Conceptual reasoning model for supporting

Conceptual reasoning model for supporting strategic planning of dental implant surgical process Anderson Luis Szejkaa,1 , Marcelo Rudekb,1, José Mauricio Perussoloc and Osiris Canciglieri Juniorb,1 a

Automation Engineering, Curitiba - Brazil. Professor, Pontifical Catholic University of Paraná - PUCPR - Brazil. c Dentist Periodontist - Curitiba - Brazil. b

Abstract. The technological evolution over the last decades brought the necessity of integration between different areas of knowledge; an example of this is the integration between the Odontology and Engineering in order to find new solutions to improve the surgical process of dental implants. This work proposes a conceptual reasoning model for supporting strategic planning of dental implant which offers support to the dentist through a three-dimensional geometric modeling of the dental arch (bone, nerves, existing teeth) allowing the realization in advance of the strategic planning of the surgical process. In this geometric modeling the reasoning system interacts with the dentist presenting the bones density, nerve location, among others features, becoming, in this way, a tool that will assist the dentist in the decision-making process. The proposed model creates an auxiliary mask that will work as a guide for locating and positioning the implants making the procedure quicker and less painful. The article’s main contributions are: i) conception and development of a computational reasoning tool that supports the process of dental implantation; ii) the interactivity in the development of surgical planning through a threedimensional geometric model of the dental arch; iii) the reduction of surgical time and the patient’s recovery time. Keywords. Implant, Imaging Process, Strategic Planning, Product Development, Reasoning Systems.

1 Introduction Since ancient times mankind has searched the improvement of its well-being and longevity through the development of means and techniques which could help in daily life and especially in the treatment of the diseases. As consequence areas of knowledge had emerged (engineering, medicine, dentistry, etc.), in order to improve the people’s quality of life through new inventions even though working individually, detached from each other. Over the years came the necessity for integration between the areas in order to 1

Master Degree of Production Engineering at Pontifical Catholic University of Paraná (PUCPR), Rua Imaculada Conceição, 1155, Prado Velho, Curitiba, CEP 80215-901, PR, Brazil; Email: [email protected]

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Professor in the Department of Production Engineering at Pontifical Catholic University of Parana (PUCPR), Rua Imaculada Conceição, 1155, Prado Velho, Curitiba, CEP 80215-901, PR, Brazil; Tel: +55 (0) 32711304; Fax: +55 (0) 32711345; E-mail: [email protected]

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Dentist Periodontist - Curitiba - Brazil, Rua Pe Anchieta, 1846 cj 402 Bigorrilho - CEP: 80.730-000PR - Brazil.

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A. L. Szejka, M. Rudek, O. Canciglieri Junior

search more efficient solutions. This search has been promoting ideological changes in the processes of conception and development of products and processes and can be considered, nowadays, as the advent of the globalization where the search for the integration and unification of the correlated areas of knowledge [7]. As a result, it has appeared the opportunity of application of the areas such as medicine, dentistry, mechanical, electrical, electronics and software engineering in the search of new results for the conception and development of products and processes [1]. In this scenario it can be highlighted the evolutionary technological process in the conception and design of dental implants. This process is characterized by the integration of different fields of knowledge through a secure planning of the whole surgical procedures [6]. However, this process requires a prior evaluation of some characteristics of arch bone that will receive the implant, such as the bone structure, the position of nerves, the dimensions of the teeth, among others. This assessment is extremely important since it can avoid errors in the surgical process that would bring harm to the patient, i.e., facial paralysis, the immediate loss of sensitivity, among others [11]. In this way, the research reported in this paper proposes a conceptual reasoning model for strategic planning that can offer support to the dental implant surgery. This conceptual model becomes an important tool assisting the dentist, in a virtual way, in the planning of the implant surgical procedures. This support happens through the 3D geometric visualization of the part of the jaw bone, the geometrical location of the nerves, the bone density, the recommended dimensions of the implants elements, the implant placement in the bone part of the jaw and mainly the planning of the surgical tools that will be used.

2 Research Methodology This research is considered practical since the studied knowledge were applied to solve a specific problem. It has a qualitative approach because it sought a deep understanding of a specific phenomenon through descriptions, comparisons and interpretations; it is exploratory as it provided greater familiarity with the problem in order to make it explicit, and finally, relating to the technical procedures it can be considered bibliographical and experimental. It is a bibliographical research because it was elaborated from already published material, consisting mainly of books, journal articles and currently available material on the Internet and experimental research in the determination of the object of study, in the selection of variables that would be capable of influencing so, in defining the ways of control and in the observation of the effects that the variables would produce in the object of study. Figure 1 illustrates the steps of the research process whose main objective was to propose conceptually a software tool that would offer support to the planning of the dental implant surgical process. Detail "A" represents the necessary knowledge regarding to the existing implant techniques and the new technologies that are being used in this process; the detail "B" shows the propose of a conceptual reasoning model to support the implant surgical process; the detail "C" presents the implementation process of the proposed conceptual model through case studies. The model was developed using the C++ platform where it can

Conceptual reasoning model for supporting strategic planning of dental implant

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develop a system that is dedicated to the image processing and files exporting. Finally, the detail "D" emphasizes the analysis of the preliminary results obtained from the comparison between the proposed model and the expected results from the experiments.

