Influence of Platform-Switched Restoration on Bone Resorption in Patients Treated with Wide-Diameter, External-Hex-Connection Dental Implants: A 10-Year Follow-up Study.

Purpose: To investigate and assess the differences in crestal bone loss (CBL) between wide-diameter, external-hexagon-connection implants restored with platform-switching (PS) and platform-matching (PM) restorations with a follow-up of 10 years. Materials and Methods: This study retrospectively analyzed the updated and enlarged dataset of a 5-year prospective clinical study at 10-year follow-up. The data concerns 182 healthy adult subjects treated in a private dental practice who received a single wide-diameter implant with an external hexagon connection in the molar area, restored with either a PS restoration (test) or PM restoration (control). The amount of CBL was radiographically measured at each annual follow-up, as well as after 5 and 10 years of implant loading. In evaluating the association between the two types of abutments and bone loss (including change over time), a linear mixed effects model was run for longitudinal data. Results: Implants connected with PS restorations exhibited significantly lower reduction (0.25 mm) in CBL than those joined to PM restorations (P < .001; 95% CI from 0.22 to 0.29). However, both groups presented a higher increase in bone loss during the first year (0.58 mm in PS and 0.83 mm in PM) and a linear increment thereafter until the 10-year follow-up (0.046 mm/year; P < .001; 95% CI from .042 to .049). Conclusion: Notwithstanding the limitations of this study, it can be concluded that after 10 years of follow-up, the implant with a wide diameter and external-hexagon connection restored with a PS abutment seems to be more effective in reducing bone loss compared with the PM abutment.

Incorporating a facial scanner into the digital workflow: A dental technique.

The transfer of extraoral and intraoral clinical information into the virtual environment is necessary to optimize prosthetic treatment planning. The purpose of this article was to describe a digital workflow designed to superimpose the different 3D files obtained with an intraoral scanner, a cone bean computed tomography (CBCT) device, and a facial scanner and their clinical application with the Digital bite device.

Influence of ceramic firing on marginal gap accuracy and metal-ceramic bond strength of 3D-printed Co-Cr frameworks.

STATEMENT OF PROBLEM: The marginal gap and ceramic bond strength of metal-ceramic restorations are important for success. However, studies evaluating the marginal gap and ceramic bond strength of fixed partial dentures (FPDs) produced with 3D printing technologies such as selective laser melting (SLM) are scarce. PURPOSE: The purpose of this in vitro study was to investigate the marginal gap of cobalt-chromium (Co-Cr) alloy frameworks produced by SLM technology before and after ceramic firing. Additionally, the metal-ceramic bond strength was evaluated with the Schwickerath crack-initiation test according to the International Standards Organization (ISO) 9693-1:2012. MATERIAL AND METHODS: Conventional impressions were made, and the definitive cast of a patient requiring a 4-unit FPD was scanned. After designing the FPD, the files were sent to a service center for the fabrication of a metal master model, 80 Co-Cr frameworks, and 80 flat specimens (25×3×0.5 mm) with SLM technology. The marginal gap between frameworks and the abutment tooth of the metal master model was nondestructively measured by using an optical coordinate-measuring machine. A total of 80 sets, consisting of 1 framework and 1 flat specimen, were sent to 80 dental laboratory technicians for ceramic firing. Detailed instructions for correct manipulation of the framework and flat specimen were provided. The marginal gap was remeasured, and the 3-point bend test was used to evaluate metal-ceramic bond strength. RESULTS: Only 28 of the 80 dental technicians returned the specimens within a prespecified time and/or in adequate condition. The mean ±standard deviation marginal gap of the framework before ceramic firing was 25 ±9 µm and 34 ±12 µm after firing. The difference was statistically significant (P=.001). The mean ±standard deviation 3-point bend strength was 33 ±9 MPa. CONCLUSIONS: Ceramic firing affected the marginal gap; however, all Co-Cr frameworks had a marginal gap lower than 120 µm, which is reported to be a clinically acceptable limit. Most of the specimens (80%) had a metal-ceramic bond strength value higher than the 25-MPa ISO 9693 requirement. Five of 28 dental laboratory technicians were not able to comply with ceramic firing instructions.

