Vertical bone augmentation using collagenated or non-collagenated bone substitute materials with or without recombinant human bone morphogenetic protein-2 in a rabbit calvarial model.

PURPOSE: The aim of this study was to determine 1) the bone-regenerative effect of porcine bone block materials with or without collagen matrix incorporation, 2) the effect of a collagen barrier, and 3) the effect of adding recombinant human bone morphogenetic protein-2 (rhBMP-2) to the experimental groups. METHODS: Four treatment modalities were applied to rabbit calvaria: 1) deproteinized bovine bone mineral blocks (DBBM), 2) porcine bone blocks with collagen matrix incorporation (PBC), 3) porcine bone blocks alone without collagen matrix incorporation (PB), and 4) PBC blocks covered by a collagen membrane (PBC+M). The experiments were repeated with the addition of rhBMP-2. The animals were sacrificed after either 2 or 12 weeks of healing. Micro-computed tomography (micro-CT), histologic, and histomorphometric analyses were performed. RESULTS: Micro-CT indicated adequate volume stability in all block materials. Histologically, the addition of rhBMP-2 increased the amount of newly formed bone (NB) in all the blocks. At 2 weeks, minimal differences were noted among the NB of groups with or without rhBMP-2. At 12 weeks, the PBC+M group with rhBMP-2 presented the greatest NB (P<0.05 vs. the DBBM group with rhBMP-2), and the PBC and PB groups had greater NB than the DBBM group (P>0.05 without rhBMP-2, P<0.05 with rhBMP-2). CONCLUSIONS: The addition of rhBMP-2 enhanced NB formation in vertical augmentation using bone blocks, and a collagen barrier may augment the effect of rhBMP-2.

Soft-tissue dimensional change following guided bone regeneration on peri-implant defects using soft-type block or particulate bone substitutes: 1-year outcomes of a randomized controlled clinical trial.

AIM: To compare the peri-implant soft-tissue dimensional changes following guided bone regeneration between particulate (particle group) and collagenated soft-block-type (block group) biphasic calcium phosphate (BCP). MATERIALS AND METHODS: This study investigated 35 subjects: 18 in the particle group and 17 in the block group. Cone-beam computed tomography obtained at 6 months post surgery and optical impressions taken periodically (before surgery, 6 months post surgery, and 1 year post surgery) were superimposed. The ridge contour changes over time and the peri-implant mucosal thicknesses were measured diagonally and horizontally, and analysed statistically. RESULTS: The increases in diagonal (1.12 ± 0.78 mm) and horizontal (2.79 ± 1.90 mm) ridge contour of the block group were significantly higher than those in the particle group during the first 6 months (p < .05); however, the contour hardly changed thereafter (diagonal: 0.07 ± 0.75 mm; horizontal: -0.34 ± 1.26 mm), resulting in the 1-year contour changes similar between the two groups. Regardless of the type of BCP, the ridge contour increased significantly over 1 year when the dehiscence defect had a contained configuration (p < .05). CONCLUSIONS: The increase in soft-tissue dimensions for 1 year was similar between the two groups. The mucosal contour increase was larger when the surgery was conducted in a more contained defect, and this was not influenced by the type of BCP.

Effect of collagen membrane and of bone substitute on lateral bone augmentation with titanium mesh: An experimental in vivo study.

AIM: The aim of this study was to identify the additional effects of collagen membrane (CM) and of synthetic bone substitute (BS) on lateral bone augmentation of chronic peri-implant defect with titanium mesh (TM). MATERIALS AND METHODS: Atrophic alveolar ridge was induced in six canine mandibles, and 5 peri-implant defects were achieved in each hemi-mandible. Bone augmentation was attempted using the following randomly allocated modalities: (1) Control: no treatment, (2) TM only group: blood clot covered by TM, (3) TM+BS group: BS covered by TM, (4) TM+CM group: blood clot covered by TM and CM, and (5) TM+BS+CM group: BS covered by TM and CM. After 16 weeks of submerged healing, micro-CT and histomorphometric analyses were performed. RESULTS: TM exposure occurred in one case in the TM only group, one case in the TM+CM group, and two cases in the TM+BS+CM group. Histologically, pseudo-periosteum was observed along the inner and outer surfaces of TM, and the directions of the collagen fiber within the pseudo-periosteum differed according to the additional use of CM. In general, the TM only group rendered higher values in vertical defect fill and dimension of the augmented hard tissue in comparison with the other treatment groups. CONCLUSIONS: Due to the small sample size, this pilot study remains inconclusive. Within the limitations of the study, the use of CM and/or BS did not appear to have an additional benefit on lateral bone augmentation of peri-implant defect with TM.

