WO2002042985A1

WO2002042985A1 - Analysis of longevity of patient treatment object

Info

Publication number: WO2002042985A1
Application number: PCT/FI2001/001016
Authority: WO
Inventors: Markku Larmas; Jari PÄKKILÄ
Original assignee: Oulun Yliopisto
Priority date: 2000-11-23
Filing date: 2001-11-22
Publication date: 2002-05-30
Also published as: WO2002042985A8; FI20002571A0; AU2002223718A1; EP1346308A1

Abstract

The invention relates to a method and a system for analyzing the longevity of an object to be placed in a patient for treatment purposes. The method comprises (702) placing the object in a number of patients. For controlling the treatment result, the effect of the object on different patients is then checked /704) in recurrent check-ups, and the effect is marked (706) in a computer-implemented patient data system for treatment follow-up and billing as status markings and/or treatment markings in a patient's medical record stored in the patient data system. The status markings and/or treatment markings in a patient's case record are (712) then gathered to a computer-implemented analysis system from at least one patient data system. Finally, an analysis of the longevity of the object is created (718) in the analysis system, based on the changes in the object as marked in the status markings and/or treatment markings.

Description

ANALYSIS OF LONGEVITY OF PATIENT TREATMENT OBJECT

FIELD

[0001] The invention relates to a method and a system for analyzing the longevity of an object to be placed in a patient for treatment purposes.

BACKGROUND

[0002] Various objects placed in a patient are used medically for treating patients. Such objects include dental fillings, dental implants, dental bridges, tooth crowns and tooth prostheses, used in dentistry. In medicine, following objects can be mentioned: endoprosthesis, bone screw, bone nail, prosthesis, silicone prosthesis, aortic valve, cardiac pacemaker. The object may also be some other object, placed permanently or temporarily in an animal or a human and used for treatment.

[0003] For example in dentistry, the material industry produces new filling and other materials at an increasing speed. At present, these products may be renewed even yearly. Tooth restoration materials, although placed permanently in the body, are, however, considered to be external to the body, wherefore they do not need normal medical testing before being taken into use. Nowadays, the usability of different materials is usually tested in experimental conditions of the trial type, whereby the actual usability is not known until later in normal clinical work. See P.J.B. Leemboel, M.A. Van't Hof ja F.J. De Haan: Survival studies of dental restorations: criteria, methods and analyses. Journal of Rehabilitation 1989, Volume 16, pages 387-394, which is incorporated herein by reference. Accordingly, no active follow-up system exists. [0004] The principles of clinical research include the achievement of an optimally exact, in practice multi-stage, classification for recording any failures at an early stage. Consequently, regarding dental caries, the terms used include initial caries, stagnant caries and remineralized caries. In these stages, a dentist observes if caries has progressed to a point that it necessarily has to be treated. As regards materials, for example implants, significant osteopenia may be present after the first two years, which then, however, stops. In such a long run, the implant is successful even though in a short-term scientific follow- up it would seem to have failed. See T. Albrektsson ja G.A. Zarb: Current Interpretations of the Osseointeg rated Response: Clinical Significance. The International Journal of Prosthodontics 1993, Volume 6, Number 2, pages 95- 103, incorporated herein by reference.

[0005] In practical clinical work, caries is definitely cured when a dentist fills it. See M.A. Larmas, J.I. Virtanen, R.S. Bloigu: Timing of first restorations in permanent teeth: a new system for oral health determination. Journal of Dentistry 1995, Volume 23, Number 6, pages 347-352, incorporated herein by reference. In the same way, an implant or a filling has definitely failed only at the stage when it has to be removed from the mouth. I .A. Mjδr, J.E. Dahl ja J.E. Moorhead: Age of restorations at replacement in permanent teeth in general dental practice. Acta Odontologica Scandinavica 2000, 58, pages 97-101 , incorporated herein by reference. In practice, these clinical failures differ from experimental failures.

[0006] In Europe, the regulations set on the testing of the usability of filling materials are not so strict as for example those set on pharmaceuticals, although, before a CE mark is granted, different rating institutions audit the production processes and products for toxicity, for instance. Longevity is followed up by a trial type of experimental arrangement, and a new filling material does not obtain the acceptance of e.g. the ADA (American Dental Association) until after its longevity has followed for five years using criteria accepted by the ADA. In practice, a product that has been granted ADA acceptance can have been withdrawn from the market and replaced with a new product before it even gets the acceptance.

