Clinical performance and risk factors of all-ceramic screw-retained implant crowns in the posterior region based on a retrospective investigation.

OBJECTIVES: Clinical data on all-ceramic screw-retained implant crowns (SICs) luted on titanium base abutments (TBAs) over more than 3 years are sparse. This study aimed to evaluate the clinical performance and potential risk factors for these restorations. MATERIALS AND METHODS: Analysis took place based on the medical patient-records of three dental offices. Implant survival and prosthetic complications over time were evaluated. The study included SICs in premolar and molar regions made from monolithic lithium disilicate ceramic (M_LiDi) or veneered zirconia (V_ZiO) luted on a TBA documented over an observation time of at least 3 years. Survival and complication rates were calculated and compared by a log-rank test. Cox-Regressions were used to check potential predictors for the survival (p < .05). RESULTS: Six hundred and one crowns out of 371 patients met the inclusion criteria and follow-up period was between 3.0 and 12.9 (mean: 6.4 (SD: 2.1)) years. Over time, six implants had to be removed and 16 restorations had to be refabricated. The estimated survival rates over 10 years were 93.5% for M_LiDi and 95.9% for V_ZiO and did not differ significantly among each other (p = .80). However, V_ZiO showed significantly higher complication rates (p = .003). Material selection, sex, age, and implant diameter did not affect the survival of investigated SICs but crown height influences significantly the survival rate (hazard ratio, HR = 1.26 (95%CI: 1.08, 1.49); p = .043). CONCLUSIONS: Screw-retained SICs luted on TBAs that were fabricated from monolithic lithium disilicate ceramic or veneered zirconia showed reliable and similar survival rates. Increasing crown heights reduced survival over the years.

CAD/CAM full-mouth rehabilitation of an elderly patient: One-piece digital complete denture meets multilayered zirconia with gradient technology.

OBJECTIVE: This article highlights a CAD/CAM complete-mouth rehabilitation in an 82-year-old patient by means of a complete maxillary prosthesis and mandibular implant- and tooth-supported fixed restorations made from multilayered zirconia. CLINICAL CONSIDERATIONS: Comprehensive complete-mouth rehabilitations in elderly patients with adaptation of the occlusal vertical dimension (OVD) often present particular challenges. This applies especially when exacting functional and esthetic requirements are to be met and the treatment should not cause the patient too much effort, still ensuring the highest level of quality and efficiency and a low intervention rate. CONCLUSION: The digital approach used for the present patient allowed for an efficient treatment procedure, facilitated virtual evaluations using a face-scan, and enhanced the predictability of the prosthodontic outcome. The approach enabled some steps required in the conventional protocol to be omitted, resulting in a straightforward clinical treatment with minimal strain on the patient. CLINICAL SIGNIFICANCE: Because of the comprehensive recording of extraoral and intraoral data, for example with a facial scanner, it was possible to transfer a digital replica of the patient to the dental laboratory technician. With this protocol, many steps can be performed in the absence of the real patient.

Clinical, radiographic, and histological/histomorphometric analysis of maxillary sinus grafting with deproteinized porcine or bovine bone mineral: A randomized clinical trial.

