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Migration, attachment, and orientation of human gingival fibroblasts to root slices, naked and porous-surfaced titanium alloy discs, and Zircalloy 2 discs in vitro.

Cell migration, attachment, and orientation of cultured human gingival fibroblasts (HGF) were measured in relation to four types of specimens: Ti-6Al-4V alloy discs with either ground surfaces or porous structured surfaces, and Zr alloy discs (Zircalloy 2) with either ground surfaces or surfaces modified by being heated to form a thicker oxide cover. Surface-demineralized and non-demineralized root slices were used as controls. Initial cell attachment was measured by means of a 51Cr assay, and cell attachment and orientation following migration by an assay that measures development of the resulting refractile material in relation to the specimen. No significant difference between initial cell attachment to Ti alloy and control demineralized root slices could be detected after one hr using the 51Cr assay. However, with the second assay, cell attachment and orientation at three, seven, 10, and 14 days were significantly higher in relation to surface-demineralized root slices than to all of the metal discs and the non-demineralized root slices. While cell attachment to the surface-ground Ti alloy discs appeared to be higher than that to the porous-surfaced Ti alloy discs at three days and seven days, cell orientation to the porous-surfaced Ti alloy discs and the non-demineralized root slices at days 7, 10, and 14 was greater than that to all of the other metal discs. These data suggest that surface geometry could affect attachment and orientation of cells in vitro.

Alloys↗

Effect of root conditioning on periodontal wound healing with and without guided tissue regeneration: a pilot study. II. Autoradiographic evaluation.

This investigation deals with the proliferation and migration of the progenitor cells during the healing of closed periodontal wounds. Periodontal surgical defects affecting the bone and dentin were created in four mongrel dogs. The defects were treated with topical applications of citric acid, tetracycline, or sterile water with and without the placement of nonresorbable membranes. The dogs were killed at 1, 3, 7, and 21 days after surgery. One hour before they were killed, they were intravenously injected with tritiated thymidine. Tissues were processed and routinely prepared for autoradiographic studies. Labeled cells were counted at the apical, coronal, and central areas of the defects. Results suggested that the citric acid and tetracycline treatments inhibited cellular proliferation at the initial time periods of 1 and 3 days. At 7 and 21 days, differences between citric acid and tetracycline treatments were minimal, and neither showed any advantage over the application of sterile water. The placement of the nonresorbable membrane demonstrated a trend of increased labeling at 21 days for all three treatments.

Acid Etching, Dental↗

Differential and overlapping expression domains of Dlx-2 and Dlx-3 suggest distinct roles for Distal-less homeobox genes in craniofacial development.

During the development of the vertebrate head, cranial neural crest cells migrate into the branchial arches to form many of the structures of the facial skeleton. These cells follow defined developmental pathways and their fates are determined early. We have isolated and characterized the murine Distal-less homeobox gene Dlx-3 and have performed a comparative analysis of Dlx-3 and Dlx-2 expression during craniofacial development. In contrast to Dlx-2 and other vertebrate Distal-less genes, Dlx-3 is not expressed in the central nervous system and is expressed in a highly restricted region of the branchial arches. Dlx-2 and -3 display temporal and spatial differences in expression in the arches and their derivatives. In later development, these two genes are expressed in both complementary and partially overlapping domains in regions whose development is dependent on epithelial-mesenchymal interactions, such as the developing middle and inner ear, teeth and whisker follicles. The differential expression of Dlx genes in the branchial region suggests that they play key roles in craniofacial patterning and morphogenesis.

Amino Acid Sequence↗

Impaired early bone formation in periodontal fenestration defects in dogs following application of insulin-like growth factor (II). Basic fibroblast growth factor and transforming growth factor beta 1.

Effects of a topically applied growth factor combination on fibroblast migration, collagen fiber formation and bone regeneration were studied in standardized periodontal defects in 4 beagle dogs. Following elevation of facial mucoperiosteal flaps, fenestration defects, 3 mm in diameter, were made through the cortical bone and into the dentin of maxillary and mandibular teeth. Collagen sponges, impregnated with 200 ng insulin-like growth factor II, 20 ng basic fibroblast growth factor and 6 ng transforming growth factor beta 1 were fitted to defects randomly in right or left quadrants and the flaps repositioned and sutured. Contralateral control defects received the collagen with vehicle only. Experimental procedures were staggered to allow observations of healing 3, 7, 10, and 14 days after surgery. Histometric analysis showed no differences in fibroblast and collagen density between control and growth factor defects. Bone regeneration was significantly greater in control than in growth factor defects 10 and 14 days after surgery. The rate of healing generally appeared more affected by intra-dog variations or procedural variations than by the growth factor combination.