[0007] Accordingly, the tests regarding the longevity of filling materials are of the trial type. Kaplan-Maier analytical statistical methods are often used in trial studies. Although filling materials do not have to be studied apply- ing the good clinical practice, as do pharmaceuticals, the results of large trials always take a long time and are expensive to run. Furthermore, studies of the trial type are associated with the problem of a 'calibrated researcher'. Researcher calibration means that a researcher should always be able to perform a given procedure in the same way, for instance to always fill a tooth equally well. This is almost impossible in practice, whereby the non-calibration of researchers causes an error to the trial study that is difficult to estimate.

[0008] Thus, in accordance with prior art, treatment generates statistically compiled health data, a part of which may be called a status portion, which describes the health status at a given moment, and a decursus portion, i.e. the description of the treatment as daily procedures. In dentistry, health data are nowadays compiled as single indexes representing them, such as DMF and DMFS. Similarly, research work gathers new health data by applying for example the Kaplan-Meier analysis and develops new statistical analysis and description models. Material research performs many years' trials, often multi-centre researches, for following the life span of products. Treatment and research are completely separate entities.

BRIEF DESCRIPTION

[0009] The object of the invention is to provide an improved method of analyzing the longevity of an object to be placed in a patient for treatment purposes and an improved system for analyzing the longevity of an object to be placed in a patient for treatment purposes. An aspect of the invention is a method according to claim 1 of analyzing the longevity of an object to be placed in a patient for treatment purposes. An aspect of the invention is a system according to claim 8 for analyzing the longevity of an object to be placed in a patient for treatment purposes. Other preferred embodiments of the invention are disclosed in the dependent claims.

[0010] The invention is based on following the longevity of the object, not only by a trial study, but also utilizing normal treatment of patients after the object is taken into use. At present, patient data systems are in wide use and include data relating to treatment follow-up and billing, the data includ- ing e.g. the effects caused by the object. The idea of the invention is to utilize this normally gathered data in a new manner. Data generated in treatment can thus be utilized in studying the longevity of objects. Furthermore, the problem of a calibrated researcher is solved at the same time, since any calibration error caused by the use of at most some researchers is removed as the use of some researchers is replaced by hundreds or thousands of physicians or dentists involved in the practical work, or veterinarians when animals are being treated.

[0011] For example in dentistry, real-time data regarding the longevity of filling materials is routinely obtained, and this enables a rapid reaction in order to withdraw filling materials from the market that were launched too early.

LIST OF FIGURES

[0012] The preferred embodiments of the invention are described below by way of example with reference to the attached drawings, in which:

Figure 1 shows a system for analyzing the longevity of an object to be placed in a patient for treatment purposes; Figure 2 shows the user interface of the system of Figure 1 ; Figure 3 shows status markings; Figure 4 shows simplification of status markings; Figures 5 and 6 illustrate the conduction of a survival analysis; Figure 7 is a flow diagram illustrating a method of analyzing the longevity of an object to be placed in a patient for treatment purposes.

DESCRIPTION OF THE EMBODIMENTS

[0013] A system for analyzing the longevity of an object to be placed in a patient for treatment purposes will be described with reference to Figure 1. The system comprises at least one computer-implemented patient data system 100, 102, 104 for controlling the treatment result of an object placed in a patient for treatment purposes for treatment follow-up and billing, and for storing the effect of the object on the patient. For the sake of clarity, Figure 1 only shows three patient data systems 100, 102, 104, but in practice the number of patient data systems may be extremely large, e.g. thousands or tens of thousands.

[0014] The effects of the object are preferably status markings in a patient's medical record stored in the patient data system 100, 102, 104. An increasing number of physicians are using or starting to use electronic medical records.

[0015] For instance in dentistry, there are hundreds of different globally used methods of recording dental health in digital form in dental statuses as part of a patient's treatment. All these clinically routinely used methods have in common that the status of a tooth, whether healthy, carious or filled with different filling materials, is coded in a digital form. These teeth statuses allow the follow-up of changes in dental health with a scientifically acceptable accuracy, starting from the eruption of the tooth to for instance a decision to restore it, although a 'non-calibrated', clinical dentist performs the health check-ups, provided the number of statuses to be followed is large and generated by several dentists.

