Lars-Eric Granath

Hard Tissue Barrier Formation in Pulpotomized Monkey Teeth Capped with Cyanoacrylate or Calcium Hydroxide for 10 and 60 Minutes

Monkey incisor teeth were pulpotomized in groups of 10. After physiological hemostasis, the pulps of group I were covered with isobutyl cyanoacrylate, and those of groups II and III with calcium hydroxide for 10 and 60 minutes, respectively, whereafter this compound was washed away and the wound surfaces covered with Teflon. In group IV, calcium hydroxide was used as a positive control, and Teflon as a negative control in group V. The animals were killed after 12 weeks and the teeth removed in tissue blocks. The material was processed and evaluated histologically with respect to location and continuity of a hard tissue barrier, type of newly formed hard tissue, state of the pulp, and presence of stainable bacteria in the coronal cavity. Seven of nine teeth in group I showed a hard tissue barrier. The corresponding figure for group II was eight out of 10 teeth. All teeth in groups III and IV had a barrier. The incidence of a continuous barrier increased from group I through group IV, as did the incidence of its location below the level of the original wound surface. The condition of the pulp was related to the presence of bacteria and the continuity of the barrier to the presence of inflammation. There was no bridging in group V. The results support the theory that a low-grade irritation is responsible for the formation of a hard tissue barrier in exposed pulps.

Variation in Caries Prevalence Related to Combinations of Dietary and Oral Hygiene Habits and Chewing Fluoride Tablets in 4-Year-Old Children

The study covered 515 children, aged 4 years and 1 month at the time of examination, selected from a total sample of about 1,600 individuals from two limited areas in southern Sweden. The investigatio

Dental caries, sucrose intake and oral hygiene in 5-year-old South African Indian children.

Dental caries and sucrose consumption in a total of 715 5-year-old Indian children living in a low fluoride area (0.2 parts/106) around Johannesburg, South Africa, were studied. The childre

Variation in Caries Prevalence Related to Combinations of Dietary and Oral Hygiene Habits in 6-Year-Old Children

The original sample consisted of 179 randomly chosen children aged 6 years and 1 month at the time of examination. Of these children, those 88 were selected who had been exposed, since the age of 4, to consistent oral hygiene measures and dietary habits. The investigation involved clinical registration of caries, including subsurface lesions, and restorations in buccal and lingual surfaces in primary molars and cuspids. The mesial surface of second molars, distal and mesial surfaces of first molars, and the distal surface of cuspids were recorded from X-ray pictures. 85 children were classified as follows, beletary habits: (1) > 6 or (2) 5–6 meals and snacks a day including at least one ‘unsuitable’ Dack with a high-sucrose component, or (3)

Reaction of the human dental pulp to silver amalgam restorations. Effect of insertion of amalgam of high plasticity in shallow cavities.

The purpose was to study the effect of amalgam with known relative sealing properties. In 28 bicuspids deep cavities were prepared and filled according to the wet technique, 14 with amalgam A, shown to give a good seal, and 14 with another amalgam, B, which gave a comparatively less good seal. Seven teeth in each group were extracted after 1 week and 7 after 1 month. In a further 6 teeth the method of preparation was checked. The effect of the packing pressure was studied in 11 other teeth with lined cavities of varying depth. The teeth were examined histologically. All teeth in the material proper showed pulpal inflammation of varying severity, somewhat more pronounced in teeth with amalgam B. The method of preparation used had caused no significant changes. Two of 6 teeth studied regarding the effect of packing in deep cavities showed extensive fresh haemorrhages. No such reaction was found in teeth with less deep cavities. The initially high mercury content together with the shortness of the distance b...

Explanatory model for the interaction of factors in the caries process

The interaction of factors in the caries process has recently been discussed in a number of articles. Based on this, a new explanatory model has been constructed, consisting of an equilateral triangle with one of the apices on a horizontal line, along which dietary and oral hygiene habits are scaled. The triangle represents the total area of interaction. A horizontal line of resistance cuts off a lower part corresponding to the area within which caries does not occur. Through planogeometric calculations the remaining part of the triangle can be divided into areas, approximately corresponding to the relative caries values of various combinations of dietary and oral hygiene habits. The model has proved to be a useful instrument for demonstrating and creating an understanding of interactive processes among various groups of dental health personnel. The example presented is based on a pilot study of 55 4-year-old children in Malmö.

Margin Adaptation of Dispersion and Traditional Amalgams with Reference to Plasticity: A Clinical Comparison

Margin adaptation of dental amalgam restorations made from traditional vs. dispersion-type alloy was compared by clinical evaluation with reference to plasticity of the mix at insertion. Also, variations in sealing properties were assessed for precondensed and not-precondensed amalgam mixes of both alloys. The data presented confirm the clinical superiority of amalgam made from dispersed type alloy. A higher plasticity tended to result in less margin deterioration for amalgams of the traditional type alloy. In vitro leakage with the dispersion type amalgam far exceeded that of the traditional amalgam.

