bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of fluoride mouthrinsing on caries lesion development in shark enamel: an in situ caries model study
Authors: ÖGAARD BJØORN , RÖLLA GUNNAR , DIJKMAN TON , RUBEN JAN , ARENDS JOOP
Published: October 2007

Abstract— Shark enamel consists of nearly pure fluorapatite and has been shown to demineralize in an in situ caries model. The present study was conducted to investigate whether additional fluoride supplementation in the form of mouthrinsing would inhibit lesion development in shark enamel. The study slabs of shark enamel were mounted in dental appliances. Six individuals wore the appliances while rinsing daily with a neutral 0.2% NaF solution for 4 wk. The specimens were analyzed by means of quantitative microradiography, and the data compared with a previous study using untreated shark enamel and the same participants. It was found that fluoride rinsing did not measurably inhibit enamel demineralization in 4 wk. Scanning electron microradiographs showed that calcium fluoride‐like material was not formed on shark enamel after neutral fluoride treatment, supporting a previous study. The present study indicates, therefore, that formation of a calcium fluoride‐like material on the enamel surface may be essential for the cariostatic effect of topical agents.
Comparative antibacterial effects of chlorhexidine and stannous fluoride‐amine fluoride containing dental gels against salivary mutans streptococci
Authors: OSTELA ILKKA , KARHUVAARA LAURA , TENOVUO JORMA
Published: October 2007

Abstract— Forty‐five young adults were divided into three groups of equal size and given a professional toothcleaning (3 times during 1 wk) with dental gels containing either chlorhexidine (CHX, 1%), or a SnF2‐amine fluoride (AmF) combination (F− content 1.20%). The control group received toothcleaning with a placebo gel. The study was done double blind. The number of salivary mutans streptococci was monitored for 11 wk after the gel treatment using both mitis‐salivarius‐bacitracin agar plates and the chairside method based on the adhesion of mutans streptococci on plastic strips (DentocuIt‐SM Strip mutans). Professional toothcleaning with a CHX gel was clearly most effective (P< 0.001) but the baseline levels of streptococci returned in 11 wk. SnF2‐AmF gel also reduced significantly (P< 0.001) mutans streptococci but recolonization occurred already in 7 wk. Placebo gel, i.e. professional toothcleaning as such, did not show any statistically significant effect on the numbers of salivary mutans streptococci. None of the treatments affected the levels of lactobacilli or the total aerobic flora in saliva samples. Professional toothcleaning with a CHX gel, or with a SnF2,‐AmF gel, can be regarded as an alternative to the commonly used, but more patience demanding, application of gel in mouth trays at home for individuals with high caries activity.
Ontogeny of class II antigen expressing cells in rat incisor pulp
Authors: JONTELL MATS , JIANG WUHAN , BERGENHOLTZ GUNNAR
Published: October 2007

Abstract— Class II antigen expressing cells are generally associated with the early phase of the immune response. Dendritic cells and macrophages expressing these cell surface antigens have recently been demonstrated and characterized in the dental pulp. The present study was undertaken to determine when the pulp receives its immunologic defense potential by examining the temporal appearance of class II antigen expressing cells in the rat incisor pulp. Pulp tissue specimens obtained at various time periods from a gestational age of 16 days to 14 wk after birth were examined by immunohistochemistry using O x 6 as a primary antibody and the ABC‐technique. Comparisons were made with tissue samples from the spleen, intestine, skin and oral mucosa. At birth, all tissues, except for the pulp, presented cells expressing class II antigen with a dendritic appearance in a number and orientation resembling the mature tissue. A complete distribution of these cells was not seen in the dental pulp until 7 weeks following birth. Data show that the dental pulp acquires its ultimate structural arrangement of immune cells later than other tissues.
Release of corrosion products from amalgam in phosphate containing solutions
Authors: MOBERG LARS‐ERIK , JOHANSSON CHRISTINA
Published: October 2007

Abstract— The effect of phosphate concentration on corrosion was compared for two types of amalgam: a conventional alloy (ANA 68) and a high‐Cu admixed alloy (Dispersalloy). The test specimens were stored for 4 months in electrolytes containing 85 mM NaCl and 85 mM NaCl with 2.5, 10, or 100 mM phosphate buffer respectively. The solutions were renewed each month and analyzed for Cu, Zn, Sn, Hg, and Ag in an atomic absorption spectrophotometer. The surfaces and cross‐sections of the specimens were studied in a scanning electron microscope (SEM) with an energy dispersive detector (EDAX). The corrosion products, mainly Sn‐compounds, at the surface of the amalgams were less in the solutions containing high concentrations of phosphate. In cross‐section subsurface corrosion of the high‐Cu amalgam was observed especially in specimens immersed in the NaCl solution without phosphate. The conventional amalgam showed surface corrosion only. The decrease in release of elements with time from the conventional amalgam in all the experimental solutions might indicate passivation. For the high‐Cu amalgam the release of elements increased with time, except for Cu and Sn in the solution with 100 mM phosphate, indicating that phosphate inhibits corrosion of the Cu‐Sn‐phases. Release of corrosion products from the high‐Cu amalgam was more dependent on the presence of phosphate than the conventional amalgam.
Marginal adaptation of a restorative resin polymerized at reduced rate
Authors: UNO SHIGERU , ASMUSSEN ERIK
Published: October 2007

