Nadeem Y. Karimbux

Innate immune peptide LL-37 displays distinct expression pattern from beta-defensins in inflamed gingival tissue

Anti‐microbial peptides produced from mucosal epithelium appear to play pivotal roles in the host innate immune defence system in the oral cavity. In particular, human beta‐defensins (hBDs) and the cathelicidin‐type anti‐microbial peptide, LL‐37, were reported to kill periodontal disease‐associated bacteria. In contrast to well‐studied hBDs, little is known about the expression profiles of LL‐37 in gingival tissue. In this study, the anti‐microbial peptides expressed in gingival tissue were analysed using immunohistochemistry and enxyme‐linked immunosorbent assay (ELISA). Immunohistochemistry revealed that neutrophils expressed only LL‐37, but not hBD‐2 or hBD‐3, and that such expression was prominent in the inflammatory lesions when compared to healthy gingivae which showed very few or no LL‐37 expressing neutrophils. Gingival epithelial cells (GEC), however, expressed all three examined anti‐microbial peptides, irrespective of the presence or absence of inflammation. Moreover, as determined by ELISA, the concentration of LL‐37 in the gingival tissue homogenates determined was correlated positively with the depth of the gingival crevice. Stimulation with periodontal bacteria in vitro induced both hBD‐2 and LL‐37 expressions by GEC, whereas peripheral blood neutrophils produced only LL‐37 production, but not hBD‐2, in response to the bacterial stimulation. These findings suggest that LL‐37 displays distinct expression patterns from those of hBDs in gingival tissue.

Interleukin-1 gene polymorphisms and chronic periodontitis in adult whites: a systematic review and meta-analysis.

BACKGROUND Interleukin-1 (IL-1) gene polymorphisms have been associated with increased levels of inflammatory mediators and several inflammatory diseases. Periodontitis is a bacterially induced chronic inflammatory disease that destroys the connective tissues and bone that support the teeth, affects substantial numbers of adults, and has been implicated as a contributing factor in systemic diseases. IL-1 gene polymorphisms, most prominently IL1A (-889), IL1A (+4845), and IL1B (+3954), have been associated with chronic periodontitis (CP) in whites. Since the first report, ≥125 studies have examined IL-1 gene variation in relation to periodontal disease. These studies have produced mixed findings in diverse periodontal phenotypes and in different ethnic groups. One previous meta-analysis has been published on this topic and supported an association between IL-1 genes and periodontitis, but considerable doubt remains about the patient populations in which the association may be of clinical relevance. METHODS A systematic review and meta-analysis was conducted in an attempt to clarify whether IL-1 gene variants were associated with well-defined clinical phenotypes of CP in white patients. Study inclusion criteria focused on the analytic framework originally proposed for the IL-1 genetic effect in which overexpression of inflammatory mediators is hypothesized to result in more severe periodontitis in response to a bacterial challenge. RESULTS Twenty-seven studies were included in the qualitative analysis. Nineteen studies yielded significant associations between carriage of the minor IL-1 alleles and periodontitis. The meta-analysis, based on 13 qualifying studies, found significant effects for the two individual gene variations (IL1A odds ratio [OR] = 1.48; IL1B OR = 1.54) and for a composite genotype that combines minor alleles at each locus (OR = 1.51). Statistically significant heterogeneity was found that could not be explained, but there was no indication of publication bias. CONCLUSION This review and meta-analysis show that IL1A and IL1B genetic variations are significant contributors to CP in whites.

Diminished forkhead box P3/CD25 double-positive T regulatory cells are associated with the increased nuclear factor-kB ligand (RANKL+) T cells in bone resorption lesion of periodontal disease