Randomized controlled clinical trial comparing guided bone regeneration of peri-implant defects with soft-type block versus particulate bone substitutes: Six-month results of hard-tissue changes.

AIM: To test whether soft-type block bone substitute used for guided bone regeneration (GBR) of peri-implant defects leads to a different dimension of the augmented hard tissue than particulate bone substitute. MATERIALS AND METHODS: In 40 patients, 40 two-piece dental implants were placed >2 months after tooth extraction. Following random allocation, 20 peri-implant bone dehiscences were grafted with a soft-type block made of synthetic biphasic calcium phosphate (BCP) + collagen and 20 bone dehiscences with particulate BCP. All the sites were covered with a collagen membrane stabilized with titanium pins. Immediately after wound closure and after 6 months, the horizontal dimension (HD) of the augmented hard tissue was measured at the level of implant shoulder using cone beam computed tomography. During re-entry at 6 months, the defect fill was clinically assessed. RESULTS: At 6 months, the median HD measured 1.15 mm (mean: 1.31 mm) in the soft-block group and 0.93 mm (mean: 1.05 mm) in the particulate group (p = .6). At 6 months, 7.1% of contained defects and 61.9% of non-contained defects showed an incomplete vertical defect fill. CONCLUSIONS: Soft-type block of BCP + collagen used for GBR of peri-implant defects did not differ from particulate BCP regarding the dimension of the augmented hard tissue after 6 months of healing.

Effectiveness of xenogeneic and synthetic bone-block substitute materials with/without recombinant human bone morphogenetic protein-2: A preclinical study using a rabbit calvarium model.

AIM: To investigate new bone (NB) formation by using bone-block substitute materials with/without recombinant human bone morphogenetic protein-2 (rhBMP-2). MATERIALS AND METHODS: Three synthetic bone-block substitute materials [biphasic calcium phosphate (BCP); nanostructured hydroxyapatite (NH); 3D-printed tricalcium phosphate/hydroxyapatite (3DP)] and one xenogeneic deproteinized bovine bone mineral (DBBM) block substitute were affixed to rabbit calvarium using osteosynthesis screws, either with rhBMP-2 (n = 12) or without rhBMP-2 (n = 16). At 2 or 12 weeks (n = 6 with rhBMP-2 and n = 8 without rhBMP-2 for each week), histologic, histomorphometric and microcomputed tomography analyses were performed. RESULTS: The application of rhBMP-2 increased NB formation in all experimental groups at both weeks. DBBM resulted in a greater area of NB compared with synthetic blocks either with or without rhBMP-2 at 2 weeks (2.8 ± 0.9 vs. 1.4 ± 0.5-1.9 ± 1.4 mm2 ; 1.4 ± 1.0 vs. 0.6 ± 0.3-0.9 ± 0.5 mm2 ) and without rhBMP-2 at 12 weeks (3.0 ± 0.8 vs. 1.7 ± 0.7-2.6 ± 1.5 mm2 ) (p > 0.05). NB formation did not differ significantly for DBBM and the three types of synthetic block with rhBMP-2 at 12 weeks (4.5 ± 2.0 vs. 3.8 ± 0.7-5.1 ± 1.1 mm2 ; p > 0.05). CONCLUSIONS: rhBMP-2 enhanced NB in all blocks. DBBM blocks yielded more NB than synthetic blocks without rhBMP-2. The application of rhBMP-2 appears to compensate for differences in late healing.

Trueness of ten intraoral scanners in determining the positions of simulated implant scan bodies.

Few investigations have evaluated the 3-dimensional (3D) accuracy of digital implant scans. The aim of this study was to evaluate the performance of 10 intraoral scanners (IOSs) (CEREC Omnicam, CEREC Primescan, CS 3600, DWIO, i500, iTero Element, PlanScan, Trios 2, Trios 3, and True Definition) in obtaining the accurate positions of 6 cylinders simulating implant scan bodies. Digital scans of each IOS were compared with the reference dataset obtained by means of a coordinate measuring machine. Deviation from the actual positions of the 6 cylinders along the XYZ axes and the overall 3D deviation of the digital scan were calculated. The type of IOSs and position of simulated cylindrical scan bodies affected the magnitude and direction of deviations on trueness. The lowest amount of deviation was found at the cylinder next to the reference origin, while the highest deviation was evident at the contralateral side for all IOSs (p < 0.001). Among the tested IOSs, the CEREC Primescan and Trios 3 had the highest trueness followed by i500, Trios 2, and iTero Element, albeit not statistically significant (p > 0.05), and the DWIO and PlasScan had the lowest trueness in partially edentulous mandible digital implant scans (p < 0.001).

