bluuebunny/crossref_metadata_2025 huggingface dataset:
Bond strength of porcelain on cast vs. wrought titanium
Authors: Dérand Tore , Herø Håkon
Published: October 2007

The bond strength of porcelain fused to cast and wrought titanium surfaces was calculated from fracture loads in a 4‐point bending test. Two different porcelain were applied (O'Hara and Duceratin). The surface of Ti‐cast specimens was treated in two different ways to produce variations in the impurity level before porcelain veneering. Microhardness measurements as well as scanning electron microscopy with EDX analysis were conducted. The results showed no significant difference in bond strength between the two porcelains. Nor was any difference in bond capacity found between thoroughly blasted castings and wrought titanium. Significantly lower bond strengths were observed for lightly blasted specimens and for specimens treated with Gold bonding agent. Impurities in the surface region of the castings were found to be due to contact with the investment during solidification. This indicates that a thin surface layer (50–100 μm) of the casting should be removed before firing of the porcelain.
Changes in amount of gingival crevicular fluid after a single episode of periodontal treatment
Authors: Talonpoika Juha T.
Published: October 2007

A total of 51 periodontal sites from 6 adults with no systemic diseases or medication were selected for the study. All sites showed radiologic bone loss and pockets of 4 mm or more. Crevicular fluid (CF) was collected by inserting filter paper strips into periodontal pockets for 5 s and was measured by Periotron. Samples were collected before and 2, 5, 10, 20, and 40 days after a single episode of periodontal treatment (scaling, root planing and curettage). Plaque Index (PII), Papilla Bleeding Index (PBI) and pocket depth (PD) were measured before and 40 days after treatment. The amount of bone loss was estimated from orthopantomograms taken immediately before the trial. Two days after treatment an increase in the amount of CF was seen. After this the amount of CF decreased, reaching the pretreatment level on day 5 after treatment and a level clearly below pretreatment level on day 10 after treatment. Forty days after treatment a slight increase in the amount of CF was seen. The difference between pretreatment values and values at days 2, 10, 20, and 40 was highly significant. In pretreatment samples, positive correlations were found between the amount of CF and PD, PBI and bone loss and, in samples collected 40 days after treatment between CF and PD. CF measurements made before treatment were of no value in predicting the changes in clinical parameters after treatment.
Antibiotic prescribing practices among Norwegian dentists
Authors: Preus Hans R. , Albandar Jasim M. , Gjermo Per
Published: October 2007

There is scarce information on antibiotics prescription habits among dentists in general. The present investigation was undertaken to study some patterns of antibiotics prescription among Norwegian dentists. A total of 459 dentists (∼ 10% of Norwegian dentists) were randomly selected, and to each was mailed a letter describing the survey, accompanied by a questionnaire about age, type of practice, educational background and pattern of prescription of antibiotics. 78% of the dentists responded to these questions. The results indicate that during a typical week, 32% did not prescribe antibiotics, whereas 5% wrote ≥ 5 prescriptions. The mean weekly number of prescriptions per dentist was 2.04. Periodontists and oral surgeons prescribed antibiotics significantly more often than did general practitioners and other disciplines. In addition, those with research and/or teaching experience seemed to prescribe significantly more often than those without. More than 1/3 of the sample indicated that they may prescribe antibiotics when treating periodontal diseases. Compared with other disciplines, periodontists prescribed such drugs significantly more often when treating periodontitis, but significantly less often in acute gingivitis, stomatitis and herpes simplex infections. Moreover, 22% of the dentists might prescribe antibiotics when the patient is in pain, 73 and 38% in cases of abscesses with or without generalized malaise, 2.5% in endodontic therapy, 60% to prevent general complications, and 68% for prophylactic use if the patient revealed a history of endocarditis. Norwegian dentists are somewhat restrictive in their prescription of antibiotics, but they mostly prescribe the correct drugs for the different conditions.
Caries, views and perspectives
Authors: Bratthall Douglas
Published: October 2007

This paper describes some advances in caries research in the last century. A tremendous body of knowledge about the disease as well as several possibilities for caries prevention and treatment have been obtained. This knowledge is not used by people in developing countries and certain obstacles for implementation of the procedures under such conditions are identified. Research aimed at finding practical means and methods that can help prevent caries and other oral diseases for the majority of the world's population must be intensified.
Recent development in endodontic research
Authors: Tronstad Leif
Published: October 2007

In essence, endodontics as a clinical disipline is concerned with the prevention and treatment of pulpal and periapical infection. In recent research the infective process has been investigated as well as the mechanisms by which the pulp and periodontium deal with microbial insults. With regard to the pulp, findings on the hemodynamics of pulpitis suggest that the inflammatory response in this tissue is much less influenced by the special anatomic environment of the tooth than was previously believed. Pulpal diseases are being underdiagnosed, mostly because of inadequate examination methods. Laser Doppler flowmetry which gives a vascular rather than a nervous response may gain importance in pulpal diagnostics in the future. It is established that apical periodontitis with bone resorption cannot develop in the absence of bacteria in the root canal system. Root canal infection is characterized by a wide variety of combinations of relatively few anaerobic bacteria, and bacterial synergism plays an important role in maintaining the infection. Microbial invasion of an apical granuloma may take place. Non‐oral and environmental organisms like Pseudomonas aeruginosa are frequently isolated from treatment‐resistant cases. Success of endodontic treatment depends on the reduction or elimination of the infecting bacteria. This may predictably be obtained after a thorough chemo‐mechanical instrumentation and disinfection of the root canal with calcium hydroxide. The standardized technique which entails the preparation of a cylindrical apical box with removal of significant amounts of den tin near the root apex predictably gives a clean canal. This technique has provided excellent clinical and radiographic results in well documented follow‐up studies.
Occurrence and distribution of blackish staining on the crowns of human teeth obtained from an archeological excavation of a medieval site in Norway
Authors: Beyer‐Olsen Eva Margrete Stermer , Risnes Steinar
Published: October 2007

