CAD/CAM

[Anonymous]

According to a new report from Reportlinker.com, in 2010, the total Chinese and Indian markets for Dental Prosthetics and CAD/CAM were valued at nearly $666 million (Rs. 3500 crores approx.) , a 7.5% increase over the previous year. The overall market for dental prosthetics and CAD/CAM is estimated to grow at a high single-digit rate in the future. The market for CAD/CAM in particular, experienced double-digit growth in 2010. Another report by Technavio, specialists in emerging technologies market research, reveals that the Dental Prosthetics market in the Asia Pacific region is expected to grow at 13 percent. Premium dental prosthetics equipment manufacturers are driving the market for dental implants and bone-graft substitutes in emerging markets such as China and India. The report also highlights that the substantial growth of regional vendors and the growing adoption of laser dentistry is expected to boost market growth. Companies mentioned in this report include Dentsply International Inc., Nobel Biocare Holding AG, Sirona Dental Systems Inc. and 3M ESPE.

[Anonymous]

Abstract
CAD/CAM systems (computer-aided design / computer aided manufacturing) used for decades in restorative dentistry have expanded its application to implant dentistry.
This study aimed to look through CAD/CAM systems used in implant dentistry, especially emphasizing implant
abutments and surgical templates manufacturing. A search of articles published in English at Medline and Scopus
databases at present was conducted, introducing “dental CAD/CAM”, “implants abutments” and “surgical guide
CAD/CAM” as key words.
These systems consist of three components: 1) data capture using optical systems or laser scanning, 2) CAD for
the design of the restoration, and 3) CAM to produce the restoration through the information generated by computer.
CAD/CAM abutments present the advantages of being specific to each patient and providing a better fit than the
rest of abutments, in addition to being much more tough as they employ materials such as titanium, alumina and
zirconium.
In order to improve accuracy during implant placement we use stereolithography to manufacture CAD/CAM surgical templates. Using this method, minimally invasive surgery is performed without a flap, and the prosthesis is
delivered, achieving immediate functional loading to the implants.

Introduction
CAD/CAM (computer-aided design/computer aided
manufacturing) systems have evolved over the last two
decades and have been used by dental health professionals for over twenty years (1).
In 1971, Francois Duret introduced CAD/CAM in restorative dentistry (1) and, in 1983, the first dental CAD/
CAM restoration was manufactured (2).
One of the main lines of implementation was the intraoperative use for dental restoration using prefabricated
ceramic monoblocks (3).
The CAD / CAM systems have been used mostly for
the manufacturing of prosthetic fixed restorations, such
as inlays, onlays, veneers and crowns. During the last
decade technological developments in these systems
have provided alternative restorations using different E142
Med Oral Patol Oral Cir Bucal. 2009 Mar 1;14 (3):E141-5. CAD / CAM dental systems in implant
materials such as porcelain, composite resin and metallic blocks, which could not be prosecuted previously
because of technical limitations (4).
Nowadays there is a greater interest in the CAD/CAM
systems for implant-supported prosthesis, as they have
been used for the manufacture of implant abutments (5)
and diagnostic templates in implant dentistry (6).
The aim of this paper is to review the CAD/CAM systems used in implant dentistry, and describe its application in the construction of implant abutments and surgical templates.
Material and Methods
A search of articles published in English at Medline
and Scopus databases at present was conducted, introducing “dental CAD/CAM”, “implants abutments” and
“surgical guide CAD/CAM” as key words. 59 articles
were found using this search strategy. All articles that
described the construction of implant abutments and
surgical templates using CAD/CAM technology were
included, not excluding articles about clinical cases or
in vitro studies. 29 articles were used finally.

        

[Anonymous]

