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A review of computer-aided design/computer-aided manufacture techniques for removable denture fabrication

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The aim of this review was to investigate usage of computer-aided design/computer-aided manufacture (CAD/CAM) such as milling and rapid prototyping (RP) technologies for removable denture fabrication. An electronic search was conducted in the PubMed/MEDLINE, ScienceDirect, Google Scholar, and Web of Science databases. Databases were searched from 1987 to 2014. The search was performed using a variety of keywords including CAD/CAM, complete/partial dentures, RP, rapid manufacturing, digitally designed, milled, computerized, and machined. The identified developments (in chronological order), techniques, advantages, and disadvantages of CAD/CAM and RP for removable denture fabrication are summarized. Using a variety of keywords and aiming to find the topic, 78 publications were initially searched. For the main topic, the abstract of these 78 articles were scanned, and 52 publications were selected for reading in detail. Full-text of these articles was gained and searched in detail. Totally, 40 articles that discussed the techniques, advantages, and disadvantages of CAD/ CAM and RP for removable denture fabrication and the articles were incorporated in this review. Totally, 16 of the papers summarized in the table. Following review of all relevant publications, it can be concluded that current innovations and technological developments of CAD/CAM and RP allow the digitally planning and manufacturing of removable dentures from start to finish. As a result according to the literature review CAD/CAM techniques and supportive maxillomandibular relationship transfer devices are growing fast. In the close future, fabricating removable dentures will become medical informatics instead of needing a technical staff and procedures. However the methods have several limitations for now.
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© 2016 European Journal of Dentistry | Published by Wolters Kluwer - Medknow
286
Review Article
geometry of an object while CAM software is used
for the manufacture. The CAD/CAM manufacturing
process can either include additive (RP) or
subtractive manufacturing (computer numerical
control [CNC] machining; milling). RP has been
used for industrial purposes and was developed
from CAD/CAM technology. It is used to create
INTRODUCTION
With continuous developments over several years,
present‑day technological advancements allow
the use of different systems with computer‑aided
design/computer‑aided manufacture (CAD/CAM)
technology for the fabrication of removable dentures,
including milling and rapid prototyping (RP).[1]
CAD/CAM technology refers to digital design
and manufacture. CAD software recognizes the
A review of computer‑aided design/computer‑aided
manufacture techniques for removable denture
fabrication
Mehmet Selim Bilgin1, Ebru Nur Baytaroğlu1, Ali Erdem1, Erhan Dilber1
ABSTRACT
The aim of this review was to investigate usage of computer‑aided design/computer‑aided manufacture (CAD/CAM) such
as milling and rapid prototyping (RP) technologies for removable denture fabrication. An electronic search was conducted
in the PubMed/MEDLINE, ScienceDirect, Google Scholar, and Web of Science databases. Databases were searched from
1987 to 2014. The search was performed using a variety of keywords including CAD/CAM, complete/partial dentures, RP,
rapid manufacturing, digitally designed, milled, computerized, and machined. The identied developments (in chronological
order), techniques, advantages, and disadvantages of CAD/CAM and RP for removable denture fabrication are summarized.
Using a variety of keywords and aiming to nd the topic, 78 publications were initially searched. For the main topic, the
abstract of these 78 articles were scanned, and 52 publications were selected for reading in detail. Full‑text of these articles
was gained and searched in detail. Totally, 40 articles that discussed the techniques, advantages, and disadvantages of CAD/
CAM and RP for removable denture fabrication and the articles were incorporated in this review. Totally, 16 of the papers
summarized in the table. Following review of all relevant publications, it can be concluded that current innovations and
technological developments of CAD/CAM and RP allow the digitally planning and manufacturing of removable dentures
from start to nish. As a result according to the literature review CAD/CAM techniques and supportive maxillomandibular
relationship transfer devices are growing fast. In the close future, fabricating removable dentures will become medical
informatics instead of needing a technical staff and procedures. However the methods have several limitations for now.
Key words: Computer-aided design/computer-aided manufacture, rapid prototyping, removable partial denture
Correspondence: Dr. Mehmet Selim Bilgin
Email: selim.bilgin@sifa.edu.tr
1Department of Prosthodontics, Sifa University, Izmir,
Turkiye
How to cite this article: Bilgin MS, Baytaroglu EN, Erdem A,
Dilber E. A review of computer-aided design/computer-aided
manufacture techniques for removable denture fabrication. Eur J Dent
2016;10:286-91.
