Wednesday, July 31, 2013

INDIAN DENTAL ACADEMY: Recent advances in Prosthetic Dentistry

INDIAN DENTAL ACADEMY: Recent advances in Prosthetic Dentistry:   ADVANCES IN FIELD OF 1.             GENERAL 2.              COMPLETE DENTURE PROTHESIS 3.              FIXED PARTIAL DEN...

Recent advances in Prosthetic Dentistry

1.             GENERAL





6.             ORAL IMPLANTOLOGY


The only thing in life that is constant is change, and developement and the developement is the essence of any change - Human Society ever since its advant house undergone various changes starting from discovery of wheels and fire to revolutionary invention of super computers and aircrafts that defy all the laws of gravity.
Moreover, human beings have used and misused their power of knowledge in various ways both for good as well as evil.
In one hand they have created nuclear weapons, gamma radiations of which is still giving birth to a crippled child's, on the other hands they have also invented life saving drugs, a drug which made hearts beat back to life and drug which restored priceless vision of blinds.
Indeed this world have progressed in leaps and bounds on the similar lines too, oral and dental health's, like many aspects of human condition, are in the midst of major transition.
The scientific and technological basis of dentistry, are expanding rapidly in a world where alternative changes in the managements and financing of health care, the demography of our nation, and public expectations of better "quality of life".
Dentistry has come a long way from just replacing missing teeth to replacing lost alveolus supporting facial structures, recreating esthetics, reestablishing phonetics and many other major developments.
Most of all we can say that in prosthetics by using all the artificial materials as well as technologies we can give a natural appearance of an individual at the best of mankind.

Aust Dent Journal 2000 45:4
The  use of stereolithography for the manufacture of implantable prosthesis is relatively new aspects of this dentistry. Until now, its use with the regard to mandibular resection has been to produce pre-operative models that allows more sophisticated planning of the contour and better preparation of the metallic framework to be implanted. The framework rejoins the mandible restoring its function.
Data extracted from Computed Tomography (CT ) scan can be used to produce computer models of three dimensional (3D) anatomical structures. Using sterolithography, a rapid prototyping technique these computer models can be made into solid physical models.
The surface and internal structure of the anatomical site can be reproduced by polymerization of UV light sensitive liquid resin using a laser beam.
The laser rays progressively polymerise photomonomer on the surface of the vat solution.
The model is built vertically step by step as the polymerized section submerged beneath the surface of the solution.
These models are then used for diagnosis and treatment planning of various cases.

DCNA Vol 44 No 4, Oct 2000
The addition of laser surgery to reconstructive process can heighten the act and the science of this multidisciplinary field.
The current use of Lasers in Reconstructive Dentistry encomposes a wide variety of soft tissue procedures but the future may hold promise for hard tissue procedures too.

1.             Complete control of the oral environment at operative site is essential.
2.             Frequently cases are encountered in which gingival tissues need to be altered because of area of inflammation, previous subgingival restoration or subgingival caries.
3.             The finish line need to be placed near epithelial attachment making it impossible to retract the gingiva without stripping the attachment, bruising the periodontal ligament and creating uncontrolled bleeding.
4.             Recurrent Bleeding in gingival sulcus can make impression making impossible.
5.             In such cases SULCULAR LASER GINGIVOPLASTY can be used to develop a new, healthier gingival sulcus, to control haemorrhage, and to remove just enough epithelial attachment and periodontal ligament to facilitate the placement of Retraction cord.
6.             Laser Sulcur gingivoplasty improves impression Technique and minimizes gingival recession.

The importance of creating an environment for soft tissues around perimucosal portion of the implants cannot be over stated.
All implants must pass through the submucosa and overlying stratified Squamous Epithelium.
Misch considered this the weak link between prosthetis attachment and predictable bony support of the implant.
The gingival epithelium or biologic seal become an important factor in implant longevity.
If a biological seal is created from the begining of implant uncovering using laser technology vs. conventional surgery, the attached gingiva would heal directly around the implant, forming an epithelial cuff.
Implants may be uncovered protectively with laser energy.
Soft tissues > then 3mm thick should be reduced with laser to create an ideal pocket depth around the implant.

The use of low-energy lasers has recently gained considerable attention. They are primarily used to relieve pain, reduce inflammation and edema and accelerate healing. Studies on the biologic effects of low energy lasers have been concerned with the ability of such light to increase blood circulation within regenerated tissues to increase production of collagen by fibroblast and to promote a suppresive effect on the immune system.
Furthermore, increased mitotic activity has been reported, which indicates the growth stimulation occurs.
Recently, the bacteriocidal effect of light from a low energy laser was introduced as an alternative approach to Antibiotics and Antiseptics in eliminiting cariogen and periodontopathogenic bacteria from lesion.
The greatest benefit of using a low energy laser is its effects can be achieved without damaging host tissues and with protection to the operator.
The effect of therapeutic laser treatment on both soft tissues and bone with subsequent improvement of denture foundation after t/t of denture induced mucosal lesions.

