***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: The aim of this study was to evaluate the internal fit , marginal adaptation , and bond strengths of inlays made of computer-aided design /computer-aided manufacturing feldspathic ceramic and polymer-infiltrated ceramic . Twenty molars were r and omly selected and prepared to receive  inlays that were milled from both material s. Before cementation , internal fit was achieved using the replica technique by molding the internal surface with addition silicone and measuring the cement thicknesses of the pulpal and axial walls . Marginal adaptation was measured on the occlusal and proximal margins of the replica . The inlays were then cemented using resin cement ( Panavia F2.0 ) and subjected to two million thermomechanical cycles in water ( 200 N load and 3.8-Hz frequency ) . The restored teeth were then cut into beams , using a lathe , for microtensile testing . The contact angles , marginal integrity , and surface patterns after etching were also observed . Statistical analysis was performed using two-way repeated measures analysis of variance ( p<0.05 ) , the Tukey test for internal fit and marginal adaptation , and the Student t-test for bond strength . The failure types ( adhesive or cohesive ) were classified on each fractured beam . The results showed that the misfit of the pulpal walls ( p=0.0002 ) and the marginal adaptation ( p=0.0001 ) of the feldspathic ceramic were significantly higher when compared to those of the polymer-infiltrated ceramic , while the bond strength values of the former were higher when compared to those of the latter . The contact angle of the polymer-infiltrated ceramic was also higher . In the present study , the hybrid ceramic presented improved internal and marginal adaptation , but the bond strengths were higher for the feldspathic ceramic Objectives This study was conducted to evaluate a self-adhesive resin luting cement [ RelyX Unicem 3MESPE – RXU ] for  luting partial ceramic crowns ( PCCs )  with and without selective enamel etching in a prospect i ve , r and omized clinical trial . Material s and methods Thirty-four patients had received the intended treatment . Two PCCs ( Vita Mark II ; Cerec 3D ; Sirona ) had been placed in a split-mouth design : one with RXU without enamel etching ( RXU ) , the other with RXU with selective enamel etching ( RXU + E ) . Restorations were evaluated at baseline ( BL ) and after 12 , 24 , and 36 months ( USPHS criteria ) . For statistical analysis , the Chi-square test was applied ( α = 0.05 ) . Clinical survival of all restorations ( n = 68 ) after 3 years was determined using Kaplan – Meier analysis . Results Twenty three patients ( 12 male/11 female ) were available for clinical evaluation after 3 years . 19 RXU-PCCs were placed in molars , four in premolars , 18 RXU + E – PCCs in molars , five in premolars . Concerning clinical changes , no significant differences were found between luting strategies RXU/RXU + E at all recalls . Statistically significant changes over time were observed for marginal adaptation and marginal discoloration between BL and 36 m for RXU and RXU + E. For RXU + E , postoperative hypersensitivities decreased significantly from BL ( n = 6 ) to 36 m ( n = 0 ) . Of the 68 restorations originally included , eight RXU and four RXU + E restorations failed . At 3 years , Kaplan – Meier survival  of RXU was 72.9 % , that of RXU + E 87.6 % . Survival rates were not statistically significant different . Conclusions Although clinical survival of RXU + E is slightly better at 3 years , restorations of both groups perform similar with respect to clinical changes over time as evaluated by modified USPHS criteria . Clinical relevance The self-adhesive resin cement RXU can be used in conjunction with selective enamel etching , because survival rates of PCCs in the RXU + E group were not lower but , as a trend , even better than without enamel etching Statement of problem Trials comparing the overall performance of digital with that of conventional workflows in restorative dentistry are needed . Purpose The purpose of the third part of a series of investigations was to test whether the marginal and internal fit of monolithic crowns fabricated with fully digital workflows differed from that of crowns fabricated with the conventional workflow . Material and methods In each of 10 participants , 5 monolithic lithium disilicate crowns  were fabricated for the same abutment tooth according to a r and omly generated sequence . Digital workflows were applied for the fabrication of 4 crowns using the Lava , iTero , Cerec inLab , and Cerec infinident systems . The conventional workflow included a polyvinyl siloxane impression , manual waxing , and heat‐press technique . The discrepancy between the crown and the tooth was registered using the replica technique with polyvinyl siloxane material . The dimensions of the marginal discrepancy ( Discrepancymarginal ) and the internal discrepancy in 4 different regions of interest ( Discrepancyshoulder , Discrepancyaxial , Discrepancycusp , and Discrepancyocclusal ) were assessed using light microscopy . Post hoc Student t test with Bonferroni correction was applied to detect differences ( & agr;=.05 ) . Results Discrepancymarginal was 83.6 ±51.1 & mgr;m for the Cerec infinident , 90.4 ±66.1 & mgr;m for the conventional , 94.3 ±58.3 & mgr;m for the Lava , 127.8 ±58.3 & mgr;m for the iTero , and 141.5 ±106.2 & mgr;m for the Cerec inLab workflow . The differences between the treatment modalities were not statistically significant ( P>.05 ) . Discrepancyshoulder was 82.2 ±42.4 & mgr;m for the Cerec infinident , 97.2 ±63.8 & mgr;m for the conventional , 103.4 ±52.0 & mgr;m for the Lava , 133.5 ±73.0 & mgr;m for the iTero , and 140.0 ±86.6 & mgr;m for the Cerec inLab workflow . Only the differences between the Cerec infinident and the Cerec inLab were statistically significant ( P=.036 ) . The conventionally fabricated crowns revealed significantly