Prosthetic Dental Laboratory

Partially Edentulous Conditions

2010-03-26T18:32:00.000-07:00

In cases where in the mouth teeth are missing, edentulous situations are grouped in 4 categories that were defined by Dr. Edward Kennedy in his classification of partially edentulous arches.

Class I (bilateral free ended partially edentulous)
Class II (unilateral free ended partially edentulous)
Class III (unilateral bounded partially edentulous)
Class IV (bilateral bounded anterior partially edentulous)

Kennedy Class I
This type is for people who are missing some or all of their teeth on both sides in a single arch and there are no teeth posterior to the edentulous area. Class I RPD´s clasp onto the teeth are more towrds the front of the mouth, while replacing the missing more back of the mouth teeth on both sides with false denture teeth.

Class II
RPD´s are fabricated for people who are missing some or all their posterior teeth on one side in a single arch, and there are no teeth behind the edentulous area. Thus, Class II RPD´s clasp onto teeth that are more towards the mouth, as well as on teeth that are more towards the back of the mouth of the side on which teeth are not missing, while replacing the missing more back of the mouth teeth on one side with false denture teeth.

Class III
RPD´s are fabricated for people who are missing some teeth such that the edentulous area has teeth remaining both posterior and anterior to it. Unlike Class I and Class II RPD´s which are both tooth and tissue borne, Class III RPD´s are strictly tooth borne, which means they only clasp onto teeth and do not need to rest on the tissue for added support. This makes Class III RPD´s exceedingly more secure as per the three rules of removable prostheses that will be mention later namely: support, stability and retention.

However is the edentulous area described in the previous paragraph crosses the anterior midline, the RPD is classified as a Class IV RPD. By definition, a Kennedy Class IV RPD design will posses only one edentulous area.

Classes I, II and III RPD´s that have multiple edentulous areas in which replacement teeth are being placed are further classified with modifications states that were defined by Oliver C. Applegate. Kennedy classification is governed by the most posterior edentulous are that is being restored. Thus, if for example, a maxilary arch is missing teeth #1,3, 7-10 and 16, the RPD would be Kennedy Class III model 1. It would not be Class I, because missing third molars are generally not restored in an RPD (although if they were, the classification would indeed be Class I), and it would not be Class IV, because modification spaces are not allowed for Kennedy Class IV.

The Occlusal Splints (night-guard)

2010-03-25T13:24:00.000-07:00

An occlusal splint or sometimes called night guard is mostly recommended to patients that are heavy grinders, or bruxes*.

Since most of the damage caused by teeth grinding is when we sleep, a splint ussually stops or prevent further damage.

The guard is custom made the upper or lower arch of the mouth. When the night guard is in place, the patient can not grind their teeth together and cause more damage.

The guard is worn during night maybe 4-5 nights a week and has been proved that they reduce the chance of fracture and tooth surface loss in the long run.

*Bruxism is the nocturnal unconscious grinding or gnashing of the teeth. It has been linked to stressful life events and occlusal or bite irregularities. Research shows that the maximun clench force capability during bruxism is up to 4 times the maximun conscious force in some subjects.

What is a dental attachment?

2010-03-22T11:06:00.000-07:00

An attachment is a connector that is formed of 2 or more parts. One part is connected to a root, tooth, or implant and the other part to a prosthesis. There are certain exceptions as some attachments have only one manufactured part and the other part must be made by the dentist or the dental technician.

Attachments can be divided into two categories: Precision and Semi-Precision. We will examine both of them prior to attachment consideration.

Precision Attachments

Precision attachments are just that - "precision". Their components are machined in special metal alloys under precise tolerances. These tolerances are within 0.01 mm. Since the specific hardness of the alloys is controlled, precision attachments offer the advantage of less wear on the abutments, and standard parts which allows the components to be interchangeable, and usually easier to repair when necessary.
Semi-Precision Attachments

A semi-precision attachment is fabricated by the direct casting of plastic, wax, or refractory patterns. Most semi-precision attachment patterns are injection molded to reduce the overall cost. They are considered "semi-precision" since in their fabrication they are subject to inconsistent water/powder rations, burn out temperatures, and other variables. The resulting components therefore, vary to a small degree.