Abstract— The aim of this study was to investigate the effect of reduced rate of polymerization on the marginal adaptation of a composite resin inserted in dentin cavities treated with a simplified Gluma system. The effect on bonding strength to dentin and compressive strength was also investigated. The light intensity of the polymerization unit was lowered by the use of a transformer, and thus the rate of polymerization of the composite resin. When the resin was irradiated for 30 s at 110 V followed by 30 s at 220 V, the marginal adaptation was significantly improved. This condition resulted in acceptable values of bonding strength to dentin and diametral compressive strength. It is suggested that the reduced rate of polymerization may allow for increased flow of the material, decreasing the contraction stress in the filling.
Experimental erosion of dentin
Authors: MEURMAN JUKKA H. , DRYSDALE TAMSIN , FRANK ROBERT M.
Published: October 2007

Abstract— Experimental erosion in human dentin was investigated with scanning electron microscopy. Erosion was caused by solutions containing either 0.030 mekV/g malic acid (pH 3.4), 0.034 mekV/g phosphoric acid (pH 2.6), or 0.038 mekV/g citric acid (pH 2.8). Test specimens prepared from the coronal parts of erupted third molars were immersed in the solutions from 30 s to 60 min. When compared with controls, exposure of dentin tubules was observed in all the specimens already after 30 s immersion, irrespective of the acid used. Mineral loss was seen to progress at the interface between peritubular and intertubular dentin in specimens immersed for 60 s in the acidic solutions. Longer times of immersion resulted in hollowing of the tubular openings by complete destruction of the peritubular dentin. Surface roughness and porosities were seen also at the intertubular areas. Although based on a simplified study model, our results may explain why so many patients with erosions suffer from painful sensitivity of their teeth: the acids causing erosion can expose inner dentin structures to outer stimuli by significant enlargement of the dentinal tubules.
Irradiation of human dental tissues with CO2‐, Nd:YAG‐, and CO2‐Nd:YAG combination laser
Authors: RAUHAMAA‐MÄKINEN RAIJA , MEURMAN JUKKA H. , LUOMANEN MARITA , TORKKO HEINI , VIHERKOSKI ESA , PAUNIO ILKKA
Published: October 2007

Abstract— Extracted third molars were used to study the effect of Nd:YAG laser irradiation combined with CO2 laser beam on dental hard tissues. The specimens were studied with SEM after lasing and the size of the impact areas and beam penetration into enamel and dentin were planimetrically analyzed. High‐energy CO2 laser (e.g. 10 s irradiation with 10 W output energy) penetrated all enamel and dentin. The simultaneous addition of Nd:YAG irradiation to the CO2 beam was found to increase the effect of CO2 laser, while Nd:YAG irradiation alone, used with equivalent energy densities, did not cause any effect on enamel surface. Thus, Nd:YAG laser was found to potentiate statistically significantly the effect of CO2 irradiation, but the morphologic alterations on dental hard tissues, such as crater formation at the beam focus site, appeared to be due to CO2 irradiation alone.
Concepts of health and disease and caries prediction: a literature review
Authors: ERIKSEN HARALD M. , BJERTNESS ESPEN
Published: October 2007

Abstract— Biomedical determinants of dental caries have been more extensively investigated than psychosocial factors and their impact on caries prevalence and incidence seems to be greater. However, a majority of these investigations relate to children and adolescents. An implementation of social and psychologic variables may be more relevant regarding dental caries in adults. In addition, a multidisciplinary approach might improve our understanding of dental caries as a multifactorial disease and bridge the gap between a biomedical concept and a more holistic approach to dental health.
Oral implantation in man of Streptococcus mutans in relation to salivary IgA activity
Authors: OLSSON JAN , SVANBERG MONA
Published: October 2007

Abstract— Oral implantations of and salivary IgA activity against a freshly isolated Streptococcus mutans strain and a repeatedly subcultured variant strain were studied in 20 subjects. The variant strain was eliminated at a higher rate than the parent strain. Both strains were eliminated at a lower rate in subjects with high oral levels of indigenous mutans streptococci than in subjects with low levels of these microorganisms. Subjects with high respectively low IgA activity against the parent strain also had high respectively low IgA activity against the variant strain (P<0.01). The correlation between IgA activity and clearance rate of implanted bacteria was not statistically significant. However, following both implantations, median values of IgA activity were consistently higher in subjects who had eliminated the implanted strain than in subjects who had not.
Effect of repeated sampling and prestimulation on saliva buffer capacity and flow rate values in children
Authors: LE BELL YRSA , SÖDERLING EVA , KARJALAINEN SÁRA
Published: October 2007

Abstract— Great variations reported in the frequency distribution of buffer capacity values may partly be due to methodological differences in saliva sampling. In this study we wanted to see to what extent these variations are due to repetition and prestimulation. 9‐yr‐old schoolchildren (n: 41, 23 girls and 18 boys), who had never had saliva samples taken before, participated in the present study. The repetition tests were carried out between 9 and 11 a.m. on three subsequent days. The effect of prestimulation was tested 4 days later with the same subjects. The buffer capacity of the samples was determined electrometrically immediately after sampling using the commercial Dentobuff‐test. The intraindividual analysis revealed a significant increase in flow rate but not in buffer capacity along with repetition of the sampling. The analysis further showed that the buffer capacity of children accustomed to saliva sampling increased significantly through prestimulation of 1 min. The use of prestimulation resulted in substantial changes also in the frequency distribution of the buffer capacity values. Our results emphasize the importance of proper sampling conditions in saliva collection when screening children for high caries risk.
Immune‐inflammatory cells in recurrent oral ulcers (ROU)
Authors: HÄYRINEN‐IMMONEN RITVA , NORDSTRÖM DAN , MALMSTRÖM MARIA , HIETANEN JARKKO , KONTTINEN YRJÖ T.
Published: October 2007

