Lecture 4: digital impressions and CAD/CAM technology

benefits of digital

accuracy of impressions, opportunity to review, adjust and rescan impressions, no physical impression, save time and one visit for in-office system, precise fit of restorations created on digital models, no casting/soldering error, cross-infection control, patient satisfaction

iTERO

accuracy rapid color scan comprehensive restorative and implant workflows comprehensive ortho workflows Open STL export

materials of the chairside workflow

use of fine instruments increases accuracy wet grinding is generally better for glass ceramic restorations dry grinding is advantageous for zirconia restorations

Straumann Cares

-3D capture technique called Multiscan Imaging -quickly and easily create digital impression data -design and produce effective dental restorations small handpiece (one of the smallest, good for limited arch space), voice and gesture control, convenience, reliability, precision, efficiency

Types of impressions

1) aqueous elastomers (water based) 2) nonaqueous elastomers 3) digital

total production time as a sum of lab plus clinical work steps was more than _____ faster for the complete digital workflow (____) compared to the mixed analog-digital workflow (_____)

2 fold faster for complete digital workflow (75.3 minutes) compared to analog-digital workflow (156.6 mins)

3M

3M true definition scanner-- available in mobile or cart editions ease of use affordability for making fast, precise digital dental impressions 3D-in-motion video technology for a true replica of patient's oral anatomy

marginal discrepancy/precision

Monolithic ZrO2 crowns (68.5um) metal-ceramic crowns (92.4) monolithic lithium disilicate crowns (113.8um) **all these are less than 120 microns, which is acceptable for conventional

companies/different scanners

Straumann DW Dentsply Sirona Cerec Planmeca-E4D iTERO 3SHAPE TRIOS 3M

CAD/CAM

computer-assisted design and computer-assisted manufacturing a chairside optical scanner that captures the geometry of prepared tooth, transforming it into 3D digital data. a computer software that allows the user to design a dental prosthesis and an additive or subtractive manufacturing process that transforms the data into a final prosthesis (3D printing or milling machine needed)

direct digital impressions and indirect digital scanning

direct digital impressions: digital scan using a camera, CAD/CAM indirect digital scanning: wax pattern made on cast. scan of cast, scan of wax pattern. then design crown based on scanned was pattern.

the most important questions that dentists should consider

do you want to make in-office chairside restorations? what do you want to fabricate with this technology? single/multiple tooth restorations, implant restorations, surgical guides...this answer will guide you to decide which you will implement. what kind of restorative materials do you anticipate processing with your chairside system? what will your strategy be for imtegrating the chairside workflow into your dental practice? do you intend to do the scanning and designing yourself? will an assistant dentist or your in-house dental technician handle the staining work? is the chairside technology an open/closed system? advantage of an open system is that scan datasets can be saved in STL format for further CAD/CAM processing. Which implant systems are compatible with a specific intraoral scanning system or CAD/CAD software? Should the datasets be compatible with CBCT? how good is the technical support for a given system?

disadvantages of digital

expensive, training, updated software, limited interarch space (hard to scan distal tooth)

image acquisition and recording occlusion

image acquisition is more rapid with continuous capturing of a series of images by the scanner once in position occlusion is recorded by scanning the interocclusal relationship. images show contacts of interdigitation of the opposing teeth.

reasons for choosing scanners

intraoral scanners used to create a digital image of teeth no need traditional impression materials patient dentitions and bite optically recorded software to produce digital models CAM/CAM- milling and printing unlimited data storage good for documenting changes -the digital camera: software to create image using CAD/CAM system and connection to export the image. milling unit: milling unit to fabricate the prosthesis (in house or in lab) in office CAD/CAM impression technique: scanner + milling chairside digital impression technique: scanner

CAD/CAM milled zirconia crown

it is milled in an OVERSIZED form due to the shrinkage that will occur upon firing (sintering process). so, the shrinkage is calculated. *in order to have minimal occlusal adjustments, tell the lab to design it out of occlusion because of the milling oversight-- will shrink in oven--calculated in oven for zirconia. if done into occlusion, then will need to adjust fit. **design zirconia out of occlusion!!

limitations of chairside workflow

learning curve dry working field implant-specific scan body is needed static and dynamic occlusion cost and closed systems scanning strategy: scan path is defines as the specific movement pattern through which an intraoral scanner must be guided in order to produce a digital model with the greatest accuracy

conventional versus digital impressions

many steps with conventional.

3SHAPE TRIOS

measures shades as you scan takes HD photos for high detail capture fast and easy

milling

milling machines can produce full contour crowns, bridges, custom abutments, full arch restorations PMMA, Zr, Ti, IPS e.mad CAD

why digital?

patient care, grow your practice, be high tech, work less hours, make more money, reduce stress, motivate your staff, have fun, predictable results, no bridge needed for the surgeon: predictability, less surprises, reduced chair time, service to client. patient: no goo, less visits, esthetic outcome, predictable cost. referring doctor: predictable cost, simpler restorations, more chair time, patient referrals

Planmeca-E4D

planmeca FIT create and design digital models with PlanCAD software share cases with Planmeca Romexis Cloud PlanMill 40S

Dentsply Sirona Cerec

precise 3D images in NATURAL color SHADE DETECTION (scan other teeth) fast and precise full-arch scans

advantages of chair-side workflow

real-time scanning and visualization of impressions easy and selective repeatability pre-scan with true-color display no impression trays, materials, or casts preparation and restoration analysis rapid communication and availability archivability implant treatment planning capability chairside treatment for patient satisfaction cost effectiveness

ideal requirements of a good impression

record all the prepared tooth surfaces and some of the unprepared tooth cervical to the finish line with implants, record their position in the bone and relationship to teeth record unprepared teeth so their shape can be used to restablish morphology of the crown and their lingual and occlusal surfaces can be used to establish the proper occlusion be made using a material that accurately records detail and maintains its dimensional stability for sufficient time to permit arrival at the dental lab so accurate fabrication procedures can be completed

fabrication sequence

scan of cast, scan of wax pattern, milled green-state crown, fired zirconia crown, surface colors applied.

digital technology used in dentistry

scanners, CAD software, and CAM 3D printing and milling

emergence profile

shape emerging from tissue

workflow recap

surgeon: impressions consultations planning surgery temporization referring doctor: refer patient place final restoration lab: model work planning guide fabrication temporaries final restoration to match

studies have shown:

that the quality of fit of CAD/CAM single-unit crowns, bridges, and frameworks fabricated using digital impressions is as good as, or even better than, those fabricated using conventional impressions

Digital impression

the first dental chairside CAM/DAM system was introduced in 1980's as Cerec (chairside economical restoration of esthetic ceramics) the main reasons for intraoral scanners to become popular: better, smaller, faster, design software became more user friendly, automated workflow, more restorative materials, precise fit, superior in accuracy only 5-15% of dentists use digital impression technologies (probably many labs use this even tho dentists don't). digital impressions resulted in a more time-efficient technique than conventional impressions and patients preferred the digital impression technique. also, digitally produced ceramic crowns were esthetically favored by the patients and clinicians.