SARS-CoV-2 mitochondrial metabolic and epigenomic reprogramming in COVID-19

To determine the effects of SARS-CoV-2 infection on cellular metabolism, we conducted an exhaustive survey of the cellular metabolic pathways modulated by SARS-CoV-2 infection and confirmed their importance for SARS-CoV-2 propagation by cataloging the effects of specific pathway inhibitors. This revealed that SARS-CoV-2 strongly inhibits mitochondrial oxidative phosphorylation (OXPHOS) resulting in increased mitochondrial reactive oxygen species (mROS) production. The elevated mROS stabilizes HIF-1α which redirects carbon molecules from mitochondrial oxidation through glycolysis and the pentose phosphate pathway (PPP) to provide substrates for viral biogenesis. mROS also induces the release of mitochondrial DNA (mtDNA) which activates innate immunity. The restructuring of cellular energy metabolism is mediated in part by SARS-CoV-2 Orf8 and Orf10 whose expression restructures nuclear DNA (nDNA) and mtDNA OXPHOS gene expression. These viral proteins likely alter the epigenome, either by directly altering histone modifications or by modulating mitochondrial metabolite substrates of epigenome modification enzymes, potentially silencing OXPHOS gene expression and contributing to long-COVID.

SARS-COV-2 viroporins activate the NLRP3-inflammasome by the mitochondrial permeability transition pore

Background

Compared to healthy controls, severe COVID19 patients display increased levels of activated NLRP3-inflammasome (NLRP3-I) and interleukin (IL)-1β. SARS-CoV-2 encodes viroporin proteins E and Orf3a(2-E+2-3a) with homologs to SARS-CoV-1, 1-E+1-3a, which elevate NLRP3-I activation; by an unknown mechanism. Thus, we investigated how 2-E+2-3a activates the NLRP3-I to better understand the pathophysiology of severe COVID-19.

Methods

We generated a polycistronic expression-vector co-expressing 2-E+2-3a from a single transcript. To elucidate how 2-E+2-3a activates the NLRP3-I, we reconstituted the NLRP3-I in 293T cells and used THP1-derived macrophages to monitor the secretion of mature IL-1β. Mitochondrial physiology was assessed using fluorescent microscopy and plate reader assays, and the release of mitochondrial DNA (mtDNA) was detected from cytosolic-enriched fractions using Real-Time PCR.

Results

Expression of 2-E+2-3a in 293T cells increased cytosolic Ca++ and elevated mitochondrial Ca++, taken up through the MCUi11-sensitive mitochondrial calcium uniporter. Increased mitochondrial Ca++ stimulated NADH, mitochondrial reactive oxygen species (mROS) production and the release of mtDNA into the cytosol. Expression of 2-E+2-3a in NLRP3-I reconstituted 293T cells and THP1-derived macrophages displayed increased secretion of IL-1β. Increasing mitochondrial antioxidant defenses via treatment with MnTBAP or genetic expression of mCAT abolished 2-E+2-3a elevation of mROS, cytosolic mtDNA levels, and secretion of NLRP3-activated-IL-1β. The 2-E+2-3a-induced release of mtDNA and the secretion of NLRP3-activated-IL-1β were absent in cells lacking mtDNA and blocked in cells treated with the mitochondrial-permeability-pore(mtPTP)-specific inhibitor NIM811.

Conclusion

Our findings revealed that mROS activates the release of mitochondrial DNA via the NIM811-sensitive mitochondrial-permeability-pore(mtPTP), activating the inflammasome. Hence, interventions targeting mROS and the mtPTP may mitigate the severity of COVID-19 cytokine storms.

Stereoscopic navigation-controlled display of preoperative MRI and intraoperative 3D ultrasound in planning and guidance of neurosurgery: new technology for minimally invasive image-guided surgery approaches

OBJECTIVE

This paper demonstrates a method that brings together three essential technologies for surgery planning and guidance: neuronavigation systems, 3D visualization techniques and intraoperative 3D imaging technologies. We demonstrate the practical use of an in-house interactive stereoscopic visualization module that is integrated with a 3D ultrasound based neuronavigation system.

MATERIALS AND METHODS

A stereoscopy volume visualization module has been integrated with a 3D ultrasound based neuronavigation system, which also can read preoperative MR and CT data. The various stereoscopic display modalities, such as "cut plane visualization" and "interactive stereoscopic tool guidance" are controlled by a pointer, a surgical tool or an ultrasound probe. Interactive stereoscopy was tested in clinical feasibility case studies for planning and guidance of surgery procedures.

RESULTS

By orientating the stereoscopic projections in accordance to the position of the patient on the operating table, it is easier to interpret complex 3D anatomy and to directly take advantage of this 3D information for planning and surgical guidance. In the clinical case studies, we experienced that the probe-controlled cut plane visualization was promising during tumor resection. By combining 2D and 3D display, interpretation of both detailed and geometric information may be achieved simultaneously. The possibilities of interactively guiding tools in a stereoscopic scene seemed to be a promising functionality for use during vascular surgery, due to specific location of certain vessels.

CONCLUSION

Interactive stereoscopic visualization improves perception and enhances the ability to understand complex 3D anatomy. The practical benefit of 3D display is increased considerably when integrated with surgical navigation systems, since the orientation of the stereoscopic projection corresponds to the orientation of the patient on the operating table. Stereoscopic visualizations work well on MR and CT images, although volume rendering techniques are especially suitable for intraoperative 3D ultrasound image data.

Bayesian 2-D deconvolution: effect of using spatially invariant ultrasound point spread functions

Observed ultrasound images are degraded representations of the-true tissue reflectance. The specular reflections at boundaries between regions of different tissue types are blurred, and the diffuse scattering within homogenous regions causes speckle because of the oscillating nature of the transmitted pulse. To reduce both blur and speckle, we have developed algorithms for the restoration of simulated and real ultrasound images based on Markov random field models and Bayesian statistical methods. The algorithm is summarized here, although a more detailed description can be found in our companion paper [1]. Because the point spread function (psf) is unknown, we investigate the effects of using incorrect frequencies and sizes for the model psf during the restoration process. First, we degrade the images either with a known simulated psf or a measured psf. Then, we use different psf shapes during restoration to study the robustness of the method. We found that small variations in the parameters characterizing the psf, less than +/- 25% change in frequency, width, or length, still yielded satisfactory results. When altering the psf more than this, the restorations were not acceptable. The restorations were particularly sensitive to large increases in the restoring psf frequency. Thus, 2-D Bayesian restoration using a fixed psf may yield acceptable results as long as the true variant psfs have not varied too much during imaging.