Results
CAD/CAM components
CAD/CAM systems are compound of three basic functional components (7):
1. Data capture or scanning to obtain the oral information. To conduct this process there are different trading
systems:
– Intraoral capture. This method uses 3D optical systems for capturing single components anatomy. Some
examples are: Interférométrie Moire, laser scan, colorcoding (such as CEREC (8) and Evolution 4D (Evolution 4D)) (9).
– Anatomical dental duplicate capture (plaster cast),
usually using a laser scan method. Comercial products
such as RapidForm® (RapidForm), Slim® (Slim), polyWorks® (polyWorks) and Geometric Studio® (Geometric Studio) are used for the 3D meshes post-process.
2. CAD for the geometric design of the restoration.
These CAD systems have some simple functions to
change the restauration geometry.
3. CAM to manufacture the restoration. CAM systems
use computer-assisted information to shape a physical
object, using subtract methods (that removes material
from a starting block to obtain the desired shape) or using additive methods, used in the rapid prototyping, increasingly used in CAD/CAM oral technology.
Prosthetic abutments
Ideally, the abutment head should resemble a prepared
tooth with good form, morphology and emergence profile.
Proper implant positioning and appropiate preparation of
hard and soft tissue are critical to creating optimal emergence profile, function, esthetics, and periodontal health.
The types available can be separated into three categories:
Stock (prefabricated). They are milled in different materials (titanium, zirconium) using CAD/CAM technology. These are available either straight or preangled.
UCLA (laboratory wax and cast). They are manufactured from a gold platform and a castable sleeve that
allows to individualize the shape and height.
Computer-milled solid abutment (10). A solid block of
titanium is milled using a computerized milling machine to the operator´s specifications.
CAD/CAM abutments in Implant Dentistry
Advantages of CAD/CAM abutments
Custom abutments created with CAD/CAM technology have the potential to provide the advantages of both
stock and laboratory processed custom abutments without the disadvantages(2). First, like laboratory-made
abutments, CAD/CAM abutments are specific for each
patient (11), however the results are much more consistent. The technician´s learning curve is less steep than
that for handmade components. The technician controls
the abutment design using CAD software that incorporates parameters to assist him or her. The virtually designed abutment is electronically transferred to a CAM
milling apparatus that creates the abutment from a block
of the selected abutment material. Most of the inherent
dimensional inaccuracies of waxing, investing and casting are eliminated. Unlike stock or cast custom abutments, the abutment surfaces of CAD/CAM abutments
are not subjected to the above-mentioned manipulation
processes after machining, so CAD/CAM abutments
have the potential to provide the most accurate fit of any
abutment type.
When compared with a stock and cast abutment, the
cost of a CAD/CAM implant abutment presently lies
somewhere between the two. This expense is likely to
decrease over time as CAD/CAM systems for abutment
fabrication become commonplace. Conversely, costs of
manpower and labor-intensive laboratory processes are
likely to escalate, thereby increasing the cost of prepared
stock abutments or handmade cast custom abutments.

        

[Anonymous]

