Veneered anatomically designed zirconia FDPs resulting from digital intraoral scans: Preliminary results of a prospective clinical study.

OBJECTIVES: The aim of this prospective clinical study was to evaluate the clinical performance of veneered anatomically designed zirconia fixed dental prostheses (FDPs) resulting from intraoral digital impressions. METHODS: 24 patients requiring treatment were provided with all-ceramic FDPs. Intraoral scans (iTero) were performed and veneered anatomically designed CAD/CAM-zirconia FDPs (Zerion/VitaVM9) were fabricated. A feldspar veneering ceramic following a slow cooling firing protocol was applied. A self-curing resin based luting material was used for adhesive cementation. Clinical evaluations were performed at baseline and 6, 12, and 18 months recalls according to the modified USPHS-criteria. Intraoral digital surface scans (iTero) were performed at each recall examination and were digitally superimposed (Geomagic) to evaluate potential veneer cohesive fractures. Kaplan-Meier survival analysis comprised secondary caries, clinically unacceptable fractures, root canal treatment and debonding. Kaplan-Meier success rate included restorations with minimal crevices, tolerable color deviations and clinically acceptable fractures. Data were statistically analyzed. RESULTS: The Kaplan-Meier survival rate and success rate of the FDPs were 100% and 91.7%, respectively. Clinically acceptable veneer cohesive fractures and crevices at the restoration margin were observed in two patients. These shallow veneer fractures were only detected by overlapping baseline and recall scans. Ceramic surface roughness increased significantly over time (p<0.0001). CONCLUSIONS: Veneered zirconia FDPs fabricated from digital intraoral scans showed a favorable clinical performance over an observation period of 18 months. Anatomical zirconia core design and slow cooling firing protocol of the veneering ceramic reduced the incidence of chip fractures to a level that could not be detected clinically. CLINICAL SIGNIFICANCE: The digital workflow on the basis of intraoral digital impressions resulted in clinically satisfying outcomes for veneered zirconia FDPs.

The randomized shortened dental arch study: temporomandibular disorder pain.

OBJECTIVES: The aim of this multi-center, randomized controlled trial was to assess the impact of missing posterior support on the risk for temporomandibular disorder (TMD) pain by comparing patients with either shortened dental arches (SDA) or molar replacement by removable dental prostheses (RDP). METHODS: A sample of 215 patients with bilateral molar loss in at least one jaw was consecutively recruited in 14 prosthodontic departments of dental schools in Germany. Of the initial sample, 152 patients (mean age: 59.7 years; 53.9 % female) received randomly allocated interventions (SDA: n = 71; RDP: n = 81). Presence of TMD pain was assessed using patients' self-reports and was verified by physical examination and by pain intensity, as the mean of current pain, worst pain, and average pain in the last 6 months, with 10-point ordinal rating scales. Assessments were performed before treatment and at follow-ups until 60 months after treatment. Impact of interventions on TMD risk and pain intensity was computed by applying logistic and linear random-intercept models. RESULTS: Tooth replacement (RDP) did not significantly change the risk for self-reported (odds ratio [OR]: 1.1; confidence interval [CI]: 0.4 to 3.4) or clinically verified (OR: 0.7; CI: 0.1 to 4.3) TMD pain compared to no tooth replacement (SDA). Mean characteristic pain intensity was virtually identical in both groups (Coeff: 0.01; CI: -0.30 to 0.32). CONCLUSION: Retaining or preservation of an SDA is not a major risk factor for TMD pain over the course of 5 years when compared to molar replacement with RPDs. CLINICAL RELEVANCE: Seemingly, missing molars do not have to be replaced in order to prevent TMD pain.

The all-on-four treatment concept: a systematic review.

