Clinical performance of CEREC ceramic inlays: a systematic review

dental materials Dental Materials 15 (1999) 54–61 www.elsevier.com/locate/dental

Clinical performance of CEREC ceramic inlays: a systematic review N. Martin a,b,*, N.M. Jedynakiewicz a a

Department of Clinical Dental Sciences, The University of Liverpool, Liverpool L69 3BX, UK b Department of Clinical Engineering, The University of Liverpool, Liverpool L69 3BX, UK Received 12 October 1998; accepted 21 October 1998

Abstract Objective: This systematic review of clinical trials seeks to identify the clinical performance of intra-coronal CEREC restorations luted with an adhesive composite technique. The focus of the review is to establish the survival rate of these restorations and to identify the factors that may cause them to fail. Method: A comprehensive literature search was undertaken, spanning from the year of introduction of the technology—1986 to 1997. This review identifies universal indicators of the clinical performance of intra-coronal CEREC restorations luted with an adhesive composite technique. Throughout the critical appraisal, each individual study was analysed identifying the aims, the methodology and materials used and the results obtained. Results: 29 clinical reports were identified in the search. The systematic analysis reduced the focus of review to 15 studies. The data available establishes ceramic intra-coronal restorations machined by the CEREC system as a clinically successful restorative method with a mean survival rate of 97.4% over a period of 4.2 years. The review also highlights the reasons and the rates of failure for this type of restoration. The predominant reasons for failures are fracture of the ceramic, fracture of the supporting tooth, postoperative hypersensitivity and wear of the interface lute. Significance: Machinable ceramics, as used by the CEREC system provide a useful restoration with a high success rate. These restorations are color stable and wear at a clinically acceptable rate. Wear of the luting composite on occlusal surfaces leads to the phenomenon of submargination. Ceramic fracture, wear at the interface and post-operative hypersensitivity remain a problem which require further investigation. q 1999 Academy of Dental Materials. Published by Elsevier Science Ltd. All rights reserved. Keywords: Intra-coronal CEREC restorations; Ceramic inlays; Ceramic fracture

1. Introduction The most limiting factor in the choice of materials for dental restorations is the restricted range of fabrication technologies. The ability to fabricate a restoration outside the mouth and subsequently integrate it with the tooth extends the range of materials available to the dentist. An indirect approach also enables the possibility of further optimising the physical properties of the restoration by widening the choice of materials. Amongst the most interesting groups of materials are high-performance ceramics [1] and glass– ceramic composites [2]. The challenge of taking a block of optimised, high performance ceramic and shaping it quickly and predictably to fit the defect of a damaged tooth was the drive behind the development of computer controlled machining techniques in dentistry. The CEREC * Corresponding author. Tel.: 144-151-706-5227; fax: 144-151-7065843. E-mail address: [email protected] (N. Martin)

method (Sirona, A.G., Bensheim, Germany) for restoring teeth by CAD–CAM is now over 10 years old [3]. It is the ingenious result of a sophisticated analysis of the requirements of a dental restorative system and the application of logical problem-reduction in cavity design. In its infancy, it was limited to the fabrication of simple inlays only. From these beginnings, it has matured into a sophisticated clinical restorative method capable of creating complex ceramic restorations and full-coverage crowns at the chair side. The clinical performance of restorations machined by a CAD–CAM system, such as the CEREC method, is determined by the total ‘process chain’. Three main factors may determine this. Firstly operator variables expressed as both clinical skills and expertise with the CEREC machine. Secondly, the intrinsic limitations of hardware devices such as the data-acquisition camera and the milling unit. Finally, the software program and the design algorithms it uses will determine the accuracy of the proposed restoration design. With ever-increasing technological sophistication,

0109-5641/99/$20.00 1 0.00 q 1999 Academy of Dental Materials. Published by Elsevier Science Ltd. All rights reserved. PII: S01 09-5641(99)0001 4-7