UP Vol 7 No 1 1994
This study investigate, the development of Computer Aided System for designing and Fabrication of Complete Denture.
So far the use of CAD/CAM has primarily being foccused on fixed restoration such as inlays crown because difficulty in recording soft tissue morphologies of edentulous areas, and interocclusal relationship.
Methods of recording and measuring 3D morphology have been greatly improved with recent advancement of optoelectronic measuring unit CAD software.
Involve three major steps
(1)   Impression procedure
(2)   Denture designing
(3)   Denture fabrication
(1)           Impression procedure
1.     As the first step, an impression of the load bearing area of the residual ridge and denture borders was made for the maxillary and mandibular arches using a specially designed double impression trays with Conventional Rubber Base or Silicone impression material.
2.     Maxillary + Mandibular impressions are hold at specific V.H. and HR in patients mouth
3.     The double impression trays are transfered and mounted on a 3D laser scanner that has a rod around which both the impression can rotate to full 360°. Two dimensional images are recorded by spread laser beam and Four Charged-Couple device camera while the impression is made to move / mearly. Surface images are obtained at three different angles time required - 15 to 20 mins.
2. Denture design, Arrangement of Artificial Teeth
Denture space data are transfered to an engeenering work station. Artificial teeth and denture surface data from the database are overlaped and matched with those of the denture space.
Placement of Artificial Teeth is done to acchive proper stress distribution.
3. Denture Fabrication
Either a numerically controlled milling machine or 3-D laser lithography machine can be used.
Laser lithgraphy create 3D models of new products based on CAD design.
Therefore, only two outer shells (occlusal/polished part) and (tissue surface part) are photopolymerised.
Tooth shade acrylic resin composites are used to fill inside the occlusal portion and two surface are connected using reference point.
Tissue coloured autopolymerizing resin composite is then placed into the space and excess removed, and shells are polished using conventional manner.
J.P.C. MARCH 2002
In 1942 Stafne's described a series of Asymptomatic Radiolucent lesions located near the angle of the mandible. Subsequent reports have shown that these condition represents a well-defined concavity of the cortical bone on the lingual surface of the mandible.
The origin of this developmental depression is thought to be secondary to
a)            Entrapment of Salivary Gland parenchyma during the developmental process of mandible.
b)            Accentuation of the cavity.
c)             Indentation along the lingual aspect of the mandible that contains an extension of the submandibular gland.
Because of their location Stafen's Bone cavities have also been called lingual/ mandibular salivary gland depression or lingual/cortical mandibular defect.
Although the defects are thought to be developemental, they do not appear to be present at Birth. Occasionally the defects appears bilaterally.
They often appears radiographically as a round or ovoid, well circumscribed radioluscency. This reported incidence based on panoromic radiographic observation. They should be differentially diagnosed out from any Mandibular Cyst. Stafen's Bone Cavity ranges from 1 to 3 cm in diameter and they often present below the inferior Alveolar cannal.
Engagement of a mandibular denture in bilateral Stafen's Bone cavity aid in retention and stability of mandibular dentures.

J.P.D. AUG 2001 Vol 86 No 2.

Magnets have generated great interest within dentistry and their application are numerous.
The 2 main areas of their interest are in the field of orthodontics as well as Removable Prosthodontics.
The reason for their popularity is related to their small size and strong attractive forces allow them to be placed in prosthesis without being obtrusive within the mouth. Over the last century, significant advances have been made in the development of magnetic materials which have been quickly transfered into dental applications. The main magnetic materials used is the rare earth elements Neodynaim-Iron­Boron (Nd, Fe, B).
Other materials used include RE Alloy, Samarium-Cobalt (Sm-Co). Samarium iron nitride is a promising new candidate for permanent magnet application because of its high resistance to demagnetisation high magnetism and better resistance than Nd Fe B to temperature and Corrossion to oral fluids.
Another Advancement includes the Encapsulation of the pre-existing magnets within a relatively inert alloys such as stainless steal or titanium.

IJP Vol 8 No 3 1995
When patients suffer from fragile supporting mucosa, excessive residual ridge resorption, substantial undercuts and/or Traumatic or pathologic tissue, less, the clinician may opt for the use of a soft lining material between the intaglio surface of a prosthesis and the supporting tissues.
Soft tissue are useful to attenuate the discomfort result from the instability of improper adaptation of the prosthesis.
The selected material must
a)       minimize bone resorption
b)       protect supporting gingival tissues
c)       provides good surface condition that is can enable to clinical adjustment.
Materials include in this family of Denture liners are those in the family of Acrylic Resins.
a)       Dentimex BV
b)       Perform
c)       Dimethyl polysiloxanes (DMPS-Flexor)
d)       Ethylene Vinyl Acetate Copolymers
All of these materials behave visco-elastically, depending of their flexibility, which can be varied according to the selected thickness.Therefore, clinical choice between these different families is determined by the problems presented by the supporting tissues and the design of the prosthesis.
The denture bearing mucosa also exhibit viscoelastic properties.
Among the new denture liners is Benzene dimethyl polysiloxane materials permaflex establish the efficiency of the material as a resilient denture liners.

A new concept of Centric Relation is defined as "A clinically determined position of the mandible both condyles into their anterior uppermost position.
This defination defines the old defination is the centric relation is the relationship of the mandible to maxilla when the condyles are at the most posterior portion of the glenoid fossa.
Because some author belief that in Centric Relation all the load of the mandibular residual ridge are transfered to the joint cavity pushing the head of the condyle against the avuscular disc and the cavity wall. Recently it has been found
that there is evidence of nerve and blood vessels in this posterior aspect which can get compressed causing pain to the individuals. But such pains are not noted in the patient thereby suspecting the actual position of this condylar head in the joint cavity. So recently authors have suggested their position to be anterior uppermost position of joint cavity.

