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PubMed1989

Stereomicroscopic evaluation of canal shape following hand, sonic, and ultrasonic instrumentation.

This study evaluated the root canal shape after using sonic, ultrasonic, and hand instrumentation on the mesial canals of extracted human mandibular first and second molars. One-hundred and five mesial roots were randomly divided into six experimental groups and one untreated control group of 15 roots each. The following instrumentation techniques were evaluated in the experimental groups: hand instrumentation with K-Flex files, sonic instrumentation with the Endostar 5, sonic instrumentation with the Sonic Air MM 3000, and ultrasonic instrumentation with the Cavi-Endo unit. Each technique was directly compared with each other. The mesial roots were instrumented alternating the techniques between the buccal and lingual canals in each group so that a direct comparison could be made. All canals were instrumented to a size corresponding to a #30 K-Flex file 1 mm from the anatomical apex. The roots were then sectioned perpendicular to the long axis so the apical and middle thirds could be evaluated with the stereomicroscope for canal shape. The control group was sectioned and examined without instrumentation. A significantly more regular shape was obtained at both levels with hand instrumentation than was obtained with either sonic or ultrasonic techniques. The comparisons between the sonic and ultrasonic techniques showed significantly better shapes were obtained with the Sonic Air MM 3000 instrument.

Dental Pulp Cavity↗
PubMed1997

The role of sonic hedgehog in vertebrate development.

Members of the hedgehog family are important signalling molecules during embryonic development. One member, Sonic hedgehog, is expressed in embryonic structures such as the zone of polarizing activity in the posterior limb bud, the notochord, and the floor plate of the neural tube, where it plays a role in patterning of the embryo. Sonic hedgehog is synthesized as an inactive precursor which must be proteolytically cleaved and modified by the addition of a cholesterol moiety to become active as a signalling molecule. In this processing, the C-terminal region of Sonic hedgehog serves as both the endoprotease and a cholesterol transferase. The importance of cholesterol for Sonic hedgehog function may explain many of the profound developmental defects caused by perturbations of cholesterol metabolism. The receptor for Sonic hedgehog is Patched, a multi-pass transmembrane protein which forms a complex with Smoothened Mutations in Patched are associated with basal cell naevus syndrome, while mutations in Sonic hedgehog cause holoprosencephaly. Downstream targets of Sonic hedgehog signalling are transcription factors like Gli3, responsible for Greigs polycephalosyndactyly in humans and Hoxd13, responsible for polysyndactyly.

Animals↗
PubMed1998

Comparison of sarcoplasmic reticulum capabilities in toadfish (Opsanus tau) sonic muscle and rat fast twitch muscle.

The sonic muscle of the oyster toadfish, Opsanus tau, can produce unfused contractions at 300 Hz. Electron microscopy shows a great abundance of the Sarcoplasmic reticulum (SR) in this muscle, but no functional characterization of the capabilities of the SR has been reported. We measured the oxalate-supported Ca2+ uptake rate and capacities of homogenates of toadfish sonic muscle and rat extensor digitorum longus (EDL) muscle, and estimated the number of pump units by titration with thapsigargin, a high-affinity, specific inhibitor of the SR Ca-ATPase. The Ca2+ uptake rate averaged 70.9 +/- 9.5 mumol min -1 per g tissue for the toad fish sonic muscle, and 73.5 +/- 3.7 mumol min -1 g-1 for rat EDL. The capacity for Ca2+ -oxalate uptake was 161 +/- 20 mumol g -1 and 33 +/- 2 mumol g -1 for toadfish sonic muscle and rat EDL, respectively. Thus, the rates of Ca2+ uptake were similar in the two muscles, but the toadfish sonic muscle had about five times the capacity of the rat EDL. The number of pumps as estimated by thapsigargin titration was 68 +/- 4 nmol of Ca-ATPase per g tissue in the toadfish, and 42 +/- 5 nmol Ca-ATPase per g tissue in the rat EDL. The turnover number, defined as the Ca2+ uptake divided by the number of pumps, was 1065 +/- 150 min -1 for toadfish and 1786 +/- 230 min -1 for rat EDL (p < 0.05) at 37 degrees C. The Ca2+ uptake rate of toadfish sonic muscle at 22 degree C, a typical temperature for calling toadfish, averaged 42 +/- 1% of its rate at 37 degree C. At these operating temperatures, the toadfish SR is likely to be slower than the rat fast-twitch SR, yet the toadfish sonic muscle supports more rapid contractions. One explanation for this is that the voluminous SR provides activator Ca2+ for contraction, but the abundant parvalbumin plays a major role in relaxation.

