Biomedical subjects

Werner H Mörmann

Publications and source records attributed to Werner H Mörmann.

9 recordsLinked to original sources

PubMed2006

The evolution of the CEREC system.

BACKGROUND AND OVERVIEW: Early in 1980, the author anticipated the attraction of restoring posterior teeth with tooth-colored material. He conducted studies and developed the clinical concept of bonded ceramic inlays, at the same time raising the issue of the fast fabrication of the ceramic restorations. The author developed plans for in-office computer-aided design/computer-aided manufacturing (CAD/CAM) fabrication of ceramic restorations specifically to enable the dentist to complete one or multiple ceramic restorations chairside, in a single appointment. The initial concept comprised a small mobile CAD/CAM unit integrating a computer, keyboard, trackball, foot pedal and optoelectronic mouth camera as input devices, a monitor and a machining compartment. CEREC 3 (Sirona Dental Systems GmbH, Bensheim, Germany) divided the system into an acquisition/design unit and a separate machining unit. Three-dimensional software makes the handling illustrative and easy both in the office and in the laboratory. CONCLUSIONS: It appears that the CEREC CAD/CAM concept is becoming a significant part of dentistry. CLINICAL IMPLICATIONS: Sound knowledge of adhesive bonding and diligent planning are essential for the successful integration of CAD/CAM into clinical dental offices.

Ceramics↗

PubMed2006

The bonding area of intra- and extra-coronal tooth preparations.

PURPOSE: To assess the accuracy of preparation surface area measurements (mm2) using the Cerec digital mouth camera in vitro and to analyze a collection of 514 Cerec camera in vivo optical impressions of preparations from 274 patients according to the size of preparation/bonding area (mm2) METHODS: The surface area (mm2) of model preparations with known dimensions namely of one occlusal (1) and one mesio-occluso-distal (2) cavity as well as of one central incisor (3) and one molar (4) crown preparation was calculated from linear (a) design dimensions, (b) slide-gauge and (c) coordinate-measuring-machine data as benchmark measurements and from repeated (n=10) (d) laser-scan (control), (e) Cerec-camera mounted on a support, (f) handheld Cerec-camera measurements. Data of (d), (e) and (f) was statistically analyzed. From a collection of data sets clinically recorded with the Cerec camera, the surface areas of 514 preparations from 274 patients were analyzed according to the type of tooth and type of preparation. RESULTS: Occlusal cavity mm2 data 1(d) 48 +/- 0.4, 1(e) 48 +/- 0.2, 1(f) 48 +/- 0.6 and mod cavity mm2 data 2(d) 137 +/- 2, 2(e) 138 +/- 1, 2(f) 138 +/- 4 did not differ between (d), (e) and (f) (P> 0.05) confirming the hypothesis for inlay cavities. Incisor crown preparation mm2 data 3(d) 82+0.4 differed (P< 0.001) from 3(e) 85 +/- 0.2 and 3(f) 85 +/- 0.6 as well as molar crown preparation mm2 data 4(d) 133 +/- 0.6 differed by 3.5% (P< 0.001) from 4(e) 137 +/- 0.4 and 4f) 138 +/- 1. Clinical cavity and crown preparation area data obtained from in vivo Cerec camera recordings differentiated between type of tooth and type of cavity. 2D data of "classic", "reduced" and "endo" type crown preparations did not differentiate clearly.

Ceramics↗

PubMed2005

Strength and fracture pattern of monolithic CAD/CAM-generated posterior crowns.

