Determination of the presence of root-bound endotoxin using the local Shwartzman phenomenon (LSP)

An integrated analysis of rare CNV and exome variation in Autism Spectrum Disorder using the Infinium PsychArray

Autism spectrum disorder (ASD) is a neurodevelopmental condition with a complex and heterogeneous genetic etiology. While a proportion of ASD risk is attributable to common variants, rare copy-number variants (CNVs) and protein-disrupting single-nucleotide variants (SNVs) have been shown to significantly contribute to ASD etiology. We analyzed a homogeneous cohort of 127 ASD Italian families genotyped with the Illumina PsychArray, to perform an integrated analysis of CNVs and SNVs and to assess their contribution to ASD risk. We observed a higher burden of rare CNVs, especially deletions, in ASD individuals versus unaffected controls. Furthermore, we identified a significant enrichment of rare CNVs intersecting ASD candidate genes reported in the SFARI database. Family-based analysis of rare SNVs genotyped by the PsychArray also indicated an increased transmission of rare SNV variants from heterozygous parents to probands, supporting a multigenic model of ASD risk with significant contributions of both variant types. Moreover, our study reinforced the evidence for a significant role of VPS13B, WWOX, CNTNAP2, RBFOX1, MACROD2, APBA2, PARK2, GPHN, and RNF113A genes in ASD susceptibility. Finally, we showed that the PsychArray, besides providing useful genotyping data in psychiatric disorders, is a valuable and cost-efficient tool for genic CNV detection, down to 10 kb.

Minimally-invasive non-surgical periodontal therapy

Periodontitis is a complex disease that has both oral and systemic consequences. The treatment of periodontitis may be both surgical and non-surgical but, in recent years, there has been a shift towards managing disease non-surgically in preference to surgery. Fundamental to all types of therapy is the patient's role in disease control, in the form of self-performed plaque control, and it is important that the patient understands this. Non-surgical periodontal therapy has a long history and has traditionally been carried out using a variety of hand and powered instruments, the objective being root surface disinfection by the removal of plaque, calculus and contaminated root cementum. However, over the last 30 years or so, it has become apparent that calculus does not cause disease, cementum does not become significantly infected and bacteria and their toxins are only loosely adherent to the diseased root surface. This has led to the development of less invasive instrumentation principles which may be better for patients, more cost-effective and more easily applied in different clinical settings.

CLINICAL RELEVANCE

This paper aims to describe and justify a minimally-invasive approach to the management of the diseased root surface in periodontitis, to clarify the terminology used and to suggest how these principles may be applied in general practice.

Coronally advanced flap procedure for root coverage. Treatment of root surface: root planning versus polishing

This clinical study was designed to determine if mechanical instrumentation (root planing) of the exposed root is useful in treating gingival recession caused by traumatic toothbrushing following a coronally advanced flap (CAF). Ten patients with high levels of oral hygiene (full-mouth plaque score <20%), from 25 to 57 years of age, were selected for the study. Each patient showed 2 bilateral Class I or II maxillary recessions. A total of 20 recessions were treated. The difference in the recessions was < or =1 mm. In each patient, one recession was randomly assigned to the test group and the contralateral one to the control group. In the test group, the exposed root surface was polished at slow speed with a rubber cup and prophylaxis paste for 60 seconds. In the control group, the exposed root surface was planed with a sharp curet. In both test and control groups, a trapezoidal full- and partial-thickness flap was elevated, coronally displaced, and sutured to cover the treated root surface. Before treatment, the mean recession depth in the test group (polishing) was 3.1+/-1.1 mm; and in the control group (root planing), 2.9+/-1.0 mm. Three months after the described procedures, the test group (polishing) showed a mean recession reduction of 2.6+/-0.6 mm; mean percent root coverage was 89+/-14%. In the control group (root planing), the mean recession reduction was 2.3+/-0.7 mm and mean percent root coverage was 83+/-16%. The difference of recession reduction between the test and control group was not statistically significant (P = 0.1405), even though the test group showed slightly better clinical results in terms of root coverage. This prospective clinical, controlled, randomized study shows that mechanical instrumentation (root planing) of the exposed root surfaces is not necessary when shallow recessions caused by traumatic toothbrushing are treated using a coronally advanced flap (CAF) in patients with high levels of oral hygiene.