Animals↗
PubMed1996

Specific phospholipid association with apolipoprotein A-I stimulates cholesterol efflux from human fibroblasts. Studies with reconstituted sonicated lipoproteins.

To understand how the lipid composition of high density lipoprotein mediates the efflux of cellular cholesterol, we have characterized the effects of variations in the lipid composition of well defined model sonicated apolipoprotein A-I (apoA-I)-containing lipoprotein (LpA-I) particle on cholesterol efflux from cultured human skin fibroblasts. LpA-I particles with varying content of phosphatidylcholine (POPC), phosphatidylinositol, sphingomyelin, cholesterol ester, and triolein were prepared by co-sonication. Association of as little as 5 mol of phosphatidylcholine with apoA-I is sufficient to transform lipid-free apoA-I into a distinct lipoprotein-like particle that is a significantly better acceptor of cellular cholesterol. Increasing the ratio of POPC/apoA-I from 5/1 to 35.5/1 in the sonicated LpA-I is associated with a significant increase in the release of cellular cholesterol. At low POPC/apoA-I ratios, native gradient gel electrophoresis of the LpA-I shows these lipoproteins to be small complexes (around 5-6 nm), with only 1 molecule of apoA-I (Lp1A-I). At a POPC/apoA-I ratio above 11/1, LpA-I form well defined complexes that contain 2 molecules of apoA-I (Lp2A-I) and range in size from 7.6 to 7.7 nm. Inclusion of sphingomyelin into an Lp1A-I further stimulates cholesterol efflux significantly. In contrast, inclusion of either sphingomyelin or phosphatidylinositol into a sonicated Lp2A-I has no effect on cholesterol efflux. Incorporation of cholesterol ester and/or triolein into an Lp2A-I particle is associated with a small reduction in cholesterol efflux to these lipoproteins. Therefore, cholesterol efflux from human fibroblasts is directly proportional to the amount and type of phospholipid in a sonicated LpA-I particle. Changes in the conformation and charge of apoA-I that result from changes in the lipid composition of a sonicated LpA-I particle appear to directly affect the ability of the lipoprotein to bind and retain cholesterol molecules. These data therefore suggest that the adsorption/desorption of cholesterol molecules to/from a sonicated LpA-I complex may be less sensitive to interfacial lipid-lipid interactions, but may depend on a conformation-dependent ability of apoA-I to bind cholesterol.

Apolipoprotein A-I↗
PubMed2004

Subjective response of people to simulated sonic booms in their homes.

In order to determine the effect of the number of sonic boom occurrences on annoyance, a computer-based system was developed for studying the subjective response of people to the occurrence of simulated sonic booms in their homes. The system provided a degree of control over the noise exposure not found in community surveys and a degree of situational realism not available in the laboratory. A system was deployed for eight weeks in each of 33 homes. Each day from 4 to 63 sonic booms were played as the test subject went about his or her normal activities. At the end of the day, the test subjects rated their annoyance to the sonic booms heard during the day. The sonic booms consisted of different combinations of waveforms, levels, and occurrence rates. The experiment confirmed that the increase in annoyance resulting from multiple occurrences can be modeled by the addition of the term "10 * log(number of occurrences)" to the sonic boom level. Of several noise metrics considered, perceived level was the best annoyance predictor. Comparisons of the subjective responses to the different sonic boom waveforms found no differences that were not accounted for by the noise metrics.

Adaptation, Physiological↗
PubMed1999

Sonic motor nucleus and its connections with octaval and lateral line nuclei of the medulla in a rockfish, Sebastiscus marmoratus.

