CAD/CAM systems available for the fabrication of crown and bridge restorations

Digital Dentistry — 3D Printing Applications

Three-dimensional (3D) printing is an additive manufacturing method in which a 3D item is formed by laying down successive layers of material. 3D printers are machines that produce representations of objects either planned with a CAD program or scanned with a 3D scanner. Printing is a method for replicating text and pictures, typically with ink on paper. We can print different dental pieces using different methods such as selective laser sintering (SLS), stereolithography, fused deposition modeling, and laminated object manufacturing. The materials are certified for printing individual impression trays, orthodontic models, gingiva mask, and different prosthetic objects. The material can reach a flexural strength of more than 80 MPa. 3D printing takes the effectiveness of digital projects to the production phase. Dental laboratories are able to produce crowns, bridges, stone models, and various orthodontic appliances by methods that combine oral scanning, 3D printing, and CAD/CAM design. Modern 3D printing has been used for the development of prototypes for several years, and it has begun to find its use in the world of manufacturing. Digital technology and 3D printing have significantly elevated the rate of success in dental implantology using custom surgical guides and improving the quality and accuracy of dental work.

Investigation of accuracy and reproducibility of abutment position by intraoral scanners

PURPOSE

We examined the accuracy, including trueness and precision, of the intraoral scanners comparing with laboratory scanner to reveal the error level of intraoral scanners.

METHODS

Measurements were performed using a computer numerical control coordinate measuring machine (CNCCMM) of the reference models as a control. Subsequently, intraoral scanners and a laboratory scanner were used for measurements of the reference trueness and precision of the distance were evaluated by image analyzing software.

RESULTS

With regard to reference model, there was a significant difference between in the trueness measured by C.O.S. (COS) and that measured by the other scanners. The trueness measured by the second-generation 3M™ true definition scanner (TDS2) and third-generation 3M™ true definition scanner (TDS3) was bigger than the one by TRIOS (TR) and KaVo (KA). With regard to reference model "B," error of the trueness measured by COS was significantly bigger, compared with the one measured by the other scanners. However, error range of intraoral scanners, except for COS, was considerably small and it should be covered with cement space.

CONCLUSIONS

The results of this study indicated that an optical impression method with an intraoral scanner could be applied to the implant therapy for multiple teeth missing.

3D printing in dentistry

3D printing has been hailed as a disruptive technology which will change manufacturing. Used in aerospace, defence, art and design, 3D printing is becoming a subject of great interest in surgery. The technology has a particular resonance with dentistry, and with advances in 3D imaging and modelling technologies such as cone beam computed tomography and intraoral scanning, and with the relatively long history of the use of CAD CAM technologies in dentistry, it will become of increasing importance. Uses of 3D printing include the production of drill guides for dental implants, the production of physical models for prosthodontics, orthodontics and surgery, the manufacture of dental, craniomaxillofacial and orthopaedic implants, and the fabrication of copings and frameworks for implant and dental restorations. This paper reviews the types of 3D printing technologies available and their various applications in dentistry and in maxillofacial surgery.

Advances in polymeric materials for dental applications

This review focuses on the relationship between the structures and properties of various polymers for different applications in dentistry.

Influence of Thermal Cycling on Flexural Properties and Simulated Wear of Computer-aided Design/Computer-aided Manufacturing Resin Composites

OBJECTIVE

The purpose of this study was to evaluate the influence of thermal cycling on the flexural properties and simulated wear of computer-aided design/computer-aided manufacturing (CAD/CAM) resin composites.

METHODS

The six CAD/CAM resin composites used in this study were 1) Lava Ultimate CAD/CAM Restorative (LU); 2) Paradigm MZ100 (PM); 3) CERASMART (CS); 4) Shofu Block HC (SB); 5) KATANA AVENCIA Block (KA); and 6) VITA ENAMIC (VE). Specimens were divided randomly into two groups, one of which was stored in distilled water for 24 hours, and the other of which was subjected to 10,000 thermal cycles. For each material, 15 specimens from each group were used to determine the flexural strength and modulus according to ISO 6872, and 20 specimens from each group were used to examine wear using a localized wear simulation model. The test materials were subjected to a wear challenge of 400,000 cycles in a Leinfelder-Suzuki device (Alabama machine). The materials were placed in custom-cylinder stainless steel fixtures, and simulated localized wear was generated using a stainless steel ball bearing (r=2.387 mm) antagonist in a water slurry of polymethyl methacrylate beads. Simulated wear was determined using a noncontact profilometer (Proscan 2100) with Proscan and AnSur 3D software.