Materials used
CAD/CAM technology has used metals such as titanium and titanium alloys, and ceramics such as aluminum
oxide or zirconium oxide for the fabrication of implant
abutments (12). The higher strength of these materials,
which can be shaped only with CAD/CAM systems, has
increased the longevity of these restorations and the demand between dentists recently. Some of these products
are: CEREC 3D® (Sirona Dental Systems) (CEREC
3D), Everest® (Everest) (13) and Lava® (LAVA) (14).
CAD/CAM Custom Implant Abutments
Most implant systems offer these kind of abutments (4).
The sequence begins introducing the patient informa-E143
Med Oral Patol Oral Cir Bucal. 2009 Mar 1;14 (3):E141-5. CAD / CAM dental systems in implant
tion in the software that employs CAD/CAM technology. The laboratory technician waxes the prosthesis
over the corresponding abutment and scans it. Then
this structure is adapted to the antagonist arch and to
the emergency profile. These data are transferred to the
CAM center and the designed abutment is then milled,
adding the ceramic later (4).
Nowadays, with the exception of the internal or external
hex, the abutment structure is designed following this
method. The current CAD softwares have databases
that allow to choose the abutment, or another option is
to scan and introduce it into the software to get the desired shape. Then the designed shape can be modified
according to instructions sent with the case. The digital information is transferred to a computer-controlled
milling machine and the abutment is milled from a solid
block of titanium alloy. The milled abutment is turned
to the cast to verify the fit and shape (10).
Commercially available CAD/CAM abutments systems
Cerec® (Sirona, Patterson Dental Co., Milwaukee, WI)
is an available system that allows the milling of ceramic
restorations at the dental office. The dentist can scan
the image from the patient mouth using an optical scanner, design the ceramic restorations and mill them at
the dental office. If diagnosis is thorough and accurate,
placing the implant and doing a definitive restoration in
1 appointment can be as predictable as the traditional
2 appointment technique (15). One of the most important disadvantages is that the dentist must purchase the
scanner machine, the milling units and softwares.
Ortorp et al. (16) show that the precision of fit between
cast and CNC-milled titanium implant frameworks for
the edentulous mandible was better than structures
made in a traditional process.
Atlantis® Abutments(Atlantis Components, Inc, Cambridge, MA), milled in titanium alloy, has been commercially available since the early the 1990s.
A single impresion or implant positioning index can be
made at the time of implant surgery, or it can be made in
a second stage, when a minor modification of the abutment will be necessary so that soft tissues will be healed.
A transfer coping is attached to the implants and an index
is fabricated orienting the transfer copings to the adjacent
teeth. This is sent to the laboratory together with full-arch
impressions. The laboratory incorporates the implant
analogs into the master cast using the transfer coping and
makes measurements directly on the cast. This determines
what degree of emergence profile is needed and the length
and shape of the abutments and the margins. The image
generated can be modified according to instructions sent
with the case. The file is transferred to a computer-controlled precision milling machine and the abutment is milled
from a solid block of titanium. The milled abutments are
returned to the treatment casts to verify proper shape, contour, and occlusal clearance (10).
Atlantis provides a second duplicate abutment to give
dentists the option of placing a provisional crown on
the first abutment and a definitive crown on the second.
Ensuing tissue recession during soft tissue healing may
necessitate hand modifications of the abutment margin
before crown fabrication (2).
Procera® (Nobel Biocare, Yorba Linda, CA), initially
developed for titanium and aluminum oxide copings for
convencional crowns, has recently added implant abutments to their line of CAD/CAM components (5).The
abutment made of commercially pure titanium elimininates concerns about the use of dissimilar metals and
about interfases between machined and cast components. As for natural abutments, the luting agent, the
height and convergence angle of the abutment influence
the retention of metal doping luted on titanium CAD/
CAM abutments. Specifically for CAD/CAM titanium
Procera® abutment the most retentive cement was zincphosphate, followed by polyurethane, polyurethane plus
vaseline, and zinc oxide-eugenol (17).
The Procera® system also allowed the production of
sintered alumina and zirconia abutments, which have
provided new opportunities for single-tooth esthetic
restorations. With this system, the abutment is virtually
designed by the local laboratory using a Procera digital
scanning system and software purchased from Nobel
Biocare. The information is ellectronically transmitted to a Procera facility where the virtual abutment is
milled and returned to the local laboratory. The dentist
has the option to receive both a CAD/CAM abutment
and CAD/CAM titanium or ceramic coping using this
same system (2).
Some advantages of this technique are the possibility
of shorten the overall treatment time and the minimal
manipulation of the soft tissue (18). Heydecke et al. (19)
emphasizes the natural appearance using aluminum
oxide ceramic implant abutments and the minimal necessity of postproduction adjustments if we compare
with stock abutments. The accuracy of this system is reflected in the concept Teeth-in-an-hourTM (20) for immediate functional loading in maxilla using CAD/CAM
fixed prostheses manufactured from a block of milled
titanium through the protocol Procera Implant Bridge.
Procera abutment, after determining the precision of fit
(21), could be considered for universal application for
the most commonly used external-hexagon implant systems Branemark System (Nobel Biocare, Lifecore Restore (Lifecore Biomedical, Chaska, MN), Implant Innovations (3i) System, ImplaMed (Sterngold-IMplaMed,
Attleboro, MA) y Paragon Taper-Lock (Encino, CA).
There are some in vitro studies (22,23) which purpose
was to assess the precision at the implant interface of titanium, zirconia and alumina Procera abutments with a
hexagonal connection for single tooth restorations, suggesting Procera abutments showed less than 3 degrees of rotational freedom, what shows a stable screw joint
and may reduce the risk of screw loosening.
Encode® Restorative System (3i Implant Innovations
Inc, Palm Beach Gardes, Fla). The system consists of
a coded healing abutment and a CAD/CAM titanium
abutment. The proprietary healing abutment has three
notches that are codes that provide the information
about the implant hex position, the platform diameter,
and the soft tissue collar height, all of which are necessary to design the definitive abutment. A laser optical
scanner interprets these codes, and a custom abutment
is designed with special CAD software. The scanning
process is a white light scanner that scans the definitive casts of the healing abutment and the opposing
arch. The digital information is transformed to a solid
model. The proprietary software recognizes the codes
on the healing abutment and the designed abutment is
then milled from a solid titanium alloy block. Finally, a
cement-retained restoration is fabricated over the CAD/
CAM abutment in the dental laboratory (24).
Advantages of this system are (24): 1) it provides an anatomical emergente profile for the definitive abutment;
2) it provides the ability to correct an implant angle of
up to 30 degrees; 3) there is no need to wax or cast,
so laboratory time and cost are decreased; 4) it is easy
to use since there is an option not to make an implantlevel impression, and there is no need for intraoral abutment preparation. However, this technique does have its
disadvantages (24,25): 1) its use is limited to a specific
implant system (3i Implant Innovtions, Inc); 2) an interarch space of at least 6 mm and minimal distance of 2
mm between the implants are required; 3) ceramic abutments are not available; 4) specific mounting plates are
needed for mounting the final casts, 5) these abutments
cannot be used when there is less than 1 mm of soft tissue surrounding an implant or if one implant deviates
more than 30 degrees from other implants.
CAD/CAM surgical guides
Placement of dental implants requires precise planning that accounts for anatomic limitations and restorative goals. Diagnosis can be made with the assistance
of computerized tomographic scanning, but transfer
of planning to the surgical field is limited. Recently,
novel CAD/CAM techniques such as stereolithographic
rapid prototyping have been developed to build surgical guides in an attempt to improve precision of implant
placement (26,27). As a result of this technology, the
surgical guide permits accurate and consistent position
and orientation of the implants (28). Sarment et al. (26)
showed the advantage of this technique in a case-control study that compared the distances between planned
implants and actual osteotomies using a conventional
surgical guide or a stereolithographic surgical guide
(SurgiGuide; Materialise Medical, Glen Burnie, MD).
Using the surgical template, minimally invasive surgery
is performed without a flap, what is called transmucosal
implant placement, that shows reduced patient morbidity (29,30).
Then, the transference of the surgical planification from
the software to the patient using these guides facilitates
the production of a prostheses that will be delivered after surgery, achieving immediate functional loading to
the implants.
Conclusions
1 CAD/CAM technology applied to implant surgery allows the production of high resistance and high density
crowns, and the manufacture of implant abutments and
surgical guides.
2 A custom design, a perfect fit and a higher resistance
are the main characteristics of CAD/CAM implant abutments.
3 CAD/CAM surgical templates allow to transfer the
software planning to the surgical field.

