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Biomedical subjects

A Carano

Publications and source records attributed to A Carano.

At least 19 recordsLinked to original sources
PubMed2006

Mechanical behavior of an osteotomized mandible with distraction orthodontic devices.

This work analyzes the mechanical behavior of a human mandible when distraction orthodontic devices are used for correcting problems of dental overcrowding and/or arch shrinkage. The mandible 3D model is reconstructed from CT scan data and meshed into finite elements. The distractor is also modeled. FEM analysis included geometric non-linearity. Displacement field of healthy and osteotomized mandibles are compared. Progressive expansion of the distractor and effects of mastication are also analyzed. Finally, we compare two distraction protocols PROT1 and PROT2 where device is, respectively, expanded by 0.6 or 1.2mm/day. The global displacement is 6mm according to clinical recommendations. It came out that mastication forces generate displacements compatible with bone remodeling. However, parasitic rotations of the mandible arms due to mastication may counteract arch expansion induced by the device. Stress concentrations occurred where the device is fixed: stress peaks stay however below yield limit. Finally, PROT2 reduced by about 10% stresses in mandible and reproduces better than PROT1 the displacement field imposed by the device.

Biomechanical Phenomena↗
PubMed2002

Self-etching vs. traditional bonding systems in orthodontics: an in vitro study.

The need for a bonding system that is consistently reliable, biocompatible, and most of all, easy to use and is unaffected by saliva contamination, has led to the development of products that did not require the initial step of etching the enamel surface. In these new systems elements of etching, priming and bonding are all in one component. The aim of this study was to compare the bonding strength of brackets with a traditional technique to the Prompt L-Pop (monocomponent adhesive) using the same composite resin. The results showed no statistical differences in detachment values of these two groups.

Acid Etching, Dental↗
PubMed2001

Treatment of the noncompliant Class III growing patient.

The treatment of skeletal Class III malocclusion is one of the most challenging problems that confronts the practicing orthodontist, particularly in the late deciduous or early mixed dentition periods. In addition to its inherent difficulty, compromised results can also be due to poor patient cooperation; orthopaedic appliances for Class III treatment can be uncomfortable and unaesthetic. There are few acceptable alternatives when a patient refuses to wear an orthopaedic appliance. The aim of this report is to introduce an approach for the treatment of the non compliant dental and skeletal Class III in growing patients. The Smart Wire (SW) is a new orthodontic device simply formed by a 1 mm diameter stainless-steel arch wire that is inserted into the extraoral tube of the upper molar bands. The SW interferes with lower incisors in the front upon mandibular closure. Thus, a distally directed force is applied on the lower incisors and on the mandible while at the same time a mesial force is transmitted onto the upper molars. This combination of force and reaction guides the orthodontic-orthopaedic correction of Class III malocclusions in growing patients.

Journal Article↗
PubMed2001

Orthodontic finalization strategies in dysfunctional adult patients.

Although orthodontic treatment for the finalization of temporomandibular dysfunction (TMD) patients is often advocated, it represents a risk of failure. Furthermore, in the literature there are few articles that illustrate appropriate orthodontic strategies for the finalization of these patients. In this article the authors suggest a step-by-step clinical procedure in order to: 1. verify the rationale for orthodontic finalization in TMD patients; 2. illustrate the guidelines for correct orthodontic treatment; and 3. suggest a strategy to stabilize the mandible during orthodontic treatment and to retain that stabilization after treatment. If splint therapy is successful in relieving the TMD symptoms, a fixed posterior bilateral stop is used for occlusal stability. After one or two months during which the bilateral stop is shown to be adequate in maintaining TMJ health without a splint, orthodontic finalization can be performed with minimal risk of failure. The essential sequences of Class I, Class II, and Class III treatment for the finalization of TMD patients are also presented. The difficult goal of a long term stability in cases that have been orthodontically finalized is reached by the conversion of the posterior bilateral stops (crown build-ups) into permanent vertical stops.

Adolescent↗
PubMed1996

MRI study of a physiotherapeutic protocol in anterior disk displacement without reduction.