lower values in Discrepancycusp and Discrepancyocclusal than all the crowns fabricated with digital workflows ( P<.05 ) . Conclusions In terms of marginal crown fit , no significant differences were found between the conventional and digital workflows for the fabrication of monolithic lithium disilicate crowns . In the occlusal regions , the conventionally manufactured crowns revealed better fit than the digitally fabricated crowns . Chairside milling result ed in less favorable crown fit than central ized milling production Background Evaluation of the marginal fit of cemented zirconia copings manufactured after digital impression with Lava ™ Chairside Oral Scanner in comparison to that of  zirconia copings manufactured after conventional impressions with polyvinyl siloxane . Methods A prepared typodont tooth # 36 , was replicated 40 times with a vinyl silicone and precise model resin . The dies were r and omly divided into two groups according to the impression taking technique . Digital impressions with Lava ™ C.O.S. and conventional impressions were taken according to the group . Subsequently  zirconia copings  were manufactured and cemented on their respective dies with zinc oxide phosphate cement . After embedding in resin , mesio-distal section of each coping was performed with a diamond saw in order to obtain two slices . One half of the specimen was used for evaluation with an optical microscope ( OM ) and the other half for evaluation with a scanning electron  microscope ( SEM ) . Marginal gap ( MG ) and absolute marginal discrepancy ( AMD ) were measured mesial and distal on each slice . Results No significant difference of the marginal parameters between the digital and the conventional group was found . The mean values for MG in the digital group were 96.28 μm ( + /−43.21 μm ) measured with the OM and 99.26 μm ( + /−48.73 μm ) measured with the SEM , respectively . AMD mean values were 191.54 μm ( + /−85.42 μm ) measured with the optical microscope and 211.6 μm ( + /−96.55 μm ) with the SEM . For the conventional group the mean MG values were 94.84 μm ( + /−50.77 μm ) measured with the OM and 83.37 μm ( + /−44.38 μm ) measured with the SEM , respectively . AMD mean values were 158.60 μm ( + /−69.14 μm ) for the OM and 152.72 μm ( + /−72.36 ) for the SEM . Conclusions Copings manufactured after digital impression with Lava ™ C.O.S. show comparable marginal parameters with the copings manufactured after conventional impression with polyvinyl syloxane . The mean MG values of both groups fit in the clinical ly acceptable range 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 . MATERIAL S AND METHODS Seventy-two caries-free , extracted human m and ibular molars were r and omly 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 material s. 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 result ed 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 clinical ly acceptable range . Marginal fit was not affected by the investigated heat-press versus CAD/CAM fabrication technique . Press fabrication result ed 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 STATEMENT OF PROBLEM Gap measurements along margins are frequently used to assess the quality of single crowns . However , the number of gap measurements required for clinical ly relevant results in laboratory studies is not known . PURPOSE This study estimated the minimum number of gap measurements on margins of single crowns to produce relevant results for gap analysis . METHODS AND MATERIAL Ten all-ceramic crowns were fabricated on a master steel die . Gaps along crown margins were investigated in a scanning electron microscope on the master steel die without cementation and on replica dies after conventional cementation . Measurements were made in 100 microm steps according to 3 gap definitions . The initial number of measurements per crown ( n = 230 ) was reduced to smaller subsets using both systematic and r and om approaches to determine the impact on the quality of results . RESULTS On the data of gap definition 1 , reduction from 230 to about 50 measurements caused less than + /-5 microm variability for arithmetic means . Analysis of st and ard errors showed slowly increasing values smaller than 3 microm , both indicating no relevant impact on the quality of results . Smaller data sizes yielded accelerated increase of st and ard errors and divergent variabilities of mean . The minimum of 50 measurements did not depend on gap definition or on cementation condition . CONCLUSION Fifty measurements are required for clinical ly relevant information about gap size regardless of whether the measurement sites are selected in a systematic or r and om manner , which is far more than what current in vitro studies use Objective This study examined the fit of two types of all-ceramic single crowns and indirect composite resin full coverage crowns .  Material and Methods Thirty intact human m and ibular first premolars were selected for this study and prepared using a machine to st and ardize the dimensions and r and omly divided into 3 groups . Slip cast ( IC ) ( In-Ceram Zircon 
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Conclusions Most of the studies reported clinical ly acceptable values for marginal adaptation .
The performance of a CAD‐CAM system is influenced by the type of restorative material .
A nonretentive cavity preparation exhibited better adaptation than a retentive preparation .
Most studies showed that thermomechanical loading affected the quality of marginal adaptation .
Cementation increased marginal discrepancies .
No statistically significant difference was found for marginal fit of onlays between intraoral and extraoral optical scans using a stone die .
The number of milling axes , the type of digital camera , and the region measured were statistically significant in relation to marginal/internal adaptation .
Values of adaptation recorded failed to reproduce the preestablished spacer parameters in the software .