RESULTS

The two-way analysis of variance of flexural properties and simulated wear of CAD/CAM resin composites revealed that material type and thermal cycling had a significant influence (p<0.05), but there was no significant interaction (p>0.05) between the two factors. The flexural properties and maximum depth of wear facets of CAD/CAM resin composite were different (p<0.05) depending on the material, and their values were influenced (p>0.05) by thermal cycling, except in the case of VE. The volume losses in wear facets on LU, PM, and SB after 10,000 thermal cycles were significantly higher (p<0.05) than those after 24 hours of water storage, unlike CS, KA, and VE.

CONCLUSION

The results of this study indicate that the flexural properties and simulated wear of CAD/CAM resin composites are different depending on the material. In addition, the flexural properties and simulated wear of CAD/CAM resin composites are influenced by thermal cycling.

Fracture toughness of chairside CAD/CAM materials - Alternative loading approach for compact tension test

OBJECTIVE

This in-vitro study determined plane-strain fracture toughness (KIC) of five different chairside CAD/CAM materials used for crown fabrication, following alternative innovative loading approach of compact tension test specimens.

METHODS

Rectangular-shaped specimens were cut from CAD/CAM blocks (n=10): Vita Mark II (Vident) (VMII); Lava-Ultimate (3M/ESPE) (LU); Vita Enamic (Vident) (VE); IPS e.max CAD (Ivoclar Vivadent); crystallized and un-crystallized (E-max and E-max-U, respectively); and Celtra Duo (Dentsply) fired and unfired (CD and CD-U, respectively). Specimens were notched with thin diamond disk prior to testing. Instead of applying tensile loading through drilled holes, a specially-made wedge-shaped steel loading-bar was used to apply compressive load at the notch area in Instron universal testing machine. The bar engaged the top ¼ of the notch before compressive load was applied at a cross-head speed of 0.5mm/min. Fracture load was recorded and KIC calculated. Data was statistically-analyzed with one-way ANOVA at 95% confidence level and Tukey's tests.

RESULTS

Means and SDs of KIC in MPam(1/2) for VMII, LU, VE, E-max, E-max-U, CD and CD-U were: 0.73 (0.13), 0.85 (0.21), 1.02 (0.19), 1.88 (0.62), 0.81 (0.25), 2.65 (0.32) and 1.01 (0.15), respectively. ANOVA revealed significant difference among the groups (p<0.001). CD and E-max had significantly highest mean KIC values.

SIGNIFICANCE

Mean KIC values of the tested materials varied considerably, however, none of them reached mean KIC of dentin (3.08MPam(1/2)) previously reported. For E-max and CD, specimens firing significantly increased mean KIC. The modified test arrangement was found to be easy to follow and simplified specimen preparation process.

Effect of different adhesive strategies on microtensile bond strength of computer aided design/computer aided manufacturing blocks bonded to dentin

Background:

The aim of this study was to determine the microtensile bond strength (μTBS) of ceramic and composite computer aided design-computer aided manufacturing (CAD-CAM) blocks bonded to dentin using different adhesive strategies.

Materials and Methods:

In this in vitro study, 30 crowns of sound freshly extracted human molars were sectioned horizontally 3 mm above the cementoenamel junction to produce flat dentin surfaces. Ceramic and composite CAD/CAM blocks, size 14, were sectioned into slices of 3 mm thick. Before bonding, CAD/CAM block surfaces were treated according to the manufacturer's instructions. Groups were created based on the adhesive strategy used: Group 1 (GI) - conventional resin cement + total-etch adhesive system, Group 2 (GII) - conventional resin cement + self-etch adhesive system, and Group 3 (GIII) - self-adhesive resin cement with no adhesive. Bonded specimens were stored in 100% humidity for 24h at 37΀C, and then sectioned with a slow-speed diamond saw to obtain 1 mm × 1 mm × 6 mm microsticks. Microtensile testing was then conducted using a microtensile tester. μTBS values were expressed in MPa and analyzed by one-way ANOVA with post hoc (Tukey) test at the 5% significance level.