Alveolar Process↗

On the origin of intrinsic matrix of acellular extrinsic fiber cementum: studies on growing cementum pearls of normal and bisphosphonate-affected guinea pig molars.

Cementum pearls (CPs) belong to a type of acellular extrinsic fiber cementum (AEFC) that form on the maturing enamel of guinea pig molars. This study aimed to elucidate the forming process of intrinsic matrix of AEFC using the CPs of normal and bisphosphonate-affected guinea pig molars as experimental models. A group of guinea pigs were subjected to continuous administration of 1-hydroxyethylidene-1,1-bisphosphonate (HEBP) for 2 wk to inhibit mineralization of growing CPs. Fenestration of the enamel organ and migration of periodontal cells on to the exposed surface of maturing enamel appeared to be unaffected by HEBP, whereas de novo formation as well as growth of pre-existing CPs did not proceed under the same conditions. Immunoreactions for osteopontin were located exclusively on the mineralized matrix of preformed CPs, implying the absence of additional deposition or accumulation of putative intrinsic cementum matrix on the affected CPs, where the propagation of mineral phase had been arrested. In both normal and HEBP-treated groups, distinct enzymatic reactions for alkaline phosphatase appeared on the cells of the periodontal ligament associated closely with the sites of CP formation, and along the mineralization front of CPs. These observations suggest that the mineralization process per se plays a central role in the deposition of AEFC matrix and that alkaline phosphatase of periodontal cells penetrating through the enamel organ to the maturing enamel surface plays a key role in the mineralization process of CPs.

Alkaline Phosphatase↗

Differentials of Yayoi immigration to Japan as derived from dental metrics.

A major influx of new people, today termed Yayoi, migrated from the East Asian continent into the Japanese archipelago during the Aeneolithic and Protohistoric periods and interbred with the preexisting Jomon people. This study classifies ancient and more modern Japanese into natives or immigrants using discriminant analysis based on dental measurements in order to reconstruct the initial impact of the immigrants and the temporal and geographical differentials of mixture with the preexisting people. The results suggest that the earliest immigrants diffused into central Japan, including the Kanto region. The proportion of immigrant origin in the protohistoric Kofun was less in eastern Japan (72%) as compared to western Japan (81%-90%). The proportion of the immigrants in the Kanto District decreased during the medieval period (63%) and increased again in the early modern Edo and later modern times (75%), which might indicate that the gene flow still was occurring from west to east even in these times. Assuming the estimated proportions of either group reflect the intermixture ratio, the recent Japanese people may be regarded as hybrid of the native and immigrant groups with the following approximate ratios: 1:3 for the Kanto Japanese, 2:3 for the Ryukyu Islanders and 7:3 for the Hokkaido Ainu. These estimations support the "dual structure model" formed by Hanihara (1991) for explaining the population history of Japan.

Anthropology, Physical↗

Cell-surface proteoglycan expression by lymphocytes from peripheral blood and gingiva in health and periodontal disease.

Cell-surface proteoglycans are involved in lymphocyte migration and activation. This study investigated the expression of syndecan-1, syndecan-4, and glypican in peripheral blood lymphocytes and by lymphocytes in variously inflamed periodontal tissues. Gingival specimens from healthy, gingivitis, or chronic periodontitis sites were stained by means of antibodies against B- and T-lymphocytes and also syndecan-1, syndecan-4, and glypican. Syndecan-1 expression by peripheral blood mononuclear cells (PBMC) from healthy, gingivitis, and chronic periodontitis subjects was assessed by flow cytometry. Syndecan-1 was expressed by B-cells/plasma cells but not T-cells in both gingivitis and chronic periodontitis lesions. Both B-cells/plasma cells and T-cells in gingivitis and chronic periodontitis expressed syndecan-4. Glypican was expressed only by macrophages. Stimulation of PBMC with mitogens and growth factors modulated syndecan-1 expression in both the T- and B-cells. Thus, cell-surface proteoglycan expression by lymphocytes in periodontal inflammation is cell-type-specific and may be modulated by inflammation.