        

[drsushant]

 IN-OFFICE MILLING

When using CEREC and E4D, clinicians can fabricate their own restorations chairside. This capability can be an advantage in most cases; however, excellent patient scheduling is needed, and the dentist or staff person is required to take the total responsibility for the restoration fabrication. Clinicians state that all current dental CAD/CAM systems can be improved, including both the chairside and laboratory aspects of the process. The level of consistency and accuracy of restorations can occasionally be less than acceptable and can require extra time if the restoration proposals are not adequate for quick and simple modification. We are told by CAD/ CAM mechanical engineers that the current level of accuracy and consistency for CAD/CAM systems in dentistry is below that of some other industries, such as medical, electronic, automotive, machining, etc. Despite this limitation, the current dental systems have proven to be clinically acceptable in most situations when attention to detail is provided by the clinician.

Currently, there are about 12,000 in-office milling devices in the US, the majority of which are CEREC systems and a growing number are E4D systems. Although there is the expected competition and marketing claims from both companies, CR has demonstrated that both systems can provide an excellent restoration. Both devices have advantages over their competitor and both have areas of improvement. We expect many new and exciting innovations as the technology continues to evolve.

What are the differences in clinical techniques when a dentist decides to use digital impressions and in-office milling instead of conventional techniques? The following steps show that there can be significant differences in the clinical procedure. Steps 3 to 8 can be legally accomplished by staff persons in most states:



1. Seat the patient, select the color of the restoration, and anesthetize the patient.

2. Make the tooth preparation to a specified design, which may be slightly different depending on the type of ceramic or composite used for the restoration.

3. Place reflective powder if required. CEREC requires a thin dusting of powder, while E4D does not require the use of powder. (Sometimes a liquid contrast agent on enamel or metal restorations is needed with the E4D.) Both preimpression techniques are minimal and require little time and effort.

4. Make a digital impression of the tooth preparation. The length of impression time varies by system. 

5. Design the restoration using the computer program. This task can require from a few minutes to 20 minutes, related to the quality of the impression, the accuracy need of the proposed restoration, and the number of changes the clinician desires. 

6. Mill the restoration from standardized blocks. There are a variety of materials from which to choose, with most materials coming from Vident, Ivoclar Vivadent, or 3M ESPE. The introduction of IPS e.max CAD (Ivoclar Vivadent) for chairside milling has allowed the clinician to provide a stronger restoration, but requires a furnace to fully crystallize (bake) the material.

7. Adjust the restoration clinically.

8. Characterize and/or stain the restoration as desired or needed. Several furnaces are available with one of the most popular being the Programat CS (Ivoclar Vivadent).