An excavation in Trondheim, Norway, in 1984–85, uncovered a part of the medieval (1100–1600) cemetery of St Olav's Church. Of 388 excavated skeletons, 248 had skulls where the condition of the jaws and teeth allowed examination.’In 51 of these skulls the teeth exhibited a characteristic blackish staining. A higher percentage of affected skulls was found in areas with organic, wood‐chip layers than in areas with gravelly sand. Affected skulls tended to have a high percentage of their teeth stained, but the staining tended to be restricted to only one or two of the three tooth surfaces scored. Posterior teeth were more often affected than anterior teeth, the occlusal/incisal part more often than the cervical part, and the buccal/labial part more often than the lingual part. Nonerupted third molars could also be stained. Staining seemed to be hampered by calculus. Occurrence of staining was independent of the presence or absence of a coffin and of coffin type. The extent of staining (% of stained surfaces within a dentition) was independent of sex and age. High correlation was found between all four jaw quadrants. There was no independence between color of the jawbone and occurrence of stained teeth. It was concluded that the staining phenomenon probably can be ascribed to factors in the soil. In vivo predisposing influences cannot be excluded.
Inhibition of bovine dentin demineralization by a glutardialdehyde pretreatment: an in vitro caries study
Authors: Boonstra Willem , de Vries Joop , ten Bosch Jaap , Ögaard Björn , Arends Joop
Published: October 2007

Intact bovine dentin specimens were demineralized in 25 mmol acetic acid buffers (pH 5), with and without a 5‐min pretreatment with an acidic 2% glutardialdehyde (GDA) solution. The results demonstrate that GDA inhibits dentin demineralization and that the inhibition depends strongly on the initial calcium and phosphate concentration in the demineralization solution. The observed inhibition increases from about 5% without calcium and phosphate to 38% with a calcium and phosphate concentration initially of 6.4 mmol and 4.1 mmol, respectively. The inhibition can be explained either by a reduction of calcium and phosphate diffusion out of the lesion or by the retention of mineral inhibitors in the dentin.
Effect of maxillomandibular fixation on condylar growth in juvenile Macaca mulatta: a cephalometric and histologic study
Authors: Isacsson Göran , Carlson David S. , McNamara James A. , Isberg Annika M.
Published: October 2007

The effect of maxillomandibular fixation on the growth of the mandibular condyle was studied in eight control and eight experimental male juvenile monkeys. All animals had metallic implants placed throughout the craniofacial complex in order to facilitate cephalometric analysis of growth‐related changes in the maxillomandibular complex during jaw immobilization. Every 3, 6, 12, and 24 wk after insertion of the appliance two experimental animals were killed for histologic analysis. Cephalometric analysis indicated no major deviation from normal maxillary or mandibular growth in the experimental animals. The condylar growth in the experimental animals was comparable with that of the controls. Histologic analysis indicated that the articular connective tissue in experimental joints remained the same thickness as in the controls. On the postero‐superior aspect of the condyle, the thickness of the prechondroblastic‐chondroblastic cell layer was reduced by 70–80% in the experimental animals. On the posterior aspect this cell layer was not visible after 12 wk of fixation, but was replaced by a periosteum‐like, cell‐rich tissue which appeared to be active in appositional formation of cancellous bone. These results indicate that long‐term maxillomandibular fixation does not cause major alterations in the growth of condyle or the entire mandible despite a profound decrease of the prechondroblastic‐chondroblastic cell layer in the postero‐superior and posterior regions of the condyle. The growth is probably due to a compensatory appositional bone formation along the surface of the condyle. It is also concluded that jaw mobility is not a prerequisite for normal maxillary or mandibular growth.
Cytotoxic and antibacterial effects of orthodontic appliances
Authors: Grimsdottir Margret Rosa , Hensten‐Pettersen Arne
Published: October 2007

The cytotoxic and antibacterial effects of orthodontic appliances were assessed. Metallic devices used in orthodontics, such as molar bands, brackets, and archwires were tested by the agar overlay cytotoxicity test with mouse fibroblast cells. The same devices were tested for antibacterial effect with Streptococcus mutans and S. sanguis. The multicomponent devices, which are bonded with silver‐ and copper‐based brazing alloys, were more cytotoxic than the single‐component devices, probably because copper is more cytotoxic than nickel. The devices had a definite, but low, antibacterial effect, as compared with the 0.05% chlorhexidine positive control. A cytotoxic effect of the devices per se might contribute to a localized gingivitis. It is uncertain whether orthodontic devices have any significant inhibitory effect on dental plaque viability.
Tissue plasminogen activator (t‐PA) and placental plasminogen activator inhibitor (PAI‐2) in gingival fluid from 8–9‐year‐old children
Authors: Kinnby Bertil , Borgström Margareta Krasse , Granath Lars , Lecander Ingegerd , Sundin Birgitta
Published: October 2007