Adult↗

The modulatory role of cementum matrix on osteoblastic cells in vitro.

The formation of new cementum is an important issue in clinical periodontology, as cementum is required to provide attachment for newly formed periodontal tissues to the root surface. In this study a model of cementogenesis in vitro was used in order to test the effects of root surface demineralization on the migration, attachment and formation of a cementum-like tissue by osteoblastic cells cultured on cementum and to test the specificity of cementum matrix in modulating those effects by comparison of root co-cultures with bone co-cultures. It was demonstrated that root surface demineralization did not significantly alter the orientation, number and attachment of cells to the root co-cultures. The results also demonstrated that cementum and bone matrix appear to behave differently in culture, as seen by their distinct action on the morphological profile of the attached cells and the extracellular matrix deposited by these cells. These results demonstrate that although cementum matrix appears to stimulate the production of cementum-like tissue, this action is not confined to cementum matrix alone, since a similar material was also deposited on dentine and bone surfaces. Thus, these results do not support a specific action of cementum matrix on the modulation of the cementoblast phenotype. The use of co-cultures of neonatal rat calvaria cells with root slices represents a promising model of cementogenesis in vitro; however, studies should be undertaken towards the identification of markers to distinguish between cementoblast and osteoblast phenotypes in order to further validate this model.

Animals↗

Attempts to label matrix synthesis of human root cementum in vitro.

The present study describes the dynamic process of both acellular extrinsic (AEFC) and acellular/cellular intrinsic fiber cementum (AIFC/CIFC) matrix production on growing human teeth. Selected erupting maxillary and mandibular premolars with roots grown to about 70%-95% of their final length were placed in organ culture immediately following extraction. Twelve teeth for short-time labeling were pulse-incubated for 15 min in medium containing 3H-proline and chased for various times in order to follow the migration and secretion of the tracer. Eight teeth for long-time incubation were labeled continuously for 5 h before being chased for 1-8 days in order to label cementum matrix accumulation. After decalcification in ethylene diaminetetraacetic acid (EDTA), their roots were subdivided into about 20 slices each. Epon-embedded sections were prepared for light- and electron-microscopic as well as autoradiographic examination. During CIFC-formation, cementoblasts revealed high intracytoplasmic silver grain concentrations within the first hour after 3H-proline administration. The release of the tracer occurred between 60 to 120 min after administration. After 2 h, cementoblasts and the cementum matrix appeared to be labeled about equally. After 5 h, most of the labeled proteins appeared to be localized in the cementoid. Silver grains increased in number over the cementum matrix from 5-24 h. Very high intracellular grain concentrations within very large cementoblasts corresponded to regions of rapid cementum formation. Tracer-halos around entrapped cells lend support to a multipolar mode of matrix production during CIFC-initiation. The fate of the tracer during the development of early AEFC-matrix was less clear. However, fibroblasts revealed dense intracytoplasmic grain accumulations within the first hour after 3H-proline administration. Thereafter, the tracer localization was vague. This indistinct grain localization reflected the particular mode of AEFC-matrix production characterized by addition of new fibril segments to pre-existing fibers of a collagenous fringe.

Adolescent↗

Histologic evaluation of new attachment apparatus formation in humans. Part III.