PURPOSE: The study aims to evaluate the all-on-four treatment concept with regard to survival rates (SRs) of oral implants, applied fixed dental prostheses (FDPs) and temporal changes in proximal bone levels. MATERIALS AND METHODS: A systematic review of publications in English and German was performed using the electronic bibliographic database MEDLINE, the Cochrane Library, and Google. Hand searches were conducted of the bibliographies of related journals and systematic reviews. The authors performed evaluations of articles independently, as well as data extraction and quality assessment. Data were submitted the weighted least-squared analysis. RESULTS: Thirteen (487 initially identified) papers met inclusion criteria. A number of 4,804 implants were initially placed, of which 74 failed, with a majority of failures (74%) within the first 12 months. A total of 1,201 prostheses were incorporated within 48 hours after the surgery. The major prosthetic complication was the fracture of the all-acrylic FDP. The mean cumulative SR/SR ± (standard deviation) (36 months) of implants and prostheses were 99.0 ± 1.0% and 99.9 ± 0.3%, respectively. The averaged bone loss was 1.3 ± 0.4 mm (36 months). No statistically significant differences were found in outcome measures, when comparing maxillary versus mandibular arches and axially versus tilted placed implants. CONCLUSION: The available data provide promising short-term results for the all-on-four treatment approach; however, current evidence is limited by the quality of available studies and the paucity of data on long-term clinical outcomes of 5 years or greater. In terms of an evidence-based dentistry, the authors recommend further studies designed as randomized controlled clinical trials and reported according to the CONSORT statement.

Long-term performance of posterior InCeram Alumina crowns cemented with different luting agents: a prospective, randomized clinical split-mouth study over 5 years.

OBJECTIVES: This prospective, randomized clinical split-mouth study investigated the 5-year performance of InCeram Alumina posterior crowns cemented with three different luting cements. 4-META- and MDP-based cements were used for adhesive luting. Glass ionomer cement served as control. MATERIALS AND METHODS: Sixty patients were treated with 149 (n = 62 Panavia F/MDP; n = 59 SuperBond-C&B/4-META; n = 28 Ketac Cem/glass ionomer) InCeram Alumina crowns on vital molars and premolars in a comparable position. Follow-up examinations were performed annually up to 5 years after crown placement using the modified United States Public Health Service (USPHS) criteria. Kaplan-Meier survival analysis comprised secondary caries, clinically unacceptable fractures, root canal treatment and debonding. Kaplan-Meier success rate included restorations with minimal crevices, tolerable color deviations (<1 Vitashade), and clinically acceptable fractures. Logistic regression models with a random intercept were fitted. RESULTS: The 5-year Kaplan-Meier survival probabilities were: SuperBond-C&B 88.7 %, Panavia F 82.8 %, Ketac Cem 80.1 % with no significant difference (p = .813). Endodontical treatment was carried out on 7.4 % of all abutment teeth, and 5.4 % revealed secondary caries. Unacceptable ceramic fractures were observed in 7.4 %. Debonding was a rare complication (1.3 %). The 5 year Kaplan-Meier success rate was 91.6 % for SuperBond-C&B-, 87.4 % for Ketac Cem- and 86.3 % for Panavia F-bonded restorations with no significant difference (p = .624). All cement types showed significant marginal deterioration over time (p < .0001). CONCLUSIONS: Posterior InCeram Alumina crowns showed acceptable long-term survival and success rates independent of luting agent used. Ceramic fractures, endodontical treatments and secondary caries were the most frequent failures. CLINICAL RELEVANCE: Glass-infiltrated Alumina crowns in combination with adhesive as well as conventional cementation can be considered as a reliable treatment option in posterior teeth.

Marginal and internal fit of heat pressed versus CAD/CAM fabricated all-ceramic onlays after exposure to thermo-mechanical fatigue.