[0016] In all patient data systems 100, 102, 104, the procedures carried out, often coded with the accuracy of a day, are followed for patient billing and statistics. These essential patient data markings are followed for patient billing and/or procedure statistics, and, in accordance with prior art, are not intended for scientific analysis nor used for scientific analysis.

[0017] In the system of Figure 1 , real-time follow-up of the longevity of dental fillings or other constructs placed on a single tooth and/or the surface of a tooth is performed in the decursus portion of a patient record, i.e. a treatment list describing the treatment of a patient. The follow-up includes, on the one hand, the manner in which and the time when the object has to undergo reparation and, on the other hand, when the object has to be replaced for good. Thus, the follow-up of changes in status markings and treatment markings in a single patient's medical records in the patient data system 100, 102, 104 allows the determination of the longevity of the object.

[0018] Figure 3 shows the recording of statuses. Teeth are coded in accordance with general praxis by dividing them into maxillary and mandibular teeth. Maxillary and mandibular teeth are further divided into teeth to the right and left of a midline. Seen from the front of the mouth, to the upper left is the first quadrant, to the upper right the second quadrant, to the lower right the third quadrant and to the lower left the fourth quadrant. In each quadrant, the teeth are numbered starting from the midline. That is, 1 and 2 are incisors, 3 is a canine, 4 and 5 are premolars and 6, 7 and 8 are molars. Since humans have a maximum of 32 teeth (including wisdom teeth), the last number is wisdom tooth 8. Reference can be made to a tooth using a number, formed from the quadrant and the number of the tooth. For example, 11 is the first maxillary tooth from the midline to the left, and 41 is the corresponding first mandibular tooth to the left of the midline. Table 1 shows the codes of the teeth.

Table 1

[0019] Figure 3 shows the seven teeth 11 , 12, 13, 14, 15, 16 and 17 on the left side of the upper jaw. A patient often lacks wisdom teeth, since they have either not erupted yet or been removed to avoid problems.

[0020] A tooth has four or five surfaces. Incisors and canines 11 , 12, 13 have four surfaces: a first lateral surface 302, a second lateral surface 304, a third lateral surface 306, and a fourth lateral surface 308. Back teeth 14, 15, 16, 17 have four lateral surfaces 302, 304, 306, 308 and an occlusal surface 300. Incisors and canines 11 , 12, 13 have no occlusal surface 300, but are thought to have an incisal line or point.

[0021] The horizontal axis in Figure 3 shows the status of each tooth in a check-up made at a given point in time. When no marking exists at a surface 300, 302, 304, 306, 308, such as in block 310, the tooth is healthy. All the surfaces of tooth 12, for example, are healthy in all six check-ups 0, 1 , 2, 3, 4, 5. [0022] The first filling of a tooth is the 'birth', i.e. the starting point of the follow-up, to be registered on the surface on which it is 'born', using vertical lines as shown in block 312. In a first check-up, a filling is placed on the first lateral surface 302 of tooth 11 , for example. Similarly, the occlusal surface 300 of tooth 17, for example, is provided with a filling in the first check-up. [0023] As long as the marking remains unchanged, the tooth retains its 'birth' status, i.e. its first filling, until the follow-up ends, which leads to the follow-up being 'censored'.

[0024] If the filling of a tooth is replaced with a new one, 'event V is concerned, which in the figure is shown by block 312, vertically lined, turning into a cross-lined block 314. In principle, a filling may have to be renewed more than once; in the example, the second renewal is shown by a horizontally lined block 316. The filling of the occlusal surface 300 of tooth 17, for example, is replaced for the first time with a new filling in check-up 2, and a second time with a new filling in check-up 4. [0025] If the filling of a tooth falls off, 'event 2' is concerned. In this case, the tooth returns to its cavitary state unless it is immediately refilled. In Figure 3 this is shown by the previously vertically lined or cross-lined surface becoming white. For instance, tooth 15 is filled in check-up 3, in check-up 4 the filling is still in place, but in check-up 5, the filling has fallen off. If follow-up ends in event 2, this event is marked as the censorship, which is accounted for in statistical calculations as a censored event whose follow-up period is zero.

