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Dentist's Resources

Lab Communication

 
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General Communication

Please return any lab telephone calls to your office promptly. Calls are necessary to clarify technical issues that have halted case production. Once we have clarified the required details, the case will be promptly placed back into production.

Photos

Photos are great for showing contours and characterizations but colour matching requires more specific information. Refer to our notes below on taking shades. When sending a photo for a shade, please include the shade tab in the photo for reference purposes.

Rx Scripts

Specific information is critical to ensure that a case is delivered as expected. 

  • Ensure you have a contact number and address especially if you have multiple offices.

  • A due date of ASAP will require our lab to contact your office and thereby potentially slow down production time. Please be specific.

  • Request a due date for a case which is the day before the patient's appointment.

  • Tooth and stump shades are vital.

Implants

Please include a copy of the letter you receive from the oral surgeon which will provide us with the implant specifications needed for ordering the appropriate hardware .

Invite

We encourage all of our clients to visit the lab and meet our team of technicians which is mutually beneficial to our ongoing relationship.

 

In-Clinic Shade Selection Tips

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  • Select the shade at the beginning of the appointment, due to the fact that teeth dehydrate very quickly.

  • Ensure the patient is sitting upright or standing. This will help with exposing the teeth to the most natural light.

  • Ensure that the shade tab is at the same level as the teeth for accurate colour.

  • If the patient is bleaching, please wait 2 weeks for the colour to stabilize.

  • Use neutral colours for the patient bibs, like light blue or grey as they are restful to the eyes and enhance our ability to perceive the parameters of shade selection.

  • If a patient is wearing lipstick, ask them to remove it.

  • Do not expose teeth to direct light. Preferable to take shades in a room with a window or colour corrected lights (CRI rating of 100 and a 5500k colour temperature)

  • Stump shades – critical for e .max crowns, veneers and translucent zirconia. Please stipulate on Rx if stump shade is dark grey or black.

  • It is always a good idea to ask your assistant or hygienist for a second opinion to confirm the shade.

  • Take a digital photo and send to the lab. Please ensure the shade tab is INCLUDED in the photo.

Remember that shade tabs are affected over time by sterilization and exposure to chemicals in the operatory, so replace them on a routine basis to maintain colour accuracy.

VITA® Shade Guides can be steam autoclaved up to a maximum temperature of 284° F (140°C).

Autoclave instructions: Use of a dry autoclave will damage the Shade Guides and will void any warranty. Follow the manufacturer instructions for autoclave cycle times.

NOTE: The base of Classical Shade Guides with the raised lettering of the word “Vitapan” cannot withstand autoclave. These holders must be treated with surface disinfectants only.

Surface disinfection: Follow the disinfectant manufacturers instructions for proper use of surface disinfectants of VITA Shade Guides. Disinfectants with Phenols, accelerated Hydrogen Peroxide, Iodine, Methyl Ethyl Ketone, or Chloroform have been shown to damage the Shade Guides and should be avoided when possible.

 

Efficient Shade Taking

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Remove the VITA Valueguide 3D-MASTER from the opened Linearguide.

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Use the VITA Valueguide 3D-MASTER to make an initial choice by comparing the shade samples with the natural tooth. Determine which degree of lightness from 0 to 5 matches the tooth shade.

 

If you are sending pictures to the lab please take a photo of the tooth AND the shade tab in the same photo. 

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Based on your initial choice, take the corresponding VITA Chroma / Hueguide 3D-MASTER (0/1, 2, 3, 4 or 5) out of the plastic box and determine the chroma and the hue.

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You have determined the suitable tooth shade quickly and reliably in just two steps. 

Benefits

  • A fast and precise way to achieve the correct tooth shade in just two steps

  • Systematic arrangement and modern design for a simple, self-explanatory application

  • Clear organization of the shade samples in terms of lightness, chroma, and hue

  • 26 natural and systematically arranged tooth shades and three additional shades for tooth whitening (VITA Bleached Shades)

  • Possibility of creating intermediate shades by mixing

Stump Shade Guide

 
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Custom Shade Protocols in Lab

Custom Shade Protocols in Lab

Our goal is to have the final restoration blend in seamlessly with the existing natural dentition.