Dental calculus: recent insights into occurrence, formation, prevention, removal and oral health effects of supragingival and subgingival deposits

Dental calculus, both supra- and subgingival occurs in the majority of adults worldwide. Dental calculus is calcified dental plaque, composed primarily of calcium phosphate mineral salts deposited between and within remnants of formerly viable microorganisms. A viable dental plaque covers mineralized calculus deposits. Levels of calculus and location of formation are population specific and are affected by oral hygiene habits, access to professional care, diet, age, ethnic origin, time since last dental cleaning, systemic disease and the use of prescription medications. In populations that practice regular oral hygiene and with access to regular professional care, supragingival dental calculus formation is restricted to tooth surfaces adjacent to the salivary ducts. Levels of supragingival calculus in these populations is minor and the calculus has little if any impact on oral-health. Subgingival calculus formation in these populations occurs coincident with periodontal disease (although the calculus itself appears to have little impact on attachment loss), the latter being correlated with dental plaque. In populations that do not practice regular hygiene and that do not have access to professional care, supragingival calculus occurs throughout the dentition and the extent of calculus formation can be extreme. In these populations, supragingival calculus is associated with the promotion of gingival recession. Subgingival calculus, in "low hygiene" populations, is extensive and is directly correlated with enhanced periodontal attachment loss. Despite extensive research, a complete understanding of the etiologic significance of subgingival calculus to periodontal disease remains elusive, due to inability to clearly differentiate effects of calculus versus "plaque on calculus". As a result, we are not entirely sure whether subgingival calculus is the cause or result of periodontal inflammation. Research suggests that subgingival calculus, at a minimum, may expand the radius of plaque induced periodontal injury. Removal of subgingival plaque and calculus remains the cornerstone of periodontal therapy. Calculus formation is the result of petrification of dental plaque biofilm, with mineral ions provided by bathing saliva or crevicular fluids. Supragingival calculus formation can be controlled by chemical mineralization inhibitors, applied in toothpastes or mouthrinses. These agents act to delay plaque calcification, keeping deposits in an amorphous non-hardened state to facilitate removal with regular hygiene. Clinical efficacy for these agents is typically assessed as the reduction in tartar area coverage on the teeth between dental cleaning. Research shows that topically applied mineralization inhibitors can also influence adhesion and hardness of calculus deposits on the tooth surface, facilitating removal. Future research in calculus may include the development of improved supragingival tartar control formulations, the development of treatments for the prevention of subgingival calculus formation, the development of improved methods for root detoxification and debridement and the development and application of sensitive diagnostic methods to assess subgingival debridement efficacy.

Removal of hard tooth structure by ROOTSHAPE root planing files used with a modified EVA contra-angle

The results of numerous recent investigations indicate that root contamination with bacteria and endotoxins is limited to the root surface only. Therefore, methods on root surfaces instrumentation that preserve root substance should be focused on. Newly available instruments or treatment systems should be evaluated for their root substance-removing potential. The devices for root planing presented here comprised specific files (Rootshape) (with diamond-coating on their convex working surfaces used in conjunction with a water-spray-cooled contra-angle head transforming rotational movements into translatory oscillations. The substance-removal potential of rigid and flexible files with diamond coatings of 2-4, 15, 25 and 40 microns compared with that of regular hand curettes, was evaluated under various working forces. The results demonstrated, that depending on the grit size of the diamond coating, the Rootshape files removed less and in no instance greater amounts of root surface substance than did hand instruments.

The periodontally-involved root surface

Recent years have seen much research on the periodontally-involved root surface. Many of these studies have produced results which suggest that plaque contaminants of the root surface are only superficially placed, and capable of being removed by gentle means. Further research has attested to the difficulties in rendering periodontally-involved root surfaces free of calculus deposits by instrumentation, yet clinical studies show that periodontal disease can be managed by root planing. It is concluded that root surface debridement is best assessed on the basis of the healing response and that it should aim to disrupt plaque on and remove plaque from the periodontally-involved root surface rather than to remove part of the root surface itself.

Citric acid treatment of periodontitis-affected cementum. A scanning electron microscopic study

Previous studies have described an inconsistent histological occurrence of a zone of surface demineralization on periodontitis-affected cementum following treatment with citric acid, and a lack of connective tissue attachment to the latter surfaces. In view of these findings, the purpose of the present study was to use scanning electron microscopy to examine the surface morphology of cementum from normal and periodontitis-affected root surfaces following citric acid treatment for differences in the effects of the demineralizing solution on these surfaces. Cementum surfaces were derived from the roots of extracted human teeth from areas beneath attached periodontal ligament fibers (normal) and calculus deposits (periodontitis-affected). 5 specimens were evaluated in both groups. Periodontal ligament fibers were removed from normal root surfaces with a curette, and calculus deposits were removed from periodontitis-affected root surfaces using an ultrasonic scaler. The resultant 5 specimens in each group were then sectioned in half, one-half serving as the untreated control and the other as the experimental, citric acid treated specimen. Experimental specimens were immersed in a saturated solution of citric acid, pH 1 for 3 min and then rinsed in tap water. Both control and experimental specimens were dehydrated in ethanol, critical-point dried, sputter-coated with gold and examined in the scanning electron microscope for morphological characteristics. Citric acid treatment of cementum from normal root surfaces produced an undulating, markedly fibrillar surface morphology which is consistent with the exposure of a fibrillar, collagen substrate. Periodontitis-affected cementum, however, was not appreciably altered in appearance by the citric acid treatment, having only a faint mat-like surface texture. (ABSTRACT TRUNCATED AT 250 WORDS)

