Surface microstructure of dental implants before and after insertion: an in vitro study by means of scanning probe microscopy.

INTRODUCTION: The surface microstructure of dental implants affects osseointegration, which makes their accurate topographic characterization important. We defined a procedure for evaluation of implant topography before (pre-) and after (post-) in vitro implantation test in bovine bone. MATERIALS AND METHODS: The apical morphology of ten implants was analyzed in pre- and post-conditions using atomic force microscopy or 3D profilometry. We extracted four topographical parameters (two amplitude, 1 spatial, and 1 hybrid) and assessed the differences by analysis of variance. RESULTS AND DISCUSSION: The implant with coating (Spline Twist MP-1 HA) was damaged. The two implants with highest pre-amplitude parameters (Pitt Easy VTPS, TLR3815) maintained their character on testing. Pitt Easy PURETEX and OT-F1 were the only nondamaged implants whose amplitude parameters increased. The surface area underwent minor changes even when the texture changed (Tri-Vent, Pitt Easy PURETEX, Exp #1). The implants that ranked the lowest in all parameters before implantation were DT4013TI, Tri-Vent, OT-F1, and Exp #2. On testing, DT4013TI showed the highest decrease in values, whereas Tri-Vent showed the highest increase in surface area. All the experimental implants showed similar topographic properties both pre- and post-test. CONCLUSION: For most implants, no major changes occurred in surface topography on implantation. The procedure applied seems promising to evaluate the degradation of implant surface on insertion.

3D optical profilometer analysis of the marginal gap of Class II restorations made with different materials for vital pulp therapy procedures.

We considered Class II dental cavities in critical tooth areas concerned with vital pulp therapy, and evaluated the marginal gap after treatment with Biodentine and Geristore, and one composite after either etching and adhesive (V2) and after use of a self-etching system (iBond Universal). We measured the surface morphology at the marginal gap by optical profilometry, and carried out analysis of the 3D data according to a new effective definition of marginal gap. The defined quantity was assessed for statistical significance of the apparent differences. The largest gaps appeared for Geristore (first) and Biodentine (not significantly lower), whereas the gaps of the composite controls were both lower, the lowest being the two-step self-etched system with respect to the three-steps etched and adhesive system, yet without statistical significance. Obviously, there is still room for improvement of the vital pulp therapy restorative materials, as compared to the use of standard composite systems.

Hydro air abrasion on dental glass-ceramics: A direct 3D analysis by stylus profilometry.

Air abrasion is used in dentistry for cavity opening, post-endodontic cavity cleaning, and removal of hard deposits or stains. Different applications may require different settings. We aimed to gain better understanding of the effect of some operating parameters on the efficiency of air abrasion on a model dental material. We abraded lithium disilicate glass-ceramic blocks (IPS e.max CAD, Ivoclar Vivadent) with Prepstart H2O device (Danville) and 27-µm-size aluminium oxide abrasive (Danville). At 5 bar constant pressure, we varied incidence direction, treatment time, distance, powder consumption, and supporting medium, in separate experiments addressing individual aspects. The abraded surfaces were characterized by stylus profilometer XP-2 (Ambios). Laboratory condition of normal incidence at fixed direction showed threefold increased volume abrasion vs 45° incidence and oscillating direction. Working in air, 2 mm distance was more efficient than 1 and 5 mm, likely due to its influence on the abrading particles speed. Maximum vs medium powder consumption decreased the abraded volume, while increasing the treated area. Using water restricted the treated surface. To minimize the risk of dental material damage, the best conditions should be 45° direction and 5 mm distance, which both increase the treated area. To counteract this, water may be used. The most abrasive condition is instead 90°, at intermediate 2 mm distance. In most cases, abraded volume scales linearly with time. The present combination of device and abrasive can be effective even on enamel-like ceramic material. Tuning air abrasion settings to the specific dental application appears to be necessary.

Immediate Loading of Implant-Supported Single Crowns after Conventional and Ultrasonic Implant Site Preparation: A Multicenter Randomized Controlled Clinical Trial.

AIM: To compare implant survival rate and marginal bone loss (MBL) of immediately loaded single implants inserted by using ultrasonic implant site preparation (UISP) (test) and conventional rotary instrumentation (control). METHODS: Two single implants were inserted for each patient: after randomization, test site was prepared by using an ultrasonic device (Piezosurgery Touch, Mectron, Italy) and control site was prepared by using the drills of the selected implant system (Premium AZT, Sweden & Martina, Italy), until reaching a final diameter of 3 mm in both groups. Identical implants (3.8x11.5 mm) were inserted in all sites at crestal level. Impressions were taken and screwed resin single crowns with platform-switched provisional abutments were delivered with 48 hours. Periapical radiographs were taken at provisional crown insertion (T0), 6 months (T1) and one year (T2) after prosthetic loading to measure MBL. All data were tested for normality and subsequently analyzed by paired samples t-test and forward multiple linear regression. RESULTS: Forty-eight patients were treated in six centers with the insertion of ninety-six implants (48 test; 48 control). Four implants in four patients failed within the first six months of healing (two in test group; two in control group; no difference between groups). Forty patients (age 60.1±10.7 years; 22 female, 18 male) were included in the final analysis. Mean MBL after six months of loading was 1.39±1.03 mm in the test group and 1.42±1.16 mm in the control group (p>0.05) and after one year was 1.92±1.14 mm and 2.14±1.55 mm in test and control, respectively (p>0.05). CONCLUSIONS: No differences in survival rate and MBL were demonstrated between UISP and conventional site preparation with rotary instruments in immediately loaded dental implants: UISP, with its characteristics of enhanced surgical control and safety in proximity of delicate structures, may be used as a reliable alternative to the traditional drilling systems.

Microstructure of titanium-cement-lithium disilicate interface in CAD-CAM dental implant crowns: a three-dimensional profilometric analysis.

BACKGROUND: Peri-implantitis is an infection of the implant surface caused by adhesion of bacteria that generate bone resorption and sometimes even consequent implant loss. Both screw-retained and cemented fixed implants are affected. PURPOSE: The purpose of this study is to investigate the morphological defects at the cemented interface between titanium abutment and ceramic crown, comparing different adhesive cements used to fill the marginal gap. MATERIALS AND METHODS: Twelve computer-aided design-computer-aided manufacturing dental crowns were cemented to titanium abutments using three different resin composite cements. Sealed margins were polished using grommets with descending diamond particle size. Three groups of four crowns each were made according to the cement used, namely RelyX Unicem (3 M ESPE), Panavia F 2.0 (Kuraray), and NX3 (Nexus Kerr). Samples were analyzed using optical inspection, three-dimensional profilometry, and image analysis, including analysis of variance. RESULTS: Although RelyX showed significantly lower root mean square surface roughness (4.4 ± 1.5 µm) than that of NX3 (7.0 ± 2.9 µm), it showed no significant difference with Panavia (3.7 ± 1.5 µm). The marginal gap was significantly wider in Panavia (149 ± 108 µm) as compared with NX3 (71 ± 45 µm) and Relyx (64 ± 34 µm). For all groups, homogeneous heights of both metal-cement and ceramic-cement gaps were observed. Moreover, all samples showed homogeneity of the margins and absence of instrumental bias, thus validating both procedure and materials. CONCLUSIONS: When using the chosen polishing method, RelyX Unicem showed both low roughness and marginal width, and thus the smoothest and more continuous abutment-crown interlayer, promising a low probability of occurrence of peri-implantitis.