Adjacent Alveolar Bone Research Articles

Morphological and functional rehabilitation of severely infra-occluded primary molars in the presence of aplasia of the permanent premolar: A clinical report

This clinical report describes the fixed prosthodontic rehabilitation of an infra-occluded primary molar. Diagnostic considerations included the patient's age, occlusal status, condition of the infra-occluded tooth including the degree of infra-occlusion and root resorption, as well as adjacent alveolar bone levels. Due to the patient's young age, an invasive prosthetic approach was delayed in favor of an onlay restoration, which represented a more rapid and conservative therapeutic choice. The treatment involved the design and fabrication of a composite onlay on the deciduous molar using a ceramic optimized polymer on a fiber-reinforced composite framework. Three years later, intraoral radiography showed satisfactory marginal adaptation. No change was observed in periodontal tissues.

Management of Periodontitis Associated with Endodontically Involved Teeth: A Case Series

The pulp and the periodontal attachment are the two components that enable a tooth to function in the oral cavity. Lesions of the periodontal ligament and adjacent alveolar bone may originate from infections of the periodontium or tissues of the dental pulp. The simultaneous existence of pulpal problems and inflammatory periodontal disease can complicate diagnosis and treatment planning. The function of the tooth is severely compromised when either one of these is involved in the disease process. Treatment of disease conditions involving both of these structures can be challenging and frequently requires combining both endodontic and periodontal treatment procedures. This article presents cases of periodontitis associated with endodontic lesions managed by both endodontic and periodontal therapy.

Cell transplantation in wounded mixed connective tissues

Direct transplantation of multipotent precursor cells into the periodontium could provide a therapeutic approach for restoring periodontal tissues destroyed by periodontitis or trauma. To improve the understanding of cell migration, proliferation, and differentiation, we used a rodent model combining orthodontic tooth movement and transplantation of Lac-Z-positive murine-cultured periodontal ligament (PL) or femur-derived bone marrow precursor cells into a defined mandibular wound site, thus promoting tissue regeneration in wounded periodontium. Our results show that in orthodontically traumatized tissues, transplanted PL and bone marrow cells migrated systemically, contributing to the repopulation of sites with reduced cell/matrix density. The transplanted PL cells proliferated in adjacent alveolar bone marrow spaces, thus migrating to vascular tissues in the PL. The capillary walls in the PL serve as delivery sites for these cells and other marrow-derived hematopoietic cells, including monocytes. The transplanted marrow cells, extracted from femur of transgenic (TgR) mice exhibited similar behavior to those of transplanted PL cells, showing high proliferative activity in alveolar marrow as well as intensive repopulating capacity in wounded periodontium. On the other hand, the buccal skin fibroblasts failed to migrate and home effectively and thus the transplantation of these cells had no effect on periodontium regeneration. Based on these results, we conclude that the transplanted PL and bone marrow cells migrate systemically and following a cyclical process of growth and development and differentiate into PL fibroblasts, osteoblasts, and cementoblasts, thereby contributing to periodontal regeneration.