OBJECTIVES: This study evaluated the strength and fracture pattern of monolithic posterior CAD/CAM crowns hypothesizing that zinc-phosphate cemented lithium disilicate crowns might show the same fracture strength as adhesively cemented crowns. METHODS: Two sets of monolithic posterior crowns each with uniform occlusal and lateral wall thickness of 1.5mm were fabricated from three types of block ceramic (1) lithium disilicate glass, (2) leucite glass and (3) feldspathic ceramic using CEREC 3 CAD/CAM. Crowns (n = 15) of ceramics (1), (2) and (3) each were (A) zinc-phosphate cemented, (B) adhesively cemented on resin-based composite dies and loaded until fracture. Load data was analyzed using ANOVA and Scheffé tests. Crack pattern was evaluated on an additional three sample cross-sections for each group at start of fracture. RESULTS: Radial cracks originated early at the cementation interfaces and cone cracks were observed finally at the loading sites. Mean load values (SD) of A-crowns at fracture start/end (1) 807 (91) N/2082 (192) N; (2) 915 (193) N/1130 (166) N; (3) 985 (199) N/1270 (301) N were all significantly (P < 0.001) lower when compared to their B-crown analogs (1) 1456 (205) N/2389 (84) N; (2) 1684 (395) N/2469 (171) N; (3) 1548 (304) N/2392 (75) N, rejecting the authors hypothesis. A-1 crowns had significantly (P < 0.001) higher fracture load than A-2 and A-3 crowns. The A-1 crown fracture load data, even if significantly (P < 0.001) lower, came close to the B-1 values. SIGNIFICANCE: Adhesive cementation balanced the strength of weak ceramics with that of strong ceramic and recommended itself for leucite glass ceramic and feldspathic ceramic crowns. Zinc-phosphate cementation appeared feasible for lithium disilicate crowns.

Aluminum Silicates↗

PubMed2004

Survival rate of mono-ceramic and ceramic-core CAD/CAM-generated anterior crowns over 2-5 years.

Anterior mono-ceramic (Mk II, n = 18) and ceramic core (In-Ceram Spinell, n = 18) crowns were CAD/CAM-fabricated using Vitablocs with the Cerec 2 CAD/CAM system and bonded in 24 patients. All crowns were rated using modified United States Public Health Services (USPHS) criteria at baseline and after a service time of 2-5 years. Survival of the crowns, regarding fracture, was analysed (Kaplan-Meier) after 44.7 +/- 10.3 months. Gingival health at crowns was assessed using plaque and bleeding scores. One core crown and one mono-ceramic crown had fractured after 42.5 months and 12 months, respectively, with survival rates of 91.7% for In-Ceram Spinell and 94.4% for Mk II; the difference was not statistically significant. Between baseline and follow-up examinations, non-significant shifts from A- to B-ratings occurred, particularly for marginal adaptation, for both crown types. Plaque and bleeding scores did not differ between the ceramic crown types but showed significantly less plaque and less bleeding at ceramic crowns than at control teeth at follow-up. The clinical performance of mono-ceramic crowns was judged to be similar to that of ceramic core crowns.

Adult↗

PubMed2003

Clinical and SEM evaluation of all-ceramic chair-side CAD/CAM-generated partial crowns.

The effect of hardware and software on the quality of Cerec all-ceramic partial crowns was investigated in this cross-sectional study. Partial crowns (n = 818) had been adhesively placed in 496 patients between 1993 and 1997 using Cerec 1 and Cerec 2 units (groups 1 and 2) as well as Cerec 2 with wall-spacing software (group 3). From each group, 25 randomly selected partial crowns were evaluated using modified United States Public Health Service (USPHS) criteria. Of these, 12 were randomly selected in each group, replicas taken and examined in a scanning electron microscope for marginal interfacial width and for continuous margin adaptation. Interfacial width of group 1 (308 +/- 95 micro m) was significantly larger than those of groups 2 (243 +/- 48 micro m) and 3 (207 +/- 63 micro m). Continuous margin adaptation at the tooth-luting composite and luting composite-restoration interfaces showed only minor differences in groups 1 (94.5 +/- 8% and 95.5 +/- 2%), 2 (98.1 +/- 1% and 97.5 +/- 1.4%) and 3 (96.8 +/- 3% and 96.8 +/- 2%). Pooled clinical rating was excellent or good at 97% for all groups, indicating acceptable restoration quality except for one breakage in group 1.

Adult↗

PubMed2002

All-ceramic, chair-side computer-aided design/computer-aided machining restorations.

An update is given on the research and development of chair-side all-ceramic CAD/CAM restorations. The Cerec CAD/CAM technology now has close to 8000 users worldwide. Recent improvements provide a sufficiently user-friendly handling of all components to accommodate the user with ordinary technical skills. CAD/CAM technology using non-metallic esthetic materials is increasingly gaining importance in restorative dentistry.

Adult↗

PubMedDate not supplied

An up to 5-year clinical evaluation of posterior in-ceram CAD/CAM core crowns.