Bayesian 2-D deconvolution: a model for diffuse ultrasound scattering

Observed medical ultrasound images are degraded representations of the true acoustic tissue reflectance. The degradation is due to blur and speckle and significantly reduces the diagnostic value of the images. To remove both blur and speckle, we have developed a new statistical model for diffuse scattering in 2-D ultrasound radio frequency images, incorporating both spatial smoothness constraints and a physical model for diffuse scattering. The modeling approach is Bayesian in nature, and we use Markov chain Monte Carlo methods to obtain the restorations. The results from restorations of some real and simulated radio frequency ultrasound images are presented and compared with results produced by Wiener filtering.

[From The Origin of Species to Artenes Oprindelse]

The Origin of Species, Charles Darwin's most important work, was published in London in 1859. The first presentation in Norway, by P. Chr. Asbjørnsen, appeared in the journal Budstikken. About 30 years passed before it was translated into Norwegian, and it took some time before Darwin's theories were debated in Norway. The zoologist Michael Sars introduced them in the Scientific Society in Christiania (i.e., Oslo) in 1869, but he was not met with a great deal of interest. However, a new generation of scientist saw this differently, mainly the botanist Axel Blytt, the zoologist G.O. Sars and the geologist W.C. Brøgger. Two prominent professors of medicine were also involved in the debate, on different sides. The Darwinist Gerhard Henrik Armauer Hansen, who discovered the lepra bacillus, wrote several books and articles about Darwinism, while Professor Ernst Ferdinand Lochmann, though admiring Darwin as a prominent naturalist, strongly rejected Darwinism as a scientific theory.

SonoWand, an ultrasound-based neuronavigation system

OBJECTIVE

We have integrated a neuronavigation system into an ultrasound scanner and developed a single-rack system that enables the surgeon to perform frameless and armless stereotactic neuronavigation using intraoperative three-dimensional ultrasound data as well as preoperative magnetic resonance or computed tomographic images. The purpose of this article is to describe our two-rack prototype and present the results of our work on image quality enhancement.

DESCRIPTION OF INSTRUMENTATION

The system consists of a high-end ultrasound scanner, a modest-cost computer, and an optical positioning/digitizer system. Special technical and clinical efforts have been made to achieve high image quality. A special interface between the ultrasound instrument and the navigation computer ensures rapid transfer of digital three-dimensional data with no loss of image quality.

OPERATIVE TECHNIQUE

The positioning system tracks the position and orientation of the patient, the ultrasound probe, the pointer, and various surgical instruments. This makes it possible to update the three-dimensional map during surgery and navigate by ultrasound data in a similar manner as with magnetic resonance data.

METHODS

The two-rack prototype has been used for clinical testing since November 1997 at the University Hospital in Trondheim.

EXPERIENCE AND RESULTS

The image quality improvements have enabled us, in most cases, to extract information from ultrasound with clinical value similar to that of preoperative magnetic resonance imaging. The overall clinical accuracy of the ultrasound-based navigation system is expected to be comparable to or better than that of a magnetic resonance imaging-based system.

CONCLUSION

The SonoWand system enables neuronavigation through direct use of intraoperative three-dimensional ultrasound. Further research will be necessary to explore the potential clinical value and the limitations of this technology.

Initial experience with stereoscopic visualization of three-dimensional ultrasound data in surgery

Initial in vivo and in vitro experiments were performed to evaluate the feasibility of stereoscopically displaying three-dimensional (3D) ultrasound data from neurosurgery, laparoscopic surgery, and vascular surgery. Stereoscopic visualization was illustrated by four video sequences, which can be downloaded from http://www.us.unimed. sintef.no/. These sequences show a brain tumor, hepatic arteries in relation to the gallbladder, a model that mimics a neuroendoscope in a cyst, and a "flight" into model of an artery with an intima flap. The experiments indicate that stereoscopic display of ultrasound data is feasible when there is sufficient contrast between the objects of interest and the surrounding tissue. True 3D vision improves perception, thus enhancing the ability to understand complex anatomic structures such as irregular lesions and tortuous vessels.

Coronally positioned flap procedures with or without a bioabsorbable membrane in the treatment of human gingival recession

BACKGROUND

A variety of surgical techniques have been used to cover recession type defects. New data have indicated that the outcome of coronally positioned flap procedures may be augmented by supporting the flap with a membrane.

METHODS

The present study aimed at comparing the clinical outcome following treatment of localized gingival recessions by a coronally positioned flap procedure alone, or combined with a bioabsorbable membrane. Twenty patients with buccal bilateral Miller Class I or Class II gingival recessions in cuspids or premolars participated in the study. The split-mouth design, randomized selection of site treatment, and blind evaluation provided 20 sites in a membrane group and 20 sites in a non-membrane group for examination at baseline, and at 3 months and 6 months postoperatively. Clinical variables included the apical extent of the gingival recession, the width of the recession defect measured at the cemento-enamel junction (CEJ), and the width of keratinized tissue at the recession site as well as probing depth and attachment level.

RESULTS

Both treatments resulted in a significant gain (P <0.0001) of root coverage, amounting to an average of 2.3 mm in the membrane group and 2.5 mm in the non-membrane group at the 6-month evaluation. There was no significant difference between the treatments. Similarly, a significant gain of clinical attachment level was seen in the membrane (1.3 mm; P <0.001) as well as in the non-membrane (1.5 mm; P <0.0001) group, but without a significant difference between the groups. The reduction of the recession width from baseline to 6 months was significantly greater (P <0.01) for the non-membrane (2.3 mm) than for the membrane (1.4 mm) group. Probing depth changes were small and not significant for either of the treatments. When patients were grouped as smokers (8) and non-smokers (12), no significant differences were revealed for any of the response variables. Overall, among the 20 membrane sites, one showed no change while the remaining 19 gained root coverage at the 6-month examination. Five sites obtained coverage to the CEJ. Among the non-membrane sites, all gained root coverage at 6 months and 10 sites showed complete coverage to the CEJ.