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Table 1 Clinical studies identified, source of publication and selected studies for review Clinical studies identified in the literature Go¨tsch et al. (1990) - [8] Mo¨rmann & Curilovic (1991) - [9] Mo¨rmann & Krejci (1991) - [10] Mo¨rmann et al. (1991) - [11] Isenberg et al. (1991) - [12] Pallesen (1991) - [13] Bieniek & Peters (1991) - [14] Otto (1991) - [15] Conforti (1991) - [16] Magnuson et al. (1991) - [17] Reiss & Walther (1991) - [18] Reiss & Walther (1991) - [19] Isenberg et al. (1992) - [20] Mo¨rmann & Krejci (1992) - [21] Van Meerbeek et al. (1992) - [22] Sjo¨gren et al. (1992) - [23] Hass et al. (1992) - [25] Thordrup et al. (1994) - [26] Gladys et al. (1995) - [27] Otto (1995) - [28] Pallesen (1996) - [29] Brauner & Bieniek (1996) - [30] Sjo¨gren et al. (1997) - [31] Walther & Reiss (1996) - [32] Hass et al. (1996) - [33] Heyman et al. (1996) - [34] Cerutti (1996) - [35] Cerutti et al. (1997) - [36] Cerutti et al. (1998) - [37] Total

Journal publication

p

p p p p p p p p p p p p

13

Symposium publication p p

Abstract publication p

p p p p p p p

Repeated publications (A) b (B) a (B) a (A) b (C) b

p p

(D) b (E) b

(F) a,b (F) a,b (C) b (A) a (G) b (H) b (K) a (G) b (E) b

p p

(D) b (H) b (F) b (K) a

p p p p 13

Studies selected for review

(L) b (L) b (L) b

3

p p p

p p p p p p p p p p 15

Key to repeated publications: Repeated incidences of the same study are denoted with a bracketed block letter, e.g. (A) a Denotes that the study has been reported in different publications. b Denotes that the study has been reported at different stages of the investigation.

the hardware and software factors have become less of a limitation. Technological improvements have increased the range of restorations capable of being milled [4,5], to the extent that virtually any shape can now be made. These improvements have reduced, but not eliminated, the impact of the operator variables on the quality of the final restoration. Furthermore, the cementation and finishing process remain highly technique-sensitive clinical procedures, a factor that will greatly influence the performance of the final restoration. A wide range of parameters relating to this restorative modality has been evaluated by in-vitro and in-vivo studies. The extensive in-vitro published research that evaluates the performance of this technology and associated materials is relatively clear and conclusive. However, the same is not so for in-vivo studies. As a result of the wide range of parameters involved, it is very difficult to extrapolate the results of individual clinical studies to differing clinical scenarios. This literature review seeks to identify the clinical performance of intra-coronal CEREC restorations luted with an adhesive composite technique. The focus of the review is to

establish the survival rate of these restorations and to identify the factors that may cause them to fail.

2. Method A systematic review follows a protocol with the following stages. Identification of the focus of review, acquisition of data, selection of studies for inclusion in the review including identification of repeated reports and the establishment of the inclusion criteria, a sensitivity analysis, a critical appraisal of selected studies. A comprehensive literature search was undertaken, spanning from the year of introduction of the technology—1986 to 1997. The objective of this search was to identify all reports concerning the testing of the performance of CEREC machined inlays in controlled clinical trials. In the search, computer-data-retrieval systems were interrogated, in addition to symposium proceedings publications and reference lists of relevant publications. Throughout the critical appraisal, each individual study

Study setting

University

University

P. Practice

P. Practice

University

University

University

P. Practice

University

University University

P. Practice

University & P. Practice

University

University

Clinical studies selected for review

Mo¨rmann & Krejci (1991) - [10]

Mo¨rmann et al. (1991) - [11]

Conforti (1991) - [16]

Magnuson et al. (1991) - [17]

Isenberg et al. (1992) - [20]

Thordrup et al. (1994) - [26]

Gladys et al. (1995) - [27]

Otto (1995) - [28]

Pallesen (1996) - [29]

Brauner & Bieniek (1996) - [30] Sjo¨gren et al. (1997) - [31]

Walther & Reiss (1996) - [32]

Hass et al. (1996) - [33]

Heyman et al. (1996) - [34]

Cerutti (1998) - [37]

Table 2 Clinical studies selected for review and relevant data

7years

4years

10years

6years

6years 2years

6years

5years

3years

1year

2years

2years

20months

3years

5years

Study period

109

50

219

1011

453 66

32

100

16

15

121

301

267

94

8

Number of CEREC inlays

Direct clinical evaluation (Modified USPHS) Direct clinical evaluation (Modified USPHS)