9. Cement the restoration (resin cement is the most commonly used for these mostly ceramic or polymer restorations). Most clinicians are using either a self-adhesive (such as RelyX Unicem 2 or Maxcem Elite, or separate self-etching resin cement (such as Multilink Automix).

10. Evaluate and adjust the occlusion with fine diamonds and porcelain polishing instruments (such as Brasseler USA or KOMET). 

11. Finish and polish the restoration where adjustments were made with porcelain polishing paste (such as Diashine by VH Technologies).



CR research has shown for more than nearly 25 years that the quality of restorations made from digital impressions and milled in-office are the same as or better than restorations made in the conventional manner when strict attention to the protocol is provided. Digital impressions and chairside milling should not be considered to allow less attention to detail or require less clinical expertise. When those using these concepts follow the manufacturers’ instructions and develop excellent clinical skills, these chairside digital devices can deliver a great restoration.

How soon this concept will become commonplace in dentistry is unknown. We appear to be somewhat behind other areas in adapting to this popular and growing concept. More innovative planning and development requiring more manufacturer investment is suggested to make the systems more accurate, faster, easier, and definitely less expensive. For some dental practices, the move to in-office milling can be efficient, predictable, and profitable.

        

[Drsumitra]

Feldspathic porcelain is the standard, traditional porcelain that is used for crowns. Many cosmetic dentists feel that this is the most beautiful porcelain.
The Empress crown – Empress is strictly speaking not a porcelain, but is more like a glass. It can be called a ceramic material. The Empress material is cast rather than baked as a feldspathic porcelain crown is. The fit of Empress is more precise than the baked feldspathic porcelain. However, the color in Empress is mostly baked on the outside. Empress can be very beautiful. For appearance’s sake, some expert cosmetic dentists prefer the feldspathic porcelain, and some prefer the Empress.
The Procera crown – Procera is a milled ceramic on the inside with a more traditional porcelain baked onto the outside. The advantage of Procera is its exceptional strength. However, the milled ceramic core is opaque white, so many cosmetic dentists feel that it isn’t as natural-looking as the more translucent materials. An advantage of Procera is that it doesn’t have to be bonded to the tooth but can be cemented with ordinary crown and bridge cement, a technique familiar to all dentists.
The Lava crown – Lava is similar to Procera, but the milled ceramic on the inside is a more translucent Zirconia, rather than an opaque white material. The Zirconia is shaded, and then the final esthetics of the crown are achieved in the baked-on outer layer. The Lava crown can also be cemented with traditional techniques. However, any crown cemented with a traditional crown and bridge cement is going to be susceptible to a compromise in the appearance if that cement line ever shows.
Zirconia crowns, if they are done right, can be translucent enough to look natural. And if they are bonded to the teeth, instead of being cemented with conventional dental cement, they won’t show a black line at the gumline.
The Cerec crown – Cerec is are also milled from a block of very hard ceramic material. What’s unique about Cerec is that the crown is milled by a computer in the dentist’s office rather than in a separate dental laboratory. Thus, the dentist doesn’t have to send out for it to be made—it can be made on the spot. So, no second appointment is required, and no wearing of a temporary crown between appointments. Cerec is milled from a block of ceramic that is a single color, so it is generally not considered esthetic enough for demanding cosmetic dentists. A few exceptional dentists who are artists, however, are able to custom stain Cerec for front teeth so that they are truly beautiful. Some even make Cerec veneers that can be placed the same day.
To be precise, Cerec is actually a technique and not a material. There are several companies that make ceramic materials for use in Cerec machines.
The InCeram crown – InCeram is made of a very dense and very tough aluminous porcelain. It also has excellent esthetics, but is more opaque than feldspathic porcelain. InCeram is also strong enough to be cemented with traditional dental cement.

 

        

[drmithila]

ST. PAUL, Minn. – (July 2, 2012) – 3M ESPE is now bringing its unique new Lava Ultimate Restorative to labs by making it available to all dental professionals through their preferred Authorized Lava® Milling and Design Centers. Lava Ultimate restorative resin nano ceramic CAD/CAM material was originally introduced to users of chairside CEREC® and E4D® CAD/CAM systems in late 2011, and as those dentists have already experienced, Lava Ultimate restorative provides a polish that lasts, along with functionality other CAD/CAM materials can’t match. In fact, 3M ESPE is backing Lava Ultimate restorative with its industry-leading 10-year warranty.

“Dentists with chairside CAD/CAM systems have responded enthusiastically to the unique properties of this new resin nano ceramic CAD/CAM material,” said Mark Gates, vice president of sales and marketing, 3M ESPE. “We are happy to now offer Lava Ultimate restorative to an even greater number of dentists through their labs.”