[0026] In a preferred embodiment, these complex data recorded in dentists' status diagrams are cut down to simple event data by recording only the changes that are obtained directly from a treatment list with a day's accu- racy or from the status of a recheck-up, in the manner shown in Figure 4. The change involves e.g. the placement, replacement or end of the placement of the object in the patient. The immense amount of data recorded in successive status diagrams is thus considerably simplified. This is clearly apparent when Figures 3 and 4 are compared. Unchanged fillings are deleted from the file. Only the changes, i.e. the first filling, a refilling or the falling of a filling, are recorded. For example, the changes in tooth 17 include: the placement 400 of a filling onto the occlusal surface 300 in check-up 0, the replacement 402 of the filling on the occlusal surface 300 in check-up 2, the placement of a filling on the fourth lateral surface 308 in check-up 2, and falling 404 of the filling from the fourth lateral surface 308 in check-up 4. [0027] The only change in tooth 16 is the placement 406 of a filling on the occlusal surface 300 in check-up 3.

[0028] The changes in tooth 15 include: the placement 408 of a filling on the occlusal surface 300 in check-up 3, the falling 410 of the filling from the occlusal surface 300 in check-up 5. [0029] The only change in tooth 14 is the placement 412 of a filling on the second lateral surface 304 in check-up 3.

[0030] There are no changes in teeth 13 and 12. [0031] The changes in tooth 11 include: the placement 414 of a filling on the first lateral surface 302 in check-up 0, and the replacement 416 of the filling on the first lateral surface 302 in check-up 1.

[0032] The system of Figure 1 also comprises a computer- implemented analysis system 120 for the creation of an analysis of the longevity of the object, based on the effects. The analysis system 120 preferably uses survival analysis for analyzing the longevity of the object. In scientific studies of the trial type, the health status of the teeth and/or the time the filling materials remaining in the mouth are followed in digital form during the survival time, whereby scientific statistical methods are generally used to estimate the significance of the observed survival time differences using complex scientific software. Previously, the material had to be modified to draw survival curves, in order to enable further analysis of the material by means of the available statistical software (e.g. SAS or SPSS). These measures require programming skills and adequate control of the statistical software used. See M.K.B. Palmar: Survival Analysis - A Practical Approach, Chichester Wiley cop. 1995, incorporated herein by reference. [0033] In the system of Figure 1 , patient data on the objects used, such as filling materials, gathered in routine treatment of teeth in the decursus part of the treatment document, are included in the survival follow-up. Different filling materials in different teeth and tooth surfaces are included in survival follow-up, whereby the placement of a filling material and its replacement in the mouth are recorded from the markings in the decursus part with a day's accuracy, whereby this interval, the survival time, is automatically subjected to fol- low-up regarding each filling material, dentist and dental office.

[0034] When coupled to nationwide and continent-wide network systems, one obtains real-time information regarding the practical longevity of different filling materials from the change in the angular coefficients of survival curves drawn up from summaries of thousands of 'blind' users. All these follow-ups can be implemented at different levels of treatment (basic, special and advanced special health care) such that individual patient data are in no case identifiable.

[0035] The simplified status markings in Figure 4 can be modified tooth-specifically for treatment in the manner shown in Figure 5. Marking 520 shows The 'birth' of a filling, i.e. the first filling, marking 522 'event 1 ', i.e. the first filling, i.e. the replacement of a filling, marking 524 'event 2', i.e. the falling of a filling, and marking 526 'censorship', i.e. the end of follow-up. This modification is particularly interesting in that the duration in time of the different events is obtained. For example, the filling on the first lateral surface of tooth 17 was placed in check-up 0, and it was replaced with a new filling in check-up 2. That is, the first filling lasted for the period in time shown by time line segment 500. Similarly, a new filling was placed in check-up 2 and it was replaced with a second new filling in check-up 4. That is, the second filling lasted for the period in time shown by time line segment 502. The second new filling lasted at least the period in time shown by time line segment 504, since it was still in place at the end of the follow-up in check-up 5.

[0036] In Figure 4, time line segments 506, 508, 510, 512, 514, 516 are generated in a corresponding manner for the other teeth to show the lon- gevity of their fillings.

[0037] In Figure 6, the longevities of the fillings of each surface of each tooth are placed in the time domain. It is to be noted that the time domain is different from that of Figures 3, 4 and 5. The horizontal axis shows time, not the check-up order numbers as in Figures 3, 4 and 5. Consequently, Figure 6 directly shows for instance that the filling on the second lateral side of tooth 11 has lasted the longest.