DOI: 10.4103/1305-7456.178304
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Bilgin, et al.: Fabricating removable dentures with CAD/CAM – A review
European Journal of Dentistry, Vol 10 / Issue 2 / Apr-Jun 2016 287
automatically physical models from computerized
three‑dimensional (3D) data.[2,3] RP, also known as
solid freeform fabrication or layered manufacturing,
has been used for creating 3D complex models in the
eld of medicine since the 1990s and has recently
become popular for the fabrication of removable
dental prostheses.[4,5] CAD/CAM and RP have
been used for several years for the fabrication
of inlays, onlays, crowns, fixed partial dentures,
implant abutments/prostheses, and maxillofacial
prostheses.[6] Currently, not only xed restorations
but also removable dentures are manufactured
using CAD/CAM and RP.[7‑14] However, few studies
have reported on the use and effectiveness of RP for
removable denture fabrication.[4]
Subtractive manufacturing technique is based on
milling the product from a block by a CNC machine.
The CAM software automatically transfers the CAD
model into tool path for the CNC machine. This
involves computation that points the CNC milling,
including sequencing, milling tools, and tool motion
direction and magnitude. Due to the anatomical
variances of dental restoration, the milling machines
combine burs with different sizes. The accuracy of
milling is shown to be within 10 µm.[15,16]
The rst removable prosthesis based on 3D laser
lithography was manufactured by Maeda et al.[12] in 1994.
Subsequently, the removable prosthesis duplication
technique was improved using CAD/CAM with a
computerized numerical control (CNC) system and
ball‑end mills by Kawahata et al.[11] in 1997. Then, Sun
et al.[13] fabricated individual physical asks using a
3D printer.
Impressions of the edentulous maxilla and mandible
or existing dentures are subjected to laser scanning
during CAD.[11,12] Also, cone beam computed
tomography is used for the modication of previous
dentures.[7] CNC, laser lithography, and RP are used
for the CAM process.[10‑13]
AvaDent and Dentca are the two available commercial
manufacturers of removable complete dentures
with CAD/CAM, using a gadget for transferring
the maxillomandibular relation (MMR) to a digital
articulator and nalizing the dentures completely
with CAD/CAM. In the process used by AvaDent,
denture bases are milled using a subtractive technique
from prepolymerized denture resin. The Dentca
technique uses an additive process, wherein a trial
denture can be prepared, if the dentist requires, using
RP (stereolithography [SLA]) before the conventional
fabrication of a denitive prosthesis.[17‑19]
An electronic search was conducted in the
PubMed/MEDLINE (National Library of Medicine,
Washington, DC), ScienceDirect, Google Scholar,
and Web of Science databases for identifying English
articles using the following key word combinations:
“CAD/CAM and complete dentures”
“CAD/CAM and removable partial dentures
(RPDs)”
“CAD/CAM and removable dentures”
“CAD/CAM and removable prosthesis”
“RP and complete dentures”
“RP and RPDs”
“RP and removable dentures”
“RP and removable prosthesis”
“Digitally designed and removable dentures”
“Digitally designed and complete dentures”
“Digital complete dentures”
“Digital removable dentures”
“Rapid manufacturing and removable dentures”
“Milled,” “machined,” “computerized,” and
“removable dentures.”
Articles about removable dentures fabricated using
CAD/CAM and RP that were published from
1987 to 2014 were selected. These included reviews and
laboratory and clinical reports. Articles published in
non‑English languages that included identied search
terms in the title or abstract were excluded. The search
process was executed in three phases as searching
of titles, analysis of abstracts, and identication of
full‑text articles. Also, Google search was conducted
for available commercial manufacturers of CAD/CAM
prostheses and their processing techniques. The
identied developments (in chronological order),
techniques, advantages, and disadvantages of
CAD/CAM and RP for removable denture fabrication
are summarized in Table 1.
TECHNIQUES AND MATERIALS USED
FOR DENTAL COMPUTER‑AIDED
MANUFACTURE
CAM includes subtractive and additive manufacturing
techniques [Figure 1].