Dental Update Jan/Feb 2002
Ceramic materials new have a firmly established role in many aspects of clinical dentistry.
The success of recently introduced ceramic materials and systems may be attributed to several factors, including Technological advences and an increasing more towards the avoidence of use of metal in the mouth and their replacement with tooth coloured materials whenever possible.
As for all Restorative materials, improvement in strength, clinical performance and longevity, continue to drive the search for the ideal ceramic material.
To date, those ceramic materials which appear to have the strength for use in posterior teeth as full and partial coverage restoration include
a) In ceram (Vita Zahnfabrik Germany) b) Procera (Nobel Biocare)
c) Empress (Invoclar Vivadent)
In ceram core material is primarily crystalline in nature, whereas other forms of ceramics used in dentistry was largely compossed of glass matrix with a secondary crystalline phase.
In ceram is said to possess sufficient strength and toughness to be used for Ant and Post all ceramic restoration and fixed partial denture bridgework.
The types of In ceram are based on alumina, spinal (a mix of alumina and magnesia) or zirconia, which makes possible the fabrication of framework of different transluscency by use of different processing technique.
Flexural Strength and # Toughness of In ceram alumina are 2.5 and 3.5 times greater than those of conventional or high leucite ceramic.
Procera crowns (Nobel Biocare) combine the advantage of a metal coping with high precision processing techniques. The substructure is fabricated from titanium (a metal used widely in detnal implants and with a proven high degree of bio compatibility) using a combination of copy milling and spark erosion.
The aesthetic porcelain that overlays the metal core is of a low fusing composition to minimize excess oxdn of Titanium during firing.
This comprises of high-strength, densely sintered alumina core veenered with porcelain. A die constructed from an impression of a prepared tooth, is scanned to allow remote production of a densely sintered alumina core which is returned to the original laboratory for porcelain build up of the final crown.
Fracture resistance of ceramic restoration is dependent not only on the intrinsic strength and toughness of the material itself overall fitting accuracy also contribute to the ability of the restoration to withstand biting force.
Hot-pressed leucite-reinforced ceramic were introduced serving to reinforce the glossy matrix and prevant crack propogation.
With IPS Empress, 30-40% crystals content can be introduced before the aesthetic of the core and resulting restoration are compromised.
In IPS Empress 2, controlled crystallization production of a lithium disilicate glass ceramic enables the creation of a 60% crystal content by volume without loss of transluscency as the refractive index of the crystals is similar to that of glass matrix.
Furthermore the strength of the resultant material is reported to be 3 times that of original Empress.
The lithium disilicate glass ceramic serves as the underlying framework for IPS Empress 2, and the manufactures stated that the strength of the material is sufficient to withstand masticatory forces and to support edentulous area upto 9 mm in premolar and 11 mm in anterior region.
Fluoroapatite crystals are formed through controlled crystalization and are reported to be similar in shape and composition to those in natural teeth providing similar wear compatibility and optical properties.
It is also claimed that the fine grain structure and high crystallinity of the glass ceramic reduces the potential for wear of the opposing dentition.
There are definite clinical advantages of using Empress 2.
While 1.5mm of axial reduction is usually recomended for metal ceramics only I mm is needed for IPS Empress 2.
The first chair side produced ceramic inlay based on a CAD CAM unit. (Cerec, Siemens Germany) was placed in 1985 since when there have been seveal related developments including introdution of second generation in 1994 and in 2000 Cerec3.
Cerec 3 comprises both an acquisition and a milling unit which enables concurrent designs and production of restoration.
The softwares can be supplemented with Cerec 3 crown which contains a tooth library and is said to be suitable for the manufacture of all posterior restoration and anterior crowns.
Another option is the Cerec 3 Veneer software for producing anterior partial crowns and veneers.
The Cerec 3 milling unit has been seperated from the acquisition unit to enable simultaneous design and milling. The milling wheel had been replaced with tapered diamond bur reducing the machining process time by 3-5 mins.
The milling element is designed to accomodate the future option of fabricatint three unit Bridges.
Another feature is the Cerec Scan option for productin of restoration by indirect approach, in which a conventional model of the preparation and adjacent teeth is cast.
This is scanned with an integrated laser scanner, the model is then replaced with a ceramic block and the milling procedure commences.
To correct the problem of rounding or slumping of conventional porcelain margins after firing as the fusion temperature were identical, manufactures created special shoulder porcelain containing aluminous porcelain that fuses at temperatures 30°-80° higher than the dentin and enamel porcelain.
Advantages : Stability during firing cycles
Stronger in flexure than conventional porcelain making the margin more resistance to fracture.
Opalescence in dental porcelains is a light scattering effect acchived with the minute concentrations of high index refraction oxides in a size range near the wavelength of visible light.
The best documented member of this group is Dicor System (Trubyte Dentsply) which is a micaceous glass ceramic.
Restoration are produced with the lost wax technique and centrifual casting of heat-treated glass ceramic. Dicor causes less wear of opposing dentition than that of reinforced conventional porcelain.

Normal mastication puts enormous pressure on opposing dentition and when conventional porcelain comes in contact with tooth enamel, serious wear damage can occur.
Thats why you need the delicacy of Ceromer that's short for a CERamia optimised Polymer.
Targis Ceromer System provides the beauty and aesthetic capabilities of ceramic with flexural strength and shade control of resin.
This system protects and prevents the opposing tooth wear.
Targis ceramic polymer matrix can be heat cured or light cured to create. 1) Crowns
2) Inlays 3) Onlays 4) Implant superstructure (telescopic crown)
This materials can be directly applied over the cast as need of necessary restoration can be buid up to form crowns, inlays, onlays and bridges after heat curing or light curing method.
A -7

UP Vol 8 No 3 1995
Dental Ceramics can provide unsurpased aesthetic qualities when used to restore natural teeth. However one of the inherent disadvantages of these materials is the low tensile strength when unsupported and subjected to occlusal loading there is a tendency to fracture.
Many developments have been directed towards a strong less esthetic material metal or reinforced ceramic core that can be overlaid by weaker tooth coloured porcelain.
Thermal tempering and ion exchange have been used to improve the mechanical properties of existing dental porcelain. Thermal tempering produces a low thermal expansion surface layer that is placed in compression on cooling, thus increses resistance to tensile strengths.
Ion exchange is a similar approach that involves the replacement of monovalent ions at the surface of the glass with larger ions.
Compressive strength are generated in the surface layer and decrease the tendency towards crack propagation.
The effect has been attributed to the inward diffusion of potassium ions replacing the smaller sodium ions in the glass matrix.
Alternatively, sodium containing glasses have been strengthened by ion exchange with smaller lithium ions.
More recently the strengthening effect of leucite-reinforced porcelain by double ion exchange has generated considerable interest. Introduction of small lithium atoms followed by exchange with Rubidium has been reported to give superior strengthening.
Dispersive X-ray Analysis revealed that the depth of ion exchange was most marked within 1Opm below the surface, although it extend to atleast 100 mm,
UP Vol 8 No 2 1995
The technical and biophysical factors/involved in the fabrication of fixed restoration are of clinical importance for the long term prognosis for prosthodontic patients. Technical failures include loss of retention fracture of matal components and porclain veener fractures. Fractures through the porcelain or at the metal metaloxide layer interface are the result of metal porcelain-bond that is stronger than strength of porcelain-porcelain or metal-metal bond itself.
Adhesive failures occur when the bond between the metal and porcelain is inadequate. The application of the porcelain opaque layer is a critical step in preventing adhesive failure. Additionally, the opaque layer masks the metal, allowing appropiate shades to be obtained.
The traditional application of opaque porcelain begins with the mixing of porcelain powder with a liquid binder that commonly consisted of distilled water, alcohol and glycerine. The creamy opaque paste is applied to the metal substructure in a minimum of two layers. The first layer acts as a wetting layer and the subsequent layers fill in the irregularities and mask the metal.
Vita VMK-Paint-On 88 opaque and Opaque P are two conventional opaque systems. Recently a new opaque system called BIOPAQUE become commercially available. This opaque system can be directly applied to metal surface without mining and condensing. It offers easy application and decrease WT.