OBJECTIVES: The aim of the study was to evaluate the marginal and internal fit of heat-pressed and CAD/CAM fabricated all-ceramic onlays before and after luting as well as after thermo-mechanical fatigue. MATERIALS AND METHODS: Seventy-two caries-free, extracted human mandibular molars were randomly divided into three groups (n=24/group). All teeth received an onlay preparation with a mesio-occlusal-distal inlay cavity and an occlusal reduction of all cusps. Teeth were restored with heat-pressed IPS-e.max-Press* (IP, *Ivoclar-Vivadent) and Vita-PM9 (VP, Vita-Zahnfabrik) as well as CAD/CAM fabricated IPS-e.max-CAD* (IC, Cerec 3D/InLab/Sirona) all-ceramic materials. After cementation with a dual-polymerising resin cement (VariolinkII*), all restorations were subjected to mouth-motion fatigue (98 N, 1.2 million cycles; 5°C/55°C). Marginal fit discrepancies were examined on epoxy replicas before and after luting as well as after fatigue at 200× magnification. Internal fit was evaluated by multiple sectioning technique. For the statistical analysis, a linear model was fitted with accounting for repeated measurements. RESULTS: Adhesive cementation of onlays resulted in significantly increased marginal gap values in all groups, whereas thermo-mechanical fatigue had no effect. Marginal gap values of all test groups were equal after fatigue exposure. Internal discrepancies of CAD/CAM fabricated restorations were significantly higher than both press manufactured onlays. CONCLUSIONS: Mean marginal gap values of the investigated onlays before and after luting as well as after fatigue were within the clinically acceptable range. Marginal fit was not affected by the investigated heat-press versus CAD/CAM fabrication technique. Press fabrication resulted in a superior internal fit of onlays as compared to the CAD/CAM technique. CLINICAL RELEVANCE: Clinical requirements of 100 µm for marginal fit were fulfilled by the heat-press as well as by the CAD/CAM fabricated all-ceramic onlays. Superior internal fit was observed with the heat-press manufacturing method. The impact of present findings on the clinical long-term behaviour of differently fabricated all-ceramic onlays warrants further investigation.

Accuracy of full-arch scans using intraoral scanners.

OBJECTIVES: This study aimed to evaluate the accuracy of intraoral scanners in full-arch scans. MATERIALS AND METHODS: A representative model with 14 prepared abutments was digitized using an industrial scanner (reference scanner) as well as four intraoral scanners (iTero, CEREC AC Bluecam, Lava C.O.S., and Zfx IntraScan). Datasets obtained from different scans were loaded into 3D evaluation software, superimposed, and compared for accuracy. One-way analysis of variance (ANOVA) was implemented to compute differences within groups (precision) as well as comparisons with the reference scan (trueness). A level of statistical significance of p < 0.05 was set. RESULTS: Mean trueness values ranged from 38 to 332.9 µm. Data analysis yielded statistically significant differences between CEREC AC Bluecam and other scanners as well as between Zfx IntraScan and Lava C.O.S. Mean precision values ranged from 37.9 to 99.1 µm. Statistically significant differences were found between CEREC AC Bluecam and Lava C.O.S., CEREC AC Bluecam and iTero, Zfx Intra Scan and Lava C.O.S., and Zfx Intra Scan and iTero (p < 0.05). CONCLUSIONS: Except for one intraoral scanner system, all tested systems showed a comparable level of accuracy for full-arch scans of prepared teeth. Further studies are needed to validate the accuracy of these scanners under clinical conditions. CLINICAL RELEVANCE: Despite excellent accuracy in single-unit scans having been demonstrated, little is known about the accuracy of intraoral scanners in simultaneous scans of multiple abutments. Although most of the tested scanners showed comparable values, the results suggest that the inaccuracies of the obtained datasets may contribute to inaccuracies in the final restorations.

Influence of preparation design and ceramic thicknesses on fracture resistance and failure modes of premolar partial coverage restorations.

