Thesis--Helsinki. / Extra t.p. with thesis statement inserted. Includes bibliographical references (p. 33-36).

Thesis--Helsinki. / Extra t.p. with thesis statement inserted. Includes bibliographical references (p. 33-36).

Thesis (D.Sc.D.)--Boston University, Henry M. Goldman School of Dental Medicine, 1999. / Includes bibliographical references (leaves 90-106). / Tooth eruption provides an excellent model to examine osseous metabolism as bone resorption (occlusal area), and formation (apical area), occur simultaneously and are spatially separated. Monocytes are thought to play an important role in regulation of bone metabolism. The goal of this study was to examine recruitment of monocytes to bone undergoing developmental remodeling in C57BL/6J mice. To account for potential mechanism for monocyte recruitment, we investigated expression of monocyte chemoattractant protein-1 (MCP-1) in tissues surrounding an erupting tooth. TNF and IL1 are potent stimulators of bone resorption. Recent evidence shows that these proinflammatory cytokines are expressed during embryogenesis and may participate in developmental tissue remodeling. To establish their role in tooth eruption and bone remodeling, we carried out experiments using mice with genetic deletions of TNFR1/IL-1R1 or TNFR1/TNFR2. Mandibles were obtained from animals sacrificed at various time points from birth to 14 days of age. Histological sections were stained using immuno/histochemistry to identify mononuclear phagocytes, osteoclasts, MCP-1-positive and apoptotic cells. The results demonstrated that a significant time-dependent increase in recruitment of monocytes in the occlusal area (bone resorption) at days 5 and 9 was associated with significant increase in number of osteoclasts at similar time points. In contrast, in the apical area (bone formation), a significant time-dependent increase in monocyte recruitment was coupled with a decrease in number of osteoclasts, found in high numbers at earliest time points (up to day 3 postnatally). The number of MCP-1 positive cells also increased with time in both areas and was generally proportional to the recruitment of mononuclear phagocytes. Osteoblasts were the principal bone cell type expressing MCP-1. Our results suggest that monocytes have different functional roles in areas of bone resorption and bone formation. Furthermore, the expression of MCP-1 is developmentally regulated and may provide mechanistic basis to explain the recruitment of monocytes. Functional deletion of TNFR1/IL-1R1 resulted in later onset of molar eruption. However, histological findings showed that only monocyte physiology in the occlusal connective tissue was affected by loss of TNFR1/IL-1R1 signaling. Increased number of monocytes in the area was observed during tooth eruption through subgingival connective tissue (day 13). Presence of monocytes in the dental follicle or presence of osteoclasts at the adjacent bone surface was not altered. Deletion of TNFR1/R2 affected recruitment/function/survival of monocytes and rate of apoptosis only in the apical area during intraosseous stage of tooth eruption (day 9). No changes in monocyte or osteoclast markers were noted in the occlusal area. Loss of TNFR1/R2 signaling had no effect on the rate of molar eruption. Lack of striking differences between the experimental and the wild type groups indicates that TNF and IL-1 do not play a critical role during tooth eruption and remodeling of surrounding bone, supporting the suggested hypothesis that tooth eruption is a redundantly regulated process.

Indiana University-Purdue University Indianapolis (IUPUI) / The effect of untimely loss of deciduous molars on the eruption and development of succedaneous premolars was serially studied in eight children in the mixed dentition stage from 45 degree cephalometric films made at three and six month intervals. Each child had one mandibular deciduous molar removed for reasons other than periapical infection and a lingual arch space maintainer provided. The premolar beneath the extracted molar served as the study tooth; its antimere, as the control tooth. Eruptive movement was measured as the distance between the cusp-tip of a premolar on a superpositioned initial tracing and the corresponding cusp-tip on successive films. Antero-posterior movement of premolars was evaluated on a composite tracing along grid lines oriented to a common base line. Tooth formation was assessed by the increase in root length on successive films. Variation was found in the amounts of eruptive movement and root growth during a three month interval, for all premolars within the sample, within an individual and for a single tooth. In no case did a control tooth erupt more than a study tooth in a given interval. The initial effect of deciduous molar loss on eruptive movement in this study appeared to be accelerative. Tooth development was not found to be effected. While moderate correlation was found between eruptive movement and root growth for all premolars, one process did not appear to be solely dependent on the other. A posterior component of eruptive movement was occasionally demonstrated but was not related to the extraction. The clinical value of this study is limited due to its small sample and short duration. Longer and more comprehensive studies of this problem are recommended.

Thesis (M.S.)--University of Michigan, 1977.

Thesis (M.S.)--University of Michigan, 1947. / eContent provider-neutral record in process. Description based on print version record.

Thesis (M.S.)--University of Michigan, 1977.

Thesis (M.S.)--University of Michigan, 1962.

Thesis (M.S.)--University of Michigan, 1962.

Thesis (doctoral)--Katholieke Universiteit te Nijmegen. / Translation of: Het proces van tanderuptie in beagle honden.