Lava Ultimate restorative is part of a new class of CAD/CAM material based on 3M ESPE’s renowned nanotechnology. This resilient new milling material is incredibly durable and shock absorbent, not brittle. The unique properties of the CAD/CAM material enable a fast, no-firing process, and only a few minutes of polishing are needed to achieve an enamel-like luster. The resin nano ceramic CAD/CAM material also allows dentists to easily make adjustments, as well as to build-up and reseal restorations.

Lava Ultimate restorative CAD/CAM material builds upon two of 3M’s core technology platforms: ceramics and nanotechnology. 3M has developed a proprietary process for creating the CAD/CAM material, which is formulated from a blend of approximately 80 percent nanoceramic particles embedded in a highly-cured resin matrix. The result is a unique, patented resin nano ceramic milling material that maintains a brilliant, long-lasting polish.

Lava Ultimate restorative is indicated for a full range of permanent adhesive, single-unit restorations, including crowns, onlays, inlays and veneers. Additionally, Lava Ultimate restorative is ideally suited for implant-supported restorations because of its high flexural strength, shock-absorbing properties and low wear. Lava Ultimate restorative reduces stress to the implant, and dentists can adjust the material for occlusion with additive and subtractive techniques. Lava Ultimate restorative is offered in eight shades, four of which include both high and low translucencies, giving labs the choices they need to create natural-looking restorations.

Two additional product introductions from 3M ESPE give dentists the complete package for delivering ceramic restorations alongside Lava Ultimate restorative: 3M™ ESPE™ RelyX™ Ultimate Adhesive Resin Cement and 3M™ ESPE™ Scotchbond™ Universal Adhesive. This cement and adhesive are compatible and offer optimal performance when used in combination with Lava Ultimate restorative, giving dentists the utmost in ease of use and high performance.

For more information about 3M ESPE’s Lava Ultimate restorative, visit http://www.3MESPE.com/LavaUltimate

 

        

[Drsumitra]

My lab tchnician is working with Bruxzir….just an article i found to try and understand this system

 

What is BruxZir?

BruxZir® Solid Zirconia is a monolithic solid zirconia restoration with no porcelain overlay. More brawn than beauty, you’ll be impressed by the esthetics of BruxZir when prescribed instead of posterior metal occlusal PFMs and full-cast metal restorations. BruxZir is virtually chip proof, making it the ideal restoration for bruxers, implant restorations and areas with limited occlusal space.

BruxZir Solid Zirconia crowns & bridges are made from the highest quality zirconia powder from Japan. We chemically and physically reprocess the powder to further reduce the zirconia particle sizes. BruxZir milling blanks are then created through a unique patent-pending process. Unlike conventional high-pressure milling blank manufacture, our processing gives BruxZir improved light transmission, which provides a lower, more natural shade value.

Designed and milled using CAD/CAM technology, BruxZir is sintered for 6.5 hours at 1,530 degrees Celsius. The final BruxZir restoration emerges nearly chip proof and is glazed to a smooth surface.

Indications

BruxZir Solid Zirconia is indicated for crowns, bridges, implants, inlays and onlays. It is an esthetic alternative to PFM metal occlusal/lingual or full-cast restorations. The chip proof durability of BruxZir is ideal for bruxers who have broken natural teeth or previous PFM restorations. BruxZir is also ideal when the patient lacks the preparation space for a PFM.

Patient Benefits

Chip-resistant, as it is made of solid zirconia with no porcelain overlay
Glazed to a smooth surface to reduce plaque accumulation
Preparation Requirements

Shoulder preparation not needed, feather edge is okay. It is a conservative preparation similar to full-cast gold, so any preparation with at least 0.5 mm of occlusal space is accepted.
Minimum occlusal reduction of 0.5 mm; 1 mm is ideal.
Instructions for Adjusting and Polishing BruxZir Crowns & Bridges

Adjust BruxZir Solid Zirconia restorations using a fine-grit diamond with light pressure to avoid potential microfractures. The specially designed Axis Dental BruxZir Adjustment & Polishing Set (LS-7579) may be purchased through your dental dealer or by calling 800-355-5063 .