STATEMENT OF PROBLEM: Preparation designs and ceramic thicknesses are key factors for the long-term success of minimally invasive premolar partial coverage restorations. However, only limited information is presently available on this topic. PURPOSE: The purpose of this in vitro study was to evaluate the fracture resistance and failure modes of ceramic premolar partial coverage restorations with different preparation designs and ceramic thicknesses. MATERIAL AND METHODS: Caries-free human premolars (n=144) were divided into 9 groups. Palatal onlay preparation comprised reduction of the palatal cusp by 2 mm (Palatal Onlay Standard), 1 mm (Palatal-Onlay-Thin), or 0.5 mm (Palatal Onlay Ultrathin). Complete-coverage onlay preparation additionally included the buccal cusp (Occlusal Onlay Standard; Occlusal Onlay Thin; Occlusal Onlay Ultrathin). Labial surface preparations with chamfer reductions of 0.8 mm (Complete-Veneer-Standard), 0.6 mm (Complete-Veneer-Thin), and 0.4 mm (Complete Veneer Ultrathin) were implemented for complete veneer restorations. Restorations were fabricated from a pressable lithium disilicate ceramic (IPS-e.max-Press) and cemented adhesively (Syntac-Classic/Variolink-II). All specimens were subjected to cyclic mechanical loading (F=49 N, 1.2 million cycles) and simultaneous thermocycling (5°C to 55°C) in a mouth-motion simulator. After fatigue, restorations were exposed to single-load-to-failure. Two-way ANOVA was used to identify statistical differences. Pair-wise differences were calculated and P-values were adjusted by the Tukey-Kramer method (α=.05). RESULTS: All specimens survived fatigue. Mean (SD) load to failure values (N) were as follows: 837 (320/Palatal-Onlay-Standard), 1055 (369/Palatal-Onlay-Thin), 1192 (342/Palatal-Onlay-Ultrathin), 963 (405/Occlusal-Onlay-Standard), 1108 (340/Occlusal-Onlay-Thin), 997 (331/Occlusal-Onlay-Ultrathin), 1361 (333/Complete-Veneer-Standard), 1087 (251/Complete-Veneer-Thin), 883 (311/Complete-Veneer-Ultrathin). Palatal-onlay restorations revealed a significantly higher fracture resistance with ultrathin thicknesses than with standard thicknesses (P=.015). Onlay restorations were not affected by thickness variations. Fracture loads of standard complete veneers were significantly higher than thin (P=.03) and ultrathin (P<.001) restorations. CONCLUSIONS: In this in vitro study, the reduction of preparation depth to 1.00 and 0.5 mm did not impair fracture resistance of pressable lithium-disilicate ceramic onlay restorations but resulted in lower failure loads in complete veneer restorations on premolars.

Prospective clinical split-mouth study of pressed and CAD/CAM all-ceramic partial-coverage restorations: 7-year results.

The aim of this prospective clinical split-mouth study was to investigate the longterm performance of pressed and computer-aided design/computer-assisted manufacture (CAD/CAM) all-ceramic partial-coverage restorations (PCRs). Twentyfive patients were restored with 40 lithium disilicate pressed PCRs (IPS e.max-Press, Ivoclar Vivadent) and 40 leucite-reinforced glass-ceramic CAD/CAM PCRs (ProCAD, Ivoclar Vivadent). All restorations were placed in vital first or second molars. The 7-year Kaplan-Meier survival rate was 100% for pressed PCRs and 97% for CAD/ CAM PCRs. Both systems showed significant deterioration over time in all modified United States Public Health Service criteria. Increased surface roughness and impaired color match were significantly more prevalent with pressed PCRs. Based on the 7-year data, both all-ceramic systems can be considered reliable treatment options for posterior PCRs.

Monolithic and bi-layer CAD/CAM lithium-disilicate versus metal-ceramic fixed dental prostheses: comparison of fracture loads and failure modes after fatigue.