Patient tooth shade, tooth translucency, thickness of the preparation, stump shade of the

preparation, plus the choice of restorative material, all influence this integration of the final

restoration. The clinic can send the lab the shade tab colour, or even better, a photo

(image@crosstowndental.com) showing the tooth with two shade tabs, incisal edges of tabs to

the incisal of the natural tooth, plus shade tab identifiers (e.g. A2 or 3M1), so that we can

visualize the subtleties of contours and characterization needed to create the final ceramics.

However, there are times that the clinic chooses to send the patient to the lab for more complex

custom ceramic work. We request that you review the following information and protocols prior

to the patient visit.

Shade Verification Time: 15 min in lab

Teeth that are prepared dry out, resulting in shades one to two shades lighter than normal

We recommend a shade be done prior to tooth preparation or 24 hours after preparation

We would suggest an appointment prior to visiting the lab

 

Custome Shade Build Time: 1-3 Hrs Special

  • Dental clinic must call the porcelain department to confirm an appointment for custom shading

  • The in lab process is time consuming so we only have one or two spots available.

  • Patients must be aware they will need to wait for the process to be completed.

  • The patient should know which is being prepped so we can shade accurately.

  • Temporary must be loosened prior to lab visit for customized staining and shade adjustments.

  • Once a custom stain process is completed to patient satisfaction, we can let the patient go, so

  • that we can complete the final steps in the ceramic process and send the crown later in the

  • week. OR

  • If a patient is returning to the dental office the same day for final cementation they will have to wait for the completed crown.

Notes

  • Custom shades and adjustments in the lab are complementary

  • Best natural light is in the morning in summer and afternoon in the winter

  • We use full spectrum daylight bulbs in our lab for accurate colour

  • Stump shades, natural or a metal post, must be noted

  • A stump shade can be taken by using the lingual of the current office shade tab you use or with

  • the Ivoclar Natural Die Material guide.

  • The darker the stump shade, the more preparation we need in full ceramics to mask the lower

  • value of the preparation.

  • Veneers always require a stump shade for an accurate restoration colour

 

Crown & Bridge Materials

Crown preparation guides for various materials:

Handling instructions for all-ceramic materials:

Lithium Disilicate

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Depending on the thickness of the crown, a lithium disilicate crown can be bonded or luted conventionally. The threshold thickness for conventional cementation is 1 .5 mm; that is, the crown should be at least 1 .5 mm in thickness in order to have the strength to be able to be cemented conventionally. If it does not have the thickness required, it should be adhesively bonded otherwise there is risk of fracture.

As with any restoration that requires bonding, the protocol can be split into two segments, the tooth and the prosthesis . The tooth should be prepared for a total bond by being etched with 35% phosphoric acid, rinsed and dried and then the selected bonding agent should be used . Instructions for handling are dependent on the selected bonding agent . Self-etch/self-adhesive bonding agents can also be used to eliminate the need for 35% phosphoric acid, however it should be noted that bond strengths with these bonding agents can be lower than with total etch solutions .

The restoration should be prepared by being etched with 5% hydrofluoric acid for 20s and rinsed . Generally, the ceramic should be cleaned by ethanol or with phosphoric acid to remove any residual and unreacted hydrofluoric acid and then rinsed with water . A silanating agent such as Ivoclar’s Monobond plus should be applied for 1m and then air dried . The resin cement can then be loaded and the crown seated on the tooth . Excess cement should be cleaned, the contacts should be flossed and the cement should be allowed to set . A final light cure is generally recommended to polymerize any unreacted resin cement .

Zirconia-based restorations

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Zirconia-based restorations can be luted but generally don’t bond as the zirconia does not acid etch. Resin cements can be used, as can resin-modified glass ionomer cements. Because micromechanical retention can’t be achieved with conventional etching, that leaves fine-grit aluminum oxide (50 um @ 2 bar) sandblasting to create mechanical retention . A bonding agent (or self-adhesive resin cement) that contains the MDP monomer will provide the best bond strength to the zirconia surface.

There is some suggestion that cleaning the zirconia surface with NaOCl or a commercial product like Ivoclean will expose the oxide layer and provide a stronger bond strength, but this hasn’t necessarily been substantiated in the literature.

Lastly there has been introduced primers designed to improve bonds strengths to Zirconia. Bisco’s Z-Prime PLUS is one such product. Z-Prime contains both MDP (phosphate monomer) as well as BPDM (carboxylate monomer) and early studies are showing potentially improved bond strength with zirconia in a lab setting.

Alternately, one can use conventional cementation.
The preparation geometry plays a vital role in long-term longevity of these crowns. Having adequate resistance and retention form is extremely important to prevent crown dislodgement and/or secondary caries.