Randomized Clinical Trial on Single Zirconia Crowns with Feather-Edge vs Chamfer Finish Lines: Four-Year Results.

The objective of this study was to evaluate the influence of two finish lines on the fracture resistance and periodontal response of porcelain zirconia crowns. Ethical committee approval was obtained, and 50 zirconia single crowns were placed in posterior regions. Abutments were randomly distributed into two groups: Group 1 (feather-edge preparation) and Group 2 (chamfer preparation). Patients were recalled after 1 month, 6 months, and 1, 2, 3, and 4 years. The function, esthetics, and marginal adaptation of the restorations were evaluated. Bleeding on probing (BoP) and distance of margins from the bone crest were recorded. Statistical analyses were performed for survival and success rates. Group 1 had an 80% success rate (21/25 crowns) and a 96% survival rate (24/25 crowns; 1 encountered irreparable fracture of ceramic layer); Group 2 had a 76% success rate (20/25 crowns) and a 100% survival rate (25/25 crowns). Chippings were noticed on 4 crowns in Group 1 (one crown replacement). Five chippings occurred in Group 2, without any replacement. There were no statistically significant differences between the two groups. BoP was found in 18 of the 25 crowns in Group 1 (72%) and in 12 of the 25 crowns in Group 2 (48%). A statistically significant correlation between BoP and the distance of the margin to the bone crest was found. It was concluded that: (1) clinical survival and success rates of the two preparation methods on crowns are not significantly different; (2) due to the statistically significant correlation between BoP and the distance of the margin to the bone crest, margins should be placed at least 3 mm from the bone crest; and (3) higher probability of BoP is expected in cases with feather-edge preparation.

Titanium and Zirconia External Connection Abutments Produced Following a Digital Protocol: An In Vitro Study.

PURPOSE: To assess the quality of precision at the implant-abutment interface of single-tooth restorations with titanium and zirconia abutments with hexagonal external connections produced using a digital protocol. MATERIALS AND METHODS: A total of 20 abutments were produced with commercially pure titanium, and 20 abutments with zirconia, both following a necessary digital protocol. Rotational freedom of all the abutments was assessed. All data were analyzed according to procedures established by software package STATA 14.2. RESULTS: No significant differences relative to rotational freedom emerged between the two groups. CONCLUSION: This study showed that both types of abutments constantly demonstrated approximately 2 degrees of rotational freedom between implant and abutment where the hexagonal external connection was concerned.

Full arch digital scanning systems performances for implant-supported fixed dental prostheses: a comparative study of 8 intraoral scanners.

PURPOSE: Compare the accuracy of intraoral digital impression in full-arch implant-supported fixed dental prosthesis acquired with eight different intraoral scanner (Ios). METHODS: A polymethyl methacrylate acrylic model of an edentulous mandible with six scan-abutment was used as a master model and its dimensions measured with a coordinate measuring machine. Eight different Ios were used to generate digital impression: True Definition, Trios, Cerec Omnicam, 3D progress, CS3500, CS3600, Planmeca Emelard and Dental Wings. Fifteen digital impressions were made. A software called "Scan-abut" was developed to analyse and compare the digital impression with the master model, obtaining the scanning accuracy. The three-dimensional (3D) position and distance analysis were performed. RESULTS: Mean value of the 3D position analysis showed that the True Definition (31 µm ± 8 µm) and Trios (32 µm ± 5 µm) have the best performance of the group. The Cerec Omnicam (71 µm ± 55 µm), CS3600 (61 µm ± 14 µm) have an average performance. The CS3500 (107 µm ± 28 µm) and Planmeca Emelard (101 µm ± 38 µm) present a middle-low performance, while the 3D progress (344 µm ± 121 µm) and Dental Wings (148 µm ± 64 µm) show the low performance. The 3D distance analysis showed a good linear relationship between the errors and scan-abutment distance only with the True Definition and CS3600. CONCLUSIONS: Not all scanners are suitable for digital impression in full-arch implant-supported fixed dental prosthesis and the weight of the output files is independent from the accuracy of the Ios.