OBJECTIVES: The authors analyzed the effect of fatigue on the survival rate and fracture load of monolithic and bi-layer CAD/CAM lithium-disilicate posterior three-unit fixed dental prostheses (FDPs) in comparison to the metal-ceramic gold standard. MATERIALS AND METHODS: The authors divided 96 human premolars and molars into three equal groups. Lithium-disilicate ceramic (IPS-e.max-CAD) was milled with the CEREC-3-system in full-anatomic FDP dimensions (monolithic: M-LiCAD) or as framework (Bi-layer: BL-LiCAD) with subsequent hand-layer veneering. Metal-ceramic FDPs (MC) served as control. Single-load-to-failure tests were performed before and after mouth-motion fatigue. RESULTS: No fracture failures occurred during fatigue. Median fracture loads in [N], before and after fatigue were, respectively, as follows: M-LiCAD, 1,298/1,900; BL-LiCAD, 817/699; MC, 1,966/1,818. M-LiCAD and MC FPDs revealed comparable fracture loads and were both significantly higher than BL-LiCAD. M-LiCAD and BL-LiCAD both failed from core/veneer bulk fracture within the connector area. MC failures were limited to ceramic veneer fractures exposing the metal core. Fatigue had no significant effect on any group. CONCLUSIONS: Posterior monolithic CAD/CAM fabricated lithium-disilicate FPDs were shown to be fracture resistant with failure load results comparable to the metal-ceramic gold standard. Clinical investigations are needed to confirm these promising laboratory results. CLINICAL RELEVANCE: Monolithic CAD/CAM fabricated lithium-disilicate FDPs appeared to be a reliable treatment alternative for the posterior load-bearing area, whereas FDPs in bi-layer configuration were susceptible to low load fracture failure.

Implant dentistry curriculum in undergraduate education: part 2-program at the Albert-Ludwigs University, Freiburg, Germany.

PURPOSE: The aim of this study was to describe the didactic and clinical undergraduate implant dentistry program of the Albert-Ludwigs University, Freiburg, Germany, with emphasis on the clinical implant experience. MATERIALS AND METHODS: A detailed description of the implant curriculum at Albert-Ludwigs University is given with documented exemplary cases and additional flow charts. RESULTS: All students participate in 28 hours of lectures and approximately 64 hours of seminars with hands-on courses and gain clinical experience. All undergraduate students are eligible to place and restore oral implants. Emphasis is placed on prosthetic-driven planning of implant positions, three-dimensional imaging, and computer-guided implant placement. Implant restorations performed by undergraduate students comprise single crowns and small multiunit fixed dental prostheses in partially edentulous posterior maxillae and anterior or posterior mandibles, implant-retained overdentures (snap attachment) in edentulous patients, and telescopic fixed-removable dental prostheses on remaining teeth and strategically placed additional implants. Over the past 2.5 years, 51 patients were treated with 97 dental implants placed by students in the undergraduate program. Seventy-one restorations were inserted: 60.6% single crowns, 7% fixed dental protheses, 21.1% overdentures, and 11.3% telescopic fixed-removable dental prostheses. The implant survival rate was 98.9%. CONCLUSIONS: Because survival rates for dental implants placed and restored by students are comparable to those of experienced dentists, oral implant dentistry should be implemented as part of the undergraduate dental curriculum.

Implant dentistry curriculum in undergraduate education: part 1-a literature review.

PURPOSE: The aim of this literature review was to evaluate to what extent oral implant dentistry was integrated into undergraduate educational programs worldwide. MATERIALS AND METHODS: An online search of PubMed (MEDLINE and additional life science journals) was performed for articles published from 1966 to January 2010 using combinations of select medical subject headings. Additionally, the ISI Web of Knowledge database (MEDLINE: 1950 to present, Web of Science: 1945 to present) was searched using "education" and "implant" as search terms. The online search was supplemented with a manual search of dental journals in the fields of education, prosthodontics, and implant dentistry and of the reference lists of selected full-text articles. Surveys comparing different undergraduate dental implant curricula and articles describing the undergraduate dental implant curriculum of a single university were identified. Postgraduate or continuing education programs for dental practitioners or master and specialist programs were excluded. RESULTS: Twenty-five articles met the inclusion criteria of this review. The percentage of universities that included implant dentistry in undergraduate education increased from 51% in 1974 to 97% in 2006 for universities in the United States and to 100% for surveyed European universities. All curricula included lectures (mostly 1 to 20 hours) and 30% to 42% included laboratory courses, but the level of clinical experience differed greatly between surveyed universities. CONCLUSION: Because oral implant dentistry has become a standard treatment alternative, the undergraduate dental curricula should include its application in treatment planning, observation of placing and restoring implants, and treating patients with implant-retained or -supported restorations.