[0038] The object of Figures 3, 4, 5 and 6 is only to illustrate the processing performed in the system. In practice, processing naturally takes place numerically by calculation, not by drawing graphs, except that for the sake of clarity, the result is displayed by drawing curves.

[0039] The system comprises means 112, 114, 116, 122, 124 for gathering the effects from the patient data system 100, 102, 104 to the analysis system 120. In Figure 1 , the patient data system 100, 102, 104 comprises an actual patient data system with a database 110, and means 112 for creating an intermediate file 114 for survival analysis, including the desired data from the data in the patient data system. The intermediate file 114 is transferred to the analysis system 120 with telecommunication means 116, e.g. using a fixed data link or a wireless data link. The required data may also be transferred by storing the intermediate file 114 in a computer memory means, and by transmitting the memory means via mail, for example, to the location of the analysis system 120, where the data is then read from the memory means to the analysis system 120. Other known ways to transfer data between two computer systems may also be used. The patient data system 100 and the analysis system 120 may also be integrated into an integrated system located in one locality, whereby data is transferred from system to system, preferably by utilizing the potential offered by the operational environments of the systems to implement data transfer as efficiently as possible, e.g. computer telecommunication ports or the different manners provided by the programming languages used.

[0040] In an embodiment, the analysis system 120 comprises tele- communication means 122 for receiving the transferred intermediate file 114. The intermediate file 114 may be modified with means 124 before storage in an intermediate file 126. Accordingly, the contents of intermediate files 114 received from all different patient data systems 100, 102, 104 are gathered to the intermediate file 126. The data in the intermediate file 126 are then subjected to an actual survival analysis using analysis software 128.

[0041] Thus, the patient data system 100, 102, 104 comprises means 112 for creating an intermediate file 114 that contains status markings and is transferred to the analysis system along a data link or using some other suitable manner. [0042] In a sense, the means 112 and the means 124 are alternative. The means 112 can modify the structure of the intermediate file 114 before it is transferred over a data link to the analysis system 120. This decreases the need for data transfer capacity. On the other hand, modification with the means 124 cannot take place until in the analysis system 120. This decreases the need to make changes in each patient data system 100, 102, 104, i.e. the data are received as they are obtained from each patient data sys- tern and modified to a suitable common data structure format used in the intermediate file 126. A solution is also feasible, wherein the functionality of the means 112 and 124 is distributed into both the patient data system 100, 102, 104 and the analysis system 120. [0043] The principle of operation is that any tooth status or procedure wherein teeth are examined and treated at given intervals is compiled as an intermediate file 126. This way an intermediate file 126 is obtained from all digital status diagrams and includes at least the following data: follow-up time, status of tooth, 'birth', events, censorship, tooth number, surface of tooth, filling material. Table 2 illustrates the structure of the intermediate file. The intermediate file 126 may also include other data, e.g. a patient's social security number and sex, location of place of treatment in the form of a municipality number, user identifier of the person (i.e. physician or dentist) performing the procedure. In a preferred embodiment, for the sake of privacy protection, the in- termediate file 126 does not comprise a patient's personal identification data. [0044] It is to be noted that even if the patient data systems 100, 102, 104 used different codes and storage forms for e.g. different filling materials, the codes can be standardized, so that the intermediate file 126 only contains one type of codes for filling materials, simplifying the analysis of the ma- terial by survival analysis.

[0045] Figure 2 illustrates the user interface of the system. At least one of the following data items can be generated by the analysis system 120 from the intermediate file 126 using survival analysis: tooth status survival time by surfaces, tooth status survival time by materials, tooth status survival time by dentists and tooth status survival time by geographical areas. The example describes the longevity of a filling material. A user uses a display 200 for selecting different parameters in a selection part 204 of the display. In the selection part 204, municipality code 564 was selected as area in field 206, class 19 as age class in field 208, both sexes as the sex in field 210, all surfaces as the surface in field 212, all materials as the filling material in field 214, and all teeth are selected in field 216. The user then presses button 218, whereby the requested survival analysis is performed. The result of the survival analysis is displayed in the curve part 202 of the display 200.

Table 2 [0046] To summarize, the analysis system 120 operates as follows:

A) The user selects the desired survival analysis type from a main menu.

B) A specification form for the cohort is opened for input of data required in the analysis.