The sonic motor nucleus and its fiber connections were examined in a rockfish, Sebastiscus marmoratus by means of tracer methods using horseradish peroxidase (HRP), biocytin, and carbocyanine dye (DiI). Sebastiscus has a swimbladder and a pair of extrinsic sonic/drumming muscles. The sonic muscle is ipsilaterally innervated by the occipital nerve which is composed of two ventral roots arising from the sonic motor nucleus. The sonic motor neurons are distributed in the most ventral part of the ventral column from the caudal medulla to the rostral spinal cord, and form a ventrally located columnar nucleus. Each neuron in this nucleus possesses a long thick dendrite and several short dendrites. The long dendrite extends dorsolaterally and branches in the lateral funiculus, whereas the short dendrites branch around their cell bodies. After biocytin injections into the sonic motor nucleus, two groups of premotor neurons were retrogradely labeled bilaterally, one in the dorsomedial portion of the descending octaval nucleus (DO) and the other in the medial zone of the reticular formation (RF) in the medulla. The DO premotor neurons were multipolar with several dendrites branching near the cell bodies, and the RF premotor neurons were bipolar. One of the two dendrites of the RF premotor neurons extends laterally into the ventral portion of the DO, and the other dendrite extends into the ventromedial area in the medulla. In the ventromedial dendritic field of the RF premotor neurons, descending fibers arising from the optic tectum (TO) and torus semicircularis (TS) traverse in the tractus tectobulbaris and terminate bilaterally. After DiI insertion into the ventromedial dendritic field, retrogradely labeled neurons were found bilaterally in the TS and TO. The majority of tectal neurons were located in the stratum griseum centrale. These neurons had two short basal dendrites branching in the cell layer and a long apical dendrite extending to the stratum fibrosum et griseum superficiale and stratum opticum. The toral neurons were bipolar and were distributed throughout the TS. Furthermore, biocytin injections into the medial nucleus of the lateral line system revealed that the nucleus projects bilaterally to the RF premotor neurons. These results show that premotor neurons for the sonic motor nucleus are located in the dorsomedial portion of the DO and the medial zone of the RF in the medulla. It is suggested that the sonic motor nucleus receives auditory input via the DO premotor neurons and input from RF premotor neurons which receive lateral line input via the medial nucleus, vestibular input through the lateral dendrite extending into the ventral portion of the DO, and information from the TO and TS via the tractus tectobulbaris.

Air Sacs↗
PubMed1997

The effects of seasonal hypertrophy and atrophy on fiber morphology, metabolic substrate concentration and sound characteristics of the weakfish sonic muscle.

Male weakfish Cynoscion regalis possess highly specialized, bilateral, striated sonic muscles used in sound production associated with courtship. Androgen-driven hypertrophy of the muscles during the late spring spawning period results in a tripling of sonic muscle mass followed by post-spawning atrophy. This study examined the morphological and biochemical changes underlying seasonal changes in sonic muscle mass and the functional effects of these on contraction as measured by sound production. Sonic muscle fiber cross-sectional area (CSA) increased significantly during the period of hypertrophy and then decreased by nearly 60%. Both the CSA of the contractile cylinder and that of the peripheral sarcoplasm decreased significantly by late summer, with the peripheral ring of sarcoplasm virtually disappearing. Muscle protein content followed a similar trend, suggesting a major loss of structural elements during atrophy. Muscle glycogen and lipid content decreased precipitously in early June during the period of maximal sound production. Sound pressure level increased and sound pulse duration decreased with increasing sonic muscle mass, indicating that sonic muscle fibers contract with greater force and shorter duration during the spawning season. Neither the pulse repetition rate nor the number of pulses varied seasonally or with muscle mass, suggesting that the effects of steroids on the acoustic variables are more pronounced peripherally than in the central nervous system. Seasonal sonic muscle hypertrophy, therefore, functions as a secondary sexual characteristic that maximizes vocalization amplitude during the spawning period.

Androgens↗
PubMed1996

Sonic hedgehog regulates patterning in early embryos.

Recently, a new family of genes, homologues of the Drosophila segment polarity gene hedgehog, has been cloned in vertebrates. One of them, Sonic hedgehog, is expressed in tissues that are known to be inductive centres for patterning early embryos, implicating Sonic hedgehog as an important signal in development. Functional experiments have demonstrated that Sonic hedgehog acts as a signalling molecule in patterning the anterior-posterior axis of the limb. By misexpression of Sonic hedgehog we show that Sonic hedgehog induces expression of Hoxd genes, known to be involved in patterning of the anterior-posterior axis of the limb, and Bmp-2, which might act as a secondary signal. We also demonstrate that Sonic hedgehog is not sufficient for these inductions. In fact, a signal from the mesoderm, Sonic hedgehog, and a signal from the ectoderm, Fgf-4, are required for the induction of Hoxd genes and Bmp-2.

Animals↗
PubMed1993

Depolymerization of hyaluronan by sonication.