Early CAM systems are based on substractive method
that was relied on cutting the restoration from a
prefabricated block using burs, drills, or diamond
disks. Subtractive manufacturing includes CNC
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Bilgin, et al.: Fabricating removable dentures with CAD/CAM – A review
European Journal of Dentistry, Vol 10 / Issue 2 / Apr-Jun 2016
288
Table 1: The table of published articles about CAD/CAM techniques for removable denture fabrication from
1994 until 2015
Article Technique Summary
Maeda et al.[12] Rapid prototyping Maeda et al. manufactured the rst removable prosthesis using 3D laser lithography
Silicone was used to obtain maxillary and mandibular impressions for 3D laser scanning
and imaging using CCD cameras. Complete dentures were manufactured using rapid
prototyping (3D laser lithography) from photopolymerized composite resin material
Kawahata et al.[11] Milling Kawahata et al. improved the digitally duplication technique for
removable prostheses using CAD/CAM with a CNC system.
Duplicate dentures were fabricated from a block of wax using CNC milling
Williams et al.[20] Rapid prototyping Williams et al. used digitized molds and electronic surveying for integrating 3D models of
removable partial prosthesis frameworks and created a metal frame. They also recommended a
technique to ease the denition of the retentive regions of the teeth and equator of the RP denture
Eggbeer et al.[21] Rapid prototyping Eggbeer et al. used RP for manufacturing a sacricial model of the
prosthesis and used the investment-cast technique for casting. However,
their technique was slightly complicated and time-consuming
Bibb et al.[22] Milling and rapid
prototyping
Bibb et al. described the fabrication of a metal frame using CAD/CAM and RP in a clinical
case report. They produced prototype epoxy resin using RP, and the prototype was used
as a replacement for the wax used during conventional processing of the metal frame.
Sufcient adaptation for hard tissues and soft tissues was provided by the metal frame
Busch and Kordass[8] Milling Busch and Kordass digitally scanned edentulous models using laser and
other kind of digital scanners and digitally arranged the teeth with anatomic
measurements/averages provided by specic computer software
Sun et al.[13] Rapid prototyping Virtual asks were constructed with 3D laser scanning of maxillary and mandibular
gypsum casts, and the teeth were digitally arranged. Physical asks were constructed
using RP. Conventional laboratory steps were used for tooth insertion
Guo-Dong et al.[23] Rapid prototyping Guo-Dong et al. presented easier and more effective techniques for designing and
processing digital models of RPD frameworks. They used current commercial 3D software
for scanning plaster casts, with the scanner based on the structured light technique.
A digital model of the RPD framework was designed, and its sacricial model was fabricated
using RP. Then, the alloy framework was processed using the cast mold method
Kanazawa et al.[7] Milling Kanazawa et al. used CBCT scans of prostheses and denture teeth and digitally arranged
the teeth. The prosthesis base was fabricated from a block of acrylic resin using CNC milling,
following which the teeth were manually bonded in the holes created in the denture base
Jevremović et al.[24] Rapid prototyping Jevremović et al. studied about alloys used for fabricating prostheses using
SLM. They concluded that Co-Cr alloys did not have cytotoxic effects, while
some metals commonly resulted in side effects, mentioning that 30 alloys
showed similar characteristics used in SLM for cast alloy processing
Goodacre et al.[9] Milling Goodacre et al. scanned silicone impressions by neutral zone technique for scanning,
additionally recorded interocclusal relations, then teeth were arranged digitally. The
prosthesis base was fabricated from a block of acrylic resin using CNC milling, following
which the teeth were manually bonded in the holes created in the denture base
Inokoshi et al.[10] Rapid prototyping Inokoshi et al. scanned wax trial prostheses of 10 patients using CBCT and modied
the scanned digital prostheses using computer software. Seven prototypes were
fabricated using RP, with various modications in teeth arrangements for researching
the applicability of prototype prostheses for trial placement functions
Alifui-Segbaya
et al.[25]
Rapid prototyping They researched the effects of the corrosive function of articial saliva on cast and Co‑Cr
alloys manufactured using RP. They found that some dental alloys, including Co, Cr, and
molybdenum, can be used in the oral cavity because of their acceptable ion release levels
Yoon et al.[26] Milling The research group had tried a different approach for restoring worn articial teeth
by onlays on removable partial denture case by milling technique. The CAD CAM
blocks that they used to restore the worn teeth were lithium disilicate blocks
Yamamoto et al.[27] Milling This study mentioned that in CAD/CAM complete denture, the recesses need offset for
accurate teeth positions and the optimal offset values differ with the basal shape of articial
teeth. And revealed optimal offset values as 0.15-0.25 mm for upper left 1, 0.15 and
0.25 mm for upper left 3, 0.25 mm for upper left 4, and 0.10-0.25 mm for upper left 6
Infante et al.[28] Milling This clinical report describes the manufacture of removable complete dentures using CAD/CAM
technology. Infante et al. manufactured complete removable dentures using the AvaDent system
from PMMA resin in two appointments. Acrylic teeth were not manufactured using CAD/CAM.