Long‐term functional loading of dental implants in rhBMP‐2 induced bone

Osseointegration [direct bone-implant contact (BIC)] is a primary goal following installation of endosseous dental implants. Such bone contact provides stability for the dental implant over time. The objective of this study was to evaluate bone formation and BIC at long-term, functionally loaded, endosseous dental implants placed into bone induced by recombinant human bone morphogenetic protein-2 (rhBMP-2) in an absorbable collagen sponge (ACS) carrier. Mandibular, saddle-type, alveolar ridge defects (approximately 15 x 10 x 10 mm), two per jaw quadrant, were surgically induced in each of six young adult American fox hounds. The defects were immediately implanted with rhBMP-2/ACS. Two defects per animal additionally received a nonresorbable expanded polytetrafluoroethylene (ePTFE) membrane or a bioresorbable polyglycolide fiber membrane. Healing was allowed to progress for 3 months, when the ePTFE membrane was removed, and machined, threaded, titanium dental implants were installed into the rhBMP-2/ACS induced bone and into the adjacent resident bone. At 4 months of osseointegration, the implants were exposed to receive abutments and prosthetic treatment (two- or three-unit bridges). Some implants were removed for histologic analysis. The remainder of implants were exposed to functional loading for 12 months at which time the animals were killed for histometric analysis. One animal died prematurely due to kidney failure unrelated to the experimental protocol and was not included in the analysis. The 12-month block sections from a second animal were lost in the histological processing. Four sites receiving rhBMP-2/ACS and ePTFE or resorbable membranes experienced wound failure and membrane exposure, and subsequently exhibited limited bone formation. Defects without wound failure filled to contour with the adjacent alveolar bone. The newly formed bone exhibited features of the resident bone with a re-established cortex; however, it commonly included radiolucent areas that resolved over time. Dental implants block biopsied at 4 months exhibited limited, if any, crestal resorption, whereas those exposed to functional loading for 12 months exhibited some crestal resorption. Implants biopsied at 4 months exhibited a mean (+/- SD) BIC of 40.6 +/- 8.2% in rhBMP-2/ACS induced bone vs. 52.7 +/- 11.4% in resident bone. Dental implants exposed to 12 months of functional loading exhibited a mean BIC of 51.7 +/- 7.1% in rhBMP-2/ACS induced bone vs. 74.7 +/- 7.0% in resident bone. There were no significant differences between dental implants placed into rhBMP-2/ACS induced bone and resident bone for any parameter at any observation interval. In conclusion, rhBMP-2/ACS-induced bone allows installation, osseointegration, and long-term functional loading of machined, threaded, titanium dental implants in dogs.

上顎臼歯部に生じた周辺性歯原性線維腫の１例：腫よう内のオキシタラン線維およびテネイシンの分布

A case of peripheral odontogenic fibroma occurring in the posterior region of the maxilla in a 7-year-old girl is presented. The patient was referred to our hospital because of a painless swelling in the buccal gingiva at 6 1. Physical examination revealed a localized elastic-hard tumor, with no radiological abnormalities in the adjacent alveolar bone. A biopsy specimen showed proliferation of fibroblastic cells in the submucosal layer. With the patient under general anesthesia, the tumor was resected subperiosteally, and the underlying bone surface was smoothened with a bur. Histologically, the lesion was composed of cellular fibrous connective tissue with scattered regions of cellular strands interwoven with less cellular areas and islands of odontogenic epithelium. The final diagnosis was peripheral odontogenic fibroma. Specific staining demonstrated that the tumor stroma contained large amounts of oxytalan fibers and tenascin. A positive reaction for tenascin was found to be a valuable pathohistological marker that could distinguish between peripheral odontogenic fibroma and calcifying fibrous epulis.As of about 9 years after the operation, there has been no evidence of recurrence.

RGD-CAP (betaig-h3) exerts a negative regulatory function on mineralization in the human periodontal ligament.

In our previous studies, RGD-CAP/betaig-h3 was isolated from a fiber-rich fraction of cartilage and was found to have a negative function on mineralization of hypertrophic chondrocytes. However, the expression and biological function of RGD-CAP in the periodontal ligament (PDL) are not known. We hypothesized that RGD-CAP could be expressed in the PDL and regulate its mineralization. To test this, we investigated the expression of RGD-CAP in human PDL and the effects of RGD-CAP on mineralization of cultured PDL cells. RGD-CAP was detected in the human PDL as multimeric proteins greater than 200 kDa. The RGD-CAP mRNA level decreased in cultured PDL cells exposed to 10(-8) M dexamethasone or 10(-8) M 1alpha,25-dihydroxyvitamin D(3) when these steroids increased alkaline phosphatase (ALP) activity. Furthermore, exogenous RGD-CAP suppressed the ALP activity and bone nodule formation of cultured PDL cells. These findings suggest that RGD-CAP in the PDL modulates the mineralization which affects adjacent alveolar bone metabolism.

Cellular, molecular, and genetic determinants of tooth eruption.