Trueness of intraoral scanners in digitizing specific locations at the margin and intaglio surfaces of intracoronal preparations.

STATEMENT OF PROBLEM: Studies evaluating the trueness of intraoral scanners (IOSs) at anatomic locations within an intracoronal preparation are lacking. PURPOSE: The purpose of this in vitro study was to evaluate the trueness of digital scans obtained by IOSs at the margin and intaglio surfaces of intracoronal preparations. MATERIAL AND METHODS: Six IOSs (CEREC Omnicam, E4D, FastScan, iTero, TRIOS, Zfx IntraScan) were used to obtain digital scans of various intracoronal preparations. Standard tessellation language (STL) data sets obtained from a reference scanner and each IOS were superimposed, and the deviation of the digital casts was assessed at multiple measuring points along the margin and intaglio surfaces of each preparation. The Kruskal-Wallis test and multiple Mann-Whitney tests were used to detect differences in trueness (α=.05). RESULTS: The overall median trueness values were lowest for TRIOS (23.9 µm), followed by Zfx IntraScan (24.6 µm), iTero (25.4 µm), FastScan (26.1 µm), CEREC Omnicam (26.9 µm), and E4D (77.5 µm). The greatest deviation was generally observed at the line angles between the preparation surfaces. The axiogingival line angle was the most error-prone location in the cavity preparations. An increased tendency to produce a more accurate impression was observed when the cavity had a greater width and more divergent walls. CONCLUSIONS: The trueness of digital scans was influenced by the type of IOS and the location within a prepared cavity. The trueness decreased at the line angles between the preparation surfaces, particularly at the axiogingival line angle. Among the tested IOSs, E4D produced the least accurate digital scans.

Histologic Outcomes After Guided Bone Regeneration of Peri-implant Defects Comparing Individually Shaped Block Versus Particulate Bone Substitutes.

Peri-implant bone dehiscences were grafted either with deproteinized bovine bone mineral (DBBM) block or with particulate DBBM, both covered with a collagen membrane and stabilized with resorbable pins. After 6 months, 17 biopsy samples were included for histologic assessment. Block and particulate DBBM rendered successful tissue integration. Particulate DBBM showed a median of 25.2% of new bone and 31.3% of bone substitute. In the block group, there was a median of 11.5% of new bone and 36.0% of bone substitute. When interpreting the discrepancy in new bone between the groups, the difference in the size of the augmented hard tissue needs to be taken into account.

Prosthetic outcomes and clinical performance of CAD-CAM monolithic zirconia versus porcelain-fused-to-metal implant crowns in the molar region: 1-year results of a RCT.

OBJECTIVE: To investigate the clinical performance of monolithic zirconia implant crowns as compared to porcelain-fused-to-metal (PFM) implant crowns. MATERIALS AND METHODS: Seventy-six healthy patients received reduced diameter implants in the molar region. Following random allocation, either a monolithic zirconia crown (Mono-ZrO2 ) or a (PFM) was inserted. Crown and implant survival rates, modified USPHS criteria, clinical measurements, and interproximal marginal bone level (MBL) were assessed at crown delivery (baseline, BL) and at the 1-year follow-up (1y-FU). Data were analyzed descriptively. Fisher's exact test and Wilcoxon rank sum test were applied for statistical analysis. The level of statistical significance was set at p < .05. RESULTS: Thirty-nine Mono-ZrO2 and 37 PFM crowns were delivered. At the 1y-FU, one crown in each group was lost due to loss of the implant. Technical complications occurred in the PFM group and were limited to four minor ceramic chippings resulting in a total technical complication rate of 11.1% (p = .024). Anatomical form and color match compared to the adjacent dentition were rated significantly inferior for the Mono-ZrO2 crowns. Patient satisfaction was high in both groups at BL (34 Mono-ZrO2 34 PFM) and at 1y-FU (36 Mono-ZrO2 31 PFM). No significant differences between the groups were detected with respect to the change in MBL and to the soft tissue parameters. CONCLUSIONS: Monolithic zirconia crowns are a similarly successful alternative option to PFM crowns for restoring single implants in the posterior area.

Trueness of digital intraoral impression in reproducing multiple implant position.