The article reports that clinical records can be obtained using AMD in the rst appointment itself
Bilgin et al.[29] Milling and rapid
prototyping
This study presents a new technique of design as one set aligned articial tooth arrangement
fabricated by CAD/CAM techniques for complete dentures
3D: Three-dimensional, CCD: Charge coupled-device, CAD/CAM: Computer-aided design/computer-aided manufacture, RP: Rapid prototyping, CNC: Computerized
numerical control, RPD: Removable partial denture, CBCT: Cone beam computed tomography, SLM: Selective laser melting, Co-Cr: Cobalt-chromium,
PMMA: Polymethyl methacrylate, AMD: Anatomical measurement device
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Bilgin, et al.: Fabricating removable dentures with CAD/CAM – A review
European Journal of Dentistry, Vol 10 / Issue 2 / Apr-Jun 2016 289
machining used for the manufacture of crowns,
posts, inlays, and onlays. The subtractive production
methods include spark erosion and milling. The spark
erosion can be dened as a metal substractive process
using continuing sparks to erode material from a
metal block according to the CAD under required
conditions. Milling techniques are diamond grinding
and carbide milling which are now found together in
chairside and inLab CAD/CAM devices together and
as the latest transferred technology from manufacture
industry to dental use is laser milling, which was
announced in rst quarter of 2015. Milling techniques
are mostly dependent on the device properties such as
the dimensional approach and possibilities of working
axis: 3 spatial direction X, Y, and Z which refers to 3
axis milling devices while 3 spatial direction X, Y, Z
and tension bridge refers to 4 axis milling device, and
nally 3 spatial direction X, Y, Z, tension bridge with
milling spindle is classied as 5 axis milling device.[30]
Additive 3D printing techniques include SLA, digital
light projection (DLP), jet (PolyJet/ProJet) printing,
and direct laser metal sintering (DLMS)/selective
laser sintering (SLS).
The SLA technique uses ultraviolet (UV) laser for
layer‑by‑layer polymerization of materials. The
technique is used for the manufacture of dental
models from UV‑sensitive liquid resins. DLP uses UV
laser and visible light for polymerization and is used
for the manufacture of dental models, wax patterns,
removable partial frameworks, and provisional
restorations from visible light‑sensitive resins, wax,
and composite materials. After the material is printed,
it is cured using a light‑emitting diode light source
or lamp.[31] Also, polymethyl methacrylate (PMMA)
is used in the DLP technique.[32] Jet (PolyJet/ProJet)
printing uses a series of ink‑jet print heads and
tiny pieces of material jetted onto support material
and create each layer of the part. Then, each jetted
layer is hardened using a UV lamp, light source, or
heating. This technique is used for the manufacture
of dental models, surgical drill guides, aligners, wax
patterns, and removable frameworks from dental
resin and waxes. DLMS/SLS is a powder‑based
technique wherein high‑power laser beam hits the
powder, resulting in melt and fusion of the powder
particles. This technique is used for the manufacture
of dental models, copings, and surgical guides from
cobalt‑chrome, palladium chrome, and nylon.[31]
MANUFACTURING PROCESS
OF REMOVABLE PROSTHESIS
WITH COMPUTER‑AIDED DESIGN/
COMPUTER‑AIDED MANUFACTURE AND
RAPID PROTOTYPING
Manufacturing steps for complete dentures
First, models can be prepared using conventional
impression or intraoral digital impression. When
digital impression is considered, practitioner will
need for high speed, high density, small size,
and multifunctional device which has driven the
Figure 1: Overview of computer‑aided design/computer‑aided manufacture systems for dental use
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Bilgin, et al.: Fabricating removable dentures with CAD/CAM – A review
European Journal of Dentistry, Vol 10 / Issue 2 / Apr-Jun 2016
290
development of 3D imaging.[33] The precision of digital
impression has been studied by several researchers and
found out that use of digital models is a relatively new
technique that has an accuracy of up to 10 µm, and the
models have been found to be as reliable as traditional
stone casts.[34] Nalcaci et al.[35] found out statistically
significant differences between measurements
obtained for width of 6 anterior teeth and 12 overall
teeth using plaster and digital models; however, these
differences were not within the clinically signicant
range (~0.27–0.30 mm). Therefore, casts are scanned
using digital scanner for conventional technique.