Influence of Crown-to-Implant Ratio on Long-Term Marginal Bone Loss Around Short Implants.

PURPOSE: To evaluate the influence of the crown-to-implant ratio (CI) on marginal bone loss (MBL) around short dental implants placed in the posterior mandible. MATERIALS AND METHODS: All patients treated with short implants (7 mm length) in the posterior mandible between 1994 and 2003 at the Dental Clinic of the Department of Neuroscience of the University of Padua (Italy) were retrospectively included in the analysis. MBL and clinical CI (cCI) were measured on the radiographs. Implant characteristics including implant diameter, prosthetic type, retention mode, antagonist type, veneering material, and implant surfaces were retrieved from local medical records. A generalized linear mixed model was estimated to identify the predictors of MBL. RESULTS: A total of 108 dental implants placed in 51 patients were included in the analysis. Mean follow-up was 16 years (range: 11 to 20 years). Mean cCI was 2.21 (SD = 0.31) with a mean crown height of 10.86 mm (SD = 0.99). Mean MBL was 1.42 mm (SD = 0.38). At multivariable analysis, cCI ≥ 2 was associated with higher MBL (regression coefficient: 0.27; 95% CI: 0.15 to 0.40), while implant characteristics, follow-up, and site were not associated with MBL. The effect of a cCI ≥ 2 was estimated in an increase of 0.28 mm in MBL (95% CI: 0.14 to 0.43 mm). CONCLUSION: Higher cCI was associated with greater MBL of implant-supported fixed dental prostheses in short dental implants placed in the posterior mandible, while implant characteristics, follow-up, and site were not associated with MBL. However, the increase of 0.28 mm of MBL in patients with a cCI ≥ 2 may be not clinically relevant.

Digital vs Conventional Workflow for Screw-Retained Single-Implant Crowns: A Comparison of Key Considerations.

PURPOSE: To evaluate patient perception and operating time of digital (DW) and conventional (CW) workflows for the rehabilitation of a screw-retained, single-implant crown. MATERIALS AND METHODS: A convenience sample of 10 patients with single implants in posterior sites was recruited for treatment with screw-retained single crowns, fabricated with either a DW or a CW protocol. Operating time and clinical adjusting time were recorded with a stopwatch, and patient preference and self-perception of the esthetic outcome were evaluated with a visual analog scale. RESULTS: The mean operating time for the DW crowns was 16:21 minutes and for the CW crowns was 28:28 minutes. The mean total adjustment times were 118.1 seconds for the DW protocol and 181.5 seconds for the CW protocol. The mean score regarding self-perception of the esthetic outcome was 73 for DW crowns and 69 for CW crowns; for discomfort, the mean score was 15.5 for DW and 62 for CW. CONCLUSION: The DW approach resulted in a time reduction for both the impression phase and operative time.

An In Vitro Evaluation of Alumina, Zirconia, and Lithium Disilicate Surface Roughness Caused by Two Scaling Instruments.

PURPOSE: Plaque control is crucial for the prevention of inflammatory periodontal disease. Hand scaling instruments have been shown to be efficient for the removal of plaque; however, routine periodontal prophylactic procedures may modify the surface profile of restorative materials. The purpose of this study was to assess in vitro the changes in roughness of alumina, zirconia, and lithium disilicate surfaces treated by two hand scaling instruments. MATERIALS AND METHODS: Forty-eight alumina specimens, 48 zirconia specimens, and 48 lithium disilicate specimens, were selected. All specimens were divided into three groups of 16 each; one group for each material was considered the control group and no scaling procedures were performed; the second group of each material was exposed to scaling with steel curettes simulating standard clinical conditions; the third group of each material was exposed to scaling with titanium curettes. After scaling, the surface roughness of the specimens was evaluated with a profilometer. First, a statistical test was carried out to evaluate the difference in surface roughness before the scaling procedure of the three materials was effected (Kruskal-Wallis test). Subsequently, the effect of curette material (steel and titanium) on roughness difference and roughness ratio was analyzed throughout the entire sample and within each material group, and a nonparametric test for dependent values was conducted (Wilcoxon signed-rank test). Finally, the roughness ratios of the three material groups were compared by means of a Kruskal-Wallis test and a Wilcoxon signed-rank test. Upon completion of profilometric evaluation, representative specimens from each group were prepared for SEM evaluation to evaluate the effects of the two scaling systems on the different surfaces qualitatively. RESULTS: After scaling procedure, the roughness profile value increased in all disks. Classifying the full sample according to curette used, the roughness of the disks treated with a steel curette reached a higher median value than that of the titanium group. Zirconia demonstrated the least significant increase in surface roughness. The result was 3.9 times of the initial value as compared to 4.3 times for alumina and 4.6 times for lithium disilicate. CONCLUSIONS: Comparison of profilometer readings before and after instrumentation, carried out with different hand scaling instruments, highlighted both a statistically and clinically relevant increase in material roughness.

