SCREW SHAPED DENTAL IMPLANTS ANALYSIS TOOL

Transcription

1 SCREW SHAPED DENTAL IMPLANTS ANALYSIS TOOL Dan-Maniu DUŞE 1 and Alexandru PAŞA 1 ABSTRACT: The goal of the current analysis is to identify the classification criteria of the screw shaped dental implants, in the context of an over-crowded dental implant market, from the implant systems number and diversity point of view. The selection will be made based on both own developed criteria and already existing ones, depending on their relevance for the implantologists, the patients and for others who want to get relevant information about screw shaped dental implants (teachers, technicians, students, engineers, PhD students etc.). KEY WORDS: dental implants, screw, analysis, tool. 1 INTRODUCTION The choosing of the right dental implant model and system is difficult for both medic and patient. Also, because the design of a new dental implant system is based on the analysis of the current systems on the market, the criteria used to analyse these systems must cover both the implants mechanical functionality and their interaction with the biological environment. Because the most frequently used dental implants today are the screw shaped endosseous ones, this study will focus on them. The following article is intended as an analysis tool, which will facilitate the classification and identification of the above mentioned dental implants. 2 CLASSIFICATION CRITERIA The analysed criteria will be presented next, as well as the reasoning by which they were chosen. Each criterion will be graded with numbers between one and five (1 being the lowest grade and 5 the highest). After the selection of the relevant criteria, a case study, which will demonstrate the generated tool s applicability, will be developed. The prior screw shaped dental implants classifications, according to contained the following criteria: - implant material; - implant surface treatment; - type of healing (one stage, two stage); - implant body shape; - implant length; - implant diameter; 1 Universitatea Lucian Blaga din Sibiu, Str. Emil Cioran, No.4, Sibiu, , România dan-maniu.duse@ulbsibiu.ro; pasa.alexandru@yahoo.com - implant-abutment connection; - implant surface covering material; - implant surface texturing procedure; - implant neck texture; - apex geometry; The internet is presently an important information media, and, as expected, dental implants classification sites emerged. The criteria present on some of these sites are: - producer name; - implant-abutment connection type; - implant body shape; - whether the implant presents a thread or not; - thread shape; - implant surface material; - implant neck geometry; - apex geometry; - implant material; - implant platform colour; - implant image; - implant lengths; - implant diameter; - implant x-rays. According to personal considerations, the following criteria, deemed as relevant, will be analysed: - producer name and logo next to the producer s name, his logo is recommended, in order not to mix-up the different manufacturers because of the similar names the companies might be registered under; - country of origin in order to form an opinion about the producer s implant system development capabilities, and to get an idea about the implant cost (the implant costs differ from one county to the next, dependent on the country s economical development status), the company s HQ location must be specified; - implant image according to Edgar Dale s cone of learning, after a couple of month of 32

2 receiving the information, people generally remember (Figure 1): Figure 1. Edgar Dale s cone of learning - implant system number of parts dependent on the number of parts, the force distribution in the implant and support bone differs, as well as the insertion procedure. A 2-piece implant is more flexible, allowing the mounting of both straight and angulated abutments, their indexation and their extra oral machining (compared to the one piece implants which require intra oral abutment machining). However, taking the opposite analysis direction, the two piece implants have bigger diameters and are more expensive than the one piece implants; - minimum and maximum implant diameters by using 3D scanning of the future implant support bone, the implantologist calculates the space available for the implant insertion. As such, results the implant maximum diameter limit. If the value he is looking for fits the available intervals, he can then browse the producers catalogues for the exact available diameters; - minimum and maximum implant lengths as stated at the previous criterion, the implantologist calculates the available insertion space, including the implant length. It is the more important to know the available implant lengths, as the vertical bone augmentation is a difficult procedure, with variable results; - implant body shape it supplies information regarding the initial stability of the implant (most conical/tapered implants generate bone condensation as they are inserted); the masticatory stresses distribution pattern in both the implant and support bone, from an engineering point of view, the conical shape generates lower stresses in both implant and bone, than the cylindrical one; - implant material the implant material determines both the implant s mechanical resistance and its biocompatibility (titanium alloys might contain elements which release ions in the biological environment); - implant surface cover material responsible for the time and quality of osseointegration; - implant surface texturing procedure not only the material, but also the texture of the implant s surface directly affects the osseointegration. Moreover, the texturing procedure indicates the possibility of potentially harmful substances leftovers, as a result of the texturing process (ex.: acids, as a result of acid etching); - implant collar texture it determines the type of insertion (the collar can be buried in the bone mass when rough, or in contact with the gingiva when smooth) and has a direct impact on bone resorption (its geometry determines the value of the stresses in the bone crest); - thread dimensions variation (constant or variable) it is an important piece of information from the initial stability point of view. No matter of the direction of the dimensions variation, this thread will generate a superior initial stability, compared to the constant dimensions thread, due to the bone condensing process; - thread shape in the axial section depending on its shape in the axial section, the thread behaves differently under the loads it is subjected to; - thread step depending on the thread step, stresses are distributed differently in the bone mass. As a result, a large step is recommended for softer bone types and a small step is recommended for harder bone types. - apex geometry it is mostly traumatologically relevant. A domed or tapered apex will have a lower traumatological effect on the maxilla/mandible bone and the mandible nerve than a flat or sharp one. Also, if the apex presents cutting edges, this means a shorter implantation protocol time less chair time for the patient; - implant-abutment contact surface determines the type of positioning of the abutment, but also the stresses distribution in the implant. A planar contact surface will result in the fixing of three degrees of freedom (DOF) of the abutment, as a conical one will fix five DOF and determine the self-centering of the abutment. There are also irregular contact surfaces, the DOF fixed depending on their shape. The following notations will be ACADEMIC JOURNAL OF MANUFACTURING ENGINEERING, VOL. 8, ISSUE 2/