CONCLUSIONS

The coronally positioned flap operation offers a predictable, simple, and convenient approach as a root coverage procedure in Miller Class I and Class II recession defects. Combining this technique with the placement of a bioabsorbable membrane does not seem to improve the results following surgical treatment of such defects.

Effects of topical metronidazole and tetracycline in treatment of adult periodontitis

The present study was performed to assess and compare the clinical healing and the microbiological findings following local application of metronidazole or tetracycline to augment subgingival scaling in previously untreated adult periodontitis sites. Eighteen patients with moderate to severe adult periodontitis at single-rooted teeth were selected. In each patient, 3 interproximal sites having comparable root anatomy, probing depth > or =5 mm and bleeding on probing were randomly assigned to 1 of 3 treatment groups: 1) two sessions of subgingival scaling and root planing; 2) similar to 1, with each treatment supplemented with a 25% metronidazole sustained release gel; 3) similar to 1 with each treatment supplemented with a 3% tetracycline ointment. The treatments were performed by 1 operator and the clinical variables probing depth, attachment level, and bleeding on probing were evaluated at baseline, 3 months and 6 months by a second blinded examiner. The microbiological findings were evaluated using a commercial test kit. The average probing depth reduction for the 3 groups at 6 months was 1.5 mm and the average gain of clinical attachment was 0.8 mm. There were no significant differences between the effects following topical application of the metronidazole gel or the tetracycline ointment. Scaling and root planing alone appeared as effective as the drug augmented regimens, although there was a weak but non-significant tendency for better results in sites treated with the antibiotic drugs. Actinobacillus actinomycetemcomitans was generally not detected; Prevotella intermedia was not significantly reduced, while Porphyromonas gingivalis was significantly reduced in all treatment groups. It was concluded that the augmentative effect of the metronidazole gel and the tetracycline ointment was comparable but small compared to scaling and root planing alone. The clinical importance of such small augmentation effects should be further evaluated.

Ultrasound imaging during endovascular abdominal aortic aneurysm repair using the Stentor bifurcated endograft

PURPOSE

To evaluate different ultrasound modalities during implantation and follow-up of endovascular grafts for abdominal aortic aneurysm (AAA) exclusion.

METHODS

Between February 1995 and May 1996, 18 patients (14 men; aged 49 to 80 years, mean 67) were treated with endovascular intervention for infrarenal AAA. Seventeen patients received Mialhe Stentor bifurcated grafts, while one patient was treated with a straight graft for pseudoaneurysm. During and after the implantation, 3.25- and 5-MHz annular array ultrasound probes were used for transabdominal visualization of the endograft. Intravascular ultrasound was applied in combination with angiography for postoperative control.

RESULTS

Intraprocedurally, transabdominal two-dimensional (2D) ultrasound successfully monitored guidewire passage from the groin into the main part of the bifurcated endograft for implantation of the second limb. All implantation procedures were technically successful, but four endoleaks were identified intraprocedurally by 2D ultrasound and angiography. One healed spontaneously, two were treated with endovascular techniques at 1 and 4 months, and the last leak was scheduled for repair when the patient died of probable myocardial infarction at 2 months. During follow-up, 2D ultrasound successfully visualized all the endografts; no endoleaks were found in up to 18 months of surveillance.

CONCLUSIONS

Transabdominal ultrasound imaging could be valuable in bifurcated endograft deployment both for guiding guidewire insertion and for controlling wire position before the second graft limb is connected to the main graft. Provided that satisfactory visualization of the entire endograft can be obtained, ultrasound examination may possibly replace arteriography and computed tomographic scanning as a follow-up investigation.

A pilot study comparing ketoprofen and acetaminophen with hydrocodone for the relief of postoperative periodontal discomfort

The aim of this study was to compare ketoprofen to acetaminophen with hydrocodone (A/H) in a postoperative periodontal pain model. A double-blind protocol was used. Thirty minutes prior to each procedure, subjects were given orally either 100 mg ketoprofen or a placebo tablet. Four hours later, the subjects took either 50 mg ketoprofen (ketoprofen group) or 1000 mg acetaminophen with 10 mg hydrocodone (placebo group). Subjects reported levels of overall discomfort and pain using visual analog scales at eight hourly intervals following the first dose of ketoprofen or placebo. Information about adverse side effects was requested from the patients in the form of a checklist. The results revealed only small differences between the two drug regimens with respect to levels of pain or overall discomfort. A/H provided significantly better pain relief at Hours 5 and 6, while overall discomfort levels were significantly higher with ketoprofen than with placebo at Hours 3 and 4. Pain levels were low for both groups. It is recommended that additional analgesics for mild to moderate pain should be tested.

A correlation study of inflammatory cell mobilization in response to subgingival microbial colonization

This study evaluated site-by-site the relations between subgingival microbial colonization and gingival tissue reactions. Experimental, deep periodontal defects were established at buccal surfaces of mandibular and maxillary canine teeth in 5 beagle dogs. The root surfaces were instrumented by a flame-shaped, fine-grained, rotating diamond point, or by a sharp curet. Following a 10-day postsurgical healing period, the dogs were fed a plaque-inducing diet for 70 days. The animals were then sacrificed and tissue blocks of the experimental sites including teeth and periodontal tissues were secured. The buccal gingiva was removed and processed for histomorphometric analysis while the teeth were prepared for scanning electron microscopic evaluation of the extent of subgingival microbial colonization. The results revealed that inflammatory cell density in the junctional epithelium and in the connective tissue were positively correlated to subgingival microbial colonization (P < 0.01). Furthermore, the degree of significance decreased with increasing distance from the plaque. The present study demonstrates that a close relation may exist between the extent of subgingival microbial colonization and inflammatory gingival tissue reactions.