Abstract— Tissue lesions from eight patients with recurrent oral ulcers (ROU) were subjected to detailed immunohistopathologic studies. In five patients, a specimen of an unaffected area from the opposite site was obtained. The main inflammatory cells in situ were CD3 positive T lymphocytes, with CD4 cells forming approximately half (range 30‐60%) and CD8 cells 20% (range 10‐30%) of all cells. CD19 positive B lymphocytes formed 5‐12% of all cells. Furthermore, 45% (range 15‐65%) of all lymphoid cells had signs of previous antigenous contact and had helper/inducer CDw29 type. Suppressor/inducer CD45R cells formed only about 20% (range 7‐50%) of all cells. Although this observation suggests involvement of antigen as a causative and/or triggering stimulus, elements of a non‐specific inflammatory response were observed as well. Endogenous peroxidase‐positive neutrophils were present at the ulcer site, and were occasionally observed intravascularly and in th extracellular matrix in areas characterized by inflammatory mononuclear cell infiltrates. Although the proportion of endogenous peroxidase‐positive, recently recruited monocytes was low, CD11b and nonspecific esterase‐positive mature tissue macrophages formed about 14% (range 5‐35%) of all inflammatory cells in situ, particularly at the periphery of the lymphoid cell infiltrates. Mast cells were also observed in all samples studied, forming 2‐5% of inflammatory cells in the richly vascularized connective tissue beneath the basement membrane. In the specimens from clinically unaffected areas, inflammatory cells were rare. Our observations stress the multifaceted nature and participation of multiple effector systems in the local tissue pathogenesis of ROU.
Fracture toughness measurements of some dental core ceramics: a methodologic study
Authors: KVAM KETIL , HERÖ HÅKON , ÖILO GUDBRAND
Published: October 2007

Abstract— Fracture toughness is regarded as an important property of dental ceramics. The most widely used methods for fracture toughness (KIc) determination are based on assessment of cracks created by hardness indentations. Different formulas have been developed for KIc calculations and all these methods and formulas include empirical factors based on pure ceramics, i.e. non‐composite ceramics. These factors may, however, vary for a specified method for materials with different and complex structure. An important question is whether the various proposed methods and formulas lead to approximately the same numerical KIc values or at least to the same ranking of materials. The aim of this work was to compare two indentation methods and various formulas for calculation of KIc values when used on four commercial composite dental ceramics. The two applied methods and the different formulas showed substantial differences in the obtained values for one and the same material and a different ranking of various materials. It is unknown which method gives the most correct KIc values for these ceramic materials.
Incidence and prediction of filled teeth from 12 to 18 years of age in a district in Norway
Authors: ÖGAARD BJØRN , RÖSLER MAREK
Published: October 2007

Abstract – The present study investigated whether the incidence or prevalence of filled teeth/ approximal surfaces at one age could be predictive for the incidence in another period or for the prevalence at the age of 18. The study was conducted in 12–18‐yr‐olds in Norway. Regression analysis showed that the best prognosis for subsequent incidence of filled teeth/approximal surfaces could be made at the age of 15. By using regression analysis or discriminant analysis it was possible at the age of 15 to predict with high accuracy those who would acquire more fillings than the median at the age of 18. Discriminant analysis with one predictor variable is suggested for clinical use. The variable that discriminated best between above and below median number of new fillings in the period 15 18 yr was untreated lesions in the inner half of the enamel in the approximal surfaces of premolars and molars at the age of 15. From the use of simple prediction tools, it was concluded that individuals at the age of 15 with a low prevalence of filled teeth/filled approximal surfaces and without untreated approximal lesions would be subjected to a low incidence of new fillings until the age of 18.
Phagocytosis and virulence of different strains of Porphyromonas gingivalis
Authors: SUNDQVIST GÖRAN , FIGDOR DAVID , HÄNSTRÖM LENNART , SÖRLIN STIG , SANDSTRÖM GUNNAR
Published: October 2007

Abstract – In this study 17 strains of Porphyromonas gingivalis, both reference and clinical isolates, were investigated for their in vitro interaction with human polymorphonuclear leukocytes, hydrophobicity, density, and virulence in a mouse model. The results of the phagocytosis, hydrophobicity, and density experiments showed that P. gingivalis strains could be divided into two distinct groups. One group of strains were readily attached and phagocytosed when exposed to the leukocytes. These bacteria were hydrophobic and had a higher buoyant density than the other group, which were poorly phagocytosed, had a low buoyant density, and were hydrophilic. This latter group also exhibited an extracellular meshwork resembling a glycocalyx when examined by electron microscopy. There were also significant differences between strains in the mouse pathogenicity model. Two strains caused an invasive, spreading infection compared with the other 15 strains which produced small, localized abscesses. There was no clear correlation between the results of the phagocytosis assay and the virulence of the bacteria when injected subcutaneously in mice. Resistance to phagocytosis may be important for survival of these bacteria, but it does not in itself imply the ability to cause damage to the host.
Effect of immediate calcium hydroxide treatment and permanent root‐filling on periodontal healing in contaminated replanted teeth
Authors: LENGHEDEN ANNELIE , BLOMLOF LEIF , EINDSKOG SVEN
Published: October 2007