All-ceramic partial coverage restorations--midterm results of a 5-year prospective clinical splitmouth study.

OBJECTIVES: Midterm-evaluation of a 5-year prospective clinical splitmouth-investigation on survival rate and long-term behavior of all-ceramic partial coverage restorations (PCRs) on molars. Pressed ceramic and CAD/CAM fabricated PCRs were compared. METHODS: 80 vital molars of 25 patients were restored with all-ceramic PCRs (40 IPS e.max Press*[IP] and 40 ProCAD*[PC]). IP-PCRs were heat pressed following the lost-wax method. PC-PCRs were fabricated with Cerec 3** and Cerec InLab** CAD/CAM system (**Sirona Dental Systems, Bensheim, Germany). All PCRs were adhesively luted with a light-polymerizing composite (Syntac*/Tetric*) (*Ivoclar Vivadent, Schaan, Liechtenstein). Clinical reevaluations were performed at baseline and 13, 25, and 36 months after insertion of the PCRs according to the modified United States Public Health Services (USPHS) criteria. Absolute failures were demonstrated by Kaplan-Meier survival rate. RESULTS: After an observation time up to 3 years, survival rate of IP-PCRs was 100% and 97% for PC-PCRs due to one severe fracture. The PC-PCR had to be replaced after 9 months. Secondary caries and endodontic complications did not occur. Increased clinical service time resulted in significant decrease of marginal adaptation (p=0.031) and enhanced marginal discoloration (p<0.0001). Both PCR ceramic materials demonstrated significant deteriorations in color match (p<0.0001) and surface roughness (p<0.0001), IP-PCRs were significantly more affected (p< or =0.005). Regarding anatomic form IP-PCRs performed significantly better (p=0.0012). CONCLUSION: Pressed ceramic and CAD/CAM fabricated partial coverage restorations exhibited a reliable treatment option to restore larger defects in posterior teeth. Marginal degradation of the resin cement and deterioration of the all-ceramic materials during clinical function determine the clinical long-term performance of partial coverage restorations.

Simplified versus comprehensive fabrication of complete dentures: patient ratings of denture satisfaction from a randomized crossover trial.

OBJECTIVE: To determine if patient ratings of their ability to chew are dependent on the method of complete denture fabrication. METHOD AND MATERIALS: Twenty edentulous patients participated in a randomized within-subject crossover trial. Each participant received 2 sets of new complete dentures. One pair (Gerber prosthesis) was manufactured based on tracings (to determine centric relation) and facebow transfer; semianatomic teeth with a lingualized and balanced occlusal pattern were used. The other set of complete dentures was made using a simplified procedure without facebow transfer; jaw relations were recorded with wax occlusion rims, and anatomic teeth were set with a canine and premolar guidance (Gysi prosthesis). The 2 dentures were delivered in randomized order, and each was worn for 3 months. Three months after insertion, patients' ratings of each new prosthesis were obtained on visual analog scales for general satisfaction, comfort, ability to speak, stability, esthetics, ease of cleaning, and ability to chew. RESULTS: Patients rated their general satisfaction, stability, and esthetic appearance significantly better for the Gysi prostheses ( P < .05). No significant differences between the 2 denture treatment methods were detected for ability to speak, comfort, chewing ability, and the ease of cleaning the dentures. CONCLUSION: A comprehensive method for the fabrication of complete dentures using lingualized teeth does not appear to positively influence patient ratings of denture satisfaction when compared to a simple procedure with anatomic teeth.

Effect of mouth-motion fatigue and thermal cycling on the marginal accuracy of partial coverage restorations made of various dental materials.