Cemental tear: a risk factor in periodontal attachment loss

The objective of this retrospective study was to evaluate the influence of cemental tear as a risk factor in periodontal attachment loss. Seventeen extracted, single-rooted teeth showing loss of attachment and having one cemental tear surface and one opposite intact surface were examined. The teeth were stained in 0.1% toluidine blue to visualize attached periodontal ligament remnants and examined in a light microscope under incident light. On each tooth, loss of attachment was measured along the long axis of the root from the cemento-enamel junction to the most coronal level of the periodontal ligament on intact as well as on defect surfaces. Cemental tear surfaces demonstrated a significantly greater loss of attachment than opposite intact surfaces (P < 0.0001). In one specimen, the cemental tear fragment was partially attached to the root after the extraction procedure. This specimen was processed for light microscopy to determine the location of the cemental tear fracture. Histological examination clearly revealed that the split between the root and the fragment had occurred along the cemento-dentinal border. The results indicate that cemental tear should be considered as a possible etiologic entity in localized rapid periodontal breakdown.

Influence of tooth instrumentation roughness on gingival tissue reactions

Histological studies have demonstrated a relationship between the amount of subgingival plaque and the magnitude and extension of gingival tissue reactions. The objective of the present study was to evaluate inflammatory reactions in the gingival tissues facing plaque accumulation at a diamond and curet-instrumented root surfaces. Experimental, deep periodontal defects were established at buccal surfaces of mandibular and maxillary canine teeth in 5 beagle dogs. The root surfaces were instrumented by a flame-shaped, fine-grained. rotating diamond point, or by a sharp curet. Next, the dogs were fed a plaque-inducing diet for 70 days. The animals were then sacrificed, and tissue blocks of the experimental sites including teeth, alveolar bone, and gingival tissues were secured. The gingival soft tissue was processed for histomorphometric analyses at 3 levels. Epithelium and connective tissue area measurements showed no differences between the two instrumentations. Junctional epithelium (JE) cell point counts exhibited a higher proportion of inflammatory cells (IC)in specimens facing diamond compared to curet-instrumented defects. A higher proportion of IC was present within the coronal compared to the apical aspect of the JE for both instrumentations (P < 0.05). A significant difference in IC density between instrumentations was detected for non-infiltrated (P < 0.05), as well as for infiltrated (P < 0.01) connective tissue. The infiltrated connective tissue (ICT) inflammatory cell density was significantly (P < 0.01) and positively correlated to the JE inflammatory cell density (r = 0.75), and to area measurements of ICT (r = 0.55). The overall results demonstrate that the character of subgingival root instrumentations significantly affects gingival inflammatory reactions, most likely by influencing subgingival plaque formation.

Root grooves: a risk factor in periodontal attachment loss

Periodontal health reflects a balance between harmful and protective elements in the gingival margin area. The total plaque mass, specific periodontopathogens, and local environmental factors may challenge this balance. The aim of this retrospective study was to evaluate the effect of proximal root grooves as a risk factor in periodontal attachment loss. One-hundred and three (103) extracted, formalin-stored, single-rooted teeth showing loss of attachment and having one non-grooved and one grooved proximal root surface were selected for the study. Following staining in 0.1% toluidine blue to visualize attached periodontal ligament remnants, the teeth were examined in a light microscope under incident light. On each tooth, loss of attachment was measured along the long axis of the root from the cemento-enamel junction to the most coronal level of the stained periodontal ligament remnants on mesial as well as on distal surfaces. Incisors and premolars were grouped separately. For both groups, a statistically significant greater loss of attachment was present on grooved than on non-grooved surfaces (P < 0.0001). Generally, there was a direct relationship between groove location and maximum loss of attachment. The results indicate that proximal root grooves should be considered in periodontal diagnosis, prognosis, and treatment planning.

Influence of tooth instrumentation roughness on subgingival microbial colonization

This study evaluated microbial colonization of periodontal pockets subjected to root instrumentation with a curet or a rotating diamond. Ten maxillary and 10 mandibular subgingival pockets were established in the canines of 5 beagle dogs. The subgingival root surface areas were debrided by a sharp curet or a flame-shaped, fine-grained, rotating diamond point. The dogs were fed a plaque-inducing diet for 70 days. Specimens from both instrumentation groups were then harvested and prepared for stereomicroscopic and scanning electron microscopic evaluation. Grading of the extent of subgingival colonization was performed in coded specimens directly on the fluorescent screen of the scanning electron microscope in a grid-counting system. Error of the method was assessed by duplicate counts. The subgingival root surface areas were divided into 3 zones: cervical, middle, and apical, and statistical differences between these zones as well as between the 2 instrumentation groups were calculated. The results revealed that curet-treated surfaces were smoother and promoted less subgingival colonization than diamond-treated surfaces. The difference in amount of bacterial colonization between the 2 groups was statistically significant (P < 0.05) in all zones. Bacterial colonization decreased in apical direction in both instrumentation groups. For the diamond-treated specimens, this decrease was significant (P < 0.05) between each of the 3 zones. In the curet-treated specimens, the decrease was significant only between the cervical and the apical zone (P < 0.05). The present study has demonstrated that subgingival instrumentation roughness significantly influences the subgingival microbial colonization.

Pain and discomfort levels in patients during root surface debridement with sonic metal or plastic inserts

The study was designed to evaluate whether root surface debridement with a sonic scaler plastic insert would cause less pain and discomfort to patients than an ordinary, probe-shaped metal sonic insert. One quadrant in each of 23 patients was debrided with each insert. Blood pressure, mean arterial pressure, and heart rate were monitored before, during, and immediately after each treatment. Pain was also evaluated on a visual analogue scale (VAS) after each treatment, as well as 2 weeks later following pain-provoking stimuli. Blood pressure, mean arterial pressure, and heart rate did not reveal any differences between quadrants treated with plastic or metal inserts. Heart rate had a weak, positive association with treatment time. The VAS gave a higher pain score for the plastic (30.8) than for the metal insert (24.4), but this difference was not statistically significant (P = 0.055). Following pain-provoking stimuli at the 2-week follow-up visit, quadrants debrided with the metal insert (31.3) scored significantly lower (less pain) (P < 0.01) on the VAS than quadrants treated with the plastic insert (30.7). It is concluded that the sonic metal insert caused less pain and discomfort to the patients due to its superior accessibility and water spray cooling. The significant difference between metal and plastic tip debrided quadrants at the follow-up visit was probably caused by the smearing effect of the metal insert with partial closure of the dentin tubule orifices.