A football-shaped bur is most effective for adjusting the occlusal surfaces of posterior teeth and lingual surfaces of anterior teeth.
A tapered bur is most effective for adjusting proximal contacts.
A round bur is used to adjust a cusp or fossa and for creating endodontic access.
Technical Update: Download Instructions
Technical Update: Do Not Use Discs To Finish Full-Contour Zirconia
Cementation Recommendations

Ceramir® Crown & Bridge (Doxa Dental; Newport Beach, Calif.) or a resin-reinforced glass ionomer cement such as RelyX™ Luting Cement (3M ESPE; St. Paul, Minn.) or GC Fuji Plus™ (GC America; Alsip; Ill.)
For short or over-tapered preparations, use a resin cement such as RelyX™ Unicem (3M ESPE) or Panavia™ F2.0 (Kuraray; New York, N.Y.)
Instructions for Seating BruxZir® and Other Zirconia-Based Crowns & Bridges

BruxZir restorations are fabricated from solid zirconia oxide material, much like the zirconia oxide coping found in restorations such as Prismatik Clinical Zirconia™, Lava™ Zirconia (3M ESPE; St. Paul, Minn.), and NobelProcera™ (Nobel Biocare; Yorba Linda, Calif.). Like most metals, zirconia exhibits a strong affinity for phosphate groups, and zirconia oxide is no different. We can take advantage of this fact with phosphate-containing primers, such as Monobond Plus (Ivoclar Vivadent; Amherst, N.Y.) and Z-Prime™ Plus (Bisco; Schaumburg, Ill.), or cements such as Ceramir® Crown & Bridge (Doxa Dental; Newport Beach, Calif.). Unfortunately, saliva also contains phosphates in the form of phospholipids, so when a BruxZir crown or bridge is tried in the patient’s mouth and comes in contact with saliva, the phosphate groups in the saliva bind to the zirconia oxide and cannot be rinsed out with water. Attempting to use phosphoric acid (which is full of phosphate groups) to "clean" the saliva out only makes the problem worse.

The only way we have found to successfully remove these phosphate groups from the interior of a BruxZir restoration is with the use of Ivoclean (Ivoclar Vivadent). This is a zirconia oxide solution placed inside the restoration for 20 seconds and then rinsed out. Due to the large concentration of free zirconia oxide in the Ivoclean, it acts as a sponge and binds to the phosphate groups that were previously bound to the BruxZir restoration. Once the Ivoclean is rinsed out, you will have a fresh bonding surface for the Monobond Plus, Z-Prime Plus or Ceramir to bond to.

The protocol would be:

Try in BruxZir or zirconia-based restoration.
Rinse saliva out of restoration.
Place Ivoclean in restoration for 20 seconds and rinse.
Cement restoration with Ceramir –or– place Monobond Plus/Z-Prime Plus and place with cement of your choice

 

        

[drmithila]

A dimensionally accurate impression is one of the primary determinants for a precise fitting indirect restoration. The clinical success of the indirect restoration requires a precise working model and thus depends upon the accuracy of the final impression.1 The use of custom fabricated trays with elastomeric impression materials can improve the accuracy of the working model.2 There are a myriad of materials and techniques available for custom tray fabrication, including autopolymerizing and heat-activated acrylic resins, thermoplastic resins, and visible light-cured resins. The techniques for custom tray fabrication also vary and range from direct intraoral techniques to indirect laboratory procedures on a primary model.

The design and use of the custom tray offers distinct clinical advantages compared to the stock tray. First, dimensional changes that occur during the polymerization of elastomeric impression materials are proportional to the thickness of the material.3 Custom tray design can provide dimensional accuracy and stability by providing a uniform thickness of material throughout the tray.2,4,5 Utilization of stock trays can result in variations in thickness of the material and the potential for dimensional changes and inaccuracies in the model.2,4,6 Second, the custom tray rigidity reduces the potential for distortion of the impression in comparison to the flexible stock trays.7,8 Flexible trays can increase the potential for the impression material to pull away from the adhesive during polymerization of the material and removal from the oral cavity.9 Reports also indicate that tray flexure can contribute to impression and cast distortion.5,10,11 Finally, the custom tray design controls the size and conserves the volume of material required for the impression, reducing the cost of the impression material used for each impression. A streamlined design can reduce discomfort to the patient during the impression procedure because of the smaller design size and reduced volume of material. Furthermore, reducing the volume of elastomeric material utilized can minimize the polymerization-induced shrinkage while offsetting the additional economical costs of the tray fabrication.

