Magnets have been used in Prosthodontics since 1960 for various purposes, like for retention in over dentures, implant-supported dentures, partial dentures and for maxillo facial prostheses. However, insufficient literature is available in this aspect of treatment procedure. Part I of this article discusses history of dental magnets, different types available, classification, their general properties, mechanism of action, biocompatibility and recent developments in great detail.

Accurate interocclusal registrations are an integral part of prosthetic rehabilitation. The success of rehabilitation treatment is closely related to an exact reproduction of occlusal relation in the articulator during all stages of treatment. This article describes a method of making an accurate interocclusal record when the most distal tooth is an abutment of a fixed partial denture. In this method a centric stop or vertical stop is prepared to maintain the vertical dimension of occlusion and to act as third point of reference for a stable occlusal relationship when occluding the definitive casts on articulators.

Posts were designed to retain the coronal restoration when inadequate tooth structure remained, for reinforcing endodontically treated teeth. Metallic posts being more rigid than the tooth structure undermines its usage. Due to the forces there could be differential movements of the components and the tooth, resulting in their separation or fracture. The metallic posts have aesthetic shortcomings especially when the newer all ceramic materials are used for restoring the anterior teeth. The growing demand for esthetic restorations in dentistry has led to development of tooth-colored, metal free post systems like carbon fiber posts, zirconia posts, glass fiber posts [translucent quartz fiber] and woven fibers[polyethylene fibers]which are discussed in this article.

The corrosion of dental biomaterials is a pertinent clinical issue. In spite of the recent innovative metallurgical and technological advances and remarkable progress in the design and development of surgical and dental materials, failures do occur. The present article describes the problem of corrosion in titanium dental implants. The clinical significance of the dental implant corrosion is highlighted and the most common form of corrosion i.e. galvanic corrosion is emphasized both in vitro and in vivo conditions. The article is presented keeping in view of carrying out different studies for indigenous titanium dental implant and indigenous alloys. The Department of Dental Research at Institute of Nuclear Medicine & Allied Sciences has developed indigenous Titanium Dental Implants and Base metal Alloys. The studies carried out have proven their biocompatibility and suitability to be used for oral defects. The aim of the study is to evaluate galvanic corrosion current around indigenously developed Titanium Dental Implant when coupled to a Base metal Alloy.

With the advent of newer provisional crown and bridge material it has become imperative to evaluate their strength and know the tissue response of these materials in order to select the appropriate one. This study takes a comparative view of two commonly used acrylic resin materials i.e. self polymerizing poly - methyl methacrylate (PMMA) and heat polymerizing poly - methyl methacrylate with a newly introduced composite resin Protemp-II, claiming better handling, strength and esthetics. To simulate the oral condition, the fracture resistance of selected materials was tested by three point bent test on Instron testing machine. The highest values for fracture resistance were displayed by heat polymerized PMMA followed by Protemp-II and self polymerized PMMA.

Historical reference to tongue tie may be found beginning in biblical time: 'and the string of his tongue loosened and he spoke plain'. [Mark 7:35] (Lalakea and Messner, Pediatr Clin N Am, 50, 2003, 381). Tongue tie (more formally known as ankyloglossia) is a congenital anomaly characterized by an abnormally short lingual frenulum; which restricts the mobility of the tongue. The clinical significance of this anomaly and the best method of management is a subject of debate (Fanibunda, Dental Uptade, 25, 1998, 296). We sought to identify the problems faced by the dental and medical professionals during the clinical treatment of these patients and to know the attitude of the patient towards it.