High concentrations of tissue plasminogen activator (t‐PA) and placental type plasminogen activator inhibitor (PAI‐2) have previously been found in gingival crevicular fluid (GCF) of adults. In the present study, the levels were examined in 16 children aged 8–9 yr. Sampling of GCF was performed with small disks of Millipore‐filter. t‐PA and PAI‐2 were analyzed with enzyme‐linked immunosorbent assays with low method errors. The mean concentration of t‐PA was slightly higher than in adults, while the mean PAI‐2‐concentration was slightly lower. An intraindividual study comparing healthy and inflamed sites in the children showed slightly higher concentrations in GCF from inflamed sites. No change was observed in the balance between t‐PA and PAI‐2.
Cyclosporin‐A‐induced gingival overgrowth in renal transplant children
Authors: Wondimu Biniyam , Dahllöf Göran , Berg Ulla , Modéer Thomas
Published: October 2007

Gingival overgrowth was assessed in renal transplant children, 19 boys and 13 girls, aged 2.5–18 yr, who had been on a cyclosporin‐A (CsA)‐based immunosuppressive regimen for at least 12 months. Data collected included number of posttransplant months, total CsA dose administered during the first 6 posttransplant months, oral dose and blood trough level of CsA on the day of examination, plaque accumulation (VPI%), gingival inflammation (GBI%), loss of attachment, and gingival overgrowth. Thirteen percent of the children exhibited gingival overgrowth characterized by one or more units with increased sulcus probing depth (≥4 mm), i.e. pseudopockets. The total amount of CsA administered during the first 6 posttransplant months was significantly higher in the children with gingival overgrowth than in those without. The study indicates that the development of CsA‐induced gingival overgrowth is positively related to the total dose of the drug administered to the children during the first 6 posttransplant months.
Doxycycline prevents root resorption and alveolar bone loss in rats after periodontal surgery
Authors: Grevstad Hans Jacob
Published: October 2007

The effect of systemic doxycycline administration on frequency of root resorption cavities and extent of bone loss following periodontal surgery was studied in albino rats. Thirty Wistar rats with healthy gingiva were divided into four groups. Six untreated animals (Group 1) served as controls. Gingivectomy (Group 2, six rats), mucoperiosteal flap operation (Group 3, eight rats), and mucoperiosteal flap operation with doxycycline added to the drinking water (Group 4, 10 rats) were performed on the palatal aspect of maxillary left molars. After a healing period of 3 wk, the rats were killed by an overdose of sodium pentothal, and specimens of first molars were prepared for light microscopy. Root resorption was absent in normal and gingivectomized animals (Groups 1 and 2). Resorption cavities occurred in all flap‐operated animals (Group 3) and in one of 10 doxycycline‐treated animals (Group 4). The distance from cementoenamel junction to alveolar bone crest remained unchanged in gingivectomized (Group 2) and doxycycline‐treated animals (Group 4), as compared with control specimens. In flap‐operated animals (Group 3), the crestal bone level was located more apically than in doxycycline‐treated rats (Group 4). This study has shown that root resorption and bone loss were associated with flap operations involving exposure of periodontal ligament and bone. Systemic doxycycline prevented both root resorption and bone loss.
Eubacterium yurii subspecies margaretiae is resistant to nonopsonic phagocytic ingestion
Authors: Kerosuo Eero , Haapasalo Markus , Lounatmaa Kari
Published: October 2007

We have previously shown that strains of Eubacterium yurii are hydrophobic, as compared with human polymorphonuclear leukocytes (PMNs), possibly because of a crystalline surface layer (S‐layer) covering the cell envelope of this potential endo‐perio pathogen. The aim of the present study was to investigate the phagocytic ingestion by PMNs of the three E. yurii subspecies, with special attention to bacterial surface structures and hydrophobicity. Type strains of subspp. margaretiae, yurii, and schtitka, together with three clinical isolates from necrotic root canals, were studied. All strains were hydrophobic when tested by a two‐phase partition method. E. yurii subspp. margaretiae strains ATCC43715T, ES4C, and ES14B‐8E were resistant to PMN ingestion in the absence of opsonins, whereas strains of the two other subspecies were readily ingested. The presence of a resistant strain (subsp. margaretiae ATCC43715T) did not inhibit the ingestion of a sensitive strain (subsp. schtitka ATCC43716T). Ingestion of E. yurii subsp. margaretiae strains required opsonization by normal human serum or specific antibodies. Electron microscopy revealed an S‐layer in all strains and fimbria‐like structures in the subspp. margaretiae and yurii strains. The antiserum prepared against the S‐protein of E. yurii subsp. margaretiae ATCC43715T showed only slight cross‐reactivity with other E. yurii strains and indicated the presence of strain‐specific rather than species‐ or subspecies‐specific antigens in the S‐protein of E. yurii subsp. margaretiae ATCC43715T. The results suggest that the mere presence of the S‐layer or fimbria‐like structures cannot explain the susceptibility to ingestion by the PMNs. It is possible that specific‐receptor‐mediated binding overrides the importance of hydrophobicity in the nonopsonic phagocytosis of E. yurii subspecies.
Varicella‐zoster virus DNA in recurrent aphthous ulcers
Authors: Pedersen Anne , Madsen Hans O. , Vestergaard Bent Faber , Ryder Lars P.
Published: October 2007