Results:

Mean values and standard deviations of μTBS (MPa) were 17.68 (±2.71) for GI/ceramic; 17.62 (±3.99) for GI/composite; 13.61 (±6.92) for GII/composite; 12.22 (±4.24) for GII/ceramic; 7.47 (±2.29) for GIII/composite; and 6.48 (±3.10) for GIII/ceramic; ANOVA indicated significant differences among the adhesive modality and block interaction (P < 0.05), and no significant differences among blocks only, except between GI and GII/ceramic. Bond strength of GIII was consistently lower (P < 0.05) than GI and GII groups, regardless the block used.

Conclusion:

Cementation of CAD/CAM restorations, either composite or ceramic, can be significantly affected by different adhesive strategies used.

Comparison of intraoral scanning and conventional impression techniques using 3-dimensional superimposition

PURPOSE

The aim of this study is to evaluate the appropriate impression technique by analyzing the superimposition of 3D digital model for evaluating accuracy of conventional impression technique and digital impression.

MATERIALS AND METHODS

Twenty-four patients who had no periodontitis or temporomandibular joint disease were selected for analysis. As a reference model, digital impressions with a digital impression system were performed. As a test models, for conventional impression dual-arch and full-arch, impression techniques utilizing addition type polyvinylsiloxane for fabrication of cast were applied. 3D laser scanner is used for scanning the cast. Each 3 pairs for 25 STL datasets were imported into the inspection software. The three-dimensional differences were illustrated in a color-coded map. For three-dimensional quantitative analysis, 4 specified contact locations(buccal and lingual cusps of second premolar and molar) were established. For twodimensional quantitative analysis, the sectioning from buccal cusp to lingual cusp of second premolar and molar were acquired depending on the tooth axis.

RESULTS

In color-coded map, the biggest difference between intraoral scanning and dual-arch impression was seen (P<.05). In three-dimensional analysis, the biggest difference was seen between intraoral scanning and dual-arch impression and the smallest difference was seen between dual-arch and full-arch impression.

CONCLUSION

The two- and three-dimensional deviations between intraoral scanner and dual-arch impression was bigger than full-arch and dual-arch impression (P<.05). The second premolar showed significantly bigger three-dimensional deviations than the second molar in the three-dimensional deviations (P>.05).

Comparison of Conventional Methods and Laser-Assisted Rapid Prototyping for Manufacturing Fixed Dental Prostheses: An In Vitro Study

This study assessed whether there are differences in marginal fit between laser-fusion and conventional techniques to produce fixed dental prostheses (FDPs). A master steel die with 2 abutments was produced to receive a posterior 4-unit FDPs and single copings. These experimental models were divided into three groups (n = 20/group) manufactured: group 1, Ni-Cr alloy, with a lost-wax casting technique; group 2, Co-Cr alloy, with selective laser melting (SLM); and group 3, yttria-tetragonal zirconia polycrystal (Y-TZP), with a milling system. All specimens were cut along the longitudinal axis and their adaptation was measured at the marginal and shoulder areas on the right and left sides of each abutment. Measurements were made using a stereomicroscope (×60 magnification) and a scanning electron microscope (×800 magnification). The data were analyzed using one-way analysis of variance and the Bonferroni post hoc test, with a significance cutoff of 5%. Significant differences (P < 0.05) were observed between group 3 and the other groups. The marginal opening was smallest with Co-Cr alloy substructures, while the shoulder opening was smallest with Ni-Cr alloy substructures. Within the limitations of this study, the marginal fit of an FDP is better with rapid prototyping (RP) via SLM than conventional manufacturing systems.

First clinical experiences with CAD/CAM-fabricated PMMA-based fixed dental prostheses as long-term temporaries

OBJECTIVE

The clinical performance of polymethylmethacrylate (PMMA)-based fixed dental prostheses (FDP) was evaluated in the indication of long-term temporaries.