“In-house” evaluation method

Direct clinical evaluation (USPHS) and SEM of replicas Direct clinical evaluation (Modified-USPHS) “In-house” evaluation method. Direct clinical evaluation Direct clinical evaluation (CDA). Two examiners, Bitewing radiographs Direct clinical evaluation (USPHS) Direct clinical evaluation (CDA) and bite-wing radiographs SEM of replicas and computeraided quantitative margin analysis Direct clinical evaluation, silicone impressions, bite-wing radiographs and history of symptoms. Direct clinical evaluation (Modified USPHS), silicone impressions, bite-wing radiographs and history of symptoms. “In-house” evaluation method Direct clinical evaluation (CDA). Single blind “In-house” evaluation method. Kaplan–Meier survival analysis

Evaluation criteria

0%

0%

0.45%

1.4%

0%

2.2% (0.5% Hypersensitivity, 0.7% Caries, 0.1% RCT, 0.7% tooth #, 0.2% marginal integrity) 2.9% (0.45% caries, 0.45% RCT, 1% tooth #,) 0%

5.5% (Pulpitis) 1.5% (Tooth #)

6.25% (Cement #)

3%

1.2% 1.5%

2% (RCT)

0%

0%

0%

0%

0%

1% (RCT)

0%

0%

0%

Other failures (# teeth, # cement, caries, pulpitis)

0%

5.8%

0.6%

0%

1.9%

25%

Fractured inlays

56 N. Martin, N.M. Jedynakiewicz / Dental Materials 15 (1999) 54–61

N. Martin, N.M. Jedynakiewicz / Dental Materials 15 (1999) 54–61

was carefully analysed identifying the aims, the methodology and materials used and the results obtained. The most significant results from each study were analysed as was the dependency of the results on the methodology and evaluation.

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[6,7], the problem arises when they undergo “in-house modifications” that are not disclosed to the reader. Hence, in some instances, it is not possible for the authors of this review to establish how these ratings deviate from the recognised criteria.

2.1. Inclusion criteria 3. Results The following inclusion criteria were established for the studies identified in this literature review. The clinical trials should be set out to measure the performance of CEREC machinable ceramic inlays as an intra-coronal restorative technique. They should be undertaken either in a controlled dental practice or university environment. A thorough and consistent placement and evaluation protocol should have been employed for each study, but not necessarily the same one between studies. 2.2. Sensitivity analysis This process establishes the robustness for the results relative to key decisions and assumptions that are made in the process of conducting the review. In order to establish the survival rate of CEREC restorations, it is necessary to identify a set of parameters, which either alone or in combination will deem the restoration to have failed. The chosen parameters based on accepted clinical evaluation scales [6] and [7] are as follows: restoration fracture, tooth fracture, cement fracture, new or secondary caries and irreversible pulpitis requiring RCT. The setting in which the studies are undertaken, a university hospital or a private dental practice may also affect the review process. Trials undertaken in a university hospital environment are normally conducted in accordance with fixed placement and evaluation protocols, in idealised conditions without the restrains of time and available materials. The data obtained in this manner should show the optimum performance of the restorative system. University studies are normally fixed-term studies with a defined placement and evaluation time-scale. The trials undertaken in a dental practice environment tend to be influenced by reduced clinical working-time, variation in the use of luting materials and usually the inability to adhere to a strict case selection protocol. These studies are normally longitudinal in nature, characterised by the continuous placement of restorations over an indefinite time period. The results obtained from these studies may not demonstrate the full capabilities of the CEREC restorative system, but the data obtained will be a more realistic representation of its clinical performance. In this review, the university and general practice studies are analysed separately to identify possible differences in the results. An interpretation error may arise as a result of the ambiguity with which some parameters are qualified. Specific parameters are commonly qualified with terms such as ‘excellent’, ‘good’, ‘acceptable’ etc. Whilst the majority of these ratings are based on recognised clinical criteria