Their main advantages are: economy, easy fabrication and ability to be cast in a wide choice of alloys without the problem of co efficiency differences between the cast alloy and the machine alloy.

http://www.attachments.com/

What Are Dental Implants?

2010-02-21T18:35:00.001-08:00

To make an exact replica of the natural function and look of the missing tooth it's a hard mission to accomplish. Throughout history, people have tried dentures or ceramic restorations as replacements, but in the end the results are not satisfactory for many. That is why dental implants came into existence, offering a more natural look and the same function as the natural tooth root. They have also been used to anchor dentures and ceramic restorations with greater success and patient satisfaction.

A dental implant is a small titanium post that works as the root structure for a natural tooth. They are placed either into your upper or lower jaw bone. When implants are integrated to the bone, they can now hold a crown, bridge or over-denture as in the case of natural roots. It is worthy of mentioning that they are very durable and can last a lifetime, with no need for special maintenance but only regular brushing, flossing and dental check ups.

3M Lava Zirconia Crowns

2010-02-13T08:00:00.000-08:00

This revolutionary system combines CAD/CAM technology with the best translucent zirconia framework. This enables one to make a strong restoration for long span bridges with an incredible fit and bio-compatibility and the aesthetics patients expect.

In modern society beautiful teeth are important for self-esteem and a sense of well-being. They want teeth that offer value for money, a natural appearance and more durability.

Lava crowns and bridges are made from zirconium oxide (zirconia) and are suitable for anterior and posterior applications for up to 4 units in lenght without any compromise of the lifespan of the restoration. Zirconium oxide combines natural appearance with the exceptional strength. The fracture strenght of a zirconia crown is many times higher than that of the conventional ceramic materials.

Some of the benefits of 3M Lava Zirconia are these:

Higlights:

Superior strenght of zirconia with high fracture resistance
Excellent aesthetics and translucency
Oustanding marginal fit

Material Composition:

Zirconium Dioxide substructure
Ceramic layering material

Applications:

Anterior: crown, 3-8 unit bridge
Posterior: crown, 3-8 unit bridge, inlay onlay, inlay bridge

Flexural Strenght:

>1000 MPa

Cementation:

Conventional cement
Resin cement
Resin-reinforced glass ionomer

Dental Crowns

2010-01-16T14:58:00.000-08:00

Dental Crowns are designed for teeth that are damaged and need to be replaced for a ceramic crown. The crowns use the tooth previously prepared to receive a covering or core that can be made of metal, metal-ceramic and all ceramic.

Metal Crowns

Although they are made mostly of precious metals like gold, silver or other alloys, they have a small inconvenient... the colors of the metals and the shine of them make they very visible and obvious to other people. What is worth to mention about them is that their lifetime is long and for patients with a strong jaw they are the best.

Metal Ceramic Crowns

This crowns that fuse porcelain to metal are the second strongest crowns available and they last longer too. We have to say that because the metal being colored by a paste opaque material the reflective quality of them is poor, but when the porcelain is applied by a master in ceramic they look really good.

All Ceramic Crowns

They are made of porcelain, resins or other dental materials. What is outstanding about them is that they look 100% natural on the mouth if you compare them with the other 2 types. Dentists normally suggest this type of crown for front teeth. Although they look better on you, they are fragile and are destined to fail if the pillars where they will be placed are not properly prepared.

Oral Hygiene - Basic Steps

2009-06-14T14:35:00.000-07:00

Brushing and Flossing
There is no better way to keep a clean and nice smile by brushing and flossing everyday. But is a fact the problem starts when after you eat, small particles of food reside on your teeth and with time they become the undesirable plaque. The big problem is that all the bacteria on the plaque produces gum disease, tooth decay and in many cases loss of teeth. For those reasons here the basic steps to keep a nice and healthy smile.