MATERIALS AND METHODS

In the current indication of the applied machinable PMMA-based material (Vita CAD-Temp), i.e. temporary crowns and FDPs, 27 patients with compromised dentitions (uncertain dental prognosis or postponement of a removable treatment option) were recruited and 45 FDPs (3 or 4 units, 37 terminal-retained, 8 cantilevered) were inserted. Frameworks were computer-aided design (CAD)/computer-aided manufacturing (CAM)-manufactured after conventional impression taking and labside scanning of stone master casts. A resin-modified hybrid cement material (RelyX Unicem) was used for luting in a conventional protocol. Clinical follow-up was performed biannually.

RESULTS

Over an observation time from 2 to 26 months (median 13 months), 11 complications were found in 9 out of 45 PMMA restorations: 4 losses of retention, 5 complete fractures; two of these subsequent to a trepanation for endodontic treatment. Thereby, 3 out of 8 cantilevered FDPs had to be removed within 8 months. Thus, the statistical evaluation included FDPs with abutment at end, only. These standard design FDPs (n = 37) showed a 90.4 % survival rate with a complication-free rate of 88.3 % estimated for an observation time of 16 months.

CONCLUSION

Cantilevered FDPs and reconstructions on abutment teeth with markedly reduced biological prognosis or endodontic intervention yielded a high-failure rate. Terminal-retained FDPs performed clinically well in cases without compromised abutment teeth.

CLINICAL RELEVANCE

PMMA-based material might be used successfully for long-term temporization with 3- to 4-unit FDPs in a standard design over at least one year.

Predictable Restorative Work Flow for Computer-Aided Design/Computer-Aided Manufacture-Fabricated Ceramic Veneers Utilizing a Virtual Smile Design Principle

The purpose of this case report was to present the use of a contemporary digital photograph-assisted virtual smile design principle, an intraoral digital impression, and computer-aided design/computer-aided manufacture-fabricated lithium disilicate ceramic veneers to treat a patient with esthetic needs in the maxillary anterior region. By using the proposed digital restorative work flow, this case report demonstrated an effective communication pathway between the patient, clinician, and dental laboratory technician. Effective communication can help to achieve a more predictable and satisfactory esthetic outcome.

Internal fit of pressed and computer-aided design/computer-aided manufacturing ceramic crowns made from digital and conventional impressions

STATEMENT OF PROBLEM

No studies have evaluated the internal adaptation of pressed and milled ceramic crowns made from digital impressions.

PURPOSE

The purpose of this in vitro study was to evaluate the internal fit of pressed and milled ceramic crowns made from digital and conventional impressions.

MATERIAL AND METHODS

Thirty polyvinyl siloxane (PVS) impressions and 30 Lava COS impressions made of a prepared dentoform tooth (master die) were fabricated. Thirty crowns were pressed in lithium disilicate (IPS e.max Press), and 30 crowns were milled from lithium disilicate blocks (IPS e.max CAD) (15/impression technique) with the E4D scanner and milling engine. The master die and the intaglio of the crowns were digitized with a 3-dimensional laser coordinate measurement machine. The digital master die and intaglio of each crown were merged. The distance between the die and the intaglio surface of the crown was measured at 3 standardized points. One-way ANOVA was used for statistical analysis (α=.05).

RESULTS

One-way ANOVA revealed that the internal gap obtained from the Lava/press group (0.211 mm, ±SD 0.041) was significantly greater than that obtained from the other groups (P<.001), while no significant differences were found among PVS/press (0.111 mm ±SD 0.047), PVS/CAD/CAM (0.116 mm ±SD 0.02), and Lava/CAD/CAM (0.145 mm ±SD 0.024).

CONCLUSIONS

The combination of the digital impression and pressed crown produced the least accurate internal fit.