PURPOSE: This study evaluated the clinical performance of posterior CAD/CAM-generated In-Ceram Alumina and In-Ceram Spinell core crowns. MATERIALS AND METHODS: Nineteen In-Ceram Spinell core crowns (four premolars and 15 molars) and 24 In-Ceram Alumina core crowns (two premolars and 22 molars) in 21 patients were examined using modified USPHS criteria at baseline and after a mean service time of 39 +/- 11 months. The crown copings were machined from Vitablocs In-Ceram Alumina and Vitablocs In-Ceram Spinell using the Cerec 2 CAD/CAM system. RESULTS: Two molar In-Ceram Alumina core crowns fractured after respective service times of 14 and 17 months in the same patient. The Kaplan-Meier survival rate regarding fracture of the ceramic was 92% for In-Ceram Alumina and 100% for In-Ceram Spinell. At the follow-up examination, 80% alpha ratings and 18% beta ratings for In-Ceram Alumina core crowns and 84% alpha ratings and 15% beta ratings for In-Ceram Spinell core crowns were recorded. CONCLUSION: Despite the two fractures, the clinical quality of CAD/CAM-generated In-Ceram Alumina and In-Ceram Spinell posterior crowns was excellent. Within the limitations of this study, both types of crowns appeared to be feasible.

Adult↗

PubMedDate not supplied

Fracture load of CAD/CAM-generated slot-inlay FPDs.

PURPOSE: This study investigated fracture load of computer-aided design/manufacturing (CAD/CAM)-generated slot-inlay fixed partial dentures (FPD) machined from ceramic and composite. MATERIALS AND METHODS: Ninety slot-inlay FPDs were machined in groups of 15 specimens each using the same design on a Cerec 3 unit. Materials were assigned to groups: (1) Mk II feldspathic ceramic, (2) ProCAD glass-ceramic, (3) glass-ceramic 1, (4) glass-ceramic 2, (5) composite 1, and (6) composite 2. The slot-inlay FPDs were placed on models with two abutment teeth without cementation and loaded to fracture. For control, test bars (n = 15) were machined from each of the materials, and flexural strength was examined using three-point bending. Data were statistically analyzed using ANOVA and Scheffé tests. RESULTS: Fracture load of groups 4 (1,557 N, SD 236), 5 (1,048 N, SD 77), and 6 (1,512 N, SD 106) was significantly higher than that of groups 1 (652 N, SD 53) and 2 (773 N, SD 65). Flexural strength of group 4 (256 MPa, SD 20) was significantly higher than that of groups 1 (103 MPa, SD 6), 2 (127 MPa, SD 15), 3 (162 MPa, SD 32), 5 (178 MPa, SD 18), and 6 (170 MPa, SD 20). CONCLUSION: Fracture loads of glass-ceramic 2 and composite 2 appear adequate for CAD/CAM slot-inlay FPDs.

Aluminum Silicates↗

PubMedDate not supplied

Survival of ceramic computer-aided design/manufacturing crowns bonded to preparations with reduced macroretention geometry.

PURPOSE: Adhesive cementation reduces the need for macroretentive preparation for crowns. This study investigated the survival and clinical rating of monolithic computer-aided design/manufacturing (CAD/CAM) ceramic crowns bonded to preparations with reduced macroretention, hypothesizing that adhesion would compensate for reduced retention geometry. MATERIALS AND METHODS: Two-hundred eight posterior CAD/CAM-generated crowns from feldspar block ceramic were adhesively bonded in 136 patients in three preparation groups: classic (100% stump height, n = 70); reduced (reduced stump height or irregular stump, n = 52); and endo (absent stump but pulp chamber retention cavity, n = 86). Crowns were examined at baseline and after 55 +/- 15 months using modified USPHS criteria. Plaque and bleeding of gingiva around the crowns were assessed. RESULTS: Cumulative Kaplan-Meier survival of crowns on premolars/molars was: classic = 97.0%/94.6%; reduced = 92.9%/92.1%; and endo = 68.8%/87.1%, confirming the hypothesis for classic, reduced, and endo molars as well as for classic and reduced premolars. A significant difference was found between classic and endo premolar crowns, rejecting the hypothesis for endo preparation on premolars. Plaque and bleeding indices were significantly lower for crowned teeth than for controls. CONCLUSION: The survival of classic and reduced crowns was rated adequate for premolars and molars. Endo preparation appeared acceptable for molar crowns but inadequate for premolar crowns.

Aluminum Silicates↗