C) An SQL query (Structured Query Language) into the intermediate file 126 is created based on the user's selections. D) The results of the search are stored in a work file.

E) The survival times and statuses required in the survival analysis are calculated by statistical units from the work file.

F) Survival analysis is performed.

G) A survival curve is drawn based on the estimates obtained from the analysis.

[0047] Steps C to G are repeated as required until all survival curves are drawn.

[0048] In the curve part, the vertical axis shows the falling rate of a filling in percent. That is, if the falling rate is 0%, all fillings are still in place, and if the falling rate is 100%, all fillings have fallen off or been replaced with new ones. The horizontal axis shows time in years. That is, a set of Kaplan-Meier curves is concerned, which enable easy interpretation of the relative qualities of filling materials. Filling material YM would seem to last best according to curve 220, which shows its longevity. According to curve 222, the second best filling material is AM. According to curve 226, the third best is filling material LC, and according to curve 224, the worst filling material is LI. When studying the curves, one may also observe other data, e.g. that after slightly over eleven years, all fillings made from filling material LI have either fallen off or been replaced.

[0049] Accordingly, in accordance with the system, new materials are tested in treatment, their longevity in research being studied by means of survival analysis. Research automatically utilizes all digital follow-up data produced by treatment, irrespective of which method was used to record the data in connection with the treatment. Although the example only illustrates the longevity of filling materials, it is apparent that the system may be used for analyzing the longevity of any object used in treatment. Thus, the innovation in the present system is to automatically convert the data gathered for health statistical and billing purposes into data providing scientific survival information with- out the original health files being modified by human resources and without a patient's personal data being visible when summary data are drawn up mechanically. Known mathematical and statistical processing methods can be implemented as a simple curve created with the Visual Basic program and showing directly the differences between different materials without, however, calcu- lating the statistical significance. It can be performed when the intermediate files are processed with present commercially available statistical software.

[0050] As was stated above, the patient data system 100, 102, 104 and the analysis system 120 are implemented in a computer, particularly as software running in the processor of a computer, whereby e.g. each function required is implemented as a separate software module. The actual patient data system 110, the means 112, 124, the analysis software 128 are thus implemented as program modules. The database of the actual patient data system 110 and the intermediate files 114, 126 are implemented with manners known to those skilled in the art, e.g. as data structures or databases. The data transfer means 116 and 122 are implemented e.g. as a combination of software and required equipment, such as a modem and a network card. The computer program may be designed to operate in a normal general-purpose personal computer, in a portable computer, in a server of a computer network or in another prior art computer. Parts of the system may also be implemented as hardware solutions, e.g. as one or more application-specific integrated circuits (ASIC) or as operational logics built from separate components. In select- ing the way to implement the means, a person skilled in the art pays attention to e.g. the required processing capacity and the production costs. Different hybrid implementations formed from software and hardware are also feasible.

[0051] A method of analyzing the longevity of an object to be placed in a patient for treatment purposes will be described next with reference to Figure 7. The method starts at block 700.

[0052] In block 702, the object is placed in a number of patients for treatment purposes.

[0053] In block 704, the effect of the object on different patients is checked in recurrent check-ups to control the treatment outcome. Then, in block 706, the effect is marked in a computer-implemented patient data system 100, 102, 104 for treatment follow-up and billing.

[0054] During the follow-up period, the procedures in blocks 702, 704, 706 can be repeated limitlessly. The repetition is shown by arrow 708, according to which the process proceeds from block 708 to block 702. Procedures 702, 704, 706 can be performed in geographically different places, e.g. in different localities, different countries, even on different continents.

[0055] In block 712, the effects are then gathered to a computer- implemented analysis system 120 from at least one patient data system 100, 102, 104. In principle, this procedure can be performed at any time, irrespective of procedures 702, 704, 706. The only prerequisite is that procedures 702, 704, 706 have already been performed on a sufficient number of patients in order for the analysis result to be reliable. Dashed-line arrow 710 shows the connection in time between blocks 706 and 712. Arrow 714 shows the recur- rence of the procedure of block 712.

[0056] Finally, in block 718, an analysis of the longevity of the object is produced in the analysis system 120, based on the effects. This procedure may take place once block 712 is executed; dashed-line arrow from block 712 to block 718 shows this dependence. The method ends at block 720. [0057] The method can be modified in accordance with the attached dependent claims. Since their contents were described above in connection with the system, the description is not repeated here.

