Fixed Prostheses

5°A ODO

Karol Riccardo Pulvirenti

Fixed Prostheses Presentation

With metal,alloys,dental implants and Titanium

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Index

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Study and master

Fixed Prostheses

Classification

Neck preparation

Dental alloys

Video fixed prostheses

Dental Implants

Dental Metals

Titanium

Map

Team

Thanks

01

What are fixed prostheses?

Fixed Prostheses are oral devices permanently cemented in the mouth to restore partially edentulous areas.They are resistant and non-toxic prostheses,they must adapt well and must achieve perfect articulation with the antagonist teeth.They can consist either of single units built to preserve natural tooth portion destroyed by caries or accidents or support pontics to substitute missing elements.Also all these devices usually present a metal framework,a cap or pontic,executed with the lost-wax method.

Classification of fixed prosthesis

Also this fixed prostheses can be classified into:Reconstruction,substitution or fixing denture

Reconstruction

Substitution

Fixing Denture

Reconstruction denture saves a natural tooth from extraction,when its coronal part has been lost:In fact it is commonly know as a "Crown"

A substitution prosthesis replaces missing anatomical crown and is called a "bridge" when the retaining element, rest on abutment teeth wich in turn restore edentulous saddle

Instead a fixing denture is required when the natural teeth show a tendency to migrate,and must distribute the masticatory load uniformly on the whole dental arch

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Study and Master model

For the creation of fixed prosthesis,two models will be used.A study models which will faithfully reproduce both the abutment and the residual teeth in order to allow the correct evaluation of seals and of safe borders,and a master model in order to verify whether the abutment preparation fits the prosthesis to be built.

Developed by...

Developed by...

Developed with first impression

Developed with position impression

What is it for?

What is for?

To faithfully reproduce both the abutment and the residual teeth

in order to verify whether the abutment preparation fits the prosthesis to be built

Study model

Master model

In order to...

In order to...

Allow for the correct evaluation of seals and of safe borders

A good success

The neck preparation

Obviously in fixed prostheses the preparation of the neck is also very important.The neck preparation can be:Shoulder,shoulderless,slice-cut,bevel or chamfer,depending on the prosthetic materials.In fact the crown must fit perfectly on the neck,to avoid that the saliva could infiltrate under the crown,reacting chemically with the fixing cement and altering its structure.Moreover a perfect adherence is necessary to hinder food infiltration,which would expose teeth to the attack of secondary caries.

Video on the fixed prostheses

Learn how to make a fixed dental prosthesis

Creation of a fixed prosthesis in short.

Fixed prostheses

Dental Implants

Dental implant surgery is a procedure that replaces tooth roots with metal,screw-like posts and replaces damaged or missing teeth with artificial teeth that look and function like the real ones.In fact dental implant surgery offers a good alternative to dentures or bridgework.How dental implant surgery is carried out depends on the type of implant and the condition of the jawbone,but all dental implant surgery occurs in stage and involves in different procedures.However the major benefit of implant is stout support for the new artificial teeth - a process that requires the bone to heal thoroughly around the implant,so a process that can take several months.Also dental implant are surgically placed in the jawbone,where they take over the function of the roots of missing teeth.Because the "Titanium" in the implants,integrates with the bone,so the implants will not slip or cause bone damaged,how they way fixed bridgework or dentures can.And the materials do not decay like the natural teeth supporting normal bridgework.Also the dental implant may be right for someone if they patient have one or more missing elements,or have a jawbone that has fully developed or have healthy oral tissues.

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Dental metals

Under the generic term "metal" we understand the chemical elements of one of the two fundamental categories into which they are usually divided,the Other one bing that of Nonmetals.Metals are solid substance characterized by a Crystalline structure whose atoms are held toghether in a compact lattice disposition,by a chemical bond defined "Metallic bond".However they are all characterized by a good termal and electric conductivity,and most of them present high specific gravity,can reflect light,are malleable and ductile.Also in nature they can be found in the form of minerals,generally as oxides and sulphides,so that to obtain them in the pure state extractive metallurgy is needed,in fact only limited number of them,like copper,gold,silver,platinum and bismuth can be found in their elemental state,so in this case they are defined "native metals".Moroeover metals are variously grouped in fact according to their specific gravity they can be either light or heavy.The most widely used metals in dentistry are:Gold,copper silver,platinum,palladium,cobalt,chronium,nickel,molybodenum,iron and cadnium and in the last few years "titanium".Obviously with the exception of titanium,all other metals used in dentistry are mixed with other metals,to improve the proprieties of the single metal.