Tooth eruption is a complex and tightly regulated process that involves cells of the tooth organ and the surrounding alveolus. Mononuclear cells (osteoclast precursors) must be recruited into the dental follicle prior to the onset of eruption. These cells, in turn, fuse to form osteoclasts that resorb alveolar bone, forming an eruption pathway for the tooth to exit its bony crypt. Some of the molecules possibly involved in the signaling cascades of eruption have been proposed in studies from null mice, osteopetrotic rodents, injections of putative eruption molecules, and cultured dental follicle cells. In particular, recruitment of the mononuclear cells to the follicle may require colony-stimulating factor-one (CSF-1) and/or monocyte chemotactic protein-1 (MCP-1). Osteoclastogenesis is needed for the bone resorption and may involve inhibition of osteoprotegerin transcription and synthesis in the follicle, as well as enhancement of receptor activator of NF kappa B ligand (RANKL), in the adjacent alveolar bone and/or in the follicle. Paracrine signaling by parathyroid-hormone-related protein and interleukin -1 alpha, produced in the stellate reticulum adjacent to the follicle, may also play a role in regulating eruption. Osteoblasts might also influence the process of eruption, the most important physiologic role likely being at the eruptive site, in the formation of osteoclasts through signaling via the RANKL/OPG pathway. Evidence thus far supports a role for an osteoblast-specific transcription factor, Cbfa1 (Runx2), in molecular events that regulate tooth eruption. Cbfa1 is also expressed at high levels by the dental follicle cells. This review concludes with a discussion of the several human conditions that result in a failure of or delay in tooth eruption.

Osteoclast induction in periodontal tissue during experimental movement of incisors in osteoprotegerin-deficient mice.

Osteoprotegerin (OPG) is a novel secreted member of the tumor necrosis factor (TNF) receptor superfamily that negatively regulates osteoclastogenesis. The receptor activator of the NFKB ligand (RANKL) is one of the key regulatory molecules in osteoclast formation and binds to OPG. In this study, it was suggested that OPG and RANKL are involved in alveolar bone remodeling during orthodontic tooth movement. We examined RANKL localization and osteoclast induction in periodontal tissues during experimental movement of incisors in OPG-deficient mice. To produce orthodontic force, an elastic band was inserted between the upper right and left incisors for 2 or 5 days, and the dissected maxillae were examined for cytochemical and immunocytochemical localization of tartrate-resistant acid phosphatase (TRAP), vacuolar-type H(+)-ATPase, and RANKL. Compared to wild-type OPG (+/+) littermates, TRAP-positive multinucleated cells were markedly induced in the periodontal ligament (PDL) on the compressed side and in the adjacent alveolar bone of OPG-deficient mice. These multinucleated cells exhibited intense vacuolar-type H(+)-ATPase along the ruffled border membranes. Because of accelerated osteoclastic resorption in OPG-deficient mice, alveolar bone was severely destroyed and partially perforated at 2 and 5 days after force application. In both wild-type and OPG-deficient mice, RANKL expression became stronger at 2 and 5 days after force application than before force application. There was no apparent difference in intensity of RANKL expression between OPG (+/+) littermates and OPG-deficient mice. In both wild-type and OPG-deficient mice, expression of RANKL protein was detected in osteoblasts, fibroblasts, and osteoclasts mostly located in resorption lacunae. These results suggest that during orthodontic tooth movement, RANKL and OPG in the periodontal tissues are important determinants regulating balanced alveolar bone resorption.

Inhibition of alveolar bone loss by matrix metalloproteinase inhibitors in experimental periodontal disease.

Periodontal disease is characterized by excessive host collagenase resulting in loss of gingival and periodontal ligament collagen and adjacent alveolar bone. Intragingival endotoxin injection induces a model of periodontal disease characterized by rapid bone loss with biochemical features similar to that of naturally occurring adult periodontitis. CH1766, a peptide with a zinc binding moeity which fits into the active site of the enzyme, and CH6631, a hydroxamic acid derivative with aryl-substituted sulphonamide residues, are inhibitors of matrix metalloproteinases (MMPIs) with differing inhibitory profiles as characterized by in vitro assays. In this study, endotoxin was injected into the gingivae of rats which were then treated orally with either 3 mg/kg or 30 mg/kg of one of the two inhibitory compounds. The gingival tissues were assessed for collagenase and gelatinase activity, plus three different pro-inflammatory cytokines. In addition, alveolar bone height in defleshed jaws was studied by computerized morphometric analysis and scanning electron microscopy. Both drugs reduced active and/or total MMP activity, in many cases to normal, and also partially normalized cytokine levels as well. A dose-response effect was seen with regard to amelioration of lipopolysaccharide-induced alveolar bone loss with both drugs. Other than studies with tetracyclines, this is the first report of beneficial effects of MMPIs in a model of periodontal disease, strongly suggesting that this class of agents could bring therapeutic benefit to patients with this disorder, and that periodontal disease can be used as a model to demonstrate in vivo efficacy of this class of drugs.