A total of 29 reports on clinical trials of CEREC restorations have been identified in the search (Table 1). Of these, 13 were published in scientific journals, 13 were published in symposium proceedings and three were published as conference research abstracts. Despite the identification of 29 relevant reports, the total yield of the search was reduced to 15 (Table 2). It was found that repeated reports on the same study were published in either journals originating in different countries or between journals and symposium proceedings. In these cases, only the most thorough article was considered for inclusion in the review. The search also identified some trials reported and published at different time intervals, based upon the data obtained from a further period of evaluation. In these instances, the data from the latest and/or most complete report was selected for inclusion in the review. However, if appropriate, information on the methodology may have been obtained from a previous report. A wide range of variables was encountered amongst the studies. Some of these related to operator technique and could not be objectively evaluated. Other variables, documented in the reports could be objectively assessed. • Size of study. This ranged from 8 to 1011 restorations • Technology employed. Original CEREC or CEREC 2 depending on the start date. Restorations placed prior to 1992 are machined by the original CEREC system. • Ceramic inlay material. Dicor MGC (Dentsply-Caulk, USA); Vita I, Vita II (Vita Zahnfabrik, Bad Sackingen, Germany). • Composite lute. Microfilled light-cure posterior composites or dual-cure luting composites. • Cementation protocol. Little detail is provided in the studies regarding the precise cementation protocol and the type of adhesives used. It is assumed that the cementation protocol followed accepted clinical guidelines. • Evaluation time-scale. 6 months to 10 years. • Evaluation protocol. All studies report a thorough evaluation protocol. This was either based on the USPHS criteria, the CDA criteria or proprietary “Inhouse” criteria. Equally a range of different parameters were assessed in each trial, in accordance with the aims and objectives of the study. These included: Status of the restoration Fracture, wear and color stability. Status of the restored tooth

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Fracture, post-operative hypersensitivity and recurrent caries. Status of the interface The width and the rate of wear. The reasons for failure and their rates also vary between studies. The predominant reasons for failure are: The fracture of the ceramic and/or the supporting tooth, postoperative hypersensitivity and wear of the interface lute. 3.1. Ceramic fracture This was the most consistently evaluated parameter throughout the analysed reports. The incidence of inlay fracture for each study is shown in Table 2. Fracture of the inlay was deemed the most common reason for restoration failure. In some instances, such as the study by Sjo¨gren [31], the fracture of an inlay was confined to a small chip of the ceramic that was easily adjusted and did not compromise the functionality of the restoration. Nevertheless, the number of fractured restorations when expressed as a percentage of the total number of restored teeth in these trials is low and consistent with either excessive occlusal loads or insufficient ceramic thickness. The study by Mo¨rmann et al. [10] with a 25% failure rate is grossly inconsistent with the other studies quoted, a finding explained by the authors as being attributed to the use of experimental materials. A further finding identified by Walther and Reiss [32] is a concentration of ceramic/tooth fractures in teeth that are non-vital. 3.2. Post-operative hypersensitivity Post-operative hypersensitivity was a common occurrence in many studies and the incidence varied amongst them. However in most cases this was of short duration and all symptoms resolved within a matter of weeks or months. For example, Conforti [16] reported an incidence of 10%, Magnusson [17] reported 0.9%, Otto [28] reported 13%, Walther et al. [32] and Hass et al. [33] reported 0.5%. Brauner et al. [30], reported an incidence of pulpitis of 5.5%. Conversely, other studies such as [10,36] reported zero incidence of post-operative hypersensitivity. 3.3. Wear of cement at the interface Mo¨rmann et al. [11] and Isenberg et al. [20] reported wear rates at the interface of approximately 80 mm, which stabilised after the first year. Heyman et al. [34] reported a low wear rate of the lute and a reduction in the speed of wear after the 3rd and 4th year. Van Meerbeck et al. [22] report that the type of lute will have an effect on the rate of wear. A sub-micron luting composite shows a greater wear resistance than a macrofilled one. 3.4. Dimensions of the interface This was only reported in two of the clinical studies

[11,20]. The mean width reported was approximately 150 mm. When analysing this data, it must be noted that these restorations were milled with the original CEREC technology and early software programmes. The machining accuracy of this earlier system was inferior to later models. A predictable occlusal interface width of approximately 50 mm can now be achieved with the CEREC 2 machine and the latest software versions [39,40]. 3.5. Wear of ceramic This was not deemed as a significant clinical problem by any of the studies. 3.6. Recurrent caries A small incidence of microleakage between the lute and the tooth and recurrent caries has been reported [32,33] (Table 2). 3.7. Color stability of the ceramic This was deemed either adequate or excellent by all studies that monitored this parameter [10,20,26,29,31,36]. 3.8. Effect of study setting Of the 15 studies included in the review, only 5 studies have been undertaken in a private practice setting. These studies are longitudinal, evaluating the long-term survival rate of restorations placed at different time intervals and using varying cementation protocols. However, the reported results are comparable to those of studies undertaken in a university environment. 3.9. Survival rate Based on the data available, it is difficult to establish an accurate survival rate for this type of restoration. Clearly the data from the eight experimental restorations in the study [10] must be excluded. Disregarding this study from the calculations, the failure rate is of 2.6%, which equates to a survival rate of 97.4% over a period of 4.2 years. 4. Discussion This literature review analyses the data on the clinical performance of ceramic inlays machined by the CEREC inlay arising from a total of 2862 restorations, placed in different settings, using different placement and evaluation protocols and examined over varying time periods, by different investigators. This provides a wealth of data, on the performance of CEREC ceramic inlays in an in-vivo setting over an average period of 4.2 years. There are two established review methodologies for performing a comprehensive analysis of such data, a meta-analysis and a systematic review [38]. Meta-analysis is an analytical review technique designed