Internal- vs External-Connection Single Implants: A Retrospective Study in an Italian Population Treated by Certified Prosthodontists.

PURPOSE: The design of an implant connection that allows prosthetic suprastructures to be attached to implants has long been debated in the dental literature. The goal of this retrospective study was to evaluate the 5-year clinical results for a large number of single implants restored by certified prosthodontists in an attempt to establish whether different clinical outcomes could be detected for external- or internal-connection implants. MATERIALS AND METHODS: All single implants with internal or external connections inserted in 27 private dental practices from January 1, 2003 to December 31, 2007 were evaluated. An initial statistical analysis was performed to describe the sample population at baseline and then to compare the two types of implant-abutment connection configurations and their clinical outcomes. All data were statistically analyzed with STATA12 (StataCorp). RESULTS: Twenty-eight of the 85 active members of the Italian Academy of Prosthetic Dentistry (AIOP) participated in this study. The sample included 1,159 patients and 2,010 implants. Of the implants, 75 were dropped because there was no information about follow-up. Of the remaining implants, 1,431 (74.0%) were followed for at least 5 years, and 332 implants (17.2%) were followed for more than 8 years. Nearly 99% (98.9%) of the implants survived. The difference between the survival frequencies of the two types of implant-abutment connection configurations was not significant for each negative event (log-rank test, P > .05). There was no difference between the two types of implants regarding restoration fracture, implant screw loosening, and peri-implant disease. CONCLUSION: Within the limitations of this study, it can be suggested that there is no difference in clinical outcomes of single restorations joined to internal- or external-connection implants.

An In Vivo Evaluation of the Fit of Zirconium-Oxide Based, Ceramic Single Crowns with Vertical and Horizontal Finish Line Preparations.

PURPOSE: Different types of tooth preparations influence the marginal precision of zirconium-oxide based ceramic single crowns. In this in vivo study, the marginal fits of zirconium-oxide based ceramic single crowns with vertical and horizontal finish lines were compared. MATERIALS AND METHODS: Forty-six teeth were chosen in eight patients indicated for extraction for implant placement. CAD/CAM technology was used for the production of 46 zirconium-oxide-based ceramic single crowns: 23 teeth were prepared with vertical finishing lines, 23 with horizontal finishing lines. One operator accomplished all clinical procedures. The zirconia crowns were cemented with glass ionomer cement. The teeth were extracted 1 month later. Marginal gaps along vertical planes were measured for each crown, using a total of four landmarks for each tooth by means of a microscope at 50× magnification. On conclusion of microscopic assessment, ESEM evaluation was completed on all specimens. The comparison of the gap between the two types of preparation was performed with a nonparametric test (two-sample Wilcoxon rank-sum test) with a level of significance fixed at p < 0.05. All data were analyzed with STATA12. RESULTS: In the group with horizontal finish line preparations, the median value of the gap was 35.45 µm (Iqr, 0.33); for the vertical finish line group, the median value of the gap was 35.44 µm (Iqr, 0.40). The difference between the two groups was not statistically significant (two-sample Wilcoxon rank-sum test, p = 0.0872). CONCLUSIONS: Within the limitations of this study, the gaps of the zirconium-oxide-based ceramic CAD/CAM crowns with vertical and horizontal finish line preparations were not different.