The present study was undertaken to examine for varicella‐zoster virus (VZV) constituents in recurrent aphthous ulcers (RAU). Smears and biopsies of ulcers 0–3 days old were obtained from 20 otherwise healthy minor/major RAU patients and from two patients with Behçet's syndrome. VZV could not be cultivated from any of the biopsies, all smears were negative for VZV antigen, and in situ hybridization on the five samples tested was negative for VZV nucleic acid. DNA extracted from biopsies, however, yielded positive polymerase chain reaction (PCR) products in all cases with one primer set of the protein kinase 66 (PK66). Ten control biopsies from non‐RAU subjects yielded no PCR products apart from the sample from AP, who obtained the biopsies, and from HOM, who performed the PCR, suggesting that the DNA had been passed on from the patients. Other parts of the PK66 gene and of thymidine kinase 36 yielded no products. Although the consistent presence of VZV DNA in RAU might suggest a pathogenetic implication, the potential presence and possible pathogenetic importance of other herpesviruses cannot be excluded.
Molecular forms and concentration of fibronectin and fibrin in human gingival crevicular fluid before and after periodontal treatment
Authors: Talonpoika Juha , Paunio Keijo , Söderling Eva
Published: October 2007

A total of 23 periodontitis‐affected sites from seven adults was selected for the study. Crevicular fluid (CF) samples were collected with paper strips before treatment (scaling, root planing, and curettage) and 2, 5, 10, 20, and 40 days after treatment. Each sample was eluted into sterile saline and two aliquots were drawn for gel electrophoresis: one for fibronectin and one for fibrin analysis. Peptides were transferred to nitrocellulose membranes, and molecules were detected by specific antibodies. The proportions of different molecular forms of fibronectin and fibrin were analyzed by laser densitometry. Plaque Index, Papilla Bleeding Index, and pocket depth were recorded before and 40 days after treatment. Radiologic bone loss was estimated from orthopantomograms. Two days after treatment, an increase was seen in the proportions of intact fibronectin, fibronectin fragments larger than 70 kDa, and fibrin‐positive material with a greater molecular mass than intact fibrin. Between days 5 and 10, the proportions of these large fragments decreased. The highest fibronectin and fibrin concentrations were seen 10 days after treatment. These changes probably reflect degradation of the subgingival fibrin clot formed after treatment, and indicate resolution of the clot during the first 10 days of healing. This agrees well with previous observations of CF plasmin activity and concentration of collagen synthesis markers in CF after periodontal treatment, and with the histologic changes seen during periodontal healing. Results of the present study, together with earlier reported findings of collagen synthesis after periodontal treatment, also support the hypothesis of sequential appearance of fibronectin and collagens during the process of wound healing.
Microvasculature of the dorsum of the rat tongue: a scanning electron microscopic study using corrosion casts
Authors: Selliseth Nils J. , Selvig Knut A.
Published: October 2007

The purpose of this study was to examine the microvascular system of the dorsum of the rat tongue in relation to the subepithelial connective tissue relief. Methylmethacrylate corrosion casts of the vasculature as well as specimens in which the epithelium had been removed were prepared and examined by scanning electron microscopy (SEM). The SEM images revealed four distinct layers in the vasculature of the lamina propria. Superficially, Layer 1 comprised the irregularly shaped ends of capillary loops. Layer 2 consisted of parallel ascending and descending capillaries. These two layers were drained by the subjacent Layer 3, a fish‐net‐like venous plexus. More deeply, Layer 4 contained arterioles ascending from the muscular layers of the tongue. The vessels of larger papillary structures formed cylindric networks supplied by several arterioles and drained through a single venule to the venous plexus in Layer 3. At their base, the capillary loops often showed a constriction, suggestive of a sphincter. Arteriovenous anastomoses were rare. The epithelium‐connective tissue interface showed short conical papillae as well as larger papillary structures which corresponded in both distribution and size to the capillary loops found in the vascular casts. The results confirm that the tongue is highly vascularized and demonstrate that the vascular supply to the papillae, taste buds, and other surface structures forms a highly organized and specific system which is adapted to the specific functions of this organ in the rat.
Effect of fluoride on caries progression and dentin apposition in rats fed on a cariogenic or non‐cariogenic diet
Authors: Kortelainen Sinikka , Larmas Markku
Published: October 2007