Additionally, uniform thickness and excellent opacity can be attained with Biopaque.
Opaque porcelain contains crystals having a high refractive index that disperse and reflects light masking the metal substructure and preventing it from influencing porcelain colour.
X-ray powder diffraction analysis of Biopaque demonstrate that only the base of this system is a newly developed material.
Biopaque attained superior clinical results with regard to technical and biologic failures as compared to the two other traditional opaque system.

Dental Update - Sept 2001
The recent years, non metal alternatives for post system have been introduced.
Composite materials are composed of fibres of carbon or silica surrounded by matrix of polymer resin.
The philosophy behind the use of these materials lies in the belief that a post should mimic the dentin of the root in its physical properties, distribute the stresses impossed in the root in most favourable ways to reduce chances of root #.
a. Carbon fibre Post
1.             Composipost :     Composed of 8mm pretensed (fibres arranged lingitudinally
within epoxy resins. The bundles are produced industrially and then machined into desired shape. Radioopaque in characteristic.
2.             Carbonite (1.2, 1.35, 1.5mm)
Differ from composipost in that bundles of fibres 6mm in dia braided together with epoxy matrix Arrangement gives increase Resistance to bending and torsion compared with parallel fibre arrangement.
3.             Mirafit Carbon :                Identical to Carbonite.
b Silica Fibre Post :           Carbon post do not lend them to utilise with all ceramic that alter aesthetics.
1.             Aesthetipost :                       Central core of carbonfibre surrounded by quartz fibres,   
arranged longitudinally.
2.             Aesthetiplus post :              Consisting entirely of Quartz fibre. More recently this
company has produced a transluscent quartz fibre post designed to permit light curing unit materials to be used for luiting.
3.             Snow post (,1.2mm, 1.4mm)
Composed of 60% longitudinally arranged silica zirconium glass fibres in epoxy resins. The surface is t/t with silane to enhance bonding with resin cements.
Cylindrical in shape with 3 ° tapper at apex.
4.             Light transmiting post
Transluscent post have been introduced in order to allow the use of light cured luiting agent, facilitate cement placement and evaluation of post seating prior to cement setting.
The original purpose of light transmitting post to provide a means of reconstituting roots with overly flared cannals caused by caries or over excessive endodontic procedure, the aim being to achieve union between remaining dentin and light cured composite, thereby restoring the lost bulk and original root strength.

The use of ceramic to provide a core and a post retention continues the idea of using a tough but aesthetic material to support all ceramic units.
The introduction of zirconium oxide ceramics has provided a material with over twice the flexure strength of Aluminus Ceramic System.
Building a core of ceramic directly onto the zirconia post has not been possible awing to ~ in coefficient of thermal expansion of core and post material. Ceramic cores and thus to be fabricated indirectly and then luted around the protuded end of post.
Cosmpost (1.4mm, 1.7mm) :            Cylindrically shaped with a conical tip lvoclar/
Posts have smooth surfaces and are subsequently t/t to roughen the surface which increased Bond strength between post and core.

Quintessence Int  Daniel Edelhoff
Metal free restorative material are oppening doors to new preparation methods of fixed partial denture prosthesis.
As the results of developement in past few years various metal free systems that can be used to fabricate short span fixed partial Denture (FPD) are now available. Generally metal-reinforced systems are the materials of choice for fabricating posterior fixed partial denture (FPD) because of their reliability and durability, but this system facilitate the periodontal assessment and preserving the healthy tooth structure.

Basic disadvantages in metal alloy_
1.             Base metal components that form on the surface of the alloy during the metal­ceramic fusing process may have a negetive effect on adjacent soft tissues.
2.             Opaque darkish appearance caused by certain metal denture retainers in abutment seem to be unesthetic. Consequently highly aesthetically acceptable materials - High strength pressed ceramic and fibre reinforced composites (FRC) have achieved a certain degree of popularities.

Matel free inlay retained FPD fabricated with High strength pressed ceramic.

Following pre requisites must be met of successful results are to be achieved –
a)            Good Oral Hygine
b)            Low Susceptibility to Caries
c)             Parallel alignment of abutment teeth.
d)            Minimum height of Abutment teth >5mm Coronogingivally.
c)             Maximum mesiodistal extension of interdental gap of 9mm if pressed ceramic and 12mm of Fibre reinforced composites are used.

a)            2mm occlusal preparation depth (floor of isthmus - central groove)
b)            1.5mm preparation depth of proximal box (shoulder with rounded internal angle).
c)             Isthmus width of 1.5mm to 2mm in premolars and 2.5-3mm in molars. d)            Proximal angle of the internal cavity surface to the enamel surface 100°-120°.
c)             Minimum dia of connectors 4mm x 5mm.
f)             Divergence angle of cavity approx 6°.