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Fig. 1. Asymptomatic fracture of an MOD CEREC Vita-I inlay at the isthmus of the occlusal surface.

to assimilate data from randomised trials, where one treatment modality is being compared to the other. A systematic review is designed to establish whether findings are consistent across populations, settings, and treatment variations, or whether findings vary significantly by particular subsets

Fig. 2. Interface wear at the occlusal surface between the enamel (left) and a CEREC Vita-I inlay (right) in a maxillary first premolar after 5 years of service. The dimension of this interface is 75 mm wide and 25 mm submarginated.

59

[41]. These review techniques are designed to limit bias and improve the reliability and accuracy of conclusions. Most of the studies identified in this particular literature search assess the performance of these restorations by monitoring a number of different parameters over time. Few of the clinical trials identified are of a comparative nature. It was therefore deemed that the most appropriate analytical technique for this review exercise would be a systematic analysis. Despite presenting the data in a summarised way, this literature review is not a summary of the clinical studies quoted. Only data common to all studies has been extracted and analysed for the purpose of this exercise. Each of the quoted studies is a valuable piece of research in its own right, with particular strengths and as such, it must not be analysed via this review. The analysis of the data from the various studies reveals that fracture of the ceramic is the primary mode of failure of CEREC inlay/onlay restorations. Most studies do not specify which inlay-material fractured, and as the majority of restoration placements occurred prior to 1992, these failures could be attributed to the use of either CEREC Vita Mark I or Dicor MGC. CEREC Vita Mark II was introduced after this date and better results can be expected from this material as it has improved physical properties [1]. An exception is the study [31], which reported that a small chip to a restoration occurred on a Vita Mark II inlay. The reasons for ceramic fracture are multi-factorial. Subsurface flaws created during machining can be a point of weakness when subjected to either high or unfavourable occlusal loads. Poor finishing and polishing of the occlusal surface will also reduce the fracture strength of the CEREC Vita Mark I and II as shown in Lu¨thy et al. [49]. Insufficient thickness of the material has been quoted in the clinical studies described, as a reason for fracture. Moreover, in most cases the authors have been able to attribute the ceramic fracture to insufficient thickness, a narrow isthmus or high occlusal loads resulting from bruxism. An example of this fracture mechanism can be seen in Fig. 1. The occurrence of ceramic/tooth fractures, identified in non-vital teeth [32], may be related to the loss of structural integrity, tooth desiccation and brittleness. A further commonly reported short-term clinical complication is post-operative thermal hypersensitivity. Thermal hypersensitivity is a well-recognised phenomenon that occurs as a post-operative complication following the placement of adhesive restorations, although the precise mechanisms involved remain less clear [43]. Some authors have attributed this to either the type of adhesive employed, the presence of occlusal interferences or the presence of bacteria and their toxins in the cavity beneath the restoration [44,45]. Another conceivable explanation of post-restorative sensitivity is the direct piezoelectric effect associated with some dental materials, especially ceramics [24,46]. This is the generation of a small electrical charge on the surface of certain anisotropic crystals when a mechanical