Periodontal disease involves multi‐bacterial infections accompanied by inflammatory bone resorption lesions. The abundant T and B lymphocyte infiltrates are the major sources of the osteoclast differentiation factor, receptor activator for nuclear factor‐kB ligand (RANKL) which, in turn, contributes to the development of bone resorption in periodontal disease. In the present study, we found that the concentrations of RANKL and regulatory T cell (Treg)‐associated cytokine, interleukin (IL)‐10, in the periodontal tissue homogenates were correlated negatively, whereas RANKL and proinflammatory cytokine, IL‐1β, showed positive correlation. Also, according to the fluorescent‐immunohistochemistry, the frequency of forkhead box P3 (FoxP3)/CD25 double‐positive cells was diminished strikingly in the bone resorption lesion of periodontal disease compared to healthy gingival tissue, while CD25 or FoxP3 single positive cells were still observed in lesions where abundant RANKL+ lymphocytes were present. Very importantly, few or no expressions of FoxP3 by the RANKL+ lymphocytes were observed in the diseased periodontal tissues. Finally, IL‐10 suppressed both soluble RANKL (sRANKL) and membrane RANKL (mRANKL) expression by peripheral blood mononuclear cells (PBMC) activated in vitro in a bacterial antigen‐specific manner. Taken together, these results suggested that FoxP3/CD25 double‐positive Treg cells may play a role in the down‐regulation of RANKL expression by activated lymphocytes in periodontal diseased tissues. This leads to the conclusion that the phenomenon of diminished CD25+FoxP3+ Treg cells appears to be associated with the increased RANKL+ T cells in the bone resorption lesion of periodontal disease.

Temporal and Spatial Expressions of Type XII Collagen in the Remodeling Periodontal Ligament during Experimental Tooth Movement

This study tested the hypothesis that the remodeling processes of adult periodontal ligament (PDL) reiterate the cellular and molecular events that occur sequentially during development. Type XII collagen has been implicated in the three-dimensional organization of the PDL extracellular matrix, and its expression has been restricted to the terminally differentiated stages. This study focused on the examination of the temporal and spatial expression of type XII collagen during experimental PDL remodeling in the rat. The temporal expressions of types I and XII collagen mRNAs were examined by RNA transfer blot and RNase protection assays, respectively, and were found to be relatively stable in the control group throughout the experimental period. In the tooth movement group, the expression of type I collagen increased at 72 hours and sustained the high level of expression at one week, while an increase in the expression of type XII collagen was first noted at the one-week period. The temporal activation of types I and XII collagen expression in the remodeling occurred in a pattern similar to that found during the development of the PDL. The spatial expression of type XII collagen mRNA was examined by in situ hybridization in the one-week-tooth-movement specimens. Labeled cells, which were more evident in the tension side, typically exhibited a spindle shape and were surrounded by the mature PDL matrix. Our data suggest that the type XII collagen expression may be closely associated with the functional regeneration of the PDL.

Site-specific Expression of Collagen I and XII mRNAs in the Rat Periodontal Ligament at Two Developmental Stages

In mammals, the periodontal ligament (PDL) is a highly specialized tissue which facilitates tooth eruption and lends mechanical support to the tooth once in occlusion. The PDL extracellular matrix fibers play a major role in such functions. During its development, the spatial arrangement of the PDL extracellular matrix undergoes rapid changes. So that it could be determined whether the structural alteration in the PDL is associated with changes in the expression of collagenous proteins with different functional properties, the transcriptional patterns of collagens I and XII were examined. The maxillary dento-alveolar segments, each containing three molars, from 25-day-old and 40-day-old Sprague-Dawley rats were selected as being representative of developing and matured tissues, respectively. Rat a2(I) collagen cDNA and rat al(XII) collagen cDNA were used as molecular probes for identification of the corresponding mRNAs by RNA transfer blot analysis, RNase protection assay, and in situ hybridization. The results showed that a2(I) collagen mRNA was expressed in both developing and matured tissues. However, the level of expression decreased with maturity. In contrast, the expression of al(XII) collagen was increased in the matured tissue as compared with the developing tissue. In situ hybridization in these tissues indicated that the expression of al(XII) collagen mRNA was limited to the mature stage of PDL development. It is suggested that collagen fibril arrangement during PDL development may be related to the expression of collagen XII.

Factors Associated With Dental Implant Survival: A 4-Year Retrospective Analysis

BACKGROUND Dental implants are a predictable treatment option for replacing missing teeth and have strong survival and success outcomes. However, previous research showed a wide array of potential risk factors that may have contributed to dental implant failures. The objectives of this study are to study if implant survival rates were affected by known risk factors and risk indicators that may have contributed to implant failures. The secondary outcome measures were whether the level of expertise of the periodontal residents affected success rates and how the rate of implant success at the Harvard School of Dental Medicine (HSDM) compared to published standards. METHODS A retrospective chart review of patients at the HSDM who had one of two types of rough-surface implants (group A or B) placed by periodontology residents from 2003 to 2006 was performed. Demographic, health, and implant data were collected and analyzed by multimodel analyses to determine failure rates and any factors that may have increased the likelihood of an implant failure. RESULTS The study cohort included 341 dental implants. The odds ratio for an implant failure was most clearly elevated for diabetes (2.59 implant surface group B (7.84), and male groups (4.01). There was no significant difference regarding the resident experience. The success rate for HSDM periodontology residents was 96.48% during the 4-year study period. CONCLUSIONS This study demonstrates that implant success rates at HSDM fell within accepted published standards, confirmed previously identified risk factors for a failure, and potentially suggested that other acknowledged risk factors could be controlled for. Furthermore, the level of experience of the periodontology resident did not have an impact on survival outcomes.