The introduction of digital dental technology into BDS curricula

The aim of this study was to determine the degree to which digital dental technologies have been introduced into the curricula of UK dental schools. A survey was carried out of all the UK dental schools that teach undergraduate dental students. The survey contained six questions and was designed to determine if digital dental technology techniques or systems were being taught in the curricula, what these techniques were, and whether the school dental laboratories supported these techniques. Sixteen schools were surveyed and 11 replied: a response rate of 69%. Forty-five percent of the schools that replied did not teach digital dental technology in their curriculum. Of the 55% of schools who did teach digital dental technology, 50% gave lectures or demonstrations while the other 50% allowed practical involvement by the student. Two thirds of these stated that not all the students participated in practical usage. Seventy-three percent of the schools that replied had dental laboratories using some, but not all the digital dental technology techniques listed. Eighty percent of the schools that were not teaching digital dental technology said it was because it was not included in the curriculum, and 20% stated it was due to a lack of technical expertise or support.

In vitro evaluation of the internal and marginal misfit of CAD/CAM zirconia copings

STATEMENT OF PROBLEM

The constant updating of computer-aided design/computer-aided manufacture (CAD/CAM) systems and the introduction of new systems confirm the need for scientific evidence on internal and marginal adaptation.

PURPOSE

The purpose of this in vitro study was to measure and compare the degree of internal and marginal misfits of zirconia single-unit copings made by using 3 different CAD/CAM systems (Ceramill, Lava 3M, and Neoshape).

MATERIAL AND METHODS

Twenty-four anatomic prefabricated abutments (Neodent) were used to fabricate zirconia copings in Ceramill (n=8), Lava (n=8), and Neoshape (n=8). All copings were cemented and cut with a precision cutting machine to obtain 5 surfaces (mesial, distal, buccal, palatal, and incisal) and angle regions (internal axiogingival and axioincisal angles). Measurements were obtained from images at a magnification of ×100 and ×200 made with a digital camera attached to an optical microscope and adapted with a measuring device. The data were statistically analyzed with the 2-way ANOVA and Tukey honestly significant difference tests (α=.05).

RESULTS

In the internal misfit evaluation, the mean values observed for Ceramill, Lava, and Neoshape were palatal surface 76.5, 65.5, and 77.7 μm (P=.003); angle regions 69.4, 68.6, and 74.5 μm (P=.010); incisal surface 127.7, 97.2, and 182.2 μm (P<.001); and overall mean 72.1, 69.4, and 76.4 μm (P=.003). Significant differences were not found for mesial, distal, or buccal surfaces (P>.05). In the evaluation of marginal misfit (marginal discrepancy and absolute marginal discrepancy), the mean values found were 40.9 and 65.8 μm for Ceramill, 34.2 and 70.0 μm for Lava, and 39.3 and 74.5 μm for Neoshape. No significant differences were found among the 3 systems (P>.05).

CONCLUSIONS

Although the Lava system showed a significantly lower value of internal misfit than the Neoshape system, all systems showed clinically acceptable marginal misfit values.

Revolutionizing restorative dentistry: an overview

The field of science and research is ever changing and the scientific discipline of prosthodontics is no exception. The practice of prosthodontics and the supporting technology involved has evolved tremendously from the traditional to the contemporary. As a result of continual developments in technology, new methods of production and new treatment concepts may be expected. Clinicians must have certain basic knowledge if they are to benefit from these new procedures. This article reviews the contemporary trends in the field of prosthodontics and provides an insight into what one might expect in the near future.

Resin-composite blocks for dental CAD/CAM applications

Advances in digital impression technology and manufacturing processes have led to a dramatic paradigm shift in dentistry and to the widespread use of computer-aided design/computer-aided manufacturing (CAD/CAM) in the fabrication of indirect dental restorations. Research and development in materials suitable for CAD/CAM applications are currently the most active field in dental materials. Two classes of materials are used in the production of CAD/CAM restorations: glass-ceramics/ceramics and resin composites. While glass-ceramics/ceramics have overall superior mechanical and esthetic properties, resin-composite materials may offer significant advantages related to their machinability and intra-oral reparability. This review summarizes recent developments in resin-composite materials for CAD/CAM applications, focusing on both commercial and experimental materials.

An esthetics rehabilitation with computer-aided design/ computer-aided manufacturing technology

AIM

This paper describes a case of a rehabilitation involving Computer Aided Design/Computer Aided Manufacturing (CAD-CAM) system in implant supported and dental supported prostheses using zirconia as framework.