Nasal T-cell/natural killer cell lymphoma: CT and MR imaging features of a new clinicopathologic entity.

Nasal T-cell/natural killer cell lymphoma is a new clinicopathologic entity with a characteristic immunophenotypic profile and distinct clinical features. This study describes the radiologic features of nine cases of proven nasal T-cell/natural killer cell lymphoma. Nasal T-cell/natural killer cell lymphoma is often a locally destructive (T stages 3 and 4) disease, typically presenting with obliteration of the nasal passages and maxillary sinuses. Involvement of the adjacent alveolar bone, hard palate, orbits, and nasopharynx is found in more than 50% of cases and is associated with extensive soft-tissue masses. Presence of bone erosion is suggestive but not diagnostic of the disease.

Microradiographic aspects of the growing mandibular body during permanent premolar eruption in the dog.

In order to explore the bony changes in the mandibular body during prefunctional intraosseous eruption of premolars, 18 dogs aged from 8 to 16 wk at the beginning of experimental period, were given two intraperitoneal injections of oxytetracycline (50 mg/kg and 35 mg/kg 2 wk later) and 2 wk later a final injection of Alizarin red S (70 mg/kg). Microradiographic and fluorescent light microscopy studies showed that changes of the alveolar bony crypt walls were influenced by the growing dental germs which they surrounded. The cervical volumetric reduction, which indicates the end of crown formation, induced the apposition of lamellar and then woven bone on the adjacent alveolar walls. Furthermore, with occlusal displacement of the dental crown, the space below the tooth was immediately filled with woven bone trabeculae and chondroid tissue. The same phenomenon was observed at the level of the alveolar base, when the speed of tooth eruption was greater than that of root growth. During premolar development, the changes in the dental germ produces accommodating changes in the adjacent alveolar bone walls, and mandibular transversal growth has the same characteristics as that of a growing diaphysis.

In situ hybridization evidence for a paracrine/autocrine role for insulin-like growth factor-I in tooth development.

Insulin-like growth factor-I(IGF-I) has both metabolic and growth-promoting activities in many cell and tissue types. Although IGF-I is present in serum, it is also thought to have important autocrine and paracrine functions. Immunohistochemistry for IGF-I and its receptor have shown that IGF-I is synthesised locally by the tooth forming cells which exhibit both the IGF-I and the growth hormone receptors. This concept required to be tested by in situ hybridization. Using a digoxigenin-labelled synthetic oligodeoxyribonucleotide probe for IGF-I, we investigated the distribution of IGF-I mRNA in the continuously erupting rat incisor by in situ hybridization. The distribution and intensity of the hybridization signal varied with the developmental stage of the rat incisor. The cells of the apical loop expressed a positive hybridization signal, but the earliest polarised odontoblasts and pre-ameloblasts did not show any positive signal. The onset of enamel secretion was accompanied by a strong hybridization signal in the secretory ameloblasts as well as the odontoblasts. Maturation ameloblasts also demonstrated IGF-I message in their cytoplasm as well as their nuclei. The cells of the pulp and the dental follicle were consistently negative. However, in the adjacent alveolar bone, the signal was high in the osteoblasts and osteoclasts. These findings support the notion of paracrine or autocrine function for IGF-I in tooth development.

Microbial coaggregation in the oral cavity.