Clinical evaluation of marginal bone level change around multiple adjacent implants restored with splinted and nonsplinted restorations: a 10-year randomized controlled trial.

PURPOSE: The management of occlusal forces on implant restorations may influence their long-term prosthetic success. The purpose of this randomized controlled trial was to compare marginal bone level changes around adjacent splinted and nonsplinted implants, functionally loaded with cemented restorations, up to 10 years in maxillae. MATERIALS AND METHODS: During 2002 and 2003, all patients who received three adjacent implants in a private office and a university setting were included in this study. All implants featured an external-hexagon design and were placed in the posterior maxilla. Implants in the left maxilla were randomly selected to be restored with splinted cemented restorations; maxillary right implants were restored with nonsplinted cemented restorations. Marginal bone resorption was measured with intraoral radiographs yearly over a period of at least 10 years after placement of abutments and restorations. The amount of bone loss in each group was analyzed with the two-sample Wilcoxon rank-sum (Mann-Whitney) test because variable bone loss was normally distributed at the fifth year only. RESULTS: One hundred thirty-two implants were placed in 44 patients. Three implants failed at stage-two surgery. Five years after initial loading, two patients moved away and were lost to follow-up (6 implants in total); three additional patients did not complete the study (9 implants in total). Of the remaining 114 implants, 60 left implants were restored with splinted cemented restorations and 54 right implants were restored with nonsplinted cemented restorations. At 10 years, the splinted group showed a mean of 1.2 mm (interquartile range: 0.2 mm) of bone loss; the nonsplinted group showed 1.3 mm (interquartile range: 0.2 mm). CONCLUSION: A significant difference in bone loss was seen between the two groups. However, the difference of 0.1 mm was not considered clinically meaningful.

An in vitro evaluation of impression techniques for multiple internal- and external-connection implant prostheses.

PURPOSE: This in vitro study evaluated the accuracy of three different impression techniques, using polyether impression material, to obtain a precise definitive cast for a multiple-unit implant restoration with internal- or external-connection implants. MATERIALS AND METHODS: Two reference resin models, one with four internal-connection implants (RRMI) and one with four external-connection implants (RRME), were fabricated. The longitudinal axes of all implants diverged by 15 to 20 degrees from the midline toward the labial/buccal. Six groups of 15 specimens each (45 RRMI, 45 RRME) were made with medium-consistency polyether: nonmodified square impression copings (NMIC and NMEC groups), square impression copings joined together with autopolymerizing acrylic resin before the impression procedure (RIC and REC groups), and square impression copings that were airborne particle-abraded and coated with impression adhesive (MIC and MEC groups). A single calibrated examiner evaluated the positional accuracy of the implant replica heads with a profile projector. These measurements were compared to the measurements calculated on the RRMI and RRME, which served as controls. All differences between the distances measured on the RRMI and on the RRME and those measured on the definitive casts of the six groups were transformed into the differences in microns each 1,000 µm of length (per mil difference) and statistically analyzed. RESULTS: Considering anterior and posterior per mil median differences together, the highest precision of the definitive casts was in the groups MEC, REC, and RIC. CONCLUSION: Within the limitations of this study, splinted square impression copings (RIC and REC) and airborne particle-abraded and coated (MIC and MEC) impression techniques showed greater accuracy in replicating the control models (RRMI and RRME) than the nonmodified technique (NMIC and NMEC). The definitive casts of the model with internal-connection implants achieved the highest precision with splinted square impression copings (RIC).

Bonding effectiveness of two adhesive luting cements to glass fiber posts: pull-out evaluation of three different post surface conditioning methods.

