Meta analysis of the treatment-related factors of external apical root resorption.

OBJECTIVE: To elucidate possible treatment-related etiological factors--such as, duration of treatment and apical displacement--for external root resorption. DESIGN: Meta-analysis of the available English-language literature. INCLUSION & EXCLUSION CRITERIA: Papers with a sample size > 10, fixed appliances, pre- and post-operative radiographs, and apical displacement recorded were included. History of trauma, prior root resorption and endodontic treatment were excluded. Appropriateness of these selections was tested with a 'funnel plot' analysis. OUTCOME MEASURE: Correlations between root resorption, apical displacement, and treatment duration. RESULTS: Mean apical root resorption was strongly correlated with total apical displacement (r = 0.822) and treatment duration (r = 0.852). CONCLUSION: The treatment-related causes of root resorption appear to be the total distance the apex had moved and the time it took.

Perceived long-term prognosis of teeth with orthodontically resorbed roots.

OBJECTIVES: To investigate the perceived significance of root resorption in the dental community. STUDY DESIGN AND SAMPLE: Mail out survey questionnaire accompanied by morphed images of 10-50% root resorption. General practitioners, periodontists, prosthodontists and orthodontists were the participants. OUTCOME MEASURES: Correlations between 'significant' and 'detrimental to the longevity of the tooth'. These assessments were conducted within specialty groups and among. Also measured was the source of knowledge upon which practitioner assessments were based. RESULTS AND CONCLUSIONS: General practitioners were the most concerned about root resorption. Although most practitioners feel 50% root resorption is significant and detrimental to the longevity of the tooth, extraction followed by prosthetic replacement was not an option. No agreement among practitioners when orthodontic treatment should be terminated; the general practitioners were conservative suggesting termination after 35% root loss. History of trauma, genetic disposition and root morphology are the most cited predisposing factors. Lengthy treatment time concerns general practitioners more than the orthodontists. With the exception of orthodontists, dentists believe excessive force is detrimental to the root, but no one is able to define what excessive force is. Overall, dental school curricula overstate the causes of root resorption. Generally, dental professionals seem to base their opinions on myths and are largely inconsistent in their assessments.

A stochastic evaluation of the decision to specialize in orthodontics.

OBJECTIVE: The objective of this paper is to identify under different scenarios, and from a financial point of view, the conditions required to successfully switch from the general dentistry practice to orthodontics. STUDY DESIGN: A mail survey was used to collect the data from the practicing orthodontists. They estimated the income, at certain points, in the working life of an orthodontist. The general practitioner data were taken from the American Dental Association figures. Subsequently, a stochastic model was constructed. RESULTS AND CONCLUSION: Those who decide to buy an existing practice expect higher profits in the near future, and therefore the required minimum number of remaining years of practice is lower than for those deciding to start a new practice. For both scenarios, the 3-year residency will delay the profits compared with a 2-year residency. Thus, an increased number of remaining years of practice is required. There must be more than 10 working years left in the practitioner's life to make the switch profitable.

Treatment time, outcome, and patient satisfaction comparisons of Damon and conventional brackets.

Efficiency of treatment mechanics has been a major focus throughout the history of orthodontics. Self-ligating brackets were developed on the premise that elimination of ligature ties creates a friction-free environment and allows for better sliding mechanics. It is expected that the self-ligating bracket will reduce the treatment time. This study was designed to compare the effectiveness and efficiency of Damon self-ligating (SL) brackets to those brackets ligated with either steel ligatures or elastomeric 'O' rings. Not only treatment time and the number of appointments needed were addressed, but the quality of the treatment outcome was also assessed. American Board of Orthodontics (ABO) grading criteria for models and panoramic radiographs were employed. Additionally, a nine-question survey was sent to the 215-patients in this study (108 Damon, 107 conventionally-ligated) to elicit their perceptions of how their orthodontic treatment progressed and finished. The results showed that patients treated with Damon SL brackets had significantly lower treatment times, required significantly fewer appointments, and had significantly higher ABO scores than those treated with conventionally-ligated edgewise brackets. There were no significant differences in Damon or non-Damon ABO scores with respect to gender. Damon patients over the age of 21 had significantly higher ABO scores. Conversely, the non-Damon patients under the age of 21 had significantly higher ABO scores. For pre-treatment Angle classification, no significant differences were noted. Patient responses showed that Damon patients perceived their treatment time as being shorter than expected. It appears that faster orthodontic treatment can be better as measured by the ABO criteria.

Maxillary expansion: a meta analysis.