There is still controversy as to the role of bone grafting materials in the formation of a new attachment apparatus and component tissues (bone, cementum, and periodontal ligament). The purpose of this study was to compare the healing of intrabony defects with and without the placement of decalcified freeze-dried bone allograft (DFDBA) in a nonsubmerged environment in humans. The most apical level of calculus on the root served as a histologic reference point to delineate root surfaces exposed to the oral environment and to measure new attachment apparatus and new component tissue formation. Free gingival grafts were placed over grafted and nongrafted defects to retard epithelial migration. Biopsies were obtained at 6 months and regeneration was evaluated histometrically. Data from 12 patients with 32 grafted and 25 nongrafted defects were submitted for statistical analysis. Results indicate that in nongrafted defects, a long junctional epithelium formed along the entire length of exposed root surfaces and often extended apical to the calculus reference notch. Free gingival grafts did not enhance regeneration of a new attachment apparatus, new cementum, new connective tissue, or new bone in nongrafted defects. The formation of a new attachment apparatus was observed when intrabony defects were grafted with DFDBA (x1.21 mm); significantly more new attachment apparatus (P less than .005), new cementum (P less than .005), new connective tissue (P less than .05), and new bone (P less than .0001) formed in intrabony defects grafted with DFDBA than in nongrafted defects. There was a greater chance for regeneration of a new attachment apparatus and component tissues in grafted defects than in nongrafted defects. New cellular cementum formed on old cementum and dentin but more often formed over both in the same defect). The periodontal ligament was more frequently oriented perpendicular to the root; there was greater loss in alveolar crest height in nongrafted than grafted defects (P less than .05); and extensive root resorption, ankylosis, and pulp death were not observed in grafted or nongrafted defects.

Analysis of Variance↗

The effect of platelet-derived growth factor on the cellular response of the periodontium: an autoradiographic study on dogs.

Platelet-derived growth factor (PDGF) is a polypeptide growth factor considered to have a role in the proliferation and migration of fibroblasts at a wound healing site. The aim of this investigation was to determine if PDGF, when applied to root surfaces, would stimulate the proliferation of fibroblasts and further enhance regeneration. Six mongrel dogs with healthy periodontia were selected for this study. Using a closed wound surgical model, standardized 4 x 4 mm fenestration defects were created into dentin on the mid-facial of the mesial and distal roots of 4 mandibular posterior teeth in each quadrant. Each defect received either: 1) saline solution (C); 2) expanded polytetrafluoroethylene (ePTFE) membrane; 3) PDGF; or 4) ePTFE + PDGF. 3H-thymidine was administered 1 hour prior to animal sacrifice at 1, 3, and 7 days postsurgery. Each time period included 2 dogs with each dog undergoing the four different treatments. Slides were prepared for autoradiography. 3H-thymidine-labeled cells were counted and results were statistically analyzed using the Bonferroni (Dunn) t test on the SAS program. Results indicated PDGF enhanced fibroblast proliferation when compared to the groups without PDGF. Significant differences (P < 0.05) were noted at day 1 and 7 when PDGF and PDGF + GT were compared to C and GT groups. No significant differences were observed in labeled fibroblasts between the C and GT groups at any time period. These findings suggest that PDGF enhances fibroblast proliferation in early periodontal wound healing, whether used alone or in combination with the ePTFE membrane.

Analysis of Variance↗

The role of serotonin and neurotransmitters during craniofacial development.

Several neurotransmitters, in particular serotonin (5-HT), have demonstrated multiple functions during early development and mid-gestational craniofacial morphogenesis. Early studies indicated that 5-HT is present in the oocyte, where it appears to function as a regulator of cell cleavage. Later, it has a significant role during gastrulation, during which there are significant areas of 5-HT uptake in the primitive streak. Subsequently, in association with neurulation, 5-HT uptake is seen in the floor plate of the developing neural tube. During neural crest formation and branchial arch formation, 5-HT has been demonstrated to facilitate cell migration and stimulate cell differentiation. During morphogenesis of the craniofacial structures, 5-HT stimulates dental development and may aid in cusp formation. All of the most commonly prescribed antidepressant drugs inhibit serotonin uptake, yet they do not appear to cause major craniofacial malformations in vivo. Given the wide spectrum of effects that 5-HT has during development, it is difficult to understand why these anti-depressants are not major teratogens. Redundancy within the system may allow receptor and uptake pathways to function normally even with lower than normal levels of circulating serotonin. Serotonin-binding proteins, that are expressed in most craniofacial regions at critical times during craniofacial development, may have a buffering capacity that maintains adequate 5-HT tissue concentrations over a wide range of 5-HT serum concentrations. Dental development appears to be particularly sensitive to even small fluctuations in concentrations of 5-HT. Therefore, it may be that children of patients who have received selective serotonergic re-uptake inhibitors (such as Prozac and Zoloft) or the less selective tricyclic anti-depressant drugs (such as Elavil) would be at a higher risk for developmental dental defects such as anodontia and hypodontia. In this review, the evidence supporting a role for 5-HT during mammalian craniofacial development is discussed. A series of models is proposed that may explain how the craniofacial effects of 5-HT are mediated.