OBJECTIVE: The present study aimed to compare histomorphometrically evaluated new bone formation, radiographically measured graft stability, and clinical implant outcome between maxillary sinus grafting with either deproteinized porcine bone mineral (DPBM) or deproteinized bovine bone mineral (DBBM). MATERIALS AND METHODS: Thirty maxillary sinuses were initially included and randomly assigned to the test group (TG; DPBM, n = 15) or control group (CG; DBBM, n = 15). After a healing period (6 months), axially retrieved bone biopsies of the molar region were used for histological/histomorphometric analysis of new bone formations. Additionally, radiographically measured graft stability and clinical implant outcome were assessed. RESULTS: Twenty-three sinus sites with 10 sinuses of the TG and 13 of the CG were ultimately available for data and statistical analysis. In the TG, a slightly, but yet significantly (p = .040) higher proportion of new bone formation (TG: 27.7 ± 5.6% vs. CG: 22.9 ± 5.1%) and a lesser (p = .019) amount of connective (non-mineralized) tissue (TG: 47.5 ± 9.5% vs. CG: 56.1 ± 9.5%) was found than in the CG. However, both xenografts showed comparable (n.s.) residual bone graft (TG: 23.7 ± 7.2% vs. CG: 21.1 ± 9.85.6%), bone-to-graft contacts (TG: 26.2 ± 9.8% vs. CG: 30.8 ± 13.8%), similar graft height reduction over time (TG: 12.9 ± 6.7% CG: 12.4 ± 5.8%) and implant survival/success rate (100%). At the 3-year post-loading evaluation, the peri-implant marginal bone loss (TG: 0.52 ± 0.19 mm; CG: 0.48 ± 0.15 mm) and the peri-implant health conditions (TG: 87.5%/CG: 81.2%) did not differ between implants inserted in both xenografts used. CONCLUSIONS: The use of DPBM or DBBM for maxillary sinus augmentation is associated with comparable bone formation providing stable graft dimension combined with healthy peri-implant conditions.

Transsinusoidal lateral nasal floor augmentation for implant placement in the atrophic premaxilla: A within-patient, 5-year, prospective comparative study.

OBJECTIVES: To evaluate the clinical outcome for implants placed with transsinusoidal-lateral nasal cavity augmentation (NA) compared to implants placed in maxillary sinus augmentation (SA). MATERIALS AND METHODS: In 28 atrophic edentulous maxillary regions (14 patients bi-maxillary), a lateral window approach was used to perform transsinusoidal-lateral NA (TSLNA) combined with maxillary SA. After healing period of about 6 months, each patient received bimaxillary one anterior implant located in the pre-maxilla having lateral NA and 2-3 implants in the maxillary posterior region with SA. In a prospective follow-up evaluation, clinical implant outcome (survival/success rates) and peri-implant health (mucositis/peri-implantitis) were assessed and compared between implants placed in TSLNA (n = 28) and SA (n = 58). RESULTS: At the year-1, year-3, and year-5 evaluation, neither patient-based nor implant-based comparisons revealed differences for marginal bone level reduction between implants placed in TSLNA (5-year overall: 1.11 ± 0.26 mm) and SA (5-year overall: 1.07 ± 0.30 mm), although with a significant (p < .001) continuous reduction over the observation time. At the year-5 evaluation, all implants (n = 86) and restorations (n = 14) were still in situ (survival 100%) and showed an implant-based incidence of peri-implant mucositis/peri-implantitis of 14.3%/0% in TSLNA and 6.9%/3.4% in SA corresponding to 21.4%/0% and 28.6%/7.1% for implant-based evaluation. In addition, the implant success rate did not differ between NA and SA at implant- (100%/ 98.8%) and patient-based (100%/97.6%) evaluation. CONCLUSION: The findings obtained show TSLNA as an effective method for implant placement of adequate length and direction in the atrophic premaxilla providing for success rates comparable to those of implants placed in SA.

Biomechanical behavior of implants with different diameters in relation to simulated bone loss- an in vitro study.

