Showing papers in "Acta Odontologica Scandinavica in 1978"
TL;DR: Number of occluding pairs of teeth was closely correlated with chewing efficiency and individuals with less than 20 teeth had a higher index score than those with more than 20, but the variation was not linear and not always significant.
Abstract: Chewing efficiency, defined as the ability to grind a certain portion of a test food during a given time, was tested in 139 Skolt Lapps, ages 14-65. 94 persons had natural teeth and the remaining 45 wore dentures (partial and/or complete). The test food was almonds. Number of chewing strokes, swallowings and chewing time was denoted. The chewing efficiency was classified after a scale from 1 to 5 where 1 meant very good and 5 very poor ability to reduce the particle size of the test food. Clear associations were found between chewing efficiency and dental state. Number of occluding pairs of teeth was closely correlated with chewing efficiency and individuals with less than 20 teeth had a higher index score than those with more than 20 teeth. The values noted for number of chewing strokes, swallowings and chewing time were smaller for those with a good chewing efficiency, but the variation was not linear and not always significant. Denture wearers had statistically significantly higher chewing efficiency score than those with natural teeth, without dentures, and needed more chewing time before swallowing.
281 citations
TL;DR: The results demonstrate that commercially available composite materials exhibit different degrees of conversion 24 hours after the start of polymerization, which can be correlated to the different monomer compositions of the composite restorative resins.
Abstract: The quantity of the remaining unreacted methacrylate groups in polymerized composite materials has been determined. Six proprietary composites were investigated by infrared multiple internal reflection spectroscopy. Infrared reflectance measurements were made before polymerization and refeated after the composites were subjected to polymerization at 37 C for 24 hours. The quantities of remaining unreacted methacrylate groups were determined and the data expressed as percentages of the total amount of methacrylate groups in the unpolymerized materials. The specimens were specially prepared to ensure that the surface properties simulated the bulk properties of the polymerized composites. The quantities of remaining methacrylate groups in the six composites determined by this surface measuring technique ranged from 25 to 48 %. The results demonstrate that commercially available composite materials exhibit different degrees of conversion 24 hours after the start of polymerization. These differences can be cor...
240 citations
TL;DR: The formed films were found to be stable over long periods of time, and only showed patches of adhering micro-organisms on some of the prisms which had been exposed in the oral cavity for 2 h.
Abstract: Baier, RE Glantz, P-O Characterization of oral in vivo films formed on different types of solid surfacesStudies were made of oral films formed in vivo, which had been allowed to form on fused silica and Ge-prisms during periods between 2 s and 2 h using a variety of physico-chemical methods To produce surfaces of different qualities the silica and Ge-prisms had either been detergent-washed, glow discharge treated or covered with polydimethylsiloxane The following simultaneous analytical techniques were performed on the adsorbed films: a internal reflection infrared spectroscopy, b ellipsometry, c contact potential measurements, d contact angle measurements, e scanning electron microscopy and f energy-dispersive x-ray analysisThe results of these studies show that the formation of oral films proceeds at high speed and is of a certain qualitative selectivity The formed films were found to be stable over long periods of time, and only showed patches of adhering micro-organisms on some of the pr
141 citations
TL;DR: The relationships between traumatic injuries to upper incisors and incisal overjet were studied in a sample of 1445 orthodontically untreated children and the range of injuries increased in relation to the overjet.
Abstract: The relationships between traumatic injuries to upper incisors and incisal overjet were studied in a sample of 1445 orthodontically untreated children aged 7 to 16 years. Traumatic injuries of the hard dental tissues and exarticulations of teeth were recorded. The frequently of injuries was 14.2% in children with normal overjet (0--3 mm), 28.4% in children with increased overjet (3.1-6mm), and 38.6% in children with extreme overjet (greater than 6 mm). The severity of injuries was also greater in children with extreme overjet than in children with overjet ranging from 0 to 6 mm. Furthermore, the range of injuries increased in relation to the overjet. Two or more injured incisors were found in 19.2% of the children with normal overjet, in 22.2% of the children with increased overjet, and in 46.7% of those with extreme overjet.