Brushing

There are hundreds of toothbrushes on the market. We recommend the use of a toothbrush with soft bristels and a small portion of fluoride toothpaste at least twice a day, particularly after breakfast and before bedtime. When you brush your teeth, do it in circular movements so you can get all the food particles that hide on the gum line. It is a fact that following this method will take several minutes to brush your teeth but the results are good for you. Even include as part of your mouth cleaning your tongue and roof of your mouth. Be careful to not swallow any portion of the toothpaste and use enough water to rinse your mouth. Also make sure to visit your dentist at least every 6 months.

Flossing

No matter how much money you pay for your toothbrush, there will be areas that you would not be able to clean thouroghly, so a good help is dental floss. It will be a task you may not like, but is very important to do it everyday. Pull a bit of the floss and slide it up and down along the front of each tooth. You will notice a difference when the teeth are clean, but again, be careful not to floss too hard so you don't get injures in the gum. I would say that the best time to floss is before you go to bed so you have a clean mouth while you are sleeping.

Finally it is very recommendable to limit the times you eat snacks each day, trying your best to eat healthy food and getting plenty of calcium.

Tooth Whitening

2009-05-19T16:22:00.000-07:00

Tooth whitening is considered the best procedure to reduce the yellowish coloration of teeth.

By means of a whitening solution (carbamide peroxide) and the direct contact with tooth, te solution removes the stains from teeth.

Some of the common reasons why teeth change in color are the use of black tea, red wine, coffee and the worst of them, tobacco. In other isolated cases the use of tetracycline on patients cause some darkening of teeth.

But mostly what moves people to ask the dentist for a whitening, is the lack of confidence in themselves when smiling, associating white teeth with beauty, good health or even youth.

It is important to remember that results may vary according to the patient's habits and age.

-Whitening Techniques-

Whitening Toothpastes

We can say that all the toothpastes on the market are good removing the stains of the teeth. However there are some special toothpastes that remove more stains than others (due to a high concentration of the peroxide), but none of them would have the results that you can get visiting a dentist.

Whitening Strips

The strips are very easy to get in pharmacies and essentially they are strips covered with peroxide in a low concentration, that after 30 minutes in direct contact with teeth, two times a day, for about 14 days, bring good results for the paerson, but remember, it will never be compared with the results obtained at a dentist chair.

Personal Whitening Trays

The laboratory makes some trays identical to the patient's teeth. At home, he fills the trays with peroxide gel (It can be 10, 16 or 30% of intensity) the areas that will be whitened, and for a few hours (preferably at night) the patient wears the tray, allowing the gel to remove practically all the stains on the tooth. The cost is reasonable, but touch ups are needed after a period of 6 to 12 months.

At the Dentist Office

This is considered the best whitening method that can be performed at the dentist office in only one session. The dentist cover the patient's gums with a special gel that protects the gum from irritation. Then it is applied to the teeth carbamida peroxide and is activated by applying heat or a light source. The cost may not be as cheap as the toothpaste or strips but the results and the convenient time of the entire process, motivates more people to ask the dentist for a teeth whitening.

Dental Waxes

2009-05-07T10:27:00.000-07:00

Dental waxes are considered to be the most important element in making dental prosthesis. They are available in multiple colors according to the different purposes they're designed for.

Base Plate Wax

This type of wax is mostly used to make a space over the cast before custom trays can be made. The other use is to block out undercuts on casts. It's pink and normally comes in sheets.

Bite Wax

This particular U-formed wax is normally used by dentists to register the occlusal relationship between the upper and lower arches of the patient's mouth, and later to make an articulation of both, upper and lower casts. It is very important to have a good record of this because it's what the dentist and laboratory will use to make a good prosthesis that will be identical to the real arch's articulation.

Sticky Wax

It's a parafin wax and resin, and it's usually orange, although it's also sometimes violet, red and blue. What makes this wax sticky and hard is the resin. Many laboratories take advantage its hardness to put together some broken pieces on a cast or denture so it can be accurately repaired.