After taking impression, the next step is making
MMR transfer during complete prosthesis fabrication
using CAD/CAM. There are three options for MMR
transfer during complete prosthesis fabrication using
CAD/CAM: The MMR can be transferred using
conventional impression and transfer techniques,
the AvaDent system kit, or the Dentca system kit.[18,19]
Two clinical appointments are required for the
manufacture of removable complete dentures using the
Avadent and Dentca systems. In the rst appointment,
impressions are recorded using special trays provided
in the AvaDent or Dentca system. Then, the jaw relation
is recorded using an anatomical measuring device.
The occlusal vertical dimension (OVD) is determined
using conventional methods. Subsequently, the centric
relation is recorded, and teeth are selected. The last
step of the rst appointment is the delivery of the nal
impression to the manufacturer (AvaDent or Dentca).
At the laboratory, the denture borders are rst dened
and marked using the system’s computer software.
Then, the teeth are virtually set, and the prosthesis
base is milled from traditional denture resin material.
A trial denture can be prepared as per the dentist’s
request.
In the second clinical appointment, the dentures are
delivered and any occlusal adjustments made. These
steps are similar to those for conventional prosthesis
delivery. Only the AvaDent technique of denture base
manufacture is not conventional.[17‑19]
Manufacturing steps for framework of partial
prosthesis
Designing of the RPD framework generally consists
of four parts as base, plate, clasp, major, and minor
connector of the framework. Every part of the RPD
framework must be done proper design and thick
value in the designing process.[23] Because of the
variety of RPD parts and their irregular forms, 3D
designing of RPD framework is taking much time and
complicated. For this reason, researchers investigated
proper CAD/CAM method and software for 3D
designing of RPD framework for many years.[20,21,36,37]
Basically, steps for manufacturing of framework
of partial prosthesis with CAD/CAM and RP are:
First, dental casts are prepared using conventional
impression method or digital impression. Casts
are scanned using digital scanner for conventional
technique. Path of insertion of the RPD is dened
digitally, and then shape of the components of the
framework is designed 3D by dentists or laboratory
technicians. Finally, digitally designed metal RPD
frameworks are produced with RP.[36]
Advantages of digital fabrication of dentures
Decreased number of appointments
Shrinkage of acrylic base caused by milling of
prepolymerized acrylic resin with an increase in
the strength and t of dentures
Decreased duration of prosthesis manipulation
Decrease in the risk of microorganism colonization
on the denture surfaces and consequent infection
Advances in standardization for clinical research
on removable prostheses
Easy reproduction of the denture and manufacture
of a trial denture using stored digital data
Superior quality control by clinicians and
technicians.[38]
Limitations and disadvantages of digital fabrication
of dentures
Manufacturing challenge caused by
impression‑taking and OVD‑recording procedures,
MMR transfer, and maintenance of lip support,
which are all similar to the procedures used in the
conventional process
Inability to dene the mandibular occlusal plane
Expensive materials and increased laboratory cost
compared with those for conventional methods
Lack of trial denture manufacture by the Avadent
system,[18] which precludes the evaluation of
dentures by patients and dentists before final
denture fabrication.
CONCLUSIONS
Since the fabrication of the rst modern removable
dentures using PMMA, no significant changes in
fabricating techniques were introduced until
CAD/CAM techniques came into the picture in the
1990s. Current innovations and developments in
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Bilgin, et al.: Fabricating removable dentures with CAD/CAM – A review
European Journal of Dentistry, Vol 10 / Issue 2 / Apr-Jun 2016 291
dental technology allow the fabrication of removal
dentures using CAD/CAM technologies from start
to nish, thus decreasing the chair side and working
time for patients and dentists and providing superior
or satisfactory functional and esthetic outcomes. The
development of a digital face simulator using imaging
techniques with lower effective doses of radiation in
the close future will be another milestone for removable
denture fabrication with digital OVD recording and
MMR transfer before nalization with CAM.
