EPA Consensus Project Paper: The Vertical Dimension of Occlusion. How to Determine and How to Alter? A Systematic Review.

PURPOSE: The aim of this systematic review was to explore the dental literature to identify high quality clinical studies that introduced methods of determining the vertical dimension of occlusion (VDO), and additionally to find studies which assessed alterations in the VDO. MATERIALS AND METHODS: An electronic search of the literature was conducted through PubMed , Embase, and Cochrane Library databases referring to the determination and alteration of the VDO by 12/2021. RESULTS: A total of 215 records were obtained from the initial search. After the first two screenings, 33 studies were selected for inclusion. Correlations in the morphometric group ranged between r=0.18-0.87, p⟨0.05-0.001, correlations in the cephalometric group ranged between r=0.28-0.92, p⟨0.05-0.001, and correlations in the mechanometric group ranged between r=0.21- 0.75, p⟨0.05-0.01. Regarding the alteration of VDO, in all studies the increase ranged between 1.8-8 mm and the patients adapted . CONCLUSIONS: No clear guidelines can be established yet, in relation to the determination and alteration of the VDO. There is no apparent benefit in using more invasive and complex methods compared to the use of the facial anatomical landmarks. Patient adaptation seems to be successful when the range of VDO increase was 1.8-6.0 mm.

Cellular biomechanics: Fluid-structure interaction or structural simulation?

The mechanisms by which cells respond to their changing mechanical environment and how this stimulus is decoded intracellularly from the tissue to the organ level, are widely considered as fundamental for most biological processes. Despite this, the underlying phenomena of mechanotransduction, are still not very well understood. Over the last years, numerical modeling has emerged as a cohesive element in the interpretation of biophysical and biochemical assays, concerning cellular mechanotransduction. We hypothesize that the consideration of continuum mechanics (studying all cellular entities as solids) is an inherent limitation of these models, and in part, responsible for their restricted application in cellular biomechanics. To evaluate this, a (verified and validated) 3D model of osteoblast is simulated through structural analysis, employing conventional Finite Element (FE) modelling and the results compared to a Fluid-Structure Interaction (FSI) analysis. Among the trend observed, FSI systematically leads to a higher stimulation of the nucleus (by up to 200%), while FE produced a more uniform stress field, resulting in the deformation of a notably larger portion of its volume. Although FE modelling captures a seemingly correct kinematic response of the cell when subjected to the simulated loading scenario, FSI represents a more realistic alternative. The equitable consideration of both, liquid- and solid-state material characteristics, in the latter analysis, revealed intra-cellular loading patterns that were more realistic from a biomechanical perspective. In conclusion, FSI can provide refined insight as to nuclear loading, thus serving as a far more accurate framework for decoding cellular mechanotransduction.

The Effect of Surface Preparation of Acrylic Teeth.

PURPOSE: To investigate whether the chemical bond between acrylic teeth and heat polymerized PMMA can be altered by chemical and/or mechanical treatment. MATERIALS AND METHODS: One hundred fifty acrylic teeth were divided in groups of 10. Their ridge lap surface underwent mechanical and/or chemical treatments: 1) no treatment, 2) air-abrasion with Al2O3 particles, 3) acid etching with phosphoric acid, 4) application of composite resin bonding agent, 5) application of MMA and ethylmethylketone bonding agent, 6) PMMA monomer application. The teeth were then placed in heat polymerized acrylic resin. Each specimen was compressed with a universal testing machine. Descriptive statistics, one-way ANOVA (α=0.05) and Tukey's HSD test were used. A scanning electron microscope (SEM) was also used to study the fracture areas. RESULTS: Statistically significant differences (p⟨0.001) in the bond strength were found. The strongest bond (239.41 N), was noted in the group treated with sandblasting followed by PMMA monomer application. CONCLUSIONS: Mechanical and/or chemical preparations affect significantly the bond strength between the acrylic resin denture teeth and the PMMA denture base. Air abrasion was the most effective treatment, either alone or combined with other treatments.

Secondary osteoporosis - an endocrinological approach focusing on underlying mechanisms.

Osteoporosis is a major and increasingly serious public health problem not only in postmenopausal women and people over 70 years old (primary osteoporosis) but also in men under 70 years and premenopausal women (secondary osteoporosis). The most common primary osteoporosis occurs as a result of menopause and aging process. Secondary osteoporosis is a consequence of an underlying cause and frequently is diagnosed after an atraumatic fracture. The pathogenesis of secondary osteoporosis is almost always multifactorial. Certain endocrinopathies, systemic diseases, malignant neoplasias, organ dysfunctions, a variety of medications such as corticosteroids, lifestyle conditions and habits, and also major depression can lead to the secondary osteoporosis. Early diagnosis and treatment can prevent further bone loss and fractures.

Obesity in the ageing man.

As the population is ageing globally, both ageing and obesity are recognized as major public health challenges. The aim of this narrative review is to present and discuss the current evidence on the changes in body composition, energy balance and endocrine environment that occur in the ageing man. Obesity in the ageing man is related to changes in both body weight and composition due to alterations in energy intake and total energy expenditure. In addition, somatopenia (decreased GH secretion), late-onset hypogonadism (LOH), changes in thyroid and adrenal function, as well as changes in appetite-related peptides (leptin, ghrelin) and, most importantly, insulin action are related to obesity, abnormal energy balance, redistribution of the adipose tissue and sarcopenia (decreased muscle mass). A better understanding of the complex relationship of ageing-related endocrine changes and obesity could lead to more effective interventions for elderly men.

