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Biomedical subjects

B Shroff

Publications and source records attributed to B Shroff.

17 recordsLinked to original sources
PubMed1998

Treatment of patients with asymmetries using asymmetric mechanics.

The orthodontic correction of dental asymmetries is often considered a difficult and challenging process, primarily because of misdiagnosis and poorly planned treatment mechanics. A careful differential diagnosis together with a thorough treatment plan can ensure successful treatment outcomes in the management of these malocclusions. In this article, key elements of differential diagnosis and treatment planning are reviewed. Different treatment strategies, including an analysis of the side effects associated with the use of these appliance systems, are described. This approach will help the clinician to best adapt treatment mechanics to a given malocclusion.

Dental Arch↗
PubMed1997

Effect of pumice prophylaxis on the bond strength of orthodontic brackets.

Pumice prophylaxis has long been accepted as a prerequisite for achieving adequate enamel etching during orthodontic bonding procedures. Three methods were used in this study to examine the effects of pumice prophylaxis on the bond strength of orthodontic brackets: (1) shear bond strength of brackets that were bonded to extracted premolars after surface preparation procedures, which either included or did not include prior pumice prophylaxis, was evaluated; (2) scanning electron microscopy (SEM) was used to examine the surface characteristics of teeth that had been etched with and without prior pumice prophylaxis; and (3) rate of bracket failure in patients who had had brackets bonded with and without prior pumice prophylaxis was recorded during an average treatment time of 18 months. No significant differences were noted in bond strength, general etched enamel surface characteristics, or bracket retention rates. Some specific differences, however, were noted on SEM in localized areas of the etched enamel surfaces, although these did not appear to affect the bond strength or bracket retention rates ultimately attained.

Acid Etching, Dental↗
PubMed1997

Simultaneous intrusion and retraction using a three-piece base arch.

Flared incisors and deep overbite are challenging to treat orthodontically. This paper describes the use of a three-piece base arch and Class I elastics to correct deep overbite while simultaneously closing spaces. An analysis of the biomechanics and a discussion of the appliance design are presented to help understand how the incisor axial inclination can be corrected and controlled during orthodontic therapy. A clinical example illustrates the treatment sequence.

Adult↗
PubMed1997

Class II subdivision treatment with tip-back moments.

Unilateral tip-back mechanics are challenging because of a number of undesirable side-effects associated with their use during orthodontic treatment. The purpose of this paper is to review the differential diagnosis and treatment planning of Class II subdivision malocclusions and present a treatment strategy based on a careful biomechanical analysis of the clinical situation. Emphasis is placed on the correction of molar axial inclination using unilateral tip-back moments in the treatment of dental asymmetries. Appliance design and treatment sequencing are also discussed.

Biomechanical Phenomena↗
PubMed1996

Epidermal growth factor and epidermal growth factor-receptor expression in the mouse dental follicle during tooth eruption.

When the role of exogenous epidermal growth factor (EGF) during tooth eruption was first demonstrated it was strongly suggested that EGF was a natural regulator of eruption. Recent immunohistochemical studies have shown that EGF and EGF-receptors are localized in the dental follicle, alveolar bone and ameloblasts before and during the prefunctional stage of eruption. Localization of mRNA for EGF has also been successfully attempted in mouse incisors and molars. The purpose now was to study the temporal expression of EGF and EGF-receptor genes in the coronal aspect of the dental follicle. First molars from 2-, 5-, 9- and 11-day-old CD-1 mouse neonates were incubated in 1% trypsin for 1.5 h at 4 degrees C. Follicles were carefully separated from the coronal aspect of the molar and processed for RNA extraction. Reverse transcriptase-polymerase chain reaction was performed on each mRNA sample. EGF expression was detected at day 2, 5 and 9 in the coronal aspect of the follicle whereas EGF-receptor expression was found at day 9 only. These findings strongly suggest that cells of the dental follicle are the target of EGF at a specific stage of their development and therefore may have a very important role during eruption.

Actins↗
PubMed1996

Combined orthodontic and prosthetic therapy. Special considerations.