Financial support and sponsorship
Nil.
Conicts of interest
There are no conicts of interest.
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... Digital production techniques are divided into two main groups: subtractive (computerized numerical control milling) and additive (3D printing) manufacturing. 11 In the subtractive technique, the prosthesis is milled from a pre-polymerized acrylic resin block using milling machines, while in the additive technique, un-polymerized light-curable resin is 3D-printed and polymerized by a light source after the digital manufacturing step. 12 For all production techniques, polymethylmethacrylate (PMMA) is usually the material of choice for removable prosthetic appliances, including feeding plates. ...
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Purpose: Feeding plates for cleft palate patients have been used by clinicians for many years to temporarily close the oro-nasal communication until definitive treatment with surgical techniques. The current in vitro study aimed to evaluate the adaptation of the feeding plates manufactured by two different techniques for three cleft types. Materials and Methods: Feeding plates were manufactured with conventional compression molding (CM) and 3-dimensional (3D) additive manufacturing on main models representing bilateral cleft, unilateral right, and unilateral left cleft types (n = 10). The 3D volumetric space between the feeding plate and the corresponding main model was measured by micro-CT to evaluate the adaptation. The adaptation of the plates was assessed based on three different measurement regions: anterior, left, and right. Repeated measure analysis of variance (ANOVA), three factorial ANOVA, and post hoc Bonferroni tests were used as statistical analysis (α = 0.05). Results: CM groups showed higher volumetric space measurements between the base and master model than 3D groups regardless of measurement region and cleft type, which refers to misfit (p ˂ 0.05). Cleft type differed in the adaptation of 3D groups yet not in CM groups (p ˂ 0.05). The volumetric space evaluation for the right measurement region resulted in higher values regardless of manufacturing method and cleft type (p ˂ 0.05). Conclusion: Considering that 3D-printed feeding plates showed better adaptation compared to conventionally manufactured plates for all cleft types, 3D printing can be suggested as the manufacturing method of choice for feeding plates.
... The CAD software distinguishes the geometry of the item whereas CAM software is utilized to manufacture it. The CAD/CAM procedure may be either additive (RP) rapid prototyping or subtractive manufacturing (computer numerical control [CNC] machining; milling) 18 . ...
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The aim: To explore the effect of different bar clip materials (plastic, poly ether ether ketone (PEEK), and zirconia) on retention force with PEEK bar in implant supported mandibular overdenture using the universal testing machine. Materials and methods: A heat-cured acrylic educational model was constructed and to implants were inserted at the canine region bilaterally. A milled PEEK bar was constructed and screwed to the multiunit abutment which were screwed to the implants. Three different clip materials groups (plastic, PEEK, and zirconia) were constructed. The clips were picked up in the intaglio surface of each denture. Three wrought wires were attached to the overdenture polished surface and connected to each other at the overdenture geometric center. The retention force of each attachment was measured at T0 (insertion) followed by T1 at 360 (3 months), T2 at 720 (6 months), T3 at 1440 (one year), T4 at 2880 (2 years) and T5 at 4320 (3 years) insertion and removal cycles simulating 36 months of usage. Results: A statistically significant difference was found between clip materials at all insertion and removal cycles. The final mean retention force of the zirconia clip group was significantly lower compared to the plastic and PEEK clip groups at T5 simulating 3-year usage. Conclusion: Within the limitations of this study, it can be concluded that the PEEK and plastic clip materials showed significantly higher retention values compared to zirconia clip materials when used with PEEK bar-retained mandibular implant-supported overdentures after a three-year simulation of overdenture use. Although the retention loss was unavoidable in the three clip materials, the rate of retention loss differed depending on the clip material. KEY WORDS: Implant overdenture, bar attachment, clip material, retention. (474) Mohamed Hosny Selem, et al.
... 1,2 Milling removes material from a preformed block until the required geometrical form is achieved, while 3D printing creates the prosthesis by depositing the material layer-by-layer. 3 CAD-CAM denture bases have been reported to be clinically acceptable because they are made from materials with optimal physical properties, the process is time efficient, and the denture design can be stored. 2,4 However, a significant concern of denture base materials is microbial adhesion and plaque accumulation, because this can lead to denture stomatitis and increased risk of systemic infection. ...