Dental alloys

Alloys are mixture of two or more elements,one of which,at least must be a metal.They are used in the construction of crown,bridges,and the metal framework of removable partial dentures.Furthmore the alloys must be tastellen and odourless,insert in the oral fluid and not allergenic.Prosthodontics makes us of two fundamental alloys:Gold alloy and Stellite alloy.Gold alloy are mainly compoused of gold alloyed with copper,silver,platinum,palladium and zinc and though presenting high resistance to corrosion,gold is too soft a material and deforms under stress,in fact to improves hardness and elasticity,the other metals are added in different proportions so that "four" different alloys are identified according to their hardness from soft to extra-hard.Copper is usually added to lower the melting point,silver makes the alloys harder,while palladium and platinum make it "silvery white".But since gold alloys present the disadvantage of cost and of a high specific gravity,a number of alloys with minimum or no gold content have been introduced in a dental techniques.These alloys defined "Stellite alloys" are basically constituted of chronium-cobalt,nickel and cadnium.Since nickel can be extremely allergenic it is often completely substitute by molybdenum.And chronium is employed in a concentration ranging from 12% to 30%,because it improves the resistance to corosion.This property called "passivity" create a surface layer of oxides which prevent oxygen from reaching deep layer.Thanks to their passivity,their hardness and their low specific gravity,these alloys greatley contribute to restorative dentistry.Then there is another alloy called stainless steel,on alloy mainly made up of iron and carbon and units low cost to high elasticity.This alloy is provided in wires,sheets,foils,plates or performed units,and for this is classified as "wrought metal".

Type of dental alloys

All various sizes of dental alloys

Denatal alloy plates

Dental alloy in sheets

Dental wire alloys

For the creation of the metal framework in a removable partial denture

For making crowns

for the creation of orthodontic appliances

Another metal the

Titanium

Titanium has been succesfully employed in dentistry in the last few years,above all for dental implants,root posts,wires and orthodontic retainers,in maxillary and mandibular prostheses in general.Actually,this metal present a very high biocompatibility and resistance to corrosion,since it behaves as a passivating agent;It has a low specific weight,no taste,scarce thermal conductivity and galvanic neutrality.However melting and casting procedures are the object of intensive research,in order to overcome the technical problems represented by a very high melting point and by faults due to incomplete casting,gaseous porosity and surface roughness,and to achieve a satisfactory application in the field of fixed and removable prostheses.Also in orthodontics,nitinol wires have already been used for their excellent mechanical properties and the elastic memory presented by this alloy.Another obstacle is represented by the high cost of the refined equipment required for its manipulation:Titanium can be handled only by means of titanium tools,every components must be provided in seals glasses containers.Finally an alternative metal,with the same chemical,biological and mechanical properties as titanium is zirconium,which however,also present the same processing difficulties.

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Created by Karol Riccardo Pulvirenti

Orthodontic appliance

Physical properties of commercially pure titanium

Crown and Veneer

Veneers and dental crown are dental techniques used in the field of fixed prostheses.

A Veneer is a very thin layer placed on the face of the tooth made of resin or porcelain,Instead the Crown is a dental restoration that covers the portion of a tooth or dental implant,that lies at and above the gum line.

• Crown are:Partial or Full
• Partial are divided into:Inlays,Onlays and Pinledge
• Full are divided into:Functional and Aesthetic

Inlays

Onlays

Pinledge

When the reconstruction is in the forntal teeth

When there is a restoration for the occlusal surface

when there is intracoronal restoration

Creation of a dental implant in short

• Learn how to make a dental implant

Fixed partial denture

A fixed partial denture,usually called "fixed bridge" is a restoration replacing one or more missing teeth,which cannot be directly removed by the patient.

It is made of metal and aesthetic material,and is fixed on natural teeth called abutment.From a biomechanical point of view it is,therefore classified as a Physiological Prostheses.The fixed bridges are composed of:Retainers,artificial crown cemented on the abutment,pontics the suspend part of the bridge,and connectors which link retainers and pontics.Furthemore the bridge can be divided into:Fixed,semifixed or removable,swing-on or cantilever bridge and compound bridge.

• Bridge are Physiological appliance
• Composed of Retainers,artificial crown,pontics and connectors
• Divided into Fixed,Semifixed,Swing-on and Compound bridge