Animals↗

A quantitative analysis of the migration, attachment, and orientation of human gingival fibroblasts to human dental root surfaces in vitro.

The purpose of this study was to assess the migration, attachment, and orientation of human gingival fibroblasts to human dental roots over a period of 21 days in vitro. The fibroblasts were incubated with a total of 120 periodontally diseased and non-diseased root slices (200 microns thickness) which had been treated in the following manner: 1) Root planed diseased root (DT); 2) Root planed and citric acid demineralized diseased root (DTD); 3) Non-treated diseased root (DNT); 4) Citric acid demineralized diseased root (DNTD); 5) Non-diseased control (ND); 6) Citric acid demineralized non-diseased root (CA); 7) Citric acid and collagenase digested non-diseased root (CAC); 8) EDTA demineralized non-diseased root (E); and 9) EDTA-demineralized and collagenase-digested non-diseased root (EC). The results showed that that most active phase of cell attachment and orientation occurred during the first 10 days of the experiment. Statistical differences were observed between the variables, and, in terms of cell attachment and orientation to the root slices, it was concluded that: 1) Root planing improves diseased roots; 2) Acid demineralization subsequent to root planing improved diseased roots to such an extent as to render them comparable to non-diseased roots; 3) Citric acid demineralization alone improved diseased roots to the same extent as root planed diseased roots; 4) The exposure of collagen fibrils resulting from acid demineralization of the tools is not the sole reason for the improvement of the root surface, but rather a combination of the exposed collagen fibrils with the creation of a more hospitable environment was found to be responsible.

Cell Adhesion↗

A study of attached and oriented human periodontal ligament cells to periodontally diseased cementum and dentin after demineralizing with neutral and low pH etching solution.

BACKGROUND: This study aimed to evaluate quantitatively the migrated, attached, and oriented human periodontal ligament cells (HPLC) to periodontally diseased cementum and dentin after demineralization with low and neutral pH etching solution. METHODS: Human teeth, extracted due to periodontal diseases, were scaled and root planed so that cementum remained on one longitudinal half of the root and dentin was exposed on the other half. Forty root slices of 200 microm thickness, obtained from the mid-third of these roots, were divided into four groups: group 1, demineralized with a saturated solution of citric acid (pH 1.20); group 2, with 24% EDTA (pH 7.04); group 3, with tetracycline HCl 100 mg/ml (pH 2.00); and group 4, only scaled and root planed (control). Root slices were placed over the confluent HPLC in 35 mm culture dishes and incubated. Phase contrast microscopic photographs of attached and oriented refractile HPLC to root surfaces were taken at days 1, 3, and 7. Quantitative analysis of attached and oriented HPLC from these photographs was done using special software. RESULTS: The results showed no significant difference in the attachment and orientation index of HPLC to cementum compared to dentin in any method of demineralization at each time point (P >0.05), although there was a significantly higher cell attachment and orientation index to demineralized dentin with EDTA and citric acid than to non-etched dentin and to all 3 demineralized cementum surfaces compared to non-etched cementum (P<0.05). CONCLUSIONS: EDTA and citric acid demineralization may enhance HPLC attachment and orientation to the root surface, and it is not always necessary to remove excessive cementum when the demineralizing procedure is used.

Cell Adhesion↗

Response to activator treatment in Class II malocclusions.