Abstract – The effect of immediate permanent root‐filling and immediate intracanal calcium hydroxide treatment on experimentally contaminated and necrotized periodontal membranes (PDM) in avulsed and subsequently replanted monkey teeth was studied. Almost the entire root surface in the non‐endodontically treated control teeth were covered with inflammatory resorp‐tion, A significant shift towards ankylosis not associated with root resorption (> 80% of the total root surface area) was noted following calcium hydroxide treatment. About two thirds of the root surfaces from the teeth with permanent root fillings showed surface resorptions or ankylosis preceded by root resorption. The root surface area which would have been covered by inffammatory resorption, unless endodontic treatment had been implemented, were instead predominantly covered by either surface resorption (permanent root filling) or ankylosis (calcium hydroxide treatment), Ankylosis compared with surface resorption may in the long term lead to progressive loss of root substance due to replacement resorption. It was concluded that calcium hydroxide may be an excellent initial intracanal treatment in teeth with healthy PDM, but care should be taken not to risk unnecessary development of ankylosis by prolonged treatment of teeth with compromised PDM.
Performance for obtaining maximal gain from a program for digital subtraction radiography
Authors: AAGAARD ESBEN , DONSLUND CLAUS , WENZEL ANN , SEWERIN IB
Published: October 2007

Abstract – The aim of this study was to evaluate the effect on subtraction image quality of number of a) gray shades sampled during camera recording, and b) reference points positioned in the two images to be subtracted. Intraoral radiographs were obtained in each of 12 patients, one at 0° and one at 15° horizontal angulation in a standardized recording procedure. The radiographs were videorecorded twice sampling 1) 160–180 and 2) 200–220 shades of gray. The 0° radiographic image was digitally copied. Subtractions were performed between the identical (0°/0°) and the non‐identical (0°/15°) radiographs from both gray shade samples after positioning 5, 10, 15, and 20 reference points, respectively, in each of the images to be subtracted. The standard deviation in the subtraction image histogram was used as the test parameter for image quality. No differences existed between image quality obtained from the radiographs sampled using 160–180 and 200–220 shades of gray (P>0.05). The standard deviation fell continuously, the more reference points were positioned in the images. For the 0°/0° images the difference was statistically significant between the 5 and 10 point images (F= 0.045) while for the 0°/15° images differences existed between 5 and 10 point images (P = 0.077) and the 10 and 15 point images (P= 0.048). The precision of reference point positioning as evaluated in the two identical images was satisfactory, the divergence being on average 1.4 pixels. The conclusion from cost/benefit analysis was that, when working with subtraction radiography, time should not be spent adjusting camera diaphragm to utilize the full range of gray shades but rather on a precise positioning of 10–15 reference points in the images to be subtracted.
Variables influencing the repair strength of dental composites
Authors: SÖDERHOLM KARL‐JOHAN M. , ROBERTS MARION J.
Published: October 2007

Abstract – Differences in the flexural strength of composites (P‐30) repaired with four different adhesive techniques were determined and compared to the flexural strength of unrepaired specimens. Besides investigating the effects of differences in repair methods, both the effect of composite age at repair time and the effect of water storage on flexural strength were evaluated. No significant differences were found between specimens which had been stored for different times (1 or 60 days) before they were repaired. All specimens, including the unrepaired ones, became weaker with time in water. After both 90 and 360 days at 37°C in water, the strength of the repaired specimens ranged between 25 and 50% of the strength of the unrepaired specimens. The weakest group was the one which had been repaired after acid etching, water rinsing, and air drying only.
Chemical analysis and scanning electron microscopy of acquired pellicle formed in vivo on stannous fluoride treated enamel
Authors: RYKKE MORTEN , ELLINGSEN JAN EIRIK , SÖNJU TORLEIF
Published: October 2007

Abstract – Stannous fluoride (SnF2) has been shown to be an effective caries preventive agent. After topical treatment of enamel surfaces, two reaction products have been demonstrated to precipitate on the surfaces, a larger type of globules, probably a calcium fluoride like product, and a smaller type of globules, probably a tin phosphate. The aim of the present study was to examine the amino acid composition and the formation of the acquired pellicle on SnF2‐treated enamel in vivo. The chemical composition was examined by amino acid analysis of pellicle material collected in vivo from SnF2‐treated enamel surfaces. Pellicle formation was examined by scanning electron microscopy on SnF2‐treated enamel fragments carried in the mouth for 2 h. The results showed that pellicle material was formed in abundant amounts and covered the globular surfaces following the SnF2 treatment. The chemical analyses showed amino acid profiles with high content of acidic and neutral amino acids. The profiles were different from known amino acid profiles obtained from analyses of pellicle material collected from untreated enamel surfaces.
Dental fear treatment: comparison of a video training procedure and clinical rehearsals
Authors: MOORE ROD
Published: October 2007