Gingivitis and periodontitis are the most common human diseases with bacterial etiology. Almost all adults worldwide experience gingivitis and some degree of periodontitis. Gingivitis can persist for prolonged periods without significant progression or can serve as a precursor to periodontitis in susceptible individuals. Periodontitis lesions are virtually irreversible and exhibit destruction of the connective tissue attachment, apical migration of the junctional epithelium and resorption of the adjacent alveolar bone. Clinically, it results in deep periodontal pockets, exposure of the root cementum to the oral environment, and eventual loss of dentition. The natural occurrence of initiation and subsequent progression of periodontal disease has been followed in a homogeneous population in Sri Lanka over a 20 year period (Loe, 1986). This study has shown that in the complete absence of oral hygiene and oral health care, all participants exhibited visible plaque, gingivitis and supra- and subgingival calculus in all teeth. But despite the remarkable homogeneity of the group, the severity of the disease among individuals varied greatly. On the basis of the rate of periodontal attachment loss, this population could be divided into three groups: (i) those who showed rapidly progressing periodontitis (approximately 8%), (ii) those who showed moderately progressing periodontitis (80%), and (iii) a small but significant group who exhibited no progression of the disease beyond chronic gingivitis. It is the observation of this last group which challenges the understanding of the mechanism(s) of how and what turns on the progression of the periodontal lesion, and how it is turned off. This is still unresolved.KeywordsOral HygieneDental PlaqueOral BacteriumCranberry JuiceBacterial EtiologyThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Expression of growth hormone receptor by immunocytochemistry in rat molar root formation and alveolar bone remodeling.

Growth hormone (GH) may regulate tooth formation and bone remodeling associated with tooth eruption. This study reports the distribution of growth hormone receptor/binding protein in developing rat molars and adjacent alveolar bone by immunocytochemistry using well-characterized anti-growth hormone receptor monoclonal antibodies. These tissues represent an excellent model for studying the ontogenic changes that occur in odontogenic and osteogenic cells, as these cells are found in linear arrays displaying the various stages of morphological and functional differentiation, and differentiated function. Immunoreactivity was first seen in precementoblasts in contact with the epithelial root sheath, and preodontoblasts. However, growth hormone receptor immunoreactivity was associated primarily with the cytoplasm of odontogenic and osteogenic cells forming their respective matrices. Thus, cementoblasts and odontoblasts at sites of new matrix formation showed intense immunoreactivity whereas cementocytes and mature odontoblasts at later stages of tooth development were nonreactive. Osteoblasts engaged in intramembranous ossification in the alveolar bone were positive, although osteocytes and endosteal cells were immunonegative. Osteoclasts at sites of alveolar bone remodeling resorption were also immunopositive. These patterns of receptor expression parallel the ontogenic sequences of odontogenic and osteogenic cells and suggest that GH promotes the functional state of these cells. Our results also imply that GH may influence differentiation or differentiated functions associated with odontogenesis, osteogenesis, and bone remodeling independent of systemic insulin-like GF-I.

Die osteoplastische Versorgung des Kieferspaltes —ein Fortschritt für die kieferorthopädische Behandlung des Spaltpatienten?

This survey deals with problems of osteoplastic supply of the cleft from the orthodontic point of view. Remarkable parallels exist between primary and secondary osteoplasty: The involution stability of the alveolar process is only presented in a space-less tooth line. Therefore, the primary goal is to guarantee tooth eruption in the former cleft area. However, the antalogous bone graft in the former cleft area has to have a similar structure as adjacent alveolar bone. If tooth germs pass through the bone graft, an own parodont can be built up in the course of eruption. This is applicable to both dentitions. Accordingly, the osteoplasty of clefts is the most important prerequisite for stable treatment results and a healthy dentition.

In vivo findings associated with heat generation during thermomechanical compactionof gutta‐percha. Part II. Histological response to temperature elevation on the external surface of the root

An in vivo investigation is described and a histological evaluation made of the effect of canal obturation by thermomechanical compaction of gutta-percha and sealer on the cementum on the lateral surface of the root and adjacent periodontal membrane and alveolar bone of the ferret canine after time intervals of 24 hours, 20 days and 40 days. These tissue reactions were compared with those in the roots of control teeth filled by lateral condensation of cold gutta-percha and sealer. Iatrogenic damage was apparent in a minority of the experimental specimens 20 and 40 days after obturation.