The effect of fluoride in drinking water on the progression of dentinal caries and dentin apposition was studied in Wistar rats. The initiation of enamel caries lesions was first induced for 2 wk with S. sobrinus and a 43% sucrose diet after weaning. Thereafter the animals were fed on either a cariogenic or a non‐cariogenic diet and distilled water supplemented with 0, 1, 7 or 19 ppm fluoride. The areas of dentinal caries and dentin apposition were quantified after tetracycline staining. Fluoride reduced dentinal caries progression after the initiation of lesions in the presence of a cariogenic diet at a concentration of 19 ppm F, and without sucrose at 1 ppm F. The effect of fluoride in reducing dentin apposition with a cariogenic diet was dose‐dependent, whereas fluoride in non‐cariogenic groups had practically no effect on dentin formation. These results suggest that fluoride together with a high concentration of sucrose in the diet might have an odontoblast‐mediated effect on the regulation of the progression of dentinal caries.
Computerized planimetric method for clinical plaque measurement
Authors: Söder Per‐Östen , Jin Li Jian , Söder Birgitta
Published: October 2007

A computerized planimetric method for plaque area measurement has been developed. Using a computerized image analysis system (CIAS), the plaque area and tooth area on color slides were digitized and the number of pixels automatically counted. The proposed Plaque Percent Index (P% Index) expresses plaque area as a percentage of tooth area. The reproducibility of this method was tested and the influence of photographic technique on the P% Index was determined. The association of the Turesky modified Quigley‐Hein plaque index (Q‐H Index) and the P% Index was assessed. The present method was highly reproducible for the P% Index with an intraexaminer variation of 0.28% and intraexaminer correlation coefficient of 0.99. The results show that highly reproducible P% Index values with an error of less than 3.0% were obtained when the photographs were taken under the following conditions. For the buccal surfaces of anterior teeth, the slides were photographed within a 20‐degree range in the horizontal plane and a 30‐degree range in the vertical plane; and for the lingual/palatal surfaces of anterior teeth and the buccal or lingual/palatal surfaces of posterior teeth, the slides were photographed with an image of the whole tooth surfaces in the photographic mirrors. The comparison of the Q‐H Index and the P% Index revealed that for each score of the Q‐H Index the corresponding values of P% Index were wide with a significant crossover value, although a strongly positive correlation was found between the Q‐H Index and the P% Index (r = 0.92, P<0.01). This study indicates that the proposed P% Index, quantitatively expressed on an interval scale, has high reproducibility and discriminative power.
Objective and subjective efficacy evaluation of various polymer‐based saliva substitutes
Authors: Olsson Håkan , Axéll Tony , Carlsson Anders , Bogentoft Conny
Published: October 2007

Various polymer solutions with and without surfactants were evaluated regarding their lubricating properties on the oral mucosa. After rinsing with the solutions, the oral mucosal friction value was registered with a probe (objective effect). After each rinsing occasion at home, the patients answered a questionnaire (subjective effect). None of the tested polymers showed a longer, clinically significant effect than the other ones. Some of them had the same effect as substitutes available on the Swedish market.
Correlation between depth of cure and surface hardness of a light‐activated resin
Authors: Hansen Erik Keith , Asmussen Erik
Published: October 2007

Microfilled test specimens were polymerized for 40 s with 10 different curing units. The specimens were stored for 7 days at 36±0.5°C, and then the hardness of the surface was measured. The depth of cure of the 10 units was also measured, but no correlation was found between surface hardness and depth of cure. Even inferior curing units were able to polymerize the surface just as effectively as good light sources. The conclusion is that one cannot use the surface hardness of an irradiated resin to assess the quality of a curing unit.
Correlation between depth of cure and temperature rise of a light‐activated resin
Authors: Hansen Erik Keith , Asmussen Erik
Published: October 2007

The temperature rise, caused by 10 different curing units, in a prepolymerized resin specimen was examined. For all units, the temperature increase in a 60s cycle followed a logarithmic curve, with the most effective light sources giving the highest temperature rise. In the surface layer the change of temperature ranged between 3.6 and 29.2°C, and 3.2 mm below the irradiated surface between 1.5 and 12.3°C. The use of a 2‐mm‐thick isolating layer of glass ionomer resulted in a significant reduction in the temperature increase. The correlation between the depth of cure and the temperature rise was of an exponential or power nature; i.e., a small increase of the depth of cure was followed by a disproportionately high increase in temperature.
Similarities between Fusobacterium nucleatum and Bacteroides fragilis studied by two DNA probes derived from Fusobacterium nucleatum
Authors: Bolstad Anne Isine , Kleivdal Hans , Jensen Harald B.
Published: October 2007

A polymerase chain reaction (PCR)‐amplified oligonucleotide DNA probe corresponding to a Fusobacterium nucleatum Fevl DNA region coding for a 40‐kDa major outer‐membrane protein (OMP) and a randomly cloned 2.1 kb DNA probe were found to recognize DNA from the Gram‐negative bacteria Fusobacterium nucleatum and Bacteroides fragilis on Southern blots and slot blots. The results indicate sequence similarity within the DNA fragments studied. Immunoblots tested with polyclonal antibodies against whole cells of F. nucleatum revealed only weak antigen similarity between these species.
Dental plaque inhibition by a combination of triclosan and polydimethylsiloxane (silicone oil)
Authors: Ellingsen Jan Eirik , Rölla Gunnar
Published: October 2007

