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PubMed1989

Apical migration of the junctional epithelium in the human primary dentition as a multifactorial phenomenon.

Apical migration of the gingival junctional epithelium and/or attachment loss in the human primary dentition have been reported in the literature. The findings of several histological, in vitro and radiographic studies are summarized and related to the etiology of this phenomenon. An hypothesis that apical migration of the junctional epithelium, in the human primary dentition, is the result of a combination of the qualitative characteristics of the inflammatory cell infiltrate, passive eruption and the shedding process is presented.

Cell Movement↗
PubMed2002

Behavior of epithelial root sheath during tooth root formation in porcine molars: TUNEL, TEM, and immunohistochemical studies.

The behavior of epithelial cells during tooth root formation in porcine molars was investigated using TUNEL, immunohistochemical and transmission electron microscopic methods. Cells of Hertwig's epithelial root sheath (HERS) expressed bcl-2, but were TUNEL-negative. Epithelial cells of HERS were tightly connected and surrounded by a continuous basement membrane. When dental papilla cells were attached to the inner HERS, they became positive for osteopontin (OPN). The inner basement membrane was intermittent immediately after those cells started to synthesize dentin matrix, and the intercellular spaces of the HERS became wider. Dental sac cells then migrated between the fragmented HERS and were directly connected to epithelial cells by desmosome-like structures. After the cementum was synthesized by these mesenchymal cells, epithelial cells aggregated to form cell clusters, which were again surrounded by a continuous basement membrane. These results suggest that fragmentation of the HERS is due to the invasion of dental sac cells, but is not related to cell death. Furthermore, the differentiation of dental papilla cells into odontoblasts occurred following their connection to the HERS through the basement membrane. Moreover, it is suggested that the differentiation of dental sac cells into cementoblasts occurred upon their direct connection to epithelial cells of the HERS.

Animals↗
PubMed1986

An experimental study of timing and topography of early tooth development in the mouse embryo with an analysis of the role of innervation.

The putative involvement of the innervation in determining the sites of dental development was investigated by intra-ocular homografting and organ culture methods. Mandibular arches were dissected from 9 and 10-day-old (E9-E10) mouse embryos and grafted to the anterior eye chambers of homologous adult mice for 12-14 days. There was no significant difference in the incidence of tooth formation between grafts in which the trigeminal ganglion was included (n = 82, 68 per cent) or excluded (n = 72, 65 per cent). A parallel in vitro study in which E9 and E10 mouse embryo mandibular arches were cultured in the absence of trigeminal innervation showed that definitive tooth germs were formed during the 7-9 day culture period. It is concluded that innervation plays no part in determination of tooth development. In further experiments with E9 and E10 material, the complete mandibular arch, the hemimandibular arch and the ventral midline region of the mandibular arch (including the median epithelial isthmus) were each grafted for a period of 21 days. Alizarin-red whole-mount staining of recovered grafts revealed that bone had been deposited and mineralized in the majority of grafts of all types. Incisor and molar teeth with near normal crown shapes developed in grafts of complete mandibular arches. Hemimandibular arches gave rise almost exclusively to molars. Grafts of the E10 ventral midline region gave rise exclusively to incisors, but the same graft performed at E9 did not produce teeth. It is concluded that incisor primordia are localized in or near the median epithelial isthmus (and are thus destroyed or damaged when the mandibular arch is hemisected) and that incisors are not determined until E10. At E9 the odontogenic neural crest has yet to complete its ventrad migration into proximity with presumptive incisor epithelium. By this time, however, odontogenic crest and presumptive molar epithelium have already reached juxtaposition and molar primordia are fully competent. In grafts of the frontonasal and maxillary processes made at E10, prior to merging of their respective mesenchymes, frontonasal processes gave rise exclusively to incisors, whereas maxillary processes gave rise exclusively to molars.

Animals↗
PubMed1989

Immunological characterization, developmental pattern and vitamin-D-dependency of calbindin D-28 K in rat teeth ameloblasts.