3 used for the current criterion: i-interior connection and e-exterior connection; - implant-abutment indexer geometry it is relevant from both the dental technician s and implantologist s point of view, as it determines the number of positions the abutment can be placed in (especially useful for angled abutments); - bone type for which the implant is recommended the usefulness of this criterion is obvious, each bone type requiring a different thread shape and thread step value, in order to optimise the stress distribution in the bone mass; - implant price the price is of great importance for both patient and medic, it being an important factor in the calculation of the implantation procedure fee - BDIZ EDI (The European Association of Dental Implantologists) published in this matter a price guidebook for all implantation procedures; - system market position this criterion could offer information about the implant system s efficiency, if judged after the number of parts sold; - implantation protocol obviously relevant for the implantologist. It is also relevant for the patient in order for him/her to determine the extent of the traumatological effect of the implantation procedure, as stated at the apex geometry criterion; Crt. No. Table 1. Criteria analysis Criterion name Patients Implantologists Third parties (engineers) Total 1 Implantation type It is up to the medic and dependent on the patient s available bone. 3 Notes Implant body shape Implant surface cover material Implant surface texturing procedure Implant collar texture Producer name and logo Country of origin Implant image Implant system number of parts Minimum and maximum implant diameters Minimum and maximum implant lengths Thread dimensions variation (constant or variable) Thread shape in axial section Apex geometry Implant-abutment contact surface Implant-abutment indexer geometry Bone type for which the implant is recommended Implant price System market position Trainings offered by the manufacturer Implantation protocol Thread step Implant material trainings offered by the manufacturer all big dental implant manufacturers offer training programs to the doctors who want to acquire their implant systems. These trainings are most 34

4 useful for novice implantologists and for those who have no other training alternatives. In order to fully describe the main characteristics of all dental implant systems, a large number of criteria are needed. Therefore, this study intends to sum up all common traits of most of the existing implant systems. In order to increase the tool s accuracy, and to make sure no important feature of an implant system is left out, a new criterion will be added: a Notes section. Here the analyst will be able to note the distinctive traits (competitive advantage) of all dental implants. To the criteria described above, grades from 1 to 5 have been assigned, depending on their importance, from the analysts point of view. The analysis has been conducted by Prof. PhD. Eng. Dan-Maniu Duşe, Prof. PhD. MD. Bernard Broos and PhD. student Eng Alexandru Paşa, from the implantologist s, the patient s and the implant development engineer s points of view (Table 1) 3 INTERPRETATION OF THE ANALYSIS RESULTS By analysing the above results, the following conclusions are formulated: - the Bone type for which the implant system is recommended is generally dependent on the implant s Thread step. Because it is easier for the medic to interpret the bone type than the thread step, this criterion will be ruled out; - the Implant price varies according to the market stability, political climate, competition etc. However, an estimation of the implant price can be made dependant on the country where the producer has the HQ. As consequence, this criterion will be eliminated from the classification; - the dental implant market is dominated by the 4 biggest producers, the market position of the other producers having little relevance in the current classification. In consequence, the System market position criterion will also be discarded; - the Implantation protocol approximation derives from the Apex geometry. Therefore the implantation protocol will be removed from the classification; - the Trainings offered by the manufacturer criterion will be discarded because of the low score it received in the analysis. In conclusion, the criteria which will be used to create the dental implants analysis tool are presented in Table 2. Table 2. Endosseous screw shaped dental implants analysis tool criteria The original elements brought forth by the created tool are: - Producer logo; - Producer country of origin; - The improvement of the presentation of the implant s diameters and lengths; - The variation of the thread s dimensions; - The bone type for which the implant system is recommended; - Notes criterion which supplements the lack of any other classification criterion. Compared to the other dental implants classifications, the current study presents a more detailed approach from the number and relevance of the criteria point of view. 4 CASE STUDY In order to demonstrate the applicability of this tool, a comparison of the first two most representative implants, of the four biggest dental implants producers in the world, will be conducted. According to figure 2, the four are: Nobel Biocare, Straumann, Biomet-3i and Astra Tech. As stated before, and results from the graphic, they control more than half of the world s dental implant market. Figure 2. World s biggest dental implant producers ACADEMIC JOURNAL OF MANUFACTURING ENGINEERING, VOL. 8, ISSUE 2/