Hypersensitive dentin: testing of procedures for mechanical and chemical obliteration of dentinal tubuli

This study examined by scanning electron microscopy the effect of various mechanical and chemical procedures in obliterating dentinal tubuli. Dentin blocks containing open, cross-sectioned dentinal tubuli were separated into one experimental and one control area. The mechanical treatments consisted of 20 seconds of continuous instrumentation with sharp and dull curets, finely textured inserts for the EVA reciprocating handpiece, metal and plastic inserts for a sonic scaler, and metal inserts for an ultrasonic scaler. Chemical treatments included a light-cured dental resin and active obliterating agents including sodium, stannous and hydrogen fluorides, potassium oxalate, glycerin, ferric oxalate, and potassium nitrate. These substances were applied to the test surfaces for 2 minutes and allowed to dry. One half of the chemically treated specimens were then sprayed with water in order to evaluate the retention of the obliterating agents. The results revealed that among the mechanical treatments, the sharp curet gave the most consistent and complete obliteration of the tubuli. The plastic inserts had no tubular occluding effects. Among the chemical procedures, the light-cured resin resulted in the most complete obliteration of the tubuli, while the fluoride agents and glycerin had no effect. It can be hypothesized that combining instrumentation with a sharp curet causing a heavy smear layer and occlusion of tubuli apertures, followed by application of a light body resin, may prove to be a rational method of desensitizing hypersensitive dentin surfaces. However, this combined treatment should be evaluated in clinical trials.

Efficacy of 5 machining instruments in scaling of molar furcations

The scaling efficacy of machining instruments was studied in the furcations of 100 extracted molars. The molars were divided into 5 groups with similar furcation anatomy, painted with artificial calculus, partly submerged in stone blocks, and the furcation entrances covered with a heavy rubber dam material. Ten mandibular and 10 maxillary molars were scaled by an experienced operator with each of the following instruments/inserts: ultrasonic instrument with either a prototype ball point insert or with a new pointed insert; ultrasonic instrument with a ball point insert; reciprocating hand-piece with new inserts for furcations; and a sonic scaler with a universal insert. The molar groups were coded and graded in a stereomicroscope by 2 independent examiners, and the rankings were tested with the Kruskal-Wallis test and the multiple comparisons between treatments test. The results revealed statistically significant differences between the instruments, as well as between different topographical areas of the furcations. The sonic scaler with a universal insert and the ultrasonic instrument with ball point inserts were significantly more efficient (P < 0.05) than the reciprocating handpiece with inserts in most of the areas studied. For mandibular molars, significantly better results (P < 0.05) were obtained for lingual furcation entrances than for furcation roofs. For maxillary molars, significantly better results (P < 0.05) were obtained for distal and buccal entrance areas than for furcation roofs and inside of mesial roots. The present study may give some guidance to the practitioner in choosing machining instruments for furcation cleaning as well as identifying the most difficult topographical areas to instrument.

Clinical responses to subgingival application of a metronidazole 25% gel compared to the effect of subgingival scaling in adult periodontitis

A newly developed metronidazole 25% dental gel was compared with subgingival scaling in the treatment of adult periodontitis. 206 patients in 9 centres participated in the study. Probing pocket depth (PPD) and bleeding on probing (BOP) were recorded before treatment and 2, 6, 12, 18, and 24 weeks after the treatment. All patients had at least 1 tooth in each quadrant with a PPD of 5 mm or more. The treatments consisted of 2 applications of dental gel (days 0 and 7) in 2 randomly selected quadrants (split mouth design) and 2 sessions of subgingival scaling (1 quadrant on day 0, and 1 quadrant on day 7). Instruction in oral hygiene was given 2 weeks after completed treatment. The average PPD and the average frequency of BOP were calculated over all sites with initial PPD of 5 mm or more. PPD and BOP were thus, at each examination, calculated from the same sites. The mean PPD was 5.9 mm before gel application and 5.8 mm before scaling (p = 0.31). BOP was 88% in both treatment groups. 24 weeks after the treatment, PPD and BOP were significantly reduced in both groups and for both parameters (p < 0.01). PPD was reduced by 1.3 mm after gel application and 1.5 mm after scaling; BOP was reduced by 32% and 39%, respectively. The difference between the treatments was statistically significantly, but considered as clinically unimportant.

Comparative in vitro studies of sonic, ultrasonic and reciprocating scaling instruments

Flat root surface areas of formalin-stored mandibular incisors with plaque and calculus were scaled by sonic (PHATELUS SONIC SCALER, SONIC FLEX 2000, TITAN-S SONIC SCALER) or ultrasonic instruments (HYGIENIST ULTRASONIC SCALER, CAVITRON) or by a new reciprocating scaling insert for the EVA/PROFIN system. The test areas were photographed by SEM and coded micrographs were independently graded by three examiners using the RCI (Remaining Calculus Index) and the RLTSI (Roughness Loss of Tooth Substance Index). The findings revealed that the sonic scalers as a group removed calculus more completely but also left significantly more roughness and loss of tooth substance than the other instruments tested. No difference was seen between the two ultrasonic scalers. The reciprocating insert gave results similar to those of the ultrasonic except for the scaling time which was significantly longer for the new "cleansing principle".