It has been suggested that vitamin D is involved in the process of cell differentiation and extracellular mineralization during tooth development. One of the best-defined molecular markers of the action of vitamin D is a calcium-binding protein of Mr 28,000 called calbindin D-28 K (CaBP 28 K). Since this protein is present in growing teeth, we have examined its synthesis in teeth from vitamin D-replete and -deplete rats by Western blotting and immunocytochemistry with an antiserum to CaBP 28 K purified from rat kidney. The CaBP 28 K present in the enamel organ is a single molecular species migrating near 30 k Da, similarly to the kidney protein. The differentiation and maturation of odontogenic cells were followed during early postnatal development (2-12 days) in rat molars. At the light-microscope level, CaBP 28 K was only found in a single cell-type, the ameloblasts. The expression of this protein appeared to be developmentally controlled, since its distribution varied with the cell stage and the functional steps of amelogenesis. The protein was localized in the basal compartment of ameloblasts from the presecretory stage. During the early secretory stage, the concentration of cytoplasmic CaBP 28 K formed a gradient from the apical to the basal pole of the ameloblasts. Staining appeared homogeneous in the cytoplasm of later secretory ameloblasts. CaBP 28 K was discontinuously distributed during the maturation stage. This discontinuity might be related to cyclical changes in mature ameloblasts. In all stages, ameloblasts from vitamin-D-deficient rats appeared depleted of CaBP 28 K.

Ameloblasts↗
PubMed1981

Ratio of alpha-1-antitrypsin to transferrin in gingival fluid and in blood from patients with periodontal disease.

In 30 men and 29 women the mean gingival exudate ratio alpha-1-antitrypsin (A1AT)/transferrin (Tr) was higher than the mean blood ratio for A1AT/Tr, when determined by double electroimmunoassay. It suggests that A1AT penetrates the tissue more easily than transferrin probably due to its smaller molecular size or that migration into the extracellular space occurs due to consumption by proteolytic enzymes. The gingival exudate ratio and the blood ratio for A1AT/Tr were not related to periodontal disease when considered separately. However, the difference between the exudate ratio and the corresponding blood ratio was significantly less (P = 0.02) for individuals with periodontal disease. This suggests that the ratio difference is of importance in the destruction of tooth-supporting collagen fibers.

Adult↗
PubMed1995

The early distribution and possible role of nerves during odontogenesis.

Neural crest cells migrate along specific pathways to reach the mandibular and maxillary arches where they condense under specific areas of the ectoderm which will give rise to the primary and permanent dentition. In the mouse, the trigeminal ganglion becomes evident on E9 and the superior cervical sympathetic ganglion E13. Several studies have suggested that nerves in the vicinity of the developing teeth could influence the surrounding tissues and initiate tooth development, whereas other investigators have suggested that tooth development will proceed without an intact innervation. Innervation of the dental papilla has been reported as early as the cap stage in human teeth using an antibody to PGP 9.5. A large variety of putative neurotransmitters have been localized in the nerves of the dental pulp. Many of the putative neurotransmitters function in vasoregulation while others have unknown functions. A hypothesis is presented describing a possible signal transduction pathway between odontoblasts and nerve terminals.

Animals↗
PubMed1993

In vitro study of the penetration of three bacterial strains into root dentine.

The purpose of this study was to assess in vitro migration of the following three bacterial species into dentinal tubules: Streptococcus sanguis, Actinomyces naeslundii and Prevotella intermedia. Twenty-seven bovine incisors were randomly divided into three groups. Only the root dentin was used for the experiment. Within each group, the nine incisors were sectioned into 36 dentin blocks that were incubated with one of the tested bacterial suspensions. Twelve samples were taken after 10, 20, and 28 days. Half the samples were observed with scanning electron microscopy and the others with light microscopy after standard histologic procedures, and the depth of bacterial penetration was measured. Analysis of the examinations showed that whatever the technique used, only one strain on this experimental model migrated into dentinal tubules. S. sanguis was observed at a depth of 792 microns, but no migration was observed for either A.naeslundii or P.intermedia. The differences in migration of the bacteria tested appear to be related to their morphologic factors and cellular arrangement.

Actinomyces↗
PubMed2001

[Periodontitis: a hidden chronic infection].

Periodontitis is a chronic inflammatory disease of the tooth supporting tissues which has a prevalence of 35% in the adult population. Risk factors are dental plaque, calculus, smoking, diabetes mellitus, stress and genetic traits. In parallel with chronic intestinal inflammatory diseases and stomach cancer, gene polymorphisms in the interleukin-I gene family are associated with severity of periodontitis. Periodontitis is usually painless. Symptoms of the disease are bleeding, redness and swelling of the gums, suppuration and migration of teeth. Halitosis may be present. Treatment of periodontitis involves supra- and subgingival mechanical debridement, oral hygiene instruction and surgical elimination of residual deepened and bleeding pockets on indication. Microbiological testing can be used to select patients who may benefit from additional systemic antimicrobial therapy. Periodontal lesions may act as a portal of entry for dissemination of periodontal bacteria into the blood stream, which may result in extraoral infections. For this reason it is recommended to include diagnosis of periodontitis in focal examination. Associations have been documented between periodontitis and cardiovascular diseases, arthritis and premature low birth weight infants.