It has previously been shown that a toothpaste which contains triclosan and polydimethylsiloxane (silicone oil) improved gingival health in a test panel with established gingivitis more markedly than usually observed when testing commercial triclosan‐containing toothpastes. In the present study the mode of action of combinations of silicone oil and triclosan was investigated. An in vitro experiment showed that triclosan was retained in a thin layer of silicone oil on the inner surfaces of test tubes that had been treated with the combination of triclosan and silicone oil. This triclosan was slowly released and inhibited the growth of bacteria in the test tubes. Silicone oil alone and in combination with triclosan was able to inhibit polysaccharide adhesion to the test tubes in the presence of a strain of Streptococcus sobrinus and a sucrose‐containing medium. Corresponding in vivo experiments showed similar results; teeth topically treated with silicone oil and triclosan showed a marked plaque reduction, and those treated with silicone oil alone showed a moderate reduction, as compared with a placebo. The silicone oil plus 0.3% triclosan combination inhibited plaque formation also on proximal surfaces. It appears likely that this combination provides a reservoir of triclosan in the thin layer of silicone oil which binds strongly to teeth because of its low surface tension. Triclosan is then slowly released into saliva because of its low solubility in this fluid.
Hg‐provocation of oral mucosa in patients with oral lichenoid lesions
Authors: Warfvinge Gunnar , Hellman Mats , Maroti Marianne , Ahlström Ulf , Larsson Åke
Published: October 2007

Five amalgam‐bearing patients, with clinically and histologically confirmed oral lichenoid lesions, were tested by applying 0.5% Hg in petrolatum for 10 min to clinically normal mucosa. Control sites were exposed to petrolatum only. Four amalgam‐bearing patients with no clinical evidence of oral lichenoid lesions served as controls; they were subjected to similar Hg and petrolatum exposure. After 24 h, biopsies were taken and immunocytochemically analyzed with monoclonal antibodies to lymphoid and nonlymphoid cells. No distinct differences could be detected between the Hg‐exposed areas of the lichen patients and those of the nonlichen patients. Furthermore, normal mucosa exposed to petrolatum only showed a staining pattern in the lichen patients which was no different from the nonlichen patients. The findings are discussed with respect to possible mechanisms of development of lichen‐like lesions in oral mucosa.
Concurrence of torus mandibularis and torus palatinus
Authors: Eggen Svein , Natvig Bent
Published: October 2007

Analysis of the concurrence of torus mandibularis and torus palatinus among a total of 2010 dental patients, by the test of independence, revealed that the concurrence was statistically significant among women, but not among men. A tentative hypothesis was proposed to explain the sexual dimorphism of the variable, combined occurrence of the two features.
Autometallographic demonstration of mercury in rat molars
Authors: Eide Rune , Schiönning Jörgen D. , Bjugn Roger , Wesenberg Gro R. , Fosse Gisle
Published: October 2007

Male, adult Wistar rats were exposed to 500 μg/m3 mercury vapor 6 h per day, 5 days a week for 4 wk. They were subsequently killed by transcardial perfusion. The molars were extracted, demineralized, and embedded in resin before section‐ing. Autometallographic development was performed according to the method of Danscher & Möller‐Madsen. Mercury deposits were found in small amounts in several areas of the pulp, but with larger accumulations of grains in relation to odontoblasts. Mercury also could be seen in odontoblastic processes in the dentin and predentin. Our conclusion is therefore that systemic uptake of mercury vapor leads to accumulation of mercury in the odontoblasts and that the mercury may be transported into the dentin tubules in the odontoblastic process.
Bite force and dentofacial morphology in men with severe dental attrition
Authors: Waltimo Antti , Nysträm Marjatta , Känänen Mauno
Published: October 2007

Patients with severely worn dentition were interviewed and clinically examined, and only those were included who had no or minimal subjective symptoms or clinical signs of craniomandibular disorder. During a 14‐month screening period, only 7 patients fulfilled the inclusion criteria; all were men. Maximal bite force was measured in the molar regions and in the incisal region. Facial morphology was evaluated from lateral cephalometric radiographs, and the form of dental arches from dental casts. Average maximal bite force in the molar region was 911 N and in the incisal region 569 N. The most characteristic findings concerning bite force were the high force levels in the incisal region and an incisal/molar bite‐force ratio of 63%. The facial morphology of the patients was rectangular, with an anteriorly rotated mandible, small anterior face height, and great interincisal angle. Moreover, the form of the maxillary dental arch was more rectangular than normal. The high bite forces of these patients, especially in the incisal area, can probably be explained by strong masticatory muscles and mechanically favorable skull morphology, which in its turn has been influenced by the surrounding muscles.
Dental caries and mutans streptococci in relation to plasma ascorbic acid
Authors: Väänänen Martti K. , Markkanen Heleena A. , Tuovinen Veikko J. , Kullaa Arja M. , Karinpää Anja M. , Luoma Heikki , Kumpusalo Esko A.
Published: October 2007