Bacterial invasion in root cementum and radicular dentin of periodontally diseased teeth in humans. A reservoir of periodontopathic bacteria

In this study the viability and the distribution of bacteria within the radicular dentin and pulp of periodontally diseased caries-free teeth were studied. Healthy teeth served as controls. Samples were obtained from the pulp tissue and from the radicular dentin. Dentin samples were taken from the interdental surfaces in the subgingival area. Starting from the pulpal side, three to five successive dentin layers of approximately 1 mm thickness were sampled. The samples were processed and cultured using an anaerobic technique. Bacterial growth was detected in 87% of the periodontally diseased teeth. In 83% of the teeth, bacteria were present in at least one of the dentin layers. Fifty-nine percent of the diseased teeth, from which the pulp tissue was cultured, contained bacteria in the pulp samples. The mean bacterial concentrations in the pulp and dentin layers ranged from 1,399 to 16,537 colony-forming units (CFU) per mg of tissue. These concentrations were 259 to 7,190 times greater than concentrations found in healthy teeth. It is suggested that the roots of periodontally diseased teeth could act as bacterial reservoirs from which recolonization of mechanically treated root surfaces can occur, as well as infection of the dental pulp. These findings might change current concepts concerning root surface debridement in periodontal therapy.

The concentration of lipopolysaccharide on individual root surfaces at varying times following in vivo root planing

Material with endotoxin activity has been detected in extracts prepared from pooled, periodontally involved teeth, and it has been shown that root planing in vivo reduces the level of such material. However, questions concerning the concentration of endotoxin on the diseased surfaces of individual teeth and questions concerning how rapidly individual root planed tooth surfaces retoxify in vivo have not been addressed previously. Citric acid extracts were prepared from individual, periodontally diseased teeth that had been extracted either from the oral cavity without prior root planing or at varying times up to 12 weeks following root planing. Using a chromogenic Limulus Amebocyte Lysate (LAL) assay, we were able to quantitate the amount of endotoxin associated with diseased root surfaces of individual teeth. We concluded that the extracted material contained endotoxin since it activated LAL and since the LAL-activation was heat-stable, acid-stable and neutralizeable by polymyxin B. The levels of endotoxin found on the root surfaces of these individual, periodontally involved teeth at varying times following in vivo root planing support the following conclusions: the concentration of endotoxin present on diseased root surfaces is markedly reduced, but not eliminated, by in vivo root planing, significant retoxification of root planed surfaces occurs within a relatively short time period after root planing and biological responses to such toxification conceivably may lead to subsequent phases having reduced levels of endotoxin.

The impact of research on scaling and root planing

The research expanding our knowledge of the periodontally involved root surface and its treatment is reviewed. To improve communication in the clinic and classroom, definitions are suggested for the terms "scaling" and "root planing." The objective and limitations of root planing procedures are discussed.

Inhibitory effect of periodontally diseased root extracts on the growth of human gingival fibroblasts

Cementum shavings obtained from periodontally diseased and nondiseased areas of 100 removed, single-rooted teeth were extracted with either pyrogen-free water (PFW) for 5 minutes, 1 M citric acid for 5 minutes or 45% phenol-PFW for 90 minutes at 65 degrees C. The extracts were membrane-filtered, dialyzed exhaustively versus PFW, lyophilized, weighed and then dissolved in complete growth medium. The phenol-water or citric acid extracts of cementum shavings from periodontally diseased roots were positive for endotoxin by the limulus lysate assay (LLA). Pyrogen-free water extracts of diseased or phenol-water extracts of nondiseased cementum shavings were negative, or only slightly positive, respectively, for endotoxin by LLA. Media containing the various extracts were added to logarithmically growing cultures of human gingival fibroblasts (HGF). Separate cultures of HGF were exposed to Escherichia coli endotoxin at concentrations of 50, 100, 250 and 500 micrograms/ml to determine the growth-inhibitory effects of a known endotoxin. Cell growth was analyzed by measuring the incorporation of tritiated thymidine into cells. Suppression of HGF growth from 30 to 49% by E. coli endotoxin was concentration-dependent and linear over the concentration range of endotoxin tested. Pyrogen-free water extracts of diseased (endotoxin negative) or phenol-water extracts of nondiseased cementum shavings (slightly endotoxin positive) did not effect HGF growth. However, citric acid or phenol-water extracts of diseased cementum shavings (highly endotoxin positive) significantly suppressed HGF growth 58% and 61%, respectively. These results indicate that citric acid is effective in removing cytotoxic substances, presumably endotoxin, from cementum shavings and suggest that citric acid treatment is effective clinically in detoxifying periodontally diseased root surfaces.