The aim of this study was to evaluate the trueness of 5 intraoral scanners (IOSs) for digital impression of simulated implant scan bodies in a partially edentulous model. A 3D printed partially edentulous mandible model made of Co-Cr with a total of 6 bilaterally positioned cylinders in the canine, second premolar, and second molar area served as the study model. Digital scans of the model were made with a reference scanner (steroSCAN neo) and 5 IOSs (CEREC Omnicam, CS3600, i500, iTero Element, and TRIOS 3) (n = 10). For each IOS's dataset, the XYZ coordinates of the cylinders were obtained from the reference point and the deviations from the reference scanner were calculated using a 3D reverse engineering program (Rapidform). The trueness values were analyzed by Kruskal-Wallis test and Mann-Whitney post hoc test. Direction and amount of deviation differed among cylinder position and among IOSs. Regardless of the IOS type, the cylinders positioned on the left second molar, nearest to the scanning start point, showed the smallest deviation. The deviation generally increased further away from scanning start point towards the right second molar. TRIOS 3 and i500 outperformed the other IOSs for partially edentulous digital impression. The accuracy of the CEREC Omnicam, CS3600, and iTero Element were similar on the left side, but they showed more deviations on the right side of the arch when compared to the other IOSs. The accuracy of IOS is still an area that needs to be improved.

Hard tissue changes after guided bone regeneration of peri-implant defects comparing block versus particulate bone substitutes: 6-month results of a randomized controlled clinical trial.

OBJECTIVES: To test whether block bone substitute used for guided bone regeneration (GBR) of peri-implant defects leads to different thickness of the augmented hard tissue than particulate bone substitute. MATERIAL AND METHODS: In 24 patients, 24 two-piece dental implants were placed >4 months after tooth extraction. Following random allocation, 12 peri-implant bone dehiscences were grafted with an individually shaped block of deproteinized bovine-derived bone mineral (DBBM) and 12 bone dehiscences with particulate DBBM. All the sites were covered with a collagen membrane stabilized with resorbable pins. Immediately after wound closure and after 6 months, the horizontal thickness (HT) of the augmented hard tissue was measured at the level of implant shoulder using cone beam-computed tomography. RESULTS: After wound closure, the median HT measured 3.35 mm (mean: 3.38) in the block group and 2.85 mm (mean: 2.73) in the particulate group. At 6 months, the median HT decreased to 2.90 mm (mean: 2.71) in the block group and to 0.2 mm (mean: 0.52) in the particulate group. This difference was statistically significant (p < .001). CONCLUSIONS: Block bone substitute used for GBR of peri-implant defects was superior to particulate bone substitute regarding the dimension of the augmented hard tissue after 6 months of healing.

Load-bearing capacities of ultra-thin occlusal veneers bonded to dentin.

OBJECTIVES: To test whether the load-bearing capacity of occlusal veneers made of ceramic or hybrid materials bonded to dentin does differ from those of porcelain-fused-to metal or lithium disilicate glass ceramic crowns. MATERIAL AND METHODS: In 80 human molars, occlusal tooth substance was removed so that the defects extended into dentin, simulating defects caused by attrition/erosion. Restorations at a standardized thickness of either 0.5 mm or 1.0 mm were digitally designed. For both thicknesses, 4 test groups (n = 10 per group) were defined, each including a different restorative material: "0.5-ZIR": 0.5 mm thick zirconia (Vita YZ HT); "1.0-ZIR": 1.0 mm thick zirconia (Vita YZ HT); "0.5-LDC": 0.5 mm thick lithium disilicate ceramic (IPS e.max Press); "1.0-LDC": 1.0 mm thick lithium disilicate ceramic (IPS e.max Press); "0.5-HYC": 0.5 mm thick PICN (Vita Enamic); "1.0-HYC": 1.0 mm thick PICN (Vita Enamic); "0.5-COC": 0.5 mm thick tooth shaded resin composite (Lava Ultimate) and "1.0-COC": 1.0 mm thick tooth shaded resin composite (Lava Ultimate). Consecutively, the specimens were thermo-mechanically aged and then loaded until fracture. The load-bearing capacities (Fmax) between the groups were statistically compared using the Kruskal-Wallis test (p < 0.05) and pairwise group comparison applying the Dunn's method. In addition, the results were compared to those of conventional lithium-disilicate ceramic crowns ("CLD") and to porcelain-fused to metal crowns ("PFM"). RESULTS: The median Finitial values for the 0.5 mm thin restorations were 1'350 N for 0.5-ZIR, 850 N for 0.5-LDC, 1'100 N for 0.5-HYC and 1'950 N for 0.5-COC. With CLD as the control, a significant difference was found between the groups 0.5-COC and 0.5-LDC (KW: p = 0.0124). With PFM as the control, the comparisons between PFM and 0.5-LDC as well as between 0.5-COC and 0.5-LDC were significant (KW: p = 0.0026). Median Fmax values of 2'493 N in the group 0.5-ZIR, 1'165 in the group 0.5-LDC, 2'275 N in the group 0.5-HYC and 2'265 N in the group 0.5-COC were found. The medians of the Finitial values for the 1.0 thick restorations amounted of 2'100 N in 1.0-ZIR, 1'750 N in 1.0-LDC, 2'000 N in 1.0-HYC and 2'300 N in 1.0-COC. Testing the multiple comparisons with Dunn's method no significant differences were found (p > 0.05). The median Fmax values of the 1.0 mm thick restorations were: 2'489 N in the group 1.0-ZIR, 1'864 N in the group 1.0-LDC, 2'485 N in the group 1.0-HYC and 2'479 N in the group 1.0-COC. With CLD as the control group, a significant difference between zirconia and lithium-disilicate was found for the 0.5 (p = 0.0017) and 1.0 mm (p = 0.0320) thick specimens. Comparing the 0.5 mm thick specimens with CLD as the control, a significant difference was found between 0.5-HYC and 0.5-LDC (p = 0.0017). With PFM as the control, the comparison of lithium disilicate and zirconia was statistically significant for both thicknesses (p = 0.0009 for the 0.5 mm thick specimens; p = 0.0074 for the 1.0 mm thick specimens). In addition, with PFM as control group, significant differences were seen between 0.5-LDC and all other groups with restorations in 0.5 mm thickness (p = 0.0017). CONCLUSIONS: Regarding their maximum load-bearing capacity, minimally invasive occlusal veneers made of ceramic, hybrid materials or polymeric materials can be applied to correct occlusal tooth wear with exposed dentin and thus replace conventional crown restorations in cases of normally expected intraoral bite forces.

Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part I: Time efficiency of complete-arch digital scans versus conventional impressions.

STATEMENT OF PROBLEM: Clinical trials are needed to evaluate digital and conventional technologies for providing fixed partial dentures. PURPOSE: The purpose of the first part of this clinical study was to test whether complete-arch digital scans were similar to or better than complete-arch conventional impressions regarding time efficiency and participant and clinician perceptions. MATERIAL AND METHODS: Ten participants in need of a posterior tooth-supported 3-unit fixed partial denture were included. Three intraoral digital scanners and subsequent workflows (Lava C.O.S.; 3M [Lava], iTero; Align Technology Inc [iTero], Cerec Bluecam; Dentsply Sirona [Cerec]) were compared with the conventional impression method using polyether (Permadyne; 3M) and the conventional workflow. A computer-generated randomization list was used to determine the sequence of the tested impression procedures for each participant. The time needed for the impression procedures, including the occlusal registration, was assessed. In addition, the participant and clinician perceptions of the comfort and difficulty of the impression were rated by means of visual analog scales. Data were analyzed with the nonparametric paired Wilcoxon test together with an appropriate Bonferroni correction to detect differences among the impression systems (α=.05). RESULTS: The total time for the complete-arch impressions, including the preparation (powdering) and the occlusal registration, was shorter for the conventional impression than for the digital scans (Lava 1091 ±523 seconds, iTero 1313 ±418 seconds, Cerec 1702 ±558 seconds, conventional 658 ±181 seconds). The difference was statistically significant for 2 of the 3 digital scanners (iTero P=.001, Cerec P<.001). The clinicians preferred the conventional impression to the digital scans. Of the scanning systems, the system without the need for powdering was preferred to the systems with powdering. No impression method was clearly preferred over others by the participants. CONCLUSIONS: For complete-arch impressions, the conventional impression procedures were objectively less time consuming and subjectively preferred by both clinicians and participants over digital scan procedures.

Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part III: Marginal and internal fit.

STATEMENT OF PROBLEM: Trials comparing the overall performances of digital and conventional workflows in restorative dentistry are lacking. PURPOSE: The purpose of the third part of this clinical study was to test whether the fit of zirconia 3-unit frameworks for fixed partial dentures fabricated with fully digital workflows differed from that of metal frameworks fabricated with the conventional workflow. MATERIAL AND METHODS: In each of 10 participants, 4 fixed-partial-denture frameworks were fabricated for the same abutment teeth according to a randomly generated sequence. Digital workflows were applied for the fabrication of 3 zirconia frameworks with Lava, iTero, and Cerec infiniDent systems. The conventional workflow included a polyether impression, manual waxing, the lost-wax technique, and the casting of a metal framework. The discrepancies between the frameworks and the abutment teeth were registered using the replica technique with polyvinyl siloxane. 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 a light microscope. Post hoc t tests with Bonferroni correction were applied to detect differences (α=.05). RESULTS: Discrepancyshoulder was 96.1 ±61.7 µm for the iTero, 106.9 ±96.0 µm for the Lava, 112.2 ±76.7 µm for the Cerec infiniDent, and 126.5 ±91.0 µm for the conventional workflow. The difference between the iTero and the conventional workflow was statistically significant (P=.029). Discrepancyocclusal was 153.5 ±66.8 µm for the iTero, 203.3 ±127.9 µm for the Lava, 179.7 ±63.1 µm for the Cerec infiniDent, and 148.8 ±66.8 µm for the conventional workflow. Discrepancyocclusal was significantly lower for the conventional workflow than for the Lava and the Cerec infindent workflows (P<.01). The iTero resulted in significantly lower values of Discrepancyocclusal than the Lava and the Cerec infiniDent workflows (P<.01). CONCLUSIONS: In terms of framework fit in the region of the shoulder, digitally fabricated zirconia 3-unit frameworks presented similar or better fit than the conventionally fabricated metal frameworks. In the occlusal regions, the conventionally fabricated metal frameworks achieved a more favorable fit than the CAD-CAM zirconia frameworks.

Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic posterior fixed partial dentures. Part II: Time efficiency of CAD-CAM versus conventional laboratory procedures.

STATEMENT OF PROBLEM: Clinical trials are needed to evaluate the digital and conventional fabrication technology for providing fixed partial dentures (FPDs). PURPOSE: The purpose of the second part of this clinical study was to compare the laboratory production time for tooth-supported, 3-unit FPDs by means of computer-aided design and computer-aided manufacturing (CAD-CAM) systems and a conventional workflow. In addition, the quality of the 3-unit framework of each treatment group was evaluated clinically. MATERIAL AND METHODS: For each of 10 participants, a 3-unit FPD was fabricated. Zirconia was used as the framework material in the CAD-CAM systems and included Lava C.O.S. CAD software (3M) and centralized CAM (group L); CARES CAD software (Institut Straumann AG) and centralized CAM (group iT); and CEREC Connect CAD software (Dentsply Sirona) and centralized CAM (group C). The noble metal framework in the conventional workflow (group K) was fabricated by means of the traditional lost-wax technique. All frameworks were evaluated clinically before veneering. The time for the fabrication of the cast, the 3-unit framework, and the veneering process was recorded. In addition, chairside time during the clinical appointment for the evaluation of the framework was recorded. The paired Wilcoxon test together with appropriate Bonferroni correction was applied to detect differences among treatment groups (α=.05). RESULTS: The total effective working time (mean ±standard deviation) for the dental technician was 220 ±29 minutes in group L, 217 ±23 minutes in group iT, 262 ±22 minutes in group C, and 370 ±34 minutes in group K. The dental technician spent significantly more time in the conventional workflow than in the digital workflow, independent of the CAD-CAM systems used (P<.001). CONCLUSIONS: Irrespective of the CAD-CAM system, the overall laboratory time for the dental technician was significantly less for a digital workflow than for the conventional workflow.

Ultra-thin occlusal veneers bonded to enamel and made of ceramic or hybrid materials exhibit load-bearing capacities not different from conventional restorations.

OBJECTIVES: The objective of this study was to test whether or not the load-bearing capacity of occlusal veneers bonded to enamel and made of ceramic or hybrid materials does differ from those of porcelain-fused-to-metal or lithium disilicate glass ceramic crowns. MATERIAL AND METHODS: In 80 human molars occlusal enamel was removed without extending into the dentin in order to mimic substance defects caused by attrition. The restorations were digitally designed at a standardized thickness of either 0.5 mm or 1.0 mm. For each thickness, 4 test groups were formed each including a different restorative material: "0.5-ZIR": 0.5 mm thick zirconia (Vita YZ HT); "1.0-ZIR": 1.0 mm thick zirconia (Vita YZ HT); "0.5-LDC": 0.5 mm thick lithium disilicate ceramic (IPS e.max Press); "1.0-LDC": 1.0 mm thick lithium disilicate ceramic (IPS e.max Press); "0.5-HYC": 0.5 mm thick PICN (Vita Enamic); "1.0-HYC": 1.0 mm thick PICN (Vita Enamic); "0.5-COC": 0.5 mm thick tooth shaded resin composite (Lava Ultimate) and "1.0-COC": 1.0 mm thick tooth shaded resin composite (Lava ultimate). Each group consists of 10 specimens. Two additional groups of 10 specimens each were used as controls and exhibited conventional crown preparations. In one group the crowns were made of lithium-disilicate ceramic ("CLD": IPS e.max CAD) and the other group consisted of porcelain-fused to metal crowns ("PFM"). All restorations were cemented onto the prepared teeth following the manufacturer's instruction of the corresponding luting cement. Subsequently, they were thermo-mechanically aged and then loaded until fracture. Load-bearing capacities (Fmax) between the groups were compared applying the Kruskal-Wallis test (p < 0.05) and pairwise group comparisons using the Dunn's method. RESULTS: Median values (and quartiles) for the load-bearing capacity amounted to (Fmax) 2'407 (1'670; 2'490) N for the CLD group and to 2'033 (1'869; 2'445) N for the PFM group. For the 0.5 mm thick restorations Fmax reached the highest median value in group 0.5-HYC 2'390 (1'355; 2'490) N, followed by 0.5-COC 2'200 (1'217; 2'492) N and 0.5-LDC 1'692 (1'324; 2'355) N. No results were obtained for group 0.5-ZIR due to the impracticability to fabricate ultra-thin specimens. The distribution of the values for the 1.0 mm thick restorations was 2'489 (2'426; 2'491) N for 1.0-COC, 2'299 (2'156; 2'490) N for 1.0-ZIR, 2'124 (1'245; 2'491) N for 1.0-HYC, and 1'537 (1'245; 1'783) N for 1.0-LDC. The differences of the medians between the test and the control groups did not reach statistical significance for the 0.5 mm thick specimens (KW: p = 0.6952 and p = 0.6986). Within the groups exhibiting 1.0 mm thickness, however, significant different medians were found: 1.0-LDC < 1.0-ZIR and 1.0-LDC < 1.0-COC (KW: p < 0.0209). CONCLUSIONS: Regarding their maximum load-bearing capacity, minimally invasive occlusal veneers made of ceramic and hybrid materials can be applied to correct occlusal tooth wear and thus replace conventional crown restorations.