Quintessence Int Vol 33 No 4 2002
Anterior primary tooth loss frequently occurs in young children (ages 6 to 36 months) despite all the routine preventive measures used in paediatric dentistry. Particularly susceptible to this phenomenon is Maxillary Central Incisors. Use of Removable Functional. Space Maintainers is recomended as a therapeutic approach to treatment.
Fixed Space Maintainers of properly designed are less damaging to the oral tissues than removable space maintainers.
A Resinbonded Prosthesis without rigid connectors permits normal physiologic premaxillary growth because it does not provide a rigid connection between the pontics.
The use of fixed prosthesis in children in limited by the arch modification that results from the developement of primary and mixed dentition occlusion. However a period of stability exists in which fixed appliances may be used i. e. in age of 3-5.5 yrs in which primary arch is completed and the sagital and transverse dimensions are unaltered.
The Crownless Bridge Works System (CBW Co) was developed in by Nijwegen University as an advancement of Universal Dental Anchorage (UDA) Plus System.
With this system it is possible to replace both anterior and posterior teeth with a strong prosthesis of single or multiple pontics and at the same time to preserve abutment teeth.

The CWB system combines techniques derived from the UDA prosthesis system with a system that utilizes precision connectors attached to Abutment Teeth, with pins comented in proximal aspect.
The CBW system combine two retention techniques, the anchorage and adhesive system.
In addition to the aesthetic advancements provided by minimal need to alter support teeth, the system offers following advantages
1.             Minimally invasive abutment preparation.
2.             Improved distribution of loads compared to that with adhesive prosthesis.
3.             Few periodontal problems because of absence of margins.
4.             Reversible and easily repairable system.
5.             No alternation in occlusion.
6.             Minimal stress to patients.

The introduction of pre impregnated fibre reinforced resin composite has provided the dental profession with the oppurtunity to fabricate and deliver adhesive, esthetic and metal free tooth replacement.
The introduction of preimpregnated fibre reinforced composite (FRC) has provided another options for chairside fixed partial denture (FPD) fabrication.
Indications of this FRC FPD
l.              Emergency replacement of Tooth lost due to Trauma.
2.             Ant Tooth extracted due to failed Endodontic procedure.
3.             Fixed space maintainer, after Orthodontic Treatment.
4.             Prior to loading of Implants.
The wings are composed of a strip of unidirectional FRC sandiwiched between 2 woven Fibre Reinforced Composite Strips.
Three unpolymerized FRC wings are covered with thin foil sheath to prevent contamination and/or premature polymerization.
The model of the edentulous space is made from Alginate Impression.
The important pre-chairside steps include positioning of the prefabricated FPD on the model trimming the wings to fit within the Abutments creating proximal retentive locks and forming intraoral putty positioning index.
Prefabricated FRC FPD being caried to the position in the incisal intraoral positioning matrix. The unpolymerized listing particulate resin composite is now polymerized, with FPD in that position.
Impression making for all fixed prosthesis requires access to the prosthetic margin white minimally traumatizing the tissue, so that clinician can produce as much clinical information as possible to laboratory.
Expa-syl is newly introduced unique paste system specifically designed for gingival retraction that ensures seperation of the gingival margin and drying of the sulcus.
Expa-syl is injected into the sulcus left in space for approx 1 to 2 mins and then thoroughly rinsed with air/water spray. The sulcus is left open and dry ready for impression making.
Expasyl composed mainly of two materials Kaolin and A12 Cl, act as an haemostatic agent, Kaolin is a clay like material responsible for the body or rigidity of the material.
Expasyl is an water soluble paste so it should be used without salivary contamination.
Clinician should be aware of potential interaction between Expasyl and Impression material especially Alginates and Polyether with A12C13 Ideally Expasyl should be used with polyvinyl siloxane impression.

JPD March 1999 Vol 81 No 3
Post Coping Restoration can be fabricated using a direct, indirect or combination direct-indirect method.
Traditionally working cast are mode of stone. Stone cast requires atleast 1 hr for setting. They also sometimes # during seperation of the cast from the impression. The use of cast that is available chairside within mins of impression making would save valuable chairside time and improve the accuracy of coping margins.
In this procedure custom post is fabricated directly into the root cannal space with pattern resin (Duralay). Core is also fabricated minimal Retentive grooves are placed in resin pattern core to look the post into the impression material.
After placing the gingival retraction cord around the teeth to provide access to intracrevicular margins, an impression is made with Polyether Elastomeric Impression Material.
Ensure for accurate reproduction of the margin and the retention of post within the impression.
Lightly lubricate the posts with petrolleum jelly and a flexible working cast is poured with Mach 2 die system using 2 stage pouring Technique.
After 6mins the flexible cast is seperated and die is made new fabrication of coping is done on the cast using an indirect method.
UP Vol 9 No 5 1996
Endosseous Dental Implants of seveal designs and materials have improved the prognosis for the successful restoration of partially or completely edentulous patient. Implant survival is primarily dependent upon the establishment of osseointegration, characterised by lack of an intervening soft tissue layer at the interface of implant surface and supporting bone.
In patients with poor oral hygine around implant supported fixed restoration alveolar bone loss is greater.
The types and abundance of micro organisms in dental plaque deposits vary with the degree of implant surface toughness at transmucosal junction. Surface properties such as hydrophobicity of various materials also appear to be an important to dental plaque adherence.
Despite the widespread used of polished titanium collars as transmucosal elements in implant system, relatively few studies appear to have been carried out on dental plaque formation on these surfaces.
This study compare the responses of the peri-implant soft tissues to titanium and ceramic coated surfaces of removable Transmucosal Element (TME) of established IM2 implant system.
Conventional IM2 TME were modified in the laboratory by addition of dental ceramic coating.