Early effects of periodontal therapy on the detection frequency of four putative periodontal pathogens in adults

This study aimed to examine early posttreatment changes in the periodontal microflora. Paper point sampling and conventional bacterial cultivation were used to monitor the effects of surgical and non-surgical periodontal therapy on the detection frequency of Porphyromonas gingivalis, Prevotella intermedia, Actinobacillus actinomycetemcomitans, and Capnocytophaga species in deep periodontal pockets. Ten patients, 5 men and 5 women (mean age 44 years), with advanced periodontal disease were selected from the dental school patient population for the study. A total of 245 teeth in 10 defined areas of the dentition were treated by oral hygiene instruction followed by scaling and root planing alone (121 sites) or with surgical interventions (124 sites). Ninety sites, 47 surgical and 43 non-surgical, with initial pocket depth greater than or equal to 6 mm were sampled at baseline and 3 months after completion of therapy. Treatment by both procedures resulted in significant clinical improvements as assessed by all clinical parameters used. Baseline results may indicate that the level of P. gingivalis was reduced in the presence of P. intermedia, while A. actinomycetemcomitans seemed to be reduced in the presence of P. gingivalis and/or P. intermedia. Three months after therapy, the detection frequency of P. gingivalis was significantly reduced (P less than 0.05) in surgical and non-surgical sites while the reduction for P. intermedia was significant only for surgical sites (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Relative production of IL-1 beta and TNF alpha by mononuclear cells after exposure to dental implants

Interleukin-1 (also known as osteoclast activating factor, OAF) is a cytokine produced primarily by monocytes and macrophages and is thought to mediate many of the immunologic, metabolic, and endocrine alterations seen with microbial infection, tissue injury, inflammatory disease, and bone loss. Stimuli for IL-1 production include microorganisms, endotoxins (LPS), antigen-antibody complexes, clotting components, and other cytokines. The purpose of this study was to determine whether dental implants stimulated peripheral blood mononuclear cells (PBMCs) to produce IL-1 beta (OAF) as well as tumor necrosis factor (TNF alpha). This production may lead to bone loss or failure of an implant. Three duplicates of five different implants were incubated with 2 x 10(6) PBMCs/ml in 20% autologous serum; the esterase positive PBMCs amounted to 14.5%. Measured by radioimmunoassay techniques and compared to controls, all of the implants except one caused significant in vitro generation of IL-1 beta and TNF alpha. The stimulation of IL-1 beta/TNF alpha production by these materials suggests that they are not physiologically inert and that the IL-1 beta (OAF) production may contribute to a less favorable osseoadaptation. OAF has a physiologic (homeostatic) role in maintenance and alteration of osseous structures, but the level at which physiologic becomes pathologic is unknown. Although there were statistical differences between the cellular response to these implants, the clinical significance of the differences remains to be determined.

Root dentin morphology after different modes of citric acid and tetracycline hydrochloride conditioning

The purpose of this study was to assess the effect of citric acid and tetracycline HCl application to dentin surfaces by a "passive dripping" or an "active burnishing" technique. Twenty dentin blocks were prepared from freshly extracted non-diseased human impacted third molars. The blocks were root planed and randomly assigned to two groups for treatment with either citric acid or tetracycline HCl. The duration of treatment was 30, 60, 120, or 240 seconds. Control blocks were treated with distilled water. After treatment the blocks were processed for observation and measurements in the scanning electron microscope (SEM). Application of either of the acid solutions resulted in removal of the smear layer. Measurements indicated a time dependent increase in the mean dentinal tubule orifice diameter ranging from 1.05 microns in control specimens to 3.18 microns after 4 minutes treatment (citric acid group). The increase in tubule diameter was significantly greater (P less than or equal to 0.01) for both citric acid treatment modalities than tetracycline HCl treatment. There was also a time dependent increase in the depth of penetration as measured by a trumpeting of the tubule profiles, and this penetration was significantly greater (P less than or equal to 0.01) after citric acid treatments. Passive or active application of the acids did not seem to have any major impact on the measurements or on the surface morphology. It was concluded that citric acid causes more extensive changes than tetracycline HCl and that the mode of application of the agent is probably not critical.

Cemental tear related to rapid periodontal breakdown: a case report

Cemental tears have been described both in exposed and unexposed cementum. The phenomenon is believed to be elicited by overloading or acute trauma from occlusion. In this case report a patient, with a history of periodontal health, presented with an acute periodontal lesion on the distal aspect of a bridge abutment tooth. Periapical radiographs demonstrated an extensive vertical intrabony defect adjacent to the vital abutment tooth containing a radiopaque "foreign body." Histological examination of the surgically removed "foreign body" revealed a piece of dental cementum with some attached soft tissue. The lesion responded well to a surgical approach. Healing was uneventful and periodontal health was restored. This case illustrates that cemental tear should be considered as a differential diagnostic entity in isolated sites with rapid periodontal breakdown.

The effect of hygiene instruments on dentin surfaces: scanning electron microscopic observations

The present study consists of two separate parts. The first section is an in vitro evaluation of the relative abrasiveness of some hygiene instrumentations commonly used during maintenance therapy. In the second section, one of the instruments, a recently developed plastic tip for use on a sonic scaler, was examined for its ability to remove dental plaque from root surface specimens instead for 5 weeks in the oral cavities of dogs. The in vitro study was performed on recently obtained dentin specimens where a ridge had been machined parallel to the long axis of the tooth. The sonic scaler fitted with the plastic tip gave considerably less removal of dentin and a smoother dentin surface than the curet, the rubber cup with polishing paste, or the sonic scaler with an ordinary metal tip. These findings further demonstrated that the plastic tip was able to efficiently remove 5-week old dental plaque from experimental root surface areas within a time frame of 5 seconds. The new plastic tip may be valuable in maintenance therapy giving less risks for iatrogenic effects on the root surfaces than other debridement methods.

Influence of polishing procedures on sonic scaling root surface roughness

The present in vitro study aimed to evaluate the efficacy of various polishing procedures in reducing root roughness caused by sonic scaling. Proximal root surface areas of extracted, formalin-stored teeth were scaled in a bucco-lingual direction by a sonic scaler. The resulting roughness was measured along the direction of scaling and perpendicular to that direction by a profilometer. The specimens were then split into two groups. Group 1 was polished by an air-powder polishing instrument followed by a rotating rubber cup and chalk; Group 2 was polished by pumice followed by chalk. Root roughness (Ra) was recorded for each step in the procedures. The measurements revealed lower Ra values when the stylus of the profilometer was running perpendicular to the scaling direction, and a weak negative correlation was found when scaling time and Ra values were compared. In both groups Ra values were significantly reduced at each step of the polishing procedures and the terminal result was similar for the groups. Pumice and air-powder polishing gave a similar reduction of the sonic scaling roughness.