OBJECTIVES: Bone resorption around implants could influence the resistance of the implant abutment complex (IAC). The present in vitro study aimed to assess the stability to static fatigue of implants presenting different levels of bone losses and diameters. MATERIALS AND METHODS: Ninety implants with an internal conical connection with 3 different implant diameters (3.3 mm (I33), 3.8 mm (I38), and 4.3 mm (I43)) and 3 simulated bone loss settings (1.5 mm (I_15), 3.0 mm (I_30), and 4.5 mm (I_45) (n = 10)) were embedded and standard abutments were mounted. All specimens were artificially aged (1,200,000 cycles, 50 N, simultaneous thermocycling) and underwent subsequently load-to-fracture test. For statistical analysis, Kolmogorov-Smirnov test, Kruskal-Wallis test, and Mann-Whitney U test (p < 0.05) were applied. RESULTS: All test specimens withstood the artificial aging without damage. The mean failure values were 382.1 (± 59.2) N (I3315), 347.0 (± 35.7) N (I3330), 315.9 N (± 30.9) (I3345), 531.4 (± 36.2) N (I3815), 514.5 (± 40.8) N (I3830), 477.9 (± 26.3) N (I3845), 710.1 (± 38.2) N (I4315), 697.9 (± 65.2) N (I4330), and 662.2 N (± 45.9) (I4345). The stability of the IACs decreased in all groups when bone loss inclined. Merely, the failure load values did not significantly differ among subgroups of I43. CONCLUSIONS: Larger implant diameters and minor circular bone loss around the implant lead to a higher stability of the IAC. The smaller the implant diameter was, the more the stability was affected by the circumferential bone level. CLINICAL RELEVANCE: Preserving crestal bone level is important to ensure biomechanical sustainability at implant systems with a conical interface. It seems sensible to take the effect of eventual bone loss around implants into account during implant planning processes and restorative considerations.

Forced surgical extrusion using an axial tooth extraction system as a practicable technique for preserving severely destroyed teeth? - Clinical outcomes up to 4.8 years.

OBJECTIVE: Several extrusion techniques have been described to restore teeth with insufficient coronal tooth structure and to avoid their extraction. Still, there is little evidence for a treatment concept combining surgical extrusion using an atraumatic axial extraction system. MATERIALS AND METHODS: A total of nine patients, each with an iso- or subgingival fractured tooth, were retrospectively examined. Treatment of the damaged tooth comprised an atraumatic forced surgical extrusion performed with an axial tooth extraction system and a more coronal positioning within the socket. The teeth were initially splinted and subsequently restored. The follow-up period was up to 57.1 months and averaged 36.5 (SD: ±13.5) months. RESULTS: All nine teeth were still in situ, without signs of inflammation. During the period of the provisional restoration, six prosthetic complications occurred, which were resolved with little effort, whereas, success rate for the definitive restoration was 100%. No biological complications were observed concerning the root apex or soft tissue. The radiographically measured mean extrusion distance was 3.4 (SD: ±1.0) mm, so that a sufficient prosthetic ferrule could be reestablished. CONCLUSIONS: Surgical extrusions using an axial tooth extraction system demonstrate low biological and prosthetic complications rates over observation time. CLINICAL SIGNIFICANCE: The presented extrusion approach preserves soft and hard tissue and is an efficient treatment option for severely destroyed teeth. Saving hopeless teeth by this relatively predictable and feasible procedure has hardly any disadvantages for patients, and in case of failure, an implant or fixed partial denture are still an option.

Immediately loaded implants simultaneously placed in fresh extraction and healed sites supporting four-implant-supported fixed mandibular prostheses using the all-on-4 concept: A 5-year prospective study.

OBJECTIVES: To evaluate the peri-implant marginal bone level for immediately loaded implants placed simultaneously in both fresh extraction sites (FES) and healed sites (HS) supporting a 4-implant supported mandibular fixed prosthesis (4-ISFMP) using the all-on-4 concept. MATERIAL AND METHODS: A 5-year prospective study was conducted in 24 patients (96 implants) treated with 4-ISFMP including 55 implants inserted in FES and 41 implants in HS. At implant placement (baseline) and at the 1st -, 3rd - and 5th -year follow-up examinations, peri-implant marginal bone level was evaluated radiographically and compared between placement in FES and HS. Marginal bone loss was calculated as the difference in the marginal bone level evaluated at the follow-up periods. Additionally, implant and prosthesis survival rates as well as the presence of peri-implant mucositis (bleeding on probing+[BOP]) and peri-implantitis (BOP+ >2 mm MBL) were evaluated. RESULTS: 22/24 patients with 88/96 implants (dropout rate: 8.3%) were continually followed for 5 years (survival rate: 100%). Radiographically measured marginal bone level differed significantly between FES and HS at implant placement (1.46 ± 0.80 mm vs. 0.60 ± 0.70 mm; p < .001), at the 1-year (-0.04 ± 0.14 mm vs. -0.18 ± 0.20 mm; p = .002) and 3-year (-0.26 ± 0.49 mm vs. -0.58 ± 0.48 mm, p = .049), but not at the 5-year evaluation (-0.90 ± 0.66 mm vs. -1.00 ± 0.59 mm, p = .361). The marginal bone loss differed significantly (p < .001) between FES and HS between implant placement and the 1-year evaluation but not for the 1- to 3-year (p > .99) and the 3- to 5-year period (p = .082). At the 5-year follow-up evaluation, no implant/prosthesis failed (100% survival) and peri-implant mucositis and peri-implantitis were noted in 41.2% and 11.7% at patient level and in 17.6% and 4.5% at implant level respectively. CONCLUSION: Implants placed in FES showed a prolonged peri-implant remodelling process but provided for similar peri-implant marginal bone levels as implants placed in HS at the 5-year evaluation for immediately loaded 4-ISFMP.