IJP Vol 9 No 5 1996
Endosseous Dental Implants of several designs and materials have improved the prognosis for the successful restoration of partially and completely edentulous patient.
Implant survival is primarily dependent upon the establishment of osseointegration, characterized by lack of an intervening soft tissue layer at the interface of implant surface and supporting bone.
In patients with poor oral hygiene around implant supported fixed restoration alveolar bone loss is greater.
The types and abundance of micro organisms in dental plaque deposits vary with the degree of implant surface toughness at transmucosal junction. Surface properties such as hydrophobicity of various materials also appear to be an important to dental plaque adherence.
Despite the widespread used of polished titanium collars as transmucosal elements in implant system, relatively few studies appear to have been carried out on dental plaque formation on these surfaces.
This study compares the responses of the peri-implant soft tissues to titanium and ceramic coated surfaces of removable Transmucosal Element (TME) of established IM2 implant system.
Conventional IM2 TME were modified in the laboratory by addition of dental ceramic coating.

In a group of patients with two functional IM2 implants linked by a Dolder0type bar to support a complete mandibular Removable prosthesis, existing THE were replaced by ceramic coated THE on one side and a comentional TME on other side.
A range of clinical parameters was used to assess the responses of the soft tissue at intervals of 1, 4 and 12 weeks.
Results shows that
The scores of accumulation of plaque deposit on ceramic coated transmucosal element were significantly lower than those recorded for titanium transmucosal elements. 


JPD Vol 87 No 2 FEB 2002 
This study evaluate the implant success and periimplant tissue response of immediately loaded threaded hydroxyapatite (HA) coated root form implants supporting mandibular bar over denture with opposing conventional maxillary over denture. Osseointegrated Endosseous implants have been a successful modalities for t/t completely or partially edentulous patient. To achieve this osseointegration certain guidelines are to be followed 
1. A complete aseptic and ......... surgical technique. 2. A complete soft tissue coverage. 
3. An extended healing time during which no load should be given. 
Periods of 3 to 4 moinths and 4 to 6 months have been recomended as healing times for osseointegrated implants placed in the mandible and maxilla respectively. Faster osseous adaptation has been demonstrated with Hydroxyapatite coated (HA) implants. 
Johson reported complications associated with HA-coated implants and suggested that the HA coatings are more succeptible to bacterial infection and rapid asseous breakdown. 
Babbush et al described a technique of immediately loading 4 Titanium plasma sprayed (TPS) implants placed in mandibular symphysis with an overdenture. The implants were rigidly splinted by metal bar and the denture was relined within 2 to 3 days after surgery. 
The final clip prosthesis were placed 2-3 weeks later. 
The author reported a cumulative failure rate is more in the cases of HA coated threaded root form implants than conventional root form implants. 