Periodontal awareness, health, and treatment need in dental school patients. III. Treatment need

The need for periodontal treatment in a group of dental school patients was estimated by means of the periodontal treatment need system (PTNS). The findings were related to information about the regularity of dental visits, awareness of own disease, and periodontal treatment experience. All the patients required motivation and oral hygiene instruction (treatment need, class A). All their quadrants needed scaling or adjustment of subgingival restorations (treatment need, class B). As many as 71% of the patients and about 49% of the quadrants needed periodontal surgery (treatment need, class C). The mean periodontal treatment time per patient was 279 min (4 h 39 min). The middle age group (30-59 years) required more treatment time than the oldest group (greater than or equal to 60 years). This was probably due to more missing teeth in the oldest age group. There were no significant differences in treatment need between males and females. The regular dental visitors had a greater periodontal treatment need than the individuals visiting their dentist less frequently. This finding emphasizes the responsibility of the general practitioner in diagnosing and treating periodontal disease.

The prevalence of hepatitis A and B in Norwegian merchant seamen--a serological study

The prevalence of viral hepatitis in Norwegian merchant seamen in overseas trade was studied in 523 volunteers during compulsory health control before embarkation from the port of Oslo. The prevalence of hepatitis B markers was 9.4%, which is significantly higher than in the general Norwegian population. The prevalence increased with the number of years of occupation. It was associated with frequent casual sexual contacts in foreign countries, but not significantly increased in participants who had been exposed to tattooing or different types of medical treatment under poor hygienic conditions in foreign areas. The prevalence of antibodies against hepatitis A (HAV) was 36% in seamen born in 1945 or earlier and 5% in younger individuals, an age-dependent pattern which is essentially similar in the general Norwegian population. However, the prevalence of hepatitis A antibodies seemed to increase with years in foreign trade. The incidence of viral hepatitis infections in the occupation was noticeably high, suggesting that vaccination of seamen in certain areas of trade should be considered.

Periodontal awareness, health, and treatment need in dental school patients. II. Periodontal conditions

The present study aimed to evaluate the periodontal conditions in a group of randomly selected patients scheduled for periodontal treatment in a dental school. The patients' age, sex, and responses to interview questions were used as predictors. About 64% of the lateral tooth surfaces had visible plaque after disclosure with erythrosine, and males had significantly more plaque-covered surfaces than females. All subjects had some areas showing 'bleeding on probing', and a total of 58% of the gingival units bled. About 99% of the subjects, 61% of the teeth, and 33% of the gingival sites had probing depths greater than or equal to 4 mm, whereas 70% of the subjects, 19% of the teeth, and 8% of the gingival sites had probing depths greater than or equal to 6 mm. Mean individual bone score for the 'Ramfjord teeth' was 5.60. Yearly dental visitors tended to keep their teeth to a greater extent than patients with a less regular treatment pattern. This is probably because irregular and emergency patients more often ask for extraction instead of restorative treatment. Since periodontal treatment usually is not offered, the periodontal conditions in the three regularity groups were not considerably different.

Periodontal health in a group of industrial employees

The aim of this study was to evaluate the dental health conditions of male employees in a large aluminum factory. The present report deals only with the periodontal findings. Five percent of the 181 examined subjects between 25 and 60 yr were edentulous, and all dentate individuals had some degree of periodontal disease. Surfaces harboring stainable plaque were high in all age groups, varying between 65 and 85%. Surfaces without retention factors were 31% and decreased with increasing age. The percentage of sites with bleeding increased from about 40% in the lowest to about 60% in the highest age group. Teeth with probing depths greater than or equal to 4 mm increased from about 30% in the age group 25-29 yr to about 45% in the age group 30-34 yr, after which it increased gradually with increasing age. The difference in bone scores (marginal bone loss) was the most extensive between the ages of 25 and 34 yr, but with a significant increase throughout the age groups. The administrators had a somewhat better oral hygiene, fewer retention factors, less bleeding, fewer pockets and some more marginal bone support than the workers. Still, the administrators had more missing teeth than the workers.

Periodontal awareness, health, and treatment need in dental school patients. I. Patient interviews

The present study aimed to evaluate the periodontal awareness and the amount of information and periodontal treatment received previously in a group of randomly selected patients scheduled for periodontal treatment in a dental school. A group of 124 patients were interviewed by a dental hygienist before the treatment started. Age, sex, and regularity of dental visits were used as predictors. Around 68% of the patients were not aware of the existing periodontal disease, and 74% had never received any information about the treatment possibilities. Ninety per cent claimed that they had never received any periodontal treatment at all. The modality of periodontal treatment and the extent to which the patients had been instructed in toothbrushing were almost equal in patients who visited the dentist yearly and in emergency patients.

Abrasivity of toothpastes. An in vitro study of toothpastes marketed in Norway

The purpose of this study was to measure the abrasivity of 23 toothpastes available on the Norwegian market. Additionally, the pH was registered. The testing was based on The British Standards Institution's specification for toothpastes, using a profilometer technique to evaluate the abrasion. The results showed that the abrasivity ranged from 0.049 to 1.367 relative to a standard reference paste. The products were classified as having 'none/slight', 'medium', or 'high' abrasivity. The pH varied between 3.7 and 10.1. Products with low pH showed evidence of a combined erosive/abrasive effect. For some brands there were statistically significant differences between the fluoride and the nonfluoride version.