BACKGROUND

The CAD-CAM technology has developed considerably over last few years, becoming a reality in dental practice. Among the widely used systems are the systems based on zirconia which demonstrate important physical and mechanical properties of high strength, adequate fracture toughness, biocompatibility and esthetics, and are indicated for unitary prosthetic restorations and posterior and anterior framework.

CASE DESCRIPTION

All the modeling was performed by using CAD-CAM system and prostheses were cemented using resin cement best suited for each situation.

CONCLUSION

The rehabilitation of the maxillary arch using zirconia framework demonstrated satisfactory esthetic and functional results after a 12-month control and revealed no biological and technical complications.

CLINICAL SIGNIFICANCE

This article shows the important of use technology CAD/CAM in the manufacture of dental prosthesis and implant-supported.

Trends in computer-aided manufacturing in prosthodontics: a review of the available streams

In prosthodontics, conventional methods of fabrication of oral and facial prostheses have been considered the gold standard for many years. The development of computer-aided manufacturing and the medical application of this industrial technology have provided an alternative way of fabricating oral and facial prostheses. This narrative review aims to evaluate the different streams of computer-aided manufacturing in prosthodontics. To date, there are two streams: the subtractive and the additive approaches. The differences reside in the processing protocols, materials used, and their respective accuracy. In general, there is a tendency for the subtractive method to provide more homogeneous objects with acceptable accuracy that may be more suitable for the production of intraoral prostheses where high occlusal forces are anticipated. Additive manufacturing methods have the ability to produce large workpieces with significant surface variation and competitive accuracy. Such advantages make them ideal for the fabrication of facial prostheses.

Comparison of the accuracy of digitally fabricated polyurethane model and conventional gypsum model

PURPOSE

The accuracy of a gypsum model (GM), which was taken using a conventional silicone impression technique, was compared with that of a polyurethane model (PM), which was taken using an iTero™ digital impression system.

MATERIALS AND METHODS

The maxillary first molar artificial tooth was selected as the reference tooth. The GMs were fabricated through a silicone impression of a reference tooth, and PMs were fabricated by a digital impression (n=9, in each group). The reference tooth and experimental models were scanned using a 3 shape convince™ scan system. Each GM and PM image was superimposed on the registered reference model (RM) and 2D images were obtained. The discrepancies of the points registered on the superimposed images were measured and defined as GM-RM group and PM-RM group. Statistical analysis was performed using a Student's T-test (α=0.05).

RESULTS

A comparison of the absolute value of the discrepancy revealed a significant difference between the two groups only at the occlusal surface. The GM group showed a smaller mean discrepancy than the PM group. Significant differences in the GM-RM group and PM-RM group were observed in the margins (point a and f), mesial mid-axial wall (point b) and occlusal surfaces (point c and d).

CONCLUSION

Under the conditions examined, the digitally fabricated polyurethane model showed a tendency for a reduced size in the margin than the reference tooth. The conventional gypsum model showed a smaller discrepancy on the occlusal surface than the polyurethane model.

Flexural strength and microstructure of two lithium disilicate glass ceramics for CAD/CAM restoration in the dental clinic

OBJECTIVES

There has been a growing interest in glass ceramic systems with good esthetics, high fracture resistance and bonding durability, and simplified fabrication techniques using CAD/CAM. The aim of this study is to compare flexural strength before and after heat treatment of two lithium disilicate CAD/CAM blocks, IPS e.max CAD (Ivoclar Vivadent) and Rosetta SM (Hass), and to observe their crystalline structures.

MATERIALS AND METHODS

Biaxial flexural strength was tested according to ISO 6872 with 20 disc form specimens sliced from each block before and after heat treatment. Also, the crystalline structures were observed using field-emission scanning microscopy (FE-SEM, Hitachi) and x-ray diffraction (XRD, Rigaku) analysis. The mean values of the biaxial flexural strength were analyzed by the Mann-Whitney U test at a significance level of p = 0.05.

