Thesis (doctoral)--Karolinska Institutet, Stockholm, 1987. / Added t.p. with thesis statement inserted. Includes bibliographical references.

Root resorption is a common problem encountered in all branches of dentistry but is more commonly seen in cases that had been treated orthodontically. Orthodontists are constantly improving materials and techniques to reduce undesirable side effects like root resorption. Therefore in this retrospective study the primary objective was to compare the amount of root resorption observed after active orthodontic treatment with three different appliance systems namely, Tip Edge, Modified Edgewise and Damon. The sample consisted of pre and post-treatment cephalograms of sixty eight cases that were treated in three different groups (i.e., techniques). Root resorption of the maxillary central incisor was assessed from pre- and post- treatment lateral cephalograms using two schemes. In the first method overall tooth length (Black, 1902) from the incisal edge to the apex was measured on both pre and post-treatment lateral cephalograms and root resorption was recorded as an actual millimetre loss of tooth length. Percentage shortening per tooth was also recorded. The results were subjected to various statistical analyses. There was a significant upward linear trend (p=0.022) for root resorption from Group 1 (Tip Edge) to Group 3 (Damon). Statistical modeling illustrated that only baseline length (pre-treatment incisor length) was a significant confounder. Gender, race, age and treatment time did not have a significant influence on the amount of root resorption seen after orthodontic treatment. In the final analysis after having adjusted for baseline length it was found that there were no significant differences (p=0.133; ANCOVA) in the degree of root resorption observed after the active phase of orthodontic treatment between groups. Similarly the percentage of root resorption calculated did not differ significantly between groups (p=0.067). The result was also confirmed by following a non-parametric approach by doing an analysis of covariance (ANCOVA) in which data was allocated a rank value. In the second method root resorption was visually evaluated by using the five grade ordinal scale of Levander and Malmgren (1988). It was found that majority of cases in the sample came under Grade1 and Grade 2 category of root resorption. The upward linear trend between actual measurements and visual measurements was found to be statistically significant (p=0.0183).

Thesis (doctoral)--Karolinska Institutet, Stockholm, 1987. / Added t.p. with thesis statement inserted. Includes bibliographical references.

Information on dental resorption first appeared in the literature in an 1829 textbook by Thomas Bell. What first was mistaken as bone tumor and known as “absorption,” continues to be one of the most challenging and mysterious phenomena dental clinicians have had to address. Over the past years, there has been a dramatic increase in reports of resorption in the literature, which have aided in the understanding of the condition and its treatments. Resorption is identified by an increase in osteoclastic cell activity that causes a loss of hard dental tissues. As a physiological process, root resorption helps with the eruption and exfoliation of primary teeth. In adults, resorption is of pathological nature. Resorption can happen both internally and externally. External resorption is a much more common occurrence in dentistry than its counterpart, internal resorption, and involves the external aspect of the tooth. External resorption has been subclassified into external inflammatory resorption, external replacement resorption, external cervical resorption, external surface resorption, and transient apical breakdown. Internal resorption is more unusual and more challenging to diagnose and affects the tooth’s pulp chamber and/or its root canal. Internal resorption has been sub-classified as internal inflammatory resorption and internal replacement resorption. Descriptions of the various forms of resorption are numerous in the literature and have become available due to case studies, clinical presentations and treatment options. From trauma, to prolonged orthodontic treatment, to viruses, to genetic and idiopathic factors, there is a variety of possible etiologic causes of both kinds of resorptions that are central to the understanding and treatment of this condition. Despite the many advances in the field, however, there are still gaps in the processes leading to resorption lesions that remain to be elucidated. If OPG and RANKL are the major culprits in initiating resorption, being able to arrest these molecules or transcription factors, such as c-fos and NFkB or identifying genetic propensities for resorption with a BRCA-like test seem to be research goals which may translate into the prevention of resorption as well as identifying how a physiological process essential to survival transforms into a pathological condition. Additionally and equally important, when resorption is suspected, there is the need for a thorough examination of the oral cavity and a proper understanding of the underlying pathogenesis for its clinical management. Depending on the extent of the lesion, resorption can be arrested by a variety of endodontic treatments that often include root canals or more complex surgical procedures, such as muco-periosteal flaps that allow the access to the resorptive lesion and the excavation of the granulomatous tissue in the tooth. Moreover, composite, sodium hypochlorite or calcium hydroxide are also employed as treatment/ preventive options as well as breaks in orthodontic procedures to eliminate pressure forces that contribute to and/or cause resorption, pulpectomy, careful monitoring, among others. Whether external or internal resorption, the condition can be treated with high rate of success if caught early. Without intervention, resorption leads to tooth loss.

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Thesis (doctoral)--Karolinska Institutet, Stockholm, 1988. / Extra t.p. with thesis statement inserted. Includes bibliographical references.

Thesis (doctoral)--Karolinska Institutet, Stockholm, 1988. / Extra t.p. with thesis statement inserted. Includes bibliographical references.

Thesis (M.S.)--University of Southern California, 1997. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Southern California, 1997. / Includes bibliographical references.

We have previously shown that osteoclasts (OCLs) from multiple myeloma (MM) specimens vary from healthy OCLs in their expression of the TRAIL receptors. TRAIL (TNF-Related Apoptosis-Inducing Ligand), a member of the TNF superfamily, has been shown to induce apoptosis in cells by binding receptors DR4 and DR5, but not DcR1 and DcR2, its decoy receptors, which lack the necessary internal death domain. The observed modulation of these receptors may confer a resistance to apoptosis in the MM environment, and could be related to the cytokine pattern that primarily involves the resorption promoting Receptor Activator of NF-[kappa]B Ligand (RANKL) and Macrophage Inflammatory Protein 1 (MIP-1[alpha]). The aim of our study was to determine which cytokines present in the disease might be responsible for this modulation. In long term cultures of OCL precursors from cord blood in the presence of M-CSF and RANKL, multinucleated cells (MNCs) that express OCL markers form, and can resorb bone. Through immunocytochemistry we showed that these MNCs can express all four TRAIL receptors. By stimulating with various cytokines (RANKL, MIP-1[alpha], Transforming Factor [bêta] (TGF[bêta]), osteoprotegerin (OPG), TRAIL), and parathyroid hormone (PTH) in OCL cultures, we were able to observe receptor modulation at the mRNA level using real time PCR, the protein level using Western blot analysis, and cell surface expression via immunocytochemistry. To determine if these changes translated to a difference in resistance to apoptosis, cells treated with [with] apoptosis-inducing levels of TRAIL after 5 days of stimulation with the selected cytokines were evaluated via TUNEL to quantify apoptosis. While no correlation has yet been established between the observed receptor modification and apoptosis induction, sample size is a factor, and further tests will be performed. Our results suggest the possibility that TRAIL receptor modification is induced by multiple cytokines present in bone diseases, capable of altering both the susceptibility and resistance pathways in osteoclasts. By potentially prolonging the lifespan of the OCL, these regulatory influences may ultimately be contributory factors to the augmentation of resorption in the micro-environment of bone resorptive diseases like multiple myeloma, Paget's disease of bone, or osteoporosis.