The utility of maxillary expansion has been equivocal for more than 100 years. The advent of meta-analysis and evidence-based learning has provided an opportunity to look objectively at this treatment modality. Medline was searched from 1978 to 1999 for all studies examining the stability of transverse expansion of the human maxilla using initial search terms of maxillary expansion and palatal expansion which were limited to those English language and human subjects. The more than 5000 articles were reduced to 12 based on the defined inclusion and exclusion criteria. The two investigators participating in the study were blinded, the studies' authors and origins blacked out and the evaluation coded and scored. A cumulative 'Meta evaluation score' was computed for each study. Six studies remained for the final analysis. The mean expansion after adjustment according to the principles of meta analysis was 6.00 mm with a standard deviation of 1.29 mm. Of the 6-mm average, 4.89 mm was retained while wearing retainers. Five of the papers provided retention data and post-retention data, but only three studies provided both retention and post-retention data. The average age of patients in these reports was 10.8 years. The 6-mm average expansion with retention in the short-term (<1 year) yielded a 4.71-mm residual expansion. Subsequently, this expansion during the short-term post-retention period was reduced to 3.88 mm. Finally, in the long-term post-retention study period only 2.4 mm of the residual expansion was reported to have remained. This 2.4 mm of expansion remaining after more than a year or more of post-retention period was no greater than what has been documented as normal growth. There is insufficient data to conclude that any useful expansion beyond that can be expected through normal growth was retained.

Regulation of IL-1-induced gingival collagenase gene expression by activator protein-1 (c-Fos/c-Jun).

Matrix metalloproteinase-1 is probably involved in the progression of periodontal disease. The aim of this study was to investigate whether IL-1beta stimulates the expression of the activator protein 1 (AP-1) transcription factor and, consequently, if the AP-1 transcription factor participates in the regulation of collagenase gene expression in human gingival fibroblast cells. In this study, we demonstrate that the concentration of the protein components of AP-1 transcription factor, c-Fos and c-Jun, is enhanced by IL-1beta both at mRNA and protein levels, utilizing Northern blot analysis, electrophoretic mobility gel shift assay and Western blot analysis. The IL-1beta stimulated the collagenase-CAT and AP-1-CAT activities in a dose dependent manner with respect to the amount of DNA used in transfections. Further, overexpression of c-Fos and c-Jun proteins revealed a dose-dependent transcriptional activation of the collagenase promoter. These findings, coupled with the existence of AP-1 consensus DNA binding sites on the collagenase gene promoter, show that regulation of collagenase gene expression by IL-1beta involves the transcription factor AP-1 in gingival fibroblasts.

Defining characteristics of financially successful orthodontists.

Financially successful personality profiles in most of the business world have been reported to be the choleric (powerful) and the melancholy (perfect) types. In 1996, Hughes proposed that the same relationship possibly exists in the profession of orthodontics. The purpose of this study was to explore whether a dominant personality profile exists for the most financially successful orthodontists. A questionnaire was used to gather information regarding the financial sophistication and the dominant personality profile of each participating orthodontist. One hundred twenty-six of the 300 surveys distributed to orthodontists were returned for a response rate of 42%. For every question, the null hypothesis of independence was tested with the chi-square test. The null hypothesis of independence was rejected for a P value of less than.05. The results revealed that no correlation exists between the financial sophistication of orthodontists and their personality profiles. However, over two thirds of the orthodontists had the choleric (powerful) and the melancholy (perfect) as dominant personality types. Interestingly, the questionnaire shed much light on factors that do contribute to financial success in orthodontics. Although statistical differences are lacking in these data, certain traits about successful practitioners could be identified. These orthodontists (1) allow their practices to grow if it will increase the net income, (2) view control of overhead as a key principle, (3) emphasize the competence of staff in determining the success of practice, and (4) believe in marketing. Implementation of these simple and common sense principles in some orthodontic practices might affect the business significantly.

Patient and parent preferences for orthodontic practices.

This study was designed to identify who chooses an orthodontic office and what factors might induce the attraction. Patients and parents from the lists provided by suburban orthodontic offices were contacted. A mail-out survey instrument was used to gather the data. Results revealed that the reputation of the practitioner was most important along with the level of caring attitude the office projected. It was also important that the office is located near home, interestingly, the mother is the most significant decision-maker in the family in choosing an orthodontic office. Moreover, not the cost of treatment but the payment plan was the critical element in the decision process. The higher income families with three or less children were attracted to office characteristics such as excellence of the orthodontist, attention, and convenience. A marketing strategy based on these elements might provide the best return on the investment.

Inhibition of gingival collagenase gene expression by dexamethasone.

Glucocorticoids are potent immunosuppressants shown to be effective in the treatment of inflammatory diseases. Reportedly, they work, in part, by inhibiting cytokines and other transcription factors including AP-1. In this study we investigated the mechanisms of efficient repression of collagenase gene expression by dexamethasone in the human gingival fibroblast. Northern analyses showed that IL-1-dependent collagenase mRNA production was significantly decreased in the presence of dexamethasone. The influence of dexamethasone on the transcription factor NF-kappaB, STAT3, and AP-1 was investigated by using the gel mobility shift assay with nuclear extracts prepared from the cells grown in the presence of dexamethasone. We observed that in addition to AP-1, binding of NF-kappaB and STAT3 to DNA was also decreased significantly. Additionally, dexamethasone induced the transcription of the I kappaB-alpha gene suggesting that in the presence of dexamethasone, NF-kappaB quickly reassociates with newly synthesized I kappaB-alpha and markedly reduces the amount of NF-kappaB. CAT transfection studies utilizing collagenase promoter demonstrated a dose-dependent transcriptional inhibition of IL-1-induced gingival collagenase gene expression by dexamethasone. These data reveal that collagenase gene expression can be regulated by the impairment of IL-1-stimulated NF-kappaB, STAT3, and AP-1 activities, and can highlight a possible molecular mechanism for the anti-inflammatory effects of glucocorticoids.