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7 5 CONCLUDING REMARKS The analysis of the 8 implant systems was realized by valuing the implant s universality, from the bone type criterion point of view. Thus result the points awarded for each implant in the Bone type for which the implant is recommended column. As a result of the developed analysis, Nobel Active generated the highest score, followed by Straumann Bone Level (2 nd place) and by Straumann Tapered Effect tied with Nano Tite Prevail Tapered (3 rd place). The criteria resulted from the analysis can be used by implantologists to determine the treatment plan for their patients. The only difference would be in the choosing of the analysed implants: the medic will choose only the implants compatible with the patient s bone type (ex.: for soft bone, the implantologist will choose implants with a large thread step / recommended for this type of bone). From the patient s point of view, he/she can get information about the current implant systems. After the analysis of the desired implants, he/she can choose certain producers/implant systems, depending on the analysed implants score, on which to consult the implantologist. From the development engineer s point of view, this tool can be used to determine the current status of the dental implant systems (strength, weaknesses, development opportunities, current implant designs, materials etc.), in order to plan, in collaboration with the implantologist, the future dental implant design directions. The usefulness of the presented tool is directly proportional to the user s experience in the field of dental implants. 6 REFERENCES Braceras, Braceras I., Ipiñazar E., De Maeztu M.A., Alava J.I., Risk analysis and implants, Medical Engineering & Physics, No.30, pp , ( ); Bratu, Emil Bratu, Implantologie orala si restaurari protetice cu sprijin implantar. Curs pentru studentii anului VI. 2nd ed. LITO U.M.F. Victor Babes ; Popa, C., Berce, P. (2006), Titanium-based composite for medical applications of rapid prototyping, Academic Journal of Manufacturing Engineering, vol.4 nr.2/2006. Elias, Elias Carlos Nelson a.o., Relationship between surface properties (roughness, wettability and morphology) of titanium and dental implant removal torque, Journal Of The Mechanical Behavior Of Biomedical Materials pp , ( ); Eraslan, Eraslan Oğuz, İnan Özgür, The effect of thread design on stress distribution in a solid screw implant: a 3D finite element analysis, Clinical Oral Investigations, ( ); Igić, Igić Aleksandar, Pavlović Ratko, Steas Antoan, Igić Stevan, Biomechanical analysis of forces and moments generated in the mandible, Medicine and Biology, Vol.8, No. 1, pp.39-45; Johnstone, Greg Johnstone, 2010 Dental Implant Procedure - Advantages and Success Rate - ( ) Jokstad, Asbjorn Jokstad 2009 Osseointegration and Dental Implants, Wiley- Blackwell Publishing; Laine, Laine Pekka, Salo Antero, Kontio Risto, Ylijoki Seija, Lindqvist Christian, Suuronen Riitta, 2005 Failed dental implants clinical, radiological and bacteriological findings in 17 patients, Journal of Cranio-Maxillofacial Surgery, No.33, pp , ( ); Mihai, Augustin Mihai and others, Implantele endoosoase osteointegrate in stomatologie, Editura Sylvi, Bucuresti; Paterson, Paterson Heather, Zamanian Kamran, 2009 The global dental implant market to experience strong growth despite the economic downturn, Implant practice, Vol. 2 No.4, ( ); Reynders, Reynders Reint, Ronchi Laura, Bipat Shandra, Mini-implants in orthodontics: A systematic review of the literature, American Journal of Orthodontics and Dentofacial Orthopedics Volume 135, No.5, pp , ( ); *** Marktübersicht Systeme und Oberflächen - Wissenschaft & Praxis - No. 1 February 2009 ( ); *** - ( ); *** - ( ); *** - ( ); *** - ( ); *** - ( ). 38