Ascorbic acid (AA) affects in vitro growth of bacteria and may also act in vivo to decrease caries activity. The aim of this study was to evaluate the possible association of AA level in plasma with number of caries lesions, relative numbers of some species of oral cariogenic flora, and rate of salivary secretion. The caries status and some bacteriologic variables of dentulous adult subjects with a low level of AA in the plasma (≤25 μmol/1; n=75) were compared with those of controls (plasma level ≥50 μmol/1; n=75) matched for age, sex, and number of teeth. For each subject, site‐specific recordings of the presence or absence of plaque, dental caries, fillings, and erosions were recorded clinically by the same dentist in a double‐blind system. The amounts of visible plaque and numbers of decayed tooth surfaces were significantly higher in the low AA group than in the controls. No between‐group differences were found in the number of fillings and the amount of oral bacterial growth. The frequencies of consumption of vegetables, berries, and other fruit were significantly lower in the low AA group than in the controls.
Allergenic potential of two orthodontic bonding materials
Authors: Söhoel Hildur , Gjerdet Nils R. , Hensten‐Pettersen Arne , Ruyter I. Eystein
Published: October 2007

The sensitization potential of two orthodontic bonding materials, one conventional premix product and one nonmix product, was evaluated by a modified guinea pig maximization test. The nonmix product, consisting of a liquid to be applied to the tooth surface and a paste which was placed on the bracket base, caused reaction in 50% of the tested animals. This material should be considered to be a possible cause of allergy in patients or professionals handling it.
Age estimation with the aid of tooth development: a new method based on objective measurements
Authors: Mörnstad Håkan , Staaf Vera , Welander Ulf
Published: October 2007

The common methods of age determination with the aid of teeth have been criticized because they rely on subjective estimations of tooth development, as seen in radiographs, and subsequent comparisons with pictures and descriptions in compiled dental charts. The distribution around an estimated age with these methods is usually more than ±2 yr between the 10th and 90th percentiles. In an attempt to avoid subjective estimations, objective measurements of developing teeth were correlated with subjects' chronologic ages. The structures measured were crown height, apex width, and root length. With the aid of a multiple regression model, a linear relationship between some of these distances and age was shown. The distances which were best correlated with age differed according to sex and age. This method has a 95% C.I. of about ±2 yr around an estimated age. It therefore seems to be more accurate than the earlier methods. Thus, the individual variation in tooth development is of the same order of magnitude, and a better estimation can therefore not be done in children 6–14 yr of age.
Variations among operators in the performance of tunnel preparations in vitro
Authors: Strand Gunhild Vesterhus , Tveit Anne Björg , Espelid Ivar
Published: October 2007

A study was performed to assess the variations among dentists in the performance of tunnel preparations for “caries” removal and cavity design, and to evaluate how these variations are affected by instruction and training. Twenty‐seven dentists with limited clinical experience in performing tunnel preparations participated in the study. They did three partial tunnel preparations each in extracted premolars with standardized, artificial, approximal “carious lesions”. The first preparation was made without instruction, the second after instruction and under supervision, and the last without supervision. After information/supervision, 26% did not manage to do a tunnel preparation without residual caries, indicating that this is not an easy procedure for beginners. The occlusal opening was significantly larger and the width of the remaining approximal wall was significantly smaller in preparations without “residual caries” than in those exhibiting “residual caries”. Visibility appears to be improved by extending the occlusal opening toward the marginal ridge.
Oral lichen planus lesions in contact with amalgam fillings: a clinical, histologic, and immunohistochemical study
Authors: Östman Pär‐Olov , Anneroth Göran , Skoglund Annika
Published: October 2007

Fifty‐one consecutive patients had clinically diagnosed oral lichen planus (OLP) lesions in total or partial contact with amalgam fillings. The clinical features of the OLP lesions were characterized and registered, and biopsies were obtained from each OLP lesion. Histologic and immunohistochemical studies were performed, as well as tests for allergy to dental materials. The clinical diagnosis of OLP corresponded to the World‐Health Organization (WHO) morphologic OLP criteria in 31 (61%) cases. The remaining lesions were histologically diagnosed as mild OLP in 11 (22%) or as benign oral keratosis in nine (17%) cases. The immunohistochemical examination showed a positive reaction to fibrinogen in the basement membrane zone (BMZ) in 10 (20%) patients and to complement C3 in one (2%) patient. No positive reactions in the BMZ were found for IgA, IgG, and IgM. In 17 (33%) patients, an allergic reaction to mercury was found, and candidiasis was diagnosed in 13 (25%) patients. The true nature of OLP‐like lesions in contact with amalgam fillings still remains to be explained. For that matter, we do not know whether OLP is one disease or a number of similar immunologic or other responses to various interacting stimuli. One such stimulus might be mercury from corroding amalgam fillings.
Oral retention of glucose at pharmacologically reduced salivary flow in man
Authors: Hase Jan C. , Birkhed Dowen , Lagerlöf Folke , Thornqvist Elisabeth
Published: October 2007

The aim was to study the influence of mouthrinses with glucose, at concentrations ranging from 1 to 50%, on oral retention at two different locations in the oral cavity. Salivary secretion was reduced in 10 subjects by injection of methylscopolamine nitrate submucosally. The volunteers were randomly assigned to rinse with 10 ml of either 1%, 10%, or 50% glucose solution for 30 s, after which measurements of glucose concentration and parotid salivary secretion rate were performed during a 10‐min period. The results showed higher salivary glucose levels vestibularly than sublingually. The difference in glucose retention between the two locations increased when the salivary flow rate recovered. The relationship between secretion rate and area under the curve for glucose measured sublingually, but not in the vestibule, was bilinear.
Efficacy of chlorhexidine solution with fluoride varnishing in preventing enamel softening by Streptococcus mutans in an artificial mouth
Authors: Sorvari Rita , Spets‐Happonen Satu , Luoma Heikki
Published: October 2007