Immediate loading of a fixed full-arch prosthesis on four template-guided implants.

BACKGROUND: Treatment of the edentulous maxilla with a fixed full-arch prosthesis on four immediately loaded implants has been discussed as a treatment option, although generally five implants are recommended for that indication. The precise transfer of the virtually planned position by 3D-guided implant placement is an essential prerequisite for delivering the prefabricated temporary restoration at the time of surgery. Three-point support on the teeth or implants ensures that the template for the guided surgery is soundly seated during the operation. CASE PRESENTATION: In the described case, the three-point support was carried out by teeth and temporary implants in the molar region inserted prior to the CBCT. The virtual implant planning determined the best prosthetic implant position while using the available bone to avoid extensive augmentation. Following this, a metal-reinforced provisional restoration was prepared using a drilling template. Four implants were placed in the planned position with the aid of a tooth-/implant-supported guide. The prosthetic axis of the angulated distal implants is balanced by 17-degree angled abutments. After transferring the implant position to the dental laboratory, the prepared restoration was finalized. The remaining teeth were extracted and the temporary restoration was delivered 3 h after implant placement. The definitive fixed full-arch zirconia restoration with micro layering was placed 9 months later in a stable situation. CONCLUSION: The remarkable accuracy of the implant placement with a surgical template generated from preoperative virtual implant planning ensures a relatively short treatment time and an uneventful and fast recovery with minimal discomfort. The immediate prosthodontic rehabilitation is a benefit, not only for the patient but also for the dental team. Micro-layered monolithic zirconia seems to be a promising option for screw-retained full-arch prostheses.

Mechanical stability of all-ceramic abutments retained with three different screw materials in two-piece zirconia implants-an in vitro study.

OBJECTIVES: To measure the abutment rotation and fracture load of two-piece zirconia implants screwed with three different abutment screw materials. MATERIAL AND METHODS: Thirty-six zirconia implants with 36 zirconia abutments were distributed into 3 test groups: group G connected with gold screws, group T with titanium screws, and group P with peek screws. In the first part of the study, the rotation angle of the abutments was measured. The second part of the study measured the maximum fracture force of adhesively bonded lithium disilicate crowns after artificial aging and fracture modes were reported. RESULTS: In group G, the median rotation angle was 8.0°, in group T 11.6°, and in group P 9.5°. After artificial aging, no screw loosening, crown, abutment, or implant fracture occurred. The median fracture force in group G was 250 N, in group T 263 N, and in group P 196 N. CONCLUSIONS: Rotation angles and fracture loads of two-piece zirconia implants with gold, titanium, or peek screws showed no significant differences; however, fracture loads showed inferior results for group P. CLINICAL RELEVANCE: The indication for the material peek as an abutment screw is still questionable and should be considered carefully.

Accuracy of five intraoral scanners compared to indirect digitalization.