Assessment of peri-implant defects at titanium and zirconium dioxide implants by means of periapical radiographs and cone beam computed tomography: An in-vitro examination.

OBJECTIVE: To test the accuracy of measurement of interproximal peri-implant bone defects at titanium (Ti) and zirconium dioxide (ZrO2 ) implants by digital periapical radiography (PR) and cone beam computed tomography (CBCT). MATERIAL AND METHODS: A total of 18 models, each containing one Ti and one ZrO2 implant, were cast in dental stone. Six models each were allocated to following defect groups: A-no peri-implant defect, B-1 mm width defect, C-1.5 mm width defect. The defect width was measured with a digital sliding caliper. Subsequently, the models were scanned by means of PR and CBCT. Three examiners assessed the defect width on PR and CBCT. Wilcoxon signed-rank test and Wilcoxon rank sum test were applied to detect differences between imaging techniques and implant types. RESULTS: For PR, the deviation of the defect width measurement (mm) for groups A, B, and C amounted to 0.01 ± 0.03, -0.02 ± 0.06, and -0.00 ± 0.04 at Ti and 0.05 ± 0.02, 0.01 ± 0.03, and 0.09 ± 0.03 at ZrO2 implants. The corresponding values (mm) for CBCT reached 0.10 ± 0.11, 0.26 ± 0.05, and 0.24 ± 0.08 at Ti and 1.07 ± 0.06, 0.64 ± 0.37, and 0.54 ± 0.17 at ZrO2 implants. Except for Ti with defect A, measurements in PR were significantly more accurate in comparison to CBCT (p ≤ 0.05). Both methods generally yielded more accurate measurements for Ti than for ZrO2 . CONCLUSIONS: The assessment of interproximal peri-implant defect width at Ti and ZrO2 implants was more accurate in PR in comparison to CBCT. Measurements in CBCT always led to an overestimation of the defect width, reaching clinical relevance for ZrO2 implants.

Clinical quality and efficiency of monolithic glass ceramic crowns in the posterior area: digital compared with conventional workflows.

PURPOSE: The aim of this clinical study was to test whether or not digital workflows for the fabrication of crowns render different clinical outcomes from the conventional pathway with respect to (1) crown quality, and (2) time efficiency. MATERIAL AND METHODS: For each of the 10 patients in need of one tooth-supported crown, five monolithic crowns were produced out of lithium disilicate reinforced glass ceramic. Four different optical impression and associated computer-aided design/computer-aided manufacturing (CAD/CAM) systems were used for crown fabrication (digital workflows): (1) Lava C.O.S. scanner and Lava C.O.S. and CARES CAD software, centralized CAM (group L); (2) Cadent iTero scanner, CARES CAD software and centralized CAM (group iT); (3) Cerec Bluecam, Cerec Connect CAD software, followed by laboratory-based CAM (group CiL); and (4) centralized CAM (group CiD). The conventional crown (group K) was fabricated based on a conventional silicone impression followed by a conventional wax-up and heat press technique. The examiners were blinded and evaluated the crowns clinically at the bisque-bake stage (initial try-in), and subsequently after finalization by a dental technician (final try-in). For the assessment of crown quality, modified United States Public Health Service (USPHS) criteria were used. Treatment times were recorded for clinical evaluation and adjustment. The quality ratings were analyzed descriptively. For both the continuous and ordinal outcomes, the non-parametric paired Wilcoxon test was applied, together with an appropriate Bonferroni correction to evaluate the differences between treatment groups. The results of the statistical analysis were interpreted globally at the significance level P = 0.05. RESULTS: The clinical evaluation during the initial and final try-ins demonstrated similar clinical outcome measures for crowns generated with the four digital workflows and the conventional workflow. No statistically significant differences of crown quality in any state were found between groups (P > 0.005). The total clinical treatment times measured were: 456 ± 240 s for L; 655 ± 374 s for iT; 783 ± 403 s for CiL; 556 ± 285 s for CiD; and 833 ± 451 s for K. No statistically significant differences in treatment times were found between the groups (P > 0.05). CONCLUSIONS: Within the limitations of the present study, the monolithic ceramic crowns resulting from the four different CAD/CAM systems did not differ from the conventionally produced crowns with respect to the clinical quality rating and the treatment time efficiency.