For study of the enamel‐protective effect of chlorhexidine‐fluoride applications, the labial surfaces of pieces of bovine incisors were treated with 0.2% chlorhexidine gluconate solution, with Duraphat fluoride varnish, or with both of the above agents, while one group was treated with distilled water and one was left as an untreated control. Furthermore, a placebo varnish was used in the chlorhexidine‐ and distilled‐water‐treated groups; all the varnishes were removed after 24 h. The enamel slabs were mounted pairwise in an artificial mouth to form approximal contacts. The teeth were continuously rinsed with a common pool of artificial saliva to which was added 3% sucrose, and which was infected on the first day with Streptococcus mutans, “Ingbritt”. The saliva was renewed daily and the incubation at 37°C lasted for 10 days. The appreciable softening found in the distilled‐water‐ and placebo‐varnish‐treated group tended to be prevented by the chlorhexidine and even more by the fluoride treatment, while the chlorhexidine‐fluoride treatment prevented enamel softening completely. The saliva, infected only on the first day, and renewed daily, tended to become more acidified toward the end of the experimental period, obviously because the fermenting organisms had infected the surfaces of the model and formed plaque‐like coatings on the enamel.
Reduction of cusp deflection resulting from composite polymerization shrinkage, using a light‐transmitting cone
Authors: Ericson Dan , Paulsson Liselotte , Sowiak Hanna , Dérand Tore
Published: October 2007

For investigation of whether the use of a transparent plastic cone (Light‐tip) influenced cusp deflection, as compared with a conventional method (control), the following experiments were performed. Mesiodistocclusal (MOD) cavities were prepared in 10 extracted premolars, and stainless steel pins were placed on the cusps. The cavities were bonded with Scotchbond Multipurpose, and the distance between the pins was measured. Control restorations using P‐50 were placed in three increments, each increment having been polymerized for 40 s. For placing the test restorations, the Light‐tip was fitted to the end of the curing wand and pressed into the resin in the proximal box. and the curing light was turned on. The next increment filled the recess created after the removal of the cone in the resin, and curing was performed with the plastic cone in the occlusal box. The third increment was cured without the cone. Each tooth was used for four restorations. In 16 of 20 cases, a significantly decreased cuspal flexure was found when the cone was used. The flexure decreased 24%, as compared with control.
Clinical and histologic appearance in enamel of primary teeth in relation to neonatal blood ionized calcium values
Authors: Ranggård Lotta , Norén Jörgen G. , Nelson Nina
Published: October 2007

The purpose of this investigation was to study the relationship between low values of blood ionized calcium measured in the first days of life postpartum and the clinical and histologic appearance of enamel of primary teeth. Twenty‐five healthy children selected on the basis of optimality with known blood values of ionized calcium from the first days of life participated in a dental examination at the age of 5 yr. Twenty‐four of the children contributed one exfoliated tooth each, which was histologically examined. The infants had lower mean values of ionized blood calcium on days 1 and 3 than day 5 postpartum. Thirteen of the 25 children had enamel aberrations, mainly on one tooth each. The histologic examination showed normal overall enamel morphology. The neonatal line was present in all teeth, and these lines were mostly thin. The registered findings about the enamel morphology could not, in any case, be correlated with the measured values of neonatal blood ionized calcium.
Effect of buccal administration of a lactose‐containing nitroglycerin tablet (Suscard) on plaque pH
Authors: Lingström Peter , Birkhed Dowen
Published: October 2007

The aim of this study was to monitor pH in 2‐day‐old dental plaque after administration of a long‐acting, lactose‐containing nitroglycerin tablet (Suscard). The tablet was placed under the lip of the maxilla. This was done both in two older subjects suffering from heart problems and in 10 younger, healthy subjects. In the latter group, a sucrose‐containing lozenge was used as a control. The influence of a 5‐wk period of daily use of Suscard (in the two elderly subjects) and the effect of normal oral hygiene procedures (in the 10 younger subjects) on the pH response was also studied. Plaque pH was measured in situ up to 1 h, at five different approximal sites in the front region of the maxilla by the microtouch method. The Suscard tablet resulted in a fall in plaque pH in both groups when teeth had not been brushed for 2 days. The lowest pH was recorded at the sites close to where the tablet had been placed. The most attenuated pH drop was found in the two older subjects, who showed a mean minimum pH of 5.7, as compared with 6.2 for the younger subjects. No further increase in the pH fall from Suscard was seen after the 5‐wk period in the two patients with heart problems. In the 10 younger healthy subjects, the most pronounced pH decrease was registered after administration of the sucrose‐containing lozenge. The pH drop for Suscard was not significant when normal oral hygiene procedures preceded the test. To conclude, this study showed that a long‐acting, lactose‐containing nitroglycerin tablet may be highly cariogenic. However, if good oral hygiene is maintained, the pH drop in plaque can be reduced to a minimum.