Abstract – Two types of fear desensitization, video training, and clinical rehearsals, were evaluated using psychometric tests, behavioral measures, and interviews for a group of 68 dental fear patients with high and low general trait anxiety. After treatment, a visual analogue scale (VAS) also tested the degree of perceived anxiety before going off to an unknown dentist. Results indicated no significant differences in dental fear reduction effects of the two types of desensitization. However, both treatments showed significant and meaningful effects when compared with a group of 75 dental fear patients on a waiting list who were also tested once at the beginning of the waiting period and again after 6 months. Only high general anxiety subjects resisted desensitization and failed standardized dental treatment tests. Exit interviews revealed that both groups named securing/accepting personnel, conversations about their fears and relaxation, in that order, as the most important factors in their dental fear reduction. Psychometric trust scores confirmed this. VAS scores showed a significant increase in fear level about the next dentist, also indicating trust as a major factor in reducing dental fear. Suggestions are made about which patient conditions can affect the choice of either of these training methods.
Area ratio effects on metal ion release from amalgam in contact with gold
Authors: JOHANSSON CHRISTINA , MOBERG LARS‐ERIK
Published: October 2007

Abstract – The effect of area ratio, chloride concentration and brushing on amalgam in contact with gold was studied by measuring the amounts of elements released in the electrolyte. A type III gold alloy was stored for 4 months in contact with a conventional amalgam, area relations 6/1 and 6/3, in an electrolyte containing 85 mM NaCl with 10 mM phosphate buffer. A specimen with area relation 6/1 was also stored in a 10 mM NaCl solution with 10 mM phosphate buffer. The solutions were renewed each month and analyzed for Cu, Zn, Sn, Hg, and Ag in an atomic absorption spectrophotometer. Cross‐sections of the amalgams were studied in a scanning electron microscope. The tendency for Sn and Cu to be released from the amalgam was greater than for the other elements. The Sn‐release probably mainly originated from surface corrosion and Cu‐release from subsurface corrosion. A stronger galvanic influence enhanced only the release of Cu, and to a less extent Zn. The subsurface corrosion of the amalgam and increasing release of Cu was, in contrast to the other elements, largely dependent on a high chloride concentration in the electrolyte. Light brushing of the specimens had no effect on the amounts of elements released.
Effect of human saliva on surface degradation of composite resins
Authors: LARSEN INGE BIRK , MUNKSGAARD ERIK GHRISTIAN
Published: October 2007

Abstract – The amount of methacrylic acid produced by incubation of the dimethacrylate ester TEGDMA in human whole saliva was measured. The conversion rate of TEGDMA was determined in stimulated saliva from dental students and in unstimulated saliva from both dental students and patients. The differences in mean conversion rate measured in the three groups were not statistically significant (P= 0.346). The mean conversion rate ± SD for all saliva samples was 4.54 ± 3.24 μmol MAA/L. h. The surface of BISGMA/TEGDMA‐polymer specimens treated with porcine liver esterase in activities equivalent to those found in human saliva exhibited a lower Wallace microhardness than the surface of untreated specimens. Polymer specimens incubated in human saliva exhibited a similar reduction in the microhardness. The results demonstrated that enzymes in human saliva are capable of softening the surface of dimethaerylate polymers presumably by inducing a hydrolysis of methacrylate ester bonds. The mechanical removal of a surface layer softened by hydrolases will expose a new surface layer to enzymatic attack. The enzymatic softening may thus contribute to the in vivo wear of composite restorations.
Root canals in one‐rooted maxillary second molars
Authors: Carlsen Ole , Alexandersen Verner , Heitmann Thomas , Jakobsen Parly
Published: October 2007

The Royal Dental College, Copenhagen, houses an extensive collection of human teeth extracted in Denmark. The collection currently contains 104 one‐rooted, permanent maxillary second molars. The root complex on these teeth was sectioned at the junction between the coronal and the apical halves, i.e. mid‐root, and at the junction between the middle and the apical thirds, i.e. apically. Using a stereomicroscope we then registered, mid‐root and apically, the following variables: canal number, canal position, and canal cross‐section. Mid‐root there was 1 centrally located root canal in 25.96% of the teeth examined; 2 canals were observed either mesially and distofacially, mesiofacially and distally, or facially and lingually in 34.62%; 3 canals positioned mesiofacially, distofacially, and lingually were found in 39.42%. At the same level 63.51% of the canal cross‐sections were non‐circular, whereas 36.49% of the canals had a circular cross‐section image. The non‐circular canal cross‐sections could more specifically be characterized as C‐shaped, Y‐shaped, hourglass‐shaped or the root canal had a greater faciolingual than mesiodistal extension or, respectively, a greater mesiodistal than faciolingual extension. Apically there was 1 centrally located root canal in 35.58%; 2 canals were observed with a position either mesially and distofacially, mesiofacially and distally, or facially and lingually in 37.49%; 3 canals located mesiofacially, distofacially, and lingually were found in 26.92%. At the apical level, 64.32%. of the root canal cross‐sections were non‐circular, whereas 35.68% of the canals showed a circular cross‐section. The results presented here are aimed at: clinical dentists, endodontists, and dental morphologists.
Effects of phosphonoformic acid and 1‐hydroxyethylidene‐1, 1‐bisphosphonate (HEBP) on distribution of tetracycline in the developing rat molar
Authors: Fouda Nasser , Kut Idil Alatli , Hammarström Lars
Published: October 2007