Computerized evaluation of the effectiveness of subgingival scaling in jaw models. An introduction to the program developed at the School of Dentistry, University of Bergen

The purpose of the present study was to improve the quality and the effectiveness of subgingival scaling managed by dental students. A training program was developed and the scaling was performed in jaw models. The teeth of these models were modified in order to ensure a quick inspection of the scaled root surfaces. Artificial "calculus", consisting of a mixture of shellac, umbra, pumice and plaster dissolved in ethanol, was painted on the root surfaces. Following the completion of the scaling test, remaining "calculus" was evaluated by adoption of a grading system. This system had scores from 0 to 3 and was defined by illustrated and described criteria. A menu-directed computer program was developed in order to ensure a rapid transformation of surface scores into clinically-related variables. The output from this program gave valuable information about the proficiency of individual students, as well as about the whole class of students as one body. Other advantages and potentials of this system are described.

Effects of chlorhexidine gel in a group of maintenance-care patients with poor oral hygiene

An intraindividual double-blind crossover study was designed in order to see if a 1% chlorhexidine gel used twice a day could substitute for ordinary toothpaste in group of maintenance-care patients with poor oral hygiene. Twenty patients from a student clinic participated, each with a long history of maintenance-care problems. A 4-week test period with chlorhexidine gel or placebo gel was followed by an intermediate period with ordinary toothpaste, and then by another 4-week test period. Plaque-covered surfaces (%), bleeding sites (%) and extraneous staining (color slides) were recorded at each sitting. The results demonstrated that brushing with chlorhexidine gel significantly influenced both the oral hygiene level and the gingival inflammation. The only adverse effect observed was a marked increase in the amount of brown staining, especially on the facial surfaces of the nonsmokers. In this short-term study, the staining was not considered cosmetically unacceptable by the patients. The total amount of staining was always greater in smokers than in nonsmokers.

Evaluation of the effect on root surfaces of air turbine scalers and ultrasonic instrumentation

Three air turbine scalers were compared to each other and to an ultrasonic instrument (CAVITRON) on medium and maximum power setting. The amount of remaining calculus, roughness and loss of tooth substance were estimated by means of well-defined index systems (RCI and RLTSI). The time required to clean the test surfaces--marked on proximal root surfaces of mandibular incisors--was also noted. Standardized scanning electron microscope (SEM) micrographs were independently "blind-scored" by three examiners, and total mean scores were calculated. The results revealed significant differences (P less than 0.001) between the instruments with respect to the amount of remaining calculus. There were also significant differences (P less than 0.05) between roughness and loss of tooth substance produced by CAVITRON at maximum power setting and that produced by the other instruments. No differences were found with regard to the time required to clean the test surface (until visually clean).

Surface coatings on dental cementum incident to periodontal disease. (II). Scanning electron microscopic confirmation of a mineralized cuticle

Root surfaces, exposed by periodontal disease, were studied after treatment with sodium hypochlorite. Observations of the anorganic specimens demonstrated that substantial changes occur in root surfaces incident to periodontal disease. A mineralized surface coating was seen in all areas of the involved root surface, although local regions occurred where the coating was apparently unmineralized. These findings generally confirmed the results of a previous study where the same specimens were studied without hypochlorite treatment. It is concluded that the coating is probably identical to the dental cuticle, and stems from adsorption of components of the gingival inflammatory exudate to the root surface. The coating may also be the carrier matrix for exogenous cytotoxic substances, previously thought to be located in the cementum. The findings may have implications for the way of treating periodontitis-involved root surfaces.

Surface coatings on dental cementum incident to periodontal disease. I. A scanning electron microscopic study

Root surfaces of extracted human teeth with advanced periodontal disease were studied by the apically migrated junctional epithelium, the topography characteristic of uninvolved cementum was frequently masked by a surface coating. The thickness of the coating increased in a coronal direction where it often blended with calculus. The observations indicate that this surface coating may originate from the inflammatory exudate and corresponds to the dental cuticle. The findings also indicate that the coating may be mineralized and may contain exogenous substances. These observations illustrate a need for further study and reexamination of the rationale for removal of tooth substance during scaling and root planing.

Replica study of plaque formation on human tooth surfaces

Plaque formation on buccal tooth surfaces was studied by replica technique, consisting of impressions using low viscosity silicone impression materials and positive models produced in epoxy resins. Bacterial accumulation occurred near the cemento-enamel junction in 6-hr specimens, and subsequently expanded in a coronal direction. This development took place partly by extensions of single layers of bacteria, and partly by a pattern where the colonization was mostly restricted to vertical enamel cracks. Plaque accumulations were also frequently located in abrasion grooves and surface pits in the enamel, and prolific plaque areas were consistently surrounded by a monolayer of bacterial cells. Globular and hemispheric structures which occurred, especially on root surfaces immediately after cleaning, were probably artefacts caused by air bubbles or remaining moisture. In separate series of experiments it was demonstrated that improved reproduction of details from the plaque could be achieved by repeating the replicating procedure. The findings indicate that plaque formation starts by adsorption and proliferation of individual bacteria on tooth surfaces, and not by adsorption of aggregates of cells. Special attention should be directed against the problem of artefacts and moisture in replica studies of dental plaque.

Morphologic studies on dental plaque formation

The present summary and the following papers (I--VII) are submitted in partial fulfillment of the requirements for the degree of Doctor Odontologiae at the University of Bergen. 1: Growth of dental plaque on hydroxyapatite splints. A method of studying early plaque morphology. J. Periodontal Res. 1974, 9, 135--146. II: Pellicle formation on hydroxyapatite splints attached to the human dentition: Morphologic confirmation of the concept of adsorption. Arch. Oral Biol. 1975, 20, 739-742. III: Scanning and transmission electron microscope study of pellicle morphogenesis. Scand. J. Dent. Res. 1977, 85, 217-231. IV: Early dental plaque morphogenesis. A scanning electron microscope study using the hydorxyapatite splint model and a low-sucrose diet. J. Periodontal Res. 1977, 12, 73-89. V: Ultrastructural study of early dental plaque formation. J. Periodontal Res. 1978, 13, 391-409. VI: Dental plaque morphology as revealed by direct observation and by replicating techniques. Acta Odontol. Scand. 1978, 36, 279-288 Co-author: F. Gusberti. VII: Replica study of plaque formation on human tooth surfaces. Acta Odontol. Scand. 1979, 37, 65-72. Co-author: F. Gusberti. These papers are referred to as I-VII in the present summary. Other papers are referred to in conventional manner.