White Wax

Because this wax is soft, it's the preferred wax to use when designing teeth. Some technicians even use it to make a preliminary model of the teeth on the cast, which later helps in checking the fine details between it and the porcelain crown(s).

Wire Wax

This type of wax allows the designer to have a wide selection of various wire shapes & gauges on hand. They are available in multiple forms, mainly rectangular, round, uncut bezel and triangular. But these can be divided into sub-categories and come in different diameters.

Dipping Wax

This is used to make coping for inlay and onlay pattern by covering dies with a base coat of wax. The die is dipped once into liquified wax to produce a perfectly adapted, detailed, reproducible and accurate coping of wax that has even-walled thickness with sealed margings. The crush resistant coping comes off the die clean while supporting flexible and sharp margins.

Inlay Wax Chunks

This wax is form-stable and contraction resistant (low shrinkage) from wax-up to burnout. It will not to pull, flare, chip, crack, drag or expand at the margins even when being cast extremely thin sections. It will resist deformation, due to handling and can be easily carved. Will not become sticky or flaky or gum up instruments and will burn-out cleanly with no residue.

Wax Patterns

When we refer to wax patterns we have to differentiate between the wax patterns for crowns and bridges, that include the anterior, posterior, upper & lower blocks, and the patterns use dto make removable metal partials. Both of them come in different forms, sizes, and even colors to make it easy for the technician the modeling either the bridges or the metal frames.

Dentures

2009-05-01T17:18:00.000-07:00

We can start by saying that there are 2 types of dentures, full and partial, and they can also be divided in sub-categories: plastic (acrylic), metal and combined (metal-acrylic). The decision of which one fits better your needs would be made by your dentist according to his judgment and criteria.

Full Dentures

A full denture is basically an acrylic base that fits perfectly your gum y form and color. The base of the upper denture covers your palate, while the lower has a U form that allows your tongue to be in place correctly.

There are some questions that you as the patient may ask, like for example how long before I get used to my new denture? How long my denture last? and some other concerning doubts about the use of a denture, so let's start with the first question.

Dentures are made of acrylic that is welcome in your mouth, but sometimes the form of your gums may change a little bit after the remaining teeth were removed. This may take a few weeks or months before they finally adopt the form of the denture. On the other hand we have the situation were your mouth produces excessive saliva, your tongue feels a little tight with the remaining space left from the denture and your voice may sound different at first. All of this are normal simptoms of a new denture, but as with new shoes, you have to wear them for a bit of time so your feet gets used to them. They may strecht a little and suddenly you don't feel that your shoes are new. The same would happen with a new denture and with time your mouth and tongue get used to the new denture. But be carefull to inform your dentist if there is excessive pain caused by the denture.

Partial Dentures

They are made commonly of metals (chrome cobalt mainly) that are approved to be used orally, and after an impression taken from the dentist to make a mold of your mouth and the remaining teeth, technicians make at the laboratories the form of your mouth and the spaces were you need one or more pieces.

With that mold and the metal frame designed to be attached to your mouth by some clasps, now there is an structure that will have premade acrylic teeth that would help to cover the spaces, but mostly to enable a better and comfortable chewing.

Removable Partial Dentures (Cast Metal)

2009-04-30T06:41:00.000-07:00

This are one of the first methods used to replace the missing teeth in certain areas of the mouth. Some people say that originally they were made of silver and gold.

Due to the versatility of the materials used to make the partials, it was possible for the dentist to mold the metal according to his needs, covering the areas that were missing some pieces and attaching the metal structure with some clasps to the remaining teeth.

It is worth to mention that the partial is not in contact with the gum on the areas where we are missing some teeth, because the gum have the characteristic of resorb. For that reason and with the study of the different metals available for oral use, it was discovered a material that allowed the frames to be thinner (less noticeable for the tongue) but at the same time strong and flexible. The metal alloy is called Chrome Cobalt.

There are different techniques to make this frames, other are flexible and finally what matters is what is best according to the needs of the patient. We will discuss some of them in the next posts.

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2009-03-03T17:00:00.001-08:00

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