Denture Adhesives: as A Denture Retentive Aid

Denture adhesives have been the objective of scientific research for over half a century. The use of denture adhesives is common among denture wearers, and it is also prescribed by many dentists. Prescribing denture adhesives has been viewed by many Prosthodontists as a means of compensating for any defects in the fabrication procedures. Denture adhesives add to the retention and thereby improve chewing ability, reduce any instability, provide comfort and eliminate the accumulation of food debris beneath the dentures. Consequently, they increase the patient's sense of security and satisfaction. However, obtaining the advice of the dental practitioner prior to the use of adhesives is a must. Although they are used worldwide, investigations of their effectiveness and biocompatibility have led to controversial conclusions

Xerostomia and Prosthodontic Conduct

Xerostomia or dry mouth is a condition frequently seen in dental practice.  The elderly people are at greater risk because they undergo medications, systemic diseases or various radiotherapy of the head and neck region. Patient complains of problems in mastication, phonetics, deglutition and in wearing dentures. Patients are at increased risk of developing dental caries usually multiple. Treatment may include the review of the current prescription drug regimen, ongoing dental care, caries prevention, use of salivary substitutes, salivary stimulants, salivary reservoirs and salivary sensors. A thorough clinical examination by the clinician is important for diagnosis, management, treatment and evaluation of the xerostomia patient

Comparison of the three-dimensional structures of a humanized and a chimeric Fab of an anti-γ-interferon antibody

The objective of this work is to compare the three-dimensional structures of 'humanized' and mouse-human chimetic forms of a murine monoclonal antibody elicited against human γ-interferon. It is also to provide structural explanations for the small differences in the affinities and biological interactions of the two molecules for this antigen. Antigen-binding fragments (Fabs) were produced by papain hydrolysis of the antibodies and crystallized with polyethylene glycol (PEG) 8000 by nearly identical microseeding procedures. Their structures were solved by X-ray analyses at 2.9 A resolution, using molecular replacement methods and crystallographic refinement. Comparison of these structures revealed marked similarities in the light (L) chains and near identities of the constant (C) domains of the heavy (H) chains. However, the variable (V) domains of the heavy chains exhibited substantial differences in the conformations of all three complementarity-determining regions (CDRs), and in their first framework segments (FR1). In FR1 of the humanized V(H), the substitution of serine for proline in position 7 allowed the N-terminal segment (designated strand 4-1) to be closely juxtaposed to an adjacent strand (4-2) and form hydrogen bonds typical of an antiparallel β-pleated sheet. The tightening of the humanized structure was relayed in such a way as to decrease the space available for the last portion of HFR1 and the first part of HCDR1. This compression led to the formation of an α-helix involving residues 25-32. With fewer steric constraints, the corresponding segment in the chimeric Fab lengthened by at least 1 A to a random coil which terminated in a single turn of 3 helix. In the humanized Fab, HCDR1, which is sandwiched between HCDR2 and HCDR3, significantly influenced the structures of both regions. HCDR2 was forced into a bent and twisted orientation different from that in the chimeric Fab, both at the crown of the loop (around proline H52a) and at its base. As in HCDR1, the last few residues of HCDR2 in the humanized Fab were compressed into a space-saving α-helix, contrasting with a more extended 3 helix in the chimetic form. HCDR3 in the humanized Fab was also adjusted in shape and topography. The observed similarities in the functional binding activities of the two molecules can be rationalized by limited induced fit adjustments in their structures on antigen binding. While not perfect replicas, the two structures are testimonials to the progress in making high affinity monoclonal antibodies safe for human use