102 citations
TL;DR: The investigation showed that clenching of teeth was correlated to the severity of headache, and functional examination of the masticatory system should be included in investigations of recurrent headaches.
Abstract: Two groups of 80 patients, one referred because of mandibular dysfunction and one seeking dental treatment, completed questionnaires concerning recurrent headaches. The function of the masticatory system of all patients was afterwards examined clinically. The investigation showed that clenching of teeth was correlated to the severity of headache. The frequency and severity of headache varied also with the severity of mandibular dysfunction. Of the variables included in the dysfunction index, only masticatory musculature painful to palpation was found to have a distinct relationship to headaches. This implies that functional treatment is indicated in patients with headaches and tendernes of the masticatory musculature. Functional examination of the masticatory system should therefore be included in investigations of recurrent headaches.
99 citations
TL;DR: The results of therapeutic pulpotomies in primary molars with formocresol technique were studied by systematic follow-up and revealed a very capricious diffusion of the medicament throughout the pulp tissue.
Abstract: The results of therapeutic pulpotomies in primary molars with farm-cresol technique were studied by systematic follow-up. Of 84 primary lower molars in the clinical study, 56 became available for histological examination. The radiographic follow-up revealed periradicular osteitis in 10 per cent of the teeth treated. Internal root resorption was seen in 37 per cent of the teeth, or one-fifth of the roots treated.The histological examination revealed a very capricious diffusion of the medicament throughout the pulp tissue. Vital pulp remnants in the apical part of the treated roots showed no signs of healing. All pulps presented a varying number of inflammatory cells in the border zone adjacent to the formocresol-fixed region. In 80 per cent of the roots the histological sections revealed signs of internal resorption with or without incomplete repair tissue formation.
53 citations
TL;DR: Heloe et al. as mentioned in this paper investigated the occurrence of TMJ-disorders in an elderly population as evaluated by recording of ''subjective« and ''objective« symptoms.
Abstract: Heloe, B. & Heloe, L.A. The occurrence of TMJ-disorders in an elderly population as evaluated by recording of »subjective« and »objective« symptoms. Acta Odont. Scand. 36, 3–9The Occurrence of »objective« symptoms of TMJ-disorder, as measured by clinical examination, and self-reported »subjective« symptoms, were investigated in a survey of 241 persons aged 65-79. This group constituted the participants of a sample which was drawn to cover all persons in this age category living in the county of Troms in Norway. The participation rate was 86. Participants were examined and interviewed by dentists in graduate training.Eight per cent of the group reported to have had TMJ pain recently. Fourteen per cent said they had clicking or crepitation. These symptoms were twice as commonly reported by women as by men, and they were also most frequent among people complaining of rheumatism or general joint pain. By the clinical examination, clicking and/or crepitation was found h 27% of the individuals. Limitation of ja...
52 citations
TL;DR: Corrosion of base metal alloys was studied by placing the alloys in artificial saliva for 2 months and then determining the concentration of metal ions in the saliva, which indicated that the amount of metal ion in the artificial saliva could be related to the Cr content of the alloy.
Abstract: Corrosion of base metal alloys was studied by placing the alloys in artificial saliva for 2 months and then determining the concentration of metal ions in the saliva. The distribution of the attack on the surface was examined. The results indicated that the amount of metal ions in the artificial saliva could be related to the Cr content of the alloy. When the Cr content exceeded 16% very little corrosion was observed. The corrosive attack was located at Cr depleted areas, grain boundaries. The Cr depletion probably resulted from coring during solidification.
48 citations
TL;DR: The frequency of a complicating pulp necrosis and the process of the physiologic root resorption were studied in traumatized primary teeth exhibiting partial or total pulp obliteration in 72 children aged 0.7--5.7 years at the time of injury.