Adult↗
PubMed1994

Evaluation of a hydroxylapatite (HA)/resorbable suture implant for alveolar ridge augmentation.

A new type of hydroxylapatite (HA) particle configuration and implant system for alveolar ridge augmentation was investigated. The PermaRidge implant system was designed to provide better HA particle handling and retention characteristics. Torous-shaped particles were bound together with resorbable sutures into rope-like bundles. The implants were placed as a single unit rather than as individual particles delivered via syringe. Six adult beagle dogs underwent bilateral mandibular tooth extraction. After an eight-week healing period, the animals had PermaRidge implants placed on the right side and HA particles alone placed on the left side. Two animals were killed at each of four, eight, and 16 weeks post-operatively. Radiographically, the PermaRidge implants maintained initial augmentation height throughout the course of the study. There was no compaction of the implant or problems with containment and migration of the HA particles. The HA particles alone demonstrated an approximate 25% decrease in augmentation height with time in situ. The majority of augmentation height was lost within the first four weeks post-operatively. There was also significant particle compaction and migration present in the implant sites. Histologically, the PermaRidge implants demonstrated bone growth into the augmentation, often extending 2-3 particle diameters (2-3 mm). The remainder of the implant was filled with dense connective tissue. There was intimate contact of the ingrown bone with the HA surface. The HA particles alone demonstrated minimal bone ingrowth, with extensive fibrous tissue infiltration. The results indicate that the PermaRidge implant system may provide a viable alternative to HA particles alone for the augmentation of the deficient alveolar ridge.

Alveolar Ridge Augmentation↗
PubMed1995

Current controversies in late incisor crowding.

Although the terminology is mildly controversial, late incisor crowding (tertiary crowding, late secondary crowding, post-adolescent crowding) is widely regarded as a normal maturation event which is likely to affect most individuals to some extent. Disagreement arises when attempts are made to quantify the change and to predict the timing of the crowding. Most young adults experience some degree of loss of incisor alignment, usually near the anticipated emergence time for the third molars, and almost characteristically it is the lower anterior teeth which best demonstrate the phenomenon. Unfortunately, the physiological crowding changes are frequently confused with orthodontic treatment relapse. Greater controversy surrounds the aetiology of the undesirable crowding changes and despite many attempts we are still not in the enlightened position of explaining, predicting or preventing the problem (except by permanent retention). It is illogical to assume a single cause as the beguilingly simple observation of crowding belies the complexity of possible interacting factors. Perhaps it is a capricious combination of: tooth size and arch form; facial growth pattern (differential soft tissue and skeletal maturation); continuing late growth rotations; cumulative effects of resting, functional and parafunctional soft tissue pressures; lack of compensating attrition; and an ill-defined, mesially acting force emanating from the back of the dental arch. Many theories have attempted to resolve the mystery of the mesially acting force, including: pressure from erupting third molars; an inherent mesial migration; continuing mesial and occlusal dental drifting; maturation and contraction of periodontal soft tissues (particularly the transseptal fibres); the anterior component of occlusal forces; and the lower anterior arch contracting influence of the incisor overbite.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Heparan sulfate and fibronectin improve the capacity of collagen barriers to prevent apical migration of the junctional epithelium.

The objective of the present study was to assess the effect of bilayered/collagen barriers enriched with fibronectin and heparan sulfate on the prevention of apical migration of the epithelium during the initial stage of periodontal wound healing. Experimental osseous defects were produced on the labial aspect of maxillary canines in dogs. Experimental sites were treated with either bilayered enriched collagen barriers or with non-enriched bilayered collagen barriers, using the guided tissue regeneration technique. Control sites were treated with monolayered collagen barriers that were not enriched with fibronectin and heparan sulfate. Histologic and histomorphometric examinations performed on specimens obtained 20 days post-operative indicate the formation of a short junctional epithelium in the experimental sites treated with enriched collagen barriers. In this group, 95% of the occlusal-apical length of the defects was repopulated by connective tissue cells. In the other 2 groups, a long junctional epithelium developed with only 65% of the occlusal-apical length of the defects being repopulated by connective tissue cells. These findings suggest that the enrichment of collagen barriers with fibronectin and heparan sulfate may be important to enhance the repopulation of exposed root surfaces by connective tissue cells and prevent the apical migration of the epithelium during the initial stages of periodontal wound healing.