RESULTS

There were no statistically significant differences in flexural strength between IPS e.max CAD and Rosetta SM either before heat treatment or after heat treatment. For both ceramics, the initial flexural strength greatly increased after heat treatment, with significant differences (p < 0.05). The FE-SEM images presented similar patterns of crystalline structure in the two ceramics. In the XRD analysis, they also had similar patterns, presenting high peak positions corresponding to the standard lithium metasilicate and lithium disilicate at each stage of heat treatment.

CONCLUSIONS

IPS e.max CAD and Rosetta SM showed no significant differences in flexural strength. They had a similar crystalline pattern and molecular composition.

Rationale for the use of CAD/CAM technology in implant prosthodontics

Despite the predictable longevity of implant prosthesis, there is an ongoing interest to continue to improve implant prosthodontic treatment and outcomes. One of the developments is the application of computer-aided design and computer-aided manufacturing (CAD/CAM) to produce implant abutments and frameworks from metal or ceramic materials. The aim of this narrative review is to critically evaluate the rationale of CAD/CAM utilization for implant prosthodontics. To date, CAD/CAM allows simplified production of precise and durable implant components. The precision of fit has been proven in several laboratory experiments and has been attributed to the design of implants. Milling also facilitates component fabrication from durable and aesthetic materials. With further development, it is expected that the CAD/CAM protocol will be further simplified. Although compelling clinical evidence supporting the superiority of CAD/CAM implant restorations is still lacking, it is envisioned that CAD/CAM may become the main stream for implant component fabrication.

Implant-supported fixed dental prostheses with CAD/CAM-fabricated porcelain crown and zirconia-based framework

Recently, fixed dental prostheses (FDPs) with a hybrid structure of CAD/CAM porcelain crowns adhered to a CAD/CAM zirconia framework (PAZ) have been developed. The aim of this report was to describe the clinical application of a newly developed implant-supported FDP fabrication system, which uses PAZ, and to evaluate the outcome after a maximum application period of 36 months. Implants were placed in three patients with edentulous areas in either the maxilla or mandible. After the implant fixtures had successfully integrated with bone, gold-platinum alloy or zirconia custom abutments were first fabricated. Zirconia framework wax-up was performed on the custom abutments, and the CAD/CAM zirconia framework was prepared using the CAD/CAM system. Next, wax-up was performed on working models for porcelain crown fabrication, and CAD/CAM porcelain crowns were fabricated. The CAD/CAM zirconia frameworks and CAD/CAM porcelain crowns were bonded using adhesive resin cement, and the PAZ was cemented. Cementation of the implant superstructure improved the esthetics and masticatory efficiency in all patients. No undesirable outcomes, such as superstructure chipping, stomatognathic dysfunction, or periimplant bone resorption, were observed in any of the patients. PAZ may be a potential solution for ceramic-related clinical problems such as chipping and fracture and associated complicated repair procedures in implant-supported FDPs.

Digitization and its futuristic approach in prosthodontics

Digitization has become part and parcel of the contemporary prosthodontics with the probability of most of the procedures being based on the digital techniques in near future. Let us think of X-rays or photographs, making impressions, recording jaw movements or fabricating prosthesis, educating and training new dentists or patient motivation for practice build up, all has become digital. CAD-CAM has revolutionized not just the ceramic technology but has also been used for the CAD-CAM implant surgeries, maxillofacial prosthesis and diagnostic splints. Today a practicing dentist needs to be abreast with the latest but with the technology changing so fast, this poses a great challenge. There is endless scope of digitisation and technology in prosthodontics- let it be in the clinical and lab procedures like use of CAD-CAM technology, stereolithography, rapid prototyping, use of virtual articulators and digital face bows, digital radiographs, or in the field of training, education and research by the use of virtual patient programs, dental softwares, optoelectronic recording of jaw motion, digital instron machine, retention testing device, audiovisual aids,… the list will remain endless. The article reviews those various aspects of prosthodontics where digitization has modified the conventional procedures. For discussion they have been considered under the educational aspect, diagnostics, treatment procedures, prosthesis fabrication and lastly the research and futuristic development. The day is not far when remote sensing robotic devices would be performing the restorations under the command and surveillance of the master-the dentist without his immediate presence.