Abstract: The frequency of a complicating pulp necrosis and the process of the physiologic root resorption were studied in traumatized primary teeth exhibiting partial or total pulp obliteration. The material comprised 88 incisors in 72 children aged 0.7–5.7 years (mean 2.9 years) at the time of injury. Trauma had resulted either in subluxation (25 teeth), or luxation (13 teeth), whereas the type of injury was unknown in 50 teeth. All cases were observed until eruption of the permanent incisors. Forty-four teeth initially displayed a reversible greyish color. The ultimate finding observed in all teeth was, however, varying degrees of yellow discoloration. Periapical pathologic findings indicative of pulp necrosis were observed in 9 teeth, from 1.6–4 years (mean 3 years) after the time of injury. Extraction was performed immediately, and none of the successional teeth showed developmental disturbances. The process of root resorption was classified as normal in all primary teeth. Subsequent eruption of the permanent ...
46 citations
TL;DR: It was shown that tin accumulated in dental plaque after application of solutions containingStannous fluoride, and it was suggested that the reduction in acid formation may be caused by stannous ions adsorbing to the bacterial cell wall thus disturbing membrane transport mechanisms, or through inhibition of enzyme systems essential in the fermentation of sugars.
Abstract: A system employing an Ingold glass electrode was shown to give reliable measurements of pH drops in dental plaque in situ (Stephan curve readings). The system was used to demonstrate that mouthrinses of 0.2 per cent aqueous solutions of stannous fluoride reduced the pH drops markedly for at least seven hours. A reduction of the stannous fluoride concentration increased the pH drops and decreased the duration of the inhibiting effect. A commercial toothpaste containing stannous fluoride and stannous pyrophosphate had an effect similar to the 0.2 per cent mouthrinse. It was shown that tin accumulated in dental plaque after application of solutions containing stannous fluoride. About 40 per cent of the amount of tin present in the plaque immediately after the mouthrinse was still retained seven hours later. It is suggested that the reduction in acid formation may be caused by stannous ions adsorbing to the bacterial cell wall thus disturbing membrane transport mechanisms, or through inhibition of enzyme systems essential in the fermentation of sugars. The observed effect may be a part of the mechanism involved in the caries preventive function of stannous fluoride.
44 citations
TL;DR: The study does not provide any obvious evidence of a chemical effect of chlorhexidine gel or Steradent as a means to prevent formation of microbial plaque on the mucosal surface of maxillary complete dentures.
Abstract: It was the purpose of the study to test the efficacy of brushing with a 1% chlorhexidine gel or a commercial solution cleanser (Steradent) in preventing formation of plaque on the fitting surface of new dentures. The study group consisted of 74 denture wearers with denture stomatitis who were assigned randomly to one of four treatment groups, testing either the chlorhexidine gel, a placebo gel, Steradent, or a placebo solution. The experiment was started immediately after denture treatment was completed. The experimental period was 1 month. The amount of denture plaque, the clinical condition of the palatal mucosa, and the concentration of yeasts in mucosal and denture smears were recorded while the patients used their original dentures and after the experimental period. Plaque had formed on all new dentures but to a smaller extent in the groups testing the chlorhexidine gel or the placebo gel. The study does not provide any obvious evidence of a chemical effect of chlorhexidine gel or Steradent as a means to prevent formation of microbial plaque on the mucosal surface of maxillary complete dentures.
TL;DR: It is suggested that the alkali soluble fluoride is adsorbed to calcium ions bound as counterions in the hydration layer of the hydroxyapatite or the enamel, consistent with previous findings, and differs slightly from that proposed by Bernardi.
Abstract: The experiments showed that a part of the fluoride which was taken up by hydroxyapatite or teeth at low concentrations of fluoride at neutral pH was soluble in alkali (IN KOH, 24 h) and was thus not fluoroapatite. Calcium fluoride could not form under the present conditions because the solubility of this compound was not exceeded. It is suggested that the alkali soluble fluoride is adsorbed to calcium ions bound as counterions in the hydration layer of the hydroxyapatite or the enamel. This is consistent with previous findings in this laboratory, showing that fluoride displaced acidic proteins adsorbed to calcium receptors on the hydroxyapatite surface in the same way as other anions displace proteins. It could also be shown that polyanions and polycations adsorbed to hydroxyapatite surfaces by ionic exchange, displacing phosphate or phosphate and calcium respectively in the process. A model is suggested which differs slightly from that proposed by Bernardi.