Alveolar Process↗
PubMed1992

Formation of new periodontal attachment apparatus after experimental root isolation with collagen membranes in the dog.

This study evaluated the ability of collagen membranes to act as biodegradable barriers that interfere with colonization of the root surface by gingival cells and allow selective repopulation of the denuded root surface by periodontal ligament-derived tissue. Over a 3-year period, experimental and control surgical procedures were performed on canine teeth in six beagle dogs and on premolars in three beagle dogs. Results showed that the membranes partially prevented apical migration of epithelium during healing. Regeneration of new cementum, alveolar bone, and periodontal ligament-like tissue was found in the studied premolars but notably absent on the canines.

Animals↗
PubMedDate not supplied

[Optimization of devices for antibiotic phoretic physiotherapy on the basis of a two-barrier model of diffusion and diffusion-osmotic migration of antibiotic anions].

One-, two-, three-, and four-component low-amplitude field phoretic effects on permeability of placental and muscular biological barriers to levomycetin, benzylpenicillin, and oxacillin anions were studied. Experimental data on exposure to constant electric fields, sinusoidal alternating magnetic field, thermal heating, and vibroacoustic and UHF effects were used to determine the mean coefficients of acceleration of antibiotic anion migration through placental and muscular barriers. The effect of physical fields was interpreted in terms of the sensitivity coefficient, total factor of systemic response of human body, and trade-off optimization index. The results of calculation of trade-off optimization index showed that the maximal relative therapeutic efficiency was observed for optimal numbers of combined fields (2-3) both for placental and muscular barriers. The obtained results showed that optimal stimulated migration of antibiotic anions in placental or muscular barrier was already observed in two-component physical fields, such as magnetoelectric, UHF-magnetic, UHF-electric, UHF-vibroacoustic, magnetovibroacoustic, electrovibroacoustic, etc. Clinical use of stimulated anion migration is illustrated by the example of its physiotherapeutic effect in male urology, ophthalmology, dentistry, and dental implantation.

Administration, Topical↗
PubMed2005

Dkk1, -2, and -3 expression in mouse craniofacial development.

The Dickkopf family is important for embryogenesis and postnatal development and growth. Dkk1 is a strong head inducer and knockout of this gene leads to absence of anterior head structures, which are predominantly formed through neural crest migration. During early craniofacial development, Dkk1 to Dkk3 show developmentally regulated expression in a number of elements. However, their expression and roles in late times of craniofacial development are largely unknown. This study focuses on the expression profile of Dkk1-3 on late embryonic and early postnatal stages. It was found that Dkks were involved in a variety of craniofacial developmental processes, including facial outgrowth, myogenesis, osteogenesis, palatogenesis, olfactory epithelium and tooth development; and the expression persisted to postnatal stage in the muscles and bones. Their expression patterns suggest important roles in these processes; further study is warranted to elucidate these roles.

Adaptor Proteins, Signal Transducing↗
PubMed1992

Changes of cytochemical properties in the Golgi apparatus during in vivo differentiation of the ameloblast in developing rat molar tooth germs.

The cytochemical changes of the Golgi stacks occurring concomitantly with cell differentiation were examined in ameloblasts of developing rat molar tooth germs using osmium impregnation and cytochemistry with nicotinamide adenine dinucleotide phosphatase (NADPase), thiamine pyrophosphatase (TPPase), and acid phosphatase (Acpase). NADPase, TPPase, and Acpase activities were already present in the Golgi stacks of the inner enamel epithelial cells, the undifferentiated form of the ameloblast: NADPase activity existed in the medial Golgi cisternae, TPPase activity in the trans Golgi cisternae, and Acpase activity in almost all cisternae and strongly in the trans-most cisterna of the Golgi stack. At this stage, however, osmium deposits after impregnation were not observed in the cisterna of Golgi stacks but were present in some small vesicles. These vesicles were located throughout the cytoplasm. Osmiophilic cisternae in the Golgi stacks were apparent for the first time at the stage when the Golgi apparatus developed and migrated to the region distal to the nucleus with the progression of cell differentiation. These findings indicate that the cis subcompartment of the Golgi apparatus was incomplete in the inner enamel epithelial cells with regard to appearance of its cytochemical property, as compared with the medial and trans subcompartments. It is suggested that the cis compartment of the Golgi stack may be completed only in the last stage of the compartmentalized Golgi organization during differentiation of the ameloblast.