The purpose of this study was to evaluate the bond strength at the post/resin-cement interface with 3 different surface treatments of glass fiber posts and with 2 different luting resin cements. Sixty glass fiber posts (RelyX Fiber Post) were randomly divided into 3 groups (n = 20) and were luted with a dual-polymerizing self-adhesive universal resin cement (RelyX Unicem) and with a dual-polymerizing resin cement (RelyX ARC). This was carried out in association with a dual-polymerizing adhesive (Scotchbond Multi-Purpose Plus) in simulated plexiglass root canals after receiving three different pretreatment procedures. A pull-out test was performed on each sample to measure bond strengths. Data were analyzed with two-way ANOVA. Two samples from each group were processed for SEM observations in order to investigate the morphologic aspect of the post/cement interface. Both resin cements demonstrated significant different bond strength values (P < 0.0001). The surface treatment result was also statistically significant (P = 0.0465). SEM examination showed a modification of the post surface after pretreatment with methyl methacrylate. The dual-polymerizing self-adhesive universal resin cement achieved higher MPa bond strength values. The use of methyl methacrylate as a surface treatment of glass fiber posts provided a significant increase in bond strengths between the posts and both luting materials.

Prosthetic procedure for simultaneous immediate loading of opposing edentulous arches.

For patients with complete edentulism, a significant problem is the transfer of diagnostic data to the definitive casts when an immediate loading technique is used. This article presents a prosthetic procedure to allow simultaneous treatment of opposing edentulous arches with immediate implant loading. This technique uses 2 occlusal acrylic resin devices to transfer the diagnostic cast information to the definitive casts. Esthetic and functional fixed dental prostheses are fabricated from diagnostic information acquired in the presurgical phase without any impression or recording of the maxillomandibular relationship during or after surgery. This methodology is applicable when the simultaneous immediate loading of implants in 2 edentulous arches is indicated.

Aesthetic functional area protection concept for prevention of ceramic chipping with zirconia frameworks.

Chipping of the ceramic veneer is reported as a frequent occurrence when using zirconia-based fixed dental prostheses (FDPs). One possible cause of this complication is the inadequate support of the veneering ceramic by the zirconia substructure. In this article, early clinical observations from patients treated with 96 zirconia-based ceramic single- and multiple-unit FDPs on natural teeth and implants are presented. The FDPs were fabricated according to the aesthetic functional area protection concept of framework design for the prevention of ceramic chipping.

Effect of aging and porcelain sintering on rotational freedom of internal-hex one-piece zirconia abutments.

PURPOSE: The purpose of this study was to assess the variation of rotational freedom at the implant interface of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramic abutments with internal-hexagon connections before and after artificial aging and after porcelain sintering. MATERIALS AND METHODS: Thirty Y-TZP ceramic abutments with internal-hex connections were used in this study. Three groups of 10 abutments each were created. Group C was made up of abutments in the as-received condition, group A abutments went through 1 hour of autoclaving at 134°C to simulate the effect of 3 to 4 years of aging in vivo, and group P abutments went through porcelain sintering procedures. Measurements of rotational freedom were compared between groups. The quantitative differences between groups were assessed using multivariate analysis of variance. Statistical testing was carried out at the 5% significance level. RESULTS: A mean rotational freedom of 115.34 ± 1.42 minutes was found for group C abutments; the values for group A and group P abutments were 115.35 ± 1.73 minutes and 115.37 ± 1.54 minutes, respectively. None of these differences were statistically significant between the three groups. CONCLUSION: Misfit of the Y-TZP ceramic abutment on the internal-hex connection of implants may be implicated in screw joint loosening. The results of this report suggested that, if all laboratory steps are followed carefully, changes will not occur at the implant/Y-TZP ceramic abutment interface. Maintenance of the original features of the abutment may reduce the risk of screw loosening.

An in vivo evaluation of fit of zirconium-oxide based ceramic single crowns, generated with two CAD/CAM systems, in comparison to metal ceramic single crowns.