TL;DR: The average oral hygiene and periodontal health was poor except for patients in a few institutions where the nurses were trained to clean teeth regularly and the preventive programs used in some institutions seemed to be effective.
Abstract: Oral hygiene, periodontal health and periodontal treatment needs were studied in the dentulous patients (n = 328) of a sample selected to be representative of all institutionalized mentally subnormal persons in Norway aged 5--45. The average oral hygiene and periodontal health was poor except for patients in a few institutions where the nurses were trained to clean teeth regularly. Increased age, epilepsy, Down's syndrome and a high degree of mental deficiency were all elements that apparently contributed to impairment of periodontal health and to increased treatment requirements. The preventive programs used in some institutions seemed to be effective. Still better results, however, could probably be obtained by the use of dental hygienists.
TL;DR: The present study showed that the plaque inhibiting effect of aqueous solutions of stannous fluoride can be maintained in toothpastes.
Abstract: The present study showed that the plaque inhibiting effect of aqueous solutions of stannous fluoride can be maintained in toothpastes. A commercial toothpaste containing 0.14 per cent of water so luble tin was effective whereas one containing 0.03 per cent showed no effect. The plaque inhibiting effect was shown in one study where the toothpastes were applied in cap splints and the plaque was scored after four days by the Plaque Index of Loe, and in another where the effect of locally applied pastes was monitored 24 hours later by the Gingival margin Plaque Index of Harrap. The present investigation supports the view that the stannous ion is essential in the plaque inhibition caused by stannous fluoride preparation. The excact mechanism is unknown but it is speculated that a change in the surface potential of oral bacteria through interaction with the stannous ion may be important.
TL;DR: The compressive strength, modulus of elasticity and the plastic strain at fracture have been studied for several dental luting cements and it was shown that large differences existed between various lute cements.
Abstract: Baa, G. & Espevik, S. Stress/strain behavior of some dental luting cements. Acta Odont. Scand. 36, 45–49The compressive strength, modulus of elasticity and the plastic strain at fracture have been studied for several dental luting cements. Stress/strain diagrams of cylindrical specimens using two different crosshead speeds (2 mm/min and 0. 1 mm/min) at 23° and 37°C showed that large differences existed between various luting cements.A zinc phosphate cement exhibited high strength, high modulus of elasticity and a small plastic strain at fracture. A resin cement also had high strength, but elastic and plastic strains were high. A polycarboxylate and an EBA-cement both showed low values of strength and modulus of elasticity combined with a high degree of plastic deformation at fracture. Testing with low strain rate at 37 °C accentuated the differences between these two materials and the zinc phosphate cement.
TL;DR: Irrespective of treatment, the IDM showed a significantly higher incidence of widened neonatal lines and also an increased frequency of postnatal disturbances compared to the controls, and the observations are discussed against the background of the neonatal hypocalcemia reported in IDM.
Abstract: According to clinical studies, infants of diabetic mothers (IDM) seem to run a higher risk of mineralization disturbances in the enamel than normal healthy infants. In order to evaluate this observation at the histologic level, exfoliated primary incisors were collected from 74 IDM, representing two types of care during gestation and the perinatal period, and from 52 healthy children.The width of the neonatal line was evaluated in the enamel and the dentin by study of bucco-lingual undemineralized sections. Pre-and postnatal enamel was classified according to discolorations, deviations of prisms and hypoplasia. Microradiographic studies included measurements of the neonatal lines and classification of the degree of mineralization in the pre-and postnatal dental hard tissues.Irrespective of treatment, the IDM showed a significantly higher incidence of widened neonatal lines and also an increased frequency of postnatal disturbances compared to the controls. The observations are discussed against the backgro...
TL;DR: Pancherz et al. as mentioned in this paper investigated the relationship between the number of intermaxillary tooth contacts and the EMG activity from the temporal and masseter muscles during chewing.
