of metalloproteinase-1 gene expression by interleukin-1alpha and tumor necrosis factor-alpha through a prostaglandin-dependent pathway

Matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of metalloproteinase-1 (TIMP-1) are involved in the degradation of extracellular matrix in many inflammatory diseases. Little is known regarding the expression of these mediators in dental pulp fibroblasts. The effects of proinflammatory cytokines (interleukin (IL)-1alpha and tumor necrosis factor-alpha (TNF-alpha)) and prostaglandin E2 (PGE2) on pulp fibroblast MMP-1 and TIMP-1 gene expression were investigated. Northern hybridization showed that IL-1alpha and TNF-alpha induced significant MMP-1 gene expression, with only little effect on TIMP-1 gene. Exogenous PGE2, however, upregulated TIMP-1 mRNA synthesis but not MMP-1. Concomitant addition of IL-1alpha and PGE2 or TNF-alpha and PGE2 suppressed MMP-1 mRNA production, compared with the groups treated with IL-1alpha or TNF-alpha alone. In contrast, PGE2 enhanced the upregulatory effects of TIMP-1 mRNA by IL-1alpha or TNF-alpha. Furthermore, cytokine stimulation of MMP-1 and TIMP-1 gene expressions can be enhanced or blocked by indomethacin, respectively, and reversed by exogenous PGE2. These results suggested that cytokine-stimulated MMP-1 and TIMP-1 gene expression in dental pulp fibroblasts was mediated, at least in part, by a prostaglandin-dependent pathway. The differential regulation of IL-1alpha or TNF-alpha-induced MMP-1 and TIMP-1 mRNA synthesis, as well as the direct upregulation of TIMP-1 gene expression by PGE2, also implied that prostaglandin may serve as a protective mechanism from excessive tissue breakdown during pulpitis.     

Multidimensional osteodistraction for correction of implant malposition in edentulous segments

This study examined multidimensional osteodistraction as a treatment method for correction of implant malposition and as an alternative to augmentation procedures. The prosthetically unfavourable implant positions were due to growth-related implant malposition (in the context of treatment of young patients with oligodontia) or primary bone-driven implant insertions. The radiographical and clinical findings obtained with this osteodistraction technique are presented and discussed. A tooth-supported osteodistractor for multidimensional distraction with custom-fabricated distraction abutments was used for treatment of 8 patients with a total of 9 maxillary and mandibular edentulous segments including single-tooth gaps. All patients underwent an osteotomy at a minimum distance of 1 mm from the implant surface. Following primary wound healing, distraction was carried out by 1 mm in vertical direction and 0.5 mm in the demanded transverse direction daily until the prosthetically optimized position was achieved. During and after the 12-week retention phase, the patients were evaluated clinically and radiographically. Multidimensional osteodistraction was carried out successfully in all 8 patients. The distraction distances were 3 to 11 mm in vertical direction and a maximum of 5 mm in buccolingual/buccopalatal direction. The malpositioned implants were brought into a prosthetically optimized position in all cases. The results of this study show that this multidimensional osteodistraction technique allows both augmentation of edentulous segments with a clearly compromised implant host site and correction of unfavourable implant positions.     

Gelatinase A (MMP-2) in developing tooth tissues and amelogenin hydrolysis

Matrix metalloproteinases (MMPs) are thought to play important roles during enamel and dentin biomineralization. Previously, membrane type-1 matrix metalloproteinase (MT1-MMP) was localized to the plasma membranes of ameloblasts and odontoblasts of the developing tooth. The best-characterized function of MT1-MMP is to initiate the activation of gelatinase A (MMP-2). Thus, we hypothesized that gelatinase A may also be expressed by developing tooth tissues. A full-length porcine gelatinase A mRNA was isolated by RT-PCR homology cloning of an enamel-organ-specific cDNA library. Northern blot and in situ hybridization analyses demonstrated gelatinase A expression in developing tooth tissues. Immunohistochemical analysis localized gelatinase A close to the plasma membrane of these tissues. Furthermore, recombinant gelatinase A was demonstrated to cleave recombinant amelogenin into several fragments of differing molecular masses. Thus, gelatinase A is expressed by developing tooth tissues along with its activator MT1-MMP and may, therefore, play an important role during tooth development.     

A possible "rescue" procedure for dental implants with a textured surface geometry: a case report.

Dental implants with textured surfaces are a valuable adjunct in restoring edentulous sites of poor bone quality and quantity, but on occasion may become denuded of bone and require "rescue." We report here the successful management of an intrabony crater affecting a single porous-surfaced dental implant using a combination of citric acid decontamination and grafting with freeze-dried, demineralized allograft covered with a barrier of calcium sulfate.