OBJECTIVES: Direct and indirect digitalization offer two options for computer-aided design (CAD)/ computer-aided manufacturing (CAM)-generated restorations. The aim of this study was to evaluate the accuracy of different intraoral scanners and compare them to the process of indirect digitalization. MATERIAL AND METHOD: A titanium testing model was directly digitized 12 times with each intraoral scanner: (1) CS 3500 (CS), (2) Zfx Intrascan (ZFX), (3) CEREC AC Bluecam (BLU), (4) CEREC AC Omnicam (OC) and (5) True Definition (TD). As control, 12 polyether impressions were taken and the referring plaster casts were digitized indirectly with the D-810 laboratory scanner (CON). The accuracy (trueness/precision) of the datasets was evaluated by an analysing software (Geomagic Qualify 12.1) using a "best fit alignment" of the datasets with a highly accurate reference dataset of the testing model, received from industrial computed tomography. RESULTS: Direct digitalization using the TD showed the significant highest overall "trueness", followed by CS. Both performed better than CON. BLU, ZFX and OC showed higher differences from the reference dataset than CON. Regarding the overall "precision", the CS 3500 intraoral scanner and the True Definition showed the best performance. CON, BLU and OC resulted in significantly higher precision than ZFX did. CONCLUSIONS: Within the limitations of this in vitro study, the accuracy of the ascertained datasets was dependent on the scanning system. The direct digitalization was not superior to indirect digitalization for all tested systems. CLINICAL RELEVANCE: Regarding the accuracy, all tested intraoral scanning technologies seem to be able to reproduce a single quadrant within clinical acceptable accuracy. However, differences were detected between the tested systems.

Fracture resistance of different implant abutments supporting all-ceramic single crowns after aging.

OBJECTIVE: To test the mechanical properties of three different restorative materials for implant abutments supporting all-ceramic single crowns. MATERIALS AND METHODS: Thirty implants with butt-joint connections were distributed into three test groups: Group A with 10 one-piece zirconia abutments, Group U with 10 titanium abutments, and Group T with 10 titanium-zirconia hybrid abutments. Monolithic zirconia single crowns were cemented and artificially aged. The crowns were loaded at a 30-degree angle in a universal testing machine until fracture or bending. Additionally, after removal of the restorations, the implant-abutment interface of the fixtures was inspected using a scanning electron microscope (SEM). RESULTS: In Group A, the abutments failed on average at 336.78 N, in Group U at 1000.12 N, and in Group T at 1296.55 N. The mean values between Groups T and U (P = 0.009), and between Group A and Groups T and U (P < 0.001) were significantly different. The abutments in Group A failed early due to fractures of the internal parts and parts close to the implant neck. In Groups T and U, failures occurred due to bending of the implant neck. CONCLUSION: This experimental study proves that hybrid and titanium abutments have similar mechanical properties. One-piece abutments made of zirconia showed significantly lower fracture resistance.

Load bearing capacity, fracture mode, and wear performance of digitally veneered full-ceramic single crowns.

OBJECTIVES: Computer-aided technologies can help to minimize clinical complications of zirconia-based restorations such as veneering porcelain fractures. The aim of this study was to evaluate different veneering approaches for zirconia single crowns regarding contact wear, fracture strength, and failure mode. METHODS: Six different types of computer-aided design (CAD) crowns were manufactured and conventionally cemented on 10 metal dies each: three groups with a zirconia framework and a CAD/CAM-fabricated veneering cap ("digital veneering system": DVS, CAD-on, Infix CAD), zirconia-based crowns with pressed veneering caps (Infix Press), zirconia framework containing the dentin layer with only the incisal enamel material added (dentin-core), and conventional substructure with powder buildup veneering porcelain (layering technique). All specimens were submitted to artificial aging (120,000 mechanical cycles, 50 N load, 0.7-mm sliding movement, 320 thermocycles). After contact wear was measured with a laser scanning system, fracture resistance and failure mode were examined using a universal testing machine and a scanning electron microscope. Statistical analysis was performed at a significance level of 5%. RESULTS: No statistical difference was revealed regarding the contact wear of the restorations (P = 0.171; ANOVA). No significant difference was found regarding the fracture resistance of the crowns (P = 0.112; ANOVA). Failure analysis revealed three different failure patterns: cohesive veneering fracture, adhesive delamination, and total fracture, with a characteristic distribution between the groups. SIGNIFICANCE: All tested specimens survived artificial aging and exhibited clinically acceptable wear resistance and fracture resistance. Digital veneering techniques offer a promising, time- and cost-effective manufacturing process for all-ceramic restorations and may usefully complement the digital workflow.