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stress is applied. It is evident that the problem of post-restorative sensitivity, thermal or otherwise, does not only concern the CEREC system, but all adhesive restorative methods. However, a careful cementation process with cavity disinfection and an appropriate occlusal adjustment should reduce the incidence of post-operative thermal hypersensitivity. Wear of the lute at the interface is a recognised problem with this type of restoration (Fig. 2). The rate of wear of the composite lute will depend on the structural characteristics of the material and the degree of protection afforded by the surrounding enamel and ceramic walls. Isenberg et al. [20] reported that once the depth of the lute reaches the same value as the width of the interface at that point, the rate slows down to an almost imperceptible rate as it gains protection from the high strength ceramic. The use of a thixotropic posterior composite with a high %Vol. filler concentration will further reduce the rate of wear [21,22,47,48]. The setting in which the study was performed, universityhospital or private dental practice, was noted earlier as a possible source of bias in the interpretation of the results. Despite a ratio of 2:1 between university and private practice, the results obtained from studies undertaken in either setting are comparable, with no noticeable discrepancies. In this literature review, it is not possible to extrapolate beyond the data available as to the validity of one setting against the other. However, the authors are of the opinion that this type of review becomes more robust and clinically meaningful when studies in both settings are considered in the same exercise. In doing so, the biases introduced by each type of setting are mutually limiting. That is, the ‘perfect working environment’ of a university-hospital against the more ‘realistic working environment’ of dental practice. Further, more structured studies are now required to study and analyse some of the problems that have been identified. These would include methods of avoiding post-operative hypersensitivity, optimisation of the interface and prevention of ceramic/tooth fracture. In conclusion, a number of observations can be made from the reviewed data. Machinable ceramics as used by the CEREC system, provide a useful restoration with a high success rate. These restorations are color stable and wear at a clinically acceptable rate. The wear of the luting composite on occlusal surfaces leads to the phenomenon of submargination. This wear is a noted problem, but the wear rates appear to stabilise after an initial rapid loss of material, hence it may not be of great clinical significance. Caution should be exercised when using this restorative system for the restoration of non-vital teeth, as a higher fracture incidence has been noted in this category. References [1] G. Datzmann, 1996 CEREC Vitablocs Mark II machinable ceramic, in: W.H. Mo¨rmann (Ed.), CAD/CIM in Aesthetic Dentistry, Quintessence Publishing Co, Chicago, 1996, pp. 205–216.

[2] D.G. Grossman, Structure and physical properties of Dicor/MGC Glass-ceramic, in: W.H. Mo¨rmann (Ed.), International Symposium on Computer Restorations, Quintessence Publishing Co, Berlin, 1991, pp. 103. [3] W.H. Mo¨rmann, M. Brandestini, F. Lutz, F. Barbakow, Chairside computer aided direct ceramic inlays, Quintessence International 20 (1989) 329–339. [4] W.H. Mo¨rmann, M. Brandestini, The fundamental inventive principles of CEREC CAD/CIM and other CAD/CAM methods, in: W.H. Mo¨rmann (Ed.), CAD/CIM in Aesthetic Dentistry, Quintessence Publishing Co, Chicago, 1996, pp. 81. [5] N.M. Jedynakiewicz, N. Martin, Extending the clinical scope of the CEREC system, in: W.H. Mo¨rmann (Ed.), CAD/CIM in Aesthetic Dentistry, Quintessence Publishing Co, Chicago, 1996, pp. 136. [6] Cvar, J.R., Ryge, G., 1971 Criteria for the clinical evaluation of dental restorative materials. U.S. Dept. of Health, Education and Welfare, Publication No. 79: 244. [7] CDA, Quality evaluation for dental care, 1977, Guidelines for the assessment of clinical quality and professional performance. Los Angeles, California Dental Association. [8] T. Go¨tsch, W. Mo¨rmann, I. Krejci, F. Lutz, CEREC ceramic inlays clinically assessed using modified USPHS criteria, J. Dent. Res. 69, 162 (Abs 425) (1990). [9] W. Mo¨rmann, Z. Curilovic, CEREC CAD-CAM ceramic restorations. A case report after 5 years in place, Acta Stomatol. Croat. 25 (1) (1991) 3–10. [10] W. Mo¨rmann, I. Krejci, Clinical and SEM evaluation of CEREC inlays after 5 years in situ, in: W.H. Mo¨rmann (Ed.), International Symposium on Computer Restorations, Quintessence Publishing Co, Berlin, 1991, pp. 25. [11] W. Mo¨rmann, T. Go¨tsch, I. Krejci, F. Lutz, F. Barbakow, Clinical status of 94 CEREC Ceramic inlays after 3 years in situ, in: W.H. Mo¨rmann (Ed.), International Symposium on Computer Restorations, Quintessence Publishing Co, Berlin, 1991, pp. 355. [12] B.P. Isenberg, M.E. Essig, K.F. Leinfelder, L.A. Mueninghoff, Clinical evaluation of marginal integrity: two year results, in: W.H. Mo¨rmann (Ed.), International Symposium on Computer Restorations, Quintessence Publishing Co, Berlin, 1991, pp. 163. [13] U. Pallesen, Clinical performance of CEREC-Restorations: restorative procedure and preliminary results, in: W.H. Mo¨rmann (Ed.), International Symposium on Computer Restorations, Quintessence Publishing Co, Berlin, 1991, pp. 285. [14] K.W. Bieniek, A. Peters, Clinical evaluation of ceramic restorations machined by a CAD/CAM technique, in: W.H. Mo¨rmann (Ed.), International Symposium on Computer Restorations, Quintessence Publishing Co, Berlin, 1991, pp. 327. [15] T. Otto, Clinical evaluation and experience with the CEREC-Method in a private practice after two years, in: W.H. Mo¨rmann (Ed.), International Symposium on Computer Restorations, Quintessence Publishing Co, Berlin, 1991, pp. 347. [16] G.P. Conforti, The CEREC System: twenty months of clinical practice, in: W.H. Mo¨rmann (Ed.), International Symposium on Computer Restorations, Quintessence Publishing Co, Berlin, 1991, pp. 337. [17] D. Magnuson, A. Ode´n, I. Krystek, Clinical evaluation of CEREC restorations, in: W.H. Mo¨rmann (Ed.), International Symposium on Computer Restorations, Quintessence Publishing Co, Berlin, 1991, pp. 339. [18] B. Reiss, W. Walther, Survival analysis and clinical evaluation of CEREC restorations in a private practice, in: W.H. Mo¨rmann (Ed.), International Symposium on Computer Restorations, Quintessence Publishing Co, Berlin, 1991, pp. 215. [19] B. Reiss, W. Walther, Survival rate analysis and clinical follow-up of tooth colored restorations of CEREC, ZWR 100 (5) (1991) 329–332. [20] B.P. Isenberg, M.E. Essig, K.F. Leinfelder, Three year clinical evaluation of CAD-CAM restorations, J. Esthet. Dent. 4 (5) (1992) 173–176. [21] W. Mo¨rmann, I. Krejci, Computer-designed inlays after 5 years in