Scandinavian Division of the International Association for Dental Research—Abstracts of Papers Presented at the Annual Meeting

S, DIVISIONS AND SECTIONS 1305 and in the cells of the dental lamina. Arylsulfates and f-glucuronidase activity was localized in the outer and inner enamel epithelium and in the cells of the region of dental papilla. These observations were thought to indicate proteolytic and glycolytic enzyme activity in the remodeling processes during tooth development. 5. CRYSTAL GROWTH IN RAT INCISOR ENAMEL.-K. A. Selvig and A. Halse, School of Dentistry, University of Bergen, Norway. The width and thickness of hydroxyapatite crystals and the crystal density at various stages of rat incisor amelogenesis were studied with the use of electron microscopy. The cross-sectional profile of the crystals increased from 259 X 12.7 A at the surface of the ameloblast to 454 X 249 A in the completely mineralized enamel. In agreement with previous observations, many crystals had a regular, flattened hexagonal profile during the matrix formation stage. During enamel maturation, the crystals assumed more irregular surface contours; the crystals tended to adapt themselves to the available space. In completely mineralized enamel, the crystals were as irregular in shape as the crystals in human enamel, and they occupied about 85% of the volume. Although the crystals at the onset of mineralization were separated by a distance of 120 to 150 A, they eventually became relatively closely packed, separated by a fine space 10 to 25 A in width. A lesser number of crystals per unit of cross-sectional area of the enamel prisms was observed in fully mineralized enamel than in the early stages of amelogenesis. Because evidence of fusion of crystals is lacking, the decrease in crystal density seems to result from swelling of the enamel prisms. 6. IRON CONTENT OF RAT INCISORS DURING EXPERIMENTAL IRON DEFICIENCY.-A. Halse and K. A. Selvig, School of Dentistry, University of Bergen, Norway. The enamel of rat incisors is characterized by a pigmented, iron (Fe)-rich surface layer. The iron content and degree of mineralization of this enamel layer in rats fed an iron-deficient diet was studied with the use of the electron microprobe. Four groups of eight 24-dayold rats were fed a milk diet, Fe-fortified milk diet, copper (Cu)-fortified milk diet, and Fe + Cu-fortified milk diet, respectively, for ten weeks. At the end of the experimental period, incisor pigmentation was greatly reduced in the rats fed the Fe-deficient diets. Close to the enamel surface, the Fe content averaged 1.9% in the midsagittal region, as compared with 9.9% in the controls. Cu deficiency had no effect on hemoglobin values of Fe content of incisor enamel. In a second experiment, rats were fed a milk diet with and without Fe supplementation. Nearly colorless incisors from rats killed after 16 weeks on the milk diet contained 1.9% Fe (range was from 1.4 to 2.5% ) close to the enamel surface. In this region, the calcium (Ca) content averaged 33.7% (32.0 to 34.9%) and phosphorus (P) 17.2% (16.3 to 18.1%). Normally orange-colored incisors from rats that received the Fe-supplemented diet contained, in the same region, 9.9% Fe (9.3 to 10.5%), 28.9% Ca (27.7 to 29.9%), and 16.0% P (15.4 to 16.4%). Although pigmentation and Fe content of incisor surface enamel were reduced significantly as a result of the Fe-deficient diet, the Ca and P content increased to values similar to those found in nonpigmented enamel. 7. OBSERVATIONS ON ENDOPEPTIDASES IN HUMAN CARIOUS DENTIN.-M. Larmas, Institute of Dentistry, University of Turku, Finland. The aim of this study was to further map the protein catabolism in carious dentin. Carious dentin was excavated from human teeth and sound dentin was obtained from intact teeth. The enzymes were extracted with phosphate buffer, pH 7.4 (4 ml/gm dentin). The remaining pellet then was sonicated for 10 minutes five different times; thus, six enzyme preparations were obtained from the samples. Enzyme activity was assayed with the use of denatured hemoglobin (Hb) or Na-benzoyl-DL-arginyl-2naphthylamine (BANA) as substrates. Protein concentration was estimated with the Folin-Ciocalteu method and dioxyribonucleic acid (DNA) with a diphenylamine color reaction. The enzyme preparation from carious dentin liberated about 0.05 moles tyrosine per minute per milligram protein from Hb at pH 7.0. The protein concentration of the preparation was about 2.0 mg/ml, and the DNA content was 0.6 [tg/ ml. The respective figures from sound dentin were 0.003 ,umoles/minute/milligram/protein (enzyme activity); 0.3 mg/ml (protein concentration); and 0.2 [tg/ml (DNA). The hydrolysis of Hb was high over a relatively wide pH range, and the pH Vol 51 1972 1306 SCANDINAVIAN DIVISION optimum was 5.5. A similar result was obtained when BANA was used as the substrate; the pH optimum then was 7.2. The significance of the enzymes was thought to be connected to the hydrolysis of protein molecules into peptides in dentinal caries. 