Accuracy and reproducibility of four cone beam computed tomography devices using 3D implant-planning software.

OBJECTIVE: To measure the deviations of four different cone beam computed tomography (CBCT) devices in three dimensions by means of a three-dimensional (3D) implant-planning program. MATERIALS AND METHODS: A master radiographic template with two vertical, two transverse, and two sagittal radiopaque markers was fabricated for a human dry skull. The lengths of the markers were measured with a high-precision caliper. The skull and the template were scanned in each of the four CBCT devices (1. Gendex GXCB-500; 2. Sirona Galileos Comfort; 3. Sirona Orthophos XG 3D; 4. Carestream CS 9300) 19 times (10 scans without moving the skull, and 9 scans with repeated repositioning of the skull in the device, according to the manufacturers' instructions). A 3D implant-planning program was used to measure the lengths of the six markers digitally. Actual and digital measurements were compared to determine device-specific errors. The repositioning of the skull examined the reproducibility of the CBCT devices. Linear measurements were analyzed statistically (P < 0.05). RESULTS: Mean deviations without moving the skull (vertical/sagittal/transverse) for device 1 were 0.023 mm/0.000 mm/0.025 mm (0.07%/0.19%/0.24%), for device 2 were 0.410 mm/0.115 mm/0.080 mm (-1.75%/0.32%/0.88%), for device 3 were -0.665 mm/-0.215 mm/-0.675 mm (-2.71%/-1.82%/-4.42%), and for device 4 were -0.045 mm/-0.135 mm/-0.410 mm (-0.45%/-1.54%/-2.57%). The overall mean deviation for device 1 was 0.028 mm (0.16%), for device 2 was 0.072 mm (-0.95%), for device 3 was 0.518 mm (-2.97%), and for device 4 was -0.197 mm (-1.53%). The mean deviation after repositioning for device 1 was 0.004 mm (-0.65%), for device 2 was -0.250 mm (0.95%), for device 3 was 0.496 mm (-2.66%), and for device 4 was -0.265 mm (-1.92%). Thus, apart from device 3, the deviations increased. CONCLUSION: Deviations from the actual measurements were detected with each device. Therefore, respecting safety distances when placing implants is crucial.

Precise Placement of Single-Retainer Resin-Bonded Fixed Dental Prostheses with an Innovative Splint Design.

Single-retainer resin-bonded fixed dental prostheses (RBFDPs) are difficult to position due to the pressure of soft tissue at the pontic area and the single-retainer design. This clinical report describes an innovative technique for the insertion of single-retainer RBFDPs. An incisal inserting splint is used to position the RBFDPs reliably. With the help of grooves in the buccal and incisal area of the splint, the precise positioning of the splint on the adjacent teeth and the RBFDP can be controlled. Also, a hole in the retainer wing region of the splint gives access for pressure application on the wing during the bonding process. With the aid of this method, 25 single-retainer FBFDPs were inserted in the correct position in a case series. The splint described here allows the precise insertion of single-retainer RBFDPs and simplifies delivery.

Factors affecting peri-implant bone resorption in four Implant supported mandibular full-arch restorations: a 3-year prospective study.