A Randomized Controlled Clinical Trial Comparing Conventional and Computer-Assisted Implant Planning and Placement in Partially Edentulous Patients. Part 1: Clinician-Related Outcome Measures.

The objectives of this study were to compare conventional and computer-assisted implant planning and placement (CAIPP) protocols regarding surgical planning predictability, intraoperative complications, and patient-centered outcomes. Partially edentulous patients (N = 73) were randomly allocated to one of three treatment groups: control (C, n = 26), with preoperative planning based on conventional radiography and freehand implant placement; and test 1 (T1, n = 24) and test 2 (T2, n = 23), with two different CAIPP protocols. The clinicians' predictions of the bony morphology, materials needed for surgery, and surgery duration were matched with intrasurgical findings using kappa tests. Complications or deviations from the surgical or prosthetic protocol were recorded. Descriptive statistics were used to study the sample sorted out by treatment group. Differences between groups were evaluated with chi-square test for qualitative variables and with nonparametric Kruskal-Wallis test for quantitative continuous variables. For post-hoc tests, the Bonferroni corrected (P < .016 = .05/3) Mann-Whitney test was used. CAIPP protocols showed better diagnostic potential than conventional protocols for the bone topography, need for simultaneous GBR procedures, membrane selection, and implant length predictions. The rate of surgical protocol deviations was similar in all groups, but their nature differed. Conventional protocols showed fewer splint-related incidences. Implant bed preparation and insertion could not be fully completed using the surgical splint in 3.8% of patients in C (1/26), 45.8% in T1 (11/24), and 47.8% in T2 (11/23). Deviation from the initial prosthetic plan was necessary in one case (T2; 4.4%). No biologic or technical complications were observed. CAIPP protocols showed a higher diagnostic potential than conventional protocols. A high incidence of intraoperative surgical protocol modifications to adjust suboptimal implant placements was reported for every group. Therefore, strict intraoperative implant position monitoring is mandatory for both treatment protocols.

Clinical Performance of Dental Implants Following Sinus Floor Augmentation: A Systematic Review and Meta-Analysis of Clinical Trials with at Least 3 Years of Follow-up.

PURPOSE: The purpose of this systematic review was to assess the survival of implants placed in augmented sinuses on a medium- to long-term basis, and identify factors affecting implant survival such as surgical technique, bone grafts, and timing of implant placement. MATERIALS AND METHODS: A literature search up to July 2016 was performed to identify prospective clinical studies on sinus floor augmentation in conjunction with implant placement with a minimum follow-up of 3 years. Meta-analytic methods were implemented to calculate implant survival rates and relative risks (RR) for failure and the effect of surgical technique, use of bone graft, graft type, use of membrane, mean residual bone height, and timing of implant insertion. RESULTS: A total of 17 clinical trials (1 randomized and 16 prospective nonrandomized) were included, which pertained to 637 patients (at least 48% male) and 1,610 implants placed after sinus floor augmentation with the osteotome (transalveolar) or lateral window approach. The pooled implant survival rate at 3 to 6 years of follow-up was 97.7% (17 studies; 95% CI = 94.4% to 99.7%) with high heterogeneity. Smoking was associated with significantly worse implant survival (2 studies; RR = 4.8; 95% CI = 1.2 to 19.4; P < .05). However, evidence of influencing factors varied from very low to moderate after adopting the GRADE approach, due to risk of bias, imprecision, inconsistency, and small-study effects. CONCLUSION: Current evidence suggests that implants in augmented sinuses have high survival rates, with smoking playing a potentially important negative role in their prognosis. Both indirect and direct maxillary sinus floor augmentation seem to have a low frequency of manageable complications.