8. IDENTIFICATION OF PLASMA PROTEINS IN FLUID FROM NONKERATINIZING JAW CYSTS.-N. Skaug, School of Dentistry, University of Bergen, Norway. Cyst fluid has been thought to be a simple dialysate from the blood plasma through the cyst membrane, which discriminates against the larger molecules. To obtain more exact information about the composition and source of cyst fluid, cyst fluids and autologous serums, blood plasma, and noninflammatory edema fluid (subcutaneous blister fluid) were investigated by microimmunoelectrophoresis in agar. The patterns developed with rabbit anti-normal human serum showed the same main protein components in all specimens. Staining with oil red 0 revealed that low density lipoproteins were diminished in quantity in cyst fluids and edema fluid. Identification of plasma proteins with monovalent immune serums from rabbits substantiated the presence of a1-lipoprotein, a,-acid glycoprotein, ac-antitrypsin, and a9macroglobulin in edema fluid and cyst fluid. Fibrinogen was not detected in edema fluid. In cyst fluid, one or two precipitation lines showed migration different from plasma fibrinogen. By double diffusion in agar, fibrinogen in plasma and cyst fluids gave a pattern of coalescence. The results indicate that fluid from nonkeratinizing jaw cysts has a qualitative composition similar to plasma rather than to noninflammatory edema fluid. Fibrinogen in cyst fluid is present as a polymer. The function of the cyst wall as a semipermeable membrane was not confirmed. The inflammatory reaction in cyst walls that causes increased capillary permeability and obstruction of lymphatic drainage may be primarily responsible for the accumulation of cyst fluid. 9. USE OF HISTOCON IN TRANSPORTS OF TISSUE BIOPSY SPECIMENS FOR HISTOPATHOLOGICAL DIAGNOSIS.-T. Arwill and G. Heyden, Department of Oral Histopathology, Faculty of Odontology, University of Giteborg, Sweden. Previous studies have shown that the chlorhexidine that contains Histocon solution as a medium for transport of biopsy specimens for diagnosis, facilitates the use of cold microtome sectioning and enzyme histochemical techniques in routine histopathological diagnostic practice. It also seems to be superior to Formalin solutions before ordinary paraffin sectioning because of better tissue preservation and retention of soluble components such as lipids and glucosaminoglycans. Since September 1971, our histochemical and cytochemical laboratory has used histological, chemical constituent histochemical, and enzyme histochemical techniques routinely on tissue biopsy specimens for histopathological diagnosis after transport of the specimens in cold (+4 C) Histocon solution. Data have been accumulated about chemical component and enzyme activity characteristics for different oral diseases, which may facilitate diagnosis, provide information of metabolic changes involved in the pathologic conditions, and have pedagogic value. 10. DNA, RNA, AND PROTEIN SYNTHESIS IN HEALING WOUNDS IN YOUNG AND OLD MICE.-P. Holm-Pedersen, A. M. Fenstad, and L. E. A. Folke, Division of Periodontology, University of Minnesota, Minneapolis, USA, and Department of Periodontology, Royal Dental College, Aarhus, Denmark. Assessments of the mitotic and functional potential of fibroblasts are important parameters in the attempt to analyze the causes of the impaired wound healing capacity of elderly people. In the present study with mice, the synthesis of dioxyribonucleic acid (DNA), ribonucleic acid (RNA), and protein in the connective tissue of skin wounds was determined, and the number of fibroblasts present during the healing process was assessed. Six incisions were made on the back of young and old mice. At 0, 4, 7, 14, and 21 days after surgery the mice received injections intraperitoneally of 3H-thymidine, 3H-uridine, and 3H-proline. In each mouse two wounds were examined histologically. Four wounds were excised and the epithelium was separated enzymatically from the connective tissue. After sequential separation of RNA, DNA, and protein, one aliquot from each sample was taken for scintillation counting and another for quantitative determination of RNA, DNA, and protein. The ratios of newly synthesized DNA and RNA to total DNA and RNA were greater in wounds on older mice. After the mice were wounded the protein synthesis decreased initially in both groups. However, J Dent Res Supplement to No. 5 ABSTRACTS, DIVISIONS AND SECTIONS 1307S, DIVISIONS AND SECTIONS 1307 between the fourth and seventh days it had increased in young mice, but remained low in the old mice. The number of fibroblasts was considerably less in older mice. The results indicate that the connective tissue cells in old mice replicate themselves more frequently than those in young mice, and that fibroblasts of old mice are less capable of synthesizing tropocollagen. 1 1. DISTANT COLLAGEN RESPONSE AFTER TRAUMA AND PREGNANCY.-P. Holm-Pedersen, A. Viidik, and A. Rundgren, Department of Periodontology, Royal Dental College, Aarhus and Institute of Anatomy, University of Aarhus, Denm