BACKGROUND: Peri-implant marginal bone-level (MBL) alteration represents one of the parameters included in the criteria for determining implant health. OBJECTIVE: Factors affecting peri-implant MBL alteration for 4-implant-supported fixed mandibular prostheses (4-ISFMP) were assessed. MATERIAL & METHODS: A 3-year prospective, cohort study was conducted on 44 mandibularly edentulous patients treated with 4-ISFMP. Peri-implant MBL alteration was evaluated radiographically at the 12-, 24- and 36-month follow-ups considering to patient-related risk factors [age, gender, diabetes mellitus, smoking, cardiovascular disease (CVD), rheumatic disorders (RD)] and implant/prosthesis-related features (implant location, keratinized gingiva, denture cantilever length, prosthesis supporting zone, opposing dentition) as well as to peri-implant biological parameters (plaque-, bleeding-, calculus index). RESULTS: 148/176 implants (37 patients, drop-out: 15%) were followed for 3 years showing significant (p < 0.001) annual differences of MBL alterations over time. The univariate analysis demonstrated differences of MBL alterations for smokers (p = 0.014), for patients with CVD (p = 0.001) and RD (p = 0.011). In the 3-year multivariate analysis, MBL alteration was influenced by time (p < 0.001) and showed relationship with risk factors as smoking (p < 0.002; OR = 18.965), CVD (p < 0.021; OR = 5.172), RD (p < 0.006; OR = 50.171) and plaque-index (p = 0.034; OR = 3.252). CONCLUSIONS: Although peri-implant MBL alteration increased annually, significant odds ratios, were found for patients-related risk factors identifying them potentiating the alterations.

Tooth-implant-supported posterior fixed dental prostheses with zirconia frameworks: 3-year clinical result.

OBJECTIVES: This case series compared the clinical survival of tooth-implant-supported (TI-S) and tooth-supported (T-S) three-unit fixed dental prostheses (FDPs) with zirconia frameworks and described the incidence of biological and technical complications. MATERIALS AND METHODS: Forty-four patients received 27 TI-S FDPs and 22 T-S FDPs. Twenty-seven titanium screw implants were inserted at the dislodged position of two missing posterior teeth. All implants were provided with customized zirconia abutments. Zirconia frameworks were fabricated by a CAD/CAM system and veneered in powder build-up technique. All restorations were cemented with glass ionomer. Baseline evaluation was performed 2 weeks after cementation with recall examinations performed at 6, 12, 24 and 36 months by calibrated investigators. Survival probabilities according to Kaplan-Meier were calculated. Gingival parameters and bone loss were assessed and statistically evaluated. RESULTS: The mean service time of the FDPs was 35 months (±6). Two technical complications (fracture of veneering porcelain) were observed. One biological complication was recorded. The Kaplan-Meier survival probability was 93.9 % for all types of complications and 100 % related to restorations in service. The type of abutment support (TI-S vs. T-S) had no significant influence on the survival probability (p = 0.412, log rank test). No difference of the gingival parameters was detected between implants and natural teeth. CONCLUSIONS: Tooth-implant-supported zirconia-based FDPs showed similar clinical performance compared to tooth-supported zirconia-based FDPs. CLINICAL RELEVANCE: Within the limitations of this case series, tooth-implant-supported FDPs with zirconia frameworks seem to be a reliable treatment option.

Transmission of light in the visible spectrum (400-700 nm) and blue spectrum (360-540 nm) through CAD/CAM polymers.

OBJECTIVES: CAD/CAM-fabricated long-term temporary restorations from high-density polymers can be applied for a wide range of indications. Milled from monolithic, mono-colored polymer blocks, the translucency of the material plays an important role for an esthetically acceptable result. The aim of this study was to compare the transmittance through visible light and blue light of CAD CAM polymers to a glass-ceramic material of the same color. MATERIALS AND METHODS: Ambarino High-Class (AM), Telio-CAD (TC), Zenotec PMMA (ZT), Cercon base PMMA (CB), CAD Temp (CT), Artbloc Temp (AT), Polycon ae (PS), New Outline CAD (NC), QUATTRO DISK Eco PMMA (GQ), Lava Ultimate (LU), and Paradigm MZ 100 (PA) were employed in this study using the feldspathic glass-ceramic Vita Mark II (MK) as control group. Using a spectrophotometer, the overall light transmittance was measured for each material (n = 40) and was calculated as the integration (t c (λ) dλ [10-5]) of all t c values for the wavelengths of blue light (360-540 nm). Results were compared to previous data of the authors for visible light (400 to 700 nm). RESULTS: Wilcoxon test showed significant differences between the light transmittance of visible and blue light for all materials. CONCLUSION: CAD/CAM polymers showed different translucency for blue and visible light. This means clinicians may not conclude from the visible translucency of a material to its permeability for blue light. This influences considerations regarding light curing. CLINICAL RELEVANCE: CAD/CAM polymers need to be luted adhesively; therefore, clinicians should be aware about the amount of blue light passing through a restoration.