Thyroid cancer in patients with hyperthyroidism.

Thyroid cancer can be associated with thyrotoxicosis caused by Graves' disease, toxic multinodular goiter, or autonomously functioning thyroid adenoma. The objective of this study was to summarize current evidence regarding the association of thyroid cancer and hyperthyroidism, particularly with respect to the type of hyperthyroidism found in some patients, and whether this affects the outcome of the patient. A PubMed search was performed up to August 2011. Articles were identified using combinations of the following keywords/phrases: thyroid cancer, papillary thyroid cancer, follicular thyroid cancer, medullary thyroid cancer, anaplastic thyroid cancer, hyperthyroidism, Graves' disease, auto-nomous adenoma, toxic thyroid nodule, and toxic multinodular goiter. Original research papers, case reports, and review articles were included. We concluded that the incidence, as well as the prognosis of thyroid cancer associated with hyperthyroidism is a matter of debate. It seems that Graves' disease is associated with larger, multifocal, and potentially more aggressive thyroid cancer than single hot nodules or multinodular toxic goiter. Patients with Graves' and thyroid nodules are at higher risk to develop thyroid cancer compared to patients with diffuse goiter. Every suspicious nodule associated with hyperthyroidism should be evaluated carefully.

Adipokines and stroke: a review of the literature.

Stroke represents one of the most important menaces to public health. A number of modifiable and non-modifiable risk factors have been identified and studied in detail; among those, obesity, the new world epidemic, seems to be one of the most important in terms of prevention. The discovery of the secretory role of the adipose tissue and of adipokines has opened new fields of research. A number of studies have been published on their relation to cardiovascular risk and the potential of using them as prevention markers. In the present review the physiology of leptin, adiponectin and resistin is described and their role in the pathogenesis of stroke is examined.

Pregnancy- and lactation-associated osteoporosis: a narrative mini-review.

Pregnancy and lactation represent stress states for maternal health and development. Pregnancy and lactation-associated osteoporosis (PLaOs) are uncommon and rare conditions characterized by the occurrence of fragility fracture(s), most commonly vertebral, in late pregnancy or during the postpartum period. The etiology and pathogenesis of these conditions is not clear and several theories are proposed. Due to the rarity of the disease, various isolated clinical cases are reported in the medical literature and only one case-control study thus far. In the current review we try to analyze the pathophysiologic pathways implicated in these conditions and provide possible explanations regarding etiology; we present data on the epidemiology, clinical course, diagnosis and current approved treatment modalities of PLaOs.

Medical management of adrenal disease: a narrative review.

Adrenal diseases comprise for a variety of medical endocrine issues, ranging from partial or complete gland insufficiency, to several kinds of adrenal hyperfunction, either of congenital or neoplastic etiology. For hypofunction of the adrenals (partial or complete) the treatment of choice is medical; the mainstay of treatment is hydrocortisone. Patients with congenital adrenal hyperplasia caused by 21-hydroxylase deficiency are treated with glucocorticoids to control androgen excess. Most benign neoplastic adrenal diseases that cause hyperfunction of the gland are surgically treated, however this may not be always feasible or effective. For Cushing's syndrome ketoconazole controls cortisol's hypersecretion, whereas in case of bilateral idiopathic hyperaldosteronism spironolactone controls hypokalemia and hypertension. For neoplastic adrenomedullary disease surgery is the treatment of choice; medical treatment is used preoperatively (mainly alpha blockers) and in case of disease persistence and /or recurrence (mainly metyrosine). For malignant adrenocortical disease, surgical removal remains the indicated treatment, but if the potential for surgical intervention is limited due to tumor extension, medical treatment can alleviate symptoms of hormone hypersecretion; mitotane in selected patients has good results.

Cement failure loads of 4 provisional luting agents used for the cementation of implant-supported fixed partial dentures.

The major disadvantage of cement-retained implant-supported fixed partial dentures (FPDs) is difficulty in retrievability. The retentive strengths of the provisional luting agents usually employed in these cases are therefore an important consideration. This study evaluated the cement failure loads of 4 provisional luting agents used for the cementation of FPDs supported by 2 implants or 4 implants. Nogenol luting agent exhibited the lowest retentive values in both types of FPD. ImProv proved to be the most retentive cement of all tested. Temp Bond NE and Temp Bond presented significantly different values (P < .05) for the 2-implant FPD, but not for the 4-implant model. On the basis of the study results, it may be concluded that Nogenol appears to be more appropriate for cementation of both 2- and 4-implant-supported FPDs when removal of the provisionally cemented superstructure is anticipated.

An esthetic and hygienic approach to the use of intracoronal attachments as interlocks in fixed prosthodontics.

This article describes a procedure that uses the Ney MS (Minimal Space) intracoronal attachment as an interlock in a pontic. This procedure overcomes the disadvantages associated with the use of the intracoronal attachments, which are (1) excessive tooth reduction often required to place the attachment within the contour of the crown; (2) compromised embrasures, which result in oral hygiene and periodontal problems; and (3) poor esthetics.