 

Preparation Guide for IPS e.max

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Zirconia Preparation Guide

Preparation guidelines for crowns and bridges are similar to the guidelines clinicians use for all-ceramic restorations. General preparation guidelines for zirconia include the following:

  • Preparation should follow the anatomy of the tooth, providing at least the minimum thickness required for the respective restoration. Axial and occlusal reduction of 1.0mm is considered ideal for full-contour zirconia restorations.

  • A definitive finish line (i.e., shoulder with rounded intern line angles or chamfer margin) is recommended. Feather-edge preparations are acceptable for restorations. 

  •  All sharp edges and line angles should be rounded. 

  • Avoid undercuts, 90-degree shoulders, and gutter preparations. 

Ideal Chamfer Margins - Posterior

Occlusal reduction of 1.0mm ideal.

Rounded internal line angles.

Taper between 4 and 8 degrees. 

Axial reduction of 0.5mm to 1.5mm. 

Reduction of 0.5mm at the gingival margin.

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Ideal Chamfer Margins - Anterior

Chamfer/shoulder preparation or feather edge.

Rounded internal line angles.

Incisal reduction of 1.0mm to 1.5mm. 

Axial reduction of 1.0mm.

Reduction of at least 0.5mm at the gingival margin.

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Feather-Edge Margin

Feather-edge margin of greater than or equal to 0.5mm gingival reduction.

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One significant advantage of this restoration is that the preparation can be more conservative than other all-ceramic or even metal-ceramic restorations, with a preparation design similar to that of a full-cast gold crown. The amount of space required will vary slightly depending on the detail of occlusal morphology expected in the outcome.

Margin design:

  • 0.5mm chamfer

  • This allows for a more accurate mill of the pre-sintered zirconia.

  • If a knife or feather-edge preparation is established instead of a chamfer, a restoration can be milled but there is a slightly higher risk of chipping the pre-sintered zirconia during the milling process.

Functional cusp reduction:

  • It is recommended to reduce the functional cusp 1.0-1.5 mm.

  • This allows for possible changes in crown morphology and possible alteration of the occlusion.

Axial wall reduction:

  • 0It should taper 6-8 degrees from the margin to the occlusal 1/3, achieving a depth of 1.0 mm.

  • All transitional edges, angles, and corners must be rounded.

Occlusal reduction:

  • The central groove should be reduced 1.0 - 1.5 mm.

  • This allows space for developing occlusal anatomy. The resulting central groove crown thickness may be as thin as 0.5 mm once the anatomy is added, yet there is still adequate strength to the restoration. If the occlusal reduction space created is less than 1.0 mm, the morphology will typically become saucer-shaped and the technician is forced to scratch the surface to provide some sort of anatomy rather than creating a more natural appearance. 

The resulting thickness of the zirconia restoration will impact the masking ability of a discolored underlying prepared tooth. The thinner the zirconia the more translucent it will be, allowing the underlying tooth substrate to impact the esthetics of the final outcome. Increasing the thickness of the zirconia (increasing the depth of the tooth reduction) will mask the discoloration but will increase the relative opacity of the zirconia because it is a monolithic restoration. It may, therefore, appear higher in value or brighter, than adjacent natural teeth or other restorations. 

 

Implant Impressions

​Dental implants have become a mainstay of restorative dentistry. With the introduction of lower-cost dental implants, and the increasing number of implants placed, more and more patients will present to dental offices for implant therapy. Once osseointegration has been successful, the restorative dentist must accurately capture the positional information of the implant in order to restore it. 

There are a number of ways of doing so, ranging from the simple to the complex. Techniques that are better suited to single implant restoration may not be accurate enough to restore multiple implants to be splinted. There are two fundamental ways of recording implant position, the closed-tray technique, and the open-tray technique.

Impression Techniques

Closed Tray

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​Step 1: The first step to any technique is to make sure that the implant has adequately integrated, and the appropriate parts have been ordered. Generally speaking, the parts needed are the impression coping, and an analog.

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​Step 2: The healing abutment should be removed, and the closed tray impression coping seated and hand tightened. Ensure that the indices have properly lined up when seating as there won't necessarily be a "click" with some implant system.

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​Step 3: It is important to take a radiograph to ensure that the impression coping has properly seated. This is especially important when dealing with implants that have been placed deep.