The orientation of the occlusal plane is an important clinical procedure in prosthodontic treatment for edentulous patients. Various intraoral and extraoral landmarks have been used for the orientation of the occlusal plane, but none of them give sufficient guidelines for that purpose. Therefore, a study was carried out to ascertain the role of intraoral and extraoral soft tissue landmarks in determining the occlusal plane. 30 Indian subjects ranging in age from 19-23 years were selected from a group of approximately 200 dental students. The soft tissue landmarks considered in the study were retromolar pad, parotid papilla, commissure of the lips, buccinator groove, and ala-tragus line. An indigeneously fabricated "Occlusal plane relator" was used to find out the relative parallelism of the ala-tragus line and the occlusal plane. This device had a base with a vertical arm over which a sliding ball and socket joint was placed. This joint had a direct connection with the anterior occlusal plane indicator and ala-tragus line indicator. Absolute mean was taken of the two readings on ala-tragus line indicator on either side of the face. The line in which the difference between the two readings was least was parallel to the occlusal plane. The lower 1/3rd of the retromolar pad was observed to be consistent with the mandibular occlusal plane. The mean distance of the parotid papilla was 2.56 mm above the maxillary occlusal plane. The mean values of all readings of buccinator groove was 0.94 mm below the mandibular occlusal plane. In this study close correlation was observed between the mandibular occlusal plane and the commissure of the lips; the mandibular occlusal plane and the buccinator groove. The line drawn from the ala of the nose to the middle of the tragus was found to be parallel to the maxillary occlusal plane.

Prosthodontic treatment of an endodontically treated tooth poses a challenge to the practitioner. Endodontic therapy has provided a solution to retain mutilated teeth. Coronoradicular reconstruction in the form of cast post and core is used as a method to provide retention and resistance form to the restoration. Endodontically treated teeth are dessicated, inelastic and brittle& have lower resistance to caries. Their inability to form secondary dentin makes them weak and susceptible to fracture. To prevent fracture and support crown and bridge, reinforcement in the form of intraradicular devices is being used. A cast post is one such method. Vertical and horizontal root fractures can occur as a result of excessive removal of tooth structure during root canal treatment, dowel placement or inceasing the width of the dowel. A cast post and core should fit passively in the canal. Even a minimally oversized post can lead to transfer of stresses to the canal walls and increase the risk of root fracture. Therefore it is necessary to ensure that there is passive fit of the post and core. Shrinkage of the mould cavity is desired during the casting process to allow a passive fit. The effect of lined and unlined rings in the dimensional behaviour of the investment during setting and subsequent heating has been investigated and it is shown that casting made of unlined rings are undersized.

The ultimate assessment of cast restoration lies in the accuracy of fit of the casting. Ring liners, through their compressibility, act as a buffer of pliable material between the expanding investment material and the rigid metallic ring. Asbestos, the traditionally used buffer, has now been found to be a potential carcinogen, leading to its withdrawal from use and subsequent introduction of its alternatives i.e. cellulose and ceramic ring liners. This in vitro study was undertaken to evaluate the marginal gap of complete crowns made by using wet and dry ceramic ring liners using a scanning electron microscope. Two groups of thirty castings each were prepared with dry and wet ceramic ring liners respectively and assessed for marginal fit. Results showed that crowns made by using dry ceramic ring liners had significantly less marginal gap as compared to the crowns made by using wet ceramic ring liners.

Prosthetic rehabilitation of acquired maxillary defects can be achieved satisfactorily if all facets of treatment planning and design considerations are taken well into account prior to the rehabilitation process. In many cases effective obturation is achieved but in the relative majority the prosthesis is usually rejected by the patient and the out come is a failure. Complications associated with maxillary defects limit the treatment protocols to a great extent. The prosthodontist has to identify these problem areas and suitably device feasible optons and incorporate them in the design. A case of acquired maxillary defect with limited mouth opening and unfavourable undercuts in the defect was successfully treated by making a two piece hollow bulb obturator. The two pieces were connected by the use of magnets. Additionally a transitional implant was placed so as to aid as an auxiliary retentive aid to enhace the overall treatment outcome. The methodology greatly reduced the chairside time and number of vists in the patient prospective and effective obturation was satisfactorily achieved.

Mini dental implants (MDI) are ultra-small diameter (l.8 millimeter width), biocompatible titanium alloy implant screws, conceived and designed over 20 years ago by a board-certified Manhattan dentist, Victor I. Sendax, DDS. Dr. R.A. Bulard added a single one piece 'O-ball' design to Dr. Sandax`s concept. These implants can be used in atrophic ridges, flabby ridges or in other cases where there is denture instability or lack of retention due to poor availability of residual bone. In this article, we shall discuss a case report of a 55 year old female patient with a severely atrophic mandibular ridge that was managed by the Mini Dental Implant system with an overdenture.