The Randomized Shortened Dental Arch Study: Tooth Loss Over 10 Years.

PURPOSE: This study aimed to compare the long-term outcomes of two different nonimplant treatments in the bilateral shortened dental arch (SDA). MATERIALS AND METHODS: In a multicenter randomized controlled clinical trial, patients with complete molar loss in one arch were assigned to one of two different nonimplant treatments. In the partial removable dental prosthesis (PRDP) group, patients were provided with a distal-extension prosthesis retained with precision attachments. In the SDA group, patients were treated according to the SDA concept by preserving or restoring a premolar occlusion. RESULTS: Of the 152 treated patients, 82 reached the 10-year examination independent of their dental or prosthetic status. In the intention-to-treat analysis, the survival rates for tooth loss at 10 years were 0.44 (95% confidence interval [CI]: 0.30 to 0.56) in the PRDP group and 0.52 (95% CI: 0.37 to 0.65) in the SDA group. For tooth loss in the study arch, the survival rates were 0.67 (95% CI: 0.52 to 0.78) in the PRDP group and 0.60 (95% CI: 0.45 to 0.73) in the SDA group. The number of teeth lost was higher than expected. In a multivariate analysis using a multiple Cox regression model, the covariates age (unit: 1 year, Hazard Ratio [HR]: 1.033, P = .03) and DMFT value (unit: 1 tooth, HR: 1.121, P = .03) were significant for time to first tooth loss in the study arch. CONCLUSION: The results suggest an overestimation of the influence of the prosthetic management of the bilateral SDA. In treatment decisions, patient preferences should be considered with appropriate weight.

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.

Influence of preparation and wall thickness on the resistance to fracture of zirconia implant abutments.

BACKGROUND: Studies about the effect of grinding procedures as well as material thickness on the resistance of zirconia implant abutments are in short supply. PURPOSE: This study evaluated the effect of wall thickness as well as preparation on the resistance of zirconia implant abutments. MATERIALS AND METHOD: Sixty-four implants received titanium (group Ti) and zirconia abutments (groups Zr-8, Zr-18, and Zr-1). The abutments of group Zr-8 had a 0.8-mm wall thickness, whereas the wall thickness of group Zr-18 was reduced by preparation from 1 mm to 0.8 mm. The abutments of group Zr-1 had a wall thickness of 1 mm. Standardized maxillary central incisor metal crowns were cemented on all abutments. All specimens were then tested in a universal testing machine for their resistance to fracture before and after masticatory simulation (n = 8). RESULTS: The median resistance to fracture values (N) before and after aging were, respectively: group Ti: 500-504; group Zr-8: 487-491; group Zr-18: 490-451; and group Zr-1: 519-480. No significant effects of group, aging, or combinations were found (p > .05). CONCLUSION: All tested abutments have the potential to withstand physiologic occlusal forces in the anterior region (> 200 N). The applicability of the results to other implant systems should be verified.

Zirconia in fixed implant prosthodontics.

BACKGROUND: CAD/CAM technology in combination with zirconia ceramic has increasingly gained popularity in implant dentistry. PURPOSE: This narrative review presents the current knowledge on zirconia utilized as framework material for implant-borne restorations and implant abutments, laboratory tests and developments, clinical performance, and possible future trends for implant dentistry are addressed. MATERIAL AND METHODS: A review of available literature from 1990 through 2010 was conducted with search terms zirconia,""implants,""abutment,""crown," and "fixed dental prosthesis" using electronic databases (PubMed) and manual searching. RESULTS: Latest applications of zirconia in implant dentistry include implant abutments, multiple unit and full-arch frameworks as well as custom-made bars to support fixed and removable prostheses. High biocompatibility, low bacterial surface adhesion as well as favorable chemical properties of zirconia ceramics are reported. Zirconia stabilized with yttrium oxide exhibits high flexural strength and fracture toughness due to a transformation toughening mechanism. Preliminary clinical data confirmed the high stability of zirconia for abutments and as a framework material for implant borne crowns and fixed dental prostheses. Zirconia abutment or framework damage has rarely been encountered. However, veneering porcelain fractures are the most common technical complication in implant-supported zirconia restorations. These porcelain veneer failures have led to concerns regarding differences in coefficient of thermal expansions between core and veneering porcelain and their respective processing techniques. CONCLUSION: As presently evidence of clinical long-term data is missing, caution with regard to especially extensive implant-borne zirconia frameworks is recommended.

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.

Influence of thermomechanical fatigue loading on the fracture resistance of all-ceramic posterior crowns.

This study evaluated the fracture resistance and the survival rate of different all-ceramic crowns in-vitro after thermomechanical fatigue loading in comparison to porcelain-fused-to-metal posterior crowns. Sixteen crowns for human mandibular first molars were made of each of the following: Cercon, IPS-Empress 2 In-Ceram Zirconia, Procera AllZircon and porcelain-fused-to-metal. Half of the specimens of each group was thermocycled and dynamically loaded using a chewing simulator All samples were thereafter tested for the maximum fracture resistance. The survival rates after 1-2 million cycles in the artificial mouth were 100% in all the tested crown systems. The chewing simulation and thermocycling did not significantly decrease the fracture strength of the ceramic crowns (P>0.005). The median fracture load of Cercon, Procera AllZircon, In-Ceram Zirconia and PFM was significantly higher than IPS-Empress 2 both for loaded and non loaded groups (P<0.005) while the difference between Cercon, Procera AllZircon, In-Ceram Zirconia and PFM was not significant (P>0.005). All-ceramic systems showed fracture load values similar to those of porcelain-fused-to-metal molar crowns and therefore may be considered for use in clinical studies.

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.