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​Step 4: Prior to registering an impression, it is important to block off the hex with wax so that the component can be reseated accurately into the impression.

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​Step 5: An adequately fitted tray is used to register an impression of the arch (including the impression coping). When removing the tray, the impression coping will stay engaged to the implant. The impression coping is designed with indices to allow it to be placed back into the impression aligned in a specific way. 

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​Step 6: The next step is to remove the closed tray impression coping from the implant and replace the healing abutment. Upon removing the impression coping from the mouth, it should be tightly screwed to a lab analog. Once it has been connected, the impression coping (with the attached lab analog) should be very carefully seated back into the impression. This step can be done by the dentist but is often done by the lab under a microscope to ensure full seating. At this point, the impression can be poured by the lab and a restoration fabricated. 

Open Tray

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​Step 1: The first step is identical to the closed-tray technique. Verify osseointegration and make sure the appropriate parts have been ordered. For open-tray impression copings, most implant companies fabricate them in a short and a long size. The short is usually used in the posterior where there is limited inter-arch space, and the long is typically used in the anterior. 

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​Step 2: As with the closed-tray technique, the healing abutment should be removed, and the open-tray impression coping is seated and hand-tightened.

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​Step 3: A verification film should be taken to ensure adequate seating. 

The next step is where things differ.

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​Step 4: A plastic tray of appropriate size is chosen. A window needs to be made in the tray where the impression coping will emerge. This window needs to be of adequate size to allow some give for the impression tray to be seated. It is recommended that this window be covered in a thin layer of way (baseplate, or rope wax). The way will contain the impression material while the tray is being seated. It will also provide a visual indication of where the coping is going to emerge. 

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​Step 5: The tray is loaded with impression material and the impression is taken. As the tray is being seated, the coping should be visualized pushing through the wax. It is important that the coping is visible before the impression material sets otherwise retrieving the post will be very onerous.

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​Step 6: Once the impression material has set, the impression coping should be unscrewed and the impression removed. The analog can be placed on the impression coping (that has been picked up by the impression) at this time or sent to the lab with the impression to be done there. 

Indications

For the single implant crown restoration, both techniques are equally accurate (according to published literature). For multiple units that will be splinted, it is advised that the open-tray impression technique be used as the copings can be connected for improved accuracy and picked up in one impression. 

 

Implant-Retained Restorative Options

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Overdenture w/ LOCATORS

  • Minimally invasive, yet affordable (typically 2 implants on lower / 2.4 on upper, LOCATOR attachments)

  • Implant-retained, tissue supported

  • Denture connects to LOCATOR attachments, yet still rests and is mainly supported by tissue

  • Removable by patient

  • Provides additional retention and significantly reduces denture mobility

  • Can retrofit existing denture to "pick up" LOCATOR attachments

  • Implants help to preserve the shape/volume of existing ridge (proximal to implant locations)

  • Denture still slightly mobile

  • Increased maintenance required (cleaning of food particles around implants/attachments in denture)

  • Easier to maintain for patient

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Bar-Supported Overdenture

  • Implant-retained, implant-supported (sometimes bar overdenture will also be supported by tissue in posterior)

  • Denture has metal "coping" or "sleeve" which fits directly onto milled bar: retention is achieved either mechanically or via LOCATOR attachments

  • Often chosen if patient's ridges are greatly resorbed, and additional lip support is needed

  • Removable by patient

  • Splinted bar provides improved stress distribution

  • Nylon retention inserts last longer

  • More expensive: 4-6 implants (typically), additional lab costs for denture - possibly SRA's plus bar

  • Maintenance - routine, thorough cleaning by patient necessary 

  • Though fixed, sometimes still made of the same material as conventional denture (acrylic base, plastic teeth)

  • Can require significantly more space vertically to achieve esthetics and function

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Fixed Hybrid

  • More expensive: 4-6 implants (typically), additional lab costs for denture - SRA's, bars, "conversion fee"

  • Implant retained & supported (prosthesis typically not in contact with tissue)

  • Bar is processed/embedded within the denture

  • More esthetically pleasing - vestibular flanges removed

  • Not removable by patient

  • Maintenance: routine, thorough cleaning by patient necessary 

  • Though fixed, still made of same material as a conventional denture (acrylic base, plastic teeth)

  • removed by Dentist for cleaning every 6 months

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Full Arch Zirconia

  • Implant retained, implant supported (prosthesis typically not in contact with tissue)