Disk displacement of the temporomandibular joint (TMJ) without reduction has been considered a fundamental pathophysiologic abnormality of the joint. In this paper there are supportive clinical and MRI evidence of a successful repetitive manipulative technique for the treatment of acute and chronic locking. In 1500 treated cases, documented on videotape, only five cases required surgical intervention. The success of the therapy was confirmed by 13 MRI images of the TMJ of patients with acute and chronic locking before and after therapy. In all cases the anteriorly dislocated disk in closing and opening position was recaptured and repositioned in a normal position in the temporomandibular fossa. Three complete cases are reported with complete clinical and MRI documentation.

Adult↗
PubMed1996

Effects of continuous and intermittent forces on human fibroblasts in vitro.

Orthodontics is based upon the cellular response to biomechanical forces. However, little is known about the way cells respond to such forces. An experimental model has been designed to study the morphological and metabolic behaviour of human cells, subjected to cyclical or static mechanical loads. The model involves attaching human fibroblasts to silicone collagen-coated membranes, which are subjected to either continuous of cyclical stretching by a motor coupled with a movable supporting frame. The effect of continuous or cyclical stretching on the secretion of collagenase, an enzyme thought to play an important role in the process of tooth movement, was measured. Cyclical stretching of fibroblasts over a 4-day period, approximately doubled collagenase production as compared with the control. Continuous stretching, on the other hand, was only 50 per cent as effective in enhancing enzyme release. In contrast, the secretion of the collagenase inhibitor was unaffected by either form of mechanical deformation. To understand the effect of cyclical forces further, a morphological study using humane fibroblasts was performed. It was found that stretching or compression delivered an immediate and proportional deformation of the cells. After 10-15 minutes the morphology of cells readapted to the new mechanical environment, causing a loss of the biological activation. This suggest that a new mechanical stimulus is necessary to induce a new biological reaction.

Biomechanical Phenomena↗
PubMed1996

The lingual distalizer system.

Class II molar relationships can be corrected by several methods. In previous systems, orthodontic forces have been applied to crowns and distal movement of the first molar has mainly been by tipping and a rotation of the crowns. A new Lingual Distalizer (LD) has recently been developed to distalize the maxillary molars without the drawbacks of previous appliances. The lingual distalizer is relatively easy to insert, is well-tolerated, does not require patient co-operation and is aesthetic. It distalizes molars without loss of anchorage and moves them with bodily translation.

Adolescent↗
PubMed1993

Acid and base effects on avian osteoclast activity.

Osteoclasts generate a massive acid flux to mobilize bone calcium. Local extracellular acidification by polarized vacuolar-type H(+)-ATPase, balanced by contralateral HCO3-(-)Cl- exchange to maintain physiological intracellular pH, is theorized to drive this process. It follows that extracellular pH, PCO2, or HCO3- concentration ([HCO3-]) should impact bone matrix dissolution. However, the effects on bone resorption of the concentrations of these ions or their transmembrane gradients are unknown. Furthermore, because bone management is a vital process, regulatory feedback may minimize such effects. Thus a complex relationship between bone resorption and pH, PCO2, and [HCO3-] is expected but requires experimental determination. We measured bone resorption by isolated avian osteoclasts while varying these parameters across the physiological range. Bone degradation increased 50% from pH 7.3 to 6.7, whether achieved by changing [HCO3-] (2.3-38 mM) at constant HCO3- or PCO2 (15-190 mmHg) at constant [HCO3-]. However, at constant pH, changing PCO2 and [HCO3-] within physiological limits did not affect bone resorption. In contrast, total HCO3- removal at pH 7.4 reduced bone degradation by rat or avian osteoclasts substantially, confirming that normal acid secretion requires HCO3-. These observations support a model coupling osteoclastic bone resorption to proton and HCO3- transport but indicate that [HCO3-] is not rate limiting under physiological conditions. Extracellular pH changes affect osteoclastic bone resorption measurably, but not dramatically, at physiological [HCO3-].

Acid-Base Equilibrium↗
PubMed1991

Eminence-posterior occlusal plane angle in patients with temporomandibular disorders.

The causes of temporomandibular disorder are not clearly understood. The controversy regarding the role of the features, either dental or skeletal, still exists after nearly a half century of debate. The present study demonstrates an interesting correlation, expressed as an angular value, between the posterior surface of the articular eminence and the posterior occlusal plane. The group with dysfunction had a mean value significantly lower (133 +/- 4) than the group without symptoms (144 +/- 5). In light of this data, it is suggested to interpret a small eminence-posterior occlusal plane as an anatomical predisposing pattern for dysfunction.

