Implantoplasty: Carbide burs vs diamond sonic tips. An in vitro study.

OBJECTIVES: Implantoplasty (IP) is a treatment option for peri-implantitis. Mechanical concerns were raised on fracture resistance of implants subjected to this procedure. This study aimed to compare two methods of IP in terms of implant wear and fracture resistance, and of surface topography. MATERIAL AND METHODS: Eighteen cylindrical screw-shaped dental implants (4 mm diameter, 13 mm length) with an external hexagonal connection were used. IP was performed on the first 6-mm implant surface with a sequence of burs or diamond sonic tips, both followed by an Arkansas finishing. IP duration and implant weight variation were recorded. Micro-computed tomography (micro-CT) was used to evaluate material loss. Implant fracture resistance was assessed by static compression test. Surface topography analysis was performed with a stylus profilometer. Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) was applied for implant surface morphology and elemental characterization. RESULTS: Micro-CT showed less material loss in sonic compared to burs. No statistically significant difference was found between the mean fracture resistance values reached in bur and sonic, both followed by Arkansas, and with respect to control. IP performed with burs led to a smoother surface compared to sonic. Equivalent final surface roughness was found after Arkansas in both IP procedures. SEM-EDS showed a deburring effect associated to sonic and revealed carbon and aluminum peaks attributable to contamination with sonic diamond tips and Arkansas bur, respectively. CONCLUSIONS: IP with sonic diamond tips was found to be more conservative in terms of structure loss. This could have a clinical relevance in case of narrow-diameter implants.

Investigation of the Accuracy of Four Intraoral Scanners in Mandibular Full-Arch Digital Implant Impression: A Comparative In Vitro Study.

Background: We compare the accuracy of new intraoral scanners (IOSs) in full-arch digital implant impressions. Methods: A master model with six scan bodies was milled in poly(methyl methacrylate), measured by using a coordinate measuring machine, and scanned 15 times with four IOSs: PrimeScan, Medit i500, Vatech EZ scan, and iTero. The software was developed to identify the position points on each scan body. The 3D position and distance analysis were performed. Results: The average and ± standard deviation of the 3D position analysis was 29 µm ± 6 µm for PrimeScan, 39 µm ± 6 µm for iTero, 48 µm ± 18 µm for Mediti500, and 118 µm ± 24 µm for Vatech EZ scan (p < 0.05). Conclusions: All IOSs are able to make a digital complete implant impression in vitro according to the average misfit value reported in literature (150 µm); however, the 3D distance analysis showed that only the Primescan and iTero presented negligible systematic error sources.

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.

Shear bond strength between feldspathic CAD/CAM ceramic and human dentine for two adhesive cements.

PURPOSE: The purpose of this study was to evaluate the shear bond strength values between dentin substrate and a feldspathic ceramic material, based on computer-assisted design and manufacture (CAD/CAM) technology, bonded together with two adhesive systems coupled with two dual-polymerized luting agents. In addition, the effect of a silane coupling agent on bond strength was evaluated. MATERIAL AND METHODS: Forty cylinders (6 mm in diameter, 5 mm thick) obtained from feldspathic ceramic blocks were cemented to the dentin of 40 recently extracted human teeth stored in saline solution at room temperature until testing. The specimens were randomly divided into four groups of ten teeth each. All specimens were airborne-particle abraded and etched with hydrofluoric acid. In the first two groups (A1, A2) 20 ceramic cylinders were cemented using Excite DSC and Variolink II; in the A2 group the bonding surfaces were also treated with a silane coupling agent. In Groups B1 and B2, 20 ceramic cylinders were cemented using Scotchbond MPP and RelyX ARC; in the B2 group the bonding surfaces were also treated with a silane coupling agent as in Group A2. All cemented specimens were submitted to a shear bond strength test to check the strength of adhesion between the two substrates, dentin and ceramic. The data were analyzed with two-way analysis of variance (p < 0.05). RESULTS: The mean values of the shear bond strength were (in MPa): 22 +/- 7 for Excite DSC/Variolink II without silanization (Group A1); 29 +/- 3 for Excite DSC/Variolink II with silanization (Group A2); 22 +/- 4 for Scotchbond MPP/RelyX ARC without silanization (Group B1); and 26 +/- 5 for Scotchbond MPP/RelyX ARC with silanization (Group B2). Two-way ANOVA revealed a significant effect of silanization (p < 0.01) and did not reveal any significant effect for either the bonding agents (p > 0.1) or the interaction between silanization and bonding agent (p > 0.05). Multinomial logit model did not show any statistical effects on the failure mode by the shear bond strength (p > 0.1). The hypotheses of independence between failure mode (cohesive vs. adhesive) and both the adhesive system (p < 0.05) and silanization (p < 0.05) were rejected by Pearson's chi-square test. CONCLUSION: Within the assumptions and limitations of this study (including the small number of specimens) both bonding systems used achieved good shear bond strength values. The application of a silane coupling agent on the ceramic surface after etching with hydrofluoric acid increased the adhesion strength with both adhesive materials used.

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.

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.

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.

Porcelain inlays cemented with composite resin cement: an in vivo investigation of pulpal reaction one year following cementation.

PURPOSE: This in vivo study was designed to verify the presence of pulpal inflammation on teeth after 1 year of function from cementation of porcelain inlays. MATERIALS AND METHODS: Thirty-two vital, healthy, caries-free and previously untreated maxillary and mandibular first premolars in eight patients needing extraction for orthodontic reasons were included in this study. For each patient three first premolars were randomly chosen and treated with porcelain MOD inlays. One first premolar served as the control group with no restorations. The porcelain inlays were cemented with dental adhesive and composite resin cement without pulpal protection. The same dentist, following standardized preparation, impression, and cementation techniques, accomplished all clinical phases. The teeth were extracted 1 year later. The condition of the pulp tissues of the 24 teeth with porcelain inlays was compared with the pulpal tissues of the eight teeth of the control group. The data relating to the number of inflammatory cells were evaluated by one-way analysis of variance to assess quantitative differences between the group of teeth with porcelain inlays and the group without porcelain inlays (p < 0.05). Means and standard deviations were calculated for each group. RESULTS: The microscopic analysis revealed the absence of pulpal inflammation of the teeth with porcelain inlays when compared with the teeth of the control group. The analysis of variance revealed no statistical differences between the two groups compared. CONCLUSION: Within the limitations of this study, the cementation of porcelain inlays with dental adhesive and composite cement on healthy premolars did not result in any inflammatory reaction of the pulpal tissues 1 year after placement.