[0058] Although the invention is described above with reference to examples according to the accompanying drawings, it is apparent that the in- vention is not limited thereto, but can be modified in a variety of ways within the scope of the inventive idea disclosed in the attached claims.

Claims

1. A method of analyzing the longevity of an object to be placed in a patient for treatment purposes, comprising:

(702) placing the object in a number of patients for treatment pur- poses;

(704) checking the effect of the object on the different patients in recurrent check-ups to control the treatment result; characterized by further comprising:

(706) marking the effect in a computer-implemented patient data system for treatment follow-up and billing as status markings and/or treatment markings in a patient's medical record stored in the patient data system;

(712) gathering the status markings and/or treatment markings in patients' medical records to a computer-implemented analysis system from at least one patient data system; and (718) creating, in the analysis system, an analysis of the longevity of the object based on changes in the object included in the status markings and/or treatment markings, such as the placement, replacement or end of the placement of the object in the patient.

2. A method as claimed in claim 1, characterized in that the object is one of the following: dental filling, dental implant, dental bridge, tooth crown, tooth prosthesis, endoprosthesis, bone screw, bone nail, prosthesis, silicone prosthesis, aortic valve, cardiac pacemaker or some other object, placed permanently or temporarily in an animal or a human and used for treatment.

3. A method as claimed in any one of the preceding claims, characterized by creating, in the patient data system, an intermediate file comprising the status markings and/or treatment markings, the file being transferred over a data link to the analysis system.

4. A method as claimed in claim 3, characterized in that, for the sake of privacy protection, the intermediate file does not comprise a patient's personal identification data.

5. A method as claimed in any one of claims 3 to 4, characterize d in that the intermediate file comprises the following data: follow-up time, status of tooth, birth, events and/or procedures, censorship, tooth number, sur- face of tooth, filling material, type of object.

6. A method as claimed in any one of the preceding claims, characterized by the analysis system generating at least one of the following data: tooth status survival time by surfaces, tooth status survival time by materials, tooth status survival time by dentists and tooth status survival time by geographical areas.

7. A method as claimed in any one of the preceding claims, characterized by the analysis system using survival analysis for analyzing the longevity of the object.

8. A system for analyzing the longevity of an object to be placed in a patient for treatment purposes, characterized in that the system com- prises: at least one computer-implemented patient data system (100, 102, 104) for checking the treatment result of the object placed in a patient for treatment purposes for the follow-up of the treatment given and for billing, and for storing the effect of the object on the patient as status markings and/or treatment markings in the patient's medical record stored in the patient data system; a computer-implemented analysis system (120) for the creation of an analysis of the longevity of the object based on changes in the object included in the status markings and/or treatment markings, such as the place- ment, replacement or end of the placement of the object in the patient; and means (112, 114, 116, 122, 124) for gathering the status markings and/or treatment markings in a patient's medical record to the computer- implemented analysis system (120) from at least one patient data system (100, 102, 104).

9. A system as claimed in claim 8, characterized in that the object is one of the following: dental filling, dental implant, dental bridge, tooth crown, tooth prosthesis, endoprosthesis, bone screw, bone nail, prosthesis, silicone prosthesis, aortic valve, cardiac pacemaker or some other object, placed permanently or temporarily in an animal or a human and used for treatment.

10. A system as claimed in any one of claims 8 to 9, character i z e d in that the patient data system (100, 102, 104) comprises means (112) for creating an intermediate file (114) that comprises the status markings and/or treatment markings and is transferred over a data link to the analysis system.

11. A system as claimed in claim 10, characterized in that, for the sake of privacy protection, the intermediate file (114, 126) does not comprise a patient's personal identification data.

12. A system as claimed in any one of claims 9 to 10, characterized in that the intermediate file (114, 126) comprises the following data: follow-up time, status of tooth, birth, events and/or procedures, censorship, tooth number, surface of tooth, filling material, type of object.

13. A system as claimed in any one of claims 8 to 12, character i z e d in that the analysis system (120) generates at least one of the following data: tooth status survival time by surfaces, tooth status survival time by materials, tooth status survival time by dentists and tooth status survival time by geographical areas.

14. A system as claimed in any one of claims 8 to 13, characterized in that the analysis system (120) uses survival analysis for analyzing the longevity of the object.