Abstract: Pancherz, H. Anehus, M. Masticatory function after activator treatment. An analysis of masticatory efficiency, occlusal contact conditions and EMG activity.Masticatory function was investigated in nine patients with relapse and ten patients without relapse of overjet after activator treatment, Masticatory efficiency, evaluated by a chewing test, was related to the number of intermaxillary tooth contacts and the electromyographic (EMG) activity from the temporal and masseter muscles during chewing. The results of the investigation indicated that a reduced masticatory efficiency was connected with fewer intermaxillary tooth contacts and less EMG activity from the temporal and masseter muscles. In patients with relapse of overjet, masticatory efficiency and muscle activity was reduced in comparison with patients without relapse. The relationship between the number of tooth contacts and masticatory efficiency was poor in the relapse patients. Unstable occlusal conditions and atypical tongue function may be an...
TL;DR: Results showed that the use of a syringe reduced the porosity content, mainly by the elimination of big pores, in resin filling materials and capsulated products.
Abstract: Four paste-paste types of resin filling materials and three capsulated products were tested with respect to porosity content and size distribution of the pores. The data were obtained by using an automatic image analyzer. The paste-paste products were inserted into the test cavities by a bulk-packing technique and an injection technique. The results showed that the use of a syringe reduced the porosity content, mainly by the elimination of big pores. The capsulated products were not less porous than the paste-paste materials.
TL;DR: The results for the Polyol and No-Sweets groups were similar; both the xylitol-sorbitol mixture and abstention from sweets reduced the VPI and GBI and lactobacillus index.
Abstract: The purpose of this study was to determine whether partial substitution of xylitol and soibitol for sucrose could produce changes in plaque formation, gingivitis and oral bacteriology in children. The subjects consisted of 55 volunteer schoolchildren aged 14 to 16, divided into the following groups: 1) Polyol Group (26 children), 2) No-Sweets Group (8), 3) Sucrose Group (21).During the two weeks of the study, the Polyol Group consumed chewing gum and pastilles containing xylitol and sorbitol, mainly after meals. The No-Sweets Group was instructed to consume no sweets during the study. The Sucrose Group chewed gum and ate sweets same as before the study. The variables measured were the visible plaque index (VPI), gingival bleeding index (GBI) and lactobacillus index (Dentocult®). The scores for these indices were determined at the beginning and end of the study. The results for the Polyol and No-Sweets groups were similar; both the xylitol-sorbitol mixture and abstention from sweets reduced the VPI and GBI...
TL;DR: Results indicate that the implantation technique described is applicable for in vivo screening of initial tissue response to biomaterials and correlates well with previous tissue compatibility studies.
Abstract: In the present paper an implantation technique is described whereby the effect of the surgical operation is eliminated and initial tissue reactions to materials may be studied. A teflon body was implanted intramuscularly in rabbits. After six weeks the overlaying tissue was excised and the implant removed. An intact, nonepithelialized tissue surface was exposed, which due to the shape of the implant showed three indentations. Materials were placed in the indentations for 15 minutes and the tissue reaction was registered by enzyme histochemical methods. Silicate cement, zinc phosphate cement and a 4% phenol solution caused an inhibition in the dehydrogenase enzyme activity in the tissue subjacent to the indentations. The seventy of the tissue reaction, indicated by the width of the inhibition zone, varied among the test materials. Silicate cement caused the widest inhibition zone and the phenol solution the narrowest one. These results correlate well with previous tissue compatibility studies and indicate ...
TL;DR: The present summary and the following papers are submitted in partial fulfillment of the requirements for the degree of Doctor Odonto-logiae at the University of Oslo.
Abstract: Oilo, G. Sealing and retentive ability of dental luting cements.The present summary and the following papers (I—VIII) are submitted in partial fulfillment of the requirements for the degree of Doctor Odonto-logiae at the University of Oslo.I Linear dimensional change during setting of a zinc phosphate cement. A methodological study. J. Oral Rehabil. 1975, 2, 179–185II Linear dimensional changes during setting of two polycarboxylate cements. J. Oral Rehabil. 1976, 3, 161–166III Linear dimensional changes of three luting agents. J. Oral Rehabil. 1977, 4, 395–399Coauthor: E. AmbjeirnsenIV Adaption of luting cements to enamel, dentin and restorative material. Acta Odontol. Scand. 1978, 36, 149–156V Extent of slits at the interface between luting, cements and enamel, dentin and alloy. Acta Odontol. Scand. 1978, 36, 257–261VI Adhesive bonding of dental luting cements: Influence of surface treatment. Acta Odontol. Scand. 1978, 36, 263–270VII Stresslstrain behaviour of some dental luting cements. Acta Odontol. Sc...