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[22]

[23]

[24]

[25]

[26]

[27]

[28]

[29]

[30]

[31]

[32]

[33]

[34]

situ: Clinical performance and scanning electron microscopic evaluation, Quintessence Int. 23 (2) (1992) 109–115. B. Van Meerbeek, S. Inokoshi, G. Willems, M.J. Noack, M. Braem, P. Lambrechts, J.F. Roulet, G. Vanherle, Marginal adaptation of four tooth cooloured inlay systems in vivo, J. Dent. 20 (1) (1992) 18–26. G. Sjo¨gren, M. Bergman, M. Molin, C. Bessing, A clinical examination of ceramic (CEREC) inlays, Acta Odontol. Scand. 50 (3) (1992) 171–178. G. Sjo¨gren, M. Bergman, K. Johansson, Piezoelectricity in dental materials, a conceivable cause of postrestorative sensitivity, Acta Odontol Scand. 50 (1992) 313–319. M. Hass, G. Arnetzl, W.A. Wegscheider, K. Konig, R.O. Bratschko, Clinical results and material behaviour of composite, ceramic and gold inlays, Dtsch-Zahnarztl-Z. 47 (1) (1992) 18–22. M. Thordrup, F. Isidor, P. Ho¨rsted-Bindslev, A one-year clinical study of indirect and direct composite and ceramic inlays, Scand. J. Dent-Res. 102 (3) (1994) 186–192. S. Gladys, Van-Meerbeek, B., Inokoshi, S., Willems, G., Braem, M., Lambrechts, P., Vanherle, G., Clinical and semiquantitative marginal analysis of four tooth-colored inlay systems at 3 years, J. Dent. 23 (6) (1995) 329–338. T. Otto, CEREC restorations. CEREC inlays and onlays: The clinical results and experiences after 6 years of use in private practice, Schweiz-Monatsschr-Zahnmed 105 (8) (1995) 1039–1044. U. Pallesen, Clinical evaluation of CAD/CAM ceramic restorations: 6 year report, in: W.H. Mo¨rmann (Ed.), CAD/CIM in Aesthetic Dentistry, Quintessence Publishing Co, Chicago, 1996, pp. 241. A.W. Brauner, K.W. Bieniek, Seven years of clinical experience with the CEREC inlay system, in: W.H. Mo¨rmann (Ed.), CAD/CIM in Aesthetic Dentistry, Quintessence Publishing Co, Chicago, 1996, pp. 217. G. Sjo¨gren, M. Molin, J. Dijken, M. Bergman, Ceramic inlays (CEREC) cemented with either a dual-cured or a chemically cured composite resin luting agent, Acta Odontol. Scand. 53 (1997) 325– 337. W. Walther, B. Reiss, Six year survival analysis of CEREC restorations in a private practice, in: W.H. Mo¨rmann (Ed.), CAD/CIM in Aesthetic Dentistry, Quintessence Publishing Co, Chicago, 1996, pp. 199. M. Hass, CEREC vs. laboratory inlays, in: W.H. Mo¨rmann (Ed.), CAD/CIM in Aesthetic Dentistry, Quintessence Publishing Co, Chicago, 1996, pp. 299. H.O. Heymann, St.C. Bayne, J.R. Sturdevant, A.D. Wilder, Th. M.