Tetracycline was used as a marker to study the effect of phosphonoformic acid and l‐hydroxyethylidene‐1, 1‐bisphosphonate (HEBP) on the mineralization of the developing dental hard tissues. Groups of young rats were given a single subcutaneous injection of tetracycline and at the same time were injected with a single dose of either phosphonoformic acid or HEBP (10 mg P/kg b.w.). Alternatively, rats were injected with the tetracycline after different time intervals from the phosphonate injection. Rats were sacrificed at intervals ranging from 1 to 4 days. Frozen‐sections were obtained at the level of the maxillary first molar and prepared for light and fluorescence microscopy. The results of the present study indicate that the distribution pattern of tetracycline in the developing dental hard tissues is greatly affected by the pathologic changes induced by phosphonoformic acid and HEBP. Both drugs caused similar changes in the pattern of tetracycline uptake in the developing enamel. There seems to be a direct relation between the presence of developmental defects of enamel and the degree of discoloration induced by tetracycline. Aberrations in the mineralization of dentin were caused only by HEBP. As demonstrated by this study, HEBP is capable of inducing a provisional inhibitory effect on dentin mineralization.
Oral function in patients wearing fixed prosthesis on osseointegrated implants in the maxilla: 3‐year follow‐up study
Authors: Lundqvist Sture , Haraldson Torgny
Published: October 2007

Seventeen consecutive selected patients rehabilitated by means of a full maxillary bridge on osseointegrated implants ad modem Brånemark were evaluated over a 3‐yr period. Besides a subjective evaluation by means of a questionnaire an examination of the occlusal relationship, chewing force, chewing efficiency and interocclusal threshold level was performed before, immediately after, 3–6 months after, and finally 3 yr after bridge installation. All subjects were very pleased with the oral rehabilitation. The chewing force and the chewing efficiency development increased over time, while the threshold level for interocclusal detection remained unchanged. The clinical dysfunction index according to Helkimo indicated that there was no marked change in signs of dysfunction of the patients' masticatory systems during the observation period. From the present longitudinal investigation one can conclude that the replacement of a full maxillary denture with a fixed prosthesis on osseointegrated implants, facing a natural dentition or an osseointegrated implant supported bridge in the opposite jaw, leads to a progressive increase of chewing efficiency and chewing force, and a constant subjective improvement of jaw function, while no masticatory dysfunction seems to occur during the observation period.
Dummy‐ and finger‐sucking habits in young Swedish and Norwegian children
Authors: Larsson Erik , Ögaard Björn , Lindsten Rune
Published: October 2007

The prevalence of dummy‐ and finger‐sucking habits in 3‐yr‐old children was registered in four different areas of Sweden and Norway. In Norway 245 children were examined and in Sweden 171 children. The Swedish children were more prone to develop a dummy‐sucking habit as well as to prolong it. About 10–19% of the children in the different groups become finger‐suckers. Very few of these finger‐suckers had stopped sucking at 3 yr of age. The highest rate of non‐suckers was found among the children from Karasjok/Kautokeino in northern Norway, who were mainly of Lappish origin.
Effect of temperature and duration of post‐cure on selected mechanical properties of resin composites containing carboxylic anhydrides
Authors: Peutzfeldt Anne , Asmussen Erik
Published: October 2007

Resin composites containing carboxylic anhydrides have recently been formulated, for use as inlay materials. To optimize the post‐cure, the present study measured the effect of post‐cure temperature and duration on four mechanical properties of anhydride‐containing resin composites. Temperatures were varied between 37°C and 225°C, and durations were varied between 0 and 24 h. An optimum in strength and stiffness was found when post‐cure temperatures of 125–150°C were used. Strength and stiffness were found to increase with increasing duration of post‐cure. Due to discoloration of the resin composites when post‐curing for 6 or 24 h, a post‐cure period of 1 h was preferred.
Dental caries and Streptococcus mutans in a rural child population in Iceland
Authors: Saemundsson Sigurdur Rúnar , Bergmann Halldóra , Magnúsdóttir Margrét O. , Holbrook W. Peter
Published: October 2007

In spite of having a high socioeconomic standing, in Iceland caries prevalence has remained stubbornly high. This study reports findings from a mixed fishing and farming community in East Iceland that has traditionally been associated with the highest prevalence of caries. A total of 188 children aged 3–16 yr (96.4% of residents of that age group) were examined. At 6 yr the mean dmfs score was 4.1, DMFS 0 and 48% were caries‐free. The mean DMFS score at 12 yr was 4.7 and 22.6% remained caries‐free but at 16 yr the DMFS score was 11.6 and no children were caries‐free. Caries was unevenly distributed within each age group and was more prevalent among residents of the fishing town than the surrounding farming district. In a pilot study conducted in 1989 mean counts of Streptococcus mutans for children aged 4–7 yr were 2.6 × 105 cfu/ml and declined to 4.6 × 104 cfu/ml in 1990 after a program of chlorhexidine brushing had been added to the routine caries preventive measures adopted in this community. It may therefore be possible to screen Icelandic children for caries risk and apply preventive measures to those demonstrated to be most in need.
Caries and saliva in 12–18‐year‐old diabetics and controls
Authors: Swanljung Outi , Meurman Jukka H. , Torkko Heini , Sandholm Leena , Kaprio Eero , Mäenpää Jorma
Published: October 2007