Adolescent↗
PubMed1991

Bone matrix constituents stimulate interleukin-1 release from human blood mononuclear cells.

To test the hypothesis that mononuclear cells are stimulated to release interleukin 1 (IL-1) by bone fragments released in the bone microenvironment during the remodeling cycle, we have investigated the effects of bone matrix and some of its constituents on IL-1 secretin from peripheral blood mononuclear cells (PBMC). Increases in IL-1 activity were observed when either PBMC or adherent monocytes, but not lymphocytes depleted of monocytes, were co-cultured with either human or rat bone particles but not with latex particles of similar size. Co-culture of PBMC with bone particles in a transwell system where the cells were physically separated from the bone particles, or with osteoblast- or osteoclast-covered bone particles, did not stimulate IL-1 release, indicating that a physical contact between PBMC and the bone surface is required for eliciting IL-1 release. This was confirmed by the finding of a lower stimulatory effect of bone particles pretreated with etidronate, a bisphosphonate which decreases the bone binding capacity of PBMC. Constituents of bone matrix, such as collagen fragments, hydroxyproline, and, to a lesser extent, transforming growth factor-beta, but not osteocalcin, alpha 2HS glycoprotein, fragments of either bone sialoprotein or osteopontin, and fibronectin, stimulated PBMC IL-1 release in a dose-dependent fashion. Collagen-stimulated IL-1 release was partially and specifically inhibited by a monoclonal antibody directed against the alpha 2 beta 1-integrin cell surface collagen receptor. These data demonstrate that products of bone resorption, known to be chemotactic for mononuclear cells, stimulate PBMC IL-1 activity. These findings may help explain previous documentation of increased IL-1 secretion by circulating monocytes obtained from patients with high turnover osteoporosis.

Animals↗
PubMed1990

Bisphosphonates directly inhibit the bone resorption activity of isolated avian osteoclasts in vitro.

Bisphosphonates are useful in treatment of disorders with increased osteoclastic activity, but the mechanism by which bisphosphonates act is unknown. We used cultures of chicken osteoclasts to address this issue, and found that 1-hydroxyethylidenediphosphonic acid (EHDP), dichloromethylidenediphosphonic acid (Cl2MDP), or 3-amino-1-hydroxypropylidene-1,1-diphosphonic acid (APD) all cause direct dose-dependent suppression of osteoclastic activity. Effects are mediated by bone-bound drugs, with 50% reduction of bone degradation occurring at 500 nM to 5 microM of the different agents. Osteoclastic bone-binding capacity decreased by 30-40% after 72 h of bisphosphonate treatment, despite maintenance of cell viability. Significant inhibition of bone resorption in each case is seen only after 24-72 h of treatment. Osteoclast activity depends on ATP-dependent proton transport. Using acridine orange as an indicator, we found that EHDP reduces proton accumulation by osteoclasts. However, inside-out plasma membrane vesicles from osteoclasts transport H+ normally in response to ATP in high concentrations of EHDP, Cl2MDP, or APD. This suggests that the bisphosphonates act as metabolic inhibitors. Bisphosphonates reduce osteoclastic protein synthesis, supporting this hypothesis. Furthermore, [3H]leucine incorporation by the fibroblast, which does not resorb bone, is also diminished by EHDP, Cl2MDP and APD except when co-cultured with bisphosphonate-binding bone particles. Thus, the resorption-antagonizing capacities of EHDP, Cl2MDP and APD reflect metabolic inhibition, with selectivity for the osteoclast resulting from high affinity binding to bone mineral.

Animals↗
PubMed1990

[Ultrasound in endodontics: S.E.M. verification].

After giving a brief illustration of the complex morphology of the root canal system, the Authors discuss the use of ultrasound in Endodontics. Following a critical evaluation of the literature and of the mechanisms of ultrasonic instruments, they illustrate their experience through a wide selection of S.E.M. photographs of teeth treated in vitro with sodium hypochlorite at various concentrations and for different lengths of time. They demonstrate the synergistic action between ultrasound and irrigation solutions, and conclude that the best results are with 2.5% hypochlorite for 1 minute.

Dental Pulp Cavity↗