PURPOSE: The purpose of this study was to assess in vivo the marginal fit of single crowns produced using two CAD/CAM all-ceramic systems, in comparison to more traditional metal ceramic crowns. MATERIALS AND METHODS: Thirty vital, caries-free, and previously untreated teeth were chosen in five patients who needed extraction for implant placement and therefore were included in this study. In the control group (C), 10 regular metal ceramic crowns with porcelain occlusal surfaces were fabricated. In the other two groups (Z and E), CAD/CAM technology was used for the fabrication of 20 zirconium-oxide-based ceramic single crowns with two systems. All zirconia crowns were cemented with glass-ionomer cement, always following the manufacturer's instructions. The same dentist carried out all clinical phases. The teeth were extracted 1 month later. Marginal gaps along vertical planes were measured for each crown, using a total of four landmarks for each tooth by means of a microscope at a magnification of 50×. On completion of microscopic evaluation, representative specimens from each group were prepared for ESEM evaluation. Mean and standard deviations of the four landmarks (mesial, distal, buccal, palatal) at each single crown were calculated for each group. Multivariate analysis of variance (MANOVA) was performed to determine whether the four landmarks, taken into consideration together, differed between groups. Two-way ANOVA was performed to study in detail, for each landmark, how the three systems used to produce the FPDs affected the gap measurements. Differences were considered to be significant at p < 0.05. RESULTS: MANOVA revealed no quantitative differences of the four landmarks, when taken into consideration together, between the three groups (p < 0.0001). Two-way ANOVA, performed at each landmark, revealed no quantitative differences between the three groups (p < 0.0001 for each landmark). CONCLUSIONS: Within the limitations of this study, it was concluded that the two zirconium-oxide-based ceramic CAD/CAM systems demonstrated a similar and acceptable marginal fit when compared to more traditional metal ceramic crowns.

Internal vs. external connections for abutments/reconstructions: a systematic review.

OBJECTIVES: The objectives of the review were (1) to evaluate the accuracy of implant-level impressions in cases with internal and external connection abutments/reconstructions, and (2) to evaluate the incidence of technical complications of internal and external connection metal- or zirconia-based abutments and single-implant reconstructions. MATERIALS AND METHODS: A MEDLINE electronic search was conducted to identify English language publications in dental journals related to each of the two topics by inserting the appropriate keywords. These electronic searches were complemented by a hand search of the January 2009 to January 2012 issues of the following journals: Clinical Oral Implants Research, The Journal of Prosthetic Dentistry, The International Journal of Prosthodontics, The International Journal of Periodontics and Restorative Dentistry, The International Journal of Oral Maxillofacial Implants, Clinical Implant Dentistry and Related Research. RESULTS: Seven in vitro studies were included in the review to evaluate the accuracy of implant-level accuracy. No clinical study was found. There was no study that directly compared the influence of internal and external implant connections for abutments/reconstructions on the accuracy of implant-level impressions. All in vitro studies reported separately on the two connection designs and they did not use same protocol and, therefore, the data could not be compared. Fourteen clinical studies on metal-based abutments/reconstructions and five clinical studies on zirconia-based abutments/reconstructions satisfied the inclusion criteria and, therefore, were included in the review to evaluate the incidence of technical complications. The most frequent mechanical complication found in both implant connection design when employing metal abutments/reconstructions was screw loosening. CONCLUSIONS: Implant-level impression accuracy may be influenced by a number of variables (implant connection type, connection design, disparallelism between multiple implants, impression material and technique employed). Implant divergence appears to affect negatively impression accuracy when using internal connection implants. Based on the sparse literature evaluating the incidence of technical complications of metal or zirconia abutments/reconstructions, it was concluded that: The incidence of fracture of metal-based and zirconia-based abutments and that of abutment screws does not seem to be influenced by the type of connection. Loosening of abutment screws was the most frequently occurring technical complication. The type of connection seems to have an influence on the incidence of the screw loosening: more loose screws were reported for externally connected implant systems for both types of materials. However, proper preload may decrease the incidence of such a complication.

Replacement of a hopeless maxillary central incisor: a technique for the fabrication of an immediate implant-supported interim restoration.

Placement of a dental implant and an interim restoration in the esthetic zone immediately following tooth extraction is now a common procedure. However, in such clinical situations, the fabrication of an appropriate interim restoration may be challenging. The aim of this article is to present a technique for modifying the extracted tooth so it can be used as an implant-supported interim restoration.