... Despite this, digital technologies have proven effective in producing one-piece RPDs, especially those made of PEEK [25]. Lastly, for measuring RPD framework fit, digital superimposition was found to be as successful as high-resolution microcomputed tomography, with gap widths lying within clinically acceptable ranges [24,38]. Overall, the choice of RPD fabrication technology is critical to fit correctness, with digital approaches showing promise but still requiring improvement in multiple domains. ...
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Objectives: The aim of this study was to compare the accuracy, reproducibility, efficacy and effectiveness of measurements obtained using digital models with those obtained using plaster models. Materials and Methods: A total of 20 digital models were produced by the Ortho Three-dimensional Models (O3DM) Laboratory and their software (O3DM version 2) was used to obtain measurements. Identical plaster models were used to obtain measurements of teeth with a vernier caliper. The maximum mesiodistal width of each study model, from first molar to first molar, was measured. All measurements were repeated at least 1 month later by the same operator for both digital and manual methods. The data were analyzed using Cronbach α, Wilcoxon signed rank test and the McNemar test. Results: Cronbach α value of the data at T1 and T2 for 6 anterior and 12 overall teeth measured using the two methods was very close to the ideal value of 1, indicating high intra-observer reliability. The Wilcoxon signed rank test showed statistically significant differences between the two methods (P = 0.000, P < 0.001). The measurements obtained using the digital models were lower than those obtained using the plaster models. No statistically significant differences were found between the two methods for anterior Bolton discrepancies (P = 0.375) or overall Bolton discrepancies (P = 0.00). Paired comparisons of repeated measurements for Bolton ratios showed no statistically significant differences for anterior or overall Bolton discrepancies (P = 0.688 and P = 0.375, respectively). Conclusions: Use of O3DM software is an acceptable alternative to the traditional vernier caliper method in orthodontic practice.
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Imaging is one of the most important tools for orthodontists to evaluate and record size and form of craniofacial structures. Orthodontists routinely use 2-dimensional (2D) static imaging techniques, but deepness of structures cannot be obtained and localized with 2D imaging. Three-dimensional (3D) imaging has been developed in the early of 1990's and has gained a precious place in dentistry, especially in orthodontics. The aims of this literature review are to summarize the current state of the 3D imaging techniques and to evaluate the applications in orthodontics.
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The CAD/CAM technology associated with rapid prototyping (RP) is already widely used in the fabrication of all-ceramic fixed prostheses and in the biomedical area; however, the use of this technology for the manufacture of metal frames for removable dentures is new. This work reports the results of a literature review conducted on the use of CAD/CAM and RP in the manufacture of removable partial dentures.
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Conventional complete denture prosthetics require several appointments to register the maxillomandibular relationship and evaluate the esthetics. The fabrication of milled complete dental prostheses with digital scanning technology may decrease the number of appointments. The step-by-step method necessary to obtain impressions, maxillomandibular relation records, and anterior tooth position with an anatomic measuring device is described. The technique allows the generation of a virtual denture, which is milled to exact specifications without the use of conventional stone casts, flasking, or processing techniques.
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Rapid prototyping is a fast-developing technique that might play a significant role in the eventual replacement of plaster dental models. The aim of this study was to investigate the accuracy and reproducibility of physical dental models reconstructed from digital data by several rapid prototyping techniques. Twelve mandibular and maxillary conventional plaster models from randomly chosen subjects were selected and served as the gold standard. The plaster models were scanned to form high-resolution 3-dimensional surface models in .stl files. These files were converted into physical models using 3 rapid prototyping techniques: digital light processing, jetted photopolymer, and 3-dimensional printing. Linear measurements on the plaster models were compared with linear measurements on the rapid prototyping models. One observer measured the height and width of the clinical crowns of all teeth (first molar to first molar) on all models (plaster and replicas) using a digital caliper. All models were measured 5 times with a 2-week interval between measurements. The intraobserver agreement was high (intraclass correlation coefficient >0.94). The mean systematic differences for the measurements of the height of the clinical crowns were -0.02 mm for the jetted photopolymer models, 0.04 mm for the digital light processing models, and 0.25 mm for the 3-dimensional printing models. For the width of the teeth, the mean systematic differences were -0.08 mm for the jetted photopolymer models, -0.05 mm for the digital light processing models, and -0.05 mm for the 3-dimensional printing models. Dental models reconstructed by the tested rapid prototyping techniques are considered clinically acceptable in terms of accuracy and reproducibility and might be appropriate for selected applications in orthodontics.