CONSIDERATION FACTORS FOR FABRICATION AND UTILIZATION OF THE CUSTOM IMPRESSION TRAY
Visible light-cured resins exhibit dimensional stability immediately after curing, thus allowing immediate clinical use after fabrication.5,12 Research indicates that autopolymerizing acrylic resins should be fabricated 24 hours before the impression procedure.5,13 The dimensional stability of elastomeric impression materials is considered to depend on the bulk of material which is the distance from the inner surface of the tray to the surface of the impression.4,14,15 Elastomeric impression materials are considered most stable when they have a uniform thickness of 2 to 4 mm.16 Incorporating dental and/or tissue stops can provide a uniform impression material thickness of approximately 2 to 4 mm.17,18
Adapting the visible light-cured resin material directly over the wax spacer may leave a wax residue remaining in the tray. This residue contamination can interfere with adhesion of elastomeric impression materials to the impression tray. Even a small release of the impression material can cause a distortion in the impression, so this is critical. Surface cleaning of the tray using boiling water, pressurized steam and/or a wax remover is suggested. Another recommended method involves burnishing tin foil over the wax spacer.It is essential that the impression material be securely attached to the tray, especially during removal of the set material from the oral cavity. Surface preparation of the custom tray can significantly affect the retention of the impression material and can improve adhesion between impression material and tray. Methods for improving retention/adhesion include: perforating or roughening of the custom tray surface with tungsten carbide burs and application of adhesive solutions.20,21

Adhesive drying times of less than 15 minutes reduced the bond strength values of the elastomeric impression materials to the custom tray. To obtain durable and stable adhesion between elastomeric impression material and tray, the drying time after application of adhesive should be at least 15 minutes.21,22 Also, it is important to remember that each adhesive is specific to the impression material (ie, a polysulfide adhesive can not be used with an addition silicone impression material).

FABRICATION AND UTILIZATION OF THE VISIBLE LIGHT-CURED CUSTOM IMPRESSION TRAY
The main objective in tray construction is to provide a rigid tray for retention of the impression material. The aforementioned consideration factors can provide insight into the optimal fabrication and utilization of the custom tray. A visible light-cured resin material (Palatray XL [Heraeus Kulzer]) was selected for its rigidity, high dimensional stability, ease of manipulation, and unrestricted working time. Also, this material provides the ability to be ideally contoured prior to curing, thus eliminating prolonged finishing times. Other visible light-cured resins include Individo Lux (VOCO), Triad (DENTSPLY International), and Fastray LC (Bosworth Products).

Fabricating an indirect custom impression tray requires planning, a diagnostic model, and laboratory procedural time. Figures 1 to 10c illustrate the laboratory fabrication and clinical utilization of the visible light-cured custom impression tray that can be used to obtain a precise and predictable final impression.

 

        

[drmithila]

Robust dental systems obtained by computer-aided design and manufacture (CAD/CAM) have been introduced and, in parallel, the strength of the ceramic materials used in fabricating dental crowns has improved. Yet all-ceramic crowns suffer from near-surface damage, limiting their clinical success, especially on posterior teeth. Factors directly associated with CAD/CAM fabrication that contribute to the degree of damage include material selection and machining parameters and strategies. However, a number of additional factors also either create new damage modes or exacerbate subcritical damage, potentially leading to catastrophic failure of the crown. Such factors include post-fabrication manipulations in the laboratory or by the clinician, fatigue associated with natural occlusal function, and stress fields created by compliance or distortion within the supporting tooth structure and/or adhesive material holding the crown to the tooth. Any damage reduces the strength of a crown, increasing the probability of catastrophic failure. The challenge is to understand and manage the combination of competing damage initiation sites and mechanisms, limitations imposed by the demand for aesthetics, and biologically related constraints.

        

[drmithila]

The global dental CAD/CAM system market is expected to reach $540 million by 2016, according to a new report from the Millennium Research Group.

This market will see particularly strong growth in its chairside segment, particularly in Japan, according to the company.

As a result of demand from dentists for chairside systems, a number of new competitors will be entering the market through 2016, which will lead to greater competition and a downward pressure on selling prices. In the U.S., for example, 3Shape’s Trios scanner will capitalize on dentists’ interest in replacing traditional impression-taking methods with digital techniques. The marketing of this intraoral scanner, along with new devices from Laserdenta, MHT (to be rebranded by Zfx and Clon 3D), Dimensional Photonics International, and a.tron3d, will dramatically expand the market, according to Millennium.

The underpenetrated Japanese market will see the most growth, due in part to a large number of technologically savvy dentists who are seeking a marketable advantage in their practice, according to Brady Baker, an analyst with Millennium. The ceramic dental restorations associated with CAD/CAM technology are not reimbursed by national health insurance, so reimbursement cuts to competing traditional metal restorations will actually improve the relative cost of ceramics, he added.

        

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