The adult patient may present with a complex medical and dental history. Comprehensive treatment planning with appropriate consultation among the restorative dentist and other dental specialists is a prerequisite for a successful treatment outcome. This article reviewed the role of orthodontic treatment in the restoration of the partially edentulous patient. The case illustrations presented show the value of collaborative efforts in a multidisciplinary team approach. Although there may be initial reluctance on the part of some patients to seek multiple specialty consultations, the rewards are great for the patient and the dentists who subscribe to this treatment philosophy.

Adolescent↗
PubMed1995

Protease activity in the mouse dental follicle during tooth eruption.

Eruption results in the movement of the tooth from an intraosseous to a functional position in the mouth. This physiological movement occurs through a path of least resistance and is mediated by the dental follicle. In this study the presence of a 80-kDa proteinase of the gelatinase family in the dental follicle of mandibular first molars obtained from CD-1 mouse neonates was investigated by zymography on sodium dodecyl sulphate-gelatin. The results showed a differential distribution of this proteinase in the coronal and apical parts of the follicle at postnatal days 9 and 11. The findings suggest that the onset of this differential enzymatic activity is concomitant with the initiation of tooth eruption.

Animals↗
PubMed1995

Segmented approach to simultaneous intrusion and space closure: biomechanics of the three-piece base arch appliance.

Deep overbite correction and space closure in patients with flared incisors are mechanically difficult to achieve with conventional orthodontic treatment. The purpose of this article is to present an appliance design that allows simultaneous intrusion and retraction of anterior teeth as well as correction of their axial inclinations. A three-piece base arch was used to achieve simultaneous intrusion and space closure. Various clinical situations are discussed and analyzed from a biomechanical standpoint. Sequences of treatment, appliance design, and management of side effects are described in detail. The segmented approach to simultaneous intrusion and space closure is useful for achieving precise control of tooth movements in the anteroposterior and vertical dimensions.

Child↗
PubMed1994

Dynamic variations in the expression of type I collagen and its molecular chaperone Hsp47 in cells of the mouse dental follicle during tooth eruption.

Tooth eruption is a precisely timed and sequenced event that brings the tooth from within bone into a functional position in the mouth. Every part of the developing tooth has been theoretically implicated as a primary factor in this process, but it now appears that eruption is multifactorial, with the dental follicle and type I collagen playing an important part. Immunological probes were used here to investigate in vivo and in vitro the temporal and spatial expression of type I collagen and its molecular chaperone Hsp47 in the dental follicle during eruption. Mandibles were dissected from 2-, 5-, 9- and 11-day-old neonatal mice and fixed in 95% ethanol overnight. Sections of 7 microns were obtained and reacted with antibodies directed against type I collagen. Dental follicles were isolated from 2-, 5-, 9- and 11-day-old neonates and cells were grown in culture for 8 days. Slides were then reacted with antibodies directed against type I collagen and Hsp47. The production of type I collagen and Hsp47 in the follicle varied with the stage of dental development and eruption. There was a progressive decrease of type I collagen in the coronal part of the follicle, leading to an arrest of its production in these areas. These findings support the notion that cells of the coronal portion of the dental follicle stop producing type I collagen as a prerequisite to the initiation of tooth eruption and that this phenotype persists in vitro.

Animals↗
PubMed1993

Hsp 47 is localized to regions of type I collagen production in developing murine femurs and molars.

To determine whether the proposed molecular chaperone Hsp47 is associated with the production of heterotrimeric procollagen, the distribution of anti-Hsp47 and anti-collagen antibodies were examined in developing murine femurs and molars of 22-23-day CD-1 mice. In addition, the expression of Hsp47, and collagen mRNAs were assessed by in situ hybridization using oligonucleotide probes. These studies revealed that Hsp47 was developmentally expressed and produced in regions that are coincident with type I collagen. Hsp47 was not localized in cartilaginous zones of developing femurs or in the regions of developing molars producing type III collagen. These results support the hypothesis that Hsp47 is necessary for the assurance of type I procollagen and is not expressed with other homotrimeric procollagen molecules.

Animals↗
PubMed1993

Adjunctive orthodontic therapy in restorative dentistry.

This article focuses on the interaction between the orthodontist and other dental specialists to facilitate combined treatment of permanent dentition and mutilated dentition. The importance of careful and precise treatment planning of such malocclusions, including a thorough restorative and periodontal treatment plan, is emphasized. Clinical examples that range from adjunctive minor orthodontic therapy to combined orthognathic surgery treatment are presented.