OBJECTIVES: To investigate the influence of mouth-motion fatigue on marginal-accuracy of partial-coverage-restorations-(PCRs) of various dental materials. METHODS: Eighty molars were prepared equally and divided into five groups (n=16). PCRs were fabricated of following dental materials: Group-GO=Gold-Pontor-MPF(double dagger), Group-TA=Targis*, Group-EX=IPS-e.max-Press*, Group-EM=IPS-Empress*, Group-PC=ProCAD*/Cerec 3(dagger) ((double dagger)Metalor/*Ivoclar-Vivadent/(dagger)Sirona-Dental-System). Gold-PCRs were cemented conventionally. Residual 64 PCRs were adhesively luted and subjected to masticatory loading (1.2million-cycles, 1.6Hz, 49N) and thermal cycling (5 degrees C/55 degrees C, 60s, dwell-time, 5500cycles). Discrepancies in marginal-accuracy were examined on epoxy replicas (200 x magnification). Statistical analysis was performed by unpaired and paired t-tests (alpha=0.05). RESULTS: After cementing, marginal-accuracy (geometrical mean)[95% confidence limits] was recorded: GO-47[43-51]microm, TA-42[38-45]microm, EX-60[52-67]microm, EM-52[45-60]microm and PC-75[59-94]microm. No significant differences were found between groups GO, TA and EM. Values of Group-EX were significantly higher compared to Group-TA (p=0.04). Group-PC demonstrated significantly decreased marginal-accuracy towards groups GO (p=0.03) and TA (p=0.02). Except for Group-GO (p=0.01), no significant changes in marginal-accuracy were observed after mouth-motion fatigue and thermal cycling (GO-42[38-45]microm, TA-42[38-47]microm, EX-56[49-65]microm, EM-54[46-64]microm and PC-71[59-84]microm). However, Group-GO and Group-EM showed significant deviations in marginal-accuracy after aging (p=0.04). Marginal discrepancies of groups EX and EM were similar (p=1.0). Values of Group-PC were significantly higher when compared to groups GO (p=0.01) and TA (p=0.02). Buccal-lingual marginal discrepancies were significantly higher than mesial-distal in all groups and stages. SIGNIFICANCE: Cast-gold-PCRs demonstrated superior marginal-accuracy, followed by indirect ceromer PCRs. All-ceramic PCRs showed in vitro clinical acceptable marginal widths, even though CAD/CAM fabrication slightly compromised marginal-accuracy. Since preparation margins were not exposed to occlusal loading directly, increased marginal discrepancies due to marginal chipping during mouth-motion fatigue were not experienced.

Patient ratings of chewing ability from a randomised crossover trial: lingualised vs. first premolar/canine-guided occlusion for complete dentures.

BACKGROUND: Complex procedures involving a facebow transfer and the use of lingualised teeth are deemed to have a positive influence on the chewing ability with complete dentures. OBJECTIVES: To determine if patients' ratings of their ability to chew depend on the method of complete denture fabrication. METHODS: Edentulous patients (n = 20) participated in a within-subject crossover trial. Each patient received two sets of new complete dentures. One pair was manufactured based on intraoral tracing of centric relation and facebow transfer; semi-anatomical teeth with lingualised occlusion denture (LOD) were chosen. The second pair was made using a simplified procedure without facebow transfer; jaw relations were recorded with wax occlusion rims, and anatomical teeth with a first premolar/canine-guidance (CGD) were selected. The dentures were delivered in randomised order, and each was worn for 3 months. Three months after delivery, patients' ratings of each new prosthesis were recorded on visual analogue scales for their ability to chew seven index foods. Repeated measurements analysis of variance was performed to investigate possible carry-over effects accounting for confounding by treatment period. RESULTS: When comparing the two treatments, participants rated their ability to chew in general, to masticate carrots, hard sausage, steak and raw apple in particular, was significantly better with the CGD (anatomical teeth) than with the LOD (p < 0.05). CONCLUSION: Comprehensive methods for the fabrication of complete dentures including semi-anatomical lingualised teeth and a full registration do not seem to influence the perceived chewing ability, when compared with more simple procedures. Chewing ability for tough foods appears to benefit from the use of anatomical teeth.

Marginal accuracy of press-ceramic veneers influenced by preparation design and fatigue.