Acid Phosphatase↗
PubMedDate not supplied

Spatio-temporal expression of E-cadherin during human odontogenesis. An immunohistochemical study.

AIMS: In craniofacial development, both morphogenesis and cell differentiation are governed by inductive tissue reactions, which mostly take place between epithelial and mesenchymal tissue. Studies in molecular biology have shown that cell interactions with cell adhesion molecules contribute to cell migration and differentiation. The aim of this study was to investigate E-cadherin expression during normal craniofacial development in human fetuses. METHODS: The study was performed on 7 human fetuses aged between the 9th and the 16th week. Histological sections were subjected to immunohistochemical treatment with anti E-cadherin monoclonal antibodies (diluted 1:100 in PBS). RESULTS: Immunohistochemical methods evidenced E-cadherin expression in the cells of the developing tooth at all stages investigated. Expression was particularly evident in the dental lamina, at the junction between cells of the oral epithelium and those of the enamel organ, in cells of the stellate reticulum and in those of the dental follicle. Reactivity to E-cadherin was also observed in the oral, nasal and lingual epithelium and in the myoblast and osteoprogenitor cells. E-cadherin did not always stain to the same intensity, indicating greater expression in the epithelium and dental lamina. CONCLUSIONS: E-cadherin plays a role in craniofacial development in man, and is present in different morphogenetic processes such as odontogenesis, ossification, mandibular skeletogenesis and myogenesis of the tongue muscles.

Cadherins↗
PubMed1990

Tissue regeneration principles applied to separation of fused teeth.

A two-step surgical procedure for separating a central incisor fused to a supernumerary tooth with a 4-year follow-up is described. The fusion was between the crowns and 3/4 of the root length. The roots were connected by web-like radio-opaque tissue. The periodontal ligament could be followed along the lateral aspect of the roots and was continuous along the base of the web. In the first surgical phase, a full-thickness semilunar flap was raised; a fissure bar was cut along and through the web up to the approximate location of the junctional epithelium and the flap was sutured. It was assumed that cells from the bone surrounding the web and/or connective tissue cells from the flap had migrated into contact with the web hard tissue. This resulted in replacement resorption of the web. The connective tissue replacing the web acted as a septum separating the 2 parts of the root. The distal root was extracted. Resorption continued until most of the web disappeared from the wound. At this point, the remaining layer of web tissue was thin enough to allow repopulation of the resorbed surface with periodontal cells from the buccal and palatal sides of the web. The successful clinical outcome supports the assumption that new attachment consisting of periodontal ligament and cementum was formed following the 2-step surgical procedure. Application of the technique is limited by the width of the fusion rather than by its length.

Child↗
PubMed1996

Absorption of iron by dentin: its role in discoloration.

This study investigated the effect of iron-containing mordants on the discoloration of human dentin. Dentin wafers with intact enamel borders were treated with one of several acid solutions containing iron. After exposure to aqueous sodium sulfide, color change was evaluated colorimetrically. X-ray photoelectron spectroscopy (XPS) and energy dispersive x-ray spectrometry (EDS) were used to probe surfaces for the presence of iron. Changes in surface morphology were evaluated by scanning electron microscopy (SEM). The results indicated that dentin treated by iron-containing solutions always discolored when the sodium-sulfide concentration exceeded 9.7 mM; variability in discoloration occurred below this level. XPS detected iron in enamel but not in dentin, while EDS detected iron in both enamel and dentin. Since XPS probes the upper atomic layers, these results indicate that acid-demineralized dentin absorbs iron; however, a water wash removes iron from the uppermost dentin surface, suggesting that the iron is physically absorbed. When exposed to sodium sulfide, at least some of the iron remaining in the bulk region is able to migrate to the surface to form iron-sulfide compounds. Based on SEM findings, discoloration is associated with the formation of a surface film on dentin.

Absorption↗