JPD Vol 77 1997 
The use of Implants for orthodontic anchorage can produce superior preprosthetic tooth position. 
Their use often requires a crown or prosthesis to be fabricated for use as a connection between the orthodontic device and the implant. 
Dental Implants because of their stability could serve as an ideal anchorage unit. Anchorage control is fundamental to successful orthodontic treatment and Dentofacial Orthopedics.
Prosthodontic advantages of implant orthodontic anchorage
Implants have been found to produce superior preprosthetic tooth position in the following situations
1.             Retruding and Realining the teeth
Proclined Anterior Teeth can present both esthetic and functional problems that may be compounded by palatal soft tissue trauma from mandibular anteriors due to increase vertical overlap.
Strategically positioning posterior implant can be used as an anchorage to effect movements of the teeth.
2.             Closing Edentulous space so prosthesis is not required
Retromolar pad implants fixation is particularly advantageous when abutment teeth use for Removable or Fixed Denture prosthesis have large pulp unsuitable for abutment preparation.
They actually help in closing of the edentulous space by using Retromolar pad implants as an anchorage units.
3.             Correcting midline and Ant tooth spacing
Implants are particularly helpful when multiple posterior teeth are missing and the desired movement requires teeth to be moved in only one direction around the arch circumference.
4.             Reestablishing proper Anteroposterior and Mediolateral position for malposed molar abutment
Implants facilitate acchieving positional goals when there are multiple missing posterior teeth and particularly when the malaligned molar abutment is located at the end of an edentulous span.
5.             Intruding and/or Extruding Teeth
It can be especially difficult to intrude one molar while extruding another particularly if posterior teeth are missing.
Implant anchorage can definitely facilitate such movements.
6.             Correcting a Reverse Occlusal Relationship
Correcting an anterior reverse occlusal relationship (cross bite) in class III patients can be challenging.
Retracting entire mandibular arch with ramus implants is possible. It is also possible to retract the mandibular arch with ramus implants simultaneously protracting the maxillary arch by tuberosity implants.
JPD Vol 87 No 3 March 2002
1.             Impression copings on the implants are seated and secured them with guide pins.
2.             Opening is prepared on the buccal side of the tray near the implants Holes are prepared in the tray to allow head of the guide pins protruded without contracting the tray.
3.             Light bodied Impression Material is used to record the area around the remaining teeth.
4.             The tray is replaced in the mouth and ensures that guidepins are visible through the holes on the top of the tray.
5.             Injection type impression material (Kerr) is placved through the side opeing until the materials flow from the holes at top of the tray.
6.             After the impression get set impression containing the copings are removed.
JPD Nov 2001 Vol 86 No 5 Russell, T. Williamson Fonda. G. Robinson
In implant prosthodontics abutment screws and prosthetic retaining screws both have the potential for 4.
Screw loosening and Retightening may lead to subsequent # of abutment screws or prosthetic retaining screws.
If an abutment screw 4 above the head of the implant, haemostat may be useful to grasp the broken screw but if the screw # below the head of the implant then other method is applicable.
After the prosthesis or abutment is removed the screw hole is vigourously flushed with an air/water spray from a 3-way syringe.
An airstream is used to dry the screw hole.
A sharp 1/4th round bur in a high speed handpiece is activated, and lightly touched to the exposed site of # screw.
The objective is to have spinning bur blades contract the metal surface of the screw so the screw will spin out of the screw hole.
JPD APRIL 2002 Vol 87 No 4
Patients with intraoral defects due to partial maxillectomy for neoplasm form a highly hetrogenous group need the most appropriate protocol for rehabilatation.
The presence of absence of natural teeth together with the size of the resection and the extent of soft tissue loss have major implication for prosthesis design.
When natural teeth are available as abutment, a metal frame work is indicated typically made up of (Co-Cr).
But comercially pure titanium has been in use for more than a decade approx. weighs 40% lighter than (Co-Cr) frame work.
Proposed approaches for reducing the weight of these components have included the use of alternative materials.
Because the tissue surrounding the defect change rapidly after surgery as well as during or after radiotherapy, repeated adjustment is necessary.
The use of visible light polymerized Resin (VLP) not only reduces the weight but also improves oral hygine since these resins demonstrate a much lower porosities than conventional auto polymerized.
Advantages :        1.             decrease weight
2.             increase facilities in fabricatin
3.             increase facilities in adjustment.
An ideal material for Maxillofacial Restoration is ideally yet to be achieved despite the research expended in the post few years.
The formulative approach with chemical Acrylic analog had a brief period of product development for maxillofacial prosthesis.
Series of Co-polymers for methylmethacrylate have been introduced. Another is Ter polymer for the use as a synthetic acrylic latex to form a skin over elastomer scaffolding.
Polydimethylsiloxane and various proprietary silicones are premost in clinical usage, particularly where flexible tissue anatomic reconstructing is needed.
There are two basic types
(A) RTV - Room Temperature Vulcanizing (B) HTV - Heat Vulcunizing.
Some new structural polymers
1. Silphenylene Elastomers
2. Chlorinated Polyethylene.
Despite some evidence of casting defects the flexibility and the long term retentive resiliency of the clasps suggest that titanium and titanium alloys are suitable for Removable Partial dentures specially in the cases of deep undercuts.
Titanium has modulus of elasticity that is lower than that of Cobalt Chromium (Co-Cr) which increase its resilience.
This property allow them to place in deeper undercut areas.
Ti-6AL-4V clasps for a 0.75mm undercut showed the least amount of work hardening and permanent deformation, as small change in retention these clasps was consistent through out the years of clinical use.
SEM examination of cross sections of Ti-6AL-4V clasp revealed that cracking was confined to the surface layer and thus not like to cause any permanent deformation.
Surveyors are necessary to determine the path of insertion of RPD.
Basically surveyor consist of a mobile platform, on which cast is placed and titled in different directions respect vertical marking red.
Because of this position the marker is always parallel to its previous position as it move from one part of the cast to other.
Using same principle cast can be surveyed by parallel light beams instead of the vertical rod.
The cast is placed on a movable table and surveyed in a dark room using parallel light beams.
The survey line is the border of the light and dark zone.
The geometric location of a conventional lead marker survey line and the one created by light beams are in the same location.
After securing most favourable path of insertion for design of RPD the table of the surveyor is fixed in position and survey lines are marked with lead marker.
Change of survey lines and undercuts can be easily inspected for different position of the cast.
Slight undercut that cannot be measured by lead marker can be observed by optical surveying.
 l.             Flavour Added - Spearmint / Mango / Mint
2.             Rapid Set - Hydrogum Normal Set - Neocolloid
3.             Dust free - Aliginoplast
4.             Chromatic Alginate - TRIALGIN / KROMALGIN
5.             Paste form - (Catalyst + Base)
6.             Alginate Containing Microbials
1) Chlorhexidine
2) Quantanary Aluminium (Components)
Faster dimension for perfect mixing. System for automatic mixing and dispensing.
Advantages :        a) Top quality mix in less time b) More flexible mix
c) Homogenous void free mix
d) Direct filling of syringes and Trays
When changing impression materials cartridges have to be changed and change penta mixing tip.
ImpregnumTM  PentaTM  Soft Heavy Body/Light Body Impression Material
With Impression materials, the better the detail, the more accurate the final restoration.