  • Cementable or screw-retained

  • Newer options allow for 2-piece, removable prosthesis (Paris bar)

  • Most esthetic 

  • Greatest functionality 

  • Most expensive option: typically 6-8+ implants, metal or zirconia substructure, porcelain directly veneered to substructure 

  • Maintenance: routine, thorough cleaning by patient necessary

  • Expensive to repair

  • Removed by Dentist for cleaning every 6 months

 

Implant - Prosthetic Torque Values

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Disclaimer:

The information (including torque recommendations) is provided for information purposes only and does not constitute advice for medical or treatment purposes. Although all reasonable effort is made to present accurate information (including torque recommendations), Crosstown makes no guarantees of any kind, including but not limited to that it may be outdated, invalid or subject to debate. The information is provided “as is” without warranty of any kind, either express or implied, including without limitation, the implied warranties of merchantability, fitness for use of a particular purpose, or non-infringement.

 

CAD/CAM Subperiosteal

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This new generation of subperiosteal implants is amde of titanium and is manufactured using the latest technology in the dental CAD/CAM field

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Our unique platform offers a wide range of prosthetic components to provide for any kind of restoration.

The proven design increases the initial stability and promotes easy insertion.

The biological design optimizes bone regeneration.

Manufactured in grade 23 6AL-4V ELI titanium.

The CAD/CAM Subperiosteal ImplantTM requires a single-stage surgery, making the patient experience less invasive. The proven design increases initial stability and ensures easy insertion and fixation.

An Unsolved Problem

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Previously there was no predictable solution for the partially edentulous patients who lack bone in the posterior area without sacrificing their healthy anterior teeth. The lack of bone and the low success rate of vertical bone grafting in this area led them to alternative removable solutions such as partials, which reduced their quality of life.

Your Solution

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The Panthera CAD/CAM Subperiosteal ImplantTM is intended to be used for the lower jaw in patients who are partially edentulous with Kennedy class I, II, and III and with bone type of division C-h. The implant is designed for the mandible in situations of severe vertical bone atrophy of the posterior ridges.

 

Aligner Guide

Our aligners are for specific tooth movements and arch coordination using a progression of transparent rigid plastic appliances. We require maxillary and mandibular impressions, using alginate or a digital scan, and a bite record, to develop the proposed treatment plan for the patient. These records will allow us to assess the case and create a video of the treatment plan’s proposed

outcome.

Process

The treatment plan goal is to realign a patient’s teeth. The longer the aligners are in place, the better and quicker will be the outcome; therefore, aligners should be worn at all times, during the day and night; only being removed when eating, playing sports, or brushing teeth. Each aligner set should be worn for 10-14 days then changed for the next set (as directed by the clinician.)

 

We have included the Clenchy seating tool for the patient to chew on to remove the air gaps between the patient’s teeth and the clear aligner.

Care

Aligners can be rinsed in water and excess water shaken off. Then they should be stored in the case that was provided. Never use a napkin or tissue because the appliance may be accidentally discarded.

Attachments


Attachments will include a Zero tray which is the current patient dentition which will be used to begin the treatment plan. This Zero tray will have indentations for the placement of composite onto the teeth to facilitate the anticipated sequence of tooth movements.

 

We recommend 3M Transbond LR Composite and 3M Transbond Plus Self Etching Primer for the tooth etchant.

IPR

IPR may be required. If so, a video can be developed and emailed, plus a printed colour coded IPR diagram will be enclosed.

Retainers

The final set of aligners can be used as retainers. Wire, or the new Clear Bow retainer, can be made for night time use.

 

Bellus 3D

Realistic Face Scanning for Dental Applications

Bellus3D provides a powerful and easy to use 3D face scanning solution enabling dentists and labs to incorporate 3D facial scans into the dental planning process. 3D face scans can be used as an integral part of diagnostic, surgical and restorative smile design planning to accelerate high-value case acceptance and clinician approval.

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Personalized 3D Printed Frames Improve Seal of Face Masks

The Bellus3D Mask Fitter frame is a personalized 3D printed plastic frame that is contoured to the specific shape of a person's face to improve the peripheral seal of surgical, KN95 or other masks. The frame is automatically generated from a 3D face scan using the Bellus3D Face App or Dental Pro app for Apple iPhone X, iPhone 11 or iPad Pro with FaceID capability.

We are excited to offer the printing of these seals and we look forward to collaborating with you and your team!

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This video will show you how to order your Mask Fitter with us.