A

Background Technologies

B1 Requirements necessary for geometric modeling

Conceptual reasoning model for strategic planning of support the surgical procedure for dental implant

B

Geometric Modeling (individual and group)

C

Models implementation through case studies

D

Analysis of results

Strategic planning tools and implants

Analysis of the results of strategic planning

B1a

B1b

B1c

B1d

Figure 1 – Methodological Sequence of the Research.

3 Background Technologies One reason for the increase in the life expectancy of the world population is the technological developments in various areas of science. Thus, it can be verified that the boundaries between different areas of knowledge became increasingly tenuous allowing, in this way, a greater synergy in cooperative actions where the results are significant improvements in the people’s quality of life [1]. This phenomenon occurs, also, in dentistry and more specifically in the areas of implant surgery and prosthesis. In this manner, the dental implants came in order to replace missing teeth caused by old age, illness or accidents. This replacement, therefore, may have an aesthetic or clinic character and have been widely accepted by dentists and patients because of the positive results [8, 13, and 14]. However, the traditional surgical procedures demand great experience and skills from the dentist in order to choose since the implant type and its respective dimensions until its location in the mandible of the patients. This lack of an appropriate strategic planning can lead to high rates of functional and aesthetic failure in surgery. This framework has been transformed using techniques such as computed tomography and magnetic resonance imaging in the precise determination of the diagnosis regarding the bone condition [9]. Therefore the use of computed tomography and magnetic resonance imaging in the dental implant process made the procedure safer likewise other areas of medicine that are already using the files obtained in these techniques in the three-dimensional geometric modelling process (3D) for the

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cranial reconstruction [5]. This is possible through the file export in the DICOM (Digital Imaging and Communications in Medicine) pattern with the aim of standardize and make possible the communication of the information related to the diagnosis, to the images and data of any kind [10]. With this, the dentist can analyse with precision the images, after that will be able of planning accurately the procedures as well as determining the surgical tools that will be necessary in the implant surgical process [12].

4 Conceptual Reasoning Model for Supporting Strategic Planning of Dental Implant Surgical Procedure In the traditional surgical procedure it is made an assessment of the arch of the patient before the procedure which determines the nerves location and mechanical properties of bone structure using magnetic resonance imaging and computed tomography in a way that the dentist can define the geometric boundaries that will be used in the implant surgical process. However, this procedure is not precise and the whole process is at the discretion solely of the experience of the dentist. Based on this, this research proposes a conceptual reasoning model for strategic planning that is able to offer support to the dental implant surgical procedure as illustrated in detail “B1” of the Figure. This model aims to assist the dentist during surgery through the improvement of the surgical process (procedures and surgical instruments) and the improvement of the post-surgery patient’s recovery. So that, the idea proposed by the reasoning model is to realize the whole strategic planning of the tools that are necessary for the dental implant surgery, offering, in this way, the support to the dentist in the decision-making process of their surgical procedures. The proposed reasoning model consists of four steps, which are: • Requirements necessary for the geometric modelling (Detail B1a – Fig. 1); • Geometric modelling (individual and set - Detail B1b – Fig. 1); • Strategic Planning of the surgical tools/instruments and the implants (Detail B1c – Fig. 1); • Analysis of the results of the strategic planning (Detail B1d – Fig. 1). 4.1 Requirements Necessary for the Geometric Modelling The geometric modelling must be done through tomographic cut in DICOM format files containing digital image. The DICOM files contain the information of the digital image of the transverse cuts, axial and panoramic views of the coordinates “X,Y,Z”, of the cuts and colour tone of each cut for the appliance of the Hunsnfield Scale. The DICOM pattern is different from others image formats as JPEG,TIFF,GIF because it allows that the information related to the patients be keep together with the image in a structured way [4]. This protocol represents the standardization of a structured data form in order to interchange digital images between medicine and engineering [2], as illustrate in the right side of the figure 3. The figure presents three images in DICOM format (axial, panoramic and transverse cut views). For the reconstruction of the missing teeth it is necessary to use the re-engineering techniques by the 3D digitalization (Rapid Prototyping) for


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the generation of a geometric model in CAD (Computer Aided Design) [1] through real models or manual modelling.