TL;DR: All dentin treatments showed in general a decreasing effect on the bond strength of zinc phosphate, polycarboxylate and EBA cements, whereas that of composite resin cement showed a slight increase.
Abstract: Tensile bond strength of four different luting cements to smooth dentin surfaces was measured. A chisel edged, stainless steel ring was cemented to the butt end of a dentin cylinder. The dentin was polished to a plane and smooth surface before cementation. The cements were also applied to dentin surfaces that were treated with a pumice slurry, etched with different acid solutions, or covered with different liners. The results showed that the polycarboxylate cement had a tensile bond strength to smooth, untreated dentin of approximately 4 MN/m2. The zinc phosphate and EBA cements had a bond strength of 0,6 MN/m2 and the composite resin cement had no measurable bond to untreated dentin. All dentin treatments showed in general a decreasing effect on the bond strength of zinc phosphate, polycarboxylate and EBA cements, whereas that of composite resin cement showed a slight increase.
TL;DR: The stress/strain behavior at different strain rates and the creep rate of dental amalgams were evaluated and it was suggested that grain boundary sliding was the deformation mechanism in both cases.
Abstract: The stress/strain behavior at different strain rates and the creep rate of dental amalgams were evaluated and compared to the microstructure. The results indicate that substantial differences exist both in strength and strain at fracture. The strain at fracture for high strain rates was associated with the nature of the particle-matrix interface, in that amalgams with an interpenetrating interface exhibited some ductility, while amalgams with an abrupt interface exhibited practically no plastic deformation at fracture. The correlation between creep and slow compressive strength was verified and it was suggested that grain boundary sliding was the deformation mechanism in both cases.
TL;DR: The study shows that even with a double layer of Copalite, known to prevent microleakage, a desirable uptake of F and Al from silicate restorations into cavity walls can take place.
Abstract: Tveit, A.B. & Hals, E. Penetration of ions from silicate cement restorations into Copalite©-covered cavity walls. Acta Odont. Scand. 36, 15–24This study aimed to assess the effect of silicate cement on Copalite®-covered cavity walls in extracted human teeth. Class V cavities were prepared in 24 premolars and filled with silicate cement (Bio-Trey®). Four cavities were unlined, the rest of the cavities were lined with 1 or 2 layers of Copalite before insertion of the restorations. After 6 months, 70-100 μm thick longitudinal sections of the teeth were studied by polarized light microscopy, microradiography and electron probe microanalysis. When imbibed in water or quinoline, a subsurface zone of altered birefringence was noticed in nearly all cavity walls. Nearly half of the cavit walls in the experimental groups showed a surface zone of increased radiopacity. In a few instances a subsurface radiolucent zone was present. By electron probe microanalysis F (0,4-3% by weight), Zn (14%) and Al (0,2-6%) were mea...
TL;DR: Fifty-two permanent tooth pairs of 37 children aged 8 to 16 years were evaluated for opacities and hypoplasia of the enamel and none of primary control teeth had a history of pulp exposure.
Abstract: Fifty-two permanent tooth pairs of 37 children aged 8 to 16 years were evaluated for opacities and hypoplasia of the enamel. Formocresol pulpotomy had been performed in one of the primary teeth proceeding each tooth pair. The study comprised teeth with clinically and radiographically successful and unsuccessful pulpotomies. None of primary control teeth had a history of pulp exposure. 57 permanent teeth with caries-free predecessors were included for further control.In the formocresol treated group the prevalence of opacities according to localization was: occlusal surface 25%, buccal surface 37% and palatal surface 14%. In the control group, the corresponding prevalence was 21%, 35% and 14%. The prevalence of hypoplasia was 2%, 8% and 0% respectively, in the formocresol group and 2%, 14% and 4% in the control group. In the 57 permanent teeth opacities were found in 16% of the occlusal and buccal surfaces and in 18% of the palatal surfaces. The prevalence of hypoplasia was 12%, 5% and 0% respectively.No d...