Effects of tooth function on adjacent alveolar bone and Sharpey's fibers of the rat periodontium

There is little information about the effects of short-term non-hypo-, and hyperfunction of teeth on the 1) mineralization patterns of intrinsic and extrinsic (Sharpey's) fibers and 2) mean number and diameter of Sharpey's fibers of adjacent alveolar bone. The mineral density of intrinsic and Sharpey's fibers and the size and number of Sharpey's fibers could indicate the relative strength of the attachment of a tooth to bone in various functional situations. In the present study, non- and hypofunctional situations were created by selective extraction of right molar teeth of the rat; the contralateral teeth were placed in hyperfunction by the surgery. In non- and hypofunctionals, intrinsic and Sharpey's fibers of the crestal third of the alveolus were less densely mineralized than in hyperfunctionals or untreated controls. Mean Sharpey's fiber diameters were significantly greater and their mean number/unit area significantly less in non- than in hypo- or hyperfunctionals or untreated controls (P less than 0.001). Mean Sharpey's fiber diameters in hyperfunctionals were significantly less than in untreated controls (P less than 0.05). Hypofunction ameliorated the effects of nonfunction on mean diameter and number of Sharpey's fibers, but had little effect on the density of mineralization of either the intrinsic or Sharpey's fibers of the alveolus, suggesting that their mineralization may be controlled by factors other than occlusal forces from the adjacent teeth. Thus changes in the stress/strain environment within the periodontium, coincident to altered occlusal function of the adjacent teeth, rapidly affects the morphology of intrinsic and Sharpey's fibers of alveolar bone and ensures that adequate tooth support is maintained in the new functional situation.

Effect of altered occlusal function on transseptal ligament and new bone thicknesses in the periodontium of the rat

Alteration of tooth function is assumed to change stress/strain on the adjacent alveolar bone and its mucoperiosteum, producing changes in morphology similar to those described for other load-bearing bones. The present study suggested that crestal alveolar bone and its mucoperiosteum respond differently to stress/strain than load-bearing bones in other locations, possibly due to differences in the mechanism of bone loading by muscles and teeth. Occlusal hypofunction was initiated by extraction of agonist teeth; the contralateral teeth were placed in hyperfunction by the surgery. Untreated animals were also studied. 3H-proline was injected, animals were killed 1-5 weeks later, and the thicknesses of new bone and transseptal ligament were measured. After 5 weeks of altered function, total thickness (new bone + transseptal ligament) was similar in untreated and in hypofunctional and hyperfunctional situations; however, a new ratio between transseptal ligament and new bone thicknesses was established. Occlusal force was negatively correlated with new bone and positively correlated with transseptal ligament thickness; both thicknesses were statistically correlated in each functional situation (P less than 0.001). Hyperfunction resulted in increased transseptal ligament thickness, but decreased new bone thickness as compared to untreated controls (P less than 0.001). In contrast, hypofunction resulted in an increased new bone thickness, but a decreased transseptal ligament thickness (P less than 0.001). Tissue responses assure appropriate support for the teeth in each functional situation.

Serial section reconstruction using a computer graphics system: applications to intracellular structures in yeast cells and to the periodontal structure of dogs' teeth.

A computer graphics system for reconstruction from serial section micrographs was applied to intracellular details of a yeast target cell (Saccharomyces cerevisiae cell) induced by the alpha factor mating pheromone and was also applied to a periodontal structure of a dog tooth moved orthodontically. In the former, intracellular organelles and a distribution of vesicles could be clearly observed through the cell membrane using the transparent display method in which the smoothing of the reconstructed outer cell membrane surface by computer processing was applied to the transparent display. In the latter case, by cutting through a reconstructed dog tooth and its periodontal tissues, labiolingual and mesiodistal cut surfaces of the tooth and of adjacent alveolar bone could be observed with fine details (232 sections were used).

Tartrate-resistant acid phosphatase in mononuclear and multinuclear cells during the bone resorption of tooth eruption.

Tartrate-resistant acid phosphatase (TRAP) has been used as a cytochemical marker for the cell mediators of bone resorption, osteoclasts and their mononuclear precursors. We have applied a cytochemical method for TRAP to study the dependence of the osteoclast-mediated bone resorption of tooth eruption on the dental follicle, a connective tissue investment of the developing tooth, by analyzing the TRAP activity of mononuclear cells in the dental follicle before and during pre-molar eruption in dogs. The percentage of TRAP-positive monocyte cells increases until mid-eruption, slightly preceding a previously demonstrated rise in numbers of osteoclasts on adjacent bone surfaces. These data suggest an ontogenetic relationship between follicular mononuclear cells and osteoclasts on adjacent alveolar bone surfaces during tooth eruption. However, because TRAP occurs in other tissues and is not an exclusive indicator of pre-osteoclasts, proof of their relationship will have to await application of more definitive techniques.