High molecular weight hyaluronan (M(r) 400,000) obtained from human umbilical cord was depolymerized by sonication for 10 h into small molecules and finally into molecules of constant size (M(r) 11,000). The molecular size of the depolymerized hyaluronan was unaltered even under different conditions of sonication. After sonication, the main sugar residues at the reducing and non-reducing termini of depolymerized hyaluronan were N-acetylglucosamine (86%) and glucuronic acid (98%), respectively. Hyaluronans derived from rooster comb (M(r) 1 x 10(6)) and Streptococcus zooepidemicus (M(r) 1.2 x 10(6)) were depolymerized into molecules of different but characteristic sizes by sonication. On the other hand, neither chondroitin sulfate nor glycogen was depolymerized by sonication. These results suggest that high molecular weight hyaluronan may have some weak linkages related to N-acetylglucosamine in the chain, which are extremely sensitive to sonication. At present, however, the nature of these linkages is still unclear.

Animals↗
PubMed1999

Comparison of the cleaning efficacy of passive sonic activation and passive ultrasonic activation after hand instrumentation in molar root canals.

The purpose of this study was to compare the cleaning efficacy of passive ultrasonic activation with that of passive sonic activation after hand instrumentation. Sixty curved molar canals were hand-instrumented to size 35 and divided into three groups. Group 1 received no further treatment. Group 2 received 3 min of passive sonic activation. Group 3 received 3 min of passive ultrasonic activation. The roots were split and photomicrographs (x20) were made of the apical 6 mm of canal. A transparent grid was placed over projected images, and the total number of squares covering the apical 6 mm of canal space and the number of squares containing debris were counted. A debris score was calculated for each specimen by dividing the number of squares with debris by the total number of squares. The mean debris scores were 31.6% for hand instrumentation only, 15.1% for the sonic group, and 16.7% for the ultrasonic group. The debris scores for the sonic and ultrasonic activation groups were significantly lower than that for the hand instrumentation only group (p < 0.01); however, there was no significant difference between the sonic and ultrasonic activation groups. Passive sonics after hand instrumentation produces a cleaner canal than hand instrumentation alone and is comparable with that of passive ultrasonics.

Analysis of Variance↗
PubMedDate not supplied

Peripheral blood mononuclear cell sonicates as an alternative to irradiated allogeneic cells to stimulate a mixed lymphocyte reaction and to enumerate CD69+ alloreactive T cells.

An alloreactive reaction similar to that occurring during GvHD can be generated in a mixed lymphocyte culture. The presence of both stimulator and responder cells in these cultures makes the identification and enumeration of alloreactive cells difficult and unreliable. We describe the use of PBMC sonicates as an alternative to the standard MLC method to stimulate an allogeneic reaction. Using combinations of autologous or allogeneic PBMC sonicates, we showed that the lymphocyte proliferative response to cell sonicates was comparable to the response using irradiated cells. The proliferative response was concentration dependent and reached maximum levels at day 6. Both irradiated cells and PBMC sonicates induced significantly lower responses when the stimulating cells were partially HLA-DR matched rather than completely mismatched. Alloreactive T cells stimulated with sonicates were enumerated by the flow cytometric detection of CD69 or CD25. In HLA-mismatched cultures, approximately 7% of CD3+ T cells were CD69+ or CD25+, suggesting alloreactivity. Although there was a significant correlation between the expression of these activation markers and lymphocyte proliferative responses, significant individual variations in the results of these two assays were observed. The results in this study demonstrate the potential of using PBMC sonicates instead of irradiated lymphocytes for the study and identification of alloreactive cells at the cellular and molecular level.

Antigens, CD↗
PubMed2006

Sonication-assisted extraction of chitin from North Atlantic shrimps (Pandalus borealis).