TL;DR: The results indicate the advantage of using an intermediary resin with etching even when the composite is diluted, as it exhibited significantly less leakage than fillings without the intermediary layer.
Abstract: Forsten, L. Marginal leakage and consistency of the composite resin material in etched cavities. Acta Odont. Scand. 36, 11–13The purpose of the study was to evaluate the degree of adaptation of und...
TL;DR: The antibacterial effect of a polycarboxylate cement and a zinc phosphate cement was studied in vitro and in vivo and a streptomycin resistant strain of Streptococcus mutans (Strep. mutansPRSR) was used.
Abstract: Dahl, B.L. Antibacterial effect of two luting cements on prepared dentin in vitro and in vivo.The antibacterial effect of a polycarboxylate cement (Durelon®) and a zinc phosphate cement (De Trey's Zink Zement Improved®) was studied in vitro and in vivo.For in vitro experiments a streptomycin resistant strain of Streptococcus mutans (Strep. mutansPRSR) was used. In one experimental series 1 ml of an overnight bacterial culture was suspended in 20 ml of nutrient agar, and poured to set in Petri dishes. Holes 5 mm in diameter were punched in the gel and filled with freshly mixed cement. The antibacterial effect was estimated by measuring the diameter of the zone of bacterial growth inhibition surrounding the holes after 24 h. In another experimental series two cavities were cut into the dentin of newly extracted human third molars. On the floor of both cavities a circular disc of filter paper saturated with Strep. mutans PRSR was placed. A sterile brass cylinder with freshly mixed cement covered one of the p...
TL;DR: The results showed that the zinc phosphate cement and poly carboxylate cement exhibited a slight to moderate tendency to formation of slits at the interfaces.
Abstract: Oilo, G. The extent of slits at the interfaces between luting cements and enamel, dentin and alloy.Four different cements were used to assess the presence of slits at the cement/tooth or the cement/alloy interfaces using a tooth-crown model. The model consisted of ground sections of teeth and plane plates of silver/palladium alloy. The plates were fixed with bolts between two brass plates and with three different dimensions of the cement film between tooth and alloy, i.e. 50 μm, 100 μm and 200 μm. The tooth-alloy specimens were sectioned and the adaption of cements was studied with an indirect technique (replica) in a scanning electron microscope. The extent of slits was expressed as the length of all slits relative to the total length of the interface in each specimen.The results showed that the zinc phosphate cement and poly carboxylate cement exhibited a slight to moderate tendency to formation of slits at the interfaces. The EBA cement had a small extent of slits adjacent to thin cement films, but mor...
TL;DR: It is indicated that a combination of mucoperiosteal flap technique and applied orthodontic traction is prefered to minimize the loss of attachment in cases of displaced impacted teeth.
Abstract: Treatment of impacted teeth is often a combination between oral surgery and orthodontics. This study evaluates the gingival condition of impacted teeth after surgical-orthodontic treatment, where two different surgical methods were used. In one group (n = 11) the teeth were radically exposed and orthodontically moved to their final position. In the other group (n = 11) the teeth were partially exposed by raising a mucoperiosteal flap. Orthodontic traction was then applied; whereafter the flap was sutured back into place. The results showed that one of the teeth in the partial exposure group and seven in the radical exposure group showed loss of attachment. This study indicates that a combination of mucoperiosteal flap technique and applied orthodontic traction is prefered to minimize the loss of attachment in cases of displaced impacted teeth.
TL;DR: In vitro studies were performed which demonstrated that 59Fe uptake in developing rat molar enamel was limited by the metabolic activity of the cells of the enamel organ.
Abstract: Bawden, J.W., Wennberg, A. Hammarstrom, L. In vivo and in vitro study of 5 9Fe uptake in developing rat molars.Autoradiographic methods were used to study 59Fe uptake in vivo in mineralizing tissues of young rats. Localization of 5 9Fe was observed in the ameloblastic layer of molars. In vitro studies were performed which demonstrated that 5 9Fe uptake in developing rat molar enamel was limited by the metabolic activity of the cells of the enamel organ.