REAL MODELS

DICOM FILE Axial View

Transverse Cut Views

View of Maxillary

Panoramic View

View of Jaw

Figure 3 – Requirements for geometric modelling.

4.2 Geometric Modelling Based on the information obtained in the previous phase, now it is done the modelling of the bone arch of the mandible/maxilla through tomographic cuts or magnetic resonance imaging. However, the dental lack will be modelled individually using rapid prototyping techniques in a re-engineering process of the real geometric model (figure 4). This process is fundamental since virtually it is possible to plan the precise positioning of the implant ant its accessories. In this geometric modelling it is used algorithms of image processing and artificial intelligence for the three-dimensional reconstruction through the cloud of points in order to generate the 3D models in CAD [3], as illustrated in the “individual modelling part” and “assembly modelling” of figure 5.

Porcelain tooth Implant

Figure 4 – Dental implant and the porcelain tooth.

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INDIVIDUAL PART MODELLING Real Teeth Modelling

ASSEMBLY MODELLING

Dental Arcade Modelling

Figure 5– Three-dimensional geometric modelling.

4.3 Strategic Planning of the Surgical Tools/Instruments and the Implants The strategic planning can be performed on two fronts: the first presents a logical order of the execution of the implants process activities, that is, the study of the bone structure of the arch and the nerves location, the stages of pre-drilling, drilling and threaded opening for insertion of the implant; the second is related to the planning of all surgical material/tools that will be used in the surgical process. It is in this stage that the system has a format of logical reasoning assisting the dentist in the decision-making process for the realization of the surgical planning. The Figure 6 presents the logical reasoning of the system which will help the dentist in the decision making process predicting in advance the possible problems that may occur during the surgical process. TOMOGRAPHIC IMAGE

IMPLANT TYPES

IMPLANT NORMAL SIZE

IMPLANT 25% LONGER

SURGICAL PROCESS PLANNING

Drill 5.0 mm

Drill 4.3 / 5.0 mm

Drill 4.3 mm

Drill 3.6 / 4.3 mm

Drill 3.5 mm

Drill 2.8 / 3.5 mm

Initial Drill

Drill 2.0 mm

DRILL SEQUENCE

• • • •

Operations sequence; Tools; Surgical instruments; Etc.

Diameter 3.5 mm Diameter 4.3 mm Diameter 5.0 mm

Figure 6 – The system logic. 4.4 Analysis of the Results of the Strategic Planning The final process of the reasoning model is executed in two parts, which are: the emission of a report showing chronologically and in detail each step of the surgical


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procedures with its respective tools that will be used in the process; virtual simulation of the surgical process through 3D visualization of the bone arch, geometric position of the implant and of the auxiliary mask that will be used as a guide in the processes of drilling and threading. This mask will be created virtually based in the planning generated and after can be export in a STL file to be manufactures in rapid prototyping (figure 7). Guide bushing for fixing mask at the surgical process Guide bushing for implant fixing Rapid prototyping mask

Figure 6 – Mask model (Rapid prototyping).

5 Analysis of the Results The conceptual model presents an evolution in the dental implant process as: i) reduction in the surgery total time; ii) faster recovery of patients; iii) the surgical procedure will be better planned and precise; and iv) better quality of the aesthetic results for the patients. Based in tomographic images the implants are guided through the models and has lower risk of being out of its position and especially determines the depth of the hole so avoinding reaching the nerve.This makes possible to re-create precisely the patient’s dental arch allowing a more accurate visualization of the mouth details through the data obtained by the vectorial digitalization.Thus it is possible to conceive the auxiliary mask (Figure 6)that will guide the dentist at the time of the implant incision. However, the model still has some limitations that should be objects of future scientific explorations.

6 Conclusion This article presentes a conceptual reasoning model for supporting the strategic planning of surgical dental implant procedure which provides images and characteristics of the patient dental arch aloowing the virtual visualization of the nerves in order to define precisely the dimensions of the holes for the implant insertion reduncing drastically the risk of partial or total facial paralisys. It also presented the development phases of the conceptual model illustrating its singularities in the research context. Despite the results still preliminaries it is

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already possible visualize the method potenciality by the results obtained in the sirgery planning. The authors believe that the model can be deeply explored in order to offer more autonomy to the system in the decision- making process. Therefore, several future researches themes can be proposed, for instance: • The use of genetic algorithms in order to generate systems rules searching more autonomy for the surgical planning; • Development of a expertise system for selection of implant types and surgical tools; • Development of new tools and accessories.

7 References [1]

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