The influence of sonication during extraction of chitin from North Atlantic shrimp (NAS) shells (Pandalus borealis) on chitin yield, purity, and crystallinity was investigated. Shells were peeled, washed, lyophilized, ground, and suspended for 4 h in 0.25 M HCl (1:40) at 40 degrees C followed by ultrasonication at 41 W/cm(2) for 0, 1, and 4 h, respectively. Demineralized shells were lyophilized, resuspended in 0.25 M NaOH (1:40), and ultrasonicated at 41 W/cm(2) for 0, 1, and 4 h to remove proteins. The yield and mineral and protein contents were determined after each processing step. The purity of extracted chitin was determined from the total amount of glucosamine. The crystallinity index and size of crystals were calculated from wide-angle X-ray scattering measurements. Scanning electron microscope images were recorded to evaluate morphological changes in samples. The yield of chitin from NAS decreased from 16.5 to 11.4% for 0 and 1 h sonicated samples, respectively, which was attributed to increased concentrations of depolymerized materials in the wash water. Sonication did not enhance the removal of minerals. The application of ultrasound enhanced the removal of proteins from 39.8 to 10.6, 8.3, and 7.3% after 0, 1, and 4 h of sonication treatments. The crystallinity index of chitin decreased from 87.6 to 79.1 and 78.5% after 1 and 4 h of sonication, yielding chitosans with crystallinity indices of 76.7, 79.5, and 74.8% after deacetylation, respectively. Fourier transform infrared spectroscopy scans indicated that the degree of acetylation of chitins was unaffected by sonication. Comparison of the extraction results of NAS with that from freshwater prawns indicated that more impurities were left in NAS chitin, suggesting that composition and structural arrangement of chitin in shells influence the efficiency of ultrasound-assisted extraction.

Chitin↗
PubMed2005

Optically sensing additional sonication effects on dispersed HiPco nanotubes in aerated water.

Ultrasonication is a necessary process to make single-walled carbon nanotubes (SWNTs) soluble in aqueous solution with surfactants such as sodium dodecyl sulfate (SDS). However, an understanding of the sonication effects on the electronic and optical properties of SWNTs in aqueous solution is still lacking. Here, we have observed that sonication-induced pH changes suppress the optical transitions of the first interband transition pair (S11) in the density of states of semiconducting SWNTs while other possible intermediates induced by sonication contribute less significantly to the observed spectral changes without the involvement of sonication-induced pH decrease. The suppressed S11 peaks can be restored by adding basic solution, suggesting that the lattice structure of SWNTs is undisrupted by the sonication used here. The absorbance of S11 peaks shows a nearly linear relationship with sonication-induced pH changes in the narrow pH range of 5.2 and 6.1. The results indicate that SDS-encased SWNTs may be used as an indicator for sonolysis-related applications.

Nanotubes, Carbon↗
PubMed1994

Treatment of subgingival implant surfaces with Teflon-coated sonic and ultrasonic scaler tips and various implant curettes. An in vitro study.

Removal of plaque and calculus by means of sonic and ultrasonic scalers causes considerable damage to implants. With a view to avoiding the aggressive effects of these instruments, an experimental study was carried out for which conventional sonic and ultrasonic scalers were coated with Teflon. The effects of these instruments on implant surfaces was then compared with that of plastic and metal implant curettes. Stereo-microscopy, scanning electron microscopy and surface profilometry were used to detect and record damage to implant surfaces and changes in surface roughness. Generation and propagation of heat in subgingival simulation of use of sonic and ultrasonic scalers were also recorded by means of temperature measurements at the implant surface. The results revealed that no discernible damage was caused by Teflon-coated sonic and ultrasonic scalers or implant curettes made of plastic on smooth titanium surfaces. Instrument material residues were found on rough implant surfaces. It was not the intention of this study to provide an analysis of the prerequisites for the cleaning of rough implant surfaces, but rather to determine what type of damage is to be expected when contact is made with smooth and rough surfaces unintentionally. Temperature measurements during the subgingival use of sonic and ultrasonic scalers indicated satisfactory functioning of the cooling system. Coating of sonic and ultrasonic scaler tips with Teflon thus facilitates the use of high-frequency instruments to achieve professional cleaning of implants.

Dental Implants↗
PubMed1996

Sonicated vascular catheter tip cultures. Quantitative association with catheter-related sepsis and the non-utility of an adjuvant cytocentrifuge Gram stain.