PURPOSE: To investigate the influence of preparation design and mouth motion fatigue on the marginal accuracy of press-ceramic veneers bonded to human maxillary central incisors. METHODS: Forty-eight extracted human maxillary central incisors divided in three groups of 16 specimens each, received veneer preparations. In Group WP a window preparation (WP) was performed. Specimens in Group IOP were prepared with an incisal overlap (IOP) of 2 mm without palatal chamfer. For Group CVP, specimens received a complete-veneer preparation (CVP) of 3 mm incisal reduction and 2 mm palatal extension. Veneers were fabricated with IPS Empress and bonded adhesively with dual polymerizing composite Variolink II. The discrepancies of marginal fit were examined on epoxy replicas before and after mouth motion fatigue at x200 magnification. RESULTS: The mean (geometrical) (95% confidence limits) marginal accuracy after cementation was recorded as follows: WP-46 (43-49) microm, IOP-46 (44-49) microm and CVP-54 (51-58) microm. Fatigue led to a significant decrease of marginal accuracy in all groups (P < 0.036) [WP-47 (44-50) microm, IOP-51 (48-53) microm and CVP-63 (59-67) microm]. Group CVP demonstrated significantly higher marginal gap values than groups WP and IOP, before and after fatigue (P < 0.004). No significant differences were found between groups WP and IOP.

Computer-aided design and fabrication of dental restorations: current systems and future possibilities.

BACKGROUND: For more than 20 years, researchers have been trying to automate conventional manual processes in dental technology with the hope of producing higher- and more uniform-quality materials, standardizing manufacturing processes and reducing production costs. METHODS: The authors review existing computer-aided design (CAD)/computer-aided manufacturing (CAM) systems, describing the components of CAD/CAM technologies and addressing the limitations of current systems, and suggest possibilities for future systems. CONCLUSIONS: Existing dental CAD/CAM systems vary dramatically in their capabilities; each has distinct advantages and limitations. None can yet acquire data directly in the mouth and produce the full spectrum of restoration types (with the breadth of material choices) that can be created by traditional techniques. Emerging technologies may expand dramatically the capabilities of future systems, but they also may require a different type of training to use them to their full effectiveness. CLINICAL IMPLICATIONS: In the future, automatically fabricated, fully esthetic restorations might be produced more quickly and have longer lifetimes than restorations currently produced with CAD/CAM systems.

[Preliminary clinical results of a prospective study of IPS e.max Press- and Cerec ProCAD- partial coverage crowns]. / Erste klinische Ergebnisse einer prospektiven Studie an IPS-e.max-Press- und Cerec-ProCAD-Teilkronen.

UNLABELLED: It was the aim of this prospective clinical splitmouth investigation to evaluate the survival rate and long-term behavior of all-ceramic partial coverage restorations (PCR) on molars. Pressed ceramic (IPS e.max Press) and CAD/CAM made (ProCAD) PCR were compared. 80 vital molars of 25 patients were restored with all-ceramic PCR (40 IPS e.max Press* and 40 ProCAD*). All PCR were adhesively luted with a light-polymerizing composite (Syntac*/Tetric*) (*Ivoclar-Vivadent AG, Schaan, Liechtenstein). The ProCAD PCR were produced with Cerec 3 and Cerec Inlab CAD/CAM system (Sirona Dental Systems, Bensheim, Germany). IPS e.max Press PCR were heat-pressed following the lost-wax IPS-Empress method. Clinical recall was arranged in average 8, 14, 20 and 28 months after cementation of the restoration. PCR were classified by USPHS criteria. The prospective survival rate of ProCAD PCR was 97% and 100% for IPS e.max Press PCR after an observation period of 24 months. After fracture, one ProCAD restoration had to be replaced after nine months. The clinical accuracy of the marginal fit of ProCAD PCR and IPS e.max Press PCR was recorded "Alfa". Limitations were recognized with respect to the color matching of both types of PCR ("Bravo"). CONCLUSION: Within the limits of the present clinical results, the tested all-ceramic materials IPS e.max Press und ProCAD seem to be indicated for partial coverage restorations on molars.