Fit of 4-unit FDPs from CoCr and zirconia after conventional and digital impressions.

OBJECTIVES: To evaluate the marginal and internal fit of CAD/CAM-generated frameworks for 4-unit, fixed dental prostheses (FDPs) from zirconia (Z) and cobalt-chromium alloy (C) made with conventional (CI) and digital impressions (DI). MATERIALS AND METHODS: A titanium model was digitized with an intraoral scanner (DI, LAVA™ C.O.S.; 3M ESPE; Seefeld, Germany; n = 12). Additionally, 12 conventional impressions were taken, and referring plaster casts were digitized by a laboratory-scanner (CI, LAVA™ Scan ST; 3M ESPE; n = 12). Frameworks were fabricated (3M ESPE) from cobalt-chromium (DI-C, n = 12; CI-C, n = 12) and zirconia (DI-Z, n = 12; CI-Z, n = 12) from the same datasets. A replica technique was applied to measure the accuracy. The Mann-Whitney U statistical test was applied to detect statistical differences between each material and methodology groups in terms of fit. RESULTS: Frameworks from DI-C (median 19.07 µm) showed significantly better marginal fit than CI-C (median 64.64 µm, p < 0.001). Frameworks from DI-Z (median 52.50 µm) showed significantly better marginal fit than CI-Z (median 72.94 µm, p = 0.001). Additionally, frameworks from DI-C showed a significantly better marginal fit than DI-Z (p < 0.001). CONCLUSIONS: CI and DI led to a clinically acceptable marginal fit of 4-unit FDPs from cobalt-chromium and zirconia. DI leads to better marginal fit of the cobalt-chromium frameworks; however, no effect on zirconia was found. CLINICAL RELEVANCE: The results indicate that DI is suitable for fabricating 4-unit, cobalt-chromium and zirconia frameworks with regard to fit requirements.

Implant Impression Techniques for the Edentulous Jaw: A Summary of Three Studies.

PURPOSE: Precise implant-supported restorations require accurate impressions. Transfer, pick-up, and splinted pick-up are commonly used techniques. Several in vitro studies have compared these impression techniques; however, all studies used mechanical evaluation methods. The purpose of this study was to compare the discrepancies of these impression techniques digitally in vitro and in vivo. MATERIALS AND METHODS: Four dental implants were inserted in ten polymer mandibular models bilaterally in the regions of the first molars and canines. Three different impressions were made of each model and the models (original and stone casts) were scanned and digitized. Clinically, four implants were inserted in ten edentulous jaws; transfer and splinted pick-up impressions were made. With inspection software, discrepancies between the different impressions were calculated. RESULTS: The mean discrepancies in the in vitro study of the original polymer model to stone casts were 124 ± 34 µm for the transfer type, 116 ± 46 µm for the pick-up type, and 80 ± 25 µm for the splinted pick-up type, resulting in a mean discrepancy between the transfer and splinted pick-up type of 44 µm (124 - 80 µm). Clinically, the mean discrepancy between these two impression techniques was 280 µm. CONCLUSIONS: The differing results between the transfer and splinted pick-up techniques of in vitro and in vivo data showed the need for clinical data; however, splinted pick-up impressions seemed to produce the most precise results.