Microbial quantification of potentially infected intravenous catheters is used to determine whether the removed device may be the source of sepsis. In this study, the authors defined a clinically significant colony count using the sonication technique to implicate the catheter as the source of sepsis. The utility of a cytocentrifuge-prepared Gram's stain of sonication broth as a rapid test for the accurate diagnosis of catheter-related bacteremia and fungemia was also evaluated. Initially, 230 consecutive vascular catheter cultures were performed. In 14 patients, the blood culture was found to grow in the same organism as the catheter culture. The eight blood-culture positive patients with probable catheter-related sepsis had four catheters with 10(4)-10(5), and four with more than 10(5) CFU derived from the catheter sonication broth. Six bacteremias not catheter related showed three catheters with < 10(3), two with 10(3)-10(4), and one with > 10(5) CFU. One catheter-related bacteremia had a negative culture. A subsequent validation study on 175 catheter specimens using 1,000 CFU as a cut-off between a positive and negative test fully separated eight patients with catheter-related bacteremia from six patients with infection at a distant site. Cytospin Gram stain, studied in the initial evaluation, was positive in 17 catheters with < 10(3) CFU, 4 at 10(3)-10(4), 4 at 10(4)-10(5) and 9 with > 10(5) CFU in the sonication broth. No correlation was found between this test and catheter-related sepsis. From these results, the authors concluded that those catheters with counts below 10(3) CFU in the catheter sonication broth do not appear to have an association with catheter-related sepsis, and that a Cytospin Gram stain done with the sonication technique does not correlate with the presence of catheter sepsis.

Bacteremia↗
PubMed1985

Comparison of sonicated and nonsonicated specimens for the isolation of Chlamydia trachomatis.

Cultures of sonicated and nonsonicated chlamydial specimens were compared using a Heat Systems sonicator with a cup-horn attachment for sonication. Chlamydial inclusions were detected in 71 of 780 cultures tested; 44 (62%) were positive from both, while 12 (16.9%) were positive in nonsonicated only, and 15 (21.1%) in sonicated specimens only. The mean number of inclusions from sonicated specimens was more than double that from nonsonicated specimens. The cultures of sonicated specimens could be screened more quickly because of statistically significant higher inclusion counts, less toxicity, and the absence of overlying epithelial cells.

Bacteriological Techniques↗
PubMed2000

Sonication per se is not as deleterious to sperm chromosomes as previously inferred.

Although sonication is a simple way to immobilize ("kill") spermatozoa prior to injection into oocytes, this has been thought to be destructive to sperm chromosomes. Mouse and human spermatozoa were immobilized by sonication and kept in various media for up to 2 h, then their nuclei were individually injected into mouse oocytes for the analysis of chromosomes at the first cleavage metaphase. In both the mouse and human, incidence of structural chromosome aberrations was much higher in the spermatozoa sonicated and stored in Biggers-Whitten-Whittingham medium for 2 h at 37.5 degrees C than in those stored for 5 min in the same medium. We concluded, therefore, that it is not sonication per se but a prolonged exposure of sperm nuclei to extracellular milieu that is detrimental to sperm chromosomes. The incidence of structural chromosome aberrations of mouse and human spermatozoa was significantly reduced when the spermatozoa were sonicated and stored in K(+)-rich nucleus isolation medium containing EDTA. This suggests that sperm chromosome degradation following sperm immobilization by sonication is partly due to detrimental effects of a Na(+)-rich medium and of DNase on sperm chromatin. Ideally, it should be possible to prepare artificial media that maintain the integrity of sperm chromosomes for many hours after immobilization.

Animals↗
PubMed1998

Sonic and mechanical toothbrushes. An in vitro study showing altered microbial surface structures but lack of effect on viability.

The purpose of the present study was to compare the in vitro effects of a mechanical and a sonic toothbrush on the viability of Actinomyces viscosus, the rationale being that induction of irreparable microbial damage resulting from aggressive mechanical action or sonic energy, may inhibit or disrupt the process of successional colonization. Cultures of A. viscosus were grown to a standardized optical density and subdivided into 3 treatment groups of 20 specimens each. Treatment groups consisted of an untreated control and exposure to a mechanical or sonic toothbrush for 15, 30, 45, and 60 s. Subsequent to the prescribed treatment, samples were taken from each specimen dish, subcultured, and the number of CFUs determined. Additional samples were obtained for negative staining and examination by electron microscopy. The mean number of CFUs for each treatment group at each treatment interval were statistically analyzed by ANOVA and multiple pairwise comparisons. Results showed a significant main effect for toothbrushes (p<0.0001) and exposure time (p<0.01), but only marginal significance for the interaction of toothbrush with exposure time (p<0.055). Post-hoc tests showed a significantly greater number of CFUs for the sonic toothbrush compared to both the untreated control and mechanical toothbrush groups. Electron microscopic examination revealed a decrease in aggregation tendency and loss of fimbriae in the sonic toothbrush group. Based on the lack of morphologic evidence that would indicate cell damage and the increase in CFUs over that of the control group, it appeared that neither the mechanical or sonic toothbrushes affected cell viability.

Actinomyces viscosus↗