Antizyme prevents ornithine decarboxylase-mediated cell death in human fibroblasts.

Ornithine decarboxylase (ODC) is a key enzyme of polyamine biosynthesis essential for growth-related cellular functions. Apart from its physiological role in cell proliferation, ODC also contributes to the induction of apoptosis under certain conditions, e.g. following growth factor withdrawal. The rate of cell death is a function of its enzyme activity, ODC activity is inhibited by a regulatory protein antizyme, also known to suppress polyamine uptake. We report that forced expression of antizyme prevents ODC-mediated cell death in human gingival fibroblasts under very low serum conditions. These data suggest an important antiapoptotic role for antizyme in cell survival.

Prediction of mandibular third molar impaction in the orthodontic patient from a panoramic radiograph.

In this study we explored the predictability of mandibular third molar impactions. Serial panoramic radiographs from 50 non-extraction and 15 extraction patients were traced for various angular and linear measurements. A linear discriminant function analysis was performed for each stage of third molar development. The results indicate that the earliest stages of development have very little predictive value. Accordingly, a justification for the oft-practiced enucleation procedure cannot be made. Although the more the tooth is developed, the higher is the accuracy of prediction, two earlier stages where the crown is fully formed or the roots 1/3 formed possess high predictive values. Based on our data, impaction of third molars in the mandible is a predictable event both in extraction and non-extraction patients.

Composite hooks enhance rotational control.

We find hooks placed in positions of convenience useful in correcting rotations, especially with lingual appliances. The steps involved in building them are straightforward. Following acid etching of the spot where the hook is to be placed, a small amount of bonding material is carried onto the enamel surface and a base established by a series of circular motions with the tip of an explorer. The bonding material is then extruded with the tip of the explorer. As soon as the material is extruded to the desired length and curvature, the UV light is applied. Of course, if needed, bigger hooks can be constructed and then trimmed to shape with a bur. A short-beak band remover works best (in a scraping motion) for the removal of these hooks. The following figures illustrate the point (Figs. 1-7).

Association of interleukin-1-induced, NF kappa B DNA-binding activity with collagenase gene expression in human gingival fibroblasts.

During earlier examination of interleukin-1 (IL-1)-induced matrix metalloproteinase gene expression in human gingival fibroblasts a highly induced immediate early gene, I kappa B-alpha, a NF kappa B DNA-binding inhibitor, was identified. The aim now was to investigate whether recombinant (r)IL-1 beta induces the stimulation of NF kappa B and its inhibitor proteins in human gingival fibroblasts and to understand if inhibition of its activity affects collagenase gene expression. Primary gingival fibroblasts (human) were treated with rIL-1 beta to determine the effect on NF kappa B-like DNA-binding activity. IL-1 induced the production of steady-state mRNA levels of I kappa B-alpha in the cultured fibroblasts. Nuclear run-on transcription studies demonstrated that rIL-1 induction of I kappa B-alpha may be transcriptionally regulated. Using electrophoretic mobility gel-shift assays it was shown that rIL-1 activates NF kappa B-like, DNA-binding activity in these fibroblasts. NF kappa B-like DNA-binding activity was rapidly induced and turned over in gingival fibroblasts with peak activity at 30 min after rIL-1 treatment. Further, treatment with chymotrypsin protease inhibitor and antioxidant inhibitor prevented IL-1-induced, NF kappa B-like, DNA-binding activity and collagenase mRNA production. When coupled with the existence of NF kappa B consensus DNA-binding sites on the collagenase gene promoter, these findings suggest that the stimulation of NF kappa B in gingival fibroblasts by rIL-1 could play an important part in the regulation of their collagenase gene expression. The ability of IL-1 to stimulate this expression may define a pivotal role for this cytokine in the pathogenesis of periodontitis.

Validity of computerized predictions of dentoskeletal and soft tissue profile changes after mandibular setback and maxillary impaction osteotomies.

The aim of the present investigation was to evaluate the validity of the predictions of a computerized cephalometric system (Dentofacial Planner) regarding dentoskeletal and soft tissue profile changes after mandibular setback and maxillary impaction osteotomies. Tracings of lateral cephalograms taken at the end of preoperative orthodontics (within 1 week before surgery) and approximately 1 year after the operation were digitized and entered into the Dentofacial Planner. For the mandibular setback group, the computerized predictions tended to place the mandible less posteriorly than the actual situation and to significantly underestimate the mandibular plane angle, the total anterior skeletal and soft tissue facial heights, the lower anterior skeletal facial height, and the upper lip height. In the maxillary impaction group, the prediction printouts significantly overestimated the total anterior soft tissue facial height, the upper lip height and the inclination and curvature of the lower lip and underestimated the soft tissue thickness in the regions of pogonion and point B.