Eighty‐five 12–18‐yr‐old adolescents suffering from insulin‐dependent diabetes mellitus (IDDM) and their healthy age‐ and sex‐matched controls were investigated with respect to dental caries, salivary flow rate, pH and buffering capacity of saliva, counts for lactobacilli and mutans streptococci, and salivary glucose content. The diabetics had their disease well controlled according to the HbA1 levels. The results showed no statistically significant difference between diabetics and controls in DMF and DMFS indexes and the number of initial caries lesions. Mean number of initial caries lesions was 3.2 in diabetics, 2.3 in controls. Mean stimulated salivary flow rate was 1.2 ml/min in the patients, 1.4 ml/min in the controls. The pH and buffering capacity values were 7.3 and 4.8 in the patients, 7.4 and 5.1 in the controls, respectively. High counts of mutans streptococci (> 106 CFU/ml) and lactobacilli (> 105 CFU/ml) were observed more often, but not significantly so, among the patients than in the controls. The mean concentration of glucose in saliva was 10.3 μg/ml in the patients, 9.7 lμg/ml in the controls. Thus, if the patients' IDDM is well controlled, their salivary and caries data does not differ from that of healthy controls.
Tobacco smoking, a factor in tooth loss in Reykjavík, Iceland
Authors: Ragnarsson Einar , Eliasson Sigfús Thor , Olafsson Sigurjón H.
Published: October 2007

A random sample of 1023 people 52–79 yr of age out of a group participating in a longitudinal study at the Heart Preventive Clinic of the Icelandic Heart Association in Reykjavík, Iceland, was examined. The examination was carried out in 1985–7. The results on the number of remaining teeth and total edentulousness were compared to information regarding smoking habits and social status. Total edentulousness was more common among women. Total and partial edentulousness was more frequent in the lower “employment” classes while no statistical difference was found for smoking in this respect. This, however, did not affect the significance of tobacco smoking as a factor in the loss of teeth. In general smokers had fewer remaining teeth and were more often edentulous than ex‐smokers, smoking time not considered, who again suffered more tooth loss than those who had never smoked. Therefore it is concluded that tobacco smoking may be a‐major single independent risk factor in the loss of teeth.
Influence of masticatory muscle function on craniofacial growth in hypocalcemic rats
Authors: Kiliaridis Stavros , Engström Christer , Chavez L. Maria E.
Published: October 2007

The aim of this study was to investigate the influence of low masticatory function on the craniofacial growth pattern in rats fed a low calcium and vitamin D deficient diet. Male growing rats were divided randomly into three groups: the Normal Hard Diet group, the Deficient Soft Diet group, and the Deficient Hard Diet Group. Lateral cephalograms were taken at days 0, 14 and at the end of the experiment, day 28. The craniofacial growth pattern was altered by an upwards rotation of the viscerocranium (orthocranialization) in the Deficient groups and, the total skull lengths were shorter than in the Normal Hard Diet group. The viscerocranium in the Deficient Soft Diet group was in an even more orthocranial position than in the Deficient Hard Diet group and the anlegonial notch was shallower. This indicates that an induced disturbance of craniofacial morphology due to metabolic bone disease during growth is accentuated by a low masticatory function.
Longitudinal study of stimulated whole saliva in an elderly population
Authors: Österberg Tor , Birkhed Dowen , Johansson Cecilia , Svanborg Alvar
Published: October 2007

The aim of this investigation, which is part of the longitudinal gerontologic population study in Gothenburg (H‐70), was to examine the effect of aging on salivary flow. Three 70‐yr‐old cohorts, born in 1901/02, 1906/07, and 1911/12, were studied both cross‐sectionally and longitudinally. Representative subsamples (n= 931) were followed up to 82 yr in the first and up to 75 yr in the second and third cohorts. Whole saliva secretion was stimulated by paraffin wax chewing for 5 min and all sampling was carried out in the morning after an overnight fast. The mean secretion rate was 1.24 for men and 0.94 ml/min for women at the age of 70 (all cohorts pooled). The percentage values for extremely low secretion rate (<0.2 ml/min) were 2 and 6%, respectively. Neither the crosssectional nor the longitudinal comparison showed any decrease in secretion rate on a group basis either in the age interval 70–82 yr in the first or between 70 and 75 yr in the other two cohorts. However, an increased prevalence of complaints of mouth dryness was found, especially among women. The main conclusion from this study is that there is no decline on a population basis in paraffin‐wax‐stimulated salivary flow with increasing age.
Factors influencing mercury evaporation rate from dental amalgam fillings
Authors: Björkman Lars , Lind Birger
Published: October 2007