[35]

[36] [37]

[38] [39]

[40] [41]

[42]

[43] [44]

[45] [46]

[47] [48]

[49]

61

Roberson, The clinical performance of CAD-CAM generated ceramic inlays (A four year study), Jada 127 (1996) 1171–1181. A. Cerutti, Valutazione clinica di intarsi eseguiti con procedura computerizzata CEREC dopo 4 anni di permanenza nel cavo orale, Quint. Int. (Edizione italiana) 3 (1996) 143–149. A. Cerutti, G. Venturi, A. Putignano, C. Prati, Six-years clinical evaluation of 109 Cad/Cam Inlays, J. Dent. Res. 76 (Abs 295) (1997). A. Cerutti, G. Venturi, P.L. Sapelli, Seven year clinical evaluation of 109 Cad/Cam inlays, J. ent. Res. 77, Special Issue B (Abs. 2249) (1998). I. Chalmers, D.G. Altman, Systematic Reviews, BMJ Publishing Group, 1996 ISBN 0-7279-0904-5. J. Schug, J. Pheiffer, B. Sener, W.H. Mo¨rmann, Schleifprazision und Passgenauigkeit von CEREC 2 inlays, Schweiz. Monatsschr. Zahnmed. 105 (1995) 913–919. W.H. Mo¨rmann, J. Shug, Grinding precision and accuracy of fit of CEREC 2 CAD-CIM inlays, JADA 128 (1997) 47–53. C.D. Mulrow, Rationale for systematic reviews, in: I. Chalmers, D.G. Altman (Eds.), Systematic reviews, BMJ Publishing Group, 1996, pp. 1. C.D. Mulrow, Rationale for systematic reviews, in: I. Chalmers, D.G. Altman (Eds.), Systematic Reviews, BMJ Publishing Group, 1996, pp. 1. H.R. Stanley, Pulpal considerations of adhesive materials, Operative Dentistry Supplement 5 (1992) 151–164. M. Bra¨nnstrom, H. Nybo¨rg, Cavity treatment with a microbiocidal fluoride solution: Growth of bacteria and effect on the pulp, Journal of Prosthetic Dentistry 30 (1973) 303–310. G. Mount, An Atlas of Glass Ionomer Cements, Martin Dunitz, London, 1990, p. 19. G. Sjo¨gren, K. Johansson, Charges extracted from dental ceramics: An indication of piezoelectric activity?, Acta Odontol Scand. 54 (3) (1996) 205–210. K. Kawai, B.P. Isenberg, K.F. Leinfelder, Effect of gap dimension on composite cement wear, Quintessence Int. 25 (1994) 53–58. T. Kershbaum, Quality assurance in Cerec restorations, in: W. Mo¨rmann (Ed.), CAD/CIM in Aesthetic Dentistry, Quintessence Publishing Co, Chicago, 1996, pp. 321. H. Lu¨thy, A. Gougoulakis, O. Loeffel, W.H. Mo¨rmann, Flexure strength of computer machined ceramics, in: W.H. Mo¨rmann (Ed.), International Symposium on Computer Restorations, Quintessance Publishing Co, Berlin, 1991, pp. 603.