the framework, mainly relies on the theoretical knowledge and operation experience of doctors and technicians and lacks the technical stability and objective standards, which is apt to generate errors in the production process, resulting in a series of problems such as the mist of the framework, casting failure, and materials waste.

which the insertion path of the framework can be adjusted and undercut areas of the abutment, presented by the color strips on the right side, will change accordingly, which can assist in the selection of the most suitable insertion path that will be indicated by the blue arrow (Fig. 4.40). After determining the path of insertion, undercuts will be blocked out automatically using red wax (Fig.4.41), and some wax in retentive areas, where the tip of the retentive arm of the clasp contact with the abutment (Fig.4.42), should be removed, leaving appro­priate depth of the undercut.

(a) Net formability. There’re almost no wasted metal

powders, and unused materials can be recycled.

(b) Superior design and geometric exibility. Enable

producing a complex 3D design and geometries,

(b) Low cost of the equipment and effectively combining

the advantages of the high accuracy of 3D printing and the low cost of casting.

To compare the average production time of traditional and digital frameworks, 20 metal frameworks are selected as samples, each of which is fabricated in three ways, the traditional, the semi-digital, and the digital, and the cost time of every step is recorded and summarized respec­tively by the same experienced technician. Results are shown in the following table. The average fabrication time of single framework is 4.12h, 10.56h, and 20.85h, for the semi-digital process, traditional process, and digi­tal process, respectively (Fig.4.46).

Thus, the advantages of digital RPD are as details:

(a) Repeatability: Conducive to the quality control of

prostheses and standardized management of the clinic and laboratory.

(b) Predictability: Facilitating communication among

(h) Materials: There’re only two main kinds of digital

dental alloys for printed RPDs, Co-Cr alloy and Ti alloy, needing to develop more kinds of metal powders.

(i) Cost At present, most of the equipment and materials

are imported, and the cost of the whole digital process is relatively high. It’s necessary to develop equipment

(d) Process integration: Facilitating the integration of

each link and avoiding errors in the information

transmission. (e) Efciency improvement: Streamlining operations (f) Environmentally friendly Computer-aided design and

ing the traditional process of waxing up, investing,

process, done through the computer, including the evaluation of the patient’s anatomy physiology, the design of the prosthesis, the impression of arches, and the precise production of the prosthesis, making the prosthesis a perfect work of art. With the continu­ous development of new materials and technologies, the aim is to optimize the digital operation and to reduce the cost, developing from powder spray to no powder spray, from rough to precise, from complex to intelligent, from slow to fast, from manual to auto­matic, from big to small, and from more to less.

Case-based reasoning (CBR) is an important reasoning method in the eld of articial intelligence. It gives the solving process and result of the new problem through the retrieval and match of previous cases. Rule-based reason­ing (RBR) system, also known as a production system, connects rules in series through logical relations and draws the required conclusions through logical derivation. Combination of RBR and CBR, playing their respective advantages, uses rules to guide case retrieval and to achieve the goal that the cases should be as few as possible and as relevant, similar or matching as possible to the target cases.