A clinical study was designed to disclose the effects of activator treatment in the correction of Class II malocclusions. The rationale for the use of the activator appliance was based on the premise that correction of distocclusion can be achieved by inhibition of forward growth of the maxilla, inhibition of mesial migration of maxillary teeth, inhibition of maxillary alveolar height increase and extrusion of mandibular molars, increased growth of the mandible, anterior relocation of the glenoid fossa, mesial movement of mandibular teeth, and combinations of these effects. The appliance, as designed for this study, could potentially have an effect on all of these factors. Measurements were obtained from cephalometric head films obtained at 6-month intervals. Matched-pairs analyses of control versus treatment change after 6 months and after 1 year of treatment were done on 36 and 29 pairs, respectively. Pretreatment versus treatment changes were analyzed on 33 subjects by means of the spline regression analysis; posttreatment versus treatment changes were analyzed on 18 subjects by means of the Student Newman-Keuls multiple comparison test. The matched-pairs analyses of mean values demonstrated significant reduction in forward growth of the maxilla, uprighting of the maxillary incisors, reduced overjet, leveling of the mandibular occlusal plane, improved molar relationship, downward and forward relocation of the glenoid fossae, increased advancement of all mandibular structures, increased face profile angle, and increased lower face height. The two longitudinal analyses yielded similar findings, but some differences were noted. Because rather severe dental malocclusions were corrected, the slight average inhibition of maxillary growth and the anterior relocation of glenoid fossae alone could not account for the correction of the Class II dental arch relationship. It was therefore concluded that, in addition to the statistically significant changes, smaller changes occurred in several areas without being consistent enough or of a large enough magnitude to become statistically significant in the analyses of mean values. Comparison of group averages may mask treatment effects that significantly contribute to the correction of malocclusions in individual cases.

Activator Appliances↗

Five-year evaluation of implants placed at extraction and with dehiscences and fenestration defects augmented with ePTFE membranes: results from a prospective multicenter study.

BACKGROUND: Barrier membranes have been used to promote bone ingrowth on implants with dehiscences and fenestrations. Membranes also have been used to protect defects adjacent to implants placed at the time of extraction. The concept of guided bone regeneration relates to preferentially allowing cells from bone to migrate into various defects while excluding fibrous tissue and epithelium. The purpose of these procedures is to enhance bone-to-implant contact at the treated sites and to prevent mucosal complications. PURPOSE: The purpose of this article is to report clinical outcomes for implants placed at the time of extraction and augmented with expanded polytetrafluoroethylene (ePTFE) and followed for 5 years. The outcomes for implants with dehiscences and fenestrations augmented with ePTFE barriers and followed up to 5 years also are reported. METHODS AND MATERIALS: Four treatment centers participated in this study (Tucson, Gothenburg, Spokane, and Leuven). In the extraction group, teeth were removed for varying reasons, and Brånemark implants were placed and stabilized within the host bone. Defects present at the coronal implant aspect were covered with ePTFE barrier membranes. Flaps were rotated to cover the membrane-treated sites. If exposure of the material occurred prior to second-stage surgery, the membranes were removed. Barriers remaining unexposed were removed at second-stage surgery. The implants were followed up to 5 years. In the fenestration and dehiscence group, implants with exposed threads were augmented with ePTFE barrier membranes. The barriers were removed at appropriate intervals, and the patients were followed up to 5 years. Radiographic measurements were made from nonstandardized periapical radiographs at abutment connection and 1, 3, and 5-year follow-up visits. RESULTS: Forty patients participated in the extraction group. They received a total of 49 implants. Three implants failed prior to loading. The 5-year cumulative survival rates for implants placed at the time of extraction were 93.9% and 93.8%, respectively, for maxillary and mandibular implants. The average maxillary mesial and distal marginal bone loss (1-5 yr) was 0.3 mm (standard deviation [SD] = 1.5) and 0.3 mm (SD = 1.0). In mandibles, the average mesial and distal bone loss (1-5 yr) was -0.2 mm (SD = 0.5) and -0.05 mm (SD = 0.6), respectively. The dehiscence and fenestration group included 44 patients. Twenty-six were followed for up to 5 years. Eight patients experienced total implant failure. For dehiscences and fenestrations, the cumulative survival rates were 76.8% and 83.8% for maxillary and mandibular implants, respectively. The average maxillary mesial and distal bone loss (1-5 yr) was 0.4 mm (SD = 0.8) and 0.2 mm (SD = 0.9), respectively. In mandibles, the average mesial and distal marginal bone loss was 0.3 mm (SD = 0.9) and 0.3 mm (SD = 0.8), respectively. CONCLUSIONS: Implants placed at the time of extraction and augmented with ePTFE barrier membranes have favorable long-term predictability. On the other hand, long-term evaluation of implant dehiscences and fenestrations augmented with barrier membranes indicates that they have less favorable 5-year survival rates. Membrane augmentation of these may be questioned.

Adolescent↗