Adolescent↗
PubMed1992

Investigation of the role of Von Korff fibers during murine dentinogenesis.

The existence and significance of Von Korff fibers during early dentinogenesis are still very controversial. The purpose of the present study was to re-examine the questions of the existence, nature and significance of Von Korff's fibers using light microscopy and immunohistochemistry. Specimens were obtained from 3 days-old CD-I mice and mandibles were carefully dissected under constant irrigation and immediately fixed in 10% neutral buffered formalin for light microscopy. Sections were treated or not with collagenase prior to silver staining. For immunohistochemistry, specimens were fixed in 95% ethanol and embedded in paraffin. Sections were reacted with goat anti-human-bovine type I or type III collagen and a rhodamine (RITC) labelled rabbit anti-goat IgG was then reacted as a secondary antibody. Slides were then examined under a Zeiss II photomicroscope equipped with epifluorescence. Our results have confirmed the presence of argyrophilic material concentrated at the periphery of the dental papilla and stretching from the subodontoblastic layer to the future dentino enamel junction. The distribution of type III collagen was very similar to the distribution of the silver staining at the cervical loop area. Type I collagen distribution was different and concentrated in areas where odontoblasts were fully differentiated. Our study showed that Von Korff fibers are not artefactual. We have established the presence of an apical compartment containing type I collagen fibers and a basal compartment containing type III collagen to explain the image of continuous silver staining crossing the entire thickness of the odontoblast layer.

Animals↗
PubMed1992

Mineral-associated adhesion proteins are linked to root formation.

There is a general agreement that the extracellular environment plays a critical role in controlling cell behavior. Thus, significant research efforts have focused on understanding the effects of extracellular matrix proteins on cell function. In particular we have focused on determining the role of adhesion proteins in the regulation of root formation. Using an OPN antibody, 2arN (generously provided by Drs Craig and Denhardt), the expression of OPN during root formation was determined. OPN (osteopontin) is a bone-associated adhesion protein. OPN was expressed in the dental follicle region of molars obtained from 3 day old CD-1 mice, but was not expressed in the odontoblast layer. In contrast by day 8, positive staining was noted in the odontoblast layer, as well as in the area of Hertwig's epithelial root sheath. However, at this same time point no positive labeling for 2arN was observed in the enamel organ or in the dental papillae cells. By day 15 positive staining for OPN was seen in the area of the periodontal ligament, as well as the region of primary deposition of extracellular matrix onto dentin. Also determined was the ability of fibronectin, OPN and dentin sialoprotein (DSP) to promote the attachment of dental ectomesenchymal cells, in vitro. Interestingly, these cells attached remarkable well on bacteriological dishes (control) in the absence of an adhesion protein. DSP did not increase cell attachment beyond that observed for control cells. In contrast, both fibronectin and OPN enhanced cell attachment. These studies, while preliminary indicate that OPN is expressed in a unique fashion during root development, thus suggesting a regulatory role for such adhesion proteins during root formation.

Animals↗
PubMed1990

Expression of attachment proteins during cementogenesis.

There is general agreement that during development the extracellular environment plays a critical role in controlling cell differentiation. Data generated from numerous studies support the possibility that cell attachment proteins and their corresponding cell receptors are possible candidates for this role. In particular, our studies are directed at identifying attachment proteins in mature cementum and establishing the function of these proteins during root formation. Fractionation of guanidine HCL/EDTA extracts of cementum revealed the presence of a bone-associated attachment, BSP, as well as fractions containing as of yet undetermined attachment proteins. Immunofluorescent examination of 1st molar tissues during root formation, obtained from 7 day-old mice neonates, for bone-associated attachment proteins indicated that osteopontin is expressed in the area of Hertwig's epithelial root sheath, but not in the region of the dental papillae. However, dental papillae cells, considered to have the capacity to form cementum, attached to osteopontin coated dishes, in vitro. Thus, unique attachment proteins, as well as those previously identified, were found in mature cementum and during root development. Future studies focused on identifying attachment proteins of mature cementum and determining the spatial and temporal localization of these proteins, pre- and post-cementogenesis, will provide important information necessary for establishing the function of these proteins during root development.

Animals↗