Introducing ImpregnumTM and PentaTM Soft Heavy Body/Light Body Impression material, a precision polyether impression material that is accurate and hydrophillic, resulting in cut standing details even in moist environment, right from start of mixing.
The Soft Technology makes the material less rigid for easier removal from the mouth while improving the taste for better patient's satisfaction.
Intrinsic presetting hydrophilicity helps capture and reproduce outstanding details.
A carbon-free phosphate bonded investment for precision castings of precious semiprecous and Pd base alloys for use in both quick heating and slow heating procedure.
Advantages :        *a) With special attention to complicated implant casting
*b) Carbon free creamy consistency
c) High fluidity and wettebility
*d) Very smooth surface
*e) Controllable expansion
(B)          GC FUJIVEST II
A carbon free phosphate bonded investment for precision crowns and bridge castings of all dental alloys for use in both quick and slow heating process.
Advantages :        a) Carbon free
b) High fluidity + Wettebility
*c) Controlled setting + Thermal Expansion
*d) Smooth surface
e) Detailed Reproduction
f) Ringless Technique possible in both slow and quick heating process.
(C)          GC Stellavest
Same as GC FUJIVEST 11
Polyvinyl siloxane silicone impression material with properties specially adjusted to the requirement of Bite Registration.
1.             Fast reliable mixing and application directly from catridges.
2.             Thixotropic properties with ideal balance between stability and fluidity. 3.            Extremely accurate reproduction of details.
Polyether impression material for Bite registration for automatic mixing and dispensing in PENTAMIX SYSTEM.
1.             Automatic mixing and dispensing with PENTAMIX unit.
Absolutely homogenous and void free mixing at the touch of a bulton.
Extremely foot setting Addition-cured silicone with high ultimate hardness.
l.              Extremely short ST of 60 secs.
2.             Automatic mixing in new GARNAT 2 SYSTEM.
Specially designed for flasking techniques in denture fabrication
Advantages :        *a) Minimal S. Expansion
*b) Comfortable WT
*c) High compressive strength
*d) Yet diminished strength after setting for easy devesting
e) Excellent Accuracy
Stone Glaze liguid specifically designed for the surface t/t/ of GC Fujirock EP plaster/white
Advantages :       
a) Better visibility of details
b) First class presentation of prosthesis
c) Bio compatible.
Agent for dissolving dental stone and plaster residues by immersion
Advantages :        High disolving capacity
Suitable for stone + Gypsum Bonded Investment
Due to complination of Resin + GIC this material provide wide varity of application possibilities.
Indicated for luiting all kinds of metal and Acrylic/Resin crowns, inlays, onlays and bridges as well as luiting of Porcelain ceramic inlays.
Advantages :        Easy mixing and handling like conventional cement.
Similar machanical properties to Resin cement.
*Elimination of complex and moisture sensitive bonding procedure.
*Good adhesion to metal, resin and silanated porcelain.
*No post operative sensitivity.
*Optimal Marginal Seal.
Luiting of long span Bridges, Combination work and luiting of several restoration.
One step extended Working Time.
Advantages :        Same as GC FUJI PLUS only l min extended Working
Time help in easy removal of excess material.
Light/Self curing luiting composite systems.
l.              Inlays, Onlays and laminate veneers
2.             Adhesive bridgework.
Cures readily and thoroughly due to light and redox curing.
Easily and quickly polished.                                             
iscosity is perfect for placing multiple surface inlays.
Dual enzymatic Detergent Concentrate.
Co enzyme is highly concentrated dual enzymatic detergent.
The ionic surfactant in Coezyme help the powerful solution to access and clean hard-to-reach areas.
The synergistic enzymes dissolve and lift
proteins and the low sudsing neutral pH
detergent component remove the dissolve particulates.
Steradent has launched Steradent Denture Comfort Fixative Cream.
As well as ensuring secure and comfortable hold of the Dentures, the cream includes camonite, claimed to help prevent gum inflamation.
The current range of steradent products include.
Steradent Tripple action original and Fresh Cleaning Tablets Steradent Extra length.
GC Fit Checker
Easy flowing white condensation silicone material for location of pressure points of dentures and for checking accuracy of Crown and Bridges.
Advantages :        1. Minimal film thickness
2. Easy to remove from metal and resin surfaces
3. Clearly visible colur contrast to denture resins and metals.
GC Fit Checker II
White Polyvinyl silicone Addition Silicone Material especially for checking pressure points and accuracy of fit of Crown + Bridges.
Advantages :       
Easy application with Thixotropic Consistency
Exact detail Reproduction
3.             Optimised colour and Transparency.
This is an Adhesive for Bonding Dental Acrylic to Metal Simple bonding Technique producing a durable bond between Composite Veneering materials and metal structures without a marginal gap.
Allow safe Adhesive bonding of resin cements to metal restorations of all dental Alloys.
Advantages :        *1. Easy fast brush Technique
*2. Reliable Adhesion
*3. No leakage
*4. Resistant to Humidity
5.  Can be used with all dental Alloys and Acrylic.
Metalor unveiled their new digital shade system developed in collaboration with Dent Park Ltd and Olympus Optical Company at recent FDI.
Metalor have secured the worldwide marketing rights to use software and Hardware developed by Dent Park, bringing together an advanced olympus digital camera to address the complicated subjects of shade selection and communication in dentistry.
The product is new generation of Hardware and Software which combine to accurately measure the shade, shape and contour of natural tooth, transmitting the data electronically from dental office to dental laboratory without compromising the shade information.
GC Acron MC is an microwave curing Denture Resins in which polymerisation takes place in a microwave at much shorter time.
This is supplied same as powder and liquid form. Advantages
* 1.         3 minutes polymerization time in a standard household microwave oven.
*2.          Uniform polymerisation even in thick sections.
*3.          Excellent Dimensional Stability.
*4.          Excellent fit to the tissue surfaces.
* 5.         High Surface Hardness.
*6.          High Strength.
*7.          Colour stability. GC PATTERN RESIN LS
GC Pattern Resin LS is a lose shrinkage modeling Resin use for modelling of metal casting plates, telescopic and Konus crown, adhesive bridges palatal and lingual bars, connectors etc.
Specially developed on brud-on-Technique. Advantages
1. High precision
2. Minimum shrinkage during polymerisation 3. Dimension stable
4. High Hardness and strength 5. Short ST
6. Modelling directly on the working model.
This is a new generation Composite Restorative Material having an unique property of Fluoride releasing action.
Coming in shades of A2 and A3.5 Advantages
l.              Unifil is a light curved, radiopaque fluoride releasing hybrid Composite for all anterior and posterior restoration.
2.             It is a non sticky, easy to place, sculpt and pack composite and is BISGMA free.
3.             Consist of silans coated fluoaluminosilicote glass fillers.
4.             Benefits from significant fluoride and stronium in release to strengthen, protect and remineralize tooth structure.
I DENTAL DIAMOND BURS MADE WITH NEW TECHNOLOGY JPD JULY 1999 Vol 82 No 1 CFM BORGES DR Med Dent Conventional Diamond Burs shows several limitations such as heterogenicity of grain shape, the difficulty of automation during fabrication, the decrease of cutting effectiveness due to repeated sterilization.
An additional short comming may be represented by the potential release of Niz+ ions from the metallic binder into body fluids.
A new diamond rotative instrument made of continuous diamond rotative instrument mode of a continuous diamond film obtained by Chemical Vapour Deposition (CVD).
Cutting Tests were followed by SEM examination and Electron microprobe analysis (EMA) to trace mettalic residue both on the surface of the bur and the substrate.
EMA demonstrate that the metals of Ni, Cr, Si and Fe were present in the metallic binder matrix of conventional bur and could be smeared on the surface of the substrate.
SEM showed that significant loss of diamond particles occured during cutting.
On other hand no discreate particles sheared off the CVD bur.
The new CVD burs not only proves to be more efficient in cutting, ability and longevity but also decrease risk of metal contamination.