The effect of keratinized mucosa width on peri-implant health: a systematic review.

PURPOSE The aim of this systematic review was to investigate the effect of keratinized mucosa width (KMW) on clinical parameters of peri-implant health and stability. MATERIALS AND METHODS Two independent reviewers conducted a comprehensive search to identify studies on human subjects reporting KMW as a bivariate factor (≥ 2 mm and < 2 mm), along with mean pocket depth (PD), bleeding on probing (BOP), modified Bleeding Index (mBI), Gingival Index (GI), Plaque Index (PI), modified PI (mPI), and implant survival with a minimum follow-up of 6 months after implant loading. Eight studies were included in the systematic review and seven in the metaanalyses to ascertain summary effects for differences in the aforementioned parameters among groups of KMW. RESULTS Pooled analyses showed that GI, PI, and mPI were significantly higher in the group with KMW of < 2 mm, while mBI was also higher but only marginally significant. In contrast, PD was not significantly different between the two groups. Differences in BOP and implant survival rate could not be analyzed because of limited data availability. Heterogeneity was highly significant among the pooled studies for all investigated variables. CONCLUSION Reduced KMW around implants appears to be associated with clinical parameters indicative of inflammation and poor oral hygiene. However, based on the selected evidence, the predictive value of KMW is limited.

Parameters defining the potential applicability of Raman spectroscopy as a diagnostic tool for oral disease

Raman spectroscopy can provide information about the molecular composition of tissues, with potential to be applied as a diagnostic tool in lieu of histopathology. Our objectives are to determine if laser Raman spectra (RS) can be acquired reliably from the oral mucosa of patients, and to determine if the RS signature of normal oral mucosa is reproducible among anatomic oral sites and among subjects of different races and gender. 25 Caucasian and 26 Asian subjects are studied using RS with a signal acquisition time of 1 s at seven specified sites within the mouth. Multivariate analysis is used to determine the variability between tissue types and between races and gender. Unique spectra are defined for various sites in the mouth and are likely related to the degree of keratinization. However, spectral concordance by site is not greatly influenced by subject ethnicity or gender. We demonstrate, for the first time, the potential in-vivo application of RS for oral mucosal disease and demonstrate its specificity for particular mucosal types in the mouth. RS offers the potential to provide a diagnosis of disease using a noninvasive, convenient, sensitive technology that provides immediate results.

Hospital based emergency department visits attributed to dental caries in the United States in 2006.

OBJECTIVE There is a paucity of published studies presenting nationally representative estimates on hospital-based emergency department visits primarily attributed to dental caries. The objective of this study is to provide estimates of hospital-based emergency department visits attributed to dental caries in the United States. METHODS The Nationwide Emergency Department Sample, a component of the Healthcare Cost and Utilization Project, sponsored by the Agency for Healthcare Research and Quality, was used for this study. All emergency department visits attributable to dental caries were identified using ICD-9-CM diagnoses codes and selected for analysis. Outcomes including hospital charges and length of stay in hospital were examined. Simple descriptive statistics were used to summarize the data. RESULTS This study found that in 2006, a total of 330,757 visits to hospital-based emergency departments occurred in the United States. The total charges were

Collagen XII Mutation Disrupts Matrix Structure of Periodontal Ligament and Skin

110 million. Approximately 45% of all visits by adults occurred among the uninsured. Medicaid was the most common payer for all visits by children, accounting for nearly 53% of all visits. About 38% of visits occurred among those residing in low-income areas. Hospitalization was required for 158 visits. CONCLUSIONS This study provides nationwide estimates of hospital-based emergency department visits attributed to dental caries in the United States. The uninsured constituted the greatest proportion of emergency department visits among adults, whereas Medicaid was the major payer for children visiting the emergency departments.