Factors influencing mercury evaporation from dental amalgam fillings were studied in 11 volunteers. Air was drawn from the oral cavity for 1 min and continuously analyzed with a mercury detector. In six volunteers the median unstimulated evaporation rate was 0.1 ng Hg/s, range 0.09–1.3 ng Hg/s. After chewing gum for 5 min the highest evaporation rate was 2.7 ng Hg/s. Chewing paraffin wax gave only a small increase in evaporation rate. Changes in airflow rates between 1.5 and 2.5 1/min during the 1 min sampling did not change the amount of mercury drawn from the oral cavity. Sampling with different mouthpieces and closed mouth was compared to open mouth sampling with a thin plastic tube. It was found that the latter method could result in lower values for some volunteers due to simultaneous mouth breathing. After placing individual plastic teeth covers in the mouth, the intraoral evaporation of mercury decreased immediately by 89–100% of previous levels. This technique could be used to detect mercury evaporation from separate amalgam fillings or to reduce the intraoral mercury vapor concentration. Rinsing the mouth with heated water for 1 min increased the mean evaporation rate by a factor of 1.7 when the water temperature increased from 35°C to 45°C.
Effects of Weight Watchers' diet on salivary secretion rate, buffer effect and numbers of mutans streptococci and lactobacilli
Authors: Andréen Ingrid , Köhler Birgitta
Published: October 2007

The aim of this investigation was to study how a change to the dietary regimen of the Weight Watchers' (WW) affected salivary secretion rate, buffer effect and number of cariogenic bacteria. Thirty‐three women joining the WW were saliva sampled at the evening prior the day of the start of the dietary regimen and after 4 and 8 wk on the dietary regimen. No significant changes were found regarding saliva secretion rate and buffer effect. A significant decrease of salivary numbers of mutans streptococci and lactobacilli occurred. Between the 4th and 8th wk of dietary regimen an increase of cariogenic bacteria occurred but not back to the baseline values. At baseline 15 of the WW carried Streptococcus sobrinus in addition to Streptococcus mutans. The total number of salivary mutans streptococci and lactobacilli was significantly higher in those subjects. In conclusion the dietary regimen of the WW, based on food choice and distributions of meals in agreement with a non‐cariogenic diet, reduced the number of cariogenic bacteria in most subjects, but not in all, while the secretion rate and buffer effect remained the same.
Uptake of KOH‐soluble and KOH‐insoluble fluoride in sound human enamel after topical application of a fluoride varnish (Duraphat) or a neutral 2% NaF solution in vitro
Authors: Cruz Roberval , Ögaard Björn , Rölla Gunnar
Published: October 2007

The uptake of alkali‐soluble fluoride (calcium fluoride‐like material and adsorbed fluoride) and alkali‐insoluble fluoride (apatitically bound fluoride) on sound human enamel from treatment with Duraphat or a neutral 2% NaF solution was investigated in vitro. Blocks from impacted third molars were used. More fluoride was deposited on the enamel from the neutral 2% NaF solution than from the Duraphat treatment. All the fluoride could be dissolved in alkali. Globules of calcium fluoride‐like material were demonstrated by scanning electron microscopy. Chemical analysis showed no measurable increase in the apatitically bound fluoride (alkali‐insoluble fluoride) after brief exposures. Duraphat‐treated samples submerged in water after the exposure lost only about 50% of the deposited fluoride, whereas samples treated with 2% NaF are known to lose all their fluoride under similar circumstances, a condition which may be related to the favorable clinical effect of Duraphat.
Efficacy of bone‐fill favoring treatment on juvenile periodontitis
Authors: Sewón Liisi , Talonpoika Juha
Published: October 2007

In this study we evaluated the effect of bone‐fill favoring mechanical treatment on the marginal bone level and periodontal pockets of juvenile periodontitis patients. A total of 10 patients (3 men and 7 women) 13–29 yr of age were treated until no gingivitis or periodontal pockets were present. The intensive therapy (3–8 wk) included scaling, curettage and modified Widman flaps. The maintenance therapy comprised 4 recall visits during the first year after therapy and 2–5 visits per year thereafter. The efficacy of the therapy was evaluated by radiologic measurements of bony defects (%) 12 and 16–65 months after the treatment. The results showed a significant improvement both 1 yr after treatment and at the end of the study. The bone loss was 10.1% less than prior to the treatment and no sites with new bone loss were found after therapy in any of the patients. The bulk of healing took place during the first year after the active therapy, while some further improvement was detected thereafter. Our results show that non‐resective mechanical treatment allows excellent healing and regeneration of JP lesions. Our findings also suggest that an adequate follow‐up period is needed before definite conclusions can be drawn about the efficacy of the treatment procedures used.
Ultrasound image of human masseter muscle related to bite force, electromyography, facial morphology, and occlusal factors
Authors: Bakke Merete , Tuxetv Anette , Vilmann Peter , Jensen Bente Rona , Vilmann Anders , Toft Mette
Published: October 2007

The thickness of the human masseter muscle, corresponding approximately to a cross‐section at the most bulky part of the superficial portion, was measured by ultrasound scanning at three sites 1 cm apart. The study included 13 women, 21–28 yr of age, with a minimum of 24 teeth and without craniomandibular disorders. Ultrasonography produced a well‐defined depiction of the muscle with distinct tendinous structures. The average thickness at the measuring sites varied from 8.83 to 11.08 mm with the muscle relaxed, and increased significantly during contraction to average values between 9.84 and 12.57 mm. The study showed a connection between measures of masseter thickness and function of the muscle, as well as parameters generally associated with masseter muscle function. Muscle thickness at the voluminous anterior part of the superficial portion was systematically and significantly correlated to bite force, occlusal tooth contact and cephalometric data (anterior face height, vertical jaw relation and mandibular inclination). In conclusion, ultrasound scanning gave an uncomplicated and a reproducible access to parameters of jaw muscle function and its interaction with the craniomandibular system.